JP2003005181A - Liquid crystal display - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a liquid crystal display device whose luminance is improved in both the transmissive display mode and the reflective display mode. SOLUTION: A liquid crystal display element 3 in which liquid crystal is sandwiched between substrates facing each other, an upper polarizing plate 1 provided on the visual side of the liquid crystal display element, and a lower polarizing plate 4 provided behind the liquid crystal display element. And a backlight 6 provided behind the lower polarizer.
A liquid crystal display device comprising: a directional diffusion layer that scatters light incident at a specific angle range and transmits light incident at other angles between the lower polarizing plate and the backlight. did. Further, since the directional diffusion layer has a function of scattering light incident in a specific angle range and directing the scattered light in a specific direction, it is possible to make the directional diffusion layer brightest most efficiently in the directional direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a watch, a mobile phone,
The present invention relates to a liquid crystal display device used in audio equipment, electronic equipment, etc., and relates to a configuration for improving the brightness of the liquid crystal display device. More specifically, the present invention relates to a liquid crystal display device that is capable of displaying both a reflective display that uses external light that is the light of the usage environment and a transmissive display that uses illumination light such as a backlight.

[0002]

2. Description of the Related Art A liquid crystal panel (LCD) used in a liquid crystal display device generally uses a TN (twisted nematic) type or STN (super twisted nematic) type liquid crystal, in which liquid crystal molecules sandwich a twisted liquid crystal layer. The main structure is two substrates facing each other. Polarizing plates are arranged on the front side and the back side of the liquid crystal panel, respectively. In the liquid crystal display device having such a configuration, an alignment state or phase change of liquid crystal molecules occurs due to an electric field, a current, or a temperature rise, and light interference in the liquid crystal state occurs
The operation principle of the display is to change optical properties such as scattering, diffraction, optical rotation, selective scattering, and absorption.
Then, a display is realized by applying a voltage between electrodes provided for forming pixels on each substrate to control the liquid crystal layer. Further, since the liquid crystal panel does not emit light, a reflector or a backlight is generally used.

The liquid crystal display device includes a reflective display that uses external light such as natural light and room light and a transmissive display that uses illumination light from a backlight so that the display can be observed in both bright and dark places. Some have both display modes. As a configuration of such a liquid crystal display device, a configuration in which a transflective plate and a backlight are provided behind a liquid crystal panel is generally known and is called a transflective display device. The structure of the transflective STN liquid crystal display device will be described below with reference to FIGS. FIG. 9 shows a case of a reflection type display in which the display is observed by using external light, and FIG. 10 shows a case of a transmission type display in which the display is observed by using the irradiation light of the backlight.

As shown in the figure, the liquid crystal panel 3 is composed of substrates facing each other with a liquid crystal layer interposed therebetween. An upper polarizing plate 1 is provided on the upper side of the liquid crystal panel 3 and a lower polarizing plate 4 is provided on the lower side thereof. ing. Each of the upper polarizing plate 1 and the lower polarizing plate 4 selectively transmits or absorbs only linearly polarized light in a specific direction.

A compensating plate 2 for compensating the optical anisotropy of the liquid crystal panel 3 is provided between the upper polarizing plate 1 and the liquid crystal panel 3. This compensator 2 is generally used in STN type liquid crystal devices. A semi-transmissive plate 5 is provided behind the lower polarizing plate 4, and a backlight 6 is provided behind the semi-transmissive plate 5.

In the liquid crystal display device having such a structure,
When the liquid crystal panel 3 is displayed using external light, as shown in FIG. 9, the incident light incident on the upper polarizing plate 1 passes through the compensating plate 2, the liquid crystal panel 3, and the lower polarizing plate 4. A part of the light is reflected by the semi-transmissive plate 5. The light reflected by the semi-transmissive plate 5 reaches the observer again through the lower polarizing plate 4, the liquid crystal panel 3, the compensating plate 2 and the upper polarizing plate 1. This allows
The information displayed on the liquid crystal panel 3 can be seen.

Next, a case where the liquid crystal panel 3 is displayed using the light of the backlight will be described with reference to FIG.
A part of the illumination light emitted by the backlight 6 passes through the semi-transmissive plate 5. The transmitted light further passes through the lower polarizing plate 4, enters the liquid crystal panel 3 from the rear surface thereof, and is emitted in front of the display panel. The emitted light passes through the compensating plate 2 and the upper polarizing plate 1 and reaches the observer. As a result, the information displayed on the liquid crystal panel 3 can be viewed.

