JP2003016964A - Cathode-ray tube device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode-ray tube device capable of forming beam spots of uniform shape on the whole surface of a phosphor screen by reducing the horizontal diameter of the beam spot at the peripheral part of the phosphor screen. SOLUTION: An electron beam structure 7 is provided with an auxiliary lens for pre-focusing electron beams, and a main lens for focusing the electron beams on the phosphor screen. The main lens is formed of a second segment G5-2, a first addition electrode GM1, a second addition electrode GM2 and a sixth grid G6 arranged in order along the proceeding direction of the electron beams. The electron gun structure 7 is provided with a means for enlarging the lens bore of the main lens with the increase of deflection amount of the electron beams, and a means for lowering the focusing force of the auxiliary lens formed of a third grid G3, a fourth grid and a first segment G5-1, with the increase of the deflection amount of the electron beams.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube device, and more particularly to a color cathode ray tube which is adapted to improve the elliptic distortion of a beam spot shape in the peripheral portion of a phosphor screen and stably supply a good image quality. Regarding the device.

[0002]

2. Description of the Related Art The mainstream self-convergence in-line type color cathode ray tube apparatus at present is an in-line type electron gun assembly that emits three electron beams arranged in a row passing through the same horizontal plane, and an electron beam emitted from this electron gun assembly. And a deflection yoke that generates an inhomogeneous deflection magnetic field that deflects. This deflection magnetic field is formed by a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field. As the deflection amount of the electron beam increases, the deflection magnetic field converges the electron beam in the vertical direction and diverges in the horizontal direction, so that the action as a quadrupole lens equivalently increases.

Further, the distance from the electron gun assembly to the phosphor screen becomes longer as the electron beam is deflected from the central part to the peripheral part of the phosphor screen. Due to this distance difference, when the electron beam is focused on the central portion of the phosphor screen, the electron beam is defocused on the peripheral portion of the phosphor screen.

Therefore, the beam spot in the peripheral portion of the phosphor screen becomes an optimal focus in the horizontal direction, although the diverging action of the deflection magnetic field and the defocus due to the distance difference described above cancel each other out in the horizontal direction. Due to the focusing effect due to and the defocus due to the distance difference, an overfocus state is achieved. Therefore, as shown in FIG. 8, the beam spot formed on the phosphor screen is almost a perfect circle in the central portion, whereas the beam spot formed in the peripheral portion is long in the horizontal direction and long in the horizontal direction in the peripheral portion. With a core) 50c and a low-luminance portion (halo) 50h extending in the vertical direction.
As a result, the resolution in the peripheral portion of the phosphor screen is greatly deteriorated.

In order to solve this problem, Japanese Patent Laid-Open No. 61-
In Japanese Patent Publication No. 99249, DAF (Dy as shown in FIG.
natural Astigmatism and Foc
A us) type electron gun assembly is disclosed. The feature of this electron gun assembly is that the third grid, which is the focus electrode, is composed of the first segment G3-1 and the second segment G3-2, and the second segment G3 of the first segment G3-1.
The electron beam passage hole shape on the −2 side is made vertically long as shown in FIG. 10A, and the electron beam passage hole shape on the first segment G3-1 side of the second segment G3-2 is shown in FIG. 10B. Horizontally as shown in. Further, the second segment G3-2 has a structure in which a dynamic voltage in which an alternating-current component that changes in a parabolic shape in accordance with a change in the deflection amount of the electron beam is superimposed is supplied.

As a result, as the electron beam is deflected, a potential difference is generated between the first segment and the second segment. This potential difference forms a quadrupole lens between the first and second segments that focuses the electron beam horizontally and diverges vertically. This quadrupole lens compensates the deflection aberration caused by the deflection of the electron beam. Further, since the dynamic voltage is supplied to the second segment, the focusing action of the main lens becomes weaker as the deflection amount of the electron beam increases. Therefore, the defocus caused by the above-mentioned distance difference is also corrected at the same time.

However, this electron gun assembly has a problem that the horizontal diameter of the beam spot in the peripheral portion of the phosphor screen becomes significantly larger than that in the central portion of the phosphor screen. The following two points can be cited as the cause of this.

(1) As the electron beam is deflected from the central portion of the phosphor screen toward the peripheral portion, the magnification of the entire lens system deteriorates due to the increase in the distance from the electron gun assembly to the phosphor screen.

