JP2002025466A - Cathode-ray tube, electron gun and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of surface discharge on the bead glass of the electron gun. SOLUTION: A membrane 26 is formed on the surface of a bead glass 23 (23A, 23B) holding plural electrodes G1-G5, and C by a substance which has the coefficient of secondary electron emission does not exceed than 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a cathode ray tube, an electron gun used for the same, and a method of manufacturing the same.

[0002]

[Prior art]

In general, for example, in a color cathode ray tube, as shown in FIG. 6, a color fluorescent screen 4 is formed on an inner surface of a panel 3 of a glass tube 2 and a color selection mechanism 5 is opposed to the fluorescent screen 4. The electron gun 7 is formed in the neck portion 6. The electron gun 7 has a plurality of electrodes, in this example, red, green,
Three cathodes K [K _R , K _G , K
_B ], the first grid G ₁ , the second grid G ₂ , the third grid G ₃ , the fourth grid G ₄ , and the fifth grid G ₅
And electrostatic convergence means C composed of four electrode plates, and each of these electrodes G ₁ -C is provided with a support pin 8 integrated therewith.
Are held and fixed so as to be embedded in a pair of bead glasses 9 [9A, 9B] facing each other.

Then, for example, the first grid G ₁ has 0
V is the number 100V the second grid G ₂ is, in the third grid G _3, and the fifth grid G _5. 27 to anode voltage
30 kV is applied to the fourth grid, and several kV of the focus voltage is applied to the fourth grid. An anode voltage is applied to the inner electrode plate of the electrostatic convergence means C, and a high voltage lower than the anode voltage is applied to the outer electrode plate.

[0005]

As described above, the electrode parts of the electron gun 7 driven by a high voltage of several tens of kilovolts at the maximum, that is, the first grid G ₁ to the electrostatic convergence means C are made of silica glass. Is held and fixed by a high withstand voltage bead glass 9 [9A, 9B] mainly composed of. Such bead glasses 9A and 9B are inevitably more or less exposed to unnecessary electron radiation due to their structures.

Further, the electrode parts G _{1 to} C formed of metal conductors are held by being cut into the bead glasses 9A and 9B, and form a so-called triple junction together with the surrounding vacuum space. . That is, as shown in FIG. 7, a region where the electrode component (therefore, the support pin 8 integrated with the electrode), the bead glass 9, and the vacuum space 11 are in contact with each other is called a triple junction A. In general, triple junctions at the electrodes tend to cause electron field emission due to electric field concentration.

Accordingly, the bead glasses 9A, 9A of the electron gun 7
B is exposed to electron radiation and is in a state where creeping discharge (so-called creeping flashover) is likely to occur. Once a creeping discharge occurs, it may cause damage to a legitimate electron emission source, destruction of an external circuit, and mental or psychological damage to a user. A number of measures have been taken against creeping discharge, but there is no truly effective method, and no fundamental solution has yet been reached.

The present invention has been made in view of the above circumstances, and provides a cathode ray tube capable of suppressing generation of creeping discharge in a tube. The present invention provides an electron gun capable of suppressing generation of creeping discharge and a method for manufacturing the same.

[0009]

A cathode ray tube according to the present invention is provided with a coating made of a substance having a secondary electron emission coefficient not exceeding 1 on the surface of an insulator in which creeping discharge is likely to occur in a region where an electron gun is arranged. Form and configure.

[0010] In the cathode ray tube of the present invention, by forming a coating of a substance having a secondary electron emission coefficient of not more than 1 on the surface of the insulator where the creeping discharge is likely to occur, the secondary electron emission avalanche on the surface of the insulator is formed. Generation is suppressed. In addition, charge-up of the insulator surface due to the secondary electron emission avalanche is suppressed.

An electron gun according to the present invention is formed by forming a coating of a substance having a secondary electron emission coefficient not exceeding 1 on a surface of a bead glass holding a plurality of electrodes.

In the electron gun of the present invention, the formation of a secondary electron emission avalanche on the surface of the bead glass is suppressed by forming a coating of a material having a secondary electron emission coefficient not exceeding 1 on the surface of the bead glass. In addition, the charge-up of the bead glass surface due to the secondary electron emission avalanche is suppressed, and the electric field emission of electrons from the junction (so-called triple junction) between the electrode, the support pin and the bead glass or the like is suppressed.

