KR0177134B1 - Electron gun for color cathode ray tube - Google Patents

Abstract

The present invention discloses an electron gun for a color cathode ray tube.

The present invention relates to an electron gun for a color cathode ray tube comprising a cathode, a control electrode, and a screen electrode forming an anterior triode, and first, second, third, and four focus electrodes and an final acceleration electrode forming an auxiliary and main lens system. An elongated electron beam through hole is formed on the emission side of the first and third focus electrodes, a focus voltage is applied to the first and third focus electrodes, and the focus voltage is applied to the second auxiliary electrode and the fourth focus electrode. It is characterized by applying a dynamic focus voltage in synchronization with the deflection signal as a base voltage, which has the advantage of obtaining a uniform electron beam cross section in the entire fluorescent film.

Description

Electron gun for colored cathode ray tube

1 is a view showing the state in which the electron beam is landing on the fluorescent film.

2 is a sectional view showing a conventional electron gun for a cathode ray tube, showing a method of applying a voltage to each electrode.

FIG. 3 is a sectional view showing an electron gun for a color cathode ray tube according to the present invention, showing a voltage application method.

4 is a perspective view showing the emission side of the second and fourth focus electrodes.

5 and 6 are diagrams showing a state in which the electron beam is elongated while passing through the quadrupole lens.

* Explanation of symbols for main parts of the drawings

21: cathode 22: control electrode

23: screen electrode 24: first focus electrode

25: second focus electrode 26: third focus electrode

27: fourth focus electrode 28: final acceleration electrode

VD: Dynamic Focus Voltage VF: Focus Voltage

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to an electron gun for a color cathode ray tube that can compensate for the distortion of an electron beam due to an uneven magnetic field caused by a deflection yoke.

In general, a cathode ray tube forms an pixel by electron beams emitted from an electron gun enclosed in a neck portion of which are selectively deflected according to a deflection yoke and landed on a fluorescent film formed on an inner surface of the panel. Gather together to form an image. Therefore, in order to form a clearer image, it is important to ensure that the electron beam emitted from the electron gun is accurately landed on the fluorescent point of the fluorescent film.

In the cathode ray tube, when the electron beam emitted from the electron gun is deflected by the deflection yoke and is deflected toward the periphery of the fluorescent film, the uneven deflection magnetic field of the deflection yoke is affected, and the inner surface of the panel is fluorescence due to the geometric curvature. The electron beam spot landing on the film is distorted as shown in FIG. 1, which causes a problem that a uniform electron beam spot cannot be obtained in the entire fluorescent film.

In order to solve such a problem, conventionally, the cross section of the electron beam emitted from the electron gun is distorted in the opposite direction to the uneven magnetic field effect of the deflection yoke, and the focal length of the electron beam is scanned into the center of the fluorescent film and when scanned into the periphery. The dynamic focusing method which makes it variable to have been sought.

2 shows an example of such a dynamic focus electron gun.

This forms the cathode 11, the control electrode 12, and the screen electrode 13, and the auxiliary and main lens systems forming the pre-triode, and includes the first, second, focus electrodes 14 and 15, and the first The final acceleration electrode 16 is installed adjacent to the two focus electrode 15 is configured. Here, an elongated electron beam through hole 14B and an elongated electron beam through hole 15H are formed on the emission side surface of the first focus electrode 14 and the incident side surface of the second focus electrode 15, respectively.

A predetermined potential is applied to each of the electrodes, and a focus voltage VF is applied to the first focus electrode 14, and the focus voltage VF is applied to the second focus electrode 15 as a base voltage. In addition, a dynamic focus voltage VD synchronized with a deflection signal is applied, and the final acceleration electrode 16 is applied with a high voltage anode voltage VE higher than the voltages.

In the conventional cathode ray tube electron gun 10 configured as described above, the dynamic focus voltage VD is not applied to the second focus electrode 15 when the electron beam emitted from the cathode 11 is scanned to the center portion of the fluorescent film. Preliminary focusing and acceleration by an electron lens formed between the electrode 13 and the first focus electrode 14 and final focusing by a main lens formed between the second focus electrode 15 and the final acceleration electrode 16. And accelerated to land in the central portion of the fluorescent film. When the electron beam emitted from the casing 11 of the electron gun is deflected to the periphery of the fluorescent film, a dynamic focus voltage VD is applied to the second focus electrode 15, thereby providing first and second focus electrodes 14 and 15. The electron beam is elongated by the quadrupole lens formed between the first and second electrodes, and the dynamic voltage VD is applied to the second focusing electrode 15 to be finally focused and accelerated by the relatively weak main lens. As described above, the elongated and accelerated electron beam passes through a non-uniform magnetic field of the yaw that has a large divergence in the transverse direction, and the distortion is compensated for and landed at the periphery of the fluorescent film.

By the way, the electron gun 10 may form quadrupole lenses at the periphery of the fluorescent film to reduce the overall spherical aberration and improve the focus characteristic, but the dynamic focus voltage VD is applied to the second focus electrode 15. When applied, the main lens formed between the second focus electrode 15 and the final acceleration electrode 16 is weakened, thereby causing a problem of convergence drift of the electron beam. In addition, since the intensity of the main lens is weakened, the cross-sectional compensation of the electron beam due to the nonuniform magnetic field of the deflection yoke is not completed.

The present invention has been made to solve the above problems, it is possible to uniformly form the cross-section of the electron beam landing on the entire fluorescent film and to improve the focus characteristics of the electron beam color cathode ray that can improve the resolution of the cathode ray tube employing it The purpose is to provide a conventional gun.

In order to achieve the above object, the present invention is a color cathode ray comprising a cathode, a control electrode and a screen electrode constituting the pre-triode, the first, second, three, four focus electrode and the final acceleration electrode constituting the auxiliary and main lens system In the conventional electron gun, an elongated electron beam through hole is formed at the emission side of the first and third focus electrodes, a focus voltage is applied to the first and third focus electrodes, and the second auxiliary electrode and the fourth auxiliary electrode are formed. The focus electrode may be a ground voltage, and a dynamic focus voltage synchronized with a deflection signal is applied to the focus electrode.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 shows the electron gun for the color cathode ray tube according to the present invention, in which the cathode 21, the control electrode 22 and the screen electrode 23 forming the pre-triode are formed, and the first, second, 3, 4 focus electrodes 24, 25, 26, 27, and a final acceleration electrode 28 disposed adjacent to the fourth focus electrode 27 to form a bi-potential main capacitive lens. It is composed.

Here, the elongated electron beam through holes 24H and 26H are formed on the emission side of the first and third focus electrodes 24 and 26, and the second and fourth focus electrodes 25 are formed. A circular electron beam through hole is formed at 27. The longitudinal electron beam passing hole is preferably formed in a rectangular or elliptical shape.

And a predetermined voltage is applied to each of the electrodes constituting the electron gun 20, which will be described below. A focus voltage VF is applied to the first and third focus electrodes 24 and 26, and the focus voltage VF is applied to the second and fourth focus electrodes 25 and 27 as a base voltage. The dynamic focus voltage VD is applied in synchronization with the deflection signal. Reference numeral VS denotes a constant voltage applied to the screen electrode and VE denotes an enwood voltage.

Referring to the operation of the electron gun for the color cathode ray tube according to the present invention configured as described above are as follows.

In the electron gun 20 for the color cathode ray tube according to the present invention, when a predetermined voltage is applied to each of the electrodes as described above, a prefocus lens is formed between the screen electrode 23 and the first focus electrode 24. A quadrupole lens is formed between the first and second focus electrodes 24 and 25 and the third and fourth focus electrodes 26 and 27 according to whether the dynamic focus voltage VD is applied. A kettle lens is formed between the four focus electrode 27 and the final acceleration electrode 28.

Therefore, the electron beam emitted from the cathode 21 of the electron gun 20 passes through each electron lens and lands at each fluorescent point of the fluorescent film. This landing process is performed when the electron beam is scanned at the center of the fluorescent film. When divided into the injection when the peripheral is as follows.

