JPH11204084A - Electric discharge apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric discharge apparatus reaching a stable operation state within a short time by providing a heating means on an external face of a closed vessel sealding in a discharge gas, and heading the closed vessel during startup. SOLUTION: A transmissive front plate 10 consisting of soda glass or the like, for example, and an insulation substrate 20 and a side plate 30 consisting of soda glass or ceramic or the like are air-tightly stuck with a low melting point glass to constitute a flat closed container 1. Surfaces of a pair of parallel discharge electrodes 40 and 41 provided on an inner face of the front plate 10 are covered with a dielectric layer 50 formed by a thick film printing method or the like. A phosphor 60 is applied to an inner face of the insulating substrate 20, and discharge gas such as mercury or rare gas is sealed in a discharge space 70 in the closed vessel 1. A flat heating heater 80 is provided substantially all over the outer surface of the insulation plate 20. In the case of preheating with the heating heater 80, the rise time of luminance can be significantly reduced. Thereby, the rising characteristics of luminance is improved, and stability and uniformity is improved from the initial stage of lighting.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[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 device (discharge lamp) is also used.

FIG. 5 is a cross-sectional view of a conventional flat discharge device described in, for example, Japanese Patent Application Laid-Open No. 9-115483. As shown in the figure, a light-transmitting front plate 10 made of soda glass or the like, an insulating substrate 20 made of soda glass or ceramic or the like, and a side plate 30 are integrally hermetically sealed with, for example, low-melting glass (not shown). The flat closed container 1 is configured.

[0004] 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, and the surfaces of the discharge electrodes 40 and 41 are covered with a dielectric layer 50. A phosphor 60 is applied on the inner surface of the insulating substrate 20, and a discharge space 70 in the closed container 1 is a mercury and mixed gas such as argon or neon-argon as a starting gas, or xenon, krypton, or argon. ,helium,
A discharge gas of a rare gas such as neon is sealed.

[0005] In the flat discharge device of this configuration, a high-frequency voltage is applied between the discharge electrodes 40 and 41 to generate a discharge in the discharge space 70, and the ultraviolet light generated by the discharge excites the phosphor 60 to emit light. Then, light is radiated outside through the front plate 10.

[0006]

The brightness of the discharge device largely depends on the vapor pressure of the enclosed mercury, that is, the temperature of the discharge device. The conventional flat discharge device has a large heat capacity and requires a considerable amount of time to reach a certain operating temperature. For this reason, at the beginning of lighting, the rise of the luminance is slow, and it takes a considerable amount of time to reach a predetermined brightness. During that time, the discharge is unstable, causing uneven brightness and flickering. In addition, this phenomenon becomes more remarkable at a low temperature, and there is a problem that the starting voltage is increased, and in some cases, the light is not turned on. An object of the present invention is to solve the above-described problems, and an object of the present invention is to provide a discharge device that can reach a stable operation state in a short time.

[0007]

In order to achieve the above object, according to the present invention, a flat airtight container is formed by combining a light-transmitting front plate and an insulating substrate, and an inner surface of the front plate is formed on the inner surface of the front plate. Is provided with a pair of discharge electrodes parallel to each other, the surface of the discharge electrodes is covered with a dielectric layer, the inner surface of the insulating substrate is coated with a phosphor, and a discharge gas is sealed inside the closed container. In the discharge device described above, a heating means is provided on the outer surface of the closed vessel, and the closed vessel is heated at the time of starting.

In this case, the heating means is provided on the outer surface of the insulating substrate. Further, a resistance heater is used as the heating means. In addition, a flat heater is used on almost the entire surface of the insulating substrate. Further, a thick-film or thin-film heater is directly formed on the insulating substrate as the heating means. Further, a heating means is provided on the front plate. Further, a mechanism is provided for adjusting the temperature so that the temperature of the closed container becomes constant after the heating is started by supplying electricity to the heating means. In addition, a mechanism is provided for stopping the power supply after a certain time has elapsed or when the temperature has reached a certain temperature after the heating means is energized to start heating. 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.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional perspective view showing one embodiment of a flat discharge device according to the present invention. As shown in the figure, a translucent front plate 10 made of, for example, soda glass or the like, an insulating substrate 20 made of soda glass, ceramic, or the like, and a side plate 30.
Are hermetically sealed together with, for example, a low-melting glass (not shown) to form a flat closed container 1. Front panel 10
A pair of parallel discharge electrodes 40 and 41 are provided on the inner surface of the substrate. The surfaces of the discharge electrodes 40 and 41 are covered with a dielectric layer 50 provided by a thick film printing method or the like. A phosphor 60 is applied, and a discharge space 70 in the closed container 1 is filled with a discharge gas of mercury or a rare gas. On the outer surface of the insulating substrate 20, a flat heater 80 is provided on almost the entire surface of the insulating substrate 20.

As shown in FIG. 2, the driving method of the flat discharge device according to the present embodiment is, for example, a rectangular wave voltage V1 having a voltage 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. The flat heater 80 has a heating element 81 such as a nichrome wire embedded in an insulator such as ceramic, silicon rubber, or a heat-resistant film.
Is a lead wire for introducing electric power. Further, as the heater 80, a heater obtained by sintering a heating element in a flat plate shape or a tape-shaped heating element may be used.

FIG. 3 is a diagram showing the effect when the heater 80 according to the present invention is provided, and shows the relationship between the lighting time and the luminance. In the figure, a shows a change in luminance when the lamp is turned on at 26 ° C., and b shows a luminance change when the container 1 is turned on after being heated to 50 ° C. by a heater. The discharge device has the same structure as that shown in FIG. 1, and the insulating substrate 20 uses soda glass having a thickness of 3 mm.
The size of the light emitting surface is 110 mm × 88 mm, and the discharge space 70 is filled with mercury and argon at 8 kPa. Heater 80
Uses a nichrome wire and is not energized at the time of lighting.