The method for manufacturing an electron gun according to the present invention comprises the steps of: forming a metal oxide film having a secondary electron emission coefficient not exceeding 1 on the surface of the bead glass; The method includes a heating step of strengthening the adhesion of the coating and a step of fixing a plurality of electrodes to the bead glass.

In the method for manufacturing an electron gun according to the present invention, since a metal oxide film having a secondary electron emission coefficient not exceeding 1 is formed on the bead glass surface, an electron gun with reduced creeping discharge can be obtained. After the metal oxide film is formed, the metal oxide film is simultaneously heated in a heating step of softening the bead glass, and the metal oxide is diffused into the bead glass or / and the metal oxide is crystallized. As a result, the adhesion strength of the metal oxide film increases. Even in the heating step using an oxidizing gas, the composition of the metal oxide film does not change because it is a metal oxide.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

The creeping discharge which occurs on the bead glass constituting the electron gun is mainly caused by secondary electron emission avalanche (SEEA: Secondary Electron).
nEmission Avalanche). According to this mechanism, when electrons due to unnecessary radiation enter the insulator surface to form a secondary electron emission avalanche, the insulator surface is charged and the field emission of unnecessary electrons is further accelerated. Furthermore, the secondary electron emission avalanche causes the release of surface adsorbed gas, and the insulation gas is destroyed by the action of the released gas and the avalanche electrons, thereby generating a creeping discharge.

In the cathode ray tube and the electron gun of the present invention,
As a means to prevent creeping discharge occurring on the insulator surface,
In particular, for the purpose of limiting the generation of secondary electron emission avalanches,
A method is used in which the insulator surface is coated with a material whose secondary electron emission rate does not exceed 1 for any incident energy of electrons.

FIG. 1 shows an embodiment of an electron gun according to the present invention. Electron gun 21 according to this embodiment, a plurality of electrodes, red in this example, green, three cathodes K corresponding to the blue color [K _R, K _G, K _B] first grid G ₁ having, second grid G _2, the third grid G _3, fourth grid G _4, has an electrostatic convergence means C consisting of the fifth grid G ₅ and four electrode plates, each of these electrodes G ₁ ~
C is held and fixed so as to embed a support pin 22 integrated therewith into a pair of opposed bead glasses 23 [23A, 23B] described later.

In the electron gun 21, for example, 0 V is applied to the first grid G ₁ and several hundreds of low voltages are applied to the second grid G _2.
About V is about 27~30kV anode voltage to the third grid G _3, and the fifth grid G ₅ are, about several kV medium voltage (Fokasu voltage) are respectively applied to the fourth grid.
Further, an anode voltage is applied to the inner electrode plate of the electrostatic convergence means C, and a high voltage lower than the anode voltage is applied to the outer electrode plate.

In this embodiment, as shown in FIGS. 1 and 2, the bead glass 23 [23A,
23B], a coating 26 made of a substance whose secondary electron emission coefficient does not exceed 1, that is, a substance whose secondary electron emission rate does not exceed 1 for any incident energy of electrons is formed. In this example, the bead glass 23 [23A, 23
B] to prevent creeping discharge on the surface facing the electrodes G _{1 to} C side (that is, the side on which the support pins 22 are embedded), and to join the electrode (particularly, the electrode on the low voltage side) to the bead glass 23. In order to prevent the field emission of electrons from the triple junction and the secondary electron emission avalanche occurring in the above, the above described side surfaces 24b (see FIG. 3b) of the bead glass 23 (23A, 23B) except for the inner surface 24a and the outer surface on the electrode side. A film 26 of a substance whose secondary electron emission coefficient does not exceed 1 is formed.

As the substance whose secondary electron emission rate does not exceed 1 for any incident energy of electrons, a metal oxide can be used, and for example, Cr ₂ O ₃ is preferable.

Here, for example, the above-mentioned Cr ₂ O ₃ or TiN is known as a substance whose secondary electron emission rate does not exceed 1 for any incident energy of electrons. However, usable substances for bead glass are limited in the following points.

