JPH03204618A - Back light device - Google Patents

Abstract

PURPOSE:To reduce a temperature rise of the tube end part of a cathode discharge tube by providing a heat radiation part which is arranged outside a case and a heat radiation plate which extends from the heat radiation part into the case and has a holding part for holding the tube end part of the cathode discharge tube. CONSTITUTION:This back light device is provided with the heat radiation part 4a arranged outside the case 1 wherein the cathode discharge tube 3 and a photoconductor 2 are arranged and the heat radiation plate 4 which extends from the heat radiation part 4a into the case 1 and has the holding part 4b for holding the tube end part of the cathode discharge tube 3. Then the light emitted by the cold cathode discharge tube 3 passes through the photoconductor 2 and a diffusion plate 6 to irradiate a liquid crystal display element 7 as a uniform face light source. In such a case, the heat of the tube end part of the cold cathode discharge tube 3 is conducted to the holding part 4b through resin 5 and radiated from the discharge part 4a to the outside. Consequently, the temperature rise of the tube end part of the cathode discharge tube can be suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a backlight device that converts a line light source into a surface light source.

[Conventional technology]

2. Description of the Related Art Conventionally, one known backlight device for converting a linear light source into a surface light source is one that guides light from, for example, a cold cathode discharge tube to a light guide to create a uniform surface light source.

Note that, for example, Japanese Patent Application Laid-Open No. 13202/1983 is related to this food device.

By the way, a cold cathode discharge tube generates heat by emitting light. In particular, the tube end (electrode part) of a cold cathode discharge tube is 80~
The temperature will be around 90℃.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the heat generation of the cold cathode discharge tube. Therefore, when the backlight device is used as a light emitting source for a liquid crystal display device, the temperature of the liquid crystal display element increases due to the radiant heat of the cold cathode discharge tube. In other words, a temperature difference occurs between the center of the liquid crystal display element and the peripheral area near the end of the cold cathode discharge tube, and when the liquid crystal display is turned on, the voltage changes due to the change in the threshold value, causing display unevenness. There was a problem.

SUMMARY OF THE INVENTION An object of the present invention is to provide a backlight device that can reduce the temperature rise at the end of a cathode discharge tube.

[Means to solve the problem]

The purpose of the above is to provide a heat dissipation section installed on the outside of the case in which the cathode discharge tube and the light guide are disposed inside the case, and a holder that extends from this heat dissipation section to the inside of the case to hold the tube end of the cathode discharge tube. This is achieved by providing a heat sink having a portion.

[Effect]

The heat at the tube end of the cathode discharge tube is transferred to the holding part of the heat sink,
Heat is radiated to the outside through the heat radiating portion of the heat sink located on the outside of the case.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

Cold cathode discharge tubes 3 are disposed on opposite sides of the light guide 2 disposed in the case 1, and cold cathode discharge tubes 3 are disposed on opposite sides of the light guide 2 disposed in the case 1.
The part of case 1 that holds the tube end of
is formed. In addition, a heat sink 4 is provided to dissipate the heat of the cold cathode discharge tube 3, and the heat sink 4 is connected to the case l.
The cold cathode discharge tube 3 is made up of a heat dissipation section 4a disposed on the outside of the cold cathode discharge tube 3, and a holding section 4b that extends from the heat dissipation section 4a toward the inside of the case l and holds the tube end of the cold cathode discharge tube 3. The cold cathode discharge tube 3 is joined to the holding part 4bK of the heat sink 4 by the resin 5.A diffusion plate 6 is disposed above the light guide 2, and the upper leg of this diffusion plate 6 is A liquid crystal display element 7 is provided. Note that 8 indicates an upper cover.

Next, the effect will be explained. The light emitted from the cold cathode discharge tube 3 passes through the light guide 2 and the diffuser plate 6 and becomes a uniform surface light source, and is irradiated onto the liquid crystal display element 7 . In this case, the heat at the tube end of the cold cathode discharge tube 3 is retained through the resin 5 i4b
The heat is transmitted to the outside through the heat radiating section 4a. Therefore, the temperature at the tube end of the cold cathode discharge tube 3 can be suppressed to about 60°C, and the temperature difference between the peripheral part and the center part of the liquid crystal display element 7 becomes small, and when the liquid crystal display element 70 is turned on, f Display unevenness will disappear.

Note that although the above embodiment has been described using the cold cathode discharge tube 3, a hot cathode discharge tube may also be used.

〔Effect of the invention〕

According to the present invention, the heat generated at the tube end of the cathode discharge tube is radiated by the heat sink, so that the temperature rise at the tube end of the cathode discharge tube is suppressed. Therefore, when used in a liquid crystal display device, a uniform display without display unevenness can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment in which a backlight device according to the present invention is applied to a liquid crystal display device, and FIG. 2 is a plan view of the bank light device of FIG. 1. ■... Case, 2... Light guide, 3... Cold cathode discharge tube, 4... Heat sink, 4a... Heat sink,
4b... Holding part. 1st vA 2nd figure 4: Hozenkyumen 4a: Thermal part 4b: I1L↑) House

Claims (1)

[Claims] 1. In a backlight device equipped with a cathode discharge tube, a light guide that guides light from the cathode discharge tube, and a case in which the cathode discharge tube and light guide are disposed inside, 1. A backlight device comprising: a heat dissipation plate having a heat dissipation section; and a holding section extending from the heat dissipation section to the inside of the case and holding an end of a cathode discharge tube.