JPH08334760A - Liquid crystal display device - Google Patents

Abstract

PURPOSE: To prevent the transfer of the heat generated from a light source to liquid crystals and to eliminate unequal display by providing the light source of a back light with a heat insulating means. CONSTITUTION: A surface light source device 4 has a prism sheet 5 arranged behind a liquid crystal panel 1 of nearly the same size as the size of the liquid crystal panel 1, a diffusion sheet 6, an acrylic light transmission plate 7 and a base reflection plate 8. Further, the edge part of the light transmission plate 7 is provided with a reflector 9 in a cylindrical shape. A CCFL 10 of a tubular light source penetrates the space of the reflector formed to the cylindrical shape and this CCFL 10 is provided with an enclosure 11 of transparent glass as heat insulating means so as to enclose the CCFL in order to prevent the transfer of the heat generated from the CCFL 10 to the liquid crystal panel 1. The reflector 9 is suppressed by a fixture 12 and is provided with a frame 13 for combining various members.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a backlight of a liquid crystal display device, and more particularly to a means for preventing heat generated from a light source from being transmitted to liquid crystal.

[0002]

2. Description of the Related Art Conventionally, a backlight source used in a liquid crystal display device is a CCFL (Cold Cathod).
Although an e Fluorescent Lamp) is used, the heat generated from the CCFL is transmitted to the liquid crystal and affects the characteristics of the liquid crystal, resulting in uneven display.

To solve this problem, for example, Japanese Patent Application Laid-Open No. 63-80289 discloses means for preventing heat from the filament coil from being transmitted to the liquid crystal display device.

However, this structure has a problem in that the heat generated from the other parts of the light source cannot be blocked only by blocking the heat generated from the filament coil, and the display unevenness still occurs. .

[0005]

DISCLOSURE OF THE INVENTION As described above,
When a surface light source device is used as a backlight of a liquid crystal display device, heat generated from the light source is transmitted to the liquid crystal and affects the characteristics of the liquid crystal, which causes uneven display.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a liquid crystal display device which prevents heat generated from a light source from being transmitted to a liquid crystal and has no display unevenness.

[0007]

SUMMARY OF THE INVENTION The present invention provides a surface light source device including a liquid crystal panel in which liquid crystal is sandwiched between a pair of substrates provided with electrodes, and a light source which illuminates the liquid crystal panel from the rear surface and emits at least light source light. The liquid crystal display device having: and a heat insulating means for not transmitting heat generated from the light source to the liquid crystal.

[0008]

According to the present invention, by providing the light source of the backlight with the heat insulating means, it is possible to prevent the heat generated from the light source from being transferred to the liquid crystal and to obtain a liquid crystal display device having no display unevenness.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the liquid crystal display device according to the present invention will be described in detail below with reference to the drawings. (Embodiment 1) FIG. 1 schematically shows a cross-sectional view of a liquid crystal display device of this embodiment. In a liquid crystal display device, a liquid crystal is enclosed in two glass substrates provided with electrodes, a liquid crystal panel 1 provided with a polarizing plate outside the two glass substrates, and a PC (Print) for supplying a drive voltage to the liquid crystal panel 1. Ci
rCuit) plate 2, TAB (Tape Automated B) for electrically connecting the liquid crystal panel 1 and the PC plate 2
Onboard) -IC 3, and a surface light source device 4 arranged behind the liquid crystal panel 1 and illuminating the liquid crystal panel 1.

The surface light source device 4 is provided with a prism sheet 5, a diffusion sheet 6, an acrylic light guide plate 7 and a bottom reflector 8 which are substantially the same size as the liquid crystal panel 1 and are arranged behind the liquid crystal panel 1. Further, a reflector 9 is provided in a cylindrical shape at the edge portion of the light guide plate 7. Then, in the space of the reflector formed in the tubular shape, the CCFL of the tubular light source is
(Cold Cathode Fluorescent
The transparent glass envelope 11 serves as a heat insulating means in order to prevent the heat generated from the CCFL 10 from being transmitted to the liquid crystal panel 1.
It is provided so as to wrap L10.

Then, the reflector 9 is fixed by the fixing metal fitting 12.
Is suppressed, and a frame 13 for assembling various members is provided. In FIG. 2, the envelope 11 and the CCFL 1
0 shows an enlarged view of 0. The envelope 11 is sealed with only the lead wire 20 extending from the end of the CCFL 10 exposed to the outside, and the inside of the envelope 11 is evacuated.

A method of manufacturing the envelope 11 will be described below with reference to FIG. First, a CCFL with an outer diameter of about 2 mm
After making 10 by the conventional manufacturing method, CCFL10
The glass beads 30 are placed on one of the lead wires 20 extending from the end of the. The bead 30 is installed at a position about 2 to 3 mm away from the end of the CCFL 10.

Next, the CCFL 10 provided with the beads 30 is inserted into a pipe-shaped glass tube 31 having an outer diameter of about 5 mm,
The end portion 32 where the beads 30 are not provided is heated and sealed.

