JP4237103B2 - External electrode type discharge lamp - Google Patents

Description

  The present invention relates to an external electrode type discharge lamp.

  In a liquid crystal display device that requires a large screen such as for a liquid crystal television, a backlight using an external electrode type mercury fluorescent lamp as a light source is often used.

  The basic structure of the external electrode type discharge lamp will be described with reference to FIG. The discharge lamp shown in FIG. J1 is a mercury fluorescent lamp, and external electrodes 2A and 2B are provided on the outer surfaces of both ends of the cylindrical glass bulb 1 one by one. The exteriors 2A and 2B are electrically insulated from each other. In the discharge chamber, which is a medium air-tight space inside the glass bulb 1, as a discharge medium gas, for example, a mixed gas of xenon and mercury vapor, or the mixed gas and other rare gases such as argon and neon Of mixed gas.

  A protective film 3 is formed on the inner surface of the glass bulb 1 below the external electrodes 2A and 2B. This protective film 3 protects the inner surface of the glass bulb and is made of a metal oxide such as yttrium oxide. A phosphor film 4 is provided on the inner surface of the glass bulb 1 on the center portion side (discharge chamber side). The phosphor film 4 plays a role of converting ultraviolet rays generated in the glass bulb by discharge into light of other wavelengths.

  In the illustrated external electrode type mercury fluorescent lamp, when a sine wave voltage, for example, is applied between the two external electrodes 2A and 2B from the external power supply device 15, the glass which is the lamp container directly under the external electrode is polarized, and the inner surface thereof is Acts as an electrode. Thereby, the enclosed mercury discharges and emits ultraviolet rays. The emitted ultraviolet light excites the phosphor and emits light, and the emitted light is emitted to the outside of the lamp vessel to function as a lamp.

Here, as the external electrodes 2A and 2B, a metal film such as silver by a printing method, a metal plating such as Ni, or solder formed directly on a glass surface by ultrasonic solder dip, directly formed on a glass bulb, A material obtained by directly forming an electrode by applying or dipping a conductive paste containing metal particles on a glass bulb was used (see Patent Document 1).
Japanese Patent Laid-Open No. 11-040109 (see paragraph [0023])

  In the conventional external electrode type mercury fluorescent lamp, the external electrode is made of a metal film such as silver by printing, metal plating such as Ni, or solder formed by ultrasonic solder dip directly on a glass bulb, or metal particles. The electrode formed by applying or dipping the contained conductive paste directly on the glass bulb is used, and the connection between the external electrode and the electrode lead-out part (for example, connector) is performed. However, in the former case, due to insufficient pinching or an increase in contact resistance due to aging of the pinching portion, a discharge occurs between the electrode lead-out portion and the external electrode during energization, and the metal exposed to the discharge There is a problem in that the external electrode portion, which is a thin film, is oxidized and scattered to expose the internal gallium bulb surface. In the latter case, the resin of the conductive paste deteriorates due to ultraviolet rays radiated from the inside, and the service life is shortened. When a silicone resin that is resistant to ultraviolet deterioration is used, the adhesive strength is low, and the external electrode peels off. was there.

  Further, when a voltage is applied between the external electrodes formed at both ends of the lamp vessel, a discharge occurs on the inner surface of the glass tube below the electrodes, and heat generated by the discharge is transmitted to the electrodes. When the electrode generates heat excessively, the glass tube is damaged by the heat, so it was necessary to transmit the heat generation to the outside and lower the glass tube temperature.

  An object of the present invention is to provide an external electrode type discharge lamp (for example, a mercury fluorescent lamp) having an external electrode having a high reliability and a long lifetime in view of the above-mentioned problems of the prior art.

In order to achieve the above object, the present invention comprises a glass bulb forming an airtight space, a gas of a discharge medium sealed inside the glass bulb, and an external electrode provided on the outer surface of the glass bulb. In the external electrode type discharge lamp including, the external electrode is made of a metal sleeve attached to each of both end portions of the glass bulb, and the inner surface of the glass bulb corresponds to the sleeve at the inner surface. The glass bulb and the external electrode are bonded to each other by melting the frit glass applied between them.

  Instead of the above-described sleeve, a metal cap placed on each of both ends of the glass bulb can be used as the external electrode.

It is preferable that the glass bulb, the frit glass, and the external electrode have relatively the same thermal expansion coefficients in order to reduce bulb damage due to thermal stress.

  In the present specification, “sleeve” refers to a cylindrical member whose openings at both ends are not closed, and “cap” refers to a cylindrical member whose one opening is closed.

