KR100235999B1 - A converging electrode of electron gun for color crt - Google Patents

Abstract

The present invention improves the resolution at the periphery of the screen by correcting astigmatism according to the amount of deflection of the electron beam.

To this end, the present invention, in the electron gun for the color cathode ray tube, a plurality of longitudinal rectangular electron beam passing holes are formed in the fixed voltage focusing electrode on the opposite surface of the variable voltage focusing electrode, and vertical flat electrodes on both sides of the vertical surface of the longitudinal rectangular electron beam passing hole. Protruding toward the cathode, a guide inner electrode having an elongated rectangular electron beam passing hole or a circular electron beam passing hole is inserted therein, and the circular electron beam passing hole and the circular electron beam are inserted into the variable voltage focusing electrode opposite to the fixed voltage focusing electrode. The purpose of this is achieved by attaching a square plate-shaped correction electrode having horizontal flat electrodes protruding toward the cathode in a direction orthogonal to the flat surface above and below the through hole.

Description

Focusing electrode of electron gun for color cathode ray tube

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun used for a large color TV or a high-definition industrial monitor, and more particularly, to an electron gun for a color cathode ray tube that can improve the resolution at the periphery of a screen by correcting astigmatism according to the amount of deflection of an electron beam. It relates to a focusing electrode.

In general, as shown in Fig. 1, the color tube consists essentially of an electron gun (1), a deflection yoke (2), a shadow mask (3), and a CRT (4), which is a kind of glass vessel made of a vacuum inside. When the electron beam 5 radiated from three cathodes of red, green, and blue is focused by the potential difference between electrodes in the electron gun 1 and is deflected to a predetermined position on the screen by the deflection yoke 2, the panel 6 and The desired image is obtained by passing through the holes of the shadow mask 3 at regular intervals and colliding with red, green, and blue phosphors applied to the inner surface of the panel 6.

At this time, the cathode ray tube 4 is coupled to the panel 6 connected to the side surface of the panel 6 and the rear surface of the fluorescent surface coated with red, green, and blue phosphors, a shadow mask having a color screening function, and converged backwards. It consists of the funnel 7 which has a tubular neck part 7a.

In addition, an electron gun 1 is embedded in the neck portion 7a of the funnel 7 that converges behind the screen, and the electron beam 5 emitted from the electron gun 1 is horizontally or vertically disposed outside the neck portion 7a. A deflection yoke 2 for deflecting in the direction is engaged.

Fig. 2 is a cross sectional view schematically showing a conventional electron gun for color water tubes, wherein the electron gun 1 is composed of a triode and a main lens unit, and each configuration is as follows.

First, the three-pole part has a heater 8, which is a heat source, emits hot electrons, and controls a control electrode for controlling and accelerating the hot electrons radiated from the negative electrode 9 and the negative electrode 9 arranged in-line. 10) and the accelerating electrode (11).

The main lens unit includes a focusing electrode 12 that focuses the electron beam 5 generated in the triode, and an anode 13 that finally accelerates the electron beam 5.

Here, the control electrode 10 is grounded, a low voltage of 500 to 1000 V is applied to the acceleration electrode 11, a high voltage of 25 to 35 kV is applied to the anode 13, and the anode 13 is applied to the focusing electrode 12. A medium voltage corresponding to 20 to 33% of the voltage applied to is applied.

In the conventional color image tube electron gun 1 configured as described above, as a predetermined voltage is applied to each electrode, an electrostatic lens is formed by a potential difference applied to the focusing electrode 12 and the anode 13 to generate an electron beam generated at the triode. (5) is focused on the center of the fluorescent surface.

In this case, in order to reproduce an image, the electron beams 5 should be sequentially scanned on each area of the screen, and for this purpose, the electron beams 5 should be deflected to the entire area of the screen. In correlation, the three red, green, and blue electron beams are arranged side by side horizontally, so that each electron beam is converged to one point of the fluorescent surface, and a self-convergence deflection yoke (2) using a non-uniform magnetic field is used. ) Is applied.

