JPH06251721A - Color picture tube device - Google Patents

Abstract

PURPOSE:To provide an equal beam spot diameter throughout the entire region of a screen by reducing the beam spot diameter of the peripheral part in a screen surface, to the same size as that of the central part. CONSTITUTION:A first auxiliary electrode 6 to which a specific focus voltage Vfoc1 is applied, and a second auxiliary electrode 7 to which a voltage Vfoc2 having the focus voltage Vfoc1 and a specific potential difference DELTAV, are provided between an acceleration electrode 3 and a focusing electrode 4. The first auxiliary electrode 6 and the second auxiliary electrode 7 have electron beam passing holes 6a, 6b, 6c and 7a, 7b, 7c, respectively, that form axially symmetric lens electric field, on the points where they are opposed to one another. A dynamic voltage generator 8 is provided on the second auxiliary electrode 7, and the dynamic voltage is increased or lowered so that the potential difference DELTAV is reduced as the deflection angle of the electron beam is increased, to gradually weaken the axial symmetric lens electric field formed between the first auxiliary electrode and the second auxiliary electrode. The incident angle of the electron beam is the same at the peripheral part and the central part of a screen surface.

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 the surface of a phosphor screen.

[0002]

2. Description of the Related Art Conventionally, the most commonly used color picture tube apparatus is, as shown in FIG. 4, cathodes 1a, 1b, 1c,
A control grid electrode 2, an acceleration electrode 3, a focusing electrode 4, and a final acceleration electrode 5 are arranged in this order. The behavior of the electron beam in such a device will be described with reference to FIG. 5. The electron beam 9 emitted from the cathodes 1a, 1b, 1c is a lens electric field generated by the control grid electrode 2 and the acceleration electrode 3.
It is once focused by 10 and crossover 11 occurs. After that, the electron beam diverges, but the acceleration electrode 3 and the focusing electrode 4
The pre-focusing action is generated by the lens electric field 12 generated by, and the strong lensing action is generated by the lens electric field 13 generated by the focusing electrode 4 and the final accelerating electrode 5, so that the fluorescent screen surface 14 is crossed. An image of the over is formed to form a beam spot 15.

[0003]

However, as shown in FIG. 6, the peripheral portion of the screen surface 14 has a longer electron beam trajectory from the electron gun to the screen surface than the central portion, so that the electron beam is incident on the screen surface. The angle decreases from β to β '. Generally, since the incident angle on the screen surface and the lens magnification are in inverse proportion to each other, the lens magnification is larger in the peripheral portion of the screen surface than in the central portion. Since the beam spot formed on the screen surface is an image formed by magnifying the crossover by the lens magnification, as shown in FIG. 7, the beam spot 16 in the peripheral portion of the screen surface is in the central portion. Larger than the beam spot 15 of. This tendency is emphasized as the deflection angle of the color picture tube device increases, and the difference in beam spot diameter between the peripheral portion and the central portion of the screen surface becomes remarkable, and a uniform beam spot is obtained over the entire screen surface. There was a problem of not having.

Therefore, the present invention provides a color picture tube device in which the beam spot diameter in the peripheral portion of the screen surface is made as small as that in the central portion so that a uniform beam spot can be obtained over the entire screen surface. The purpose is to do.

[0005]

To achieve the above object, in the color picture tube device of the present invention, at least an acceleration electrode and a predetermined focus voltage Vfoc1 are applied between the control grid electrode and the final acceleration electrode. A first auxiliary electrode, a second auxiliary electrode to which a voltage Vfoc2 having a predetermined potential difference ΔV from the focus voltage Vfoc1 is applied, and the focus voltage V
Focusing electrodes to which foc1 is applied are arranged in this order, and the first auxiliary electrode and the second auxiliary electrode have electron beam passage holes that generate an axisymmetric lens electric field at positions facing each other, and As the deflection angle increases, the dynamic voltage gradually increasing or decreasing from the voltage Vfoc2 is applied to the second auxiliary so as to gradually weaken the axisymmetric lens electric field generated between the first auxiliary electrode and the second auxiliary electrode. A means for applying the voltage to the electrodes to reduce the potential difference ΔV is provided.

[0006]

According to the above construction, the axis generated between the first auxiliary electrode and the second auxiliary electrode by applying the dynamic voltage that increases or decreases with the increase of the deflection angle to the second auxiliary electrode. The focusing action of the symmetric lens electric field is weakened.
Therefore, the electron beam is spread in the peripheral portion of the screen surface and the incident angle on the screen surface becomes large, and therefore,
Since the lens magnification is reduced, the beam spot diameter can be reduced. By such an action, the spot diameter of the peripheral portion on the screen surface can be made as small as that of the central portion.

[0007]

Embodiments will be described in detail below with reference to the drawings. FIG. 1 shows a color picture tube device according to an embodiment of the present invention, in which three cathodes 1a, 1 are arranged in a horizontal straight line.
b and 1c are the control grid electrode 2, acceleration electrode 3, first auxiliary electrode 6, second auxiliary electrode 7, focusing electrode 4 and final acceleration electrode 5.
Together with it, it constitutes an in-line type electron gun. Also, the first
Circular electron beam passage holes 6a, 6b, 6c and 7a, 7b, 7c, for example, as shown in FIG. 2, are provided at positions where the auxiliary electrode 6 and the second auxiliary electrode 7 face each other. Generate a symmetric lens field.

