JP2000011958A - Plate-type light source and liquid crystal display device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To have a light source uniformly discharge over a long time period by providing a pair of discharge electrodes on the inner surface of a light transmitting front plate of a flat closed container, and providing a radiating means on the outer surface of the front plate so as to face opposite to the electrodes. SOLUTION: A light transmitting front plate 10 made of soda glass or the like, an insulating substrate 20 made of ceramics or the like and a side plate 30 are integrally sealed air tightly to form a flat closed container 1. A pair of discharge electrodes 40, 41 parallel to each other are provided on the inner surface of the front plate 10, and the surfaces thereof are covered with dielectric substances 50, 51. A fluorescent body 60 is applied to the inner surface of the insulating substrate 20, and mercury and a mixed gas such as argon gas, neon- argon or the like are sealed in a discharge space 70 in the closed container 1. In this arrangement, radiating foils 80, 81 made of a metal such as copper, aluminum or the like are provided opposite to the discharge electrodes 40, 41 on the outer surface of the front plate 10.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat light source which emits light in a plane, and more particularly to a flat panel light source which uses a display element such as a liquid crystal panel which requires a backlight, such as a television, a game machine, a car navigation system and the like. The present invention relates to a flat light source suitable for use in an OA device such as an information video device or a word processor, or a display system incorporating a light source, a lighting device using the flat light source, and a liquid crystal display device.

[0002]

2. Description of the Related Art Liquid crystal panels are widely used as various types of information video displays such as personal computers and televisions because of their thinness, lightness and low power consumption. A backlight that supplies light from the back of the liquid crystal panel is required. The backlight generally used is mainly a combination of a small-diameter fluorescent lamp and an acrylic resin light guide, but a flat discharge lamp is also used.

FIG. 5 is a cross-sectional view of a conventional flat light source described in, for example, Japanese Patent Application Laid-Open No. 9-115483. As shown in the figure, a translucent front plate 10 made of soda glass or the like.
And an insulating substrate 20 made of soda glass, ceramic, or the like.
The side plate 30 and the side plate 30 are integrally hermetically sealed with, for example, low-melting glass (not shown) to form a flat closed container 1. A pair of discharge electrodes 40 and 41 parallel to each other are provided on the inner surface of the front plate 10 serving as a light emitting surface.
The surfaces of 0 and 41 are covered with a dielectric layer 52. Also,
The phosphor 60 is applied to the inner surface of the insulating substrate 20,
The discharge space 70 in the sealed container 1 is filled with mercury and a mixed gas such as argon or neon-argon as a starting gas, or a rare gas such as xenon, krypton, argon, helium, or neon.

[0004] The flat light source according to the present configuration has a discharge electrode 4.
By applying a high-frequency voltage between 0 and 41, a discharge is generated in the discharge space 70, and the phosphor 60 is excited by the ultraviolet rays generated by the discharge to emit light, and the light is emitted to the outside through the front plate 10.

[0005]

The conventional flat light source is
Due to the energy loss of the electrode portion due to the discharge, the temperature of the electrode portion increased, and the temperature of the dielectric layer covering the electrode also increased considerably. For this reason, the dielectric strength of the dielectric layer is weakened, and in some cases, dielectric breakdown occurs in the dielectric layer, and there is a problem that discharge is concentrated at one place and the discharge is not uniform.

Further, the temperature of the electrodes on the front panel and the vicinity thereof become higher than that of the central part due to the rise in the temperature of the electrode parts. Therefore, when incorporated in a liquid crystal device, the temperature of the liquid crystal near the electrode parts becomes high, resulting in uneven brightness. In addition, there is a problem that color unevenness or the like occurs or an operation failure occurs.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and when uniform discharge is performed for a long time and used in combination with a liquid crystal, it is possible to prevent the occurrence of uneven brightness, uneven color and malfunction. An object of the present invention is to provide a flat light source.

[0008]

The flat light source according to the present invention comprises:
Combining a light-transmitting front plate and an insulating substrate to form a flat closed container, providing at least a pair of discharge electrodes on the inner surface of the front plate, and providing a dielectric layer covering the surface of the discharge electrodes Applying a phosphor to the inner surface of the closed container,
In the flat light source in which a discharge gas is sealed in the closed container, a heat radiating means is provided on an outer surface of the front plate.

Further, the heat radiating means is provided on the outer surface of the front plate and opposed to the discharge electrodes. In this case, an insulating material or a metal foil having good heat conductivity is used as the heat radiation means. Further, irregularities are provided on the surface of the heat radiating means.

[0010] Further, the lighting device is configured to illuminate using the above-described discharge device. Further, the above-described discharge device is used as a backlight in a liquid crystal display device.

[0011]

FIG. 1 is a sectional view showing an embodiment of a flat light source according to the present invention. As shown in the figure, a translucent front plate 10 made of, for example, soda glass, an insulating substrate 20 made of soda glass, ceramic, or the like, and a side plate 30 are integrally hermetically sealed with, for example, low-melting glass (not shown). Thus, a flat closed container 1 is formed. A pair of discharge electrodes 40 and 41 parallel to each other are provided on the inner surface of the front plate 10, and the surfaces of the discharge electrodes 40 and 41 are respectively covered with dielectric layers 50 and 51 provided by a thick film printing method or the like. I have. By printing the dielectric layer only on the discharge electrodes, the transmittance of the front plate 10 increases, and the light extraction efficiency can be improved. On the outer surface of the front plate 10, heat dissipating foils 80 and 81 made of a metal such as copper or aluminum are provided so as to face the discharge electrodes. A phosphor 60 is applied to the inner surface of the insulating substrate 20, and a mixed gas such as mercury and a rare gas such as argon or neon-argon is sealed in the discharge space 70 in the sealed container 1.

