JPH0568054B2 - - Google Patents

Description

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

[Background of the invention]

In general, the lens aperture of the electrode of an electron gun for a color picture tube greatly affects the focus characteristics, and it is desirable to make the lens aperture as large as possible in order to obtain suitable focus characteristics.

FIG. 2 is a sectional view of a main part of an example of a conventional bipotential focusing type in-line electron gun. 1A, 1B, and 1C are cathodes that emit three electron beams A, B, and C from their top surfaces, 2 is a control electrode that controls electron beams A, B, and C, and 3 is a control electrode that controls electron beams A, B, and C. accelerating electrode, 4
is a lower focusing electrode that focuses the electron beams A, B, and C, and each of the electrodes 2, 3, and 4 has an electron beam passage hole 2 for the three electron beams A, B, and C, respectively.
A, 2B, 2C, 3A, 3B, 3C and 4A,
It has 4B and 4C. Reference numeral 5 indicates an upper focusing electrode, and 6 indicates an anode.
B, 5C and 6A, 6B, 6C form three electrodes corresponding to the three electron beams A, B, C. 7 is a convergence electrode.

Therefore, the three electron beams A, B, and C, whose amounts are controlled by the signal potentials applied to the three cathodes 1A, 1B, and 1C, are placed between the accelerating electrode 3 and the lower focusing electrode 4 facing each other. After receiving a slight focusing effect from the prefocus lens formed between each hole, the light is focused on the fluorescent surface of the picture tube (not shown) by the respective electrodes formed by the upper focusing electrode 5 and the anode 6. It is focused like an image. At the same time, the electron beams A and C on both sides are deflected at an angle θ by known means of slightly eccentrically eccentricizing the electron beam passage holes 6A and 6C of the anode 6 outward with respect to the electron beam passage holes 5A and 5C of the upper focusing electrode 5. A tilt is applied to make the three electron beams A, B, and C converge at one point.

FIG. 3 is a plan view showing the upper surface of the upper focusing electrode 5. FIG. Three electron beam passing holes 5A, 5 with diameter D
B and 5C are arranged in a straight line with an interval S between them.

By the way, the size of the image point on the fluorescent surface of the picture tube, that is, the focus characteristics, affects the sharpness of the image, so it is desirable to make it as small as possible. Efforts have been made to increase the diameter of the electrode. Therefore, in order to enlarge the diameter of the electrode, it is necessary to increase the diameter D of the electron beam passage holes 5A, 5B, and 5C.

However, the electron beam passing holes 5A, 5B, and 5C of the upper focusing electrode 5 are formed by pressing a non-magnetic metal, such as a stainless steel plate, with a thickness of about 0.3 mm.
In order to improve the withstand voltage characteristics with the anode 6, it is necessary to have an aperture hole structure. Furthermore, to prevent deterioration of the rotational symmetry of the electrode electric field, the drawing depth l should be set to 1/2 of the hole diameter D.
Because of the above requirements, the diameter D is limited to a size smaller than the hole spacing S by 0.8 to 1.0 mm due to problems in parts processing. Increasing the hole spacing S also increases the convergence error at each point on the fluorescent surface during operation of the picture tube, and increases the horizontal dimension of the upper focusing electrode 5 and the anode 6 that form the electrodes. There was a problem in that when the valve neck in which the electron gun was housed was placed close to the inner wall, the withstand voltage characteristics deteriorated.

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, and 5C is desirably about 0.5% or less of the hole diameter D. Therefore, to assemble the electron gun, each electrode is held on a jig (not shown) equipped with three core metals passing through each electron beam passage hole, and heated multiform glass 8 is placed on a support. 9. In this case, the three core metals are set to be approximately 0.02 to 0.03 mm thinner than the hole diameter D since there is an error in the hole pitch S and hole diameter D of each electrode component. Therefore, the deformation of the cup-shaped body due to errors in manufacturing each electrode component and stress during crimping of the multiform glass 8 spreads to the electron beam passage holes 5A, 5B, and 5C formed by the aperture holes, and is cured. In extreme cases, the roundness error measured when removed from the tool can reach approximately 0.05 mm, that is, approximately 1.3% when the hole diameter D = 3.9 mm. As described above, the electrode of the main lens is distorted due to the decrease in roundness, which causes astigmatism in the electron beam, impairing focus characteristics.

[Purpose of the invention]

An object of the present invention is to provide a method for manufacturing an electrode for an electron gun, which increases the electrode diameter, improves the accuracy of the electrode, and improves the focus characteristics.

