JPS63254420A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To prevent the deterioration of contrast caused by an incidence of external light, by performing black coating to the outside of a polarizing plate of a negative type liquid crystal display element. CONSTITUTION:The titled element for executing a display brightly to a black background is formed by placing both faces of a substrate 1 for constituting a liquid crystal cell, between polarizing plates 2, and to a part which does not obstruct a display of the outside of the polarizing plate 2, black coating 3 is performed. Also, as for the element having a light source, it is desirable to perform white coating 4 onto the coating 3 of the light source side. When the coating 3 is performed, incidence of the external light being harmful to the display is obstructed, therefore, the display can be made easily visible by preventing the deterioration of contrast caused by the incidence of the external light. Also, when the coating 4 is performed to the element having the light source, a light beam which is radiated thereto is reflected, and a uniform incident light can be obtained on the display part.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element that can display a bright display with particularly good contrast against a black background.

(Prior art) A so-called negative type liquid crystal display element that displays on a black background can freely select the display color, especially if it is a transmitted light type liquid crystal display element equipped with a rear light source, and if the light source is made brighter, the display color can be freely selected. Since it provides an easy-to-read display that is relatively unaffected by external light, it is often used, for example, in automobile display panels (Japanese Patent Application Laid-open No. 102611/1983).

However, although it is said that negative display liquid crystal display elements are relatively easy to read, they are not unaffected by external light irradiation, and especially when installed in a car, the environment changes significantly, so it is necessary to further improve the contrast. was desired.

FIGS. 2(a) and 2(b) are diagrams showing examples of conventional negative type liquid crystal display elements, in which ■ indicates a glass substrate with a liquid crystal sandwiched between them to form a liquid crystal cell; , 3 are black coated. FIG. 2(a) is mainly used for those utilizing normal reflected light, and FIG. 2(b) is mainly used for transmitted light. In either case, black coating is applied to areas that do not interfere with display in order to improve contrast. Of course, if such a black coating is applied, it is unavoidable that the 16th case will rise, so there are many cases without a black coating. Similarly, conventionally, a black coating was applied to the outside of the polarizing plate of either one of the upper and lower glass substrates. This produces a considerable effect, but since there is no black coating on the outside of one of the polarizing plates, external light that enters the glass substrate at a large angle of incidence is repeatedly reflected within the glass substrate, reducing contrast. In many cases, the environment changes considerably, especially when mounted on a vehicle, so it has been desired to further improve the contrast.

[Problem that the invention seeks to solve]

The present invention solves the above problems of the conventional negative type liquid crystal display element and provides a liquid crystal display element that can obtain better contrast than the conventional one even under very bad environmental conditions such as external light irradiation. With the goal.

[Means for solving problems]

In order to solve the above-mentioned problems, in the present invention, a black coating is provided on the outside of each of the upper and lower polarizing plates attached to the outside of the upper and lower glass substrates, at locations that do not interfere with display. In particular, in the case of a transmitted light type liquid crystal display element having a light source, a white coating is further applied on the outside of the black coating on the light source side so that the light from the transmitted light source uniformly enters the display section.

[Effect]

By taking the above-mentioned measures, it is possible to prevent almost all harmful and useless external light from entering the display, and therefore it is possible to significantly prevent a decrease in contrast due to the incidence of external light. In addition, in the case of a transmitted-light type liquid crystal display element that has a light source, if a white coating is applied to the outer surface of the black coating on the light source side, the light irradiated there will be reflected (normally, the area around the light source has been placed on the display element side). The inside was surrounded by white-painted parts)
In the end, reflection is repeated many times on the light source side, approaching cavity radiation, and uniform incident light can be obtained on the display section.

Note that the black coating is applied to absorb light and not reflect it, so it is desirable that it not only be black but also be as matte as possible and not easily peeled off from the base (polarizing plate surface).

〔Example〕

FIG. 1 shows an example in which the present invention is applied to a transmitted light type liquid crystal display element having a light source, in which l is a glass substrate forming a liquid crystal cell, 2 is a polarizing plate, 3 is a black coating, and 4 is a white coating. It is. In this way, all areas that do not interfere with the display are coated with black to prevent outside light from entering the glass substrate, so the negative effects of outside light are suppressed and the contrast is improved compared to the prior art. In this example for a transmitted-light type liquid crystal display element, a white coating is further applied on the outside of the black coating on the light source side, which reduces light loss on the light source side and makes the brightness of the light incident on the display area uniform. approach.

In this example, the part on the light source side that is not coated with black is the part on the viewer's side that is not coated with black (display part).
The reason why it is slightly wider is so that it does not get in the way when the viewer views the display from a direction that is easy to view (generally not perpendicular to the display surface, but slightly tilted in °C).

It is better to make the area covered with black as wide as possible unless it interferes with viewing the display.

For example, in the case of a numeric display using 7 elements, in order to make the work easier, it is convenient not to apply black coating inside the area surrounded by 7 elements, even in areas where there are no display elements. Using photolithography technology that has been developed along with element manufacturing, it is also possible to apply a black coating to the inside surrounded by the seven elements.

〔Effect of the invention〕

As explained above, according to the present invention, it is possible to obtain a negative type liquid crystal display element that has better contrast and is easier to see than the conventional display even under harsh environments.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an example in which the present invention is implemented in a transmitted light type liquid crystal display element having a light source, and FIGS. 2(a) and (b) are diagrams showing an example of a conventional negative type liquid crystal display element. l-glass substrate, 2-polarizing plate, 3-black coating,
4-.-White coating.

Claims (1)

[Scope of Claims] 1. A liquid crystal display element that displays brightly on a black background, characterized in that a black coating is provided on the outside of each of the upper and lower polarizing plates at a portion that does not interfere with the display. 2. The liquid crystal display device according to claim 1, further comprising a white coating on the outside of the black coating on the light source side of the transmissive light type liquid crystal display device having a light source.