According to the present invention, as an external electrode on the surface of both end portions of the glass bulb, fitted with a metal cap or sleeve, to bond the metal cap or a metal sleeve is a glass bulb and the external electrode by melting frit glass As a result, a problem arises in that a discharge occurs between the electrode extraction portion and the external electrode, and the external electrode portion exposed to the discharge is oxidized and scattered, thereby exposing the internal gallium bulb surface. A sufficiently thick metal cap or metal sleeve was used. Can be avoided. Since the frit glass is welded to the external electrode and the glass bulb, the adhesive strength is sufficiently high and there is almost no deterioration due to ultraviolet rays.

  Next, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing an external electrode type mercury fluorescent lamp according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of the mercury fluorescent lamp of FIG. 1 cut along its tube axis.

  As shown in FIGS. 1 and 2, the mercury fluorescent lamp of this embodiment has a structure in which external electrodes 12 </ b> A and 12 </ b> B are bonded to the surfaces of both ends of the glass bulb 11.

The glass bulb 11 is a light-transmitting sealed cylinder made of borosilicate glass or the like, and a gas of a discharge medium such as a mixed gas of xenon and mercury vapor is enclosed in an airtight space inside. The pressure inside the valve is about 1.3 × 10 ³ to 40 × 10 ³ Pa (10 to 300 Torr). A protective layer 14 made of, for example, an yttrium oxide film is formed on the inner surface of the glass bulb 1 under the external electrodes 12A and 12B, and a phosphor layer 15 is formed on the other portions. The phosphor is not particularly limited, and an appropriate phosphor is selected according to the wavelength of light to be emitted to the outside.

  The external electrodes 12A and 12B are sufficiently thick metal sleeves of 2 to 5 mm, for example. Further, as shown in FIGS. 3 and 4, a metal cap may be used so as to cover the end portion of the glass bulb as the external electrodes 22A and 22B. The glass bulb 11 and the external electrodes 12A and 12B (or 22A and 22B) are bonded together by heating and melting a sealing glass (frit glass) 13 applied therebetween.

  As the material of the external electrodes 12A and 12B (or 22A and 22B), 42 alloy, KOV (Kovar) or the like is used.

  The sealing glass 13 is a powder glass mainly used for sealing glass and metal. In use, a sealing portion (external electrode) is obtained by dispersing a powder glass in a solvent by a printing method or the like. Are applied and formed, and the sealing glass 13 is melted and bonded by heating.

  The glass bulb 11, the sealing glass 13, and the metal sleeve that is the external electrodes 12A and 12B (or the metal cap that is the external metal 22A and 22B) have a relatively similar thermal expansion coefficient. Desirable to reduce.

1 is a perspective view showing an external electrode type mercury fluorescent lamp according to an embodiment of the present invention. It is sectional drawing when the mercury fluorescent lamp of FIG. 1 is cut along the tube axis. It is a perspective view which shows the external electrode type | mold mercury fluorescent lamp by another embodiment of this invention. It is sectional drawing when the mercury fluorescent lamp of FIG. 2 is cut along the tube axis. (A) is a perspective view which shows the conventional external electrode type | mold mercury fluorescent lamp, (b) is sectional drawing when the mercury fluorescent lamp of FIG. (A) is cut | disconnected along the tube axis | shaft.

Explanation of symbols

11 Glass bulb 12A, 12B, 22A, 22B External electrode 13 Sealing glass 14 Protective layer 15 Phosphor layer

Claims (3)

In an external electrode type discharge lamp including a glass bulb that forms an airtight space, a gas of a discharge medium sealed inside the glass bulb, and an external electrode provided on an outer surface of the glass bulb,
The external electrode consists of a metal sleeve attached to each of both ends of the glass bulb,
A protective layer for protecting the inner surface is formed at a position corresponding to the sleeve on the inner surface of the glass bulb,
2. An external electrode type discharge lamp, wherein the glass bulb and the external electrode are bonded by melting frit glass applied between them. In an external electrode type discharge lamp including a glass bulb that forms an airtight space, a gas of a discharge medium sealed inside the glass bulb, and an external electrode provided on an outer surface of the glass bulb,
The external electrode consists of a metal cap placed on each end of the glass bulb,
A protective layer for protecting the inner surface is formed at a position corresponding to the cylindrical portion of the cap on the inner surface of the glass bulb,
2. An external electrode type discharge lamp, wherein the glass bulb and the external electrode are bonded by melting frit glass applied between them. The external electrode type discharge lamp according to claim 1 or 2, wherein the glass bulb, the frit glass, and the external electrode have the same thermal expansion coefficient.

Images