JPS62153827A - Liquid crystal element - Google Patents

Abstract

PURPOSE:To drive quickly a liquid crystal element while securing a high contrast by forming an oriented layer, which controls the direction of orientation of liquid crystal molecules, on the inside face of one of a pair of substrates. CONSTITUTION:One of orientation films on both substrates, for example, an oriented film 24 on a signal electrode substrate 11 is subjected to the rubbing treatment in a prescribed direction. An orientation film 25 on the other common electrode substrate 12 consists of the same materials as the orientation film 24 but is not subjected to the rubbing treatment. When a high frequency electric field is applied to a liquid crystal 15 between a signal electrode 18 and a common electrode 22, liquid crystal molecules are oriented in a prescribed direction by the orientation control force of the oriented film 24 on the signal electrode substrate 11. When a low frequency electric field is applied, liquid crystal molecules are arranged vertically surely because the horizontal orientation control force acting upon the liquid crystal 15 is weak.

Description

[Detailed description of the invention] Concerning children.

[Technical background of the invention and its problems]

Liquid crystal elements, which have a large number of microscopic shutter sections that control the transmission of light, are used for optical writing in optical writing type printers and for displaying images on televisions and image-receiving surfaces.

Among such liquid crystal elements, the liquid crystal element used for optical writing, that is, the liquid crystal shutter, is made by disposing a pair of transparent substrates facing each other with a liquid crystal layer made of GH (dust-host) effect type liquid crystal in between. A large number of transparent signal electrodes are formed on the inner surface of one substrate, and a common electrode is formed on the inner surface of the other substrate so as to face each other, and a metal film is formed on the signal electrodes and the common electrode, leaving 7-shape forming portions. As a result, a shutter section is formed by the opposing signal electrodes, the common electrode, and the liquid crystal between the electrodes, and a large number of these 7-shape sections are arranged.

Since this liquid crystal shutter needs to be driven at high speed, a two-frequency drive method that utilizes the dielectric dispersion phenomenon of liquid crystal is adopted. In this driving method, when a high frequency electric field is fully applied to the liquid crystal, the liquid crystal molecules are aligned perpendicular to the electric field, and when a low frequency electric field is applied, the liquid crystal molecules are aligned parallel to the electric field. In the case of a GH type liquid crystal element using this drive method, the shutter part closes (no light transmittance) when high frequency is applied.
・・Coloring), the shutter part opens when low frequency is applied (light transmission・・
...no coloring).

Conventionally, in this type of liquid crystal cage, an oriented iTh is formed on the inner surfaces of both of the pair of substrates, and a horizontal alignment process is applied to each of the oriented films, so that the liquid crystal is sealed between the pair of substrates. A horizontal alignment regulating force is applied to the GH type liquid crystal from both alignment films of both substrates to initially align the liquid crystal molecules.

However, with the configuration in which the liquid crystal is aligned in this manner, liquid crystal molecules near the alignment films formed on both substrates are strongly subjected to the horizontal alignment regulating force of each alignment film. For this reason, when a low-frequency electric field is applied to the liquid crystal when driving the shutter section, the liquid crystal molecules near the alignment film cannot be aligned vertically, and the incident light is absorbed by the liquid crystal in that area. However, there was a problem in that the amount of light when the shutter was open was insufficient, resulting in a decrease in contrast.

Figure 5 shows the state of liquid crystal molecules in a conventional liquid crystal shutter when a low frequency is applied (between the shutter parts).
2 is a substrate, and 3.4 is a substrate l.

2 is an alignment film formed and subjected to a rubbing treatment, and 5 is a liquid crystal.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and an object of the present invention is to provide a liquid crystal element that can be driven at high speed while maintaining high contrast.

[Summary of the invention]

The liquid crystal element of the present invention has a pair of substrates placed opposite each other with a liquid crystal sandwiched between them, and an alignment treatment layer for regulating the alignment direction of liquid crystal molecules is formed on the inner surface of one of the substrates. It was designed to alleviate the

[Embodiments of the invention]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings for all examples of liquid crystal elements used for optical writing in an optical writing type grid.

An optical writing type glitterer controls light from a light source with a liquid crystal element, and performs optical writing by irradiating the light beam transmitted through the liquid crystal element as a light spot on the surface of a photosensitive drum. This is a device that develops an electrostatic latent image on the surface of a photosensitive drum with toner, transfers it to recording paper, and then fixes the transferred toner image on recording paper to perform glint.

The liquid crystal element has a horizontally elongated shape along the axial direction of the photosensitive drum, and has a large number of shutter parts formed at close intervals along its length to control transmission of light.

