JP4675767B2 - Liquid crystal display device - Google Patents

Description

  The present invention relates to a liquid crystal display device having a polarizing element and a quarter-wave layer.

  For example, a liquid crystal display device used as a display screen of a notebook computer or a word processor has a narrower viewing angle than a display device such as a CRT because of the optical anisotropy of the liquid crystal. The quality tends to decline. Therefore, for example, in a liquid crystal display device 501 described in Patent Document 1 described later, as shown in FIG. 42, a liquid crystal cell 511 and a liquid crystal cell 511 are disposed adjacent to each other in order to enlarge the viewing angle. A liquid crystal compensator 514 that optically compensates for the cell 511, λ / 4 plates 513c and 513d disposed so as to sandwich the liquid crystal cell 511 and the liquid crystal compensator 514, and both λ / 4 plates 513c and 513d are disposed. The linearly polarizing films 512a and 512b are provided. Each of the λ / 4 plates 513c and 513d has an in-plane retardation set to one quarter of the transmitted light, and the λ / 4 plate 513c is made of a uniaxial material having negative optical activity. The λ / 4 plate 513d is made of a uniaxial material having positive optical activity.

  In the above configuration, the light transmitted through the linearly polarizing film 512a is converted into circularly polarized light by the λ / 4 plate 513c and then incident on the liquid crystal cell 511 through the liquid crystal compensator 514. Here, in a state where no electric charge is applied, the nematic liquid crystal of the liquid crystal cell 511 is arranged substantially perpendicular to the substrate, so that the emitted light of the liquid crystal cell 511 is in a circularly polarized state substantially the same as the incident light, and λ / It is converted into linearly polarized light by the four plates 513d. Here, since the both linearly polarizing films 512a and 512b are arranged so that the absorption axes thereof are orthogonal to each other, the linearly polarized light is absorbed by the linearly polarizing film 512b and becomes black display. Further, since the liquid crystal compensator 514 has optical activity opposite to that of the liquid crystal cell 511, even when the liquid crystal cell 511 gives a phase difference to transmitted light inclined from the substrate normal direction during black display, the liquid crystal compensation is performed. The plate 514 can cancel the phase difference, and the viewing angle can be enlarged.

On the other hand, when a charge is applied, the liquid crystal molecules are inclined in the horizontal direction with respect to the substrate, and the light emitted from the liquid crystal cell 511 becomes elliptically polarized light. Therefore, the light emitted from the λ / 4 plate 513d is not completely absorbed by the linearly polarizing film 512b and white display is performed.
JP 5-113561 A (published May 7, 1993)

  However, in the above configuration, both the λ / 4 plates 513c and 513d have different optical activities, and therefore need to be manufactured in separate manufacturing processes, and it is difficult to match the in-plane retardation of both. This causes a problem.

  Here, if the in-plane retardation is different due to manufacturing variations that are independent of each other in each manufacturing process, light leakage occurs in the front direction during black display, and the contrast ratio in the front direction decreases. .

  In the above configuration, when the contrast ratio at a predetermined angle from the normal direction is measured over all in-plane directions, the peak value of the contrast ratio is likely to vary, and it is difficult to balance the viewing angle characteristics of the upper, lower, left, and right.

  The present invention has been made in view of the above problems, and its purpose is to maintain a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left and right, and to reduce the contrast ratio in the front direction. The object is to realize a liquid crystal display device that can be prevented.

  The liquid crystal display device according to the present invention is a liquid crystal display device having a vertical alignment mode liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell. And a quarter-wave layer in which the retardation in the in-plane direction is set to approximately a quarter wavelength of the wavelength of transmitted light, and at least the quarter-wave layer One of the phase difference layers disposed between the liquid crystal cell and the liquid crystal cell, where the main refractive index in the in-plane direction is nx1, ny1, and the main refractive index in the normal direction is nz1, and at least the above-mentioned retardation layer When the main refractive index in the in-plane direction is nx2, ny2, and the main refractive index in the normal direction is nz2, provided between the quarter wavelength layer on which the phase difference layer is provided and the polarizing element. With a compensation layer having the largest rate nz2 It is characterized by a door.

  Furthermore, a liquid crystal display device according to the present invention is a liquid crystal display device in a horizontal alignment mode having a liquid crystal cell containing a liquid crystal with positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell, In order to solve the above-mentioned problems, a quarter wavelength is arranged between each of the polarizing elements and the liquid crystal cell, and the retardation in the in-plane direction is set to approximately a quarter wavelength of the wavelength of the transmitted light. A positive uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell, and at least one of the quarter-wave layers and the liquid crystal cell. A negative uniaxial retardation layer, and at least one of the above-mentioned retardation layers is provided between the quarter wavelength layer and the polarizing element, and the main refractive index in the in-plane direction is nx2, ny2, when the main refractive index in the normal direction is nz2, It is characterized in that the rate nz2 is a largest compensation layer. Instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, An inclined retardation layer may be provided in which the na axis coincides with the in-plane rubbing orthogonal direction and the nc axis is inclined at a predetermined angle from the normal direction.

  The liquid crystal display device according to the present invention is an optically compensated bend mode liquid crystal display device including a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell. In order to solve the above-described problem, the quarter is arranged between each of the polarizing elements and the liquid crystal cell, and the retardation in the in-plane direction is set to approximately one-fourth of the wavelength of the transmitted light. Nx1 when the main refractive index in the in-plane direction is nx1, ny1 and the main refractive index in the normal direction is nz1, which is arranged between the one wavelength layer and at least one of the quarter wavelength layers and the liquid crystal cell. > Ny1> nz1 is provided between the retardation layer and at least the quarter wavelength layer on which the retardation layer is provided and the polarizing element, and the main refractive index in the in-plane direction is nx2, ny2, normal When the main refractive index in the direction is nz2, the main refractive index z2 is characterized in that has a largest compensation layer. Instead of the retardation layer, the original refractive index ellipsoid is na = nb> nc and the na axis is in-plane rubbing between at least one of the quarter-wave layers and the liquid crystal cell. An inclined retardation layer may be provided that is aligned with the orthogonal direction and inclined so that the nc axis forms a predetermined angle from the normal direction.

  According to these configurations, since light that has passed through the polarizing element and the quarter-wave layer is incident on the liquid crystal cell, substantially circular polarized light is incident on the liquid crystal cell, and light emitted from the liquid crystal cell is divided into four minutes. After a phase difference of approximately a quarter wavelength is given by the one wavelength layer, the light is emitted through the polarizing element.

  Here, when the voltage between the pixel electrode and the counter electrode is a predetermined voltage, such as an initial alignment state when a voltage is applied or no voltage is applied, the liquid crystal cell corresponds to the alignment state of the liquid crystal molecules. Since the phase difference is given to the transmitted light, the circularly polarized light is converted into elliptically polarized light. Therefore, even if it passes through the quarter wavelength layer, it does not return to linearly polarized light, and a part of the emitted light of the quarter wavelength layer is emitted from the polarizing element. As a result, the amount of light emitted from the polarizing element can be controlled according to the applied voltage, and gradation display is possible.

  Furthermore, since substantially circularly polarized light is incident, even if alignment disorder occurs in the liquid crystal molecules, the alignment direction of the liquid crystal molecules and the transmitted light do not match in both the in-plane component and the substrate normal direction. As long as the liquid crystal molecules can give a phase difference to the transmitted light, high light utilization efficiency can be secured.

  On the other hand, when the liquid crystal molecules of the liquid crystal cell are aligned in the substrate normal direction (vertical), the liquid crystal cell cannot give a phase difference to the transmitted light. As a result, the transmitted light is emitted while maintaining substantially circularly polarized light. The emitted light is converted into linearly polarized light in the quarter wavelength layer, and then input to the polarizing element to limit transmission. Therefore, the liquid crystal display device can display black.

  However, even if the liquid crystal molecules are aligned vertically, when viewed from an oblique direction inclined by a polar angle from the substrate normal direction, the alignment direction of the liquid crystal molecules and the direction of transmitted light do not match, and the liquid crystal cell is A phase difference corresponding to the polar angle is given to the transmitted light. However, in each of the above configurations, a retardation layer having retardation in the thickness direction is provided, and the liquid crystal cell can be optically compensated. Therefore, a wide viewing angle can be maintained.

  Further, in the above configuration, a compensation layer having a retardation in the thickness direction opposite to that of the quarter wavelength layer or the retardation layer is disposed between the polarizing element and the quarter wavelength layer. Yes. Therefore, for example, a member that functions in the same optical activity as the retardation layer, such as a support for the polarizing element, is interposed between the polarizing element and the quarter-wave layer, or a quarter-wave layer is provided. Even if it has retardation in the thickness direction, the retardation of these members can be canceled by the compensation layer.

  As a result, even if the total retardation in the thickness direction from the polarizing element to the liquid crystal cell and from the liquid crystal cell to the polarizing element is the same, Since the absolute value of the retardation in the thickness direction in the range up to 1 / wavelength layer can be reduced, the compensation retardation (thickness direction) of the liquid crystal cell is made closer to the liquid crystal cell than in the case without the compensation layer. be able to. Therefore, light leakage during black display can be prevented and good black display can be achieved. In addition, unlike the case of using a quarter-wave layer having positive and negative optical activities, the same type of quarter-wave layer can be used, so that both in-plane retardation can be easily aligned. The contrast ratio in the front direction can be improved.

  In addition, since the retardation (absolute value) in the thickness direction within the above range can be reduced, when the contrast ratio at a predetermined angle from the normal direction is measured over all in-plane directions, the peak value of the contrast ratio is the same value. It is easy to balance the viewing angle characteristics of the top, bottom, left and right.

  In addition, in the case of these configurations, a quarter-wave layer is created with a retardation film represented by a biaxial refractive index ellipsoid, and the characteristics of the negative film are added to the quarter-wave layer. The quarter wavelength layer can also be used as a negative film. Even in this case, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to that of the liquid crystal cell, so that a good black display can be achieved.

  Furthermore, in the case of the configuration in which the compensation layer having the largest main refractive index nz2 is provided, there is at least an in-plane direction between the quarter-wave layer and the polarizing element on which the retardation layer is provided. When the main refractive index is nx3, ny3, and the main refractive index in the normal direction is nz3, nx3> ny3, and the polarizing axis on the same side with respect to the liquid crystal cell is parallel to the ny3 axis. It is desirable to provide a polarizing element compensation layer set as described above.

  According to this configuration, the polarizing element can be optically compensated by the polarizing element compensation layer. For example, when the absorption axis of the polarizing element and the y axis of the polarizing element compensation layer are arranged in parallel, the liquid crystal display device having the polarizing elements whose absorption axes are orthogonal to each other is inclined from the in-plane orientation of 45 degrees of the absorption axis. Light leakage when seen can be suppressed. Furthermore, since the retardation in the thickness direction of the polarizing element compensation layer can be canceled by the compensation layer, the retardation for compensation of the liquid crystal cell (thickness direction) is provided despite the provision of the polarizing element compensation layer. ) Can be brought closer to the liquid crystal cell. As a result, in all in-plane directions, light leakage during black display can be prevented, and a liquid crystal display device capable of displaying black well can be realized.

  In the case of a configuration in which a compensation layer having the largest main refractive index nz2 is provided, it is desirable that each main refractive index of the compensation layer is set to nx2 = ny2 <nz2. According to this configuration, since the retardation in the in-plane direction of the compensation layer is 0 nm, the coloring phenomenon that occurs when the in-plane retardation exists can be prevented and the contrast ratio can be maintained at a high value.

  Further, when the main refractive index in the in-plane direction is set to nx4, ny4 and the main refractive index in the normal direction is set to nz4 as the quarter wavelength layer instead of providing the compensation layer having the above-described configuration, (nx4 + ny4) A quarter wavelength layer with / 2 being approximately nz4 may be used.

  In this configuration, retardation in the thickness direction of the quarter wavelength layer is suppressed to substantially zero. Therefore, similarly to each liquid crystal display device described above, even if the total retardation in the thickness direction from the polarizing element to the liquid crystal cell and from the liquid crystal cell to the polarizing element is the same, The retardation of the thickness direction from the said polarizing element to a quarter wavelength layer can be reduced including a layer. Thereby, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell. As a result, a liquid crystal display device capable of maintaining a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, and preventing a decrease in the contrast ratio in the front direction, as in the case where the compensation layer is provided. realizable.

  Further, regardless of whether (nx4 + ny4) / 2 of the quarter-wave layer is set to nz4 or not and whether or not the compensation layer is present, the quarter-wave layer including the quarter-wave layer is four minutes from the polarizing element. The absolute value of the retardation in the thickness direction in the range up to one wavelength layer may be set to less than 1/8 of the wavelength of the transmitted light.

  Even in this configuration, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell as in the above-described liquid crystal display devices. Therefore, similarly to the liquid crystal display devices described above, it is possible to realize a liquid crystal display device that can maintain a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, and can prevent a decrease in the contrast ratio in the front direction.

  Furthermore, it is desirable that the absolute value of the retardation in the thickness direction in the above range is set to substantially zero. According to this configuration, the retardation in the thickness direction effective for optically compensating the liquid crystal cell can be brought closest to the liquid crystal cell, and the display quality of the liquid crystal display device can be improved.

  In addition to the above-described configurations, the liquid crystal cell includes a first substrate provided with a pixel electrode corresponding to a pixel, a second substrate provided with a counter electrode, and a liquid crystal layer provided between the two substrates. And the liquid crystal layer is controlled so that the alignment directions of the liquid crystal molecules are different from each other in the pixel when the voltage between the pixel electrode and the counter electrode is at least a predetermined value. desirable.

  In the above configuration, since the alignment directions of the liquid crystal molecules are different from each other in the pixel, regions where liquid crystal molecules having different alignment directions are present can optically compensate for each other. As a result, the display quality when viewed from an oblique direction can be improved and the viewing angle can be expanded.

  Here, in the liquid crystal layer, as a result of controlling the alignment directions of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, disorder of the alignment state is likely to occur. Therefore, in the case of a conventional liquid crystal display device in which linearly polarized light is incident on the liquid crystal layer and light emitted from the liquid crystal layer is incident on the analyzer, the alignment of the liquid crystal molecules is disturbed, and the in-plane component in the alignment direction is reduced. If it coincides with the absorption axis of the polarizing element, the liquid crystal molecules cannot give a phase difference to the transmitted light regardless of the component in the normal direction of the substrate. Therefore, the region where the liquid crystal molecules are present cannot contribute to the improvement of brightness, and roughness or the like occurs. In addition, since the liquid crystal molecules whose in-plane components in the alignment direction coincide with the absorption axis of the analyzer cannot contribute to the improvement in brightness, the light utilization efficiency (effective aperture ratio) decreases. As a result, it is difficult to ensure the contrast ratio and increase the number of gradations.