[0008]

The liquid crystal display device using a semi-transmissive plate that reflects and transmits light so that both external light and backlight light can be used has the following problems. That is, when the reflection rate of the semi-transmissive plate is increased, the transmission rate is decreased, so that it becomes bright when using external light, but becomes dark when using a backlight. vice versa,
When the transmissivity of the semi-transmissive plate is increased, the rate of reflection is decreased, so that it becomes bright when a backlight is used, but becomes dark when external light is used. As described above, the liquid crystal display device having the above-described configuration has a problem that it is not possible to make both the outside light and the backlight bright.

[0009]

In order to solve the above problems, the present invention provides a liquid crystal display element in which liquid crystal is sandwiched between substrates facing each other, and is provided on the visual side and the back of the liquid crystal display element, respectively. In a liquid crystal display device including an upper polarizing plate, a lower polarizing plate, and a backlight provided behind the lower polarizing plate, a direction that scatters light incident in a specific angle range and transmits light incident in other angles. The characteristic diffusion layer was provided between the lower polarizing plate and the backlight. With such a configuration, it is possible to efficiently use and display both the external light incident at an incident angle within a specific angle range and the illumination light from the backlight. Therefore, high brightness,
A bright and good-quality liquid crystal display device can be easily realized with a simple configuration.

Next, the directional diffusion layer was constructed so that the scattered light scattered by the directional diffusion layer was condensed with directivity in a specific direction. With such a configuration, light is efficiently condensed in a specific direction. Therefore, it is possible to display an extremely bright and high-luminance image when viewed from a specific direction.

Next, the directional diffusion layer is configured so that the direction in which the diffused light that has passed through the directional diffusion layer is condensed matches the optimum viewing angle of the liquid crystal display element. With such a configuration, light is efficiently condensed at the optimum viewing angle. Therefore, an extremely bright display can be realized when observed at the optimum viewing angle.

Further, a reflective polarizer for transmitting only linearly polarized light in a specific direction and reflecting the other light is provided between the directional diffusion layer and the backlight. With this configuration, the light of the component that the observer could not observe,
There is a possibility that the light is emitted to the front side of the liquid crystal display element due to reflection by the reflective polarizer or multiple reflection between the reflective polarizer and the backlight. That is, since the light of the component that cannot be conventionally observed by the observer can be used as a part of the scattered light from the liquid crystal display device,
Further, the efficiency of light utilization is increased, and display with higher brightness can be realized.

Further, the transmission axis direction of the reflective polarizer and the transmission axis direction of the lower polarizing plate are made to coincide with each other. With such a configuration, the component whose polarization direction has been converted by the transmission of the directional reflective film or the reflection by the backlight is reflected by the reflective polarizer, or by the multiple reflection between the reflective polarizer and the backlight, It is emitted to the front side of the liquid crystal display element. It can be used as a part of the scattered light from the liquid crystal display device. Therefore, the light utilization efficiency is further increased, and higher brightness display can be realized.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device according to the present invention includes a liquid crystal display element in which liquid crystal is sandwiched between substrates facing each other, an upper polarizing plate provided on the visual side of the liquid crystal display element, and a liquid crystal display element. A direction that includes a lower polarizing plate provided behind and a backlight provided behind the lower polarizing plate, scatters light incident in a specific angle range, and transmits light incident at other angles. The structure in which the property diffusion layer is provided between the lower polarizing plate and the backlight is adopted. When observing the liquid crystal display device having such a structure with external light, light incident in a specific angle range is scattered by the directional diffusion layer. The directional diffusion layer has a function of scattering light incident in a specific angle range and directing the scattered light in a specific direction. By changing the configuration of the directional diffusion layer, the direction in which the scattered light is directed can be adjusted, and the characteristics of the directional diffusion layer can be set arbitrarily. Therefore, by setting the directivity direction of the directional diffusion layer so as to be adapted to the viewing angle direction of the liquid crystal display element, it is possible to make the liquid crystal display element brightest most efficiently in the viewing angle direction.