Figures 1 and 4 show liquid crystal elements, and here a GH effect type liquid crystal element is shown.

The structure of this liquid crystal element will be explained with reference to FIGS. 3 and 4. In the figure, reference numerals 11.12 denote a pair of upper and lower substrates made of transparent glass plates, and the pair of substrates 11.12 are formed inside an oblong frame-shaped outer sealing material 13a and both sides of this outer sealing material 13a. A pair of parallel inner sealing materials J3b and 13b are bonded to each other. Both ends of the inner sealing materials 13b and Jsb are connected to both sides of each of the six outer sealing materials 13m, and the substrates 11.
The inner sealing material 13b between 12.

13b and both sides of the outer sealing material 13a, the nine portions are defined as a space 14.degree. 14 in which air is sealed. The inner sealing material 13b.

Both ends of the narrow portion between the substrates 11 and 13b are communicated with the wide portions at both ends of the outer sealing material 13L, and the liquid crystal 15 is filled in the narrow portion and the wide portion between the substrates 11 and 12. This liquid crystal 15 is made of dust phosphorus (Dust Phosphate) in which dichroic dye is dissolved in the liquid crystal.
GH). Note that the liquid crystal 15 is injected from a liquid crystal injection hole 16 provided in the outer sealing material 13&, and after injection, the liquid crystal injection hole 16 is sealed with a sealing material 17.

Among the substrates 11 and 120, one substrate 1 (hereinafter referred to as a signal electrode substrate) has inner sealing materials 13b and 1 on its inner surface.
A large number of signal electrodes 18 are formed side by side over the entire length within the narrow portion between the electrodes 3b. Further, on both sides of the inner surface of the signal electrode substrate 11, a large number of lead electrodes 19 are formed in rows, which are alternately led out from the signal electrodes 18 on the left and right sides, and are located outside the outer sealing material 13a. The +7- electrode 19 is placed on the inner surface of the substrate 1.
A large number of terminal electrodes 20 connected to... are formed side by side. Note that each of these electrodes 18..., 19
. . . and 20 . . . are integrally formed of a transparent electrode material such as insium. The signal electrode 18.
A metal film 21 made of a low-resistance metal such as chromium or gold is coated on a portion that does not correspond to the shutter section described later and on the lead electrode 19.r. No. 2... is the signal electrode 18... covered with this.
and the lead electrodes 19... are provided to reduce the electrical resistance of the portions.

Further, on the inner surface of the other substrate 12 (hereinafter referred to as the common electrode substrate), two strip-shaped common electrodes 22.degree. 22 are formed in parallel with a minute interval so as to face the signal electrodes of the signal electrode substrate 11.

The common electrodes 22.22 are the signal electrodes 18..., the lead electrodes 19... and the terminal electrodes 20 of the signal electrode substrate 11.
A signal electrode, a lead electrode, and a terminal electrode corresponding to the above are integrally formed, and is made of a transparent conductive material such as inzoum oxide. A metal film 23.23 made of a low-resistance metal is deposited on the common electrode 22.22, except for a shutter portion to be described later. This metal film 23.23 is provided to reduce the electrical resistance of the common electrodes 22.22 and to regulate the light transmission area of the shutter section.

Further, each signal electrode 1 is provided on the inner surface of the signal electrode substrate 11.
An alignment film 24 is formed to cover the region where the liquid crystal 15 is injected, including the surfaces of the common electrodes 22 and 22, and the liquid crystal 15 is injected into the inner surface of the common electrode substrate 12. The orientation is P! X25 is formed. One of the alignment films of these side substrates, for example the alignment film 24 of the signal electrode substrate 11, has been subjected to horizontal alignment treatment, and this alignment Mz4 is made of polyimide resin, PVA (
The material is made of polyvinyl alcohol, etc. with silane and a bling agent added thereto, and is formed by applying a uniform Kli cloth, then polymerizing or drying, and then subjected to a rubbing treatment in a predetermined direction. In the figure, 24m is the rubbed surface. Alignment film 254 on the other common electrode substrate 12
, is formed of the same material as the alignment film 24, but is not subjected to rubbing treatment. That is, only one of the alignment films is subjected to the rubbing treatment.

The shutter forming portions of each signal electrode 18, each common signal electrode 22, 22, and the liquid crystal 15 located between these two shutter forming portions form a large number of shutter forming portions S...
All are arranged and configured.

In the liquid crystal element configured in this way, the horizontal alignment regulating force of the horizontally aligned alignment film 24 on the side of the signal electrode substrate 11 acts on the liquid crystal 15, and the liquid crystal molecules of the liquid crystal 15 are parallel to the substrate and are rubbed. Initial orientation along the direction.

