JPH0743480B2 - Liquid crystal display - Google Patents

Description

The present invention relates to a liquid crystal display device, and more particularly to a pixel electrode, a signal line for sending a signal to the pixel electrode, the pixel electrode and the signal line on a substrate. A liquid crystal display device having a non-linear element for connecting to and a polymer-dispersed liquid crystal between the substrate and a substrate provided with an electrode facing the pixel electrode.

[Prior Art] A liquid crystal display element has advantages that it is thin, can be driven at a low voltage, has low power consumption, and can be directly driven by an IC, so that the device can be easily downsized and thinned. In particular, TN type liquid crystal is excellent in terms of low current collection and low power consumption.
Widely used in calculators, etc.

In recent years, along with the spread of information processing devices such as word processors and personal computers, the portability and thinning of the devices,
With the demand for miniaturization, liquid crystal display elements have begun to be adopted as display elements in CRTs. In such a case, the number of pixels is very large in comparison with the use for a wristwatch, a calculator or the like to enable the display of Chinese characters, and the liquid crystal display device is driven by a matrix display drive in which electrodes are crossed in a XY shape. However, in this case, since a pixel electrode is not independent in each pixel, a constant voltage is applied to the adjacent pixel, and the adjacent pixel is not completely in the non-display state, so-called crosstalk. May occur.

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

[Problems to be Solved by the Invention] However, it is difficult to dispose a diode, a thin film transistor, or the like for each pixel ranging from several thousand to several hundred thousand pixels without any defect or with substantially the same characteristics, and variations in characteristics are caused. It has been desired to fabricate a non-linear element which has a small amount and can be formed in a large area.

On the other hand, the development of liquid crystals for use in large-area display devices has progressed, and in recent years, NCAP (Nematic curvilinear Aligned Phas
A new liquid crystal technology called e: nematic curvilinear aligned phase liquid crystal has been developed, and features such as large area, fast response time, no need for polarizing plate, and wide viewing angle are compared. It is expected to be suitably used for a display device having a large target area.

However, a polymer-dispersed liquid crystal solution (or emulsion) is applied over the entire surface of a substrate having a varistor element,
When the polymer-dispersed liquid crystal layer is formed by drying, there is a problem that the upper part of the varistor element rises, the distance between the substrates increases when the upper and lower substrates are bonded, and the driving voltage becomes higher than necessary. Further, there is a problem that the varistor characteristics are deteriorated due to the contact of the solvent and additives in the polymer-dispersed liquid crystal solution (or emulsion) with the varistor element.

An object of the present invention is to provide a polymer-dispersed liquid crystal display device in which a driving voltage is not higher than necessary and a varistor element maintains a good varistor characteristic for a long period of time and can perform a good display. is there.

[Means for Solving the Problems] A liquid crystal display device of the present invention includes a pixel electrode, a signal line for transmitting a signal to the pixel electrode, and a varistor element for connecting the pixel electrode and the signal line on a substrate. And a polymer-dispersed liquid crystal except for at least the varistor element so as not to come into contact with the varistor element between the substrate and the substrate on which the scanning electrode is provided so as to face the pixel electrode. It is characterized by forming and sandwiching layers.

[Operation] The operation of the present invention will be described below with reference to the drawings.

FIG. 4 is a schematic partial sectional view for explaining the operation of the liquid crystal display device of the present invention.

In the figure, 1 is a pixel electrode 9 and a varistor element 4.
(Here, the signal line is not shown) is provided on the substrate, and the polymer dispersed liquid crystal layer 3 is provided between the substrate and the substrate 2 provided with the scanning electrode 10.

According to the present invention, as shown in FIG. 4, a polymer dispersed liquid crystal layer 3 is formed on a varistor element by forming a gap d so as not to contact the varistor element 4 and forming a polymer dispersed liquid crystal layer 3 between the substrates. Various problems caused by the formation of the varnish, for example, the distance between the substrates increases, the driving voltage becomes higher than necessary, or the solvent or additive in the polymer-dispersed liquid crystal solution (or emulsion) contacts the varistor element. By doing so, problems such as deterioration of varistor characteristics are solved.

EXAMPLES Examples of the present invention will be described in detail below with reference to the drawings.

First, prior to the description of the liquid crystal display device of the present invention, the polymer dispersion type liquid crystal used in the present invention will be described.

NCAP liquid crystal is known as a polymer dispersed liquid crystal. The structure and operation of the polymer-dispersed liquid crystal will be explained below by taking this NCAP liquid crystal as an example (the following explanation is "Principle and application of new liquid crystal display" electronic material
1987, 12, P.67 to P.71, based on the patent application publication No. 58-501631).

