JPH0246631A - Electron gun structure for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To eliminate the halo leaning in the lateral direction of both side electron beams by providing three electron beam passage holes at the surface of the second grid electrode opposite to the third electrode, and making the centers of circular projections around the both electron beam passage holes eccentric to the outer side to the centers of the electron beam passage holes respectively. CONSTITUTION:In an in-line type color cathode-ray tube which releases, accelerates, focuses, and concentrates three electron beams lining up on a plane, circular projections 21a and 23c are formed eccentric to the outer side to electron beam passage holes 12a and 12c of the second grid electrode 12. As a result, the electron beam orbits B are bent a little to the outer side, and they pass through a main electron lens without leaning to the inner side. Consequently, a halo leaning can be almost all eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Fields] The present invention provides an in-line collar with improved focusing uniformity by improving the prefocus lens electrode structure so as to reduce the halo deviation phenomenon of the electron beam spot. The present invention relates to an electron gun assembly for a cathode ray tube.

[Prior art] In color cathode ray tubes, there are some problems with focusing the electron beam.For example, the core is well focused, but a halo appears around it, or the conditions for optimal focusing and concentration are different. There are various problems.

Therefore, various countermeasures for the above-mentioned problems have been proposed for a long time. For example, the first to
In an electron gun equipped with four grid electrodes, among the electron lenses formed between the second grid electrode and the third grid electrode, and between the third grid electrode and the fourth grid electrode, electron lenses related to electron beams on both sides Automatic static focusing of three electron beams by eccentrically
JP-A-52-3936 discloses that even if the focusing state is adjusted by changing the voltage applied to the third grid electrode, that is, the focusing voltage, the focusing state is not affected.
It is disclosed in Publication No. 6. In addition, in practical use, the first grid electrode, which is closer to the cathode, becomes hotter than the second grid electrode, and in order to prevent the difference in thermal expansion from adversely affecting the electron beam trajectory on both sides, the third grid electrode, which is a focusing electrode, is Of the three electron beam holes provided on the side of the electrode facing the second grid electrode, which is the accelerating electrode, the shapes of the holes on both sides are made non-circular, and the substantial center of each hole is aligned with the second grid electrode. It is disclosed in Japanese Patent Application Laid-Open No. 1989-1987 that the electron beam holes on both sides of the
It is disclosed in the publication No.-108153. The latter method has the problem that setting of jigs, manufacturing, and management are not necessarily easy.

[Problems to be Solved by the Invention] In an in-line color cathode ray tube electron gun, three electron beams emitted from the cathode are strongly focused by the main electron lens, and are focused on the minimum beam diameter on the fluorescent surface. is focused so that it is obtained. FIG. 2(a) shows an example of a conventional electron gun. In this electron gun, a first grid electrode 1, a second grid electrode 2. The voltage values applied to the third grid electrode 3 and the fourth grid electrode 4 are gradually increased, and a main lens is formed where the third grid electrode and the fourth grid electrode face each other. The electron beam passing holes on both sides on the fourth grid electrode side forming the main lens are set to be offset outward from the both side electron beam passing holes on the third grid electrode side, so that the electron beam trajectory is bent inward. , is subjected to a focusing action as well as a static focusing action. However, if this is done, the electron beams on both sides will be subject to comatic aberration caused by passing through the main lens biased toward the inside of the main lens, that is, toward the tube axis, and as a result, as shown in FIG. 2(C), An outer lateral halo deviation occurs in the electron beam spots on both sides. FIG. 2(b) is a plan view of the vicinity of the electron beam passage hole of the second grid electrode, and shows that the annular protrusion formed around the electron beam passage hole of the second grid electrode is concentric with the electron beam passage hole. Show that something is true.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron gun assembly for an in-line color cathode ray tube in which the halo bias described above does not occur.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes at least the first to fourth grid electrodes, and emits, accelerates, focuses, and concentrates three electron beams lined up on one plane. In the integrally constructed electron gun structure of an in-line color cathode ray tube,
On the surface of the accelerating electrode, that is, the second grid electrode, which faces the focusing electrode, that is, the third grid electrode, an annular protrusion having a diameter larger than the diameter of each hole is provided around the three electron beam passing holes. It was decided that the centers of the annular protrusions surrounding the electron beam passage holes on both sides would be eccentrically outward from the center of the electron beam passage holes.

