JP2002268062A - Liquid crystal display device and apparatus applied to image display provided with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection type liquid crystal display device which is bright and employs no polarizing plate and to provide an apparatus applied to image display provided with the same. SOLUTION: In the liquid crystal display device provided with a liquid crystal display element formed by encapsulating a liquid crystal between a pair of electrode substrates and a reflection plate, the reflection surface of the reflection plate is formed as a stripe-shaped groove part and the section of the groove part is formed in a V shape or nearly in a V shape.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device widely used in OA equipment and the like in recent years, and to an image display application device provided with the same.

[0002]

2. Description of the Related Art Today, TN type and STN type liquid crystal display devices are used in liquid crystal display devices widely used in OA equipment and the like. These liquid crystal display devices may be of either a transmission type or a reflection type. A polarizing plate is always used.

[0003]

However, these liquid crystal display devices use a polarizing plate as described above (the polarizing plate is also used for the guest-host type because the contrast is not good). Poor light utilization efficiency (about 5
0% light is not used), and particularly in a reflective liquid crystal display device, there is a problem that the display is dark. On the other hand, it has been difficult to commercialize a light-scattering type liquid crystal display element as a reflective type due to the characteristic of forward scattering.

Accordingly, an object of the present invention is to provide a very bright reflective liquid crystal display device without using a polarizing plate and an image display application device having the same in order to solve the above-mentioned conventional problems.

[0005]

In order to achieve the above object, a liquid crystal display device according to the present invention is a liquid crystal display device comprising a liquid crystal display element in which liquid crystal is sealed between a pair of electrode substrates, and a reflector. The reflection surface of the reflection plate is formed as a stripe-shaped groove, and the cross-section of the groove is V-shaped or substantially V-shaped.
Characteristic. The reflection plate may be formed in advance on one side of the electrode substrate, or may be provided later on the liquid crystal display device.

Further, in the liquid crystal display device according to the present invention, the liquid crystal display element is a guest-host type liquid crystal display element in which liquid crystal mixed with a dichroic dye is sealed, and the pitch of the groove is set to a pixel of the liquid crystal display element. Is preferably equal to or less than the pixel pitch.

Further, in the liquid crystal display device of the present invention, it is preferable that the liquid crystal display element is of a light scattering type.

Further, in the liquid crystal display device according to the present invention, the liquid crystal display element is a light scattering type liquid crystal in which a light scattering type liquid crystal is sealed between a pair of electrode substrates each having a color filter formed on at least one substrate. It is a display element, and it is preferable that a pitch of the grooves is the same as a pitch of pixels of the color filter.

Further, in the liquid crystal display device of the present invention, it is preferable that the liquid crystal display element is of a light scattering type, and that a light absorbing wall is formed at the bottom of the groove.

Further, an image display application device according to the present invention is provided with the liquid crystal display device. Examples of image display applied devices include devices in which a liquid crystal display device is conventionally used such as a monitor, a personal computer, a television, and a DVD player. In particular, devices used outdoors (under external light), such as a car navigation device and a PDA , A mobile phone or the like is most suitable.

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 1 is a sectional view of a liquid crystal display device according to Embodiment 1 of the present invention. Although the transparent electrode is not shown, a transparent electrode is formed on the color filter 4 and on the flattening layer 5 made of acrylic resin so as to face the liquid crystal 3 and face the liquid crystal 3. The pixel size of the display pixel of the liquid crystal display element is the pixel size of the color filter. The pitch of the V-shaped groove of the reflective film 6 made of silver or aluminum is half the pixel pitch.
The angle between the characters is 90 degrees.

In order to form the liquid crystal display element, first, an alignment film is formed on the transparent electrodes of the glass substrates 1 and 2 (not shown), and the alignment film is formed at an angle of about 45 degrees with respect to the stripe direction of the V-shaped groove. Rubbing is performed so that the liquid crystal molecules are arranged in the directions, and the P-type liquid crystal 3 mixed with dichroic dyes of three colors of red, blue and green is sealed and homogeneously aligned.

