JPH0682773A - Ferroelectric liquid crystal device - Google Patents

Abstract

PURPOSE:To perform gradation display without lowering the cost of a ferroelectric liquid crystal device. CONSTITUTION:A ferroelectric liquid crystal device has picture element electrodes 2 and orienting films 3 on both sides of opposed insulating bases 1; a dielectric layer A4 and a dielectric layer B5 between at least either one-side picture element 2 and orienting film 3; and a ferroelectric liquid crystal 6 nipped between the insulating bases 1. Since the ferroelectric liquid crystal device has two kinds or more of dielectric constants on the picture element electrodes, the short-circuit between the opposed picture element electrodes can be prevented by the dielectric layer A4 or dielectric layer B5, and gradation display can be performed by the difference in dielectric constant between dielectric layers in one picture element. Since the difference between the dielectric layers can be easily formed in a good yield, this device has the effect in that the reduction in yield by refining of pattern by division of a conventional picture element electrode and the cost up by increase of driving IC can be significantly improved. Since the picture element electrode is not divided, this device further has the effect of never reducing aperture ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ferroelectric liquid crystal device used for an image display panel of a personal computer or a liquid crystal television.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 2, a ferroelectric liquid crystal device has a pixel electrode 2 formed on a glass substrate 1 facing each other.
A structure in which a dielectric layer 9 is laminated on one side, an alignment film 3 is laminated, a rubbing treatment is performed, and a ferroelectric liquid crystal 6 is sandwiched is generally used. The ferroelectric liquid crystal device shown in FIG. 2 is difficult to perform halftone representation by voltage or pulse width modulation used in the twisted nematic liquid crystal device due to its characteristic bistability. A general method is to divide and perform area gradation.

[0003]

However, the conventional area gradation has a problem that the cost is deteriorated due to a decrease in manufacturing yield and an increase in driving IC due to an increase in scanning electrodes and signal electrodes and miniaturization, and an aperture ratio. However, there was a quality problem of deterioration.

Therefore, an object of the present invention is to obtain an area gradation by an inexpensive and easy manufacturing method in order to solve such a conventional problem.

[0005]

In order to solve the above-mentioned problems, the present invention has a pixel electrode and an alignment film on both sides of an insulating substrate facing each other, and at least one of the pixel electrode and the alignment film is provided between the pixel electrode and the alignment film. In a ferroelectric liquid crystal device having a dielectric layer and sandwiching a ferroelectric liquid crystal between the insulating substrates, the structure of the dielectric layer is formed on one pixel electrode depending on the film thickness or the relative dielectric constant. I made two or more kinds.

[0006]

In the ferroelectric liquid crystal device having the above-described structure, the gradation voltage is obtained by utilizing the fact that two or more kinds of dielectric layers having different permittivities on one pixel electrode have different threshold voltages in area. It becomes possible to display.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. (Example 1) In FIG. 1A, a pattern was formed on a glass substrate 1 by using, for example, ITO as a pixel electrode 2.
After that, the dielectric layer A4 having a relative dielectric constant of εSA and the relative dielectric constant of εSA are ε
The dielectric layer B5 of SB was formed on the pixel electrode 2 so that, for example, the film thickness was the same and the area was 1/2. For example, here, a Ta2O3 film is formed on the dielectric layer A4 and an S layer is formed on the dielectric layer B5.
Since the iO2 film is used, the relationship of εSA> εSB is established, and the dielectric constant thereof is εA> εB. Further, an alignment film is laminated on the dielectric layers A4 and B5 and subjected to a rubbing treatment. For example, in this embodiment, a ferroelectric liquid crystal is provided between the alignment film and an opposing glass substrate having only the alignment film laminated on the pixel electrodes. 6 was sandwiched to form a ferroelectric liquid crystal device. Here, the pixel electrode 2 and the dielectric layer A
Ferroelectric liquid crystal in the portion where 4 is laminated is set to the liquid crystal region A.
7. The ferroelectric liquid crystal in the portion where the pixel electrode 2 and the dielectric layer B5 are laminated will be referred to as a liquid crystal region B8. Figure 1
1B is a voltage-transmittance characteristic of the ferroelectric liquid crystal device of the present embodiment, which has a first threshold value VthA by the liquid crystal area A7 and a second threshold value VthB by the liquid crystal area B8 in FIG. Then
It is shown that the area gradation can be performed by utilizing the difference ΔVth between VthA and VthB.

