JPH01277819A - Liquid crystal display panel and production thereof - Google Patents

Abstract

PURPOSE:To less steepen the change in transmittance with an impressed voltage by providing an oriented film contg. a photoreactive material on at least one of the transparent electrodes of 1st and 2nd insulating substrates. CONSTITUTION:The oriented film 3 contg. the photoreactive material is provided on the transparent electrode 2 of the substrate 1 to form picture elements and the orientation control power is partially changed by the partial light irradiation applied within one picture element. The threshold voltage and voltage- transmittance characteristics as the electro-optic characteristics of the ferroelctric liquid crystal panel vary sensitively with the kind of the oriented film and the surface condition of the oriented film such as rubbing method. The photoreactive material is, therefore, changed in the stereoscopic structure if the oriented film 3 contg. the photoreactive material is subjected to the partial light irradiation after the uniform control power of the oriented film is once formed by subjecting the film to a rubbing treatment. The orientation control power, therefore, changes. The electrooptic characteristics over the entire part are thereby made into the synthesized characteristics of both thereof and, therefore, the gentle rising characteristic is obtd.

Description

[Detailed Description of the Invention] [Summary] Regarding the configuration of a liquid crystal display panel and its manufacturing method for realizing a good multi-gradation display, the present invention relates to a structure of a liquid crystal display panel and a manufacturing method thereof, which smooths the change in transmittance of a ferroelectric liquid crystal panel with respect to applied voltage. For the purpose of this, a ferroelectric liquid crystal is sandwiched between first and second insulating substrates each having a transparent electrode formed on one principal surface facing each other, and the substrates disposed facing each other.
In a configuration in which pixels are arranged between opposing electrodes, an alignment material containing a photoreactive substance is formed on at least one transparent electrode of the first and second insulating substrates, and
The structure includes an alignment film that is partially irradiated with light and has two regions with different alignment regulating forces within one pixel.

[Industrial application field]

The present invention relates to a structure of a panel and a method of manufacturing the same for realizing a good multi-gradation display.

[Conventional technology]

As shown in FIG. 3, a conventional liquid crystal display panel using ferroelectric liquid crystal has a transparent electrode 2 formed on one principal surface of a pair of glass substrates 1 facing each other, and a transparent electrode 2 on the opposite main surface. Each of them has a structure in which an alignment film 3 is applied and a ferroelectric liquid crystal 4 is sandwiched between the alignment films. At least one of the upper and lower alignment films 3 is subjected to a rubbing treatment in a predetermined direction.

[Problem to be solved by the invention]

Even if a conventional ferroelectric liquid crystal panel with the structure described above attempts to display gradations through voltage control, it is difficult to obtain a sufficient number of gradations because the transmittance changes sharply with respect to the applied voltage. Ta.

Therefore, an object of the present invention is to smooth the change in transmittance of a ferroelectric liquid crystal panel with respect to applied voltage.

[Means to solve the problem]

The present invention consists of an alignment material containing a photoreactive substance, -
It is provided with an alignment film whose alignment regulating force is partially changed by applying partial light irradiation within the pixel.

In addition, an alignment film with partially different alignment regulating forces within a pixel,
Form as follows. That is, an alignment film containing a photoreactive substance is formed, and a desired portion of this alignment film for each pixel is irradiated with light in advance to change the three-dimensional structure of the photoreactive substance in the irradiated area in advance. (Next, after applying a rubbing treatment to the entire alignment film, the entire alignment film is irradiated with light again to change the three-dimensional structure of the photoreactive substance in the part that was not irradiated during the first light irradiation. Change the orientation regulating force of the part.

[For production]

The electro-optical characteristics of a ferroelectric liquid crystal panel, that is, the dark value voltage and voltage-transmittance characteristics, vary sensitively depending on the surface condition of the alignment film, such as the type of alignment film and the rubbing method.

The present invention takes advantage of this, and involves applying a rubbing treatment to an alignment film containing a photoreactive substance to uniformly form the alignment regulating force of the alignment film, and then partially irradiating the alignment film with light. I do. Since the three-dimensional structure of the photoreactive substance in the portion exposed to this light changes, the alignment regulating force previously formed by the rubbing process changes.

Therefore, by providing regions with different alignment regulating forces within one pixel, two regions with different electro-optical characteristics are formed within the pixel, and the electro-optical characteristics of the entire pixel are a combination of these two regions. Therefore, a gradual rise characteristic can be obtained.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

In this example, the size of each pixel is 300 μm x 300 μm.
m, and the alignment film 3'' on the upper glass substrate 1' is a normal P
The alignment film 3 on the lower glass substrate 1 was formed by applying VA (polyvinyl alcohol) containing 10% wt of a photoreactive substance azobenzene (C6H5N11NC6H5) to PVA by a spin cord method.

Portion A of the alignment film 3 thus formed is irradiated with ultraviolet light prior to the rubbing treatment. When the azobenzene used in this example is irradiated with light, it undergoes an isomer change reaction from the trans form to the cis form. Therefore, by irradiation with the ultraviolet light, the irradiated part A changes to the cis type, and no structural change occurs even after this irradiation, but the unirradiated part B remains trans type 7, and after irradiation with light. This causes an isomer change reaction.

