JPH08124498A - Electron gun for cathode-ray tube - Google Patents

Abstract

PURPOSE: To prevent discharge leakage from occurring so as to improve deterioration of withstand voltage by providing folding pieces at both ends of a supporting electrode for the purpose of eliminating the burr of sharp edges at both ends of the supporting electrode holding bead glass. CONSTITUTION: The portion 92 of a supporting electrode 9 which fits around bead glass, and the support portions 91 of the electrode 9 are provided with folding pieces 94. To subject the electrode 9 to press working, the electrode 9 is punched with the direction of press working being fixed with respect to a development, and the folding pieces 94 of each support portion 91 are bent, and finally each support portion 91 is bent into a U-shape. The sharp edges of the support portions that present problems of deterioration of withstand voltage are thereby converted into the folding pieces 94, and the sharp edges that become planar portions can be eliminated. Since the fitting portion 92 of the electrode 9 is inserted into the bead glass 2, the part of each support portion 91 where the folding pieces 94 do not exist is embedded into the bead glass and so the burr of a sharp-edge press does not affect withstand voltage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube, and more particularly to improvement of withstand voltage of an electron gun for a video projector to which a high voltage is applied.

[0002]

2. Description of the Related Art A cathode ray tube for a video projector has an extremely high voltage (about 32
kV) is applied. Therefore, since a high voltage is applied to the electron gun incorporated in the cathode ray tube, discharge or leak current may occur between the electrodes forming the electron gun,
There were many cases where the characteristics of the cathode ray tube were deteriorated.
FIG. 4 illustrates the basic structure of an electron gun used in a conventional cathode ray tube for a video projector.

The electrode structure of the electron gun is as follows: G ₁ electrode 11, G ₂ electrode 12, G ₃ electrode 13, G ₄ electrode 14a divided into two parts,
14b, G ₅ electrode 15 is held by the bead glass 2,
An electron gun base 1 made of these is provided, and a shield cup 5 and a contactor 6 for guiding the high voltage of the CRT and holding the electron gun base 1 in a neck glass (not shown) of the CRT. ing.

By the way, a prescribed voltage is applied to each electrode constituting the electron gun substrate 1. In this embodiment, the G ₃ electrode 13 and the G ₅ electrode 15 are electrically connected by the connector 4 and a high voltage (about 32 kV) applied to the cathode ray tube is applied, and the G ₄ electrodes 14 a and 14 b are focused on the focus voltage (about 32 kV). 8 kV) is applied. Thus G ₄ electrode 14a which G ₃ electrode 13 to which a high voltage is applied during CRT operation, G ₅ electrode 15 and the focus voltage is applied, a discharge or leak current to deteriorate the characteristics of the generated cathode ray tube between the 14b Was there.

FIG. 5 is an enlarged view of the vicinity of the G ₅ electrode 15 and the G ₄ electrode 14b. G ₅ electrode 15 and G ₄ electrode 14b
Since a high voltage and a focus voltage are applied to each of them, the curl portions 8 forming the respective cylindrical electrodes are formed at the opposite tips.
Is provided to eliminate the protrusion of the electrode part by design. The distance between both electrodes is set to an interval (for example, 1.2 mm or more) that sufficiently satisfies the pressure resistance characteristic in vacuum.

[0006]

Problems to be Solved by the Invention As shown in FIG.
_{The 5th} electrode 15 and the G ₄ electrode 14b are provided with a curl portion 8 at the facing portion to take a measure against withstand voltage. However, the supporting electrodes 7a and 7b for holding each electrode (cylindrical electrode) by the bead glass 2 are shown in FIG. The shape was as shown in. The supporting electrode 7 shown in FIG. 6 plays a role of holding the cylindrical electrode, and has a U-shape having a recessed portion 72 into the bead glass, a supporting portion 71, and a welded portion 73 with the cylindrical electrode. .

However, the U-shaped support electrode 7 has the support portion 7
1, sharp edges of the press cut portion of the welded portion 73, press burrs, protrusions, etc. remain on the edge portion shown in FIG.
Focus electrodes 14a, 14 facing the high voltage electrode 15
The supporting electrode 7a of b is leaked to the high voltage electrode 15 due to discharge, which causes deterioration of withstand voltage.

The present invention has been made to solve the above-mentioned problem of withstand voltage deterioration, and an object of the present invention is to prevent deterioration of the characteristics of a CRT for a high-luminance, high-resolution video projector and improve its reliability.

