Liquid crystal display with polymeric support

Abstract

A display medium layer is sandwiched between a TFT substrate and a counter substrate. In the display medium layer, resin walls are respectively formed in regions other than those where a plurality of segmented electrodes are formed, and liquid crystal portions are respectively formed in regions between the respective resin walls, corresponding to those where the segmented electrodes are formed. Disclination lines are formed on the interfaces between the resin walls and the liquid crystal regions. In a liquid crystal display device, liquid crystal molecules in the liquid crystal regions are radially oriented and at least one liquid crystal domain is formed in each liquid crystal region.

Description

BACKGROUND OF THE INVENTION1. Field of the InventionThe present invention relate to a liquid crystal display device and a method for producing the same. More specifically, the present invention relates to a liquid crystal display device having a display medium with a structure in which liquid crystal regions are partitioned by a polymeric material and a method for producing the same.2. Description of the Related ArtAs display devices utilizing an electro-optic effect, liquid crystal display devices using nematic liquid crystals have conventionally been used. Examples of such liquid crystal display devices include a twisted nematic (TN) liquid crystal display device and a super-twisted nematic (STN) liquid crystal display device. Liquid crystal display devices using ferroelectric liquid crystal have also been proposed. These liquid crystal display devices include a pair of glass substrates, nematic liquid crystal or smectic liquid crystal provided between the substrates, and two pola...

AI Technical Summary

Benefits of technology

According to another aspect of the present invention, the method for producing a liquid crystal display device of this invention comprises the steps of (1) providing a mixture containing a liquid crystalline compound and a photopolymerizable compound between two substrates, at least one of which is transparent; and (2) irradiating light having a predetermined irradiation intensity distribution to the mixture between the two substrates, allowing a phase separation of the mixture involved in polymerization thereof to be effected, and uniformly distributing supporting walls made of a resin and a liquid crystal.

Alternatively, the method for producing a liquid crystal display device of this invention comprises the steps of: injecting a mixture containing a liquid crystalline compound, a photopolymerizable compound, and a liquid crystalline photopolymerizable compound between electrode substrates in a cell, at least one of the substrates being transparent; and irradiating the mixture with light having a uniform irradiation intensity distribution while at least one of an electric field and a magnetic field is applied to the mixture, thereby allowing phase separation involved in polymerization to be effected.

The liquid crystal display device of the present invention has a structure in which a display medium layer is sandwiched between two substrates. For producing such a liquid crystal display device, in the first step, a mixture containing a liquid crystalline compound, a photopolymerizable compound, and a photopolymerization initiator is provided between the two substrates. In the second step, the mixture is irradiated with light having a predetermined irradiation intensity distribution, thereby allowing phase separation involved in polymerization of the mixture to be effected. In this way, the display medium layer having a structure in which supporting walls made of the polymer (resin) and liquid crystal are uniformly distributed is obtained.

When the angle and direction, in which the liquid crystal display device of the present invention are observed from outside, are changed, the dependence of display contrast on a viewing angle can be eliminated because of the axisymmetric orientation of the liquid crystal molecules. Also, the axisymmetric orientation of the liquid crystal molecules prevents the disclination lines from being formed in the liquid crystal region, and thus the display quality is remarkably improved.

According to the present invention, the product .DELTA. n.multidot.d of anisotropy of refractive index .DELTA. n of the liquid crystal material and a cell gap d (distance between substrates sandwiching a display medium) is set to be in the range of 300 to 650 nm, and the twist angle of liquid crystal between the substrates is set to be in the range of 45.degree. to 150.degree. when the liquid crystal is injected therebetween. Because of this, the light transmittance of the display device can be optimized, and the light transmittance of the liquid crystal display device can be remarkably improved.

Thus, the invention described herein makes possible the advantages of (1) providing a liquid crystal display device with markedly improved viewing angle characteristics and display quality; and (2) a simplified method for producing a liquid crystal display device.

Problems solved by technology

Thus, these conventional devices have not found a wide range of use.

However, according to this method, liquid crystal domains are formed at random, a polymeric material enters a pixel portion, and a plurality of disclination lines formed at random between the liquid crystal domains are not eliminated even under the application of a voltage.

For these reasons, the conventional liquid crystal display devices have the disadvantage of low contrast, light transmittance under the application of no voltage is low, that is, the black level is not satisfactory under the application of a voltage.

Accordingly, the conventional liquid crystal display devices using polarizing plates have poor viewing angle characteristics and hence are unsuitable for use as a liquid crystal display device for a wide viewing angle.

This also makes the difference in contract between directions A and B large, and in some cases, results in an abnormal display such as a change in hue and the reversal of black and white colors.

As described above, the conventional liquid crystal display devices have the disadvantage of poor viewing angle characteristics.

This leads to problems during practical use, such as the reduction of liquid crystal regions and decreased light transmittance under the application of no voltage.

Furthermore, in this case, disclination lines between the liquid crystal domains cannot be controlled, which makes it impossible to eliminate the disclination lines even under the application of voltage.

As a result, the display quality is degraded.

Alternatively, the decrease in contrast due to difficulties in eliminating disclination lines degrades the display quality.

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