JP2002289133A - Cold cathode discharge tube and illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cold cathode discharge tube whose electrodes which are mounted on sealing metal members which are sealed to a glass valve do not drop from the sealing metal members while the cold cathode discharge tube is being lighted for a long period of time, and an illuminating device using it. SOLUTION: By fixing the electrodes 5 and 6 with the sealing metal members 3 and 4 which are, via medium metal members, sealed to ends of the glass valve in which prescribed pressure rare gas is enclosed and mercury is diffused, the electrodes 5 and 6 do not drop keeping their junctions stable while the cold cathode discharge tube is being lighted for a long period of time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cold cathode discharge tube and an illuminating device used for a lighting device of a liquid crystal display device such as a personal computer, and more particularly to a cold cathode discharge tube sealed at both ends of a glass bulb. The present invention relates to a cold-cathode discharge tube in which an electrode attached to the tip of a sealing metal body located at a position above does not fall off from the sealing metal body even when used for a long time, and a lighting device using the same.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 6, a cold cathode discharge tube used for a lighting device of a liquid crystal display device is sealed at both ends of a glass bulb 2 through bead glasses 7 and 8, and is a glass bulb. The electrodes 19 and 20 of a bottomed cylindrical metal body are attached to the tips of the sealing metal bodies 3 and 4 located in the inside 2, and a phosphor coating (not shown) is applied to the inner surface of the glass bulb 2.
Further, mercury is diffused and sealed in the interior 9 of the bulb 2 together with a mixed rare gas such as argon or neon.

As shown in FIG. 7, a sealing metal body 3 is formed by welding a first metal body 21 made of, for example, tungsten and a second metal body 22 made of kovar or nickel having a relatively low melting point at a welding portion 23. In addition, the sealing metal body 3 and the electrode 19 which is a cylindrical metal body with a bottom are fixed by welding at a substantially central portion outside the bottom surface of the electrode 19. Reference numeral 24 denotes the welded portion, and FIG. 8 is a perspective view of the welded portion. The other sealing metal body 4 and the electrode 20 have the same configuration as the sealing metal body 3 and the electrode 19. Reference numeral 25 denotes a space portion of the electrode 19, and the glass bulb 2
Inside, the electrodes 19 and 20 are provided in the glass bulb so that the space 25 and the space (not numbered) of the other electrode 20 face each other.

[0004]

The above conventional discharge tube is
When the lamp is used for a long time of 1,000 or 1,500 hours, as shown in FIG. 9, the inner bottom surface of the electrode 19 is gradually scraped off from a flat broken line as indicated by 26, and the first metal is removed. The thickness of the bottom surface becomes very thin before reaching the welded portion 24 welded to the body 21, and finally the electrode 19 falls off the first metal body 21 and falls into the glass bulb 2. When the electrode drops from the first metal body 21, the function as a discharge tube cannot be exhibited, and naturally, a lighting device using the same cannot exert its lighting function.

Accordingly, the present invention has been made to eliminate such a problem, and an object of the present invention is to provide a cold cathode discharge tube in which an electrode does not come off from a sealing metal body even when used for a long time, and a lighting device therefor. It is the purpose.

[0006]

In order to solve the above-mentioned problems, a cold-cathode discharge tube according to the present invention according to the first aspect of the present invention comprises a pair of sealed metal bodies sealed in a glass bulb and located in the glass bulb. The electrode to be attached is a cylindrical metal body, an intermediate metal body that is interposed between the sealing metal body and the cylindrical metal body and is welded together with the cylindrical metal body and the sealing metal body,
It consists of a space formed at the tip of the cylindrical metal body, and the intermediate metal body is inserted between the sealing metal body and the cylindrical metal body, and they are welded and fixed. There is no fear that the electrode will fall off the sealing metal body even afterwards.

The cold cathode discharge tube of the present invention according to claim 2 is
The intermediate metal body interposed between the sealing metal body and the cylindrical metal body and welded together with the cylindrical metal body and the sealing metal body has a bottomed shape. You may use your body.

The cold cathode discharge tube of the present invention according to claim 3 is:
The intermediate metal body inserted between the sealing metal body and the cylindrical metal body and welded together with the cylindrical metal body and the sealing metal body has a cylindrical shape without a bottom, and is a simple cylinder without a bottom. An intermediate metal body may be used.

