JP2000241834A - Liquid crystal display device using minute refractive display method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a liquid crystal display device which uses refraction or diffraction. SOLUTION: The liquid crystal display device consists of a pair of substrates, plural scanning electrodes and signal wirings disposed in a matrix on one of the transparent substrates so that region between the transparent substrates is divided into plural pixel regions by the scanning wirings and signal wirings, plural counter wirings which are disposed on the other transparent substrate and which are parallel to the scanning electrodes and a pair of alignment controlling material layers and a liquid crystal compsn. layer laminated between the pixel regions. The display device has such a structure that the scanning wirings and counter wirings on the pair of transparent substrates in each pixel region are staggered and that these staggered wiring are not overlapped with each other in the normal direction of the substrate.

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, and more particularly to a display device using no polarizing plate and a projection / reflection display device.

[0002]

2. Description of the Related Art As a conventional liquid crystal display device, a twisted nematic (TN) mode using optical rotation, a birefringence control (ECB) mode using optical coherence, and a super twisted nematic (STN) mode are well known. However, each mode requires one or two polarizing plates, and therefore has a drawback that a sufficient contrast and viewing angle cannot be obtained and a response speed is slow. SID International Symposium Digest of Technic
al Papers, vol.XX1X, p.718, (1998).
Although this liquid crystal display device has a wide viewing angle, it has a disadvantage that the response speed is slow. In addition, a liquid crystal display device having a zigzag electrode is an IDW Proceedings of The Fourth In
ternational Display Workshops, p.175, (1997). This liquid crystal display device has a wide viewing angle and a high response speed, but has a drawback of low luminance and high drive voltage.

[0003]

SUMMARY OF THE INVENTION Birefringence control (ECB)
Both the mode and the super twisted nematic (STN) mode have drawbacks in that they have low contrast and are not suitable for displaying moving images due to their low response speed. In the twisted nematic (TN) mode, the response speed is fast, but the viewing angle is very narrow. Twisted nematic (TN) mode, birefringence control (EC)
B) Mode and Super Twisted Nematic (STN)
In each of the modes, one or two polarizing plates are required, so that transmitted light or reflected light is partially absorbed by the polarizing plates. Therefore, the brightness of the display device is reduced, and the contrast is also reduced. The backlight was strengthened to compensate for the brightness, but the power consumption was also increased. Further, the birefringence control (ECB) mode and the super twisted nematic (STN) mode are colored by birefringence, so that an optical compensating film or the like is required, so that the optical design is difficult and the cost is increased. A first object of the present invention is to provide a liquid crystal display device that achieves high contrast, high-speed response, or a wide viewing angle by utilizing refraction or diffraction. A second object is to provide a liquid crystal display device that achieves high luminance by reducing the number of polarizing plates.

[0004]

Means for Solving the Problems A first invention of the present invention is:
As shown in FIG. 1, a pair of substrates are arranged, a plurality of scanning electrodes and signal wirings are arranged in a matrix on one of the transparent substrates, and the area between the transparent substrates is each scanning wiring and each signal wiring. A plurality of pixel regions are divided by wiring, and a plurality of opposing wirings are arranged on the other transparent substrate in parallel with the scanning electrodes, and a pair of alignment control material layers and a liquid crystal composition are provided between each pixel region. In a liquid crystal display element in which layers are stacked, each scanning wiring and a counter wiring of a pair of transparent substrates in each pixel region are in a zigzag shape, and each has a structure in which they do not overlap in the normal direction of the substrate. The present invention relates to a liquid crystal display device characterized by the above-mentioned.

[0005] A second invention relates to a liquid crystal display device characterized in that one polarizing plate is arranged in the liquid crystal display device according to the first invention as shown in FIG. According to a third invention, as shown in FIG. 3, a liquid crystal display element according to the first invention is provided with a single polarizing plate and a λ / 4 wavelength plate. About. The fourth invention relates to a liquid crystal display device characterized in that the liquid crystal display device according to the first invention is arranged so as to be sandwiched between two polarizing plates as shown in FIG.

According to a fifth aspect of the present invention, as shown in FIG. 5, the liquid crystal display element according to the first aspect of the present invention is arranged in a structure in which a reflection plate is disposed on the side opposite to one polarizing plate. And a liquid crystal display element. A sixth invention relates to the liquid crystal display device according to the fourth invention, wherein two polarizing plates are arranged in a linearly polarized light arrangement and in a parallel Nicol state. A seventh invention relates to the liquid crystal display device according to the fourth invention, wherein two polarizing plates are arranged in a linearly polarized light arrangement and crossed Nicols. The eighth invention relates to the liquid crystal display device according to the first to fifth inventions, wherein the zigzag angle (θ) between each scanning electrode and the counter electrode in each pixel region is 60 ° to 120 °. .

A ninth aspect of the present invention is the liquid crystal according to the first to fifth aspects, wherein the width (W) of each scanning electrode and the counter electrode in each pixel region is independently 5 to 35 μm. It relates to a display element. According to a tenth aspect, the distance (L) between each scanning electrode or each counter electrode in each pixel region is 20 to 200 μm.
The present invention also relates to the liquid crystal display devices according to the present invention. An eleventh invention relates to the liquid crystal display device according to the first to fifth inventions, wherein the thickness (D) of the liquid crystal composition layer is 3 to 30 μm.

[0008] The liquid crystal display device of the present invention is configured as shown in FIG. A pair of glass substrates (1) are arranged, a plurality of scanning electrodes (5) and signal wirings (6) are arranged in a matrix on one of the transparent substrates (2), and the area between the transparent substrates is reduced. Each scanning line and each signal line are divided into a plurality of pixel regions. On the other transparent substrate (2), a plurality of opposing lines (7) are arranged in parallel with the scanning electrodes. A pair of alignment control material layers (3) and a liquid crystal composition layer (4) are laminated between them. FIG. 6 shows a plan view and a cross-sectional view of this one pixel. In the pixel having the cell thickness (D), the scanning electrodes and the opposing electrodes are arranged at an electrode interval (W) so that the scanning wiring having the electrode width (W) does not overlap with the opposing wiring. When a signal is applied to each scanning wiring and each signal wiring, a signal having a different potential difference is applied to a pair of signal wirings belonging to each pixel region each time a scanning signal is applied to each scanning wiring. When a signal having a different potential difference is applied to each signal wiring, an electric field according to the potential difference acts on the liquid crystal in each pixel region, and the liquid crystal molecules rise at a certain elevation angle with respect to the transparent substrate surface. Thereby, the orientation of the liquid crystal in each pixel region can be controlled as shown in FIG. At this time, since the liquid crystal composition is obliquely oriented with respect to the substrate, a refraction or diffraction phenomenon occurs, and the light transmission path can be controlled.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION There are approximately three optical arrangements of the present invention. First, there is a diffraction arrangement that does not use a polarizing plate, in which random light is incident and outgoing light is extracted using the light diffraction effect of liquid crystal molecules induced by an electric field. Secondly, there is a circularly polarized light arrangement in which one polarizing plate and a λ / 4 wavelength plate are arranged together. The circularly polarized light arrangement utilizes the light diffraction effect of liquid crystal molecules induced by an electric field upon incidence of circularly polarized light. This is to extract the emitted light. Third, there is a linear polarization arrangement using one or two polarizing plates. Regarding the incident direction of the linearly polarized light, there are a method in which the direction of the light propagation axis of the linearly polarized light matches the liquid crystal alignment direction of the incident side glass substrate (parallel incidence) and a method in which the direction is perpendicular (vertical incidence).

[0010] Further, regarding the polarizing plate, a single polarizing plate arrangement for inducing a diffraction effect due to the extraordinary light of the incident light, a diffraction effect due to the extraordinary light of the incident light, and blocking the ordinary light of the outgoing light 2
It is distinguished by the polarizing plate arrangement. Regardless of the orientation of the liquid crystal composition layer, either the anti-parallel (AP) orientation or the twisted nematic (TN) orientation, the refraction phenomenon is dominant at parallel incidence and the diffraction phenomenon is dominant at vertical incidence. For example, in a linear polarization arrangement using two polarizing plates, when the incident light is parallel incident and the liquid crystal is in the TN alignment, when no voltage is applied, the light first enters the polarizing plate on the incident light side, and a certain polarization axis It is replaced by light.

The light is transmitted because the orientation axis of the liquid crystal on the incident side coincides with the polarization axis of the incident light. Due to the TN orientation, the polarization axis is twisted by 90 ° along the liquid crystal molecules, passes through the cell, and reaches the opposite polarizer. At this time, if the two polarizing plates are parallel Nicols, the polarization axis of the outgoing light and the polarizing axis of the polarizing plate on the outgoing light side are shifted by 90 °, so that the outgoing light is not transmitted and a normally black mode is set. Conversely, if the two polarizing plates are crossed Nicols, the polarization axis of the outgoing light coincides with the polarization axis of the outgoing light-side polarizing plate, so that the outgoing light passes through the polarizing plate and becomes a normally white mode. For example, when a voltage is applied in the normally white mode, the liquid crystal starts to rise, and light refraction can be seen with the liquid crystal alignment deformation. The refraction angle of the emitted light gradually increases as the voltage increases. As shown in FIG. 7, the refraction angle is maximized when the liquid crystal is oriented obliquely at about 45 °.

