JPH11144643A - Color cathode-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a good focus characteristic by improving the shape of beam spots throughout an image plane. SOLUTION: In a color cathode-ray tube equipped with an electron gun 17 and a deflection yoke to generate a pin cushion horizontal deflection magnetic field and a parallel vertical deflection magnetic field, for the electron gun 17, a multipolar lens of which horizontal focusing is weaker than its vertical focusing and of which intensity varies dynamically is formed by applying a voltage to vary dynamically synchronizing with the variation of the deflection magnetic field to at least one of grids Gs forming a prefocusing lens, and a unipotential multipolar lens of which horizontal focusing is stronger than its vertical focusing and of which intensity varies dynamically is formed in at least one part of a main lens.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color CRT device, and more particularly, to a color CRT device which displays a good image by reducing elliptic distortion of a beam spot at a peripheral portion of a screen.

[0002]

2. Description of the Related Art In general, a color cathode ray tube has an envelope composed of a panel and a funnel, and emits three electron beams emitted from an electron gun disposed in the neck of the funnel in horizontal and vertical directions generated by a deflection yoke. It is deflected by a deflecting magnetic field and horizontally and vertically scans a phosphor screen provided on the inner surface of the panel via a shadow mask, so that a color image is displayed.

In such a color cathode ray tube, in particular, the electron gun is an in-line type electron gun which emits three electron beams arranged in a line consisting of a center beam and a pair of side beams passing on the same horizontal plane, and a horizontal deflection generated by a deflection yoke. A self-convergence in-line type color cathode ray tube which self-concentrates the three electron beams arranged in a row as a non-uniform magnetic field in which a magnetic field is a pincushion type and a vertical deflection magnetic field is a barrel type is widely used.

There are various types of electron guns that emit three electron beams arranged in a line, and one of them is a bipotential (BPF) type DACF (Dyamic Astigma).
There is an electron gun called tismCorrection and Focus method. As shown in FIG. 8, the BPF DACF-type electron gun includes three cathodes K arranged in a row and first to fourth grids G1 to G4 sequentially arranged from the cathodes K in the direction of the phosphor screen. The third grid G3 is formed in a structure divided into two grids G31 and G32. These grids G1 to G2, G31, G
32 and G4 are each formed in an integral structure, each having 3
Three electron beam passage holes are formed in one row corresponding to the three cathodes K.

In this electron gun, each cathode K has about 150
A voltage of V is applied, the first grid G1 is grounded, and a voltage of about 700 V is applied to the second grid G2. The voltage applied to the divided grid G31 of the third grid G3 is about 6 kV, and the voltage applied to the divided grid G32 is the reference voltage, which dynamically changes in synchronization with the change in the deflection magnetic field generated by the deflection yoke. A parapolar voltage is applied, which is the lowest when the electron beam is directed toward the center of the screen without being deflected, and the highest when the electron beam is deflected to the corner of the screen. A high voltage of about 26 kV is applied to the fourth grid G4.

By the application of such a voltage, in the electron gun, the cathode K and the first and second grids G1, G2
Form a triode that generates an electron beam and forms an object point with respect to a main lens, which will be described later. The split grid G31 of the second and third grids G3 prefocuses the electron beam from the triode. A prefocus lens is formed. The division grids G31 and G32 form a quadrupole lens that converges horizontally and diverges vertically according to the deflection angle of the electron beam. Further, the split grid G32 and the fourth grid G4 form a bi-potential (BPF) type main lens for finally focusing the electron beam on the phosphor screen.

In this electron gun, when the electron beam goes to the center of the screen without being deflected, the divided grid G3
No quadrupole lens is formed between 1 and G32, and the electron beam from the tripole portion is prefocused by the prefocus lens and then focused on the center of the screen by the main lens.

On the other hand, when the electron beam is deflected toward the periphery of the screen, the voltage of the division grid G32 increases according to the deflection angle of the electron beam, and the division grid G3
A quadrupole lens is formed between 1 and G32 to converge the electron beam in the horizontal direction and diverge in the vertical direction. At the same time, the strength of the main lens formed by the divided grid G32 and the fourth grid G4 becomes weak. As a result, when the screen is deflected toward the periphery of the screen, the distance between the electron gun and the phosphor screen is increased by electro-optics, and the lens magnification is changed in response to the image point becoming longer. The deflection aberration caused by the horizontal deflection magnetic field generated by the yoke being a pincushion type and the vertical deflection magnetic field being a barrel type is compensated.