According to a fourth aspect of the present invention, there is provided a cold cathode discharge tube comprising:
The portion of the sealing metal body fixed to the intermediate metal body is composed of the first metal body and the second metal body sealed at the end of the glass bulb, and is not a single metal body. Is also good.

According to a fifth aspect of the present invention, there is provided a cold-cathode discharge tube according to the first aspect of the present invention, wherein a first metal member sealed in a glass bulb is used.
The metal body is tungsten metal and the second metal body is nickel metal, and such a metal material may be used.

According to a sixth aspect of the present invention, in the lighting device of the present invention, the electrodes attached to the pair of sealing metal bodies sealed with the glass bulb are formed of a cylindrical metal body, the sealing metal body and the cylindrical metal body. An intermediate metal body interposed between the metal body and welded together with the cylindrical metal body and the sealing metal body, and a cold cathode discharge tube formed by a space formed at the tip of the cylindrical metal body; A light guide disposed in close proximity to the cold cathode discharge tube, a light reflector that reflects light emitted from the cold cathode discharge tube and makes light incident on the light guide, and a lower surface side of the light guide. A light reflecting plate to be arranged;
A light control member disposed on the upper surface side of the light guide and controlling the direction of light emitted from the upper surface of the light guide, even if the electrodes of the cold cathode discharge tube have been turned on for a long time. Since there is no fear of falling off from the sealing metal body, stable light can be emitted from the upper surface of the light guide and above the light control member for a long period of time.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view of a cold-cathode discharge tube according to the present invention.
It has the same configuration, and the description is omitted. The cold cathode discharge tube 1 of the present invention is different from the conventional cold cathode discharge tube 1 in the electrodes 5 and 6, and the other configuration is the same as the conventional one. FIG. 2 is an enlarged sectional view of the electrode, and FIG. It is a perspective view.

In the figure, an electrode 5 is welded to a tungsten sealing metal body 3 by a welding device (not shown) via a tubular intermediate metal body 11 having a bottomed cylindrical metal body 10 made of nickel metal. It is fixed with. The outer diameter of the intermediate metal body 11 is slightly smaller than the inner diameter of the cylindrical metal body 10, and the inner diameter of the intermediate metal body 11 is slightly larger than the outer diameter of the sealing metal body 3. 10, the inner and outer diameters of the intermediate metal body 11 and the outer diameter of the sealing metal body 3
A size such that each of the cylindrical metal body 10, the intermediate metal body 11, and the sealing metal body 3 can be completely welded when the discharge electrode of the welding device is pressed from the outside of the cylindrical metal body 10 and brought into contact therewith and welded. Is necessary. This welding may be performed at two places on the outer surface of the cylindrical metal body in the perspective view of FIG.
Welding may be performed by increasing the number of welding places, such as six places and six places.

Reference numeral 13 denotes a space formed by welding the cylindrical metal body 10, the intermediate metal body 11, and the sealing metal body 3. Further, the intermediate metal body 11 is
Although the side is a cylindrical metal body with a bottom, it may be a cylindrical metal body without a bottom like the cylindrical metal body 10, but in this case,
Since the tip of the sealing metal body 3 is exposed and thus the tip of the sealing metal body 3 is worn by the impact at the time of discharge, the bottomed shape is preferable as in the present embodiment. Further, the intermediate metal body 1
Although the opening end face (not numbered) of 1 is the same as the end face of the cylindrical metal body 10, the respective end faces may be slightly shifted and not the same.

FIG. 4 is a cross-sectional view schematically showing an illuminating device according to the present invention using such a cold cathode discharge tube. In FIG. 4, reference numeral 1 denotes a cold cathode discharge tube, and 14 denotes a translucent resin material. The light guide 15 having, for example, a rectangular parallelepiped shape, which is made, is a light diffusion plate alone or a combination of a light diffusion plate and a prism sheet, and is a light control for controlling the direction of light emitted from the upper surface of the light guide 14. Reference numeral 16 denotes a light reflecting plate disposed on the lower surface of the light guide 14 for reflecting light passing through the light guide 14 and causing the light to enter the light guide 14 again. Reference numeral 17 denotes light emitted from the cold cathode discharge tube 1. It is a light reflector that reflects light to be incident on the light guide 14, and has a light reflection layer with good light reflectivity on its inner surface.