  On the other hand, in the liquid crystal display device configured as described above, since substantially circularly polarized light is incident on the liquid crystal layer, there is no anisotropy in the alignment direction of the liquid crystal layer, and the alignment direction of the liquid crystal molecules and the transmitted light are As long as both the inner component and the substrate normal direction do not match, the liquid crystal molecules can give a phase difference to the transmitted light.

  Therefore, as a result of controlling the alignment direction of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, the alignment direction of the liquid crystal molecules whose alignment is disturbed despite the fact that the alignment state is likely to be disturbed. As long as it does not match, it can contribute to the improvement of brightness. As a result, high light utilization efficiency can be secured while maintaining a wide viewing angle.

  In addition to the above-described configurations, the main refractive indexes nx1 and ny1 of the retardation layer are preferably set to nx1 = ny1. According to this configuration, since the retardation in the in-plane direction of the retardation layer is 0 nm, the coloring phenomenon that occurs when the in-plane retardation exists can be prevented, and the contrast ratio can be maintained at a high value.

  On the other hand, instead of setting nx1 = ny1, the retardation layer is arranged between the quarter-wave layer and the liquid crystal cell, and the respective main refractive indexes nx1, ny1 are different from each other. The nx1 axes of the two retardation layers may be orthogonal to each other, and the ny1 axes of the two retardation layers may be orthogonal to each other.

  In this configuration, the nx1 axis and the ny1 axis of the retardation layers arranged on both sides of the liquid crystal cell are orthogonal to each other. Therefore, the retardation in the in-plane direction generated in one retardation layer is canceled out by the other retardation layer. As a result, the coloring phenomenon can be prevented, and the contrast ratio can be maintained at a high value.

  In addition to the above-described configurations, it is desirable that both the quarter-wave layers have the same retardation in the thickness direction. According to this configuration, both quarter-wave layers can be manufactured in the same process, so that both characteristics can be easily aligned even if production variations occur. As a result, the productivity of the liquid crystal display device can be improved as compared with the case where a quarter-wave layer having different retardation in the thickness direction is used.

  As described above, the liquid crystal display device according to the present invention is disposed between each polarizing element and the liquid crystal cell in the vertical alignment mode, and the retardation in the in-plane direction is approximately one-fourth of the wavelength of transmitted light. It is arranged between the set quarter-wave layer, at least one of the quarter-wave layers and the liquid crystal cell, and the main refractive index in the in-plane direction is nx1, ny1, and the main refractive index in the normal direction Is set between the retardation layer having the smallest main refractive index nz1 and the quarter wavelength layer and the polarizing element on which at least the retardation layer is provided, and the main refraction in the in-plane direction. In this configuration, the refractive index is nx2, ny2, and the main refractive index in the normal direction is nz2, and the compensation layer has the largest main refractive index nz2.

  As described above, the liquid crystal display device according to the present invention is disposed between each polarizing element and a liquid crystal cell including a liquid crystal having positive dielectric anisotropy, and the in-plane retardation is approximately the wavelength of transmitted light. A quarter-wave layer set to a quarter-wave, a positive uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell, and the four-minute A negative uniaxial retardation layer disposed between at least one of the one wavelength layer and the liquid crystal cell, and a quarter wavelength layer and a polarizing element provided with at least one of the retardation layers And a compensation layer having the largest main refractive index nz2 when the main refractive index in the in-plane direction is nx2, ny2 and the main refractive index in the normal direction is nz2. Further, instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, In this configuration, an inclined retardation layer is provided in which the na axis coincides with the in-plane rubbing orthogonal direction and the nc axis is inclined at a predetermined angle from the normal direction.

  As described above, the optically compensated bend mode liquid crystal display device according to the present invention is disposed between each polarizing element and a liquid crystal cell including a liquid crystal having positive dielectric anisotropy, and has an in-plane retardation. The main refractive index in the in-plane direction is arranged between the quarter wavelength layer set to approximately one quarter of the wavelength of the transmitted light, at least one of the quarter wavelength layer and the liquid crystal cell. Are nx1, ny1, and the main refractive index in the normal direction is nz1, a retardation layer of nx1> ny1> nz1, and a quarter wavelength layer and a polarizing element on which at least the retardation layer is provided And a compensation layer having the largest main refractive index nz2 when the main refractive index in the in-plane direction is nx2, ny2 and the main refractive index in the normal direction is nz2. Further, instead of the retardation layer, the original refractive index ellipsoid is na = nb> nc and the na axis is in-plane rubbing between at least one of the quarter-wave layers and the liquid crystal cell. In this configuration, an inclined retardation layer is provided that is aligned with the orthogonal direction and inclined so that the nc axis forms a predetermined angle from the normal direction.

  According to these configurations, a compensation layer whose retardation in the thickness direction is opposite to the quarter-wave layer or the retardation layer is disposed between the polarizing element and the quarter-wave layer. ing. Therefore, even if the total retardation in the thickness direction from the polarizing element to the liquid crystal cell and from the liquid crystal cell to the polarizing element is the same, the compensation for the liquid crystal cell is less than that without the compensation layer. The retardation (thickness direction) can be brought close to the liquid crystal cell. As a result, it is possible to realize a liquid crystal display device that can maintain a wide viewing angle without impairing the balance of the viewing angle characteristics of the upper, lower, left, and right sides, and that can prevent a decrease in contrast ratio in the front direction.

  The liquid crystal display device according to the present invention includes, in addition to the configuration in which the compensation layer having the largest main refractive index nz2 is provided, at least between the quarter wavelength layer and the polarizing element on which the retardation layer is provided. Nx3> ny3 where the main refractive index in the in-plane direction is nx3, ny3, and the main refractive index in the normal direction is nz3, and the absorption axis of the polarizing element on the same side with respect to the liquid crystal cell is In this configuration, a polarizing element compensation layer set so as to be parallel to the ny3 axis is provided.

  According to these configurations, since the retardation in the thickness direction of the polarizing element compensation layer can be canceled by the compensation layer, the compensation of the liquid crystal cell can be performed even though the polarizing element can be optically compensated by the polarizing element compensation layer. Retardation (thickness direction) can be brought close to the liquid crystal cell. As a result, in all in-plane orientations, light leakage at the time of black display can be prevented, and a liquid crystal display device capable of displaying black well can be realized.

  In the liquid crystal display device according to the present invention, in addition to the configuration in which the compensation layer having the largest main refractive index nz2 is provided, each main refractive index of the compensation layer is configured to satisfy nx2 = ny2 <nz2. is there. According to this configuration, since the retardation in the in-plane direction of the compensation layer is 0, it is possible to prevent the coloring phenomenon that occurs when the in-plane retardation exists, and to maintain the contrast ratio at a high value. .

In the liquid crystal display device according to the present invention , the main refractive index in the in-plane direction is set to nx4, ny4, and the main refractive index in the normal direction as the quarter-wave layer instead of providing the compensation layer having the above-described configurations. Is nz4, (nx4 + ny4) / 2 is a configuration using a quarter wavelength layer of nz4.

  In this configuration, retardation in the thickness direction of the quarter wavelength layer is suppressed to substantially zero. Accordingly, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell, and a wide viewing angle can be obtained without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, as in the case where the compensation layer is provided. In addition, there is an effect that it is possible to realize a liquid crystal display device that can maintain the contrast and prevent a reduction in contrast ratio in the front direction.

The liquid crystal display device according to the reference of the present invention has the above-mentioned quarter-wave layer regardless of whether (nx4 + ny4) / 2 of the quarter-wave layer is set to nz4 or not and whether or not a compensation layer is present. And the absolute value of the retardation in the thickness direction in the range from the polarizing element to the quarter-wave layer is set to be less than one-eighth of the wavelength of the transmitted light.

  Even in this configuration, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell in the same manner as the above-described liquid crystal display devices. There is an effect that it is possible to realize a liquid crystal display device capable of maintaining a wide viewing angle without impairing the balance of characteristics and preventing a reduction in the contrast ratio in the front direction.

In addition to the above configuration, the liquid crystal display device according to the reference of the present invention has a configuration in which the absolute value of retardation in the thickness direction in the above range is set to substantially zero. According to this configuration, the retardation in the thickness direction effective for optically compensating the liquid crystal cell can be brought closest to the liquid crystal cell, and the display quality of the liquid crystal display device can be improved.

  In the liquid crystal display device according to the present invention, in addition to the above components, the liquid crystal cell includes a first substrate provided with a pixel electrode corresponding to a pixel, a second substrate provided with a counter electrode, and both the substrates. A liquid crystal layer provided between them, and the liquid crystal layer has different alignment directions of liquid crystal molecules in the pixel when the voltage between the pixel electrode and the counter electrode is at least a predetermined value. The configuration is controlled as described above.

  In the above configuration, the orientation direction of the liquid crystal molecules is controlled to be different from each other in the pixel in order to ensure a wide viewing angle. As long as is not coincident with the viewing angle, it can contribute to improving the brightness. As a result, there is an effect that high light utilization efficiency can be secured while maintaining a wide viewing angle.

  In the liquid crystal display device according to the present invention, in addition to the above-described configurations, the main refractive indexes nx1 and ny1 of the retardation layer are set to nx1 = ny1. According to this configuration, since the retardation in the in-plane direction of the retardation layer is 0 nm, it is possible to prevent the coloring phenomenon that occurs when the in-plane retardation exists, and to maintain the contrast ratio at a high value. Play.

  In the liquid crystal display device according to the present invention, instead of setting nx1 = ny1 as described above, the retardation layer is disposed both between the quarter-wave layer and the liquid crystal cell, and the respective main refractions thereof. The rates nx1 and ny1 are different from each other, and the nx1 axes of the two retardation layers are orthogonal to each other, and the ny1 axes of the two retardation layers are orthogonal to each other. In this configuration, the nx1 axis and the ny1 axis of the retardation layers arranged on both sides of the liquid crystal cell are orthogonal to each other. Therefore, the retardation in the in-plane direction generated in one retardation layer is canceled out by the other retardation layer. As a result, the coloring phenomenon can be prevented, and the contrast ratio can be maintained at a high value.

  In the liquid crystal display device according to the present invention, in addition to the above-described configurations, the quarter-wave layers have a configuration in which the positive and negative retardations in the thickness direction are the same. According to this configuration, both quarter-wave layers can be manufactured in the same process, so that both characteristics can be easily aligned even if production variations occur. As a result, there is an effect that the productivity of the liquid crystal display device can be improved as compared with the case where a quarter-wave layer having different positive and negative retardations in the thickness direction is used.

[First Embodiment]
An embodiment of the present invention will be described below with reference to FIGS. As will be described in detail later, the present invention can be applied to other liquid crystal cells, but in the following, as a suitable example, the alignment direction of liquid crystal molecules such as radial tilt alignment and multi-domain alignment is in the pixel. The liquid crystal cells controlled to be different from each other will be described.

  As shown in FIG. 1, the liquid crystal display device 1 according to this embodiment includes a liquid crystal cell 11 and linearly polarizing films (polarizing elements) 12 a and 12 b disposed on both sides of the liquid crystal cell 11. However, it is characterized by the following measures. That is, the liquid crystal cell 11 includes a TFT substrate 11a (first substrate) provided with a pixel electrode 21a (see FIG. 2) corresponding to a pixel, and a counter substrate 11b (see FIG. 2) provided with a counter electrode 21b (see FIG. 2). A second substrate) and a liquid crystal layer 11c provided between the substrates 11a and 11b. Further, when the voltage between the pixel electrode 21a and the counter electrode 21b is at least a predetermined value, the liquid crystal layer 11c has, for example, an orientation direction of liquid crystal molecules as indicated by an arrow in FIG. It is controlled to be different from each other in the pixel.

  In addition, as shown in FIG. 1, the liquid crystal display device 1 includes λ / 4 plates 13a and 13b (quarter wavelength layers) disposed between the linearly polarizing films 12a and 12b and the liquid crystal cell 11, respectively. ) And at least one of the λ / 4 plates 13a and 13b (both in this case) and the liquid crystal cell 11, the main refractive index in the in-plane direction is nx1, ny1, and the main refractive index in the normal direction Is a liquid crystal compensator (retardation layer; negative film) 14a and 14b having the smallest main refractive index nz1, and between the linearly polarizing film 12a (12b) and the λ / 4 plate 13a (13b). An Rth compensation film (compensation) in which the main refractive index nz2 is the largest when the main refractive index in the in-plane direction is nx2, ny2 and the main refractive index in the normal direction is nz2. Layer) 16a, 16 It is equipped with a door.

  Here, in the λ / 4 plate 13a (13b), the retardation in the in-plane direction is set to a quarter wavelength of the wavelength of the transmitted light, and the slow axes SLa (SLb) are orthogonal to each other. In addition, the absorption axis AAa (AAb) and the slow axis SLa (SLb) of the adjacent linearly polarizing film 12a (12b) are set to form an angle of 45 degrees.

  In the liquid crystal display device 1 having the above configuration, when light is incident from the linearly polarizing film 12a as an example, light that has passed through the linearly polarizing film 12a and the λ / 4 plate 13a is incident on the liquid crystal cell 11. The circularly polarized light is incident on the light 11, and the light emitted from the liquid crystal cell 11 is emitted through the linearly polarizing film 12b after being given a phase difference of a quarter wavelength by the λ / 4 plate 13b. .

  Here, when the voltage between the pixel electrode 21a and the counter electrode 21b is a predetermined voltage, such as an initial alignment state when a voltage is applied or no voltage is applied, the alignment directions of the liquid crystal molecules are mutually in the pixel. Controlled differently. In this state, since the liquid crystal cell 11 gives the transmitted light a phase difference corresponding to the alignment state, the circularly polarized light is converted into elliptically polarized light. Therefore, the light transmitted through the liquid crystal cell 11 does not return to linearly polarized light even when transmitted through the λ / 4 plate 13b, and a part of the emitted light from the λ / 4 plate 13b is emitted from the linearly polarizing film 12b. As a result, the amount of light emitted from the linearly polarizing film 12b can be controlled according to the applied voltage, and gradation display is possible.

  In addition, since the alignment directions of the liquid crystal molecules are different from each other in the pixel, the regions where the liquid crystal molecules having different alignment directions are present can optically compensate for each other. As a result, the display quality when viewed from an oblique direction can be improved and the viewing angle can be expanded.

  Here, in the liquid crystal cell 11, as a result of controlling the alignment directions of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, disorder of the alignment state is likely to occur. Therefore, in the case of a conventional liquid crystal display device in which linearly polarized light is incident on the liquid crystal cell and the light emitted from the liquid crystal cell is incident on the analyzer, the alignment of the liquid crystal molecules is disturbed, and the in-plane component in the alignment direction is reduced. If it coincides with the absorption axis of the polarizing element, the liquid crystal molecules cannot give a phase difference to the transmitted light regardless of the component in the normal direction of the substrate. Therefore, the region where the liquid crystal molecules are present cannot contribute to the improvement of brightness, and roughness or the like occurs. In addition, since the liquid crystal molecules whose in-plane components in the alignment direction coincide with the absorption axis of the analyzer cannot contribute to the improvement in brightness, the light utilization efficiency (effective aperture ratio) decreases. As a result, it is difficult to ensure the contrast ratio and increase the number of gradations.

