JP2001084920A - Electron gun for color picture tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve focus over an entire screen and reduce circuit cost by reducing a dynamic voltage. SOLUTION: From a cathode side to a fluorescent screen side, first focusing electrode 4, second focusing electrode 5, third focusing electrode 6, and fourth focusing electrode 7 are arranged one after another. To the first focusing electrode 4 and the third focusing electrode 6, a uniform focusing voltage is applied, and to the second focusing electrode 5 and the fourth focusing electrode 7, a dynamic voltage raised with the increase in the deflection amount of an electron beam is applied. Among the second focusing electrode 5, a third focusing electrode 6, and the fourth focusing electrode 7, a unipotential quadrupole lens is formed having a diverging action in a horizontal direction and a focusing action in the vertical direction, and the unipotential quadrupole lens is combined with a main lens whose horizontal lens integrity is increased more than its vertical one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-line type electron gun for a color picture tube, which is capable of relatively easily and inexpensively obtaining high resolution over the entire surface of a phosphor screen and reducing a dynamic voltage. To reduce the circuit cost.

[0002]

2. Description of the Related Art In a color picture tube in which three electron beam radiating portions are arranged in a horizontal straight line, a horizontal magnetic field is distorted in a pincushion shape and a vertical magnetic field is distorted in a barrel shape in order to form a self-convergence configuration. As a result, the three electron beams passing through the deflecting magnetic field undergo a diverging action in the horizontal direction and a focusing action in the vertical direction, resulting in a horizontally flat cross-sectional shape having a long axis in the horizontal direction. Generally, as the deflection angle of the electron beam increases, the trajectory of the electron beam increases, and the beam spot becomes overfocused. However, since a part of the beam spot is canceled by the divergence, the beam spot is kept in the just focus state in the horizontal direction throughout the entire deflection period. However, in the vertical direction, since the above-mentioned focusing action is added, the degree of overfocus increases, resulting in a long haze in the beam spot, and the resolution of the peripheral portion of the screen decreases.

[0003] The above problem is improved by the invention described in Japanese Patent Application Laid-Open No. Hei 6-187921. As shown in FIG. 7, the electron gun has a cathode 1a, 1b, 1c, a control grid electrode 2, an acceleration electrode 3, a first focusing electrode 4, a second focusing electrode 5, and a third focusing connected to the first focusing electrode 4. The electrode 6, the fourth focusing electrode 7 connected to the second focusing electrode 5, and the final accelerating electrode 8 are sequentially arranged. As shown in FIG. 8, the second focusing electrode 5
Are vertically elongated electron beam passage holes 5 in the end face on the third focusing electrode 6 side.
a, 5b, and 5c, and the third focusing electrode 6 has laterally elongated electron beam passage holes 6a, 6b, and 6c at the end face on the second focusing electrode 5 side.
The end face on the fourth focusing electrode 7 side has vertically elongated electron beam passage holes 6d, 6e, 6f, and the fourth focusing electrode 7 has a horizontally elongated electron beam passing hole on the end face on the third focusing electrode 6 side. 7
a, 7b, 7c, and the fourth focusing electrode 7 and the final accelerating electrode 8 are provided with non-circular electron beam passage holes 7d, 7e, 7f and 8a, 8b, 8c for generating a main lens at opposing end surfaces.
Respectively.

A constant first focus voltage Vf is applied to the first focusing electrode 4 and the third focusing electrode 6, and the final accelerating electrode 8
Is applied with a constant high voltage Va. Then, to the second focusing electrode 5 and the fourth focusing electrode 7, a dynamic voltage is applied which starts from the first focus voltage Vf and gradually increases as the deflection angle of the electron beam increases. As the electron beam increases its deflection angle, the potential of the fourth focusing electrode 7 gradually becomes higher than the potential of the third focusing electrode 6. An electric field) is generated. The quadrupole lens field imparts a horizontally focused and vertically divergent lens effect to the electron beam passing therethrough. Also, the fourth focusing electrode 7
Is closer to the potential of the final accelerating electrode 8, so that the main lens (axially asymmetric lens electric field) generated between the two electrodes 7, 8
Lens action is weakened. Then, while maintaining the optimal focus state in the horizontal direction by these two actions,
Generates a beam spot without haze in the vertical direction,
High resolution can be obtained over the entire area of the phosphor screen.