5 (A), (B), and (C) are schematic configuration diagrams for explaining one configuration example of the NCAP liquid crystal, and FIG. 5 (A) is a configuration diagram of the liquid crystal configuration unit, and FIG. B) is a configuration diagram of the liquid crystal layer, the fifth
FIG. (C) shows a configuration diagram of the liquid crystal capsule.

As shown in FIG. 5 (A), the NCAP liquid crystal element has a structure in which an NCAP liquid crystal layer 13 is sandwiched between plastic films 11, and the plastic film 11 is coated with a transparent conductive layer such as ITO as an electrode 12. ing. Fig. 5 (B)
Shows the structure of a part 14 of the NCAP liquid crystal layer 13, and FIG. 5C shows the structure of the liquid crystal capsule 15 of the NCAP liquid crystal layer 13. As shown in FIGS. 5 (B) and (C),
The NCAP liquid crystal layer 13 is a collection of small spheres 16 of liquid crystal dispersed in a polymer matrix 17.

The polymer-dispersed liquid crystal of the present invention is a liquid crystal material (not limited to a spherical shape) in the polymer matrix as described above.
Refers to a collection of dispersed objects.

Figures 6 (A) and (B) show NCAP using a black dichroic dye.
6A and 6B are schematic explanatory diagrams for showing the operation of the liquid crystal. FIG. 6A shows a non-voltage state and FIG. 6B shows a voltage application state.

As shown in FIG. 6 (A), liquid crystal molecules 16
b tries to line up along the outer wall of the capsule. in this case,
Due to the birefringence of the liquid crystal molecules 16b, incident light is scattered on the surface and inside of the liquid crystal capsule and is absorbed by the dichroic dye 16a. As a result, the film appears dark black.

As shown in FIG. 6 (B), in the voltage applied state, the liquid crystal molecules 16b rotate their axes so as to align in the direction of the electric field. Liquid crystal molecule 1
If the refractive index of the axis of 6b and the refractive index of the polymer are the same, the light goes straight without being scattered and becomes transparent. In this way, by adjusting the voltage, it is possible to continuously change the state from the completely scattered and absorbed state to the sufficiently transparent state to perform display.

The liquid crystal display device of the present invention will be described below.

FIG. 1 is a schematic exploded view showing the configuration of the first embodiment of the liquid crystal display device of the present invention.

In the figure, reference numeral 1 is a substrate on which the varistor element 4 is formed. The polymer-dispersed liquid crystal layer 3 is formed on the other base body 2 which does not have the other varistor element. The polymer-dispersed liquid crystal layer 3 has a portion where the varistor element portion is a little wider than the area of the varistor element portion. It is open.

When the base 1 and the base 2 are attached to each other, the varistor element portion is placed in the opened portion 5 of the polymer-dispersed liquid crystal layer 3 so that a gap is formed between the varistor element and the polymer so as not to contact the varistor element. A dispersed liquid crystal layer can be formed and sandwiched. As a method for partially opening the polymer dispersed liquid crystal layer, there is a method described below.

(1) When a polymer-dispersed liquid crystal layer is formed on a substrate not provided with a varistor element and is bonded to a substrate having a varistor element, the polymer-dispersed liquid crystal layer is partially widened in advance to a portion where the varistor element portion hits in advance. How to scrape off.

(2) A polymer having a proper thickness that completely covers the varistor element is overlaid on a substrate without a varistor element to form a polymer dispersion type liquid crystal layer, and then the mask is peeled off to disperse the polymer on the mask. Method to partially remove the liquid crystal.

FIG. 2 (A) is a schematic exploded view showing the configuration of the second embodiment of the liquid crystal display device of the present invention, and FIG. 2 (B) is a schematic perspective view showing the bonded state of the bases. .

This embodiment is preferably used when the number of varistor elements is large, and the polymer dispersion type liquid crystal layer 3 is partially removed in stripes to form the grooves 6, in which the varistor is formed. The base body is arranged so that the element portion is inserted therein.
The scraped width is preferably narrower than the distance between adjacent pixel electrodes.

In this embodiment, the upper and lower substrates are adhered by placing an adhesive 7 between adjacent varistor elements.

When the polymer dispersion type liquid crystal layer is formed in a stripe shape,
It can be formed along the scanning line or the signal line (the signal line and the scanning line will be described in a specific example described later).

As a method of partially removing the polymer-dispersed liquid crystal layer in a stripe shape, a method of scraping off the polymer-dispersed liquid crystal layer in a stripe shape as in the above-described first embodiment, a polymer-dispersed liquid crystal layer using a stripe-shaped mask There is a method of partially removing the liquid crystal layer.

