JPH07142027A - Discharge tube - Google Patents

Abstract

PURPOSE:To provide high efficiency and high brightness over a long period of time, and lengthen the service life by restraining the blackening of the tube wall of a glass tube. CONSTITUTION:A pair of electrode devices 4A connected to inner leads 3 are arranged opposite in the discharge space of an airtightly sealed glass tube 1, and the pair of electrode devices 4A are composed of a column-shaped electrode 41A constituted by doping La by 0.2mol% to BaTiO3 and an Al cup-shaped electrode 42A which covers this column-shaped electrode 41A and captures an electron emitting substance scattered, evaporated and emitted from the column- shaped electrode 41A. In the column-shaped electrode 41A, since preferentially gasified Ba is captured by the cup-shaped electrode 42A, the blackening of a tube wall is restrained. Since the captured Ba is kept in the same electric potential, it acts as an electron emitting substance on an inside surface of the cup- shaped electrode 42A, so that high electron emitting efficiency is maintained over a long period of time.

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, high efficiency and high brightness are required, and long life is required.

FIG. 4 is a diagram for explaining the structure of this type of discharge tube. FIG. 4 (a) is a cross-sectional view of an essential part showing the overall structure, FIG. 4 (b) is a perspective view of an electrode device, and FIG. (C) is the sectional drawing. In FIG. 4, 1 is a transparent glass tube whose both ends are hermetically sealed to form a discharge tube body, and 2 is this glass tube 1.
3 is an inner lead made of, for example, a Ni material held through both ends of the glass tube 1 in the longitudinal direction, and 4 is attached to the tip of each inner lead 3. The electrode devices are arranged to face each other on the same axis in the longitudinal direction of the glass tube 1, and these electrode devices 4 are formed of a sintered body such as BaTiO ₃ (barium titanate) which is an electron emitting substance. . In addition, in the glass tube 1, for example, about 60 argon gas for discharge is used.
A mixed gas of Torr and a small amount of mercury is enclosed. The structure of the electrode device 4 of this type of discharge tube is disclosed in, for example, Japanese Utility Model Publication No. 5-14453.

The discharge tube constructed in this manner has sufficient mechanical strength as an electrode and is made of a raw material by forming the electrode device 4 from a sintered body of BaTiO ₃ as an electron emitter. Since the electrode can be formed without deteriorating the characteristics, it works as an arc discharge electrode, and an ultra-high brightness discharge can be stably obtained.

[0005]

However, in the discharge tube having such a structure, the electrode device 4 is made of BaT.
Since it is formed of a sintered body of iO ₃ and the like, high electron emission efficiency can be obtained, but the activation time required to obtain this high electron emission efficiency is about 100 hours, which is extremely long, so a great deal of man-hours are required. That is, there is a problem that productivity is lowered. Further, the electrode device 4 configured in this way
Although high electron emission efficiency is obtained, only Ba (barium) is preferentially vaporized and adhered to the inner surface of the glass tube 1 for long-term use, and the blackening of the tube wall becomes large, and BaT
Since iO ₃ deviates from the stoichiometric ratio, the electron emission efficiency is likely to deteriorate and the life tends to be short, so that the life cannot be extended and high efficiency and high luminance emission cannot be obtained for a long time. It was

Therefore, the present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to provide a discharge tube capable of achieving high efficiency and high brightness and high productivity. Especially. Another object of the present invention is to provide a discharge tube capable of suppressing blackening of the wall of the inner surface of the glass tube, achieving high efficiency and high brightness over a long period of time, and achieving a long life. .

[0007]

In order to achieve such an 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 connected electrode devices are arranged opposite to each other, and at least one of the pair of electrode devices is formed by doping BaTiO ₃ with 0.1 to 5 mol% of La. Further, in a discharge tube according to another invention, 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. At least one of the electrode devices added BaTiO ₃ with La.
A first electrode formed by doping 1 to 5 mol%;
The second electrode 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 composed of BaTiO ₃ and L
By doping a by 0.1 to 5 mol%, Ba is partially metallized and made into a semiconductor, so that activation can be unnecessary. In addition, the first electrode in the other electrode device of the present invention comprises BaTiO ₃ containing 0.1 to 5 mol of La.
%, The Ba is partially metallized and turned into a semiconductor, so that activation can be dispensed with, and by providing the second electrode, Ba vaporized preferentially from the first electrode becomes It is captured by the second electrode and the blackening of the tube wall is suppressed. Also, since the captured Ba is kept at the same potential,
It acts as an electron emitting substance on the inner surface of the second electrode, and high electron emitting efficiency is maintained for a long period of time.

