JPH06162958A - Color cathode-ray tube device - Google Patents

Abstract

PURPOSE:To enable high resolution to be obtained over the whole area of a phosphor screen. CONSTITUTION:The first constant focusing voltage is applied to the first focusing electrode 3 and the third focusing electrode 6, while the second focusing voltage higher than the first focusing voltage and giving a gradual rise according to an increase in the deflection angle of an electron beam, is applied to the second focusing electrode 5 and the fourth focusing electrode 7. The first electrical field of an axially asymmetrical lens divergent in a horizontal direction but convergent in a vertical direction is generated between the second focusing electrode 5 and the third focusing electrode 6, while the second electrical field of an axially asymmetrical lens convergent in a horizontal direction but divergent in a vertical direction is generated between the third focusing electrode 6 and the fourth focusing electrode 7. In addition, the third electrical field of an axially asymmetrical lens for weakening a focusing effect in a horizontal direction and intensifying the effect in a vertical direction is generated between the fourth focusing electrode 7 and a final accelerating electrode 8. Furthermore, when a horizontal focusing effect due to all of the first, second and third electrical field of an axially asymmetrical lens is kept at A, and the focusing effect in a vertical direction is kept at B, the values of A and B are made approximately equal to each other with the deflection angle of an electron beam kept at zero. Also, a relationship of A>B is established, as the deflection angle increases. As a result, the spherical aberration of a main lens in a horizontal direction becomes small and high resolution characteristics can be provided, even when a large amount of beam current flows.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube device constructed so that a high resolution can be obtained over the entire surface of a phosphor screen.

[0002]

2. Description of the Related Art The resolution of a color picture tube device largely depends on the size and shape of the beam spot. That is, good resolution characteristics cannot be obtained unless the beam spot generated on the phosphor screen surface by the electron beam impingement has a small diameter and is close to a perfect circle.

In a color picture tube in which three electron beam radiating parts are arranged in a straight line in a horizontal direction, the horizontal deflection magnetic field is pincushion-shaped in order to form a self-convergence structure.
Then, the vertical deflection magnetic field is distorted in a barrel shape. For this reason, the three electron beams passing through the deflection magnetic field are subjected to a diverging action in the horizontal direction and a focusing action in the vertical direction, respectively, and have a horizontally long flat cross-sectional shape with the long axis in the horizontal direction.

Generally, as the deflection angle of the electron beam increases, the trajectory of the electron beam becomes longer and the beam spot becomes overfocused. However, since this is canceled by the divergence effect, the beam spot is kept in the optimum focus state in the horizontal direction during the entire deflection period. However, since the focusing action is added in the vertical direction, the degree of overfocus increases, resulting in a long haze portion in the beam spot, resulting in a reduction in resolution.

[0005]

This problem has been considerably improved by the invention described in Japanese Patent Application Laid-Open No. 3-95835 filed by the present applicant. However, since the three main lens electric fields generated between the final focusing electrode and the final accelerating electrode are arranged inline in the horizontal direction, it is difficult to increase the horizontal diameter even if the vertical diameter can be set large. The electron beam passing through the electric fields of the two main lenses tends to have a horizontally long cross-sectional shape. Therefore, the spherical aberration in the horizontal direction becomes large, and the resolution is deteriorated, especially at a large beam current.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an acceleration electrode, a flat plate-shaped first focusing electrode, and a flat plate-shaped first electrode are provided between a control grid electrode and a final acceleration electrode. The second focusing electrode, the third focusing electrode connected to the first focusing electrode, and the fourth focusing electrode connected to the second focusing electrode are sequentially arranged. Then, a constant first focus voltage is applied to the first focusing electrode and the third focusing electrode, while the second focusing electrode and the fourth focusing electrode are higher than the first focusing voltage and the deflection angle of the electron beam is By applying a second focus voltage that gradually increases with an increase, a first axially asymmetric lens electric field that is divergent in the horizontal direction and convergent in the vertical direction is applied between the second focusing electrode and the third focusing electrode. To generate a second axially asymmetric lens electric field, which is horizontally focused and divergent in the vertical direction, between the third focusing electrode and the fourth focusing electrode to weaken the horizontal focusing action. Third to enhance vertical focusing action
An axially asymmetric lens electric field is generated between the fourth focusing electrode and the final accelerating electrode. When the horizontal focusing action by all of the first, second and third axial asymmetric lens electric fields is A and the vertical focusing action is B, A≈B when the deflection angle of the electron beam is 0, As the deflection angle increases, A> B.