  On the other hand, in the liquid crystal display device 1 according to the present embodiment, substantially circular polarized light is incident on the liquid crystal cell 11, so that there is no anisotropy in the alignment direction of the liquid crystal cell 11, and the alignment direction and transmission of the liquid crystal molecules As long as the light does not match in both the in-plane component and the substrate normal direction, the liquid crystal molecules can give a phase difference to the transmitted light. Therefore, as a result of controlling the alignment direction of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, the alignment direction of the liquid crystal molecules whose alignment is disturbed despite the fact that the alignment state is likely to be disturbed. As long as it does not match, it can contribute to the improvement of brightness. As a result, high light utilization efficiency can be secured while maintaining a wide viewing angle.

  On the other hand, when the liquid crystal molecules of the liquid crystal cell 11 are aligned in the substrate normal direction (vertical), the liquid crystal cell 11 cannot give a phase difference to the transmitted light. As a result, the transmitted light is emitted while maintaining substantially circularly polarized light. The emitted light is converted into linearly polarized light by the λ / 4 plate 13b and then input to the linearly polarizing film 12b, and transmission is limited. Therefore, the liquid crystal display device 1 can display black.

  However, even if the liquid crystal molecules are aligned vertically, the alignment direction of the liquid crystal molecules and the direction of transmitted light do not match when viewed from an oblique direction inclined by a polar angle from the normal direction of the substrate. A phase difference corresponding to the polar angle is given to the transmitted light. However, since the liquid crystal compensators 14a and 14b have the smallest main refractive index nz1, they can give a phase difference opposite to the phase difference given by the liquid crystal cell 11.

  Further, in the above configuration, the Rth compensation films 16a and 16b, which are opposite to the liquid crystal compensation plates 14a and 14b in terms of the thickness direction retardation, are linearly polarized films 12a and 12b and λ / 4 plates 13a and 13b. Arranged in between. Therefore, for example, a member that functions as a negative film, such as a support for the linearly polarizing films 12a and 12b, is interposed between the polarizing element and the quarter-wave layer, or the quarter-wave layer is in the thickness direction. Even if it has retardation, the retardation of these members can be canceled by the compensation layer. In the negative film, the main refractive index in the in-plane direction is nx and ny, the main refractive index in the normal direction is nz, the thickness is d, and the retardation Rth = {nz− (nx + ny) / 2} in the thickness direction. When d is defined, it is a retardation layer having a negative value for Rth.

  As a result, even if the total retardation in the thickness direction from the linearly polarizing film 12a to the liquid crystal cell 11 and from the liquid crystal cell 11 to the linearly polarizing film 12b is the same, the λ / 4 plate 13a (13b) The retardation in the thickness direction from the linearly polarizing film 12a (12b) to the λ / 4 plate 13a (13b) can be reduced. Thereby, the retardation for compensation (thickness direction) of the liquid crystal cell 11 can be made closer to the liquid crystal cell 11 than in the case where the Rth compensation film 16a (16b) is not provided. Therefore, light leakage during black display can be prevented and good black display can be achieved.

  As a result, in order to secure a wide viewing angle, the alignment direction of the liquid crystal molecules is controlled to be different from each other in the pixel, so that a high contrast ratio is maintained over a wide viewing angle even though the alignment state is likely to be disturbed. A possible liquid crystal display device can be realized.

  Below, the concrete structural example and effect of each said member are demonstrated in detail, comparing with a comparative example. That is, the liquid crystal cell 11 is a vertical alignment (VA) type liquid crystal cell in which liquid crystal molecules are aligned perpendicularly to the substrate when no voltage is applied, and exhibit a radially inclined alignment in which the alignment direction continuously changes when a voltage is applied. Then, a vertical alignment film (not shown) is applied to both the TFT substrate 11a in which the thin film transistor elements (not shown) and the pixel electrodes 21a are arranged in a matrix and the counter substrate 11b having the counter electrode 21b. The substrates are bonded to each other, and a nematic liquid crystal having a negative dielectric anisotropy is sealed in a gap between both substrates. Thus, when no voltage is applied, the liquid crystal molecules of the liquid crystal layer 11c are aligned substantially vertically, and when a voltage is applied, the liquid crystal molecules are tilted and can be horizontally aligned.

  In this embodiment, as an example, the refractive index anisotropy Δn of the liquid crystal is 0.1, and the cell thickness is set to 3 μm. In this case, the retardation in the thickness direction is 300 nm. In the present embodiment, the refractive index anisotropy Δn is realized using a material having an ordinary light refractive index no = 1.5 and an extraordinary light refractive index ne = 1.6, for example.

  Furthermore, in the liquid crystal cell 11 according to the present embodiment, as shown in FIG. 2, circular slits 22 are formed in each pixel electrode 21a provided on the TFT substrate 11a. Thus, when a voltage is applied, an electric field that tilts the liquid crystal molecules is not applied in the region immediately above the slit 22 in the surface of the pixel electrode 21a. Therefore, in this region, the liquid crystal molecules are aligned vertically even when a voltage is applied. On the other hand, in the region near the slit 22 in the surface of the pixel electrode 21a, the electric field is inclined and spreads so as to avoid the slit 22 as it approaches the slit 22 in the thickness direction. Here, the liquid crystal molecules are inclined in the direction in which the major axis is vertical, and the liquid crystal molecules separated from the slit 22 are also aligned in the same direction due to the continuity of the liquid crystal. Therefore, when a voltage is applied to the pixel electrode 21a, each liquid crystal molecule is aligned such that the in-plane component in the alignment direction spreads radially around the slit 22, as shown by the arrows in the drawing, that is, the slit 22 It can be oriented symmetrically about the center of the axis. Here, since the gradient of the electric field changes depending on the applied voltage, the substrate normal direction component (tilt angle) in the alignment direction of the liquid crystal molecules can be controlled by the applied voltage. When the applied voltage is increased, the tilt angle with respect to the normal direction of the substrate is increased, and each liquid crystal molecule is substantially parallel to the display screen and is radially aligned in the plane.

  For example, when forming a large-sized liquid crystal television such as 40 inches, the size of each pixel is as large as about 1 mm square, and the alignment regulating force can be obtained only by providing one slit 22 in the pixel electrode 21a. It may weaken and the orientation may become unstable. Therefore, when the alignment regulating force is insufficient, it is desirable to provide a plurality of slits 22 on each pixel electrode 21a.

  On the other hand, the λ / 4 plate 13a (13b) shown in FIG. 1 has a positive uniaxial optical anisotropy, for example, by being composed of a uniaxially stretched polymer film. Since the film has birefringence anisotropy, the thickness (length in the normal direction of the substrate) is set so that the optical path difference between the ordinary ray and the extraordinary ray becomes a quarter wavelength of the incident light. By setting, linearly polarized light having a polarization direction of 45 degrees with respect to the slow axis SLa can be converted into circularly polarized light. Further, when circularly polarized light is incident, it can be converted into linearly polarized light having a polarization direction of 45 degrees with respect to the slow axis SLb of the λ / 4 plate 13b. In the present embodiment, the in-plane retardation of each of the λ / 4 plates 13a and 13b is set to 137.5 nm at a wavelength of 550 nm. As an example, in this embodiment, when the main refractive index in the in-plane direction is nx and ny, and the main refractive index in the normal direction is nz, nx = 1.501375 and ny = nz = 1. 5, a uniaxially stretched film having a thickness d of 100 μm is used. In this case, the retardation in the in-plane direction is 137.5 nm for light having a wavelength of 550 nm, and the retardation in the thickness direction is −68.75 nm because it is a uniaxially stretched film.

  In addition, when forming the liquid crystal layer 11c, a chiral agent is attached so that the twist angle is 90 degrees as in the liquid crystal display device described in Japanese Patent Application Laid-Open No. 2000-47217 (published on February 18, 2000). Similarly to the TN mode liquid crystal display device, when the light use efficiency and the color balance at the time of white display are optimized, the λ / 4 plate 13a (13b) according to the twist angle in the liquid crystal cell 11. It is desirable to deviate the optical path difference from the quarter wavelength.

  Further, in the liquid crystal display device 1 according to the present embodiment, as shown in FIG. 1, the absorption axis AAa of the linearly polarizing film 12a and the absorption axis AAb of the linearly polarizing film 12b are arranged so as to be orthogonal to each other. Further, the slow axes SLa and SLb of the both λ / 4 plates 13a and 13b are arranged so as to be orthogonal to each other. Further, the adjacent λ / 4 plates 13a (13b) and the linearly polarizing film 12a (12b) are arranged so that the slow axis SLa (SLb) and the absorption axis AAa (AAb) form an angle of 45 degrees. Is done.

  Further, the liquid crystal compensators 14a and 14b are formed of a film of nx = ny> nz, where nx and ny are the main refractive indices in the in-plane direction and nz is the main refractive index in the normal direction. The retardation Rth in the thickness direction of the film can be defined as Rth = d · {nz− (nx + ny) / 2} where d is the thickness. Therefore, the retardation Rth in the thickness direction of the liquid crystal compensators 14a and 14b is The film material and the thickness are selected so that each becomes -100 nm. As an example, in the present embodiment, the retardation Rth is achieved by setting a film of nx = ny = 1.502 and nz = 1.5 to a thickness d = 50 μm.

  On the other hand, in the Rth compensation films 16a and 16b, the retardation Rth in the thickness direction is set to 68.75 nm, respectively, so as to cancel the retardation in the thickness direction of the λ / 4 plates 13a and 13b. In the present embodiment, as an example, each of the Rth compensation films 16a and 16b has one axis where nx = ny <nz, where nx and ny are the main refractions in the in-plane direction and nz is the main refractive index in the thickness direction. A refractive index ellipsoid of which the characteristic is expressed, and each has a thickness d = 100 μm, an in-plane main refractive index nx = ny = 1.5, and a normal refractive index nz = 1.5006875. Is set to Since nx = ny, the in-plane retardation Re is 0 nm.

  In the above configuration, the liquid crystal molecules of the liquid crystal cell 11 are in the vertical alignment state while no voltage is applied between the pixel electrode 21a and the counter electrode 21b. In this state (when no voltage is applied), the light incident on the liquid crystal display device 1 passes through the linear polarizing film 12a and becomes linearly polarized light whose polarization direction is 45 degrees with respect to the slow axis SLa of the λ / 4 plate 13a. . Further, the linearly polarized light is converted into circularly polarized light by passing through the λ / 4 plate 13a.

  Here, the liquid crystal molecules do not give a phase difference to light incident in a direction parallel to the alignment direction. Therefore, the liquid crystal cell 11 cannot give a phase difference to vertically incident light and has almost no birefringence. As a result, the circularly polarized light emitted from the λ / 4 plate 13a passes through the liquid crystal cell 11 while maintaining the polarization state, and is incident on the λ / 4 plate 13b. When the circularly polarized light passes through the λ / 4 plate 13b, the circularly polarized light has a polarization direction of 45 degrees with respect to the slow axis SLb of the λ / 4 plate 13b, that is, along the absorption axis AAb of the linearly polarizing film 12b. Is converted into linearly polarized light in the specified direction. Therefore, the linearly polarized light is absorbed by the linearly polarizing film 12b, and the liquid crystal display device 1 can display black in a state where no voltage is applied.

  On the other hand, when a voltage is applied between the pixel electrode 21a and the counter electrode 21b, the liquid crystal molecules of the liquid crystal cell 11 are radially inclined with the slit 22 as the central axis. Even in this state, up to the liquid crystal cell 11, the polarization state is converted in the same manner as when no voltage is applied, and circularly polarized light enters the liquid crystal cell 11.

  However, when a voltage is applied, the alignment direction of the liquid crystal molecules changes and the alignment is radially inclined. Here, the liquid crystal molecules do not give a phase difference to light incident in a direction parallel to the alignment direction, but when the alignment direction and the incident direction are different, the phase difference according to the angle between the two is transmitted. Can be given to light.

  As a result, in the case of light perpendicularly incident on the liquid crystal cell 11, for example, the liquid crystal except for a slight region in which liquid crystal molecules are aligned in the normal direction of the substrate even when a voltage is applied, such as a region directly above the slit 22. The cell 11 can give a phase difference to the transmitted light, and can change the polarization state of the transmitted light. Therefore, the light emitted from the liquid crystal cell 11 generally changes to elliptically polarized light. Even when this elliptically polarized light passes through the λ / 4 plate 13b, it does not become linearly polarized light unlike when no voltage is applied. Therefore, a part of the light given from the liquid crystal cell 11 to the linearly polarizing film 12b through the λ / 4 plate 13b can pass through the linearly polarizing film 12b. Here, the amount of polarized light transmitted through the linearly polarizing film 12b depends on the magnitude of the phase difference provided by the liquid crystal cell 11. Therefore, by controlling the voltage applied to the pixel electrode 21a and adjusting the alignment direction of the liquid crystal molecules, the amount of light emitted from each pixel of the liquid crystal display device 1 can be changed, and gradation display becomes possible.

  In the above configuration, since the liquid crystal molecules of the liquid crystal cell 11 are radially inclined and aligned, each liquid crystal molecule compensates optically. Therefore, when the liquid crystal display device 1 is viewed from a certain in-plane orientation, even when the amount of light emitted through a certain liquid crystal molecule is reduced as compared with the case of viewing from another in-plane orientation, Among other liquid crystal molecules having different alignment directions, there are those that increase the amount of emitted light. As a result, the entire liquid crystal molecules related to the display of a certain pixel have substantially the same phase difference given to the transmitted light. As described above, in each pixel, regions where liquid crystal molecules having different pixel alignment directions exist are optically compensated for each other, so that all liquid crystal molecules related to display of a certain pixel are inclined in a single specific direction. Compared with the case of orientation, the display quality when viewed from an oblique direction can be improved and the viewing angle can be expanded.

  Here, as in the liquid crystal display device 101 shown in FIG. 3 as a comparative example, even if the liquid crystal molecules of the liquid crystal cell 111 are radially inclined and aligned in order to ensure a wide viewing angle, the liquid crystal cell 111 is linearly aligned. In the case of a configuration in which polarized light is incident, there are liquid crystal molecule groups in which the in-plane component in the alignment direction is tilted and aligned in a direction that matches the direction of linearly polarized light. Here, since these liquid crystal molecule groups cannot give a phase difference to transmitted light regardless of the normal direction component of the alignment direction, the light transmitted through the liquid crystal molecule groups is emitted in the same manner as in the vertical alignment. It is absorbed by the linear polarizing film 112b on the side.

  As a result, the transmittance of the region along the direction of the linearly polarized light and the region along the direction perpendicular to the direction of the linearly polarized light with the slit position as the center decreases. Therefore, when the decrease in transmittance is large, for example, as shown in FIG. 4, black shadows along the absorption axis direction (crossed Nicols) of the linearly polarizing films 112a and 112b are visually recognized when displaying white. There is a fear.

  In particular, as in the liquid crystal display device 101, when the alignment direction in a pixel is separately controlled, alignment disturbance is likely to occur. For example, a single electric field such as an external electric field from a source signal line or a gate signal line is used. In the case of this orientation direction, disorder of orientation occurs due to a slight factor that does not cause a problem. Since the alignment disorder is different for each place and each pixel, the black shadow is observed as roughness during display, and there is a possibility that the display quality is deteriorated.

  Moreover, when the location where the alignment disorder occurs becomes dark, the luminance of the entire pixel also decreases as compared with the case where the planned transmittance is maintained at all locations. As a result, the light utilization efficiency (effective aperture ratio) of the liquid crystal display device also decreases.

  Here, the resolution and the number of gradations of a liquid crystal display device are improving year by year, and there is a demand for a liquid crystal display device that can display more gradations even when the area of one pixel is reduced. However, if the effective aperture ratio is reduced due to the above-mentioned disorder of orientation, the luminance at the time of white display is lowered and it is difficult to improve the number of gradations. Note that when the pixel area is enlarged, the luminance can be improved, but it is difficult to improve the resolution.

  On the other hand, in the configuration of the present embodiment, since the circularly polarized light is incident on the liquid crystal cell 11, a phase difference is given to the transmitted light even though a wide viewing angle is ensured by the inclined orientation in the radial direction. The only liquid crystal molecules that cannot be aligned are those that are aligned in the same direction as the viewing angle in both the in-plane component and the normal direction component. Therefore, the number of liquid crystal molecules that cannot contribute is reduced, and it becomes difficult to visually recognize the shadow. Furthermore, even if the transmittance decreases to such an extent that a shadow is visually recognized, a phase difference can be given if both the in-plane component and the normal direction component are not the same as the viewing angle. Therefore, as shown in FIG. 5, the area where the shadow is displayed is only the position of the slit 22, and the area where the shadow is displayed can be greatly reduced. Further, the number of liquid crystal molecules capable of giving a phase difference to transmitted light increases regardless of whether or not a shadow is visually recognized. As a result, the transmittance can be improved about twice as compared with the conventional liquid crystal display device 101 without the λ / 4 plates 13a and 13b, and the light use efficiency (effective aperture ratio) and the luminance can be improved.

  In the liquid crystal display device 1, since the slow axis SLa of the λ / 4 plate 13a and the slow axis SLb of the λ / 4 plate 13b are orthogonal to each other, each of the λ / 4 plates 13a and 13b has. The chromatic dispersions of refractive index anisotropy cancel each other. As a result, in the black display state, the linearly polarizing film 12b can absorb transmitted light in a wider wavelength range, and a good black display without color can be realized.

  Here, at the time of black display, the liquid crystal molecules are aligned vertically, and the liquid crystal cell 11 does not give a phase difference to the light incident in the normal direction of the substrate. However, in particular, in a transmissive liquid crystal display device, the amount of light incident on the liquid crystal cell 11 in an oblique direction (a direction inclined from the substrate normal direction) is larger than that in a reflective liquid crystal display device. Therefore, even when viewed from the substrate normal direction, not only incident light in the substrate normal direction but also incident light from an oblique direction is related to display.

  Here, the oblique incident light is also given a phase difference by the vertically aligned liquid crystal layer 11c. Therefore, as a comparative example, as shown in FIG. 6, in the case of the liquid crystal display device 51 in which the liquid crystal compensation plates 14a and 14b and the Rth compensation films 16a and 16b are omitted from the liquid crystal display device 1 shown in FIG. Even if the emitted light (elliptical polarized light) passes through the λ / 4 plate 13b, it does not return to linearly polarized light, and a part thereof passes through the linearly polarizing film 12b. As a result, there is a possibility that light leakage occurs and the contrast ratio of the display is lowered despite the vertical alignment state that should originally be black.

  In addition, as shown in FIG. 7, when the display surface of the liquid crystal display device is viewed from an oblique direction, incident light from the oblique direction with respect to the substrate further contributes to the display, so that a larger light leakage occurs. The contrast ratio is further reduced. As a result, for example, the contrast ratio in the direction where the angle (extreme) with respect to the substrate normal direction is 60 degrees is about 10 at the maximum as shown in FIG. In FIG. 8, the contrast ratios in all directions where the extreme is 60 degrees are drawn while changing the in-plane component (orientation).

  On the other hand, in the liquid crystal display device 1 according to the present embodiment, the liquid crystal compensation plates 14a and 14b are provided, and the phase difference added by the vertically aligned liquid crystal cell 11 depending on the extreme is obtained. It can be canceled with 14b.

  In addition, since the Rth compensation films 16a and 16b are provided in the liquid crystal display device 1 according to this embodiment, the liquid crystal display device 1 includes the λ / 4 plate 13a (13b), and includes the λ / 4 plate from the linearly polarizing film 12a (12b). Of the retardation in the thickness direction in the range up to 13a (13b), for example, the retardation in the thickness direction of the λ / 4 plates 13a and 13b itself can be offset. Thereby, the liquid crystal compensators 14 a and 14 b having retardation in the thickness direction and optically compensating the liquid crystal cell 11 can be brought close to the liquid crystal cell 11.

  In particular, in the above configuration, even if a negative film is provided in the above range due to manufacturing reasons, etc., the retardation Rth1 in the above range is substantially 0. It can be equivalent to the case where an effective retardation in the thickness direction exists only in the negative films (14a and 14b) in contact with the liquid crystal cell 11.

  As a result, as shown in FIG. 9, the contrast ratio in all directions of 60 degrees is a value exceeding 50, and the liquid crystal display device 1 having a wider viewing angle than the liquid crystal display device 51 shown in FIG. 6 is realized. it can.

  Furthermore, as shown in FIG. 9, in the liquid crystal display device 1 according to the present embodiment, regions having a particularly high contrast ratio appear in four directions every 90 degrees, and the respective peak values are substantially the same value. ing. Therefore, the liquid crystal display device 1 with a well-balanced viewing angle characteristic in the four directions is realized.

  Here, the total S of the retardation in the thickness direction from the linearly polarizing film 12a to the liquid crystal cell 11 and the retardation in the thickness direction from the liquid crystal cell 11 to the linearly polarizing film 12b is determined by the liquid crystal cell 11 depending on the viewing angle. It is necessary to set so as to cancel the phase difference to be given, and it cannot be changed.

  Therefore, in order to confirm the effect of bringing the retardation for compensation (thickness direction) of the liquid crystal layer closer to the liquid crystal cell 11, the λ / 4 plate 13a (13b) is included and the linearly polarizing film 12a (12b) / 4 plate 13a (13b) in the thickness direction retardation Rth1 and λ / 4 plate 13a (13b) are not included, and the thickness direction retardation in the range from λ / 4 plate 13a (13b) to liquid crystal cell 11 While changing the ratio K to the retardation Rth2, the contrast ratio was obtained by simulation.

  Strictly speaking, the retardation Rth2 is a retardation up to the liquid crystal layer 11c and does not include a retardation of the liquid crystal layer 11c itself. However, even in the liquid crystal cell 11, if a phase difference has occurred in the layers up to the liquid crystal layer 11 c such as the substrates 11 a and 11 b and the thin film, the retardation in these layers is the above retardation. Included in Rth2.

  The contrast ratio is improved by bringing the liquid crystal compensator 14a (14b) closer to the liquid crystal cell 11 even if the total S with the thickness direction retardation is the same as a result of this simulation or comparison with each comparative example. Turned out to be.

More specifically, as shown in Equation (1) below,
K = Rth2 / (Rth1 + Rth2) ≧ 0.1 (1)
As long as the above is satisfied, an improvement in contrast ratio was observed. Further, it was found that the ratio K is closer to 1.0, and when 1.0, that is, when Rth1 = 0, the display quality is the highest.

  For example, as shown in FIG. 10, in the liquid crystal display device 1a as a modification of the present embodiment, the Rth compensation films 16a and 16b are deleted from the configuration shown in FIG. 1, and the thickness direction of the liquid crystal compensation plates 14a and 14b is reduced. The retardation Rth is set to −60 nm depending on the film material and thickness. Also in this example, the ratio K is 0.1 or more, and the contrast ratio in all directions of 60 degrees is a value exceeding 10 as shown in FIG. Therefore, a liquid crystal display device having a wider viewing angle than the liquid crystal display device 51 shown in FIG. 6 is realized.

  In the above description, the liquid crystal compensation plates 14a and 14b are arranged on both sides of the liquid crystal cell 11. However, if the total retardation S in the thickness direction is the same, for example, the liquid crystal display device 1b shown in FIG. As described above, even when the liquid crystal compensation plate 14 (for example, Rth = 200 nm) having a double retardation in the thickness direction is disposed only on one side of the liquid crystal cell 11, substantially the same effect as that of the present embodiment can be obtained. Furthermore, even in this case, the insertion position of the negative film (liquid crystal compensation plate) should be close to the liquid crystal cell 11 as between the λ / 4 plate 13a (13b) and the liquid crystal cell 11, The ratio K is preferably set to 0.1 or more, and it was confirmed that the display quality was the highest when 1.0, that is, when Rth1 = 0.

  For example, as a comparative example, the liquid crystal display device 52 shown in FIG. 13 is provided with a liquid crystal compensation plate 14a (14b) in addition to the configuration of the liquid crystal display device 51 shown in FIG. However, the liquid crystal compensator 14a (14b) is not between the λ / 4 plate 13a (13b) and the liquid crystal cell 11 as shown in FIG. 1, but the λ / 4 plate 13a (13b) and the linearly polarizing film 12a (12b). ). In addition, since the Rth compensation films 16a and 16b are not provided, the retardation in the thickness direction of the liquid crystal compensation plate 14a (14b) is more absolute than the configuration of FIG. 1 by the amount of the λ / 4 plate 13a (13b). The values are set small and each is set to −60 nm.

  In this configuration, when the contrast ratio in all directions of 60 degrees is measured, as shown in FIG. 14, the contrast ratio is improved as compared with the liquid crystal display device 51 that does not have the liquid crystal compensation plates 14a and 14b. The contrast ratio is lower than that of the liquid crystal display device 1 shown in FIG. 1, and there is an orientation in which the contrast ratio is less than 5. Thus, the insertion position of the liquid crystal compensation plate 14a (14b) is more like the liquid crystal display device 1 shown in FIG. 1 than between the λ / 4 plate 13a (13b) and the linearly polarizing film 12a (12b). The λ / 4 plate 13a (13b) and the liquid crystal cell 11 can ensure a wider viewing angle.

  As another comparative example, as compared with the case where the Rth compensation films 16a and 16b of the liquid crystal display device 1 shown in FIG. 1 are arranged inside the λ / 4 plates 13a and 13b, as shown in FIG. It has also been confirmed that the contrast ratio in all directions of 60 degrees can be improved by arranging the films 16a and 16b on the outside.

  Further, the degree of approaching the compensation retardation (thickness direction) of the liquid crystal layer to the liquid crystal cell 11 is determined by simulation focusing on the value of Rth1 itself, not the ratio K defined by the above formula (1). As a result, it was confirmed that the effect was obtained if the absolute value of Rth1 was less than λ / 8, and that the display quality was highest when Rth1 = 0, as in the case of confirmation with the ratio K. In addition, within the range of less than λ / 8, the absolute value of Rth1 on both sides of the liquid crystal layer 11c is less than 11 nm when the wavelength of transmitted light is 550 nm, that is, less than 1/50 of the wavelength, respectively. In this range, it was confirmed that it was particularly preferable.

  For example, as another comparative example, in the liquid crystal display device 53 shown in FIG. 15, the λ / 4 plates 13c and 13d having negative and positive optical activities between the linearly polarizing films 12a and 12b similar to FIG. The liquid crystal cell 11 similar to that in FIG. 1 is disposed between the two λ / 4 plates 13c and 13d. Further, a liquid crystal compensator 14 similar to that shown in FIG. 1 is disposed between the liquid crystal cell 11 and the λ / 4 plate 13c having negative optical activity. Here, each of the λ / 4 plates 13c and 13d has uniaxial optical anisotropy, and the retardation in the thickness direction is 68.75 nm and −68.75 nm, respectively.

  In this configuration, the retardation in the thickness direction of both λ / 4 plates 13c and 13d is opposite, so that they cancel each other out, and the total S with the retardation in the thickness direction is the same as the configuration in FIG. However, the ratio K is a value exceeding 0 on the λ / 4 plate 13d side and exceeding 1 on the λ / 4 plate 13c side, both of which are out of the range of 0.1 to 1.0. . Further, the retardation in the thickness direction of the λ / 4 plates 13c and 13d is half of the retardation in the in-plane direction, that is, λ / 8. For example, the retardation Rth1 is changed to λ /, such as the Rth compensation films 16a and 16b. No particular measures are taken to make it less than 8 (optimum value 0).

  In this case, for example, the contrast ratio in the direction where the angle (extreme) with respect to the substrate normal direction is 60 degrees is as shown in FIG. 16, which is lower than that in FIG. 1 (see FIG. 9) in any orientation. ing. Furthermore, in this configuration, unlike the case of FIG. 9, the values of the four peaks of the contrast ratio are not substantially the same. In the example of FIG. 16, the peak values near the azimuth of 0 degrees and 180 degrees are near 90 degrees and 270. It is far below the peak value near the degree. This means that the balance of the contrast ratio between the top and bottom and the left and right is poor in practical conditions (the conditions in which the peak value is arranged in the up and down direction or the left and right direction). The observer may determine that the contrast ratio is high but the contrast ratio is not so high in the left-right direction compared to the up-down direction.

  On the other hand, in the liquid crystal display device 1 shown in FIG. 1, the Rth compensation films 16a and 16b are arranged so that the retardation Rth1 in the thickness direction is on both the λ / 4 plate 13a side and the λ / 4 plate 13b side. , Approximately 0 (at least less than λ / 8). Therefore, as shown in FIG. 16, the four peak values of the contrast ratio are substantially the same value, and a liquid crystal display device with a good balance between the upper and lower and left and right contrast ratios can be realized.

  Further, in the configuration of FIG. 15, the positive and negative λ / 4 plates 13 c and 13 d are different types of retardation films, and production conditions and processes are different, so that independent production variations occur. As a result, it is extremely difficult to make the retardation in the in-plane direction exactly match. As a result, light leaks even in black display, and there is a concern that the contrast ratio in the front direction (extremely 0 degrees) may be greatly reduced.

  On the other hand, in the configuration of FIG. 1, both λ / 4 plates 13 a and 13 b are the same type of retardation film, and production conditions and processes can be matched. As a result, even if production variation occurs, the retardation in the in-plane direction of both can be strictly matched. As a result, light leakage during black display can be suppressed and the front contrast ratio can be improved.

