KR100258906B1 - Electron gun for color cathode ray tube - Google Patents

Abstract

PURPOSE: An electron gun for color cathode ray tube is provided to prevent moire phenomenon of screen image and that brightness is decreased relatively at screen circumstance by preventing lateral enlargement of electron beam at screen circumstance. CONSTITUTION: A fronting triode part is composed of cathode(11), control electrode(12), screen electrode(13), and a subsidiary electron lens. Main lens are composed of the first(14), second(15), third(16), fourth(17), and fifth(18) focus electrode, and final acceleration electrode(19) is installed. Lateral enlargement type electron beam pass hole(16H)(17H) is formed at exit side(16b)(17b) of above the third, fourth focus lens(16)(17), longitudinal enlargement type electron beam pass hole(17H')(18H') is formed at incident side(17a)(18a) of above the fourth, fifth focus lens(17)(18). And focus voltage(VF) is licensed at the first, third, fifth focus electrode(14)(16)(18), dynamic focus voltage(VD), which considers above focus voltage(VF) as basis voltage, is licensed at the four focus electrode(17), and static voltage(VS) lower than focus voltage(VF) is licensed at the second focus electrode(15).

Description

Electron gun for colored cathode ray tube

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

FIG. 2 is a view showing the orbits of the electrostatic lens and the electron beam formed between the electrodes of the electron gun shown in FIG. 1, showing that a is formed on the horizontal side, and b is formed on the vertical side. .

* 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 16: third focus electrode

17: fourth focus electrode 18: fifth focus electrode

19: final acceleration electrode VF: focus voltage

VD: Dynamic Focus Voltage VS: Constant 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 of a cathode ray tube employing the same by uniformizing the cross section of the electron beam landing on the entire fluorescent film.

In general, an electron gun for a color cathode ray tube is mounted on a funnel neck of a cathode ray tube to emit hot electrons that excite a fluorescent film to form an image. In order to improve the resolution of an image formed by exciting the fluorescent film, an electron gun is scanned at the center of the fluorescent film. The electron beam spot scanned at the periphery of the fluorescent film should be small while the electron beam spot is not as large as possible, and the convergence and focus characteristics of the electron beam should be improved in all regions of the fluorescent film.

However, the conventional electron gun for color cathode ray tube has a barrel magnetic field in the horizontal direction and a pin cushion magnetic field in the vertical direction by the deflection yoke while the electron beam emitted from the point is selectively deflected by the deflection yoke and scanned at the center of the fluorescent film. There is a problem that the spot of the electron beam is distorted and the unevenness is generated under the influence of the degradation of the cathode ray tube.

In order to solve such a problem, conventionally, a method of applying a dynamic focus voltage to an electrode constituting the main lens or the auxiliary lens has been sought, but a satisfactory effect cannot be expected.

The present invention has been made to solve the above problems, and because the spot of the electron beam to be scanned on each portion of the fluorescent film can be small and its size can be provided to provide an electron gun for a color cathode ray tube that can improve the resolution of the cathode ray tube. Has its purpose.

Another object of the present invention is to provide an electron gun for a color cathode ray tube which can prevent the deterioration of focus characteristics due to the strength and weakness of the main lens by not applying the dynamic focus voltage to the electrode forming the main lens.

In order to achieve the above object, the present invention includes a cathode, a control electrode and a screen electrode forming a pre-triode, a first electrode, a first focusing electrode, a focusing electrode, and a final accelerating electrode. In the electron gun for cathode ray tube, a horizontal electron beam through hole is formed on the emission side of the third and fourth focus electrodes, respectively, and an elongated electron beam through hole is formed on the incident side of the fourth and fifth focus electrodes, respectively. A focus voltage is applied to the 3,5 focus electrodes, a dynamic focus voltage having the focus voltage as the base voltage is applied to the fourth focus electrode, and a constant voltage lower than the focus voltage is applied to the second focus electrode. It is done.

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

1 shows a electron gun for a color cathode ray tube according to the present invention, which comprises a cathode 11, a control electrode 12, and a screen electrode 13, which form an anterior triode, and a quadrupole lens and a main lens. The first, second, third, fourth and fifth focus electrodes 14, 15, 16, 17 and 18 and the final acceleration electrode 19 are provided.

In the emission side surfaces 16b and 17b of the third and fourth focus electrodes 16 and 17 constituting the quadrupole lens, transverse electron beam through holes 16H and 17H are formed, and the fourth and fifth Longitudinal electron beam through holes 17H 'and 18H' are formed in the incident side surfaces 17a and 18a of the focus electrodes 17 and 18. The horizontal electron beam passing holes 16H and 17H are band-shaped metal members parallel to the upper and lower portions of the electron beam passing holes formed on the incident side surfaces 16b and 17b of the 3 and 4 focus electrodes 16 and 17, respectively. (Not shown) may be attached to each other, and the elongated electron beam through holes 17H 'and 18H' are interposed between the electron beam through holes formed on the incident side surfaces of the fourth and fifth focus electrodes 17 and 18. It may be formed by attaching a band-like metal member or a metal member of a failure type to the band.

And a predetermined potential is applied to each electrode constituting the electron gun, which will be described in detail as follows.

