JP4506183B2 - Liquid crystal device and projection display device - Google Patents

Description

  The present invention relates to a liquid crystal device and a projection display device.

Conventionally, a projection display device (liquid crystal projector) provided with a liquid crystal device in a light valve has been put to practical use as a display device capable of displaying a large screen. However, the conventional liquid crystal projector has a contrast ratio of the projected image of only about 1: 500, which is inferior to the contrast ratio of 1: 3000 of the projector using a mechanical shutter such as DMD (registered trademark). The cause is the viewing angle characteristic of the liquid crystal device. In the first place, in a liquid crystal projector, light incident on the liquid crystal device is not completely parallel light. However, since the liquid crystal device has an incident angle dependency, this causes a reduction in the contrast ratio of the projected image. As a countermeasure against this, in Patent Document 1 below, an optical compensator is used to compensate for the incident angle dependence of the liquid crystal device, and a higher contrast display is realized by the viewing angle compensation effect of the optical compensator.
JP 2001-174776 A

By the way, recently, as a liquid crystal device for a projector has been reduced in size and definition and the aperture ratio has been reduced, a structure including a microlens array that collects light in each pixel has been widely adopted. Such a structure can prevent light leakage from an abnormal alignment portion around the pixel, and thus has an effect of improving the contrast to about 1: 800. For example, Japanese Patent Application Laid-Open No. 2002-14345 discloses an optical compensation method (viewing angle compensation method) suitable for a configuration using a microlens array. The basic idea is that no microlens is provided between the optical compensator and the liquid crystal so that the incident angle of the light incident on the optical compensator becomes equal to the incident angle of the light incident on the liquid crystal. An optical compensation plate is provided on the side of the substrate without a microlens.
However, with this structure, the maximum contrast ratio obtained is about 1: 1000, and further improvement in characteristics is desired.
The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid crystal device and a projection display device capable of obtaining a high contrast ratio.

In order to solve the above problems, a liquid crystal device of the present invention has a plurality of dots that can be displayed independently, and a TN formed by twist-aligning a liquid crystal having positive refractive index anisotropy between a pair of substrates. Type liquid crystal panel, and a liquid crystal device that modulates incident light by changing the orientation of the liquid crystal, wherein a dielectric having negative refractive index anisotropy is hybrid-aligned on the light incident side of the liquid crystal panel A second optical compensation plate is provided, in which a first optical compensation plate is disposed, and a dielectric having negative refractive index anisotropy is hybrid-aligned on the opposite side of the first optical compensation plate from the liquid crystal panel. The first optical compensator has a surface with a larger angle formed by the optical axis of the dielectric of the first optical compensator and the normal of the first optical compensator; The second optical compensation is disposed so as to face the liquid crystal panel. Is arranged such that the surface with the smaller angle formed by the optical axis of the dielectric of the second optical compensation plate and the normal line of the second optical compensation plate faces the liquid crystal panel side. A microlens that can collect incident light on the liquid crystal side is disposed between the first optical compensator and the liquid crystal, corresponding to each dot, and passes through the microlens. By changing the inclination of the light to be transmitted, the direction of the optical axis of the dielectric of the first optical compensator with respect to the incident light from the direction opposite to the alignment regulating direction of the liquid crystal, and the optical axis of the liquid crystal The direction is set closer to each other.

  In the liquid crystal device of the present invention, since the microlens is disposed between the optical compensation plate and the liquid crystal panel, light is incident on the liquid crystal panel at an angle inclined relative to the optical compensation plate. Therefore, when viewed from a predetermined direction, the pretilt angle of the liquid crystal is apparently larger than that of the conventional one, and the viewing angle compensation effect by the optical compensator can be exerted more strongly.

  That is, as the optical compensator as described above, one using a discotic compound as described in Patent Document 1 is well known, but such an optical compensator is manufactured for reasons of manufacturing. Thus, the optical axis of the dielectric cannot be tilted (tilted) with respect to the plate surface, and therefore the optical phase difference generated in the vicinity of the alignment film of the liquid crystal panel cannot be sufficiently compensated. For example, in the conventional optical compensator, the tilt angle of the dielectric relative to the normal of the optical compensator is about 60 ° at the maximum, but it is intended to completely compensate the optical phase generated in the vicinity of the alignment film of the liquid crystal panel. When tilting, the tilt angle needs to be about 80 ° to 88 °. Therefore, in the conventional configuration in which the angles of light incident on the optical compensation plate and the liquid crystal panel are equal, sufficient optical compensation cannot be performed. On the other hand, in the liquid crystal device of the present invention, since the microlens is disposed between the optical compensation plate and the liquid crystal panel and light is incident on the liquid crystal panel at a large angle, the dielectric of the optical compensation plate This makes it possible to make the optical axis of the liquid crystal panel and the optical axis of the liquid crystal of the liquid crystal panel appear to be almost parallel to each other.