In the first embodiment, two kinds of dielectric layers on the pixel electrode are arranged on one side, but the number of kinds may be three or more,
It goes without saying that the number of gradations can be increased by disposing them on both sides. (Embodiment 2) In the present embodiment 1, the difference in dielectric constant of two or more types of the dielectric layers on the pixel electrodes is constituted by two or more types of dielectric layers having different relative dielectric constants. By changing the film thickness even for one type of dielectric layer,
For example, if the dielectric layer 9 (dielectric constant εC) of the liquid crystal region C10 is thinned and the dielectric layer 9 (dielectric constant εD) of the liquid crystal region D11 is thickened, εC> εD, and the liquid crystal region C is the same as in the first embodiment.
A first threshold VthC of 10 and a second threshold VthD of the liquid crystal region D11 are provided, and the area gradation can be performed by utilizing the difference ΔVth between VthC and VthD.

(Third Embodiment) Further, by combining or laminating dielectric layers having different relative dielectric constants or film thicknesses, several different dielectric constants of the dielectric layers on the pixel electrodes are formed. Area gradation can be performed. In FIG. 4, as an example, a dielectric layer 4 having a relative permittivity εA is uniformly formed on the pixel electrode 2, and then a dielectric layer 5 having a relative permittivity εB is formed in a half area on the pixel electrode 2. FIG. If the permittivity of the liquid crystal region E12 is εE and the permittivity of the liquid crystal region F13 is εF, then εE> εF, and area gradation is possible as in the first embodiment.

[0010]

As described above, according to the present invention, the pixel electrodes and the alignment film are provided on both sides of the opposing insulating substrates, and the dielectric layer is provided between at least one of the pixel electrodes and the alignment film. In the ferroelectric liquid crystal device in which the ferroelectric liquid crystal is sandwiched between the insulating substrates, the ferroelectric liquid crystal device having at least two types of dielectric constants on the pixel electrode of the dielectric layer is used. The body layer can prevent a short circuit between the opposing pixel electrodes, and at the same time, can express gradation by the difference in the dielectric constant of the dielectric layer in one pixel. Since the difference in the dielectric layers can be easily formed with a high yield, the yield is significantly reduced due to the miniaturization of the pattern due to the division of the conventional pixel electrode, and the cost increase due to the increase of the driving IC is significantly improved. There is. Moreover, since the pixel electrode is not divided, there is an effect that the aperture ratio is not lowered.

[Brief description of drawings]

FIG. 1A is an explanatory diagram showing a cross-sectional view of a ferroelectric liquid crystal device according to a first embodiment of the present invention. (B) It is explanatory drawing which showed the voltage-transmittance characteristic of the ferroelectric liquid crystal device of this invention.

FIG. 2 is an explanatory diagram showing a cross-sectional view of a conventional ferroelectric liquid crystal device.

FIG. 3 is an explanatory diagram showing a cross-sectional view of a ferroelectric liquid crystal device according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a cross-sectional view of a ferroelectric liquid crystal device according to a third embodiment of the present invention.

[Explanation of symbols]

 1 Glass Substrate 2 Pixel Electrode 3 Alignment Film 4 Dielectric Layer A 5 Dielectric Layer B 6 Ferroelectric Liquid Crystal 7 Liquid Crystal Region A 8 Liquid Crystal Region B 9 Dielectric Layer 10 Liquid Crystal Region C 11 Liquid Crystal Region D 12 Liquid Crystal Region E 13 Liquid Crystal Area F

Claims (3)

[Claims] 1. A ferroelectric film having a pixel electrode and an alignment film on both sides of an opposing insulating substrate, a dielectric layer between at least one of the pixel electrode and the alignment film, and a ferroelectric layer between the insulating substrates. In a ferroelectric liquid crystal device sandwiching an organic liquid crystal, the dielectric layer on the pixel electrode has at least two types of film thickness. 2. The ferroelectric liquid crystal device according to claim 1, wherein the dielectric layer on the pixel electrode comprises at least two types of dielectric layers having different relative permittivities. Liquid crystal device. 3. The ferroelectric liquid crystal device according to claim 1, wherein the dielectric layer on the pixel electrode has a multi-layer structure including at least two layers. apparatus.