Further, a reflective polarizer for transmitting only linearly polarized light in a specific direction and reflecting the other light is provided between the directional diffusion layer and the backlight. With this configuration, the light of the component that the observer could not observe,
Due to reflection by the reflective polarizer or multiple reflection between the reflective polarizer and the backlight, the light passes through the lower polarizing plate and enters the liquid crystal display element, and is emitted to the front surface side of the liquid crystal display element. That is, the light of the component that cannot be conventionally observed by the observer can be used as a part of the scattered light from the liquid crystal display device. Therefore, even in the transmissive display mode and the reflective display mode, the light utilization efficiency is further increased, and a display with higher brightness can be realized.

[0016]

Embodiments of the liquid crystal display device according to the present invention will be described below with reference to the drawings.

(Embodiment 1) FIGS. 1 and 2 are schematic views showing a sectional structure of a liquid crystal display device in this embodiment. In particular, FIG. 1 shows a state where external light is used, and FIG. 2 shows a state where illumination light from a backlight is used.

As shown in the figure, an upper polarizing plate 1 is provided on the upper side of a liquid crystal panel 3 in which liquid crystal is sealed, and a lower polarizing plate 4 is provided on the lower side thereof. Here, the liquid crystal panel 3 is a liquid crystal display element in which liquid crystal molecules are twisted in a structure in which liquid crystal is sandwiched between transparent substrates. When the STN type liquid crystal layer is used for the liquid crystal panel, a compensator for compensating the optical anisotropy of the liquid crystal panel is provided between the upper polarizing plate 1 and the liquid crystal panel 3. Behind the lower polarizing plate 4, a directional diffusion film 7 is arranged as a directional diffusion layer. Further, the backlight 6 is arranged behind the directional diffusion film 7. Below is the ST
The N-type liquid crystal display element will be specifically described, but the same principle is applied to the case where a TN-type liquid crystal display element is used except for the action of the compensating plate.

The upper polarizing plate 1, the compensating plate 2 and the lower polarizing plate 4 are
The liquid crystal display element 3 is arranged at an angle that compensates for the optical anisotropy. The liquid crystal display element is set so that the front side has an optimum viewing angle, and is designed so that it can be observed within a viewing angle range of about 15 degrees before and after the optimum viewing angle. Therefore, the directional diffusion film 7 substantially transmits the incident light from the thickness direction (normal direction), and efficiently transmits the light having an incident angle of 5 to 15 degrees in the thickness direction, that is, the directional diffusion film. A diffused light is collected on the front surface of No. 7 and has a characteristic of almost transmitting the incident light having a critical angle of about 20 degrees or more.
The directional diffusion film has a structure in which a portion having a refractive index different from that of the base material is provided in the base material of the film, and is formed by, for example, partially exposing a photopolymer using a mask. The polymer film thus prepared has a function as a directional diffusion film because the refractive index of the light-sensitive area is different from that of the non-light-sensitive area. As the backlight 6, a backlight having an LED that emits white light as a light source was used. In general, a backlight is a light guide plate 1 that guides light emitted from a light source 11 to its front surface, as shown in FIG.
2, a reflection layer 13 provided behind the light guide plate, and a diffusion plate 14 provided to diffuse the light emitted from the light guide plate and suppress uneven brightness. The light guide plate may be subjected to a treatment for uniformly irradiating the light on the upper side or the reflection layer side.

FIG. 1 shows the case of observing the liquid crystal display device having such a structure in a reflection mode display using external light from almost the front of the liquid crystal display device (that is, from the normal direction).
Will be explained. The light incident from the outside is the upper polarizing plate 1,
Polarization separation and elliptically-polarized light conversion are performed by the compensating plate 2, the linearly polarized light is returned by the liquid crystal display element 3, and the light is emitted from the lower polarizing plate 4 while substantially maintaining the incident angle. Part of the emitted light is reflected at the interface of the directional diffusion film, and the rest of the light passes through the directional reflection film. At this time, the light passing through the action of the directional reflection film 7 becomes diffused light and is collected in the thickness direction (normal direction) of the directional diffusion film 7. The light that has passed through the directional reflection film in this manner is reflected by the surface of the backlight 6 or the reflective layer, and passes through the directional diffusion film 7 again. Even at this time, the light passing therethrough is collected in the thickness direction (normal direction) of the directional diffusion film and is incident on the lower polarizing plate at approximately 0 degrees with respect to the normal direction. Here, some light is collected so as to enter the backlight 6 almost from the normal direction when it first passes through the directional reflective film, and this light is reflected as it is on the surface of the backlight or the reflective layer. This reflected light is incident on the directional diffusion film at approximately 0 degrees with respect to the normal line direction of the directional diffusion film 7, and therefore efficiently passes through the directional diffusion film 7. In any case, the light passing through the directional diffusion film and traveling toward the lower polarizing plate is incident on the lower polarizing plate at approximately 0 degrees with respect to the normal direction. Then, the lower polarizing plate 4, the liquid crystal display element 3,
The reverse conversion is performed when the light enters the compensating plate 2, and the light is emitted from the upper polarizing plate 1. In this way, external light that enters the liquid crystal display device within the critical angle of the directional diffusion film is collected and emitted in the normal direction (in this case, the viewing angle direction of the liquid crystal display element, that is, the observation direction). .

