JP3389971B2 - Discharge tube - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube provided with a pair of electrodes, and more particularly, to a discharge tube capable of reducing a non-light emitting region and shortening its overall length.

[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 filled with a rare gas and mercury vapor and a fluorescent film is coated on the inner wall of the glass tube has been conventionally used in a liquid crystal display. It is widely used as a light source for backlights. One end of the lead-in wire is connected to the pair of electrodes of the cold cathode discharge tube, and the other end of the lead-in wire is led out from both ends of the glass tube. When a voltage is applied between the pair of electrodes, electrons are emitted from one of the electrodes, and the electrons collide with mercury atoms in the glass tube to generate ultraviolet rays. The wavelength of this ultraviolet ray is converted into visible light by the fluorescent film formed on the inner wall of the glass tube.

A conventional cold cathode discharge tube (40) shown in FIG. 3 has a lead-in wire (11) and a lead-in wire (11) formed by fusing a first lead-in wire constituent member (14) and a second lead-in wire constituent member (15). The electrode assembly shown in FIG. 4 (c), which comprises a cup-shaped electrode (3) fixed to the lead-in wire (11).
(20), a glass tube (7) in which the electrode assembly (20) is fixed at both ends and is filled with a discharge gas, and a lead-out portion (28) of the introduction wire (11) outside the glass tube (7). ) Connected to external lead (8)
And a fluorescent film (9) which covers the inner surface (7a) of the glass tube (7) and emits visible light upon being irradiated with ultraviolet rays generated by discharge between the electrodes (3). The lead-in line (11) is
8), an embedded part (29) formed in the glass tube (7), and a coupling part (16) connecting the lead-out part (28) and the embedded part (29).

In manufacturing the cold cathode discharge tube (40), first, the first lead wire constituting member (14) made of nickel, which is excellent in solderability, and the first lead wire constituent member (14) made of tungsten, which is excellent in glass fusion property, are first prepared. Two
Introducing wire (11) shown in FIG. 4 (a) fused with the introductory wire constituting member (15), and glass beads (2) formed in a cylindrical shape,
Prepare an electrode (3) made of nickel. The diameters of the first and second lead wire components (14, 15) are substantially equal. next,
As shown in FIG. 4 (b), the second introduction line constituting member (15) of the introduction line (11) is inserted into the hole (2a) of the glass bead (2), and the protrusion (11a) is attached to the glass bead (2). ), The glass beads (2) are fused to the second introducing wire constituting member (15). The hole (2a) of the glass bead (2) has a diameter smaller than that of the joining portion (16) and larger than that of the second introducing wire constituting member (15), and the joining portion (16) allows the glass bead (2) to be formed. The fusion bonding position of is set. Then, as shown in FIG. 4 (c), the tip (11b) of the protrusion (11a) is welded to the outer bottom surface (3a) of the electrode (3) to form an electrode assembly (20), which has a cylindrical shape. The electrode assemblies (20) are arranged on both ends of the glass tube (7). After filling the glass tube (7) with a discharge gas containing a rare gas and mercury vapor, when the glass beads (2) are fused to the glass tube (7),
As shown in FIG. 4 (d), the electrode (3) and the embedded portion (29) are sealed in the glass tube (7), and the coupling portion (16) and the lead-out portion (28) are outside the glass tube (7). It will be in the state derived to. Derivation part (28)
After being cut to an appropriate length, the external leads (8) are soldered to form the cold cathode discharge tube (40) shown in FIG.

[0005]

[Problems to be Solved by the Invention] The cold cathode discharge tube (40)
Then, since the first and second introduction line constituting members (14, 15) have substantially the same diameter, when they are fused together as shown in FIG.
As shown in (a), the molten metal hump has first and second
Larger than the diameter of the lead-in wire components (14, 15) of the joint (16)
Is formed. In the case of nickel and tungsten having a diameter of about 0.8 mm, the length (L) of the joint portion (16) shown in FIG. 4 (a) is about 0.6 mm. For this reason, the external lead (8)
When connecting to (28), as shown in FIG.
It is not possible to downsize the cold cathode discharge tube (40) because it is necessary to solder the external lead (8) to a position apart from the glass tube (7) and the coupling portion (16) instead of 6). . Since this joint portion (16) is, so to speak, a non-luminous region, if the joint portion (16) is large, the luminous efficiency is reduced. It is possible to solder the external leads (8) to the bumps of the joint (16) in order to reduce the non-light emitting area, but the joint (16) has a curved surface and an irregular shape, and moreover nickel Solderability is poor due to the fusion of tungsten and tungsten, and external leads (8)
Is easy to come off. Therefore, the connection strength between the external lead (8) and the lead-out portion (28) cannot be sufficiently obtained, which causes a connection failure.

