JP2003109534A - Cold cathode discharge tube and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten the lead of the cold cathode discharge tube. SOLUTION: A glass tube (5) in which rare gas and discharge gas are filled in sealed state, a pair of leads (6) that have an embedded part (6a) fixed at both ends of the glass tube (5), and an electrode (3) that is arranged in the glass tube (5) and fixed at each inner side part (6b) of the pair of leads (6) are provided in the cold cathode discharge tube. The main body of the lead (6) of which the inner side part (6b) and the lead-out part (6) are integrated by a single metal material selected from tungsten or a metal having a melting point lower than tungsten and which does not have a welded lump (12) and is shortened without jointing the inner side part (6a) and the lead-out part (6c) can be manufactured.

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 more particularly to a cold cathode discharge tube in which a shortened lead is attached to an end of a glass tube and a method for manufacturing the same.

[0002]

2. Description of the Related Art A cold cathode discharge tube in which a pair of electrodes are arranged to face each other inside a glass tube in which a rare gas and mercury vapor are sealed and a fluorescent film is coated on the inner wall of the glass tube is a liquid crystal display. It is widely used as a light source for backlights. The cold cathode discharge tube (1) shown in FIG. 3 (d) is composed of a glass tube (5) in which an internal cavity (5b) is filled with mercury vapor, and a pair of electrodes arranged at both ends of the glass tube (5). (3), a fluorescent film (5a) coated on the inner wall of the internal cavity (5b), a lead (6) connected to the electrode (3) and led out from the glass tube (5), and a lead (6) And an external terminal (10) connected to. When a voltage is applied between the pair of electrodes (3), electrons are emitted from one electrode (3), and the electrons collide with mercury atoms or molecules in the glass tube (5) to generate ultraviolet rays. This ultraviolet ray is a fluorescent film (5a) formed on the inner wall of the internal cavity (5b) of the glass tube (5).
The wavelength is converted into visible light by means of which the visible light is emitted to the outside of the glass tube (5).

When forming the electrode assembly (11) shown in FIG. 3 (c), as shown in FIG. 3 (a), the inner part made of tungsten is used.
The lead (6) is formed by joining the (6b) and the lead-out portion (6c) made of nickel by resistance welding. When performing resistance welding, the inner portion (6b) and the lead-out portion (6c) are pressed against each other, an electric current is applied while applying a compressive force to heat and melt the joint, so that a bulge that protrudes outward in the radial direction ( 12) is the inner part (6b) and the lead-out part (6b)
It is formed at the joint with c). Next, as shown in FIG. 3 (b), the lead (6) is inserted into the through hole of the cylindrical glass bead (2) so that the glass bead (2) is embedded in the inner part (6b) (6a). After fusing, the electrode (3) made of nickel is resistance-welded to the end of the inner part (6b) to complete the electrode assembly (11) as shown in FIG. 3 (c). Then, as shown in FIG. 3 (d), a fluorescent film (5
The electrode (3) is placed in a cylindrical glass tube (5) coated with a), and the glass beads (2) are fused to the end of the glass tube (5).
Noble gas and mercury vapor are supplied from the other end of the glass tube (5) into the internal cavity (5b) of the glass tube (5), and the leads (6) are fused to the other parts of the glass tube (5) in the same manner as above. When fixed to the end, the lead-out part
(6c) is led out of the glass tube (5), and the electrode (3) and the inner part (6b) are sealed in the glass tube (5). Furthermore, the derivation part (6
c) is cut into a predetermined length, and the external terminal (10) is fixed to the lead-out portion (6c) by soldering.

[0004]

As described above, in the conventional cold cathode discharge tube, when the lead (6) is manufactured, the inner portion (6b)
Since it is necessary to weld the lead-out portion and the lead-out portion (6c), the manufacturing cost becomes high. Further, a welding hump (12) protruding radially outward is formed between the inner portion (6b) and the lead-out portion (6c), and the welding hump (1
The entire length of the cold cathode discharge tube becomes longer by the length of 2). At the same time, the non-light emitting region that does not contribute to light emission becomes long, and the effective light emission length of the cold cathode discharge tube is shortened, resulting in a decrease in light emission efficiency. Moreover, when the lead (6) is manufactured by satisfactorily welding and joining the inner portion (6b) and the lead-out portion (6c), the lead portion (6) having a wire diameter of less than 0.5 mm is connected to the inner portion (6b). Since the adhesion efficiency of the lead-out part (6c) is reduced and sufficient mechanical strength cannot be obtained at the joint part, a lead (6) with a wire diameter of 0.5 mm or more is required, making it difficult to make a glass tube into a thin tube. Become.