When the orientation of the liquid crystal is the AP orientation, the polarizing plate 1
The contrast is good in the case of parallel Nicols with one or two polarizing plates. In the case of the TN orientation, the contrast is good in the case of crossed Nicols with one polarizing plate or two polarizing plates. In the conventional mode, by using one or two polarizing plates, the contrast was significantly reduced. However, when the method of the present invention is used, high contrast can be realized not only when no polarizing plate is used but also when one or two polarizing plates are used. The zigzag angle (θ) between each scanning electrode and the counter electrode in each pixel area is preferably 60 ° to 120 °. Preferably, the zigzag angle (θ) between each scanning electrode and the counter electrode in each pixel region is 80 ° to 100 °. In particular, when the zigzag angle (θ) between each scanning electrode and the counter electrode is 90 °, the intensity of the refracted light becomes maximum.

It is desirable that the width (W) of each scanning electrode and counter electrode in each pixel region is independently 5 to 35 μm. Preferably, the width (W) of each scanning electrode and counter electrode in each pixel region is independently 10 to 25 μm. If the width of the electrode is less than 5 μm, an electric field is not generated well and liquid crystal molecules are not well aligned, which is not preferable. On the other hand, when the width of the electrode is larger than 35 μm, the aperture ratio is significantly reduced, which is not preferable.

It is desirable that the distance (L) between each scanning electrode or each counter electrode in each pixel region is 20 to 200 μm. Preferably, the interval (L) between each scanning electrode or each counter electrode in each pixel region is preferably 40 to 150 μm. If the distance between the electrodes is less than 20 μm, the aperture ratio is significantly reduced, which is not preferable. On the other hand, if the distance between the electrodes is larger than 200 μm, the liquid crystal molecules do not sufficiently rise when a voltage is applied, which is not preferable.

The thickness (D) of the liquid crystal composition layer is 3 to 30 μm.
It is desirable that Preferably, the thickness (D) of the liquid crystal composition layer is 3 to 25 μm. If the thickness of the liquid crystal composition layer is less than 3 μm, it is not preferable because the control of the cell gap becomes difficult and the yield remarkably deteriorates. Further, when the thickness of the liquid crystal composition layer is larger than 30 μm, the liquid crystal molecules do not sufficiently rise when a voltage is applied, which is not preferable.

The liquid crystal may have a dielectric anisotropy (Δε) of either positive or negative for the basic purpose of obtaining an oblique 45 ° orientation after voltage application, and the initial orientation is a homogeneous orientation, a TN orientation, a homeotropic orientation. Either may be used. As the alignment controlling substance, a polyimide type alignment film, a soluble polyimide type alignment film, and a polyamic acid type alignment film are preferable. The orientation control material layer is made of metal or SiO ₂
There is no problem even if it is vapor-deposited. In a homogeneous alignment or a homeotropic alignment, refraction and diffraction occur in one or both depending on conditions. Refracted light and diffracted light can be selectively used by changing the presence or absence of a polarizing plate, the type of orientation, the polarization direction of incident light, and the like.

[0017]

According to the above-mentioned means, when a signal is applied to each scanning wiring and each signal wiring in accordance with video information, each time a scanning signal is applied to each scanning wiring, a pair of signals belonging to each pixel region are applied. Signals having different potential differences are applied to the wiring. When a signal having a different potential difference is applied to each signal wiring, an electric field according to the potential difference acts on the liquid crystal in each pixel region, and the liquid crystal molecules rise at a certain elevation angle with respect to the transparent substrate surface. As a result, the orientation of the liquid crystal in each pixel region is changed as shown in FIG.
Can be controlled as follows. At this time, since the liquid crystal composition is obliquely oriented with respect to the substrate, a refraction or diffraction phenomenon occurs, and the light transmission path can be controlled.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. (Example 1) The orientation film was of TN orientation and no polarizing plate was used. FIG. 2 shows the configuration at that time. The electrode width (W) is 1
5 μm, electrode spacing (L) is 55 μm, cell thickness (D) is 2
5 μm and the zigzag angle (θ) of the electrode was 90 °.
The liquid crystal composition has a clearing point of 103 ° C., a refractive index anisotropy (Δn) of 0.219, and a dielectric anisotropy (Δε) of 29.
1 and the alignment film was PSI-G-4001 (manufactured by Chisso, pret
ilt = 4 ゜). The voltage-transmittance measurement was performed using He-N as the light source.
e-laser, detector, photodiode, linear amplifier, digital multimeter (ADVANTEST, R6451)
Using A), a 1 KHz rectangular wave was applied with an arbitrary waveform generator (HP, 33120A). The threshold voltage (V90) at the 90% transmittance in the normally white mode. The threshold voltage (V90) was 1.38 V and the contrast ratio was 40: 1.

