JPS6311911A - Liquid-crystal element - Google Patents

Abstract

PURPOSE:To obtain a clear picture which is free from display unevenness over the whole area, by providing a low-resistance metallic film which is formed in such a way that the film is brought into contact with stripe-like transparent electrodes in parallel with the electrodes and covers the inter-electrode spaces. CONSTITUTION:Rays of light are intercepted at the inter-electrode spaces of stripe-like transparent electrodes 2 formed on a base plate 1, by forming a metallic film 3 in such a way that the film 3 is contacted with the electrodes 2 in parallel with the electrodes 2 and covers the inter-electrode space sections A. A cell is obtained by arranging two such base plates in such a way that the electrodes of each base plate can be faced to each other and interest each other at right angles and enclosing ferroelectric liquid crystal in the space between the base plates. Since the inter-electrode spaces are covered with the low-resistance metallic film 3, the area where the two stable states of the ferroelectrid liquid crystal exist can be eliminated and, moreover, the inter- electrode spaces can be intercepted from light. Therefore, unevenly oriented states of liquid crystal can be eliminated and a clear picture can be obtained.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a liquid crystal element used in a liquid crystal display element, a liquid crystal light shutter, etc. This relates to the electrode configuration.

[Summary of the Disclosure] This specification and drawings disclose that in a liquid crystal element using ferroelectric liquid crystal, display unevenness can be prevented over the entire surface by forming a low resistance metal wire in the space between the stripe electrodes to block light. The present invention discloses a technology that enables the acquisition of clear images and high-speed display.

[Prior Art] Conventionally, the structure of this type of liquid crystal display element is to process a transparent conductive film deposited on a glass substrate into stripes to form a transparent electrode, and then to form liquid crystal molecules on the glass substrate. Applying an alignment film to keep the molecular direction constant, and arranging the transparent electrodes to face each other and orthogonally cross each other,
It had a simple matrix structure with a ferroelectric liquid crystal sandwiched between two substrates.

[Problem to be Solved by the Invention 1] A ferroelectric liquid crystal is oriented from one of two stable states at the time of initial alignment. However, in the space between the electrodes to which no voltage is applied during driving, these two stable states always coexist, resulting in a drawback that the display characteristics of the device are significantly degraded.

The present invention was made in view of the drawbacks of the conventional examples, and provides a liquid crystal element that can provide a clear image without display unevenness over the entire surface and that can display at high speed even if the display area is increased. The purpose is to provide the following.

Means for Solving Problems c] and [Operation] Means for solving the above problems will be explained using FIG. 1 corresponding to the embodiment. This liquid crystal element is characterized in that a low-resistance metal film 3 is provided that is in parallel contact with the formed transparent electrodes 2 and covers the space between the transparent electrodes. By covering the space between the electrodes with a low-resistance metal film in this manner, it is possible to eliminate a region where two stable states of the ferroelectric liquid crystal coexist and to shield the space from light. As a result, alignment unevenness of the liquid crystal can be eliminated and clear images can be obtained. Furthermore, by using this low-resistance metal film as a light-shielding layer, high-speed display is possible even if the display area is increased.

[Example] FIG. 1 is a cross-sectional view of a substrate used in the liquid crystal element of the present invention. In Fig. 1, l is a substrate made of glass or plastic, and 2 is In203, 5n02, or IT.
After depositing a transparent conductive film such as O (Indium-Tin-Oxide) using a sputtering deposition method or an ion-blating deposition method, 1. A transparent electrode formed in a stripe shape using ordinary photolithography and etching techniques; 3. 4 is a metal film such as Al, Cr, or Au; 4 is an inorganic insulating film such as 5i02, TiO2, Ti2O5, or Zr0z; and 5 is an alignment film such as polyimide or polyvinyl alcohol.

As shown in FIG. 1, the present invention forms a metal film 3 so as to be in parallel contact with striped transparent electrodes 2 formed on a substrate 1 and to cover the space between the electrodes (A in the figure). The space between the electrodes is shielded from light. Two such boards,
The electrodes are facing each other.

Example 1 ITO film 100 was formed on a glass substrate by high frequency sputtering method.
0A was deposited and a positive resist (AZ-1370Hoe
(manufactured by CHST) using a spinner and prebaked. Mask width 80grs on this resist layer
The ITO film was exposed to light using a striped mask with a mask pitch of 100 p and m, followed by development, washing with water to form a stripe pattern, and then etching the ITO film with a mixture of ferric chloride, hydrochloric acid and water.