(2) Deterioration of the horizontal magnification of the lens system by operating the quadrupole lens.

A phenomenon in which the horizontal diameter of the beam spot significantly expands will be described.

First, the phenomenon in which the beam spot diameter increases due to the above-mentioned cause (1) will be described.

In order to simplify the model, (a) of FIG.
And (b), except for the quadrupole lens component formed by the deflection magnetic field and the quadrupole lens formed in the electron gun assembly,
Only the distance from the electron gun structure to the phosphor screen and the strength of the main lens will be described.

The size of the beam spot on the phosphor screen depends on the magnification M represented by the ratio of the divergence angle αo from the electron beam generator in the electron gun assembly to the incident angle αi on the phosphor screen. . That is, the magnification M
Is represented by M = (divergence angle αo / incident angle αi).

As shown in FIG. 11A, when the electron beam is focused on the center of the phosphor screen, the object point O
The electron beam emitted from the horizontal direction X and the vertical direction Y at a divergence angle αo is focused by the main lens 20 and is incident on the phosphor screen in the horizontal direction X and the vertical direction Y.
It is incident at (1). If the magnification at this time is M (1), M (1) is expressed by M (1) = αo / αi (1).

As shown in FIG. 11B, when the electron beam is deflected to the peripheral portion of the phosphor screen, the distance from the electron gun assembly to the phosphor screen becomes long. The electron beam emitted from the object point O in the horizontal direction X and the vertical direction Y at a divergence angle αo is focused by the main lens. In the electron gun assembly disclosed in Japanese Patent Laid-Open No. 61-99249, the focal length is extended by weakening the focusing power of the main lens. The electron beam focused by the main lens is projected on the phosphor screen in the horizontal direction X and the vertical direction Y.
At an incident angle αi (2). The magnification in this case is M
Assuming (2), M (2) is expressed by M (2) = αo / αi (2). Since the distance from the object point O to the main lens is constant, αi (2) becomes smaller as the distance (focal length) from the main lens to the phosphor screen becomes longer.

Therefore, since αi (1)> αi (2), M (1) <M (2).

That is, when the focal length is changed by the strength of the main lens, the magnification M increases as the focal length increases, and the spot diameter formed on the phosphor screen increases. Therefore, in the electron gun assembly disclosed in Japanese Patent Laid-Open No. 61-99249, the average spot diameter of the beam spot formed in the peripheral portion of the phosphor screen is larger than the average spot diameter formed in the central portion.

Next, the phenomenon in which the electron beam is distorted in the lateral direction due to the above-mentioned cause (2) will be described using an optical lens model in the same manner. The horizontal magnification of the electron beam is Mx,
The vertical magnification is My. Mx and My are respectively Mx (horizontal magnification) = αox (horizontal divergence angle) / αix
(Horizontal incident angle) My (vertical magnification) = αoy (vertical divergence angle) / αiy
(Vertical incident angle).

In the non-deflected state, as shown in FIG. 11A, the electron beam emitted from the object point O at the divergence angle αo in the horizontal direction X and the vertical direction Y has no astigmatism. The light is focused by the lens 20 and is incident on the phosphor screen in the horizontal direction X and the vertical direction Y at an incident angle αi (1). In this case, the horizontal magnification Mx is equal to the vertical magnification My, and a perfect circular beam spot is formed.

At the time of deflection, as shown in FIG. 11C, a quadrupole lens component 30 due to the deflection magnetic field and a quadrupole lens 21 for correcting this are newly formed. This allows the object point O to diverge in the horizontal direction x and the vertical direction y.
The electron beam emitted at o is made incident on the phosphor screen in the horizontal direction X by the quadrupole lens 21, the main lens 20, and the quadrupole lens component 30 by the deflection magnetic field.
(3), incident in the vertical direction Y at an incident angle αiy (3).
In this case, the horizontal magnification Mx (3) and the vertical magnification My (3) are expressed by Mx (3) = αo / αix (3) My (3) = αo / αiy (3), respectively. . At this time, as is apparent from FIG. 11C, αix (3) <αiy (3). Therefore,
The relationship between the horizontal magnification Mx (3) and the vertical magnification My (3) is Mx (3)> My (3). That is, the beam spot formed in the peripheral portion of the phosphor screen becomes horizontally long. As a result, the incident angle αix on the phosphor screen in the horizontal and vertical directions is
(3) and αiy (3) are compared with the incident angle αi (2) of the electron beam on the phosphor screen shown in FIG. 11B, αix (3) <αi (2) <αiy (3 ). Therefore, Mx (3)> M (2)> M (1), that is, Mx (3) >> M (1). Therefore, the horizontal diameter of the beam spot around the phosphor screen is as shown in FIG.
The diameter of the beam spot in the central portion of the phosphor screen is significantly enlarged as compared with the horizontal diameter.

