JPH0613032A - Discharge tube - Google Patents

Abstract

PURPOSE:To increase discharge current and attain a longer life even in the case of high luminance emission by forming a second electrode from a metal having a low sputtering yield by cation, and providing a metal film having high secondary electron emitting property on the inner surface of the electrode. CONSTITUTION:A second electrode 42A is formed of a composite structure consisting of a cylindrical electrode 42A1 formed of a metal having a low sputtering yield by cation, for example, Al, and a metal film having high secondary electron emitting property formed on its inner surface, for example, an Ag-Cs metal film 42A2. On the outer circumferential part of a cylindrical first electrode 41, the electrode 42A is caulked and fixed to its root part, enclosing the electrode 41, and arranged in a determined position concentrical to an inner lead 3. Thus, the secondary electron current from the inner surface film 42A2 can be utilized as discharge current even in the case of the cylindrical electrode 42A1 never reaching the temperature causing thermion emission because of its less rise of electrode temperature, a high current can be carried without increasing the load of the electrode 41. Thus, a high luminance and a long life can be attained.

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 an electrode device composed of a first electrode part and a second electrode part surrounding the outer periphery of the first electrode part is arranged to face each other, and more specifically to an electrode structure of the electrode device. It is a thing.

[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, 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 sectional view, and FIG. 2 (b) is an enlarged perspective view of a main part of the electrode device. In FIG. 2 (a), 1 is a transparent glass tube forming the main body of the discharge tube, 2 is a fluorescent substance applied to the inner wall surface of the glass tube 1, and 3 is the glass tube at the longitudinal end of the glass tube 1. Inner leads 4 held through 1 are a pair of electrode devices which are arranged coaxially in the longitudinal direction of the glass tube 1 so as to face each other at the tip of each inner lead 3. The glass tube 1 is filled with a mixed gas of, for example, argon gas and mercury for discharging.

In FIG. 2 (b), reference numeral 4 ₁ denotes a first electrode for emitting thermoelectrons formed of a sintered metal body at the tip of the inner lead 3 and reference numeral 4 ₂ denotes this first electrode 4 _1. Is a cylindrical second electrode made of a nickel molded body that is concentrically arranged by penetrating the inner lead 3 so as to surround it and crimping and fixing its root portion.

In such a structure, the pair of electrode devices 4 arranged to face each other includes the first electrode 4 ₁ and the first electrode 4 _1.
And a second electrode 4 ₂ surrounding the arc discharge electrode, which is disposed adjacent to each other. The first electrode 4 ₁ is impregnated with the emitter material as a thermoelectron emitting substance or is applied on the surface thereof. The second electrode 4 ₂ functions as a glow discharge electrode, and a synergistic effect of the two allows stable discharge of ultra-high brightness. Since a super-high-intensity discharge tube can be stably obtained, and the thermoelectron emitting substance or electrode material which is sputtered and evaporated by the first electrode 4 _{1 due} to ion bombardment is trapped on the inner surface of the second electrode 4 ₂ . The trapped thermionic emissive material is used as an electron emissive material on the second electrode 4 ₂ without causing blackening of the inner surface of the glass tube 1, and is reattached to the surface of the first electrode 4 _1. By repeating the above steps, a long-life discharge tube can be obtained. In addition,
This type of discharge tube is disclosed in, for example, Japanese Patent Application No. 2-318277.

[0006]

However, in the discharge tube having such a structure, when higher brightness is required, if the discharge current by the first electrode 4 ₁ is increased, the first electrode 4 1 There is a restriction that the life of ₁ is remarkably reduced and the purpose of long life is impaired, and the electrode temperature cannot be raised too much depending on the type of emitter material.
There was a problem that it was not possible to meet those demands.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and an object thereof is to increase the discharge current by increasing the electron emission function of the second electrode 4 _2. An object of the present invention is to provide a discharge tube that does not have a risk of shortening its life even if it emits light with brightness.

[0008]

In order to achieve such an object, the present invention comprises a second electrode made of a metal having a low sputtering yield by cations, and a secondary electrode is formed on the inner surface of the second electrode. A metal film having a high electron emission property is provided.

[0009]

The second electrode of the present invention does not reduce the life of the tube even when a high discharge current is passed in order to obtain high brightness.

[0010]

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 of an electrode device for explaining the configuration of an embodiment of the discharge tube according to the present invention, and the same parts as those in the above-mentioned figures are designated by the same reference numerals. In the figure, the electrode device 4A is composed of a first electrode 4 ₁ provided at the distal end of the inner lead 3, and the second electrode 4 _2A surrounding the electrodes 4 ₁ of the first, the second Electrode 4
_2A is a cylindrical electrode _{42A1 made} of, for example, Al as a metal having a low sputtering yield due to cations, and a cylindrical electrode _42A1.
As a metal film having a high secondary electron emission property formed on the inner wall surface of, the composite structure is composed of, for example, an Ag—Cs metal film _42A2 .

The cylindrical electrode 4 _2A1 thus constructed is
For example, Al is formed by hot press molding at about 350 ° C., and the Ag—Cs metal film _42A2 is formed by applying a metal powder slurry formed by mixing powdery Ag and Cs, for example. ing.

The second electrode 4 _2A having a cylindrical shape as described above has a cylindrical first electrode 4 ₁ formed of a sintered metal body at the tip of the inner lead 3 and impregnated with an electron emitting substance. The first electrode 4 ₁ is surrounded by the outer peripheral portion of the inner electrode 3 and is caulked and fixed at its root portion, and is arranged at a predetermined position concentrically with the inner lead 3.

