KR20060056884A - Electrode of cold cathode tube and its manufacturing method - Google Patents

Abstract

An electrode of a large cold cathode for displays such as a large-screen liquid crystal television set. The electrode comprises (a) a cup-shaped electrode body (a) composed of a cup- shaped electrode portion (10) mainly made of tungsten or molybdenum and a lead wire base (13) integrally led out of the bottom (11) of the cup- shaped electrode portion(10), (b) a lead wire end (14) electrically connected to the end of the lead wire base (13), having a melting point lower than that of the cup-shaped electrode body (a), and constituting a part of a lead wire (12) for power supply, and (c) a glass bead (15) so provide to surround the lead wire base (13) and welded to a sealing portion (16) of a sealing body (19) when the electrode is sealed. Since the lead wire base (13) is integrally provide to project from the bottom (11) of the cup-shaped electrode portion (10), only one portion, namely a welded portion (17) welded to the lead wire end (14), is welded, and consequently the step of welding the electrode (A1) is shortened to half. Further the problem of a conventional electrode caused when the bottom (21) of a cup-shaped electrode portion (20) is welded to a lead wire base (23) is solved 100%.

Description

Electrode of cold cathode tube and its manufacturing method

The present invention relates to a novel electrode of a cold cathode tube and a manufacturing method thereof.

The conventional electrode B has various shapes (Patent Document 1), but is welded to the cup-shaped electrode portion 20 and the bottom portion 21 of the cup-shaped electrode portion 20, for example, as shown in FIG. The lead wire 22 (the lead wire 22 is composed of the lead wire base 23 and the lead wire tip 24) and the lead wire 22 at the position near the cup-shaped electrode part 20 (here, the lead wire base 23 ) Is composed of glass beads 25 mounted to surround the periphery thereof.

The cup-shaped electrode part 20 is made of Ni, and is formed by a throttle press working, for example, has an outer shape (diameter) of 0.9 mm and a bottomed tubular shape having a length of about 3 mm. In addition, the lead wire 22 is the lead wire base 23 of the cobalt which is directly welded to the bottom portion 21 of the cup-shaped electrode portion 20, and " welded point is indicated by reference numeral 26 ". It is composed of a lead line tip 24 made of Ni to be abutted welded, the glass bead 25 is a butt weld portion 27 of the lead line base 23 and the lead line tip 24 as a reference numeral 6 in FIG. And slightly swollen together) and the cup-shaped electrode portion 20. These electrodes B are used after the glass beads 25 are fused to both ends of a thin straight tubular rod for cold cathode low pressure discharge lamps. 4, the glass bead 25 corresponds to the reference numeral 15 of FIG. 4, and is fused to both ends of the rod 19. As shown in FIG. The reason why the glass beads 25 are used is to fill the gap between the thick rod body and the thin lead wire base 23.

The cold cathode discharge lamps thus formed are used for backlights of liquid crystal displays such as word processors and personal computers, and liquid crystal displays including liquid crystal televisions. When the same display device can be enlarged, that is, large-sized, high-power, and long-life of cold cathode discharge, etc. (in particular, in consumer devices such as liquid crystal televisions, the demand for long-life, such as cold cathode discharge, is absolute, and the life is short. Is directly connected to the quality of the liquid crystal television itself).

In particular, in order to cope with high power, the cup-shaped electrode portion 20 needs to withstand high temperatures at the time of lighting (high heat resistance), and the material of the cup-shaped electrode portion 20 is Ni due to shape deformation or consumption. The deterioration and accompanying blackening (phenomena in which the electrode material evaporates and adheres to the inner surface of the rod and greatly impairs the light transmittance of the entire rod) is severe, and it is hardly possible to expect long life.