Each electrode G ₁ -C is connected to a bead glass 23 [23
A, 23B] in the beading step of holding and fixing
22. Support pins attached to part of electrode parts and electrodes
Bead glass 2 in order to embed
3 is heated and softened. At this time, the bead glass 23 is heated in an oxidizing atmosphere in order to prevent the material of the bead glass 23 from being reduced. Therefore, non-oxide such as TiN
It is oxidized and turns into a different substance from the one that serves its original purpose. For this reason, a metal oxide such as Cr ₂ O ₃ is suitable for the bead glass 23.

Further, in order to cope with a large potential difference between the electrodes, the thin film material constituting the coating 26 is required to have high insulation properties. Even when the thin film material does not have the withstand voltage required as the bead glass 23 at the beginning of deposition due to impurities contained in the thin film material and impurities that are mixed in during film formation, a metal oxide such as Cr ₂ O ₃ can be used. If there is, it has a resistance (insulating property) necessary for oxidation in a heating process of beading. Further, as described below,
Since this heating step has the effect of improving the film strength of the metal oxide, that is, the adhesion strength of the metal oxide film to the bead glass, the metal oxide insulating film is not suitable for forming a film on the bead glass. Indicates the height.

According to the electron gun 21 of this embodiment,
Bead glass 23 [2] for holding and fixing each electrode G ₁ -C
3A, 23B], at least the inner surface on the electrode side, of a coating of a substance whose secondary electron emission coefficient does not exceed 1 for any incident energy of electrons, for example, a metal oxide such as Cr ₂ O ₃ . By coating with the film 26, even if electrons due to unnecessary radiation are incident on the surface of the bead glass 23 [23A, 23B], occurrence of secondary electron emission avalanches can be suppressed. In addition, the charge-up of the surface of the bead glass 23 due to the secondary electron emission avalanche is suppressed, and the electric field emission of electrons from the triple junction formed at the junction between the electrode, the support pin 22, the bead glass 23, and the vacuum space is suppressed. Can be.

As a result of the suppression of the secondary electron emission avalanche, or the suppression of the field emission of electrons from the junction between the electrode, the support pin and the bead glass, etc., the creeping discharge in the bead glass 23 results. Can be reduced.

As a substance whose secondary electron emission rate does not exceed 1 for any incident energy of electrons, Cr ₂ O
By using a metal oxide insulator such as _{3 in} the beading process, the coating 2 can be formed without changing the composition of the substance.
6 can improve the film strength and the adhesion strength.

Next, one embodiment of the method for manufacturing the above-described electron gun 21 will be described.
An embodiment will be described. First, as shown in FIG.
Surface of the bead glass 23 [23A, 23B] on the electrode side,
In this example, metal oxide is used on the inner surface 24a and the side surface 24b.
For example, Cr_TwoO _ThreeIs formed. Of coating 26
For deposition, for example, vacuum deposition is allowed, and other
It can be performed by a method such as spraying or slurry application.

Next, as shown in FIG. 3B, the inner surfaces 24a,
A pair of bead glasses 23A and 23B each having a Cr ₂ O ₃ coating 26 formed on the side surface 24b are arranged at predetermined intervals so that the inner surfaces thereof are opposed to each other, and in this state, between the two bead glasses 23A and 23B. Heating means, in this example, the burner 31 is placed, and the inner and side surfaces of the bead glasses 23A and 23B are heated while the burner 31 and the bead glass 23 are relatively moved to soften the bead glasses 23A and 23B. In this heating step, the Cr ₂ O ₃ coating 26 is also heated simultaneously, and the surface of the bead glass 23 and the Cr ₂ O ₃ coating 2
6 melts, and Cr ₂ O ₃ diffuses into the bead glass 23. In particular, when the film 26 is formed by vacuum deposition,
_{Although the 2} O ₃ coating 26 is amorphous, most of it is solidified even when melted and diffused. In addition, Cr
Part of ₂ O ₃ is crystallized so as to bite into the bead glass 23. FIG. 4A shows a state in which the coating 26 before heating is vacuum-deposited, and FIG. 4B shows a state of the coating 26 after heating. FIG.
As shown in B, a diffusion region 32 of Cr ₂ O ₃ is formed, and a part 33 of the coating 26 is crystallized. This diffusion, crystallization, film strength of Cr ₂ O ₃ film 26, i.e., contributes to the improvement of the deposition strength of Cr ₂ O ₃ film 26 to the bead glass 23.