[0021]

As described above, in order to improve the image quality of the cathode ray tube device, it is necessary to make the shape of the beam spot uniform over the entire surface of the phosphor screen. Therefore, it is required to simultaneously compensate the defocus caused by the increase in the distance between the electron gun structure and the phosphor screen and the astigmatism due to the deflection magnetic field as the deflection amount of the electron beam increases.

In the conventional electron gun structure represented by Japanese Patent Laid-Open No. 61-99249, by applying an appropriate parabolic dynamic voltage to the low-voltage side electrode of the main lens,
Defocus is corrected by changing the main lens strength, and at the same time, astigmatism due to the deflection magnetic field is corrected by forming a dynamically changing quadrupole lens.

However, if the beam spot in the central portion of the phosphor screen is formed into a substantially perfect circle, the shape of the beam spot in the peripheral portion of the phosphor screen will be significantly crushed and the average diameter will be large.

The phenomenon that the beam spot in the peripheral portion of the phosphor screen is crushed laterally is caused by the astigmatism of the deflection magnetic field.
This occurs because the difference between the horizontal lens magnification Mx and the vertical lens magnification My is increased by compensating with the quadrupole lens located on the cathode side of the main lens.

Further, since the defocus that occurs as the electron beam is deflected to the peripheral portion of the phosphor screen is compensated by changing the strength of the main lens, the magnification at the peripheral portion of the phosphor screen is increased. Will be larger than Therefore, the average diameter of the beam spot around the phosphor screen is increased.

The present invention has been made in view of the above-mentioned problems, and an object thereof is to reduce the horizontal diameter of the beam spot in the peripheral portion of the phosphor screen so that a uniform shape is formed on the entire surface of the phosphor screen. It is to provide a cathode ray tube device capable of forming a beam spot.

[0027]

In order to solve the above-mentioned problems and to achieve the object, a first aspect of the present invention provides an electron beam generator for generating an electron beam and an electron beam generated by the electron beam generator. An electron gun assembly having at least one auxiliary lens for focusing and a main lens for focusing the electron beam prefocused by the auxiliary lens on a phosphor screen, and an electron beam emitted from the electron gun assembly. In a cathode ray tube device including a deflection yoke that generates a deflection magnetic field that deflects in a horizontal direction and a vertical direction, the electron gun structure is sequentially arranged along a traveling direction of an electron beam that constitutes the main lens. A focus electrode, at least two additional electrodes, and an anode electrode,
A constant focus voltage is always applied to the focus electrode, an anode voltage which is always constant and higher than the focus voltage is applied to the anode electrode, and the focus voltage is applied to the first additional electrode arranged on the focus electrode side. A parabolic dynamic voltage that is higher than the anode voltage and that decreases with an increase in the deflection amount of the electron beam is applied, and the second additional electrode arranged on the anode electrode side is always higher than the dynamic voltage. When the electron beam is focused on the central portion of the phosphor screen without deflection, a voltage substantially equal to the anode voltage is applied, and the deflection amount of the electron beam during deflection is deflected to deflect the electron beam toward the peripheral portion of the phosphor screen. A voltage that decreases with an increase is applied, and at least one auxiliary lens is used to deflect the electron beam. It is characterized in that the focusing power decreases as the amount increases.

According to the cathode ray tube device of the present invention, the electron lens is not formed between the second additional electrode and the anode electrode because the potentials of the second additional electrode and the anode electrode are substantially the same when there is no deflection. Therefore, the main lens is formed by the focus electrode, the first additional electrode, and the second additional electrode. The electron beam generated from the electron beam generator is focused on the central portion of the phosphor screen by the main lens and the auxiliary lens.