Therefore, although it has been examined to change the material of the electrode portion 20 to a high melting point metal such as tungsten or molybdenum, it is impossible or very difficult to form a high melting point metal such as tungsten or molybdenum into a cup shape, and furthermore, for example, a cup shape. Even if it could be formed in a high melting point due to the recrystallization (crystallization around the fusion joining portion grows and breaks from the portion) of the bottom portion 21, which is the welding portion 26 with the lead wire base 23, the high melting point The bottom portion 21 of the cup-shaped electrode portion 20 made of metal and the lead line base 23 of the cobalt agent could not be welded by a method similar to that of ordinary resistance welding.

Thus, welding the bottom 21 of the cup-shaped electrode portion 20 and the cobalt introduction line base 23 is performed using a welding means such as a laser having a short welding time and a small generation of heat affected by the recrystallization. In this case, although the surface of the bottom portion 21 of the cup-shaped electrode portion 20, which is the welded portion 26, is deteriorated, recrystallization problems can be alleviated, the cup-shaped electrode portion 20 is finally removed. There is a manufacturing problem that requires polishing the inner surface. For this reason, at present, this electrode problem is the biggest difficulty for the enlargement of a display device such as a liquid crystal television.

Patent Document 1: Japanese Unexamined Patent Publication No. 2002-110087

The object of the present invention is to newly develop an electrode which can cope with an enlargement of a display device such as a liquid crystal television, an electrode using a high melting point metal such as tungsten or molybdenum as a main material, and a manufacturing method thereof.

In the case where the electrode is composed of W or Mo alone, the encapsulated gas (for example, Ne gas) inside the encapsulation leaks out through the W electrode or the Mo electrode for a long time, and the gas composition inside the encapsulation changes and is turned on. There is a problem that causes a defect, and the solution of this problem is the subject of the present invention. In addition, when the display device becomes large, a plurality of cold cathode discharge lamps used in one display device should be used, but the brightness of the plurality of cold cathode discharge lamps used in one display device should be about the same level. do. In such a case, it is necessary to facilitate the exchange of cold cathode tube discharge or the like, but the solution of such a problem is also a secondary problem of the present invention.

In the first embodiment of the electrode A1 of the cold cathode discharge lamp according to claim 1,

(a) A cup-shaped electrode body composed of a cup-shaped electrode portion 10 of tungsten or molybdenum and an introduction line base 13 which protrudes integrally from the bottom portion 11 of the cup-shaped electrode portion 10. a) and,

(b) a lead wire tip 14 which is electrically connected to an end of the lead wire base 13 and which is lower than the melting point of the cup-shaped electrode body a and constitutes a part of the lead wire 12 for feeding;

(c) It is mounted so that the circumference | surroundings of the introduction line base 13 may be carried out, and it is comprised by the glass bead 15 welded to the sealing part 16 of the sealing body 19 at the time of sealing.

In the second embodiment of the electrode A2 of the cold cathode discharge lamp according to claim 2, in the second embodiment, the main material is tungsten or molybdenum, and its tip is concave in a cup shape, and a part of the rear end thereof is the discharge lamp rod 19. It is characterized in that the lead line 12 is embedded in the sealing portion 16.

Claim 3 is a limitation on the electrodes A1 and A2 of the cold cathode discharge lamp according to claim 1 or 2, wherein "Ni is mixed in tungsten or molybdenum".

Claim 4 is another limitation with respect to the electrodes A1 and A2 of the cold cathode discharge lamp of any one of Claims 1-3, "As an electron emitting material Sc, Y, La, Ce, Gd, Lu, Th, U, , At least one element selected from the group of Nb is further incorporated. &Quot;

Claim 5 is a limitation on the rear end portions of the electrodes A1 and A2 of the cold cathode discharge lamp according to any one of claims 1 to 4, wherein "the rear end portion located on the opposite side of the cup-shaped front end portion is the power supply contact point 18. It is characterized in that.

