JPH021343B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the main electron lens constituent electrode of an in-line color picture tube electron gun.

The resolution of the electron gun is mainly limited by the spherical aberration of the electrostatic electron lens, which can be of the bi-potential type, uni-potential type, or other multi-stage focusing type. It is necessary to increase the diameter and reduce the spherical aberration of the electron lens. The diameter of the main electron lens electrode is limited to the inner diameter of the glass neck of the color picture tube, and in an in-line color picture tube with three electron guns arranged in a row, the diameter of the main electron lens electrode is at most 1/3 or less of the inner diameter of the glass neck. An important point in designing the structure is how to approach this maximum diameter.

Based on the above request, the applicant filed Japanese Patent Application No. 56-199825,
In Japanese Patent Application No. 57-008433, we proposed a method for forming electrodes for constructing large-diameter electrostatic electron lenses.

FIGS. 1 and 2 are a cross-sectional view and a plan view showing an example of a main electron lens electrode structure of an in-line integrated structure electron gun obtained by the electrode forming method described above.

That is, the electrode structure 1 has three electron gun shafts 10G at the center and both outer sides separated by the distance S between the openings.
It is a closed cylindrical body in which center and both outer electron beam transmission apertures 11G, 11R, 11B are bored in the closed surface 12 on the closed surfaces 10R and 10B, and a cylinder side portion 13 is formed continuously to the closed surface 12. The periphery of the electron beam aperture is surrounded by a protruding edge 14 that protrudes into the inside of the closed cylindrical body, which prevents mutual influence of the electrostatic electron lenses formed in each of the apertures and strengthens the closed surface 12. , the height h thereof is made as large as possible. Electron beam transmission apertures 11R, 11G, 11B
The diameters D of the holes do not overlap with each other, and at least the central opening is a completely circular hole, and the adjacent openings 11R, 11G, and 11
The gap 15 between G and 11B is made large in diameter by narrowing it to approximately the thickness of the material forming the electrode structure 1. Figure 3 shows this electrode assembly 1 and an electrode assembly 1' having the same structure on the same axis 10R, 10G, 1.
0B, and when a high voltage is applied to the electrode assembly 1 and a low voltage is applied to the electrode assembly 1', within the cross section including the axes 10R, 10G, and 10B of the three electron guns (usually with respect to the fluorescent screen of the cathode ray tube). The electrostatic field forming the main electron lens in the horizontal plane (horizontal plane) is shown, and the equipotential lines that are the intersections of the equipotential surface of the main electron lens and this cross section are shown by line groups 16 and 16'. Figure 4 shows the electrostatic field of the main electron lens in a cross section that is perpendicular to the above cross section and includes the axis of the central electron gun (usually a plane perpendicular to the phosphor screen), and shows the equipotential surface of the main electron lens and this cross section. Equipotential lines, which are the intersection lines of , are shown by line groups 17 and 17'.

In the cross section shown in FIG. 3, as is clear from the figure, independent electrostatic electron lenses are formed in each electron beam transmission aperture on the opposite side of the electrode structures 1 and 1'. However, in the present electrode assembly, the height h of the protruding edge 14 is usually 1/2 or less of the aperture diameter D due to structural constraints, and an electrostatic electron lens is formed inside the electrode assembly 1, 1'. Potential line group 16,1
6' is a common equipotential line without passing through each aperture, and the curvature of the electron lens electric field of the central aperture 11G, 11G' is the same as that of the outer aperture 11R, 11R',
It is smaller than that of 11B and 11B'.
Therefore, the electrostatic electron lenses formed in the central apertures 11G, 11G' are formed in the both outer apertures 11R, 11R', 1
It is weaker than the electrostatic electron lens formed at 1B and 11B', and the center electron beam diameter of the electron beam within this cross section (horizontal plane) is larger than the diameters of both outer electron beams. Furthermore, in the cross section shown in FIG. 4 (only the planes of the central opening 11G and 11G' are shown in the figure), equipotential line groups 17 and 1 formed at the center and both outer openings are shown.
Each of the electron lenses 7' constitutes an independent electrostatic electron lens, which is symmetrical about the axis of the electron gun, and each electron lens has approximately the same electron lens strength.

However, when comparing the electrostatic electron lenses shown in FIG. 3 and FIG. Group of equipotential lines in the vertical plane 1
7, 17', the electron lens is stronger in the vertical plane of FIG. 4 than in the horizontal plane of FIG. 3, and each electron beam is more strongly focused in the vertical plane than in the horizontal plane; The diameter of the electron beam is smaller than that of the horizontal plane in FIG. 3, and therefore, this electron lens has large astigmatism due to the difference in the curvature of the equipotential lines in the horizontal and vertical planes.

Due to the electrostatic electron lens described above, each electron beam passing through the aperture becomes a horizontally elongated electron beam cross section in the direction of the three apertures (on the horizontal axis), and furthermore, the central electron beam is smaller than both outer electron beams. It is horizontally long, and the resolution in the horizontal and vertical directions of the phosphor screen is different.In addition, the resolution of the central electron gun is worse than that of both outer electron guns. In this way, an electron beam cross section with large aberrations is obtained on the fluorescent screen of the cathode ray tube, and therefore the cathode emission current resulting in a high brightness image is large.
This becomes particularly noticeable when the occupancy of the electron beam flux in the electron beam aperture increases, and the disadvantage of degrading resolution is observed.

The present invention was made in order to improve the above-mentioned drawbacks, and the main electron lens apertures of the in-line electron gun are made large in diameter, and even if they are very close to each other, the apertures are arranged in the aperture direction and in the direction perpendicular to this. It is an object of the present invention to provide an electron gun electrode structure in which electron lens curvatures are made substantially equal and an electron beam with small astigmatism can be obtained.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 5 is a perspective view of the main electron lens electrode structure 2 of an in-line integrated structure electron gun according to an embodiment of the present invention, and FIG. 6 shows an electrode structure 2' having the same structure as this electrode structure 2. 20R, 20G on the same axis,
20B, and when a high voltage is applied to the electrode structure 2 and a low voltage is applied to the electrode structure 2', a main electron lens is formed in a cross section including the axes 20R, 20G, and 20B of the three electron guns. Equipotential lines, which are lines of intersection between the equipotential surface of the main electron lens and this cross section, are shown by line groups 26 and 26'.

Similar to the conventional electrode structure 1, the electrode structure 2 has three electron gun shafts 20R, 20 with a distance S between the openings.
Three electron beam transmission apertures 2 on G, 20B
1R, 21G, 21B are drilled in the closed surface 22,
It is a closed cylindrical body in which a cylindrical side part 23 is formed continuously to a closed surface 22, the diameters D of the openings do not overlap with each other, and at least the central opening is completely circular, and the adjacent openings 21
The gap portions 25 of R, 21G and 21G, 21B are made large in diameter by narrowing to approximately the thickness of the material forming the electrode structure 2, and the periphery of the opening is surrounded by a protruding edge 24 protruding into the electrode. There is. However, the gap 25 between the adjacent openings 21R, 21G and 21G, 21B
protrudes inside the electrode and is recessed in a concave shape by a height d from the closed surface 22.

As is clear from FIG. 6, since the gap 25 is concave with respect to the closed surface 22, the main electron lens The equipotential line groups 26 and 26', which form the electrostatic field, are created by minimizing the occurrence of common equipotential lines that do not pass through each aperture, and forming an independent and almost equal electrostatic electron lens for each aperture. is formed. Therefore, the strength of each electron lens in the horizontal plane is approximately equal, and the electron beam diameters of the central and both outer apertures are equal. Furthermore, the sixth
Equivalent to the plane showing the equipotential lines of the three electron lenses in the plane shown in the figure and the electrostatic electron lens in the cross section (vertical plane) perpendicular to the plane containing the axes 20R, 20G, and 20B of the three electron guns. When compared with Fig. 4, isoelectric line group 2
The curvature of 6,26' is the equipotential line group 1 in Figure 3.
6 and 16', the curvature of the equipotential lines 17 and 17' in the vertical plane shown in FIG. There is no difference in the curvature of the electron lens electric field in a plane perpendicular to the phosphor screen, and astigmatism becomes extremely small, resulting in a beam spot on the phosphor screen with no aberrations in which the longitudinal and lateral diameters of the beam cross section match.

As described above, according to the embodiment of the present invention, the spherical aberration of the main electron lens can be reduced and the astigmatism can be reduced by increasing the diameter of the electron beam transmission aperture.
By matching the vertical and horizontal diameters of the electron beam in the horizontal and vertical planes with respect to the cathode ray tube fluorescent screen, the resolution in the horizontal and vertical directions of the fluorescent screen can be matched, and the difference in resolution between the central electron beam and both outer electron beams can be eliminated. Therefore, the resolution of each electron beam is uniformly improved. Furthermore, since the reduction of spherical aberration by increasing the diameter of the electron lens can be achieved by reducing astigmatism, the cathode emission current resulting in a high-brightness image is large, and the electron beam flux at the electron beam transmission aperture is reduced relative to the electron lens. Even if the occupation rate increases, the resolution will not deteriorate.

In the above embodiment, the concave depression in the gap from the closed surface of the electrode structure was simultaneously depressed to the inside of the protruding edge. It goes without saying that the same effect as described above can be obtained even if the internal height is kept the same as the height other than the gap.

[Brief explanation of drawings]

Figures 1 and 2 were filed by the applicant in Japanese Patent Application No. 56-199825.
The cross-sectional view and plan view of the main electron lens electrode structure of the in-line integrated structure electron gun, which has a larger diameter by narrowing the gap between two adjacent openings described in Japanese Patent Application No. 57-008433, are shown in Section 1. Figures 3 and 4 show a cross section including the axes of the three electron guns, and the axis of the central electron gun perpendicular to this cross section, when the pair of electrodes are opposed to each other and high and low voltages are applied, respectively. FIG. 5 is a perspective view of the main electron lens electrode assembly of an in-line integrated structure electron gun showing an embodiment of the present invention, and FIG. The main electron lens electrostatic fields in a cross section including the axes of the three electron guns are shown when the electrodes face each other and high and low voltages are applied, respectively. 10R, 10G, 10B; 20R, 20G, 2
0B...electron gun axis, 11R, 11G, 11B;
21R, 21G, 21B... Electron beam transmission aperture, 12, 22... Closed surface, 13, 23... Cylinder side part, 14, 24... Projected edge, 15, 25... Gap part, 16, 16 ', 17, 17', 26, 26'...
...Equipotential line group.

Claims (1)

[Claims] 1 In a closed cylindrical electrode structure in which three independent apertures surrounded by a protruding edge are arranged in-line on a closed surface, the gap between two adjacent apertures including the protruding edge is locally opened. An in-line electrode structure characterized by having a concave depression from the hole drilling and closing surface.