At the time of deflection, the intensity of the auxiliary lens is weakened as the deflection amount of the electron beam increases, and defocus due to the increase in the distance from the electron gun structure to the phosphor screen is compensated, so that the lens magnification deteriorates. Can be suppressed.

However, when the strength of the auxiliary lens is weakened, the diameter of the electron beam incident on the main lens is enlarged, and the beam spot cannot be sufficiently reduced due to the spherical aberration of the main lens.

Therefore, in the cathode ray tube device according to the present invention, a parabolic dynamic voltage whose potential decreases is applied to the first additional electrode, and the second additional electrode receives the parabola via the capacitance with the first additional electrode. Voltage is induced to reduce the voltage of the second additional electrode. Thereby, a potential difference is generated between the second additional electrode and the anode electrode, and an electron lens is formed. Therefore, the main lens is formed by the focus electrode, the first additional electrode, the second additional electrode, and the anode electrode by enlarging the lens region along the tube axis direction as compared to when there is no deflection.

Enlarging the lens area substantially corresponds to enlarging the lens aperture. By enlarging the diameter of the main lens, the influence of the spherical aberration of the main lens can be reduced, and the beam spot diameter at the peripheral portion of the phosphor screen can be sufficiently reduced.

Therefore, by suppressing the deterioration of the lens magnification that occurs as the electron beam is deflected to the peripheral portion of the phosphor screen and further improving the lens aberration, the horizontal diameter of the beam spot in the peripheral portion of the phosphor screen is reduced. However, a good beam spot can be formed on the entire phosphor screen.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the cathode ray tube device of the present invention will be described below with reference to the drawings.

As shown in FIG. 3, an in-line type color cathode ray tube device as an example of the cathode ray tube device of the present invention comprises:
It has an envelope including a panel 1 and a funnel 2 integrally joined to the panel 1. The panel 1 has a phosphor screen 3 on its inner surface, which is composed of three-color phosphor layers arranged in a dot shape or a stripe shape that emits blue, green, and red.
Is equipped with. The shadow mask 4 has a large number of electron beam passage holes inside and is arranged so as to face the phosphor screen 3.

The in-line type electron gun assembly 7 is arranged inside the neck 5 corresponding to the small diameter portion of the funnel 2.
The electron gun assembly 7 emits three electron beams 6B, 6G, 6R arranged in a row, which includes a center beam 6G passing through the same horizontal plane and a pair of side beams 6B, 6R.

The deflection yoke 8 is attached from the large diameter portion of the funnel 2 to the neck 5. This deflection yoke 8
Are three electron beams 6B, 6 emitted from the electron gun assembly 7.
An inhomogeneous deflection magnetic field for deflecting G and 6R in the horizontal direction (X) and the vertical direction (Y) is generated. This non-uniform magnetic field is formed by a pincushion type horizontal deflection magnetic field and a barrel type vertical deflection magnetic field.

The three electron beams 6B, 6G and 6R emitted from the electron gun assembly 7 are deflected by the non-uniform magnetic field generated by the deflection yoke 8, and the phosphor screen 3 is passed through the shadow mask 4 in the horizontal and vertical directions. To scan. As a result, a color image is displayed.

As shown in FIG. 1, the electron gun assembly 7 has three cathodes K arranged in a line in the horizontal direction (X) and three heaters (not shown) for individually heating the cathodes K. , And 9 electrodes. Nine electrodes, namely, the first grid G1, the second grid G2, the third grid G3, the fourth grid G4, the first segment G5-1 of the fifth grid G5, and the second segment G5-2 of the fifth grid G5 ( The focus electrode), the first additional electrode GM1, the second additional electrode GM2, and the sixth grid G6 (anode electrode) are sequentially arranged from the cathode K in the phosphor screen direction. The heater, the cathode K, and the plurality of electrodes are integrally fixed by a pair of insulating supports (not shown).

First grid G1 and second grid G2
Are each composed of a plate-shaped electrode having an integral structure. These plate-like electrodes have three substantially circular electron beam passage holes formed in a row in the horizontal direction corresponding to the three cathodes K. The third grid G3 and the fourth grid G4 are composed of tubular electrodes having an integral structure. These cylindrical electrodes have three substantially circular electron beam passage holes formed in a row in the horizontal direction corresponding to the three cathodes K at both ends thereof.