(Example 2) The alignment film was antiparallel oriented, and two polarizing plates were arranged in linearly polarized light and parallel Nicols. The configuration at that time is shown in FIG. Others were the same as Example 1. The threshold voltage (V90) is 1.02
V, the contrast ratio was 462: 1.

Example 3 The alignment film was of TN orientation, and two polarizing plates were arranged in a linearly polarized light and crossed Nicols. The configuration at that time is shown in FIG. Others were the same as Example 1. The threshold voltage (V90) was 2.10 V and the contrast ratio was 168: 1.

[0021]

As described in detail above, according to the present invention,
A liquid crystal display device that achieves high contrast, high-speed response, or a wide viewing angle by utilizing the refraction or diffraction phenomenon caused by the orientation of liquid crystal when liquid crystal molecules in each pixel region rise at a certain elevation angle with respect to the transparent substrate surface. provide. Another object of the present invention is to provide a liquid crystal display device that achieves high luminance by reducing the number of polarizing plates.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a display device described in claim 1;

FIG. 2 is an explanatory diagram of a display device described in claim 2;

FIG. 3 is an explanatory diagram of a display device described in claim 3;

FIG. 4 is an explanatory diagram of a display device described in claim 4;

FIG. 5 is an explanatory diagram of a display device according to claim 11;

FIG. 6 is a plan view and a cross-sectional view of a pixel.

FIG. 7 is an explanatory diagram of liquid crystal molecules when a voltage is applied.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Transparent substrate 3 Alignment control material layer 4 Liquid crystal composition layer 5 Scanning wiring 6 Signal wiring 7 Counter wiring 8 Polarizing plate 9 λ / 4 wavelength plate 10 Reflector

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H088 EA44 HA02 HA03 HA06 HA17 HA18 HA21 JA05 JA10 JA11 KA02 KA05 MA02 MA07 2H092 GA13 GA20 GA26 PA02 PA07 PA11

Claims (11)

[Claims] A pair of substrates are arranged, a plurality of scanning electrodes and signal wirings are arranged in a matrix on one of the transparent substrates, and a region between the transparent substrates is formed by each scanning wiring and each signal wiring. It is divided into a plurality of pixel regions, a plurality of opposing wirings are arranged on the other transparent substrate in parallel with the scanning electrodes, and a pair of alignment control material layer and liquid crystal composition layer are provided between each pixel region. In the stacked liquid crystal display element, each of the scanning wiring and the counter wiring of the pair of transparent substrates in each pixel region has a zigzag shape, and each has a structure in which they do not overlap in the normal direction of the substrate. Characteristic liquid crystal display element. 2. A liquid crystal display element according to claim 1, wherein one polarizing plate is arranged on the liquid crystal display element according to claim 1. 3. A liquid crystal display device according to claim 1, wherein one polarizing plate and a λ / 4 wavelength plate are arranged together with the liquid crystal display device according to claim 1. 4. A liquid crystal display device according to claim 1, wherein the liquid crystal display device is disposed so as to be sandwiched between two polarizing plates. 5. A liquid crystal display device according to claim 1, wherein the liquid crystal display device is arranged in a structure in which a reflection plate is arranged on a side opposite to one polarizing plate. 6. The liquid crystal display device according to claim 4, wherein the two polarizing plates are arranged in a linear polarization arrangement and a parallel Nicol arrangement. 7. The liquid crystal display device according to claim 4, wherein the two polarizing plates are arranged in linearly polarized light and crossed Nicols. 8. The liquid crystal display device according to claim 1, wherein a zigzag angle (θ) between each scanning electrode and the counter electrode in each pixel region is 60 ° to 120 °. 9. The liquid crystal display device according to claim 1, wherein the width (W) of each scanning electrode and the counter electrode in each pixel region is independently 5 to 35 μm. 10. The distance (L) between each scanning electrode or each counter electrode in each pixel region is 20 to 200 μm.
The liquid crystal display device according to claim 1, wherein m is m. 11. The thickness (D) of the liquid crystal composition layer is 3 to 25.
The liquid crystal display device according to claim 1, wherein the thickness is μm.