KR920005866Y1 - Electron gun for color cathode ray tube - Google Patents

Abstract

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Description

Electron gun for colored cathode ray tube

FIG. 1 is a sectional view showing a conventional electron gun for color cathode ray tubes showing a method of applying an electric potential.

2 is a cross-sectional view showing the electron gun for the color cathode ray tube according to the present invention, showing a method of applying a potential.

* Explanation of symbols for main parts of the drawings

11 cathode 12 control electrode

13 screen electrode 14 first focus electrode

15: second focus electrode 15a: first electrode

15b: second electrode 15c: third electrode

16: third focus electrode 16a: 3a electrode

16b: 3b electrode 17: anode wood electrode

Vs: Constant voltage Vf: Focus voltage

Vd1, Vd2: Dynamic Focus Voltage Ve: Anode Wood Voltage

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to an improved method of applying a potential to an electrode constituting the electron gun.

In general, as the color cathode ray tube is enlarged and planarized, the angle of deflection of the electron beam emitted from the electron gun is increased, which is caused by astigmatism caused by a non-uniform field of deflection yoke for deflecting the electron beam and at the center and periphery of the screen surface. The occurrence of the upper spread by the focus curriculum causes a problem of resolution of the cathode ray tube.

In order to solve this problem, a dynamic focus method for changing a focus voltage in synchronization with a deflection synchronous signal of a deflection yoke has been proposed.

The dynamic focus method is roughly divided into a low voltage drive method and a high voltage drive method. FIG. 1 shows an example of the low voltage dynamic focus electron gun 1. This includes the cathode 2, the control electrode 3, and the screen electrode 4, which form the transposition triode, and the first focus electrode 5 and the second focus electrode that focus and accelerate the electron beam emitted from the cathode 2; (6), the third focus electrode (7) and the anode electrode (8) are arranged, while the second focus electrode (6) is the first electrode (6a), the second electrode (6b), the third electrode ( 6c). In addition, a constant voltage Vs is applied to the second electrode 6b of the screen electrode 4 and the second focus electrode 6, and a focus voltage (V) is applied to the first focus electrode 5 and the third focus electrode 7. Vf) is applied to the first electrode 6a and the third electrode 6c of the second focus electrode 6 and the dynamic focus voltage Vd, which is variable in accordance with the vertical synchronization signal and also in accordance with the horizontal synchronization signal, is applied. The high voltage anode voltage Ve is applied to the anode electrode 8.

In the conventional low voltage dynamic focus electron gun 1 configured as described above, a prefocus electrostatic lens is formed between the screen electrode 4 and the first focus electrode 5, and the first focus electrode 5 and the third focus electrode 7 are formed. An asymmetric auxiliary capacitive lens is formed between the two electrodes, and a main capacitive lens is formed between the third focus electrode 7 and the anode electrode 8. When the electron beam emitted from the electron gun 1 is not deflected to the periphery of the screen, that is, when the electron beam is scanned at the center of the fluorescent surface, the first electrode 6a and the third electrode 6 of the second focus electrode 6 ( Since the dynamic focus voltage Vd is not applied to 6c) (Vd = 0), the asymmetric auxiliary capacitive lens formed between the first focusing electrode 5 and the third focusing electrode 7 becomes weak. Therefore, the divergence force diverging in the vertical direction is weakened to form a circular cross section of the beam spot landing at the center of the screen.

When the electron beam emitted from the cathode 2 is deflected to the periphery of the screen by the deflection yoke, the dynamic focus voltage Vd, which is variable to the horizontal and vertical synchronization signals of the deflection yoke, is changed to the second focus electrode 6. The asymmetric auxiliary electrostatic lens formed between the first focusing electrode 5 and the third focusing electrode 7 is applied to the first electrode 6a and the third electrode 6c of the As a result, a strong diverging lens is formed. Therefore, the cross section of the electron beam passing through this has an elongated shape, and the distortion of the electron beam due to the nonuniform magnetic field of the deflection yoke is corrected to form a circular shape of the electron beam landing on the periphery of the screen. Therefore, astigmatism due to deflection of the deflection yoke can be corrected.

However, the low voltage dynamic focus electron gun 1 corrects the distortion of the electron beam due to deflection at the periphery of the screen by adjusting the intensity of the asymmetric auxiliary electrostatic lens, but the effect is very weak, and the focus voltage Vf does not change. Therefore, the problem of deterioration of focus has been a problem.

The present invention was devised to solve the above-mentioned problems. By changing the focus voltage in synchronization with the deflection signal of the deflection yoke, the strength of the auxiliary electrostatic lens system and the main lens system is changed, and the beam spot landing on the screen improves distortion and focus degradation. The purpose is to provide an electron gun for color cathode ray tubes in which no spreading occurs in the entire screen area.

In order to achieve the above object, the present invention provides a cathode, a control electrode and a screen electrode to which a positive voltage is applied, and a first focus electrode to which a focus voltage is applied to form a main lens system. The second focusing electrode, which is formed into three electrodes, is applied with the constant voltage to the second electrode, and the dynamic focus voltage is applied to the first and third electrodes, and the focus voltage of the first focus voltage and the coin is applied. In a color cathode ray tube electron gun in which a third focus electrode to be applied and an anode electrode to which a high voltage anode voltage is applied are sequentially arranged, the third focus electrode is separated into a 3a electrode and a 3b electrode from a second focus electrode side. And a focus voltage between the first focus electrode and a round potential is applied to the third a electrode, and the third voltage is synchronized with the focus voltage and the deflection signal. And that the focus voltage is applied to its features.

