JP2000057964A - Electron gun and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a structure and a manufacturing method by which a control grid and an accelerating grid can be perforated, with the center of a transmission hole of a focused grid as a reference, by using an electric discharge machine by numerical control, and by using a hole center detecting function thereof. SOLUTION: In this electron gun, equipped with a control grid, an accelerating grid and a focusing grid 8, which is to be given with perforation of transmission holes of electrons of the control grid and the accelerating grid by electric discharge machining by numerical control, with a transmission hole 8a of the focused grid 8 perforated beforehand as a reference, in the state where a grid electrode is already assembled, the focused grid 8 is divided so that an electrode support part of an electric discharge machine can easily approach a working part at the time of perforation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a cathode ray tube electron gun, in which through holes of a control grid and an acceleration grid are machined by an electric discharge machine in order to realize a particularly accurate structure. It is.

[0002]

2. Description of the Related Art In order to realize a higher-definition electron beam with an electron gun for a cathode ray tube, it is necessary to realize a structure in which the central axes of electron transmission holes of a control grating, an acceleration grating and a focusing grating are precisely aligned. . In order to realize this high-precision structure, a technique is known in which a control grid and an acceleration grid are drilled by an electric discharge machine. In this case, the focusing grid after the drilling, the control grid before the drilling, and the acceleration grid were assembled by positioning with an insulating member (generally bead glass), and the jig was positioned with reference to the electron transmission holes of the focusing grid. Drilling is performed on the grid electrode by an electric discharge machine. FIG. 2 is a cross-sectional view for explaining an electron gun according to a conventional technique and a state in which a hole is drilled. The assembled electron gun is positioned by a jig 6 with reference to the transmission holes 3a of the focusing grating 3, and a hole is formed in the control grating 1 and the acceleration grating 2 by the discharge electrode 4 from the control grating 1 side.

[0003]

According to the above technique, the position accuracy of the electron transmission holes of the control grid 1 and the acceleration grid 2 can be accurately obtained, but the position accuracy of the transmission holes of the electrode and the focusing grid 3 is determined by the positioning jig. 6 and the position accuracy of the discharge electrode 4 are determined by the accuracy of the electric discharge machine and the jig, and sufficient accuracy cannot be secured for each electron gun. On the other hand, in recent years, electric discharge machines based on numerical control have become popular, and progress in precision and application of numerical control has been remarkable. Among such electric discharge machines, there is one in which the center coordinates are calculated by bringing the discharge electrode into contact with the inside of an existing hole, and a hole is drilled at the center. FIG. 3 is a sectional view for explaining a discharge electrode of an electric discharge machine by numerical control, an electron gun using the discharge electrode, and a drilling state thereof. There is a ceramic guide 5 that holds the discharge electrode 4 for performing drilling. The center of the hole 8a of the focusing grating 8 is detected by the discharge electrode 4
Is inserted into the hole 8a, and the discharge electrode 4 is brought into contact with the surface facing each of the X direction and the Y direction.
These coordinates are detected, and the center coordinates of the hole are calculated and obtained. With the short focusing grating 8 as shown in FIG. 3, it is easy to perform electric discharge machining from the focusing grating side.

In the prior art electron gun shown in FIG. 2, the discharge by the above-described numerical control is used to more accurately align the center of the electron transmission hole 3a of the focusing grating 3 with the transmission hole of each electrode of the control grating 1 and the acceleration grating 2. It is conceivable to use a processing machine.
The thickness of the discharge electrode 4 varies depending on the size of the hole to be processed, but is, for example, 200 μm. In order to detect the position of the transmission hole of the focusing grating 3 more accurately, the ceramic guide 5 is arranged as close as possible to the transmission hole 3a of the focusing grating 3 in order to minimize the deflection of the discharge electrode 4 when detecting the hole wall. , Detection of the hole wall must be performed. Generally, since the focusing grating 3 has a long pipe shape as shown in FIG. 2, it is difficult to insert the ceramic guide 5 to the vicinity of the transmission hole 3a. The length of the focusing grating 3 tends to be long in order to obtain a high-resolution cathode ray tube, which is becoming more and more difficult.

The present invention uses a numerically controlled electric discharge machine and utilizes a hole center detection function to perform a drilling process on a control grid and an acceleration grid with reference to the center of a transmission hole of a focusing grid. The aim is to get the way.

[0006]

Means for Solving the Problems In order to solve the above problems,
An electron gun provided with a control grid, an acceleration grid, and a focusing grid. With the grid electrodes assembled, the transmission holes of the control grid and the acceleration grid are based on the transmission holes of the focusing grid that has already been drilled. In an electron gun that drills holes by electric discharge machining by numerical control, the focusing grid is divided so that the electrode support portion of the electric discharge machine can easily approach the machining portion at the time of drilling.

[0007] At least a step of positioning and fixing the control grid, the acceleration grid and the focusing grid with an insulating member, a step of forming holes in the acceleration grid and the control grid by electric discharge machining with reference to the holes formed in the focusing grid, and a focusing grid. And a method for manufacturing an electron gun comprising a step of fixing a focusing grating for extension to the electron gun. A discharge electrode for making a hole is inserted into the hole of the focusing grid, and the coordinates of the center of the hole are detected by detecting an electric signal obtained by contacting the discharge electrode with a surface facing each of the X direction and the Y direction. The position of the discharge electrode is calculated by calculation.

[0008]

FIG. 1 is an exploded sectional view of a focusing grating according to one embodiment of the present invention. The focusing grating includes a short focusing grating 8 having a transmission hole 8a, an electrode portion having a large-diameter portion 8d at the tip, a fitting portion 8c at the other end, and a pipe portion 8b at the center. In the present invention, the focusing grid electrode is formed by connecting the short pipe-shaped portion 8 including the transmission hole 8a and the long pipe-shaped portion (8b,
c, 8d), the control grid 1 and the acceleration grid 2 are fixed by a jig (not shown) after positioning and fixing the focusing grid 8 including the transmission holes 8a with the insulating member 9 and then by numerical control. Drilling is performed on the control grid 1 and the acceleration grid 2 by electric discharge machining, and then the above-mentioned long pipe-shaped fitting portion 8c is inserted into the inner diameter of the focusing grid 8 and connected by welding or the like to form the focusing grid. To complete.

That is, until the electric discharge machining is performed, the ceramic guide of the electric discharge machine is brought close to the electron transmission hole of the focusing grid when the hole wall is detected by numerical control by using the electron gun structure shown in FIG. It becomes easier.

[0010]

According to the present invention, electric discharge machining is facilitated by dividing the focusing grid, and the positions of holes formed in the focusing grid by the discharge electrodes can be accurately detected, so that a high-definition electron beam can be obtained. And a cathode ray tube capable of realizing a high-definition image.

By dividing the focusing grating, the positions of the holes formed in the focusing grating by the discharge electrodes can be accurately detected regardless of the length of the focusing grating, and a high-definition electron beam can be realized. The degree of freedom in designing electron guns has increased.

[Brief description of the drawings]

FIG. 1 is an exploded sectional view of a focusing grating according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view illustrating an electron gun according to a conventional technique and a drilling state thereof.

FIG. 3 is a cross-sectional view illustrating a discharge electrode of an electric discharge machine by numerical control, an electron gun using the discharge electrode, and a drilling state thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control grating 2 Acceleration grating 3 Focusing grating 3a Transmission hole 4 Discharge electrode 5 Ceramic guide 6 Jig 7a Insulating member 8 Focusing grating 8a Transmission hole 8b Focusing lattice fitting part 8c Focusing lattice pipe part 8d Large diameter focusing lattice 9 Insulating member

Claims (3)

[Claims] An electron gun provided with a control grid, an acceleration grid, and a focusing grid, in a state where the grid electrodes are assembled, the control grid and the acceleration grid are determined based on the transmission holes of the focusing grid that has been drilled. In an electron gun that drills holes through the electron transmission holes by numerically controlled electric discharge machining, the electrode support of the electric discharge machine is easily brought close to the machining part at the time of drilling.
An electron gun wherein a focusing grating is divided. 2. A step of positioning and fixing at least a control grid, an acceleration grid and a focusing grid with an insulating member, and a step of forming holes in the acceleration grid and the control grid by electric discharge machining with reference to holes formed in the focusing grid. A method for manufacturing an electron gun, comprising a step of fixing an extension focusing grid to the focusing grid. 3. An electric signal obtained by inserting a discharge electrode for making a hole into a hole of a focusing grid and bringing the discharge electrode into contact with a surface opposed to each of the X and Y directions to detect their coordinates. 3. The method according to claim 2, wherein the position of the discharge electrode is determined by calculating the center coordinates of the hole.