JPH0757690A - 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 spherical electrode 41A arranged in the tip part of an inner lead 3 and an Al cup shape electrode 42A to surround this spherical electrode 41A This spherical electrode 41A is formed of a plasma flame spraying body of LaB6, and the cup shape electrode 42A is formed in a conical shape by press forming work of an aluminium plate material. This cup shape electrode 42A is inserted in the inner lead 3, and is calked and fixed at the root part to the inner lead 3 by surrounding the spherical 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 formed by opposing a pair of electrode devices each composed of an electron emission electrode and a metallic cup-shaped electrode surrounding the outer periphery of the electron emission electrode, and more particularly to the structure of the electrode device. .

[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 of a plasma spray material of an electron emitting material. The glass tube 1 is filled with a mixed gas of, for example, argon gas and mercury for discharging.

In the discharge tube thus constructed, these electrode devices 4 are formed of a plasma sprayed material of thermionic emission material, so that they have sufficient mechanical strength as electrodes and impair the characteristics of the raw materials. Since the electrode can be formed without using the electrode, it works as an arc discharge electrode, and an ultra-high brightness discharge can be stably obtained.

[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 arranged to face each other, and at least one of the pair of electrode devices is composed of a plasma spray material of an electron emitting substance.
And an second electrode that covers the first electrode and captures an electron emitting substance scattered and evaporated and emitted from the first electrode.

[0008]

The electrode device according to the present invention is provided with the second electrode which covers the first electrode and captures the electron emitting substance scattered and evaporatively emitted from the first electrode, so that the amount of the electron emitting substance is scattered. Less evaporation and longer life.

[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 has a spherical electrodes 4 _1A provided at the distal end of the inner lead 3, the spherical electrode 4 _1A Surrounding Al
It is composed of a cup-shaped electrode _42A .

The spherical electrode 4 _1A is formed of a plasma sprayed material such as LaB ₆ as an electron emitter, and the Al cup-shaped electrode 4 _2A is formed into a conical shape by pressing an aluminum plate material. Has been formed. Then the Al cup electrode 4 _2A is inserted into the inner leads 3 are arranged in caulking fixed concentric axis on the inner lead 3 at the root portion surrounds the spherical electrodes 4 _1A provided at its distal end It is configured to.

In such a structure, the spherical electrode 4 _1A is enclosed in the conical Al cup-shaped electrode 4 _2A so that the spherical electrode 4 _1A has an appropriate temperature for emitting thermoelectrons. It can be raised to emit light with high brightness. Furthermore the cup-shaped electrode 4 _2A is spherical electrodes 4 _1A is sputtered by ion bombardment, while preventing the blackening due to adhering to the inner surface of the glass tube 1 by thermionic emission material or the electrode member scattered evaporation, the cup-shaped Thermionic emission by the electron emitting substance attached to the inner surface of the electrode _42A can be used.

Further, since the regenerating effect of the electron emitting substance can be utilized by reattaching the electron emitting substance to the surface of the spherical electrode _41A , the consumption of the electron emitting substance is extremely reduced and a sufficient discharge current can be obtained. Therefore, the amount of light is increased, high-luminance light emission can be obtained, and a long life can be achieved.

In the above-mentioned embodiment, the case of using the LaB ₆ plasma spray material as the spherical electrode 4 _1A has been described. However, instead of this LaB ₆ plasma spray material, the BaTiO ₃ plasma spray material is used. However, the same effect as the above was obtained.

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.

[0015]

[Table 1]

In the above-mentioned embodiment, the case where the cylindrical electrode 4 _1A is formed from the plasma sprayed material of LaB ₆ or BaTiO ₃ has been described, but a boride or oxide containing an alkali metal or an alkaline earth metal is used. Even if it is used, the same effect as described above can be obtained.

Further, in the above-mentioned embodiment, the case where the cup-shaped electrode _42A is made of an aluminum material has been described, but it may be made of a nickel material, and 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.

[0018]

As described above, according to the present invention,
At least one of the pair of electrode devices comprises a first electrode composed of a plasma sprayed material of an electron emitting substance, and an electron emitting substance which covers the first electrode and is scattered and evaporated and emitted from the first electrode. The provision of the second electrode has an extremely excellent effect that sufficient discharge characteristics are obtained, small size and high-luminance light emission are obtained, and a discharge tube having a long life is obtained.

[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 spherical 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 an inner lead 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 first electrode, one of which is composed of a plasma spray material of an electron emitting substance, and a second electrode which covers the first electrode and captures the electron emitting substance which is scattered and evaporated and emitted from the first electrode. Discharge tube characterized by having.