JP3040269B2 - Color picture tube equipment - Google Patents

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 area 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 a beam spot. That is, good resolution characteristics cannot be obtained unless the beam spot generated on the phosphor screen surface by the bombardment of the electron beam is small in diameter and close to a perfect circle.

In a color picture tube in which three electron beam radiating portions are arranged in a horizontal straight line, a horizontal deflection magnetic field is formed into a pincushion shape in order to form a self-convergence structure.
The vertical deflection magnetic field is distorted in a barrel shape. As a result, the three electron beams passing through the deflecting magnetic field undergo a diverging action in the horizontal direction and a focusing action in the vertical direction, resulting in a horizontally oblong cross-sectional shape having a 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 out by the diverging effect, the beam spot is kept in the optimum focus state in the horizontal direction throughout the entire deflection period. However, in the vertical direction, since the above-mentioned focusing action is added, the degree of overfocus is increased, and the beam spot is accompanied by a long haze portion, and the resolution is reduced.

[0005]

This problem can be 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 in-line in the horizontal direction, even if the vertical diameter can be set large, the horizontal diameter is difficult to increase. An electron beam passing through two main lens electric fields tends to have a horizontally long cross-sectional shape. For this reason, the horizontal spherical aberration becomes large, and the resolution at the time of a large beam current is rather lowered.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and comprises an acceleration electrode, a plate-shaped first focusing electrode, and a plate-shaped first focusing electrode between a control grid electrode and a final acceleration electrode. A second focusing 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. Then, while applying a constant first focus voltage to the first focusing electrode and the third focusing electrode, the second focusing electrode and the fourth focusing electrode are higher than the first focusing voltage and have a deflection angle of the electron beam. A second focus voltage, which gradually increases with the increase, is applied, and a first axially asymmetric lens electric field of a divergent type in the horizontal direction and a convergent type in the vertical direction is applied between the second focusing electrode and the third focusing electrode. A second axially asymmetric lens electric field that is horizontally focused and divergent in the vertical direction between the third focusing electrode and the fourth focusing electrode, thereby weakening the horizontal focusing action. To enhance vertical focusing
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 axially asymmetric lens electric fields is A and the vertical focusing action is B, A ≒ B when the electron beam deflection angle is 0, A> B is established as the deflection angle increases.

[0007]

With this configuration, the horizontal lens function of the main lens is weakened, so that the horizontal spherical aberration can be reduced. In addition, since the spherical aberration of the axially asymmetric lens electric field is smaller than that of the axially symmetric lens, the horizontal aberration of the combined lens obtained by combining the lens actions at each stage can be reduced, and therefore, the electron beam passing through the main lens electric field can Even if it has a horizontally long cross-sectional shape, horizontal spherical aberration can be reduced.

[0008]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. As shown in FIG. 1, three cathodes 1a, 1b, 1c arranged in a horizontal straight line include a control grid electrode 2, an acceleration electrode 3, a first plate-shaped focusing electrode 4, and a plate-shaped second focusing electrode. 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, 4c, and the second focusing electrode 5 has a rectangular or oval shape having a long axis in the vertical direction. Electron beam passage holes 5a, 5b, 5c are provided on the end face on the third focusing electrode 6 side. The third focusing electrode 6 has a rectangular or elliptical electron beam passage hole 6 having a major axis in the horizontal direction.
a, 6b, 6c on the end face on the side of the second focusing electrode 5;
The end surface on the side of the focusing electrode 7 has rectangular or oblong electron beam passage holes 6d, 6e, and 6f having a long axis in the vertical direction. Further, the fourth focusing electrode 7 has a rectangular or oval electron beam passage hole 7a, 7b,
7c on the end face on the third focusing electrode 6 side, and the final accelerating electrode 8
An electron beam passing hole 7 for generating a main lens electric field
d, 7e and 7f. And the final accelerating electrode 8
Have electron beam passage holes 8a, 8b, 8c for generating a main lens electric field on the end face on the fourth focusing electrode 7 side.

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 higher by 400 V to 2000V than the first focusing voltage V1. In addition, a second focus voltage (dynamic voltage) V2 which 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 has a diverging type in the horizontal direction.
Then, in the vertical direction, it becomes a convergent axially asymmetric (quadrupole electric field). Further, the lens electric field generated between the third focusing electrode and the fourth focusing electrode is axially asymmetric (quadrupole electric field) of a focusing type in the horizontal direction and a diverging type in the vertical direction. Then, the lens electric field generated between the fourth focusing electrode 7 and the final accelerating electrode 8 becomes axially asymmetric, which weakens the horizontal focusing action and strengthens the vertical focusing action.

The behavior of an electron beam in such an electron lens system will be described with reference to FIGS. 3 to 6. FIG. 3 is a horizontal sectional view when the deflection angle of the electron beam is 0, and FIG. Each section is shown. In a horizontal section from the crossover section 9 to the phosphor screen 10, a diverging lens electric field 11, a focusing lens electric field 12, and a weak focusing lens electric field 13 serving as a main lens.
Are lined up. In the vertical section, the focusing lens electric field 1
4. A diverging lens electric field 15 and a strong focusing lens electric field 16 serving as a main lens are arranged. However, the lens electric fields 11, 14 are generated by the potential difference between the second and third focusing electrodes, and the lens electric fields 13, 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
4 causes the lenses to be divergent in the horizontal direction and convergent in the vertical direction. The focusing lens field 12 and the diverging lens field 15 then undergo a horizontal focusing and a vertical diverging lens action. Furthermore, 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 in just focus in both the horizontal and vertical directions. At this time, the spherical aberration generated by 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 section and a vertical section, respectively, when the electron beam is deflected in the horizontal direction. The lens action by the lens electric fields 11 and 14 and the lens electric fields 13 and 16 is shown in FIG. 4 and the lens action shown in FIG. Therefore, both the horizontal lens magnetic field 17 and the vertical lens magnetic field 18 acting on the electron beam passing through the deflection magnetic field can be offset, and the cross-sectional shape of the electron beam entering the main lens can be made closer to a perfect circle. Since the horizontal focusing action of the main lens is smaller than the vertical focusing action, 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 operation 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, the horizontal spherical aberration of the main lens can be reduced, so that good resolution characteristics can be obtained even at a large beam current.

[Brief description of the drawings]

FIG. 1 is a diagram showing an electrode arrangement 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 constituting 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 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 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 acceleration electrode

Claims (1)

(57) [Claims] An accelerating electrode, a plate-shaped first focusing electrode, a plate-shaped second focusing electrode between a control grid electrode and a final accelerating 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 higher than the first focus voltage and gradually increasing with an increase in the deflection angle of the electron beam is applied to the second focusing electrode and the fourth focusing electrode, and the diverging type is applied in the horizontal direction. A first axially asymmetric lens field, which is of a focusing type in the vertical direction, is generated between the second and third focusing electrodes, and which is of a focusing type in the horizontal direction and a diverging type in the vertical direction. A second axially asymmetric lens electric field is generated between the third focusing electrode and the fourth focusing electrode to reduce the horizontal focusing action and enhance the vertical focusing action. And the final Yielding between the fast electrode, and,
When the horizontal focusing action by all of the first, second and third axially asymmetric lens electric fields is A, and the vertical focusing action is B, A ≒ B when the electron beam deflection angle is 0,
A color picture tube device wherein A> B is established as the deflection angle increases.