The first segment G5- of the fifth grid G5
1 is composed of a cylindrical electrode having an integral structure. This cylindrical electrode has 3 end faces facing the fourth grid G4.
It has three substantially circular electron beam passage holes formed in a line in the horizontal direction corresponding to each cathode K. Also,
This cylindrical electrode is used for the second segment G of the fifth grid G5.
On the end surface facing 5-2, as shown in FIG.
It has three non-circular electron beam passage holes formed in a line in the horizontal direction corresponding to the three cathodes K. These three non-circular electron beam passage holes are formed in a vertically long shape having a long axis in the vertical direction Y.

Second segment G5- of the fifth grid G5
2 is composed of a cylindrical electrode having an integral structure. This cylindrical electrode is the first segment G5 of the fifth grid G5.
The end surface facing -1 has three non-circular electron beam passage holes formed in a line in the horizontal direction corresponding to the three cathodes K. These three non-circular electron beam passage holes are formed in a horizontally long shape having a major axis in the horizontal direction X. In addition, the cylindrical electrode has three substantially circular electron beam passage holes formed in a line in the horizontal direction corresponding to the three cathodes K on the end surface facing the first additional electrode GM1. There is.

First additional electrode GM1 and second additional electrode GM
Each of the electrodes 2 is composed of a plate-shaped electrode having an integral structure. These plate-like electrodes have three substantially circular electron beam passage holes formed in a row in the horizontal direction corresponding to the three cathodes K. The sixth grid G6 is composed of an integrally structured tubular electrode. These cylindrical electrodes have three substantially circular electron beam passage holes formed in a row in the horizontal direction corresponding to the three cathodes K at both ends thereof.

In the electron gun assembly 7 having such a structure,
A voltage in which a video signal is superimposed on a DC voltage of about 150 to 200 V is applied to the cathode K. First grid G
1 is grounded. About 60 in the second grid G2
A DC voltage of 0 to 1000 V is applied.

The third grid G3 is electrically connected to the second segment G5-2 of the fifth grid G5 in the tube and has a relatively medium voltage, for example, about 4 to 8 kV regardless of the deflection amount of the electron beam. Then, a fixed voltage (focus voltage) Vf1 is applied.

A relatively high voltage, for example, a constant anode voltage (anode voltage) Eb at about 25 to 35 kV is applied to the sixth grid G6 regardless of the amount of deflection of the electron beam.

The fourth grid G4 is electrically connected to the first additional electrode GM1 in the tube, and a voltage higher than the focus voltage Vf1 and lower than the anode voltage Eb is applied thereto. That is, these grids have a voltage higher than the focus voltage Vf1, for example, a DC voltage Vf of about 8 to 12 kV.
A dynamic voltage in which an AC voltage component Vd that changes in a parabolic shape is superimposed is applied to 2. This AC voltage component V
d is synchronized with the sawtooth-shaped deflection current supplied to the deflection yoke 8 and decreases in a parabolic shape as the deflection amount of the electron beam increases.

Therefore, the voltage of the level corresponding to the potential Vf2 is applied to the fourth grid G4 and the first additional electrode GM1 when the electron beam is focused on the central portion of the phosphor screen 3 without deflection, and the electron beam As the deflection amount increases, a voltage lower than Vf2 is applied. In addition,
The dynamic voltage (Vf2 + Vd) is set to be higher than the focus voltage Vf1 even at the lowest potential.

The first segment G5- of the fifth grid G5
1 is a voltage divider resistor 1 arranged along the electron gun structure 7.
Anode voltage Eb applied to the sixth grid G6 by 01
A voltage substantially equal to the focus voltage Vf1 applied to the second segment G5-2, which is obtained by dividing the voltage, is applied. That is, the voltage applied to the first segment G5-1 is substantially equal to the focus voltage Vf1 in the non-deflected state, and the parabolic alternating current induced through the capacitance with the fourth grid G4 in the deflected state. The components are superimposed. The parabolic AC component decreases in a parabolic shape as the deflection amount of the electron beam increases.

The second additional electrode GM2 is applied to the sixth grid G6 obtained by dividing the anode voltage Eb applied to the sixth grid G6 by the voltage dividing resistor 101 arranged along the electron gun structure 7. A voltage substantially equal to the anode voltage Eb is applied. That is, the voltage applied to the second additional electrode GM2 is substantially equal to the anode voltage Eb in the non-deflected state, and the parabolic alternating current induced through the capacitance with the first additional electrode GM1 in the deflected state. The components are superimposed. The parabolic AC component decreases in a parabolic shape as the deflection amount of the electron beam increases.