  In the above description, the liquid crystal compensators 14a and 14b are formed as uniaxially stretched films of nx = ny> nz. However, the liquid crystal compensators 14a and 14b are disposed on both sides of the liquid crystal cell 11. May use a negative film in which the in-plane main refractive indexes nx and ny are not equal. In this case, by arranging the x-axis and the y-axis to be orthogonal to each other, in-plane retardation caused by the mismatch between nx and ny can be canceled out. As a result, substantially the same effect as this embodiment can be obtained.

  Further, in the above, the retardation in the thickness direction of the Rth compensation films 16a and 16b is set so as to offset the retardation in the thickness direction of the λ / 4 plates 13a and 13b, whereby the retardation Rth1 in the thickness direction is set. The case of setting to approximately 0 has been described as an example, but the thickness direction includes the λ / 4 plate 13a (13b) itself and includes the linearly polarizing film 12a (12b) to the λ / 4 plate 13a (13b). For example, when a support for the linearly polarizing film 12a (12b) is present as the member having the retardation of Rt, the Rth compensation film 16a (16b) is a retardation in the thickness direction, taking into account the support. Rth1 is set to be substantially zero. For example, as the support film of the linearly polarizing film 12a (12b), films made of triacetyl cellulose (TAC) having each main refractive index nx = ny <nz are used, respectively, and the retardation in the thickness direction of the film is In the case of −30 nm, the retardations in the thickness direction of the Rth compensation films 16a and 16b are set to 98.75 nm, respectively. Also in this case, since the retardation Rth1 in the thickness direction is substantially 0, the same effect as the configuration of FIG. 1 can be obtained.

[Second Embodiment]
As shown in FIG. 17, the liquid crystal display device 1c according to the present embodiment has a linearly polarizing film between the linearly polarizing film 12a (12b) and the λ / 4 plate 13a (13b) in addition to the configuration shown in FIG. Polarizing plate compensation films (polarizing element compensation layers) 15a and 15b (15b) having a slow axis arranged so as to be orthogonal to the absorption axis AAa (AAb) of 12a (12b) are provided. The polarizing plate compensation film 15a (15b) is similar to the support of the linearly polarizing films 12a and 12b and the λ / 4 plates 13a and 13b, and the Rth compensation films 16a and 16b are opposite in retardation in the thickness direction. The retardation in the thickness direction of the Rth compensation films 16a and 16b cancels the retardation in the thickness direction of the support, the polarizing plate compensation film 15a (15b) and the retardation in the thickness direction of the λ / 4 plate 13a (13b). It is set to be.

  Specifically, the polarizing plate compensation film 15a (15b) is a uniaxially stretched film having an in-plane retardation of 100 nm. Therefore, the retardation in the thickness direction is −50 nm.

  In the polarizing plate compensation film 15a (15b), the slow axis Sa (Sb) is orthogonal to the absorption axis AAa (AAb) of the adjacent linearly polarizing film 12a (12b). As a result, it is possible to prevent light leakage when the liquid crystal display device having linearly polarizing films 12a and 12b whose absorption axes AAa and AAb are orthogonal to each other is viewed obliquely from the direction of 45 degrees from the absorption axis AAa (AAb). .

  Furthermore, in the present embodiment, the linearly polarizing film 12a (12b) is supported by a support film having a thickness direction retardation of −30 nm, as in the above example. The retardations in the thickness direction of the Rth compensation films 16a and 16b are set to 148.75 nm, respectively. Thereby, the retardation Rth1 in the thickness direction is set to approximately 0, respectively.

  In this configuration, the negative film is provided in the range from the λ / 4 plate 13a (13b) to the linearly polarizing film 12a (12b) including the λ / 4 plate 13a (13b) for manufacturing reasons. Regardless, the retardation Rth1 in the thickness direction is set to approximately zero. As a result, as shown in FIG. 18, the contrast ratio in all azimuths of 60 degrees is a value exceeding 100, which exceeds the case of FIG. 1 (see FIG. 9) in all azimuths. In addition, the contrast ratio is improved particularly in the valley (minimum value) portion, and a liquid crystal display device with a wider viewing angle can be realized.

  As another numerical example, the retardation in the thickness direction of the polarizing plate compensation films 15a and 15b and both supports is -30 nm, the retardation in the thickness direction of the liquid crystal compensation plates 14a and 14b is -130 nm, the Rth compensation film 16a When the retardation in the thickness direction of 16b is 90 nm, the contrast ratio at the extreme 60 degrees is as shown in FIG. 19, and a liquid crystal display device with a wider viewing angle is realized as compared with the configuration of FIG. Yes.

  In the above description, the liquid crystal compensators 14a and 14b are inserted on both sides of the liquid crystal cell 11. However, the liquid crystal compensator having a retardation Rth that is double that of the liquid crystal cell 11 inserted in both of the liquid crystal cells 11. Even if 14 is inserted, substantially the same effect can be obtained.

[Third Embodiment]
1 and 17, the Rth compensation films 16a and 16b are provided in order to make the retardation Rth1 in the thickness direction substantially zero. However, in this embodiment, the Rth compensation films 16a and 16b are provided. First, the case where the λ / 4 plate 13a (13b) having a small retardation in the thickness direction is used will be described.

  That is, as shown in FIG. 20, in the liquid crystal display device 1d according to the present embodiment, the Rth compensation films 16a and 16b are deleted from the configuration shown in FIG. 1, and the λ / 4 plate 13a (13b) is ( A film having a biaxial refractive index ellipsoid of nx + ny) / 2 = nz and a characteristic is used.

  Here, when the thickness is d, the retardation Rth in the thickness direction is Rth = d · {nz− (nx + ny) / 2}, so that the retardation in the thickness direction of the film is 0 nm. On the other hand, since the retardation Re in the in-plane direction is d · (nx−ny), the thickness and material of the film were selected, and the quarter wavelength, that is, Re = 137.5 nm was set. In the present embodiment, as the liquid crystal compensators 14a and 14b, films having a retardation in the thickness direction of −100 nm are used.

  Even in the above configuration, when the contrast ratio in all directions at an extreme of 60 degrees is measured, the same characteristics as in FIG. 9 are exhibited. As another numerical example, when a film having a retardation in the thickness direction of −130 nm is used as the liquid crystal compensators 14a and 14b, the contrast ratio is as shown in FIG. In any case, it was confirmed that a high contrast ratio of 10 or more could be secured in all directions. In addition, in any case, the four peak values of the contrast ratio are substantially the same value, and a liquid crystal display device in which the contrast ratio in the vertical direction and the horizontal direction is balanced can be realized.

  Thus, in the present embodiment, by suppressing retardation in the thickness direction of the λ / 4 plate 13a (13b), the retardation in the thickness direction is brought closer to the liquid crystal cell 11, and a liquid crystal display device with a wider viewing angle is obtained. realizable.

  In the above description, the liquid crystal compensators 14a and 14b are inserted on both sides of the liquid crystal cell 11. However, the liquid crystal compensator 14 having double retardation when inserted into only one of the liquid crystal cells 11 is used. Even if is inserted, substantially the same effect is obtained.

  Here, in the first to third embodiments, the case where the liquid crystal molecules are axially symmetrically aligned by the slit 22 has been described. However, the present invention is not limited to this. For example, as shown in FIG. 22, a substantially hemispherical protrusion 23 may be provided on the pixel electrode 21 a instead of the slit 22. In this case, in the vicinity of the protrusion 23, the liquid crystal molecules are aligned so as to be perpendicular to the surface of the protrusion 23. In addition, when a voltage is applied, the electric field at the portion of the protrusion 23 is inclined in a direction parallel to the surface of the protrusion 23. As a result, when the liquid crystal molecules are tilted when a voltage is applied, the liquid crystal molecules are easily tilted radially around the protrusion 23 in the in-plane direction, and each liquid crystal molecule of the liquid crystal cell 11 can be tilted radially. Each of the protrusions 23 can be formed by applying a photosensitive resin on the pixel electrode 21a and processing it by a photolithography process.

  In addition, the orientation direction of the liquid crystal molecules is not limited to the axially symmetric orientation as described above, and the pixels may be divided into a plurality of ranges (domains) and controlled so that the orientation directions of the liquid crystal molecules are different in each domain. Good. For example, in the configuration of FIG. 23, a quadrangular pyramid-shaped projection 23 a is provided instead of the projection 23. Even in this configuration, the liquid crystal molecules are aligned so as to be perpendicular to the inclined surfaces in the vicinity of the protrusions 23a. In addition, when a voltage is applied, the electric field at the portion of the protrusion 23a is inclined in a direction parallel to the slope of the protrusion 23a. As a result, when a voltage is applied, the in-plane component of the orientation angle of the liquid crystal molecules becomes equal to the in-plane component (direction P1, P2, P3 or P4) in the normal direction of the nearest slope. Therefore, the pixel region is divided into four domains D1 to D4 having different alignment directions at the time of inclination. As a result, when the liquid crystal display device is viewed from a certain domain side, even if the transmittance of the domain is lowered, the transmittance of the remaining domains is not lowered, and a decrease in the overall transmittance can be suppressed. Thereby, the brightness of the liquid crystal display device is less likely to depend on the in-plane orientation of the viewing angle.

  Further, for example, as shown in FIG. 24, the pixel electrode 21a is provided with stripe-shaped convex portions 24 having a mountain shape in the normal direction and an in-plane shape bent substantially at right angles to the zigzag, and the counter substrate 11b. This counter electrode 21b can also be realized by providing a convex portion 25 having the same shape. The spacing in the in-plane direction of both the convex portions 24 and 25 is arranged so that the normal line of the slope of the convex portion 24 and the normal line of the slope of the convex portion 25 coincide. Each of the convex portions 24 and 25 can be formed by applying a photosensitive resin on the pixel electrode 21a and the counter electrode 21b and processing it in a photolithography process, like the protrusions 23 and the like.

  In the structure described above, in the line portion L1 (L2) other than the corner portion C among the convex portions 24, the liquid crystal molecules in the regions D1 and D2 (D3 and D4) in the vicinity of the line portion are aligned along both mountain-shaped slopes. . The two line portions L1 and L2 are orthogonal to each other. As a result, each pixel can be divided into a plurality of domains D1 and D2 (D3 and D4) having different alignment directions.

  Furthermore, for example, as shown in FIG. 25, a Y-shaped slit is formed in the vertical direction on the counter electrode 21b of the counter substrate 11b (in the plane, a direction parallel to any side of the substantially rectangular pixel electrode 21a). Multi-domain alignment can be realized even if the alignment control window 26 formed by connecting them symmetrically is provided.

  Even in this configuration, as in the case where the slits 22 are provided, in the region immediately below the alignment control window 26 in the surface of the counter substrate 11b, an electric field that tilts the liquid crystal molecules is not applied, and the liquid crystal molecules are vertical. Orient. On the other hand, in the area around the orientation control window 26 in the surface of the counter substrate 11b, an electric field is generated that spreads away from the orientation control window 26 as the counter substrate 11b is approached. As a result, the liquid crystal molecules are inclined in the direction in which the major axis is perpendicular to the electric field, and the in-plane component in the alignment direction of the liquid crystal molecules is substantially perpendicular to each side of the alignment control window 26 as indicated by arrows in the figure. .

  In any case, the in-plane component in the alignment direction is limited in the 4-domain multi-domain alignment. Therefore, unlike the case of the above-described radial tilt alignment, even when linearly polarized light is incident, the transmitted light can be transmitted by setting the angle between the directions P1 to P4 and the direction of the linearly polarized light to be 45 degrees. It is possible to reduce the number of liquid crystal molecules that cannot give a phase difference to.

  However, even if it is set in this way, the alignment state of the liquid crystal molecules tends to be disturbed in the boundary region between domains (such as B12) or the outer edge region of the pixel electrode 21a. There is a possibility that the number of liquid crystal molecules that cannot give a phase difference to transmitted light increases because the direction of linearly polarized light and the in-plane component in the alignment direction match.

  Specifically, in the boundary region, the liquid crystal molecules are aligned so as to be supported by the liquid crystal molecules existing in the domains on both sides, so the alignment of the liquid crystal molecules is not fixed and is in an unstable state. As a result, when the balance of the alignment regulating force from the domains on both sides is broken by a slight trigger, the alignment state of the boundary region changes (inclines). Here, the balance changes not only due to a slight variation in the orientation regulating force in the manufacturing process but also due to a lateral electric field caused by a voltage applied to the gate signal line and the source signal line, deterioration with time, and the like. Therefore, the change in the orientation state is not only different for each part in the boundary region, but is also different for each picture element. As a result, when linearly polarized light is incident, there is a possibility that it will be visually recognized as rough. For example, when linearly polarized light is incident on the liquid crystal cell shown in FIG. 25, a disclination line DL is generated in the alignment control window 26 along the absorption axis direction (crossed Nicols) of the linearly polarizing film 12a (12b). Since the state of the disclination line DL is different for every pixel and every pixel, there is a possibility that the roughness is visually recognized.

  In the edge region, the alignment state continuously changes, and is more susceptible to an external electric field such as an electric field from a source signal line or a gate signal line than the central portion of the pixel electrode 21a. In addition, when the orientation is controlled by the wall structure, it is easily subjected to three-dimensional strain. As described above, since the edge region is easily affected by the surroundings, the alignment regulating force is likely to be non-uniform, and the alignment state of the liquid crystal molecules is likely to change (tilt). This change in the orientation state is not only different for each part in the boundary region, but is also different for each pixel. As a result, when linearly polarized light is incident on a liquid crystal layer having a multi-domain configuration, the alignment state may be visually perceived as rough.

  In contrast, in each of the above embodiments, circularly polarized light is incident on the multi-domain aligned liquid crystal cell by the λ / 4 plate 13a. As a result, even if the alignment state of the liquid crystal molecules is disturbed, as in the case of the radially inclined alignment, as long as the alignment direction and viewing angle of the liquid crystal molecules do not match not only the in-plane component but also the substrate normal component, the liquid crystal molecule M Can contribute to the display. Thereby, for example, even when the liquid crystal cell of FIG. 25 is used, the disclination line DL is hardly observed in the alignment control window 26. As a result, as a result of using a multi-domain alignment liquid crystal layer to ensure a wide viewing angle, not only the edge region of the pixel electrode 21a but also the boundary region of the domain is present, and there is no roughness and the display A high-quality liquid crystal display device can be realized.

  Further, in the above, as an example of the liquid crystal cell, it has a negative dielectric anisotropy, and as an initial alignment, the liquid crystal molecules are aligned perpendicular to the substrate surface, and the liquid crystal molecules in the pixel are aligned in multiple directions when a voltage is applied. The case where an inclined liquid crystal layer is used has been described as an example, but a nematic liquid crystal having a positive dielectric anisotropy, a smectic liquid crystal, or a cholestic liquid crystal and a horizontal alignment film are combined to form a substrate surface during initial alignment. On the other hand, the liquid crystal cell 11 may be formed so as to be aligned horizontally and in a plurality of directions.

