JP2000231890A - Color cathode ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode ray tube device capable of displaying a high quality image by reducing elliptical distortion of a beam spot on a whole display surface. SOLUTION: This color cathode ray tube device includes an electron gun comprising a main lens 4 and at least one multipolar lens 6a, 6b for passing an electron beam before incident to the main lens 4. The electron gun is structured so that focusing force of the main lens 4 and the multipolar lens 6a, 6b changes in synchronization with a deflecting value of a deflection yoke. As the deflecting value of the deflection yoke increases, the focusing force in a horizontal direction of the main lens 4 is relatively strengthened and the focusing force in a vertical direction is relatively weakened, and the focusing force in a horizontal direction of the multipolar lens is relatively weakened and the focusing force in a vertical direction of the multipolar lens is relatively strengthened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube device, and more particularly to a color cathode ray tube device which displays a high-quality image by reducing elliptic distortion of a beam spot in a peripheral portion of a screen.

[0002]

2. Description of the Related Art In general, a color cathode ray tube device has an envelope composed of a panel and a funnel, and three electron beams emitted from an electron gun disposed in the neck of the funnel are mounted on the outside of the funnel. Horizontal and vertical deflection magnetic fields generated by the deflection yoke, and a horizontal and vertical scan of a phosphor screen provided on the inner surface of the panel through a shadow mask to form a structure for displaying a color image. ing.

At present, such a color cathode ray tube apparatus is of an inline type in which an electron gun emits three electron beams arranged in a line composed 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 CRT device that concentrates three electron beams over the entire screen without the need for a special correction circuit using these horizontal and vertical deflection magnetic fields. Has been put to practical use.

There are various types of electron guns that emit three electron beams arranged in a line, and one of them is a bi-potential [BPF (Bi-Potential)].
Focus)] type DAC & F (Dynamic Ast)
igmatism Correction and F
There is an electron gun called an ocus type.

As shown in FIG. 12, this electron gun has three cathodes K arranged in a line, and a first grid G 1, a second grid G 2, and a monolithic structure which are sequentially arranged from the cathode K in the direction of the phosphor screen. It has two divided electrodes G31 and G32 of the third grid G3 and a fourth grid G4.
In each of the electrodes, three electron beam passage holes corresponding to the three cathodes K are formed in a line.

In this electron gun, a voltage obtained by superimposing a video signal on a voltage of 150 V is applied to the cathode K, and the first grid G1 is grounded. About 600 in the second grid G2
V, a voltage of about 6 kV is applied to the divided electrode G31 of the third grid G3 and about 6 kV is applied to the divided electrode G32 in accordance with the deflection amount of the electron beam of the deflection yoke. A fluctuating voltage on which a parabolic voltage that becomes higher is superimposed is applied. A voltage of about 26 kV is applied to the fourth grid G4.

As a result, the cathode K and the first and second
The grids G1 and G2 form a triode that generates an electron beam and forms an object point with respect to a main lens described later. The pre-focus lens for pre-focusing the electron beam from the triode is formed by the divided electrodes G31 of the second grid G2 and the third grid G3. The divided electrode G32 of the third grid G3 and the fourth grid G4 finally form a BPF type main lens for accelerating and focusing the electron beam on the phosphor screen.

When the electron beam is deflected to the corner of the phosphor screen, the potential difference between the divided electrode G32 and the fourth grid G4 becomes the smallest, and the intensity of the main lens becomes the weakest. At the same time, a quadrupole lens that converges in the horizontal direction and diverges in the vertical direction is formed between the divided electrodes G31 and G32, and the intensity is maximized. Thereby, when the electron beam is deflected to the corner of the phosphor screen,
In response to the greatest distance from the electron gun to the phosphor screen and the longer image point, compensation is made by weakening the strength of the main lens. Also, the divided electrodes G31, G
A quadrupole lens between 32 compensates for the deflection aberration generated by the pincushion-type horizontal deflection magnetic field and the barrel-type vertical deflection magnetic field of the deflection yoke.