[0007]

In such a structure, the horizontal lens action of the main lens is weakened, so that the horizontal spherical aberration can be reduced. Further, since the spherical aberration of the axially asymmetric lens electric field is smaller than that of the axially symmetric lens, it is possible to reduce the horizontal aberration of the synthetic lens that combines the lens action at each stage, and thus the electron beam passing through the main lens electric field is reduced. Even if it has a laterally long cross-sectional shape, horizontal spherical aberration can be reduced.

[0008]

The present invention will be described below with reference to the illustrated embodiments. As shown in FIG. 1, the three cathodes 1a, 1b, 1c arranged inline on a horizontal straight line include a control grid electrode 2, an acceleration electrode 3, a plate-shaped first focusing electrode 4, and a plate-shaped second focusing. The electrode 5, the third focusing electrode 6 connected to the first focusing electrode 4, the fourth focusing electrode 7 connected to the second focusing electrode 5, and the final accelerating electrode 8 constitute an in-line type electron gun.

As shown in FIG. 2, the first focusing electrode 4 has circular electron beam passage holes 4a, 4b and 4c, and the second focusing electrode 5 has a rectangular or oval shape with a long axis in the vertical direction. The electron beam passage holes 5a, 5b, 5c are provided on the end surface on the third focusing electrode 6 side. The third focusing electrode 6 has a rectangular or elliptical electron beam passage hole 6 having a long axis in the horizontal direction.
a, 6b, 6c on the end face on the second focusing electrode 5 side,
The end surface on the side of the focusing electrode 7 has rectangular or elliptical electron beam passage holes 6d, 6e, and 6f having a long axis in the vertical direction. Further, the fourth focusing electrode 7 is a rectangular or elliptical electron beam passage hole 7a, 7b, which has a long axis in the horizontal direction,
7c on the end face on the third focusing electrode 6 side, and the final accelerating electrode 8
The electron beam passage hole 7 for generating the electric field of the main lens is formed on the side end surface.
It has d, 7e, and 7f. And the final acceleration electrode 8
Has electron beam passage holes 8a, 8b, 8c for generating the electric field of the main lens on the end surface on the side of the fourth focusing electrode 7.

A constant first focus voltage V1 is applied to the first focusing electrode 4 and the third focusing electrode 6, and the second focusing electrode 5 and the fourth focusing electrode 7 are 400V to 2000V higher than the first focusing voltage V1. A second focus voltage (dynamic voltage) V2 that gradually increases as the deflection angle of the electron beam gradually increases from 0 is applied.

The lens electric field generated between the second focusing electrode 5 and the third focusing electrode 6 is divergent in the horizontal direction.
Then, in the vertical direction, it becomes a focusing type axially asymmetrical one (quadrupole electric field). In addition, the lens electric field generated between the third focusing electrode and the fourth focusing electrode is a focusing type in the horizontal direction and a diverging type in the vertical direction (quadrupole electric field). Then, the lens electric field generated between the fourth focusing electrode 7 and the final accelerating electrode 8 is axially asymmetric, which weakens the horizontal focusing action and strengthens the vertical focusing action.

The behavior of the electron beam in such an electron lens system will be described with reference to FIGS. 3 to 6. FIG. 3 is a horizontal cross section when the deflection angle of the electron beam is 0, and FIG. 4 is a vertical cross section in the same state. Each cross section is shown. In the horizontal cross section from the crossover portion 9 to the phosphor screen 10, the diverging lens electric field 11, the focusing lens electric field 12, and the weak focusing lens electric field 13 which is the main lens.
Are lined up. In the vertical section, the focusing lens electric field 1
4, the diverging lens electric field 15 and the strong focusing lens electric field 16 as the main lens are arranged. However, the lens electric fields 11 and 14 are generated by the potential difference between the second and third focusing electrodes, and the lens electric fields 13 and 16 are generated by the potential difference between the third and fourth focusing electrodes.