In the liquid crystal device of the present invention, the maximum tilt angle of the optical axis of the dielectric relative to the normal line of the first optical compensation plate and the second optical compensation plate is 30 ° or more and 60 ° or less. be able to. By doing so, a contrast ratio higher than the maximum contrast ratio obtained with the conventional configuration can be obtained. In particular, when the maximum value of the tilt angle of the optical axis of the dielectric with respect to the normal line of the first optical compensation plate and the second optical compensation plate is 40 ° or more and 60 ° or less, the contrast characteristic is the most. Get better. This point will be described in the section of [Best Mode for Carrying Out the Invention].

  In the liquid crystal device of the present invention, the liquid crystal panel has a plurality of dots that can be displayed independently, and the microlens that can collect incident light toward the dots corresponds to each dot one by one. It can be set as the provided structure. By doing so, incident light can be condensed for each individual dot, and the light utilization efficiency is the highest.

  In the liquid crystal device of the present invention, as the optical compensation plate, a first optical compensation plate for compensating an optical phase difference generated in a light incident side region of the liquid crystal panel, and a light emission side region of the liquid crystal panel And a second optical compensation plate for compensating for an optical phase difference generated in the above. By doing so, the viewing angle dependency of the liquid crystal device can be further reduced. Note that the region on the light incident side of the liquid crystal panel refers to a region located on the light incident side (that is, on the microlens side) of the liquid crystal layer of the liquid crystal panel with respect to the central portion. Similarly, the region on the light emission side of the liquid crystal panel refers to a region located on the light emission side (that is, the side opposite to the microlens) of the liquid crystal layer of the liquid crystal panel with respect to the central portion.

  The projection display device of the present invention is characterized in that the above-described liquid crystal device is provided as a light modulation means. Thereby, high contrast can be obtained in the projected image.

  Embodiments of the present invention will be described below with reference to the drawings. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size. In the present specification, the liquid crystal layer side of each component of the liquid crystal device is referred to as an inner side, and the opposite side is referred to as an outer side. “When a non-selection voltage is applied” and “when a selection voltage is applied” are respectively “when the applied voltage to the liquid crystal layer is close to the threshold voltage of the liquid crystal” and “the applied voltage to the liquid crystal layer is It means “when sufficiently high compared to the threshold voltage”. In the present specification, the “orientation regulation direction” is defined as follows. That is, the liquid crystal molecules in the vicinity of the alignment film are subjected to an alignment regulation process such as rubbing, so that one end portion (second end portion of the liquid crystal molecules) in the major axis is the other end portion (first end portion of the liquid crystal molecules). In this specification, when the major axis of the liquid crystal is projected onto the substrate surface, the second end of the liquid crystal molecule is projected from the first end of the liquid crystal molecule. The direction toward the end of the liquid crystal is referred to as a liquid crystal alignment regulating direction.

[First Embodiment]
First, a liquid crystal device according to a first embodiment of the present invention will be described with reference to FIGS. The liquid crystal device according to the first embodiment includes a liquid crystal panel in which a liquid crystal layer is sandwiched between a pair of substrates, a pair of polarizing plates respectively disposed outside the liquid crystal panel, and the polarizing plate on the liquid crystal panel and the light incident side. And an optical compensator disposed between the two. In the present embodiment, an active matrix transmissive liquid crystal panel using a thin film transistor (hereinafter referred to as TFT) element as a switching element will be described as an example.

(Equivalent circuit)
FIG. 1 is an equivalent circuit diagram of a liquid crystal panel. In the transmissive liquid crystal panel 60 of the present embodiment, a plurality of dots that can be displayed independently are provided in the image display area, and each of these dot areas arranged in a matrix has a substantially rectangular pixel shape. An electrode 9 is formed. Further, on the side of the pixel electrode 9, a TFT element 30 which is a switching element for performing energization control to the pixel electrode 9 is formed. A data line 6 a is electrically connected to the source of the TFT element 30. Image signals S1, S2,..., Sn are supplied to each data line 6a. The image signals S1, S2,..., Sn may be supplied to each data line 6a in this order, or may be supplied for each group to a plurality of adjacent data lines 6a.

