JPH0129016B2 - - Google Patents

Description

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

The resolution characteristics of an electron gun for a picture tube 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 diameter of the electrode that constitutes the main electron lens. In an in-line electron gun in which three apertures through which the electron beam passes are arranged in a straight line, simply increasing the diameter of the main electron lens increases the eccentric distance between the apertures and also increases the distance between the apertures and the arrangement of the electron gun. The picture tube neck diameter must be increased.

As is well known, an increase in the eccentric distance deteriorates the convergence characteristic of concentrating the three electron beams over the entire area on the fluorescent surface, and an increase in the net diameter increases the deflection power of the picture tube, both of which are undesirable. .

Therefore, as shown in Figures 1 and 2, as a method of increasing the aperture D of the main electron lens constituent electrode without changing the eccentric distance S and the net diameter of the in-line electron gun, the eccentric distance of the three apertures is An electrode structure has been proposed in which three apertures having an aperture D of S or more are arranged in-line by overlapping each other.

FIG. 1 shows a top view of the electrode 11 in which three apertures 11R, 11G, and 11B each having a diameter D greater than or equal to the aperture eccentric distance S are arranged in-line by overlapping each other, and each aperture 11R, 11G, Reference numeral 11B does not form independent openings, but is a continuous communication hole with an overlapping portion, and a linear partition electrode 12 is installed at the boundary between adjacent openings. Figure 2 shows the electrode with the above structure as a focusing electrode.
G3 and G4 are placed opposite each other as anode electrode G4.
A side sectional view of an electron gun assembly 1 in which a potential focus type main electron lens is formed is shown. As shown in Fig. 1, this main electron lens has apertures in the focusing electrode G3 and anode electrode G4 that are axially symmetrical and not independent apertures.
Since it has an truncated circular shape with a straight line in the horizontal direction, which is the direction in which the holes are arranged, the horizontal lens action is weaker than the vertical lens action, and the beam spot on the fluorescent surface becomes vertically elongated. Resolution is lost. In particular, the central aperture has a truncated circular shape with straight parts at both horizontal ends, making it more vertically elongated than the beam spot formed by the outer apertures.
The vertical resolution of the central main electron lens is further degraded than that of both outer main electron lenses. This deterioration in resolution characteristics becomes more noticeable in a high current region where the diameter of the electron beam occupying the electron lens becomes large.

Normally, the aperture eccentricity of the main electron lens of the final electrode is set to be about 3 to 5% larger than the above-mentioned S, and the outer two electron beams are electrostatically concentrated. We will ignore the increase in aperture due to increase in distance.

The present invention eliminates the above-mentioned drawbacks and sufficiently reduces the spherical aberration of the main electron lens while keeping the three electron gun aperture eccentric distances of the conventional inline electron gun assembly the same. The purpose is to provide a type electron gun structure.

That is, the main electron lens of the in-line electron gun structure is a multi-stage focusing electron lens in which three or more electrodes are opposed to each other and a focusing electron lens stage is constructed between two or more opposing electrodes, and each focusing electron lens from the front stage to the rear stage is While keeping the aperture eccentric distance S the same in the electron lens stage, the ratio of the main electron lens electrode aperture D to S is gradually increased from 1 or less to 1 or more to eliminate spherical aberration in the large-diameter focusing electron lens stage. It is designed so that it can be reduced.

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

FIG. 3 shows an embodiment of the invention, which is electrically and structurally common to three electron guns, each electron beam path having an integrated electrode forming a substantially separate electron lens, and the main electron FIG. 2 is a sectional side view of a main part of an in-line electron gun assembly 2 whose lenses are multistage focusing electron lenses, including the axes of three electron guns.

The in-line three-electron gun type electron gun assembly 2 is opposed to three cathode assemblies 20 (not shown) that are insulated from each other and arranged in a line with the same three-electron gun aperture eccentric distance S as in the past. G1 electrode 21 and G2 are integrated electrodes arranged sequentially in the electron beam traveling direction.
The electrode 22 and the first to fourth focusing electrodes include an electrode in which two occluded cylindrical body electrodes are overlapped at the mouth edge.
Consisting of G3 to G6 electrodes 23 to 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, to maintain a predetermined electrode spacing. However, 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.
The G3 electrode 23 and the G5 electrode 25 are also connected to each other and a medium-high voltage of about 10 to 40% of the anode voltage is applied.
5, and three stages of focusing electron lenses are formed between two opposing electrodes, G5 electrode 25 and G6 electrode 26, respectively.