By the way, in order to improve the image quality of a color CRT, it is necessary to improve the focus characteristics over the entire screen. However, in an in-line type color cathode-ray tube having a normal electron gun that emits three electron beams arranged in a line, as shown in FIG. The beam spot 1b is distorted (horizontal collapse) into a long ellipse in the horizontal direction due to the deflection aberration, and a blur 2 occurs in the vertical direction.

However, like the electron gun shown in FIG.
It is called the F system, in which the low voltage side electrode forming the BPF type main lens is divided into a plurality of grids, and the divided grids form quadrupole lenses in accordance with the deflection of the electron beam to compensate for the deflection aberration. In an in-line type color cathode ray tube having an electron gun, as shown in FIG. 9B, the bleeding of the beam spot 1b at the peripheral portion of the screen can be eliminated and the focus characteristic can be improved, but the beam spot at the peripheral portion of the screen can be improved. The horizontal collapse of 1b is not resolved. As a result, moire is caused by interference with the electron beam passage holes of the shadow mask, and there is a problem that display of characters and the like on a screen becomes difficult to see.

As a countermeasure, in the above-mentioned electron gun, as shown in FIG. 8, a non-circular electron having a long axis in the horizontal direction is provided on the surface of the second grid G2 facing the divided grid G31 of the third grid G3. The beam passing hole 4 is formed so that the horizontal focus of the prefocus lens formed by the second grid G2 and the division grid G31 is weaker than the vertical focus, and the virtual object point diameter in the horizontal direction with respect to the main lens. Shrink,
The virtual virtual object point diameter in the vertical direction is enlarged, so that FIG.
As shown in (c), the beam spot 1a at the center of the screen
At the same time, the horizontal squashing of the beam spot 1b at the peripheral portion is alleviated to prevent moire caused by interference with the electron beam passage hole of the shadow mask.

However, in this electron gun, as the depth of the non-circular electron beam passage hole 4 whose major axis is in the horizontal direction of the second grid becomes deeper, the horizontal collapse of the beam spot 1b at the periphery of the screen can be alleviated. At the same time, the vertical length of the beam spot 1a at the center of the screen is promoted, and the diameter of the beam spot in the vertical direction is enlarged, so that the resolution at the center of the screen is degraded.

[0013]

As described above, in order to improve the image quality of a color CRT, it is necessary to maintain a good focus state over the entire screen and to reduce the elliptic distortion of the beam spot. .

In this respect, in the conventional BPF type DACF type electron gun, the electron beam is deflected on the low voltage side grid forming the BPF type main lens in synchronization with the change of the deflection magnetic field. Applying a parapolar voltage that is lowest when heading toward the center of the screen and highest when heading toward the corner of the screen without changing the intensity of the main lens and forming a quadrupole lens, deflection aberration , The beam spot in the peripheral portion of the screen due to the vertical direction can be eliminated, and the focus characteristics can be improved. However, with this electron gun, the horizontal collapse of the beam spot at the periphery of the screen cannot be eliminated, and moire is caused by interference with the electron beam passage holes of the shadow mask, making it difficult to see characters and the like on the screen. Occurs.

In order to eliminate the horizontal collapse of the beam spot at the peripheral portion of the screen, a non-circular electron beam passage hole having a long axis in the horizontal direction is formed on a surface of the second grid facing the third grid. Is formed, the horizontal collapse of the beam spot at the peripheral portion of the screen is reduced, and moire caused by interference with the electron beam passage hole of the shadow mask can be prevented. However, the beam spot at the center of the screen becomes vertically long.
In addition, the deeper the non-circular electron beam passage hole having the long axis in the horizontal direction of the second grid, the more the lateral collapse of the beam spot at the peripheral portion of the screen can be alleviated.
The vertical length of the beam spot at the center of the screen is promoted, and the resolution at the center of the screen deteriorates.

That is, with the conventional electron gun, it is difficult to optimize the beam spot shape over the entire screen, and there is a problem that a compromise design must be made over the entire screen.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the invention is to provide a color CRT device in which the shape of a beam spot over the entire screen is good and good focus characteristics can be obtained over the entire screen. And

[0018]

The present invention has a cathode and a plurality of grids arranged in the direction of the phosphor screen from the cathode, and an electron beam generator for generating an electron beam by the cathode and the plurality of grids. A pre-focus lens for pre-focusing the electron beam from the beam generator, an electron gun for forming a main lens for finally focusing the electron beam pre-focused by the pre-focus lens on the phosphor screen, and In a color cathode ray tube device having a pincushion type horizontal deflection magnetic field for deflecting the emitted electron beam and a deflection yoke for generating a barrel type vertical deflection magnetic field, an electron gun is provided.
A voltage that dynamically changes in synchronization with a change in the deflection magnetic field is applied to at least one grid forming the prefocus lens and at least one grid forming the main lens, and this voltage is applied to the prefocus lens. Form a multipole lens whose horizontal focusing is weaker than the vertical focusing and the intensity dynamically changes, and at least a part of the main lens has the horizontal focusing stronger than the vertical focusing and the intensity is dynamic. It is configured to form a unipotential multipole lens that changes gradually.

A cathode and an electron beam generator for generating an electron beam by a first grid and a second grid sequentially arranged in the direction of the phosphor screen from the cathode;
A prefocus lens for prefocusing the electron beam from the electron beam generator between the grid and a third grid disposed on the phosphor screen side of the second grid;
An electron gun forming a main lens for finally focusing the electron beam prefocused by the prefocus lens on the phosphor screen between the grid and the plurality of grids arranged on the phosphor screen side of the third grid; And a deflection yoke for generating a pincushion-type horizontal deflection magnetic field and a barrel-type vertical deflection magnetic field for deflecting the electron beam emitted from the electron gun. Forming a non-circular electron beam passage hole having a long axis in the horizontal direction on the third grid side of the second grid, and a non-circular electron beam passage hole having a long axis in the vertical direction in the auxiliary grid; A voltage that dynamically changes in synchronization with a change in the deflection magnetic field is applied to the auxiliary grid, and the voltage applied to the auxiliary grid is always the second grid voltage. ≦ auxiliary grid voltage <the relationship of the third grid voltage. Further, the grid on the low voltage side forming the main lens is divided into a plurality of grids, and at least one of the divided grids has a non-circular electron beam passage hole having a long axis in the horizontal direction and another divided grid. A non-circular electron beam passage hole with a long axis in the vertical direction is formed, and a divided grid in which a non-circular electron beam passage hole with a long axis in the horizontal direction is formed in synchronization with a change in the deflection magnetic field. It was configured to apply a dynamically changing voltage.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows the configuration of an in-line type color CRT device as one embodiment. This color cathode ray tube device has an envelope composed of a substantially rectangular panel 10 and a funnel 11 having a funnel shape, and a dot-shaped three-color fluorescent light emitting blue, green and red is provided on the inner surface of the panel 10. A phosphor screen 12 made of a body layer is provided, and a shadow mask 13 is provided inside the phosphor screen 12 so as to face the phosphor screen 12.
Is arranged. On the other hand, the neck 15 of the funnel 11
An electron gun 17 which emits three electron beams 16B, 16G, 16R arranged in a line, consisting of a center beam 16G and a pair of side beams 16B, 16R passing on the same horizontal plane, is provided therein. A deflection yoke 20 for generating a pincushion-type horizontal deflection magnetic field and a barrel-type vertical deflection magnetic field is mounted outside the vicinity of the boundary between the large diameter portion 18 and the neck 15 of the funnel 11. The three electron beams 16B and 16G emitted from the electron gun 17 are used.
, 16R are deflected by the horizontal and vertical magnetic fields generated by the deflection yoke 20, and the phosphor screen 12 is horizontally and vertically scanned through a shadow mask 13 to display a color image.

As shown in FIG. 1, the electron gun 17 has three cathodes K arranged in a row in the horizontal direction (H-axis direction), and three heaters (not shown) for heating these cathodes K separately. And first to fifth grids G1 to G5 which are sequentially arranged at predetermined intervals from the cathode K in the direction of the phosphor screen. The fourth grid G4 is
It is divided into three grids G41, G42, G43 arranged sequentially from the third grid G3 side to the fifth grid G5 direction. Further, in the electron gun 17, an auxiliary grid Gs is arranged between the second grid G2 and the third grid G3.

