KR940004108Y1 - Electron gun for c-crt - Google Patents

Abstract

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Description

Electron gun for colored cathode ray tube

1 is a cross-sectional view of an electron gun for a conventional color cathode ray tube.

2 is a cross-sectional view of an electron gun for a color cathode ray tube according to the present invention.

3A and 3B show a second focus electrode or a third focus electrode shown in FIG. 2, wherein a is a front view and b is a sectional view taken along the line A-A 'in FIG.

FIG. 4 is a partially cutaway sectional view showing another embodiment of the second auxiliary electrode provided between the second and third focus electrodes shown in FIG.

* Explanation of symbols for main parts of the drawings

11 cathode 12 control electrode

13 screen electrode 14 first focus electrode

15: first auxiliary electrode 16: second focus electrode

17: second auxiliary electrode 18: third focus electrode

19: final acceleration electrode 20: horizontal flat plate

Vf: Focus voltage Vs: Constant voltage

Vd: Dynamic 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 improve the resolution by correcting astigmatism and focus characteristics due to a nonuniform magnetic field of a deflection yoke for deflecting an electron beam.

In general, the electron gun for inline type color cathode ray tube, as shown in FIG. 1, the first focus electrode 5 forming the main lens system with the cathode 2, the control electrode 3, and the screen electrode 4 constituting the pre-triode tube portion. And a second focusing electrode 6 and a final accelerating electrode 7, which are arranged on the exit side surface 5a of the first focusing electrode 5 and the incident side surface 6a of the second focusing electrode 6. The elongated electron beam through hole 5H and the horizontal electron beam through hole 6H are formed, respectively. A predetermined focus voltage Vf is applied to the first focus electrode 5, and an anode voltage Ve that is much higher than a focus voltage is applied to the final acceleration electrode 7, and the second focus electrode 6 is applied. A parabolic type dynamic focus voltage Vd is applied to the focus voltage Vf as a base voltage and synchronized with a deflection synchronous signal of the deflection yoke.

In the conventional color cathode ray tube electron gun 1 configured as described above, a prefocus lens is formed between the screen electrode 4 and the first focus electrode 5, and between the first focus electrode 5 and the second focus electrode 6. The quadrupole lens is formed according to whether the dynamic focus voltage Vd is applied, and a main lens is formed between the second focus electrode 6 and the final acceleration electrode 7. The electron gun has a quadrupole lens between the first and second focus electrodes 5 and 6 because the dynamic focus voltage Vd is not applied to the second focus electrode 6 when the electron beam is scanned to the center portion of the screen surface. Since the electron beam emitted from the cathode 2 passes through the prefocus lens and the main lens, it is landed at the center of the screen surface. When the electron beam is deflected toward the periphery of the screen surface, a dynamic focus voltage Vd is applied to the second focus electrode 6 to form a quadrupole lens between the first and second focus electrodes 5 and 6. Since the electron beam emitted from the cathode 2 passes through the prefocus lens and then passes through the quadrupole lens, the electron beam passing through this has an elongated cross section due to the effect of the quadrupole lens. After passing through the main lens it is deflected by the deflection yoke and landed at the periphery of the screen surface.

At this time, the electron beam landing at the periphery of the screen surface is circular when the electron beam having the longitudinal beam cross section is corrected by the nonuniform magnetic field of the deflection yoke when the main lens passes.

However, the conventional color cathode ray tube electron gun 1 has a small potential difference (about 1400 V) between the first focusing electrode 5 and the second focusing electrode 6, so that the effect of a sufficient quadrupole lens cannot be expected. In this case, the astigmatism generated at the periphery of the screen surface, that is, the phenomenon in which the electron beam is laterally deformed at the periphery cannot be completely eliminated, and thus the resolution of the cathode ray tube employing the same cannot be improved. In particular, the electron gun has a problem that it is difficult to implement the circuit due to a high correction voltage for correcting the electron beam, that is, a voltage applied to the first and second focus electrodes, and arc discharge occurs between the electrodes.

The present invention improves astigmatism and focus characteristics by correcting the distortion of the electron beam generated by the non-uniform magnetic field of the deflection yoke to solve the above problems, and improves the resolution of the cathode ray tube employing the electron gun for color cathode ray tube. The purpose is to provide.

In order to achieve the above object, the present invention provides a cathode, a control electrode, a screen electrode, and a first, second, and three focus electrodes to which a predetermined focus voltage is applied at an equipotential, and the first, second, and third focus electrodes. An electron gun for a color cathode ray tube provided with a first and second auxiliary electrodes provided between and provided with a potential lower than the focus voltage and having an elongated electron beam through hole and a transverse electron beam through hole, respectively. A horizontal flat plate parallel to the electron beam passing hole is provided on the upper and lower sides of the emission side and the incident side of the opposing second and third focus electrodes.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the accompanying drawings.

