JPH10268322A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a memory type bistable liquid crystal display device which uses flickerless, high-duty chiral nematic liquid crystal. SOLUTION: A scanning electrode member 4 having scanning electrodes 2 and an orientation film 3 formed in order on a transparent base 1 and a signal electrode member 7 having signal electrodes 7 and an orientation film 8 formed in order on a transparent substrate 6 are arranged opposite each other across chiral nematic liquid crystal 10 so that the scanning electrodes 2 and signal electrodes 7 cross each other, thus forming rectangular pixel areas. This chiral nematic liquid crystal 10 initially has twisted structure and is applied with a voltage which causes Frederick's dislocation in the initial state to have two metastable states different from the initial state, and spacers 16 are arranged only in non-pixel areas between the scanning electrode members 4 and signal electrode members 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a memory-type bistable liquid crystal display using a chiral nematic liquid crystal.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 7-248485 proposes a memory-type bistable liquid crystal display device using a chiral nematic liquid crystal. According to this memory-type bistable liquid crystal display device, there has been proposed a technique of providing a signal waveform in which a delay time is introduced between a reset pulse and a selection pulse, thereby shortening the delay time.

[0003] That is, it is said that the transition to the metastable state (0 ° or 360 °) after the Freedericks transition is related to the backflow phenomenon. In order to make the most of this phenomenon, a reset pulse and a reset pulse are required. An interval is provided between the selection pulses, which makes it easier to shift to a metastable state. As a result, the writing time (selection time) per one line of the matrix driving is shortened, and the flicker-less high duty is achieved. It is intended to realize simple matrix driving.

[0004]

According to the above proposal, the narrower the liquid crystal layer thickness, the shorter the selection time.
It is necessary to reduce the thickness of the liquid crystal layer considerably and to make the layer thickness uniform over the display area. To satisfy this requirement, a resin spacer is interposed between two substrates while being appropriately dispersed. I have.

[0005] However, there is a problem that even if the two substrates are bonded via the spacer, it is difficult to uniformly set the desired thickness of the liquid crystal layer in the display area.

Also, in this bonding, there is a problem that the spacer alone cannot withstand the pressure applied to the substrate, which causes display failure due to the flow of the liquid crystal.

Accordingly, the present invention has been completed in view of the above circumstances, and an object of the present invention is to provide a liquid crystal display device which realizes a simple matrix driving with a high and low duty without flicker by making the liquid crystal layer thickness small and uniform. Is to do.

[0008]

According to the present invention, there is provided a liquid crystal display device comprising: a scanning electrode member in which a scanning electrode pattern in which a large number of scanning electrodes are arranged on a transparent substrate;
A signal electrode pattern in which a number of signal electrodes are arranged on a transparent substrate and a signal electrode member in which an alignment film is sequentially formed, and a chiral nematic liquid crystal is formed so that the scanning electrode pattern and the signal electrode pattern intersect. The chiral nematic liquid crystal has a twisted structure in an initial state, and applies a voltage that causes a Freedericks transition in the initial state,
A memory-type bistable type having two metastable states different from the initial state due to the voltage difference, and a spacer is arranged only in a non-pixel region between the scanning electrode member and the signal electrode member. It is characterized by having done.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A bistable liquid crystal display device according to the present invention will be described with reference to FIGS. FIG. 1 is a plan view of the liquid crystal display device of the present invention, and FIG. 2 is an enlarged vertical sectional view of a main part thereof. Also,
FIGS. 3 (A) and 3 (B) are enlarged cross-sectional views of main parts, respectively, and FIGS. 4 (A) and 4 (B) are also enlarged cross-sectional views of main parts, respectively. 2 is a scanning electrode made of ITO or the like, 3 is an alignment film, and these constitute a scanning electrode member 4. As for the other signal electrode member 5, 6 is a transparent substrate made of glass or the like. , 7 are signal electrodes made of ITO or the like, and 8 is an alignment film. The alignment films 3 and 8 are made of polyimide and have been subjected to a rubbing process.

The scanning electrode 2 and the signal electrode 7 are patterned so as to intersect with each other, and each intersection is formed into a rectangular pixel region 9 (for example, 300 μm × 300 μm), the pixel pitch is set to 20 μm, and scanning is performed. The electrode member 4 and the signal electrode member 5 are composed of a chiral nematic liquid crystal 10.
(A liquid crystal composition exhibiting a nematic phase at room temperature [E. Me
rck: ZLI-1557] and an optically active additive [E. Merck: S-811] and the helical pitch P is adjusted to 2.7 μm).

As shown in FIG. 1, a seal member 11 for enclosing a chiral nematic liquid crystal 10 is provided between the members 4 and 5 around the display area. Provided and injected by a vacuum injection method. Further, as shown in FIG. 2, polarizing plates 13 and 14 are provided outside the two transparent substrates 1 and 6.

