JPH0129017B2 - - 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 electrodes constituting 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 shows a conventionally used electronically and structurally common system in which each electron beam path has an integrated electrode that essentially forms an individual electron lens, and the main electron lens is of a bi-potential focus type. A side cross-sectional view including the axis of three electron guns of an in-line type electron gun assembly 1 is shown. The in-line electron gun assembly 1 includes three cathode assemblies 10 that are insulated from each other and arranged in a line at equal distances S, and integrated electrodes that are arranged in sequence in the direction of electron beam propagation in opposition to these cathode assemblies 10.
G1 electrode 11, G2 electrode 12, G3 electrode 13 which is a focusing electrode made by overlapping two closed cylindrical electrodes 13 _-1 and 13 _-2 at the mouth edge, and G4 electrode 14 which is a closed cylindrical body and is an anode electrode. , and a shielding magnetic pole 17,
Although each electrode except for the shielding magnetic pole 17 is not shown, it is fused and fixed to the insulator support rod 18 via each electrode support part, and a predetermined electrode interval is maintained, and an independent electron gun 1R, 1G and 1B are formed. G4 electrode 1 of each electron gun 1R, 1G, 1B
The apertures D ₃₀ of the apertures H ₃₀ and 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 about 3 to 5% larger than the above-mentioned S, and accordingly, the aperture D' ₄₀ of both outer apertures H' ₄₀ of the G4 electrode 14 is larger than the G3 Opening diameter of electrode 13 D ₃₀
Asymmetrical electric fields are 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, and the outer two electric fields are formed at the center of the fluorescent surface of the cathode ray tube. 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 for the purpose 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, it has an electron beam forming section consisting of at least a cathode, a G1 electrode, and a G2 electrode, and G3, G4, G5, and G6 electrodes that accelerate and focus the electron beam emitted from this section. electrode and G5 electrode,
In an in-line electron gun assembly equipped with a multi-stage focusing electron lens system in which a three-stage main focusing electron lens is formed at each opposing part of the G5 and G6 electrodes, the main focusing electron lens of the front two stages on the cathode side of the central electron gun By making the electron lens electrode aperture larger than the electrode aperture of both outer electron guns, and by making the third stage main electron lens electrode aperture on the electron beam exit side of both outer electron guns larger than the electrode aperture of the central electron gun, The spherical aberration can be reduced by the large-diameter focusing electron lens stage of each electron gun without changing the strength of both outer main electron lenses.

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 separate electron lenses in each electron beam path, with the main electron lens being G3~ FIG. 2 is a sectional side view of a main part of an in-line electron gun assembly 2 including the axis of three electron guns, in which four electrodes consisting of G6 electrodes are opposed to each other to constitute a three-stage main focusing electron lens.

The in-line electron gun structure 2 has three cathodes 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 a cathode 20 (not shown) that faces in the electron beam traveling direction. The G1 electrode 21, the G2 electrode 22 (the above is referred to as an electron beam forming part), which are integrated electrodes arranged sequentially in G3 electrode 23 which is the first to fourth focusing electrodes
Consisting of a G6 electrode 26 and a shielding magnetic pole 27, each electrode except the shielding magnetic pole 27 is fused and fixed to an insulator support rod 28 via each electrode support part, although not shown.
A predetermined electrode spacing is maintained, and independent electron guns 2R, 2G, and 2B are formed 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 2.
3 and G5 electrodes 25 are also connected to each other and the anode voltage is 10
A medium-high voltage of ~40% is applied to the G3 electrode 23.
and G4 electrode 24, G4 electrode 24 and G5 electrode 25, and
Three stages of focusing electron lenses are formed between two opposing electrodes, G5 electrode 25 and G6 electrode 26, respectively.

Generally, the focal length f of a composite lens with focal lengths f ₁ , f ₂ , f ₃ and distances between the electron lenses d ₁ and d ₂ is given by the following equation.

1/f=1/f ₁ +1/f ₂ +1/f ₃ −d ₁ /f ₁ f ₂ −
d ₂ / f ₂ f ₃ − (d ₁ + d ₂ ) / f ₃ f ₁ + d ₁ d ₂ / f ₁ f ₂ f ₃ ...(1) However, in Fig. 2 and the arrow A-A' in the same figure, As shown in FIG. 3, which is a plan view of the G3 electrode _23-2 , a first focusing electron lens stage is formed on the cathode side.
At the opposing part of G3 electrode 23 _-2 and G4 electrode 24 _-1 ,
Diameter of both outer openings H _S34 of both outer electron guns 2R and 2B
While keeping D ₂ at the same aperture diameters D ₃₀ and D ₄₀ as the conventional ones of the G3 electrode 13 and _G4 electrode ₁₄ shown in FIG.
The diameter becomes larger than both outer openings until it circumscribes the rim of H _S34 . Similarly, in Fig. 2 and the arrow B-B' in the same figure,
As shown in FIG _{. 4} , which is a plan view of the G4 electrode _24-2 , the center electron The caliber of the central opening H _C45 of gun 2G is _D1 ,
The diameter of both outer openings H _S45 is set to _D2 . On the other hand, the G5 electrode 25 _-2 shown in Fig. 2 and the C-C' arrow in the same figure
As shown in FIG. 5, which is a plan view of the electron beam, in the opposing portion of the G5 electrode _25-2 and the G6 electrode 26, which form the third stage focusing electron lens on the electron beam exit side, The central aperture of the central electron gun 2G has a reverse relationship with the first and second stage electron lenses described above.
Change the caliber of H _C56 to small caliber D ₂ , both outer electron guns 2R,
The diameters of both outer openings H _S56 of 2B are set to the large diameter _D1 .

Here, if the central and both outer electron lenses are represented by suffixes C and S, and the electron lenses formed by apertures D ₁ and D ₂ are represented by suffixes 1 and 2, and equation (1) is applied to the above-mentioned electron lens, then Focal length fcenter of the composite main electron lens of the central and both outer electron guns,
fside is given by the following formula.

1/fcenter=1/f _C11 +1/f _C12 +1/f _C2 -d ₁ /f _C
11 f _C12 −d ₂ /f _C12 f _C2 −d ₁ +d ₂ /f _C2 f _C11 +d ₁ d ₂ /f _C11 f _C12
f _C2 ……(2) 1/fside=1/f _S21 +1/f _S22 +1/f _S1 −d ₁ /f _S21
f _S22 −d ₂ /f _S22 f _S1 −d ₁ +d ₂ /f _S1 f _S21 +d ₁ d ₂ /f _S21 f _S22
f _S1 ...(3) Normally d ₁ < D ₁ , D ₂ so f _C11 = f _C12 ≡ f _C1 , f _S21
=f _S22 ≡f _S2 , and equations (2) and (3) are 1/fcenter=2/f _C1 +1/f _C2 −d ₁ /f ² / _C1 −d ₂ /f
_C1 f _C2 −d ₁ +d ₂ /f _C2 f _C1 +d ₁ d ₂ /f ² / _C1 f _C2 …(4) 1/fside=2/f _S2 +1/f _S1 −d ₁ /f ² / _S2 −d ₂ /f _S2
f _S1 −d ₁ +d ₂ /f _S1 f _S2 +d ₁ d ₂ /f ² / _S2 f _S1 ...(5).

Also, the relationship between the apertures of the central and both outer electron lenses is
Since D ₁ > D ₂ , the following relationships hold: f _C1 > f _C2 , f _S1 > f _S2 (6).

Furthermore, in the electron gun with the above configuration, d ₁ < d ₂ can be selected, so even if the aperture is the same, f _C1 > f _S1 , f _C2 < f _S2 ...( 7) Therefore, from equations (4) to (7), it is possible to set fcenter=fside...(8). On the other hand, the following relationship clearly holds from equations (4) and (5).

fcenter＜f _C1 , f _C2 , fside＜f _S1 , f _S2 ...(9) As mentioned above, in the electron gun according to the present invention, the main electron lens parts of the central electron gun 2G and both outer electron guns 2R and 2B are Since each stage has a large-diameter electron lens stage, the lens strength can be weaker and the spherical aberration can be made extremely small in the large-diameter electron lens stage than in conventional three-electron guns configured with equal diameters, and (9) As shown in the formula, the aberrations of the main electric lenses of the central and both outer electron guns are significantly reduced due to the weak focusing lens strength of each stage of the multi-stage focusing lens and the effect of reducing spherical aberration. Therefore, according to the embodiments 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 large-diameter electron lens parts of the center and both outer electron guns are provided at different stages, but by making the number of stages of the large-diameter electron lens parts different, as shown in equation (8), It is possible to match the focusing conditions of the electron gun.