Next, as shown in FIG. 3C, each grid G
_{1 to} G ₅ , the electrostatic convergence means C is coaxially arranged at a predetermined interval, and is brought between the softened bead glasses 23A and 23B to form the bead glass 23.
A and 23B are pressed and each electrode component is held and fixed to bead glasses 23A and 23B. Thus, the intended electron gun 21 is obtained.

According to the method of manufacturing an electron gun according to the present embodiment, the bead glass 23 having the Cr ₂ O ₃ coating 26
[23A, 23B] to form the bead glass 23
By holding and fixing the electrodes to each other, the electron gun 21 with reduced surface discharge can be manufactured. During the heating step, the Cr ₂ O ₃ coating 26 is also heated and melted at the same time, and a part of the Cr ₂ O ₃ is diffused into the bead glass 23 to form the Cr ₂ O 3.
_{3 A} diffusion region 32 is formed and a part 3 of the Cr ₂ O ₃ coating 26 is formed.
By crystallizing 3 so as to bite into the bead glass 23, the film strength, that is, the adhesion of the bead of the film 26 to the lath 23 can be improved.

In the manufacturing process of the cathode ray tube, after the electron gun is sealed and evacuated, a voltage higher than that in normal operation is applied to forcibly generate a discharge to improve the withstand voltage, so-called conditioning or knocking. There is such a process. In a thin film in which the above-mentioned coating film 26 is formed only by vacuum deposition or the like, it is easily peeled off by discharge in this conditioning or knocking process.
take off. The same applies to discharge during normal operation. In this case, the film 26 cannot satisfy the original purpose. However, in the present manufacturing method, as described above, the coating film 26 is also heated at the same time in the heating step, and a part of the film is diffused and crystallized so as to partially penetrate the bead glass, whereby the film strength is improved, and the conditioning, Alternatively, the coating film 26 does not peel or fall off even in the knocking step or in the discharge during normal driving.

According to the present invention, a cathode ray tube is formed by forming a coating of a substance having a secondary electron emission coefficient not exceeding 1 on the surface of an insulator in which creeping discharge is likely to occur in a region where an electron gun is arranged. be able to. FIG. 5 shows the electron gun 21 described above.
1 shows an embodiment of a color cathode-ray tube provided with. The color cathode ray tube 41 has a color fluorescent screen 4 formed on the inner surface of the panel 3 of the glass tube body 2 and a color selection mechanism 5 formed opposite the fluorescent screen 4. An electron gun 21 according to the embodiment is arranged. Further, a metal oxide insulating film having a secondary electron emission coefficient not exceeding 1 is formed on the inner wall surface of the neck portion 6 in the region where the electron gun is arranged or on the outer surface of the bead glass 23 of the electron gun 21 on the inner wall surface side of the neck portion. For example, it is also possible to form a Cr ₂ O ₃ coating 26 similar to that described above.

According to the color cathode ray tube of the present embodiment,
Bead glass 23 [23A, 23 where creepage discharge is likely to occur]
B], the secondary electron emission coefficient is 1
By forming a metal oxide insulating film, for example, a Cr ₂ O ₃ film 26 which does not exceed ₂₀₀ nm, a secondary electron emission avalanche is generated even when electrons due to unnecessary radiation enter the surface of the bead glass 23 or the inner wall surface of the neck portion. Can be suppressed, and creeping discharge can be reduced. Therefore, it is possible to obtain a highly reliable color cathode ray tube in which creeping discharge hardly occurs. The present invention can be applied to cathode ray tubes other than the color cathode ray tube.