[0009]

Embodiments of the present invention will now be described in detail with reference to the drawings. (Embodiment 1) FIG. 1 is an enlarged sectional view of an essential part showing a structure according to an embodiment of a discharge tube according to the present invention. 4C is an enlarged perspective view thereof, and (c) is a sectional view thereof, and the same portions as those in FIG. 4 are denoted by the same reference numerals. In Figure 1, the diameter is about 4 mm,
A pair of electrode device 4A disposed opposite to both ends of the glass tube 1 having a length of about 260mm surrounds a columnar electrode 4 _1A provided at the distal end of the inner lead 3 made of Ni material, the columnar electrode 4 _1A It is composed of an Al cup-shaped electrode _42A .

The columnar electrode 4 _1A is formed by doping, for example, BaTiO ₃ as an electron emitting substance with La in a range of about 0.2 mol%. Specifically, the columnar electrode 4 _1A was prepared by mechanically mixing BaTiO ₃ powder and La ₂ O ₃ powder so that the doping amount of La would be about 0.2 mol%. A sintered body electrode can be formed by firing at a temperature of about C for about 2 hours. The columnar electrode _41A has a diameter of about 2
It has a size of about mm and a length of 1 mm.

The Al cup-shaped electrode _42A is formed into a substantially conical shape by press-molding an aluminum plate material, and its dimensions are about 2.5 mm inside diameter and about 2.7 mm outside diameter.
It is formed in the size of about. The Al cup-shaped electrode 4 _2A is inserted into the inner lead 3 and surrounds the columnar electrode 4 _1A provided at the tip of the inner lead 3 and is caulked and fixed to the inner lead 3 at the root portion thereof and arranged on the concentric shaft. It is configured to. In addition, inside the glass tube 1,
A mixed gas of argon gas of about 60 Torr and a small amount of mercury is enclosed.

In such a structure, the columnar electrode 4 _1A is enclosed in the conical Al cup-shaped electrode 4 _2A so that the columnar electrode 4 _1A has an appropriate temperature for emitting thermoelectrons. It can be raised to emit light with high brightness. Further, the cup-shaped electrode 4 _2A suppresses the blackening of the tube wall due to the thermionic emissive material that is sputtered by the ion bombardment of the columnar electrode 4 _{1A and} is scattered and evaporated or the electrode member adheres to the inner surface of the glass tube 1. Thermionic emission by the electron emitting material attached to the inner surface of the cup-shaped 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 columnar electrode _41A , the consumption of the electron emitting substance is extremely reduced and a sufficient discharge current can be obtained. As a result, the amount of light is increased, high-luminance light emission is obtained, high electron emission efficiency is maintained for a long time, and a long life can be achieved.

Further, according to this structure, the columnar electrode _41A serves as an electron emitter and is formed of, for example, BaTiO _{3 or} L.
By doping about 0.2 mol% of a, Ba partially becomes a metal and becomes a semiconductor, so that a long aging step for activation can be unnecessary, and therefore, high electron emission efficiency and high electron emission efficiency can be obtained. A discharge tube having bright light emission and long life can be obtained by reducing the number of manufacturing steps, and the productivity can be improved.

(Embodiment 2) In Embodiment 1 described above, the columnar electrode _41A has BaTiO ₃ and La of about 0.2.
Although the case of doping with mol% has been described, substantially the same effect can be obtained even when BaTiO ₃ is doped with about 4 mol% of La as another example.

Further, in the above-mentioned Examples 1 and 2, the case where the doping amount of La to be doped into BaTiO ₃ was set to about 0.2 mol% and about 4 mol% was explained. If it is less than 0.1 mol%, there is no effect in shortening the activation time, and about 5 mo
exceeds l%, because the columnar electrode 4 _1A is life to short life, the doping amount of La as a result in the range of 0.1 to 5 mol% experimental, it was confirmed that the preferable effect can be obtained.