Incidentally, in order to improve the image quality of the color CRT device, it is necessary to improve the focus characteristics and the beam spot shape on the phosphor screen. In particular, in an in-line type color CRT device that emits three electron beams arranged in a row, as shown in FIG. 13, the beam spot 1 at the center of the screen can be made circular, but from the end of the horizontal axis (X axis). As shown with respect to the diagonal axis end, the beam spot 1 in the peripheral portion is distorted in an elliptical shape due to deflection aberration (horizontal collapse), and blur 2 occurs.

However, the bleeding 2 of the beam spot 1
Describes a method of dividing a low-voltage side electrode forming a main lens into a plurality of electrodes like a third grid G3 of the electron gun.
By using the C & F method, the problem can be solved as shown in FIG. However, the elliptical distortion of the beam spot 1 at the periphery of the screen is not eliminated. For this reason, the elliptical distortion interferes with the electron beam passage hole of the shadow mask, causing moire and the like, and makes it difficult to see characters and the like when displayed.

The phenomenon of lateral collapse of the beam spot 1 at the peripheral portion will be described with reference to optical models shown in FIGS. In FIG. 15, 4 is a main lens, 5 is a phosphor screen, 6 is a quadrupole lens, and 7 is a quadrupole lens formed by a deflection magnetic field.

Generally, the size of the beam spot on the screen depends on the magnification M. The magnification M can be represented by the ratio α0 / αi between the divergence angle α0 and the incident angle αi of the electron beam 8. Then, if the horizontal magnification is Mh, the vertical magnification is Mv, the horizontal divergence angle α0h, the incident angle αih, the vertical divergence angle α0v, and the incident angle αiv are as follows: Mh = α0h / αih Mv = α0v / αiv It is represented by

Accordingly, when α0h = α0v, αih = αiv Mh = Mv when there is no deflection shown in FIG. 15A, and the beam spot at the center of the screen is circular. On the other hand, at the time of deflection shown in FIG. 15B, αih <αivMh> Mv, and the beam spot in the peripheral portion becomes horizontally long.

As a means for solving the elliptical distortion of the beam spot at the periphery of the screen, there is an electron gun called a double quadrupole lens system. As shown in FIG. 16, this electron gun has a first grid G1, a second grid G2, and a third grid G3 of an integral structure which are sequentially arranged in a row from three cathodes K in the phosphor screen direction. Split electrode G
31, G32, G33 and a fourth grid G4.

In this electron gun, the first quadrupole lens and the split electrode G are divided by the split electrodes G31 and G32 of the third grid G3.
32 and G33 form a second quadrupole lens. The divided electrodes G31 and G33 are electrically connected to each other, and to these divided electrodes G31 and G33, a fluctuating voltage in which a parabolic voltage that increases in accordance with the deflection amount of the electron beam of the deflection yoke is applied is applied. When deflected, the first quadrupole lens has a diverging action in the horizontal direction and a focusing action in the vertical direction, and the second quadrupole lens has a focusing action in the horizontal direction and a diverging action in the vertical direction. .

FIG. 17 shows an optical model of the electron gun.
4 is the main lens, 5 is the phosphor screen, 6a is the first 4
A pole lens, 6b is a second quadrupole lens, and 7 is a quadrupole lens formed by a deflection magnetic field. In this case, the horizontal magnification is Mh ′, the vertical magnification is Mv ′, the horizontal divergence angle α0h ′, the incident angle αih ′, and the vertical divergence angle α.
Assuming that 0v ′ and the incident angle αiv ′, Mh ′ = α0h ′ / αih ′ Mv ′ = α0v ′ / αiv ′, α0h ′ = α0v ′ αih ′ = αiv ′, and Mh ′ = Mv ′ holds. .

That is, if the double quadrupole lens system is used, the beam spot shape on the screen becomes a circle in theory of magnification. However, actually, as shown in FIG. 18, the vertical diameter Ssv of the beam spot 1 is enlarged, but the horizontal diameter Ssh is not reduced, and the average diameter ((Ssv + Ssh) / 2) of the beam spot 1 is As a result, the beam spot 1 on the screen is enlarged, which deteriorates the image.