  The scanning line 3 a is electrically connected to the gate of the TFT element 30. Scan signals G1, G2,..., Gm are supplied to the scanning line 3a in pulses at a predetermined timing. The scanning signals G1, G2,..., Gm are applied sequentially to the respective scanning lines 3a in this order. Further, the pixel electrode 9 is electrically connected to the drain of the TFT element 30. When the TFT elements 30 serving as switching elements are turned on for a certain period by the scanning signals G1, G2,..., Gm supplied from the scanning line 3a, the image signals S1, S2,. , Sn are written into the liquid crystal of each pixel at a predetermined timing.

  The predetermined level image signals S1, S2,..., Sn written in the liquid crystal are held for a certain period by a liquid crystal capacitor formed between the pixel electrode 9 and a common electrode described later. In order to prevent leakage of the held image signals S1, S2,..., Sn, a storage capacitor 17 is formed between the pixel electrode 9 and the capacitor line 3b, and is arranged in parallel with the liquid crystal capacitor. . Thus, when a voltage signal is applied to the liquid crystal, the alignment state of the liquid crystal molecules changes depending on the applied voltage level. As a result, the light incident on the liquid crystal is modulated to enable gradation display.

(Planar structure)
FIG. 2 is an explanatory diagram of a planar structure of the liquid crystal panel. In the liquid crystal panel of this embodiment, a rectangular pixel electrode 9 made of a transparent conductive material such as indium tin oxide (hereinafter referred to as ITO) is formed on the TFT array substrate (the outline is indicated by a broken line 9a). Are arranged in a matrix. A data line 6 a, a scanning line 3 a, and a capacitor line 3 b are provided along the vertical and horizontal boundaries of the pixel electrode 9. In the present embodiment, the region in which each pixel electrode 9 is formed is a dot, and the display can be performed for each dot arranged in a matrix.

  The TFT element 30 is formed around a semiconductor layer 1a made of a polysilicon film or the like. A data line 6 a is electrically connected to a source region (described later) of the semiconductor layer 1 a through a contact hole 5. Further, the pixel electrode 9 is electrically connected to the drain region (described later) of the semiconductor layer 1 a through the contact hole 8. On the other hand, a channel region 1a 'is formed in a portion of the semiconductor layer 1a facing the scanning line 3a. The scanning line 3a functions as a gate electrode in a portion facing the channel region 1a '.

  The capacitance line 3b is a data line from the intersection of the main line portion (that is, the first region formed along the scanning line 3a in plan view) extending in a substantially straight line along the scanning line 3a and the data line 6a. And a protruding portion (that is, a second region extending along the data line 6 a when viewed in a plan view) protruding toward the front side (upward in the drawing) along 6 a. In addition, a first light shielding film 11a is formed in a region indicated by a diagonal line rising to the right in FIG. Then, the protruding portion of the capacitor line 3b and the first light shielding film 11a are electrically connected through the contact hole 13 to form a storage capacitor to be described later.

(Cross-section structure)
FIG. 3 is an enlarged view showing a cross section of the liquid crystal panel. As shown in FIG. 3, the liquid crystal panel 60 of the present embodiment is mainly composed of a TFT array substrate 10, a counter substrate 20 disposed so as to face the TFT array substrate 10, and a liquid crystal layer 50 sandwiched therebetween. Yes. The TFT array substrate 10 includes a TFT element 30, a pixel electrode 9, an alignment film 16, and the like inside a substrate body 10 </ b> A made of a translucent material such as glass or quartz. One counter substrate 20 includes a second light shielding film 23, a common electrode 21, and an alignment film 22 inside a substrate body 20 </ b> A made of a translucent material such as glass or quartz. The second light shielding film 23 prevents light incident on the liquid crystal panel from entering the channel region or the like of the TFT element 30. In the formation region of the data line 6 a, the scanning line 3 a, and the TFT element 30 described above. It is formed in a grid at corresponding positions (non-pixel regions). Further, the alignment films 16 and 22 are subjected to an alignment regulation process such as rubbing so that the alignment direction of the liquid crystal molecules when a non-selection voltage is applied can be regulated.

