JPH06110064A - Liquid crystal display device - Google Patents

Abstract

PURPOSE:To improve a voltage holding rate on a liquid crystal so as to decrease display defects, to prevent the drop of the impressed voltage and to ameliorate the intra-surface nonuniformity of a contrast by clamping a liquid crystal between two sheets of substrates having electrodes and incorporating ion absorptive materials into the liquid crystal. CONSTITUTION:The ion absorptive materials, such as cation exchange resin and anion exchange resin, are used by dispersing these materials into the liquid crystal. The ion absorptive materials are mixed as spherical particulates 8 with the spacers 3 and are sprayed onto oriented films 5 subjected to a rubbing treatment by a spacer spraying device. Glass fibers and plastic resins are used like heretofore for the spacers 3. The ion absorptive materials are otherwise used for the spacers 3 in place of the conventional spacers. Since the ratio of the resin and spacers 3, etc., in the parts clamped by the liquid crystal display panel is thereby decreased, the intra-surface nonuniformity of the contrast is decreased.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device provided with a substance that adsorbs impurity ions in liquid crystal.

[0002]

2. Description of the Related Art Color display technology using liquid crystals has been put to practical use in various fields such as liquid crystal TVs. As shown in FIG. 4, a conventional color liquid crystal display device has a color filter substrate 1 and a counter substrate 2, and ITO (Indium) is provided on each substrate.
A -Tin-Oxide) film 4 is formed, and an alignment film 5 is provided on the surface of the ITO film 4. And these two substrates 1,
In order to realize a high viewing angle and a high contrast, 2 is sandwiched by a spacer 3 which maintains a uniform gap, and a seal 6
Thus, these two substrates are adhered to each other and the liquid crystal 7 is provided inside. Further, at this time, the spacers 3 are distributed at even intervals on the substrate to ensure the uniformity of the screen.

[0003]

In the conventional manufacturing process of a color liquid crystal display device, there are cases where ionic impurities are taken in during the assembly process or the material itself constituting the liquid crystal display device contains ionic impurities. However, these ionic impurities were mixed in the liquid crystal 7. Once mixed in the device, it cannot be removed from the device, and as the amount of impurities increases, the voltage holding ratio for the liquid crystal during liquid crystal driving decreases, causing display problems such as unevenness. .

Further, an electric double layer or the like is formed on the surface of the alignment film 5, and the voltage applied to the liquid crystal is lowered, so that the contrast is lowered.

[0005]

According to the present invention, there is provided a liquid crystal display device characterized in that a liquid crystal is sandwiched between two substrates having electrodes and an ion-adsorbing substance is contained in the liquid crystal.

Further, according to the present invention, there is obtained a liquid crystal display device having a spacer and fine particles of an ion-adsorbing substance smaller than the spacer in the liquid crystal.

Further, according to the present invention, there is obtained a liquid crystal display device characterized by having a spacer made of an ion-adsorbing substance in the liquid crystal.

Next, according to the present invention, there is obtained a liquid crystal display device characterized by using an ion exchange resin as the ion-adsorbing substance.

Further, according to the present invention, a liquid crystal display device characterized by using synthetic zeolite as an ion-adsorbing substance can be obtained.

Cations such as Na and K and Cl, Br and F
Anionic impurities, such as, may be taken into the liquid crystal during the assembling process of the liquid crystal display device or may be contained in the constituent material itself, and are easily mixed in the liquid crystal. Impurity ions once taken into the liquid crystal are difficult to remove to the outside of the device.

The presence of these impurity ions lowers the voltage holding ratio of the liquid crystal when the liquid crystal device is driven, forms an electric double layer on the surface of the alignment film, and lowers the voltage applied to the liquid crystal. As a result, display defects such as unevenness and a decrease in contrast occur.

The present invention is intended to remove impurity ions by having an ion-adsorptive substance in the liquid crystal.

As the ion-adsorptive substance, there is a cation-exchange resin which is a polymeric acid in which an acidic group such as an acidic hydroxyl group, a carboxyl group or a sulfo group is bonded to a base synthetic resin such as polystyrene cross-linked with divinylbenzene. .
Further, there is an anion exchange resin which is a polymer base in which a basic group such as an amino group, an imino group or an ammonium group is bonded to a base synthetic resin. Further, other ion exchange resins, ion exchange celluloses, ion exchange membranes, synthetic zeolites, silica gels, silica alumina, magnesia, etc. may be mentioned. From the viewpoint of low reflectance, an ion exchange resin, synthetic zeolite or the like is preferably used. Further, the synthetic zeolite is more effective because it also has water absorption. These cation exchange resin, anion exchange resin and the like function as a molecular sieve that adsorbs impurity cations and anions in liquid crystal on the surface or has selective adsorptivity.

