KR930004792Y1 - Electron gun for cathode-ray tube - Google Patents

Abstract

No content.

Description

Electron gun for cathode ray tube

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

2 is a view showing an extract of a conventional focus electrode and a final acceleration electrode,

Figure 2a is a cross-sectional view.

FIG. 2B is a front view of the focus electrode or the final acceleration electrode shown in FIG. 2A.

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

4 is a perspective view of the final acceleration electrode shown in FIG.

FIG. 5 is a front view of the final accelerometer shown in FIG. 3 and shows a cross section of the electron beam passing therethrough.

* Explanation of symbols for main parts of the drawings

11 cathode 12 control electrode

13 screen electrode 14 focus electrode

20: final acceleration electrode 21: the first electrode

21a: (burring portion of the first electrode) 22: second electrode

M: Main Lens

The present invention relates to an electron gun for a cathode ray tube, and more particularly to an electron gun having a field extension focusing lens.

There are many kinds of electron guns for cathode ray tubes according to their characteristics, but as shown in FIG. 1, the cathode 2, the control electrode 3 and the screen electrode 4, which form the pre-triode tube portion, and the main lens system are formed. The focus electrode 5 and the final acceleration electrode 6 for final focusing and accelerating the electron beam are arranged in sequence. The electron gun 1 configured as described above is preliminarily focused and accelerated by the electron beam emitted from the cathode 2 through a prefocus lens formed between the screen electrode 4 and the focus electrode 5, and the focus electrode. Passed through the main lens formed between the (5) and the final acceleration electrode 6, the final focus and acceleration is landed on the fluorescent surface to form a single pixel. Therefore, in order to obtain a clear image in the full screen, it is desirable that the diameter of the beam post landing on the fluorescent screen is as small as possible and high density. However, the conventional electron gun 1 is subjected to many spherical aberrations caused by the main lens when the electron beam emitted from the cathode 2 passes through the main lens, so that the electron beam spot on the fluorescent surface is small and has a high density. There was a problem that the image quality of the cathode ray tube employing the same could not be obtained. In order to solve the effect of the spherical aberration, the diameters of the electron beam through holes of the focus electrode 5 and the final acceleration electrode 6 forming the main lens have been increased. Since the electron beam passing holes are arranged inline and inserted into the neck portion of the cathode ray tube in (6), it is impossible to make the electron beam passing holes larger than the eccentric distance of two adjacent electron beam passing holes, and the diameter of the electron beam passing holes is When the eccentric distance is increased to increase the convergence characteristic of the electron gun, a large improvement effect cannot be expected. Therefore, in order to improve spherical aberration in the conventional main lens, as shown in US Patent No. 4,370,592 and shown in FIG. 2, the exit side 7a of the focus electrode 7 and the incident side of the final acceleration electrode 8 are shown. The large-diameter electron beam passing holes 7H and 8H through which portions except for the edge portions (hereinafter referred to as burring portions 7b and 8b) are immersed in predetermined depths so that R, G, and B electron beams pass through them respectively. Are formed, and R, G, and B independent small-diameter electron beam through holes 7H 'and 8H' are formed at positions where a predetermined length is drawn from the burring portions 7b and 8b.

The electron beam passing through the main lens having passed through the electron beam formed with the main lens formed by the focus electrode 7 and the final acceleration electrode 8 is centered because the large-diameter electron beam passing holes 7H and 8H are asymmetrical. The vertical and horizontal focusing components of the electron beam passing through the independent small-diameter electron beam passing hole and the electron beam passing through the independent small-diameter electron beam passing hole on both sides were different from each other to uniformly form the electron beam spot landing on the fluorescent surface. That is, as shown in FIG. 2B, both side electron beams RB (BB) having passed through the large-diameter electron beam through hole of the focus electrode 7 or the final acceleration electrode 8 have low or high voltages distributed in the horizontal direction. Close to the burring portions 7b and 8b, and the central electron beam through hole is located far from the burring portions 7b and 8b, so that the electron beams RB and BB of both sides are relatively strongly focused in the horizontal direction. The central electron beam GB is focused relatively weakly. Both side electron beams RB and BB are approximately equal to the horizontal focusing in the vertical direction since the distance from the burring portions 7b and 8b in the vertical direction is approximately equal to the distance in the horizontal direction. The central electron beam GB is subjected to a large focusing force due to the influence of many electric fields in the vertical direction because the vertical distance between the burring portions 17b and 18b is closer than the horizontal distance. Therefore, the electron beams RB and BB on both sides passing through the main lens have a substantially circular beam cross section and a horizontal beam cross section, respectively, so that a uniform electron beam cross section can be obtained on the typical light plane. There will be no.

The present invention has been made to solve the above problems, to improve the spherical aberration of the main lens system to prevent the distortion of the electron beam passing through it and to provide an electron gun for cathode ray tube to improve the resolution of the cathode ray tube employing the same There is this.

In order to achieve the above object, the present invention provides a burring portion formed at the edge of the final acceleration electrode of the two electrodes constituting the main lens system, and from the edge of the first electrode formed with a large-diameter electron beam through hole sharing three electron beams. In a cathode ray tube electron gun having a second electrode having three independent small diameter electron beam through holes formed at a predetermined depth, the length of the burring portion formed at the edge of the large diameter electron beam through hole of the first electrode has an outer independent small diameter electron beam through hole. The electron beam passing hole in the center is formed longer than the ball, characterized in that formed.

