JPH11307060A - Noble gas discharge lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high brightness and long life back light with less characteristic variation against atmospheric temperature, by installing a cylindrical container of a dielectric having a light transmitting property in which a phosphor layer is formed on the inner surface, an outer electrode of a transparent conductive film on the outside of the container, an inner electrode of a conductor whose surface is covered with a dielectric layer on the inside of the container, and sealing a noble gas in the container. SOLUTION: A translucent glass bulb 10 made of soda glass for example has an outer electrode 20 made of a transparent conductive film such as an ITO film in the whole periphery of the outer surface, and the inner surface of the glass bulb 10 is covered with a protecting film 60 made of MgO for example, and furthermore coated with a phosphor 40. An inner electrode 30 is installed on the inside of the glass bulb 10. The inner electrode 30 is formed in such a way that a dielectric layer 50 is formed on the surface of a metal conductor 31 made of Dumet wire for example, the protecting layer 60 is formed thereon, and the phosphor 40 is applied to the protecting layer 60. Sputtering of the electrode can be reduced even if discharge current is increased to heighten brightness.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp, in particular, to a display device such as a liquid crystal panel, for example, a backlight for an information visual equipment such as a television, a game machine or a car navigation system, or an OA equipment such as a word processor. The present invention relates to a discharge lamp, an illumination device using the discharge lamp, and a liquid crystal display device in an information device such as a facsimile, a copying machine, 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 flat light emission backlight that supplies light from the back of the liquid crystal panel is required. A cold cathode fluorescent lamp in which mercury and a rare gas are sealed is mainly used as a light source for the backlight, but an external electrode type discharge lamp is also used in a fluorescent lamp in which xenon is sealed or a copying machine.

FIG. 4 is a cross-sectional view of a conventional external electrode type discharge lamp described in, for example, Japanese Patent Publication No. 3-30259.
As shown in the figure, 1 is a discharge lamp, 10 is a glass bulb made of soda glass or the like, and a phosphor 40 is applied to the inner surface thereof,
A rare gas such as xenon is sealed inside. An external electrode 20 made of a transparent conductive film such as ITO is formed on the outer periphery of the glass bulb 10, and a metal internal electrode 30 is provided in the glass bulb 10 over substantially the entire length of the bulb.

[0004] In the discharge lamp according to this configuration, a rare gas discharge is generated in almost the entire area of the glass bulb 10 by applying an AC voltage between the electrodes 20 and 30, and the phosphor 40 is excited by ultraviolet rays generated by the discharge. Light is emitted from the discharge lamp 1.

[0005]

The conventional cold-cathode fluorescent lamp excites and emits a phosphor by ultraviolet rays generated by mercury discharge, and thus has a feature of high brightness and high efficiency, and is widely used as a normal backlight. Have been. However, since mercury is used, there is a problem in that the temperature characteristics, particularly at low temperatures, a significant decrease in luminance and a rise in starting voltage occur, resulting in a short life.

[0006] To improve such temperature characteristics, for example, a rare gas fluorescent lamp in which xenon is sealed as described above has been developed. However, when the discharge current is increased in order to obtain high luminance, a metal internal electrode is formed. There is a problem that the film is sputtered and adheres to the phosphor to cause a decrease in luminance, resulting in a short life.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a rare gas discharge lamp having high luminance and long life.

[0008]

According to the present invention, there is provided a cylindrical container which is a translucent dielectric having a phosphor layer formed on an inner surface thereof and a transparent conductive film formed on an outer surface of the container. A discharge lamp is used which has an external electrode and an internal electrode made of a conductor provided on the inside of the container and covered with a dielectric layer, and in which a rare gas is sealed in the container.

A mesh-shaped conductor is used as the external electrode. In addition, a metal foil or sheet having an opening, a vapor-deposited metal, or the like is used as the external electrode. Further, as the internal electrode, a dielectric pipe made of a thin glass tube or the like provided with a conductor is used. Further, a phosphor layer is formed on the surface of the dielectric layer of the internal electrode. Further, the inner surface of the cylindrical container as the dielectric and the surface of the dielectric layer of the internal electrode are covered with a protective layer. In addition, a rare gas such as xenon or krypton or a mixture of these rare gases is used as the sealing gas.

