JPH0821318B2 - Method for forming electrode for color CRT electron gun - Google Patents

Description

The present invention relates to a method for forming an electrode for an electron gun of an in-line type color cathode ray tube, and more particularly to an electrode forming method suitable for improving the focus around the screen.

[Conventional technology]

Conventionally, as an electron gun for the purpose of improving the focus around the screen of a color cathode ray tube, for example, Japanese Patent Application Laid-Open No. 59-157936
The one shown in Japanese Patent Publication is known. As shown in FIG. 3, this structure is provided with a slit-shaped recess 3 in the peripheral portion of the electron beam passage hole 2 of the second grid electrode 1, and the plate thickness of the peripheral portion of the hole 2 is changed in the vertical deflection direction ( It is thicker in the y direction) and thinner in the horizontal deflection direction (x direction), which reduces the divergence angle of the electron beam in the vertical deflection direction (y direction). In the drawing, reference numeral 4 denotes a ring-shaped projection.

In order to form the recessed portion 3, coining by pressing is generally used. For example, Japanese Examined Patent Publication No. 40-4550 can be cited.

When molding the electrode 1 shown in FIG.
As shown in the publication, for the purpose of reducing the coining working force, first, as shown in FIG. 4, a prepared hole 5 for absorbing excess thickness is provided in the corresponding portion of the electron beam passage hole 2. Next is the fifth
As shown in the drawing, the recess 3 is formed on the recess forming surface 6 in the peripheral portion of the excess hole absorbing pilot hole 5 by coining. As a result, the excess hole preparation hole 5 becomes smaller as indicated by numeral 7. After that, a portion of the prepared hole 7 for absorbing excess thickness is formed in a predetermined electron beam passage hole 2.

[Problems to be solved by the invention]

In the above-mentioned prior art, as shown in FIG. 5, the extra thickness that is inevitably produced by coining the concave portion 3 is in the directions of the flow 8 in the reduction direction of the prepared hole 5 and the flow 9 in the direction of the protrusion 4. Flow to. At this time, the flow 9 in the direction of the projection 4 is absorbed by the deformation as shown by the broken line 10, but due to this flow 9, the opening 11 of the recess 3 has an irregular roundness around the circumference. This causes a so-called sink mark. This sink mark becomes irregular in size around the concave portion 3, resulting in variation in concave shape accuracy. In particular, since a step is formed in the recess 3 near the electron beam passage hole 2 shown in FIG. 3, the shape in the vertical deflection direction (y direction) near the hole 2 is the main shape.

As described above, since the accuracy of the concave shape in the vertical deflection direction (y direction) varies, there is a problem that uniform performance cannot be obtained even in the focus of the color CRT.

An object of the present invention is to provide a method for forming an electrode for an electron gun, which prevents sink marks from occurring and has a highly uniform recess shape accuracy.

[Means for solving problems]

The above object is achieved by providing a groove portion on at least the vertical deflection direction side of the concave portion forming surface around the concave portion, and inserting a guide into the groove portion to restrain the groove portion.

[Action]

When a groove is provided in advance on at least the vertical deflection direction side corresponding to the periphery of the recess formed on the recess forming surface, a guide is fitted into the groove, and the recess is restrained by coining to form the recess. Since the flow of the excess thickness in the sink mark generation direction is limited, sink marks are not generated, and the recess shape accuracy in the vertical deflection direction (y direction) can be formed uniformly and with high accuracy.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. The second grid electrode 20 has a slit-shaped recess 22 around the electron beam passage hole 21, and an annular groove 24 and a projection 25 are provided around the recess 22 on the recess forming surface 23.

The second grid electrode 20 having such a shape is manufactured by the process shown in FIG. First, as shown in FIG. 3A, a reserve hole absorbing pilot hole 26 is provided in the corresponding portion of the electron beam passage hole 21. Next, as shown in FIG. 3B, an annular groove 24 is provided in a portion corresponding to the periphery of the recess 22. This annular groove 24
Is preferably approximately the same depth as the recess 22,
The V-shaped cross section is most effective. Next, as shown in FIG. 3C, the semi-finished product is placed on the die 27 and the guide 28, and the guide 29 is lowered from above to restrain the annular groove 24. In this state, the punch 30 is lowered to coin the recess 22. As a result, the excess hole absorbing pilot hole 26 is 31
It transforms small like. Finally, when a predetermined electron beam passage hole 21 is formed, the second grid electrode 20 shown in FIG. 1 is obtained.

In this way, the annular groove 24 is provided in advance, and this groove
When the recessed portion 22 is constrained by 24 and coined, the flow of the excess thickness in the direction of sink mark formation when forming the recessed portion can be significantly limited, and the excess thickness can be concentrated in the flow in the direction of reduction of the prepared hole. Therefore, it is possible to form the concave portion with uniform and high precision.

In the above embodiment, the groove portion 24 is provided over the entire circumference of the concave portion 22, but as described above, the sink mark does not occur near the concave portion 22, that is, in the concave opening portion on the vertical deflection direction (y direction) side. It is important that the groove 24 is partially formed on the vertical deflection direction side.

〔The invention's effect〕

According to the present invention, a groove portion is provided on at least the vertical deflection direction side corresponding to the periphery of the recess portion, a guide is fitted into the groove portion, and the groove portion is restrained to form the recess portion. Since it can be limited, the precision of the concave shape is improved, and the focus quality of the color CRT becomes highly uniform.

[Brief description of drawings]

FIG. 1 shows an electron beam passage hole portion of a second grid electrode according to an embodiment of the present invention, (a) is an enlarged front view,
2B is a sectional view, FIGS. 2A to 2C are sectional views showing an embodiment of a method for forming the second grid electrode of FIG. 1, and FIG. 3 is a conventional second grid electrode. , (A) is a front view, (b) is a sectional view, and FIG. 4 and FIG.
The method of forming the grid electrode is shown, (a) is an enlarged front view,
(B) is a sectional view. 20: second grid electrode, 21: electron beam passage hole, 22
...... Concave, 23 ...... Concave forming surface, 24 ...... Groove.

Claims (1)

[Claims] 1. A method for forming an electrode for a color cathode ray tube electron gun, comprising a slit-shaped recess (22) in the periphery of an electron beam passage hole (21), comprising: (a) a plate-shaped material and a ring-shaped projection (25). ) By coining, and (b) then a region (23) surrounded by the ring-shaped protrusions.
A step (c) of forming an excess hole absorbing hole (26) in a corresponding portion of the electron beam passage hole (21) inside, and (c) an area (23) surrounded by the ring-shaped projection.
A step of forming a groove (24) in at least the vertical deflection direction side corresponding to the periphery of the slit-shaped recess (22), and (d) then applying the plate-shaped material to the die (27) and the first On the guide (28) of the first guide (28) so that the protrusion of the first guide (28) is fitted into the groove formed by the ring-shaped protrusion (25). Guide of 1 (2
8) and a second portion having a protrusion fitted into the groove (24)
While holding the plate-shaped material with the guide (29),
An electrode for a color CRT electron gun, comprising the steps of coining the slit-shaped recess (22) with a punch (30), and (e) punching out the electron beam passage hole (21). Molding method.