  A microlens array 24 is disposed outside the counter substrate 20. The microlens array 24 is composed of a plurality of microlenses 24a provided one for each dot. Each micro lens 24a has a planar shape on the light incident surface side and a convex shape on the light exit surface side. That is, each micro lens 24a has a positive refractive power, and condenses the light incident from the counter substrate side toward the corresponding pixel electrode 9 (that is, the corresponding dot). For example, the light incident perpendicularly to the incident surface of the liquid crystal panel 60 has an incident angle with respect to the optical axis by the action of each microlens 24a except for the light component passing through the optical axis of each microlens 24a. The light enters the liquid crystal layer 50 in an inclined state. Further, the light incident obliquely on the incident surface of the liquid crystal panel 60 is incident on the liquid crystal layer 50 at an angle more inclined than the incident angle by the action of each microlens 24a. Since the microlens 24a is provided on the light incident side of the liquid crystal panel 60 in this manner, the proportion of incident light absorbed by the second light shielding film 23 is reduced, and a bright display is possible. In FIG. 3, reference numeral 25 denotes an adhesive layer for adhering the microlens array 24 and the substrate body 20A.

  A liquid crystal layer 50 made of nematic liquid crystal is sandwiched between the TFT array substrate 10 thus configured and the counter substrate 20. This nematic liquid crystal exhibits positive dielectric anisotropy, and is horizontally aligned when a non-selection voltage is applied and vertically aligned when a selection voltage is applied. The nematic liquid crystal exhibits positive refractive index anisotropy, and the product (retardation) Δnd of its birefringence and the liquid crystal layer thickness is, for example, about 0.40 μm (60 ° C.). Note that the alignment regulation direction by the alignment film 16 of the TFT array substrate 10 and the alignment regulation direction by the alignment film 22 of the counter substrate 20 are arranged in a twisted state of about 90 ° as shown by arrows 67 and 68 in FIG. (Ie, twist orientation). As a result, the liquid crystal panel 60 of the present embodiment operates in a twisted nematic mode (TN mode).

(Polarizer)
FIG. 4 is an exploded perspective view of the liquid crystal device according to the first embodiment. The liquid crystal device 100 of this embodiment includes the above-described liquid crystal panel 60, a pair of polarizing plates 62 and 64 disposed on the outside of the liquid crystal panel 60, and the liquid crystal panel 60 and one polarizing plate 62, respectively. Two optical compensation plates 70 and 80 are provided. The optical compensators 70 and 80 and the polarizing plates 62 and 64 are mounted on a support (not shown) made of a light-transmitting material having high thermal conductivity such as sapphire glass or quartz, and from the liquid crystal panel 60. They are spaced apart.

  As shown in FIG. 4, a polarizing plate 62 is disposed on the light incident side of the liquid crystal panel 60, and a polarizing plate 64 is disposed on the light emitting side. Each of the polarizing plates 62 and 64 has a function of absorbing linearly polarized light in the absorption axis direction and transmitting linearly polarized light in the transmission axis direction. And each polarizing plate 62 and 64 is arrange | positioned so that each absorption axis and transmission axis may be orthogonal. The light emitting side polarizing plate 64 is arranged such that the absorption axis 65 or the transmission axis thereof substantially coincides with the alignment regulating direction 68 of the alignment film 16 in the light emitting side substrate 10 of the liquid crystal panel 60. The light incident side polarizing plate 62 is arranged such that the absorption axis 63 or the transmission axis thereof substantially coincides with the alignment regulating direction 67 of the alignment film 22 in the light incident side substrate 20 of the liquid crystal panel 60.

  When light enters the liquid crystal device 100 from above the polarizing plate 62, only linearly polarized light that matches the transmission axis of the polarizing plate 62 is transmitted through the polarizing plate 62. In the liquid crystal panel 60 when the non-selection voltage is applied, the liquid crystal molecules are horizontally aligned in a spiral shape. Therefore, the linearly polarized light incident on the liquid crystal panel 60 is rotated about 90 ° and emitted from the liquid crystal panel 60. Since this linearly polarized light coincides with the transmission axis of the polarizing plate 64, it passes through the polarizing plate 64. Therefore, white display is performed on the liquid crystal panel 60 when the non-selection voltage is applied (normally white mode). Further, in the liquid crystal panel 60 when the selection voltage is applied, the liquid crystal molecules are vertically aligned. Therefore, the linearly polarized light incident on the liquid crystal panel 60 is emitted from the liquid crystal panel 60 without being rotated. Since this linearly polarized light is orthogonal to the transmission axis of the polarizing plate 64, it does not pass through the polarizing plate 64. Therefore, black display is performed on the liquid crystal panel 60 when the selection voltage is applied.