Claim 6 is a method of manufacturing an electrode A1 of the cold cathode discharge lamp,

(a) Tungsten fine sintered powder or molybdenum fine sintered powder, Ni powder, an electron-emitting material applied as needed, and a two-component thermoplastic binder resin are kneaded, and the mixture is injection molded to predict shrinkage due to firing. To form the green body of the cup-shaped electrode to which the introduction line of one size is attached,

(b) eluting one thermoplastic binder resin with a solvent to form a porous degreasing green body held by the other residual thermoplastic binder resin;

(c) After the degreasing green body is fired, the lead line base 13 of the cup-shaped electrode main body a with the plastic lead line and the lead line tip 14 formed of a different type of metal rod are electrically joined to each other,

(d) A glass bead 15 having a coefficient of thermal expansion substantially the same as that of the lead-in base 13 is fused around the lead-in base 13.

Claim 7 is a manufacturing method of the electrode A2 of the said cold cathode discharge lamp,

(a) Tungsten fine sintered powder or molybdenum fine sintered powder, Ni powder, an electron-emitting material added as needed, and a two-component thermoplastic binder resin are kneaded, and the mixture is injection molded to estimate shrinkage due to firing. In size, the tip portion is formed in a cup-shaped electrode-shaped green body which is concave in a cup shape,

(b) eluting one thermoplastic binder resin with a solvent to form a porous degreasing green body formed by the other remaining thermoplastic binder resin;

(c) The degreasing green body is fired.

Effects of the Invention

According to the electrode A1 of the first embodiment of the present invention, since the lead line base 13 protrudes integrally from the bottom portion 11 of the cup-shaped electrode portion 10, the welding point is the lead line tip portion 14. It becomes one place of the junction part 17 with, and not only half the welding process of the electrode A1, but also welds the bottom part 21 of the cup-shaped electrode part 20 like the conventional example, and the lead line base 23. Problems that occur at 100% are solved.

The cup-shaped electrode main body a of claim 1 or the electrode A2 of claim 2 is made of a high melting point metal such as tungsten or molybdenum, so that even if it is used as an electrode of a large cold cathode discharge lamp supplied when high power is turned on. Unlike the conventional electrode B made of Ni, the heat resistance and deformation resistance (the electrode body gradually evaporates and damages due to the discharge phenomenon at the time of lighting and wears out, and the electrode shape is gradually damaged. This phenomenon is excellent, and greatly contributes to the long life of a large cold cathode discharge lamp.

Moreover, as a formation method of the cup-shaped electrode main body a with the lead-out base of Claim 1, or the cup-shaped electrode A2 of Claim 2, the use of a two-component binder resin has attached the lead-out base which was not possible conventionally. Accurate integrally molded articles of the cup-shaped electrode main body a or the cup-shaped electrode A2 have been obtained by the sintering method. In other words, by adopting this method, mass production of an electrode having a cup-shaped portion became possible for the first time.

In addition, by incorporating Ni into tungsten or molybdenum, Ni fills minute gaps generated between the sintered tungsten particles or molybdenum particles, thereby allowing a gas outflow (so-called slow leak) over a long period of filling gas of the rod 19. This is avoided. In addition, by the incorporation of an electron-emitting material, it is possible to improve the lighting start performance and the lighting stability. In addition, by setting the rear end portions of the electrodes A1 and A2 as the contact points for feeding 18, attachment and detachment from the backlight of the cold cathode tube using the electrodes A1 and A2 are facilitated and can be easily replaced (normally). The contact of the cold cathode tube is soldered to the cord of the backlight, so the attachment and detachment is not easy.)

1A to 1C are cross-sectional views of electrodes (first and second embodiments) according to the present invention.

2 is a cross-sectional view before assembling of an electrode (first embodiment) according to the present invention;

3 is a sectional view of an electrode of a conventional example.

4 is a partial cross-sectional view of a large cold cathode discharge lamp using an electrode (first embodiment) according to the present invention.

Fig. 5 is a partial sectional view of a large cold cathode discharge lamp using an electrode (second embodiment) according to the present invention.

6 is a partial cross-sectional view of a large cold cathode discharge lamp using an electrode (another example of the second embodiment) according to the present invention.