The illuminating device having the above configuration is publicly known in terms of configuration, and detailed description of its operation is omitted.
By using the cold cathode discharge tube of the present invention, even in long-time lighting use, the electrode does not fall off the sealing metal body, and the cold cathode discharge tube functions as a discharge tube for a long time. Since the lighting device can be fully exhibited over a long period of time, a lighting device which emits stable emission light over a long period of time can be provided.

Next, 10 cold cathode discharge tubes of the present invention and conventional cold cathode discharge tubes were manufactured with the same specifications except for the respective electrodes, and each was actually subjected to a lighting test. That is, the outer diameter of the glass bulb 2 shown in FIGS.
The inner diameter is 1.6 mm, the interval between the tip of the electrode 5 and the tip of the electrode 6 and the interval between the tip of the electrode 19 and the tip of the electrode 20 are 280 mm, and 5% of neon sealed inside the glass bulb. 6.6 KP mixed rare gas of 95% argon
a, and 2.0 mg of mercury was diffused and sealed.

The sealing metal body 3 includes a first metal body 21 of 0.6 mmφ tungsten and a second metal body of 0.6 mmφ nickel.
A metal body fixed to the metal body 22 was used, and a sealing metal body 4 similar to the sealing metal body 3 was used.

Further, the electrodes 5, 6 of the cold cathode discharge tube of the present invention.
Has an outer diameter of 1.4 mmφ, an inner diameter of 1.2 mmφ, and a wall thickness of 0.1 m
m, using a cylindrical metal body 10 of nickel material with a total length of 5 mm, outer diameter 1.1 mmφ, inner diameter 0.7 mmφ, wall thickness 0.2 m
m, bottomed intermediate metal body 1 of 2.5 mm length nickel material
1 using a conventional cold cathode discharge tube.
Nos. 9 and 20 were manufactured using a cylindrical metal body of nickel material having an outer diameter of 1.4 mm, an inner diameter of 1.2 mm, a wall thickness of 0.1 mm, and a total length of 4.0 mm.

Using the lighting circuit shown in FIG. 5, the present invention and the conventional cold-cathode discharge tube having the above-described structures were turned on by supplying a current of 6 mA at a frequency of 57 kHz, and the dropout of the electrode was examined. In FIG. 5, reference numeral 18 denotes a power supply for supplying a lighting current to the cold-cathode discharge tubes, X denotes a discharge tube to be tested for lighting, and the discharge tube is a sealed metal body of the present invention and the conventional cold-cathode discharge tube. 3 is connected to the ground side, which is the low-voltage side of one end of the power supply 18, and the sealed metal body 4 is connected to the high-pressure side at the other end of the power supply, and is turned on.
After 500 hours of lighting, the electrode was checked for drop-off.

As a result, the difference between the cold-cathode discharge tube of the present invention and the conventional cold-cathode discharge tube is obvious, and the product of the present invention remains on the high voltage side and the earth side even after the lighting time of 1,500 hours. The electrodes 5 and 6 attached to the connected enclosing metal bodies 3 and 4 do not drop off at all in the electrodes 5 and 6, whereas the conventional product does not drop off at all after the lighting time of 500 hours. After lighting for 2,000 hours, six out of ten electrodes 19 attached to the encapsulating metal body 3 connected to the ground side of the power supply device 18 have been dropped, and the encapsulation connected to the high voltage side of the power supply device 18 Since eight out of ten electrodes 20 attached to the metal body 4 were dropped, which was a very bad result, lighting of the conventional cold cathode discharge tube was stopped after 1,000 hours.

As described above, since the electrode of the present invention does not have any electrode detachment even after lighting for 1,500 hours,
It is clear how excellent the invention is.

In the above embodiment, nickel is used for the tubular metal body 10 of the electrodes 5 and 6. However, other materials such as iron, an alloy of iron and nickel, and niobium may be used. Nickel 11 is also used, but other materials such as iron, an alloy of iron and nickel, and an alloy of iron, nickel and cobalt may also be used.

