JPH03102743A - Color picture tube device - Google Patents

Abstract

PURPOSE:To prevent a change of the lens work with a prefocus lens according to the deflection of electron beams by respectively providing an axial asymmetric electron beam passing hole in a first- a third focusing electrodes. CONSTITUTION:A focusing electrode system 17 between an acceleration electrode 16 and an anode 15 consists of a first focusing electrode 18, a second focusing electrode 18 and a third focusing electrode 20. The first and the third focusing electrodes 18, 20 of both sides, to which the constant focusing voltage is applied, respectively have an axial asymmetric electron beam passing hole on the surface facing to the second focusing electrode 19 in the intermediate position between them, and the dynamic voltage gradually falling and rising from the focusing voltage thereof with the increase of the beam deflecting quantity is applied to the second focusing electrode 19. At this stage, an axial asymmetric electron beam passing hole is provided in the second focusing electrode 19. As a result, the axial asymmetric focusing work against the electron beam is performed in the focusing electrode systems 18-20. A change of a beam orbit directing from the acceleration electrode system to the prefocus lens in response to the beam deflecting quantity can thereby be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a color picture tube device configured to provide good resolution over the entire area of a phosphor screen.

l Conventional technology In general, the deflection yoke for the self-convergence system attached to a color picture tube equipped with an in-line electron gun is
Generates a horizontal deflection magnetic field distorted like a bottle cushion and a vertical deflection magnetic field distorted like a barrel. The cross-sectional shape of the electron beam passing through such horizontal and vertical deflection magnetic fields is distorted as the amount of beam deflection increases, so that the beam is produced at the center of the phosphor screen surface l, as shown in FIG. While spot 2 is a perfect circle, the phosphor screen surface l
The beam spot 3 generated at the periphery has a shape in which a horizontally long elliptical high-brightness core part 4 is accompanied by a vertically long low-brightness haze part 5, and the beam spot 3 has a shape that is particularly high in the peripheral part. you won't be able to get it.

In the invention disclosed in Japanese Patent Publication No. 59-53656, as shown in FIG. The electron beam passing hole 10a, 10b of the central second grid electrode 10 is composed of a third grid electrode 9, 10.11. 1
0c is made non-circular. Then, a dynamic voltage that gradually decreases or increases from a constant acceleration voltage Vx2 as the amount of deflection of the electron beam increases is applied to the second grid electrode 1.
When the accelerating electrode system 8 as described above is arranged by applying a voltage of 0 to , will be formed between the third grid electrode 11 and the focusing electrode 7. Moreover,
As the amount of deflection increases, the electron beam is subjected to an axially asymmetric focusing/diverging action within the accelerating electrode system 8, so that the trajectory of incidence on the brifocus lens constantly changes. In other words, yellowtail 7 inches. There was a problem in that the lens action of the one-piece lens changed as the electron beam was deflected. Note that 12, 13, and 14 in the figure indicate the cathode, and 15 indicates the final acceleration electrode (anode).

According to the invention, a focusing electrode system arranged between the accelerating electrode and the anode consists of a first focusing electrode, a second focusing electrode and a third focusing electrode. The first and third focusing electrodes on both sides to which a constant focusing voltage is applied each have an axially asymmetrical electron beam passing hole on the surface facing the second focusing electrode located at an intermediate position between them, and the beam A dynamic voltage that gradually decreases or increases from the focusing voltage as the amount of deflection increases is applied to the second focusing electrode. It is configured to have holes.

Effect: With this configuration, the axially asymmetric focusing action on the electron beam is performed by the focusing electrode system, so the beam trajectory from the accelerating electrode system to the prefocus lens does not change depending on the amount of beam deflection. . In addition, since the length of the accelerating electrode system in the tube axis direction is short and small, the electron beam does not cross over twice on the axis when the beam current is low, so good resolution can be obtained over the entire area of the phosphor screen surface. be able to.

Example 1 shows an electron gun for a color picture tube device embodying the present invention.
In the figure, three cathodes 12, 13, and 14 arranged in-line on a horizontal straight line constitute an in-line electron gun together with a control grid electrode 6, a flat accelerating electrode 16, a focusing electrode system 17, and an anode 15. The focusing electrode system 17
are plate-shaped first and second focusing electrodes 18, 19 and a box-shaped third focusing electrode arranged sequentially along the electron beam path.
It consists of a focusing electrode 20. 2 1 a + 2
-1 b *21c indicates the main lens. As shown in FIG. 2, the first focusing electrode 18 has three
circular electron beam passing holes 18a. 18b, 18C, and three oblong rectangular electron beam passing holes 18d, 18e. 18f each. In addition, the second focusing electrode l9 in the center
are three vertically elongated rectangular electron beam passing holes 1 9 a ,
1 9 b + 1 9 c and the third focusing electrode 2
0 are three oblong rectangular electron beam passing holes 20a. 20
b, 20c. A constant focusing voltage Vfoc is applied to the first and third focusing electrodes 18.20, and a constant focusing voltage Vfoc is applied to the second focusing electrode 19, which increases or decreases from the focusing voltage Vfoc as the amount of deflection of the electron beam increases. A dynamic voltage is applied. In other words, the dynamic voltage is the focusing voltage V fo when the beam deflection amount is zero and the beam spot appears at the center of the phosphor screen surface.
It takes the same value as c, and gradually decreases or increases from the focusing voltage Vfoe as the deflection current increases. Therefore, when the beam spot appears at the center of the phosphor screen surface, the first to third focusing electrodes 18, 19, 20
are all at the same potential Vfoc, and these focusing electrodes 18
.about.20, the lens electric field is not activated. That is, each electron beam passing hole 18d. of the first to third focusing electrodes 18-20. 1 8 e. 1 8 f.
19 a. 1 9b, 19c, 20a, 20b
．． Although 20c is non-circular, an axially asymmetric electric field is not generated, and the electron beam generates a nearly perfectly circular beam spot at the center of the phosphor screen surface.

