JPH04315736A - In-line type electron gun for color picture tube - Google Patents

Abstract

PURPOSE:To enhance the focus characteristic of an in-line type electron gun for a color picture tube and the accuracy of the manufacture and inspection of the gun by arranging on a straight line three holes through which to pass electron beams, and forming both side holes of the three from arcs of more than two kinds of radii and more than one straight line. CONSTITUTION:In an electrode comprising a cup electrode 1 having a laterally- extending elliptical opening 13 common to three electron beams and a correction electrode 12, the electrode 12 comprises two side electron beam through holes 15 and a center electron-beam through hole 14. The holes 15 are each formed by an arc 15a of a radius R1, arcs 15b, 15b of a radius R2 and a straight line 15d of length L1 and there is relationship among the respective dimensions expressed by R1=R2+L1/2. Two large-aperture electrode assemblies 10 constituted are made to face each other to form a main electron lens. The main electrode lens having substantially a large aperture is thus formed and thereby spherical aberration is reduced so as to eliminate astigmatism and, since each electrode is so formed to consist only of arcs and a straight line, high accuracy can be secured in the manufacture and inspection of the lens.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line color picture tube electron gun, and more particularly to an in-line color picture tube electron gun with a small electron beam diameter and high resolution.

0002

[Prior Art] It is well known that one of the most effective ways to improve the focusing characteristics of a picture tube is to reduce the spherical aberration coefficient by increasing the diameter of the main electron lens of the electron gun. It is. However, if the diameter of the neck portion in which the electron gun is sealed is made thicker in order to achieve this larger diameter, the deflection power increases, which goes against the goal of energy conservation.

Therefore, various methods have been proposed to increase the diameter of the electron gun main lens as a measure to improve the focus characteristics of in-line color picture tubes under the constraint that the neck diameter is constant (for example, Japanese Patent Publication No. 55-179
No. 63, JP-A-61-2240).

A typical large-diameter main lens disclosed in Japanese Patent Application Laid-Open No. 61-2240 has a cup electrode 41 having a horizontally elongated aperture 43 common to three electron beams, as shown in FIG. and a correction electrode plate 42 located therein at a position set back by a predetermined distance. This correction electrode plate 42 has a vertically long ellipse 44a serving as the center electron beam passage hole 44, and a vertically long notch-shaped semi-ellipse 45a surrounding approximately half of the side electron beam passage hole 45. .

[0005] By arranging two such electrodes to face each other as a set, a vast lens space is formed, and the objective of reducing spherical aberration by substantially enlarging the main lens aperture can be achieved. Further, by optimizing the dimensions of the ellipse 44a and the semi-ellipse 45a of the correction electrode plate 42, the oval opening 43
, the astigmatism caused by the non-rotational symmetry of the ellipse 44a and the semi-ellipse 45a is eliminated. This is said to improve focus characteristics.

[0006]

[Problems to be Solved by the Invention] In increasing the diameter of the main lens of this conventional in-line type color picture tube electron gun, the shape of the hole in the correction electrode plate 42 is entirely or partially elliptical. The parts were difficult to manufacture and inspect. In particular, in a large-diameter main electron lens with a common aperture and an independent aperture as shown in Fig. 4, the focus characteristics change greatly due to changes in the shape of the correction electrode of several microns, so it is necessary to It is essential to maintain manufacturing accuracy and defect detection accuracy.

[0007]

[Means for Solving the Problems] The present invention provides an in-line type color picture tube electron gun having a main electron composed of an assembly of a cup electrode and a plate-shaped correction electrode, in which three electron beams are arranged in a straight line through which an electron beam passes. The shape of the two holes on both sides of the two holes is characterized by being composed of a plurality of circular arcs having at least two different radii and at least one straight line. Furthermore, the shape of the central hole is composed of a circle or two arcs with equal radii and two straight lines connecting them.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be explained with reference to the drawings. FIG. 1(a) is a front view of one electrode constituting the main electron lens of the first embodiment of the present invention, and FIG. 1(b) is a perspective view including a quarter cross section of this electrode. It is. This electrode is composed of a cup electrode 11 having a horizontally elongated aperture 13 common to the three electron beams, and a correction electrode 12 located within the cup electrode 11 and set back a predetermined distance. There is. The correction electrode 12 has two side electron beam passing holes 15 and one center electron beam passing hole 14.
It consists of The side electron beam passing hole 15 is shown in FIG.
), it is composed of a circular arc 15a with a radius R1, circular arcs 15b and 15c with a radius R2, and a straight line 15d with a length L1,
Further, there is a relationship of R1=R2+L1/2 between each dimension. One main electron lens is formed by opposing two large-diameter electrode assemblies 10 configured as described above.

FIG. 2 shows an equipotential diagram when the low voltage side large diameter electrode assembly 21 and the high voltage side large diameter electrode assembly 22 are opposed to each other. The electric field of the electrode facing portion 27 enters the vast lens space formed between the horizontally elongated low-voltage side elliptical aperture 23 and the high-voltage side elliptical aperture 24 that are common to the three electron beams, and Spherical aberration can be reduced by enlarging the aperture of the main electron lens. In addition, astigmatism occurs due to non-axisymmetric shapes of the low-voltage side elliptical opening 23, the high-voltage side elliptical opening 24, the low-voltage side electron beam passage hole 25a, and the high-voltage side electron beam passage hole 26a. Aberrations are eliminated by optimizing each shape, the position d1 of the low-voltage correction electrode 25, and the position d2 of the high-voltage correction electrode 26.

FIG. 3(a) is a front view of one electrode constituting the main electron lens according to the second embodiment of the present invention.
b) is a perspective view including a quarter section of this electrode. The difference between this second embodiment and the first embodiment is the shape of the center electron beam passage hole 34 of the correction electrode 32. Here, the shape of the center electron beam passage hole 34 is as follows: circular arcs 34a and 34b with radius R3, straight lines 34c and 34d
It consists of

In the second embodiment, the main electron lens formed by opposing two large-diameter electrode assemblies 30 reduces spherical aberration and eliminates astigmatism, as in the first embodiment. is realized.

In this embodiment, a large-diameter main electron lens having a common aperture and an independent aperture has been described, but it can be similarly applied to a main electron lens having only an independent aperture without a common aperture, for example. Needless to say.

[0013]

Effects of the Invention As explained above, the present invention provides a method in which the shapes of the two holes on both sides of the three holes lined up on a straight line through which the electron beam passes are a plurality of circular arcs having at least two different radii. It is composed of at least one straight line, and the shape of the central hole is composed of two circular arcs with equal radii and two straight lines connecting them, so it essentially forms a large-diameter main electron lens and eliminates spherical aberration. and eliminate astigmatism. Furthermore, since the electrode shape is composed of only circular arcs and straight lines, it has the effect of ensuring high manufacturing accuracy and inspection accuracy.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a first embodiment of the present invention, in which (a) is a front view and (b) is a perspective view.

FIG. 2 is a diagram showing equipotential lines when two electrodes shown in FIG. 1 are placed opposite each other.

FIG. 3 is a diagram showing a second embodiment of the present invention, in which (a) is a front view and (b) is a perspective view.

FIG. 4 is a diagram showing a typical large-diameter main electron lens electrode of the prior art, where (a) is a front view and (b) is a perspective view.

[Explanation of symbols]

10, 30, 40 Large diameter electrode assembly 11, 31,
41 Cup electrodes 12, 32 Correction electrodes 14, 34, 44 Center electron beam passage hole 1
5, 35, 45 Side electron beam passing hole 21
Low voltage side large diameter electrode assembly 22 High voltage side large diameter electrode assembly 23 Low voltage side oval opening 24 High voltage side oval opening 25 Low voltage side correction electrode 26 High voltage side correction electrode 27 Electrode opposing part 42 Correction electrode board

Claims (3)

[Claims] 1. An in-line color picture tube electron gun having a main electron lens formed of an assembly of a cup electrode and a plate-shaped correction electrode, including three holes arranged in a straight line through which the electron beam of the correction electrode passes. An in-line color picture tube electron gun characterized in that the shapes of two holes on both sides of the holes are composed of a plurality of circular arcs having at least two types of radii and at least one straight line. [Claim 2] Claim 1, wherein the shape of the central hole is a circle.
The described in-line color picture tube electron gun. 3. The in-line color picture tube electron gun according to claim 1, wherein the shape of the central hole is comprised of two circular arcs with equal radii and two straight lines joining them.