* Description of the sign *

A: electrode of cold cathode discharge lamp of the present invention

10 cup-shaped electrode body 11 bottom

12: introduction line 13: introduction line donation

14: tip of the lead line 15: glass beads

Hereinafter, the present invention will be described in detail in accordance with the illustrated embodiment. An electrode A1 (Example 1) of a cold cathode discharge lamp according to the present invention is integrally formed from a cup-shaped electrode portion 10 mainly composed of tungsten or molybdenum, and from a bottom portion 11 of the cup-shaped electrode portion 10. The lead wire base 13 which extends and protrudes to the end, and is electrically connected to the end of the lead wire base 13 and constitutes a part of the lead wire 12, for example, nickel, a dumet wire (Ni-Fe alloy), It is widely used as an introduction line such as a Mn-Ni wire (man-nee wire), and is attached to surround the periphery of the lead wire tip 14 formed of a metal wire having a low melting point compared with tungsten or molybdenum, and the base wire base 13. It is comprised from the glass bead 15, What is characteristic is that the cup-shaped electrode part 10 and lead wire base 13 which are conventionally manufactured separately and to be welded are integrally formed.

The shape of the cup-shaped electrode portion 10 used here is large in comparison with that made of conventional Ni, for example, 1 to 3 mm in diameter (? 2 in this embodiment), and 4 to 6 mm in length [this embodiment] Is about an opening of one end, and the obstruction end (that is, the bottom portion 11) is a hemispherical shape. And the lead wire base 13 protrudes integrally from this hemispherical bottom part 11. The thickness of the lead wire base 13 is 0.8 to 1.4 mm (about ψ 1 in this embodiment), and the length is 2 to 5 mm (about 3 mm in this embodiment).

The lead line base 13 may have the same thickness until reaching the bottom 11 of the cup-shaped electrode portion 10 as shown in FIG. 1A, but the bottom portion of the cup-shaped electrode portion 10 as shown in FIG. It may be formed to become thicker gradually as it approaches 11), thereby increasing the mechanical strength of the portion near the bottom 11 of the cup-shaped electrode portion 10 of the lead line base 13. In this case, the entire lead wire base 13 may be tapered, the portion near the bottom 11 may be tapered, and the tip portion may be straight from the tapered portion.

In addition, the whole thickness of the cup-shaped electrode part 10 may also be the same thickness, or may become thin as it moves toward an opening side. In any case, the thickness of the tip of the opening of the cup-shaped electrode portion 10 is about t0.2 to t0.1, which is a typical example. In addition, since the integral molded body (a) which reaches from the cup-shaped electrode part 10 of the present invention to the lead line base 13 is formed by sintering the green body formed by injection molding as described later, the lead line base 13 The shape of the cup-shaped electrode portion 10 can be freely formed, as well as the shape of the cup electrode portion 10. However, it is preferable to taper or thin as described above.

Fig. 1C is an example of the electrode A2 (second embodiment) of claim 2, the whole being mainly composed of tungsten or molybdenum, and the cup shape described above is formed at the front end side in a cylindrical shape and reaches the rear end. (The rear end portion may be thinner or thicker than the front end portion, of course.) In addition, the rear end portion is a flat surface in this case, as shown in FIG. The recessed part 31 may be formed so that the terminal 30 may be attached or detached, or the power feeding member 18 such as Ni may be welded. Although the thickness of the power feeding member 18 is the same thickness as the electrode A2 in the embodiment of the figure, it is, of course, not limited to this, and may be thicker or thinner than the electrode A2. Reference numeral 32 is a clamp at the electrode end.

The cup-shaped electrode body (a) of claim 1 or the electrode (A2) of claim 2 may be a tungsten single body or a molybdenum single body, but in order to prevent the above-mentioned slow leak, it is preferable to mix a small amount of Ni as a binder. It is also effective to further incorporate at least one element selected from the group of Sc, Y, La, Ce, Gd, Lu, Th, U, Nb as the electron-emitting material in order to improve the lighting ease and lighting stability.

