JPH0293432A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To obtain the device which has high luminance and generates less crosstalks by disposing electrodes in such positions where the electrodes do not face the varistor disposed on the other substrate. CONSTITUTION:The picture element electrodes 12, signal lines 13, and the varistor films 14 constituting mainly of varistor powder are formed on the substrate 11a. On the other hand, the scanning electrodes 15 are disposed on the substrate 11b so as to face the electrodes 12. The parts of the electrodes 15 which face the films 14 are notched to prevent the opposition of the electrodes 15 and the films 14. The flow of current from the signal lines 13 via the films 14 to the electrodes 15 is obviated even under a high pressure and the normal matrix circuit of the liquid crystal and the varistor is formed. The crosstalks are, therefore, hardly generated even in case of using a polymer dispersion type liquid crystal of a high operating voltage and the display with the high luminance and high contrast is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display device with almost no crosstalk and high brightness.

[Prior art and its problems] Liquid crystal display devices are thin, can be driven at low voltage, consume little power, and can be directly driven by ICs, so they have the advantage of being easy to make devices smaller and thinner. have

In particular, TN type liquid crystals are excellent in terms of low voltage and low power consumption, and have been widely used in wristwatches, calculators, and the like.

In recent years, with the spread of information processing devices such as word processors and personal computers, there has been a demand for flexible, thin, and compact devices, and liquid crystal display devices have begun to be adopted as display devices to replace CRTs. In this case, in order to display kanji characters, the number of pixels is much larger than that used in wristwatches, calculators, etc., and the driving method for the liquid crystal display device is usually a simple matrix drive circuit in which electrodes cross in an X-Y pattern. However, in this case, since the pixel electrodes of each pixel are not independent, a certain voltage is also applied to adjacent pixels, and the adjacent pixels are not completely hidden, resulting in so-called crosstalk. may occur.

In order to improve this crosstalk, there is a method of providing a nonlinear element such as a diode or a thin film transistor for each pixel.

However, it is difficult to arrange diodes, thin film transistors, etc. for each pixel, which number from thousands to hundreds of thousands of pixels, without defects or with almost the same characteristics.There is little variation in characteristics and it is possible to form over a large area. It has been desired to create a nonlinear element with

On the other hand, the development of liquid crystals used in large-area display devices has progressed, and in recent years, N CA P (NetIllaticCu
A new liquid crystal technology called rvilinear aligned phase (nematic curve aligned phase) liquid crystal has been developed, and the thickness of the liquid crystal layer can be easily controlled, allowing for large areas, fast response time, and no need for polarizing plates. Since it has vP characteristics such as a wide viewing angle, it is expected to be suitably used in display devices with a relatively large area.

However, while the operating voltage of the TN-type liquid crystal is about 5V, the operating voltage of the above-mentioned NCAP liquid crystal is as high as several tens to hundreds of volts. It was wanted.

The applicant filed a patent application for a liquid crystal display device using a film mainly made of varistor powder as a nonlinear element in Japanese patent application No. 63-1388.
I proposed it as No. 70. According to the liquid crystal display device proposed above, even when NCAP liquid crystal having a high operating voltage is used as the liquid crystal, display with almost no crosstalk can be performed.

The present applicant has investigated the above-mentioned proposed device and has discovered the following facts. That is, the conventional electrode pattern as shown in FIGS. 5(B) and 5(C) (in the figure, the pixel electrode, signal line, and varistor film on the first substrate are shown as solid lines, and the electrodes on the second substrate are shown as dotted lines). Indicated by

) to form the thin liquid crystal display device shown in FIG. 5A, the surface portion of the varistor film 52 printed on the first substrate 51a and the scanning line electrode 5 on the second substrate 51b are
3 are close to each other, the signal line 54 provided on the first substrate 51a is connected to the second substrate 5 through the varistor film 52.
In order to facilitate the flow of current to the scanning line electrode 53 disposed on the first substrate 51a, or to facilitate the flow of current from the pixel electrode 55 to the scanning line electrode 53 via the varistor film 52, the first substrate 51a A problem arises in that the voltage between the pixel electrode 55 and the electrode 53 formed above decreases, making it impossible to obtain display with desired brightness. This phenomenon occurs in the liquid crystal layer 5.
6 becomes more noticeable as it becomes thinner.

It is an object of the present invention to solve these problems and provide a liquid crystal display device with high brightness and less crosstalk.

