JPH0917376A - Electrode for fluorescent lamp and its manufacture - Google Patents

Abstract

PURPOSE: To lengthen the service life by shortening time of glow discharge at starting time. CONSTITUTION: In an electrode for a fluorescent lamp having a metallic cup 1 which has a side wall 1b on the peripheral end of a bottom part 1a and is formed into a cylindrical shape and a cylindrical body made of a high melting point metal 4 which is housed in the metallic cup 1 and opens on the opposite side of the bottom part 1a, an electron emissive substance 2 is filled between the side wall 1b of the metallic cup 1 and the cylindrical body 4. Therefore, in a glow discharge period at starting time, hollow negative electrode discharge is generated in the cylindrical body 4, and the cylindrical body 4 is warmed. Since a cylindrical structure can easily accumulate cations and hardly causes a radiation loss, a temperature of the cylindrical body 4 easily rises. Therefore, most of ion bombardments applied to a negative electrode in a glow discharge period is shut up inside the cylindrical body 4, and the electron emissive substance 2 is heated in a short time, and reaches a thermoelectron emitting temperature, and time to transfer to arc discharge from glow discharge is shortened, and the service life can be lengthened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluorescent lamp electrode and a method for manufacturing the same.

[0002]

2. Description of the Related Art FIG. 9 shows a conventional fluorescent lamp electrode disclosed in JP-A-57-96453. The fluorescent lamp electrode is a cold cathode and has a bottomed cylindrical shape. The metal emissive material 2 is filled in the metal cup 1 and the conductive fiber 3 is dispersed in the electron emissive material 2.

Since such an electrode for a fluorescent lamp has a metal cup 1 filled with an electron emissive substance 2,
As compared with a hot cathode of a fluorescent lamp in which a filament winding is filled with an electron emitting substance, a large amount of the electron emitting substance 2 can be supported. Further, since it is well known that there is a close correlation between the lamp life and the amount of electron emissive material, the electrode structure as described above has a great advantage in extending the life of the fluorescent lamp. Can be said to have.

However, in general, the cold cathode does not have a filament for emitting a thermoelectron by preheating an electron emissive material applied to the cathode by supplying a preheating current to the cathode at the initial stage of lighting like the hot cathode. , About 500 at start
It requires a high starting voltage of ~ 550V.

Therefore, the cathode heating of the cold cathode is performed by bombarding the cathode with the ions accelerated by the cathode drop voltage formed on the front side of the cathode in the glow discharge state after the application of the starting voltage. As a result, the electron emissive material reaches the operating temperature of thermionic emission, the glow discharge shifts to an arc discharge, and a current starts to flow between the electrodes to turn on the fluorescent lamp.

[0006]

However, in the conventional cold cathode fluorescent lamp electrode constructed as described above, the time required for transition from glow discharge to arc discharge is as long as about 1 to 2 seconds. The long glow discharge time means that the amount of sputtering of the cathode material by the high-speed ions accelerated by the high cathode drop voltage increases, which contaminates the cathode surface and reduces the electron emission capability. There are problems that the electron emissive material 2 is scattered and the tube wall near the cathode is blackened to shorten the life of the fluorescent lamp.

The present invention has been made in view of the above problems, and it is an object of the present invention to shorten the glow discharge time at the time of start-up and extend the life of the cold cathode fluorescent lamp electrode. Another object of the present invention is to provide an electrode for a fluorescent lamp, and another object thereof is to provide a method for manufacturing the electrode for a fluorescent lamp.

[0008]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a bottom portion 1a according to the first aspect of the invention.
Has a metal cup 1 formed in a tubular shape with a side wall 1b at the peripheral end thereof, and a tubular body 4 made of a high melting point metal and housed in the metal cup 1 and opened on the side opposite to the bottom portion 1a. An electrode for a fluorescent lamp as described above, characterized in that the electron emissive substance 2 is filled between the side wall 1b of the metal cup 1 and the cylindrical body 4.

Further, in the invention according to claim 2, in the fluorescent lamp electrode according to claim 1, the cylindrical body 4 is provided.
Is formed of a refractory metal having fine pores, and the cylindrical body 4 is impregnated with the electron emissive substance 2.

