JPH012018A - lcd display panel - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [4 Already Required] The present invention relates to a ferroelectric liquid crystal display panel, in which upper and lower alignment films are formed on a pair of transparent substrates having display electrodes facing each other with a ferroelectric liquid crystal in between. Among them, the thickness of one of the alignment films is made thicker than the other alignment film, and at least the other alignment film is subjected to an alignment treatment to reduce the difference in surface polarity between the upper and lower alignment films. This allows the liquid crystal molecules to be aligned uniformly over the entire surface of the panel, and also provides good bistability to ensure memory performance.

[Industrial application field]

The present invention relates to a liquid crystal display panel, and particularly to the structure of an alignment film in a ferroelectric liquid crystal display panel.

Liquid crystal display panels using ferroelectric liquid crystals have better image quality and response speed of 10% compared to conventional TN type liquid crystal display panels.
It has the major features of being more than 0 times faster and has a memory function, and is expected to be used as a large-capacity display.

In such a ferroelectric liquid crystal display panel, it is desired that the liquid crystal can be aligned uniformly over the entire surface of the panel and be bistable.

[Conventional technology]

As shown in Figure 3, the conventional ferroelectric liquid crystal display panel
A ferroelectric liquid crystal 14 and a second alignment film 15 are placed on a backside transparent substrate 11 made of glass on which a first display electrode 12 made of ITO (Indium Tin Oxide) or the like is formed, via a first alignment film 13. and a surface-side substrate 1 on which a second display electrode 17 made of ITO or the like is formed.
6 are laminated in order. 18 is a spacer that defines the filling thickness of the ferroelectric liquid crystal 14; 19, 20;
is a polarizing plate.

[Problem that the invention seeks to solve]

By the way, in the conventional ferroelectric liquid crystal display panel mentioned above,
The first and second alignment films 13 and 15 are made of the same alignment film material and have the same thickness, and by subjecting only one of the alignment films, for example, the second alignment film 15, to an alignment treatment such as rubbing, The liquid crystal molecules of the ferroelectric liquid crystal 14 are oriented without defects.

However, the inherent surface polarity of the second alignment film 15 is reduced due to the alignment treatment, and the strength of the surface polarity of the first and second alignment films 13.15 becomes unbalanced.

For this reason, the bistability of the ferroelectric liquid crystal 14 is lost and it tends to become monostable, which has the drawback of deteriorating memory performance.

In view of the above-mentioned conventional drawbacks, the present invention has been developed by adjusting the film thickness of an alignment film subjected to an alignment treatment and an alignment film not subjected to an alignment treatment, which are arranged so as to sandwich a ferroelectric liquid crystal between them, so that the surface polarity of each film is different from that of the other. It is an object of the present invention to provide a novel liquid crystal display panel in which liquid crystal molecules are uniformly aligned by controlling the intensity difference to be small, and which also achieves bistability.

[Means for solving problems]

In order to achieve the above object, the present invention increases the film thickness of one of the upper and lower alignment films formed on a transparent substrate having a pair of display electrodes facing each other with a ferroelectric liquid crystal in between. At the same time, the structure is such that only the other (thinner) alignment film is subjected to alignment treatment.

[Effect]

In the ferroelectric liquid crystal display panel of the present invention, the surface polarity of the alignment film that is not subjected to alignment treatment is large compared to the alignment film whose surface polarity is reduced by alignment treatment, and the surface polarity of the alignment film that is not subjected to alignment treatment is large. Utilizing the property that the surface polarity decreases when the thickness of the untreated alignment film is increased, the difference in surface polarity between the upper and lower alignment films formed on a pair of transparent substrates facing each other with a ferroelectric liquid crystal in between is reduced. By doing so, the alignment direction of the liquid crystal molecules can be equally easily oriented in both directions of the cone angle (angle along the outer periphery of the cone), and bistability can be achieved.

□ [Example] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a sectional view of a main part showing an embodiment of a ferroelectric liquid crystal display panel according to the present invention, and the same parts as in FIG. 2 are given the same reference numerals.

The difference between the embodiment shown in FIG. 1 and the example shown in FIG. 2 is that the ITO
The film thickness of the first alignment film 21 on the back side transparent substrate 11 made of glass on which the first transparent electrode 12 made of
Second alignment films 1 facing each other via ferroelectric liquid crystal 14
The second alignment film 15 has a structure in which the second alignment film 15 is made thicker by, for example, about 20% than the film thickness of No. 5, and only the surface of the second alignment film 15 is subjected to an alignment treatment.

The first and second alignment films 21.15 are both made of polyimide thin films, and the first alignment film 21 is thickly coated using a coat spinner at a rotation speed of 11,000 rpm, and the second alignment film 21 is also coated using a coat spinner. by 2000
After a thin coating was formed at a rotation speed of rpm+, the surface was rubbed eight times in one direction.

That is, by controlling the thickness of the first alignment film 21 to such a thickness that the surface polarity of the first alignment film 21 is no different from the surface polarity of the second alignment film 15 that has been subjected to the alignment treatment, the ferroelectric First and second alignment films 21 facing each other with a liquid crystal 14 interposed therebetween
．． The intensity of each of the 15 surface polarities is balanced.

Therefore, the liquid crystal molecules are uniformly aligned over the entire panel surface, and good bistability is obtained.

Incidentally, as a result of making a liquid crystal display panel of the present invention and a conventional liquid crystal display panel in parallel and comparing and observing the bistability by applying a single pulse of voltage of 50 V to these panels, it was found that the conventional liquid crystal display In a panel, the bistable area is approximately 40% of the total display surface, whereas in the liquid crystal display panel of the present invention, it was confirmed that more than 95% of the total display surface has bistability. did it.

〔Effect of the invention〕

As is clear from the above description, according to the ferroelectric liquid crystal display panel according to the present invention, liquid crystal molecules can be uniformly aligned over the entire surface of the panel without significantly changing the panel configuration, and the ferroelectric liquid crystal display panel can have good bistable properties. It has excellent advantages such as being able to obtain high performance and secure memory performance, and has remarkable effects when applied to display devices such as office automation equipment.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a main part showing an embodiment of a liquid crystal display panel according to the present invention, and FIG. 2 is a cross-sectional view of a main part showing an example of a conventional liquid crystal display panel. In FIG. 1, 11 and 16 are transparent substrates, 12 is a first display electrode, 14 is a ferroelectric liquid crystal, 15 is a second alignment film subjected to alignment treatment, and 17
18 indicates a second display electrode, 18 indicates a spacer, 19 and 20 indicate a polarizing plate, and 21 indicates a thick first alignment film.

Claims (1)

[Claims] Display electrodes (1) face each other with a ferroelectric liquid crystal (14) in between.
The thickness of one of the upper and lower alignment films (15, 21) formed on a pair of transparent substrates (11, 16) having transparent substrates (2, 17) is determined by the thickness of the other alignment film (21). 15), and at least the other alignment film (15) is subjected to an alignment treatment.