[Means for Solving the Problems] The liquid crystal display device of the present invention includes, on a substrate, a pixel electrode, a signal line disposed at a distance from the pixel electrode and sending a signal to the pixel electrode, and a signal line between the pixel electrode and the pixel electrode. A liquid crystal display device in which liquid crystal is filled between a first substrate having a varistor connected to a signal line, and a second substrate having an electrode facing the pixel electrode. The liquid crystal display device is characterized in that the electrodes on the second substrate are arranged so as not to face the varistors arranged on the first substrate.

Next, the present invention will be explained based on drawings showing one embodiment of the present invention.

FIG. 1 is a transparent perspective view of an embodiment of the present invention.

On the first substrate 11a, a pixel electrode 12 and a signal line 1 are provided.
The 0 pixel electrode 12 and the signal line 13 on which the 0 pixel electrode 3 is arranged are spaced apart from each other, and the 0 pixel electrode 12 and the signal line 13 are electrically connected to each other by a varistor 14. ~400 μm.

Varistors are generally used as surge absorption elements, and as shown in Figure 2 (A), below a certain voltage (hereinafter referred to as the varistor dark value voltage (Va)), the resistance is large and the current is substantially reduced. Although almost no current flows, when the voltage Va is exceeded, the resistance suddenly decreases and the current flows.By controlling the distance between the electrodes, particle size, etc., the varistor voltage, current capacity, etc. can be adjusted. It is an element that can be controlled arbitrarily and can cover a wide range of areas such as electronic circuit protection and lightning protection.

The action of the varistor will be explained in more detail based on FIG.

As shown in FIG. 2(B), a liquid crystal component 21 and signal lines X1, X2, . X3, intersecting signal lines Y1, Y2, Y3, and liquid crystal component 2
A varistor film 22 is formed to connect one pixel electrode to the signal lines X1, X2, and X3. And the signal yAXi
, X2, X3 have a voltage of O1V/2.0 (V/2<Va
<V) is applied to the signal lines Yl, Y2, Y3 to 0, -■/
When a voltage of 2.0 is applied, since V/2<V a holds true except for the liquid crystal region where the signal lines x2 and Y2 intersect, the varistor film 22 blocks the inflow of charges, and the voltage is almost not applied.

On the other hand, in the liquid crystal region where the signal lines X2 and Y2 intersect, Va
<V, so a voltage of V-Va is applied to the liquid crystal component 21. In this way, crosstalk can be prevented. Note that the voltage applied to the liquid crystal region where the signal lines X2 and Y2 intersect is such that even if the voltage applied to the signal lines X2 and Y2 changes due to sequential scanning in the multiplex drive, the charge is retained by the varistor film 22. Therefore, a voltage application state lower than the varistor voltage is maintained, and the liquid crystal can maintain its display state.

In the present invention, if the varistor 14 is a varistor film mainly made of varistor powder, the varistor can be manufactured at any position and size on the substrate. Furthermore, if the varistor film is formed individually between the pixel electrode and the signal line by a printing method using a paste containing varistor powder as the main component, the manufacturing process will be faster than when using thin film formation technology. The method is simple and inexpensive, and it is possible to manufacture elements over a wide area at once, and it is possible to form stable varistor elements with little variation in characteristics.

When the varistor 14 is made of a varistor film mainly made of varistor powder, by using substantially spherical varistor powder with uniform particle size, the varistor dark value voltage between each pixel electrode and the signal line becomes almost constant, resulting in a clear display. It will be done.

The particle size of barista powder is generally 1 to 30 μm, preferably 2 to 20 μm. If excessively large particles are used, the thickness of the liquid crystal layer becomes thick as a result, and the driving voltage becomes too high (too much), and the effect of making the particles too small is not observed.

An electrode 15 is arranged on the second substrate 11b so as to face the pixel electrode 12. The individual electrodes 15 are electrically connected by bridges 16, and the pixel electrodes 12
Together, they form a so-called matrix drive circuit.

The TLL 125 has a shape in which a portion facing the varistor 14 is cut out, so that the electrode] 5 and the varistor 14 do not face each other. FIG. 6 shows another type M of the electrode pattern that prevents the electrode 15 and the varistor film from facing each other (in the figure, the pixel electrode 61, signal line 62, and varistor film 63 on the first substrate are shown as solid lines, and the second The electrode 64 on the substrate is indicated by a dotted line. In FIG. 6, the electrode 64 is not provided with a notch, but a tongue piece 65 is provided to protrude from the portion of the pixel electrode 61 that contacts the varistor 63.

The distance between the substrate 11a and llb is generally 5 to 50μ.
m, and the space between them is filled with liquid crystal (not shown).

