JPH0744014B2 - Electron gun electrode - Google Patents

Description

TECHNICAL FIELD The present invention relates to an electron gun electrode for an in-line type color cathode ray tube.

[Conventional technology]

The resolution of the electron gun for a cathode ray tube is limited mainly by the spherical aberration of the electron lens, and in order to obtain high resolution characteristics, it is necessary to increase the diameter of the electrode forming the main electron lens and reduce the spherical aberration of the electron lens. In an in-line type electron gun in which three apertures through which the electron beam passes are arranged in a straight line, if the diameter of the main electron lens is simply increased, the electron gun is sealed as the eccentric distance, which is the distance between the apertures, increases. It is necessary to increase the diameter of the neck of the cathode ray tube.

Generally, an increase in the eccentricity distance deteriorates the convergence property of concentrating three electron beams at one point on the entire fluorescent screen, and an increase in the neck diameter causes an increase in deflection power when a cathode ray tube is used. Absent.

Therefore, there has been conventionally proposed a method of increasing the diameter of the electrode constituting the main electron lens without changing the eccentric distance S and the neck diameter of the in-line type electron gun (JP-A-60-9036).

FIG. 4 is a perspective view of a notched part of this conventional example, FIG. 5 is its plan view, FIG. 6 is a sectional view of FIG. 5A-A, and FIG.
FIG. 3 is a side sectional view of an electron gun in which the electrodes shown in the drawing are opposed to each other as a focusing electrode G3 electrode 18 and an anode electrode G4 electrode 19 to form a bi-potential focus type main electron lens. .

As shown in FIG. 4, this conventional electron gun electrode has a cylindrical shape whose side surface is covered by the outer side wall 13, and the upper surface is the main opening surface 3 which is opened as shown in FIG. The lowest part of the bottom surface is the first closed surface 12, and the center line A-A in the longitudinal direction of the first closed surface 12 and the center line A-A that passes through substantially the center of the first closed surface 12 A line Y- on the first obstruction surface 12 which goes orthogonally
It is larger than the distance S between the center points around the three points a, b, c where Y and the line Y-Y and the parallel lines X-X and Z-Z parallel to the line Y-Y are separated from each other by the distance S. A portion surrounded by the diameter D _O has a shape of being squeezed up by a predetermined height h _O , and a surface parallel to the first closing surface 12 is the second closing surface 11. The first closed surface 12 and the second closed surface 11 are connected by the side walls 11WR, 11WG, 11WB of the three-circle overlapping portion. Three-circle overlapping part surrounded by the first closing surface 12
11WR, 11WG, and 11WB are the first opening faces partitioned by the constricted part 17.
11R, 11G, 11B, from the first opening surface 11R, 11G, 11B to the second
Up to the closed surface 11 is defined as openings R ₁ , G ₁ , and B ₁ . Furthermore, three points a, b, and c on the second closed surface 11 are centered, and three points surrounded by a diameter D ₁ smaller than the distance S between the center points are predetermined heights h ₁
Three second opening faces 16R, 16G, 16B are formed by cutting out three end faces while leaving the inner cylindrical portion 16W in a squeezed shape. An electrode support 14 and a brim 15 are provided around the main opening surface 3 for attachment and reinforcement.

The electrode of this structure is a focusing electrode as shown in FIG.
The spherical aberration of the electron lens formed by facing the G3 electrode 18 and the G4 electrode 19 as the anode electrode is extremely small, and the lens in the horizontal direction, which is the aperture arrangement direction of the central and outer electron lenses, and the vertical direction perpendicular to this. The action is uniform, and the resolution characteristics are remarkably improved up to a high current region where the occupied electron beam diameter in the electron lens becomes large.

[Problems to be solved by the invention]

The conventional electron gun electrode described above has the first opening surface 11R, 11G, 11
B, and increasing the opening R _1, G _1, B ₁ opening diameter D ₀ to form a according to increase the mutual superposition of the opening R _1, G _1, B _1, the central and two outer electron lens Spherical aberration is reduced, but the constriction 17 between the central opening G ₁ and the outer openings R ₁ and B _{1 is} 17
The constriction amount is small, and the lens action in the horizontal direction becomes weaker in the electron lens of the central aperture G ₁ than in the vertical direction, and astigmatism becomes noticeable, so the focusing voltage that gives the best focus state in the horizontal direction is vertical. The focusing voltage that gives the best focus condition in the direction becomes low, and the two do not match, and the electron beam spot on the fluorescent screen imaged by the central electron lens becomes remarkably horizontal. Therefore, in this type of electron lens, The resolution of the electron lens is inferior to that of both outer electron lenses.

[Means for solving problems]

The electron gun electrode of the present invention has a cylindrical shape and an upper surface which is a main opening surface intersecting at right angles to the central axis, and a lower surface on which a first closed surface parallel to the main opening surface is formed. A predetermined height is raised so that a portion surrounded by three circles each having a diameter at each of three equally spaced points on a straight line passing through substantially the center of the closed surface as a center is larger than the spacing is the first opening surface. , The squeezed end surface is a second closing surface parallel to the first closing surface,
Of the three points on the second closed surface, a circle whose center is the outer two points is smaller than the interval and a straight line connecting the three points around the center point of the three points is a minor axis. The three points surrounded by an ellipse that does not intersect with the circle centered on the two outer points are squeezed by a predetermined height to form a cylindrical shape, and the end faces thereof are cut off to make the three parallel to the first closed surface.
They are integrally formed to form one opening surface.

Therefore, when the electron gun electrode of the present invention is applied to an electron gun, the deterioration of the lens action occurring in the central portion of the first opening is caused by the cylindrical shape having the elliptical opening cross section formed on the second closed surface. It is corrected by the part.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of an electron gun electrode of the present invention,
2 is a perspective view of a notched part of FIG. 1, and FIG. 3 is a sectional view taken along line AA of FIG. Those having the same symbols as in the conventional example represent the same members.

In this embodiment, the circular opening surfaces 16R, 16 are arranged on the center line of the horizontal section of the cylindrical electron gun electrode having the three central points a, b, c in the conventional example.
Of the three inner cylindrical portions having G and 16B, the portion having the central opening surface 16G passes through the center point b and has a major axis D ₂ in a straight line direction orthogonal to the centerline and a minor axis in the centerline direction. It has an inner cylindrical portion 26W having an elliptical opening surface 26G. here,
The height h _O from the lower surface of the first closed surface 12 to the lower surface of the second closed surface 11 is 0.2 to 0.6 of the diameter D _O of the circle that encloses the second closed surface around the center points a, b, c. The height of the three inner cylindrical portions is set to be the same height h ₁ from the lower surface of the second closing surface 11.

As in the case of FIG. 7, the two electron gun electrodes are opposed to each other as the focusing electrode 18 and the anode electrode 19 to form a bi-potential focus type electron lens. An electron lens having a large diameter and a small spherical aberration is formed in each of the openings R ₁ , G ₁ , and B ₁ of _{No. 1} . However, since the communication with the portion of the opening R _1, G _1, the central opening G ₁ and both outer openings R ₁ in B _1, B ₁ between the constricted portion 17, central aperture electron lens in G ₁ Causes astigmatism in which the lens action in the horizontal direction, which is the aperture arrangement direction, becomes weaker than in the vertical direction, but since the central aperture 26G of the internal tubular portion 26W is an elliptical shape having a long axis in the vertical direction, The electron lens formed on the second opening surface 26G from the connection portion with the second closing surface 11 has a stronger lens action in the horizontal direction than in the vertical direction.
By canceling the lens action of G ₁ , it is possible to obtain a homogenous electron lens without astigmatism. On the other hand, the electron lenses of both outer openings R ₁ and B ₁ communicate with the central opening G ₁ at the constricted portion 17 and are not independent, but because of communication on only one side, the central opening G ₁ Large astigmatism does not occur, and the residual astigmatism is sufficiently compensated by the lens action of the inner cylindrical portion 16W formed in the cylindrical shape on the second blocking surface 11.

The longitudinal degree of the elliptical second opening surface 26G of the inner tubular portion 26W formed in the center is the superimposition degree of the first opening portions R ₁ , G ₁ , B ₁ formed in the first closing surface 12. You can decide according to. That is, the major axis of the ellipse of the second opening surface 26G may be increased as the diameter of the first opening R ₁ , G ₁ , B ₁ increases and the degree of superposition increases. The minor diameter of the elliptical second opening surface 26G does not necessarily have to match the opening diameter D ₁ of the outer second opening surfaces 16R and 16B as described above, and is optimal for the central and outer electron lenses. It may be determined in consideration of the major axis so that the focusing voltages match.

In the above description, the case where the main electron lens is of the bi-potential focus type has been described, but it goes without saying that the present invention is not limited to this and can be applied to a multi-stage focusing electron lens or the like.

〔The invention's effect〕

As described above, according to the present invention, the central portion of the opening from the first opening surface to the second closing surface, which is partially divided into three parts, is different from both outer portions in both outer portions. Although the lens action in the direction of connecting to is weak, by providing an internal cylindrical portion having an elliptical cross section directly above the central portion of the opening,
There is an effect that it is possible to realize an electron gun electrode that constitutes an electron lens in which the lens action is corrected and has no astigmatism.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of an electron gun electrode of the present invention,
2 is a perspective view of a notched part of FIG. 1, and FIG. 3 is FIG. 1A.
-A sectional view, FIGS. 4, 5 and 6 are perspective views of a conventional example with a notched portion of each, a plan view, A-A sectional view, and FIG. 7 show an electron gun electrode assembled in an electron gun. FIG. 11 …… Second closing surface, 12 …… First closing surface, 13 …… External side wall, 14 …… Electrode supporter, 15 …… Brim edge, 16R, 26G, 16B
...... Second opening surface, 16W, 26W ...... Inner tubular part, 17 ...... Constricted part, 11WR, 11WG, 11WB ...... Side of three circle overlapping part, 11R, 11G,
11B: first opening surface, R ₁ , G ₁ , B ₁ ... first opening portion.

Claims (1)

[Claims] 1. An electron gun electrode for a cylindrical cathode ray tube, comprising:
The upper surface is a main opening surface intersecting at right angles to the central axis, and the lower surface has a first closed surface parallel to the main opening surface.
A predetermined height so that a portion surrounded by three circles having a diameter at each of three equally spaced points on a straight line passing through substantially the center of the closed surface of the above is larger than the spacing as the first opening surface A raised and squeezed end surface is used as a second closing surface parallel to the first closing surface, and a circle having a diameter centering on two outer points of the three points on the second closing surface is smaller than the interval. The three points surrounded by an ellipse that does not intersect with a circle centered on the outer two points having a minor axis in the direction of the straight line connecting the three points around the center of the three points are raised to a predetermined height. An electron gun electrode integrally formed into a cylindrical shape, each end surface of which is cut off to form three second opening surfaces parallel to the first closed surface.