In this case, a sine wave, a rectangular wave, a triangular wave, or a pulse voltage is applied between the external electrode and the internal electrode to cause an AC high frequency discharge. The surface of the external electrode is covered with a light-transmitting insulator. In a lighting device or an information device, illumination is performed using the rare gas discharge lamp described above. In the liquid crystal display device, the rare gas discharge lamp is used as a backlight.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view in the tube axis direction showing one embodiment of a rare gas discharge lamp according to the present invention. As shown in the figure, 1
Is a rare gas discharge lamp, and a translucent glass bulb 10 made of, for example, soda glass or borosilicate glass has an external electrode 20 made of, for example, a transparent conductive film such as an ITO film or a Nesa film formed all around the outer surface. The inner surface of the glass bulb 10 has a protective layer 6 made of, for example, MgO, SiO ₂ , Al ₂ O ₃ or the like.
0, and a phosphor 40 is further applied thereon. An internal electrode 30 is provided inside the glass bulb 10 along its axial direction. For the internal electrode 30, a dielectric layer 50 such as glass is formed on the surface of a metal conductor 31 made of, for example, a dumet wire, a protective layer 60 is provided on the surface, and a phosphor 40 is applied. A rare gas such as xenon or krypton as a discharge gas is enclosed in the glass bulb 10 alone or as a mixture.

The lighting method of the rare gas discharge lamp according to the present embodiment is such that a rectangular wave, a sine wave, a triangular wave or a pulse voltage of several kHz to several MHz is applied between the external electrode 20 and the internal electrode 30 to apply an AC electric field type. A discharge is generated, and the phosphor 40 is excited by the ultraviolet light generated by the discharge, so that almost the entire area of the discharge tube 1 emits light with uniform luminance, and the light is emitted to the outside through the glass bulb 10.

In the rare gas discharge lamp according to the present invention, the electric discharge is performed through the glass bulb 10 and the dielectric layer 50 of the internal electrode 30, so that the electric current is limited by the dielectric and the glow discharge does not develop into an arc discharge. Further, the discharge does not concentrate on a specific place, and the discharge is generated from the entire inner surface of the glass bulb 10 facing the external electrode 20. Since the current flows immediately after the polarity of the applied voltage is inverted, a pulse-like current flows.

As described above, in the rare gas discharge lamp according to the present invention, since the metal is not exposed to the discharge space in both electrodes, spattering of the electrodes can be reduced even if the discharge current is increased for higher luminance. Further, by forming a protective layer of MgO or the like on the dielectric layer, spatter can be further reduced, and the stability of discharge is greatly improved. Thus, a long-life rare gas discharge lamp with high luminance and little luminance degradation can be obtained. Further, in addition to the improvement of the luminance maintenance ratio, there is an effect that the discharge becomes stable and the change in the electric characteristics can be reduced. When the rare gas discharge lamp according to the present invention is used as, for example, a light source for a backlight of a liquid crystal display device, a backlight having high luminance and long life can be obtained.

In the above embodiment, the external electrode 20 is I
Although a transparent electrode such as TO was used, the present invention is not limited to this. For example, a mesh-shaped metal is formed into a cylindrical shape and covered on the glass bulb 10, or a thick-film or thin-film conductor is formed on the glass bulb 10 in a mesh-shaped pattern. Or you may. The external electrode 20 may have any configuration as long as the external electrode 20 can be effectively taken out so as not to reduce the light emission of the discharge lamp 1.

Also, in the rare gas discharge lamp, the surface of the external electrode 20 is covered with a light-transmitting insulator (not shown) such as PET to prevent a short circuit around the discharge lamp or the lighting circuit. Or electric shock can be prevented to improve safety.

Although the terminal portion of the internal electrode 30 extends from both sides of the glass bulb 10 in the above embodiment, it may be provided on only one side.

FIG. 2 is a partial sectional perspective view showing another embodiment of the rare gas discharge lamp according to the present invention. The discharge lamp 1 according to the present embodiment uses a metal conductor made of a metal foil or sheet having an opening, a vapor-deposited metal, or the like as the external electrode 21, and does not have a protective layer. This is the same as the embodiment of FIG. The rare gas discharge lamp according to the present embodiment has the same effects as described above, and uses a feature that the luminance change is small with respect to the change of the ambient temperature and the luminance rises quickly, so that information of a copier, a facsimile, an image reader, etc. can be used. It is good to use for equipment.