The liquid crystal in the present invention is preferably a polymer-dispersed liquid crystal whose driving voltage is higher than that of a TN liquid crystal or the like. This provides a liquid crystal display device consisting of a large number of pixels that takes advantage of the excellent features of polymer dispersed liquid crystal in combination with a varistor that can control the varistor voltage up to a high voltage.

Polymer dispersed liquid crystal (NCAP liquid crystal) is used, for example, in "Principles and Applications of New Liquid Crystal Displays" Electronic Materials 198
7.12. Pages 67-71 and patent application publication 1982-
It is described in No. 501631.

3(A), 3(B), and 3(C) are schematic configuration diagrams for explaining one configuration example of NCAP liquid crystal, FIG. 3(A) is a configuration diagram of the liquid crystal component, and FIG. B) is a configuration diagram of the liquid crystal layer,
FIG. 3(C) shows a configuration diagram of a liquid crystal capsule.

As shown in FIG. 3(A), the NCAP liquid crystal element
The AP liquid crystal layer 31 is sandwiched between plastic films 32, and the plastic film 32 is coated with a transparent conductive layer such as ITO as an electrode 33. FIG. 3(B) shows the configuration of a part 34 of the NCAP liquid crystal 131, and FIG. 3(C) shows the structure of the NCAP liquid crystal 131.
It shows the structure of a liquid crystal capsule 35 of a liquid crystal layer 31.

As shown in FIGS. 3(B) and (C), the NCAP liquid crystal layer 3
1 is a small sphere of liquid crystal 3 in a polymer matrix 36
It is a collection of dispersed numbers 7.

Figures 4 (A) and (B) show N dyes using black dichroic dye.
4A and 4B are schematic explanatory diagrams showing the operation of the CAP liquid crystal, with FIG. 4(A) showing a no-voltage state and FIG. 4(B) showing a voltage applied state.

As shown in FIG. 4(A), in a no-voltage state, liquid crystal molecules 4
1b tries to line up along the outer wall of the capsule. In this case, due to the birefringence of the liquid crystal molecules 41b, the incident light is scattered on the surface and inside of the liquid crystal capsule, and is absorbed by the dichroic dye 41a. As a result, the film appears dark black.

As shown in FIG. 4(B), when a voltage is applied, the liquid crystal molecules 41b rotate their axes to be aligned in the direction of the electric field. If the refractive index of the axis of the liquid crystal molecule 41b is equal to the refractive index of the polymer, light travels straight without being scattered and becomes transparent. In this manner, by adjusting the voltage, it is possible to continuously change the state from a completely scattered and absorbed state to a fully transparent state for display.

In the description, the electrodes on the second substrate are used as scanning lines, but the present invention is not necessarily limited to this, and the signal lines on the first substrate may be scanned during driving.

[Effect]

A feature of the present invention is that the varistor 14 on the first substrate 11a and the scanning line electrode 15 on the second substrate 11b are arranged so as not to face each other.

Therefore, even under high voltage, no current flows from the signal line 13 to the scanning line electrode 15 via the varistor 14, and a normal matrix circuit between the liquid crystal and the varistor 14 is formed, allowing high brightness and high contrast display. Become.

Furthermore, since the liquid crystal display device of the present invention does not require any insulating film to be formed on the electrode surface, it is very advantageous in terms of process, and is also effective when driven at a low voltage.

Production Example First, ZnO powder was molded at a pressure of 50 to 1500 kg/cJ and fired at 700 to 1300°C in an electric furnace.

The obtained pellets are crushed in a mortar and classified to have a particle size of 5 to 8μ.
A powder of m was obtained. In order to round the corners of the powder, it was fired again at 800 to 1300°C in an electric furnace. The obtained spherical Zn
Bigol, Cot's, Mn0z to 100g of O powder
, 5btos, etc. were added thereto, stirred well, and then fired at 700 to 1300°C to produce a varistor powder.

Add 10g of this varistor powder, glass powder and binder (
A paste was prepared by mixing.

A predetermined pixel electrode 12 made of ITO or the like and a signal line 1 are prepared in advance.
3 (The gap between the pixel electrode 12 and the signal line 13 is 100μ
The above paste was screen printed on a glass substrate 11a patterned with m), and heat treated at 300 to 500°C to form a varistor film 14 on the glass substrate 11a.

Next, add 10.0 g of polyvinyl alcohol to 90 g of distilled water.
30g of liquid crystal and 0.3~3g of black dye
A solution of g was mixed to prepare an emulsion. The emulsion was applied to the glass substrate 11a to a thickness of 50 pm using a doctor blade and dried.

On the other hand, the above emulsion was applied to a substrate 11b (glass, PET film, etc.) on which electrodes 15 such as ITO were previously patterned to a thickness of 50 μm using a doctor blade, and dried. .