The reason that the horizontal diameter Ssh of the beam spot 1 is not reduced by the theory of magnification as described above is that the electron beam is converged and diverged by the first and second quadrupole lenses, and the aberration of the quadrupole lens is reduced. Due to increased impact. Further, the electron beam diameter Dh 'incident on the main lens.
(See FIG. 17) is also large, and the influence of the spherical aberration of the main lens increases.

[0019]

As described above, in order to improve the image quality of a color CRT device, it is necessary to improve the focus characteristics and the beam spot shape on the phosphor screen.

Regarding the focus characteristic and beam spot shape, the conventional BPF type DAC & F type electron gun has a fluctuating voltage in which a parabolic voltage which increases according to the deflection amount of the deflection yoke is superimposed on the low voltage side electrode of the main lens. To make the intensity of the main lens variable,
By forming a dynamically changing quadrupole lens, it eliminates vertical bleeding of the beam spot due to deflection aberration,
And it focuses on the whole screen. But,
The elliptical distortion of the beam spot at the periphery of the screen cannot be eliminated. This is because the astigmatism of the electron lens formed by the electron gun and the deflection magnetic field causes the magnification Mh in the horizontal direction and the magnification M in the vertical direction.
v is set so that the relation of Mh> Mv is satisfied.

As means for solving the elliptical distortion of the beam spot at the periphery of the screen, there is an electron gun called a double quadrupole lens system. According to this electron gun, even if Mh = Mv can be theoretically set, the electron beam is affected by the aberration of the quadrupole lens in the horizontal direction and the spherical aberration of the main lens, and the image is projected over the entire screen. Quality cannot be improved.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to constitute a color CRT device which displays a high-quality image by reducing elliptic distortion of a beam spot on the entire screen. I do.

[0023]

SUMMARY OF THE INVENTION An electron gun having at least a focus electrode and an anode electrode and having a main lens formed thereon for accelerating and converging an electron beam on a phosphor screen, and electrons emitted from the electron gun In a color cathode ray tube apparatus having a deflection yoke for deflecting a beam in a horizontal direction and a vertical direction, an electron gun is provided with at least one multipole lens through which an electron beam passes before entering the main lens. The focusing force of the pole lens changes in synchronization with the deflection of the deflection yoke. With the increase in the deflection amount of the deflection yoke, the horizontal focusing force of the main lens is relatively strong, and the vertical focusing force is relatively small. And the horizontal focusing power of the multipole lens is relatively weak and the vertical focusing power is relatively strong as the deflection amount of the deflection yoke increases.

At least one additional electrode is disposed between the focus electrode and the anode electrode forming the main lens. The voltage of the focus electrode is Vf, the voltage of the anode electrode is Eb, and the voltage of the additional electrode is Vs. In this case, the value of (Vs-Vf) / (Eb-Vf) changes in accordance with the change in the deflection amount of the deflection yoke.

Further, a configuration is adopted in which a fluctuating voltage that increases as the deflection amount of the deflection yoke increases is applied to the focus electrode.

Furthermore, at least one electrode forming the multipole lens is electrically connected to a focus electrode forming the main lens.

[0027]

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

According to the present invention, in the above-described electron gun of the double quadrupole lens type, the second quadrupole lens is formed at the center of the main lens to eliminate the difference between the horizontal and vertical magnifications Mh and Mv. In addition, the basic configuration is to reduce the aberration of the quadrupole lens and the aberration of the main lens.

As shown in FIG. 15B, the conventional DP
In the F-type DAC & F type electron gun, since the horizontal and vertical magnifications Mh and Mv represented by Mh = α0h / αih Mv = α0v / αiv satisfy αih <αiv at the periphery of the screen, Mh> Mv. Was. Therefore, in order to eliminate the difference between Mh and Mv, αih should be increased and αiv should be reduced.