Since the first auxiliary electrode 6 is connected to the focusing electrode 4, a predetermined focus voltage Vfoc1 is applied. When the electron beam is not deflected, the voltage Vfoc2 lower than the focus voltage Vfoc1 by a predetermined voltage ΔV is applied to the second auxiliary electrode 7.
Takes. Therefore, due to this potential difference, the first auxiliary electrode 6
An axisymmetric lens electric field is generated between the second auxiliary electrode 7 and the second auxiliary electrode 7. A dynamic voltage generator 8 is connected to the second auxiliary electrode 7, and when the electron beam is deflected, a dynamic voltage gradually increasing from Vfoc2 is applied to the second auxiliary electrode 7 as the deflection angle increases. At this time,
Since the potential difference between the first auxiliary electrode 6 and the second auxiliary electrode 7 is smaller than ΔV, the axisymmetric lens electric field between both electrodes becomes weak.

The behavior of the electron beam due to such a lens electric field will be described with reference to FIG. 3. FIG. 3A shows the case where the electron beam is not deflected, and FIG. 3B shows the case where the electron beam is deflected. 17 is an axially symmetric lens electric field generated by the acceleration electrode 3 and the first auxiliary electrode 6, and 18 of the axially symmetric lens electric field generated by the first auxiliary electrode 6 and the second auxiliary electrode 7 is deflected. A non-axially symmetric lens electric field is shown, and 19 is a deflecting axially symmetric lens electric field.

An angle α from the crossover 11 to the central axis
The electron beam emitted at 1 is first focused by the axially symmetric lens electric field (convex lens) 17, and then by the axially symmetric lens electric field (convex lens) 18 or 19. At this time, the axially symmetric lens electric field 19 is weaker than the axially symmetric lens electric field 18, so that the electron beam when deflected is wider than that when not deflected. By such an action, it is possible to cancel the effect of reducing the incident angle on the screen surface due to the long distance from the electron gun to the screen surface 14 at the time of deflection, and the incident angle on the screen surface at the time of deflection can be It can be expanded to the same degree as the angle β when not deflected from β ′. That is, the peripheral portion and the central portion of the screen surface have the same incident angle to the screen surface and the same lens magnification, so that the beam spot diameters can be the same.

In the above, the case where a voltage Vfoc2 which is lower than the focus voltage Vfoc1 by a predetermined voltage .DELTA.V is applied to the second auxiliary electrode 7 when not deflected, and a dynamic voltage which gradually increases from Vfoc2 is applied when deflected is described. However, the same explanation applies when the second auxiliary electrode is applied with a voltage Vfoc2 that is higher than the focus voltage Vfoc1 by a predetermined voltage ΔV when not deflected and with a dynamic voltage that gradually decreases from Vfoc2 when deflected.

[0012]

As described above, according to the present invention,
It is possible to eliminate the difference in beam spot diameter between the peripheral portion and the central portion on the screen surface, which becomes remarkable as the deflection angle increases, and realize a uniform beam spot over the entire fluorescent screen surface. be able to.

[Brief description of drawings]

FIG. 1 is a sectional view of an electron gun of a color picture tube device according to an embodiment of the present invention.

FIG. 2 is a view showing electron beam passage holes of a first auxiliary electrode and a second auxiliary electrode in the same example.

FIG. 3 is a diagram showing an action of an axially symmetric lens electric field in a case where the electron beam is not deflected (a) and a case where the electron beam is deflected (b) in the embodiment.

FIG. 4 is a sectional view of an electron gun of a conventional color picture tube device.

FIG. 5 is a diagram showing an action of an axially symmetric lens electric field in the conventional example.

FIG. 6 is a diagram showing a difference in incident angle between a central portion and a peripheral portion of a screen surface in a conventional example.

FIG. 7 is a diagram showing a beam spot diameter according to a difference in incident angle.

[Explanation of symbols]

1a, 1b, 1c ... Cathode, 2 ... Control grid electrode, 3
... Accelerating electrode, 4 ... Focusing electrode, 5 ... Final accelerating electrode,
6 ... 1st auxiliary electrode, 7 ... 2nd auxiliary electrode, 8 ...
Dynamic voltage generator.

Claims (1)

[Claims] 1. Between the control grid electrode and the final accelerating electrode,
At least an accelerating electrode, a first auxiliary electrode to which a predetermined focus voltage Vfoc1 is applied, a second auxiliary electrode to which a voltage Vfoc2 having a predetermined potential difference ΔV from the focus voltage Vfoc1 is applied, and a focusing to which the focus voltage Vfoc1 is applied. Electrodes are arranged in this order, and the first auxiliary electrode and the second auxiliary electrode have electron beam passage holes that generate an axially symmetric lens electric field at positions facing each other, and increase the deflection angle of the electron beam. Accordingly, a dynamic voltage gradually increasing or decreasing from the voltage Vfoc2 is applied to the second auxiliary electrode so as to gradually weaken the axisymmetric lens electric field generated between the first auxiliary electrode and the second auxiliary electrode. And a means for reducing the potential difference ΔV by applying to the color picture tube device.