On the other hand, flI! When the dynamic voltage decreases or increases from Vfoc as the direction current increases, that is, the amount of beam deflection increases, the first and third focusing electrodes 18,20 to which a constant focusing voltage Vfoc is applied, and the second focusing electrode 18. An axially asymmetrical lens electric field is generated between the lens and the electrode 19 .

This lens electric field is applied to the first to third focusing electrodes 18 to 20.
Each electron beam passing hole 18d. 18e, 18f. 19a
, 19b. 19c. 20a, 20b. Since 20c is axially asymmetric, it gives an axially asymmetrical focusing effect to the three electron beams passing through them.

Each electron beam passing hole 18d of the first and third focusing electrodes 18.20. 18e, 18f, 19a, 19b. 19c
are both horizontally long rectangles, and the electron beam passing holes 19a . 19b. When 19c is a vertically elongated rectangle, the lens electric field provides a strong focusing effect in the vertical direction and a weak focusing effect in the horizontal direction on the electron beam passing through it, in response to changes in the dynamic voltage. As a result, the focusing electrode system 17
Immediately after exiting the electron beam, the electron beam has an elliptical cross-sectional shape long in the horizontal direction and passes through the main lens portion 2 1 a.
, 2 l b + 2 1 c.

Note that even when the electron beam passage holes of the first and third focusing electrodes 18 and 20 are vertically long rectangles and the electron beam passage holes of the second focusing electrode 19 are horizontally long rectangles, the change in dynamic voltage causes The same lens effect as described above can be obtained.

Due to spherical aberration, the refractive index of the part of the electron beam that passes through the peripheral edge of the lens is larger than the refractive index of the part of the electron beam that passes near the center of the lens. Therefore, as shown in FIG. 3, when the electron beam 22 with a horizontally long elliptical cross section is incident on the main lens portion 2l, the vertical focus point 23 on the outer circumference of the electron beam is changed to the horizontal focus point 24.
occurs at a point farther away than

In this way, when the cross-sectional shape of the electron beam that has passed through the focusing electrode system is distorted into a long ellipse in the horizontal direction as the amount of beam deflection increases, refraction of the outer peripheral portion of the electron beam, which greatly affects the deflection aberration, occurs. The ratio is larger in the horizontal direction than in the vertical direction. This phenomenon is caused by the effect that the electron beam undergoes within the self-convergent deflection magnetic field, that is,
This cancels out the phenomenon that the focusing effect in the horizontal direction is weakened and the focusing effect in the vertical direction is strengthened. Therefore, even though the beam spot is caused by an electron beam that is largely deflected in the horizontal direction, it can be made close to a perfect circle, and the resolution in the peripheral area of the phosphor screen surface can be made good. Very clear images can be obtained over the entire area.

In addition, the focusing electrode system is configured with first to third focusing electrodes, and a dynamic voltage is applied to the second focusing electrode in the center,
Applying a constant focusing voltage to the first and third focusing electrodes may not change the pre-focusing lens generated between the accelerating electrode and the first focusing electrode.
Although the embodiment has been described in which the main lens generated between the third focusing electrode and the anode is not changed and is applied to extremely stable operation, the purpose of the present invention is to The point is to correct the distortion of the beam spot by the electron beam deflected within the deflection magnetic field at the periphery of the phosphor screen surface, and the same applies to picture tube devices that operate with one or two beams. Applicable to

[Brief explanation of drawings]

FIG. 1 is a side cross-sectional view of an electron gun of a color picture tube device embodying the present invention, FIG. 2 is a partially cutaway i'l view of an electrode constituting the focusing electrode system of the electron gun, and FIG. A diagram for explaining the refraction state of the outer circumferential part of the electron beam with a horizontally elongated elliptical cross section at the main lens part. Figure 4 schematically shows the shape distortion of the beam spot generated on the phosphor screen surface of the device. Figure 5 is a diagram schematically showing the distortion of the beam spot shape due to the self-convergence method (Fa-directed magnetic field).
FIG. 6 is a side sectional view of an electron gun of a conventional color picture tube device. 12,13.14...Cathode, l6...
Accelerating electrode, l7... Focusing electrode system, l8...
...first focusing electrode, 19...second focusing electrode, 2o...third focusing electrode.

Claims (1)

[Claims] A focusing electrode system disposed between the accelerating electrode and the anode is a first
a focusing electrode, a second focusing electrode, and a third focusing electrode, and a constant focusing voltage is applied to the first and third focusing electrodes on both sides, and the second focusing electrode is located at an intermediate position between them. The second focusing electrodes each have an axially asymmetrical electron beam passage hole on opposing surfaces, and to which a dynamic voltage that gradually decreases or increases from the focusing voltage as the amount of beam deflection increases is also axially asymmetrical. A color picture tube device characterized in that it has an electron beam passage hole.