As shown in FIGS. 3A and 3B, the distribution of the magnetic field generated in the deflection yoke to which the self-focus type is applied is a pincushion type of horizontal deflection magnetic field and a barrel type of vertical deflection magnetic field. Mis-convergence) was corrected.

However, as shown in FIGS. 4A and 4B, each magnetic field can be described by dividing into two-pole and four-pole components. The two-pole component serves to deflect the electron beam in the horizontal and vertical directions. By converging the electron beam in the vertical direction and diverging in the horizontal direction, the vertical beam is focused at a shorter distance than the horizontal beam, causing haze phenomenon in which the vertical direction of the beam rises on the screen. This results in deterioration of image quality.

5A and 5B show more specifically how the distortion of the electron beam spot appears on the screen.

5A and 5B, since the deflection magnetic field is not applied at the center of the screen, the electron beam spot has an accurate shape, but at the periphery thereof, as described above, the high-density horizontal core that is dissipated in the horizontal direction and over-focused in the vertical direction is distorted 14) and the haze 15, which is a low-density upper spreading region above and below, are generated, which causes resolution deterioration, particularly in the periphery of the screen.

FIG. 6A illustrates a principle in which the electron beam spot represented by the deflection yoke generates astigmatism without being focused at the periphery of the screen.

Even if the magnetic field is close to uniform, the beam spot is distorted by astigmatism at the periphery of the fluorescent surface due to the fine pincushion or barrel magnetic component. .

In addition, this problem becomes larger as the water pipe becomes larger or the deflection angle becomes larger, and a problem that must be solved in consideration of the tendency of consumers who prefer a large water pipe and the increasing deflection angle according to the size of the water pipe. Is one of.

In order to solve the above problems, the 4-pole component is generated by the electron gun 1 to cancel the 4-pole component generated by the self-focusing deflection yoke 2 so that the electron beam components in the horizontal and vertical directions can be focused at one point. Can be.

In other words, in order to form a four-pole lens, the focusing electrode 12 is divided into two first and second focusing electrodes, and a dynamic quadrupole electrode is provided between the electrodes to generate a potential difference at the four-pole electrode. By forming a pole lens, astigmatism can be corrected.

However, the electron beam 5 is focused in front of the screen at the periphery due to the difference in the electron beam travel distance between the center of the screen and the periphery, and the haze phenomenon still occurs.

Therefore, to solve this problem, when the electron beam 5 is deflected to the periphery of the screen, the electrostatic lens is controlled by applying a dynamic voltage (variable voltage) synchronized with the deflection frequency to weaken the power of the main lens and to adjust the focusing distance of the beam. The method of correcting the astigmatism of is mainly adopted.

Brief description of the astigmatism correcting means according to the prior art will be described with reference to FIGS. 7 to 11 as follows.

The astigmatism correcting means disclosed in US Pat. No. 5,061,881 of Matsushita, Japan shown in FIGS. 7 to 11 has a longitudinal rectangular electron beam through hole 201, 202, 203 formed on the first focusing electrode 20. And a plurality of horizontal rectangular electron beam through holes 301, 302, and 303 formed in the second focusing electrode 30 to form a quadrupole lens to correct astigmatism at the periphery. .

That is, the electron beam generated in the triode portion, which is the electron beam forming region, passes through the first divided electrode 20 and the second focused electrode 30 divided into two parts, is focused by the main lens, and forms an image on the screen.

In particular, when the electron beam is deflected to the periphery, the voltage applied to the first focusing electrode 20 is fixed at a constant level, but the voltage applied to the second focusing electrode 30 changes in synchronization with the amount of deflection of the electron beam. That is, the quadrupole lens is operated by the quadrupole electrode.

In general, the larger the CRT or the larger the deflection angle, the higher the voltage applied to the second focusing electrode 30 is than the voltage applied to the first focusing electrode 20.

The voltage applied to the second focusing electrode 30 is supplied in a parabolic waveform from a circuit of a TV or a monitor, and is generally applied at a voltage of about 300V to 1000V higher than the voltage applied to the first focusing electrode 20.

That is, when a voltage is applied to the second focusing electrode 30, the four-pole lens is operated by the difference between the voltage applied to the first focusing electrode 20 and the voltage applied to the second focusing electrode 30, thereby operating the electron beam. The shape of the spot is changed into an elongated shape, and acts in a direction to improve the haze 15, which is the upper part of the periphery generated by the non-uniform magnetic field of the deflection yoke through the main lens.

FIG. 6B is a conceptual diagram illustrating a principle in which the path of the electron beam is corrected to match the focal point of the peripheral part when the quadrupole lens is used, and compensates the astigmatism of the deflection yoke by the quadrupole with the same focusing force of the main lens. One state is shown.

The quadrupole lens focuses in the horizontal direction by the divergence force in the horizontal direction of the deflection yoke, and the quadrupole lens diverges in the vertical direction by the amount of focus in the vertical direction of the deflection yoke.

For this purpose, a main lens weakening component (dynamic voltage) is required, which serves to focus the electron beam at any position in the periphery and match in both horizontal and vertical directions as in FIG. 6B.

In this way, the appropriate four-pole lens and the dynamic voltage can ensure that the electron beam has an optimal focusing force at the periphery of the screen.

However, in the conventional electron gun, the focusing voltage applied to the focusing electrode is generally about 20 to 33% of the anode voltage, and the action force of the 4-pole lens formed by the 4-pole electrode is changed according to the voltage applied to the focusing electrode. .

That is, when the focusing voltage ratio is low, the action force of the main lens may be strong and the action force of the quadrupole lens may be weak. However, when the focusing voltage ratio is high, the main lens is weakened and the main lens diameter becomes large. The larger the main lens, the smaller the change in the divergence angle of the electron beam due to the change in the voltage of the second focusing electrode 30. Therefore, the force of the quadrupole lens should be strong. Otherwise, the phenomenon that the electron beam pixel becomes small and becomes large occurs.

In order to improve this phenomenon, the force of the quadrupole lens must be strong, but there was a limit in the conventional method.

In more detail, first, as the variable element, the horizontal width, the vertical length and the thickness of the longitudinal rectangular electron beam through holes 201, 202, and 203 of the first focusing electrode 20, the second focusing electrode 30 also has six types, such as the horizontal width, the vertical length, and the thickness of the horizontal rectangular electron beam through holes 301, 302, and 303.

In order to have the strongest four-pole lens action, the horizontal widths of the vertical rectangular electron beam passing holes 201, 202, and 203 of the first focusing electrode 20 are reduced as much as possible within the range in which they can be assembled. The vertical length of the electron beam passing hole of the first focusing electrode is smaller than the vertical length (l) of the entire first focusing electrode 20 and the size of the parts can be processed. This state is the case where the four-pole lens force is the strongest.

On the other hand, the rectangular rectangular electron beam through-holes 301, 302, 303 it is impossible to configure, which is the pitch of the electron beam through-holes, that is, the rectangular rectangular electron beam through-holes 301, 302, Since the distance between the center and center of 303 is 4.75 mm and the pore diameter is 3.9 mm, the bridge width formed between the electron beam through holes remains only 0.85 mm.

The actual bridge width should be at least 0.5 mm and form the transverse rectangular electron beam through holes 301, 302, 303 in the 0.35 mm range, which is not possible.

Therefore, the conventional electron gun depends on the shape and thickness of the longitudinal rectangular electron beam passing holes 201, 202, and 203 of the first focusing electrode 20.

This alone has a limit to strengthening enough to satisfy the four-pole lens action force when the main lens focusing voltage ratio is high or when the main lens is large in diameter.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and by strengthening the action force of the quadrupole lens to effectively correct the astigmatism according to the deflection amount of the electron beam, in particular the color gun tube electron gun that can improve the resolution at the periphery of the screen The purpose is to provide a focusing electrode.

1 is a cross-sectional view showing a general color water pipe structure

2 is a cross-sectional view showing a schematic structure of the electron gun of FIG.

Figure 3a, 3b is a non-uniform magnetic field of the deflection yoke,

3A is an exemplary view showing a distribution of a pincushion type magnetic field and a shape in which pixels formed by an electron beam are distorted in a horizontal direction;

3B is an exemplary view showing a distribution of a barrel-shaped magnetic field and a shape in which a pixel formed by an electron beam is distorted in a vertical direction.