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

The electron gun 10 for the color cathode ray tube according to the present invention shown in FIG. 2 includes the cathode 11, the control electrode 12, and the screen electrode 13, which form the pre-triode tube portion, and the first focus electrode 14 forming the main lens system. ), The second focusing electrode 15 formed separately from the first, second, and third electrodes 15a, 15b, and 15c, and the third focusing electrode 16 and the anode electrode 17 are sequentially arranged. Configuration. In this case, the third focus electrode 16 is separately formed as a third a electrode 16a and a third b electrode 16b from the second focus electrode 15 side according to a feature of the present invention.

A predetermined potential is applied to each of the electrodes. That is, a constant voltage Vs is applied to the screen electrode 13 and the second electrode 15b, and a focus voltage Vf of 5 to 10 Kv is applied to the first focus electrode 14 and the third a electrode 16a. The dynamic focus voltage Vd ₁ of approximately 800 to 1600V is applied to the first electrode 15a and the third electrode 15c. An anode voltage (Ve) of 20 to 30 Kv is applied to the anode electrode (17), and a focus voltage (Vf) of 28 to 32% of the anode voltage (Ve) and 0 to 0 is applied to the third b electrode (16b). A dynamic focus voltage Vd ₂ of 5 Kv is applied. In this case, the potential applied to the third b electrode 16b may be a potential synchronized with the potential applied to the first and third electrodes 15a and 15c.

In the electron gun 10 for the color cathode ray tube according to the present invention configured as described above, a prefocus lens is formed between the screen electrode 13 and the first focus electrode 14, and the first focus electrode 14 and the third focus electrode ( A unipotential pre-formed lens is formed between the first and second electrodes. The auxiliary electrostatic lens is formed only when the dynamic focus voltage Vd2 is applied to the 3a electrode 16a and the 3b electrode 16b. And an anode electrode 17 form a main electrostatic lens. Therefore, when the electron beam emitted from the cathode 11 is scanned to the center of the screen, a dynamic focus voltage Vd ₁ (Vd ₂ ) is applied to the first electrode 15a, the third electrode 15c, and the third b electrode 16b. Since the electron beam emitted from the cathode 11 is prefocused and accelerated in the prefocus electrostatic lens and the unipoten set lens, and finally focused and accelerated in the main electrostatic lens, it is landed optimally in the center of the screen. do.

When the electron beam emitted from the cathode 11 is deflected to the periphery of the screen surface by the deflection yoke, the dynamic focus voltage Vd ₁ , which is varied according to the vertical synchronizing signal and the horizontal synchronizing signal of the deflection yoke, is made. In addition to the first and third electrodes 15a and 15c, the dynamic focus voltage Vd ₂ is applied to the third b electrode 16b in combination with the focus voltage Vf applied thereto. Accordingly, the unipotential electrostatic lens formed between the first focusing electrode 14 and the third focusing electrode 16 is strongly formed, and an auxiliary electrostatic lens is formed between the third a 16a and the third b electrode 16b. Since the main lens is relatively weakly formed, the electron beam emitted from the cathode 11 receives a strong divergence force in the vertical direction and a weak focusing force in the horizontal direction in the unipotentiometric lens so that its cross section is elongated. The focal length is increased because the light is passed through the central portion of the preliminarily focused and weakened main capacitive lens. As such, when the electron beam having a longitudinal cross section through the main lens is deflected by the deflection yoke, the distortion of the electron beam is corrected by the nonuniform magnetic field of the deflection yoke, thereby obtaining a circular beam spot around the screen surface. .

As described above, the electron gun for the color cathode ray tube of the present invention can apply a dynamic focus voltage to a plurality of electrodes forming the same, thereby correcting astigmatism accompanying deflection of the electron beam and improving focus characteristics, thereby realizing a sound tube having a clear screen. There is this.

Claims (2)

The cathode, the control electrode and the screen electrode to which the positive voltage is applied, the first focus electrode to which the focus voltage is applied, and the first, second, and third electrodes form a main lens system. A second focus electrode to which the constant voltage is applied and a dynamic focus voltage applied to the first and third electrodes in synchronization with the deflection yoke, and a third focus electrode to which the first focus voltage and the focus voltage on the coin are applied, and a high-voltage ano In an electron gun for a color cathode ray tube in which an anode electrode to which a wood voltage is applied is sequentially arranged, the third focusing electrode 16 is moved from the second focusing electrode 15 side to the 3a electrode 16a and the 3b electrode ( 16b), and the focus voltage Vf of the first potential electrode 14 and the round potential is applied to the third a electrode 16a, and the focus voltage Vf and the third b electrode 16b are applied. Dyna synchronous to deflection signal An electron gun for a color cathode ray tube, characterized by applying a mix focus voltage (Vd ₂ ). The focus voltage Vf and the dynamic focus voltage Vd ₂ applied to the third a, 3b electrodes 16a and 16b of the third focus electrode 16 are respectively 28 An electron gun for color cathode ray tubes, characterized in that from 0 to 32%, and 0 ≦ Vd ₂ ≦ 5kv.