The relationship between the voltages applied to the third grid G3 to the sixth grid G6 and the sawtooth-shaped deflection current supplied to the deflection yoke 8 is as shown in FIG. That is, the anode voltage Eb applied to the sixth grid G6 is the highest. Further, the voltage applied to the second additional electrode GM2 is substantially equal to the anode voltage Eb when there is no deflection, and decreases with an increase in the deflection amount of the electron beam.
It does not fall below the DC voltage Vf2.

Fourth grid G4 and first additional electrode GM1
The dynamic voltage (Vf2 + Vd) applied to the reference voltage is at the same level as Vf2 when there is no deflection, and decreases as the deflection amount of the electron beam increases.
Never falls below.

Third grid G3 and second segment G5
The focus voltage Vf1 applied to −2 is always constant regardless of the deflection amount of the electron beam. The voltage applied to the first segment G5-1 is substantially equal to the focus voltage Vf1 when there is no deflection, and decreases as the deflection amount of the electron beam increases.

The electron gun assembly 7 forms the electron beam generator, the prefocus lens, the auxiliary lens, the quadrupole lens, and the main lens by applying the voltage as described above to each grid.

The electron beam generator is formed by the cathode K, the first grid G1 and the second grid G2. The electron beam generator generates an electron beam and forms an object point for the main lens. The prefocus lens is formed by the second grid G2 and the third grid G3. The prefocus lens prefocuses the electron beam generated by the electron beam generator.

The auxiliary lens is formed by the third grid G3 (first electrode), the fourth grid G4 (second electrode), and the first segment G5-1 (third electrode) of the fifth grid G5. The auxiliary lens further prefocuses the electron beam prefocused by the prefocus lens.

In the non-deflected state, the auxiliary lens is formed by a relatively large potential difference between the third grid G3 and the fourth grid G4. Further, during the deflection, the auxiliary lens is formed by a relatively small potential difference between the third grid G3 and the fourth grid G4. Therefore, the lens strength of the auxiliary lens becomes weaker when deflected than when not deflected.

The quadrupole lens is the first of the fifth grid G5.
It is formed by the segment G5-1 and the second segment G5-2. This quadrupole lens has a quadrupole lens component (having a diverging action in the horizontal direction X, which is included in the deflection magnetic field,
It is formed only at the time of deflection in order to compensate astigmatism due to (having a focusing action in the vertical direction Y), and has a focusing action in the horizontal direction X and a diverging action in the vertical direction Y.

The main lens is composed of the second segment G5-2 (focus electrode) of the fifth grid G5 and the first additional electrode G.
M, the second additional electrode GM2, and the sixth grid G6 (anode electrode). This main lens ultimately focuses the electron beam on the phosphor screen.

At the time of non-deflection, the second additional electrode GM2 is
Since a voltage substantially equal to the anode voltage Eb applied to the sixth grid G6 is applied, the main lens includes the second segment G5-2, the first additional electrode GM1, and the second additional electrode along the tube axis direction Z. It is formed by the electrode GM2. Further, at the time of deflection, a voltage lower than the anode voltage Eb is applied to the second additional electrode GM2, so that the main lens has the second segment G5-2, the first additional electrode GM1, and the first additional electrode GM1 along the tube axis direction Z. Two
It is formed by the additional electrode GM2 and the sixth grid G6. Since the main lens formed during the deflection is formed over a region having a longer interval along the tube axis direction Z as compared with the case where there is no deflection, it is possible to substantially enlarge the lens aperture.

Next, the effect of the electron gun assembly having the above structure will be described.

First, the lens action when there is no deflection will be described using an optical model.

That is, as shown in FIG. 5A, the auxiliary lens 22 is formed in front of the main lens 20. The electron beam emitted from the object point O at the divergence angle αo in both the horizontal direction X and the vertical direction Y is prefocused by the auxiliary lens 22 and further focused by the main lens 20. This electron beam enters the phosphor screen 3 at an incident angle αi (5) in both the horizontal direction X and the vertical direction Y. If the magnification at this time is M (5), then M (5) = αo / αi (5). In this case, since the horizontal direction X and the vertical direction Y are symmetric, the beam spot diameter of the electron beam focused on the central portion of the phosphor screen 3 is almost a perfect circle, with the horizontal diameter and the vertical diameter being equal. .