Further, in the invention according to claim 3, in the fluorescent lamp electrode according to claim 1 or 2, heat generated in the tubular body 4 is generated outside the tubular body 4. A heat conducting fin 4a for conducting the electron emissive material 2 filled in the metal cup 1 is provided.

Further, in the invention according to claim 4, in the fluorescent lamp electrode according to any one of claims 1 to 3, the cylindrical body 4 is opposite to the opening. It is characterized in that the bottom plate portion 4b is provided on the side so as to have a bottom.

The invention of claim 5 provides the method of manufacturing an electrode for a fluorescent lamp according to claim 4, wherein the metal cup 1 is filled with an electron emissive material 2 and then the metal cup 1 is filled. In addition, the tubular body 4 is press-fitted from the bottom plate portion 4b side.

[0013]

With the above-mentioned structure, the present invention provides the invention according to claim 1 in which the hollow portion inside the tubular body 4 has one side of the tubular body 4 during the glow discharge period at the time of starting. A hollow cathode discharge occurs in which the electrons emitted from hit the opposite surface and heat it, and are reflected and returned to the vicinity of the original surface again. Further, the tubular structure tends to accumulate positive ions, and since the radiation loss is small, the temperature of the tubular body 4 is likely to rise. As a result, most of the ion bombardment that the cathode receives during the glow discharge is confined inside the tubular body 4, and the electron emissive material 2 filled inside the metallic cup 1 and outside the tubular body 4 is short. It is heated in the paddle time to reach the thermionic emission temperature, and the time for transition from glow discharge to arc discharge is shortened.

According to the second aspect of the present invention, in addition to the function of the fluorescent lamp electrode according to the first aspect, the electron emissivity filled in the tubular body 4 during the glow discharge period at the time of starting. Thermionic electrons are also emitted from the substance 2 to improve the electron emission ability of the fluorescent lamp electrode, and the electron emissive substance 2 filled inside the metal cup 1 and outside the cylindrical body 4 is heated in a shorter time. As a result, the time to reach the thermionic emission temperature and transition from glow discharge to arc discharge is further shortened.

Further, in the invention described in claim 3, in addition to the function of the fluorescent lamp electrode according to claim 1 or claim 2, the heat conduction fins 4a are filled in the metal cup 1. The heat generated in the tubular body 4 is efficiently conducted to the radioactive substance 2, and the electron radioactive substance 2 is heated in a shorter time to reach the thermionic emission temperature, and the time required for transition from glow discharge to arc discharge is further increased. It gets shorter.

Further, in the invention described in claim 4, in addition to the function of the fluorescent lamp electrode according to any one of claims 1 to 3, the inside of the cylindrical body 4 is provided. It is difficult for the electron emissive substance 2 to enter, and it is easy to manufacture.

The invention of claim 5 provides the method of manufacturing an electrode for a fluorescent lamp according to claim 4, wherein the metal cup 1 is filled with the electron emissive material 2 and then the metal cup 1 is filled. In addition, if the tubular body 4 is press-fitted from the bottom plate portion 4b side, an electrode for a fluorescent lamp can be manufactured, and the workability of manufacturing is good.

[0018]

1 and 2 show a first embodiment of an electrode for a fluorescent lamp according to the present invention. The electrode for a fluorescent lamp comprises a metal cup 1, an electron-emitting substance 2 and a tubular body. 4,
And an introduction line 5.

The metal cup 1 is made of metal having conductivity, for example, iron, and a cylindrical side wall 1b is erected on the peripheral end of a substantially disc-shaped bottom portion 1a so as to open to one side. The outer surface of the side wall 1b is formed of, for example, a copper wire,
Or a pair of lead wires 5 composed of nickel-plated iron wires
Are welded.

The tubular body 4 is made of a high melting point metal such as tantalum, tungsten, or molybdenum, and a cylindrical side plate portion 4c is provided upright on the peripheral end of a substantially disc-shaped bottom plate portion 4b. The metal cup 1 is formed into a cup shape having a smaller diameter than the metal cup 1 and substantially the same height.