As described above, since the external light is efficiently collected in the normal direction of the liquid crystal display device, bright display can be realized in the reflection mode utilizing the external light and good display characteristics can be obtained.

If a diffusing plate is provided on the surface of the backlight, incident light passing through the liquid crystal display element will be diffusely reflected on the surface of the backlight (ie, the surface of the diffusing plate). The effect of reducing the distance between the liquid crystal layer and the reflection portion, that is, so-called parallax, is produced. Therefore, a display without shadow can be realized. On the other hand, when the surface of the backlight is not provided with a diffusion plate, that is, when the light guide plate is exposed, the parallax corresponding to the thickness of the light guide plate occurs, but the light condensed by the directional diffusion film is used. Is not diffused by the diffusion plate, so that the light condensing effect of the directional diffusion film is not disturbed. Therefore, a very bright display can be realized.

Further, the light guide plate used for the backlight preferably has a small phase difference. Light linearly polarized by the polarizing plate enters the light guide plate. If the light guide plate has a phase difference, it is converted into elliptically polarized light by the light guide plate, reflected by the reflection layer, and colored when passing through the polarizing plate again. As a result, only the part having the phase difference becomes dark. In particular, when the backlight is not provided with a diffusion plate, this phenomenon becomes noticeable, and thus it is necessary for the light guide plate to have a small phase difference. Usually, the light guide plate guides the irradiation light (that is, the light in the lateral direction) from the light source and emits the light from the entire front surface. Therefore, the light guide plate may be provided with a function of diffusing the light from the lateral direction in order to uniformly emit the surface light. However, when the directional diffusion film is provided on the front surface side of the backlight as in the present invention, it is preferable that the light guide plate is transparent without scattering in the thickness direction. When the light guide plate has a scattering property, the incident light collected by the directional diffusion film is scattered, which hinders the light collecting effect of the directional diffusion film, resulting in a dark display. If the light guide plate does not have a scattering characteristic, the light condensing effect of the directional diffusion film works effectively, and an extremely bright display can be realized.

The reflective layer of the backlight has a good mirror surface. Since the light condensed by the directional diffusion film is specularly reflected and enters the directional diffusion film again and is condensed, it becomes particularly bright in the viewing angle direction. If the reflection layer is not a mirror surface, for example, a matte reflection layer, the light condensed by the directional diffusion film is scattered at the time of reflection, and the light collection effect is deteriorated.

From the above, the backlight is constructed without using the diffusion plate, and the light guide plate of the backlight has a small phase difference and is not scattering in the thickness direction. By providing the specular reflection layer, the function of the directional diffusion film can be fully utilized, and the display in the reflection mode can be made extremely bright. With such a configuration, if the scattered portion is reduced as much as possible, the display becomes pinpoint and extremely bright when observed from a specific direction. In order to make it bright within a certain viewing angle range, a scattering member may be partially used. For example, by providing a diffusion plate on the surface of the backlight or using a matte reflection layer, the maximum range of brightness (luminance) is inferior, but the brightly observable range (viewing angle range) is widened.

Next, in the liquid crystal display device having the constitution of the present invention, the case of displaying in the transmissive mode using the irradiation light of the backlight will be described with reference to FIG.

