JP2002170522A - Discharge tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a discharge tube capable of properly preventing a damage of a sealing part by a heat effect when soldering a lead wire to a metal body forming at least a part of a main electrode sealed in a glass bulb, or by a stress effect when folding a metal body to an L-shape. SOLUTION: A discharge tube comprises a glass tube in which rare gas is sealed in, and also a pair of main electrodes are sealed in at its both ends. An inserting hole of a predetermined length corresponding to a width of a soldering prohibited area or a folding prohibited area is provided at an exposed part of the metal body outside the sealing part. An auxiliary tool which is inserted into the metal body and abuts on the end of the sealing part is also provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube, and more particularly, to a cold cathode discharge tube used as a light source of a lighting device of a liquid crystal display device such as a personal computer, a word processor and a liquid crystal television.

[0002]

2. Description of the Related Art In recent years, cold cathode discharge tubes have been known as light sources for backlights of liquid crystal display devices such as personal computers and word processors. Such a cold cathode discharge tube has been widely used in liquid crystal display devices, particularly because of its high luminance, low power consumption, and low lighting start voltage.

FIGS. 4 and 5 are sectional views showing one example of the cold cathode discharge tube. Reference numeral 1 denotes a glass bulb in which mercury is sealed together with a discharge gas such as neon or argon. Main electrodes 3 (6) are sealed and attached to the sealing portions 2 and 2 at both ends of the glass bulb 1, respectively. This pair of main electrodes 3, 3 (6,
In 6), a bead glass 5 having substantially the same thermal expansion coefficient as that of the glass bulb 1 is fixed, and sealed at both ends of the glass bulb 1 via the bead glass 5.

For the main electrodes 3, 3 (6, 6), a metal body 4 (7) forming the main electrode is used, and materials such as tungsten, nickel, and dumet are mainly used. Then, the metal body 4 (7) is connected to a known device such as an inverter circuit via a lead wire or directly connected to an electric board. In the former case shown in FIG. 4, the tip of the lead wire is wound around an exposed portion where the metal body forming the main electrode 3 projects outside the sealing portion of the glass bulb 1, and soldering is performed on the connection portion. In the latter case shown in FIG. 5, connection is made by passing a bent portion of the metal body 7 bent at about 90 degrees to form a main electrode through a hole in the substrate and soldering the inserted portion from the back surface of the substrate. Is done.

The metal member 4 (7) forms the main electrode itself. As the electrode, a sintered metal member or a cylindrical metal member is connected to the tip of the metal member located in the glass bulb. There is also a configuration that has

[0006]

The above-mentioned main electrode 3
As the metal body forming at least a part of (6), a single nickel wire or a Kovar wire is used. For example, a tungsten wire is used for a sealing wire extending from the sealing portion 2 to the inside of the glass bulb 1. There is a wire formed by welding a nickel wire to form a protruding wire from the sealing portion 2, or a wire using a Kovar wire or a Dumet wire as a sealing wire instead of a tungsten wire.

On the other hand, devices incorporating such a discharge tube are required to have a small diameter as the discharge tube in order to reduce the size and weight. Recently, the discharge tube having an outer diameter of 2 mm or less has been put to practical use. In the case of a discharge tube having a small diameter, the sealing line and the protruding line from the sealing portion are of course a thin line of 1 mm or less, and the sealing portion of the glass bulb is inevitably weak in strength. When soldering a lead wire to such a protruding wire of the discharge tube, if the heat of the solder is directly applied to the sealing part or the solder comes close to the sealing part, the heat of the solder causes distortion or cracks in the sealing part having weak strength. The sealing part may be damaged by entering.

In the case where the protruding line is bent as shown in FIG. 5, stress is applied to the sealing portion if it is bent right at the sealing portion, so that the sealing portion becomes distorted or cracked and the sealing portion becomes brittle. Will be damaged. The adverse effects of these soldering and bending slightly differ depending on the material of the glass bulb of the discharge tube, the material of the sealing line, the protruding wire, etc. However, the outer diameter of the glass bulb of the discharge tube is 1.8 mm to 6 mm. And the diameter of the sealing line and the protruding line is 0.5 mm to 1.5 m.
The combination of m tends to occur easily.

