JPS6057572B2 - liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a liquid crystal display using a transparent conductive film, and more particularly to a liquid crystal display using a transparent conductive film using an amorphous polymer molded product as a base film.

2. Description of the Related Art Conventionally, transparent conductors for liquid crystal displays have been made of glass whose surface is made transparent and conductive.

However, liquid crystal displays are becoming increasingly lighter and thinner, and attempts have also been made to install a liquid crystal panel between two opposing polarizing plates in order to increase the contrast of the display. Under such circumstances, when the glass surface is made transparent and conductive, it is not possible to make the glass plate thinner due to the mechanical strength of the glass and manufacturing constraints, and O, 57Q is said to be the limit. Therefore, there are natural limits to its application to the above purposes, and furthermore, due to its vulnerability to impact, it is likely to cause damage and become unreliable during the assembly process of the element and the completed display. I have no choice but to. On the other hand, an attempt has been made to utilize a transparent conductive film, which is formed by providing a transparent conductive thin film on the surface of a polymer molded product, in a liquid crystal display by utilizing the dynamic alignment change of a nematic phase liquid crystal substance. Encapsulated type liquid crystal display for the purpose of improving durability (Japanese Patent Laid-Open No. 1983
-22694 publication), and those using metal or alloy as the transparent electrode thin film material (Japanese Patent Application Laid-Open No. 53-7405).
(see Publication No. 5) is known.

In particular, the latter is possible when tin oxide or indium oxide is used as the transparent electrode coating material, which is possible with inorganic glass but difficult to achieve with synthetic resin, by using metal or alloy as the material. It is noteworthy that synthetic resin can also be used. However, the present inventors have discovered that it is possible to form a transparent conductive film such as tin oxide and/or indium oxide on a synthetic resin molded product, which has been considered difficult or impossible in the past. For display bodies, it has been discovered that amorphous polymer moldings are preferable among synthetic resin moldings, and the present invention has been achieved.

That is, the present invention provides a voltage application type liquid crystal display that uses a transparent conductive film formed by providing a transparent conductive thin film on the surface of a polymer molded product in combination with a polarizing plate as a pair of transparent electrodes that sandwich a liquid crystal substance. The liquid crystal display is characterized in that the polymer molded product is an amorphous polymer molded product, and the transparent conductive thin film is provided on the surface thereof with an undercoat to improve adhesion, among others: The amorphous polymer molded product is a molded product of polyethersulfone or polysulfone, or a liquid crystal display in which the transparent conductive thin film is a thin film of indium oxide containing tin oxide or tin oxide containing antimony oxide. . The liquid crystal display of the present invention is of a type that uses a polarizing plate to improve its display effect, and has a structure as shown in FIG. 1, for example.

That is, an amorphous polymer film 1 is used as a base material, a transparent conductive coating 2 is provided thereon, and a liquid crystal composition 4 is sealed between the opposing coatings. The liquid crystal composition is sealed using a suitable spacer 3. However, the seal does not necessarily have to be the spacer 3; a separate sealing material may be used, or the film 1 may be fused together. Also, the spacers 3 do not necessarily have to be provided only at both ends, but they do make the thickness of the liquid crystal layer uniform! Any suitable number and shape of spacers may be present to accommodate the spacer. The liquid crystal display element assembled in this manner is inserted between two polarizing plates 5 whose polarization angles are vertically perpendicular to each other to form a liquid crystal display. At this time, the amorphous polymer film 1 and the polarizing plate 5 can be laminated in advance. The amorphous polymer molded product is a molded product of polyethersulfone, polysulfone, polyacrylate, polymethyl methacrylate, polycarbonate, etc., and its form is preferably sheet-like, film-like, and especially film-like. .

Among the above amorphous polymer molded products, heat resistance, chemical resistance,
From the viewpoint of adhesion, polyether sulfone films and polysulfone films are preferred. The thickness of the amorphous polymer molded product is preferably in the range of 50 μm to 500 μm.

If it exceeds 500 pm, it deviates from the purpose of making the liquid crystal display thinner.