Of the illumination light from the backlight 6, the components emitted in the normal direction pass through the directional diffusion film 7 almost as they are. 0 to 20 of components other than the normal direction
The illuminating light incident at a degree is converted into diffused light by the directional diffusion film 7 and is collected in the normal direction. As a result, most of the illumination light from the backlight 6 is incident on the lower polarizing plate 4 in the normal direction. The incident illumination light is converted into linearly polarized light by the lower polarizing plate 4, converted into elliptically polarized light by the liquid crystal panel 3, further converted into linearly polarized light by the compensating plate 2, and emitted from the upper polarizing plate 1. As a result, the light from the backlight is efficiently collected in the normal direction of the liquid crystal display device. Therefore, a bright display was obtained even in the transmissive mode using the illumination light of the backlight, and good display characteristics could be realized. Thus, the configuration of the present invention, that is,
A configuration in which a directional diffusion layer that scatters light incident in a specific angle range and transmits light incident in other angles is provided between the lower polarizing plate provided behind the liquid crystal display element and the backlight. According to this, bright display is possible in both reflective display and transmissive display.

Here, the directional diffusion film used in this embodiment will be briefly described. FIG. 5 shows the structure of the directional diffusion film according to the present invention. FIG. 6 schematically shows the optical path of light incident on the directional diffusion film. The directional diffusion film 7 is based on the material of photopolymer,
The non-exposed portion 60 which is not exposed to light and the exposed portion 50 caused by exposure are adjacent to each other. The photosensitive section 50 is
The shape extends on the cylinder in the thickness direction. The photosensitive section 50 and the non-photosensitive section 60 have different refractive indexes. for that reason,
As shown in FIG. 6, the light 80 incident on the photosensitive portion 50 from within the critical angle is repeatedly reflected at the interface with the non-photosensitive portion 60,
The light 80 becomes scattered light gathered in the normal direction. Further, the light 70 incident perpendicularly to the thickness direction passes through the photosensitive section 50 without being refracted by the photosensitive section 50. On the other hand, the light 90 that has entered beyond the critical angle passes through the photosensitive section 50 and the non-photosensitive section 60 at the incident angle.
As described above, according to the directional diffusion film having the configuration of FIGS. 5 and 6, incident light within the critical angle can be efficiently collected in the normal direction.

Here, the critical angle can be changed by changing the difference in refractive index between the light-sensitive area and the non-light-sensitive area. Further, by adjusting the distribution density, the layout, or the dimensions such as the diameter and the length of the photosensitive section 50, it is possible to arbitrarily set the scattering degree and the directivity direction.

Next, the optical characteristics of the directional diffusion film used in this example will be described. FIG. 7 shows the transmittance of the film with respect to the incident angle of light, where the incident angle of light is the horizontal axis and the transmittance is the vertical axis. Here, the light that is vertically incident on the directional diffusion film 7 has an incident angle of 0.
Let the light of the degree. In addition, one direction from 0 degree is positive, and the opposite direction is negative. As shown in the figure, the directional diffusion film exhibits high transmittance for light with an incident angle of zero degree, and the transmittance decreases as the incident angle increases,
The scattering property becomes large. Then, the transmittance becomes the minimum and the scattering property becomes the maximum when the incident angle is around 10 degrees. When the incident angle further increases, the transmittance gradually increases, and when the incident angle exceeds 20 degrees, the transmittance sharply increases, and the scattering property is lost accordingly. This angle is the critical angle.
Therefore, light incident on the directional diffusion film at an incident angle of 20 to 90 degrees, which is the critical angle, is transmitted without being scattered. The minus side also shows symmetrical characteristics with the plus side.

That is, the directional diffusion film used in this example almost transmits light incident from an incident angle of about 0 degrees and efficiently scatters light with an incident angle of 5 to 15 degrees. It has a characteristic of condensing light and substantially transmitting it with respect to incident light having a critical angle of about 20 degrees or more. As described above, the directional diffusion film is set so that the incident angle range having low transmittance and high scattering property matches the viewing angle range of the liquid crystal display element.