(Optical compensation plate)
In the present embodiment, the first optical compensation plate 70 is disposed outside the light incident side substrate 20 in the liquid crystal panel 60, and the second optical compensation plate 70 is disposed on the opposite side of the first optical compensation plate 70 from the liquid crystal panel 60. A compensation plate 80 is disposed.

FIG. 5 is a perspective view schematically showing a schematic structure of the optical compensation plate. The first optical compensation plate 70 is obtained by providing an alignment film (not shown) on a support 72 made of triacetylcellulose (TAC) or the like and forming a discotic compound layer 74 such as a triphenylene derivative on the alignment film. is there. The alignment film is made of polyvinyl alcohol (PVA) or the like, and its surface is subjected to rubbing or the like so that the alignment direction of the liquid crystal molecules can be regulated. On the other hand, the discotic compound layer 74 has an optical structure in which the inclination angle of the optical axis 76 of the discotic compound 75 that is a dielectric exhibiting negative uniaxiality continuously changes in the thickness direction. Such hybrid orientation structure, the liquid crystal discotic compound is the uniaxial dielectric on a support 72 coated with (discotic liquid crystal) 75, a discotic nematic phase by heating at a constant temperature (N _D phase ) And then cured. The discotic liquid crystal 75 exhibits a minimum tilt angle θmin (for example, 0 ° to 15 °) on the support 72 side, and a maximum tilt angle θmax (for example, 20 ° to 60 °) on the air interface side that is the opposite side. Indicates. The alignment regulation direction 71 of the discotic liquid crystal 75 is defined as the X-axis direction. The X-axis direction is the fast axis direction when the optical compensator is viewed from the normal direction. As such a first optical compensation plate 70, specifically, a WV film made by Fuji Photo Film can be adopted. The second optical compensation plate 80 is also configured in the same manner as the first optical compensation plate 70 described above.

  FIG. 6 is an explanatory diagram of optical compensation. The nematic liquid crystal 65 sealed in the liquid crystal panel 60 is optically positive uniaxial. That is, the refractive index in the direction of the optical axis 66 is larger than the refractive index in the other direction, and the refractive index ellipsoid becomes a rugby ball type. When a selection voltage is applied to the liquid crystal layer 50 of the liquid crystal panel 60, the liquid crystal molecules are vertically aligned from the central portion to the end in the thickness direction of the liquid crystal layer 50. Here, the refractive index ellipsoid of the rugby ball type becomes an ellipse when observed from an oblique direction, and the difference between the major axis and the minor axis becomes birefringence. This phase difference when observed from an oblique direction causes light leakage in black display, which lowers the contrast ratio of the liquid crystal panel and deteriorates the viewing angle characteristic.

  On the other hand, the discotic liquid crystal 75 constituting the first optical compensation plate 70 is optically negative uniaxial. That is, the refractive index in the direction of the optical axis 76 is smaller than the refractive index in the other direction, and the refractive index ellipsoid has a disk shape. Here, if the optical axis 76 of the disc-shaped refractive index ellipsoid 75 in the first optical compensator 70 is arranged in parallel with the optical axis 66 of the rugby ball-type refractive index ellipsoid 65 in the liquid crystal panel 60, the optical axis 76 can be obtained. Therefore, the birefringence effect of the refractive index ellipsoid 65 can be canceled. Therefore, as shown in FIG. 4, the first optical compensation plate 70 is arranged so that the alignment regulation direction 71 of the alignment film in the first optical compensation plate 70 substantially coincides with the alignment regulation direction 67 of the alignment film 22 in the liquid crystal panel 60. Deploy. As shown in FIG. 6, a surface 70 a having a larger angle between the optical axis 76 of the liquid crystal (discotic compound) 75 and the normal line of the first optical compensation plate 70 in the first optical compensation plate 70 is a liquid crystal panel. The first optical compensation plate 70 is disposed so as to face 60. As a result, as shown by the arrow in FIG. 6, the first optical compensation plate with respect to the optical axis 66 of the liquid crystal 65 (that is, positive refractive index ellipsoid) located in the light incident region of the liquid crystal panel 60. The optical axis 76 of the negative refractive index ellipsoid 75 constituting 70 is arranged in parallel. Therefore, it is possible to three-dimensionally compensate for the optical phase difference that occurs in the light incident side region of the liquid crystal panel 60.