(Embodiment 3) FIGS. 2A and 2B are views showing the structure of a discharge tube according to another embodiment of the present invention. FIG. 2A is a sectional view showing the overall structure of the discharge tube, and FIG. 4C is an enlarged perspective view thereof, and (c) is a sectional view thereof, and the same portions as those in FIG. 4 are denoted by the same reference numerals. 2 is different from FIG. 1 in that a pair of electrode devices 4B, which are arranged opposite to each other on both ends of a glass tube 1 having a diameter of about 4 mm and a length of about 260 mm, have an electronic lead at the tip of an inner lead 3 made of Ni material. As a radiation material, for example, BaTiO ₃ is doped with La in a range of about 0.2 mol%. That is, in the third embodiment, the electrode device 4B is different from the above-described first and second embodiments in that the electrode device 4B does not have the cup-shaped electrode _42A . Even in this case, the electrode device 4B has a diameter of about 2 m.
It has a size of about m and a length of 1 mm.

In such a structure, the electrode device 4B
Has high thermoelectron emission efficiency, so even if it emits high brightness light,
There are few sputters due to ion bombardment, and few thermionic emissive substances that evaporate and evaporate.

Further, according to this structure, the electrode device 4B is made of, for example, BaTiO _{3 or} L as an electron emitter.
By doping a with 0.1 to 5 mol%, part of Ba is metallized and made into a semiconductor, so a long aging step for activation, a step of forming a cup-shaped electrode, and an inner lead of this cup-shaped electrode. 3 can be eliminated, and therefore the number of manufacturing steps of the discharge tube having high electron emission efficiency and high brightness light emission can be further shortened, so that the productivity can be greatly improved.

(Embodiment 4) Also in the above-described Embodiment 3, the electrode device 4B has BaTiO ₃ and La of about 0.
Although the case of doping with 2 mol% was described, the same effect as described above was obtained even when BaTiO ₃ was doped with about 4 mol% of La as another example.

Further, in the above-mentioned Examples 3 and 4, the case where the doping amount of La to be doped into BaTiO ₃ was set to about 0.2 mol% and about 4 mol% was explained. no effect is less than 0.1 mol%, When it exceeds about 5 mol%, since the columnar electrode 4 _1A is life to short life, the doping amount of La is preferably in the range of 0.1 to 5 mol%.

In FIG. 3, a mixed gas of argon gas of about 60 Torr and a small amount of mercury is enclosed, and a tube diameter of about 4 mm and a tube length of about 260 mm in which a phosphor screen 2 is formed on the inner surface of a glass tube 1 according to the conventional example 1 is made of BaTiO _3. Electrode device 4 consisting of a sintered body of
And a discharge tube arranged opposite to each other and Ti ₃ Hg according to Conventional Example 2
And a BaTiO ₃ according to the first embodiment with La of about 0.2 mo.
A discharge tube in which an electrode device 4A in which a columnar electrode 4 _1A doped with 1% and a cup-shaped electrode 4 _2A is arranged opposite to each other, and a columnar electrode 4 _{1A in} which BaTiO ₃ according to Example 2 is doped with about 4 mol% of La and a cup are formed. A discharge tube in which an electrode device 4A in combination with a _circular electrode 4 _2A is disposed oppositely, an electrode device 4B in which BaTiO ₃ according to the example 3 is doped with La at about 0.2 mol%, and a BaTiO ₃ according to the example 4 are included. L
Discharge with respect to the number of times of switching (30 seconds on, 30 seconds off) when a tube current is supplied to each of the electrode device 4B only doped with about 4 mol% of a and the tube current is kept constant at about 14 mA. Change in voltage, that is, about 14mA
3 shows a change in discharge voltage for maintaining the tube current of No.

As shown in FIG. 3, in Conventional Example 1, activation of about 100 H (hours) is required for the discharge voltage to reach about 250V. Further, in the conventional example 1 and the example 4, the discharge voltages are about 350 V and 340, respectively, after opening and closing about 40,000 times.
Rise to V. Further, in the third embodiment, the voltage rises to about 340V after opening / closing about 80,000 times. On the other hand, in Example 1 and Example 2, after opening and closing about 100,000 times, each about 250
A low discharge voltage of V, 260V is maintained. In addition, in Examples 1 to 4, aging of about 100H is performed under the same conditions.

Therefore, as is apparent from FIG.
With the configuration according to Example 2, high electron emission efficiency is initially obtained at a low discharge voltage (about 240 to 250 V), and subsequently about 250 V, 260 even after opening and closing about 100,000 times.
The tube voltage of about V was maintained, and the electron emission efficiency was extremely good. That is, it was confirmed that high-luminance light emission with high electron emission efficiency can be obtained for a long period of time. Also, in the configurations according to Example 3 and Example 4, since the tube voltage of about 340 V can be maintained by opening / closing up to about 80,000 times, the electron emission efficiency becomes good, and high electron emission efficiency and high-luminance light emission are achieved. It was confirmed that it can be obtained over a relatively long period of time.