As is apparent from FIG. 3, when the heater is preliminarily heated by the heater, the rise time of the luminance can be greatly reduced as compared with the case without the heater. For example, compared to the case where the conventional discharge device requires three minutes to reach 80% of the luminance in the stable operation state, the time can be reduced to 20 seconds by preheating with the heater. Also, according to the present invention, it was possible to shorten the luminance to 90% of the luminance in the stable operation state, compared to about 5 minutes according to the present invention, and to greatly improve the luminance rising characteristic. Further, there is an advantage that stability and uniformity are improved from the beginning of lighting.

FIG. 4 is a plan view showing another embodiment of the discharge device according to the present invention. The discharge device according to this embodiment is provided with a heater 82 made of, for example, a resistor of a nickel alloy by a thick film printing or a thin film process on the surface of the insulating substrate 20, and the effect is the same as described above. . Heater 8
2 may be formed on the insulating substrate 20 in advance and assembled as an integral part, or may be formed after assembling the closed container 1.

As another embodiment of the present invention, the outer surface of the flat heater 80 in the discharge device shown in FIG. 1 is preferably made of a material having good thermal conductivity such as aluminum.
By using this configuration, the effect of the heat equalizing plate is added to the heating means, so that the entire insulating substrate 20 is heated to a uniform temperature, and there is an advantage that stability and luminance uniformity are further improved. Further, as another embodiment of the present invention, a heating means may be provided on the front plate. In the case of this configuration, since the front plate 10 is a light-emitting surface, a light-transmitting material such as an ITO film or a Nesa film may be used for the heater, or a thin linear heater may be used so as to reduce the emission luminance little. desirable. Further, the heating means may be provided on both surfaces of the front plate 10 and the insulating substrate 20.

In the discharge device provided with the heating means, for example, in order to improve the starting characteristics at a low temperature, the heater 80 is energized at the time of starting or before starting to start heating, and then the closed container is started. Improve the brightness start-up characteristic and discharge stability at low temperature start-up by providing a mechanism such as a timer that stops power supply when 1 reaches a certain temperature or turns off power after a certain time after power supply. And wasteful power consumption can be avoided. Providing a temperature adjusting mechanism for controlling the voltage and current of the heater 80 so that the temperature of the sealed container 1 is maintained at a constant temperature is also effective in improving the characteristics of the discharge device. By adjusting the temperature of the closed vessel 1, the discharge device can be maintained at a temperature that is optimal for high brightness and high efficiency operation. In the discharge device according to the present embodiment, the temperature of the sealed container is 40 to 60 ° C., and the brightness and the efficiency are maximized.
By performing temperature adjustment so as to maintain this temperature, a discharge device that always operates with high luminance and high efficiency can be obtained.

As described above in detail, the discharge device according to the present invention reaches a stable state in a short time after lighting, so that high-luminance, high-efficiency, stable and uniform display can be performed from the beginning of lighting. . In addition, a backlight having excellent startability can be obtained even at a low temperature.

[0017]

According to the discharge device of the present invention, a heater for heating is provided on the outer surface of the discharge device, and the discharge device is heated at the time of starting, so that a certain operating temperature is reached in a short time after lighting. For this reason, the rise of the luminance is accelerated, and a display with high luminance and good stability and uniformity from the initial lighting can be performed.
Further, even at a low temperature, a rise in the starting voltage is small, and a backlight having excellent starting characteristics can be obtained. Furthermore, after heating starts,
Turning off the power supply when the temperature reaches a certain time or a certain temperature also has an effect of reducing power consumption. In addition, by adjusting the temperature of the discharge device, there is also an effect that the temperature can be maintained at an optimum temperature for high brightness and high efficiency operation.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a cross section of a discharge device according to the present invention.

FIG. 2 is a characteristic diagram showing a driving voltage waveform of the discharge device of FIG.

FIG. 3 is a characteristic diagram showing a relationship between luminance and operation time in FIG. 1;

FIG. 4 is a plan view showing another embodiment of the discharge device according to the present invention.

FIG. 5 is a sectional view showing a conventional discharge device.

[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 waveform, 50: dielectric layer, 60: phosphor, 70: discharge space,
80, 81, 82... Heater, 90, 91.

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Masashi Tsuchiya 888 Fujibashi, Ome-shi, Tokyo Inside the Heater Lighting Division of Hitachi, Ltd.

Claims (10)

[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. A discharge device in which 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, wherein a heating unit is provided on an outer surface of the closed container. apparatus. 2. A discharge device according to claim 1, wherein heating means by a resistance heater is provided on an outer surface of said insulating substrate. 3. The discharge device according to claim 1, wherein a flat heater is provided on substantially the entire surface of said insulating substrate. 4. The discharge device according to claim 1, wherein a thick-film or thin-film heater is directly formed on said insulating substrate as said heating means. 5. The heating means provided on the insulating substrate has an effect of a heat equalizing plate.
The discharge device according to any one of the above items. 6. The discharge device according to claim 1, wherein a heating means is provided on the front plate. 7. A mechanism according to claim 1, further comprising a mechanism for adjusting the temperature so that the temperature of the closed container becomes constant after the heating is started by supplying electricity to the heating means. The discharge device according to any of the above items. 8. A mechanism according to claim 1, further comprising a mechanism for stopping the current supply after a predetermined time has elapsed or a predetermined temperature has been reached after the heating means is energized to start heating. The discharge device according to any of the above items. 9. An illuminating device configured to illuminate using the discharge device according to any one of claims 1 to 8. 10. A liquid crystal display device using the discharge device according to claim 1 as a backlight.