JPH0578130B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a method of manufacturing a color picture tube electron gun, and particularly to a method of processing a main lens electrode of an in-line electron gun.

[Background of the invention]

Generally, the main lens aperture of an electron gun for a color picture tube has a great influence on focus characteristics, and it is desirable to make the main lens aperture as large as possible in order to obtain suitable focus characteristics.

FIG. 1 is a cross-sectional configuration diagram of essential parts showing an example of a conventional bipotential focusing type in-line electron gun. In the figure, 1A, 1B, and 1C are cathodes that each emit three electron beams from the top surface, 2 is a control electrode that controls the electron beam, 3 is an acceleration electrode that accelerates the electron beam, and 4 is a convergence electrode that focuses the electron beam. There are two lower focusing electrodes each.
A, 2B, 2C, 3A, 3B, 3C and 4A,
4B and 4C are electron beam passage holes for three electron beams. 5 is an upper focusing electrode, 6 is an anode,
The upper focusing electrode 5 and the anode 6 have three aperture holes 5A, 5B,
5C, 6A, 6B, and 6C form three main lenses that face the three electron beams.

In such an electron gun configuration, the amount of each electron beam is controlled by the signal potential applied to the three cathodes 1A, 1B, and 1C, and the three electron beams A, B, and C are connected to the accelerating electrode 3. After receiving a slight focusing effect from the prefocus lenses formed between the holes facing the lower focusing electrode 4, the main lenses formed by the upper focusing electrode 5 and the anode 6, A focusing action is applied to form an image on a fluorescent surface of a picture tube (not shown). At the same time, electron beams A, B, and C are placed on both sides of the electron beam passing hole 6 of the anode 6.
The three electron beams A, B, and C are tilted at an angle θ by known means of slightly eccentrically eccentrically outwardly the electron beams A and 6C with respect to the electron beam passing holes 5A and 5C of the upper focusing electrode 5. Converge to one point. Note that 7 is a coherence electrode.

In an electron gun configured in this way, the size of the image point on the fluorescent surface of the picture tube, that is, the focus characteristic, affects the sharpness of the image, so it is desirable to make it as small as possible. In order to improve focus characteristics, the aperture of the main lens is generally increased.

FIG. 2 is a plan view of essential parts showing the upper surface of the upper focusing electrode 5. FIG. In the figure, three electron beam passing holes 5A, 5B, and 5C each having a diameter D are arranged in a straight line with an interval S between them. In order to enlarge the main lens aperture as a means of improving focus characteristics, an electron beam passing hole 5 is provided.
It is necessary to increase the diameter D of A, 5B, and 5C. However, the electron beam passing holes 5A, 5B, and 5C of the upper focusing electrode 5 are formed by pressing a nonmagnetic metal, such as a stainless steel plate, with a thickness of about 0.3 mm.
In order to improve the withstand voltage characteristics of the anode 6 shown in Fig. 1,
It is necessary to have an aperture hole structure. Furthermore, in order to prevent deterioration of the rotational symmetry of the main lens electric field, the aperture depth l needs to be at least 1/2 of the hole diameter D, so due to problems in parts processing, the diameter D is 0.8 to 1.0 mm smaller than the hole spacing S. Constrained by small dimensions. In addition, when D is increased to improve focus characteristics, the hole spacing S becomes larger.Increasing the hole spacing S increases the convergence error at each point on the phosphor surface during picture tube operation, and the main lens If the diameter L of the upper focusing electrode 5 and anode 6 in the longitudinal direction perpendicular to the tube axis increases, and the diameter of the valve neck is constant, the withstand voltage characteristics will increase due to the closeness to the inner wall of the valve neck in which the electron gun is housed. There was a problem of deterioration.

Furthermore, in order to obtain good focus characteristics, it is said that the roundness error (major axis - minor axis) of the electron beam passing holes 5A, 5B, 5C, etc. is desirably about 0.5% or less of the hole diameter D. Therefore, to assemble the electron gun, each electrode component is held on a jig (not shown) equipped with three core metals passing through each electron beam passage hole, and the heated multiform glass 8 is attached to the support 9. It is done by crimping. In this case, the three core metals have errors in the hole pitch S and hole diameter D of each electrode component, so
The hole diameter is set to be approximately 0.02 to 0.03 mm smaller than the hole diameter D.
Therefore, the deformation of the cup-shaped body due to errors in manufacturing each electrode component and stress during pressure bonding of the multiform glass 8 spreads to the electron beam passage holes 5A, 5B, and 5C formed by the aperture holes, and is cured. The roundness error measured when removed from the tool is approximately 0.05 mm in extreme cases, or approximately 1.3% when hole diameter D = 3.9 mm.
may reach. This reduction in roundness distorts the electric field of the main lens, causing astigmatism in the electron beam, resulting in a serious drawback in that focus characteristics are impaired.

[Purpose of the invention]

Therefore, the present invention has been made in view of the above-mentioned conventional drawbacks, and its purpose is to reduce the above-mentioned side effects, enlarge the main lens aperture, and improve the assembly accuracy of an electron gun. Another object of the present invention is to provide a method for manufacturing an electron gun for a color picture tube with improved focus characteristics.