[0025]

As described above, the cold cathode discharge tube of the present invention is sealed with the cylindrical metal body via the intermediate metal body interposed between the cylindrical metal body forming the electrode and the sealed metal body. Since the electrode is fixed to a metal body, the electrode can be provided with extremely stable lighting without falling off of the enclosed metal body even during long-time lighting as compared with a conventional cold cathode discharge tube. Also, an illumination device using such a cold cathode discharge tube can provide an illumination device that can exhibit a stable illumination function for a long period of time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a cold cathode discharge tube showing one embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a state where the sealing metal body and the electrode according to FIG. 1 are mounted.

FIG. 3 is an enlarged perspective view of an attached state of the sealing metal body and the electrode according to FIG. 2;

FIG. 4 is a cross-sectional view of an illumination device using the cold cathode discharge tube of the present invention.

FIG. 5 is a lighting circuit diagram of a cold cathode discharge tube.

FIG. 6 is a sectional view of a conventional cold cathode discharge tube.

FIG. 7 is an enlarged sectional view showing an attachment state between the electrode and the sealing metal body according to FIG. 6;

FIG. 8 is an enlarged perspective view showing an attached state of the electrode and the sealing metal body according to FIG. 7;

FIG. 9 is a cross-sectional view showing a state of a bottom surface of an electrode attached to a sealing metal body of a conventional cold cathode discharge tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Cold cathode discharge tube 2 Glass bulb 3, 4 Sealing metal body 5, 6 Electrode 10 Cylindrical metal body 11 Intermediate metal body 13 Space part 14 Light guide 15 Light control member 16 Light reflector 17 Light reflector 21 First Metal body 22 Second metal body

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Claims (6)

[Claims] 1. A glass bulb, a rare gas and mercury sealed at a predetermined pressure inside the glass bulb, a fluorescent coating applied to an inner surface of the glass bulb, and sealed at both ends of the glass bulb. A pair of sealing metal bodies, and a pair of electrodes attached to tips of the pair of sealing metal bodies located in the glass bulb, wherein the electrodes are a cylindrical metal body and the sealing metal body. And an intermediate metal member interposed between the metal member and the cylindrical metal member, and a space formed between the cylindrical metal member, the intermediate metal member, and the sealing metal member. A cold cathode discharge tube in which a metal body, the intermediate metal body, and the cylindrical metal body are welded and fixed to each other, and the space portions of the pair of electrodes face each other in the glass bulb. 2. The intermediate metal body according to claim 1, wherein the intermediate metal body has a bottomed cylindrical shape, and is attached to the sealing metal body such that the bottomed bottom surface is in contact with a tip of the sealing metal body. Cold cathode discharge tube. 3. The cold cathode discharge tube according to claim 1, wherein the intermediate metal body has a cylindrical shape without a bottom. 4. The sealing metal body includes a first metal body fixed to the intermediate metal body, and a second metal body sealed to an end of the glass bulb. Body and said second
2. The cold cathode discharge tube according to claim 1, wherein said cold cathode discharge tube is welded to said metal body. 5. The cold cathode discharge tube according to claim 4, wherein the first metal body is made of tungsten metal and the second metal body is made of nickel metal. 6. A glass bulb, a rare gas and mercury sealed at a predetermined pressure inside the glass bulb, a fluorescent coating applied to an inner surface of the glass bulb, and sealed at both ends of the glass bulb. A pair of sealing metal bodies, comprising a pair of electrodes attached to the tip of the pair of sealing metal bodies located in the glass bulb, the electrode, a cylindrical metal body,
An intermediate metal body interposed between the sealing metal body and the cylindrical metal body, and a space formed between the cylindrical metal body, the intermediate metal body, and the sealing metal body. The sealing metal body, the intermediate metal body, and the cylindrical metal body are welded and fixed, and the space between the pair of electrodes is a cold cathode discharge tube facing the inside of the glass bulb. A light guide disposed in close proximity to the cold cathode discharge tube, a light reflector that reflects light emitted from the cold cathode discharge tube and makes light incident on the light guide, and a lower surface side of the light guide. An illumination device comprising: a light reflecting plate disposed; and a light control member disposed on an upper surface side of the light guide and controlling a direction of light emitted from the upper surface of the light guide.