[0009]

An electron gun for a cathode ray tube according to a first aspect of the present invention has a substantially U-shaped configuration including a plurality of electrodes constituting the electron gun, a bottom portion and two supporting portions. A plurality of support electrodes whose bottoms are fixed to each of the plurality of electrodes, and a bead glass in which a part of the support portions of the plurality of support electrodes are embedded and the plurality of electrodes are fixedly arranged at predetermined positions. At least one of the supporting portions of the plurality of supporting electrodes is provided with a flat portion piece facing the adjacent electrode between the bottom portion and the bead glass. Further, in the electron gun for a cathode ray tube according to the invention described in claim 2, in the invention described in claim 1, the flat piece is provided by bending a part of the support part.

The cathode ray tube electron gun according to a third aspect of the present invention is the electron gun for a cathode ray tube according to the first or second aspect of the present invention, wherein the plurality of electrodes constituting the electron gun are cylindrical electrodes. An electron gun for a cathode ray tube according to a fourth aspect of the present invention is the electron gun for a cathode ray tube according to any one of the first to third aspects of the present invention, in which The support portion is provided with a flat piece. Further, in the electron gun for a cathode ray tube according to the invention described in claim 5, in the invention described in any one of claims 1 to 4, the supporting electrode has a flat burr direction in which a burr direction of the press generated at the time of press molding is flat. In the above, the press molding is performed so as to be inside the support electrode.

[0011]

According to the invention described in claim 1, since the edge portion of the portion of the supporting portion of the supporting electrode facing the adjacent electrode between the bottom portion and the bead glass is reduced, the supporting electrode and the adjacent electrode are separated from each other. Prevent the occurrence of discharge leakage. Claim 2
According to the invention described in (1), since the edge portion of the supporting electrode facing the adjacent electrode is almost eliminated, the occurrence of discharge leak is largely prevented. According to the invention of claim 3,
Since the electrode forming the electron gun is a cylindrical electrode having no edge portion, the occurrence of discharge leakage between the electrode and the supporting electrode is prevented.

According to the invention described in claim 4, the support electrode has a flat portion only on the support portion of the support electrode fixed to the low voltage side electrode facing the electrode to which a high voltage is apt to occur in discharge leakage. Since the piece is provided, the conventional support electrode can be used as the support electrode fixed to the other electrode. According to the invention described in claim 5, since the burr of the press generated at the time of press molding at the end of the flat part provided on the support part of the support electrode is in a direction that does not induce the occurrence of discharge leak,
Further, it effectively prevents the occurrence of discharge leak.

[0013]

【Example】

Example 1 FIG. 1 shows an example of the shape of a supporting electrode, which is a feature of the present invention. The support electrode 9 which is a feature of the present invention is provided with a bead glass stand-in portion 92 and a bent piece 94 on the support portion 91. The welding portion 93 at the bottom of the U-shaped support electrode is the same as the conventional product. When the supporting electrode 9 is pressed, the pressing direction is punched out in a fixed direction with respect to the developed view, the bending piece 94 of the supporting portion 91 is bent, and finally both supporting portions 91 are bent into a U shape. To do.

Therefore, the sharp edge of the supporting portion, which causes a problem of deterioration in pressure resistance, becomes the bent piece 94, and the sharp edge which becomes the flat portion can be removed. Next, FIG. 2 shows a cross section of the electron gun substrate 1 when the supporting electrode 9 of the present invention is adopted as the G ₄ electrode 14b (as seen from the G ₅ electrode 15 side which is a high voltage electrode).

In FIG. 2, since the protruding portion 92 of the supporting electrode 9 is inserted into the bead glass 2, a portion of the supporting portion 91 where there is no bent piece 94 is embedded in the bead glass, so that a sharp edge is formed.・ Press burrs do not affect the pressure resistance as before. Also, the welded portion 93 at the bottom of the U-shaped support electrode has a small effect on the breakdown voltage because the electric field is shielded by the curl portion 8 of the G ₄ electrode 14b, which is the focus electrode, when viewed from the high voltage electrode side as in the conventional product. Therefore, in most of the supporting electrode 9, the bent piece 94 faces the G ₅ electrode 15, which is a high-voltage electrode, and the burrs and sharp edges on the low voltage side are eliminated, and the withstand voltage characteristic is greatly improved.

FIG. 3 shows the effect of improving the withstand voltage characteristics according to this embodiment. FIG. 3 shows the conventional product and the product of the present invention.
As shown in (a), a voltage is applied between the electrodes, the applied voltage is increased, and the voltage value when the leak current between the electrodes reaches 50 nA is compared. FIG. 3B shows the result of FIG. 3B, and it can be seen that the product of the present invention is improved by about 3.5 kV as compared with the conventional product.