4A is an exploded view of components of a fin magnetic field

4b is an exploded view of components of a barrel magnetic field;

5A and 5B are exemplary diagrams illustrating a state in which pixels are distorted at the periphery of the screen due to astigmatism.

6a and 6b show the trajectory of the electron beam during deflection of the electron beam by the deflection yoke,

FIG. 6A is a conceptual diagram illustrating a principle in which an electron beam deflected by a deflection yoke generates astigmatism without focusing at the periphery when a quadrupole lens is not used;

6B is a conceptual diagram illustrating a principle in which a path of an electron beam is corrected to match the focus of a peripheral part when using a quadrupole lens;

7 is a cross-sectional view showing a two-divided focusing electrode of a conventional electron gun

8 is a front view illustrating the first focusing electrode of FIG. 7;

FIG. 9 is a cross-sectional view taken along line II of FIG. 8.

FIG. 10 is a front view illustrating the second focusing electrode of FIG. 7.

FIG. 11 is a cross-sectional view taken along line II-II of FIG. 10.

12 is a cross-sectional view showing an electron gun focusing electrode of the present invention.

FIG. 13 is a front view illustrating the first focusing electrode of FIG. 12. FIG.

14 is a cross-sectional view taken along the line III-III of FIG.

FIG. 15 is a front view illustrating the second focusing electrode of FIG. 12.

16 is a cross-sectional view taken along the line IV-IV of FIG.

17 is a front view illustrating the guide inner electrode of FIG. 12.

Explanation of symbols for main parts of the drawings

40: fixed voltage focusing electrode 401, 402, 403: vertical rectangular electron beam through hole

410, 411, 412: vertical flat electrode 42: guide inner electrode

420,421,422: Longitudinal square or circular electron beam through hole of guide inner electrode

4200,4210,4220: Elliptical or keyhole electron beam through hole of guide inner electrode

50: variable voltage focusing electrode 60: correction electrode

600,601,602: Horizontal flat electrode 610,611,612: Circular electron beam through hole

In order to achieve the above object, the present invention focuses on forming a three-pole portion consisting of a plurality of cathodes for emitting an electron beam, a control electrode and an acceleration electrode for controlling the radiation amount of the electron beam, and a main lens for focusing the electron beam on the screen. The electrode and the electron beam are sequentially arranged as an anode for finally accelerating, and when the focusing electrode is divided into two, the constant voltage is applied to one of the focusing electrodes and the variable voltage synchronous to the deflection current is applied to the other focusing electrode. In a color cathode ray tube electron gun in which a dynamic quadrupole lens is formed between two focused electrodes, a plurality of longitudinal rectangular electron beam passing holes are formed in the fixed voltage focusing electrode on the opposite surface of the variable voltage focusing electrode, and the rectangular square electron beam passes. Vertical flat electrodes protrude toward the cathode on both sides of the vertical surface of the ball, and inside the fixed voltage focusing electrode A guide inner electrode having an elongated rectangular or circular electron beam through hole is inserted, and a plurality of circular electron beam through holes and a plurality of circular electron beam through holes and upper and lower portions of each of the circular electron beam through holes are inserted into the variable voltage focusing electrodes on the opposite surface of the fixed voltage focusing electrode. It is a focusing electrode of an electron gun for a color cathode ray tube which is attached to a square plate-shaped correction electrode having a horizontal plate electrode protruding toward the cathode vertically.

Hereinafter, an embodiment of the present invention will be described in detail with reference to FIGS. 12 to 17.

12 is a cross-sectional view showing an electron gun focusing electrode of the present invention, FIG. 13 is a front view showing a first focusing electrode of FIG. 12, FIG. 14 is a cross-sectional view showing a line III-III of FIG. 13, and FIG. FIG. 16 is a cross-sectional view illustrating the IV-IV line of FIG. 15, and FIG. 17 is a front view of the guide inner electrode of FIG. 12.

The present invention is to enhance the action of the four-pole lens, the first focusing electrode for a color cathode ray tube of the present invention disposed after the three-pole portion that is an electron beam forming portion for generating three electron beams to focus the electron beam is a first applied voltage A focusing electrode (fixed voltage focusing electrode) 40 and a second focusing electrode (variable voltage focusing electrode) disposed after the first focusing electrode 40 and to which a variable voltage is applied in accordance with the deflection amount of the electron beam by the deflection yoke. 50).

In this case, a plurality of rectangular rectangular electron beam passing holes 401, 402, and 403 are formed in the first focusing electrode 40, which is a fixed voltage focusing electrode on the opposite surface of the second focusing electrode 50, which is a variable voltage focusing electrode. And vertical flat electrodes 410, 411, and 412 are projected toward the cathode on both sides of the vertical planes of the vertical rectangular electron beam passing holes 401, 402, and 403. The guide inner electrode 42 having four elongated rectangular or circular electron beam through holes 420, 421, and 422 is inserted.

The shape of the electron beam through hole of the guide inner electrode 42 is formed to form a longitudinal rectangle 420, 421, 422 (FIG. 17A), but has circular shapes 420, 421, and 422. 17B, or a vertical elliptical shape 4200, 4210, 4220 or 1720 with a length of the vertical axis longer than the length of the axis in the horizontal direction, or formed at the center thereof. It is also possible to enhance the action force of the quadrupole lens to form a longitudinal key-hole shape 4200, 4210, 4220 (FIG. 17D), which is a combination of circular holes.

In addition, a square plate-shaped correction electrode 60 is attached to the second focusing electrode 50 on the opposite surface of the first focusing electrode 40, and the square plate-shaped correction electrode 60 includes a plurality of circular electron beam passing holes ( 610, 611, and 612, and horizontal flat electrodes 600, 601, and 602 projecting in the vertical direction with respect to the flat surface above and below each circular electron beam passing hole.

The electrodes are a basic configuration forming a dynamic quadrupole lens.

In addition, the horizontal flat electrodes 600, 601, and 602 of the correction electrode 60 attached to the second focusing electrode 50 may have an elongated rectangular electron beam passing hole formed in the first focusing electrode 40. 401, 402, 403 is installed and configured to be inserted into.

In addition, the vertical plate electrode formed on the outer vertical surface of the electron beam through holes 401 and 403 formed on the outside of the vertical rectangular electron beam through holes 401, 402, and 403 of the first focusing electrode 40. 410 and the length of the vertical plate electrodes 411 and 412 formed on the inner vertical surface of the outer electron beam passing hole so as to face the vertical plate electrode 410 are formed to be different from each other. The length of the vertical square electrodes 410, 411, and 412 of the vertical rectangular electron beam through holes 401, 402, and 403 of the first focusing electrode 40, which is the voltage focusing electrode, is toward the cathode side. The vertical plate electrode 410 formed on the outer vertical surface is formed to be longer than the length of the vertical plate electrodes 411 and 412 formed on the inner vertical surface so as to face the vertical plate electrode 410.

Meanwhile, the circular electron beam through holes 610, 611, and 612 of the correction electrode 60 may be formed as a horizontal rectangular electron beam through hole instead of a circle.

Design values for each component of the present invention can be obtained through computer three-dimensional simulation, the process is as follows.

The quadrupole lens operates by a potential difference when the fixed voltage is about 300 to 1000 V lower than the variable voltage. The quadrupole lens corrects the astigmatism by generating a correction field in the quadrupole lens as much as the astigmatism generated when the electron beam is deflected toward the periphery of the screen. There is a number.

In the computer 3D simulation method, the center, top, edge, and corner portions of the screen are displayed in a non-dynamic state in which astigmatism correction means do not operate. Measure the focus voltage (V _foc ) at the

Here, the non-dynamic state refers to a state when a voltage having the same magnitude is simultaneously applied to the first focusing electrode 40 to which the fixed voltage is applied and the second focusing electrode 50 to which the variable voltage is applied.

In this non-dynamic state, when the focus voltage of the center, top, edge, and corner portions of the screen is measured, the horizontal focus voltage at each point remains almost constant, and the focus voltage for the vertical direction is center, top, and edge. , It changes exponentially in corner order.

Therefore, since the horizontal focus voltage in the horizontal direction is maintained almost constant regardless of the position on the screen, the vertical focus voltage in the vertical direction that changes exponentially in the non-dynamic state is excluded from the aberration component to be improved. We design a dynamic quadrupole lens that can correct vertical aberration components using.

To do this, the focus voltage at each point is measured and this value is used as simulation data.

, 화면 에지 일지점에서의 포커스 전압에서 센터의 포커스 전압을 뺀 값을

, 화면 코너 일지점에서의 포커스 전압에서 센터의 포커스 전압을 뺀 값을

라고 할 때, 이들 값, 즉,

,

,

이 최종적으로 개선해야 할 편향요크의 수차 성분이 된다.That is, subtract the focus voltage of the center from the focus voltage at each screen top point.

, The focus voltage at the screen edge point minus the focus voltage of the center.

, The focus voltage at the screen corner point minus the center focus voltage

, These values, i.e.

,

,

This becomes the aberration component of the deflection yoke to be finally improved.

(화면 센터에서의 집속 전압),

,

,

을 컴퓨터에 입력하여 주렌즈 출구(즉, 양극 전극 끝단)에서의 전자빔 반경, 발산각, 초점거리를 각각의 경우에 대하여 구하게 된다.In a non-dynamic state like this,

(Focusing voltage at screen center),

,

,

Is input to a computer to obtain the electron beam radius, divergence angle and focal length at the main lens exit (i.e., the anode electrode end) in each case.

,

,

값으로부터 컴퓨터를 이용하여 산출한 톱, 에지, 코너의 측정지점에 대한 전자빔 반경, 발산각, 초점거리를 말하며, 각각의 경우에 대해 구해진 전자빔 반경, 발산각, 초점거리는 다이나믹 상태에서의 수차 보정을 위한 기본 목표치로 삼게 된다.Here, each case is obtained by measuring the top, edge and corner

,

,

The value refers to the electron beam radius, divergence angle, and focal length for the measured points of the top, edge, and corner computed from the computer.The electron beam radius, divergence angle, and focal length calculated for each case are used to correct It will be used as the basic target for this.

On the other hand, after obtaining aberration components such as electron beam radius, divergence angle and focal length by using a computer in the non-dynamic state as described above, when the dynamic voltage is applied to the second focusing electrode 50, the electron beam radius and divergence are obtained. The dimensions and shape of the focusing electrode are designed through computer simulation so that the focal length is equal to the non-dynamic state.

,

,

값들의 1/2 정도가 되도록 한다.At this time, the variable voltage (dynamic voltage) applied to the second focusing electrode 50 must be finally improved.

,

,

It should be about half of the values.

The changes in the effects of the focusing and diverging effects on the horizontal and vertical components of the electron beam according to the dimensional change of the first and second focusing electrodes of the present invention obtained through the simulation are shown in the table below.

TABLE 1

In the above table, it can be seen that the vertical lengths of the vertical rectangular electron beam through holes 401, 402, and 403 of the first focusing electrode 40 have no effect on the vertical component of the electron beam. That is, the horizontal flat electrodes 600, 601, and 602 of the correction electrode 60 having a constant gap between the upper and lower side plates are vertical rectangular electron beam through holes 401, 402, and 403. Since the vertical component of the electron beam is influenced only by the horizontal flat electrodes 600, 601, and 602, the vertical components of the longitudinal rectangular electron beam through holes 401, 402, and 403 are vertically moved. This is because the length of is not affected by the change.

In addition, the length of the outer side of the outer electron beam passing hole among the vertical plate electrodes 410, 411, and 412 protruding into the first focusing electrode 40 is longer than that of the inner side, so that the variable (dynamic) voltage is increased. When applied, the convergence force of the outer electron beam is reduced to prevent a phenomenon in which a convergence error occurs in the peripheral portion.

If the length of the vertical plate electrode 410 outside the outer longitudinal rectangular electron beam passing hole 401 in the direction of the cathode is long, it is over convergence, whereas if it is long, under convergence is under convergence. do.

In order to improve this, the length of the vertical plate electrode 410 of the outer vertical rectangular electron beam passing hole 401 is set to be 0.5 mm longer than the inner vertical plate electrodes 411 and 412.

On the other hand, the schematic design dimensions of the above-described focusing electrode components of the present invention are as follows.

* First focusing electrode

· Horizontal width of long hole: 3.90mm

Longitudinal width of long hole: 6.50mm

Length of slot: 0.4mm

Vertical flat electrode height (inside): 1.0mm

Vertical plate electrode height (outer side): 1.5 mm

Electron beam through hole of guide inner electrode: 3.90mm

* Second focusing electrode

Compensation electrode diameter: 3.90mm

The length of the cathode side of the horizontal plate electrode of the calibration electrode: 2.00 mm

Calibration electrode thickness: 0.4mm

As described above, the present invention enhances the four-pole lens action force to more effectively correct the astigmatism according to the deflection amount of the electron beam.

In particular, it is possible to improve the resolution of the screen by preventing distortion of the beam spot at the periphery of the screen, thereby providing a better quality image.

Claims (6)

A three-pole portion comprising a plurality of cathodes emitting an electron beam, a control electrode and an acceleration electrode for adjusting the radiation amount of the electron beam, a focusing electrode forming a main lens for focusing the electron beam on the screen, and an anode for finally accelerating the electron beam A dynamic quadrupole lens disposed between the divided two focused electrodes when a constant voltage is applied to one of the focused electrodes and a variable voltage synchronized with a deflection current is applied to the other focused electrodes. In the electron gun for color cathode ray tube, A plurality of longitudinal rectangular electron beam passing holes are formed in the fixed voltage focusing electrode on the opposite surface of the variable voltage focusing electrode, Vertical flat electrodes protrude toward the cathode on both sides of the vertical plane of the longitudinal rectangular electron beam passing hole, A guide inner electrode having an elongated rectangular electron beam through hole is inserted into the fixed voltage focusing electrode. In the variable voltage focusing electrode on the opposite surface of the fixed voltage focusing electrode, a plurality of circular electron beam through-holes and correction electrodes having a plate-shaped horizontal flat electrode are formed on the upper and lower portions of the circular electron beam through-holes to protrude in a vertical direction with respect to the flat surface. Become, And a horizontal flat electrode of the correction electrode attached to the variable voltage focusing electrode is inserted into the vertical rectangular electron beam passing hole formed in the fixed voltage focusing electrode. The method of claim 1, A vertical plate electrode formed on an outer vertical surface of an electron beam passing hole formed outside of the horizontal rectangular electron beam passing hole of the fixed voltage focusing electrode, and toward a cathode of a vertical plate electrode formed on an inner vertical surface of the outer electron beam passing hole so as to face the vertical plate electrode; Focusing electrode of the electron gun for a color cathode ray tube, characterized in that the length of the formed different. The method of claim 2, The length of the fixed voltage focusing electrode of the horizontal rectangular electron beam pass-through hole toward the cathode of the vertical plate electrode is longer than the length of the vertical plate electrode formed on the inner vertical surface so that the vertical plate electrode formed on the outer vertical surface is opposed thereto. Focusing electrode of electron gun for color cathode ray tube. The method of claim 1, Focusing electrode of the electron gun for the color cathode ray tube, characterized in that the shape of the electron beam through hole of the guide inner electrode formed in the fixed voltage focusing electrode has a longitudinal ellipse, the length of the axis in the vertical direction is longer than the length of the axis in the horizontal direction. The method of claim 1, The shape of the electron beam through hole of the guide inner electrode formed inside the fixed voltage focusing electrode forms an elongated key-hole, which is a combination of an elongated rectangular through hole and a circular hole protruding in a horizontal direction in the center thereof. Focusing electrode of electron gun for color cathode ray tube. The method of claim 1, The focusing electrode of the electron gun for color cathode ray tube, characterized in that the shape of the electron beam through hole of the correction electrode is a horizontal rectangular.

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