The operation principle of the liquid crystal display device thus formed will be described. First, when no voltage is applied to the liquid crystal 3, incident light from the outside into the liquid crystal 3 is decomposed into two parallel and perpendicular axes of the polarization axis to the liquid crystal molecules, and one light is absorbed by the dichroic dye. However, the other light reaches the reflection surface without being absorbed. In the conventional liquid crystal display device as shown in FIG. 18, the reflection film is formed on a flat surface or a scattering surface. In such a configuration, light that has reached the reflection surface without being absorbed has a polarization axis. Because it does not change, it is reflected outside without being absorbed again. However, according to the reflector of the present invention, the polarization axis is rotated by 90 degrees by the two reflections on the reflection surface as shown in FIGS.
On the way back, the light is absorbed by the dichroic dye and no light leaks out. FIG. 7 is a perspective view showing a reflection surface, a polarization axis of incident light and reflected light, and FIGS. 8 and 9 are a side view and a plan view thereof. On the other hand, when a voltage is applied to the liquid crystal 3, the incident light is not absorbed by the dichroic dye and is reflected as it is, similarly to a normal guest-host type liquid crystal display element. A very high contrast and very bright display can be achieved without using a plate.

In the first embodiment, a homogeneous alignment is used. However, it is needless to say that a twist alignment or a homeotropic alignment can be used. The angle formed by the V-shape of the groove of the reflecting surface is most preferably 90 degrees in the first embodiment, but the effect can be obtained even at 80 degrees or 100 degrees. Also, the V-shaped shape is
Considering the viewing angle direction, it is not always necessary to be the target.
Although the pitch is set to half the pixel pitch, the pitch may be equal to or smaller than the pixel pitch. Furthermore, there is no problem if the direction of the V-shaped groove is not only one direction as shown in FIG. 14 but also two directions perpendicular to each other as shown in FIG. It is desirable that the liquid crystal be parallel and perpendicular to the direction, but the present invention is not limited to this as long as the alignment direction of the liquid crystal when voltage is applied or not applied is considered. Even if the concave portion of the groove portion is partially flat or the convex portion is partially flat like the V-shaped groove portion in FIG. 4, the characteristics are slightly inferior, but there is no problem. These are based on the principle that as much light as possible incident on a pixel is reflected by a reflective film and passes through the same pixel with a different polarization axis. It is preferable to design according to required characteristics. FIG. 6 shows another embodiment in which the reflection plate is externally attached. Even in this case, the effect of the first embodiment is not obtained, but a glass substrate having a small thickness is used. If it does, the effect is enough.

In the first embodiment, metallic luster may appear in white display. In this case, a light scattering film may be attached to the surface of the glass substrate 1, but a filler may be added to the color filter. It is best to have a light scattering function to improve the viewing angle.

As described above, in the present invention, the polarization axis is changed by the reflector, thereby improving the display performance of the reflection type liquid crystal, and has a great value in other liquid crystal display modes.

Embodiment 2 FIG. 2 is a cross-sectional view of a liquid crystal display according to another embodiment. In the second embodiment,
Since the light scattering type is used as the liquid crystal 3,
The alignment treatment may be performed as needed. In the second embodiment, the formation of the alignment film and the alignment treatment are not performed. The reflection film 6 has a V-shaped angle of 120 degrees, and the other configuration is the same as that of the first embodiment.

The operation of the liquid crystal display device having such a configuration will be described. The liquid crystal enters a transparent state or a light scattering state by applying or not applying a voltage. First, when the liquid crystal is in a transparent state, incident light reaches the reflection film 6 as it is. by the way,
Light incident on the glass substrate of the liquid crystal display element from the outside is refracted and changes its angle. However, from the refractive index of the glass, the angle of incidence of light rays incident on the liquid crystal 3 (the angle with respect to the perpendicular of the substrate) is about 45 degrees or less. is there. The light that has now entered the liquid crystal 3 at an angle of 45 degrees is reflected by the reflective film 6 as shown in FIG.
The light enters the air at an angle of 15 degrees with respect to the normal to the substrate surface. This light spreads to about 20 degrees due to the difference in the refractive index between the glass and the atmosphere. The vertically incident light is reflected by the reflection film 6, but has a reflection angle of 60 degrees. This light is totally reflected on the surface of the glass substrate 1 and does not go outside. That is, when the liquid crystal is in a transparent state, the liquid crystal display element looks black when viewed from the front at an angle of about 20 degrees or less with respect to a perpendicular to the substrate surface. On the other hand, when the liquid crystal is in the scattering state, the light is scattered by the liquid crystal and the light incident on the reflection surface becomes 45 degrees or more (the angle with respect to the perpendicular to the substrate), so that the light is also reflected in the front direction. , The pixels appear bright. As described above, according to the second embodiment, a very bright liquid crystal display device with good visibility is obtained although the viewing angle direction is restricted.