Therefore, when the lead wire shown in FIG. 4 is soldered, it is not preferable to solder the lead wire in the range of the width dimension D from the end of the sealing portion 2 of the glass bulb 1.
When bending the metal body 7 shown in FIG. 5, it is not preferable to bend the range of the width dimension D from the end of the sealing portion 2. Width D of the area where such soldering or bending is prohibited
Is required to be 0.75 mm or more.

Therefore, the present invention has been made in view of the above-mentioned conventional problems, and has been made in consideration of the thermal effect of soldering a lead wire to a metal body and the stress at the time of bending the metal body into an L-shape. An object of the present invention is to provide a discharge tube capable of suitably preventing a sealing portion of a glass bulb from being damaged by an influence.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and the present invention relates to a discharge tube having a main electrode sealed at both ends of a glass bulb filled with a rare gas. A metal body that has a portion exposed outside the sealing portion of the glass bulb and forms at least a part of the pair of main electrodes, and a width corresponding to a predetermined length from the position of the sealing portion end in the exposed portion; And an auxiliary tool which is in contact with the end of the sealing portion and is inserted into the exposed portion of the metal body.

With this configuration, if the auxiliary tool inserted into the metal body is in contact with the sealing portion of the glass bulb, the metal body has no soldering prohibited area or bending prohibited area in the insertion hole. Is hidden, and the auxiliary tool becomes a hindrance, so that neither soldering nor bending this area is possible.

According to a second aspect of the present invention, if the diameter of the insertion hole is substantially the same as the diameter of the metal body, the movement of the auxiliary tool can be restricted. If it is formed in a tapered shape that gradually expands from a diameter approximately the same as the body, the work of inserting the metal body into the insertion hole becomes easy, the workability is improved, and the radial movement of the auxiliary tool is suitably restricted. be able to.

[0014] As described in the fourth and fifth aspects, the auxiliary tool may be made of a resin material or a metal material.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a main part in a state where an auxiliary tool is attached to a cold cathode discharge tube. In FIG. 1, reference numeral 1 denotes a glass bulb, and sealing members 2 and 2 at both ends thereof are used as a main electrode 3 as a pin-shaped metal body such as Kovar or Dumet having a larger thermal expansion coefficient than tungsten or nickel. Are sealed and attached via a bead glass 5.

The glass bulb 1 has an outer diameter of several mm or less, for example, 1.8 mm to 3 mm, and the metal body has a diameter of 2 mm or less, for example, about 1 mm. Is used. Further, as the main electrode 3, a sintered metal body or a cylindrical metal body (not shown) obtained by sintering a conductive metal oxide powder is fixed to the inner end of a metal rod by welding or caulking. It may be made of.

Further, a fluorescent film is applied to the inner surface of the glass bulb 1 and mercury is sealed inside the glass bulb 1 together with a discharge gas such as neon or argon.

The exposed portion of the metal body 4 of the main electrode 3 protruding outside the sealing portion of the glass bulb 1 is soldered with a lead wire or bent into an L-shape to be attached to a circuit board. This is the part that receives power supply. An auxiliary tool 8 made of iron or nickel is mounted on each of the pair of metal bodies 4 and 4.

As shown in FIG. 2, the auxiliary member 8 is a circular member having a diameter smaller than the outer diameter of the glass bulb 1 and has an insertion hole 9 for inserting the metal body 4 at the center position. It is formed in a ring shape. The width D of the auxiliary tool 8 is a size corresponding to (coincident with) the width of the above-described soldering prohibition region or bending prohibition region of the metal body, and makes it impossible to contact the region.

The insertion hole 9 is a straight hole having substantially the same diameter as the metal body 4, that is, a straight hole having a diameter of about 1 mm, so that movement in the radial direction is restricted. As shown in FIG. 3, the hole may be a tapered hole whose minimum diameter allows the insertion of the metal body 4, that is, the diameter is substantially the same as that of the metal body 4, and the diameter gradually increases. In the case of the auxiliary tool of FIG. 3, by inserting the metal member 4 from the larger diameter into the metal member 4, the thin metal member 4 easily enters the insertion hole 10 and the workability is improved.

