JPH0133894B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the resolution of an in-line color picture tube electron gun.

The resolution characteristics of an electron gun are mainly limited by the spherical aberration of the electron lens, and in order to obtain high resolution characteristics, it is necessary to reduce the spherical aberration of the electron lens by increasing the aperture of the electrode that constitutes the main 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. When designing an electron gun structure, an important point is how to increase the diameters of the three main electron lenses for a fixed inner diameter of the glass neck.

Figure 1 is electrically and structurally common to conventional electron beams, each electron beam path has an integrated electrode that essentially forms an individual electron lens, and the main electron lens employs a bi-potential focus system. A side sectional view including the axis of three electron guns of the in-line type electron gun 1 adopted is shown. The in-line electron gun structure 1 includes three cathode structures 10 that are insulated from each other and arranged in a line with equal distances S between them, and a G1 electrode that is an integrated electrode that is arranged in sequence in the direction of electron beam propagation in opposition to the cathode structures 10. 11, G2 electrode 12, two closed cylinder electrodes 1
G3 electrode 13 is a focusing electrode made by overlapping _3-1 and _13-2 at the mouth edge, and G4 is a closed cylindrical body that is an anode electrode.
Consisting of an electrode 14 and a shielding magnetic pole 17, each electrode except the shielding magnetic pole 17 is fused and fixed to an insulator support rod 18 via each electrode support part, maintaining a predetermined electrode interval, and each electrode is Independent electron guns 1R, 1G, and 1B are formed for each electron beam path. G4 electrode 14 of each electron gun 1R, 1G, 1B
The apertures D _{30 , of the apertures H 30} , H ₄₀ forming the main electron lenses of the G3 electrode 13 and the G4 electrode 14 facing _the
D ₄₀ is equal and less than 1/3 of the inner diameter of the glass neck 19.

However, the distance S' between the centers of the main electron lens apertures of the G4 electrode 14 is approximately 2 to 4% larger than the above-mentioned S, and along with this, the diameter of both outer apertures H' ₄₀ of the G4 electrode 14 is
D′ ₄₀ is somewhat larger than the aperture diameter D ₃₀ of the G3 electrode 13, and an asymmetrical electric field is formed on both outer sides of the main electron lens formed in each corresponding aperture gap between the G3 electrode 13 and the G4 electrode 14. At the center of the cathode ray tube's phosphor screen, the two outer electron beams are electrostatically concentrated into a central electron beam. Here, for convenience of explanation, in order to electrostatically concentrate the outer two-electron beam, the increase in the aperture due to the increase in the distance between the minute apertures will be ignored.

For example, the diameter of the glass neck that has been widely used in the past
In the case of a 29.1 mm (inner diameter 23.9 mm) cathode ray tube, the distance between the three electron guns S = 6.6 mm, D ₃₀ = 5.5 mm,
S′ = 6.8 mm, D′ ₄₀ = 5.9 mm, and the main electron lens aperture D ₃₀ is actually less than 1/4, which is much smaller than 1/3 of the inner diameter of the glass neck.

As described above, in the conventional in-line electron gun structure, the aperture diameter of each corresponding main electron lens electrode of the three electron guns is equal, and is 1/3 of the inner diameter of the glass neck.
Therefore, unless the glass neck aperture is increased, the distance between the three electron guns is increased, and the main electron lens electrode aperture is increased, it is not possible to sufficiently reduce the spherical aberration of the main electron lens and obtain high resolution characteristics. Nakatsuta. In particular, in recent years, the distance S between the three electron guns has been made as small as possible with the aim of reducing the deflection power and improving the convergence characteristic of spatially overlapping the scanning screens created by the three electron beams emitted from the three electron guns. There is a trend to reduce the diameter of the cathode ray tube glass neck, and the diameter of the main electron lens electrode becomes smaller.
This is extremely disadvantageous in terms of resolution characteristics.

The present invention eliminates the above-mentioned drawbacks and provides an in-line electron gun structure that can sufficiently reduce the spherical aberration of the main electron lens while maintaining the same distance between the three electron guns in the conventional in-line electron gun assembly, thereby obtaining high-resolution characteristics. The purpose is to provide gun structures.

That is, the main electron lens is a multi-stage focusing electron lens in which three or more electrodes are opposed to each other to form two or more focusing electron lens stages, and in the different focusing electron lens stages, a central electron gun and both outer electron guns form a large diameter part. The same number of stages are formed as the small diameter part and the large diameter focusing electron lens stage, so that spherical aberration can be reduced.

Hereinafter, one embodiment of the present invention will be described in detail based on the drawings.

FIG. 2 shows an embodiment of the invention, which is electrically and structurally common and includes integrated electrodes forming substantially individual electron lenses in each electron beam path, the main electron lens being a multi-stage focusing electron lens. It is a sectional side view of a main part including an in-line type electron gun assembly 2 which is a lens and the axis of a three-electron gun. The in-line electron gun assembly 2 has three cathode assemblies 20 (not shown) that are insulated from each other and arranged in a line with the same distance S between the three electron guns as in the conventional case, and the electron beam advances in opposition to these cathode assemblies 20 (not shown). G1 electrode 21, G2 which is an integrated electrode arranged sequentially in the direction
It is composed of an electrode 22, G3 to G6 electrodes 23 to 26, which are first to fourth focusing electrodes made by overlapping two closed cylindrical body electrodes at the mouth edge, and a shielding magnetic pole 27, and each electrode except the shielding magnetic pole 27 is Although not shown, they are fused and fixed to an insulator support rod 28 via each electrode support part, maintaining a predetermined electrode interval, and forming independent electron guns 2R, 2G, and 2B for each electron beam path.
Here, the G4 electrode 24 and the G6 electrode 26 are connected to each other and a high anode voltage is applied to the G3 electrode 23.
and G5 electrode 25 are also connected to each other and the anode voltage is 10 to 40
A medium-high voltage of about % is applied, and G3 electrode 23 and G4
Focusing electron lenses are formed in three stages between two opposing electrodes: the electrode 24, the G4 electrode 24 and the G5 electrode 25, and the G5 electrode 25 and the G6 electrode 26, respectively.

However, the G5 electrode 2 in Fig. 2 and the arrow A-A' in the figure
As shown in FIG. 3, which is a plan view of _5-1 , the central opening H4 _2c of the central electron gun 2G is located at the opposing portion of the G4 electrode 24 and G5 electrode 25 forming the second focusing electron lens stage. , H5 _1c diameter D45 _c is shown in Figure 1 G3
Same opening diameter as conventional electrode 13 and G4 electrode 14
While maintaining D ₃₀ and D ₄₀ , the diameter D45 _s of both outer openings H4 _2s and H5 _1s of both outer electron guns 2R and 2B is made larger than the central opening until it circumscribes the central opening H4 _2c and H5 _1c . . On the other hand, as shown in FIG. 2 and FIG. 4, which is a plan view of the G5 electrode 25 _-2 indicated by the arrow B-B' in the figure, the G5 electrode 25 and the G6 electrode 26 forming the third focusing electron lens stage are shown in FIG. In the opposing part, the aperture D56 _s of both outer apertures H5 _2c and H6 _s of both outer electron guns 2R and 2B is the same as the aperture diameter D ₃₀ and D ₄₀ , which is the same as the conventional one, so that the relationship is opposite to the above. Keep the central electron gun 2
The diameter D56 _c of the center openings H5 _2c and H6 _c of G is made larger than that of both outside openings until it circumscribes both outside openings H5 _2s and H6 _s .

As mentioned above, the central electron gun 2G, both outer electron guns 2
Since the R and 2B main electron lens sections each have one large-diameter main electron lens stage, the large-diameter electron lens stage can significantly reduce the spherical aberration of the electron lens compared to the conventional one. That is, in both outer electron guns 2R and 2B, the electron beam bundle focused by the first stage of the multi-stage focusing electron lens is focused using the central part of the second stage large-diameter electron lens section where the aberration is small, and the aberration is reduced. Since a small focused beam flux enters the third stage electron lens, even if it is a small diameter electron lens, the beam flux is small and can pass through the center where there is small aberration, and the beam is transmitted through all stages of the electron lens. The beam can be focused without being affected by spherical aberration. In addition, in the central electron gun 2G, the beam bundles focused by the first and second stage electron lenses, which are small diameter electron lenses, are passed through the central part of the final stage electron lens, which is a large diameter electron lens, which has low aberration characteristics. , the beam can be focused without being affected by the spherical aberration of the electron lens. Therefore, according to the embodiment of the present invention, it is possible to sufficiently reduce the spherical aberration of the multistage focusing electron lens and obtain high resolution characteristics.