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

The electron gun 10 for a cathode ray tube according to the present invention shown in FIG. 3 includes a cathode 11, a control electrode 12, a screen electrode 13, a focus electrode 14 constituting a main lens system, and a cathode 11. The final acceleration electrode 20 is configured, and the final acceleration electrode 20 has a burring portion 21a formed at the edge thereof in the direction of the electron beam travel, and has a large diameter electron beam passing hole sharing three electron beams of red, blue, and green. The first electrode 21 provided with 15H and the second electrode 22 having the first electrode independent small diameter electron beam passing holes 22HR, 22HG and 22HB spaced apart from the burring portion 21a by a predetermined distance. Has Here, the burring portion 21a formed around the large-diameter electron beam passing hole 21H of the first electrode 21 is the central independent small-diameter electron beam passing hole 22HG formed on the second electrode 22 according to the feature of the present invention. The length L of the side) is longer than the length L 'of the independent small-diameter electron beam through hole 22HG and 22HB on the outside. That is, the burring portion 21a 'formed at the edge of the first electrode 21 on the side corresponding to the upper and lower portions of the central independent small diameter electron beam passing hole 22HG of the second electrode 22 is formed longer than the surroundings. At this time, the width W of the burring portion 21a 'formed longer than the circumference of the first electrode 21 is smaller than twice the eccentric distance of the independent small-diameter electron beam passing hole formed in the second electrode 22. This is preferred.

Referring to the action of the electron gun for another cathode ray tube in the present invention configured as described above are as follows.

When a predetermined voltage is applied to each electrode of the cathode ray tube electron gun 10, a cathode lens is formed between the control electrode 12 and the screen electrode 13 and the screen electrode 13 and the focus electrode 14. The prefocus lens P is formed between the first and second lenses, and the main lens M is formed between the focus electrode 14 and the final acceleration electrode 20. Therefore, the electron beam B emitted from the cathode 11 is pre-focused and accelerated in the cathode lens and the prefocus lens P, and finally accelerated and focused in the main lens M to screen the screen surface S of the cathode ray tube. Landing in the center of the burring portion (21a) formed in the first electrode 25 of the final acceleration electrode 15, that is to be opposed to the central independent small diameter electron beam through hole (22HG) of the second electrode (22) Since the side is formed long, the spherical aberration when the electron beam passes through the main lens M is self-corrected to obtain a uniform beam cross-sectional shape. That is, among the electron beams B emitted from the cathode 11 and passing through the main lens M formed between the focus electrode 14 and the final acceleration electrode 20, the electron beam BG in the center, ie, the green electron beam BG, Strong in the vertical direction because it is located far from the burring portion 21a of the focus electrode 14 and the final acceleration electrode 20 in the horizontal direction and relatively close to the burring portions 14a and 21a in the vertical direction. A burring portion is formed at the edge of the first electrode 21 of the final acceleration electrode 20 to which the focusing force is received and the beaming cross section is received in the horizontal direction because of the relatively weak focusing force. Since the center portion 21a is formed relatively long, the electron beam is attracted to the burring portion side, so that the horizontal beam cross section is corrected to almost circular shape as shown in FIG. In more detail, the electrostatic lens magnification of the green beam is increased by the burring portion 21a 'formed at the edge of the first electrode 21 of the final accelerating electrode 20 so that the green electron beam is red and blue. It is more intense in the vertical direction than the electron beam to self-correct the cross section of the elongated electron beam in a circle. Both side electron beams, ie, red and blue electron beams, passing through the main lens M between the focus electrode 14 and the final acceleration electrode 20 have horizontal and vertical distances from the burring portion 21a. The focusing force received in the vertical direction is the same to form a circular beam cross section. Therefore, the electron beam emitted from the electron gun 10 can be landed on the screen surface in the best state, thereby improving the resolution.

In particular, according to the experiments of the present inventors, the resolution of the cathode ray tube employing the electron gun was improved by 30% or more.

As described above, the electron gun for the cathode ray tube can improve the spherical aberration and the astigmatism by compensating for the distortion of the electron beam cross section due to the non-uniform magnetic field of the main lens. .

Claims (2)

Of the two electrodes constituting the main lens system, the final acceleration electrode has a burring portion formed at an edge thereof, and the three independent electrodes are positioned at a predetermined depth from the edge of the first electrode and the first electrode having a large diameter electron beam through hole sharing three electron beams. In a cathode ray tube electron gun including a second electrode having a small diameter electron beam through hole, the length of the burring portion 21a 'formed at the edge of the large diameter electron beam through hole 21H of the first electrode 21 is an outer independent small diameter. An electron gun for a cathode ray tube, characterized in that the center of the electron beam passing hole (22HG) side is formed longer than the electron beam passing hole (22HR) (22HB) side. The width W of the burring portion 21a 'formed at the center electron beam through hole 22HG is twice the eccentric distance S of the independent small diameter electron beam through hole formed in the second electrode. Electron gun for cathode ray tube, characterized in that formed smaller.