In the electrode device 4A constructed as described above, the first electrode 4 ₁ is enclosed in the cylindrical second electrode 4 _2A , so that the first electrode 4 ₁ is heated. It is possible to flow a discharge current that is raised to a temperature suitable for emitting electrons and causes high-luminance light emission. Furthermore the second electrode 4 _2A of the cylindrical shape, the first electrode 4 ₁ is sputtered by ion bombardment, blackening due to adhering to the inner surface of the glass tube 1 by thermionic emission material or the electrode member scattered evaporated While preventing, thermionic emission due to the electron emitting substance attached to the inner surface of the second electrode _2A can be used, and the electron emitting substance can be reattached to the surface of the first electrode 4 ₁ to prevent the emission of the electron emitting substance. The regeneration effect can be used and the life can be extended.

According to this structure, the second electrode 4 _2A
Is Ag-Cs on the inner wall surface of the cylindrical electrode _{42A1 made} of Al.
By forming the metal film 4 _2A2, less increase in electrode temperature, be cylindrical electrode 4 _2A1 that does not reach the temperature at which thermionic emission occurs, secondary electron emission highly Ag-Cs metal on its inner surface film 4 can be utilized as a secondary electron current discharge current from _2A2, without heavier first electrode 4 ₁ burden, since a high current can flow, can be a long life with high intensity.

Further, in such a structure, the second electrode 4 _2A comprises the cylindrical electrode 4 _2A1 made of Al, which is a metal having a low sputtering yield due to cations, so that the electrode material of the cylindrical electrode 4 _2A1 is made. The blackening of the tube surface attached to the inner surface of the glass tube 1 can be reduced.

The discharge tube constructed as described above was produced by the inventors of the present invention in a large amount and subjected to a life test for a plurality of times. As a result, the life time of the discharge tube was changed from the conventional one without impairing other electrical characteristics. About 5000 hours to about 2000
It was confirmed that it could be extended to 0 hours.

In the above-described embodiment, the case where Al is used as the metal having a low sputtering yield due to cations for the second electrode 4 _2A has been described, but the present invention is not limited to this. , Si, Ti, V, Zr, N
Even if it is formed by using a metal having a sputtering yield of 0.8 (atoms / ions) or less for Ar ions such as b, Mo, Ta, W or the like, or an alloy of at least two kinds of these metals, it is the same as described above. The effect is obtained.

Further, in the above-mentioned embodiment, the case where the mixture of Ag-Cs is used as the secondary electron emitting substance has been described, but the present invention is not limited to this, and Ag-Mg, Cu- Of course, even if a mixture of metals such as Be, Cs-Sb, and Cr ₂ O _{3 having} a maximum secondary electron emission gain of 1.0 or more is used, the same effect as described above can be obtained.

Further, in the above-described embodiment, the case where the second electrode _42A is formed in a substantially cylindrical shape has been described, but the present invention is not limited to this and the cylindrical shape is not limited to this. Of course, it may be formed in various shapes such as a deformed body, a conical shape, or a modified shape thereof.

Further, in the above-mentioned embodiment, the case where the first electrode 4 ₁ is formed of a sintered metal body has been described, but the present invention is not limited to this, and for example, a tungsten wire is used as a coil. It goes without saying that the same effect as described above can be obtained even with a coil structure formed in a shape.

[0021]

As described above, according to the present invention,
Since the second electrode is made of a metal having a low sputtering yield due to cations and a metal film having a high secondary electron emission property is provided on the inner surface, a long life can be obtained even when a large amount of discharge current is supplied to cause high-luminance light emission. It has an extremely excellent effect such as obtaining a discharge tube.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view of an essential part of an electrode device showing a configuration according to an embodiment of a discharge tube according to the present invention.

FIG. 2A is a cross-sectional view showing the configuration of a conventional discharge tube,
FIG. 3B is an enlarged cross-sectional view of a main part showing the configuration of the electrode device.

[Explanation of symbols]

1 Glass Tube 2 Fluorescent Material 3 Inner Lead 4A Electrode Device 4 ₁ First Electrode 4 _2A Second Electrode 4 _2A1 Cylindrical Electrode 4 _2A2 Ag-Cs Metal Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Ken Kawai 700 Wada, Ueno Town, Ise City, Mie Prefecture, Ise Denshi Kogyo Co., Ltd. Company Noritake Company Limited (72) Inventor Yoshiyuki Okubo 3-1, 36 Noritake Shinmachi, Nishi-ku, Nagoya-shi Stock company Noritake Company Limited 3-72 (36) Inventor Sato Fuyu 3-36, Noritake Shincho, Nishi-ku, Nagoya Ceremony Company Noritake Company Limited

Claims (3)

[Claims] 1. A discharge comprising a pair of electrode devices arranged opposite to each other in a discharge space and having a first electrode portion connected to an inner lead and a second electrode portion surrounding the outer periphery of the first electrode portion. In the tube, the second electrode portion is made of a metal having a low sputtering yield due to cations, and a metal film having a high secondary electron emission property is provided on the inner surface of the second electrode portion. . 2. The metal of any one of Al, Si, Ti, V, Zr, Nb, Mo, Ta and W, or an alloy comprising at least two kinds of these metals, according to claim 1. Discharge tube characterized by being composed of. 3. The metal film according to claim 1, wherein the metal film provided on the inner surface of the second electrode portion is Ag-Cs, Ag-Mg, Cu-.
A discharge tube comprising any one of Be, Cs-Sb, Cr ₂ O ₃ or a mixture thereof.