FIGS. 16 and 17 show another embodiment of the V-shaped groove. In each of the V-shaped grooves, the reflection film 6 is formed only on one surface, and is not formed on one of the facing surfaces. The surface on which the reflective film is not formed may be the transparent portion 9 or the light absorbing portion 9. With such a configuration, when the liquid crystal is not in the scattering state, if the liquid crystal is formed on a 45-degree slope as in the reflection film of FIGS. (The angle with respect to the liquid crystal display element) is absorbed or transmitted and goes out of the glass substrate 2 (to the rear side of the liquid crystal display element).
Alternatively, the light reflected by the reflection film 6 is directed to the surface of the glass substrate 1 at an angle of 45 degrees or more, and is totally reflected there, and does not emerge from the surface of the liquid crystal display element.
On the other hand, when the liquid crystal is in the scattering state, light is emitted from the display element surface as described above, and thus, in this configuration, a favorable display can be obtained without any restriction in the viewing angle direction.

In the second embodiment, the angles formed by the V-shaped grooves are 45 degrees, 90 degrees, and 120 degrees, and the pitch is half the pixel pitch. However, the present invention is not limited to this. Further, even if the concave portion of the groove portion is partially flat or the convex portion is partially flat like the V-shaped groove portion in FIG. 4, the characteristics are slightly inferior, but there is no problem. Further, the direction of the V-shaped groove is not limited to one direction as shown in FIG. 14, but may be two directions perpendicular to each other as shown in FIG. 15 or more. Desirably, the direction is parallel to and perpendicular to the direction of the pixel stripe, but is not limited to this. These should be designed according to the required characteristics, including black and white without a color filter, so that the light scattered by the scattered liquid crystal does not affect adjacent pixels as much as possible. preferable. Also,
Although an effect similar to that of the second embodiment cannot be obtained by externally attaching a reflection plate as shown in FIG. 6, a sufficient effect can be obtained by using a thin glass substrate.

(Embodiment 3) FIG. 3 is a cross-sectional view of a liquid crystal display device showing another embodiment of the present invention. Although a transparent electrode is not shown, a transparent electrode is formed on the color filter 4 and the flattening layer 5 so as to face the liquid crystal 3 and face the liquid crystal 3. The pixel size of the display pixel of the liquid crystal display element is the pixel size of the color filter.
The pitch of the U-shaped groove is equal to the pixel pitch,
The angle formed by the V-shape is 90 degrees. Embodiment 3
Since the liquid crystal 3 is of a light scattering type, the liquid crystal 3 may be subjected to an alignment treatment as necessary. In the third embodiment, no alignment film is formed and no alignment treatment is performed.

Next, the operation of the liquid crystal display device having such a configuration will be described with reference to FIG. In the third embodiment, the liquid crystal enters a transparent state or a light scattering state by applying or not applying a voltage. First, when the liquid crystal is in a transparent state, the light that has passed through the glass substrate 1 reaches the reflection film 6 as it is. Liquid crystal 3
As described in the first embodiment, the incident angle of light incident on the substrate (the angle with respect to the perpendicular of the glass substrate 1) is about 45 degrees or less. Therefore, the light that reaches the reflection film 6 is reflected at an angle of 45 degrees or less with respect to the perpendicular to the glass substrate 1 in one reflection because the reflection film 6 is inclined 45 degrees with respect to the substrate surface. However, since the light is totally reflected on the surface of the glass substrate 1, it does not go out of the liquid crystal display element. In addition, as shown in FIG. 11, light incident on a certain pixel of the liquid crystal display element is reflected twice by the reflective film 6 and is reflected through an adjacent pixel. Being lined with patina, that is, light that has passed red will be reflected and will pass through the adjacent blue or green, and eventually the light will be absorbed there and will not exit. Next, when the liquid crystal enters a light scattering state, the light incident on the liquid crystal 3 is scattered and changes its direction. Some of the incident angles (the angles with respect to the perpendicular to the glass substrate 1) are 45 degrees or more, so that the light passes through the same pixel due to reflection on the reflection film,
It goes out of the liquid crystal display element.

In this way, a bright liquid crystal display without using a polarizing plate is possible. In the configuration of FIG. 3, light incident near the bottom of the V-shaped groove is reflected through the same pixel. That is, since the light always leaks, the contrast is slightly inferior. Another embodiment shown in FIG. 4 has been devised to improve this. In FIG. 4, the concave portion of the V-shaped groove is partially flat.
By doing so, as shown in FIG. 12, light incident on the bottom of the groove is necessarily absorbed by the adjacent pixels (color filters), and the contrast is further improved as compared with the configuration of FIG.