Next, the defocus compensation when the distance between the electron gun structure and the phosphor screen during deflection is enlarged will be described. Here, for simplification of description, the quadrupole lens in the electron gun assembly 7 and the quadrupole lens component included in the deflection magnetic field are omitted.

This defocus compensation will be described with reference to the optical model shown in FIG. In FIG. 5B, the distance between the electron gun assembly and the phosphor screen is expanded as compared with FIG. In this electron gun assembly 7, defocus compensation is performed by increasing the distance between the electron gun assembly and the phosphor screen by changing the lens strength of the auxiliary lens 22 arranged on the cathode side of the main lens 20.

That is, at the time of deflection, the fourth grid G4
Is applied with a parabolic dynamic voltage (Vf2 + Vd) that decreases with an increase in the deflection amount of the electron beam. Therefore, the voltage difference between the fourth grid G4 and the third grid G3 decreases as the deflection amount of the electron beam increases.

Further, in the first segment G5-1, the fourth segment
The parabolic AC component induced via the capacitance with the grid G4 is superimposed, but the induced parabolic voltage is smaller than the dynamic voltage (Vf2 + Vd) applied to the fourth grid G4. Therefore, the voltage difference between the fourth grid G4 and the first segment G5-1 decreases as the deflection amount of the electron beam increases.

As described above, the lens strength of the auxiliary lens 22 decreases as the deflection amount of the electron beam increases.

In this case, the electron beam emitted from the object point O at the divergence angle αo in both the horizontal direction X and the vertical direction Y is prefocused by the auxiliary lens 22.
Has a weaker lens strength than that in the non-deflected state shown in FIG. Therefore, the diameter of the electron beam incident on the main lens 20 is larger than that shown in FIG. Since the lens strength of the main lens 20 is substantially the same as that when there is no deflection,
When the distance between the electron gun structure and the phosphor screen is increased,
The electron beam is incident on the phosphor screen 3 in both the horizontal direction X and the vertical direction Y at an incident angle αi (6). Therefore, the magnification M (6) is M (6) = αo / αi (6). The incident angle αi (6) of the electron beam incident on the phosphor screen 3 changes depending on the lens strength of the auxiliary lens 22, and by weakening the lens strength, the undeflected phosphor shown in FIG. The angle of incidence αi (5) on the screen 3 can be made substantially equivalent, that is, αi (6) ≈αi (5). Therefore, the magnification M during deflection
(6) can be made substantially equal to the magnification M (5) when there is no deflection. Alternatively, it is possible to make αi (6)> αi (5) by weakening the lens strength of the auxiliary lens 22.

Therefore, the deterioration of the lens magnification due to the enlargement of the distance between the electron gun structure and the phosphor screen can be almost eliminated.

However, enlarging the diameter of the electron beam incident on the main lens 20 makes the spherical aberration of the main lens more susceptible, and the lens is enlarged by increasing the distance between the electron gun structure and the phosphor screen. Even if the deterioration of magnification is suppressed, the beam spot diameter cannot be sufficiently reduced due to the influence of lens aberration.

Therefore, in the electron gun assembly 7, the substantial lens aperture of the main lens 20 is enlarged as the deflection amount of the electron beam is increased.

This method will be specifically described with reference to FIG.

That is, the second segment G5-2 forming the main lens in the non-deflected state, the first additional electrode GM1,
As described above, the relationship between the voltages of the second additional electrode GM2 and the sixth grid G6 is the second segment applied voltage Vf1.
<First additional electrode applied voltage Vf2 <Second additional electrode applied voltage = sixth grid applied voltage Eb. Therefore, in the non-deflected state, the main lens is substantially the second segment G.
5-2, first additional electrode GM1, and second additional electrode GM2
Is formed by. The axial potential distribution of the main lens at this time is as shown by A in the figure, and the main lens is
It is formed from a point S in the segment G5-2 to a point E in the second additional electrode GM2 through a point C in the first additional electrode GM1.

On the other hand, the deflection amount of the electron beam increases and the first
When the dynamic voltage (Vf2 + Vd) is applied to the additional electrode GM1, the potential of the first additional electrode GM1 decreases from the point C to the point D, and the voltage becomes Vf2 → Vf2 ′.