When driving the shutter section S, when a high frequency electric field is applied to the liquid crystal 15 between the signal electrode 18 and the common electrode 22 as shown in FIG. (direction perpendicular to the direction of the electric field), and the shutter section S... closes (no light transmits). In this case, the liquid crystal molecules are aligned in a predetermined direction (rubbing direction) by the horizontal alignment regulating force of the alignment film 24 on the side of the signal electrode substrate 1. Further, as shown in FIG. 2, when a low frequency electric field is applied to the liquid crystal 5, the liquid crystal molecules are aligned vertically (parallel to the direction of the electric field), and the shutter section S becomes open (light transmitting). In this case, the alignment films 24 and 25 of both electrode substrates 11 and 12
Rather than subjecting both of them to a rubbing process, only one of the alignment films is subjected to a horizontal alignment process, and the horizontal alignment regulating force acting on the liquid crystal 15 is small, so that the liquid crystal 15 is reliably aligned vertically. That is, the liquid crystal molecules in the vicinity of the alignment film 25 which has not been subjected to horizontal alignment processing are aligned vertically, and the absorption of light by the liquid crystal 15 in this portion is eliminated, making it possible to obtain a high contrast between the open state and the closed state.

In this way, the liquid crystal 15 behaves in response to the application of an electric field using the two-frequency driving blade type, so that the shutter section 10 can be driven to open and close at high speed.

Here, a specific example will be explained.

One set each of liquid crystal shutters was manufactured as an example of the present invention and a conventional example. For each liquid crystal display, the liquid crystal materials for GH type shown in Table 1 were used, and the dyes shown in Table 2 were used. The alignment film is t? An IJ imide resin was used, and in the example of the present invention, the rubbing treatment was applied to only the alignment film on one substrate, and in the conventional example, the rubbing treatment was applied to the alignment films on both substrates, respectively. The liquid crystal was driven by a two-frequency drive blade type. The drive signal has a high frequency of 200 kHz.

A low frequency of 3.3 kHz and a voltage of 30 V were used. Then, the example of the present invention and the conventional example are compared with each other when the shirt shirt is open and closed. The amount of light when the shirt shirt is closed is almost the same for both, and there is no difference. When the shirt flap is open, the example of the present invention has an average of 10% more light and is brighter than the conventional example, and the contrast of the example of the present invention is superior to the extent of this contribution. Further, in the example of the present invention, even though the orientation treatment was performed only on one side, there was no difference in the initial orientation form from the conventional example.

In the present invention, the surface treatment applied to the surface of the alignment film is not limited to rubbing treatment, and other treatments may be used. The alignment film to be subjected to surface treatment is not limited to that on the signal electrode substrate, but may be on the common electrode substrate side. The alignment film subjected to surface treatment may be one subjected to surface treatment to align the orientation of liquid crystal molecules in a certain direction. As described above, an alignment film is generally formed on the surface-treated substrate on which no alignment film is provided, but an insulating film having no alignment regulating force may also be formed.

The liquid crystal element of the present invention can be used not only for optical writing in optical writing printers, but also for various liquid crystal display devices.

〔Effect of the invention〕

As explained above, according to the liquid crystal element of the present invention, since the alignment treatment layer that regulates the alignment direction of liquid crystal molecules is formed on only one substrate, it is possible to increase the contrast when opening and closing the shutter part, and also It is possible to realize faster opening/closing drive of the parts.

[Brief explanation of drawings]

1 to 4 show an embodiment of the liquid crystal element of the present invention, FIGS. 1 and 2 are cross-sectional views of the liquid crystal element showing the closed and open states, and FIG. FIG. 4 is a plan view showing the inner surface of the segment substrate, FIG. 4 is a cross-sectional view of a liquid crystal element, and FIG. 5 is a cross-sectional view showing the schematic structure of a conventional liquid crystal element. 1 No... Signal electrode substrate, 12... Common electrode substrate, 1
5...Liquid crystal, 18...Signal electrode, 22...Common electrode 24.25...Alignment film.

Claims (1)

[Claims] A liquid crystal layer consisting of a guest-host effect type liquid crystal, a pair of substrates placed opposite each other with this liquid crystal layer in between, one electrode formed on the inner surface of one of the pair of substrates, and one electrode formed on the inner surface of one of the pair of substrates. and another electrode formed on the inner surface and arranged opposite to the one electrode, and an alignment treatment layer for regulating the alignment direction of the liquid crystal molecules of the liquid crystal is formed on the inner surface of one of the pair of substrates. A liquid crystal element featuring: