JP2000285823A - Color cathode-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color cathode-ray tube device displaying a favorable quality picture image by reducing elliptical distortions of beam spots at a screen periphery. SOLUTION: In this color cathode-ray tube device, at least one additional electrode Gs is arranged between a focus electrode G3 forming a main lens and an anode electrode G4. Also an electron lens is formed wherein an electrical potential distribution on a center axis of an electron beam through hole of the additional electrode Gs when a deflection yoke is a non-deflection state is practically the same as an electrical potential distribution on a center axis of a main lens when no additional electrode is arranged, and when Vf is a voltage of the focus electrode G3 in a deflection state, Eb is a voltage of the anode electrode G4, and Vs is a voltage of the additional electrode Gs, focusing or diverging functions in horizontal and vertical directions are differentiated by the additional electrode Gs accompanying changes of a value of (Vs-Vf)/(Eb- Vf) in accordance with an increase of a deflection amount.

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 horizontally and vertically scan a phosphor screen provided on the inner surface of the panel through a shadow mask to form a structure for displaying a color image. I have.

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 is widely used due to the pincushion magnetic field and the vertical deflection magnetic field barrel. ing.

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. 14, this electron gun has three cathodes K arranged in a row, and a first grid G 1, a second grid G 2, and a monolithic structure which are sequentially arranged from the cathodes 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 a voltage of about 6 kV is superimposed on the divided electrode G32 at the corner of the phosphor screen according to the deflection of the electron beam. The changed fluctuation voltage 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. A quadrupole lens described later is formed by the divided electrodes G31 and G32 of the third grid G3. The divided electrode G32 of the third grid G3 and the fourth electrode G32
The grid G4 forms a BPF type main lens that finally accelerates and focuses 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. The quadrupole lens 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 line, as shown in FIG. 15A, the beam spot 1 at the center of the screen can be circular, but the horizontal axis (X axis) ) Diagonal axis from end (D
The beam spot 1 at the peripheral portion toward the (axis) end is distorted in an elliptical shape (collapsed horizontally) due to deflection aberration, and a 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 in the peripheral portion from the horizontal axis end to the diagonal axis end of the screen cannot be 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. 16 (a) and 16 (b). In FIGS. 16A and 16B, 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

Therefore, when α0h = α0v, αih = αiv Mh = Mv when there is no deflection shown in FIG. 16A, and the beam spot at the center of the screen is circular. On the other hand, at the time of deflection shown in FIG. 16 (b), αih <αivMh> Mv, and the beam spot in the peripheral portion becomes horizontally long.

[0014]

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.

With respect to the focus characteristics and the beam spot shape, the conventional BPF DAC & F type electron gun has a fluctuation in which the parabolic voltage which is the highest at the corner of the phosphor screen is superimposed on the low voltage side electrode of the main lens. By applying a voltage to vary the intensity of the main lens and forming a dynamically changing quadrupole lens, the beam spot in the vertical direction due to the deflection aberration is eliminated and the entire screen is focused. I have. However, it is not possible to eliminate the elliptical distortion of the beam spot in the peripheral portion from the horizontal axis end to the diagonal axis end of the screen. Therefore, there is a problem that the elliptical distortion interferes with the electron beam passage hole of the shadow mask and causes moire or the like, making it difficult to see characters and the like when displayed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and it is an object of the present invention to provide a color CRT device which displays a high-quality image by reducing elliptic distortion of a beam spot at a peripheral portion of a screen. Aim.

[0017]

(1) An electron gun having at least a focus electrode and an anode electrode and having a main lens for accelerating and focusing an electron beam on a phosphor screen, and emitted from the electron gun. In a color cathode ray tube device having a deflection yoke for generating a deflection magnetic field for deflecting an electron beam, at least one additional electrode is arranged between a focus electrode forming a main lens and an anode electrode, and the deflection yoke is in a non-deflection state. In this case, the potential distribution on the central axis of the electron beam passage hole of the additional electrode is substantially the same as the potential distribution on the central axis of the main lens when the additional electrode is not arranged, and the deflection yoke is in the deflected state. The focus electrode voltage is Vf and the anode electrode voltage is Eb
When the voltage of the additional electrode is Vs, as the value of (Vs-Vf) / (Eb-Vf) changes with an increase in the deflection amount, the additional electrode causes the horizontal and vertical focusing or diverging effects. A different electron lens was formed.

(2) An electron gun having at least a focus electrode and an anode electrode and having a main lens for accelerating and focusing an electron beam on a phosphor screen, and a deflection for deflecting the electron beam emitted from the electron gun. In a color cathode ray tube apparatus having a deflection yoke for generating a magnetic field, at least one additional electrode is arranged between a focus electrode forming a main lens and an anode electrode, and the additional electrode is provided when the deflection yoke is in a deflected state. The potential distribution on the central axis of the electron beam passage hole becomes substantially the same as the potential distribution on the central axis of the main lens when the additional electrode is not arranged, and the voltage of the focus electrode is Vf and the voltage of the anode electrode is Eb. When the voltage of the additional electrode is Vs, the value of (Vs-Vf) / (Eb-Vf) changes as the deflection amount changes. And configured to focusing action or diverging action in the horizontal and vertical directions to form a different electronic lens by pressing the electrode.

(3) In the color cathode ray tube device of (1) or (2), the focusing power in the vertical direction becomes weaker than the focusing power in the horizontal direction of the main lens as the deflection amount increases.

(4) In the color cathode ray tube apparatus according to any one of (1) to (3), the additional electrode is formed in a plate shape, and a non-circular electron beam passage hole having a long axis in a vertical direction is formed in the additional electrode. The value of (Vs-Vf) / (Eb-Vf) changes in synchronization with the change in the deflection magnetic field and decreases as the deflection amount increases.

(5) In the color cathode ray tube device according to any one of (1) to (3), the additional electrode is formed in a plate shape, and a non-circular electron beam passage hole having a long axis in the horizontal direction is formed in the additional electrode. The value of (Vs-Vf) / (Eb-Vf) changes in synchronization with the change in the deflection magnetic field and increases as the deflection amount increases.

[0022]

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

As described above, the conventional BPF type DAC & F
In the system electron gun, a quadrupole lens is arranged in front of the main lens. According to the present invention, a quadrupole lens is formed at the center of an electrode forming the main lens, and a horizontal magnification Mh is obtained.
And a magnification Mv in the vertical direction.

As shown in FIG. 16B, in the conventional electron gun, the magnifications Mh and Mv in the horizontal and vertical directions represented by Mh = α0h / αih Mv = α0v / αiv are set at αih < Since αiv, Mh> Mv. Therefore, in order to alleviate the difference between Mh and Mv, αih may be increased and αiv may be decreased.

Therefore, in the present invention, as shown by the optical model in FIG. 1, a quadrupole lens 6 is formed at the center of the electrode forming the main lens 4. In this case, assuming that the horizontal magnification is Mh 'and the vertical magnification is Mv', Mh '= α0h' / αih 'Mv' = α0v '/ αiv'. Further, since the quadrupole lens 6 approaches the quadrupole lens 7 formed by the deflecting magnetic field, α0h = α0h ′ α0v = α0v ′ αiv <αiv ′ αiv> αiv ′. Therefore, it is possible to satisfy Mh '<MhMv'> Mv, and as shown in FIG. 2, elliptic distortion of the beam spot 1 at the periphery of the screen can be reduced.

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

A general rotationally symmetric BPF type main lens is
As shown by equipotential lines 10 in FIG. 3A, an electric field symmetrical in the horizontal and vertical directions is formed, and the same focusing force is applied to the electron beam 8 in the horizontal and vertical directions. Also, curve (b)
As shown by 1, the focus electrode G forming the main lens
f and the potential on the central axis 12 of the anode electrode Ga increase along the traveling direction of the electron beam 8. In this case, assuming that the focus electrode Gf is 6 kV and the anode electrode Ga is 26 kV, the equipotential surface 13 formed at the geometric center of the main lens is a plane, and the potential on this plane is 16 kV.

Therefore, as shown in FIG. 4A, a vertically long non-circular electron beam passage hole 15 having a vertical diameter larger than a horizontal diameter is provided at the geometric center of the rotationally symmetric BPF type main lens. Are arranged, and a plate-shaped additional electrode Gs having
When a potential of 16 kV is applied to the additional electrode Gs, the potential of the focus electrode Gf forming the main lens and the potential on the central axis 12 of the anode electrode Ga are changed to the potential of the additional electrode Gs as shown by a curve 11 in FIG. It is the same as not placing. That is, in this case, the same electric field 10 as that of the main lens shown in FIG.
Is formed, and the same focusing force is applied to the electron beam 8 both in the horizontal and vertical directions.

However, when the potential of the additional electrode is lowered as shown by the curve 11a in FIG. 5B, as shown in FIG. 5A, the potential of the additional electrode Gs is reduced through the electron beam passage hole 15 of the additional electrode Gs.
An electric potential penetrates from the anode electrode Ga side to the focus electrode Gf side to form an aperture lens. in this case,
Since the electron beam passage hole 15 of the additional electrode Gs 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 has astigmatism.

When the potential of the additional electrode is increased as shown by a curve 11b in FIG. 6B, as shown in FIG. 6A, the focus electrode is passed through the electron beam passage hole 15 of the additional electrode Gs. The potential penetrates from the Gf side to the anode electrode Ga side to form an aperture lens. In this case, since the electron beam passage hole 15 of the additional electrode Gs is vertically long,
Contrary to the case of FIG. 5, the horizontal focusing force is weaker than the vertical focusing force. As a result, the main lens has astigmatism opposite to that in the case of FIG.

That is, a plate-shaped additional electrode Gs is disposed in the main lens based on a BPF lens, and the additional electrode Gs is provided.
By applying a predetermined potential to s, astigmatism for adjusting the horizontal convergence and the vertical convergence can be provided without impairing the aperture of the main lens.

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. However, in general, the voltage of the focus electrode is set to Vf, and the voltage of the anode electrode is set to Vf. Eb, the voltage of the additional electrode is Vs
In this case, 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.

[0034]

[Embodiment 1] FIG. 7 shows the overall configuration of a color CRT device as one embodiment thereof. This color cathode ray tube device has an envelope composed of a panel 17 and a funnel 18 having a funnel shape. On the inner surface of the panel 17, a phosphor screen 5 composed of a three-color phosphor layer emitting blue, green and red light is provided. Is provided. Also, facing the phosphor screen 5,
A shadow mask 19 in which a large number of electron beam passage holes are formed is disposed inside the panel 17. On the other hand, an electron gun 22 that emits three electron beams 8B, 8G, and 8R arranged in a line composed of a center beam 8G and a pair of side beams 8B and 8R passing on the same horizontal plane is disposed in a neck 21 of the funnel 18. I have. In addition, funnel 1
A deflection yoke 25 is mounted from the large diameter portion 24 of FIG. 8 to the outside of the neck 21. The three electron beams 8B, 8G, and 8R emitted from the electron gun 22 are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke 25, and scan the phosphor screen 5 horizontally and vertically via the shadow mask 19. Thereby, it is formed in a structure for displaying a color image.

As shown in FIG. 8, the electron gun 22 has three cathodes K arranged in a row in the horizontal direction, three heaters (not shown) for individually heating these cathodes K, and It has four electrodes consisting of a first grid G1, a second grid G2, a third grid G3, and a fourth grid G4 of an integral structure which are sequentially arranged in the direction of the phosphor screen from the cathode K. The four electrodes are integrally fixed by a pair of insulating supports (not shown).

Of the four 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 third grid G3 is composed of a cylindrical electrode, and has three cathodes K at both ends of the electrode.
, Three electron beam passage holes are formed in a line. The fourth grid G4 is formed of a cup-shaped electrode, and three electron beam passage holes corresponding to the three cathodes K are formed in a line on the third grid G3 side of the electrode.

Further, in the electron gun 23, between the third grid G3 and the fourth grid G4, as shown in FIG. A plate-like additional electrode Gs in which vertically long non-circular electron beam passage holes 15 having a large diameter in a direction are formed in a line is arranged.

In the electron gun 22, 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
As shown in FIGS. 10 (a) and 10 (b), a parabola which is synchronized with the sawtooth-shaped deflection current 27 and becomes higher as the deflection amount increases is supplied to the third grid G3. Fluctuating voltage 28 (V
f) is applied. A voltage (Vs) of about 16 kV is applied to the additional electrode Gs, and about 26 kV is applied to the fourth grid G4.
A voltage (Eb) of V is applied.

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. By the second grid G2 and the third grid G3,
A prefocus lens for prefocusing the electron beam from the triode is formed. The third grid G3 (focus electrode), the additional electrode Gs, and the fourth grid G4 (anode electrode) finally form a BPF type main lens that focuses the electron beam on the phosphor screen.

When the electron beam is not deflected by the deflection yoke, the main lens formed by the third grid G3, the additional electrode Gs and the fourth grid G4 does not have astigmatism, and the main lens formed by the three poles The electron beam is prefocused by a prefocus lens formed by the second grid G2 and the third grid G3, and the third grid G3,
The beam is focused on the center of the phosphor screen by the main lens formed by the additional electrode Gs and the fourth grid G4, and the beam spot on the phosphor screen has a substantially circular shape.

On the other hand, when the electron beam is deflected by the deflection yoke, the voltage of the third grid G3 increases as the electron beam is deflected in the peripheral direction, and the voltage becomes (Vs-Vf) / (Eb-Vf). The value decreases. Further, since the vertically elongated electron beam passage hole 15 is formed in the additional electrode Gs, the horizontal focusing force is stronger than the vertical focusing force. Further, the potential difference between the third grid G3 and the fourth grid G4 is reduced, and the horizontal focusing power and the vertical focusing power are simultaneously reduced. Accordingly, the horizontal focusing force which is increased by the additional electrode Gs, and the third grid G3 and the fourth grid G4
In this configuration, the focusing force in the horizontal direction, which is weakened by the decrease in the potential difference, is canceled out, so that the focusing condition of the electron beam can be satisfied even in the peripheral portion of the screen. Moreover,
When the main lens has astigmatism, as shown in FIG. 2, elliptic distortion of a beam spot at the periphery of the screen can be improved.

When the main lens formed by the third grid, the additional electrode Gs, and the fourth grid is configured as an electron lens in which the horizontal focusing power is stronger than the vertical focusing power, the electron beam is generated. When the deflection is not performed by the deflection yoke, the same effect can be obtained by setting the voltage of the additional electrode low. Further, when the electron beam is deflected by the deflection yoke, a parabolic fluctuating voltage that increases as the deflection amount increases is applied to the third grid, and the value of (Vs−Vf) / (Eb−Vf) is reduced. A similar effect can be obtained by a configuration in which the horizontal focusing force that is increased by the additional electrode and the horizontal focusing force that is weakened by the decrease in the potential difference between the third grid and the fourth grid are canceled out. A color CRT device can be configured.

[0043]

Second Embodiment FIG. 11 shows an electron gun according to a second embodiment. This electron gun 22 has the same configuration as that of the electron gun shown in FIG.
Alternatively, as shown in (b), a horizontally long non-circular electron beam passage hole having a horizontal diameter larger than a vertical diameter.

In this electron gun 22, 150 is applied to the cathode K.
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
As shown in FIGS. 10 (a) and (b), the third grid G3 has a DC voltage of about 6 kV, which is synchronized with the sawtooth-shaped deflection current 27 and increases as the deflection amount increases. Variable voltage 28 with parabolic voltage superimposed
(Vf) is applied. In addition, the additional electrode Gs
As shown in FIGS. 3 (a) and 3 (b), a parabolic voltage synchronized with the sawtooth deflection current 27 and increasing as the deflection amount increases is superimposed on the DC voltage of about 16 kV,
A fluctuation voltage 30 (Vs) having an amplitude substantially equal to the fluctuation voltage of the third grid G3 is applied. A voltage (Eb) of about 26 kV is applied to the fourth grid G4.

Even with such a configuration, the cathode K and the first and second grids G1 and G2 form a triode that generates an electron beam and forms an object point with respect to the main lens described later. Second grid G2 and third grid G
3 forms a prefocus lens for pre-focusing the electron beam from the triode, and the third grid G3,
A BPF that finally focuses the electron beam on the phosphor screen by the additional electrode Gs and the fourth grid G4
The main lens of the mold is formed.