The three divided grids G41, G42, G43 of the first and second grids G1, G2, the auxiliary grid Gs, and the fourth grid G4 are each a plate having an integral structure whose major axis is in the arrangement direction of the cathodes K. Consists of electrodes. The third grid G3 is composed of a cylindrical electrode having a long diameter in the direction in which the cathodes K are arranged. The fifth grid G5 is composed of a cup-shaped electrode having a long diameter in the direction in which the cathodes K are arranged.

The plate surface of the first grid G1, both end surfaces of the third grid G3, and the grid G43 of the fifth grid G5
Side end faces, corresponding to three cathodes K, respectively.
The plurality of circular electron beam passage holes are formed in a row in the horizontal direction. On the other hand, as shown in FIG. 2 (a), the second grid G2 has three faces on the side facing the first grid.
Three circular electron beam passage holes 22 are formed in a row in the horizontal direction corresponding to the three cathodes K.
Three non-circular electron beam passage holes 23 having a major axis in the horizontal direction are formed in a row in the horizontal direction coaxially with each of the electron beam passage holes 22 on the side opposite to s. Further, in the auxiliary grid Gs, as shown in FIG. 2 (b), three non-circular electron beam passage holes 24 having a long axis in the vertical direction corresponding to the three cathodes K are arranged in a line in the horizontal direction. Is formed. Further, the division grid G4 of the fourth grid G4
1, G43, as shown in FIGS. 3 (a) and 3 (c),
Three non-circular electron beam passage holes 25 and 26 having a long axis in the horizontal direction are formed in a row in the horizontal direction corresponding to the three cathodes K. In the divided grid G42 of the fourth grid G4, as shown in FIG. 3B, three non-circular electron beam passage holes 27 having a long axis in the vertical direction corresponding to the three cathodes K are horizontally arranged. They are formed in a line in the direction.

In the electron gun 17, each cathode K has about 1
A voltage of 50 V is applied, the first grid G1 is grounded, and a voltage of about 700 V is applied to the second grid G2. The auxiliary grid Gs has a horizontal and vertical deflection magnetic field generated by the deflection yoke, that is, as shown in FIGS. 5A and 5B, with a voltage of about 700 V applied to the second grid G2 as a reference voltage. , Vertical deflection current 29H,
A parabolic voltage which dynamically changes in synchronization with 29V and is lowest when the electron beam is directed toward the center of the screen without being deflected, and is highest when directed toward the corner of the screen.
0H and 30V are applied. A high voltage of about 26 kV is applied to the third grid G3. That is, the voltages applied to the second grid G2, the auxiliary grid Gs, and the third grid G3 satisfy the following relationship: second grid voltage ≦ auxiliary grid voltage <third grid voltage.

The division grids G41, G of the fourth grid G4
Numeral 43 is connected to an auxiliary grid Gs in the tube, and a dynamically changing parabolic voltage is applied to the auxiliary grid Gs in the same manner as the voltage applied to the auxiliary grid Gs. These divided grids G
The divided grid G42 located between 41 and G43 has about 700
A voltage of V is applied. The fifth grid G5 is connected to the third grid G3 in the tube, and a high voltage of about 26 kV, which is the same as the voltage applied to the third grid G3, is applied.

By applying such a voltage, in the electron gun 17, the cathode K and the first and second grids G 1, G 1,
G2 forms an electron beam and forms an object point with respect to the main lens, which will be described later. A triode is formed by the second grid G2, the auxiliary grid Gs and the third grid G3. A pre-focusing lens for pre-focusing is formed, and the electron beam pre-focused by the pre-focusing lens is finally formed by three divided grids G41, G42, G43 of a third grid G3, a fourth grid G4, and a fifth grid G5. A unipotential (UPF) type main lens is formed on the phosphor screen.

The second forming the pre-focus lens
The grid G2 has three non-circular electron beam passage holes 23 whose major axis is in the horizontal direction on the side facing the auxiliary grid Gs, so that the horizontal focusing is weaker than the vertical focusing. It has astigmatism (negative astigmatism). On the other hand, the auxiliary grid Gs is formed with three non-circular electron beam passage holes 24 having the long axis in the vertical direction, so that the focusing in the horizontal direction is stronger than the focusing in the vertical direction. Astigmatism). However, since the second grid G2 and the auxiliary grid Gs have substantially the same potential when the electron beam is directed toward the center of the screen without being deflected (when there is no deflection), the positive and negative astigmatisms are cancelled, and the prefocusing is performed. The lens will have no or very weak astigmatism. However, when the electron beam is deflected toward the periphery of the screen, the second grid G2
The voltage of the auxiliary grid Gs becomes higher than the voltage of the above, causing negative astigmatism.

As for the main lens, the divided grid G
Since the three non-circular electron beam passage holes 25 and 26 having the long axis in the horizontal direction are formed in 41 and G43, the horizontal focusing has a weaker astigmatism than the vertical focusing. . On the other hand, in the division grid G42, since three non-circular electron beam passage holes 27 having the long axis in the vertical direction are formed, the positive astigmatism in which the horizontal focusing is stronger than the vertical focusing is provided. However, when the electron beam goes to the center of the screen without being deflected, these divided grids G41, G41,
Since G43 and the divided grid G42 have almost the same potential,
The positive and negative astigmatisms cancel each other out, and the astigmatism has no astigmatism, or at least has weak astigmatism.
On the other hand, when the electron beam is deflected toward the peripheral portion of the screen, the voltages of the divided grids G41 and G43 become higher than the voltage of the divided grid G42, and have positive astigmatism.

Therefore, when the electron beam is directed toward the center of the phosphor screen without being deflected, the electron beam from the triode portion is applied to the second grid G2 and the auxiliary grid G.
s and the pre-focusing lens formed by the third grid G3 preliminarily focuses without causing astigmatism, and thereafter the divided grids G41, G42, G43 and the fifth grid G5 of the third grid G3, the fourth grid G4. Is focused on the phosphor screen with almost no astigmatism. As a result, as shown in FIG.
The beam spot 32a at the center of the screen is substantially circular.

On the other hand, when the electron beam is deflected in the peripheral direction of the phosphor screen, the second grid G2
Are preliminarily focused by the prefocus lens formed by the auxiliary grid Gs and the third grid G3. At this time, the voltage of the auxiliary grid Gs becomes higher than the voltage of the second grid G2, and negative astigmatism is reduced. Since it is formed, the virtual object point diameter in the horizontal direction with respect to the main lens is larger and the virtual object point diameter in the vertical direction is smaller than in the case of no deflection. In addition, the divergence angle in the horizontal direction is larger and the divergence angle in the vertical direction is smaller than when there is no deflection. Thereafter, the electron beam prefocused as described above is applied to the third grid G3.
, The fourth grid G4 divided grids G41, G42, G43
Focusing is performed by the unipotential type main lens formed by the fifth grid G5, and in this case, the voltage of the divided grids G41 and G43 becomes higher than the voltage of the divided grid G42, and positive astigmatism is formed. You. Thereby, the deflection aberration is corrected. Also, the divergence angle of the electron beam changed by the negative astigmatism of the prefocus lens is corrected. As a result, the electron beam focused by this main lens forms an image on the periphery of the screen in both the horizontal and vertical directions,
As the horizontal diameter of the virtual object point increases due to the negative astigmatism of the prefocus lens, the horizontal diameter of the beam spot around the surface increases, and the vertical horizontal diameter of the virtual object point decreases. As a result, the horizontal diameter of the beam spot at the peripheral portion of the surface is reduced, and the horizontal collapse of the beam spot is reduced. As shown in FIG. 6, the beam spot 32b at the peripheral portion of the screen approaches a circle.

Therefore, by configuring the electron gun 17 as described above, it is possible to eliminate the bleeding of the beam spot over the entire screen and to reduce the elliptic distortion to make it almost circular. A color CRT device that displays a good image can be provided.

Next, an electron gun having a configuration different from that of the above embodiment will be described. In this electron gun, the main lens of the electron gun in the above embodiment is a unipotential type, whereas the main lens is a compound type of a bipotential electron lens and a unipotential electron lens.

That is, as shown in FIG. 7, the electron gun 17 includes three cathodes K arranged in a row in the horizontal direction, three heaters (not shown) for heating these cathodes K separately, and First to sixth grids G1 to G6 are sequentially arranged at predetermined intervals in the direction of the phosphor screen from the cathode K, and the fourth grid G4 is the third grid G4.
A configuration in which the grid G3 is divided into three grids G41, G42 and G43 sequentially arranged in the direction of the fifth grid G5 from the grid G3 side, and an auxiliary grid Gs is further arranged between the second grid G2 and the third grid G3. Has become.

The three divided grids G41, G42, G43 of the first and second grids G1, G2, the auxiliary grid Gs, and the fourth grid G4 are each a plate-like member having an integral structure whose major axis is in the direction in which the cathodes K are arranged. The electrodes, the third and fifth grids G3 and G5 are cylindrical electrodes of an integral structure having a longer diameter in the arrangement direction of the cathodes K, and the sixth grid G6 is a cup-shaped electrode of an integral structure having a longer diameter in the arrangement direction of the cathodes K. Consists of

The plate surface of the first grid G1, the both end surfaces of the third grid G3, the both end surfaces of the fifth grid G5 and the sixth
On the end face of the grid G6 on the fifth grid G5 side, three circular electron beam passage holes corresponding to the three cathodes K are formed in a row in the horizontal direction. On the other hand, in the second grid G2, three circular electron beam passage holes 22 corresponding to the three cathodes K are formed in a row in the horizontal direction on the surface facing the first grid, and On the side facing the grid Gs, three non-circular electron beam passage holes 23 having a long axis in the horizontal direction are formed coaxially with the electron beam passage holes 22 in a row in the horizontal direction (FIG. 2).
(A)). In the auxiliary grid Gs, three non-circular electron beam passage holes 24 having a long axis in the vertical direction corresponding to the three cathodes K are formed in a row in the horizontal direction (see FIG. 2B). ). Also, in the divided grids G41 and G43 of the fourth grid G4, three non-circular electron beam passage holes 25 having a long axis in the horizontal direction corresponding to the three cathodes K,
26 are formed in a line in the horizontal direction (FIG. 3A,
(See (c)), three non-circular electron beam passage holes 27 having a long axis in the vertical direction corresponding to the three cathodes K are arranged in a row in the divided grid G42 of the fourth grid G4. (See FIG. 3B).

In this electron gun 17, each cathode K has about 1
A voltage of 50 V is applied, the first grid G1 is grounded, and a voltage of about 700 V is applied to the second grid G2. The auxiliary grid Gs and the divided grids G41 and G43 of the fourth grid G4 are connected in a tube, and a voltage of about 700 V applied to the second grid G2 is applied to the auxiliary grid Gs and the divided grids G41 and G43 as a reference voltage. Parabolic shape that changes dynamically in synchronization with the horizontal and vertical deflection magnetic fields generated by the deflection yoke, and is lowest when the electron beam goes to the center of the screen without being deflected, and becomes highest when it goes to the corner of the screen. (See FIGS. 5A and 5B). The third grid G3 and the fifth grid G5 are connected in a tube, and a voltage of about 700 V is applied to the third and fifth grids G3 and G5. A voltage of about several kV is applied to the divided grid G42 of the fourth grid G4. A high voltage of about 26 kV is applied to the sixth grid G6.

Even when the electron gun 17 is configured in this manner, the same effect as that of the electron gun according to the above-described embodiment can be obtained, the bleeding of the beam spot is eliminated over the entire screen, and the elliptic distortion is reduced to make the electron gun almost circular. Thus, a color CRT device that displays a good image by making the focus state of the entire screen uniform can be achieved.

In the above-described embodiment, the horizontal axis is the major axis on the side of the second grid facing the auxiliary grid.
The non-circular electron beam passage holes were formed in a line,
Instead of the three non-circular electron beam passage holes, a horizontally long groove extending in the horizontal direction may be used.

[0040]

As described above, when the electron gun is constructed, it is possible to eliminate the bleeding of the beam spot over the entire screen and to reduce the elliptic distortion to make it almost circular, thereby making the focus state over the entire screen uniform. And a color CRT device that displays a good image.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an electron gun of an in-line type color cathode ray tube according to an embodiment of the present invention.

FIG. 2A is a view showing a shape of an electron beam passage hole of a second grid of the electron gun, and FIG. 2B is a view showing a shape of an electron beam passage hole of an auxiliary grid.

FIGS. 3A to 3C are diagrams showing the shapes of electron beam passage holes of three divided grids of a fourth grid of the electron gun, respectively.

FIG. 4 is a diagram showing a configuration of an in-line type color CRT according to an embodiment of the present invention.

5A is a diagram showing a voltage that changes in synchronization with a horizontal deflection current applied to two divided grids of the auxiliary grid and the fourth grid, and FIG. 5B is a diagram showing the same. FIG. 6 is a diagram illustrating a voltage that changes in synchronization with a vertical deflection current.

FIG. 6 is a diagram for explaining the shape of a beam spot on a screen of an in-line type color CRT according to an embodiment of the present invention.

FIG. 7 is a diagram showing a configuration of an electron gun different from the electron gun shown in FIG.

FIG. 8 is a diagram showing a configuration of a conventional electron gun of an in-line type color cathode ray tube.

FIG. 9A is a view for explaining the shape of a beam spot on the screen of a conventional color CRT having an ordinary in-line type electron gun, and FIG. 9B is a bi-potential DACF type electron gun. For explaining the shape of a beam spot on the screen of a color CRT having
(C) Shape of a beam spot on the screen of a color cathode-ray tube having an electron gun having three non-circular electron beam passage holes having a major axis in the horizontal direction in the second grid of the bipotential DACF electron gun. FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 ... Phosphor screen 16B, 16R ... A pair of side beams 16G ... Center beam 17 ... Electron gun 20 ... Deflection yoke 22 ... Electron beam passage hole 23 ... Electron beam passage hole 24 ... Electron beam passage hole 25 ... Electron beam passage hole 26 ... Electron beam passage hole 27 ... Electron beam passage hole G1 ... First grid G2 ... Second grid G3 ... Third grid G4 ... Fourth grid G41 ... Fourth grid division lid G42 ... Fourth grid division grid G43 ... Second grid Four grids divided grid G5 ... fifth grid G6 ... sixth grid Gs ... auxiliary grid K ... cathode

Claims (3)

[Claims] A cathode having a plurality of grids arranged in a direction from the cathode toward a phosphor screen;
An electron beam generator for generating an electron beam by these cathodes and a plurality of grids, a prefocus lens for prefocusing the electron beam from the electron beam generator, and an electron beam preliminarily focused by the prefocus lens. A collar comprising: an electron gun forming a main lens focused on the phosphor screen; and a deflection yoke for generating a pincushion-type horizontal deflection magnetic field and a barrel-type vertical deflection magnetic field for deflecting an electron beam emitted from the electron gun. In the cathode ray tube device, the electron gun applies a voltage that dynamically changes in synchronization with a change in the deflection magnetic field to at least one grid forming the prefocus lens and at least one grid forming the main lens. By applying this voltage, the prefocus lens is A multipole lens is formed in which the focusing in the direction is weaker than the focusing in the vertical direction and the intensity is dynamically changed, and the main lens has horizontal focusing at least partially stronger and stronger than the vertical focusing. A color CRT device comprising a dynamically changing unipotential multipole lens. 2. A cathode, an electron beam generator for generating an electron beam by a first grid and a second grid sequentially arranged in the direction of the phosphor screen from the cathode, a second grid, and a second grid on the phosphor screen side. A prefocus lens for prefocusing the electron beam from the electron beam generator between the third grids to be arranged;
Electrons forming a main lens that finally focuses the electron beam prefocused by the prefocus lens on the phosphor screen between the grid and a plurality of grids arranged on the phosphor screen side of the third grid. In a color cathode ray tube device comprising a gun and a deflection yoke for generating a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field for deflecting an electron beam emitted from the electron gun, an auxiliary device is provided between the second and third grids. Grit is placed,
A non-circular electron beam passage hole having a long axis in the horizontal direction is formed on the third grid side of the second grid, and a non-circular electron beam passage hole having a long axis in the vertical direction is formed in the auxiliary grid. In addition, a voltage that dynamically changes in synchronization with the change in the deflection magnetic field is applied to the auxiliary grid, and the voltage applied to the auxiliary grid is always in the relationship of the second grid voltage ≦ the auxiliary grid voltage <the third grid voltage. A color CRT device characterized in that: 3. The grid on the low voltage side forming the main lens is divided into a plurality of grids, and at least one of the divided grids has a non-circular electron beam passage hole having a long axis in the horizontal direction, and other grids. A non-circular electron beam passage hole having a long axis in the vertical direction is formed in the divided grid, and a deflection magnetic field changes in the divided grid in which the non-circular electron beam passage hole having the long axis in the horizontal direction is formed. 3. A color CRT device according to claim 2, wherein a voltage that dynamically changes in synchronization with the voltage is applied.