  On the other hand, the second optical compensation plate 80 is arranged such that the alignment regulating direction 81 thereof substantially coincides with the alignment regulating direction 68 of the alignment film 16 in the liquid crystal panel 60. Further, as shown in FIG. 6, the second optical compensator 80 has an angle formed by the optical axis 86 of the liquid crystal (discotic compound) 85 in the second optical compensator 80 and the normal line of the second optical compensator 80. The smaller surface is arranged to face the liquid crystal panel 60. As a result, as shown by the arrow in FIG. 6, the second optical compensation is performed with respect to the optical axis 66 of the liquid crystal 65 (that is, the positive refractive index ellipsoid) located in the light emission side region of the liquid crystal panel 60. The optical axis 86 of the negative refractive index ellipsoid 85 constituting the plate 80 is arranged in parallel. Therefore, it is possible to three-dimensionally compensate for the optical phase difference that occurs in the light emission side region of the liquid crystal panel 60.

  As described above, in the present embodiment, the optical compensation action of the first and second optical compensation plates 70 and 80 compensates for the phase difference when observed from all directions, thereby preventing light leakage in black display. Thus, the contrast ratio of the liquid crystal panel can be improved, and the viewing angle characteristics can be improved. In particular, in this embodiment, since the microlens 24a is disposed between the optical compensation plate and the liquid crystal panel 60, the inclination of the light passing through both changes, and the viewing angle compensation effect by the optical compensation plate is further enhanced. Become.

  This operation will be described with reference to FIG. FIG. 7 is a perspective view schematically showing the vicinity of the microlens 24a. As described above, in the optical compensator 70 shown in FIG. 7, the discotic compound 75 has a relatively small tilt angle θmin of 0 ° to 15 on the TAC support side, but the tilt on the air interface side opposite to the tilt angle θmin. The angle θmax cannot take a very large value of 20 ° to 60 °. This is because precise orientation control is possible by rubbing or the like on the TAC support side, but orientation control can be performed only by a limited method such as selecting a material on the air interface side. On the other hand, the ideal tilt angle of the discotic compound 75, which can be considered from the tilt angle of the liquid crystal molecules 65 of the liquid crystal panel 60, is θmin = 3 ° to 10 ° and θmax = 80 ° to 88 °, and can be actually manufactured. Compared with a simple structure, the value of θmax is particularly different. In other words, such an optical compensator cannot originally perform ideal viewing angle compensation. On the other hand, in this embodiment, since the microlens 24a is disposed between the optical compensation plate 70 and the liquid crystal panel 60, the inclination of the light passing through both changes. In particular, with respect to the light L1 incident from the right side in FIG. 7 (that is, the direction opposite to the alignment regulating direction 67), the tilt angle of the liquid crystal 65 is apparently large, and the optical axis 66 of the liquid crystal 65 and the discotic compound 75 The optical axis 76 becomes closer to parallel. Since this direction is the direction in which the viewing angle of the liquid crystal panel 60 is the narrowest, this micro lens 24a is effective in enhancing the viewing angle compensation effect. In addition, regarding the light L2 incident from the left side in FIG. 7 (that is, the alignment regulation direction side), the viewing angle of the liquid crystal panel 60 is conversely narrowed, but this direction is originally the widest viewing angle. The influence on the display by is considered not so large.