[0035]

According to the electron gun of the present invention, the formation of a secondary electron emission avalanche can be suppressed by forming a film of a substance having a secondary electron emission coefficient not exceeding 1 on the surface of the bead glass. Can be. In addition, charge-up on the bead glass surface due to the secondary electron emission avalanche can be suppressed, and field emission of electrons from the triple junction can be suppressed. As a result, creeping discharge at the bead glass can be reduced. As a coating material on the bead glass surface,
For example, when using a metal oxide such as Cr ₂ O ₃ ,
The secondary electron emission rate does not exceed 1 for any incident energy of electrons, and the occurrence of secondary electron emission avalanches can be suppressed.

By using a metal oxide such as Cr ₂ O ₃ as a substance whose secondary electron emission coefficient does not exceed 1 for any incident energy of electrons, the composition of the substance in the beading process can be improved. It is possible to improve the film strength without any change.

The above 2 formed on the surface of the bead glass
A film made of a substance whose secondary electron emission coefficient does not exceed 1 is diffused into bead glass by heating in the beading step or / and crystallized, thereby improving the film strength.
The coating does not peel off or fall off during a conditioning or knocking step in the manufacture of a cathode ray tube or during a discharge during a normal operation.

According to the method for manufacturing an electron gun according to the present invention,
An electron gun with reduced creeping discharge on the bead glass can be manufactured, and the metal oxide film is heated using a heating process to soften the bead glass, so the adhesion of the metal oxide film to the bead glass surface is enhanced. can do.

According to the cathode ray tube of the present invention, a film made of a substance whose secondary electron emission coefficient does not exceed 1 is formed on the insulator surface where the surface discharge is likely to occur in the region where the electron gun is arranged, A highly reliable cathode ray tube in which creeping discharge is suppressed can be provided. Further, by providing the above-described electron gun, it is possible to provide a cathode ray tube in which creeping discharge particularly in bead glass is suppressed.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing one embodiment of an electron gun according to the present invention.

FIG. 2 is an enlarged view of the bead glass in FIG.

3A to 3C are manufacturing process diagrams showing one embodiment of a method for manufacturing an electron gun according to the present invention.

4A and 4B are explanatory diagrams of a metal oxide film according to the present invention.

FIG. 5 is a configuration diagram showing one embodiment of a cathode ray tube according to the present invention.

FIG. 6 is a configuration diagram showing an example of a conventional cathode ray tube.

FIG. 7 is an explanatory view showing a portion where electron field emission easily occurs due to electric field concentration in the electron gun.

[Explanation of symbols]

2 ... Glass tube, 3 ... Panel, 4 ... Phosphor screen, 5 ... Color selection mechanism, 6 ... Neck, 21 ...
Electron gun, K [K _R, K _G, K _B], G ₁ ~G ₅ ... grid, C ... electrostatic convergence means, 22 ...
Support pins, 23 [23A, 23B] ··· bead glass, 26 · · · coating with a substance whose secondary electron emission coefficient does not exceed 1, 31 · · burner, 41 · cathode ray tube

Claims (9)

[Claims] 1. An electron gun comprising a bead glass holding a plurality of electrodes, on which a film made of a substance having a secondary electron emission coefficient not exceeding 1 is formed. 2. The electron gun according to claim 1, wherein said coating is formed of a metal oxide. 3. A bead glass having a coating made of a material having a secondary electron emission coefficient not exceeding 1 on a surface thereof, wherein the coating material is diffused and / or crystallized in the bead glass by heating in a beading process. An electron gun, comprising: 4. The electron gun according to claim 3, wherein said coating is formed of a metal oxide. 5. A step of forming a metal oxide film having a secondary electron emission coefficient not exceeding 1 on a surface of the bead glass, and heating the softening of the bead glass and simultaneously strengthening the adherence of the metal oxide film. And a step of fixing a plurality of electrodes to the bead glass. 6. A cathode ray tube, wherein a coating made of a substance whose secondary electron emission coefficient does not exceed 1 is formed on an insulator surface in which creeping discharge easily occurs in a region where an electron gun is arranged. 7. The cathode ray tube according to claim 6, wherein the coating is formed of a metal oxide. 8. A cathode ray tube comprising the electron gun according to claim 1. 9. A cathode ray tube comprising the electron gun according to claim 3.