The electron gun for the color cathode ray tube according to the present invention, as shown in FIG. 2, forms the main lens system with the cathode 11, the control electrode 12, and the screen electrode 13 constituting the pre-triode tube part. It is interposed between the first, second and third focus electrodes 14, 16 and 18 sequentially arranged from the side, and the first, second and third focus electrodes 14, 16 and 18 respectively. First and second auxiliary electrodes 15 and 17 having an electron beam through hole 15H and an elongated electron beam through hole 17H formed therein, and a final acceleration electrode 19 disposed adjacent to the third focus electrode 18. And an inner surface of the emission side surface 16a of the second focus electrode 16 opposite to the second auxiliary electrode 17 and an incident side surface 18a of the third focus electrode 18. According to a feature of the present invention, the horizontal flat plate 20 is installed in parallel with the three electron beam passing holes 16R, 16G, 16B, 18R, 18G, and 18B. In this case, the horizontal flat plate 20 is preferably installed to be adjacent to the upper and lower edges of the electron beam passing holes 16R, 16G, 16B, 18R, 18G, and 18B, and the second auxiliary electrode 17 The elongated electron beam passing holes 17H are electron beam passing holes 16R, 16G, 16B and 18R formed on the emission side of adjacent second and third focus electrodes 16 and 18 as shown in FIG. It is preferable to form larger vertical width than (18G) (18B). A predetermined focus voltage Vf is applied to the first, second and third focus electrodes 14, 16 and 18, and the first and second auxiliary electrodes 15 and 17 are applied to the focus voltage Vf. At least one electrode constituting the triode lower than) is applied with a constant voltage (Vs) having an equipotential, while the second auxiliary electrode (17) has a dynamic focus voltage (Vd) synchronous with a deflection synchronous signal of the deflection yoke. An anode voltage (Ve) higher than the focus voltage is applied to the final acceleration electrode 19. The first and second auxiliary electrodes 15 and 17 are preferably applied at the equipotential to the screen electrode 13. Do.

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

In the electron gun for the color cathode ray tube according to the present invention, a prefocus lens is formed between the screen electrode 13 and the first focus electrode 14 as the predetermined potential is applied to each electrode, and the first focus is formed. A first universal electrostatic lens is formed between the electrode 14, the first auxiliary electrode 15 having the elongated electron beam through hole 15H, and the second focus electrode 16, and the second focus electrode 16 ), A second universal electrostatic lens is formed between the second auxiliary electrode 17 and the third focus electrode 18 on which the horizontal electron beam through hole 17H is formed, and the third focus electrode 18 A bipotential main lens is formed between the final acceleration electrodes 19. Therefore, when the electron beam emitted from the cathode 11 is scanned to the center of the screen surface, the dynamic focus voltage Vd in synchronization with the deflection signal is not applied to the second auxiliary electrode 17. The first universal electrostatic lens receives the focusing force in the horizontal direction and the second the universal electrostatic lens receives the focusing force in the vertical direction to form a circular beam cross section, and the electron beam having the circular cross section is It passes through the main lens and renders in the best state in the center of the screen surface. When the electron beam emitted from the cathode 11 is deflected to the periphery, a dynamic focus voltage synchronized with a deflection signal is applied to the second auxiliary electrode 17. The third focus electrodes 16 and 18 Since the horizontal flat plate 20 is provided on the inner surface of the emission side surface 16a and the incident side surface 18a, the axial potential rises even if the potential applied to the second auxiliary electrode 17 is not high. That is, the potential difference between the second auxiliary electrode 17 and the second and third focus electrodes 16 and 18 becomes small, so that the second universal electrostatic lens is relatively weakened. Accordingly, the electron beam emitted from the cathode 11 receives a weak focusing force in the vertical direction and a strong focusing force in the horizontal direction while passing through the second universal electrostatic lens, so that the cross section is lengthened, and the focal length in the vertical direction is Will be longer. As described above, the electron beam having the elongated cross section is circularly corrected by the non-uniform magnetic field of the deflection yoke, so that the landing is optimally performed at the periphery of the screen surface.

As described above, the electron gun for the color cathode ray tube of the present invention can lower the dynamic focus voltage applied to the second auxiliary electrode, thereby improving the breakdown voltage characteristics between the electrodes, and improve the focus characteristic and astigmatism, thereby providing a uniform beam cross section on the entire screen surface. There is an advantage you can get.

Claims (4)

A cathode, a control electrode, and a screen electrode forming a transposition triode are provided between the first, second and third focus electrodes to which a predetermined focus voltage is applied at an equipotential, and a potential lower than the focus voltage. In the electron gun for a color cathode ray tube, wherein the first and second auxiliary electrodes are formed, each of which has an elongated electron beam through hole and an elongated electron beam through hole, the second and third focusing opposing the second auxiliary electrode 17. An electron gun for a color cathode ray tube, characterized in that a horizontal flat plate (20) in parallel with an electron beam through hole is provided above and below an emission side (16a) and an incident side (18a) of an electrode (16). The electron gun for a color cathode ray tube according to claim 1, wherein the vertical width of the electron beam through hole of the second auxiliary electrode 17 is larger than the vertical widths of the second and third focus electrodes 16 and 18 opposite thereto. . The dynamic focus voltage of claim 1, wherein the first and second auxiliary electrodes 15 and 17 are applied at an equipotential with at least one electrode forming the triode, and the second auxiliary electrode 17 is synchronized with a deflection signal. An electron gun for a color cathode ray tube, characterized by applying (Vd). The electron gun for a color cathode ray tube according to claim 1, wherein the first and second auxiliary electrodes (15, 17) are applied at an equipotential with the screen electrode (13).