The tubular body 4 is placed in the metal cup 1 such that the bottom plate portion 4b of the tubular body 4 is substantially in contact with the bottom portion 1a of the metal cup 1, and is housed in the metal cup 1. On the outside of the side plate portion 4c of the cylindrical body 4, that is, between the side wall 1b of the metal cup 1 and the side plate portion 4c of the cylindrical body 4, an electron emissive substance 2 such as barium tantalate is formed in a cylindrical shape. It is filled up to the vicinity of the opening which is the upper end of the tubular body 4 so as not to enter the inside of the body 4.

The fluorescent lamp electrode thus constructed is disposed near both ends of a glass bulb 6 having an inner wall coated with a phosphor 6a as shown in FIG. A fluorescent lamp is formed by filling vapor and argon gas which is a rare gas. Then, the electron emissive substance 2 filled in the metal cup 1 is activated in the exhausting process of the bulb 6 as in a normal fluorescent lamp. As a method of the activation treatment, for example, a method of causing hollow cathode discharge to heat by the tubular body 4 while flowing an inert gas such as argon in the bulb 6 or a method of performing dielectric heating of the electrode portion is performed. Etc.

This hollow cathode discharge is a discharge using a hollow cathode having a hollow cylindrical shape in which a negative glow appears so that it is considered as a kind of glow discharge. In the hollow cathode discharge, in the hollow portion inside the tubular body 4, electrons emitted from one side plate 4c of the tubular body 4 hit the surface on the opposite side and heat it, and then it is reflected back to the vicinity of the original surface. As a result, the hollow cathode effect is produced in which the electron emission capability of the cathode is increased.

With this structure, in the fluorescent lamp electrode according to the present embodiment, during the glow discharge period at the time of starting, since the tubular body 4 has a small diameter, the hollow inside the tubular body 4 is used. In the portion, a hollow cathode discharge occurs in which electrons emitted from one side of the side plate portion 4c of the tubular body 4 hit the surface on the opposite side and heat it, and are reflected back to the vicinity of the original surface and return, resulting in electron emission. Ability is improved. In addition, the cylindrical structure easily accumulates positive ions, and the radiation loss is small, so that the temperature of the cylindrical body 4 easily rises. As a result, most of the ion bombardment received by the cathode during the glow discharge period is confined inside the tubular body 4, the electron emissive material 2 is not directly damaged by the ion bombardment, and is kept inside the metal cup 1. Emissive material 2 filled outside the cylindrical body 4
Is heated for a short time to reach the thermionic emission temperature, and the time for transition from glow discharge to arc discharge that produces bright spots on the electron-emitting substance 2 is about 0.8 seconds, which is 1 to 2 seconds compared to the conventional one. It gets shorter.

Therefore, the amount of spatter during glow discharge is reduced, the electron emission capability due to contamination of the cathode surface and the scattering of the electron emissive material 2 can be suppressed, and the electron emissive material 2 held by the cold cathode is suppressed. Is effectively consumed, and the life is about 1.5 to 2 times that of the conventional cold cathode. Further, the tubular body 4 has a bottomed tubular shape with one end shielded by the bottom plate portion 4b, and the electron emissive substance 2 is less likely to enter the inside of the tubular body 4 during manufacturing, which facilitates manufacturing.

FIG. 3 shows a modification of the fluorescent lamp electrode shown in the first embodiment. In the first embodiment, when the tubular body 4 is housed in the metal cup 1, the metal cup 1
The cylindrical body 4 is formed so as to have a high height so as to project from the inside. Even if configured in this way, the same effect as that of the first embodiment is obtained, and the inside of the cylindrical body 4 is manufactured at the time of manufacturing. It becomes more difficult for the electron emissive substance 2 to enter, and it is easier to manufacture.

FIG. 4 shows another modification of the fluorescent lamp electrode shown in the first embodiment. In the first embodiment, the metal cup 1 and the cylindrical body 4 are provided with bottomed corners, respectively. It is formed in a tubular shape. Even with this structure, substantially the same effect as that of the first embodiment can be obtained.

