JPS6322606Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to an electron gun for color picture tubes, and in particular,
This invention relates to an electron gun for a color picture tube that constitutes a main electron lens unit that focuses three electron beams arranged in a row.

A shadow mask type color picture tube focuses three electron beams emitted from an electron gun mounted inside the net onto a phosphor screen via a shadow mask, and reproduces a color image on the phosphor screen. .

As the electron gun for the color picture tube, bipotential type, unipotential type, quadrapotential type, etc. have been developed. All types of electron guns have a main electron lens, and the thermionic electrons emitted from the cathode are The electron beam is focused onto a phosphor screen by a main electron lens. This main electron lens is an electrostatic lens,
As with optical lenses, the main performance is determined by the diameter of the lens.

Generally, the maximum diameter of the main electron lens of an electron gun is determined by the inner diameter of the net of the shadow mask-shaped color picture tube and the structure of the electron gun. For guns, the limit is about 30% of the inside diameter of the neck, and for electron guns with a single-row arrangement, the limit is about 28% of the inside diameter of the neck.

That is, the maximum diameter of the main electron lens relative to the inner diameter of the net is small as mentioned above, and in recent color picture tubes, there is a demand for a narrower neck diameter as one means of reducing the deflection power. The maximum diameter of the main electron lens also becomes smaller. Therefore, the aberration of the electron lens becomes large, and the spread component of the electron beam increases due to this, which is one of the factors that worsens the focusing of the electron beam on the phosphor screen.

Next, an example of an electrode structure forming such a main electron lens will be explained with reference to FIGS. 1 and 2.

That is, in the electrode structure 1, a central electron beam aperture 3 and electron beam apertures 4 and 5 on both sides are bored in a plane part 2, and the edge of the plane part 2 is provided with a side wall 6 interposed therebetween. A flange 7 is connected to the flange 7, and the flange 7 is provided with a support piece 8 that is implanted in the bead glass, and is formed into a shallow dish shape as a whole.

The electron beam apertures 3, 4, and 5 have a perfect circular shape;
Alternatively, it has a shape close to a perfect circle, and the diameter D ₁ of the electron beam apertures 3, 4, and 5 is
The width of the bridge B provided between the electron beam apertures 3, 4, and 5 is defined by the spacing _S1 between the centers of the electron beam holes 3, 4, and 5, and there is a drawback that the width of the bridge B cannot be made sufficiently large.

The present invention was devised in view of the drawbacks of the conventional electron guns for color picture tubes, and it is an object of the present invention to provide an electron gun for color picture tubes that can provide a large main lens.

Next, one embodiment of the electrode structure of the electron gun of the present invention will be described with reference to FIGS. 3 to 5.

That is, the electrode structure 11 has a flat part 12, an electron beam hole 13 in the center, and electron beam holes 1 on both sides.
4 and 15 are bored, but these electron beam passage parts 13, 14, 15 form one through hole part 19, and these electron beam passage parts 13, 14, 15
The edge of is formed by one closed curve. That is, each electron beam aperture 1
It has a shape in which three electron beam apertures 13, 14, and 15 are connected, each having a diameter _D2 that is approximately equal to or larger than the center-to-center spacing _S2 of the electron beam apertures. The distance d between the electron beam aperture connecting regions 21 formed by the opposing protrusions 20 formed between the electron beam apertures 13, 14, and 15 of the through hole 19 is Through hole part 1
3, 14, ₁₅ and the diameter _D2 of these electron beam apertures 13, 14, 15.

A flange 17 is connected to the end edge of the plane part 12 in which the through-hole part 19 is formed via the side wall part 16, and a support piece 18 that is implanted in the bead glass is connected to the flange 17. The overall shape is a shallow dish.

The main electron lens formed in the above-described embodiment is a so-called rotationally asymmetric electrostatic lens, so the diameter is
D ₂ cannot necessarily be applied to the arrangement direction of the electron beam apertures. That is, between the diameter D ₂ in the arrangement direction of _the electron beam apertures in FIG. Alternatively, depending on the low pressure side, the relationship D ₂ D ₃ or D ₂ D ₃ may be appropriately selected and used, or the distance d between the protrusions 20
and the diameter D ₂ of the electron beam apertures 13, 14, 15
It is desirable that there be a certain relationship between

That is, if d is sufficiently small, the through hole 19 will be completely separated into each electron beam hole, resulting in a structure that is almost the same as the conventional electrode structure, the main electron lens diameter will be small, and the mechanical processing accuracy will be reduced. becomes worse.
Also, if d is too large, the difference between the focusing voltage in the direction in which the electron beam holes are arranged and the focusing voltage in the direction perpendicular to this becomes large, making it unsuitable for practical use, so the distance d should be within 60% of the diameter _D2 . It becomes necessary.

Furthermore, as shown in FIG. 5, the protrusion 20 needs to protrude gradually or in a step-like manner toward the main electron lens side, that is, outward, from the plane part 12 in which the through-hole part 19 is formed. This protrusion amount g is the protrusion 2
It is determined by the distance d between 0 and the voltage difference between the electrodes forming the main electron lens. Moreover, instead of providing the protrusion, it is of course possible to provide an auxiliary electrode for controlling the potential distribution from the flange side in the connection region formed by the protrusion. However, in this case, the actual lens diameter may be reduced, so the shape must be carefully considered.

As mentioned above, by mounting the electron gun in the neck of the color picture tube having the electrode structure, it is possible to equivalently increase the diameter of the main electron lens, which is close to a perfect circle, and to make the diameter of the electron beam aperture smaller. Since it is possible to control the focusing voltage in the array direction and the direction perpendicular to this, it has the advantage of improving the characteristics of so-called coma aberration, which not only improves assembly accuracy but also increases the equivalent electron lens diameter. This also has the effect of providing stable characteristics even with variations in assembly.

[Brief explanation of drawings]

FIG. 1 is a top view of a conventional electrode structure, and FIG. 2 is a cross-sectional view of FIG. 1 taken along the line X-X'.
FIG. 3 is a top view of an embodiment of the electrode structure of the present invention;
4 is a cross-sectional view of FIG. 3 taken along line Y-Y', and FIG. 5 is a cross-sectional view of FIG. 3 taken along line Z-Z'. 2, 12...Plane part, 3, 4, 5, 13, 1
4, 15...Electron beam passage portion, 20...Protrusion portion.

Claims (1)

[Scope of utility model registration request] In an electron gun for a color picture tube that emits multiple beams, the electron beam holes provided in the flat part of the electrode constituting the main lens are formed so as to communicate in one direction, and the adjacent holes are formed so as to communicate in one direction. 1. An electron gun for a color picture tube, characterized in that the protruding parts formed between and facing each other gradually or stepwise protrude outward from the flat part toward the tip.