JPH0757687A - Discharge tube - Google Patents

Abstract

PURPOSE:To obtain high intensity light emission in a small type, and realize the long service life. CONSTITUTION:A pair of electrode devices 4A arranged opposite on both end sides of a glass tube 1 are composed of a column shape electrode 41A arranged in the tip part of an inner lead 3 and an Al cup shape electrode 4w to surround this column shape electrode 41A. This column shape electrode 41A is formed by containing TiC, for example, in a sintered body of tungsten (W), and the Al cup shape electrode 42A is formed in a conical shape by press forming work of an aluminium plate material. This Al cup shape electrode 4-)) is inserted in the inner lead 3, and is calked and fixed at the root part to the inner lead 3 by surrounding the column shape electrode 41A arranged in the tip part, and is arranged on a concentric axis so that a quantity of a scattering electron emitting substance is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge tube applied to, for example, a backlight for a liquid crystal panel, and in particular, it is constructed by enclosing a rare gas and mercury in a glass tube and connected to inner leads at both ends. The present invention relates to a discharge tube in which a pair of electrode devices composed of a sintered electrode and a metallic cup-shaped electrode surrounding the outer periphery of the sintered electrode are arranged to face each other, and more specifically, a sintered electrode forming the electrode device. Is related to the structure of.

[0002]

2. Description of the Related Art With recent advances in liquid crystal technology, liquid crystal display panels have come to be widely used in various display devices. Recently, a liquid crystal display device using this liquid crystal display panel has been strongly demanded to be particularly small and lightweight, and in order to satisfy the requirements relating to such a liquid crystal display device, a discharge tube is widely used as a backlight of the liquid crystal display panel. Has been adopted.
Therefore, in order to manufacture a miniaturized liquid crystal display device, it has been particularly required to improve the liquid crystal display panel and miniaturize the backlight. At the same time, in order to improve the display quality of the liquid crystal display device, higher brightness and longer life are required.

FIG. 2 is a diagram for explaining the structure of this type of discharge tube. FIG. 2 (a) is a perspective view of an electrode device, and FIG. 2 (c).
Is a sectional view thereof. In FIG. 2, 1 is a transparent glass tube whose both ends are hermetically sealed to form a discharge tube main body, 2 is a fluorescent surface applied to the inner wall surface of the glass tube 1, and 3 is both ends in the longitudinal direction of the glass tube 1. The inner leads 4 held by penetrating the glass tube 1 are electrode devices that are arranged on the tip ends of the inner leads 3 so as to face each other and coaxially in the longitudinal direction of the glass tube 1. The electrode device 4 is formed by impregnating a sintered body of tungsten (W) with, for example, titanium carbide (TiC) or tantalum carbide (TaC) as an electron emitting substance. In addition, this glass tube 1
A mixed gas of, for example, argon gas and mercury for discharging is enclosed therein.

In the discharge tube constructed as described above, since the electrode device 4 is formed by impregnating a sintered body with TiC or TaC as a thermoelectron emitting substance, it is used as an arc discharge electrode and a glow discharge electrode. It works, and the synergistic effect of the two makes it possible to stably obtain an ultra-high brightness discharge.

[0005]

However, in the discharge tube constructed in this manner, the pair of electrode devices 4 are heavily sputtered by ion bombardment, so that the amount of electron-emissive substances is scattered and evaporated, resulting in a short service life. However, there is a problem that the life is not easily extended.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to provide a discharge tube capable of realizing a long life.

[0007]

In order to achieve the above object, the discharge tube according to the present invention has an inner lead in a discharge space in which at least a rare gas and mercury are enclosed in a glass tube whose both ends are hermetically sealed. A pair of electrode devices connected to each other are opposed to each other, and at least one of the pair of electrode devices is made of a heat-resistant metal containing a metal carbide as an electron emitting substance, and a sintered electrode that covers the sintered electrode and It is composed of a metallic cup-shaped electrode that captures an electron emitting substance scattered and evaporatively emitted from the connecting electrode.

[0008]

The electrode device according to the present invention comprises a sintered electrode made of a heat-resistant metal, and a metallic cup-shaped electrode which covers the sintered electrode and captures an electron emitting substance scattered and vaporized and emitted from the sintered electrode. With this configuration, the amount of electron-emissive substances scattered and evaporated is reduced, and the life is extended.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is an enlarged cross-sectional view of an essential part showing the configuration of an embodiment of a discharge tube according to the present invention, and the same parts as those in FIG. 2 are designated by the same reference numerals. In Figure 1, the diameter 4 mm, a pair of electrode device 4A disposed opposite to both ends of the glass tube 1 of length 260mm is a cylindrical electrode 4 _1A provided at the distal end of the inner lead 3, the cylindrical electrodes It is composed of an Al cup electrode 4 _2A surrounding 4 _1A .

