JPH02304856A - Cold cathode fluorescent lamp - Google Patents

Abstract

PURPOSE:To obtain a cold cathode low pressure electric discharge lamp excellent in efficiency and service life, with a tube end of simple structure by providing electrodes at both ends such that a fine tungsten filament and an electronic radioactive substance are contained on the surface or in the inside of one or a plurality of metal sheets. CONSTITUTION:Electrodes 5 at both ends are welded to a lead wire 6. The electrodes 5 are so constituted that two metal sheets 7 consisting of Fe-Zr are welded in a projecting shape a tungsten filament 8 and an electronic radiant substance of an oxide consisting of Ba, Ca, Sr and Zr are contained therein. Barium oxide out of a compound of tungsten and electronic radiant substance contained in the inside of the metal plate 7 is liable to enhance the secondary electronic radioactivity for the whole of the electrodes 5 so that the cathode drop voltage in cold cathode electric discharge is lowered resulting in the high efficiency of a lamp. Thereby, it is possible to simplify the structure of the tube end and decrease power necessary for getting the same luminous flux value so that a cold cathode fluorescent lamp with high efficiency can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a cold cathode fluorescent lamp used for backlights for liquid crystals and the like.

[Conventional technology]

Regarding hot cathode discharge lamps and cold cathode discharge lamps, please refer to the Illumination Institute of Japan's Lighting Handbook (May 1978).

Ohmsha), pages 759 to 760. Further, hot cathode type fluorescent lamps are described on page 160 of the same document. Regarding the structure of the hot cathode, please refer to the Illuminating Engineering Society's Lighting Handbook (1932).
February/November, Ohmsha), page 121.

[Problem to be solved by the invention]

In the above-mentioned conventional hot cathode low-pressure discharge lamp, two lead wires connected to both ends of one electrode are required to heat the electrode by energizing it, and the structure of the end of the discharge tube is complicated. It had the disadvantage of becoming In particular, the above drawbacks were fatal when the dimensions of the discharge vessel were small. In addition, cold cathode low pressure discharge lamps have one lead wire per electrode.
However, the drawback was that the cathode drop voltage was high and therefore the efficiency was low. Furthermore, the discharge current is 10-mA
In the above, there was a drawback that the life span was short.

An object of the present invention is to provide a cold cathode low pressure discharge lamp with a simple tube end structure, high efficiency, and long life.

[Means to solve the problem]

In order to achieve the above objective, the cathode drop voltage can be reduced by incorporating a material consisting of tungsten wire and an electron emitting material on the surface of the metal plate serving as the cold cathode discharge electrode or inside the area surrounded by multiple metal plates. This makes it possible to increase lamp efficiency.

[Effect]

The metal plate for the electrode acts as an electrode for cold cathode discharge, and due to the presence of barium oxide among the compounds of tungsten and electron radioactive substances contained on the surface of the metal plate or inside the metal plates, the entire electrode is Since the secondary electron emissivity is improved, the cathode drop voltage during cold cathode discharge is reduced, and therefore the lamp efficiency is improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows the overall structure of the cold cathode fluorescent lamp of the present invention, and FIG. 2 shows details of the electrode portion.

Both ends of the glass tube 1 are sealed, a phosphor 2 is applied to the inner wall of the glass, and mercury 3 and Ar gas 4 are sealed inside 6. Further, electrodes 5 of the present invention are welded to lead wires 6 at both ends. It is arranged as follows. The structure of the electrode is Fe-Zr.
It has a structure in which two metal plates 7 are welded to form a convex shape, and the inside contains a tungsten wire 8 and an oxide electron emitting substance (not shown) made of Ba, Ca, Sr, and Zr. be.

In this case, the electron-emitting substance is generally activated by decomposing the carbonate suspension into oxides by high-frequency heating in the tube, but before incorporating it into the tube, it is heated for 100 minutes in a nitrogen atmosphere.
Even when sintered at about 0°C, there was no change in performance.

In the present invention, the total length of the tube is 270+m+, and the outer diameter of the tube is -φ6.
5. A cold cathode lamp was prototyped, lit at high frequency, and the case using the electrode of the present invention when the lamp current was 5 mA, and the case using Fe-Zr.
In the case of only two metal plates (conventional electrodes), the lamp voltages are 280 V and 330 V, respectively, and the difference of 50 V is the decrease in cathode drop voltage.

The lamp power is 1.4W and 1.65W, respectively, so the lamp power is 0.25W (15%
reduction) was also reduced.

In this embodiment, the metal plate was made of Fe-Zr, but it goes without saying that any metal that is not particularly weak in heat resistance may be used, and the shape is not particularly limited.

FIG. 3 shows another electrode structure. The six-electrode structure has the advantage that the tungsten strip and the electron emitting material are more firmly fixed.

〔Effect of the invention〕

According to the present invention, the cathode drop voltage can be greatly reduced in a cold cathode fluorescent lamp, and the power required to obtain the same luminous flux value can be reduced, resulting in good lamp efficiency.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a lamp according to one embodiment of the present invention, FIG. 2 is a diagram showing one embodiment of the electrode section of the present invention, and FIG. 3 is a diagram showing another embodiment of the electrode section of the present invention. It is. 1...Glass tube, 2...phosphor, 3...mercury, 4
... Filled gas, 5 ... Electrode, 6 ... Lead wire, 7
...Metal plate, 8th 1st (2) 2nd (2)

Claims (1)

[Claims] 1. The tube contains an inert gas and mercury as a sealed gas,
A fluorescent lamp comprising a phosphor adhered to the inner surface of a glass tube, characterized in that the structure of the electrodes at both ends includes thin tungsten filaments and an electron emitting substance on the surface or inside of one or more metal plates. Cold cathode fluorescent lamp. 2. The cold cathode fluorescent lamp according to item 1, wherein the electron emitting substance activates a carbonate suspension system containing Ba in the tube and is an electron emitting substance containing Ba oxide. 3. The cold cathode fluorescent lamp according to item 1, wherein the electron radioactive substance is activated by sintering outside the tube.