Hereinafter, examples and comparative examples in which a liquid crystal display device is specifically manufactured will be described.

(Examples) Examples of the present invention will be described below with reference to FIGS. 3 (A) to 3 (D).

FIG. 3 (A) is a schematic plan view of the substrate on the side provided with the varistor element, FIG. 3 (B) is a partially enlarged view thereof, and FIG. 3 (C) is the substrate on the side provided with the scanning electrodes. FIG. 3D is a schematic cross-sectional view showing a state in which a polymer dispersed liquid crystal layer is formed on a substrate.

First, an emulsion consisting of 20 g of an aqueous solution in which 2 g of polyvinyl alcohol is dissolved, 5 g of liquid crystal, and 0.2 g of a black dichroic dye is added to 100 μm on the electrode 10 side of the substrate 2 having the transparent scanning electrode 10 shown in FIG. 3 (C). A polymer dispersion type liquid crystal layer (thickness: 15 μm) was formed by applying and drying using a doctor blade of (1).

Next, as shown in FIG. 3 (D), the polymer-dispersed liquid crystal layer in a portion having no electrode in parallel with the scanning electrode 10 was striped.

On the other hand, as shown in FIGS. 3A and 3B, a varistor element (0.5 mm × 0.5 mm, thickness 13 μm, varistor 13 μm, varistor is formed between the signal line 8 made of a transparent electrode and the pixel electrode 9 by a printing method. Voltage 40
V ± 3V) was formed.

Liquid crystal is thinly applied to the entire surface of the substrate 1 on the varistor element side, and the surface having the polymer dispersion type liquid crystal layer 3, the pixel electrode 9 and the scanning electrode 10
They were attached so that and overlap well, and after pushing out excess liquid crystal, they were sealed with an adhesive.

When an AC voltage of 70V (Duty ratio of 1) is applied between the signal line of such a liquid crystal display device and the scanning line connected to the scanning electrode, the desired pixel portion is illuminated brightly (contrast ~ 30) without crosstalk. I was able to.

(Comparative Example) A panel having the same structure as that of the above-described example of the present invention was prepared, except that the polymer dispersed liquid crystal layer 3 was not scraped off.

Even when an AC voltage of 70V (Duyt ratio 1) was applied between the signal line and the scanning line, it did not light up very well (contrast ~
5). When an AC voltage of 100 V was applied, the lamp lit brightly, but crosstalk occurred.

[Effects of the Invention] As described in detail above, according to the liquid crystal display device of the present invention, by forming and sandwiching the polymer dispersed liquid crystal layer with a gap between the varistor element and the varistor element so as not to contact the varistor element, Since it is possible to suppress the variation in the distance between the substrates, it is possible to reduce the driving voltage, and it is possible to suppress the varistor characteristics due to the influence of the polymer-dispersed liquid crystal material and improve the reliability.

[Brief description of drawings]

FIG. 1 is a schematic exploded view showing the configuration of the first embodiment of the liquid crystal display device of the present invention. 2 (A) and 2 (B) are explanatory views showing the configuration of the second embodiment of the liquid crystal display device of the present invention. FIGS. 3A to 3D are explanatory views of constituent members of an embodiment of the liquid crystal display device of the present invention. FIG. 4 is a schematic partial sectional view for explaining the operation of the liquid crystal display device of the present invention. 5 (A), (B) and (C) are schematic configuration diagrams for explaining one configuration example of the NCAP liquid crystal. Figures 6 (A) and (B) show NCAP using a black dichroic dye.
FIG. 6 is a schematic explanatory diagram illustrating an operation of liquid crystal. 1, 2 …… Substrate 3 …… Polymer dispersed liquid crystal layer 4 …… Varistor element 5 …… Removed portion of polymer dispersed liquid crystal layer 6 …… Groove 7 …… Adhesive 8 …… Signal line 9 …… Pixel Electrode 10 ... Scanning electrode

Claims (2)

[Claims] 1. A substrate having a pixel electrode, a signal line for sending a signal to the pixel electrode, and a varistor element connecting the pixel electrode and the signal line, the substrate and the pixel electrode. A liquid crystal display characterized in that a polymer-dispersed liquid crystal layer is formed and sandwiched between a substrate provided with scanning electrodes so as to face each other except at least above the varistor element so as not to come into contact with the varistor element. apparatus. 2. The liquid crystal display device according to claim 1, wherein the varistor elements are arranged in a matrix, and at least the polymer dispersion type liquid crystal layer on the varistor elements and between the varistor elements in one arrangement direction is removed. A liquid crystal display device characterized in that an adhesive is applied to at least a part of a space between both substrates excluding the polymer-dispersed liquid crystal, and the two substrates are bonded and adhered.