Next, the alignment film 3 is subjected to a rubbing treatment. By this rubbing process, even if the alignment film 3 contains both trans type and cis type, the alignment regulating force within each pixel becomes uniform.

After this, the entire surface of the alignment film 3 is irradiated with ultraviolet light again.

By this irradiation, the azobenzene in the unexposed area B undergoes an isomer change reaction and changes to the cis form. When such a structural change occurs, the alignment regulating force previously formed by the rubbing process is reduced.

On the other hand, the irradiated area A was irradiated with light prior to the wrapping process.
Even if irradiated with light again, the isomer change reaction no longer occurs, so there is no change in the orientation regulating force.

Therefore, in this embodiment, as described above, two regions A and B having different alignment regulating forces are formed within the -pixel by the second light irradiation after the rubbing process.

There are two regions A with different orientation regulating forces.

B is shown in Figure 2 as curve 1. As shown by II, the electro-optical characteristic of a pixel having two regions with different dark value voltages is a curve 3 which is a combination of the above two characteristics, and exhibits a gentle rising characteristic.

When the alignment regulating force of the alignment film is controlled in a ferroelectric liquid crystal panel, the dark value may be low as described above, or it may be high. This depends on the type of alignment control film and the rubbing direction. Therefore, the transmittance characteristics of the conventional ferroelectric liquid crystal panel are I or ■ in the figure.

The transmittance characteristics with respect to the input pulse height of this example shown by the curve ■ in FIG. This was obtained by applying a so-called AC stabilization method in which written information is retained by applying an AC voltage with a frequency of 2 KHz.

As seen in the figure, the rise characteristic of the liquid crystal display panel obtained in this example is more gradual than that of the conventional panel, so that multi-gradation display is possible by controlling the input voltage.

In this example, the reason why portion A of the alignment film 3 containing a photoreactive substance was irradiated with light prior to the rubbing treatment was to prevent the alignment regulating force from changing over time.

That is, if two regions having different orientation regulating forces are simply formed within one pixel, it is possible to do so by first performing a rubbing process and then irradiating the above-mentioned B portion with light. However, as it is, part A remains in the trans form because it is not irradiated with light, and the isomer change reaction is not completed. Therefore, after the panel is completed, it is irradiated with light during actual use, and the isomer change reaction gradually progresses, resulting in changes in the alignment regulating force over time, and electro-optical characteristics fluctuate.

Therefore, in this example, after the above part A was irradiated with light in advance to complete the isomer change reaction, a rubbing treatment was performed,
Thereafter, by irradiating the 8 parts with light, the alignment regulating forces of parts A and B were made different, the isomer change reaction was completed over the entire surface of the alignment film, and subsequent changes over time were suppressed.

In the above embodiment, an example was described in which PVA was used as the alignment material and azobenzene was used as the photoreactive substance, but the present invention is not limited thereto. That is,
The alignment material may be any commonly used material such as polyimide, and the photoreactive material may be one that causes a ring-opening-ring-closing reaction, such as spiropyran [C2°H+*04Nz], or a diazonium salt (( NH4,
) Z Cr.

Various materials can be used, such as those that cause a crosslinking reaction such as [07], and these can be appropriately selected in consideration of the ferroelectric liquid crystal to be used, the rubbing treatment, etc.

Note that, as described above, the photoreactive substance in the present invention is trans-cis-form when irradiated with light.

Refers to a substance that produces steric structural isomers due to ring-opening-ring-closing reactions, etc.

〔Effect of the invention〕

As described above, according to the present invention, a slow voltage-transmittance characteristic can be realized, and multi-gradation display can be performed by voltage control.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of one embodiment of the present invention, FIG. 2 is a voltage-transmittance characteristic diagram of the above-mentioned embodiment, and FIG. 3 is an explanatory diagram of a conventional ferroelectric liquid crystal panel. In the figure, 1,1゛ is a glass substrate (insulating substrate), 2
3 indicates a transparent electrode, 3 and 3' indicate alignment films, and 4 indicates a ferroelectric liquid crystal. 1: Sai T-ka "uni old man and 1': O 2 false 77' Raz 耘 3': tl1 phrase beginning 4: The invention of the pillar layer bud for begging - the husband or the number of examples in the 1st figure or l (Ru Matanami)'f @ 9M-Arrow Q IFj==l tlwoki-M
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Claims (2)

[Claims] (1) First and second insulating substrates (1, 1') each having a transparent electrode (2) formed on one opposing principal surface, and a ferroelectric liquid crystal (4 ),
In the configuration in which pixels are arranged between opposing electrodes, an alignment material containing a photoreactive substance is provided on at least one transparent electrode (2) of the first and second insulating substrates (1, 1'). An alignment film (3
) A liquid crystal display panel comprising: (2) Transparent electrode (2) that becomes a pixel on the surface of the insulating substrate (1)
), a film made of an alignment material containing a predetermined photoreactive substance is formed, and the film made of the alignment material is partially irradiated with light, so that the photoreactivity is partially applied to each pixel. An isomer reaction is caused in the substance, and then the film made of the alignment material is subjected to a rubbing treatment, and then the entire surface of the film made of the alignment material is irradiated with light to partially regulate the alignment within each pixel. 2 different powers
A method for manufacturing a liquid crystal display panel, comprising forming an alignment film (3) having two areas.