Further, if the thickness is less than 50 μm, it is difficult to maintain a constant distance between the electrodes of the liquid crystal display because of flexibility. Therefore, a range of 75 μm to 200 μm is particularly preferable from the viewpoint of keeping the electrode spacing constant and making it thinner, and from the viewpoint of producing a transparent conductive film. Examples of the transparent conductive thin film provided on the amorphous polymer molding include an indium oxide thin film doped with a small amount of tin oxide, a tin oxide thin film doped with a small amount of antimony oxide, and a cadmium/tin oxide (CdSnO,) thin film. In particular, from the viewpoint of transparency and etching resistance, indium oxide thin films doped with a small amount of tin oxide and tin oxide thin films doped with a small amount of antimony oxide are suitable.
Particularly preferred is an indium oxide thin film doped with a small amount of tin oxide. In addition, the transparent conductive thin film is normally exposed to visible light (550r1w
t, ) is at least 75% and the surface resistance is less than 10KΩI, preferably the transmittance is at least 80% and the surface resistance is less than 5KΩI. Incidentally, undercoating to improve the adhesion between the thin film and the amorphous polymer molded product serving as the substrate can be performed by a conventional method using a silane coupling agent or the like.

Methods for providing a transparent conductive thin film on the surface of the polymer molded product include vacuum evaporation, sputtering,
Examples include physical means such as ion blating method.
For example, in the case of an indium oxide thin film doped with a small amount of tin oxide, the substance is vacuum-deposited in a vacuum, and the resulting low-oxide thin film is heated to the desired high Methods for converting into the following oxides can be selected depending on the type of polymer molded product, such as reactive vapor deposition in an oxygen atmosphere or sputtering. An example of the structure of a liquid crystal display using the transparent conductive film thus obtained is shown in FIG.

Since the liquid crystal display of the present invention uses crossed nicols and the transparent conductive film has no optical anisotropy, there is no coloration of the film within the crossed nicols, and it is dark, allowing white light to pass through. When a voltage is applied to the liquid crystal display, the molecules of the liquid crystal rotate, producing birefringence and changing the hue, resulting in a display effect with excellent contrast.

Moreover, since the thickness of the element of the liquid crystal display can be made thin, it is possible to fully satisfy the purpose of making the liquid crystal display lightweight and thin. Example 1 After a polyether sulfone film with a thickness of 100μ was undercoated with a silane coupling agent, 11120395 parts,
5×10-5T0 using a mixture consisting of 25 parts of SnO
The deposition was performed under rr at a deposition rate of 20 A1 sec.

The thickness of the deposited film was 130A. Subsequently, heat treatment was performed at 150° C. to produce a transparent conductive film having a resistance value of 4K01 and a transmittance of 86%. Since polyether sulfone film is an amorphous polymer film, the extinction position does not show optical anisotropy in any direction of the film, and the entire surface of the film can be punched out in a free shape and used as an electrode for liquid crystals. It was possible. The adhesion between the transparent conductive layer and the film substrate was good, and when rubbed under a load of 100yIc71f, 1
The resistance value after the old friction was within 7 times the resistance value before the friction.

When a liquid crystal display having the structure shown in FIG. 1 was assembled using this film and a voltage was applied between the transparent conductive layers, a change in hue occurred and a display effect with excellent contrast was exhibited.

In addition, the display body was extremely thin with a thickness of 0.77 rm compared to a conventional display body using glass, and was also lightweight. Example 2 Using a polysulfone film with a thickness of 100μ, Example 1
When a transparent conductive film was produced under the same conditions as above, the resistance value was 3.5K01 and the transmittance was 87%.

Since polysulfone film is an amorphous polymer film, the extinction position does not show optical anisotropy in any direction of the film, and the entire surface of the film can be punched out in any shape and used as an electrode for liquid crystals. It was hot. Furthermore, the adhesion between the transparent conductive layer and the film substrate was comparable to that of Example 1.

When a liquid crystal display having the structure shown in FIG. 1 was assembled using this film and a voltage was applied between the transparent conductive layers, a change in hue occurred and a display effect with excellent contrast was exhibited.

The display body was extremely thin and lightweight compared to conventional displays using glass. Furthermore, the display did not break even when dropped from a height of 1 m.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a liquid crystal display. 1 represents an amorphous polymer film, 2 represents a transparent conductive coating, 3 represents a Spencer, 4 represents a liquid crystal composition, and 5 represents a polarizing plate.

Claims (1)

[Claims] 1. A voltage-applied liquid crystal display in which a transparent conductive film formed by providing a transparent conductive thin film on the surface of a polymer molded product is used in combination with a polarizing plate as a pair of transparent electrodes that sandwich a liquid crystal substance. A liquid crystal display, characterized in that the polymer molded product is an amorphous polymer molded product, and the transparent conductive thin film is provided on the surface thereof with an undercoat to improve adhesion. 2. The liquid crystal display according to claim 1, wherein the amorphous polymer molded product is a molded product of polyethersulfone or polysulfone. 3. The liquid crystal display according to claim 2, wherein the transparent conductive thin film is a thin film of indium oxide containing tin oxide or tin oxide containing antimony oxide.