[0006] Therefore, an object of the present invention is to provide a discharge tube in which the non-luminous region is made small to be miniaturized. Another object of the present invention is to provide a discharge tube that strengthens the connection between the discharge tube and the external lead and prevents connection failure.

[0007]

The discharge tube according to the present invention comprises:
Metal lead-in wire (1) and electrode (3) fixed to the lead-in wire (1)
An electrode assembly (10) provided with a glass tube (7) in which the electrode assembly (10) is fixed at both ends and is filled with a discharge gas.
And a fluorescent film (9) which is coated on the inner surface of the glass tube (7) and emits visible light upon irradiation with ultraviolet rays generated by discharge between the electrodes (3). Introductory line (1) is a glass tube
The lead-out portion (18) arranged outside both ends of (7) and the lead-out portion (1
8) having a smaller diameter and an embedded portion (19) sealed in the glass tube (7) together with the electrode (3), and the embedded portion (19) is a lead-out portion.
It is made of a material different from that of (18). A tapered diameter-reduced portion (6) whose diameter decreases from the lead-out portion (18) toward the embedded portion (19) is formed between the embedded portion (19) and the lead-out portion (18). The glass beads (2) locked to the reduced diameter portion (6) are fused to the glass tube (7).

Metal bumps are not formed on the reduced diameter portion (6), and the total length of the discharge tube can be shortened. That is, when connecting the lead wire to the lead-in wire (1), since it can be connected to the reduced diameter portion (6) formed at the position closest to the glass tube (7), the non-light emitting area can be reduced and sufficient light emission can be achieved. The amount can be secured and the discharge tube can be downsized. Further, when connecting the lead wire to the lead-in wire (1), the lead wire can be firmly and reliably connected to the reduced diameter portion (6), and after the connection, the lead wire and the reduced diameter portion (6) have a poor connection. Does not occur.

In the embodiment of the present invention, the derivation unit (18) is
The buried portion (19) is made of nickel, the buried portion (19) is made of tungsten, and the reduced diameter portion (6) is made of a mixed metal of nickel and tungsten. Outside the glass tube (7) has an external lead (8) connected to the lead-in wire (1), the external lead (8) being the lead-in wire
It is fixed to the lead-out portion (18) or the reduced diameter portion (6) of (1).

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a discharge tube according to the present invention will be described below with reference to FIG. A cold cathode discharge tube (30) according to the present embodiment shown in FIG. 1 includes an electrode assembly (1) made of metal and a cup-shaped electrode (3) fixed to the introduction wire (1) ( 10), a glass tube (7) in which the electrode assembly (10) is fixed at both ends and is filled with a discharge gas, and a glass tube (7)
External lead (8) externally connected to the lead-in wire (1) and glass tube
Fluorescent film coated on the inner surface (7a) of (7) and emitting visible light upon irradiation with ultraviolet rays generated by the discharge between the electrodes (3)
(9) and are provided. The metal introduction wire (1) of the electrode assembly (10) is fused with a cylindrical glass bead (2), and the electrode (3) is formed by connecting the glass bead (2) and the glass tube (7). Are sealed in the glass tube (7).

In the present invention, the lead-in wire (1) is made up of a lead-out portion (18) formed outside both ends of the glass tube (7) and a glass having a smaller diameter than the lead-out portion (18) and the electrode (3). An external lead (8), which is a lead wire, is provided with a buried portion (19) sealed in a pipe (7), and a reduced diameter portion (6) and a lead-out portion (18) coupled to the buried portion (19). Are connected. For this reason, the conventional cold cathode discharge tube shown in FIG. 3 in which the external leads (8) are connected apart from the glass tube (7).
Different from (40), in the present embodiment, the total length of the cold cathode discharge tube (30) can be shortened.