The columnar electrode _41A is formed by, for example, a sintered body of tungsten (W) containing TiC as a metal carbide, and the Al cup electrode 4A.
_2A is formed in a conical shape by press molding an aluminum plate material. And this Al cup electrode 4 _2A
Is inserted through the inner leads 3, are configured to be disposed in caulking fixed concentric axis on the inner lead 3 at the root portion surrounds the cylindrical electrode 4 _1A provided at its distal end.

Further, the cylindrical electrodes 4 _1A includes a TiC powder, a powder of a refractory metal such as W were mixed, normal compression, can be formed as a sintered body by performing sintering process.

In such a structure, the cylindrical electrode 4 _1A
There by being encapsulated in Al cup-shaped electrode 4 _2A which is formed into a conical shape, can be cylindrical electrodes 4 _1A is raised to a temperature suitable to release thermoelectrons, thereby high luminance. Further, the cup-shaped electrode 4 _2A is a cup-shaped electrode 4 _1A while preventing blackening due to adhesion to the inner surface of the glass tube 1 by a thermoelectron emitting substance or electrode member that is scattered and evaporated when the cylindrical electrode 4 _1A is sputtered by ion impact. Electrode 4 _2A
Thermionic emission by an electron emitting substance attached to the inner surface of the can be used.

Further, the electron emitting material is used as a cylindrical electrode _41A.
By reattaching it to the surface of the electron emitting material, the regeneration effect of the electron emitting material can be utilized, so the consumption of the electron emitting material is extremely reduced, a sufficient discharge current is obtained, the light amount is increased, and high brightness light emission is obtained. In addition, it is possible to achieve a long life.

In the above-mentioned embodiment, the case where TiC is used as the thermoelectron emitting substance has been described, but the same effect as described above can be obtained by using TaC instead of TiC.

Table 1 below shows the electric characteristics of a discharge tube having the above-configured electrode device 4A and a discharge tube having the conventional electrode device 4 and having the same size (diameter 4 mm, tube length 260 mm). It shows the obtained results. As is clear from Table 1, in the configuration according to the embodiment, the result of the on / off test every 30 seconds is significantly improved as compared with the structure of the conventional discharge tube while maintaining the emission brightness and the emission efficiency of the discharge tube. Was confirmed. In other words, it was confirmed that the life is long.

[0016]

[Table 1]

[0017] Incidentally, in the above-mentioned embodiment has described the case of using the W sintered body as an electrode material of the cylindrical electrode 4 _1A, W, Mo, Ti, even with Nb or mixtures thereof previously described The same effect as can be obtained.

Further, in the above-mentioned embodiment, the case where the cup-shaped electrode _42A is formed of an aluminum material has been described, but it may be formed of a nickel material, or a mixture of tungsten and nickel is cut by a die. May have a saw-tooth shape, and the whole shape may be formed into a bell shape and then sintered to form a sintered body.

[0019]

As described above, according to the present invention,
At least one of the pair of electrode devices, a sintered electrode made of a heat-resistant metal containing a metal carbide as an electron emitting material,
Since it is composed of a metallic cup-shaped electrode that covers the sintered electrode and captures the electron emitting substance scattered and evaporated and emitted from the sintered electrode, sufficient discharge characteristics can be obtained, and the compact and high-luminance light emission can be achieved. In addition to being obtained, it has an extremely excellent effect of obtaining a long-life discharge tube.

[Brief description of drawings]

1A is a cross-sectional view showing a structure according to an embodiment of a discharge tube according to the present invention, FIG. 1B is an enlarged perspective view showing a structure of an electrode device, and FIG. 1C is a cross-sectional view thereof.

FIG. 2A is a cross-sectional view showing the configuration of a conventional discharge tube,
(B) is an enlarged perspective view showing the configuration of the electrode device, and (c) is a sectional view thereof.

[Explanation of symbols] 1 glass tube 2 phosphor screen 3 inner lead 4A electrode device 4 _1A columnar electrode 4 _2A cup-shaped electrode

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshiyuki Okubo 3-36 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Noritake Company Limited Limited (72) Inventor Sato Fuyu 3-chome, Noritake Shin-cho, Nishi-ku, Nagoya, Aichi No. 1-36 Noritake Company Limited (72) Inventor Go Maeda No. 1-336 Noritake Shinmachi, Nishi-ku, Nagoya-shi Aichi Prefecture Noritake Company Limited (72) Inventor Tokuhide Shimojo Ueno, Ise City, Mie Prefecture Town 700 Wada, Ise Electronics Industry Co., Ltd. (72) Inventor Masao Uchiyama 700 Wada, Ueno Town, Ise City, Mie Prefecture Ise Electronics Industry Co., Ltd.

Claims (1)

[Claims] 1. A pair of electrode devices connected to inner leads are arranged opposite to each other in a discharge space in which at least a rare gas and mercury are sealed in a glass tube whose both ends are hermetically sealed, and at least one of the pair of electrode devices. A sintered electrode, one of which is made of a heat-resistant metal containing a metal carbide as an electron emitting substance, and a metallic cup-shaped electrode that covers the sintered electrode and captures an electron emitting substance that is scattered and evaporated and emitted from the sintered electrode. Discharge tube characterized by being composed of.