In the third embodiment, the V-shaped angle of the groove of the reflection surface is set to 90 degrees, which is the most desirable.
The same effect can be obtained even at 0 degrees, and the present invention is not limited to this, and it is preferable to design according to required characteristics. Further, the direction of the V-shaped groove is not limited to one direction as shown in FIG. 14 but may be two directions or more perpendicular thereto as shown in FIG. No problem. In addition, as in the case of the V-shaped groove in FIG. 4, not only is the concave part of the groove partly flat, but also if the convex part is partially flat, the characteristics are slightly inferior, but the problem remains. Absent.

As shown in FIG. 6, even if an external reflector is used, the same effect as in the third embodiment cannot be obtained, but a sufficient effect can be obtained by using a thin substrate.

As described above, according to the present invention, the reflection film 6 is formed in the V-shaped groove at the same pitch as the color filter (pixel pixel).
By absorbing light by passing through two color filters of different colors, the characteristics of a light-scattering and reflective liquid crystal display device can be significantly improved.

(Embodiment 4) FIG. 5 is a sectional view of a liquid crystal display device showing another embodiment of the present invention. Although not shown, a transparent electrode is formed on the color filter 4 and the flattening layer 5 so as to face the liquid crystal 3 and face the liquid crystal 3. The pixel size of the display pixel of the liquid crystal display element is the pixel size of the color filter, the pitch of the V-shaped groove of the reflection film 6 is equal to the pixel pitch, and the angle formed by the V-shape is 90 degrees. Further, a light absorbing wall 7 made of a resin mixed with carbon fine particles is formed at the bottom of the V-shaped groove. In the fourth embodiment, since the liquid crystal 3 is of a light scattering type, an alignment treatment may be performed as needed. In the fourth embodiment, no alignment film is formed and no alignment treatment is performed.

Next, the operation of the liquid crystal display device having such a configuration will be described. In the fourth embodiment, as shown in FIG. 13, the light incident on the glass substrate 1 has an incident angle (an angle with respect to a perpendicular to the glass substrate 1) of 45 degrees or less.
Whether the light is absorbed by the light absorbing wall 7 provided at the lower part of the V-shaped groove, or is totally reflected on the surface of the glass substrate 1 when the reflection angle (angle with respect to the perpendicular of the glass substrate 1) is 45 degrees or more. It is. Therefore, this configuration also has higher contrast than the configuration of FIG. Moreover, in this configuration, it is not necessary to absorb light by two color filters of different colors, so that if the pitch of the groove is less than the pixel pitch, it is not necessary to make the pitch of the groove equal to the pixel pitch, and The direction does not need to be the same as the direction of the color filter or pixel.

In the fourth embodiment, the angle formed by the V-shape is the most desirable 90 degrees. However, the same effect can be obtained even when the angle is 80 degrees or 100 degrees, and the present invention is not limited to this. They are,
It is preferable to design according to required characteristics, including black and white without a color filter. Further, there is no problem if the direction of the V-shaped groove is not only one direction as shown in FIG. 14 but also two directions perpendicular to each other as shown in FIG. 15 or more. As in the case of the letter-shaped groove, not only is the concave part of the groove partly flat, but also if the convex part is partially flat, the characteristics are slightly inferior, but there is no problem. Further, even if the reflection plate is externally provided as shown in FIG. 6, the effect of the fourth embodiment cannot be obtained, but a sufficient effect can be obtained by using a thin glass substrate.

As described above, according to the present invention, the light incident on the glass substrate is absorbed by the light absorbing wall 7 provided at the lower part of the V-shaped groove, or the reflected light is reflected by the reflecting film 6. By increasing the angle (the angle with respect to the perpendicular of the glass substrate 1) and performing total reflection on the surface of the glass substrate 1, the display performance of the scattering type reflection type liquid crystal display device is greatly improved.

In the first, second, third and fourth embodiments, glass is used as the substrate. However, even if the substrate is a film or plastic, there is no problem if it is designed in consideration of the refractive index. It does not matter if the substrate is formed on either of the pair of substrates.