[Summary of the invention]

In order to achieve the above object, the present invention forms predetermined coining pilot holes in a thick plate material at locations corresponding to three inline electron beam passage holes, and then forms desired coining pilot holes on one side of the thick plate material. forming a concave surface with a depth of, then punching the outer shape of the thick plate material into an outer shape larger than a predetermined dimension, and then punching the area of the coining pilot hole to have an inner diameter larger than the coining pilot hole and smaller than the predetermined dimension. Next, both sides of the thick plate are flattened, and finally, the outer shape and three electron beam passage holes are shaved to predetermined dimensions.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG. First, as shown in FIG. 1A, predetermined coining pilot holes 11 are formed in a thick plate material 10 having a thickness of about 2 mm at locations corresponding to three electron beam passage holes. In this case, the purpose of these prepared 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 prepared holes 11 are circular holes in the illustrated embodiment, they may have other shapes than circular holes.

Next, as shown in Figure b, an elliptical concave surface 12 having substantially the same shape as a predetermined elliptical concave surface is formed on one surface of the thick plate material 10 by coining.
Thereafter, as shown in FIG. 3C, the outer shape of the thick plate material is punched out to have an outer shape larger than a predetermined size to form an oval thick plate electrode 13. Subsequently, punched holes having an inner diameter larger than the coining pilot hole 11 and smaller than a predetermined size are punched at locations corresponding to the three electron beam passage holes. In this case, the bridge portion R between the punched hole on both sides and the outer shape is deformed due to a reduction in plate thickness and twisting, and the flatness of this portion is significantly reduced. In order to correct this, both sides of the oblong plank are then leveled. This flattening is performed by a method such as a press mold while constraining the outer shape and elliptical concave surface of the thick plate. Finally, as shown in Figure d, the outer shape of the oblong thick plate and the three electron beam passage holes 14A, 14B, 14C are each shaved to predetermined dimensions to complete the electron gun electrode 15.

In this way, in order to ensure the strength of the electrode, even if a thick plate material of approximately 2 mm is used, by combining coining, punching, and shaving as in the present invention, two adjacent electron beams can be The bridge width that must be provided between the electron beam passing holes can be formed narrowly and with high precision to about 1/4 of the material thickness, for example, about 0.5 mm for a material thickness of about 2 mm. Even if the hole spacing is the same as before, the diameter of the electron beam passing hole can be expanded by making the bridge width narrower than before.
When a drawing hole structure is formed by conventional press working, the bridge width must be set to 0.8 to 1.0 mm, as described above. Furthermore, the electron beam passage hole is
It is formed on a concave surface formed by coining symmetrically with respect to both the inline direction in which the electron beam passage holes are lined up and the direction perpendicular to this inline through the central electron beam passage hole, so that there is As the electrode thickness increases as it goes, the electrode deforms less and the roundness of the electron beam passage hole is significantly improved compared to conventional electrodes with a uniform thickness, resulting in improved focus characteristics. Ru.

Furthermore, since there is no need to increase the outer diameter of the electrode when enlarging the diameter of the electron beam passage hole, there is no need to make the outer diameter of the electrode excessively close to the inner diameter of the bulb, so there is no problem of deterioration of withstand voltage characteristics.

〔Effect of the invention〕

As is clear from the above description, according to the method of manufacturing an electrode for an electron gun according to the present invention, the electrode diameter can be expanded without impairing the withstand voltage characteristics.
Further, the roundness of the electrode diameter is improved, and an electrode for an electron gun with improved focus characteristics can be obtained.

[Brief explanation of the drawing]

Figures 1a, b, c, and d are plan and cross-sectional views showing a process explanation of an embodiment of the method for manufacturing an electrode for an electron gun according to the present invention, and Figure 2 is a cross-sectional view of a main part of a conventional in-line electron gun. FIG. 3 is a plan view of the upper focusing electrode of FIG. 2. 10...Thick plate material, 11...Coining pilot hole,
12...Concave surface, 13...Oval thick plate electrode, 14
A, 14B, 14C...Electron beam passing hole, 15
... Electrode for electron gun.

Claims (1)

[Claims] 1. A step of forming predetermined coining pilot holes in a thick plate material at locations corresponding to three inline electron beam passage holes, and forming a predetermined coining hole on one side of the thick plate material. Both a straight line perpendicular to the inline and a straight line passing through the electron beam passing hole located at the center of the three electron beam passing holes and extending over an area having a depth and having a predetermined width and length; forming a symmetrical concave surface by coining; punching the thick plate material into a larger external shape according to the final electron gun electrode dimensions including the concave surface portion; a step of punching to an inner diameter larger than the prepared hole and smaller than the final dimension of the electron beam passage hole, a step of smoothing both sides of the thick plate material, and a step of making the thick plate material include the concave portion inside. A method of manufacturing an electrode for an electron gun, comprising the step of shaving the three electron beam passage holes to the outer shape of the final electron gun electrode and the final dimensions.