JPH09134705A - External electrode type fluorescent discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge tube of simple structure with no provision of any separate reflex mirror in conformity to the request for optical output increase of a light source resulting from a high speed operation of original document reading. SOLUTION: A discharge tube concerned including a glass tube 1 has an effective light emission surface 7 where light emission takes place, and a reflecting material 8 is applied to a region at least between electrodes 2, 3 on the external surface of tube facing the effective light emission surface 7, and the whole glass tube 1 incl. reflecting material 8 and electrodes 2, 3 is covered with an insulative tube 9. The coated reflecting material 8 serves for effective utilization of the light emitted from this discharge tube without requiring provision of any separate reflection mirror in the vicinity of outside of the discharge tube.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external electrode type fluorescent discharge tube used for a document illumination used for information equipment such as a facsimile, a copying machine, an image reader and a backlight of a liquid crystal panel display. .

[0002]

2. Description of the Related Art A conventional technique will be described with reference to the drawings. FIG. 1 shows a cross-sectional view of a conventional external electrode type fluorescent discharge tube perpendicular to the tube axis. There is an external electrode type fluorescent discharge tube as a fluorescent lamp used as a light source for reading originals for OA equipment, a backlight of a liquid crystal display device, and the like. As shown in FIG. 1, in this fluorescent discharge tube, a pair of linear or strip-shaped external electrodes 2 and 3 are provided on the outer surface of a glass tube 1, and a fluorescent substance 5 is applied to the inner surface of the glass tube 1. . The external electrodes 2 and 3 are turned on by applying a continuous high frequency voltage or a pulsed high frequency voltage.

That is, this external electrode type fluorescent discharge tube is
A high frequency voltage oscillating through the wall surface of the glass tube 1 is applied to the discharge space inside the glass tube 1 sandwiched between the pair of external electrodes 2 and 3, and a discharge is generated in the glass tube 1. This discharge can have a large discharge current by setting the size of the external electrodes 2 and 3 to a predetermined size or more, and can effectively excite the entire fluorescent substance 5 on the inner surface of the bulb.
The light output can be significantly increased as compared with the conventional internal electrode type discharge tube.

[0004]

As described above, the external electrode type fluorescent discharge tube of recent years can greatly increase the light output as compared with the conventional internal electrode type fluorescent discharge tube, but the facsimile, copying machine, image In document illumination applications used for information devices such as readers, there is a demand for higher document reading speed, and therefore, it is necessary to further increase the light output of the fluorescent discharge tube for the same applications.

In order to increase the light output of the fluorescent discharge tube, a reflection mirror is arranged in the vicinity of the discharge tube separately from the discharge tube, and the reflected light from the reflection mirror is added to the light emitted from the discharge tube. There is also a method to increase the amount of light, but the reflection mechanism including the discharge tube becomes dimensionally large, and the method of attaching the discharge tube and the reflection mirror and the alignment of the discharge tube and the reflection mirror become complicated, and the discharge tube and the reflection mirror When it comes to unitization with a mirror, the manufacturing cost of the unit also increases. The present invention solves such a problem and makes it possible to realize an external electrode type fluorescent discharge tube brighter than the conventional external electrode type fluorescent discharge tube with a simple structure.

[0006]

[Means for Solving the Problems]

<Means 1> He, Ar, Xe, Kr, N inside the glass tube
A predetermined amount of at least one kind of rare gas of e is sealed and sealed, a fluorescent substance is applied to the inner surface of the glass tube, and a linear or strip electrode is provided parallel to the tube axis direction on the outer surface of the glass tube. In a pair of external electrode type fluorescent discharge tubes, a light reflecting material is provided between at least the electrodes on the outer surface of the glass tube excluding the effective light emitting surface of the glass tube. The problem is solved by using a discharge tube.

<Means 2> The fluorescent substance on the inner surface of the glass tube facing the effective light emitting surface of the glass tube is removed over a substantially entire length of the glass tube in a predetermined width along the tube axis direction. The problem is solved by using the external electrode type fluorescent discharge tube according to claim 1.

<Means 3> The external electrode type fluorescent discharge tube according to claim 1 or 2, wherein the entire glass tube including the reflector and the electrode is covered with an insulating tube. By solving the problem.