[Summary of the invention]

In order to achieve such an object, the present invention provides two sets of elongated pressure plates each having a concave surface on one surface perpendicular to the thickness direction of an oblong pressure plate having three electron beam passing holes arranged in-line in the major axis direction. In a method for manufacturing an electrode for an electron gun, in which circular thick plate electrodes are arranged at intervals with their concave surfaces facing each other to form a main lens electric field between the opposing electrodes, the thickness is approximately the same as that of the oval thick plate electrode. Predetermined base holes for coining are formed in the plate material at locations corresponding to the three electron beam passage holes, and then a concave surface of the desired depth is formed on one surface perpendicular to the thickness direction of the thick plate material. . in this case,
The formation of this concave surface involves a first coining process in which a built-up part of the material is formed around the groove edge at the same time as the preforming of the concave surface, and a subsequent coining process in which the built-up part is flattened and a predetermined concave surface is formed at the same time. It consists of two coining steps. Thereafter, the outer shape of the oval thick plate electrode is punched to a predetermined size, and then three electron beam passage holes are punched to a predetermined size.

[Embodiments of the invention]

Next, embodiments of the present invention will be described in detail using the drawings.

3a, b to 7 a, b are process diagrams for explaining one embodiment of the method for processing an electrode for an electron gun related to the method for manufacturing an electron gun for a color picture tube according to the present invention, and FIG. Figure b shows a plan view, and Figure b shows a cross-sectional view thereof. First, as shown in FIGS. 3a and 3b, predetermined coining base holes 11 are formed in a thick plate material 10 having a thickness of about 2 mm at locations corresponding to three electron beam passing holes. In this case, the purpose of these coining base holes 11 is to reduce the coining force for coining a concave surface in the next step and to form a highly accurate concave surface. Therefore, although the hole shapes of these coining base holes 11 are circular holes in the drawings, they may be of other shapes than circular holes. Next, Figure 4a,
As shown in b, an elliptical concave surface 1 having approximately the same shape as a predetermined elliptical concave surface is formed on one bottom surface of the thick plate material 10.
At the same time as the second preform coining, a first coining process is performed to form a built-up portion 13 around the groove edge of the concave surface 12. In this case, the built-up portion 13 is formed by forming a V-shaped groove 14 continuous to the built-up portion around the elliptical concave surface 12 using a method such as a press mold, as shown in the figure. This V-shaped groove 14 allows the first
The excess thickness of the thick plate material 10 generated during the coining process can be easily released, and the built-up portion 13 can be formed. Subsequently, as shown in FIGS. 5a and 5b, a second coining process is performed to flatten the built-up portion 13 and at the same time form a predetermined elliptical concave surface 22.
At this time, since there is a build-up part 13 formed in the first coining process, the build-up part 13 is pressed and dipped by a coining jig (not shown) during the second coining process, so as shown in FIG. The radius of curvature R of the cross section in the thickness direction of the thick plate around the groove edge 18 of the elliptical concave surface 22 shown in FIG. Next, the outer shape of this thick plate material 10 is punched to a predetermined size to form an oval thick plate electrode 15 as shown in FIGS. 6a and 6b.
3 as shown in Figure 7a and b.
The electron gun electrode 17 is completed by punching out the electron beam passing holes 16A, 16B, and 16C to predetermined dimensions.

〔Effect of the invention〕

As explained above, according to the method of manufacturing an electron gun for a color picture tube according to the present invention, there is no processing restriction when drawing a thin plate in the past, so that the main lens can be used without changing the dimension L in the long axis direction of the electrode. The aperture can be increased, and deformation due to heating during electrode assembly using multiform glass can be reduced, making it easy to create electron gun electrodes that can enlarge the main lens aperture and improve focus characteristics without compromising withstand voltage characteristics. An extremely excellent effect can be obtained in that it can be formed as follows.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the main part showing the structure and operating state of a conventional in-line electron gun, FIG. 2 is a plan view of the main part showing the conventional upper focusing electrode, FIGS. 3 a, b to 7 a, b is a plan view of a main part and a sectional view thereof showing a process explanation of an embodiment of a method of manufacturing an electron gun for a color picture tube according to the present invention. 10... Thick plate material, 11... Base hole for coining, 12... Concave surface, 13... Built-up portion, 14...
V-shaped groove, 15... Oval thick plate electrode, 16A, 1
6B, 16C... Electron beam passing hole, 17... Electron gun pole, 22... Elliptical concave surface.

Claims (1)

[Claims] 1. Two sets of oval thick plate electrodes each having a concave surface on one surface perpendicular to the thickness direction of an oval thick plate with three electron beam passage holes provided in the long axis direction, with the concave sides facing each other with an interval. In a method for manufacturing an electron gun for a color picture tube, which includes an electron gun arranged to form a main lens electric field between opposing electrodes, three electron beams are applied to a thick plate material having approximately the same thickness as the oval thick plate electrode. forming predetermined coining base holes 11 at locations corresponding to passage holes, and forming a concave surface of a desired shape containing the three coining base holes on one surface perpendicular to the thickness direction of the thick plate material; 12 and a built-up portion 13 of the material around the groove edge of the concave surface at the same time; a second coining step of flattening the built-up portion to form a predetermined concave surface 22; It is characterized by comprising the steps of punching the outer shape of the thick plate material to a predetermined size, and punching three electron beam passing holes to a predetermined size in the prepared hole after the second coining. A method for manufacturing an electron gun for color picture tubes.