JPS6119030A - Electron gun - Google Patents

Abstract

PURPOSE:To improve a focusing property by forming a circular arc part in a position, corresponding to the central electron beam, of the linear part passing two circular hole parts on both sides corresponding to both side electron beam paths in the salient edge part of an electrode on high voltage side. CONSTITUTION:An electron gun is composed of a cathode 10 and a complex large aperture lens consisting of a G1 electrode 2, a G2 electrode 3, G3 electrode 4, 5 and the G4 electrodes 6 and 7 to be impressed by high voltage. Thereby, a circular arc part 6f having a radius Rc is provided in the place, corresponding to the central electron beam, of the line passing the circular hole parts 6b and 6c having a radius Rs and lying on both sides of the salient edge part 6d of the G4 electrode 6 is provided, while the width of said circular arc part is made to be Hb and the width of the linear part connecting the circular arc part 6f to the circular hole parts 6b, 6c is made to be Ha, followed by selecting Ha and Hb in order to set up the respective outline shapes of the beams in the center and on both sides independently into true circles. Thus, the focusing property can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron gun used in an in-line color cathode ray tube.

[Prior art]

Recently, in order to improve the convergence performance of infin type color cathode ray tubes, there has been a trend to reduce the distance between the three infin electron beams. However, when the distance between the three electron beams is reduced, the diameter of the focus lens for focusing the electron beam becomes smaller, and the electron beam focusing power deteriorates.

For this reason, proposals have been made in which multiple focus lenses are overlapped with each other for each of the three electron beams in the Infin structure, or a compound large-diameter lens is used.

FIG. 1 shows a cross-sectional view of the above-mentioned proposed electron gun, which was announced in 1982 by the American company ECA. Three electron beams (11Fi), (IIG), (
IIB) are G1 electrode (2), G electrode (3) and G
, the 03 side electrode (4) of the electrode (also referred to as a focus electrode, to which a medium-high voltage is applied) passes all the way through, and the 04' Wft pole (to which a high voltage is applied) passes through the 04 side electrode (6) of the G electrode (to which a medium-high voltage is applied). 6) The G4 plate is focused by a composite large-diameter lens (14A to 14D) composed of a pole (7) and a minute spot is formed on a fluorescent surface (not shown).

In the above configuration, three Infin electron beams (1tR)
, (lIG), (1tB) is the conventional 5. (i
Since it is significantly narrower from Ml to 5.1H, it has the characteristic that the coherence performance is improved by more than 50%.
If the above-mentioned distance P is narrow, the compound large-diameter lens shown in Fig. 1 (
14A), (14B) 'e has been adopted to increase the aperture of the focus lens and improve focus performance.

FIG. 2 (fL) is a view taken along the line A-A in FIG. 1, showing the Gs electrode (5), and each electron beam (IIR), (IIG),
(IIB) Small diameter electronic lens (140) corresponding to each
The three apertures (to) forming the beam are arranged in-line with the same dimension as the beam spacing P. In order to completely form a large-diameter compound lens on the surface with these three apertures a3,
Projected edge (5a) as a surface forming the gap between G1 and G4 electrodes
It is located in a concave portion (5b) that is depressed by about 3 HIM.

On the other hand, FIG. 2(b) is a view taken along the line B-B in FIG.
The hole (6a) of the G4 electrode (6) facing the G and electrode (5) has a complicated peanut shape. This peanut-shaped hole (6a) has circular holes on both sides (6
b), the shape can be determined by the radius Rs of (6(1)), the distance d1 between the biaxial diameters Fs, and the width H of the straight portion connecting the holes on both sides.

Of course, the 04 electrode (6) as the high voltage electrode in this case
The three openings Q4 are also located in a recess (6e) that is depressed by about 3 mm from the protruding edge (6d) that forms the gap between the Gs and G4 electrodes. In addition, Fig. 2 (a
), (b), (g) is bead glass for supporting the electrode.

By the way, the compound large-diameter lens (14A) shown in FIG.
The electron beam focused at ~(14D) passes through the fluorescent surface (
However, the conventional electrode shape method shown in Fig. 2 has a central electron beam (IIG), both side electron beams (IIB),
IB) shows contradictory electron beam shapes.

Figure 3 shows the circular shape of the electron beam in terms of roundness BE (Incorporated), and shows the peanut-shaped hole (6a) of the G4 electrode (6).
) is a diagram illustrating the situation when the linear portion width H dimension of the curve is changed.