When the directional diffusion film 7 having the above-mentioned characteristics is used in a liquid crystal display device, as already described with reference to FIG. 1, the light passing through the lower polarizing plate 4 is partially reflected by the directional diffusion film 7. The remaining light passes through the directional diffusion film 7 and is reflected by the backlight 6. At this time, from the characteristics shown in FIG. 7, the light that has passed through the lower polarizing plate 4 and is incident on the directional diffusion film at 0 to 20 degrees is scattered and condensed by the directional diffusion film and is directed to the backlight 6. , Is reflected by the backlight and is condensed in the 0 degree direction when passing through the directional diffusion film again. Then, the reflected light from the directional diffusion film 7 and the reflected light from the backlight 6 are combined and passed through the lower polarizing plate 4, the liquid crystal panel 3, the compensation plate 2, and the upper polarizing plate 1 to be recognized by an observer. In this way, since the scattered light appearing above the upper polarizing plate 1 can be provided with directivity, it can be made particularly bright in the case of reflective display using external light.

(Example 2) FIGS. 3 and 4 show a liquid crystal display device having a structure in which a reflective polarizer 8 is used between the directional reflective film 7 and the backlight 6 of Example 1. The reflective polarizer 8 has a characteristic of selectively transmitting or selectively reflecting only linearly polarized light in a specific direction of incident light. By changing the transmission axis of the lower polarizing plate 4 and the axial direction of the selective transmission of the reflective polarizer 8, the ratio of the light transmitted by the reflective polarizer to the reflected light can be arbitrarily changed. In the second embodiment, the transmission axis of the lower polarizing plate and the transmission axis of the reflective polarizer are parallel to each other, that is, they are arranged at an angle of 0 degree.

A case of observing the liquid crystal display device having the above-mentioned structure in the display in the reflection mode by external light will be described with reference to FIG. The light incident from the outside is the upper polarizing plate 1 and the compensating plate 2.
Polarization separation and elliptical polarization conversion are performed by. And
It is returned to linearly polarized light by the liquid crystal panel 3 and is incident on the lower polarizing plate 4. The light is emitted from the lower polarizing plate 4 while substantially maintaining the angle of incidence on the lower polarizing plate. Part of the emitted light is diffusely reflected at the interface of the directional diffusion film 7,
The remaining light passes through the directional reflection film 7. At this time, the light that has passed through the directional reflection film becomes diffused light due to the action of the directional reflection film, and is also collected in the same direction as the thickness direction of the directional diffusion film 7 (that is, the direction in which the incident angle becomes smaller). Up to this point, the same operational effects as in Example 1 are obtained, but in Example 2 the reflective polarizer 8 is arranged between the directional diffusion film 7 and the backlight 6. The reflective polarizer 8 is set so that its selective transmission axis is parallel to the transmission axis of the lower polarizing plate. Therefore, of the linearly polarized light components made by the lower polarizing plate 4, the light whose polarization direction has been converted by the directional reflection film 7 becomes a selective reflection component that cannot pass through the reflective polarizer 8 and becomes a reflective polarizer. The light is reflected by and can be used as a part of the scattered light 10 from the liquid crystal display device. Further, of the light transmitted through the reflective polarizer, the component whose polarization direction is changed when reflected by the backlight 6 can be reused in the multiple reflection between the backlight 6 and the reflective polarizer 8. Therefore, the external light can be used more effectively due to the light use efficiency in the reflection mode of the liquid crystal display device described in the first embodiment.

Next, in the liquid crystal display device having the structure of the present invention, the case of the transmissive mode using a backlight will be described with reference to FIG. Of the light emitted from the backlight 6, the light in the transmission axis direction of the lower polarizing plate 4 is selectively transmitted by the reflective polarizer 8. Light that has not passed through the reflective polarizer is selectively reflected toward the backlight 6 side,
Is reflected again. In this way, theoretically, light that has not passed through the reflective polarizer is repeatedly reflected multiple times between the backlight 6 and the reflective polarizer 8 until it reaches the transmission axis of the reflective polarizer. That is, while the multiple reflections of the backlight 6 and the reflective polarizer 8 are repeated, most of the light components of the backlight 6 become light of the polarization axis passing through the lower polarizing plate and passing through the liquid crystal panel to the observer. Will be ejected to the side. Therefore, the liquid crystal display device can be used for ensuring visibility when the backlight is turned on. That is, in addition to the effect of the first embodiment, the utilization efficiency of the illumination light from the backlight can be further improved.

[0036]

As described above, according to the liquid crystal display device of the present invention, the directional diffusion film which is incident at a specific angle and scatters light and transmits the light incident at other angles is disposed. By providing between the polarizing plate and the backlight,
Light incident at a specific angle can be scattered and brightness can be improved.

