KR19990031146A - Liquid Crystal Display and Manufacturing Method Thereof - Google Patents

Abstract

Fine concave lenses are formed on the upper plate where the color filter of the liquid crystal display is formed to extend the viewing angle of the liquid crystal display. Two fine concave lenses are arranged for each pixel. The method of forming the fine concave lens is a method using a photolithography technique, a photolithography and then contacting the glass substrate with the ion exchange liquid to form a flat lens. In this way, the concave lens spreads the light passing through the liquid crystal at a wide angle, thereby extending the viewing angle of the liquid crystal display.

Description

Liquid Crystal Display and Manufacturing Method Thereof

The present invention relates to a liquid crystal display device and a manufacturing method thereof.

Hereinafter, a conventional liquid crystal display device employing the TN mode will be described.

In a conventional liquid crystal display device, a flat upper plate on which a color filter and a black matrix are formed, and a lower plate on which a thin film transistor and a pixel electrode are formed face to face, and liquid crystal is disposed between the upper and lower plates. It is injected and sealed with an adhesive.

However, the liquid crystal display having such a structure has a problem in that the change in retardation value is large with respect to the change in the viewing angle, so that the viewing angle is narrow, and gray scale inversion occurs according to the viewing angle.

An object of the present invention is to manufacture a liquid crystal display device having a wide viewing angle with simple means and low cost.

1 is a cross-sectional view of a liquid crystal display according to an exemplary embodiment of the present invention.

FIG. 2 is a plan view of an upper plate for a liquid crystal display according to an exemplary embodiment of the present invention, and illustrates an arrangement of pixels and a micro concave lens.

3 is a cross-sectional view showing a part of a process of forming a concave lens on the upper plate using a photolithography technique,

4 is a cross-sectional view showing a part of the process of forming a concave lens on the upper plate using the ion exchange penetration method,

5 is a diagram illustrating a path in which light is refracted by a fine concave lens,

6 is a table showing the degree to which light is refracted by the fine concave lens.

In order to solve the above problems, in the present invention, a fine concave lens is formed on the upper plate. Two fine concave lenses are arranged for each pixel, and a photolithography technique or an ion exchange penetration method is used as the fabrication method.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, a description will be given with reference to FIGS. 1 and 2.

1 is a cross-sectional view of a liquid crystal display device according to an exemplary embodiment of the present invention, in which liquid crystal is injected between the lower plate 1 and the upper plate 3 on which the color filter 5 is formed, and thus the adhesive agent 7 is used. It is sealed, and the upper surface of the upper plate 3 is recessed with hemispherical grooves 4 so that the groove portion of the upper plate 3 serves as a concave lens. On the top plate is a compensation plate 6. Here, the compensation plate 6 may be located elsewhere, such as under the lower plate 1. FIG. 2 shows that two grooves 4 are recessed in the upper plate 3 for each pixel 8.

In this way, as shown by the arrow in FIG. 1, even when it passes through a color filter, even if it is a substantially parallel light beam, it will be refracted in the process of passing through the concave lens part of an upper board, and it will become a light ray which spreads at a wide angle.

Now, the manufacturing method of the upper board shown in FIGS. 1 and 2 is demonstrated with reference to FIGS.

First, a method of forming a concave lens on the upper plate by a photolithography technique will be described.

A photoresist is applied on the flat top plate 3, covered with a mask having fine circular holes, perforated so as to be arranged two per pixel, and then exposed and developed. In this way, the hole 40 is drilled in the exposed part of the photosensitive agent layer 20 applied on the top plate 3, and the top plate 3 is exposed. At this time, the hole 40 is made to have a diameter slightly smaller than the fine concave lens to be formed. When the exposed portion of the upper plate 3, which is glass, is corroded with hydrofluoric acid (HF) solution, a hemispherical groove having a diameter slightly larger than the hole 40 is formed on the upper plate 3, and the groove portion of the upper plate 3 It acts as a concave lens.

Next, a method of forming a concave lens by an ion exchange penetration method will be described.

Through the photolithography process in the same manner as in the photolithography technique, as shown in FIG. 4, the upper plate 3 is exposed through the annular hole 41 drilled in the photosensitive agent layer 21. The upper plate 3 is brought into contact with the ion exchange liquid to exchange ions through the exposed portion. At this time, the density of the penetrating ions is highest in the ring-shaped hole portion in direct contact with the ion exchange liquid, and lowers as it moves away from the portion in direct contact. In this way, since light is refracted toward the higher density of ions in the course of passing through the top plate, the top plate functions as a concave lens despite being flat.

Now, the role of the fine concave lens will be described with reference to FIG. 5.

The refractive index (n₁) of the upper plate which is glass is 1.51, and the refractive index (n2) of air is 1. If the angle of incidence is θ₁ when light enters the air through the top plate, the angle of refraction θ₂ is determined by Snell's law.

sinθ ₂ = 1.51sinθ ₁

θ ₂ = sin ^-1 (1.51sinθ ₁ )

Becomes When the light is refracted as described above, the light refracted by the incident light spreads out by the effect angle (θ₂-θ 비). However, when the incident angle θ₁ exceeds 41 °, the total reflection occurs because the refractive angle θ₂ becomes 90 ° or more, and therefore, the incident angle θ₁ should be 41 ° or less. Therefore, the maximum effect angle θ₂−θ₁ can be obtained when the incident angle θ₁ is 41 °, which is about 41.2 °.

The change in the refractive angle and the effect angle according to the change of the incident angle is shown in the table of FIG. 6.

In the ion-exchange permeation method, the degree of refraction can be adjusted by changing the kind of ions to be penetrated.

When the upper plate for the liquid crystal display device is manufactured according to the exemplary embodiment of the present invention, the light emitted from the screen of the liquid crystal display device is spread at a wide angle, thereby easily enlarging the viewing angle. In particular, the present invention has the advantage that it does not require new equipment, materials or process technology for its implementation.

Claims (8)

A liquid crystal display substrate having a concave lens portion on its upper surface. In claim 1, And said concave lens portion is a hemispherical groove formed in said substrate. In claim 1, And said concave lens portion is an ion permeation portion formed in said substrate. The method of claim 1, 2 or 3, A substrate for a liquid crystal display device wherein two concave lens portions are arranged per pixel. In claim 4, A liquid crystal display substrate further comprising a color filter formed on the bottom surface of the substrate. A substrate on which a concave lens portion is formed, And a compensation plate attached to an outer side of the substrate. Applying a photosensitizer onto the substrate, Covering and exposing a mask having a circular hole on the substrate, Developing the substrate to remove the exposed portion of the photosensitizer, And etching the substrate by contacting the substrate with a hydrofluoric acid solution. Applying a photosensitizer onto the substrate, Covering and exposing a mask having a ring-shaped hole formed on the substrate, Developing the substrate to remove the exposed portion of the photosensitizer, A method for manufacturing a substrate for a liquid crystal display device comprising the step of contacting the substrate with an ion exchange penetration liquid.