In FIG. 8, the simulation result about the structure of this embodiment is shown.
The optical compensation plate used here has θmin = 2 ° and θmax = 50 °. In this case, a liquid crystal device that can obtain only a contrast of about 1: 800 when no optical compensator is used can obtain a contrast of 1: 1050 when two optical compensators are arranged on the light exit side as in the prior art. Further, as described above, a contrast of 1: 1400 can be obtained by arranging two optical compensators on the light incident side where the micro lens is provided. This effect varies depending on the value of θmax of the optical compensator. For example, when [theta] max is large (for example, 70 [deg.] Or more), a higher contrast can be obtained if it is disposed on the light exit side. Conversely, when θmax is small (for example, 10 ° or less), the effect of using the optical compensator is small. However, as described above, it is difficult to manufacture an optical compensator having a large θmax. Therefore, in order to obtain a high contrast, the maximum tilt angle θmax of the optical compensator is set to 30 ° to 60 °, and the light incident side of the microlens It can be said that the arrangement arranged in the is preferable. Actually, in a configuration in which an optical compensator with a maximum tilt angle θmax of 30 ° is arranged on the light incident side of the microlens, an optical compensator with a maximum tilt angle θmax of 60 ° (the actual tilt angle obtained is the maximum It can be seen that a contrast comparable to or higher than that of the microlens arranged on the light exit side can be obtained (FIG. 8). In particular, when the maximum tilt angle is not less than 40 ° and not more than 60 °, the contrast characteristics are the best.

  As described above, in the present embodiment, the microlens is disposed between the optical compensation plate and the liquid crystal panel, and light is incident on the liquid crystal panel at a large angle. The optical axis and the optical axis of the liquid crystal of the liquid crystal panel can be made apparently parallel to each other, and the viewing angle compensation can be more effectively performed than before.

[Second Embodiment]
Next, a liquid crystal device according to a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, the second optical compensation plate 80 is omitted from the configuration of the first embodiment, and only the first optical compensation plate 70 is provided between the microlens array 24 and the light incident side polarizing plate 62. It is arranged. That is, in the liquid crystal device 200 of the present embodiment, only one optical compensation plate is used from the viewpoint of emphasizing cost. In such a configuration, as shown in FIG. 10, it is possible to compensate only for an optical phase difference that occurs in the light incident side region of the liquid crystal panel 60.

In FIG. 11, the simulation result about the structure of this embodiment is shown.
The optical compensator used here is also of θmin = 2 ° and θmax = 50 °. In this case, when a liquid crystal device that can obtain only a contrast of about 1: 800 when an optical compensator is not used, a single optical compensator is arranged on the light exit side, a contrast of 1: 870 can be obtained. Further, by adopting a configuration in which one optical compensation plate is disposed on the light incident side where the micro lens is provided as described above, a contrast of 1: 1050 can be obtained. Although this effect also varies depending on the value of the maximum tilt angle θmax of the optical compensator, the optimum value is in the range of 30 ° to 60 °, preferably 40 ° to 60 °.

  As described above, also in this embodiment, since the optical compensation plate is arranged on the light incident side of the microlens, a display with higher contrast than the conventional display can be obtained.

[Projection type display device]
Next, a projection type display device which is a specific example of the electronic apparatus of the present invention will be described with reference to FIG. FIG. 12 is a schematic configuration diagram showing a main part of the projection display device. This projection type display device includes the liquid crystal device according to each of the above-described embodiments as light modulation means.

  In FIG. 12, 810 is a light source, 813 and 814 are dichroic mirrors, 815, 816 and 817 are reflection mirrors, 818 is an incident lens, 819 is a relay lens, 820 is an exit lens, and 822, 823 and 824 are liquid crystal devices of the present invention. 825 is a cross dichroic prism, and 826 is a projection lens. The light source 810 includes a lamp 811 such as a metal halide and a reflector 812 that reflects the light of the lamp.

  The dichroic mirror 813 transmits red light contained in white light from the light source 810 and reflects blue light and green light. The transmitted red light is reflected by the reflection mirror 817 and is incident on the red light light modulating means 822. The green light reflected by the dichroic mirror 813 is reflected by the dichroic mirror 814 and is incident on the light modulating means 823 for green light. Further, the blue light reflected by the dichroic mirror 813 passes through the dichroic mirror 814. For blue light, in order to prevent light loss due to a long optical path, a light guide means 821 including a relay lens system including an incident lens 818, a relay lens 819, and an exit lens 820 is provided. Blue light is incident on the light modulating means 824 for blue light through the light guiding means 821.

  The three color lights modulated by the respective light modulation means are incident on the cross dichroic prism 825. The cross dichroic prism 825 is formed by bonding four right-angle prisms. A dielectric multilayer film that reflects red light and a dielectric multilayer film that reflects blue light are formed in an X shape at the interface. Yes. These dielectric multilayer films combine the three color lights to form light representing a color image. The synthesized light is projected onto the screen 827 by the projection lens 826 which is a projection optical system, and the image is enlarged and displayed.