  In any case, a liquid crystal display device using a liquid crystal layer in which the orientation direction is controlled so that in-plane components of the orientation direction of each liquid crystal molecule are different from each other within one pixel in a state where a certain voltage is applied. If so, the alignment state is likely to be disturbed, and when the linearly polarized light is incident, the roughness is easy to visually check, so that substantially the same effect as in the present embodiment can be obtained.

  Furthermore, even in the liquid crystal layer in which the alignment direction of the liquid crystal molecules is controlled so that the alignment direction of the liquid crystal molecules in the pixel is a single direction, at the edge portion of the pixel, for example, a source signal line or a gate signal line The orientation direction may be disturbed by an oblique electric field from the bus wiring. In the case where the orientation is controlled by the wall structure, if a three-dimensional strain is generated by a wiring provided around the pixel, the orientation state may be disturbed and roughening may occur. Therefore, a certain degree of effect can be obtained if the liquid crystal display device uses liquid crystal layers in which in-plane components in the alignment direction of each liquid crystal molecule are different from each other in a state where a certain voltage is applied.

  However, in a liquid crystal layer in which the alignment direction is controlled such that the in-plane components of the alignment direction of each liquid crystal molecule are different from each other within one pixel in a state where a certain voltage is applied, such as multi-domain alignment and radial tilt alignment. If present, the alignment state is likely to be disturbed and the display quality is likely to be deteriorated as compared with a liquid crystal layer in which the alignment direction is controlled to be a single direction. Therefore, the display quality can be further improved when the circularly polarized light is incident on the liquid crystal layer.

  In addition, a vertical alignment type liquid crystal cell has a higher display contrast and a faster monochrome level response speed than a TN (Twisted Nematic) type liquid crystal cell. Furthermore, the in-plane orientation dependence of the viewing angle can be suppressed by combining radial tilt orientation or multi-domain orientation. Therefore, liquid crystal satisfying all of contrast, response speed, viewing angle, in-plane orientation dependence of viewing angle and display quality by entering circularly polarized light into a multi-domain or radially tilted liquid crystal cell in the vertical alignment method. A display device can be realized. In particular, the radial tilt alignment is easier to visually recognize when combined with linearly polarized light than the multi-domain alignment, but has less in-plane orientation dependency. Therefore, as in the present embodiment, by entering substantially circularly polarized light and suppressing roughness, a liquid crystal display device with less in-plane orientation dependency can be realized without deteriorating display quality.

  As a configuration example showing another alignment state, in the case of a liquid crystal cell of a monodomain alignment and a vertical alignment mode, as shown in FIG. 26, unlike FIG. 2 and FIG. 22 to FIG. 25, the pixel electrode 21a and the counter electrode 22b are The slits 22 and the like are not provided and are formed flat. In FIG. 26, vertical alignment films 27a and 27b provided on the TFT substrate 11a and the counter substrate 11b are illustrated.

  Further, in the case of a liquid crystal cell of monodomain alignment, unlike a liquid crystal cell of multidomain alignment or radial tilt alignment, a rubbing process is provided in the manufacturing process, and the rubbing direction of the liquid crystal molecules in the liquid crystal layer 11c is set to both substrates 11a. -It is set to be antiparallel at 11b. Further, the liquid crystal cell 11 and the linearly polarizing films 12a and 12b are arranged so that the rubbing direction and the absorption axis AAa (AAb) of the linearly polarizing films 12a and 12b are at an angle of 45 degrees.

  In the above configuration, when no voltage is applied, as shown in FIG. 26, the liquid crystal molecules that are aligned in the substrate normal direction (vertical) have a voltage between the pixel electrode 21a and the counter electrode 21b as shown in FIG. Tilt with application. However, in this configuration, since it is monodomain alignment, as shown in FIG. 28, each liquid crystal molecule in the pixel is basically aligned only in one direction. In the figure, the alignment direction of the liquid crystal molecules is indicated by an arrow whose tip is the direction in which the liquid crystal molecules are lowered.

  However, even in the above-described monodomain alignment, in the peripheral portion of the pixel electrode 21a, the electric field is distorted due to the influence from the source bus line 28a and the gate bus line 28b, and the alignment direction of the liquid crystal molecules at the time of voltage application is disturbed. There is a risk of deviation from the direction. Here, as described above, in the configuration without the λ / 4 plates 13a and 13b, when the absorption axis AAa (AAb) and the alignment direction of the liquid crystal molecules coincide with each other in the in-plane direction component, the presence of the liquid crystal molecules exists. Since the area to be blackened becomes black, a black area α occurs in the peripheral portion of the pixel electrode 21a as shown in FIG.

  On the other hand, in the liquid crystal display device according to this modification, since the λ / 4 plates 13a and 13b are provided, the liquid crystal molecules are not black unless the alignment direction of the liquid crystal molecules coincides with the absorption axis AAa (AAb). As shown in FIG. 30, only the region where the liquid crystal molecules remain perpendicular to the substrate is black at the boundary region between the regions where the alignment directions of the liquid crystal molecules are different from each other. Therefore, the area of the region α that becomes black can be greatly reduced.

  Further, similarly to the above-described embodiments, the retardation Rth1 in the thickness direction in the range from the linearly polarizing film 12a (12b) to the λ / 4 plate 13a (13b) including the λ / 4 plate 13a (13b) is substantially 0. (At least less than λ / 8), a liquid crystal display device capable of maintaining a wide viewing angle without impairing the balance of the viewing angle characteristics of the upper, lower, left, and right sides and preventing the reduction of the contrast ratio in the front direction. realizable.

  Further, in the liquid crystal cell 11 of the liquid crystal display device of monodomain alignment and horizontal alignment mode, as shown in FIG. 31, a liquid crystal layer 11d made of liquid crystal having positive dielectric anisotropy is used instead of the liquid crystal layer 11c. It has been. The TFT substrate 11a and the counter substrate 11b are provided with horizontal alignment films 27c and 27d instead of the vertical alignment films 27a and 27b. Similarly to FIG. 25, the pixel electrode 21a and the counter electrode 21b are formed flat, and the rubbing direction is set to be antiparallel (parallel and reverse in direction) between the substrates 11a and 11b. Yes.

  Furthermore, in the liquid crystal display device according to this modification, as shown in FIG. 32, liquid crystal compensation plates 14c to 14f are provided instead of the liquid crystal compensation plates 14a, 14b, or 14 described above. The liquid crystal compensation plates 14c and 14d are formed so as to have positive uniaxial optical anisotropy (nx> ny = nz), and are arranged so as to sandwich the liquid crystal cell 11 therebetween. The liquid crystal compensators 14e and 14f are formed so as to have negative uniaxial optical anisotropy (nx = ny> nz), and are arranged so as to further sandwich the liquid crystal compensators 14c and 14d. . Further, the y-axis of each of the liquid crystal compensators 14c to 14f is arranged so as to coincide with the rubbing direction.

  In this modification, as an example, the liquid crystal cell 11 having the refractive index anisotropy Δn of the liquid crystal layer 11d of 0.09, the cell thickness d = 3.0 μm, and d · Δn = 270 nm is used. The retardation in the in-plane direction of the liquid crystal compensation plate 14c (14d) can cancel the residual retardation value (15 nm) of the liquid crystal layer 11d when black display is performed (when 5 V is applied). In addition, the total of both the members 14c and 14d is set to d · (nx−ny) = 15 nm. Furthermore, since the retardation in the thickness direction of the liquid crystal compensator 14e (14f) compensates for a retardation of about 70% of d · Δn (270 nm) of the liquid crystal cell 11, a good viewing angle can be obtained. The total of both members 14e and 14f is set to d (nx−nz) = 100 nm. In addition, this numerical value is a case where the retardation (for example, 40 nm respectively) of the support body of linearly polarizing film 12a * 12b is not compensated like 3rd Embodiment, for example, 270 * 0.7-40 * 2 was determined to be about 100 nm.

  In the above configuration, when no voltage is applied between the electrodes 21a and 21b, the liquid crystal molecules in the liquid crystal layer 11d are along the surfaces of the substrates 11a and 11b so as to be along the rubbing direction as shown in FIG. Oriented in the direction. However, as in FIG. 28, as shown in FIG. 33, in the peripheral portion of the pixel electrode 21a, the electric field is distorted and the orientation direction is deviated from the rubbing direction due to the influence from the source bus line 28a and the gate bus line 28b. Unlike the case of the vertical alignment, since it is along the rubbing direction, it is not aligned reverse to the rubbing direction even in the vicinity of the gate bus line 28b. On the other hand, when a voltage is applied between the electrodes 21a and 21b, the liquid crystal molecules in the liquid crystal layer 11d are inclined in the substrate normal direction, as shown in FIG. Thus, since the tilt direction of the liquid crystal molecules changes according to the voltage, the brightness of the pixel can be controlled as in the case of the vertical alignment.

  Also in this case, as in FIG. 29, without the λ / 4 plates 13a and 13b, as shown in FIG. 35, in the region where the alignment of the liquid crystal molecules is disturbed, such as the peripheral portion of the pixel electrode 21a, When the absorption axis AAa (AAb) of the linearly polarizing film 12a (12b) coincides in the in-plane direction, the region where the liquid crystal molecules exist becomes black. On the other hand, when the λ / 4 plates 13a and 13b are provided, in the horizontal alignment mode, there are no liquid crystal molecules that are vertically aligned when no voltage is applied. Due to the retardation Rth1 in the thickness direction, the retardation for liquid crystal compensation (thickness direction) cannot be made sufficiently close to the liquid crystal cell 11, and the viewing angle may be limited.

  On the other hand, in the liquid crystal display device according to the present modification, the retardation Rth1 is set to substantially 0 (at least less than λ / 8) as in the above embodiments, so that the λ / 4 plates 13a and 13b. In spite of being provided, it is possible to realize a liquid crystal display device capable of maintaining a wide viewing angle and preventing a reduction in contrast ratio in the front direction without impairing the balance of the viewing angle characteristics in the vertical and horizontal directions.

  In the above description, the case where the liquid crystal cell 11 in the horizontal alignment mode is optically compensated by the liquid crystal compensators 14c to 14f has been described, but other retardation layers may be used as long as the optical compensation can be performed. For example, in the configuration shown in FIG. 37, instead of the liquid crystal compensation plates 14 c to 14 f, liquid crystal compensation plates 14 g and 14 h made of an inclined retardation film are provided on both sides of the liquid crystal cell 11.

  The liquid crystal compensators 14g and 14h have an original refractive index ellipsoid of na = nb> nc, the rubbing orthogonal direction (in the substrate plane) is the x axis, the rubbing direction (in the substrate surface) is the y axis, and the substrate direction is When the z axis is defined, the a axis is parallel to the x axis, and the b axis is formed at a predetermined angle θ with the y axis. In this case, the angle between the c-axis and the z-axis is also θ. In this example, for example, each of the liquid crystal compensators 14g and 14h is formed of an inclined retardation film having na = nb = 1.5, nc = 1.497, θ = 35 degrees, and a film thickness d = 50 μm. Yes. Even in this case, since the liquid crystal cell 11 is optically compensated by the liquid crystal compensators 14g and 14h, the same effect as the configuration of FIG. 32 can be obtained.

  As another modification, a case where a liquid crystal cell of monodomain alignment is used in an OCB (Optically Compensated Bend) mode will be described. As shown in FIG. 38, the liquid crystal cell according to this modification is used. 11 includes a liquid crystal layer 11d having a positive dielectric anisotropy and horizontal alignment films 27c and 27d as in FIG. However, unlike FIG. 31, the liquid crystal cell 11 is formed so that the rubbing direction is parallel between the two substrates 11a and 11b.

  Further, in the liquid crystal display device using the liquid crystal cell 11, liquid crystal compensation plates 14i and 14j are arranged on both sides of the liquid crystal cell 11 instead of the liquid crystal compensation plates 14c to 14f, as shown in FIG. Both the liquid crystal compensators 14i and 14j are each composed of a retardation layer having biaxial optical anisotropy, and each main refractive index is set to nx> ny> nz. In this example, in order to compensate for the retardation in the thickness direction of the liquid crystal cell 11, d · ((nx + ny) / 2−nz) is set to 230 nm, and in order to cancel the residual retardation during black display, d · (nx−ny) = 40 nm is set. These numerical values were derived as optimum values for optical compensation of the liquid crystal cell 11 by optical simulation. The liquid crystal cell 11 and the liquid crystal compensation plates 14i and 14j are arranged so that the y-axis of the liquid crystal compensation plates 14i and 14j and the rubbing direction coincide.

  In the above configuration, when no voltage is applied, the liquid crystal molecules of the liquid crystal layer 11d are aligned so that the retardation given to the transmitted light is canceled between the TFT substrate 11a side and the counter electrode 21b side from the center position in the thickness direction. In the same manner as in the horizontal alignment mode, white display is performed. In this case, as in the horizontal alignment mode, the alignment disorder of the liquid crystal molecules occurs in the peripheral portion of the pixel electrode 21a. On the other hand, when a voltage is applied to the liquid crystal cell 11, the liquid crystal molecules in the liquid crystal layer 11d are vertically aligned except in the vicinity of both substrates 11a and 11b as shown in FIG. Black display.

  Even in this case, as in the case of the horizontal alignment mode, the λ / 4 plates 13a and 13b do not generate black regions due to the alignment disorder, and the retardation Rth1 is substantially 0 (as in the above embodiments). At least less than λ / 8). Therefore, it is possible to realize a liquid crystal display device that can maintain a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, and can prevent a reduction in the contrast ratio in the front direction.

  In the OCB mode, as in the horizontal alignment mode, as shown in FIG. 41, instead of the liquid crystal compensators 14i and 14j, liquid crystal compensators 14k and 14m made of tilted retardation films are used. The cell 11 can be optically compensated. In this example, by optical simulation, for example, an inclination type retardation film having na = nb = 1.5, nc = 1.497, θ = 35 degrees, and a film thickness d = 110 μm. Is forming. Even in this case, since the liquid crystal cell 11 is optically compensated by the liquid crystal compensators 14k and 14m, the same effect as the configuration of FIG. 39 can be obtained.

  In the above description, the retardation of the λ / 4 plates 13a and 13b is set to ¼ of the wavelength of the transmitted light so that the incident light is circularly polarized. However, the present invention is not limited to this. Even if it is not completely circularly polarized, if the deviation is such that the brightness does not decrease so much and the roughness does not occur, the retardation in the in-plane direction is set to approximately one-fourth of the wavelength of the transmitted light. Circularly polarized elliptically polarized light may be incident. As an example, if the rate of change in brightness at the wavelength with the highest visibility (550 nm) is within 10%, that is, if the transmittance is 0.9 or more, a decrease in brightness is not easily recognized by the observer. The graininess is also difficult to see. When the retardation range satisfying this condition is derived by measuring transmittance (simulation), the retardation of the λ / 4 plates 13a and 13b is optimal if it is 135 nm with respect to light near 550 nm, If it is in the range of 95 nm to 175 nm, the same effect can be obtained even if it is not completely circularly polarized.