Therefore, it is an object of the present invention to provide a cold cathode discharge tube having a shortened lead without welding humps and a method for manufacturing the same.

[0006]

A cold cathode discharge tube according to the present invention is a glass tube (5) filled with a rare gas and a discharge gas in a sealed state, and fixed to both ends of the glass tube (5). A pair of leads (6) having a buried portion (6a), an electrode (3) arranged inside the glass tube (5) and fixed to each inner portion (6b) of the pair of leads (6), The glass tube (5) is provided with a fluorescent film (5a) which is coated inside and emits visible light upon being irradiated with ultraviolet rays generated by the discharge of the electrode (3). Inside part
(6b) and the lead-out part (6c) are not joined, and embedded in a shortened length without a welding bump (12) by a single metal material selected from tungsten, a tungsten alloy, and a metal having a melting point lower than that of tungsten. Part (6a), inner part (6b) and glass tube
The main body of the lead (6) having the lead-out portion (6c) led out from (5) can be formed in an integral shape. The embedded portion (6a) of the lead (6) having a surface of tungsten or a tungsten alloy having high glass adhesion is fixed to the glass tube (5).
The lead-out portion (6c) of the lead (6) has a metal surface having a melting point lower than that of tungsten and high solder adhesion.

The lead (6) is integrally formed of tungsten or a tungsten alloy, and the lead-out portion (6) of the lead (6) is formed.
The outer metal coating (8) formed of a metal having a melting point lower than that of tungsten on the outer peripheral surface of c) is electrically connected to the external terminal (10) by soldering.

In another embodiment of the present invention, the outer peripheral surface of the embedded portion (6a) of the lead (6) integrally formed of a metal having a melting point lower than that of tungsten is made of tungsten or a tungsten alloy having excellent glass adhesion. Since the glass tube (5) is fused to the formed inner metal coating (9), the glass tube
(5) adheres to the inner metal coating (9). The metal having a lower melting point than tungsten is selected from nickel, copper, iron, gold or silver or an alloy of nickel, copper, iron, gold and silver.

The method of manufacturing a cold cathode discharge tube according to the present invention comprises a step of forming a lead (6) with tungsten or a tungsten alloy, and an electrode (3) fixed to one end of the lead (6) to form a cylindrical glass bead ( Inserting the lead (6) into the through hole of 2) and forming the outer metal coating (8) on the other end of the lead (6) with a metal material selected from metals having a lower melting point than tungsten, and a pair of glass beads. Heat (2) and reed (6)
And the step of fusing the glass beads (2) to both ends of the glass tube (5) while fusing to the embedded portion (6a).

Another cold cathode discharge tube manufacturing method according to the present invention is
A step of forming the lead (6) with a metal having a melting point lower than that of tungsten, and attaching tungsten to the lead (6) by sputtering to form an inner metal film (9) on the embedded portion (6a) of the lead (6). And a step of fixing the electrode (3) to one end of the lead (6) before or after forming the inner metal coating (9), and inserting the lead (6) into the through hole of the cylindrical glass bead (2). And heating the pair of glass beads (2) to fuse them to the embedded portion (6a) of the lead (6) and fuse the glass beads (2) to both ends of the glass tube (5). .