<Means 4> The fluorescent substance on the effective light emitting surface side of the glass tube is removed by a predetermined width along the tube axis direction of the glass tube, and an aperture is provided.
The problem is solved by using the external electrode type fluorescent discharge tube according to claim 3.

[0010]

By arranging the reflecting material directly on the outer surface of the glass tube, the ultraviolet light generated by the discharge inside the glass tube is converted into visible light by the fluorescent substance on the inner surface of the glass tube, and the emitted light is the reflecting material. The light emitted to the outside of the discharge tube is increased by being reflected by the surface of the.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a schematic view of the connection between the external electrode type fluorescent discharge tube and the high frequency ballast of this embodiment. A high-frequency voltage oscillating from a high-frequency ballast 4 is applied to the discharge space inside the glass tube 1 sandwiched between the pair of external electrodes 2 and 3 through the wall surface of the glass tube 1 to cause discharge inside the glass tube 1. Cause

FIG. 3 is a sectional view of the external electrode type fluorescent discharge tube in this embodiment, which is perpendicular to the tube axis. The glass tube 1 is filled with a rare gas containing xenon gas as a main component after a predetermined evacuation process, and both ends of the glass tube 1 are closed. If necessary, the glass tube 1 may be filled with mercury in addition to the rare gas. The fluorescent material 5 is applied to the inner surface of the glass tube 1. Here, the effective light emitting surface 7 of the external electrode type fluorescent discharge tube is a region sandwiched by a pair of electrodes on the outer surface of the glass tube 1, and is defined as the glass tube surface on the light extraction side of the discharge tube. The effective light emitting surface 7 is one of the two regions of the glass tube 1 located between the electrodes 2 and 3, and here the fluorescent material 5 on the inner surface of the glass tube is removed and an aperture 6 is provided. . The electrodes 2 and 3 are strip electrodes provided along the axial direction of the glass tube 1. The electrodes 2 and 3 are formed of a metal tape such as Al or Cu, or a conductive paint such as a silver paste. .

In FIG. 3, a reflecting material 8 in which a white powder is dissolved in a solution is applied between the electrodes on the outer surface of the glass tube 1 facing the effective light emitting surface 7, and after the reflecting material 8 is dried, the reflecting material 8 and the electrodes are formed. The entire glass tube 1 including 2 and 3 is covered with a transparent insulating tube 9 to fix the reflecting material 8. In addition,
The glass tube 1 is not covered with the insulating tube 9 and the electrodes 2, 3
The electrode end portion, which is located on the aperture 6 side and is parallel to the axial direction of the glass tube, may be covered with an insulator.

Further, as in the example shown in FIG. 4, the fluorescent substance 5 on the inner surface of the glass tube 1 facing the effective light emitting surface 7 is provided with a predetermined width W along the tube axis direction over substantially the entire length of the glass tube 1. The effect of the reflective material 8 can be increased by removing it by.

In this embodiment, as the reflecting material 8, barium sulfate is dissolved in concentrated sulfuric acid, a binder is added, and a thin film is applied to the outer surface of the glass tube 1 to be dried.
The ultraviolet rays generated by the discharge inside the glass tube 1
Visible light is emitted from the fluorescent substance 5 upon hitting the fluorescent substance 5 on the inner surface, and the emitted light is reflected by the surface of the reflector 8 to increase the light emitted to the outside of the discharge tube. In addition to the above-mentioned barium sulfate, magnesium oxide, aluminum oxide, calcium pyrophosphate, etc. may be used as the material of the reflecting material 8, and any material having a high reflectance of light in the visible light region and being electrically insulating may be used. Good. The electrical insulation of the reflector 8 is necessary to prevent creeping discharge between the external electrodes 2 and 3 on the surface of the glass tube 1. As a means for disposing the reflecting material 8, a powdery reflecting material may be fixed to the outer surface of the glass tube, or a tape-like reflecting material or a sheet-like reflecting material may be stuck to the outer surface of the glass tube 1. Good.

Further, if the insulating tube 9 covering the entire glass tube 1 is colored, there is no problem. Since it covers the entire lamp to hold the reflector 8,
The insulating tube 9 may have any color as long as it can hold the reflecting material.