The difference in diameter between the lead-out portion 18 and the buried portion 19 is 0.2 to 3.0 mm. If the difference in diameter is less than 0.2 mm, a hump having a diameter larger than that of the lead-out portion (18) is formed in the reduced diameter portion (6), and if it exceeds 3.0 mm, the taper angle of the reduced diameter portion (6) is increased. It becomes a steep slope, and in both cases, the connectivity between the reduced diameter portion (6) and the external lead (8) deteriorates.

In the method of manufacturing the cold cathode discharge tube (30) according to the present embodiment, first, the first lead wire constituting member made of nickel is formed.
(4) and the second lead-in wire constituent member (5) made of tungsten having a smaller diameter than the first lead-in wire constituent member (4) are fused,
The introduction line (1) shown in FIG. 2 (a) is formed.

Since the external lead (8) is connected to the lead-in wire (1) by soldering, the first lead-line forming member
For (4), nickel with excellent solderability is used. Also,
Second lead wire constituent member (5) to which glass beads (2) are fused
Uses tungsten, which has a good fusion property with glass. Therefore, the reduced diameter portion (6), which is the connection point between the first introduction line constituent member (4) and the second introduction line constituent member (5), is a metal in which nickel and tungsten are mixed, The first lead wire component (4) made of nickel is the second lead wire made of tungsten.
Since it has a large diameter and a low melting point, it contains a large amount of nickel as compared with the introduction wire constituting member (5). The reduced diameter portion (6) is formed in a taper shape in which a hump is not formed and the diameter gradually decreases from the first introduction line forming member (4) to the second introduction line forming member (5). The diameter is, for example, the first lead wire constituent member.
(4) is about 0.8 mm, and the second introduction line forming member (5) is about 0.5 mm.

The lead-in wire (1) is inserted into the hole (2a) of the glass bead (2) from the side of the second lead-in wire constituting member (5), and as shown in FIG. ) The glass beads (2)
Project from. When the glass beads (2) are inserted into the introduction line (1), the introduction line (1) is vertically arranged so that the first introduction line constituent member (4) is on the lower side, and the glass is inserted from above. beads
Insert (2). Holes formed in glass beads (2)
Since the diameter of (2a) is smaller than the diameter of the first introduction line forming member (4) and slightly larger than the diameter of the second introduction line forming member (5), the glass beads (2) are reduced in diameter (6). ) Is locked. Since the glass beads (2) are shorter than the second lead wire constituent member (5),
When the introduction wire (1) is inserted into the glass beads (2), the second introduction wire constituent member (5) slightly protrudes from the glass beads (2) to form a protrusion (1a) having a length of 0.5 to 30 mm. Form.

Next, as shown in FIG. 2 (c), the tip (1b) of the projection (1a) is welded to the outer bottom surface (3a) of the cup-shaped nickel electrode (3). Tip (1b) of protrusion (1a)
And the outer bottom surface (3a) of the electrode (3) are brought into contact with each other, and an electric current is passed between them to weld the both. At this time, glass beads (2)
Since it is not fused to the introduction line (1), even if the heat generated during welding is transferred to the glass beads (2) side, cracks due to the difference in linear expansion coefficient between metal and glass
It does not occur in (2). Therefore, the length of the protruding portion (1a), it is sufficient to ensure only the minimum length required to perform good welding, after fusion of the glass beads (2) and the introduction line (1). It can be set shorter than the protrusion (11a) of the conventional method shown in FIG. 4 for welding the electrode (3). For example, in order to prevent the glass beads (2) from cracking, the length of the conventional protrusion (11a) needs to be at least about 0.7 mm, whereas in the present embodiment, the length of the protrusion (1a) is required. Can be set to about 0.2 mm. Lead-in line (1)
The glass beads (2) are sandwiched between the reduced diameter portion (6) and the electrode (3) by welding the electrode (3) and the electrode (3), and the glass beads (2) do not come off from the lead-in wire (1). After that, the glass beads (2) are fused to the second introducing line constituting member (5) and the introducing line shown in FIG.
(1), the glass beads (2) and the electrode (3) are integrally fixed to each other to form an electrode assembly (10).