  As described above, the liquid crystal display device according to any one of the above embodiments is a liquid crystal display device including a liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell, and solves the above problems. Therefore, a quarter-wave layer that is arranged between each of the polarizing elements and the liquid crystal cell and in which the retardation in the in-plane direction is set to approximately a quarter wavelength of the wavelength of transmitted light, 4 which is disposed between at least one of the half-wavelength layers and the liquid crystal cell, has retardation in the thickness direction, optically compensates for the liquid crystal cell, and at least the liquid crystal compensation layer. A compensation layer provided between the quarter wavelength layer and the polarizing element, and the retardation value in the thickness direction of the compensation layer includes the quarter wavelength layer and is a quarter of that from the polarizing element. Thickness in the range up to the wavelength layer Out of retardation, it is characterized in that the sum excluding the compensation layer and the negative is set in reverse.

  In addition, the liquid crystal display device according to any of the above embodiments is a liquid crystal display device including a liquid crystal cell in a vertical alignment mode and polarizing elements disposed on both sides of the liquid crystal cell. In order to do so, a quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of the transmitted light, The main refractive index nz1 is the smallest when the main refractive index in the in-plane direction is nx1, ny1, and the main refractive index in the normal direction is nz1, which is arranged between at least one of the quarter-wave layers and the liquid crystal cell. Provided between the retardation layer and at least the quarter wavelength layer on which the retardation layer is provided and the polarizing element, the main refractive index in the in-plane direction is nx2, ny2, the main refractive index in the normal direction Where nz2 is the main refractive index nz2 It is characterized by and a deal of compensation layer.

  Furthermore, the liquid crystal display device according to any of the above embodiments is a liquid crystal in a horizontal alignment mode having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell. In order to solve the above-described problem, the display device is disposed between each of the polarizing elements and the liquid crystal cell, and the retardation in the in-plane direction is set to approximately a quarter wavelength of the wavelength of transmitted light. A quarter-wave layer, at least one of the quarter-wave layer and a positive uniaxial retardation layer disposed between the liquid crystal cells, at least one of the quarter-wave layer and liquid crystal Provided between the negative uniaxial retardation layer disposed between the cells and the quarter wavelength layer and the polarizing element on which at least one of the retardation layers is provided, and in the in-plane direction. The main refractive index is nx2, ny2, and the main refractive index in the normal direction is n When 2, is characterized in that the main refractive index nz2 is a largest compensation layer. Instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, An inclined retardation layer may be provided in which the na axis coincides with the in-plane rubbing orthogonal direction and the nc axis is inclined at a predetermined angle from the normal direction.

  The liquid crystal display device according to any of the above embodiments includes an optically compensated bend mode including a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell. In order to solve the above problems, the liquid crystal display device is arranged between each of the polarizing elements and the liquid crystal cell, and the retardation in the in-plane direction is set to approximately a quarter wavelength of the wavelength of the transmitted light. The quarter wavelength layer is arranged between at least one of the quarter wavelength layer and the liquid crystal cell, and the main refractive index in the in-plane direction is nx1, ny1, and the main refractive index in the normal direction is When nz1, it is provided between the retardation layer of nx1> ny1> nz1 and at least the quarter wavelength layer on which the retardation layer is provided and the polarizing element, and the main refractive index in the in-plane direction is nx2, ny2, the main refractive index in the normal direction is nz2. When, is characterized in that the main refractive index nz2 is a largest compensation layer. Instead of the retardation layer, the original refractive index ellipsoid is na = nb> nc and the na axis is in-plane rubbing between at least one of the quarter-wave layers and the liquid crystal cell. An inclined retardation layer may be provided that is aligned with the orthogonal direction and inclined so that the nc axis forms a predetermined angle from the normal direction.

  According to these configurations, since light that has passed through the polarizing element and the quarter-wave layer is incident on the liquid crystal cell, substantially circular polarized light is incident on the liquid crystal cell, and light emitted from the liquid crystal cell is divided into four minutes. After a phase difference of approximately a quarter wavelength is given by the one wavelength layer, the light is emitted through the polarizing element.

  Here, when the voltage between the pixel electrode and the counter electrode is a predetermined voltage, such as an initial alignment state when a voltage is applied or no voltage is applied, the liquid crystal cell corresponds to the alignment state of the liquid crystal molecules. Since the phase difference is given to the transmitted light, the circularly polarized light is converted into elliptically polarized light. Therefore, even if it passes through the quarter wavelength layer, it does not return to linearly polarized light, and a part of the emitted light of the quarter wavelength layer is emitted from the polarizing element. As a result, the amount of light emitted from the polarizing element can be controlled according to the applied voltage, and gradation display is possible.

  Furthermore, since substantially circularly polarized light is incident, even if alignment disorder occurs in the liquid crystal molecules, the alignment direction of the liquid crystal molecules and the transmitted light do not match in both the in-plane component and the substrate normal direction. As long as the liquid crystal molecules can give a phase difference to the transmitted light, high light utilization efficiency can be secured.

  On the other hand, when the liquid crystal molecules of the liquid crystal cell are aligned in the substrate normal direction (vertical), the liquid crystal cell cannot give a phase difference to the transmitted light. As a result, the transmitted light is emitted while maintaining substantially circularly polarized light. The emitted light is converted into linearly polarized light in the quarter wavelength layer, and then input to the polarizing element to limit transmission. Therefore, the liquid crystal display device can display black.

  However, even if the liquid crystal molecules are aligned vertically, when viewed from an oblique direction inclined by a polar angle from the substrate normal direction, the alignment direction of the liquid crystal molecules and the direction of transmitted light do not match, and the liquid crystal cell is A phase difference corresponding to the polar angle is given to the transmitted light. However, in each of the above configurations, a retardation layer having retardation in the thickness direction is provided, and the liquid crystal cell can be optically compensated. Therefore, a wide viewing angle can be maintained.

  Further, in the above configuration, a compensation layer having a retardation in the thickness direction opposite to that of the quarter wavelength layer or the retardation layer is disposed between the polarizing element and the quarter wavelength layer. Yes. Therefore, for example, a member that functions in the same optical activity as the retardation layer, such as a support for the polarizing element, is interposed between the polarizing element and the quarter-wave layer, or a quarter-wave layer is provided. Even if it has retardation in the thickness direction, the retardation of these members can be canceled by the compensation layer.

  As a result, even if the total retardation in the thickness direction from the polarizing element to the liquid crystal cell and from the liquid crystal cell to the polarizing element is the same, Since the absolute value of the retardation in the thickness direction in the range up to 1 / wavelength layer can be reduced, the compensation retardation (thickness direction) of the liquid crystal cell is made closer to the liquid crystal cell than in the case without the compensation layer. be able to. Therefore, light leakage during black display can be prevented and good black display can be achieved. In addition, unlike the case of using a quarter-wave layer having positive and negative optical activities, the same type of quarter-wave layer can be used, so that both in-plane retardation can be easily aligned. The contrast ratio in the front direction can be improved.

  In addition, since the retardation (absolute value) in the thickness direction within the above range can be reduced, when the contrast ratio at a predetermined angle from the normal direction is measured over all in-plane directions, the peak value of the contrast ratio is the same value. It is easy to balance the viewing angle characteristics of the top, bottom, left and right.

  In addition, in the case of these configurations, a quarter-wave layer is created with a retardation film represented by a biaxial refractive index ellipsoid, and the characteristics of the negative film are added to the quarter-wave layer. The quarter wavelength layer can also be used as a negative film. Even in this case, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to that of the liquid crystal cell, so that a good black display can be achieved.

  Further, in addition to the configuration in which the retardation layer for optical compensation of the liquid crystal cell is provided, the thickness direction is at least between the quarter wavelength layer and the polarizing element on which the retardation layer is provided. It is preferable that a polarizing element compensation layer is provided that has retardation in the in-plane direction and optically compensates the polarizing element with retardation in the in-plane direction. In the case of the configuration in which the compensation layer having the largest main refractive index nz2 is provided, there is at least an in-plane direction between the quarter-wave layer and the polarizing element on which the retardation layer is provided. When the main refractive index is nx3, ny3, and the main refractive index in the normal direction is nz3, nx3> ny3, and the polarizing axis on the same side with respect to the liquid crystal cell is parallel to the ny3 axis. It is desirable to provide a polarizing element compensation layer set as described above.

  According to these configurations, the polarizing element can be optically compensated by the polarizing element compensation layer. For example, when the absorption axis of the polarizing element and the y axis of the polarizing element compensation layer are arranged in parallel, the liquid crystal display device having the polarizing elements whose absorption axes are orthogonal to each other is inclined from the in-plane orientation of 45 degrees of the absorption axis. Light leakage when seen can be suppressed. Furthermore, since the retardation in the thickness direction of the polarizing element compensation layer can be canceled by the compensation layer, the retardation for compensation of the liquid crystal cell (thickness direction) is provided despite the provision of the polarizing element compensation layer. ) Can be brought closer to the liquid crystal cell. As a result, in all in-plane directions, light leakage during black display can be prevented, and a liquid crystal display device capable of displaying black well can be realized.

  In the case of a configuration in which a compensation layer having the largest main refractive index nz2 is provided, it is desirable that each main refractive index of the compensation layer is set to nx2 = ny2 <nz2. According to this configuration, since the retardation in the in-plane direction of the compensation layer is 0 nm, the coloring phenomenon that occurs when the in-plane retardation exists can be prevented and the contrast ratio can be maintained at a high value.

  Further, when the main refractive index in the in-plane direction is set to nx4, ny4 and the main refractive index in the normal direction is set to nz4 as the quarter wavelength layer instead of providing the compensation layer having the above-described configuration, (nx4 + ny4) A quarter wavelength layer with / 2 being approximately nz4 may be used.

  In this configuration, retardation in the thickness direction of the quarter wavelength layer is suppressed to substantially zero. Therefore, similarly to each liquid crystal display device described above, even if the total retardation in the thickness direction from the polarizing element to the liquid crystal cell and from the liquid crystal cell to the polarizing element is the same, The retardation of the thickness direction from the said polarizing element to a quarter wavelength layer can be reduced including a layer. Thereby, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell. As a result, a liquid crystal display device capable of maintaining a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, and preventing a decrease in the contrast ratio in the front direction, as in the case where the compensation layer is provided. realizable.

  Further, regardless of whether (nx4 + ny4) / 2 of the quarter-wave layer is set to nz4 or not and whether or not the compensation layer is present, the quarter-wave layer including the quarter-wave layer is four minutes from the polarizing element. The absolute value of the retardation in the thickness direction in the range up to one wavelength layer may be set to less than 1/8 of the wavelength of the transmitted light.

  Even in this configuration, the compensation retardation (thickness direction) of the liquid crystal cell can be brought close to the liquid crystal cell as in the above-described liquid crystal display devices. Therefore, similarly to the liquid crystal display devices described above, it is possible to realize a liquid crystal display device that can maintain a wide viewing angle without impairing the balance of the viewing angle characteristics of the top, bottom, left, and right, and can prevent a decrease in the contrast ratio in the front direction.

  Furthermore, it is desirable that the absolute value of the retardation in the thickness direction in the above range is set to substantially zero. According to this configuration, the retardation in the thickness direction effective for optically compensating the liquid crystal cell can be brought closest to the liquid crystal cell, and the display quality of the liquid crystal display device can be improved.

  In addition to the above-described configurations, the liquid crystal cell includes a first substrate provided with a pixel electrode corresponding to a pixel, a second substrate provided with a counter electrode, and a liquid crystal layer provided between the two substrates. And the liquid crystal layer is controlled so that the alignment directions of the liquid crystal molecules are different from each other in the pixel when the voltage between the pixel electrode and the counter electrode is at least a predetermined value. desirable.

  In the above configuration, since the alignment directions of the liquid crystal molecules are different from each other in the pixel, regions where liquid crystal molecules having different alignment directions are present can optically compensate for each other. As a result, the display quality when viewed from an oblique direction can be improved and the viewing angle can be expanded.

  Here, in the liquid crystal layer, as a result of controlling the alignment directions of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, disorder of the alignment state is likely to occur. Therefore, in the case of a conventional liquid crystal display device in which linearly polarized light is incident on the liquid crystal layer and light emitted from the liquid crystal layer is incident on the analyzer, the alignment of the liquid crystal molecules is disturbed, and the in-plane component in the alignment direction is reduced. If it coincides with the absorption axis of the polarizing element, the liquid crystal molecules cannot give a phase difference to the transmitted light regardless of the component in the normal direction of the substrate. Therefore, the region where the liquid crystal molecules are present cannot contribute to the improvement of brightness, and roughness or the like occurs. In addition, since the liquid crystal molecules whose in-plane components in the alignment direction coincide with the absorption axis of the analyzer cannot contribute to the improvement in brightness, the light utilization efficiency (effective aperture ratio) decreases. As a result, it is difficult to ensure the contrast ratio and increase the number of gradations.

  On the other hand, in the liquid crystal display device configured as described above, since substantially circularly polarized light is incident on the liquid crystal layer, there is no anisotropy in the alignment direction of the liquid crystal layer, and the alignment direction of the liquid crystal molecules and the transmitted light are As long as both the inner component and the substrate normal direction do not match, the liquid crystal molecules can give a phase difference to the transmitted light.

  Therefore, as a result of controlling the alignment direction of the liquid crystal molecules to be different from each other in the pixel in order to ensure a wide viewing angle, the alignment direction of the liquid crystal molecules whose alignment is disturbed despite the fact that the alignment state is likely to be disturbed. As long as it does not match, it can contribute to the improvement of brightness. As a result, high light utilization efficiency can be secured while maintaining a wide viewing angle.

  In addition to the above-described configurations, the main refractive indexes nx1 and ny1 of the retardation layer are preferably set to nx1 = ny1. According to this configuration, since the retardation in the in-plane direction of the retardation layer is 0 nm, the coloring phenomenon that occurs when the in-plane retardation exists can be prevented, and the contrast ratio can be maintained at a high value.

  On the other hand, instead of setting nx1 = ny1, the retardation layer is arranged between the quarter-wave layer and the liquid crystal cell, and the respective main refractive indexes nx1, ny1 are different from each other. The nx1 axes of the two retardation layers may be orthogonal to each other, and the ny1 axes of the two retardation layers may be orthogonal to each other.

  In this configuration, the nx1 axis and the ny1 axis of the retardation layers arranged on both sides of the liquid crystal cell are orthogonal to each other. Therefore, the retardation in the in-plane direction generated in one retardation layer is canceled out by the other retardation layer. As a result, the coloring phenomenon can be prevented, and the contrast ratio can be maintained at a high value.