When the electron beam is not deflected by the deflection yoke, the main lens formed by the third grid G3, the additional electrode Gs, and the fourth grid G4 has no astigmatism, and does not have astigmatism. The electron beam is prefocused by a prefocus lens formed by the second grid G2 and the third grid G3, and the third grid G3,
The beam is focused on the center of the phosphor screen by the main lens formed by the additional electrode Gs and the fourth grid G4, and the beam spot on the phosphor screen has a substantially circular shape.

On the other hand, when the electron beam is deflected by the deflection yoke, the voltage of the third grid G3 increases as the electron beam is deflected in the peripheral direction. Further, the voltage of the additional electrode Gs also increases as the voltage is deflected in the peripheral direction. As a result, the value of (Vs-Vf) / (Eb-Vf) increases. Since the laterally elongated electron beam passage hole 15 is formed in the additional electrode Gs, the horizontal focusing force is stronger than the vertical focusing force. Further, the potential difference between the third grid G3 and the fourth grid G4 is reduced, and the horizontal focusing power and the vertical focusing power are simultaneously reduced. Accordingly, the horizontal focusing force which is increased by the additional electrode Gs, and the third grid G3 and the fourth grid G4
In this configuration, the focusing force in the horizontal direction, which becomes weaker due to the decrease in the potential difference, is canceled out, so that the focusing condition of the electron beam is satisfied even at the peripheral portion of the screen. Moreover, since the main lens has astigmatism, the elliptical distortion of the beam spot at the peripheral portion of the screen is improved as shown in FIG.

If the main lens formed by the third grid, the additional electrode Gs, and the fourth grid is configured as an electron lens in which the horizontal focusing power is stronger than the vertical focusing power, the electron beam is When the deflection is not performed by the deflection yoke, the same effect can be obtained by setting the voltage of the additional electrode high. Further, when the electron beam is deflected by the deflection yoke, a parabolic fluctuating voltage that increases as the deflection amount increases is applied to the third grid to increase the value of (Vs-Vf) / (Eb-Vf). A similar effect can be obtained by a configuration in which the horizontal focusing force that is increased by the additional electrode and the horizontal focusing force that is weakened by the decrease in the potential difference between the third grid and the fourth grid are canceled out. A color CRT device can be configured.

[0049]

As described above, at least one additional electrode is arranged between the focus electrode and the anode electrode forming the main lens for finally focusing the electron beam on the phosphor screen. When a configuration is made so as to have dynamically changing astigmatism, the elliptical distortion of the beam spot can be reduced over the entire screen, and a color CRT device that displays a high-quality image 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 for explaining relaxation of elliptical distortion of a beam spot on a phosphor screen of the color CRT device according to the embodiment of the present invention;

3 (a) is a view showing the horizontal and vertical electric fields of a rotationally symmetric BPF type main lens, and FIG. 3 (b) is an axial potential distribution between a focus electrode and an anode electrode. FIG.

FIG. 4A is a diagram showing horizontal and vertical electric fields when an additional electrode is arranged on a rotationally symmetric BPF type main lens, and FIG. 4B is a diagram showing the relationship between the focus electrode and the anode electrode; It is a figure which shows the potential distribution on the axis between.

FIG. 5 (a) is a view showing horizontal and vertical electric fields when an additional electrode is arranged on a rotationally symmetric BPF type main lens and the additional electrode is set to a different potential, and FIG. 5 (b).
FIG. 3 is a diagram showing an axial potential distribution between the focus electrode and the anode electrode.

FIG. 6 (a) is a view showing horizontal and vertical electric fields when an additional electrode is arranged on a rotationally symmetric BPF type main lens and the additional electrode is further set to a different potential.
(B) is a diagram showing an axial potential distribution between the focus electrode and the anode electrode.

FIG. 7 is a diagram illustrating a configuration of a color CRT device according to the first embodiment of the present invention;

FIG. 8 is a diagram showing a configuration of an electron gun of the color cathode ray tube device of the first embodiment.

FIG. 9 is a view showing a shape of an electron beam passage hole of an additional electrode arranged in the electron gun of the first embodiment.

FIG. 10A 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. 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 a second embodiment of the present invention.

