JPH0887967A - Electron gun for color cathode-ray tube - Google Patents

Abstract

PURPOSE: To narrow the spot diameter in the whole area of a phosphor screen face and provide images with high resolution, regarding a color cathode-ray tube. CONSTITUTION: Dynamic voltage, which changes as the deflection angle increases, is applied to two electrodes; an adding electrode 77 installed between an acceleration electrode 12 and a convergence electrode 13 and the converging electrode 13; in order to weaken the converging function of a main lens 7 at the time of scanning the peripheral part of a screen and moderate the deterioration of the over focusing function in vertical direction. Moreover, the diameter of electron beam in horizontal direction is expanded by the adding electrode 77 and the increase of the converging function of the main lens 7 due to the expansion of the beam diameter compensates for the under focusing function due to the deterioration of the converging function of the main lens 7 itselt.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a color cathode ray tube constructed so that a high resolution can be obtained over the entire area of the phosphor screen surface.

[0002]

2. Description of the Related Art The structure of a conventional in-line type electron gun in which three electron beam emitting portions are horizontally arranged is shown in FIGS.
Will be explained. FIG. 16 is a vertical sectional view of the conventional in-line electron gun 1. As shown in FIG. 16, a control electrode 11 is provided so as to surround three cathodes 18 (not shown) arranged in the horizontal direction, and an acceleration electrode 12 is provided in front of the control electrode 11.
The focusing electrode 13 and the final accelerating electrode 14 are sequentially provided. The electron beam 6 emitted from the cathode 18 passes through the control electrode 11 and the accelerating electrode 12, is pre-focused by the prefocus lens 8 formed by the accelerating electrode 12 and the focusing electrode 13, and is further focused on the focusing electrode 13 and the final accelerating electrode. 14
The main lens 7 formed in 1. forms a beam spot 21a on the phosphor screen surface 3 as shown in FIG. The focusing electrode 13 is applied with either a constant voltage or a changing voltage synchronized with the deflection current.

Generally, in a color cathode ray tube using an in-line type electron gun, in order to obtain a self-convergence effect, a horizontal deflection magnetic field is distorted into a pincushion shape and a vertical deflection magnetic field is distorted into a barrel shape. Therefore, the cross-sectional shape of the electron beam that has passed through the horizontal deflection magnetic field and the vertical deflection magnetic field is affected by the aberration due to the deflection magnetic field, and as shown in FIG. 17, a spot 21 formed on the phosphor screen surface 3 is formed.
b, 21c, 21d, etc. are distorted into a non-circular shape. In particular, the spots 21c and 21d generated on the screen peripheral portion 23 have large distortion. In order to reduce such spot distortion, in the above-mentioned in-line type electron gun 1, astigmatism is given to the main lens 7 and the shape of the electron beam 6 is made less susceptible to aberrations by a deflection magnetic field (not shown). Consideration is given to such a shape.

[0004]

In the conventional in-line type electron gun 1, the electron beam 6 emitted from the electron gun 1 is
Before it hits the phosphor screen surface 3, it is deflected by a deflection magnetic field generator (not shown) and is subjected to strong deflection distortion.
Therefore, there is a problem in that astigmatism occurs due to the horizontal deflection magnetic field in the peripheral portion of the screen of the phosphor screen surface 3, and the haze 20 shown in FIG. 17 causes the resolution of the peripheral portion of the screen to significantly deteriorate. . The present invention has been made to solve the above problems, and an object of the present invention is to provide an electron gun for a color cathode ray tube which can obtain high resolution over the entire phosphor screen surface.

[0005]

In order to achieve the above object, an electron gun for a color cathode ray tube according to the present invention comprises three cathodes, a control electrode, an accelerating electrode, a focusing electrode, a final accelerating electrode, and the accelerating electrode. An additional electrode is provided between the electrode and the focusing electrode, and is configured to apply a dynamic voltage that changes with an increase in the deflection angle to the additional electrode and the focusing electrode. Alternatively, the electron gun for a color cathode ray tube according to the present invention is provided between three cathodes, a control electrode, an accelerating electrode, a focusing electrode divided into two, a final accelerating electrode, and the divided focusing electrode. And an additional electrode that is provided, and is configured to apply a dynamic voltage that changes with an increase in the deflection angle to the additional electrode and the focusing electrode. In the above configuration, it is preferable that the horizontal cross-sectional shape and the vertical cross-sectional shape of the beam passage hole of the additional electrode are different. In the above structure, the additional electrode is composed of two or more electrode plates, the focusing electrode side electrode plate has beam passage holes having different horizontal and vertical cross-sectional shapes, and the acceleration electrode side electrode plate is the focusing electrode side. It is preferable to have a beam passage hole having a smaller geometry than the beam passage hole of the electrode plate. Further, in the above structure, it is preferable that at least one of the beam transmitting holes of the control electrode and the accelerating electrode has a different horizontal sectional shape and vertical sectional shape. Further, in the above structure, it is preferable that the beam transmission hole on the side of the additional electrode of the focusing electrode has a different horizontal sectional shape and vertical sectional shape. Further, in the above configuration, it is preferable that the beam transmission hole on the accelerating electrode side of the focusing electrode divided into two has different horizontal and vertical sectional shapes. Further, in the above configuration, it is preferable that the beam transmission hole on the side of the additional electrode of the focusing electrode divided into two has a different horizontal sectional shape and vertical sectional shape. In the above configuration,
When the deviation of the convergence of the electron beams of three colors occurs with the increase of the deflection angle, it is preferable to correct it by the deflection magnetic field. Alternatively, in the above structure, when the deflection angle is 0, the voltage applied to the additional electrode and the voltage applied to the acceleration electrode are preferably the same. Alternatively, in the above structure, when the deflection angle is 0, it is preferable that the voltage applied to the additional electrode is always higher than the voltage applied to the acceleration electrode by a constant potential. Alternatively, in the above configuration, when the deflection angle is 0, the voltage applied to the additional electrode is
It is preferable to always lower the voltage by a constant voltage than the voltage applied to the acceleration electrode. Alternatively, in the above configuration, when the deflection angle is 0, the voltage applied to the additional electrode is preferably set independently of the voltage applied to the acceleration electrode. Alternatively, in the above configuration, it is preferable to give stigma to the beam spot at the center of the screen.