However, in Figure 3 and in the same figure, A-A', B-B', and C
As shown in FIGS. 4 to 6, which are part of the plan views of the G3 electrode 23 _-2 , the G4 electrode 24 _-2 , and the G5 electrode 25 _-2 indicated by the arrow -C', On the other hand, the diameter of the electrode apertures in each focusing electron lens stage increases in three stages, from a size that does not overlap with each other to a diameter that overlaps with each other.

That is, the first focusing electron lens stage is formed.
In the G3 electrode 23 _-2 and the G4 electrode 24 _-1 , the diameter D 1 of the electrode hole H ₃₄ is the diameter D ₁ of the center and both outer holes for the electrode material with a plate thickness of 0.2 to 0.4 mm, which is normally used for electrode formation. The gap distance was selected to be sufficiently large, S-D ₁ = 1.2 to 0.7 mm, and the electrode formation was easy, and 0.75≦D ₁ /S
It satisfies the relationship <0.835. In addition, the above conditions are met
The size of D ₁ is the same value as conventionally used.

The G4 electrode 24 _-2 and the G5 electrode 25 _-1 forming the second focusing electron lens stage are formed by the electrode forming method already disclosed by the applicant, and have three openings.
The aperture diameter D ₂ of H ₄₅ has a value that is increased so that the gap S-D ₂ between the central and both outer apertures is approximately the thickness of the electrode forming material without overlapping each other. In this case, the relationship between D ₂ and S is 0.835≦D ₂ /S<1.0
meets the requirements.

Next, G5 forms the third focusing electron lens stage.
In the electrode 25 _-2 and the G6 electrode 26, the aperture diameter D ₃ of the three apertures H ₅₆ is greater than or equal to the aperture eccentric distance S, so the three apertures overlap each other, but their shape is that of the center and both outer sides. The overlapping part of the openings is a truncated circular opening having a linear partition part _C56 whose width is approximately the thickness of the electrode forming material.
Are the projecting edges B ₃₄ and B ₄₅ formed around the electrode openings H ₃₄ and H ₄₅ forming the first and second stage focusing electron lenses described above continuous _?
The protruding edges B ₅₆ formed around the aperture H ₅₆ of the G6 electrode 26 are located at two locations for the central aperture and at one location for both outer apertures.
Since it is discontinuous by being cut at several places, a partition electrode 29 higher than the height of the formed protruding edge B ₅₆ is installed in the overlapped part, and the electron lens electric field formed in the third focusing electron lens stage is installed. This is to prevent the electron lens electric field from being disturbed by interference with each other. If the degree of overlapping of the holes H ₅₆ of the G5 electrode 25 _-2 and the G6 electrode 26 is too large, each hole will have a truncated circular shape with a straight line in the horizontal direction, which is the direction in which the holes are arranged. Since the directional lens effect is significantly weaker than the vertical lens effect, in order to minimize this effect in the electron gun structured according to the present invention, the aperture diameter D ₃ must be selected to satisfy 1.0≦D ₃ /S<1.2. Bye.