In addition to the above-described configurations, it is desirable that both the quarter-wave layers have the same retardation in the thickness direction. According to this configuration, both quarter-wave layers can be manufactured in the same process, so that both characteristics can be easily aligned even if production variations occur. As a result, the productivity of the liquid crystal display device can be improved as compared with the case where a quarter-wave layer having different retardation in the thickness direction is used.
(Configuration 8)
A liquid crystal display device having a liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
A retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell, having retardation in the thickness direction, and optically compensating the liquid crystal cell;
The quarter-wave layer is characterized in that (nx4 + ny4) / 2 is approximately nz4 when the main refractive index in the in-plane direction is nx4, ny4 and the main refractive index in the normal direction is nz4. Display device.
(Configuration 9)
A liquid crystal display device having a vertical alignment mode liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
When the main refractive index in the in-plane direction is nx1 and ny1 and the main refractive index in the normal direction is nz1, the main refractive index nz1 is the highest. With a small retardation layer,
The quarter-wave layer is characterized in that (nx4 + ny4) / 2 is approximately nz4 when the main refractive index in the in-plane direction is nx4, ny4 and the main refractive index in the normal direction is nz4. Display device.
(Configuration 10)
A horizontal alignment mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
A positive uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell;
A negative uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell,
The quarter-wave layer is characterized in that (nx4 + ny4) / 2 is approximately nz4 when the main refractive index in the in-plane direction is nx4, ny4 and the main refractive index in the normal direction is nz4. Display device.
(Configuration 11)
Instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, and the na 11. A liquid crystal display according to structure 10, wherein an inclined retardation layer is provided, the axis of which coincides with the in-plane rubbing orthogonal direction and the nc axis is inclined so as to form a predetermined angle from the normal direction. apparatus.
(Configuration 12)
An optically compensated bend mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
It is arranged between at least one of the quarter-wave layers and the liquid crystal cell, where nx1>ny1> nz1 when the main refractive index in the in-plane direction is nx1, ny1 and the main refractive index in the normal direction is nz1. A retardation layer,
The quarter-wave layer is characterized in that (nx4 + ny4) / 2 is approximately nz4 when the main refractive index in the in-plane direction is nx4, ny4 and the main refractive index in the normal direction is nz4. Display device.
(Configuration 13)
Instead of the retardation layer, between at least one of the quarter-wave layers and the liquid crystal cell, the original refractive index ellipsoid is na = nb> nc, and the na axis is in-plane rubbing orthogonal 13. A liquid crystal display device according to constitution 12, wherein an inclined retardation layer is provided which is aligned with the direction and inclined so that the nc axis forms a predetermined angle from the normal direction.
(Configuration 14)
A liquid crystal display device having a liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
A retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell, having retardation in the thickness direction, and optically compensating the liquid crystal cell;
The absolute value of the retardation in the thickness direction in the range from the polarizing element to the quarter wavelength layer including the quarter wavelength layer is set to less than one eighth of the wavelength of the transmitted light. A liquid crystal display device.
(Configuration 15)
A liquid crystal display device having a vertical alignment mode liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
When the main refractive index in the in-plane direction is nx1 and ny1 and the main refractive index in the normal direction is nz1, the main refractive index nz1 is the highest. With a small retardation layer,
The absolute value of the retardation in the thickness direction in the range from the polarizing element to the quarter wavelength layer including the quarter wavelength layer is set to less than one eighth of the wavelength of the transmitted light. A liquid crystal display device.
(Configuration 16)
A horizontal alignment mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
A positive uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell;
A negative uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell,
The absolute value of the retardation in the thickness direction in the range from the polarizing element to the quarter wavelength layer including the quarter wavelength layer is set to less than one eighth of the wavelength of the transmitted light. A liquid crystal display device.
(Configuration 17)
Instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, and the na 17. A liquid crystal display according to the structure 16, wherein an inclined retardation layer is provided, the axis of which coincides with the in-plane rubbing orthogonal direction and the nc axis is inclined so as to form a predetermined angle from the normal direction. apparatus.
(Configuration 18)
An optically compensated bend mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
It is arranged between at least one of the quarter-wave layers and the liquid crystal cell, and when nx1 and ny1 are the main refractive indices in the in-plane direction and nz1 is the main refractive index in the normal direction, nx1>ny1> nz1 A retardation layer,
The absolute value of the retardation in the thickness direction in the range from the polarizing element to the quarter wavelength layer including the quarter wavelength layer is set to less than one eighth of the wavelength of the transmitted light. A liquid crystal display device.
(Configuration 19)
Instead of the retardation layer, between at least one of the quarter-wave layers and the liquid crystal cell, the original refractive index ellipsoid is na = nb> nc, and the na axis is in-plane rubbing orthogonal 19. A liquid crystal display device according to configuration 18, further comprising an inclined retardation layer which is aligned with the direction and inclined so that the nc axis forms a predetermined angle from the normal direction.
(Configuration 20)
20. The liquid crystal display device according to the structure 14, 15, 16, 17, 18, or 19, wherein the absolute value of the retardation in the thickness direction in the above range is set to substantially zero.
(Configuration 21)
The liquid crystal cell includes a first substrate provided with a pixel electrode corresponding to a pixel, a second substrate provided with a counter electrode, and a liquid crystal layer provided between the two substrates.
The liquid crystal layer is controlled such that the orientation directions of the liquid crystal molecules are different in the pixel when the voltage between the pixel electrode and the counter electrode is at least a predetermined value. 20. The liquid crystal display device according to any one of items 1 to 19.
(Configuration 22)
20. The liquid crystal display device according to any one of Structures 8 to 19, wherein the main refractive indexes nx1 and ny1 of the retardation layer are set to nx1 = ny1.
(Configuration 23)
The retardation layer is disposed between the quarter-wave layer and the liquid crystal cell, and the main refractive indexes nx1 and ny1 are different from each other.
20. The liquid crystal display according to claim 8, wherein the nx1 axes of the two retardation layers are orthogonal to each other, and the ny1 axes of the two retardation layers are orthogonal to each other. apparatus.
(Configuration 24)
The liquid crystal display device according to any one of Structures 8 to 19, wherein both the quarter-wave layers have the same retardation in the thickness direction.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1, showing an embodiment of the present invention, is a schematic diagram showing a main part configuration of a liquid crystal display device. FIG. 2 is a perspective view illustrating a configuration example of the liquid crystal display device and illustrating a pixel electrode and a counter electrode. It is a schematic diagram which shows the comparative example of this invention and shows the principal part structure of a liquid crystal display device. It is explanatory drawing which shows the example of a display of the said liquid crystal display device. It is explanatory drawing which shows the example of a display of the liquid crystal display device which concerns on the said embodiment. It is a schematic diagram which shows the other comparative example of this invention and shows the principal part structure of a liquid crystal display device. It is explanatory drawing which shows the evaluation method of contrast ratio in a liquid crystal display device. It is a graph which shows the contrast ratio of the liquid crystal display device which concerns on the said comparative example. It is a graph which shows the contrast ratio of the liquid crystal display device which concerns on the said embodiment. The modification of the said embodiment is shown and it is a schematic diagram which shows the principal part structure of a liquid crystal display device. It is a graph which shows the contrast ratio of the liquid crystal display device which concerns on the said modification. The other modification of the said embodiment is shown and it is a schematic diagram which shows the principal part structure of a liquid crystal display device. It is a schematic diagram which shows the other comparative example of this invention, and shows the principal part structure of a liquid crystal display device. It is a graph which shows the contrast ratio of the liquid crystal display device which concerns on the said comparative example. It is a schematic diagram which shows another comparative example of this invention and shows the principal part structure of a liquid crystal display device. It is a graph which shows the contrast ratio of the liquid crystal display device which concerns on the said comparative example. FIG. 24, which shows another embodiment of the present invention, is a schematic diagram illustrating a configuration of main parts of a liquid crystal display device. It is a graph which shows the contrast ratio of the said liquid crystal display device. It is a graph which shows the contrast ratio of the said liquid crystal display device using another numerical example. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram illustrating a configuration of a main part of a liquid crystal display device according to a reference embodiment of the present invention. It is a graph which shows the contrast ratio of the said liquid crystal display device. It is a perspective view which shows the other structural example of each said liquid crystal display device, and shows a pixel electrode. It is a perspective view which shows the further another structural example of each said liquid crystal display device, and shows a pixel electrode. FIG. 10 is a plan view showing another configuration example of each of the liquid crystal display devices and showing the vicinity of a pixel electrode. It is a top view which shows the further another structural example of each said liquid crystal display device, and shows the pixel electrode vicinity. It is a schematic diagram which shows another structural example of each said liquid crystal display device, and shows the liquid crystal cell at the time of no voltage application. It is a schematic diagram which shows the said liquid crystal cell at the time of voltage application. It is a top view which shows the pixel electrode vicinity of the liquid crystal display device which concerns on the said structural example. FIG. 9 is a diagram illustrating a comparative example of the liquid crystal display device and is an explanatory diagram illustrating a display example when there is no λ / 4 plate. It is explanatory drawing which shows the example of a display of the liquid crystal display device which concerns on the said structural example. It is a schematic diagram which shows another structural example of each said liquid crystal display device, and shows the liquid crystal cell at the time of no voltage application. It is a schematic diagram which shows the said structural example and shows the principal part structure of a liquid crystal display device. It is a top view which shows the pixel electrode vicinity of the liquid crystal display device which concerns on the said structural example. It is a schematic diagram which shows the said liquid crystal cell at the time of voltage application. FIG. 9 is a diagram illustrating a comparative example of the liquid crystal display device and is an explanatory diagram illustrating a display example when there is no λ / 4 plate. It is explanatory drawing which shows the example of a display of the liquid crystal display device which concerns on the said structural example. The modification of the said liquid crystal display device is shown, and it is a schematic diagram which shows the principal part structure of a liquid crystal display device. It is a schematic diagram which shows the further another structural example of each said liquid crystal display device, and shows the liquid crystal cell at the time of no voltage application. It is a schematic diagram which shows the said structural example and shows the principal part structure of a liquid crystal display device. It is a schematic diagram which shows the said liquid crystal cell at the time of voltage application. The modification of the said liquid crystal display device is shown, and it is a schematic diagram which shows the principal part structure of a liquid crystal display device. It is a schematic diagram which shows a prior art and shows the principal part structure of a liquid crystal display device.

1. 1a to 1d Liquid crystal display device 11 Liquid crystal cell 11a TFT substrate (first substrate)
11b Counter board (second board)
11c / 11d Liquid crystal layer 12a / 12b Linearly polarizing film (polarizing element)
13a / 13b λ / 4 plate (quarter wavelength layer)
14.14a-14m Liquid crystal compensation plate (Liquid crystal compensation layer)
15a / 15b Polarizing plate compensation film (polarizing element compensation layer)
16a, 16b Rth compensation film (compensation layer)
21a Pixel electrode 21b Counter electrode

Claims (11)

A liquid crystal display device having a vertical alignment mode liquid crystal cell and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
When the main refractive index in the in-plane direction is nx1 and ny1 and the main refractive index in the normal direction is nz1, the main refractive index nz1 is the highest. A small retardation layer,
When the main refractive index in the in-plane direction is nx2, ny2 and the main refractive index in the normal direction is nz2, provided at least between the quarter wavelength layer on which the retardation layer is provided and the polarizing element. And a compensation layer having the largest main refractive index nz2. A horizontal alignment mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
A positive uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell;
A negative uniaxial retardation layer disposed between at least one of the quarter-wave layers and the liquid crystal cell;
At least one of the above-mentioned retardation layers is provided between the quarter wavelength layer and the polarizing element, the main refractive index in the in-plane direction is nx2, ny2, and the main refractive index in the normal direction is nz2. A liquid crystal display device, comprising: a compensation layer having the largest main refractive index nz2.   Instead of the positive and negative uniaxial retardation layers, the original refractive index ellipsoid is na = nb> nc between at least one of the quarter-wave layers and the liquid crystal cell, and the na 3. A liquid crystal according to claim 2, further comprising an inclined retardation layer having an axis aligned with an in-plane rubbing orthogonal direction and an nc axis inclined at a predetermined angle from a normal direction. Display device. An optically compensated bend mode liquid crystal display device having a liquid crystal cell including a liquid crystal having positive dielectric anisotropy and polarizing elements disposed on both sides of the liquid crystal cell,
A quarter-wave layer disposed between each of the polarizing elements and the liquid crystal cell, the retardation in the in-plane direction being set to approximately a quarter wavelength of the wavelength of transmitted light;
It is arranged between at least one of the quarter-wave layers and the liquid crystal cell, where nx1>ny1> nz1 when the main refractive index in the in-plane direction is nx1, ny1 and the main refractive index in the normal direction is nz1. A retardation layer;
When the main refractive index in the in-plane direction is nx2, ny2 and the main refractive index in the normal direction is nz2, provided at least between the quarter wavelength layer on which the retardation layer is provided and the polarizing element. And a compensation layer having the largest main refractive index nz2.   Instead of the retardation layer, between at least one of the quarter-wave layers and the liquid crystal cell, the original refractive index ellipsoid is na = nb> nc, and the na axis is in-plane rubbing orthogonal 5. A liquid crystal display device according to claim 4, further comprising an inclined retardation layer which is aligned with the direction and inclined so that the nc axis forms a predetermined angle from the normal direction.   6. The liquid crystal display device according to claim 1, wherein each main refractive index of the compensation layer is set to nx2 = ny2 <nz2.   Furthermore, the main refractive index in the in-plane direction is set to nx3, ny3, and the main refractive index in the normal direction is set to nz3 between the quarter wavelength layer and the polarizing element on which at least the retardation layer is provided. When nx3> ny3, there is provided a polarizing element compensation layer set so that the absorption axis of the polarizing element on the same side with respect to the liquid crystal cell and the ny3 axis are parallel to each other. 6. A liquid crystal display device according to claim 1, 2, 3, 4 or 5.   The liquid crystal cell includes a first substrate provided with a pixel electrode corresponding to a pixel, a second substrate provided with a counter electrode, and a liquid crystal layer provided between the two substrates.
  2. The liquid crystal layer according to claim 1, wherein when the voltage between the pixel electrode and the counter electrode is at least a predetermined value, the alignment directions of the liquid crystal molecules are different from each other in the pixel. The liquid crystal display device according to 1, 2, 3, 4 or 5.   6. The liquid crystal display device according to claim 1, wherein the main refractive indexes nx1 and ny1 of the retardation layer are set to nx1 = ny1.   The retardation layer is disposed between the quarter-wave layer and the liquid crystal cell, and the main refractive indexes nx1 and ny1 are different from each other.
  6. The liquid crystal according to claim 1, wherein the nx1 axes of the two retardation layers are orthogonal to each other, and the ny1 axes of the two retardation layers are orthogonal to each other. Display device.   6. The liquid crystal display device according to claim 1, wherein the quarter wavelength layers have the same retardation in the thickness direction.

Images