Next, the manufacturing method of the integral body a (the same applies to the electrode A2 of Claim 2) of the said cup-shaped electrode part 10 and the lead wire base 13 is demonstrated. Submicron fine powder for fine sintering having an average particle diameter of about 0.2 to 0.5 μm of tungsten or molybdenum (hereinafter referred to simply as fine powder for sintering) is prepared, and the powder for sintering is Tungsten or molybdenum only) or a powder of the Ni or electron-emitting material described above (ie, W or Mo sweet rice, W or Mo + Ni, W or Mo + electron-emitting material, or W or Mo + Ni + electron-emitting material) ] And the thermoplastic two-component binder resin which disperse | distribute and carry this sintering powder are knead | mixed uniformly enough, and there exists no uneven distribution of the fine powder for sintering. In other words, all of the fine powder for sintering is kneaded so as to sufficiently disperse in the binder resin. This kneaded material is made into pellet form over a pelletizing machine, this is thrown into the hopper of the heating cylinder of an injection molding apparatus, and the heat-melting kneading | mixing is carried out.

On the other hand, in the metal mold | die mounted in the metal mold | die part of an injection molding apparatus, the cup-shaped metal mold cavity (or the electrode-shaped metal mold cavity of Claim 2) in which the recessed part for forming a lead wire base | substrate is formed from the bottom part is provided in concave shape. And the fine powder-containing kneading resin for sinter, which is kneaded and metered in the heating cylinder, is filled in the mold cavity. The green body of the cup-shaped electrode main body (or the electrode shape of Claim 2) to which the lead line base adhered is formed through injection filling process-> pressurization process-> cooling process, and a normal injection molding process.

When the green body of the cup-shaped electrode main body (or the electrode shape of Claim 2) to which the lead wire base was attached is formed, it is immersed by immersing the green body in the solvent of binder resin. The binder resin is two-liquid, completely mixed with each other in a fine state, one binder resin is dissolved in a solvent, but the other binder resin remains without melting in the solvent, and an insoluble binder resin is used for fine sintering. Maintain complete shape with supporting fine powder. When one binder resin elutes, the green body composed of the remaining insoluble binder resin and the fine sintered fine powder supported thereon is in a porous state in which traces of the eluted binder resin are left as fine communication holes throughout. The green body is formed in a mold (generally almost analogous) larger than the final shape in anticipation of the shrinkage amount generated in the sintering step described later.

Subsequently, the porous green body is placed in a calcination furnace, the temperature is raised from room temperature to 700 ° C., and the porous degreasing product is heated. First, the residual solvent-insoluble resin (including a releasing agent and a plasticizer) is thermally decomposed and lost, The temperature is further raised and heated to the sintering temperature of the powder material to densely integrate tungsten or molybdenum sintering powders to complete the sintering. (It is preferable to use a hip furnace generated by pressurizing the furnace.) At this time, when Ni is mixed, fine gaps between sintered tungsten or molybdenum are blocked with Ni. In addition to the slow leakage prevention, the action of Ni may be easier to weld with a different metal due to the presence of Ni in comparison with the case of tungsten or molybdenum alone due to the presence of Ni. have. In the case of firing tungsten, it is preferable to carry out in a hydrogen atmosphere in which carbon is not present in order to avoid formation of WC. When the sintering is completed, the cup-shaped electrode main body a (or the electrode A2 of claim 2) to which the lead wire base is attached has a desired dimension.

Subsequently, in the cup-shaped electrode main body a with the lead wire base of claim 1 or the electrode A2 of claim 2, for example, a lead wire tip 14 formed of nickel and a lead wire formed by the powder sintering The lead line base 13 (or the electrode A2 of claim 2 and other necessary members 18) of the integrated cup-shaped electrode body a with the base attached is suitable for welding method (rotational friction welding, laser welding or silver soldering). Etc.), and in the case of claim 1, the glass bead 15 so as to surround the periphery of the lead line base 13 between the welding portion 17 and the cup-shaped electrode portion 10 at the end. ) Is fused. The glass beads 15 have a coefficient of thermal expansion substantially the same as that of the tungsten base line 13, for example, hard glass.