In the in-line electron gun structure 2 described above, G1
After the crossover point is formed between the electrode 21 and the G2 electrode 22, the electron beam fluxes of the three electron guns that have passed through the aperture _H3 of the G3 electrode _23-1 and have not been sufficiently diffused are transferred to the second and third stages. Eye focusing electron lens electrode aperture
It is strongly focused by the first stage focusing electron lens, which has an aperture D ₁ smaller than D ₂ and D ₃ and is equipped with a perfect circular hole, and then is larger than the first stage main electron lens electrode aperture D ₁ .
The beam is then guided with approximately the maximum beam diameter into a second-stage focusing electron lens equipped with a complete circular hole. The second stage focusing electron lens stage has a larger electrode aperture D ₂ than the first stage and has a completely circular hole shape, so the formed electron lens is weaker than the first stage and spherical aberration is reduced. The electron beam flux that has reached almost the maximum beam diameter within the electron gun is not affected by spherical aberration as compared to the electron gun structure of the conventional structure, which has the same electrode aperture as the first stage focusing electron lens electrode, and is uniform. The electron beam is focused to a sufficiently small diameter in the second focusing electron lens stage, and then enters the third focusing electron lens in the final stage. Although the third focusing electron lens stage has an incomplete circular hole, its electrode aperture is the largest, so the center part corresponding to the diameter of the electron beam after passing through the second focusing electron lens is the center part of the first and second stages. The spherical aberration is smaller than that of a focusing electron lens, and the convergence force of the electron lens is uniform without being affected by the directionality in the aperture arrangement direction. Therefore, the electron beam is uniformly and sufficiently focused, and the electrons on the fluorescent surface are The beam spot is not distorted into a non-circular shape, and the electron beam spot is significantly smaller than when using an electron gun structure with a conventional structure in which three stages of electron lenses are formed with the same electrode diameter as the first focusing electron lens stage. Obtained on a fluorescent surface,
High resolution characteristics can be obtained. Furthermore, with the above configuration, even in a high current range where the diameter of the electron beam occupying the electron lens becomes large, the electron beam spot is not distorted into a non-circular shape and high resolution characteristics are maintained.

In the above explanation, the case where the main electron lens has three stages composed of four main electron lens electrodes has been described, but for example, a multistage focusing electron lens composed of four stages may be used, with five main electron lens electrodes facing each other. Furthermore, the above-mentioned three-stage focusing electron lens was a multi-stage focusing electron lens in which medium-high voltage and high voltage were applied alternately. It goes without saying that the present invention can be applied to other multistage 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 can also be applied 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 top view of a conventional main electron lens constituent electrode that has apertures having an aperture diameter greater than the eccentric distance of three apertures, and which has truncated circular superimposed apertures arranged in-line by overlapping each other. 3 is a side sectional view including the axis of the three electron guns of an electron gun assembly in which the electrodes of the above structure are opposed to each other to form a bipotential focus type main electron lens, and FIG. 3 is a side sectional view including the axis of the three electron guns. Figures 4 to 6 are side sectional views of main parts including the axis 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, and Figures 4 to 6 are A-A' in Figure 3;
B-B', C-C'arrow G3 electrode 23 _-2 , G4 electrode 2
4 _-2 and a plan view of the G5 electrode 25 _-2 , respectively. 11...Main electron lens constituent electrode, 12...Partition electrode, 21-26...G1-G6 electrode, _H34 ...G3
Electrode 23 _-2 , hole in G4 electrode 24 _-1 , H ₄₅ ...G4 electrode 24 _-2 , hole in G5 electrode 25 _-1 , H ₅₆ ...G5 electrode 25 _-2 , hole in G6 electrode 26, _B34 , _B45 , _B56 ...
Projected edge of the opening, C ₅₆ ...Straight partition.

Claims (1)

[Claims] 1. The main electron lens of the in-line electron gun structure is a multi-stage focusing electron lens in which three or more electrodes are opposed to each other and a focusing electron lens stage is configured between two or more opposing two electrodes, and the electron beam is The ratio of the main electron lens electrode aperture D to S was gradually increased from 1 or less to 1 or more while keeping the aperture eccentric distance S the same in each focusing electron lens stage from the front stage to the rear stage on the cathode side that emits . An in-line electron gun structure featuring 2 The main electron lens is composed of four electrodes, G3 to G6, with the G4 and G6 electrodes set to a common high voltage anode potential, and the G3 and G5 electrodes set to a common high voltage of 10 to 10% of the anode voltage.
In the in-line electron gun assembly described in item 1, in which three stages of focusing electron lenses are formed by maintaining a common medium-high potential corresponding to 40%, the first to third stages of focusing electron lenses are formed. When the electrode diameters of the G3 and G4 electrodes, the G4 and G5 electrodes, and the G5 and G6 electrodes facing each other are D ₁ to D ₃ , 0.75≦D ₁ /S<0.835,
An in-line electron gun assembly characterized by satisfying the following relationships: 0.835≦D ₂ /S<1.0 and _{1.0≦D 3} /S<1.2.