FIGS. 12 (a) and 12 (b) are diagrams showing different shapes of electron beam passage holes of an additional electrode arranged in the electron gun of the second embodiment.

FIG. 13 (a) is a diagram of a fluctuation voltage applied to an additional electrode of the electron gun of the second embodiment in synchronization with a deflection current of a deflection yoke, and FIG. 13 (b) is a diagram of the deflection current. is there.

FIG. 14: 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. 15 (a) is a diagram showing a shape of a beam spot on a phosphor screen of a conventional in-line type color CRT device, and FIG. 15 (b) is a BPF type DAC & F.
FIG. 4 is a view showing a shape of a beam spot on a phosphor screen of a color CRT device having a system electron gun.

FIGS. 16 (a) and 16 (b) are optical model diagrams for explaining elliptical distortion of a beam spot on a phosphor screen of the conventional in-line type color CRT device.

[Explanation of symbols]

 4 Main lens 5 Phosphor screen 8B, 8R Pair of side beams 8G Center beam 15 Electron beam passage hole 22 Electron gun 25 Deflection yoke G3 Third grid G4 Fourth grid 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 Inside the Toshiba Fukaya Plant (72) Inventor Tsutomu Takekawa 7-1, Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa-ken F-term (reference) in Toshiba Electronic Engineering Corporation 5C041 AA03 AA14 AB07 AC06 AC07 AC26 AC35 AC38 AC42 AD04 AE01

Claims (5)

[Claims] 1. An electron gun having at least a focus electrode and an anode electrode and having a main lens for accelerating and focusing an electron beam on a phosphor screen, and a deflecting magnetic field for deflecting the electron beam emitted from the electron gun. A color cathode ray tube device comprising: a deflection yoke for generating the main lens; at least one additional electrode is arranged between a focus electrode forming the main lens and an anode electrode; and the additional electrode is provided when the deflection yoke is in a non-deflection state. The potential distribution on the central axis of the electron beam passage hole of the electrode is substantially the same as the potential distribution on the central axis of the main lens when the additional electrode is not disposed, and the focus is applied when the deflection yoke is in the deflected state. When the voltage of the electrode is Vf, the voltage of the anode electrode is Eb, and the voltage of the additional electrode is Vs, (Vs-Vf) / (Eb-Vf) Color cathode ray tube apparatus values, characterized in that the focusing action or diverging action in the horizontal and vertical directions to form a different electronic lens by the additional electrode with the changes with increasing deflection. 2. An electron gun having at least a focus electrode and an anode electrode and having a main lens for accelerating and focusing an electron beam on a phosphor screen, and a deflecting magnetic field for deflecting the electron beam emitted from the electron gun. And a deflection yoke for generating a color image, wherein at least one additional electrode is disposed between a focus electrode and an anode electrode forming the main lens, and the additional yoke is provided when the deflection yoke is in a deflected state. The potential distribution on the central axis of the electron beam passage hole of the electrode is substantially the same as the potential distribution on the central axis of the main lens when the additional electrode is not disposed, the voltage of the focus electrode is Vf, and the voltage of the anode electrode is Is the voltage of Eb, and the voltage of the additional electrode is Vs
When the value of (Vs-Vf) / (Eb-Vf) changes according to the change in the amount of deflection, the additional electrode forms an electron lens having different horizontal and vertical focusing or diverging functions. A color CRT device characterized by that: 3. The color CRT device according to claim 1, wherein the focusing power in the vertical direction becomes weaker than the focusing power in the horizontal direction of the main lens as the amount of deflection increases. 4. An additional electrode is formed in a plate shape, a non-circular electron beam passage hole having a long axis in a vertical direction is formed in the additional electrode, and the value of (Vs-Vf) / (Eb-Vf) is deflected. 4. The color CRT device according to claim 1, wherein the color CRT device changes in synchronization with a change in the magnetic field and decreases as the deflection amount increases. 5. An additional electrode is formed in a plate shape, a non-circular electron beam passage hole having a long axis in the horizontal direction is formed in the additional electrode, and the value of (Vs-Vf) / (Eb-Vf) is deflected. 4. The color cathode ray tube device according to claim 1, wherein the color CRT device changes in synchronization with a change in the magnetic field and increases as the deflection amount increases.