JPH0721991A - Discharge tube - Google Patents

Abstract

PURPOSE:To use easily as a back light regardless of the installing direction of a trigger electrode, as well as to make discharge easily even at a low discharge starting voltage. CONSTITUTION:In a discharge space where at least a rare gas and mercury are sealed in a glass tube 1 whose both ends are sealed, a pair of electrode devices 4A connected to inner leads 3 respectively are provided opposing each other. To a luminescent screen 2A formed on the inner wall surface of the glass tube 11, a phosphor to which a transparent conductive material is included in the scope about 15wt.% is used, and the luminescent screen 2A is connected electrically to either one side of the inner leads 3.

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 liquid crystal panel backlight, and more particularly to a phosphor coated on the inner wall surface of a glass tube.

[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, FIG. 2 (b) is an enlarged perspective view of an essential part of the electrode device, and FIG. ) Is a sectional view thereof. In FIG. 2A, 1 is a transparent glass tube whose both ends are hermetically sealed to form a discharge tube body, 2 is a fluorescent surface applied to the inner wall surface of the glass tube 1, and 3 is the length of the glass tube 1. Inner leads 4 held by penetrating the glass tube 1 at the end portions in the direction are composed of composite electrodes arranged coaxially in the longitudinal direction of the glass tube 1 so as to face each other at the tip portions of the inner leads 3. The first electrode device and the second electrode device. The glass tube 1 is filled with a mixed gas of, for example, argon gas and mercury for discharging.

Further, these electrode devices 4 are shown in FIG.
As shown in (b) and (c), a cylindrical electrode 4 ₁ provided at the tip of the inner lead 3 and the cylindrical electrode 4 ₁ are crimped and fixed to the inner lead 3 so as to surround the cylindrical electrode 4 ₁ and arranged on a concentric shaft. And a conical electrode 4 ₂ . The cylindrical electrode 4 ₁ acts as an arc discharge electrode by impregnating or coating the surface of the sintered body with an emitter material as a thermoelectron emitting substance, and the conical electrode 4 ₂ is formed by a metal plate molded body to form a glow electrode. It works as a discharge electrode, and a synergistic effect of the two makes it possible to stably obtain an ultra-high brightness discharge.

[0005] discharge tube constructed in this way, cylindrical electrodes 4 ₁ is sputtered by ion bombardment with the discharge tube of ultra-high brightness can be obtained stably, thermionic emission material scattered evaporation conical electrode 4 Glass tube 1 captured on the inner surface of ₂
The trapped thermoelectron emitting substance is used as an electron emitting substance on the conical electrode 4 ₂ without causing blackening on the inner surface of the column, and is again captured by the columnar electrode 4 ₁ again. A long-life discharge tube can be obtained. A discharge tube of this type is disclosed in, for example, Japanese Patent Application No. 2-318277.

[0006]

However, in the discharge tube constructed as described above, when the tube diameter of the glass tube 1 is limited and the tube length becomes long in response to the demand for miniaturization, the discharge starts accordingly. There is a problem that the voltage becomes high and it becomes difficult to start the discharge. Further, as a solution to such a problem, there is a method of providing a trigger electrode formed by sticking a metal tape along the length direction on the outer surface of the glass tube 1. When it is provided on the outer surface, there is a problem in that it has directionality and the mounting process becomes complicated when it is used as a backlight.

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 discharging even at a low discharge starting voltage. Another object of the present invention is to provide a discharge tube that can be easily used as a backlight without being affected by the mounting direction of the trigger electrode.

[0008]

In order to achieve such an object, the discharge tube according to the present invention has a fluorescent screen formed on the inner wall surface of a glass tube whose both ends are hermetically sealed, transparent to the phosphor. The conductive material is contained in the range of 1 to 10% by weight, and the phosphor screen is electrically connected to either one of the inner leads.

[0009]

In the present invention, the fluorescent surface containing the transparent conductive material also functions as a trigger electrode together with fluorescence emission.

[0010]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 (a) is a sectional view showing the structure of an embodiment of the discharge tube according to the present invention, and FIG. 1 (b) is an enlarged sectional view of the electrode device portion. I am doing it. In FIG. 1 (b), a pair of electrode device 4A disposed opposite to both ends of the glass tube 1 surrounds a cylindrical electrode 4 _1A provided at the distal end of the inner lead 3, the cylindrical electrodes 4 _1A It is composed of a cup-shaped electrode _42A . The columnar electrode _41A is formed by impregnating or coating the surface of the sintered body with an emitter material as a thermoelectron emitting material, and the cup-shaped electrode _42A is formed by pressing an aluminum plate material, for example. The cup-shaped electrode 4 _2A is inserted into the inner lead 3 and surrounds the cylindrical electrode 4 _1A provided at the tip of the inner lead 3 and is caulked and fixed to the inner lead 3 at the base portion thereof and arranged on the concentric shaft. It is composed.