Both substrates 11a and llb were bonded together at predetermined positions, and the periphery of the substrates was sealed with an adhesive.

In the liquid crystal display device manufactured in this way, the signal line 13
A drive circuit is connected between the and scanning line electrodes 15, and ±150V
When multiplex driving (1/400 duty) was performed, a clear display with a contrast of 30:1 or more was obtained.

In the above manufacturing example, the varistor is formed as a varistor film, but it is not limited to a film-like form.

For example, there has been a conventional example in which a nonlinear element was fabricated using a polycrystalline ZnO substrate and used as a varistor, and this can also be used in the present invention. However, in this case, there is a problem that transmission type display is not possible (Nikkei Electronics, 1987, 1, 128 (No, 412), 1
Section 45), if a varistor film made mainly of varistor powder is formed on the substrate at a different position from the pixel electrodes, as in the above-mentioned embodiments, a transmission type display is also possible.

In the manufacturing example described above, as a method for producing a varistor film, varistor powder, glass powder, and a binder were added onto a glass substrate and printed and fired as a paste, but there are other methods for forming a varistor film using a printing method. There are also methods of adding varistor powder to an evaporative adhesive and printing and drying it as a paste to form a varistor film, and adding varistor powder to a curable adhesive and printing and curing it as a paste to form a varistor film. It is possible.

Note that although a glass substrate or a PET substrate is often used as the substrate, it is not particularly limited to these, and other materials may be used.

As the evaporative adhesive, cellulose-based, acrylic-based, vinyl acetate-based, polyvinyl alcohol-based adhesives, and the like can be used. In addition, it is also possible to add an appropriate amount of a solvent and a plasticizer.

As a curable adhesive, epoxy type (for example, DP p
ure 60. (manufactured by 3M Company), room temperature curing type such as silicone type (for example, TSE 352, manufactured by Toshiba Silicone Company), epoxy type (for example, JA-7437, manufactured by 3M Company),
Silicone type (e.g., epoxy TSJ 3155, manufactured by Toshiba Silicone Co., Ltd.) and other heat-curing types, monomers that initiate polymerization with photoinitiators (e.g., 2-ethylhexyl acrylate, dicyclopentenyl acrylate), prepolymers (e.g., Photo-curable adhesives such as polyester acrylate, epoxy acrylate), mixtures thereof, and compositions containing monomers and/or prepolymers can be used, as well as radiation-curable adhesives, electron beam-curable adhesives, etc. Available for use.

[Brief explanation of drawings]

FIG. 1 is a transparent perspective view of one embodiment of the present invention. FIGS. 2A and 2B are characteristic diagrams for explaining the operation of a varistor and a matrix wiring diagram of a liquid crystal display device. FIGS. 3A, 3B, and 3C are schematic configuration diagrams for explaining the configuration of the NCAP liquid crystal. FIGS. 4(A) and 4(B) are schematic explanatory diagrams showing the operation of the NCAP liquid crystal. FIG. 5(A) is a schematic partial sectional view of a conventional liquid crystal display device, and FIGS. 5(B) and 5(C) are diagrams showing electrode patterns constituting the conventional liquid crystal display device. FIG. 6 is a diagram showing one embodiment of an electrode pattern constituting the liquid crystal display device of the present invention. 11a, llb, 51a, 51b: substrate, 12°55.
61: Pixel electrode, 13, 54, 62: Signal line, 14, 5
2.63: Varistor, 15, 33: Electrode, 16: Bridge, 21: Liquid crystal component, 22° 52: Varistor film, 31
: NCAP liquid crystal layer, 32niblast film,
53.64: Scanning line electrode patent applicant Ube Industries, Ltd. Figure (A) (B) Figure (A) (B Figure (B) Figure (C)

Claims (1)

[Scope of Claims] (1) A pixel electrode, a signal line disposed at a distance from the pixel electrode and sending a signal to the pixel electrode, and a varistor connecting the pixel electrode and the signal line are provided on a substrate. 1st to have
In a liquid crystal display device in which liquid crystal is filled between the substrate and a second substrate on which an electrode is provided to face the pixel electrode, the electrode on the second substrate is connected to the first substrate. A liquid crystal display device characterized in that it is arranged so as not to face a varistor arranged on a substrate. (2) The liquid crystal display device according to claim 1, wherein the liquid crystal is a polymer-dispersed liquid crystal. (3) The liquid crystal display device according to claim 1, wherein the varistor is a varistor film mainly made of varistor powder. (4) The liquid crystal display device according to claim 3, wherein the varistor film is produced by a printing method using a paste containing varistor powder as a main component.