Further, since the scattered light has directivity in a specific direction, the directivity can be enhanced and the brightness can be enhanced.

Further, by making the specific direction coincide with the visual direction, when the user looks at the liquid crystal display device, the brightness when the user visually recognizes it can be improved.

Further, by providing the reflective polarizer between the directional diffusion film and the backlight, the light of the backlight can be more focused on the directional diffusion film, so that the brightness can be improved.

Therefore, it is possible to provide a liquid crystal display device which is bright in both reflection and transmission and has good display quality. As a result, the product value can be increased in the field of electronic devices such as cameras, mobile phones, and watches, in which liquid crystal display devices are frequently used in the consumer products market.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing a cross-sectional structure of a liquid crystal display device according to a first embodiment of the present invention. In particular, it is a diagram schematically showing an optical path in the case of reflective display using outside light.

FIG. 2 is a diagram schematically showing a cross-sectional structure of the liquid crystal display device according to the first embodiment of the present invention. In particular, it is a diagram schematically showing an optical path in the case of transmissive display using a backlight.

FIG. 3 is a diagram schematically showing a cross-sectional structure of a liquid crystal display device according to a second embodiment of the present invention. In particular, it is a diagram schematically showing an optical path in the case of reflective display using outside light.

FIG. 4 is a diagram schematically showing a cross-sectional structure of a liquid crystal display device according to a second embodiment of the present invention. In particular, it is a diagram schematically showing an optical path in the case of transmissive display using a backlight.

FIG. 5 is a diagram schematically showing the structure of a directional diffusion film.

FIG. 6 is a view schematically showing the action of the directional diffusion film.

FIG. 7 is a diagram showing a relationship between a visible angle and a transmittance of a directional diffusion film.

FIG. 8 is a diagram schematically showing a sectional configuration of a backlight.

FIG. 9 is a schematic cross-sectional view showing the configuration of a conventional liquid crystal display device. It is the figure which showed the state when using external light typically.

FIG. 10 is a schematic cross-sectional view showing the configuration of a conventional liquid crystal display device. In particular, it is a diagram schematically showing a case where a backlight is used.

[Explanation of symbols] 1 Upper polarizing plate 2 compensator 3 LCD panel 4 Lower polarizing plate 5 Semi-transmissive reflector 6 backlight 7 Directional diffusion film 8 reflective polarizer 10 Light emitted from liquid crystal display device 50 Photosensitive layer 60 non-photosensitive layer

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09F 9/00 324 G09F 9/00 324 F term (reference) 2H042 BA03 BA12 BA14 BA20 2H049 BA02 BA06 BB03 BB06 BB63 BC22 2H091 FA08X FA08Z FA23Z FA31Z FA41Z FA50Z LA30 5G435 AA03 BB12 BB15 BB16 DD12 EE25 FF02 FF03 FF05 HH01 LL07

Claims (7)

[Claims] 1. A liquid crystal display device in which liquid crystal is sandwiched between substrates facing each other, an upper polarizing plate provided on the visual side of the liquid crystal display device, and a lower polarizing plate provided behind the liquid crystal display device. In the liquid crystal display device provided with a backlight provided behind the lower polarizing plate, a directional diffusion layer that scatters light incident in a specific angle range and transmits light incident in other angles, A liquid crystal display device provided between the lower polarizing plate and the backlight. 2. The liquid crystal display device according to claim 1, wherein the scattered light scattered by the directional diffusion layer has directivity in a specific direction. 3. The liquid crystal display device according to claim 2, wherein the specific direction coincides with a viewing angle direction of the liquid crystal display element. 4. The specific angle range is greater than 0 degree and less than or equal to a critical angle with respect to the normal direction of the liquid crystal display element, and the angular range for transmitting light is 0 degree and 90 degrees beyond the critical angle. The liquid crystal display device according to any one of claims 1 to 3, wherein: 5. A reflective polarizer that transmits only linearly polarized light in a specific direction is provided between the directional diffusion layer and the backlight. The liquid crystal display device according to item. 6. The transmission axis direction of the reflective polarizer and the transmission axis direction of the lower polarizing plate are coincident with each other.
The liquid crystal display device according to item 1. 7. The light guide plate of the backlight does not have a phase difference, and the reflective layer of the backlight is a specular reflective layer, according to any one of claims 1 to 6. Liquid crystal display device.