A predetermined constant voltage VS is applied to the second focus electrode 15, and a focus voltage VF that is relatively higher than the constant voltage VS is applied to the first, third and fifth focus electrodes 14, 16, and 18. Is applied to the fourth focusing electrode 17 and the focus voltage VF is applied as a base voltage, and a dynamic focus voltage VD synchronized with a deflection signal is applied to the fourth focusing electrode 17. The wood voltage VE is applied. In this case, it is preferable that the constant voltage VS applied to the second focus electrode 15 is applied to the screen electrode and the coin.

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.

First, as a predetermined voltage is applied to each electrode of the electron gun, a universal potential first auxiliary lens 100 is formed on the first, second, and third focus electrodes 14, 15, and 16. 4, a first quadrupole lens 200 is formed between the focus electrodes 16 and 17, and a second quadrupole lens 300 is formed between the fourth and fifth focus electrodes 17 and 18. A bi-potential main lens 400 is formed between the fifth focus electrode 18 and the final acceleration electrode 19.

As described above, a state in which an electron beam passes through the electron lens formed between the electrodes and lands on the fluorescent film is divided into when the electron beam is scanned at the center of the fluorescent film and at the periphery.

In FIG. 2, the trajectory of the electrostatic lens and the electron beam formed between the electrodes forming the tank gun is visualized. The solid line shows when the electron beam is scanned to the center of the fluorescent film and the dotted line shows the electron beam to be scanned to the periphery of the fluorescent film. The time was shown.

First, when the electron beam is scanned to the center portion of the fluorescent film, the dynamic focus voltage VD synchronous with the deflection signal applied to the deflection yoke to the fourth focus signal 17 becomes equal to the focus voltage VF. The potential difference does not occur between the 3, 4 and 5 focus electrodes 16, 17 and 18, so that the first and second quadrupole lenses 200 and 300 are not formed. Therefore, the electron beam emitted from the cathode 11 is preliminarily focused and accelerated in the first auxiliary lens 100 and finally focused and accelerated in the main lens 400 so as to land in the best state in the center of the fluorescent film.

When the electron beam emitted from the cathode 11 is scanned to the periphery of the fluorescent film, the dynamic focus voltage VD in synchronization with the deflection signal is applied to the fourth focus electrode 17. The first and second quadrupole lenses 200 and 300 are formed between the five focus electrodes 16, 17, and 18, which are divided into horizontal and vertical directions as follows.

First, in the horizontal direction, as shown in FIG. 2, a diverging lens 201 is formed between a third focus electrode 16 to which a relatively low potential is applied and a fourth focus cug 17 to which a high potential is applied. The focusing lens 301 is formed between the fourth and focus electrodes 17 to which the high potential is applied and the fifth focus electrode 18 to which the low potential is applied. The focusing lens 202 is formed between the third and fourth focus electrodes 16 and 17 in the vertical direction, and the diverging lens 302 is formed between the fourth and fifth focus electrodes 17 and 18. do. Therefore, the electron beam passing therethrough is preliminarily focused and accelerated by the first auxiliary lens 100 formed between the first, second, and third focus signals 14, 15, and 16, and then diverges in the horizontal direction. Passing through 201) receives a diverging power and passes through the outer focus of the focusing lens 301 and the main lens. Therefore, the electron beam receives a lot of aberration in the horizontal direction by the nonuniform magnetic field of the deflection yoke. The vertical component of the electron beam is focused and diverged by the diverging lens 302 formed between the focusing lens 202 and the fourth and fifth focusing electrodes 17 and 18 formed between the third and fourth focusing electrodes. Since it passes through the central part of the electron beam, the electron beam is focused, thereby receiving less aberration due to the nonuniform magnetic field of the deflection yoke. Accordingly, the cross section of the electron beam scanned at the periphery of the fluorescent film is circular due to the difference in the correction force due to the non-uniform magnetic field of the deflection yoke in the horizontal and vertical directions.

In addition, since the electron gun according to the present invention has no change in the voltage applied to the fifth focus electrode 18 constituting the main lens, there is no change in focus and change in convergence, and thus the resolution can be prevented from being deteriorated by color blurring at the periphery of the screen.

As described above, the electron gun for the color cathode ray tube of the present invention can prevent the electron beam from being lateralized in the periphery of the screen, thereby preventing the moiré phenomenon of the image and the relative decrease in luminance at the periphery of the screen.

Claims (2)

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, fourth, fifth focus electrodes forming an auxiliary lens and a main lens, and a final acceleration electrode. On the emission side surfaces 16b and 17b of the four focus electrodes 16 and 17, horizontal electron beam passing holes 16H and 17H are formed, respectively, and the fourth and fifth focus electrodes 17 and 18 are formed. Longitudinal electron beam through holes 17H 'and 18H' are respectively formed in the incident side surfaces 17a and 18a of the first and second focus electrodes 17, 16 and 18, respectively. VF is applied to the fourth focusing electrode 17, and a dynamic focus voltage VD is applied to the fourth focusing electrode 17 as the base voltage, and lower than the focus voltage VF to the second focusing electrode 15. An electron gun for a color cathode ray tube, characterized in that a constant voltage (VS) is applied. The electron gun for color cathode ray tube according to claim 1, wherein the elongated electron beam through holes 17H 'and 18H' and the elongated electron beam through holes 16H and 17H are rectangular and elongated rectangular holes. .