As shown in FIG. 2, the driving method of the flat discharge device according to the present embodiment is, for example, as shown in FIG. Are applied, and 46 rectangular wave voltages V2 having a half-cycle phase shift are applied. By using such a driving method, a discharge is generated in the discharge space 70, and the phosphor 60 is excited by the ultraviolet rays generated by the discharge to emit light, and the light is emitted to the outside through the front plate 10.

According to the flat type light source of the present invention, the heat radiation foils 80 and 81 provided opposite the discharge electrodes 40 and 41 dissipate the heat from the electrode portions, and the temperature of the dielectric layers 50 and 51 covering the electrodes is reduced. . The dielectric strength of a dielectric depends on the temperature, and the dielectric strength decreases exponentially with an increase in temperature. Therefore,
Due to the heat radiation effect of the heat radiation foil provided on the front plate, the temperature of the dielectric layer can be kept low and the dielectric strength improves, so dielectric breakdown of the dielectric layer can be prevented and uniform and stable discharge can be obtained. Can be

FIG. 3 is a partial sectional perspective view showing another flat type light source according to the present invention. The flat light source according to the present embodiment includes:
As shown in the figure, a heat-dissipating foil 82 is provided on a portion of the front plate other than the light-emitting region. In this flat light source, since the area of the heat radiating foil is large, the heat radiating effect is large, the temperature on the electrode can be further reduced, and stable and uniform discharge can be obtained for a long time.

FIG. 4 is a partial sectional view of still another flat light source according to the present invention. In this embodiment, the heat radiation foils 80 and 81 of the flat light source shown in FIG. By providing irregularities on the surface of the heat dissipation foil, the surface area is increased, the heat dissipation efficiency of the heat dissipation foil is improved, the temperature on the electrode can be further reduced, and stable and uniform discharge for a long time is achieved.
A long-life flat light source can be obtained.

In the above-described embodiment, a metal is used for the heat radiation foil, but an insulating material having good heat conductivity may be used.

As described in detail above, when the flat light source of the present invention is used in, for example, an illuminating device, an illuminating device which eliminates the concentration of discharge and stably emits light uniformly for a long time can be obtained.

When the flat light source of the present invention is used in, for example, a liquid crystal display device, a long-life backlight that emits light uniformly can be obtained. Further, since the temperature of the front plate is kept constant by radiating heat from the electrode portion by the heat radiating foil, the temperature gradient of the liquid crystal is also eliminated, and the occurrence of luminance unevenness, color unevenness and operation failure can be prevented.

[0019]

In the flat light source according to the present invention, the temperature of the dielectric layer can be reduced by providing the heat radiating means on the outer surface of the front plate, and the concentration of electric discharge due to dielectric breakdown of the dielectric layer is eliminated.
It emits light uniformly and stably for a long time.

When the flat light source of the present invention is used in, for example, a liquid crystal display device, there is an effect that a long-life backlight that emits light uniformly can be obtained. Furthermore, since the electrode portion is radiated by the heat radiating foil, the temperature of the front plate becomes constant, so that the temperature gradient of the liquid crystal is eliminated, and there is an effect that occurrence of luminance unevenness, color unevenness, and operation failure can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a flat light source according to an embodiment of the present invention.

FIG. 2 is a drive voltage waveform diagram of a flat light source.

FIG. 3 is a sectional perspective view showing still another embodiment of the flat light source according to the present invention.

FIG. 4 is a partial sectional view showing still another embodiment of the flat light source according to the present invention.

FIG. 5 is a sectional view showing a conventional flat light source.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Closed container, 10 ... Front plate, 20 ... Insulating substrate, 30 ...
Side plates, 40, 41 ... discharge electrodes, 45, 46 ... drive voltage waveforms, 50, 51, 52 ... dielectrics, 60, 61 ... phosphors,
70: discharge space, 80, 81, 82: heat dissipation foil.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H091 FA41Z FA43Z GA07 GA11 LA04 LA16 LA18 5C039 AA02 5C043 AA04 AA05 AA09 BB04 CC08 CD08 DD03 EA01 EA09 5G435 AA14 BB12 BB15 EE26 EE29 GG25 GG44 HH06 LL16 LL12

Claims (6)

[Claims] A flat closed container is formed by combining a light-transmitting front plate and an insulating substrate, and at least one pair of discharge electrodes is provided on an inner surface of the front plate, and the surface of the discharge electrodes is covered. In a flat light source, a dielectric layer is provided, a phosphor is applied to an inner surface of the closed container, and a discharge gas is sealed in the closed container, and a heat radiating unit is provided on an outer surface of the front plate. Flat light source. 2. A flat closed container is formed by combining a light-transmitting front plate and an insulating substrate, and at least one pair of discharge electrodes is provided on an inner surface of the front plate, and the surface of the discharge electrodes is covered. In a flat light source having a dielectric layer provided thereon, a phosphor applied to the inner surface of the closed container, and a discharge gas sealed in the closed container, heat radiating means is provided on the outer surface of the front plate and opposed to the discharge electrode. A flat light source characterized by comprising: 3. The flat light source according to claim 1, wherein an insulating material or a metal foil having good heat conductivity is used as said heat radiating means. 4. The flat type light source according to claim 1, wherein the heat radiating means has a surface with irregularities. 5. An illuminating device configured to illuminate using the discharge device according to claim 1. Description: 6. A liquid crystal display device using the discharge device according to claim 1 as a backlight.