FIG. 3 is a partial sectional view showing another embodiment of the rare gas discharge lamp according to the present invention. The rare gas discharge lamp according to the present embodiment uses, for example, a thin glass tube 70 as a dielectric layer, in which a conductive layer 80 is provided, as the internal electrode 30.
Used as Alternatively, the internal electrode can be easily formed by passing a metal rod through a glass tube. The effect of the rare gas discharge lamp according to the present embodiment is the same as described above.

As described above, in the rare gas discharge lamp according to the present invention, the surface of the discharge electrode is covered with the dielectric layer.
Since the metal is not exposed to the discharge space, spattering of the electrodes can be reduced even if the discharge current is increased to increase the luminance, so that a rare gas discharge lamp with high luminance and little deterioration in luminance can be obtained.

[0021]

According to the rare gas discharge lamp of the present invention, even if the discharge current is increased to increase the brightness, the sputter of the electrode can be greatly reduced, and the discharge stability is improved. Therefore, there is an effect that a long-life rare gas discharge lamp with high luminance and little luminance degradation can be obtained. In addition, there is an effect that the discharge becomes stable and the change in electrical characteristics can be reduced. If the rare gas discharge lamp according to the present invention is used for a backlight light source of a liquid crystal display device, for example,
A backlight having high brightness and long life is obtained with little change in characteristics with respect to a change in ambient temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a rare gas discharge lamp according to the present invention.

FIG. 2 is a sectional perspective view showing another embodiment of the rare gas discharge lamp according to the present invention.

FIG. 3 is a partial sectional view showing another embodiment of the rare gas discharge lamp according to the present invention.

FIG. 4 is a sectional view showing a conventional discharge lamp.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Discharge lamp, 10 ... Glass bulb, 20 ... External electrode, 2
DESCRIPTION OF SYMBOLS 1 ... External electrode, 30 ... Internal electrode, 31 ... Metal electrode, 40
... a phosphor, 50 ... a dielectric layer, 60 ... a protective layer, 70 ... a glass tube, 80 ... a conductor layer.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasushi Ikuta 2-16-16 Shinmachi, Ome City, Tokyo Ome Sangyo Co., Ltd.

Claims (11)

[Claims] 1. A cylindrical container which is a light-transmitting dielectric having a phosphor layer formed on an inner surface thereof, an external electrode formed of a transparent conductive film formed on an outer surface of the container, and an inside of the container. A rare gas discharge lamp, characterized in that it has an internal electrode made of a conductor whose surface is provided with a dielectric layer, and a rare gas is sealed in the container. 2. The rare gas discharge lamp according to claim 1, wherein a mesh-shaped conductor is used as said external electrode. 3. The rare gas discharge lamp according to claim 1, wherein a metal foil or sheet having an opening, a vapor-deposited metal, or the like is used as the external electrode. 4. The internal electrode according to claim 1, wherein a conductor is provided in a dielectric pipe made of a thin glass tube or the like. Noble gas discharge lamp. 5. The rare gas discharge lamp according to claim 1, wherein a phosphor layer is formed on a surface of the dielectric of the internal electrode. 6. The phosphor layer according to claim 1, wherein the inner surface of the cylindrical container, which is the dielectric, and the dielectric surface of the internal electrode are covered with a protective layer to form a phosphor layer. The rare gas discharge lamp according to 1. 7. The rare gas according to claim 1, wherein a rare gas such as xenon or krypton or a mixture of these rare gases is used as the sealed gas. Discharge lamp. 8. A high frequency discharge is performed by applying a sine wave, a rectangular wave, a triangular wave, or a pulse voltage between the external electrode and the internal electrode. The rare gas discharge lamp according to 1. 9. The rare gas discharge lamp according to claim 1, wherein a surface of said external electrode is covered with a transparent insulator. 10. An illuminating device configured to illuminate using the rare gas discharge lamp according to any one of claims 1 to 9. 11. A liquid crystal display device using the rare gas discharge lamp according to claim 1 as a backlight.