FIG. 5 shows a second embodiment of the fluorescent lamp electrode of the present invention.
Of the present invention, which is different from the first embodiment in the cylindrical body 4, and is otherwise configured similarly to the first embodiment.

The cylindrical body 4 is formed of, for example, a member having fine holes made of tungsten as a base metal, has a bottomed cylindrical shape, and the fine holes are of the same type as those filled in the metal cup 1. The electron emissive substance 2 is filled in to form a so-called impregnated electrode.

Due to this structure, in the fluorescent lamp electrode of this embodiment, in addition to the effects of the first embodiment, the tubular body 4 is filled during the glow discharge period at the time of starting. Thermionic electrons are also emitted from the generated electron emissive material 2 to improve the electron emission capability of the fluorescent lamp electrode, and the electron emissive material 2 filled inside the metal cup 1 and outside the cylindrical body 4 is further shortened. It is possible to further shorten the time for transition from glow discharge to arc discharge by heating for a short time to reach thermionic emission temperature, and to obtain a fluorescent lamp electrode with a longer life.

FIG. 6 shows a third embodiment of the fluorescent lamp electrode of the present invention.
The difference from the first embodiment is that the heat of the tubular body 4 is applied to the outside of the side plate portion 4c of the tubular body 4,
This is that a plurality of heat conducting fins 4a made of the same material as the tubular body 4 are provided for conducting to the electron emissive material 2 filled in the metal cup 1, and other points are the same as in the first embodiment. It is configured.

With this structure, in the fluorescent lamp electrode of this embodiment, in addition to the effects of the first embodiment, the heat conducting fin 4a is replaced by the metal cup 1
The heat generated in the cylindrical body 4 is efficiently conducted to the electron emissive material 2 filled in the, and the electron emissive material 2 is heated in a shorter time to reach the thermionic emission temperature, and the glow discharge is changed to the arc discharge. The transition time can be further shortened, and a long-life fluorescent lamp electrode can be obtained.

In this embodiment, the heat conducting fins 4a are provided on the cylindrical body 4 shown in the first embodiment, but the present invention is not limited to this, and the second embodiment can be applied. It may be provided on the cylindrical body 4 shown.

In each of the above embodiments, the cylindrical body 4
Although the bottom has a bottom plate portion 4b, the present invention is not limited to this, and a cylindrical body having openings at both ends may be bonded to the bottom portion 1a of the metal cup 1.

FIG. 7 shows a method of manufacturing an electrode for a fluorescent lamp according to the present invention. As shown in the first to third embodiments, the electrode for a fluorescent lamp having a cylindrical body 4 with a bottom is manufactured. It shows a method.

That is, first, as shown in FIG. 1A, for example, the metal cup 1 shown in the first embodiment (introduction line is not shown).
Then, a predetermined amount of the electron emissive substance 2 is filled. After that, the cylindrical body 4 is press-fitted into the electron-emitting substance 2 from the bottom plate 4b side in the first embodiment, which is the opposite side of the opening, as shown in FIG. To obtain various fluorescent lamp electrodes. Since it is manufactured by such a method, the fluorescent lamp electrode can be manufactured only by press-fitting the tubular body 4 into the metal cup 1 filled with the electron emissive material 2, and the manufacturing workability is good.

In this embodiment, as shown in FIG. 8, if the side opposite to the opening which is the tip of the cylindrical body 4 is made thin, for example, conical, it is easy to press fit into the electron emitting substance 2. Therefore, the workability of manufacturing is further improved.

[0038]

As described above, according to the first aspect of the present invention, during the glow discharge period at the time of starting, the hollow portion inside the tubular body is provided with one of the side surfaces of the tubular body. A hollow cathode discharge occurs in which electrons emitted from one side hit the opposite surface and heat it, and are reflected back to the vicinity of the original surface and returned. Further, the tubular structure tends to accumulate positive ions, and since the radiation loss is small, the temperature of the tubular body is likely to rise. As a result, most of the ion bombardment that the cathode receives during the glow discharge period is confined inside the tubular body, and the electron emissive material filled inside the metallic cup and outside the tubular body is heated in a short time. As a result, the time required to reach the thermionic emission temperature and transition from glow discharge to arc discharge is shortened, and a long-life cold cathode fluorescent lamp electrode is obtained.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, heat is also generated from the electron emissive material filled in the tubular body during the glow discharge period at the time of starting. Electrons are emitted and the electron emission capability of the fluorescent lamp electrode is improved, and the electron emissive material filled in the outside of the cylindrical body inside the metal cup is heated in a shorter time to reach the thermoelectron emission temperature. The time taken to reach the arc discharge from the glow discharge is further shortened, and a long-life cold cathode fluorescent lamp electrode is obtained.