The thickness of at least the junction portion 13a of the lead line base 13 of the integrated cup-shaped electrode main body a is the same as the thickness of the lead line tip 14 or is approximately 30% thin, and at the time of joining, the lead line tip of the low melting point side is joined. The junction part of (14) melt | dissolves, and the front-end | tip part (namely, the junction part 13a) of the lead wire base 13 enters into this junction part, and it joins by unifying at the boundary surface. Therefore, as shown in FIG. 4, the junction part 17 of both is a junction part in the state in which the junction part 13a of the tip end of the introduction line base 13 was integrated in the expansion part of the lead line tip part 14, and was integrated. (17) is formed.

The electrodes A1 and A2 for the cold cathode tube formed in this way are filled with the necessary filling material and the necessary filling gas inside the sealing body 19 by a conventional method, and the glass beads 15 are provided on both sides of the sealing body 19. Fusion and integration The large cold cathode discharge lamp thus formed is a large straight cathode or U-tube having a length of 1,000 to 2,000 mm and a diameter of 4 to 6 mm (? 5 in this embodiment), which is a large cold cathode discharge lamp so far.

The electrode of the present invention is particularly used as an electrode for a large cold cathode tube used as a light source for a backlight of a large liquid crystal display device.

Claims (7)

(a) a cup-shaped electrode body composed of a cup-shaped electrode portion of tungsten or molybdenum, a lead wire base integrally extending from and protruding from the bottom of the cup-shaped electrode portion; (b) a lead wire tip electrically connected to the end of the lead wire base, which is lower than the melting point of the cup-shaped electrode body and constitutes a part of the lead wire for power feeding; (c) An electrode, such as a cold cathode discharge lamp, comprising a glass bead mounted so as to surround the periphery of the lead wire and welded to the sealing portion of the rod during sealing. A main electrode is tungsten or molybdenum, and its tip is concave in the shape of a cup, and a part of the rear end thereof is a lead wire which is directly enclosed in the sealing portion of the discharge lamp container during sealing. Ni is mixed as a cup-shaped electrode main body forming material of claim 1 or an electrode forming material of claim 2, wherein an electrode such as a cold cathode discharge lamp is used. The method according to any one of claims 1 to 3, wherein at least one element selected from the group of Sc, Y, La, Ce, Gd, Lu, Th, U, Nb is further incorporated as the electron emitting material. The electrode of a cold cathode discharge lamp characterized by the above-mentioned. The electrode of a cold cathode discharge lamp according to any one of claims 1 to 4, wherein the rear end portion located on the opposite side of the cup-shaped front end portion serves as a power supply contact point. (a) Tungsten fine sintered powder or molybdenum fine sintered powder, Ni powder, an electron-emitting material applied as needed, and a two-component thermoplastic binder resin are kneaded, and the mixture is injection molded to predict shrinkage due to firing. To form the green body of the cup-shaped electrode to which the introduction line of one size is attached, (b) eluting one thermoplastic binder resin with a solvent to form a porous resin green body formed by the remaining thermoplastic binder resin on the other; (c) after the degreasing green body is fired, the lead line of the cup-shaped electrode main body with a plastic lead line and the lead line tip formed of a different type of metal rod are electrically joined to each other, (d) A method for producing an electrode, such as a cold cathode discharge lamp, comprising fusing a glass bead having a thermal expansion coefficient substantially the same as that of the lead-in base, around the lead-in base. (a) Tungsten fine sintered powder or molybdenum fine sintered powder, Ni powder, an electron-emitting material applied as needed, and a two-component thermoplastic binder resin are kneaded, and the mixture is injection molded to predict shrinkage due to firing. In one size, a tip-shaped end portion is formed in a cup-shaped concave green body, (b) eluting one thermoplastic binder resin with a solvent to form a porous degreasing green body formed by the other remaining thermoplastic binder resin; (c) The manufacturing method of the electrode of a cold cathode discharge lamp characterized by baking this degreasing green body.

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