JPH031429A - Electron gun for color television picture tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a color picture tube electronic device comprising two electrodes in which a focusing lens for focusing a plurality of electron beams is arranged facing each other with an appropriate distance between them. The present invention relates to guns, and specifically relates to improving the withstand voltage characteristics of electron guns.

[Prior Art] The withstand voltage characteristics of an electron gun are determined by the ease with which discharge occurs between the two electrodes that make up the focusing lens.
The smaller the potential difference between the two electrodes, the better the voltage resistance characteristics will be, and conversely, the larger the potential difference, the worse the voltage resistance characteristics.

Generally, the withstand voltage characteristics of an electron gun largely depend on the structure and arrangement of the two electrodes that constitute the focusing lens. Furthermore, it is well known that reducing the angle of the electrodes and widening the spacing between the electrodes are effective in improving the withstand voltage characteristics.

The electron gun used in color picture tubes holds the electrodes with glass called bead glass and is enclosed in a glass tube with a fixed inner diameter called neck tube, so the trajectory of the electron beam is accumulated on the glass surface. Affected by static electricity, as a result the convergence quality of the electron beam on the screen is adversely affected.

Therefore, widening the spacing between the electrodes is not preferable because, although it improves the electric resistance performance, it deteriorates the convergence quality.

Furthermore, reducing the corners of the electrodes is effective in suppressing discharge because concentration of charges can be avoided.

FIG. 5 is a front view of an electrode constituting a main focusing lens in a conventional color picture tube electron gun disclosed in, for example, Japanese Unexamined Patent Publication No. 57-103246, and FIG. 6 is a cross-sectional view of FIG. 5. In the same figure, reference numerals (13) and (13) are two electrodes placed opposite each other with an appropriate interval, and these electrodes (13) and (13) each have a peripheral rim (2) recessed in opposite directions. ), (2) are formed.

(14), (14) are the passage holes for the three R, G, and B electron beams (12), (12), and these electron beam passage holes (14), (14) are formed. surface (1), (1) is the above-mentioned peripheral rim (2),
(2) It is located in a more retreated location.

In the color picture tube electron gun having the above configuration, the peripheral rim (13) closest to the opposing electrodes (13),
2) Discharge is likely to occur at the tip face portions (3) and (3) of (2), and the shape of this portion is an important point in determining the quality of withstand voltage characteristics.

For example, as shown in FIG. 7, if the corner (4) of the distal end surface (3) of the peripheral rim (2) is formed into an edge, the equipotential line (5) will form with respect to the electrode (13). The edge part (4
), the charges (6) tend to concentrate on the edge portion (4), which tends to cause discharge.

In the conventional electron gun for color picture tube disclosed in Japanese Unexamined Patent Publication No. 57-103246, as shown in FIG.
By forming the corner (4) of the distal end surface (3) of the peripheral rim (2) into a curved surface, the charge (6) is prevented from concentrating on the corner (4) and discharge is suppressed. There is.

[Problem B to be solved by the invention] Conventional electron guns for color picture tubes were constructed as described above, so when used with a high anode voltage, the potential difference between the two electrodes that make up the focusing lens becomes large. Therefore, there was a problem that the withstand voltage characteristics deteriorated.

This invention was made to solve the above-mentioned problems, and its purpose is to provide an electron gun for color picture tubes that can improve the withstand voltage characteristics without increasing the distance between the two electrodes. shall be.

[Means for Solving the Problems] In the electron gun for color picture tubes according to the present invention, the entire circumference or part of the tip of the peripheral rim of at least one of the two electrodes constituting the focusing lens is fixed. It is characterized by having a cross section with a curvature of a circular arc.

[Operation] According to the present invention, by configuring the tip of the peripheral rim of the electrode constituting the focusing lens into a curved surface with an arc cross section, the flat portion of the peripheral rim does not exist at all or is kept to a minimum. In addition, the curved surface of the tip of the rim is formed into an arc with a constant curvature, making it difficult for electric charges to concentrate. Withstand voltage characteristics can be improved.

[Embodiment of the Invention] Hereinafter, an embodiment of the present invention will be described based on the drawings.

FIG. 1 is a cross-sectional view of an electrode constituting a main focusing lens in an electron gun for a color picture tube according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view taken along the If-If line in FIG.
In the same figure, (1) (2) (12) to (14)
Since these are the same as the conventional examples shown in FIGS. 5 and 6, the same reference numerals are given and detailed explanation thereof will be omitted.

In Figures 1 and 2, (10) is the peripheral rim (2
), the thick-walled cylinder (7) is the tip of its peripheral rim (2), and has a curved surface with a circular arc cross section having a constant curvature (R).

According to the color picture tube electron gun having the above configuration, equipotential lines (
5) is shown in FIG.
3) is uniformly distributed along the arc-shaped curved surface and does not locally approach the electrode (13). Therefore, the charge (
6) is dispersed over a wide range, electric discharge is less likely to occur, and therefore the withstand voltage characteristics are improved.

In the above embodiment, the peripheral rim (2) is a thick-walled cylinder (1).
0), but as shown in Figure 4, the peripheral rim (2) is comprised of a thin tube (11), and the tip (7) of the peripheral rim (2) is curled. Even if the surface is formed into an arcuate curved surface by processing, the same effect as in the above embodiment can be obtained.

Further, in the above embodiments, the electrodes forming the main focusing lens have been described, but the same effects as in the above embodiments can be obtained even if the present invention is applied to the electrodes forming the front focusing lens.

[Effects of the Invention] As described above, according to the present invention, there is no need to widen the distance between the two electrodes constituting the focusing lens, and the electric charge can be dispersed and discharge can be carried out while keeping the distance to maintain good convergence quality. can be suppressed and the withstand voltage characteristics can be improved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an electrode in an electron gun for a color picture tube according to an embodiment of the present invention, FIG. 2 is a cross-sectional view taken along the line ■-■ in FIG. 1, and FIG. 3 is for explaining the operation. 4 is a cross-sectional view of an electrode according to another embodiment of the present invention. FIGS. 5 and 6 are a front view and a cross-sectional view of an electrode in a conventional color picture tube electron gun, and FIG. 7 and 8 are schematic cross-sectional views for explaining the operation of the conventional example, respectively. (1)...Surface where openings are formed, (2)...Peripheral rim, (3)...Tip of rim, (12)...Electron beam, (13)... electrode. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A peripheral rim is formed on at least one of the two electrodes that are arranged opposite to each other with a predetermined interval so as to form a focusing lens that focuses an electron beam, and a portion is set back from the peripheral rim. In an electron gun for a color picture tube, in which a plurality of apertures equal to the number of electron beams are arranged in a part, the entire circumference or a part of the tip of the peripheral rim has a cross section with a constant curvature that is an arc. An electron gun for a color picture tube characterized by having a curved surface.