In the discharge tube thus constructed, the fluorescent surface 2A formed by coating is formed on the inner surface of the glass tube 1.
Is a transparent conductive material for the phosphor, such as In ₂ O ₃
Is contained in an amount of about 5 wt%. It should be noted that the addition of In ₂ O ₃ does not have a great influence on the manufacturing process because it is sufficient to mix a predetermined amount when the phosphor and the binder are mixed in advance in the step of applying the phosphor screen 2A. Absent.

Further, in such a structure, FIG.
As shown in (b), the fluorescent screen 2 formed in the glass tube 1
A is an inner lead 3 provided at both ends of the glass tube 1.
It is applied so as to come into contact with either one of them and electrically connected.

The discharge tube thus constructed has inner leads 3 on the side connected to the phosphor screen 2A formed by coating on the inner wall surface of the glass tube 1 and inner leads not connected to the phosphor screen 2A. By applying a predetermined discharge voltage from an AC power supply (not shown) between the two and 3, a discharge current flows, discharge is started, and extremely stable discharge is obtained.

In this case, since the columnar electrode _41A is contained in the cup-shaped electrode _42A formed in a conical shape, the columnar electrode _41A rises to an appropriate temperature for emitting thermoelectrons. It is possible to emit light with high brightness. Furthermore, this conical cup-shaped electrode _42A is a cylindrical electrode _41A.
Are sputtered by ion bombardment and are scattered and evaporated, or blackening due to sticking to the inner surface of the glass tube 1 by the electrode member or blackening by the electron emitting material sticking to the inner surface of the cup-shaped electrode _42A is prevented. Radiation can be utilized, and by reattaching the electron-emitting substance to the surface of the cylindrical electrode _41A , the regeneration effect of the electron-emitting substance can be utilized, a long life can be achieved, and a sufficient discharge current can be achieved. As a result, the amount of light is increased, and high-luminance light emission is obtained.

Table 1 below shows electrical discharge tubes each having a phosphor screen 2A in which a transparent conductive material is added to a phosphor and a conventional discharge tube having a phosphor screen 2 only in which a transparent conductive material is not added. The results of measuring the characteristics are shown. As is clear from Table 1, in a discharge tube structure having a fluorescent surface 2A with a conductive material added and having a trigger function, a discharge tube with a tube diameter of about 3 mm and a tube length of about 200 mm has sufficient light emission as before. While maintaining the brightness, the discharge starting voltage can be made lower than before and the mounting on the backlight becomes easy.

[0016]

[Table 1]

As a comparative example, in the discharge tube in which the fluorescent material contains 15 wt% or more of the transparent conductive material, the discharge starting voltage is about 4
Although it is as low as 00V, it is easy to mount it on the backlight, but the brightness is reduced to about 90%.

In the above-mentioned embodiment, the case where the transparent conductive material added to the phosphor is within the range of about 5 wt% has been described, but if this range is 1 wt% or less,
Sufficient trigger effect cannot be obtained, and if it is 10 wt% or more, the emission characteristics are impaired and sufficient emission brightness cannot be obtained. Therefore, the addition of the transparent conductive material is 1 to 10 w
The t% range was extremely effective.

Further, although the case where In ₂ O ₃ and ZnO are used as the transparent conductive material has been described in the above-mentioned embodiment, the present invention is not limited to this.
Even if SnO ₂ or the like is used instead of In ₂ O ₃ or ZnO, the same effect as described above 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, 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.

[0021]

As described above, according to the present invention,
1 to 10% by weight of transparent conductive material on the phosphor screen
By being electrically connected to either one of the inner leads of a pair of electrode devices that are contained in the range of and the fluorescent surface is opposed to the fluorescent surface, the fluorescent surface can simultaneously function as a trigger electrode together with fluorescent light emission. Therefore, the discharge starting voltage can be lowered to meet the demand for downsizing such as thinning the diameter of the glass tube and increasing the tube length, and the discharge can be started easily. Also, when adding the trigger electrode to the glass tube, the trigger electrode can be provided without being influenced by the mounting directionality thereof, and further, since the mounting directionality is lost, the trigger electrode of the discharge tube is not used when used as a backlight. An extremely excellent effect such as a simple mounting process can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional view 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,
(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 2A 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 opposed to each other in a discharge space in which a fluorescent screen is formed on an inner wall surface of a glass tube whose both ends are hermetically sealed and at least a rare gas and mercury are sealed. In the discharge tube, the phosphor screen contains a transparent conductive material in a range of 1 to 10% by weight with respect to the phosphor, and the phosphor screen is electrically connected to one of the inner leads. And discharge tube.