In a conventional double quadrupole lens type electron gun,
As shown in FIG. 17, Mh ′ = α0h ′ / αih ′ Mv ′ = α0v ′ / αiv ′ and αih ′ = αiv ′, so that Mh ′ = Mv ′, and the magnification difference in the horizontal and vertical directions Has been resolved. However, in the conventional double quadrupole lens type electron gun, the horizontal diameter of the beam spot is not reduced due to the aberration of the quadrupole lens and the spherical aberration of the main lens.

In order to reduce the aberration of the quadrupole lens, the divergence angles θQ1h ′ and θQ2h ′ shown in FIG. 17 may be reduced by weakening the intensity of the quadrupole lens.
When h ′ and θQ2h ′ are reduced, Mh ′> Mv ′, and the horizontal diameter of the beam spot cannot be reduced.

Further, the spherical aberration of the main lens can be reduced by reducing the electron beam diameter Dh 'when entering the main lens. For this purpose, as described in the quadrupole lens, θQ1h , ΘQ2h 'must be reduced, and Mh'> Mv ', so that the horizontal diameter of the beam spot cannot be reduced.

Therefore, in the present invention, as shown in FIG. 1, a quadrupole lens 6b corresponding to the second quadrupole lens of the conventional double quadrupole lens type electron gun is formed in the main lens 4. . In this case, the horizontal magnification is Mh '
, Vertical magnification Mv ″, horizontal divergence angle α
0h '', incident angle αih '', vertical divergence angle α0v ''
Assuming that the incident angle is αiv ″, Mh ″ = α0h ″ / αih ″ Mv ″ = α0v ″ / αiv ″, and αih ″ = αiv ″, so that Mh ″ = Mv ″, and the difference in magnification in the horizontal and vertical directions can be eliminated. Further, a second quadrupole lens 6 is provided at the center of the main lens 4.
By forming b, the distance between the first quadrupole lens 6a and the second quadrupole lens 6b can be increased, and the first and second quadrupole lenses 6a and 6b can be enlarged.
The divergence angle θQ1h ″ of the polar lens 6a, 6b in the horizontal direction,
θQ2h ″, vertical divergence angle θQ1v ″, θQ2v ″
ΘQ1h ′> θQ1h ″ θQ2h ″> θQ2h ″ θQ1v ″> θQ1v ″ θQ2v ″> θQ2v ″, and the aberration of the quadrupole lens can be reduced.

Further, by forming the second quadrupole lens 6b at the center of the main lens 4, the electron beam diameter Dh '' when entering the main lens becomes Dh ''> Dh '', and Spherical aberration can be reduced.

That is, when the quadrupole lens 6b corresponding to the second quadrupole lens of the conventional double quadrupole lens type electron gun is formed in the main lens 4 as described above, the electron beam is transmitted to the peripheral portion of the screen. 2. The difference in magnification in the horizontal and vertical directions that occurs when the light beam is deflected in the horizontal direction can be eliminated, and the aberration of the quadrupole lens and the spherical aberration of the main lens are alleviated. As shown in FIG. Can be eliminated.

Next, a method of forming the dynamically changing quadrupole lens 6b in the main lens and its operation will be described.

FIG. 3A shows a plate shape in which a vertically long non-circular electron beam passage hole 10 having a vertical diameter larger than the horizontal diameter is formed at the geometric center of the rotationally symmetric BPF type main lens 4. Is disposed on the focus electrode Gf.
kV, the anode electrode Ga is 26 kV, and the additional electrode Gs is 1
The potential distribution when a potential of 6 kV is applied is shown. In this case, the main lens 4 moves the electron beam 1 in both the horizontal and vertical directions.
Give 1 the same focusing power.

However, when a potential lower than 16 kV is applied to the additional electrode Gs, the focus electrode Gf is moved from the anode electrode Ga side through the electron beam passage hole 10 of the additional electrode Gs, as shown in FIG. The potential penetrates to the side, forming an aperture lens. In this case, the additional electrode G
Since the electron beam passing hole 10 of s is vertically long, the focusing force in the horizontal direction becomes stronger than the focusing force in the vertical direction. As a result, the main lens 4 has astigmatism, and has a quadrupole lens function.

When a potential higher than 16 kV is applied to the additional electrode Gs, as shown in FIG.
s of the focus electrode G through the electron beam passage hole 10.
The potential penetrates from the f side to the anode electrode Ga side, and an aperture lens is formed. In this case, since the electron beam passage hole 10 of the additional electrode Gs is vertically long, the focusing force in the horizontal direction is weaker than the focusing force in the vertical direction, contrary to the case shown in FIG. As a result, the main lens has astigmatism opposite to that of FIG. 5, and has a quadrupole lens effect.

That is, a plate-shaped additional electrode Gs is provided in the main lens based on a BPF type lens, and
By applying a predetermined potential to s, astigmatism that adjusts the horizontal focusing power and the vertical focusing power without impairing the aperture of the main lens can be provided. A polar lens function can be provided. In the above description, the case where the astigmatism of the main lens is adjusted by changing the potential of the additional electrode has been described. In general, the voltage of the focus electrode is Vf, the voltage of the anode electrode is Eb, and the additional voltage is Eb. When the voltage of the electrode is Vs, the same adjustment can be made by changing the value of (Vs-Vf) / (Eb-Vf).

Next, embodiments of the present invention will be described with reference to examples.

[0042]

[Embodiment 1] FIG. 4 shows the overall structure of a color CRT device as one embodiment thereof. This color CRT device has an envelope composed of a panel 13 and a funnel 14 having a funnel shape, and a phosphor screen 5 composed of a three-color phosphor layer emitting blue, green, and red light is provided on the inner surface of the panel 13. Is provided. Also, facing the phosphor screen 5,
A shadow mask 16 having a large number of electron beam passage holes formed therein is arranged inside the panel 13. On the other hand, in the neck 18 of the funnel 14, a center beam 11G and a pair of side beams 11B, 11B passing on the same horizontal plane are provided.
R, three electron beams 11B, 11G, 1
An electron gun 19 for emitting 1R is provided. further,
A deflection yoke 21 is mounted from the large diameter portion 20 of the funnel 14 to the neck 18. And the above-mentioned electron gun 1
Three electron beams 11B, 11G, 11R emitted from 9
Are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 21, and the phosphor screen 5 is horizontally and vertically scanned through the shadow mask 16 to display a color image.

As shown in FIG. 5, the electron gun 19 has three cathodes K arranged in a line in the horizontal direction, three heaters (not shown) for individually heating these cathodes K, and Two divided electrodes G31 of a first grid G1, a second grid G2, and a third grid G3 of an integrated structure sequentially arranged in the direction from the cathode K to the phosphor screen.
It has five electrodes G32 and a fourth grid G4. The heater, cathode K and five electrodes are integrally fixed by a pair of insulating supports (not shown).

Of the five electrodes, the first and second grids G1 and G2 are composed of plate-like electrodes.
Three electron beam passage holes are formed in one row corresponding to the three cathodes K. The two divided electrodes G31 and G32 of the third grid G3 are cylindrical electrodes, the fourth grid G4 is a cup-shaped electrode, and both ends of the divided electrodes G31 and G32 and the divided electrode G32 side of the fourth grid G4 have three electrodes. Three electron beam passage holes are formed in one row corresponding to the three cathodes K. In particular, the electron beam passage hole on the G32 side of the divided electrode G31 has a vertical diameter larger than the horizontal diameter.
There are three vertically long non-circular electron beam passage holes. On the other hand, the electron beam passage holes on the G31 side of the divided electrode G32 are three horizontally long non-circular electron beam passage holes having a horizontal diameter larger than a vertical diameter.

Further, in this electron gun 19, the third
As shown in FIG. 6, between the divided electrode G32 of the grid G3 and the fourth grid G4, three vertically long non-circular electrons having a vertical diameter larger than a horizontal diameter corresponding to the three cathodes are provided. A plate-shaped additional electrode Gs in which the beam passage holes 10 are formed in a line is arranged.