The electrode assembly (10) has a fluorescent film (9) on the inner surface (7a).
Are placed in a coated cylindrical glass tube (7). The electrode assembly (10) is coaxial with both ends of the glass tube (7) with the electrodes (3) facing inward with the glass tube (7) inserted in a chamber (container) that can be sealed. Will be placed. After that, the chamber is closed, and a discharge gas consisting of one or more rare gases of neon gas, argon gas, and xenon gas, and metal vapor such as mercury vapor is applied to the glass tube at a pressure of about 5.3 to 13 kPa. Fill in (7). Both ends of the glass tube (7) filled with the discharge gas and the glass beads (2) are heated in an electric furnace or the like provided in the chamber, and the glass beads are heated.
By fusing (2) to the glass tube (7), the glass tube (7)
Close both ends of. This allows the electrode (3) to pass through the glass tube (7).
While being sealed inside, the embedded portion (19) of the lead-in wire (1) is formed in the glass tube (7). Further, although the reduced diameter portion (6) and the lead-out portion (18) are formed outside the glass tube (7), the reduced diameter portion (6) is embedded in the glass tube (7) as shown in FIG. 2 (e). The buried length (A) is 0.5 mm or less.

Finally, after cutting the leading end side of the lead-out portion (18) arranged outside the glass tube (7), the lead-out portion (18) and the reduced diameter portion
Solder the external lead (8) to (6). Since the external lead (8) can be connected to the reduced diameter portion (6) close to the glass tube (7), the total length of the cold cathode discharge tube (30) can be shortened.

[0019]

As described above, according to the present invention, it is possible to reduce the size of the discharge tube and prevent the connection failure between the discharge tube and the external lead to improve the strength and durability of the discharge tube.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a discharge tube according to the present invention.

FIG. 2 is a sectional view showing a method of manufacturing a discharge tube according to the present invention.

FIG. 3 is a sectional view showing an embodiment of a conventional discharge tube.

FIG. 4 is a sectional view showing a conventional method of manufacturing a discharge tube.

[Explanation of symbols]

(1) ・ ・ Introduction line, (1a) ・ ・ Projection part, (1b) ・ ・ Tip,
(2) ・ ・ Glass beads, (2a) ・ ・ Hole, (3) ・ ・ Electrode,
(3a) ... Outer bottom surface, (4) .. First lead wire component member,
(5) ・ ・ Second lead wire component, (6) ・ ・ Reduced diameter part,
(7) ・ ・ Glass tube, (7a) ・ ・ Inner surface, (8) ・ ・ External lead, (9) ・ ・ Fluorescent film, (10) ・ ・ Electrode assembly, (18)
・ ・ Leading part, (19) ・ ・ Buried part, (30) ・ ・ Cold cathode discharge tube, (A) ・ ・ Buried length,

Claims (3)

(57) [Claims] 1. An electrode assembly comprising a metal lead wire and electrodes fixed to the lead wire; a glass tube having the electrode assembly fixed at both ends and filled with a discharge gas;
A fluorescent film which is coated on the inner surface of the glass tube and emits visible light upon being irradiated with ultraviolet rays generated by the discharge between the electrodes, and the introduction line is arranged outside both ends of the glass tube. A lead-out portion and a buried portion that has a diameter smaller than that of the lead-out portion and is sealed in the glass tube together with the electrode, wherein the buried portion is a discharge tube formed of a material different from that of the lead-out portion, The glass beads that form a tapered diameter-reduced portion having a diameter that decreases from the lead-out portion toward the embedded portion between the embedded portion and the lead-out portion and lock the reduced diameter portion are the glass tube. Discharge tube characterized by being fused to. 2. The lead-out portion is made of nickel,
The discharge tube according to claim 1, wherein the buried portion is made of tungsten, and the reduced diameter portion is made of a mixed metal of nickel and tungsten. 3. An outer lead connected to the lead wire outside the glass tube, the outer lead being fixed to a lead-out portion or a reduced diameter portion of the lead wire. The discharge tube described in.