[Function] Conventionally, it was thought that the prefocus lens formed between the second grating electrode and the third grating electrode had little effect on the halo deviation in the outer lateral direction that occurs in the electron beam spots on both sides. However, it turned out that the impact was surprisingly large. As described above, in the past, the shapes of the holes on both sides of the three electron beam holes provided on the surface of the third grid electrode opposite to the second grid electrode were made non-circular, and the substantial center of each hole was made non-circular. There has been a proposal to shift the position inward with respect to the center axis of the electron beam holes on both sides of the second grid electrode, but this would also involve using non-circular holes, making it easy to manufacture a positioning jig with high precision. However, there were also difficulties in the actual manufacture and management of electron guns. In contrast, according to the present invention, an annular protrusion is formed around each of the three electron beam passing holes on the side face of the second grid electrode facing the third grid electrode. By making the centers of the annular protrusions around the electron beam eccentric to the outside with respect to the center of the electron beam passage hole, it is relatively easy to manufacture tools and manage operations during assembly of the electron gun.

By doing the above, it is possible to reduce the extent to which the electron beams on both sides pass through the main lens biased inward without changing the static concentration, and as a result, the electron beams on both sides can pass through the main lens biased inside. The horizontal halo deviation of the electron beams on both sides, which had been generated due to this, also becomes almost inconspicuous.

[Example] FIG. 1(a) is a cross-sectional view of the vicinity of the second grid electrode of an example of the present invention, in which 1 is the first grid electrode, 12 is the second grid electrode,
3 is a third grid electrode; 12a, 12b, and 12c are electron beam passing holes of the second grid electrode; and 21a, 22b, and 23c are annular projections formed around the electron beam passing holes 12a, 12b, and 12c, respectively. be. Figure 1(b) shows the second
This is a plan view of the vicinity of the electron beam passage holes of the grid electrode 12, showing one annular protrusion 21a for each of the electron beam passage holes 12a and 12c.

It can be seen that 23c is formed eccentrically outward.

By doing this, the electron beam trajectory B curves slightly outward as shown in FIG. 1(a) and passes through the main electron lens 5 without being biased only inward. ), the halo bias is hardly recognized. By implementing the present invention, the amount of change in the halo bias aberration voltage can be halved. If the amount of aberration voltage change from the state in which the halo is biased to the right to the state in which it is biased to the left is Δvf, then ΔV is the same as in the conventional case.

Compared to this, we were able to reduce it by more than half.

In the present invention, the length of the third grid electrode (box-shaped, at both ends of the tube axis, forming electron lenses on the second grid side and @4 grid side, respectively) is long, and the focusing voltage is approximately 8% higher than that of a normal tube. The effect was particularly large for high-performance tubes, such as tubes with ~13% higher lattice electrodes and tubes with 1st to 6th grid electrodes, where the 2nd and 4th grids are at equal potential, and the 3rd and 5th grids are at equal potential. .

[Effects of the Invention] As explained above, according to the present invention, the angle of incidence of the electron beam on the main lens changes, making it possible to reduce the halo deviation of the electron beam spot. There is no need to change, and the current management method can be used.

[Brief explanation of the drawing]

FIG. 1(a) is a cross-sectional view of the vicinity of the second grid electrode of the embodiment of the present invention, FIG. 1(b) is a plan view of the vicinity of the electron beam passage hole of the second grid electrode of the same embodiment, and FIG. c) is a diagram showing the state of the electron beam spot in the example, FIG. 2(a) is a cross-sectional view of the electrode system of the conventional electron gun, and FIG.
A plan view of the vicinity of the electron beam passage hole of the grid electrode, Fig. 2(c)
) is a diagram showing the state of the electron beam spot in the conventional example. l...First grid electrode, 2.12...Second grid electrode, 3...Third grid electrode, 4...Fourth grid electrode,
12a. 12b, 12c... Electron beam passing hole of the second grid electrode according to the present invention, 21a, 22b, 23c... First ellipse formed around the electron beam passing hole of the second grid electrode according to the present invention Figure 2

Claims (1)

[Claims] 1. In an electron gun assembly integrally constructed of an in-line color cathode ray tube that is equipped with at least the first to fourth grid electrodes and emits, accelerates, focuses, and concentrates three electron beams lined up on one plane, the accelerating electrode That is, on the surface of the second grid electrode facing the focusing electrode, that is, the third grid electrode, annular protrusions having a diameter larger than the diameter of each hole are formed around the three electron beam passing holes. 1. An electron gun assembly for a color cathode ray tube, characterized in that the centers of annular projections around an electron beam passage hole are eccentrically outward from the center of the electron beam passage hole.