FIG. 6 shows another embodiment of the present invention,
A predetermined amount of at least one kind of rare gas of He, Ar, Xe, Kr and Ne is sealed and sealed in the glass tube 1,
The fluorescent material 5 is applied to the inner surface of the glass tube 1, and the effective light emitting surface 7 of the glass tube 1 is formed in a band shape parallel to the tube axis direction, and is insulated from the outer surface of the glass tube 1 other than the effective light emitting surface 7. Of the reflective material 8 and the electrodes 2 and 3 are provided with a pair of strip-shaped electrodes parallel to the tube axis direction of the outer surface of the glass tube 1 at a predetermined interval on the reflective material 8. An external electrode type fluorescent discharge tube in which the entire tube 1 is covered with an insulating tube 9 is shown.

FIG. 5 shows an external electrode type fluorescent discharge tube having the structure shown in FIG. 3 in which the reflector 8 according to the present invention is arranged, and the reflector 8.
The following shows the results of experiments in which the relative values of illuminance were compared in a conventional external electrode type fluorescent discharge tube in which is not provided. The external electrode type fluorescent discharge tube used in the experiment has a lamp tube diameter of φ8 mm,
The lamp length is 360 mm, and the illuminance is 8 from the lamp wall.
The illuminance at a distance of mm was measured with a luminometer. The lamp current during lighting is 48 mA, and the lighting frequency is 34 kHz.
It is. In the experiment conducted this time, it was confirmed that the external electrode type fluorescent discharge tube of the present invention provided with the reflecting material increased the illuminance by about 10% as compared with the conventional external electrode type fluorescent discharge tube having no reflecting material. .

[0017]

As described above, according to the present invention, a reflector is provided between at least electrodes on the outer surface of the glass tube facing the effective light emitting surface side of the glass tube from which the emitted light of the external electrode type fluorescent discharge tube is emitted. By coating the entire glass tube including the reflective material and electrodes with an insulating tube and holding the reflective material, the emitted light can be used effectively without a separate reflection mirror outside the discharge tube. I was able to do it.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a conventional external electrode type fluorescent discharge tube perpendicular to the tube axis.

FIG. 2 is a schematic diagram of a connection between a lamp and a high frequency ballast according to an embodiment of the present invention.

FIG. 3 is a cross-sectional view perpendicular to the tube axis of the external electrode type fluorescent discharge tube of the present invention.

FIG. 4 is a cross-sectional view perpendicular to the tube axis of a discharge tube according to another embodiment of the external electrode type fluorescent discharge tube of the present invention, in which some fluorescent substances are removed.

FIG. 5 is a diagram showing the effect of increasing the illuminance by the reflector of the external electrode type fluorescent discharge tube of the present invention.

FIG. 6 is a cross-sectional view perpendicular to the tube axis of the discharge tube of another embodiment of the external electrode type fluorescent discharge tube of the present invention, in which a reflecting material is arranged below the electrodes.

[Explanation of symbols]

 1 Glass Tube 2 External Electrode 3 External Electrode 4 High Frequency Ballast 5 Fluorescent Material 6 Aperture 7 Effective Light Emitting Surface 8 Reflective Material 9 Insulating Tube

Claims (4)

[Claims] 1. Inside the glass tube, He, Ar, Xe, Kr,
A predetermined amount of one or more rare gases of Ne is sealed and sealed, a fluorescent substance is applied to the inner surface of the glass tube, and a linear or strip electrode is formed parallel to the tube axis direction on the outer surface of the glass tube. In the external electrode type fluorescent discharge tube in which a pair of are arranged, a reflecting material is provided between at least the electrodes on the outer surface of the glass tube excluding the effective light emitting surface of the glass tube. tube. 2. The fluorescent substance on the inner surface of the glass tube facing the effective light emitting surface of the glass tube is removed with a predetermined width over substantially the entire length of the glass tube along the tube axis direction. The external electrode type fluorescent discharge tube according to 1. 3. The external electrode type fluorescent discharge tube according to claim 1, wherein the entire glass tube including the reflection material and the electrode is covered with an insulating tube. . 4. The fluorescent substance on the effective light emitting surface side of the glass tube is removed with a predetermined width along the tube axis direction of the glass tube, and an aperture is provided.
The external electrode type fluorescent discharge tube according to claim 3.