JPS63168937A - In-ling electron gun structure for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain a good reproduced image by making the diameter of an electron beam passing cylinder section at the center of a pair of grid electrodes larger than the diameter of both side beam passing cylinder sections so that the voltage focusing an electron beam on a fluorescent screen becomes the same value for both side and center electron beams. CONSTITUTION:The diameter Dc of an electron beam passing cylinder section at the center is experimentally determined so that the center and both side electron beams are focused on a fluorescent screen by the same focusing voltage. That is, Dc>D, where D is the diameter of both side electron beam passing cylinder sections. Accordingly, when the focusing voltage of the same value is applied to main lenses for both side electron beams and a main lens for the center electron beams, all the three electron beams are concurrently focused on the fluorescent screen.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is an in-line electron gun for a color cathode ray tube. A tilt gun system is used in which the end cut surface is tilted away from perpendicular to the cylinder axis, and the voltage for focusing the electron beam on the fluorescent surface is the same for both sides and the central electron gun. The present invention relates to an in-line electron gun assembly for a color cathode ray tube.

[Conventional technology]

Since a shadow mask type color cathode ray tube uses three electron beams, the electron gun assembly has a focusing function that focuses each electron beam, and at the same time focuses the three electron beams at a predetermined point. (convergence) must be carried out.

Even in the case of the currently widely used in-line electron gun assembly in which three electron guns are arranged on a horizontal plane, the electron beams on both sides are concentrated at a predetermined location on the central electron beam.

Methods for concentrating these three electron beams include an offset method in which holes or cylinders for electron beams to pass on both sides of the fifth and sixth grids forming the main lens are decentered, and a cylindrical portion for electron beams to pass on both sides. There is a so-called tilt gun method in which the end cut surface is not perpendicular to the cylindrical axis but is inclined obliquely.

In the currently produced tilt gun type electron gun structure, 3
Even though it is desirable that all the electron beams are just focused when they land on the fluorescent surface, the voltage to focus the central electron beam is
100~ from the voltage for focusing the electron beams on both sides
200V high, so when installed in a television receiver, if the same voltage as the focusing voltage suitable for focusing the central electron beam is applied to the electron guns for the electron beams on both sides, the voltage will increase. There was a problem that the height was too high and the electron beams on both sides exhibited pluming. This problem can be solved by creating a structure in which focusing can be adjusted by applying different focusing voltages to the three electron beam lenses, but such a structure is not suitable for mass production.

Note that FIG. 2(a) is a front view of the in-line electron gun assembly for a color cathode ray tube, and in the figure, 1 indicates the sixth grid, and 2 indicates the fifth grid.
3 is a fourth grid, 4 is a third grid, 5 is a second grid, 6 is a first grid, and 7 is a multiform glass that insulates and supports each of the electrodes.

Figure 2(b) shows the fifth part of the conventional tilt gun type electron gun structure.
, is a sectional view of the main lens portion formed by the sixth grid, in which 1 is the sixth grid, 2A is the fifth grid cup, 2
B is the fifth grid bottom. From this figure, it is clearly seen that the tilt gun system is used, in which the end cut surfaces of the cylindrical portions for passing electron beams on both sides are not orthogonal to the cylinder axis but diagonally intersect with it in order to obtain the desired electron beam concentration effect. In this conventional tilt gun type electron gun assembly, the diameters of the electron beam passing cylindrical portions on both sides and the diameter of the central electron beam passing cylindrical portion are all made to have the same value.

[Problem that the invention seeks to solve]

In order to solve the above problems, in the present invention, due to the structure of the in-line electron gun assembly itself, when the same focusing voltage is applied to the main lenses for electron beams on both sides and the main lens for electron beams in the center, It is an object of the present invention to provide an in-line electron gun assembly for a color cathode ray tube in which all three electron beams are focused on a fluorescent surface at the same time.

Means for Solving Problem c] In order to solve the above problem, in the present invention, the diameter of the electron beam passing cylinder part at the center of the fifth grid and the sixth grid is changed so that the electron beam is emitted by the fluorescent surface. It was decided to make the diameter larger than the diameter of the cylindrical part for passing electron beams on both sides so that the voltage to be focused is the same for both sides and the center electron beam.

[Effect]

In the conventional tilt gun type electron gun structure, the end cut surfaces of the cylindrical parts for passing the electron beam on both sides are not orthogonal to the cylinder axis but diagonally intersect, and the average length of the cylindrical part is as shown in Figure 2 (b). As shown, it is shorter than the length of the central electron beam passage cylinder.

Generally, the larger the diameter of the main lens, the lower the focusing voltage for focusing at a given distance. Furthermore, if the diameters of the cylindrical portions of the fifth and sixth grids are increased, the diameter of the main lens will be increased.

In the conventional tilt gun type electron gun structure, the average length of the cylindrical parts for passing the electron beam on both sides, whose ends are cut diagonally, is short, the electric field distribution is widened, and as a result, the diameters of the electron lenses on both sides are equivalently The end cut surface is perpendicular to the cylindrical axis, and the length of the cylindrical part for passing the electron beam is larger than the diameter of the central electron lens for the electron beam.
Therefore, it is considered that the focusing voltage for both side electron beams is lower than the focusing voltage for the center electron beam. Focusing on this point, the present invention makes the diameter of the central electron beam passage cylinder part slightly larger than the diameter of the both side electron beam passage cylinder parts, thereby increasing the focusing voltage for the central electron beam and the focusing voltage for both side electron beams. I made it so that they were the same. Although the above facts are known qualitatively, there is no way to quantitatively calculate the diameter of the central electron beam passage cylinder where the focusing voltages for the central and opposite electron beams are equal, and currently there is no way to quantitatively calculate the diameter of the central electron beam passage cylinder. or by computer simulation.

〔Example〕

FIG. 1 shows a sectional view of the main lens portion formed by the fifth and sixth grids in one embodiment of the present invention, where 1 is the sixth grid, 2 is the main lens part formed by the fifth and sixth grids, and
A is the fifth grid cup, and 2B is the fifth grid bottom. In this example, the diameter Dc of the central electron beam passage cylinder was determined experimentally so that the electron beams at the center and both sides were focused on the fluorescent surface with the same focusing voltage. That is, D
c>D (where D is the diameter of the cylindrical portion for passing electron beams on both sides).

In the above-described embodiment, the main lens is formed by the fifth grid and the sixth grid, but the present invention is of course not limited to this.

〔Effect of the invention〕

As explained above, according to the present invention, three electron beams can be focused exactly on the fluorescent surface using the same focusing voltage using a tilt gun type inline electron gun structure that is easy to mass produce. A reproduced image can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the main lens portion formed by the fifth and sixth grids of the embodiment of the present invention, FIG. 2(a) is a front view of the in-line electron gun assembly, and FIG. 2(b) is a conventional FIG. 7 is a sectional view of a main lens portion formed by fifth and sixth grids of the tilt gun type electron gun assembly. 1-6th grid, 2-・5th grid, 2A-・
-Fifth grid cup, 2B--Fifth grid bottom, D-Diameter of cylindrical part for electron beam passage on both sides, ・4゛-

Claims (1)

[Claims] 1. For a tilt gun type color cathode ray tube, in which the end cut surfaces of the electron beam passing cylinder on both sides of the pair of grid electrodes forming the main lens are oblique to the cylinder axis in order to obtain an electron beam concentration effect. In the in-line electron gun structure, the diameter of the central electron beam passing cylindrical portion of the pair of grid electrodes is set to such an extent that the voltage for focusing the electron beam on the fluorescent surface has the same value for both sides and the central electron beam. An in-line electron gun assembly for a color cathode ray tube, characterized in that the diameter is larger than the diameter of the cylindrical part for beam passage on both sides.