As is clear from Figure 3, conventionally the central electron beam (1
1G) BE curve and double-sided electron beam (IIB).

The width dimension H was set to no where the EEE curve of (11R) was closest. In this case, the central electron beam (IIG) had a slightly elongated electron beam shape, and the side electron beams (IIB) and (IIR) had slightly horizontally elongated electron beam shapes. Therefore, since there is no coincidence between the two, the focus voltage adjustment is insufficient and the focus performance deteriorates.

[Summary of the invention]

This invention was made to eliminate the above drawbacks.
The two electrodes constituting the main electron lens have three in-line apertures, and the mutually opposing apertures of the electrodes are located in a recessed part receding from the protruding edge forming the gap between the two electrodes. In guns.

Of the two t-poles, the protruding edge of the high-voltage side electrode.

By forming an arcuate portion in the straight line section that connects the two circular holes on both sides corresponding to the electron beam passages on both sides, at a location corresponding to the central electron beam, the focus voltage can be adjusted optimally and the focus performance can be completely improved. The purpose is to provide an electron gun.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 4 is a front view of the 04 electrode (6) as a high voltage electrode according to an embodiment of the present invention. In this figure, G4
An arcuate portion (6f) with a radius of Roi is located at a location corresponding to the central electron beam of the conventional straight portion connecting the circular hole portions (sb), (6o)v with a radius of RsO on both sides of the protruding edge portion (6d) of the electrode (6). ), the width of the circular arc part (6f) is Hb, and the circular hole part (6b) with radius Rs on both sides of the circular arc part (6f)
, (6(1)) is expressed by Ha.

As is clear from the characteristic diagram of the H dimension of the conventional 04 electrode (6), that is, FIG. Roundness B of electron beam (IIB), (11F+)
Various experiments have revealed that in order to improve Et, it is necessary to set it to a value smaller than Ho.

Figure 5 shows the hole shape and dimension Ha of the 04 electrode (6) of the present invention.
.

Hb and electron beams (IIB), (IIG), (II
It shows the relationship between the roundness characteristics of R). From this figure, the center electron beam (IIG) has the circularity io of the electron beam.
The radius H of the G, vL pole (6) shown by o*'e is H=Hb,
Hb:>HOte exists. In addition, both side electron beams (1t
B) , (11R) is the width Hif indicating 100% circularity of the electron beam, H=Ha e Ha<HO.

As above, Ha, lb dimension 2 Ha <
Ho, Hb>H.

The center electron beam (IIG), both side electron beams (IIB), and (IIB) can each be independently set to a perfect circle shape, which makes it possible to achieve a Focus voltage can be adjusted optimally to improve focus performance.

〔Effect of the invention〕

As explained above, according to the electron gun of the present invention, the central electron beam corresponds to the straight portion of the protruding edge of the high-voltage side electrode that connects the two circular holes on both sides corresponding to the electron beam passages on both sides. By forming the arcuate portions at the positions where the focus voltage is adjusted, it is possible to optimally adjust the focus voltage and improve the focus characteristics.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of an electron gun that uses a conventional compound large-diameter lens, Figure 2 (a) is a view taken along line A-A in Figure 1, and Figure 2 (b) is B in Figure 1. -B line arrow view, FIG. 3 is a beam circularity characteristic diagram of a conventional compound large-diameter lens, FIG. 4 is a front view of the 04 electrode as a high voltage electrode according to an embodiment of the present invention, and FIG. 5 is a beam circularity characteristic diagram for determining the shape of the G4 electrode according to an embodiment of the present invention. (5) "Gi electrode, (5B) --- projecting edge, (5b
)...concavity, (6)...Ga t[pole, (6b)
, (60) ・Pl hole, (6d)-'! Edge, (6
e)... Concave portion, (6f)... Arc portion, (7)...
・G4 plate electrode, (IIB), (IIG), (II
R)...Electron beam, U, α→...Aperture. In addition, the same reference numerals in the figures indicate equivalent parts.

Claims (1)

[Claims] (1) The two electrodes constituting the main electron lens have three in-line apertures, and the apertures facing each other are inside a recessed part receding from the protruding edge that forms the gap between the two electrodes. In the electron gun shown in FIG. An electron gun characterized by forming an arcuate portion.