JPH0426821A - Backlight for non-emission type display element - Google Patents

Abstract

PURPOSE:To prevent brightness from lowering even though the thickness of a light transmission body is made thin by providing a convex lens between a light source and the side part of the light transmission body. CONSTITUTION:The convex lens 2 is provided between a cold cathode tube 1 and the side part of the light transmission body 4 and a concave lens 3 is provided between the lens 2 and the side part of the light transmission body 4. Therefore, light emitted from the cold cathode tube 1 is converged by the lens 2, turned into the collimated beam of light by the lens 3 and made incident from the side part of the light transmission body 4. Thus, the incident quantity on the light transmission body 4 from the cold cathode tube 1 is not reduced even though the thickness of the light transmission body 4 is made thin, so that the brightness is not lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a backlight for a non-emissive display element such as a liquid crystal display element.

[Conventional technology]

Backlight of conventional liquid crystal display element (Japanese Patent Application Laid-Open No. 55-40
No. 66), a light source is located near the side of the light guide.

[Problem to be Solved by the Invention 1] In the backlight of such a liquid crystal display element, when the thickness of the light guide is reduced, the amount of light incident on the light guide from the light source is reduced, and the brightness is reduced.

The second invention was made to solve the above-mentioned problem, and its purpose is to provide a backlight for a non-emissive display element in which the brightness does not decrease even if the thickness of the light guide is reduced. shall be.

[Means for Solving the Problems] In order to achieve this object, the present invention provides a backlight for a non-emissive display element having a light source and a light guide whose side portion is located near the light source. A convex lens is provided between the light source and a side portion of the light guide.

[Effect]

In the backlight of this non-emissive display element, even if the thickness of the light guide is reduced to 7", the amount of light incident on the light guide from the light source will not decrease.

[Example] FIG. 1 is a plan view showing a backlight of a liquid crystal display element according to the present invention, and FIG. 2 is a front view thereof. In the figure, 1 is a cold cathode tube, 4 is a light guide whose side portion is located near the cold cathode tube 1, and the light guide 4 is made of resin such as acrylic or polycarbonate. Reference numeral 5 denotes a reflecting plate provided on the opposite side of the light-emitting surface of the light guide 4, and the reflecting plate 5 is made of a sheet of aluminum, polyester, or the like. Reference numeral 6 denotes a diffuser plate provided on the light emitting surface side of the light guide 4, and the diffuser plate 6 is made of a white sheet of acrylic, polyester, or the like. Reference numeral 7 denotes a reflector plate provided near the cold cathode tube l, and the reflector plate 7 is made of aluminum.

2 is a convex lens provided between the cold cathode tube 1 and the side of the light guide 4, and 3 is a concave lens provided between the convex lens 2 and the side of the light guide 4.

In the backlight of such a liquid crystal display element, as shown in FIG. Incident from the side. And the light guide 4
The light incident on the inside is reflected by the light guide 4 and the reflection plate 5 into the third
The light is diffused upward from the plane of the drawing, and further diffused by the diffusion plate 6.

In the backlight of this liquid crystal display element, the light emitted from the cold cathode tube 1 is narrowed down by the convex lens 2 and enters from the side of the light guide 4, so even if the thickness of the light guide 4 is made small. Since the amount of light incident on the light guide 4 from the cold cathode tube 1 does not decrease, the brightness does not decrease. Further, since the light made parallel by the concave lens 3 enters from the side of the light guide 4, the brightness of the light emitting surface becomes uniform.

In the above embodiment, the cold cathode tube 1 is used as a light source, but other light sources may be used.

〔Effect of the invention〕

As explained above, in the backlight of a non-emissive display element according to the present invention, even if the thickness of the light guide is reduced, the amount of incident light from the light source does not decrease, so the brightness decreases. As described above, the effects of this invention are remarkable.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing a backlight of a liquid crystal display element according to the present invention, FIG. 2 is a front view, and FIG.
FIG. 3 is an explanatory diagram of the operation of the backlight of the liquid crystal display element shown in FIG. 2; l... Cold cathode plate 2... Convex lens 4... Light guide plate Figure 2 Figure 3

Claims (1)

[Claims] 1. In the backlight of a non-emissive display element having a light source and a light guide whose side portion is located near the light source, a convex lens is provided between the light source and the side portion of the light guide. A backlight for a non-emissive display element characterized by: