KR100223842B1 - Electron gun for cathode ray tube - Google Patents

Abstract

The present invention relates to an electron gun for a color cathode ray tube, which compensates for the deterioration of the electron beam spot deterioration due to a larger deflection force in a large CRT and a space in the triode due to the use of a high current amount according to the high luminance demand of the screen. Spot deterioration caused by increased charge repulsion is prevented in advance.

To this end, an elongated recess 4b having a horizontal direction smaller than the vertical direction is formed around at least one or more electron beam through holes formed in the first electrode 4 in the electrode forming the tripolar lens. However, the thickness of the first electrode 4 is 0.25 mm or less, and the depth of the depression 4b is in the range of 40 to 70% of the thickness of the first electrode, and among the electron beam through holes formed in the second electrode 5. On the periphery of at least one electron beam through hole facing the first electrode, a horizontal depression 5d having a horizontal direction larger than the vertical direction is formed, and the depression 5d formed on the second electrode 5 is formed. The depth is set in the range of 50 to 80% of the thickness of the second electrode.

Description

Electron gun for color 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 three pole portion.

1 is a cross-sectional view of a conventional color cathode ray tube, in which each electrode of the electron gun for a color cathode ray tube controls the electron beam 2 emitted from the three cathodes 1 in a constant intensity form and then reaches the fluorescent surface 3. To this end, the electron beams 2 are arranged in-line at regular intervals from each other so as to be perpendicular to the path through which the electron beam 2 passes.

In more detail, the three cathodes (1) arranged in parallel with each other horizontally and independently of each other, the first electrode (4) arranged to maintain a predetermined distance from the cathode to control the hot electrons generated in the cathode, and the first A second electrode 5 arranged to maintain a predetermined distance from the first electrode and serving to accelerate and accelerate hot electrons gathered 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) is coated on the inner surface of the funnel 10. A shield cup 13 having a plurality of shield springs 12 fixed thereon to serve as a grounding with (11) and supporting the electron gun at the center of the neck portion 10a is disposed.

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, heat electrons are emitted from the electron emission material applied to the distal end 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 by the prefocus lens (17 in FIG. 5B) formed between the (6) and the prefocus lens (18 in FIG. 5B) formed by the third, fourth and fifth electrodes 6, 7 and 8 After focusing, the light passes through the fifth and sixth electrodes 8 and 9, which are electrodes for forming the main lens 19.

The electron beam accelerated and focused while passing through each electrode is installed to be maintained at a predetermined distance from the fluorescent surface 3, passes through a shadow mask 20 that performs color selection, and then impinges on the fluorescent surface 3 to emit light. This is reproduced.

In the operation as described above, the deflection yoke 21 installed on the outer peripheral surface of the neck portion 10a of the funnel 10 is emitted from the electron gun and deflects the electron beam 2 moving toward the fluorescent surface 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. A long depression 5b is formed, or as shown in FIG. 4B of US Pat. No. 4,641,058, the vertical direction is more perpendicular to the electron beam through hole 6a of the third electrode 6 opposite to the second electrode 5. A larger longitudinal depression 6b is formed.

Thus, the recesses 5b and 6b formed in the second and third electrodes 5 and 6 are commonly referred to as slots, which are formed by the potential difference between the second and third electrodes 5 and 6. Serves to asymmetrically form the lens.

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.

The fifth and sixth electrodes 8 and 9 of the electron gun applied to the color cathode ray tube have openings 8a and 9a through which three electron beams pass in common, as shown in FIG. Electrostatic field control electrode bodies 22 and 23 are respectively provided at the point where they become.

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 recessed portion 5b or the third electrode facing the second electrode 5 is formed long in the in-line direction on the surface of the second electrode 5 facing the third electrode 6. There is a depression 6b having a long vertical direction with respect to the inline direction formed on the (6) surface, so that the electron beam 2 emitted from the cathode 1 has an asymmetry of which the lens intensity in the horizontal direction is smaller than that in the vertical direction. By the prefocus lens 17, the horizontal direction becomes an electron beam having a horizontal shape larger than the vertical direction, and is incident to the main lens 19 side as shown in FIG. 5A.

The above is described in more detail as follows.

The horizontal direction of the prefocus lens 17 formed by the recessed portion 5b of the second electrode 5 and the recessed portion 6b of the third electrode 6 weakens the intensity of the lens, thereby The focusing is small, and the lens direction is strong in the vertical direction, so that the electron beam is focused largely, thus forming a horizontal electron beam.

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 adoption of the yoke convergence deflection yoke, the horizontal direction has a low focusing force, and the vertical direction has a strong focusing force to compensate for the deterioration of the electron beam. To do this.

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.

In addition, the asymmetric prefocus lens 17 formed by the recesses 5b and 6b formed in the second and third electrodes 5 and 6 has an elongated electron beam of which the water point size of the electron beam is smaller than the vertical direction. 2) to compensate for the lateralization of the electron beam generated at the periphery of the screen.

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, due to the use of screen coating technology or dark tint glass for high brightness and contrast enhancement, the main current amount of the electron gun increases by about 20%.

Accordingly, even in the electron gun, since the current density at the electron beam crossover portion of the triode increases, the spot size increases on the screen due to an increase in the space charge repulsion force.

In particular, in the electron gun which forms the asymmetric lens in the prefocus lens between the second and third electrodes 5 and 6, it is impossible to solve the phenomenon of increasing the space charge repulsion force in the triode as described above.

5A and 5B are schematic diagrams showing a focused state of an electron beam in a rotationally symmetric electron gun. In the center portion of the screen where the electron beam is not deflected, circular spots 25 may be realized as shown in FIG. When deflected, the electron beam exhibits a horizontal core portion 26 and a hollow 27 deteriorating the resolution by the non-uniform deflection magnetic field 24 generated in the deflection yoke as shown in FIG. 5B. As a result, the resolution deviation between the center and the periphery of the screen is very severe, resulting in deterioration of focus uniformity.

However, in the rotationally asymmetric electron gun shown in Figs. 6A and 6B, an asymmetric prefocus lens 17 and an asymmetric main lens 19 are used to form a longitudinal spot 28 whose horizontal direction is smaller than the vertical direction as shown in Fig. 6A in the center of the screen. Is formed, but when the electron beam is deflected toward 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. As described above, the hollow 30 is reduced while increasing the core portion 29 than the rotationally symmetric electron gun.

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.

However, such a conventional electron gun can compensate for the degradation of the spot due to deflection to some extent, but the spot degradation due to the increase of the space charge repulsion force in the triode cannot be compensated, and thus a small spot cannot be obtained on the screen.

The present invention has been made to solve such a problem in the prior art, the use of a high current amount in accordance with the high brightness requirements of the screen while compensating for the phenomenon that the deflection of the electron beam spot is increased due to the greater deflection force from the large CRT to the periphery of the screen. Therefore, the purpose is to prevent the phenomenon of spot deterioration due to the increase of space charge repulsion in the triode.

According to an embodiment of the present invention for achieving the above object, 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 to 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 configured to focus a predetermined amount and two or more electrodes forming a main lens for focusing the electron beam on a screen, wherein the three-pole lenses are formed. An elongated recess having a horizontal direction smaller than the vertical direction is formed around at least one electron beam through hole formed in the first electrode in the electrode, but the thickness of the first electrode is 0.25 mm or less and the depth of the recess is It is in the range of 40 to 70% of the thickness of the first electrode, and it is opposed to the first electrode in the electron beam through hole formed in the second electrode. At least one electron beam through-hole is formed in the periphery of the horizontal direction is larger than the vertical direction to form a depression, the depth of the depression formed in the second electrode is set to be set to 50 to 80% of the thickness of the second electrode An electron gun for a color cathode ray tube is provided.

1 is a cross-sectional view showing a typical color 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 rotationally asymmetric electron gun;

7A and 7B are perspective views of first and second electrodes showing an embodiment of the present invention.

8A and 8B are perspective views of first and second electrodes showing another embodiment of the present invention;

9A and 9B are graphs showing comparison of electron beam focusing shapes in the tripolar portions of the prior art and the present invention.

10A and 10B are graphs showing a characteristic change according to the depth of the depression of the first electrode.

11A and 11B are graphs showing a characteristic change according to the depth of depression of the second electrode.

Explanation of symbols for main parts of the drawings

4: first electrode 4a, 5c: square hole

4b, 5d: depression 4c, 5e: round hole

5: second electrode

Hereinafter, the present invention will be described in more detail with reference to FIGS. 7A to 11B illustrating the embodiments.

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

Referring to FIGS. 7A and 7B, which illustrate an embodiment of the present invention, an electron beam passing hole formed in the first electrode 4 is a square hole 4a and is positioned on a surface opposite to the second electrode 5. The at least one electron beam through hole of the electron beam through hole is formed with an elongated recess 4b having a horizontal direction smaller than the vertical direction.

At this time, the thickness of the first electrode 4 is set to 0.25 mm or less, and the depth of the depression 4b is set in the range of 40 to 70% of the thickness of the first electrode.

The electron beam passing hole formed in the second electrode 5 is formed as a square hole 5c in the same manner as the first electrode, and at least one electron beam passing hole among the electron beam passing holes positioned on the surface facing the first electrode 4 is passed. The ball is formed with a recessed portion 5d having a vertical direction smaller than the horizontal direction.

At this time, the depth of the recessed portion 5d formed in the second electrode 5 is set in the range of 50 to 80% of the thickness of the second electrode.

8A and 8B show another embodiment of the present invention, which is different from one embodiment in that the electron beam passing holes are formed as square holes 4a and 5c as circular holes 4c and 5e. Is the point.

In the above-described embodiments, in the case of a color cathode ray tube requiring a high amount of electron beam current, it is preferable that the electron beam through hole formed in the first electrode 4 be a square hole 4a.

The reason is that the square hole 4a can maintain the same horizontal and vertical pore diameter of the first electrode 4 which determines the size of the water point while widening the radiation area of the cathode 1 compared to the circular hole 4c. This is because an increase in the spot size on the screen can be suppressed while increasing the lifetime of the cathode 1.

The first and second electrodes 4 and 5 are arranged inline to maintain a predetermined interval so that different voltages are applied. In general, 0 V is applied to the first electrode 4 and the second electrode 5 is applied. 260 to 10,000 V is applied to the asymmetric tripolar lens 16 by the potential difference between the two electrodes.

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

First, when power is applied to the heater 14 in the cathode 1 and the electron beam 2 is emitted from the cathode, the emitted electron beam is focused by the first and second electrodes 4 and 5 and then accelerated to generate the first. It passes through the tripolar lens 16 formed between the first and second electrodes.

At this time, an elongate recess 4b formed on the surface of the first electrode 4 opposite to the second electrode 5 and a horizontal shape formed on the surface of the second electrode 5 opposite to the first electrode 4 are provided. The recessed portion 5d of the action of the tripolar lens 16 has a lens strength that is horizontally weaker than that of the vertical direction, so that the electron beam passed through is horizontalized.

In addition, as shown in FIG. 9B, the tripolar lens 16 penetrates into the electron beam passing hole in the shape of the square hole 4a or the circular hole 4c formed in the first electrode 4 and formed on the cathode 1. In the lens action to draw them out, the vertical becomes stronger than the horizontal, so the crossover 31 in the horizontal direction is located closer to the cathode 1 than the crossover 32 in the vertical direction.

Accordingly, as in the conventional electron gun triode shown in FIG. 9A, the crossover 33 is formed at the same horizontal and vertical position, thereby increasing the current density at the crossover portion, thereby increasing the space charge repulsion force and deteriorating the spot. The phenomenon can be compensated in the present invention.

Then, the horizontal action of the tripolar lens 16 formed between the first and second electrodes 4 and 5 is weaker than the vertical by the recesses 4b and 5d to pass through the tripolar lens 16. Deflection defocusing with the asymmetrical main lens shown in FIG. 3 while reducing the spherical aberration of the main lens 19 formed between the fifth and sixth electrodes 8, 9 in the vertical direction, since one electron beam is made horizontal. To compensate for the phenomenon.

That is, when the horizontally longened electron beam is focused on the screen through the main lens, the horizontal distance is formed longer than the vertical distance, so the horizontal distance is shorter than the vertical direction. Compensation for deflection defocusing caused by non-uniform deflection magnetic field 24 when deflected by the deflection.

Here, the depth of the depressions 4b and 5d is the most important factor in designing the tripolar lens 16 formed between the first and second electrodes 4 and 5 in an optimal state.

In order to design the tripolar lens 16 in an optimal state, the depth of the recess 4b formed on the surface of the first electrode 4 opposite to the second electrode 5 is equal to or greater than 40% of the thickness of the first electrode. As shown in FIG. 10A and FIG. 10B, the characteristic change was shown.

At this time, the depth of the recessed portion 5d formed in the second electrode 5 was set to 50% of the thickness of the second electrode.

Accordingly, although the characteristics of the tripolar lens 16 are the best, the thickness of the first electrode 4 is increased so that the lens penetration strength of the tripolar lens 16 into the first electrode 4 is increased. There is a limit to forming more than 0.25 mm.

If the depression 4b is deeply set and the thickness of the electron beam through hole forming portion formed in the first electrode 4 becomes 0.08 mm or less, there is a possibility that deformation may be inadvertently generated during handling of the electrode in the electron gun manufacturing process. Therefore, it was found through experiments that the depth of the depression 4b formed in the first electrode 4 is most preferably set in the range of 40 to 70% of the thickness of the first electrode.

Also, the depth of the recessed portion 5d formed on the surface of the second electrode 5 opposite to the first electrode is also the second electrode thickness when considering the manufacturability and characteristics of the electron gun as shown in the graphs shown in FIGS. 11A and 11B. Is preferably set to 50 to 80%.

The reason why the depth of the recessed portion 5d formed in the second electrode 5 is deeper than the depth of the recessed portion 4b formed in the first electrode 4 is that the first electrode 4 is connected to the second electrode 5. This is because the influence on the tripolar lens 16 is greater.

When the electron beam passing holes formed in the first and second electrodes 4 and 5 are formed as square holes 4a and 5c as in one embodiment, compared to the circular holes 4c and 5e shown in other embodiments. The surface area of the first electrode 4 which affects the electron beam radiation area is kept the same while reducing the horizontal and vertical diameters of the electron beam passing holes formed in the first electrode which directly affect the spot diameter of the screen, compared to the circular holes. As a result, the life of the cathode can be kept the same while reducing the spot diameter on the screen.

As described above, according to the present invention, the deflection force toward the screen periphery becomes larger due to the larger size and higher definition of the CRT due to the simple structure change of the first and second electrodes 4 and 5, thereby deteriorating the electron beam spot. While compensating, it prevents the increase in space charge repulsion at the triode, which is caused by the increased use of a high current amount according to the high brightness demand of the screen, thereby enabling the formation of small spots on the screen as well as uniform focus in all areas of the screen. Can get characteristics.

In other words, it reduces the size of spot on the screen by reducing the space charge repulsion at the three poles and simultaneously compensates for spot degradation at the periphery of the screen caused by deflection magnetic field lens caused by deflection. You get a spot.

Claims (4)

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 toward the screen, a prefocus lens unit comprising 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 of the electron beam through hole formed in the first electrode in the electrode forming the tripolar lens A longitudinal depression having a horizontal direction smaller than the vertical direction is formed around the electron beam through hole, wherein the thickness of the first electrode is 0.25 mm or less, and the depth of the depression is in the range of 40 to 70% of the thickness of the first electrode. Among the electron beam through holes formed in the two electrodes, a horizontal direction is formed at the periphery of the at least one electron beam through hole facing the first electrode. But formation of the depressions greater than the transverse elongate vertical direction, the depression depth of the color cathode-ray tubes the electron gun, characterized in that the hayeoseo set to 50 to 80% range of thickness of the second electrode formed on the second electrode. 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. The method of claim 1, An electron gun for a cathode ray tube, wherein a depth of the depression formed in the second electrode is set deeper than a depth of the depression formed in the first electrode.

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