In the electron gun 19, the cathode K is
A voltage in which a video signal is superimposed on a voltage of V
Grid G1 is grounded. About 6 in the second grid G2
00V, about 6 kV is applied to the divided electrode G31 of the third grid G3.
As shown in FIG. 7, a parabolic voltage which is synchronized with the sawtooth deflection current 23 and increases with an increase in the deflection amount is superimposed on the divided electrode G32 as shown in FIG. The fluctuating voltage 24 is applied. A voltage of about 16 kV is applied to the additional electrode Gs, and a voltage of about 26 kV is applied to the fourth grid G4.

Thus, when the electron beam is not deflected by the deflection yoke, the divided electrodes G31 and G32 have the same potential, and no electron lens is formed between the divided electrodes G31 and G32. The main lens formed by the divided electrode G32, the additional electrode Gs, and the fourth grid G4 has no astigmatism, that is, no quadrupole lens action. Therefore, the electron beam emitted from the cathode K sequentially passes through the first and second grids G1, G2 and the split electrode G31, and split electrode G32, additional electrode Gs and fourth grid G
The light is focused on the center of the phosphor screen by the main lens formed by step 4, and a substantially circular beam spot is obtained on the phosphor screen.

On the other hand, when the electron beam is deflected by the deflection yoke, the voltage of the split electrode G32 increases as the electron beam is deflected in the peripheral direction, and the split electrode G3
1, a quadrupole lens is formed between G32 and the electron beam is
It is divergent in the horizontal direction and convergent in the vertical direction. Next, this electron beam is applied to the split electrode G32 and the additional electrode Gs.
And the main lens formed by the fourth grid G4,
Since the voltage Vf of the divided electrode G32 increases, the value of (Vs-Vf) / (Eb-Vf) decreases, and the vertically long non-circular electron beam passage hole 10 is formed in the additional electrode Gs. It is converged horizontally and divergent vertically. Further, a voltage difference (Eb-Vf) between the divided electrode G32 and the fourth grid G4.
, The focusing action in the horizontal direction and the diverging action in the vertical direction are simultaneously reduced.

Therefore, the reduction of the focusing force caused by the reduction of the voltage difference (Eb-Vf) between the divided electrode G32 and the fourth grid G4 in advance and the diverging effect generated by the divided electrodes G31 and G32 are offset each other. In this configuration, the focusing condition of the electron beam is satisfied also at the peripheral portion of the screen, the magnification difference between the horizontal and vertical directions of the beam spot at the peripheral portion of the screen is eliminated, and the quadrupole lens formed by the divided electrodes G31 and G32 By reducing the aberration of the quadrupole lens formed on the main lens and reducing the diameter of the electron beam incident on the main lens, the spherical aberration of the main lens is reduced, and the elliptical distortion of the beam spot at the periphery of the screen is improved. You.

[0050]

Embodiment 2 As shown in FIG. 8, the electron gun 19 has the same structure as the electron gun shown in FIG. 5, and in particular, the electron beam passage hole of the additional electrode Gs is shown in FIG. 9 (a) or 9 (b). like,
Three or one horizontally long non-circular electron beam passage holes 10 having a horizontal diameter larger than a vertical diameter.

In this electron gun 19, the cathode K is
A voltage in which a video signal is superimposed on a voltage of V
Grid G1 is grounded. About 6 in the second grid G2
00V, about 6 kV is applied to the divided electrode G31 of the third grid G3.
As shown in FIG. 7, a parabolic voltage synchronized with the sawtooth-shaped deflection current 23 and increased as the deflection amount increases is applied to the divided electrode G32 as shown in FIG. The superimposed fluctuation voltage 24 is applied. As shown in FIG. 10, the additional electrode Gs has a fluctuation voltage 26 in which a DC voltage of about 16 kV is superimposed with a parabolic voltage synchronized with the sawtooth deflection current 23 and increased as the deflection amount increases. Applied. The fourth grid G4 has about 26 k
A voltage of V is applied.

Even with this configuration, if the electron beam is not deflected by the deflection yoke, the divided electrodes G31 and G32
And the same potential, and no electron lens is formed between the divided electrodes G31 and G32. The split electrode G32 and the additional electrode G
The main lens formed by s and the fourth grid G4 has no astigmatism, ie no quadrupole lens action.
Therefore, the electron beam emitted from the cathode K is
The first and second grids G1, G2 and the divided electrode G31 are sequentially formed.
And is focused at the center of the phosphor screen by the main lens formed by the divided electrode G32, the additional electrode Gs, and the fourth grid G4, and a substantially circular beam spot is obtained on the phosphor screen.

On the other hand, when the electron beam is deflected by the deflection yoke, the value of (Vs-Vf) / (Eb-Vf) increases as the electron beam is deflected in the peripheral direction. Since the additional electrode Gs is formed with the horizontally elongated electron beam passage hole 10, it has a horizontal focusing function and a vertical diverging function. Further, the voltage difference between the divided electrode G32 and the fourth grid G4 (Eb-Vf
), The focusing action in the horizontal direction and the diverging action in the vertical direction are simultaneously reduced.

Therefore, even with the above configuration, the same effects as in the first embodiment can be obtained.

[0055]

Embodiment 3 In the electron gun shown in FIG. 11, a quadrupole lens through which an electron beam passes before entering a main lens is formed in a prefocus lens portion.

The electron gun 19 includes three cathodes K arranged in a row in the horizontal direction, three heaters (not shown) for individually heating these cathodes K, and a cathode screen extending from the cathode K to the phosphor screen. , Two divided electrodes G31, G32 of a first grid G1, a second grid G2, a third grid G3, and a fourth grid G4, which are sequentially arranged.
, And the heater, the cathode K, and the five electrodes are integrally fixed by a pair of insulating supports (not shown).

Of the above five electrodes, the divided electrodes G31 of the first and second grids G1, G2 and the third grid G3.
Are composed of plate-like electrodes, in which three electron beam passage holes corresponding to the three cathodes K are formed in a line. The divided electrode G32 of the third grid G3 is a cylindrical electrode, and the fourth grid G4 is a cup-shaped electrode. Three cathodes K are provided at both ends of the divided electrode G32 and on the divided electrode G32 side of the fourth grid G4. Thus, three electron beam passage holes are formed in a line. In particular, in the electron gun 19, the electron beam passage holes of the split electrode G31 are three horizontally long non-circular electron beam passage holes having a horizontal diameter larger than a vertical diameter. On the other hand, the electron beam passage holes on the G31 side of the divided electrode G32 are three vertically long non-circular electron beam passage holes having a vertical diameter larger than a horizontal diameter.

Further, in this electron gun 19, the third
As shown in FIG. 6, between the divided electrode G32 of the grid G3 and the fourth grid G4, corresponding to the three cathodes,
A plate-shaped additional electrode Gs in which three vertically long non-circular electron beam passage holes 10 whose vertical diameter is larger than the horizontal diameter is arranged in a line is arranged.

When the electron gun 19 is configured as described above, the third
By applying a predetermined voltage to each of the divided electrodes G31 and G32 of the grid G3, it is possible to form a prefocus lens having no astigmatism, and the divided electrode G32 increases as the deflection amount of the electron beam increases. By applying a fluctuating voltage on which a parabolic voltage is superimposed, the prefocus lens can have a quadrupole lens function.

Thus, the same effect as that of the first embodiment can be obtained by the configuration described above.

[0061]

According to the above configuration, the elliptical distortion of the beam spot can be reduced without enlarging the beam spot, and a color cathode ray tube device capable of displaying a high-quality image over the entire screen can be configured.

[Brief description of the drawings]

FIG. 1 is an optical model diagram for explaining a basic configuration of an electron gun of a color CRT device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a shape of a beam spot on a phosphor screen of the color CRT device according to the embodiment of the present invention;

3 (a) to 3 (c) show rotationally symmetric B
It is a figure for explaining a quadrupole lens operation of a PF type main lens.

FIG. 4 is a diagram illustrating a configuration of a color CRT device according to the first embodiment of the present invention;

FIG. 5 is a diagram illustrating a configuration of an electron gun of the color cathode ray tube device according to the first embodiment.