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a cold cathode discharge tube and a method for manufacturing the same according to the present invention will be described below with reference to FIGS. 1 and 2, the same parts as those shown in FIG. 3 are designated by the same reference numerals and the description thereof will be omitted. In the cold cathode discharge tube (1) according to the present embodiment shown in FIG. 1 (e), the structure and manufacturing method of the electrode assembly (11) are different from those of the prior art. That is, as shown in FIG. 1 (a), without performing the welding process, the inner portion (6b)
The lead (6) including the lead-out portion (6c) can be integrally manufactured from tungsten or a tungsten alloy in a short time. An outer metal coating (8) made of nickel having a lower melting point than tungsten is formed on the outer peripheral surface of the lead-out portion (6c) of the lead (6). The outer metal coating (8) is formed on the lead-out portion (6c) of the lead (6) by, for example, applying nickel plating or a nickel cap and caulking. Next, Fig. 1 (b)
Attach the cylindrical glass beads (2) to the inner lead (6) of the outer metal coating (8), and then lead the electrode (3) as shown in Fig.
After bonding to the inner part (6b) of (6), the glass beads (2) are fused to the leads (6) to form the electrode assembly (11). In this case, the glass beads (2) are in close contact with and fused to the leads (6) formed of tungsten or a tungsten alloy having excellent glass adhesion (glass wettability). Glass has a lower melting point than 900 ° C than tungsten and nickel, and has a lower melting point than 400 ° C than copper, iron, gold, and silver. Therefore, when glass beads (2) are heated, glass beads (2)
Only melted and embedded in the glass beads (2) or leads (6) (6
The embedded portion (6a) of the lead (6) and the glass beads (2) can be reliably fused to each other without damaging components such as a) by heating. As shown in FIGS. 1 (c) and 1 (d), the electrode (3)
After welding to the inner part (6b), the glass beads (2) are heated. When welding the electrode (3) to the inner part (6b) in a state where the glass beads (2) are not fused to the embedded part (6a), the linear expansion coefficient of the glass beads (2) and the embedded part (6a) Since no thermal stress is generated due to the difference, it is possible to prevent cracking of the glass beads (2) due to heat generated when welding the electrodes (3). In other words, even if the length between the end of the inner part (6b) to which the electrode (3) is connected and the embedded part (6a) is short, the glass beads
Since the crack generation of (2) can be prevented, the length of the inner portion (6b) can be shortened and the effective light emitting region can be expanded.
The lead 6 has a circular cross section with a diameter of, for example, about 0.25 mm or more and 0.5 mm or less. Reed (6) diameter 0.2
If it is less than 5 mm, when the glass beads (2) are fused to the embedding part (6a), the glass beads (2) are not only melted in the embedding part (6a) by heating, but also the ignition loss (Ignition Loss) Therefore, the thin wire lead (6) causes metal consumption. If the wire diameter exceeds 0.5 mm, the glass beads (2) for the embedded part (6a)
The external terminal (10) can be well fused and adhered to the lead-out portion (6c), but not only the cold cathode discharge tube is hindered from being thinned, but also the quality becomes excessive, and the material used is wasted. . The electrode (3) is welded and the inner portion (6b) of the lead (6) protruding inside the glass tube (5) and the embedded portion (6a) of the lead (6) where the glass beads (2) are fused. Total length with lead (6)
It is desirable to shorten the inner portion (6b) of the lead (6), which is a region that does not contribute to the effective light emitting region, as much as about 2/3 or more of the total length of the above. It is common to form the electrode (3) into a cup shape with nickel etc., which has excellent workability, but has sputtering resistance selected from tungsten, niobium, titanium, molybdenum, tungsten alloys, niobium alloys and titanium alloys. It can be made of metal to extend the life of the cold cathode discharge tube. In the cold cathode discharge tube, a sputtering action occurs in which ions of the discharge gas containing mercury or an inert gas collide with the electrode (3) during lighting, so that the electrode (3) and the mercury in the glass tube (5) are separated from each other. It is desirable to form the electrode (3) with a metal having a sputtering resistance, since it gradually wears. Further, the electrode (3) may be formed in any shape such as a plate shape, a linear shape and a spiral shape. The rare gas is one or more of neon gas, argon gas and xenon gas, and the discharge gas is metal vapor such as mercury vapor.

Thereafter, as in FIG. 3, when the electrode assembly (11) is attached to the glass tube (5), the embedded portion (6a) of the lead (6) having the surface of tungsten or tungsten alloy is
It is fixed to the glass tube (5). Although the product can be shipped at this stage, the external terminal (10) is finally attached to the outer end of the lead (6) through the outer metal coating (8) provided on the outer end of the lead (6). Are bonded with solder. Since nickel has good solder adhesion (solder wettability), as shown in Fig. 1 (e),
The external terminals (10) can be firmly adhered to the outer ends of the leads (6) by soldering.

FIG. 2 shows nickel, copper, iron, gold or silver, which has a lower melting point than tungsten, or nickel, copper, iron,
Lead integrally by metal selected from gold and silver alloy
(6) is formed, and an inner metal coating (9) made of tungsten or a tungsten alloy is formed on the outer peripheral surface of the embedded portion (6a) of the lead (6).
An example in which the As shown in FIG. 2 (a), after integrally forming the lead (6) with a metal having a melting point lower than that of tungsten, the lead (6) is formed on the outer peripheral surface of the embedded portion (6a) with tungsten having excellent glass adhesion or A lead (6) having a tungsten or tungsten alloy surface formed by sputtering an inner metal coating (9) made of a tungsten alloy.
The buried portion (6a) of is obtained. After that, the electrode (3) is welded to the end of the lead (6), and the glass beads (2) are attached to the inner metal coating (9).
Are fused to manufacture the electrode assembly (11). Furthermore, the electrode assembly (11) is fused to the end of the glass tube (5), and finally the lead (6) and the external terminal (10) are bonded by soldering.