Ion-adsorptive substances such as cation exchange resins and anion exchange resins are used by being dispersed in liquid crystals.
Two forms are proposed as the method. Firstly, the ion-adsorptive substance is mixed as spherical fine particles with the spacer, and is dispersed on the alignment film that has been rubbed by the spacer dispersion device. At this time, as the spacer, glass fiber or plastic resin is used as usual.

Second, instead of the conventional spacer, an ion-adsorbing substance is used for the spacer. Since the proportion of resin, spacers, etc. in the portion sandwiched by the liquid crystal panels is smaller than that of the first one, the in-plane non-uniformity of contrast is reduced.

[0016]

The present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a first embodiment of the present invention. The fine particles 8 are the diameter of the spacer 3 (4.6 μm)
Spherical cation exchange resin and anion exchange resin of smaller diameter (2.3 μm), which is mixed with spacer 3 (a schematic of which is shown in FIG. 3A). The ITO film 4 is superposed on the color filter substrate 1, and the rubbing-treated alignment film 5 is formed thereon. The above-mentioned mixture of the ion-exchange resin and the spacer is evenly sprayed by the spacer spraying device. The opposing substrates 2 are stacked and the liquid crystal 7 is injected. The color liquid crystal display device manufactured as described above has a voltage holding characteristic of liquid crystal of 5 to 7% as compared with the conventional one.
Improved. In addition, display defects due to ionic impurities could be reduced to one-fifth compared to the conventional case. And the decrease of the applied voltage to the liquid crystal was also eliminated.

FIG. 2 is a sectional view showing a second embodiment of the present invention. The fine particles 9 also having a spacer function have a diameter of 4.6.
It is a rod-shaped water-absorbing zeolite having a diameter of μm, and its schematic view is shown in FIG. 3B. Similar to the first embodiment, this is uniformly dispersed on the alignment film 5, the counter substrate 2 is superposed and the liquid crystal 7 is injected. In the liquid crystal display device manufactured in this manner, the voltage holding characteristic of liquid crystal is improved by 6 to 9% as compared with the conventional one. In addition, display defects were reduced to 1/10 of the conventional case. And the decrease of the applied voltage to the liquid crystal was also eliminated. In addition, since the fine particles 8 existing on the pixels of the counter substrate 2 are eliminated by also having the spacer function, the change in the luminance in the pixels, that is, the in-plane nonuniformity of the contrast is smaller than that in the first embodiment. Improved.

[0019]

As described above, in the present invention, the dispersed ion-adsorptive fine particles serve to remove the ionic impurities in the liquid crystal.

As a result, ionic impurities mixed in the liquid crystal during the manufacture of the color liquid crystal display device can be reduced, so that the voltage holding ratio with respect to the liquid crystal at the time of driving the liquid crystal is improved and the display defect is significantly reduced. Have an effect.

Further, it has an effect of preventing the formation of an electric double layer or the like on the surface of the alignment film and preventing a decrease in the voltage applied to the liquid crystal.

Further, if the ion-adsorptive substance is used as the spacer, the ratio of the ion-adsorptive substance such as the ion exchange resin in the portion sandwiched by the liquid crystal panels can be reduced. Therefore, there is an effect that the in-plane nonuniformity of the contrast is improved as compared with the case where the fine particles of the ion-adsorbing substance are dispersed in the liquid crystal.

When an ion exchange resin or synthetic zeolite is used as the ion-adsorbing substance, the reflectance is small,
It has the effect of not disturbing the display screen.

When synthetic zeolite is used as the ion-adsorptive substance, it also has the effect of adsorbing the water in the liquid crystal and removing the water in the liquid crystal.

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a schematic view of an ion-adsorptive substance used in the present invention. FIG. 3A is the ion-adsorptive substance shown in FIG. 1 and FIG. 3B is the ion-adsorptive substance shown in FIG.

FIG. 4 is a cross-sectional view showing a conventional liquid crystal display device.

[Explanation of symbols]

 1 Filter Substrate 2 Counter Substrate 3 Spacer 4 ITO Film 5 Alignment Film 6 Seal 7 Liquid Crystal 8 Fine Particles Made of Ion Adsorbent 9 Spacer Made of Ion Adsorbent

Claims (5)

[Claims] 1. A liquid crystal display device, characterized in that a liquid crystal is sandwiched between two substrates having electrodes, and an ion-adsorbing substance is contained in the liquid crystal. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal has spacers and fine particles made of the ion-adsorbing substance and having a diameter smaller than that of the spacers. 3. The liquid crystal display device according to claim 1, further comprising a spacer made of the ion-adsorptive substance in the liquid crystal. 4. An ion exchange resin is used as the ion-adsorptive substance, wherein the ion-exchange resin is used.
The described liquid crystal display device. 5. The synthetic zeolite is used as the ion-adsorptive substance, according to claim 2 or 3.
The described liquid crystal display device.