FIG. 6 is a diagram showing a shape of an electron beam passage hole of an additional electrode arranged in the electron gun of the first embodiment.

FIG. 7A is a diagram of a fluctuation voltage applied to an additional electrode of the electron gun of the first embodiment in synchronization with a deflection current of a deflection yoke, and FIG. 7B is a diagram of the deflection current. is there.

FIG. 8 is a diagram illustrating a configuration of an electron gun of a color CRT device according to a second embodiment of the present invention;

FIGS. 9A and 9B are diagrams showing different shapes of electron beam passage holes of an additional electrode arranged in the electron gun according to the second embodiment.

FIG. 10A is a diagram of a fluctuation voltage applied to an additional electrode of the electron gun according to the second embodiment in synchronization with a deflection current of a deflection yoke, and FIG. 10B is a diagram of the deflection current. is there.

FIG. 11 is a diagram showing a configuration of an electron gun of a color CRT device according to Embodiment 3 of the present invention.

FIG. 12: BPF type DA of a conventional color CRT device
FIG. 2 is a diagram illustrating a configuration of a C & F type electron gun.

FIG. 13 is a diagram showing the shape of a beam spot on a phosphor screen of a conventional in-line type color CRT device.

FIG. 14 is a diagram showing a shape of a beam spot on a phosphor screen of a color CRT device having the above-mentioned conventional BPF type DAC & F type electron gun.

FIGS. 15A and 15B are optical model diagrams of the conventional BPF type DAC & F type electron gun, respectively.

FIG. 16 is a diagram showing a configuration of a conventional double quadrupole lens type electron gun.

FIG. 17 is an optical model diagram of the conventional double quadrupole lens type electron gun.

FIG. 18 is a view showing a shape of a beam spot on a phosphor screen of a color cathode ray tube device having the above-described double quadrupole lens type electron gun.

[Explanation of symbols]

 4: Main lens 5: Phosphor screen 6a, 6b: Quadrupole lens 11B, 11G, 11R: 3 electron beam 19: Electron gun 21: Deflection yoke Gf: Focus electrode Ga: Anode electrode Gs: Additional electrode

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazunori Sato 1-9-2 Hara-cho, Fukaya-shi, Saitama Pref. Inside the Toshiba Fukaya Electronics Factory (72) Inventor Tsutomu Takekawa 7 Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa 1 F-term in Toshiba Electronic Engineering Corporation (reference) 5C041 AA03 AB07 AC05 AC06 AC07 AC26 AC34 AC35 AD02 AD03 AE01

Claims (4)

[Claims] 1. An electron beam having at least a focus electrode and an anode electrode, wherein an electron beam is accelerated on a phosphor screen.
In a color cathode ray tube device having an electron gun in which a converging main lens is formed, and a deflection yoke for deflecting an electron beam emitted from the electron gun in horizontal and vertical directions, the electron gun is arranged so as to be incident on the main lens. At least one multipole lens through which the electron beam passes, the focusing force of the main lens and the multipole lens changes in synchronization with the deflection of the deflection yoke, and the deflection amount of the deflection yoke increases. The horizontal focusing force of the main lens is relatively strong, the vertical focusing force is relatively weak, and the horizontal focusing force of the multipole lens is relatively increased as the deflection amount of the deflection yoke increases. A color CRT device characterized by a relatively weak focusing power in the vertical direction. 2. At least one additional electrode is disposed between a focus electrode and an anode electrode forming a main lens, wherein the voltage of the focus electrode is Vf, the voltage of the anode electrode is Eb, and the voltage of the additional electrode is 2. The color CRT device according to claim 1, wherein when Vs is Vs, the value of (Vs-Vf) / (Eb-Vf) changes with a change in the deflection amount of the deflection yoke. 3. The color cathode ray tube device according to claim 2, wherein a fluctuating voltage that increases as the amount of deflection of the deflection yoke increases is applied to the focus electrode. 4. The color cathode ray tube device according to claim 1, wherein at least one electrode forming the multipole lens is electrically connected to a focus electrode forming the main lens.