[0006]

According to such a preferable structure, when the peripheral portion of the screen is scanned, the focusing action of the main lens is weakened by applying the dynamic voltage to the focusing electrode, and the vertical overfocus state is the optimum focus state. It is improved in the vicinity, and the resolution in the vertical direction in the peripheral portion of the screen can be improved. Further, by applying the dynamic voltage to the additional electrode, the diameter of the electron beam is greatly expanded in the horizontal direction when passing through the additional electrode due to the lens effect of the additional electrode. When the focusing action of the main lens is constant, the focusing action of the main lens is stronger when the beam diameter in the horizontal direction is larger than when the beam diameter is small. Therefore, the weakening of the focusing action of the main lens due to the application of the dynamic voltage is offset by the enhancement of the focusing action due to the expansion of the diameter of the electron beam in the horizontal direction, and the underfocusing in the horizontal direction is offset, so that the resolution of the horizontal direction is reduced. It is possible to improve. As a result, the resolution over the entire screen can be improved.

By configuring the beam passage hole of the additional electrode so that the horizontal sectional shape and the vertical sectional shape are different from each other, the lens action of the additional electrode is different between the horizontal direction and the vertical direction.
When the electron beam passes through the main lens, the beam diameter in the horizontal direction can be increased, and the underfocusing in the horizontal direction can be offset. Similarly, the additional electrode is composed of two or more electrode plates, the focusing electrode side electrode plate has beam passage holes having different horizontal and vertical cross-sectional shapes, and the acceleration electrode side electrode plate is the focusing electrode side electrode plate. The same effect can be obtained even if the beam passage hole having a smaller geometry than the beam passage hole is formed. Further, at least one of the beam transmitting holes of the control electrode and the accelerating electrode may be configured so that the horizontal sectional shape and the vertical sectional shape are different. Also, the beam transmission hole on the side of the additional electrode of the focusing electrode may be configured so that the horizontal cross-sectional shape and the vertical cross-sectional shape are different. Further, the beam transmission hole on the acceleration electrode side of the focusing electrode divided into two may be configured to have different horizontal and vertical cross-sectional shapes. Further, the same applies to the case where the beam transmission holes on the side of the additional electrode of the focusing electrode divided into two have different horizontal and vertical cross-sectional shapes.

Further, when the deviation of the convergence of the electron beams of three colors occurs with the increase of the deflection angle, the deviation of the static convergence in the peripheral portion can be reduced by correcting the deviation by the deflection magnetic field. Further, by making the voltage applied to the additional electrode the same as the voltage applied to the accelerating electrode, it is possible to reduce the types of supply voltage on the color cathode ray tube device side. Similarly, the voltage applied to the additional electrode is always higher than the voltage applied to the accelerating electrode by a constant potential, or the voltage is always lowered by a constant voltage to reduce the number of types of supply voltage on the color cathode ray tube device side. You can Similarly, by setting the voltage applied to the additional electrode independently of the voltage applied to the accelerating electrode, it is possible to reduce the types of supply voltage on the color cathode ray tube device side. Further, by giving stigma to the beam spot at the center of the screen, it is possible to reduce the dynamic voltage applied to the additional electrode and the focusing electrode when scanning the peripheral portion of the screen.

[0009]

【Example】

(First Embodiment) A first preferred embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. FIG. 1 is a vertical sectional view showing the structure of an electron gun for a color cathode ray tube according to the first embodiment, and FIG. 2 is a horizontal sectional view thereof. 1 and 2, the electron gun 1 of the first embodiment has three cathodes 18 arranged in a horizontal direction and a cathode 18
Control electrode 11 provided so as to surround the
Acceleration electrode 12, additional electrode 77,
The focusing electrode 13 and the final acceleration electrode 14 are included. The acceleration electrode 12, the additional electrode 77 and the focusing electrode 13 are
It has three beam passage holes arranged horizontally corresponding to the cathodes 18, respectively.

In particular, the shape of the beam passage hole provided in the additional electrode 77 is illustrated in FIG. In FIG. 3, (a
1) to (a6) show the cross-sectional shapes of the beam passing holes in the first to sixth examples, respectively, and (b1) to (b).
Up to 6), the front shape of each of the first to sixth examples of the beam passage hole is shown. (A1) and (b1) show a first example in which a flat plate is provided with a rectangular (rectangular shape whose longitudinal direction is the horizontal direction) beam passage hole. (A2) and (b2) show a second example in which a flat plate is provided with an elliptical beam passage hole whose major axis is in the horizontal direction. (A3) and (b3) show a third example in which protrusions are provided above and below a rectangular (substantially square) beam passage hole. (A4) and (b4) show a fourth example in which protrusions are provided above and below a rectangular (horizontally long rectangle) beam passage hole. (A
5) and (b5) show a fifth example in which arc-shaped projections are provided above and below a substantially circular beam passage hole. (A6) and (b6)
Shows a sixth example in which flat plate-shaped projections are provided above and below a substantially circular beam passage hole. In each of the third to sixth examples having the projections above and below the beam passage hole, the surface provided with the projections is used so as to face either side of the acceleration electrode 12 and the focusing electrode 13. Good.