Although the present invention is effective as a supporting electrode for a cylindrical electrode of an electron gun for a video projector, it goes without saying that it is effective for a supporting electrode used for supporting an electrode of an in-line type electron gun for a television or the like.

[0018]

As described above, according to the first aspect of the present invention, since the edge portion of the supporting portion of the supporting electrode facing the adjacent electrode is reduced and the occurrence of discharge leakage is prevented, the breakdown voltage is less deteriorated. It is possible to obtain an electron gun for a cathode ray tube that can be stably operated even at a high voltage. Further, according to the invention of claim 2, since the supporting portion of the supporting electrode is bent to form a flat piece and almost no edge portion facing the adjacent electrode is formed, discharge leakage is generated even at a high voltage. Therefore, it is possible to obtain an electron gun for a cathode ray tube that can always operate stably even at a high voltage with very little deterioration in breakdown voltage. According to the third aspect of the invention, since the electrode forming the electron gun is a cylindrical electrode having no edge portion, the occurrence of discharge leak between the electrode and the supporting electrode is prevented, and the breakdown voltage is less deteriorated. It is possible to obtain an electron gun for a cathode ray tube that can be stably operated even at a high voltage.

Further, according to the invention described in claim 4, since the flat piece is provided only on the supporting portion of the supporting electrode where the discharge leak is likely to occur, the other supporting electrodes are the conventional supporting electrodes. Therefore, the cost can be reduced. Further, according to the invention as set forth in claim 5, since the burr of the press generated at the time of press molding at the end of the flat piece provided on the support portion of the support electrode is in a direction that does not induce the occurrence of discharge leak, Further, it is possible to obtain an electron gun for a cathode ray tube which can effectively prevent the occurrence of discharge leak and can operate extremely stably even at a high voltage with little breakdown voltage deterioration.

[Brief description of drawings]

FIG. 1 is a perspective view showing a structure of a supporting electrode of an electron gun according to an embodiment of the present invention.

FIG. 2 is a diagram showing a mounting state of a support electrode of an electron gun in one embodiment of the present invention.

FIG. 3 is a diagram illustrating an effect of the present invention.

FIG. 4 is a diagram showing a basic structure of a conventional electron gun.

FIG. 5 is a partially enlarged view of the basic structure of a conventional electron gun.

FIG. 6 is a perspective view showing a structure of a support electrode in a conventional electron gun.

[Explanation of symbols]

1 Electron Gun Base 14 G ₄ Electrode 2 Bead Glass 15 G ₅ Electrode 3 Connector (Focus Voltage) 71 Support Electrode Support 4 Connector 72 Support Electrode Standing 5 Shield Cup 73 Support Electrode Weld 6 Contactor 9 Present Invention Support electrode of 7 Support electrode 91 Support part of support electrode of the present invention 8 Curling part 92 Curvature part of support electrode of the present invention 11 G ₁ electrode 93 Weld part of support electrode of the present invention 12 G ₂ electrode 94 Support of the present invention Electrode bending piece 13 G ₃ electrode

Claims (5)

[Claims] 1. A plurality of electrodes forming an electron gun, and a plurality of support electrodes each having a bottom portion fixed to each of the plurality of electrodes and having a substantially U-shaped shape including a bottom portion and two support portions. A bead glass in which a part of the support portions of the plurality of support electrodes are embedded, and the plurality of electrodes are fixedly arranged at predetermined positions, and at least one of the support portions of the plurality of support electrodes is provided. Is an electron gun for a cathode ray tube, characterized in that a flat piece facing the adjacent electrode is provided between the bottom portion and the bead glass. 2. The electron gun for a cathode ray tube according to claim 1, wherein the flat portion piece is provided by bending a part of the support portion. 3. The cathode ray tube electron gun according to claim 1, wherein the plurality of electrodes forming the electron gun are cylindrical electrodes. 4. The flat portion piece is provided on a support portion of a support electrode fixed to a low voltage side electrode facing the electrode to which a high voltage is applied among a plurality of electrodes forming the electron gun. An electron gun for a cathode ray tube according to any one of claims 1 to 3. 5. The support electrode is press-molded so that the direction of press burr generated during press-molding is inside the support electrode at the end of the flat piece. 4. The electron gun for a cathode ray tube according to any one of 4 to 4.