As shown in FIGS. 3A and 3B, a columnar spacer 16 and a prismatic spacer 17 are provided only in the non-pixel region 15 between the scanning electrode member 4 and the signal electrode member 5. And the liquid crystal layer thickness was 1.5 μm.

The spacers 16 and 17 are formed by a usual photolithography method. More specifically, a resist is applied on one of the rubbed alignment films 3 or 8, exposed and developed using a photomask, and disposed only in the non-pixel region 15. Are formed by making the thickness of the layers uniform. Spacers 16, 17
Is adjusted by the thickness of the applied resist in accordance with the desired thickness of the liquid crystal layer.

On the other hand, instead of the photolithography method for the spacers 16 and 17, an insulating film such as SiO ₂ is printed or applied on one of the rubbed alignment films 3 or 8, and further on the insulating film. It may be formed by applying a resist in the same manner as in a normal photolithography method and performing exposure, development, and etching using a photomask.

According to the liquid crystal display device having the above configuration, the chiral nematic liquid crystal has a twisted structure in an initial state, and the initial state is changed by a voltage applied after applying a voltage that causes a Freedericks transition in the initial state. Memory type bistable type having two different metastable states. For example, when the positional relationship (crossed Nicols) of the polarizing plates 13 and 14 is such that the twisted state of φ ₀ + π (= 360 °) becomes a dark state with respect to the twist angle φ ₀ (= 180 °) in the initial state. In the bright state, the twist angle is φ ₀ −π (= 0 °).

Thus, in the liquid crystal display device of the present invention, the thickness of the spacers 16 and 17 is adjusted according to the desired thickness of the liquid crystal layer, and the spacers 16 and 17 are arranged only in the non-pixel region 15. The layer thickness of the layer could be equalized. In addition, the display failure caused by the flow of the liquid crystal which occurred when the conventional liquid crystal panel was pressed could be prevented by the spacers 16 and 17 provided only in the non-pixel region 15.

As a modification of the liquid crystal display device of the present invention, as shown in FIGS. 4A and 4B, adjacent square-shaped pixel electrodes 9 are used instead of the columnar or prismatic spacers 16 and 17. In the same manner, wall-shaped spacers 18 and 19 may be provided in the same process as described above. In this case, the support area is further increased, so that the thickness of the liquid crystal layer can be made uniform and display defects can be reduced. It is even more advantageous for prevention. Further, by providing these wall-shaped spacers 18 and 19, the liquid crystal can be injected without any trouble in the arrangement relationship with the liquid crystal injection port 12.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements may be made without departing from the scope of the present invention. For example, a color liquid crystal display device provided with a color filter has a similar effect.

[0019]

As described above, according to the memory-type bistable liquid crystal display device of the present invention, the spacer is provided only in the non-pixel region between the scanning electrode member and the signal electrode member.
The thickness of the liquid crystal layer can be reduced and made uniform, thereby achieving a high duty without flicker and a high definition display with many scanning lines.

In the liquid crystal display of the present invention,
By providing such spacers, display defects due to the flow of liquid crystal did not occur.

[Brief description of the drawings]

FIG. 1 is a plan view of a liquid crystal display device of the present invention.

FIG. 2 is an enlarged longitudinal sectional view of a main part of the liquid crystal display device of the present invention.

FIGS. 3A and 3B are enlarged cross-sectional views of a main part of the liquid crystal display device of the present invention.

FIGS. 4A and 4B are enlarged cross-sectional views of a main part of the liquid crystal display device of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 6 Transparent substrate 2 Scan electrode 3, 8 Alignment film 4 Scan electrode member 5 Signal electrode member 7 Signal electrode 9 Pixel region 10 Chiral nematic liquid crystal 11 Seal member 12 Liquid crystal inlet 13, 14 Polarizer 15 Non-pixel region 16 Column shape Spacer 17 Square pillar spacer 18, 19 Wall spacer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiromi Fukuoka 999-3 Hayato-cho, Aira-gun, Kagoshima Pref.

Claims (1)

[Claims] A scanning electrode member in which a plurality of scanning electrodes are arranged on a transparent substrate and an alignment film are sequentially formed; and a signal electrode pattern in which a large number of signal electrodes are arranged on a transparent substrate. An alignment film and a signal electrode member sequentially formed are arranged so that the scanning electrode pattern and the signal electrode pattern intersect with each other and through a chiral nematic liquid crystal, and each intersection is defined as a pixel region. The chiral nematic liquid crystal has a twisted structure in an initial state, and a voltage that causes a Freedericks transition is applied to the initial state.
A liquid crystal display device having two metastable states, wherein a spacer is provided only in a non-pixel region between a scanning electrode member and a signal electrode member.