Further, in the invention described in claim 3, in addition to the effect of the invention described in claim 1 or 2, the heat-conducting fins are cylindrical in the electron emissive material filled in the metal cup. Conducting the heat of the body efficiently, the electron emissive material is heated in a shorter time to reach the thermionic emission temperature,
The transition time from glow discharge to arc discharge is further shortened, and a long-life cold cathode fluorescent lamp electrode is obtained.

Further, in the invention described in claim 4, in addition to the effect of the invention described in one of claims 1 to 3, in addition to the effect of the invention, the electron emissive substance is provided inside the cylindrical body. Difficult to enter and easy to manufacture.

Further, in the invention according to claim 5, for the fluorescent lamp, if the cylindrical body is press-fitted into the metal cup from the bottom plate side after filling the metal cup with an electron emissive substance. The electrode can be manufactured and the workability of manufacturing is good.

[Brief description of the drawings]

1A and 1B show a first embodiment of an electrode for a fluorescent lamp according to the present invention, wherein FIG. 1A is a front view of a vertical section and FIG. 1B is a plan view.

FIG. 2 is a front view showing a state in which the above-mentioned fluorescent lamp electrodes are held at both ends of the bulb.

FIG. 3 is a perspective view of a main part showing a modified example of the above electrode for a fluorescent lamp.

FIG. 4 is a plan view showing another modification of the above-mentioned fluorescent lamp electrode.

FIG. 5 is a front view of a vertical section showing a second embodiment of the electrode for a fluorescent lamp of the present invention.

FIG. 6 is a partial cross-sectional front view showing a third embodiment of the fluorescent lamp electrode of the present invention.

7A and 7B show a method for manufacturing an electrode for a fluorescent lamp according to the present invention, wherein (a) is a perspective view of a step of filling a metal cap with an electron emissive material, and (b) is a perspective view of a step of press-fitting a tubular body. Figure,
(c) is a perspective view showing a state in which press-fitting is completed.

FIG. 8 is a front view of a vertical cross section showing a modified example of the above-mentioned electrode for a fluorescent lamp.

FIG. 9 is a partial cross-sectional perspective view showing a conventional fluorescent lamp electrode.

[Explanation of symbols]

 1 Metal Cup 1a Bottom 2 Electron Emissive Material 4 Cylindrical 4a Heat Conduction Fin 4b Bottom Plate

Claims (5)

[Claims] 1. A metal cup formed in a tubular shape having a side wall at the peripheral end of the bottom portion, and a tubular body made of a high melting point metal and housed in the metal cup and opening on the side opposite to the bottom portion. An electrode for a fluorescent lamp comprising, wherein an electron emissive material is filled between the side wall of the metal cup and the cylindrical body. 2. The electrode for a fluorescent lamp according to claim 1, wherein the tubular body is formed of a refractory metal having fine holes, and the tubular body is impregnated with an electron emissive material. . 3. A heat conducting fin for conducting heat generated in the tubular body to an electron-emitting substance filled in the metal cup, is provided outside the tubular body, or The fluorescent lamp electrode according to claim 2. 4. The fluorescent lamp according to claim 1, wherein the cylindrical body is provided with a bottom plate portion on the side opposite to the opening so as to have a bottom. electrode. 5. The method of manufacturing an electrode for a fluorescent lamp according to claim 4, wherein after filling the metal cup with an electron emissive substance, the tubular body is press-fitted into the metal cup from the bottom plate portion side. A method of manufacturing an electrode for a fluorescent lamp, comprising: