JPS58206030A - Inline type electrode structure - Google Patents

Abstract

PURPOSE:To obtain an electron beam with little astigmatism, even when main electron lens apertures of an inline type electron gun are made to be large- sized and extremely close each other, by making the gap parts of neighboring apertures to sink in a depressed form on the aperture cut-through and blocked surface. CONSTITUTION:In an electrode structure 2, three electron beam transmitting apertures 21R, 21G and 21B lying on three electron gun axes 20R, 20G and 20B are cut through on the blocked surface 22 while salient fringes 24 projecting into the electrodes encircle the peripheries of the apertures. The gap parts 25 of the neighboring apertures 21R, 21G and 21B are projected into the electrodes while being sunken in a depressed form by the height (d) from the blocked surface 22. The difference of the curvatures of the electron lens electric fields on a level surface facing to a phosphor surface, whereon the electron beam transmitting apertures are to be arranged and on the vertical surface facing to the phosphor surface vertical thereto, is removed while an astigmatism becomes extreme small thus enabling to obtain a beam spot having the accorded vertical-and- horizontal diameters of the beam section and no astigmatism.

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 pi-potential type, uni-potential type, or other multi-stage focusing type, and to obtain high resolution characteristics, the diameter of the electrode that makes up the main electron lens is limited. It is necessary to increase the spherical aberration of the electron lens by increasing the . 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 close to this maximum diameter can be approached.

Based on the above requirements, the applicant has proposed a method of forming electrodes for constructing a large-diameter mirror lens in Japanese Patent Application No. 56-199825 M57-0084 A3.

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 above-described electrode forming method.

That is, the electrode structure 1 has three electron gun shafts 10G at the center and on both sides separated by the distance S between the openings.

It is a closed cylindrical body in which central and bilateral electron beam transmission apertures 11G and 118.11B are bored in the closed surface 12 on 10R910B, 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 protruding into the closed cylindrical body, and a ridge 11 formed in each aperture
In order to prevent mutual influence of the child lenses, the occluding surface 12 is strengthened, and its height h is made as large as possible.

The diameters of the electron beam transmission apertures 11R, IIG, and IIB do not overlap with each other, and at least the central aperture is a completely circular hole, and the adjacent apertures 11a, 11G, and 11G.

The gap 15 of the electrode structure 1 is narrowed to approximately the thickness of the material forming the electrode structure 1, thereby increasing the diameter. In FIG. 3, this electrode structure 1 and an electrode structure 1' having the same structure are arranged facing each other on the same axis at 10R, 10G, and IOB, and the electrode structure 1
High voltage, 1! When a low voltage is applied to the pole structure 1', within the cross section including the axes 10R, 110G, and 10B of the three electron guns (
It shows the electrostatic field that forms the main electron lens in a plane (usually horizontal to the fluorescent screen of the cathode ray tube), and the equipotential lines that are the intersections of the equipotential surface of the main electron lens and this cross section are line groups 16 and 16'.
Indicated by 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 group 17.17'.

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 this electrode structure, the height h of the protruding edge 14 is usually 1/2 or less of the aperture diameter due to structural constraints, and the electrode structure 1,
1', the potential line group 1 that constitutes the electrostatic electron lens
6, l6' are common equipotential lines without going through each aperture, and the curvature of the electron lens electric field of the central apertures 11'G, 11G' is the same as that of the apertures 11R, IIR',
It is smaller than that of IIB and IIB'. Therefore, the electrostatic electron lenses formed in the central openings 11G and 11G' are weaker than the electrostatic electron lenses formed in the openings 11R, IIR', IIB, and IIB' on both row sides, and the The center electron beam diameter of the electron beam is larger than the electron beam diameters on both row sides. Furthermore, within the cross section shown in Figure 4, (
In the figure, the equipotential line groups 17, 17 formed in the center and both row side openings (only the central opening 1iF) and 11()' planes are shown)
' constitute independent electrostatic electron lenses, and are symmetrical about the axis of the electron gun, and each electron lens has approximately the same electron lens strength.

However, when compared with the 11 lens shown in FIGS. 3 and 4, the equipotential line group 16 in the horizontal plane relative to the phosphor screen in FIG.
16' electricity! ! The curvature inside the structure is smaller than the curvature inside the electrode specimen of the group of equipotential lines 17°17' in the plane perpendicular to the phosphor screen in FIG. The lens is strong, in the vertical plane each electron beam is more strongly focused than in the horizontal plane, and the electron beam diameter is smaller than in the horizontal plane in Figure 3, so this electron lens is horizontal.

Astigmatism is large due to the difference in curvature of equipotential lines in the vertical plane.

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 the central electron beam is larger than the out-of-plane electron beam. The phosphor screen is elongated horizontally, and the resolution in the horizontal and vertical directions of the phosphor screen is different.In addition, the resolution of the central electron beam is worse than that of the out-of-plane electron beam. 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.
As the occupation rate of the electron beam flux in the electron beam aperture increases, the disadvantage becomes noticeable and the resolution deteriorates.

The present invention has been made to improve the above-mentioned drawbacks.
The main electron lens aperture of an in-line electron gun has a large diameter, and even if they are very close to each other, the electron lens curvature is substantially equal in the aperture arrangement direction and in the direction perpendicular to this, resulting in small astigmatism. An object of the present invention is to provide an electron gun electrode structure that can obtain an electron beam.

The present invention will be described in detail 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', three electron guns
a, 20G, 20 Bt - shows the electrostatic field forming the main electron lens within the tr-containing cross section, and the equipotential nose, which is the intersection line between the equipotential surface of the main electron lens and this cross section, is represented by line group 26. Indicated by 26'.

Similar to the conventional electrode structure 1, the electrode structure 2 has a distance S between the openings.
II' with three electron guns! '20R, 20G.

Three electron beam transmission apertures 21R on 20B.

210.21B is a closed cylindrical body in which a hole is bored in the closed surface 22 and a cylinder side portion 23 is formed continuously to the closed surface 22, and the diameters of the openings do not overlap with each other, and at least the center opening is a completely circular hole, and adjacent openings 21f'L, 21G and 21G, 21B
The diameter of the gap 25 is increased by narrowing it to approximately the thickness of the material forming the electrode assembly 2, and the area around the opening is inside the electrode (
It is surrounded by a protruding protruding edge 24. However, adjacent hole 2
The gap portions 25 of 1R, 21G, 21G, and 21B protrude inside the electrode and are recessed by a height d from the closed surface 22.

As is clear from FIG. 6, the gap 25 is closed.
is not concave and convex with respect to the closed surface 22, so in the cross section including the three electron gun axes 20R, 20G, and 20B (horizontal plane relative to the phosphor screen), the equipotential line group 26 becomes the main electron lens forming electrostatic field. In .26', the generation of common equipotential lines that do not pass through each aperture is minimized, and an independent and almost equal electrostatic electron lens is formed for each aperture. Therefore, the strength of each electron lens in the horizontal plane is approximately equal, and the electron beam diameters of the center and both row side apertures are equal.

Furthermore, the three electron lenses in the plane shown in Fig. 6, and the electrostatic electron lenses in the cross section (vertical plane) perpendicular to the plane containing the three electron solution axes 20R, 20G, and 20B. When compared with Figure 4, which is equivalent to the plane showing the potential lines, the isoelectric line group 26.26'
The curvature of the equipotential line group 17.17' in the vertical plane shown in FIG. 4 is greater than that of the equipotential line group 16.16' in FIG.
The curvature of the electron lens electric field closely approximates the curvature of As a result, an aberration-free beam spot with the same vertical and horizontal beam cross-section diameters can be obtained on the phosphor screen.
Ru.

As described above, according to the embodiment of the present invention, the spherical aberration of the main electron lens is reduced by increasing the diameter of the electron beam transmission aperture.
In addition, since astigmatism can be reduced, the vertical and horizontal diameters of the electron beam in the horizontal and vertical planes with respect to the cathode ray tube phosphor screen are made to match, the resolution in the horizontal and vertical directions of the phosphor screen is made to be the same, and the center electron beam and the inner and outer sides are matched. Since the difference in the resolution of the electron beams can be removed, 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 recess in the gap from the closed surface of the electrode structure was simultaneously recessed to the inside of the protruding edge, or only the gap adjacent to the three electron beam transmission apertures was concavely recessed, and the inside of the electrode at the protruding edge was recessed. It goes without saying that the same effect as described above can be obtained even if the height is kept the same as the height of the parts other than the gap.

[Brief explanation of the drawing]

Figures 3 and 4 show a cross-sectional view and a plan view of the main electron lens electrode structure of an in-line integrated structure electron gun whose diameter has been increased by narrowing the portion, and Figures 3 and 4 show the pair of electrodes facing each other, respectively. Figure 5 shows the main electron lens electrostatic field in a cross section that includes the axes of the three electron guns and a cross section that is perpendicular to this cross section and includes the axis of the central electron gun when high and low voltages are applied. FIG. 6 is a perspective view of the main electron lens electrode structure of an in-line integrated structure electron gun showing an embodiment of the present invention. , respectively, show the main electron lens electrostatic field within the cross section including the axes of the three electron guns. 10R, 10G, IOB: 20L, 20G, 20B...
...Electron gun axis, IIR, IIG, IIB: 21F
L, 21G, 21B... Electron beam transmission aperture,
12゜22...Closing surface, 13.23...Pipe cylinder side, 14゜24...Protruding edge, 15.25...
...Gap, 16°16', 17, 17'
, 26, 26'...-Equipotential line group. Single S Figure 210 阜6 Close

Claims (1)

[Claims] In a closed-base cylindrical electrode structure in which three independent apertures surrounded by a protruding edge are arranged in-line, the gap between two adjacent apertures including the protruding edge is drilled from the closed base surface. An in-line electrode structure characterized by a concave depression.