JP2672505B2 - Method for forming electrode for color CRT electron gun - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method of forming an electrode for an electron gun of an in-line type color cathode ray tube, and more particularly for an electron gun having a slit-shaped recess around the electron beam passage hole. The present invention relates to an electrode forming method. [Prior Art] Conventionally, as an electron gun for improving the focus around the screen of a color cathode ray tube, for example, Japanese Patent Laid-Open No. 59-157936.
Japanese Unexamined Patent Publication (KOKAI) No. 2000-205,086 is known. In this structure, a slit-like recess is provided in the peripheral portion of the electron beam passage hole of the second grid electrode, and the plate thickness in the peripheral portion of the hole is increased in the vertical deflection direction and decreased in the horizontal deflection direction. Therefore, the divergence angle of the electron beam is reduced in the vertical deflection direction. Here, the electrode plate thickness is 0.45 to 1.0 times the electron beam passage hole,
The thickness of the recess is 0.2 to 0.4 times that of the electron beam passage hole. [Problems to be Solved by the Invention] In the above-mentioned conventional technology, in a cathode ray tube having a screen size of less than 20 ″, no particular problem occurs, but 20 ″ or more, for example,
There was a problem that high precision focus characteristics could not be obtained in the case of a 33 ″ super-large tube. An object of the present invention is a method of forming an electrode for an electron gun capable of obtaining high precision focus characteristics even in a large tube. [Means for Solving the Problem] The above object is to provide three electron beam passage holes formed in a straight line, and to provide three slit-like holes surrounding each of the electron beam passage holes. A method for forming an electrode for a color CRT electron gun provided with a recess is described in (a) an approximately elliptical extra thickness having a diameter in the longitudinal direction of the slit-like recess in a portion corresponding to an electron beam passage hole of a plate-shaped material A step of forming an escape hole,
This is achieved by (b) subsequently forming a slit-shaped recess by coining, and (c) subsequently punching out the electron beam passage hole. [Operation] Before forming the slit-shaped recess by coining, a substantially elliptical relief hole having a major axis in the longitudinal direction of the slit-shaped recess is formed in advance. When forming the recessed portion, since the major diameter direction of the excess thickness relief hole is mainly contracted, the excess thickness relief hole is transformed into a shape close to a circle, and no hole chipping occurs when forming the beam passage hole, Further, for a slit-shaped recess, it is possible to make the hole area sufficiently large by making the excess relief hole an elliptical shape similar to the slit shape rather than a circular shape. Molding accuracy is greatly improved. [Example] First, an example of an electrode to which the present invention can be applied will be described with reference to FIGS. 1 and 2. In the second grid electrode 1, three electron beam passage holes 2 are formed in a straight line. A slit-shaped recess 3 is formed in the x-direction (horizontal deflection direction) around the electron beam passage hole 2. here,
Assuming that the hole diameter of the electron beam passage hole 2 is D, the electrode plate thickness T is set to (0.4 to 1.0) D and the plate thickness t of the recess 3 is set to (0.1 to 0.2) D. In this way, the plate thickness t of the recess 3 is as very small as (0.1 to 0.2) D, that is, the depth of the recess 3 is deep,
The divergence angle of the electron beam in the horizontal deflection direction (x direction) is much larger than the divergence angle in the vertical deflection direction (y direction), and highly accurate focus characteristics can be obtained. Next, the test results will be described. For example, the diameter of the neck is 29
In a mmφ cathode ray tube, the distance S between the three electron beam passage holes 2 of the second grid electrode 1 is 6.6 mm and D is 0.67 mm, and T = 0.30 mm (= 0.45 D) and t = 0.13 mm (= 0.2
D), S = 5.5 mm, D = 0.64 mm, T = 0.26 mm (= 0.4 D), t = 0.10 mm (= 0.15 D), very good results were obtained. Was given. Next, an embodiment of the present invention for forming the second grid electrode 1 having the deep recesses 3 described above will be described with reference to FIG. First, as shown in FIG. 3A, an elliptic excess hole 4 having a major axis in the longitudinal direction of the slit-shaped recess is formed in advance. Next, as shown in FIG. 3B, a slit-shaped recess 3 is formed by coining. At this time, the escape hole 4 is contracted mainly by the coining process in the longitudinal direction of the slit-shaped recess 3, that is, in the major diameter side of the escape hole 4, so that the escape hole 5 has a shape close to a circle. Next, as shown in FIG. 3C, a predetermined beam passage hole 2 is formed in the escape hole 5. In this way, since the escape hole 5 after coining has a shape close to a circle, even if the beam passage hole 2 is formed, no hole is formed. Further, the elliptical excess hole escape hole 4 provided in advance may be set within a range in which the beam passage hole 2 can be processed after coining, and the hole area can be made sufficiently larger than that of a circular hole. The machining can be reduced and the life of the coining tool can be extended. [Effect of the Invention] According to the present invention, since the excess clearance hole formed before forming the slit-shaped recess by coining is formed in an elliptical shape similar to the slit shape, When forming the slit-shaped recess, the major diameter direction of the excess thickness relief hole shrinks mainly and the excess thickness relief hole is deformed into a shape close to a circle, so no hole chipping occurs when forming the beam passage. For slit-shaped recesses, the elliptical shape relief hole similar to the slit-shaped recess can form a sufficiently large hole area rather than the circular shape. The accuracy is greatly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows an electron beam passage hole portion of a second grid electrode for explaining the present invention, (a) is an enlarged front view,
(B) is a sectional view, FIG. 2 shows a second grid electrode,
FIG. 3A is a front view, FIG. 3B is a cross-sectional view, and FIGS. 3A to 3C are cross-sectional views showing an embodiment of the present invention for molding the second grid electrode shown in FIGS. Is. 1 ... Second grid electrode, 2 ... Electron beam passage hole, 3 ... Recess, D ... Electron beam passage hole diameter, T ... Electrode plate thickness, t ... Recess plate thickness.

Claims (1)

(57) [Claims] 1. Three electron beam passage holes (2) are formed in a straight line, and three slit-shaped recesses (3) surround each of the electron beam passage holes (2). In the method for forming an electrode for a color cathode ray tube electron gun provided with, (a) an electron beam passage hole (2) of a plate-shaped material,
A step of forming a substantially elliptical margin relief hole (4) having a diameter in the longitudinal direction of the slit-shaped recess (3), and (b) a step of forming the slit-shaped recess (3) by coining. And (c) then punching out the electron beam passage hole (2), the method for forming an electrode for a color cathode ray tube electron gun.