KR19990038061A - Electron gun for colored cathode ray tube - Google Patents

Abstract

The present invention relates to an electron gun for a color cathode ray tube, and the use of a high current amount according to the high brightness demand of the screen while compensating for the deterioration of the electron beam spot due to the larger deflection force toward the screen periphery due to the larger size and higher definition of the CRT. The problem of spot deterioration due to an increase in space charge repulsion at the three-pole portion caused by an increase is solved at the same time.

To this end, a tripolar lens consisting of a cathode 1 for emitting an electron beam 2, at least two electrodes for adjusting the radiation amount of the electron beam and accelerating the electron beam to the screen side, and at least two for focusing a predetermined amount of the electron beam In the electron gun for color cathode ray tubes composed of a prefocus lens unit configured as described above and at least two electrodes forming a main lens for focusing the electron beam on the screen, the first electrode 114 facing the second electrode 115. A longitudinal depression 114a having a vertical direction longer than the horizontal direction is formed at the periphery of at least one of the three electron beam through holes formed on the plane), and the second electrode 115 facing the first electrode 114. In the peripheral portion of at least one of the three electron beam through holes formed on the plane), a horizontal recessed portion 115a having a horizontal direction longer than the vertical direction is formed, and the prefocus lens is The electron beam through hole 116a formed in the at least one electrode is a vertical rectangular hole 116b having a vertical direction longer than the horizontal direction, and a circular hole 116c having a pore larger than the horizontal width of the square hole and smaller than the vertical width. ) Is formed in the shape of an elongated keyhole.

Description

Electron gun for colored cathode ray tube

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for color cathode ray tubes, and more particularly to a structure of first and second electrodes forming a tripolar portion and a third electrode forming a prefocus portion.

1 is a cross-sectional view of a typical color cathode ray tube, in which each electrode of the electron gun for a color cathode ray tube is controlled so that the electron beam 2 emitted from three cathodes 1 is controlled in a constant intensity to reach the fluorescent surface 3. In order to be perpendicular to the path through which the electron beam (2) passes, they are arranged in-line at regular intervals.

The configuration is described in more detail with reference to FIG. 1 as follows.

Three cathodes (1) arranged horizontally and side by side independently from each other, a first electrode (4) arranged to maintain a constant distance from the cathode to control hot electrons generated from the cathode, and a constant distance from the first electrode A second electrode 5 which serves to draw out and accelerate the hot electrons collected on the surface of the electron-emitting material of the cathode (not shown), and the third electrode 6, the fourth electrode 7, The fifth electrode 8 and the sixth electrode 9 are arranged in this order, and one side of the sixth electrode (the traveling direction side of the electron beam) serves as the ground with the graphite film 11 coated on the inner surface of the funnel 10. At the same time, a shield cup 13 having a plurality of shield springs 12 fixed to the center of the neck portion 10a is fixed to the electron gun.

Different voltages are applied to the cathode 1 in order to obtain a constant current value such that the cut-off voltage of each electron gun is the same.

Therefore, when power is applied from the stem pin 15 to the heater 14 in the cathode 1 constituting the triode of the electron gun, when the heater generates heat, the hot electrons are emitted from the electron emission material applied to the tip of the cathode.

The hot electrons emitted as described above are controlled by the first electrode 4 serving as the control electrode and accelerated by the second electrode 5 serving as the acceleration electrode (three-pole lens: 16 in FIG. 5B) and the second and third electrodes 5. Slightly focused by a prefocus lens (18 in FIG. 5B) formed by a lens formed between the lens 6 and the third, fourth and fifth electrodes 6, 7 and 8. The fifth and sixth electrodes 8 and 9, which are formed electrodes, are sequentially passed.

The electron beam accelerated and focused while passing through the electrodes passes through the shadow mask 20, which is installed to be maintained at a predetermined distance from the fluorescent surface 3 and serves as color screening, and then impinges on the fluorescent surface 3 to emit the fluorescent surface 3. The screen is reproduced.

In the above operation, the deflection yoke 21 provided on the outer peripheral surface of the neck portion 10a of the funnel 10 deflects the electron beam 2 emitted from the electron gun to the entire fluorescent surface 3.

FIG. 2 is an exploded perspective view showing a partially cut in-line electron gun, and the transverse direction of the electron beam through hole 5a of the second electrode 5 opposite to the third electrode 6 is smaller than the in-line direction as shown in FIG. 4A. The long depression 5b is formed.

As such, the depression 5b formed in the second electrode 5 is referred to as a “slot”, and this slot is used to asymmetrically form a lens formed by a potential difference between the second and third electrodes 5 and 6. Play a role.

In general, the voltage applied to the second electrode 5 is about 400 to 1,000 V, and the voltage applied to the third electrode 6 is about 6,000 to 10,000 V.

In the electron guns applied to the colored cathode ray tube, openings 8a and 9a through which the three electron beams pass in common are shown in the fifth and sixth electrodes 8 and 9, and a predetermined distance therefrom. Electrostatic field control electrode bodies 22 and 23 are provided at the retracted position.

The above-described structure functions to expand the size of the main lens and forms an asymmetric main lens having a stronger focusing force of the lens than the direction in which the inline direction is perpendicular thereto, so that the diff is generated when the electron beam is deflected by the deflection yoke 21. It reduces the deterioration of the electron beam due to the retraction defocusing phenomenon.

In US Pat. No. 4,641,058 shown in FIG. 4, the depression 5b formed in the inline direction is formed on the surface of the second electrode 5 facing the third electrode 6 so that the electron beam emitted from the cathode 1 ( 2), an asymmetric prefocus lens 18 having a smaller lens intensity in the horizontal direction is smaller than that in the vertical direction, and is incident on the main lens 19 side as an electron beam having a horizontal shape larger than the vertical direction.

The above is described in more detail as follows.

The horizontal direction of the prefocus lens 18 formed by the recessed portion 5b of the second electrode 5 weakens the intensity of the lens to focus the electron beam 2 small, and the vertical direction has a strong lens strength to generate the electron beam. As a result of large focusing, a horizontal electron beam is formed.

The reason for the horizontal lengthening of the electron beam is to reduce the spherical aberration of the main lens 19 formed between the fifth and sixth electrodes 8 and 9 with respect to the vertical direction while deflecting with the asymmetric main lens of FIG. When the electron beam is deflected by the non-uniform deflection magnetic field 24 by the focusing phenomenon and the use of the amplifier convergence deflection yoke, the focusing force is decreased in the horizontal direction, and the focusing force is strong in the vertical direction to compensate for the deterioration of the electron beam.

When the compensation of the deflection defocusing phenomenon is described in more detail, when the horizontal electron beam is focused on the fluorescent surface 3 through the main lens 19, the horizontal focusing distance is longer than that in the vertical direction, and thus the horizontal focusing is performed. Since the distance is shorter than the vertical direction, the deflection defocusing phenomenon generated by the non-uniform deflection magnetic field 24 when deflected by the deflection yoke 21 is compensated.

The asymmetric prefocus lens 18 formed by the recessed portion 5b formed in the second electrode 5 forms an elongated electron beam 2 whose horizontal direction is smaller than the vertical direction. Compensating for the horizontalization of the generated electron beam.

Therefore, when the electron beam is deflected to the periphery of the screen, the amount of lateralization is reduced to maintain a nearly circular shape, resulting in the improvement of focus due to the reduction of the horizontal spot diameter at the periphery and the increase of the vertical spot at the periphery of the screen. Moire is less likely to occur, thereby improving resolution.

However, in recent years, the use of screen technology or dark tint glass for high brightness and contrast enhancement has led to an increase of about 20% of the current used in the electron gun.

Accordingly, a problem arises in that the spot size on the screen increases due to an increase in the space charge repulsion force due to an increase in current density at the electron beam crossover portion of the triode.

In particular, in the electron gun technique of forming an asymmetric lens on the prefocus lens formed between the second and third electrodes 5 and 6, the problem of the increase in the space charge repulsion force in the triode is solved as described above. Can't.

5A and 5B briefly illustrate the lens action of the rotationally symmetrical electron gun and the focusing state of the electron beam. In the center portion of the screen where the electron beam is not deflected, the tripolar lens 16, the prefocus lens 18, and the main lens are shown. A circular spot 25 can be realized by the lens 19, but when deflected to the periphery of the screen, the electron beam is caused by the non-uniform deflection magnetic field 24 generated in the deflection yoke. And the hollow 27 (HOLO) that degrades the resolution, the deviation of the resolution is very large between the center portion and the periphery of the screen, thereby lowering the focus uniformity of the screen.

However, in the rotating asymmetric electron gun shown in Figs. 6A and 6B, the longitudinal direction of the screen is smaller than the vertical direction at the center of the screen by the asymmetric tripolar lens 16, the prefocus lens 18 and the asymmetric main lens 19. Although the spot 28 is formed, when the electron beam is deflected to the periphery of the screen, the asymmetric prefocus lens and the main lens partially compensate for the influence of the non-uniform deflection magnetic field 24 generated in the deflection yoke 21. The hollow 30 is reduced while increasing the core portion 29 than the rotationally symmetric electron gun in the peripheral portion.

Therefore, since the resolution deviation between the center and the peripheral portion of the screen can be reduced, it is possible to improve the focus uniformity over the entire screen.

In response to the recent demand for larger and more detailed CRTs, the deflection force toward the periphery of the screen is increased, thereby compensating for the deterioration of the electron beam spot, and the space charge repulsion at the tripolar portion caused by the increased use of a high amount of current according to the demand for high brightness of the screen. As the phenomenon increases, the spot deterioration problem must be solved at the same time.

However, the electron gun as described above can compensate for the deterioration of the spot due to deflection, but the spot deterioration due to the increase in the space charge repulsion force at the triode is difficult to compensate, and thus, the small spot on the screen cannot be realized.

The present invention has been made to solve such a problem of the prior art, the higher the brightness of the screen while compensating for the phenomenon that the deflection of the electron beam spot is increased due to the larger deflection force toward the screen periphery in accordance with the demand for larger and higher resolution of the CRT. The purpose of the present invention is to solve the problem of spot deterioration due to an increase in space charge repulsion at the triode caused by an increase in the use of a high amount of current according to a request.

According to an embodiment of the present invention for achieving the above object, a tripolar lens unit consisting of a cathode for emitting an electron beam, at least two electrodes for adjusting the radiation amount of the electron beam and accelerate the electron beam to the screen side, and the electron beam An electron gun for a color cathode ray tube composed of at least two prefocus lenses comprising at least two focusing a predetermined amount of light and a main lens for focusing the electron beam on the screen. Longitudinal depressions having a vertical direction longer than the horizontal direction are formed in the periphery of at least one of the three electron beam through holes formed on one electrode surface, and three electron beam through holes formed on the second electrode surface facing the first electrode. In the periphery of at least one or more electron beam through hole is formed a horizontal depression longer than the vertical direction, The electron beam through hole formed in at least one electrode forming the prefocus lens has a vertical square hole having a vertical direction longer than the horizontal direction and a circular hole having a hole having a pore larger than the horizontal width of the square hole and smaller than the vertical width. An electron gun for a color cathode ray tube formed in a long keyhole shape is provided.

1 is a cross-sectional view showing a typical colored cathode ray tube

2 is an exploded perspective view showing a partially cut in-line electron gun

Figure 3 is a perspective view showing a part of the large-diameter main lens cut out

4A and 4B are perspective views showing a part of the conventional second and third electrodes.

5A and 5B are schematic diagrams showing a focused state of an electron beam in a rotationally symmetric electron gun;

6A and 6B are schematic diagrams showing a focused state of an electron beam in a rotating asymmetric electron gun;

7A to 7C are perspective views of first, second and third electrodes showing an embodiment of the present invention.

8A to 8C are perspective views of first, second and third electrodes showing another embodiment of the present invention.

9a and 9b are graphs showing the comparison of the lens action in the electron gun of the prior art and the present invention

Explanation of symbols for main parts of the drawings

1 cathode 114 first electrode

114a, 115a: depression 114b, 115b, 116b: square hole

114c, 115c, and 116c: circular hole 116: third electrode

116a: electron beam passing hole

Hereinafter, with reference to the accompanying Figures 7 to 9 showing the present invention in each embodiment will be described in more detail as follows.

7A to 7C are perspective views of the first, second and third electrodes showing one embodiment of the present invention, and FIGS. 8A to 8C are perspective views of the first, second and third electrodes showing another embodiment of the present invention.

Referring to FIGS. 7A to 7C, which are illustrated as an embodiment of the present invention, an elongated recess having a vertical direction longer than a horizontal direction in the periphery of the electron beam through hole on the surface of the first electrode 114 facing the second electrode 115 is shown. And forming a recessed portion 115a having a horizontal direction longer than the vertical direction at the periphery of the electron beam through hole on the surface of the second electrode 115 facing the first electrode 114. The electron beam through hole 116a on the surface of the third electrode 116 facing 115 has a square hole 116b having a vertical direction longer than the horizontal direction, and a larger than the horizontal width of the square hole at the center of the square hole and having a vertical direction. The circular hole 116c smaller than the width is formed in the shape of an elongated key-hole.

At this time, the electron beam passing holes of the first electrode 114 and the second electrode 115 are configured as square holes 114b and 115b.

8A to 8C show another embodiment of the present invention, which is different from an embodiment in that the electron beam through hole formed in the first electrode 114 and the second electrode 115 is formed in a circular hole 114c ( 115c).

The first electrode 114, the second electrode 115, and the third electrode 116 applied to the above embodiments maintain a constant interval and are fixed to the bead glass so that different potentials are applied to each other. 0 V (zero volts) is applied to the 114, 260 to 1,000 V is applied to the second electrode 115, and 6,000 to 9,000 V is applied to the third electrode 116. 16 and an asymmetric prefocus lens 18 are formed.

Referring to the operation of the present invention configured as described above is as follows.

First, when power is applied and an electron beam is radiated from the cathode and scanned to the screen side, the second recess 115a and the second electrode 115 formed on the opposite surface of the second electrode 115 of the first electrode 114 are first formed. The horizontal action of the tripolar lens 16 is weaker than that of the vertical direction by the horizontal depression 115a formed on the opposite surface of the first electrode 114, thereby reducing the first and second electrodes 114 and 115. The passing electron beam is horizontalized.

In addition, as shown in FIG. 9B, even in a lens action in which the tripolar lens penetrates into the electron beam through hole of the first electrode 114 and draws out electrons formed on the cathode, the vertical direction is stronger than the horizontal direction. The crossover 31 is located closer to the cathode than the crossover 32 in the vertical direction.

Therefore, since the crossovers 33 and 34 are formed at the same position in the horizontal direction and the vertical direction of the three-pole portion of the conventional electron gun as shown in FIG. 9A, the current density at the crossover portion is increased to increase the space charge repulsion force, thereby increasing the spot. The deterioration phenomenon can be compensated for.

In addition, the horizontal direction of the prefocus lens 18 has a weaker action than the vertical direction by the electron beam passing hole 116a formed in the third electrode 116 in a keyhole shape, and thus the shape of the electron beam passing through the prefocus lens 18. Since this sidewall is reduced, the spherical aberration of the main lens formed between the fifth electrode 8 and the sixth electrode 9 is reduced with respect to the vertical direction while compensating for deflection defocusing with the asymmetric main lens shown in FIG. 3. do.

In other words, when the horizontally focused electron beam is focused on the screen through the main lens, the horizontal focusing distance is formed longer than the vertical direction, and the focusing distance in the vertical direction is shorter than the focusing distance in the horizontal direction. The deflection defocusing caused by the non-uniform deflection magnetic field 24 when the deflection is caused by the deflection is compensated.

When the electron beam passing holes of the first electrode 114 and the second electrode 115 are configured as square holes 114b and 115b as in one embodiment of the present invention, the circular holes 114c ( The surface area of the first electrode 114 which affects the radiation area of the electron beam while reducing the horizontal and vertical diameters of the electron beam through hole of the first electrode 114 which directly affects the spot diameter on the screen compared to 115c). Since it is possible to keep the same, the spot diameter on the screen can be reduced, and the lifetime of the cathode can be obtained to have the same characteristics.

As described above, the present invention compensates for the deterioration of the electron beam spot due to the greater deflection force toward the peripheral portion of the screen, and increases the space charge repulsion phenomenon in the tripolar portion generated due to the increase in the use of a high current amount according to the high brightness demand of the screen. The problem of spot deterioration due to the problem can be solved at the same time, so it is possible to simultaneously obtain a small spot on the screen and uniform focus characteristics in the entire area of the screen.

In other words, by reducing the space charge repulsion at the triode, it is possible to reduce the spot size on the screen while simultaneously compensating for the spot degradation at the periphery of the screen due to the deflection magnetic field caused by deflection. A uniform spot can be obtained.

Claims (3)

A tripolar lens consisting of a cathode for emitting an electron beam, at least two electrodes for adjusting the radiation amount of the electron beam and accelerating the electron beam to the screen side, a prefocus lens portion consisting of at least two or more for focusing the electron beam a predetermined amount; In the electron gun for color cathode ray tube composed of two or more electrodes forming a main lens for focusing the electron beam on the screen, at least one electron beam of the three electron beam through holes formed on the first electrode surface facing the second electrode Longitudinal depressions in which the vertical direction is longer than the horizontal direction are formed in the periphery of the through-hole, and the horizontal direction is formed in the periphery of the at least one electron beam through-hole in at least one of the three electron beam through-holes formed in the second electrode surface facing the first electrode. A long horizontal depression is formed and is formed on at least one electrode forming the prefocus lens. Electron beam passage hole is a vertically long rectangular jongjang ball, color cathode-ray tubes the electron gun formed in the shape of a keyhole with a circular longitudinal elongated holes mutually coupled with a small opening diameter greater than the vertical width than the horizontal width of the rectangular hole than the horizontal direction. The method of claim 1, An electron gun for a color cathode ray tube, wherein the electron beam passing holes formed in the first and second electrodes are square holes. The method of claim 1, An electron gun for a color cathode ray tube, wherein the electron beam passing hole formed in the first and second electrodes is a circular hole.