Here, the inside of the glass tube 31 is evacuated from the bead 30 side, and the unsealed end 33 of the glass tube 31 is heat-sealed in this state. CC in this way
A desired envelope can be formed on the outside of the FL 10.

In addition to the above method, CCFL10
There is also a method of bringing the ends of the envelope and the end of the envelope 11 close to each other and sealing them at the same time. According to this embodiment, it is possible to reduce display unevenness without transmitting heat generated from the CCFL 10 to the liquid crystal panel 1. In this embodiment, the envelope 1
Since the inside of 1 is a vacuum, the heat insulating effect is higher.

Further, by confining the heat generated by the CCFL 10 in the envelope 11, the CCFL 1 is activated at the time of starting.
The time it takes for 0 to warm can be shortened, and further, CCFL
The brightness of 10 is increased, and the same brightness as the conventional one can be generated with low power consumption.

The material of the envelope 11 is not limited to glass. Any material may be used as long as it has a smaller amount of transmitted infrared light than that of visible light, and the larger the difference in the amount of transmitted light, the more preferable. In addition, if colored glass is used for the envelope 11 or a color filter is provided, there is an effect that a portion that is conventionally displayed in white is colored.

Further, in the present embodiment, the inside of the envelope 11 is evacuated, but the same effect can be obtained if the gas inside is made lean even if the inside of the envelope 11 is not completely evacuated. (Embodiment 2) In this embodiment, as shown in FIG.
A film-shaped reflector 40 made of silver (Ag) is formed on the outer surface of 1. In this case, not only the outer surface but also the inner surface may be used. The reflector 40 may be attached in the form of a film, or may be directly applied or vapor-deposited on the envelope 11.

When the configuration of this embodiment is adopted, the envelope 11
It is also possible to make the shape in consideration of light reflection.
Conventionally, since a white or silver film was rolled into a reflector, there was a problem that sufficient light could not be reflected due to its positional accuracy and bending condition.However, according to the configuration of this embodiment, The reflector 4 is attached to the envelope 11.
Since 0 is provided, the position accuracy is greatly improved.

The above-mentioned (Example 1) and (Example 2) are side edge type surface light source devices in which CCFLs are provided at the edge portions of the light guide plate 7, but as shown in FIG. It is also applicable to a direct type surface light source device in which the CCFL 10 is arranged behind the liquid crystal panel.

[0021]

According to the present invention, by providing the means for not transmitting the heat of the light source to the liquid crystal, it is possible to reduce the display unevenness without changing the characteristic of the liquid crystal with respect to such a voltage. Further, since the light source is kept warm, the light source can be driven with low power consumption.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a liquid crystal display device in an example of the present invention.

FIG. 2 is a cross-sectional view showing a CCFL and an envelope according to an embodiment of the present invention.

FIG. 3 is a flowchart showing a manufacturing process of an envelope according to an embodiment of the present invention.

FIG. 4 is a sectional view showing an envelope and a reflector in an embodiment of the present invention.

FIG. 5 is a cross-sectional view of a liquid crystal display device including a direct type surface light source device according to an embodiment of the invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Liquid crystal panel 4 ... Surface light source device 7 ... Light guide plate 10 ... CCFL 11 ... Enclosure 40 ... Reflector

Claims (10)

[Claims] 1. A liquid crystal display device comprising: a liquid crystal panel in which liquid crystal is sandwiched between a pair of substrates provided with electrodes; and a surface light source device having a light source for illuminating the liquid crystal panel from the rear surface and emitting at least light source light. The liquid crystal display device according to claim 1, further comprising a heat insulating means for preventing heat generated from the light source from being transmitted to the liquid crystal. 2. The liquid crystal display device according to claim 1, wherein the heat insulating unit has a transparent portion that transmits the light from the light source. 3. The liquid crystal display device according to claim 1, wherein the surface light source device has a planar light guide plate that transmits the light source light, and the light source is provided at an end portion of the light guide plate. A liquid crystal display device characterized by the above. 4. The liquid crystal display device according to claim 1, wherein the light source includes a direct type surface light source device arranged behind the liquid crystal panel. 5. The liquid crystal display device according to claim 1, wherein the light source is a tubular light source, and the heat insulating means is a tubular shape surrounding an outer circumference of the tubular light source. 6. The liquid crystal display device according to claim 1, wherein the tubular heat insulating means encloses the tubular light source and is hermetically sealed, and the inside of the heat insulating means is a vacuum or gas inside thereof is A liquid crystal display device characterized by being in a dilute state. 7. The liquid crystal display device according to claim 1 or 2, wherein a reflector having a light reflecting effect is provided on an inner surface or an outer surface of the heat insulating means. 8. The liquid crystal display device according to claim 1, wherein the heat insulating unit is a glass tube. 9. The liquid crystal display device according to claim 1, wherein the heat insulating unit has a transmittance of light having a wavelength in the infrared region lower than that of light having a wavelength in the visible region. Display device. 10. The liquid crystal display device according to claim 1 or 2, wherein the heat insulating means is colored.