Next, Al was deposited on this substrate at 500A using an EB evaporator.
It was deposited with After that, a positive resist (A
Z-1370 (manufactured by Hoechst) was applied at 1 gtx using a spinner, and a mask width of 2
Using a striped mask of 0 JLm and a mask pitch of 100 JLll, the stripe pattern of the ITO film was exposed to light so as to overlap by about 5 cm. After developing and washing with water to form a stripe pattern, phosphoric acid, nitric acid, Aβ was etched with a mixture of acetic acid and water.

A polyvinyl alcohol layer of approximately 500 A was formed as a liquid crystal alignment film on the surface of each of the two substrates thus produced, and a rubbing treatment was performed. Next, the two substrates were placed facing each other, the gap was adjusted to approximately IJLI11 using bead spacers, and the ferroelectric liquid crystal (p-η-octyloxybenzoic acid-p'-(2-methylbutyloxy) phenyl ester) p-η-menyloxybenzoic acid-p'
-(2-methylbutyloxy)phenyl ester-based liquid crystal composition] was injected.

When polarizing plates were arranged in a crossed nicol configuration on both sides of the liquid crystal cell thus formed and the cell was driven, good display characteristics could be obtained.

Example 2 As shown in FIG. 2, after patterning the transparent electrode 2 of the ITO film, an insulating film 6 of 5i02 was deposited by photolithography in the space between the electrodes, and then AI!
A striped pattern was formed. Other than that, the configuration is the same as that of the first embodiment. With this configuration, it is possible to prevent short circuits with adjacent ITO films caused by poor formation of the stripe pattern of Ai), and it is possible to almost completely cover the space between the electrodes. In this example, as well as in Example 1, good display characteristics could be obtained.

In Example 1.2 above, the space between the transparent electrodes is AI! For example, when displaying a moving image according to normal TV standards on a display area of A4 size, the density of the scanning line should be 4/mta and the length of the scanning line should be approximately Assuming 300t+s, if the scanning line is made only of ITO, the sheet resistance of ITO is 20Ω/gate, and the resistance of the scanning line is about 27 KΩ.

On the other hand, according to the present invention, if Ai) is used as the metal and is partially overlapped with ITO with a width of 30 g, m and a thickness of 0.1 p, m, the wiring resistance of this metal will be approximately 4 Ω. becomes. As a result, the wiring resistance of the metal-covered ITO scanning line is approximately 3.5
becomes Ω.

Further, the capacitance of the ferroelectric liquid crystal attached to this scanning line is approximately 3.5 Xl0-9F.

That is, when a voltage signal is applied to the scanning line of this panel to invert the liquid crystal, the rise time of the voltage signal depends on the electrical resistance of the scanning line and the capacitance of the liquid crystal attached on the scanning line. If the scanning line is made of only ITO, this rise time will be approximately 94 JLS, but in the case of the ITO line with metal according to the present invention, it will be 14 JLS.

When displaying moving images according to normal TV standards, the scanning time allowed for one scanning line is 83.5S, and as mentioned above, if the scanning line is only ITO, the rise time is longer than the scanning time. Because the length of the video is long, it is impossible to display video according to TV standards. On the other hand, in the case of the metal-attached ITO wire according to the present invention, the scanning time is approximately five times the rise time, making it possible to display a moving image in accordance with the full V standard.

[Effects of the Invention] As described above, according to the present invention, it is possible to eliminate alignment unevenness in the electrode space portion over the entire surface of the cell, and it is possible to obtain a uniform and clear image over the entire surface. Furthermore, by using a low-resistance metal film as a light-shielding layer, high-speed display became possible even when the display area was increased.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a substrate showing one embodiment of the invention, and FIG. 2 is a sectional view of a substrate showing another embodiment of the invention. 12 substrates, 2: transparent electrode, 3: metal film, 4.5: insulating film, 5: alignment film.

Claims (2)

[Claims] (1) In a liquid crystal element having a cell structure in which bistable liquid crystal is sandwiched between two substrates on which striped transparent electrodes are formed, the liquid crystal element is in parallel contact with the striped transparent electrodes, and A liquid crystal element characterized in that a low resistance metal film is provided to cover the space between the striped transparent electrodes. (2) The liquid crystal element according to claim 1, wherein the liquid crystal having bistability is a ferroelectric liquid crystal.