In addition, in the present invention, the large-diameter main electron lens section is configured at the front stage of the central electron gun and at the rear stage of both outer electron guns, but this is generally not necessary when assembling an in-line electron gun structure. Since the core rod is passed through the plurality of electron gun constituent electrodes from the end (corresponding to the G6 electrode 26 in this example) side through their both outer openings, and they are stacked one on top of the other in order, the diameter of the core rod and the aperture diameter of the electrodes to be stacked are the same. This is done in consideration of the fact that the two parts can be completely fitted together, and if the large-diameter parts are reversed in this embodiment and in the front and rear stages, it will be difficult to assemble the electron gun assembly, and the assembly accuracy will also deteriorate.

Alternatively, 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 focusing electron lens stages with large apertures. It is possible to effectively increase the diameter of the three openings in the electron lens stage compared to making the same large diameter holes, and the electrode processing and formation thereof becomes easier. For example, when the distance S between three electron guns is 6.6 mm, the diameter D ₂ of the small diameter part is 5.5 mm, which is the same as before, and the gap between adjacent holes is 0.5 mm, the diameter D ₁ of the large diameter part is 6.7 mm.
This is approximately 22% larger than the small diameter _D2 .

In the above explanation, the three-stage focusing electron lens was a multi-stage focusing electron lens in which medium-high voltage and high voltage were applied alternately. Needless to say, the present invention can be applied to 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 three electron guns of an in-line electron gun assembly in which the main electron lens used in the past adopts a bipotential focus method, and Fig. 2 shows an embodiment of the present invention. Figures 3, 4, and 5 are side sectional views including the axes of three electron guns of an in-line type electron gun assembly in which the main electron lens adopts a multi-stage focusing electron lens system. B-B',
Plan views of the G3 electrode 23 _-2 , the G4 electrode 24 _-2 , and the G5 electrode 25 _-2 of C-C' are shown, respectively. 13, 23...G3 electrode, 14, 24...G4 electrode, 25...G5 electrode, 26...G6 electrode, H _S34 ...
...Both outer openings of G3 electrode 23 _-2 and G4 electrode 24 _-1 ,
H _C34 ... G3 electrode 23 _-2 , central opening of G4 electrode 24 _-1 , H _S45 ... G4 electrode 24 _-2 , both outer openings of G5 electrode 25 _-1 , H _C45 ... G4 electrode 24 _-2 , G5 electrode 25
_-1 central opening, H _S56 , H′ _S56 ...G5 electrode 25 _-2 ,
Both outer openings of the G6 electrode 26, H _C56 , H' _C56 . . . G5 electrode 25 _-2 , central opening of the G6 electrode 26, S . . . distance between three electron guns.

Claims (1)

[Claims] 1 It has an electron beam forming section consisting of at least a cathode, a G1 electrode, and a G2 electrode, and G3, G4, G5, and G6 electrodes that accelerate and focus the electron beam emitted from this section, and the G3 electrode, G4 electrode, and G4 electrode In an in-line electron gun assembly equipped with a multi-stage focusing electron lens system in which a three-stage main focusing electron lens is formed by opposing parts of the G5 electrode, the G5 electrode, and the G6 electrode, the first two main stages on the cathode side The aperture of the electron lens electrode of the central electron gun is set to be larger than that of the center and both outer electron guns, and the aperture of the main electron lens electrode of the third stage on the electron beam exit side is set to be larger than that of the center and both outer electron guns. By making the aperture of the outer electron gun larger than when the diameter was made equal, the main electron lenses of each electron gun were made equal in diameter without changing the strength of each composite main electron lens of the central and both outer main electron lenses. An in-line electron gun characterized by reducing spherical aberration with a focusing electron lens stage with a larger diameter than the previous one.