  In addition, since the light from the lamp 811 in the light source 810 is converted into substantially parallel light by the reflector 812, the incident angle of the light source light with respect to the light modulation means 822, 823, and 824 is about 12 ° at the maximum. A projection image is formed by the incident light. Here, if the liquid crystal device according to each of the above-described embodiments is used as the light modulators 822, 823, and 824, the contrast ratio of the image projected on the screen 827 can be improved.

  Another specific example of the electronic device of the present invention is a mobile phone. This mobile phone includes the liquid crystal device according to each of the above-described embodiments or modifications thereof in a display unit. Other electronic devices include, for example, an IC card, a video camera, a personal computer, a head mounted display, a fax machine with a display function, a digital camera finder, a portable TV, a DSP device, a PDA, an electronic notebook, and an electric bulletin board. And advertising announcement displays.

  It should be noted that the technical scope of the present invention is not limited to the above-described embodiment, and includes those in which various modifications are made to the above-described embodiment without departing from the spirit of the present invention. For example, in the embodiment, a liquid crystal device including a TFT as a switching element has been described as an example. However, a two-terminal element such as a thin film diode may be employed as the switching element. In the embodiment, the transmissive liquid crystal device has been described as an example. However, the liquid crystal device of the present invention can be applied to a reflective or transflective liquid crystal device. Furthermore, although the three-plate projection display device has been described as an example of the electronic apparatus, the liquid crystal device of the present invention can be applied to a single-plate projection display device or a direct-view display device.

It is an equivalent circuit diagram of a liquid crystal panel. It is explanatory drawing of the planar structure of a liquid crystal panel. It is explanatory drawing of the cross-section of a liquid crystal panel. It is a disassembled perspective view of the liquid crystal device of 1st Embodiment. It is a perspective view which shows typically the schematic structure of an optical compensation board. It is explanatory drawing of optical compensation. It is explanatory drawing of optical compensation. It is a figure which shows the relationship between the maximum tilt angle of an optical compensator, and contrast. It is a disassembled perspective view of the liquid crystal device of 2nd Embodiment. It is explanatory drawing of optical compensation. It is a figure which shows the relationship between the maximum tilt angle of an optical compensator, and contrast. It is a block diagram which shows the principal part of a projection type display apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... TFT array substrate, 20 ... Counter substrate, 24 ... Microlens array, 24a ... Microlens, 50 ... Liquid crystal layer, 60 ... Liquid crystal panel, 65 ... Liquid crystal, 70: first optical compensator, 75, 85: discotic compound (dielectric), 76, 86: optical axis, 80: second optical compensator, 100: liquid crystal apparatus

Claims (4)

A TN-type liquid crystal panel having a plurality of dots that can be displayed independently and having a liquid crystal having a positive refractive index anisotropy between a pair of substrates is twisted. A liquid crystal device that modulates
On the light incident side of the liquid crystal panel, a first optical compensator formed by hybrid alignment of a dielectric having negative refractive index anisotropy is disposed, and the side of the first optical compensator opposite to the liquid crystal panel A second optical compensator formed by hybrid orientation of a dielectric having negative refractive index anisotropy,
In the first optical compensation plate, a surface having a larger angle formed by the optical axis of the dielectric of the first optical compensation plate and a normal line of the first optical compensation plate faces the liquid crystal panel. The second optical compensator has a surface with a smaller angle formed by the optical axis of the dielectric of the second optical compensator and the normal of the second optical compensator. , Arranged to face the liquid crystal panel side,
Between the first optical compensator and the liquid crystal, microlenses that can collect incident light on the liquid crystal side are arranged one by one corresponding to each dot,
By changing the inclination of the light passing by the microlens, the direction of the optical axis of the dielectric of the first optical compensator with respect to incident light from the direction opposite to the alignment regulating direction of the liquid crystal, and A liquid crystal device characterized in that the direction of the optical axis of the liquid crystal is set closer .   The maximum value of the tilt angle of the optical axis of the dielectric with respect to the normal line of the first optical compensation plate and the second optical compensation plate is 30 ° or more and 60 ° or less. LCD device.   The maximum value of the tilt angle of the optical axis of the dielectric with respect to the normal line of the first optical compensation plate and the second optical compensation plate is 40 ° or more and 60 ° or less. LCD device.   A projection type display device comprising the liquid crystal device according to claim 1 as light modulation means.

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