Furthermore, in the present invention, the main electron lens is a multi-stage focusing electron lens while maintaining the same distance between the three electron guns as in the past, and the central electron gun and both outer electron guns have different stages of focusing electron lenses with larger apertures, so that the same focusing distance can be achieved. The aperture can be increased more effectively than increasing the aperture of three electron lens stages at the same time, and the electrode processing and formation thereof becomes easier. For example, the same three-electron gun mutual spacing distance S = 6.6 as before
In the case of mm, the diameter of the small diameter part is the same as before, 5.5 mm,
If the gap between adjacent holes is 0.5 mm, the large diameter part can be made as large as 6.7 mm, which is approximately 22% larger than the small diameter part.

FIG. 5 is a plan view of one electrode 30 constituting a multi-stage focusing electron lens showing another embodiment of the present invention. In the electrode 30, the diameter D3 _s of both outer openings H3 _s of both outer electron guns 3R and 3B, which are made larger in diameter, is larger than the distance S between the three electron guns, and is adjacent to the completely circular central opening H3 _c . It is an incomplete circular hole with a straight part at the bottom. In this case, even with an incomplete circular hole, the spherical aberration can be made smaller than before in the electron beam passage section, and in combination with the focusing electron lens stages with complete circular holes in the front and rear stages, the incomplete circular hole can be reduced. The non-axial symmetry of the incomplete circular hole can be corrected compared to the case of a single-stage focusing electron lens, the spherical aberration of the multi-stage focusing lens can be made extremely small, and the resolution characteristics of the electron lens can be further improved.

In the above explanation, the main electron lens consists of three stages,
Only two stages of the large-diameter part were used, but for example, a multi-stage focusing electron lens consisting of four stages, with five electrodes facing each other, could be used, and the large-diameter part could be divided into four different stages for the central electron gun and both outer electron guns. It is also possible to arbitrarily select a combination of the large diameter focusing electron lens stages of the central and both outer electron guns and the small diameter focusing electron lens stages. Also, in the explanation, the three-stage focusing electron lens was a multi-stage focusing electron lens in which medium-high voltages and high voltages were applied alternately, or it was said that the three-stage focusing electron lens was a multi-stage focusing electron lens in which medium-high voltages and high voltages were applied alternately, or that the voltage distribution ratio and electrode lengths applied to the four electrodes were different combinations. It goes without saying that the present invention is also applicable to , or other focusing electron lens systems.

Further, the electron gun structure is not limited to an in-line type electron gun using an integrated electrode, but the present invention is also applicable to an in-line type electron gun structure in which the center and both outer electron guns are each composed of independent electrodes. be.

[Brief explanation of drawings]

Fig. 1 is a side sectional view including the axis of a three-electron gun of an in-line type electron gun structure in which the main electron lens used in the past adopts a bi-potential focus system, and Fig. 2 shows an embodiment of the present invention. 3 and 4 are side sectional views including the axis of three electron guns of an in-line electron gun assembly in which the main electron lens adopts a multi-stage focusing electron lens system, and FIGS. B-
FIG. 5 shows a plan view of the G5 electrode taken from B', and FIG. 5 shows a plan view of an electrode showing another embodiment of the present invention. 13,23...G3 electrode, 14,24...G4 electrode, 15,25...G5 electrode, 26...G6 electrode,
H5 _1s , H5 _2S ...Both outer openings of G5 electrode, H5 _1c ,
H5 _2c ... Center opening of G5 electrode, S... Distance between three electron guns.

Claims (1)

[Claims] 1 The main electron lens of the inline electron gun structure is
In an in-line electron gun assembly equipped with a multi-stage focusing electron lens in which three or more electrodes are arranged facing each other in multiple stages to form at least two or more focusing electron lens stages, a large-diameter central electron lens and small-diameter both outer electron lenses are used. and one or more second focusing electron lens stages each having a small-diameter center electron lens and a large-diameter both outer electron lenses; An in-line electron gun assembly characterized in that the number of focusing electron lens stages is the same.