[0033]

The present invention is configured as described above and has the following features. That is, the present invention
A liquid crystal display element in which liquid crystal is sealed between a pair of electrode substrates,
A liquid crystal display device comprising: a reflecting plate, wherein the reflecting surface of the reflecting plate is formed as a stripe-shaped groove, and the cross section of the groove is V-shaped or substantially V-shaped, whereby the reflecting plate is polarized. Since the axis is changed, when the guest-host type is used as the liquid crystal display element, the display performance can be greatly improved, and the utility value in other liquid crystal display modes is great.

Further, the reflecting plate of the present invention can be designed so that light incident on the glass substrate is not reflected in the front direction by forming a reflecting film only on one side of the V-shape or the V-shape. Alternatively, the reflection angle of the reflected light (the angle with respect to the vertical line of the glass substrate) can be increased so that the light is totally reflected on the surface of the glass substrate. Furthermore, if the pitch of the V-shaped groove is made equal to the pitch of the pixels of the color filter, light can be absorbed by passing through two color filters of different colors depending on the angle of the V-shape.
If a light scattering type liquid crystal is used, a very bright reflective color liquid crystal display device can be realized.

Further, in the present invention, a light absorbing wall is provided at the lower part of the V-shaped groove, and the incident light in the glass substrate is
Absorbed by the light-absorbing wall provided at the lower part of the U-shaped groove, or by increasing the reflection angle of the reflected light (the angle with respect to the perpendicular to the glass substrate) on the reflection film and totally reflecting the light on the surface of the glass substrate Thus, the display performance of the light scattering type reflection type liquid crystal display device is greatly improved.

[Brief description of the drawings]

FIG. 1 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 3 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 4 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 5 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 6 is a sectional view of a liquid crystal display device according to an embodiment of the present invention.

FIG. 7 is a perspective cross-sectional view showing a reflection surface according to an embodiment of the present invention, and a polarization axis of reflected light.

FIG. 8 is a side sectional view showing a reflecting surface according to an embodiment of the present invention and a polarization axis of reflected light.

FIG. 9 is a plan view showing a reflection surface according to an embodiment of the present invention, and a polarization axis of reflected light.

FIG. 10 is a diagram of incident and reflected light according to an embodiment of the present invention.

FIG. 11 is a diagram of incoming and reflected light according to an embodiment of the present invention.

FIG. 12 is a diagram of incident and reflected light according to an embodiment of the present invention.

FIG. 13 is a diagram of incoming and reflected light according to an embodiment of the present invention.

FIG. 14 is a perspective view of a reflection surface according to an embodiment of the present invention.

FIG. 15 is a perspective view of a reflection surface according to an embodiment of the present invention.

FIG. 16 is a diagram of incoming and reflected light according to an embodiment of the present invention.

FIG. 17 is a diagram of incoming and reflected light according to an embodiment of the present invention.

FIG. 18 is a cross-sectional view of a conventional liquid crystal display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Glass substrate 3 Liquid crystal 4 Color filter 5 Flattening layer 6 Reflection film 7 Light absorption wall 8 Polarization plate 9 Light absorption part or transparent part 10 Reflection plate 11 Adhesion part

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H042 DA02 DA04 DA12 DB00 DD01 DE04 2H088 EA02 EA23 HA01 HA02 HA12 HA15 JA05 JA13 MA06 2H091 FA02Y FA16Z FD23 HA07 HA10 LA15 LA17 LA18

Claims (6)

[Claims] 1. A liquid crystal display device comprising: a liquid crystal display element in which liquid crystal is sealed between a pair of electrode substrates; and a reflection plate, wherein the reflection surface of the reflection plate is formed as a stripe-shaped groove. A liquid crystal display device characterized in that the groove has a V-shaped or substantially V-shaped cross section. 2. The liquid crystal display element is a guest-host type liquid crystal display element enclosing liquid crystal mixed with a dichroic dye, wherein the pitch of the groove is less than the pixel pitch of the pixels of the liquid crystal display element. Item 2. The liquid crystal display device according to item 1. 3. The liquid crystal display device according to claim 1, wherein the liquid crystal display element is of a light scattering type. 4. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is a light scattering type liquid crystal display element in which light scattering type liquid crystal is sealed between a pair of electrode substrates having a color filter formed on at least one substrate. 2. The liquid crystal display device according to claim 1, wherein a pitch is equal to a pitch of pixels of the color filter. 5. The liquid crystal display device is of a light scattering type,
The liquid crystal display device according to claim 1, wherein a light absorbing wall is formed at a bottom of the groove. 6. An image display application device comprising the liquid crystal display device according to claim 1.