A typical potential supplied to each electrode during operation is illustrated. For example, 50V to 250 is applied to the cathode 18.
V, 0V for the control electrode 11, 350V for the acceleration electrode 12
~ 1200V, additional electrode 77 200V ~ 2500
V, 5500 V to 9000 V is applied to the focusing electrode 13, and 23 kV to 32 kV is applied to the final accelerating electrode. Further, a dynamic voltage synchronized with the deflection current as shown in FIG. 4, for example, is applied to the additional electrode 77 and the focusing electrode 13. In FIGS. 4A and 4B, the voltage of the additional electrode 77 is Vap and the voltage of the focusing electrode 13 is Vfc when the deflection current becomes 0, that is, when the central portion of the screen is scanned. At this time, since the additional electrode 77 has a small influence on the electron beam, a potential difference Va-Vfc is generated between the voltage Vfc of the focusing electrode 13 and the voltage Va of the final accelerating electrode 14, and the main lens 7 is generated there. . Due to the action of the main lens 7, the three electron beams 6 emitted from each cathode 18 are provided at the central portion 22 of the screen of the phosphor surface 3.
It is focused in the optimal focus state.

Next, when the scanning position moves from the screen central portion 22 to the screen peripheral portion 23, the voltage applied to the additional electrode 77 is increased to Vap + Vdy1 as shown in FIG. 4A as the deflection current increases. To rise. The voltage applied to the focusing electrode 13 is also Vfc + Vd as shown in FIG.
rise to y2. Compared to the case where the deflection current is 0, that is, the case where the screen central portion 22 is scanned, the potential difference between the acceleration electrode 12 and the additional electrode 77 increases by Vdy1. When the potential of the additional electrode 77 increases by Vdy1, the shape of the electron beam is greatly expanded in the horizontal direction when passing through the additional electrode 77. When the focusing action of the main lens is constant, the focusing action of the main lens is stronger when the beam diameter in the horizontal direction is larger than when the beam diameter is small.

At the same time, when the voltage of the focusing electrode 13 is increased by Vdy2, the potential difference of the main lens 7 is Vdy.
It becomes smaller by 2 and the focusing action of the main lens 7 becomes weaker. When the focusing action of the main lens 7 becomes weak, the beam spot of the electron beam is deformed to underfocus. By weakening the focusing action of the main lens 7,
The vertical overfocus state is improved to near the optimum focus state. On the other hand, the weakening of the focusing action of the main lens 7 due to the application of the dynamic voltage is offset by the enhancement of the focusing action due to the expansion of the diameter of the electron beam in the horizontal direction. As a result, horizontal underfocusing is offset. Further, since it has an adverse effect on the strain applied to the electron beam spot by the pincushion-shaped horizontal deflection magnetic field, it is possible to reduce the strain of the horizontally long spot 21c and the like, and at the screen peripheral portion 23 of the phosphor surface 3. Also,
It is possible to reduce the diameter and generate a spot close to a perfect circle.

Further, in the system in which the electron beam 6 is deflected by the prefocus lens 8 formed by the accelerating electrode 12 and the focusing electrode 13 as shown in FIG. 5 and the static convergence is taken, the focusing electrode 13 is formed together with the additional electrode 77. By applying the dynamic voltage, the intensity change of the prefocus lens 8 is reduced. Therefore, it is possible to reduce the deviation of the static convergence even though the dynamic voltage is applied to the focusing electrode 13.

Further, in the system of taking the static convergence by the main lens 7 as shown in FIG. 6, since the intensity of the main lens 7 changes when a dynamic voltage is applied, the static convergence is deviated. However, this problem is that when a dynamic voltage is applied, that is, when the electron beam 6 is deflected to the screen peripheral portion 23, the system is configured to generate the magnetic field strength by the deflection so that the static convergence in the screen peripheral portion 23 is improved. It is possible to reduce the deviation.

In the in-line color cathode ray tube, the resolution in the peripheral portion 23 of the screen can be considerably improved by only applying the dynamic voltage synchronized with the horizontal deflection. However, if a more complete effect is desired, a dynamic voltage synchronized with vertical deflection may be applied in a superimposed manner.

(Second Embodiment) Next, a second preferred embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. The basic structure of the electron gun for a color cathode ray tube according to the second embodiment is similar to that of the electron gun for a color cathode ray tube according to the first embodiment. However, the difference is that the shape of the beam passage hole provided in the control electrode 11 or the acceleration electrode 12 is configured to have different shapes in the horizontal cross section and the vertical cross section, as shown in FIG. 7.

In FIG. 7, (a) shows a first electrode plate having three substantially rectangular openings arranged in the horizontal direction, and a second electrode having three substantially circular openings similarly arranged in the horizontal direction. A first example is shown in which the plates are stacked and the first electrode plate has a narrower width in the vertical direction than the second electrode plate. (B) shows that one electrode plate is provided with three substantially rectangular openings arranged in the horizontal direction and three substantially circular openings arranged in the horizontal direction, or in the first example, the first Electrode plate and second
A second example in which the size of the electrode plates is substantially the same is shown.
(C) shows a third example in which three substantially rectangular openings are arranged horizontally on one electrode plate. (D) is a first electrode plate having three substantially elliptical openings arranged in the horizontal direction and a second electrode plate having three substantially elliptical openings similarly arranged in the horizontal direction and having a small size. A fourth example in which the first electrode plate has a smaller width in the vertical direction than the second electrode plate is shown. In (e), one electrode plate is provided with three elliptical openings arranged in the horizontal direction and three substantially elliptical openings having a small size arranged in the horizontal direction, or Of the four examples, a fifth example is shown in which the first electrode plate and the second electrode plate have substantially the same size. (F) shows a sixth electrode in which three substantially elliptical openings are horizontally arranged on one electrode plate.
Here is an example: (G) is formed by stacking a first electrode plate having one rectangular opening whose longitudinal direction is in the horizontal direction and a second electrode plate having three substantially circular openings arranged in the horizontal direction, A seventh example is shown in which the first electrode plate has a smaller width in the vertical direction than the second electrode plate. In (h), one rectangular opening having the horizontal direction as the longitudinal direction and three substantially circular openings arranged in the horizontal direction are provided in one electrode plate, or in the seventh example, the first opening is used. An eighth example in which the size of the electrode plate and the size of the second electrode plate are substantially the same is shown. (I) is
The 9th example which provided one rectangular opening which makes a horizontal direction the longitudinal direction in one electrode plate is shown.

In this way, the control electrode 11 or the acceleration electrode 1
By configuring the shape of the beam passage hole provided in No. 2 to have different shapes in the horizontal cross section and the vertical cross section, the electron beam diameter in the horizontal direction when passing through the main lens 7 becomes large. As described above, when the electron beam diameter increases, the main lens 7 receives a strong focusing action, so that it is possible to cancel the underfocusing in the screen peripheral portion 23, and the diameter of the phosphor surface 3 in the screen peripheral portion 23 is small, And it becomes possible to generate a spot close to a perfect circle.

(Third Embodiment) Next, a preferred third embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. The basic structure of the electron gun for a color cathode ray tube according to the third embodiment is similar to that of the electron gun for a color cathode ray tube according to the first embodiment. However, the difference is that the beam passage hole of the focusing electrode 13 on the side of the additional electrode 77 has a shape as shown in FIG.

In FIG. 8, (a1) to (a6) show the cross-sectional shapes of the first to sixth examples of the beam passing holes, and (b1) to (b6) show the beam passing holes. The front shape of each example from the 1st to the 6th is shown. (A1) and (b1) show a first example in which a rectangular (rectangular shape whose longitudinal direction is the vertical direction) beam passage hole is provided in a flat plate. (A2) and (b2) show a second example in which a flat plate is provided with an elliptical beam passage hole whose long axis is the vertical direction. (A
3) and (b3) show a third example in which protrusions are provided on the left and right of a rectangular (substantially square) beam passage hole. (A4) and (b
4) shows a fourth example in which projections are provided on the left and right of a rectangular (vertically long rectangle) beam passage hole. (A5) and (b5) show a fifth example in which arc-shaped projections are provided on the left and right of the substantially circular beam passage hole. (A6) and (b6) show a sixth example in which flat plate-shaped projections are provided on the left and right of the substantially circular beam passage hole.

With this structure, the electron beam diameter in the horizontal direction becomes large, and when passing through the main lens 7, a strong focusing action is exerted. Therefore, the screen peripheral part 2
3 can be canceled out, and a beam spot with a small diameter and close to a perfect circle can be generated in the screen peripheral portion 23 of the phosphor surface 3.

(Fourth Embodiment) Next, a fourth preferred embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. The basic structure of the color cathode ray tube electron gun according to the second embodiment is similar to that of the color cathode ray tube electron gun according to the third embodiment. However, the additional electrode 77 has a structure in which two electrode plates are bonded together, and as shown in FIGS. 9 and 10, the shape of the beam passage hole on the side of the accelerating electrode 12 is a shape capable of position regulation, and the focusing electrode 13 is formed. The difference is that the side electrode is shaped so that the lens action in the horizontal direction is different from that in the vertical direction.

In FIG. 9, (a1) to (a6) show the sectional shapes of the first to sixth examples of the beam passing holes, and (b1) to (b6) show the beam passing holes. The front shape of each example from the 1st to the 6th is shown. Further, in FIG. 10, (a1) to (a6) show the cross-sectional shapes of the beam passing holes in the seventh to twelfth examples, respectively, and (b1) to (b6) show the beam passing holes in the first to the twelfth examples, respectively. The front shape of each example from 7 to 12 is shown.

In FIGS. 9A and 9B, (a1) and (b1) are rectangular (rectangular with the longitudinal direction being the horizontal direction) beam passage holes formed in the first plate-like electrode plate, and the second electrode plate is substantially circular. The 1st example which provided the beam passage hole of is shown. Also, (a2)
And (b2), a rectangular (rectangular shape whose longitudinal direction is the horizontal direction) beam passage hole is provided in the first plate-shaped electrode plate,
A second example in which a rectangular beam passage hole having a small size is also provided in the electrode plate of FIG. (A3) and (b3) show a rectangular (substantially square) beam passage hole in the first electrode plate and a second beam above and below it.
A third example is shown in which a projection in the opposite direction to the electrode plate is provided, and a substantially circular beam passage hole is provided in the second electrode plate. (A4) and (b4) are provided with a rectangular (substantially square) beam passage hole in the first electrode plate and projections toward the second electrode plate above and below the beam passage hole.
The 4th example which provided the substantially circular beam passage hole in the 2nd electrode plate is shown. In (a5) and (b5), the first electrode plate is provided with a rectangular (rectangular with the longitudinal direction as horizontal direction) beam passage hole and projections above and below the beam passage hole in the opposite direction to the second electrode plate.
5 shows a fifth example in which a substantially circular beam passage hole is provided in the electrode plate of FIG. (A6) and (b6) show that the first electrode plate has a rectangular (rectangular shape whose longitudinal direction is the horizontal direction) beam passage hole and projections toward the second electrode plate above and below the beam passage hole. The 6th example which provided the substantially circular beam passage hole is shown.

Further, in FIG. 10, (a1) and (b)
In 1), the first electrode plate is provided with a substantially circular beam passage hole and arc-shaped projections above and below the beam passage hole in the opposite direction to the second electrode plate,
The 7th example which provided the small circular beam passage hole in the 2nd electrode plate is shown. (A2) and (b2) show a substantially circular beam passage hole in the first electrode plate and arc-shaped projections above and below the beam passage hole in the direction of the second electrode plate, and the second electrode plate has a small circular shape. The 8th example which provided the beam passage hole of is shown.
In (a3) and (b3), the first electrode plate is provided with a substantially circular beam passage hole and plate-like protrusions above and below the beam passage hole in a direction opposite to that of the second electrode plate. The 9th example which provided the small substantially circular beam passage hole is shown. In (a4) and (b4), the first electrode plate is provided with a substantially circular beam passage hole and flat plate-shaped projections in the second electrode plate direction above and below the beam passage hole.
10 shows a tenth example in which a substantially circular beam passage hole having a small size is provided on the electrode plate. In (a5) and (b5), the first electrode plate is provided with an elliptical beam passage hole whose horizontal direction is the horizontal direction, and the second electrode plate is provided with a small circular beam passage hole. 11 examples are shown. (A6) and (b6) are rectangles on the first electrode plate (rectangles whose longitudinal direction is the horizontal direction)
12 shows a twelfth example in which the beam passage hole and the projections in the direction of the second electrode plate are provided above and below the beam passage hole, and the second electrode plate is provided with an elliptical beam passage hole whose horizontal axis is the horizontal direction.

With this structure, the diameter of the electron beam in the horizontal direction becomes large, and when passing through the main lens 7, it is strongly focused. Therefore, the screen peripheral part 2
3 can be canceled out, and a beam spot with a small diameter and close to a perfect circle can be generated in the screen peripheral portion 23 of the phosphor surface 3.

(Fifth Embodiment) Next, a preferred fifth embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. FIG. 11 is a sectional view showing the structure of the electron gun for a color cathode ray tube according to the fifth embodiment. In FIG. 11, the electron gun 1 includes a cathode 18 and a control electrode 11.
The accelerating electrode 12, the first focusing electrode 15, the additional electrode 77, the second focusing electrode 16, and the final accelerating electrode 14. First focusing electrode 15 and second focusing electrode 16
The same voltage is applied to both. Further, at least one of the beam transmission holes of the control electrode 11 and the acceleration electrode 12 is
The cross-sectional shape in the horizontal direction is different from the cross-sectional shape in the vertical direction. The beam transmission holes of each electrode may be configured to have the shapes shown in the first to fourth embodiments.

As in the case of the first embodiment, the additional electrode 7
A dynamic voltage synchronized with the deflection current as shown in FIG. 4, for example, is applied to 7 and the focusing electrode 13. When the deflection current becomes 0, that is, when the central portion of the screen is operated, the voltage of the additional electrode 77 is Vap and the voltage of the focusing electrode 13 is Vfc. At this time, since the additional electrode 77 has a small influence on the electron beam, a potential difference Va-Vfc is generated between the voltage Vfc of the focusing electrode 13 and the voltage Va of the final accelerating electrode 14, and the main lens 7 is generated there. . Due to the action of the main lens 7, the three electron beams 6 emitted from each cathode 18 are provided at the central portion 22 of the screen of the phosphor surface 3.
It is focused in the optimal focus state.

Next, when the scanning position moves from the screen central portion 22 to the screen peripheral portion 23, the voltage applied to the additional electrode 77 increases to Vap + Vdy1 as the deflection current increases. The voltage applied to the first focusing electrode 15 and the second focusing electrode 16 also rises to Vfc + Vdy2. The potential difference between the acceleration electrode 12 and the first focusing electrode 15 is increased by Vdy1 as compared with the case where the deflection current is 0, that is, the case where the screen central portion 22 is scanned. When the potential of the first focusing electrode 15 is increased by Vdy1, the shape of the electron beam is greatly expanded in the horizontal direction when passing through the first focusing electrode 15. When the focusing action of the main lens is constant, the focusing action of the main lens is stronger when the beam diameter in the horizontal direction is larger than when the beam diameter is small.

At the same time, the voltage of the second focusing electrode 16 is Vd.
By increasing y2 relatively, the final accelerating electrode 1
The potential difference with respect to 4 is reduced by Vdy2, and the focusing action of the main lens 7 is weakened accordingly. When the focusing action of the main lens 7 becomes weak, the beam spot of the electron beam is deformed to underfocus. By weakening the focusing action of the main lens 7, the overfocus state in the vertical direction is improved to near the optimal focus state. On the other hand, the weakening of the focusing action of the main lens 7 due to the application of the dynamic voltage is offset by the enhancement of the focusing action due to the expansion of the diameter of the electron beam in the horizontal direction. As a result, the horizontal underfocusing is canceled out, and it is possible to generate a spot having a small diameter and a shape close to a perfect circle in the screen peripheral portion 23 of the phosphor surface 3.

(Sixth Embodiment) Next, a sixth preferred embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. FIG. 12 is a sectional view showing the structure of the electron gun for a color cathode ray tube according to the sixth embodiment. In FIG. 12, the electron gun 1 includes a cathode 18 and a control electrode 11.
The accelerating electrode 12, the first focusing electrode 15, the additional electrode 77, the second focusing electrode 16, and the final accelerating electrode 14. First focusing electrode 15 and second focusing electrode 16
The same voltage is applied to both.

Further, regarding the shape of the beam transmission hole of each electrode, at least one of the following conditions is satisfied. Condition 1: At least one of the beam transmission holes of the control electrode 11 and the acceleration electrode 12 has a different horizontal sectional shape and vertical sectional shape. Condition 2: The additional electrode 77 has three laterally long beam passage holes having their long axes in the horizontal direction. Condition 3: At least one of the beam passing hole of the first focusing electrode 15 on the side of the additional electrode 77 and the beam passing hole of the second focusing electrode 16 on the side of the additional electrode 77 has a vertically long beam passing hole having a long axis in the vertical direction. Is.

As in the case of the first embodiment, the additional electrode 7
A dynamic voltage synchronized with the deflection current as shown in FIG. 4, for example, is applied to 7 and the focusing electrode 13. When the deflection current becomes 0, that is, when the central portion of the screen is operated, the voltage of the additional electrode 77 is Vap and the voltage of the focusing electrode 13 is Vfc. At this time, since the additional electrode 77 has a small influence on the electron beam, a potential difference Va-Vfc is generated between the voltage Vfc of the focusing electrode 13 and the voltage Va of the final accelerating electrode 14, and the main lens 7 is generated there. . The three electron beams 6 emitted from each cathode 18 are focused by the action of the main lens 7 on the screen central portion 22 of the phosphor surface 3 shown in FIG.

Next, when the scanning position moves from the screen central portion 22 to the screen peripheral portion 23, the voltage applied to the additional electrode 77 increases to Vap + Vdy1 as the deflection current increases. The voltage applied to the first focusing electrode 15 and the second focusing electrode 16 also rises to Vfc + Vdy2. The potential difference between the acceleration electrode 12 and the first focusing electrode 15 is increased by Vdy1 as compared with the case where the deflection current is 0, that is, the case where the screen central portion 22 is scanned. When Vdy2 is applied to the first focusing electrode 15, the potential difference from the acceleration electrode 12 increases. Further, the shape of the electron beam is greatly expanded in the horizontal direction due to the lens effect formed by the first focusing electrode 15, the additional electrode 77, and the second focusing electrode 16. If the focusing effect of the main lens is constant,
The case where the beam diameter in the horizontal direction is large is more strongly focused by the main lens than the case where the beam diameter is small.

At the same time, the voltage of the second focusing electrode 16 is Vd.
By increasing y2 relatively, the final accelerating electrode 1
The potential difference with respect to 4 is reduced by Vdy2, and the focusing action of the main lens 7 is weakened accordingly. When the focusing action of the main lens 7 becomes weak, the beam spot of the electron beam is deformed to underfocus. By weakening the focusing action of the main lens 7, the overfocus state in the vertical direction is improved to near the optimal focus state. On the other hand, the weakening of the focusing action of the main lens 7 due to the application of the dynamic voltage is offset by the enhancement of the focusing action due to the expansion of the diameter of the electron beam in the horizontal direction. As a result, the horizontal underfocusing is canceled out, and it is possible to generate a spot with a small diameter and close to a perfect circle even in the screen peripheral portion 23 of the phosphor surface 3.

(Seventh Embodiment) Next, a preferred seventh embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. The electrode structure in the seventh embodiment is
It may have any structure among the structures shown in the first to sixth embodiments.

When the deflection current becomes 0, that is, when the voltage of the additional electrode 77 is Vap and the voltage of the focusing electrode 13 is Vfc, the voltage Vfc of the focusing electrode 13 and the voltage Va of the final accelerating electrode 14 are set. A potential difference Va-Vfc is generated during the period. The main lens 7 is generated by this potential difference. At this time, the main lens 7 is provided with some stigma, which is the difference between the horizontal and vertical lens actions. As a result, the three electron beams 6 that have passed through the main lens 7 are almost optimally focused on the screen central portion 22 of the phosphor surface 3 as indicated by 9a in FIG.

In the first to sixth embodiments, in order to just focus the electron beam 6 when the deflection current is increased, that is, when the electron beam 6 is deflected to the peripheral portion 23 of the screen, A high dynamic voltage Vdy2 was required. However, in the seventh embodiment, the screen central portion 2
Since the stigma is given to 2, it is possible to perform just focus near the screen peripheral portion 23 without raising the dynamic voltage Vdy2 so much. For example, the maximum point of the dynamic voltage is set at the place shown by the straight line 24 in FIG. As a result, the required amount of dynamic voltage can be reduced as shown in FIG. 15, for example. The dynamic voltage is applied with a constant waveform regardless of vertical deflection. Thereby,
Regarding the screen peripheral portion 23, 9b, 9c, and 9 in FIG.
As shown by d, it is possible to reduce moire due to an underfocus state and an increase in beam vertical diameter, and to generate a spot with a small diameter and close to a perfect circle in the screen peripheral portion 23 of the phosphor surface 3. Is possible. In other words, it means that the entire screen is just in focus.

(Eighth Embodiment) Next, a preferred eighth embodiment of the electron gun for a color cathode ray tube of the present invention will be described with reference to the drawings. The electrode structure in the eighth embodiment is
It may have any structure among the structures shown in the first to sixth embodiments.

In the eighth embodiment, the same voltage as that applied to the acceleration electrode 12 is applied to the additional electrode 77. In this case, the effects shown in each of the above embodiments can be obtained without increasing the types of supply voltage on the color cathode ray tube device side. Further, the voltage applied to the additional electrode 77 may be set higher than the voltage applied to the accelerating electrode 12, and the supply of the voltage of the additional electrode 77 and the accelerating electrode 12 voltage may be cut by the resistance on the circuit side. Also in this case, the effects of the above-described respective embodiments can be obtained without increasing the types of supply voltage on the color cathode ray tube device side. Note that the effects of each of the above-described embodiments can be obtained even if a separate power supply voltage is provided when optimum operation is always desired.

[0042]

As described above, according to the present invention, the focusing action of the main lens is weakened by applying the dynamic voltage to the focusing electrode when scanning the peripheral portion of the screen.
The overfocus state in the vertical direction is improved to be close to the optimum focus state, and the vertical resolution in the peripheral portion of the screen can be improved. Further, by applying the dynamic voltage to the additional electrode, the shape of the electron beam is greatly expanded in the horizontal direction when passing through the additional electrode due to the lens effect of the additional electrode. When the focusing action of the main lens is constant, the focusing action of the main lens is stronger when the beam diameter in the horizontal direction is larger than when the beam diameter is small. Therefore, the weakening of the focusing action of the main lens due to the application of the dynamic voltage is offset by the enhancement of the focusing action due to the expansion of the diameter of the electron beam in the horizontal direction, and the underfocusing in the horizontal direction is offset, so that the resolution of the horizontal direction is reduced. It is possible to improve. As a result, the resolution over the entire screen can be improved.

By making the horizontal cross-sectional shape and the vertical cross-sectional shape of the beam passage hole of the additional electrode different, the lens action of the additional electrode differs between the horizontal direction and the vertical direction.
When the electron beam passes through the main lens, the beam diameter in the horizontal direction can be increased, and the underfocusing in the horizontal direction can be offset. Similarly, the additional electrode is composed of two or more electrode plates, the focusing electrode side electrode plate has beam passage holes having different horizontal and vertical cross-sectional shapes, and the acceleration electrode side electrode plate is the focusing electrode side electrode plate. The same effect can be obtained even if the beam passage hole having a smaller geometry than the beam passage hole is formed. Further, at least one of the beam transmitting holes of the control electrode and the accelerating electrode may be configured so that the horizontal sectional shape and the vertical sectional shape are different. Also, the beam transmission hole on the side of the additional electrode of the focusing electrode may be configured so that the horizontal cross-sectional shape and the vertical cross-sectional shape are different. Further, the beam transmission hole on the acceleration electrode side of the focusing electrode divided into two may be configured to have different horizontal and vertical cross-sectional shapes. Further, the same applies to the case where the beam transmission holes on the side of the additional electrode of the focusing electrode divided into two have different horizontal and vertical cross-sectional shapes.

Further, when the deviation of the convergence of the electron beams of three colors occurs with the increase of the deflection angle, the deviation of the static convergence in the peripheral portion can be reduced by correcting the deviation by the deflection magnetic field. Further, by making the voltage applied to the additional electrode the same as the voltage applied to the accelerating electrode, it is possible to reduce the types of supply voltage on the color cathode ray tube device side. Similarly, the voltage applied to the additional electrode is always higher than the voltage applied to the accelerating electrode by a constant potential, or the voltage is always lowered by a constant voltage to reduce the number of types of supply voltage on the color cathode ray tube device side. You can Similarly, by setting the voltage applied to the additional electrode independently of the voltage applied to the accelerating electrode, it is possible to reduce the types of supply voltage on the color cathode ray tube device side. Further, by giving stigma to the beam spot at the center of the screen, it is possible to reduce the dynamic voltage applied to the additional electrode and the focusing electrode when scanning the peripheral portion of the screen.

[Brief description of drawings]

FIG. 1 is a preferred first example of an electron gun for a color cathode ray tube according to the present invention.
Vertical cross-sectional view showing the configuration of the embodiment

FIG. 2 is a horizontal sectional view of the electron gun for a color cathode ray tube of the first embodiment shown in FIG.

FIG. 3 is a diagram enumerating and exemplifying the shape of a beam passage hole of an additional electrode 77 in the first embodiment.

4A shows an example of a dynamic voltage applied to an additional electrode 77, and FIG. 4B shows an example of a dynamic voltage applied to a focusing electrode.

FIG. 5 is a horizontal cross-sectional view showing a case where static convergence is obtained by the prefocus lens 8 in the first embodiment.

FIG. 6 is a horizontal sectional view showing a case where static convergence is achieved by the main lens 7 in the first embodiment.

FIG. 7 is a preferred second embodiment of the electron gun for a color cathode ray tube of the present invention.
Of the shapes of the control electrodes or the acceleration electrodes and the shapes of their beam passage holes in the embodiment of FIG.

FIG. 8 is a third preferred electron gun for a color cathode ray tube of the present invention.
Of the examples of the shape of the beam passage hole on the accelerating electrode side of the focusing electrode in the embodiment of FIG.

FIG. 9 is a preferred fourth example of the electron gun for a color cathode ray tube of the present invention.
Of the beam passing holes of the additional electrodes in the example of FIG.

FIG. 10 is a diagram enumerating and exemplifying the shape of a beam passage hole of an additional electrode in a fourth preferred embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 11 is a vertical sectional view showing the configuration of a fifth preferred embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 12 is a vertical sectional view showing the configuration of a sixth preferred embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 13 is a diagram showing the shape of a beam spot on a phosphor screen in a preferred seventh embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 14 is a diagram showing optimum focus points (lines) on a phosphor screen in a preferred seventh embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 15 is a diagram showing a dynamic voltage in a preferred seventh embodiment of the electron gun for a color cathode ray tube of the present invention.

FIG. 16 is a vertical sectional view showing the configuration of a conventional in-line type electron gun for a color cathode ray tube.

FIG. 17 is a diagram showing the shape of a beam spot on a phosphor screen in a conventional in-line electron gun for a color cathode ray tube.

[Explanation of symbols]

 1: electron gun 3: phosphor surface 6: electron beam 7: main lens 8: prefocus lens 9a: electron beam spot 9b: electron beam spot 9c: electron beam spot 9d: electron beam spot 11: control electrode 12: acceleration electrode 13 : Focusing electrode 14: Final accelerating electrode 15: First focusing electrode 16: Second focusing electrode 18: Cathode 20: Haze 21a: Electron beam spot 21b: Electron beam spot 21c: Electron beam spot 21d: Electron beam spot 22: Screen central part 23: Screen peripheral part 24: Optimal focus point (line) 77: Additional electrode

Claims (14)

[Claims] 1. The apparatus comprises three cathodes, a control electrode, an accelerating electrode, a focusing electrode, a final accelerating electrode, and an additional electrode provided between the accelerating electrode and the focusing electrode. An electron gun for a color cathode ray tube, wherein a dynamic voltage that changes with an increase is applied to the additional electrode and the focusing electrode. 2. A cathode, a control electrode, an accelerating electrode, a focusing electrode divided into two, a final accelerating electrode, and an additional electrode provided between the divided focusing electrodes. An electron gun for a color cathode ray tube, wherein a dynamic voltage that changes with an increase in deflection angle is applied to the additional electrode and the focusing electrode. 3. The electron gun for a color cathode ray tube according to claim 1, wherein a horizontal cross-sectional shape and a vertical cross-sectional shape of the beam passage hole of the additional electrode are different. 4. The additional electrode is composed of two or more electrode plates, the focusing electrode side electrode plate has beam passage holes having different horizontal and vertical cross-sectional shapes, and the acceleration electrode side electrode plate is the focusing electrode side electrode. The electron gun for a color cathode ray tube according to claim 1 or 2, wherein the electron beam gun has a beam passage hole having a smaller geometry than the beam passage hole of the plate. 5. The electron gun for a color cathode ray tube according to claim 1, wherein at least one of the beam transmitting holes of the control electrode and the accelerating electrode has a different horizontal sectional shape and vertical sectional shape. 6. The horizontal cross-sectional shape and the vertical cross-sectional shape of the beam transmission hole on the additional electrode side of the focusing electrode are different from each other.
An electron gun for a color cathode ray tube according to any one of 1. 7. The electron gun for a color cathode ray tube according to claim 2, wherein the beam transmission hole on the accelerating electrode side of the focusing electrode divided into two has different horizontal and vertical sectional shapes. 8. The electron gun for a color cathode ray tube according to claim 2, wherein the beam transmitting hole on the side of the additional electrode of the focusing electrode divided into two has different horizontal and vertical sectional shapes. 9. The electron gun for a color cathode ray tube according to claim 1, wherein when the deviation of the convergence of the electron beams of three colors occurs with the increase of the deflection angle, the deviation is corrected by the deflection magnetic field. 10. The electron gun for a color cathode ray tube according to claim 1, wherein the voltage applied to the additional electrode and the voltage applied to the accelerating electrode are the same when the deflection angle is 0. 11. The electron gun for a color cathode ray tube according to claim 1, wherein when the deflection angle is 0, the voltage applied to the additional electrode is always higher than the voltage applied to the accelerating electrode by a constant potential. . 12. The electron gun for a color cathode ray tube according to claim 1, wherein when the deflection angle is 0, the voltage applied to the additional electrode is always lower than the voltage applied to the accelerating electrode by a constant voltage. . 13. The electron gun for a color cathode ray tube according to claim 1, wherein when the deflection angle is 0, the voltage applied to the additional electrode is set independently of the voltage applied to the accelerating electrode. 14. The electron gun for a color cathode ray tube according to claim 1, wherein stigma is given to a beam spot at the center of the screen.