In this embodiment, the following operational effects can be obtained. (1) The external terminal (10) can be satisfactorily soldered to the nickel outer surface of the lead-out portion (6c) led out of the glass tube (5). (2) The glass beads (2) can be well fused to the tungsten outer surface of the embedded portion (6a) to which the glass beads (2) are fused. (3) Since the main body of the lead (6) is integrally formed of a single metal material selected from tungsten, a tungsten alloy, and a metal having a melting point lower than that of tungsten, it is not necessary to weld a plurality of metal materials, and the manufacturing is performed. It is possible to simplify the process and reduce the cost. (4) The glass diameter of the cold cathode discharge tube (1), which can be manufactured without the welding step, by reducing the wire diameter of the lead (6) to 0.5 mm or less.
(5) can also be reduced in diameter. (5) By using the lead (6) having no welding hump, it is possible to shorten the total length of the non-luminous region or the cold cathode discharge tube.

[0015]

As described above, according to the present invention, it is not necessary to weld the inner and outer portions of the lead, the manufacturing process can be simplified and the cost can be reduced, and the welding hump can be omitted to lead out the lead. By shortening the length of the portion, the effective light emitting region is increased, and the brightness of the cold cathode discharge tube can be improved. Moreover, since the diameter of the lead can be reduced, the glass tube can be reduced in diameter.

[Brief description of drawings]

FIG. 1 is a process diagram showing a manufacturing process of a cold cathode discharge tube according to the present invention.

FIG. 2 is a process diagram showing a manufacturing process of a cold cathode discharge tube according to the present invention.

FIG. 3 is a process diagram showing a manufacturing process of a conventional cold cathode discharge tube.

[Explanation of symbols]

(1) ・ ・ Cold cathode discharge tube, (2) ・ ・ Glass beads, (3)
..Electrodes, (5) .. Glass tubes, (5a) .. Fluorescent films (6)
・ ・ Lead, (8) ・ ・ Outer metal coating, (9) ・ ・ Inner metal coating, (10) ・ ・ External terminal, (11) ・ ・ Electrode assembly,

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5C012 JJ01                 5C015 EE07                 5C043 AA12 BB04 DD11 DD17 EA01

Claims (6)

[Claims] 1. A glass tube in which a rare gas and a discharge gas are hermetically filled, a pair of leads having embedded portions fixed to both ends of the glass tube, and a glass tube disposed inside the glass tube. A cold cathode including an electrode fixed to each inner side of the pair of leads, and a fluorescent film coated inside the glass tube and emitting visible light upon irradiation with ultraviolet rays generated by discharge of the electrode. In the discharge tube, the lead having the buried portion, the inner portion, and the lead-out portion led out from the glass tube is integrally formed of a metal material selected from tungsten, a tungsten alloy, and a metal having a melting point lower than that of tungsten. Alternatively, the embedded portion of the lead having a surface of a tungsten alloy is fixed to the glass tube, and the lead-out portion of the lead is made of tungsten. A cold cathode discharge tube having a metal surface with a low melting point. 2. The lead is integrally formed of tungsten or a tungsten alloy, and an outer metal coating formed of a metal having a melting point lower than that of tungsten on the outer peripheral surface of the lead portion is electrically connected to an external terminal. The cold cathode discharge tube according to claim 1. 3. The lead is integrally formed of a metal having a melting point lower than that of tungsten, and the glass tube is fused to an inner metal coating formed of tungsten or a tungsten alloy on the outer peripheral surface of the embedded portion of the lead. The cold cathode discharge tube according to claim 1. 4. The metal having a melting point lower than that of tungsten is nickel, copper, iron, gold or silver or nickel,
The cold cathode discharge tube according to claim 1, which is selected from an alloy of copper, iron, gold, and silver. 5. A step of forming a lead with tungsten or a tungsten alloy, wherein an electrode is fixed to one end of the lead, the lead is inserted into a through hole of a cylindrical glass bead, and the other end of the lead has a melting point higher than that of tungsten. A step of forming an outer metal coating with a metal material selected from low-metal, and heating the pair of glass beads to fuse them to the embedded part of the lead and to fuse the glass beads to both ends of the glass tube. And a step of attaching the cold cathode discharge tube. 6. A step of forming a lead with a metal having a melting point lower than that of tungsten; a step of depositing tungsten on the lead by sputtering to form an inner metal coating on an embedded portion of the lead; Before or after forming, a step of fixing an electrode to one end of the lead and inserting the lead into a through hole of a cylindrical glass bead; heating a pair of the glass beads and fusing them to an embedded portion of the lead And a step of fusing the glass beads to both ends of the glass tube.