The electron beam 17 from the crossover section 9
First, the diverging lens electric field 11 and the focusing lens electric field 1
The lens functions of 4 are divergent in the horizontal direction and focused in the vertical direction. Then, the focusing lens electric field 12 and the diverging lens electric field 15 respectively exert a focusing lens action in the horizontal direction and a diverging lens action in the vertical direction. Further, since the main lens receives a relatively weak focusing action in the horizontal direction and a relatively strong focusing action in the vertical direction, the electron beam on the phosphor screen 10 is just focused in both the horizontal and vertical directions. At this time, the spherical aberration generated in the main lens is smaller in the horizontal direction where the focusing action is weaker than in the vertical direction.

FIGS. 5 and 6 show a horizontal cross section and a vertical cross section when the electron beam is deflected in the horizontal direction, respectively, and the lens action by the lens electric fields 11, 14 and the lens electric fields 13, 16 is shown in FIG. And becomes stronger than the lens action shown in FIG. Therefore, both the horizontal lens magnetic field 17 and the vertical lens magnetic field 18, which act on the electron beam passing through the deflection magnetic field, can be canceled out, and the cross-sectional shape of the electron beam entering the main lens can be made close to a perfect circle. Since the focusing action in the horizontal direction of the main lens is smaller than the focusing action in the vertical direction, the spherical aberration can be kept small. Although the case where the electron beam is deflected in the horizontal direction has been described above, the same effect as described above can be obtained when the electron beam is deflected in the vertical direction.

[0015]

As described above, according to the present invention, since the horizontal spherical aberration of the main lens can be reduced, good resolution characteristics can be obtained even at a large beam current.

[Brief description of drawings]

FIG. 1 is a diagram showing an electrode array of an electron gun of a color picture tube device embodying the present invention.

FIG. 2 is a view mainly showing an electron beam passage hole of an electrode forming the electron gun.

FIG. 3 is a horizontal cross-sectional view for explaining the behavior of the electron beam when the deflection angle of the electron beam is 0.

FIG. 4 is a vertical cross-sectional view for explaining the behavior of the electron beam when the deflection angle of the electron beam is 0.

FIG. 5 is a horizontal sectional view for explaining the behavior of the electron beam when the electron beam is deflected in the horizontal direction.

FIG. 6 is a vertical cross-sectional view for explaining the behavior of the electron beam when the electron beam is deflected in the horizontal direction.

[Explanation of symbols]

 2 control grid electrode 3 acceleration electrode 4 first focusing electrode 5 second focusing electrode 6 third focusing electrode 7 fourth focusing electrode 8 final accelerating electrode

Claims (1)

[Claims] 1. An acceleration electrode, a flat plate-shaped first focusing electrode, a flat plate-shaped second focusing electrode, between a control grid electrode and a final acceleration electrode,
A third focusing electrode connected to the first focusing electrode and a fourth focusing electrode connected to the second focusing electrode are sequentially arranged, and a constant first focus voltage is applied to the first focusing electrode and the third focusing electrode. On the other hand, a second focus voltage that is higher than the first focus voltage and that gradually increases with the increase of the deflection angle of the electron beam is applied to the second focusing electrode and the fourth focusing electrode, and the second focusing voltage is divergent in the horizontal direction. A first axially asymmetric lens field that is vertically focused and between a second focusing electrode and a third focusing electrode that is horizontally focused and divergent in the vertical direction. A second axially asymmetric lens electric field is generated between the third focusing electrode and the fourth focusing electrode to weaken the horizontal focusing action and strengthen the vertical focusing action. And the final Yielding between the fast electrode, and,
When the horizontal focusing effect due to all of the first, second and third axial asymmetric lens electric fields is A and the vertical focusing effect is B, A≈B when the deflection angle of the electron beam is 0,
A color picture tube device, wherein A> B is satisfied as the deflection angle increases.