As the deflection angle of the electron beam increases, the potential of the second focusing electrode 5 becomes higher than the potential of the third focusing electrode 6, so that a four-pole lens electric field is generated between the electrodes 5 and 6. Is done. Since the quadrupole lens electric field has the opposite characteristic to the quadrupole lens electric field generated between the third and fourth focusing electrodes 6 and 7, the lens magnifications in the horizontal and vertical directions in this lens system are not substantially equal. Therefore, it is possible to prevent the occurrence of moire due to the vertical diameter of the beam spot being too small.

[0006]

However, with the increase in the size of the color picture tube, the increase in the deflection angle, and the flatness of the screen, the horizontal and the horizontal for the self-convergence structure have been developed.
The distortion of the vertical magnetic field becomes larger than before. For this reason, the degree of overfocus in the vertical direction of the beam spot increases, and the four poles of the cross-slot hole which is formed between the third and fourth focusing electrodes 6 and 7 of the conventional configuration and intersects the vertically long hole and the horizontally long hole. When a lens structure is used, it cannot be combined with a main lens with large astigmatism due to the limited lens strength that can be formed, and the dynamic voltage must be significantly increased to generate a beam spot without haze. Therefore, the circuit configuration for generating the dynamic voltage is complicated, and the cost is increased.

As a method of increasing the strength of the quadrupole lens, a structure in which a partition member is provided around the electron beam passage hole has been devised. In this case, however, there is a problem that the cost of parts and the production of parts become difficult. there were.

SUMMARY OF THE INVENTION An object of the present invention is to generate a beam spot having an optimum focus at the periphery of a screen by using a relatively low dynamic voltage, and to provide a dynamic voltage generating circuit in a color picture tube device having a high deflection angle or a completely flat screen. It is an object of the present invention to prevent complication of the device and increase in manufacturing cost.

[0009]

According to the present invention, an acceleration electrode, a first focusing electrode, and a first focusing electrode are provided between a control electrode and a final acceleration electrode.
A second focusing electrode, a third focusing electrode connected to the first focusing electrode, and a fourth focusing electrode connected to the second focusing electrode are sequentially arranged. A constant first focus voltage is applied to the first focusing electrode and the third focusing electrode, while the second focusing electrode and the fourth focusing electrode are lower than the first focusing voltage at the center of the screen and deflect the electron beam. A second focus voltage that gradually increases as the angle increases is applied. A first axially asymmetric lens electric field of a horizontal focusing type and a vertical diverging type is formed between the first focusing electrode and the second focusing electrode, and the second focusing electrode, the third focusing electrode and the fourth focusing electrode form a uniaxial lens. Potential type stronger second axially asymmetric lens electric field (horizontal divergence type, vertical focusing type axially asymmetric lens electric field)
To form In addition, a third axially asymmetric lens electric field having a focusing lens action that is strong in the horizontal direction and weak in the vertical direction is generated between the fourth focusing electrode and the final acceleration electrode.

With such a configuration, a unipotential type quadrupole lens (the second focusing electrode formed by the second focusing electrode, the third focusing electrode, and the fourth focusing electrode, which is mainly involved in correcting the astigmatism of the beam spot) is used. Lens strength) is stronger than that of a conventional cross-slot type asymmetric lens, so that the dynamic voltage can be reduced.

[0011]

FIG. 1 shows an electrode configuration of an electron gun according to the present invention. Cathodes 1a, 1b, 1c, control electrode 2, accelerating electrode 3, first focusing electrode 4, second focusing electrode 5, first focusing electrode 4
, A fourth focusing electrode 7 connected to the second focusing electrode 5 and a final accelerating electrode 8 are sequentially arranged. As shown in FIG. 2, a horizontally elongated electron beam passage hole 4 is formed in the end face of the first focusing electrode 4 on the second focusing electrode 5 side.
a, 4b, and 4c, and vertically elongated electron beam passage holes 5a, 5b, and 5c are formed in the end face of the second focusing electrode 5 on the first focusing electrode 4 side.
The second focusing electrode 5 has laterally elongated electron beam passing holes 5d, 5e, and 5f on the end face on the third focusing electrode 6 side. The third focusing electrode 6 has a vertically long electron beam passage hole 6
a, 6b, and 6c, and the laterally elongated electron beam passage holes 7a, 7b, and 7c are formed in the end face of the fourth focusing electrode 7 on the third focusing electrode 6 side.
Having.

A constant first focus voltage is applied to the first focusing electrode 4 and the third focusing electrode 6, while a second focusing electrode 5 and the fourth focusing electrode 7 are applied with a voltage value lower than the first focusing voltage. A second focus voltage which starts and gradually increases as the deflection angle of the electron beam increases is applied, and a unipotential type is applied between the second focusing electrode 5, the third focusing electrode 6 and the fourth focusing electrode 7. A strong quadrupole lens electric field (horizontal divergence type, vertically converging type axially asymmetric lens electric field) of a type (consisting of three electrodes and having the same electrode potential at both ends and different center electrode potentials) Thus, the required dynamic voltage can be reduced.

In this embodiment, the first quadrupole lens formed between the first focusing electrode 4 and the second focusing electrode 5 and the second
It has two quadrupole lens systems composed of a focusing electrode 5, a third focusing electrode 6, and a second quadrupole lens formed between the fourth focusing electrode 7, but the second quadrupole lens system is provided near the main lens. 2 of 4
The polar lens is mainly involved in correcting the astigmatism of the beam spot, and the required dynamic voltage can be reduced by increasing the strength of the second quadrupole lens action.

The second unipotential type second electrode formed between the second focusing electrode 5, the third focusing electrode 6 and the fourth focusing electrode 7.
In the four-pole lens of the first embodiment, design parameters such as a hole diameter, a plate thickness, and an inter-electrode gap of three electrodes are increased as compared with a conventional four-pole lens having a cross slot formed of two electrodes. Therefore, there is more room for adjusting the strength of the quadrupole lens, and the strength of the quadrupole lens can be easily increased. In addition, since the three electrodes are subjected to press hole forming, parts can be manufactured relatively easily, and the processing cost of the parts is lower than that of the structure provided with the partition members.

In the present embodiment, the third focusing electrode 5
At the end face on the side of the focusing electrode 6, a horizontally long electron beam passage hole 5d,
5e, 5f, and horizontally long electron beam passage holes 7a, 7b, 7c are provided on the end face of the fourth focusing electrode 7 on the third focusing electrode 6 side. The third focusing electrode 6 is basically provided with vertically elongated electron beam passage holes 6a, 6b, 6c in the plate-like electrode. However, in order to facilitate the assembly of the electron gun, the hole shape of the third focusing electrode 6 is made a round hole. 6d, 6e, 6f (FIG. 3 (a)) in the shape of a combination of a hole and a vertically long rectangular hole, or holes 6g, 6h, 6i in the shape of a combination of a round hole and a wedge-shaped hole.
(FIG. 3B).

The first quadrupole lens formed by the first focusing electrode 4 and the second focusing electrode 5 forms an axially asymmetric lens of a focusing type in the horizontal direction and a diverging type in the vertical direction. It has the opposite polarity to the quadrupole lens, and as a total quadrupole lens system, makes the lens magnification in the horizontal direction and the vertical direction almost equal, prevents the vertical diameter of the beam spot from becoming too small, and reduces the occurrence of moire. is there. Since the first quadrupole lens is arranged at a position close to the cathode 1, the effect of the total astigmatism of the quadrupole lens is small, and it hardly contributes to the reduction of the dynamic voltage.

The second focusing electrode 5 close to the main lens and the third focusing electrode 5
The dynamic voltage can be reduced by increasing the lens strength of the unipotential type quadrupole lens formed between the focusing electrode 6 and the fourth focusing electrode 7, but the focus quality can be reduced simply by increasing the intensity of the quadrupole lens. Is insufficient in securing high resolution over the entire screen. That is, it is necessary to match the action of the main lens with the action of the quadrupole lens.

This will be described with reference to FIGS. FIG. 4 is a schematic view of the lens operation in the horizontal direction (FIG. 4A) and the vertical direction (FIG. 4B) at the center of the total screen of the main lens and the two quadrupole lenses using an optical lens model. It is shown. The quadrupole lens has a divergent type in the horizontal direction and a convergent type in the vertical direction, and the second focus voltage starts from a value lower than the first focus voltage and gradually increases as the deflection angle of the electron beam increases. At the center of the screen (deflection angle 0), the potential difference between the first focus voltage and the second focus voltage is the largest, and the function of the quadrupole lens is the largest. Therefore, if the third axially asymmetric lens (main lens) generated between the fourth focusing electrode 7 and the final acceleration electrode 8 has no astigmatism, that is, the main lens in the horizontal direction and the vertical direction At the same intensity, the lens magnification of the electron gun as a whole is significantly larger in the horizontal direction than in the vertical direction due to the influence of the quadrupole lens. And the horizontal resolution is significantly degraded.

In order to avoid this adverse effect when only the quadrupole lens function is strengthened, it is necessary to increase the amount of astigmatism of the main lens and to match the main lens function with the quadrupole lens function. In order to obtain a substantially perfect beam spot at the center of the screen, as shown in FIG. 4, the main lens action is made stronger in the horizontal lens action than in the vertical lens action, and the total of the quadrupole lens and the main lens is used. By making the lens magnifications in the horizontal and vertical directions substantially equal, a substantially perfect beam spot can be obtained.

FIG. 5 shows an optical lens model when it is deflected to the periphery of the screen. In the peripheral portion of the screen, the second focus voltage starts from a value lower than the first focus voltage. In the peripheral portion of the peripheral portion of the screen, the second focus voltage and the first focus voltage are substantially equal to each other. Polar lens action does not work. Therefore, only the action of the main lens and the action of the deflecting magnetic field (divergent in the horizontal direction and convergent in the vertical direction) work at the end around the screen. For this reason, H of the main lens
If the H / V difference of the focusing action by the deflection magnetic field is canceled by the / V difference, a perfect circular beam spot can be obtained even in the peripheral portion.

The strength of the unipotential type quadrupole lens formed between the second focusing electrode 5, the third focusing electrode 6 and the fourth focusing electrode 7 in the present embodiment matches the strength of the main lens and the quadrupole lens. In order to reduce the intensity of a conventional four-pole lens having a cross slot hole composed of two electrodes.
Since it is increased to about 5 times, the astigmatism amount (H
V difference) needs to be made larger. Conventionally, in order to increase the amount of astigmatism (HV difference) of the main lens, a pair of three-dimensional (partition) or rectangular holes is provided near the flat type electric field correction electrode 81 of the final acceleration electrode (anode) 8. Are provided. However, a desired main lens astigmatism amount (about 1500 [V]) cannot be obtained even if a screen-shaped electrode having a greater effect of astigmatism adjustment is provided. In addition to the screen-like astigmatism adjusting electrode 10, a vertically long astigmatism adjusting vertical as shown in FIG. 2 is further provided between the end surface of the fourth focusing electrode 7 on the third focusing electrode 6 side and the main lens. By providing the electrodes having the rectangular holes 7d, 7e, 7f, it is possible to obtain a substantially desired amount of astigmatism. The electrode having the vertically elongated rectangular hole is disposed almost at the middle between the flat electric field correction electrode 71 of the fourth focusing electrode 7 and the horizontally elongated rectangular hole on the end face on the third focusing electrode 6 side. Even in the case of a square hole or a round hole instead of a vertically long rectangular hole, it is possible to sufficiently adjust astigmatism.

The main electrode dimensions and voltage conditions of the present invention are as follows. The rectangular holes 4a, 4b, 4c in FIG.
Horizontal 3.4 [mm], vertical 1.2 [mm], pitch 6.
03 [mm]. The rectangular holes 5a, 5b, 5c have horizontal 1.2 [mm], vertical 3.4 [mm], and pitch 6.03.
[Mm]. The rectangular holes 5d, 5e and 5f are horizontal.
75 [mm], vertical 3.55 [mm], pitch 5.62
[Mm]. Combination hole 6 of round hole and rectangular hole in FIG.
In a, 6b, and 6c, the round hole has a diameter of 3.5 mm, the rectangular hole has a horizontal 1.5 mm, a vertical 4.5 mm, and a pitch of 5.62 mm. The rectangular holes 7a, 7b, 7c
Horizontal 4.75 [mm], vertical 3.55 [mm], pitch 5.62 [mm]. The rectangular holes 7d and 7f are 4.5 mm horizontally and 4.5 mm vertically. Rectangular hole 7e
Is horizontal 3.6 [mm], vertical 6 [mm], and pitch 6.
0 [mm]. The voltage condition is Va = 27.5 [k
V], Vg2 = 600 [V], Vfoc1 = 7.9 [k
V].

The present invention is applied to a computer monitor tube of 21 inches-100 degrees deflection with the present invention and a conventional structure (a quadrupole lens structure having a cross-slot hole and a screen-like astigmatism adjusting electrode). The dynamic voltages were compared.
FIG. 6A shows the relationship between the position in the horizontal direction of the screen (horizontal axis) and the horizontal dynamic voltage Vd (vertical axis). Curve A shows the prior art, and curve B shows the present invention. FIG. 6B shows the relationship between the position in the vertical direction of the screen and the vertical dynamic voltage Vd, wherein curve C represents the prior art and curve D represents the present invention. FIG. 6A shows that the conventional horizontal dynamic voltage is about 650 at the periphery of the screen (200 mm from the center).
[V], but in the case of the present invention, about 500 [V]
It can be seen that the horizontal dynamic voltage is reduced by about 150 [V]. Further, from FIG. 6B, the conventional dynamic voltage is about 200 [V] at the peripheral portion of the screen (150 [mm] from the center), but is reduced to about 150 [V] in the case of the present invention. You can see that.

[0024]

As described above, according to the present invention, it is possible to generate a beam spot having an optimum focus on the periphery of a screen by using a relatively low dynamic voltage. When applied to a flat color picture tube device, it is possible to suppress the complexity of the dynamic voltage generation circuit and increase in manufacturing cost.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an electron gun of the present invention.

FIG. 2 is a plan view of each electrode constituting the electron gun of the present invention.

FIG. 3 is a plan view of electrodes constituting the electron gun of the present invention.

FIG. 4 is a diagram for explaining the behavior of the electron beam in the electron lens system of the present invention (when no deflection is performed).

FIG. 5 is a diagram for explaining the behavior (at the time of deflection) of an electron beam in the electron lens system of the present invention.

FIG. 6 is a diagram comparing the horizontal dynamic voltage and the vertical dynamic voltage between the related art and the present invention.

FIG. 7 is a side sectional view of a conventional electron gun.

FIG. 8 is a plan view of electrodes constituting a conventional electron gun.

[Explanation of symbols]

 1a-1c Cathode 2 Control electrode 3 Acceleration electrode 4 First focusing electrode 5 Second focusing electrode 6 Third focusing electrode 7 Fourth focusing electrode 8 Final acceleration electrode 10 Electrode for astigmatism adjustment

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takashi Watanabe 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Co., Ltd. F term (reference) 5C041 AA03 AB07 AC05 AC26 AC35 AD02 AD03 AE01

Claims (5)

[Claims] 1. A color picture tube electron gun comprising a cathode, a control electrode, an accelerating electrode, a focusing electrode, and a final accelerating electrode, the cathode being arranged in a direction substantially perpendicular to the tube axis direction. Is divided into a first focusing electrode, a second focusing electrode, a third focusing electrode, and a fourth focusing electrode in the tube axis direction, and a constant focusing voltage is applied to the first focusing electrode and the third focusing electrode, The second focusing electrode and the fourth focusing electrode are applied with a dynamic voltage that starts from a voltage value lower than the focus voltage and increases with an increase in the amount of deflection of the electron beam. An electron gun for a color picture tube, wherein the third focusing electrode and the fourth focusing electrode form a unipotential type quadrupole lens having a diverging function in a horizontal direction and a focusing action in a vertical direction. 2. The main lens formed by the fourth focusing electrode and the final accelerating electrode, wherein the horizontal lens intensity is higher than the vertical lens intensity.
4. The electron gun for a color picture tube according to claim 1. 3. An electron beam passage hole provided on a surface of said second focusing electrode facing said third focusing electrode, said third focusing electrode comprising:
At least one of the electron beam passage holes provided in the focusing electrode and the electron beam passage holes provided in the surface of the fourth focusing electrode facing the third focusing electrode has a non-axisymmetric shape. The electron gun for a color picture tube according to claim 2, wherein 4. An electrode plate having one of a vertically long rectangular hole, a square hole, and a round hole for adjusting the amount of astigmatism is provided between the unipotential type quadrupole lens and the main lens. Item 3. An electron gun for a color picture tube according to Item 1 or 2. 5. The electron gun for a color picture tube according to claim 1, wherein the third focusing electrode is a plate-like electrode, and the vertical diameter of the electron beam passage hole is larger than the horizontal diameter.