Further, although the conventional hot cathode tube can obtain high brightness and high efficiency, the hot cathode tube having a short life and a small tube diameter is difficult to manufacture, and the cold cathode tube is Although a long life can be obtained, it has low luminance and low efficiency. On the other hand, the structure of the electrode device 4A and the electrode device 4B according to the present embodiment is as easy to manufacture as a cold cathode tube and is easy to manufacture. A long-life, high-luminance, high-efficiency discharge tube with a small tube diameter that can be used as a backlight can be easily realized.

In the above-described embodiment, the columnar electrode 4 _1A and the electrode device B are made of BaTiO ₃ powder,
The case where a mixture of La ₂ O ₃ powder and a mechanically mixed La doping amount to a predetermined amount is fired to form a sintered electrode has been described, but the present invention is not limited to this. The same effect as described above can be obtained by using a structure such as a sintered body obtained from a LaTiO ₃ -doped BaTiO ₃ powder, a plasma sprayed body, or a molded body made of a slurry.

Further, in the above-mentioned embodiment, the case where the molded body made of an aluminum material is used as the cup-shaped electrode 4 _2A has been described, but a molded body made of Ti, Ta, Mo, W or a stainless steel material is also used. Similar effects were obtained.

[0028]

As described above, according to the present invention,
A pair of electrode devices connected to the inner leads are arranged opposite to each other in a discharge space of a glass tube whose both ends are hermetically sealed, and at least one of the pair of electrode devices is placed on the BaTiO _{3 layer} .
By doping a with 0.1 to 5 mol% of Ba, Ba is partially metallized and becomes a semiconductor, so that electron emission efficiency can be maintained for a long period of time without activation, and highly efficient discharge characteristics can be obtained. As a result, the number of manufacturing steps can be greatly reduced, and a highly efficient and compact discharge tube having high efficiency and high brightness light emission can be obtained.

According to another aspect of the invention, a pair of electrode devices connected to the inner leads are arranged opposite to each other in an electric space of a glass tube whose both ends are airtightly sealed, and at least one of the pair of electrode devices is arranged at least oppositely. 0.1 to 5 m of La in BaTiO ₃
By comprising a first electrode configured by ol% doping and a second electrode that covers the first electrode and captures an electron emitting substance that is scattered and evaporatively emitted from the first electrode, Ba that is preferentially vaporized from the first electrode is captured by the second electrode, blackening of the wall of the tube is suppressed, and the captured Ba is kept at the same potential, so that the electron-emitting substance on the inner surface of the second electrode As a result, high electron emission efficiency can be maintained for a long period of time, and highly efficient discharge characteristics can be obtained. Therefore, in addition to the above effects, a compact, highly efficient, high-luminance light emission can be obtained and a long-life discharge tube can be obtained. It has an extremely excellent effect of being 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.

2A is a cross-sectional view showing the structure of a discharge tube according to another embodiment of the present invention, FIG. 2B is an enlarged perspective view showing the structure of an electrode device, and FIG. 2C is its cross-sectional view.

FIG. 3 is a diagram showing the relationship between the discharge voltage and the number of times of opening and closing of each discharge tube according to the present embodiment and a conventional discharge tube.

FIG. 4A is a cross-sectional view showing a 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 4 _1A columnar electrode 4 _2A cup-shaped electrode 4A electrode device 4B electrode device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Fuyuki Sato 1-3-1, Noritake Shinmachi, Nishi-ku, Nagoya, Aichi Prefecture No. 36 Noritake Company Limited (72) Inventor Go Maeda 3-chome, Noritake Shincho, Nishi-ku, Nagoya, Aichi Prefecture No.36 Noritake Company Limited (72) Inventor Tokuhide Shimojo 700 Wada, Ueno-cho, Ise City, Mie Prefecture 700 Ise Electronics Industry Co., Ltd. (72) Masao Uchiyama 700, Wada, Ueno-cho, Ise City, Mie Prefecture Address inside Ise Electronics Industry Co., Ltd.

Claims (2)

[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.
At least one of the pair of electrode devices is constructed by doping BaTiO ₃ with 0.1 to 5 mol% of La. 2. 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.
At least one of the pair of electrode devices is formed by doping BaTiO ₃ with 0.1 to 5 mol% of La.
Discharge electrode, and a second electrode that covers the first electrode and that captures an electron emitting substance that is scattered and evaporatively emitted from the first electrode.