First, when the electron beam emitted from the cathode 21 is scanned to the center portion of the fluorescent film, the dynamic focus voltage VD is not applied to the second focusing electrode 25 and the fourth focusing electrode 27 in synchronization with the deflection signal. Since the potential difference does not occur between the first and second focus electrodes 24 and 25 and the third and fourth focus electrodes 26 and 27, the quadrupole lens is not formed. Therefore, the electron beam emitted from the cathode 21 is prefocused and accelerated by a prefocus lens formed between the screen electrode 23 and the first focus electrode 24, and the final focus is achieved with the fourth focus electrode 27. Final condensation and acceleration are achieved by the kettle lens formed between the acceleration electrodes 28 so that the circular electron beam is landing in the best state in the center of the fluorescent film. In addition, when the electron beam emitted from the cathode 21 of the electron gun 20 is scanned to the periphery of the fluorescent film, the dynamic focus voltage synchronous with the deflection signal is applied to the second focus electrode 25 and the fourth focus electrode 27. VD) is applied to the first quadrupole lens due to the influence of the elongated electron beam through hole 24H formed on the emission side of the first focus electrode 14 between the first and second focus electrodes 24 and 25. Is formed, and a second quadrupole lens is formed between the third and fourth focus electrodes 26 and 27 under the influence of the elongated electron beam through hole 26H formed on the emission side of the third focus electrode 26. The dynamic focus voltage VD is applied to the fourth focus electrode 27 between the fourth focus electrode 27 and the final acceleration electrode 28 to form a relatively weak main lens.

Therefore, the electron beam emitted from the cathode 21 is subjected to diverging force in the vertical direction and focusing force in the horizontal direction by the quadrupole lens by the first quadrupole lens, and is lengthened as shown in FIG. In addition, the divergence force in the vertical direction and the focusing force in the horizontal direction are received while passing through the second quadrupole lens, so that the elongated electron beam is further lengthened while passing through the first quadrupole lens as shown in FIG.

The elongated electron beam is focused and accelerated by the main lens and then deflected by the deflection yoke to land at the periphery of the fluorescent film. The cross section of the electron beam landing on the fluorescent film is compensated by the nonuniform magnetic field of the deflection yoke having the focusing force and the diverging force in the vertical direction and the horizontal direction when the longitudinally shaped electron beam cross section of the quadrupole lens is deflected. Will have an electron beam cross section. The electron gun according to the present invention is applied with the dynamic focus voltage VD to the fourth focus electrode 27 constituting the main lens, so that the potential difference with the final accelerating electrode 28 is reduced, thereby decreasing the magnification of the lens. The miss convergence of the generated electron beam can be compensated by focusing and diverging the electron beam in multiple stages by the first and second quadrupole lenses, thereby improving the focus characteristic of the electron beam with respect to the entire fluorescent film.

As described above, the electron gun for the color cathode ray tube according to the present invention can reduce spherical aberration in each electrostatic lens by focusing and accelerating the electron beam emitted from the cathode by the first and second quadrupole lenses. A uniform electron beam cross section can be obtained in the fluorescent film and the resolution of the cathode ray tube employing the same can be improved.

Claims (3)

An electron gun for a color cathode ray tube comprising a cathode, a control electrode, and a screen electrode forming an anterior triode, and first, second, third, and four focus electrodes forming an auxiliary and main lens system and a final accelerating electrode. An elongated electron beam through hole is formed on the emission side of the focus electrode, a focus voltage is applied to the first and third focus electrodes, and the focus voltage is applied to the second and fourth focus electrodes as a base voltage. An electron gun for a color cathode ray tube, characterized by applying a dynamic focus voltage synchronized with a deflection signal. The electron gun for a color cathode ray tube according to claim 1, wherein the elongated electron beam passing hole is rectangular. The electron gun for a color cathode ray tube according to claim 1, wherein the elongated electron beam passing hole is elliptical.