JPH03182043A - Rare gas cold cathode discharge tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to the structure of a rare gas cold cathode discharge tube.

[Prior Art] In recent years, rare gas cold cathode discharge tubes have come to be used as light sources for illuminating documents in facsimile machines, image scanners, and the like. This is different from fluorescent lamps, which are normally used for indoor lighting, by filling the tube with a gas such as xenon instead of mercury vapor, and by replacing the electrode with a hot cathode with a heater effect. A cathode is used.

Figure 2 is a diagram showing the configuration of a conventional rare gas cold cathode tube.
In the figure, the rare gas cold cathode discharge tube is characterized in that discharge occurs not throughout the tube but on a single line, and this discharge line is called a positive column 1.

The positive column 1 is generated so as to connect the electrodes 2 at both ends of the cold cathode tube, but the path it takes is not stable.

Therefore, in order to guide the positive column 1 along a fixed path, it has been conventional practice to provide an auxiliary electrode 3 on the tube wall.

FIG. 2 shows the configuration of a conventional rare gas cold cathode tube.

In this configuration, first, the auxiliary electrode 3 is brought to the side opposite to the document 7 to be illuminated to attract the sunlight column 1. This auxiliary electrode 3 is usually made of a black conductive adhesive containing carbon or the like, and is formed by applying it in a line along the tube wall. Fluorescent material 4 is coated on the entire inner wall of the tube except for the side opposite to the auxiliary electrode, and the positive column 1 excites the fluorescent material 4 in its vicinity. The excited phosphor 4 generates visible light, which passes through a portion (aperture 5) where the phosphor is not coated on the opposite side and irradiates the document. Figure 3 shows the overall configuration including rare gas cold cathode discharge tubes and lighting circuits.

A rare gas cold cathode discharge tube having such a configuration can emit light in red, blue, green, etc. by selecting the type of phosphor used. Further, if a configuration is adopted in which the three color lamps mentioned above are sequentially turned on to illuminate the document, an image scanner or the like capable of color reading can be constructed.

However, rare gas cold cathode discharge tubes have a property that the amount of light they emit is limited due to their discharge characteristics, and the amount of light cannot be increased even if the diameter of the discharge tube is increased, for example.

[Problems and objects to be solved by the invention] Therefore, if more light is required, there is no other way than to increase the number of rare gas cold cathode discharge tubes, but color reading requires at least three tubes. In terms of equipment, there was a problem in that it was virtually impossible to arrange multiple rare gas cold cathode discharge tubes of each color with circular cross sections.

In view of this problem, it is an object of the present invention to provide a rare gas cold cathode discharge tube that makes it possible to arrange a plurality of rare gas cold cathode discharge tubes even in a color reading device, and that can obtain a sufficient amount of light.

[Means for solving the problem] In a cold cathode discharge tube that generates a discharge in a tube filled with a rare gas and excites the phosphor on the tube wall to emit light, an auxiliary electrode is provided on the tube wall to guide the discharge. The discharge tube is characterized by being composed of transparent electrodes and having a cross-sectional shape other than circular.

[Function] The rare gas cold cathode discharge tube of the present invention configured as described above has the following features:
The auxiliary electrode provided on the tube wall to guide the discharge is made of a transparent electrode, and the cross-sectional shape of the discharge tube is made into an irregular shape. By combining a large number of discharge tubes, the light emitting part can be brought closer to the document, making it possible to This makes it possible to increase the illuminance on the surface.

[Example 1] Fig. 1 shows an example of a rare gas cold cathode discharge tube according to the present invention.

In FIG. 1, the cross-sectional shape of the discharge tube is triangular as shown, and a transparent electrode 6 is attached to the apex of the discharge tube to guide a sunlight column 1. By directing the vertex of the transparent electrode 6 toward the document 7 to be illuminated, the light transmitted through the transparent electrode illuminates the document 7.

Here, the transparent electrode 6 uses a transparent conductive adhesive instead of the black conductive adhesive. A typical example of this transparent conductive adhesive is one whose main components are fine metal powder (Sn, etc.) and an organic binder.
There is one with 010Ω/cm2. Furthermore, the light transmittance is generally around 80%.

By adopting such a configuration, a large number of rare gas cold cathode discharge tubes can be arranged in a small volume, and the amount of illumination light can be significantly increased.

Further, the cross-sectional shape of the cold cathode tube according to the present invention is not limited to a triangular shape, and the same effect can be obtained by using an oval shape as shown in FIG. 4, for example.

[Effect of the invention] Noble gas according to the present invention? By using cathode discharge tubes, it is possible to arrange a large number of discharge tubes, which has the effect of providing much brighter illumination than in the past.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a cold cathode fluorescent tube according to the present invention, which is a rare gas cold cathode fluorescent tube using a transparent auxiliary electrode and having an irregular cross section. FIG. 2 is a cross-sectional perspective view showing the configuration of a conventional rare gas cold cathode fluorescent tube. FIG. 3 is a conceptual diagram showing the overall configuration of a rare gas cold cathode fluorescent tube. FIG. 4 is a diagram showing another specific example of the rare gas cold cathode discharge tube according to the present invention. 1...Positive column 2...Electrode 3...Auxiliary electrode 4...Phosphor 5...Aperture 6...Transparent electrode 7...More than original

Claims (1)

[Claims] In a cold cathode discharge tube that generates a discharge in a tube filled with a rare gas and excites the phosphor on the tube wall to emit light, the auxiliary electrode provided on the tube wall to guide the discharge is composed of a transparent electrode, and the discharge A rare gas cold cathode discharge tube characterized in that the tube has a cross-sectional shape other than circular.