Since the cold-cathode discharge tube according to the present embodiment has the above-described configuration, soldering is not performed in the soldering prohibited area (area of width D). Also, the insertion hole 9 of the auxiliary tool 8
In (10), since the outer opening is filled with the metal body 4 and closed, the solder does not enter the prohibited area due to osmotic pressure. Further, since the metal member 4 in the insertion hole 9 (10) cannot be bent, the bending is not performed in the prohibited area. When the exposed portion of the metal body 4 is bent, the edge of the opening outside the insertion hole 9 of the auxiliary tool 8 serves as a fulcrum, so that the metal body 4 can be bent neatly at a right angle.

It should be noted that the present invention is not limited to the above embodiment, and various changes can be made without departing from the gist of the present invention. For example, the auxiliary tool can be made of a resin material or a ceramic material because it is excellent in non-conductivity and heat-blocking properties instead of a metal material. If a notch communicating with the insertion hole is formed in a part of the auxiliary tool, the auxiliary tool can be removed from the metal body after the soldering or bending of the lead wire is completed.

In the above embodiment, the entire main electrode is constituted by one metal body. However, the main electrode is formed of a metal body which is sealed in the sealing portion of the glass bulb and protrudes into the glass bulb. It may be configured by attaching the above-mentioned sintered metal body or ordinary metal body to the tip.

Further, the shape of the auxiliary tool is not limited to a circular shape, but it is located outside the outer peripheral surface of the glass bulb so that the auxiliary tool does not hinder the lighting device when the lighting apparatus is installed in a device. It is more preferable that the shape and size do not protrude.

The kind of the discharge tube is not limited to the one having the sealing portion of the above-described form, but is intended for all discharge tubes that may cause the same kind of problem. It is not limited to.

[0026]

As described above, according to the present invention, a soldering area or a bending-inhibited portion is exposed at an exposed portion outside a glass bulb sealing portion of a metal body which is sealed in a glass bulb and forms at least a part of a main electrode. An auxiliary tool having an insertion hole having a predetermined length corresponding to the width of the length of the region is provided. In a state where the metal body is inserted through the metal body exposed portion outside the glass bulb sealing portion, the soldering prohibited area or the bending prohibited area is accommodated in the insertion hole. In other words, the sealing portion is inserted by the insertion hole. As a result, it is impossible to solder in the soldering prohibited area and to bend the bending prohibited area, so that the heat effect when soldering the lead wire to the metal body and the L It is possible to suitably prevent damage to the sealing portion due to the influence of stress when bending in a letter shape.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a cold cathode discharge tube according to an embodiment of the present invention.

FIG. 2 is a perspective view of an auxiliary tool of the cold cathode discharge tube of the present invention.

FIG. 3 is a perspective view showing an auxiliary tool of another embodiment of the cold cathode discharge tube of the present invention.

FIG. 4 is a sectional view of a main part of a conventional cold cathode discharge tube.

FIG. 5 is a sectional view of a main part of another conventional cold cathode discharge tube.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Glass bulb 2 Sealing part 3 Main electrode 4 Metal body 5 Bead glass 6 Main electrode 7 Metal body 8 Auxiliary tool 9,10 Insertion hole

Claims (5)

[Claims] 1. A discharge tube in which a pair of main electrodes are sealed at both ends of a glass bulb in which a rare gas is sealed, the discharge bulb having a portion exposed outside a sealing portion of the glass bulb. A metal body forming at least a part of an electrode; and an insertion hole having a length corresponding to a width of a predetermined length from a position of the end of the sealing portion in the exposed portion of the metal body. A discharge tube provided with an auxiliary tool which is in contact with the metal member and is inserted into the exposed portion of the metal body. 2. The discharge tube according to claim 1, wherein the insertion hole has substantially the same diameter as the metal body. 3. The discharge tube according to claim 1, wherein the insertion hole is formed in a tapered shape that gradually expands from a diameter substantially equal to that of the metal body. 4. The discharge tube according to claim 1, wherein the auxiliary member is made of a resin material. 5. The discharge tube according to claim 1, wherein the auxiliary member is made of a metal material.