Further, since a voltage is supplied to the second additional electrode GM2 via the voltage dividing resistor 101, a parabolic AC voltage is applied via the capacitance with the first additional electrode GM1. It Therefore, the potential of the second additional electrode GM2 decreases from the point E to the point F, and the voltage becomes Eb → Vf3.

The anode voltage applied to the sixth grid G6 is fixed at Eb, and the focus voltage applied to the second segment G5-2 is also fixed at Vf1. Therefore, the axial potential distribution of the main lens at the time of deflection is as shown by B in the figure. As shown in the on-axis potential distribution B, the main lens has a point S in the second segment G5-2, a point D in the first additional electrode GM1, and a point F in the second additional electrode GM2.
Through a point T in the sixth grid G6.

That is, the area forming the main lens is enlarged along the tube axis direction Z. The enlargement of the formation area of the main lens substantially corresponds to the enlargement of the lens aperture of the main lens. Therefore, the diameter of the main lens can be increased with an increase in the deflection amount of the electron beam.

From the above, as shown in FIG.
The lens aperture of the main lens 20 at the time of deflection is enlarged, and the spherical aberration of the main lens 20 can be suppressed.

When the electron beam is deflected to the peripheral portion of the phosphor screen, it is actually affected by astigmatism due to the quadrupole lens component contained in the deflection magnetic field. The above electron gun structure also includes a quadrupole lens arranged between the auxiliary lens 22 and the main lens 20 in order to compensate for this astigmatism.

FIG. 5C shows an optical lens model during deflection.

When the electron beam is deflected by the deflection magnetic field, the deflection magnetic field forms a quadrupole lens component 30 that diverges in the horizontal direction X and focuses in the vertical direction Y with respect to the electron beam. Quadrupole lens component 30 included in this deflection magnetic field
The first segment G of the electron gun assembly to compensate for the effect of
A quadrupole lens is formed between 5-1 and the second segment G5-2 to enhance the lens action as the deflection amount of the electron beam increases.

This quadrupole lens is formed as follows.

That is, as shown in FIG. 1, the first segment G5-1 is supplied with a voltage via the voltage dividing resistor 101 for dividing the anode voltage Eb. When there is no deflection, the second
Focus voltage Vf1 applied to segment G5-2
The resistance value of the voltage dividing resistor 101 is set so that a voltage substantially equal to the voltage is applied to the first segment G5-1. As a result, no voltage difference occurs between the first segment G5-1 and the second segment G5-2 during non-deflection.
No quadrupole lens is formed.

On the other hand, at the time of deflection, since the parabolic dynamic voltage (Vf2 + Vd) is applied to the fourth grid G4, the parabolic AC voltage is applied to the first segment via the capacitance with the fourth grid G4. Induced by G5-1. Therefore, as the deflection amount of the electron beam increases, the applied voltage of the first segment G5-1 decreases,
A voltage difference occurs between the first segment G5-1 and the second segment G5-2.

On the surface of the first segment G5-1 facing the second segment G5-2, a vertically elongated electron beam passage hole is formed as shown in FIG. 2 (a). Further, a laterally long electron beam passage hole as shown in FIG. 2B is formed on the surface of the second segment G5-2 facing the first segment G5-1. Therefore, the first segment G5-
A quadrupole lens having a focusing action in the horizontal direction X and a diverging action in the vertical direction Y can be formed between the first and second segments G5-2.

As shown in FIG. 5C, the quadrupole lens 21 formed between the first segment G5-1 and the second segment G5-2 has an effect of the quadrupole lens component 30 due to the deflection magnetic field. However, the magnification in the horizontal direction X is larger than that in the vertical direction Y, and the horizontal diameter of the beam spot is larger than the vertical diameter, as in the conventional case.

That is, the electron beam emitted from the object point O at the divergence angle αo in both the horizontal and vertical directions is the auxiliary lens 2
It is prefocused by 2 and is focused in the horizontal direction X by the quadrupole lens 21 and diverged in the vertical direction Y. This electron beam is further focused by the main lens 20, and then is incident on the phosphor screen 3 in the horizontal direction X by the quadrupole lens component 30 of the deflection magnetic field.
(7), incident at an incident angle αiy (7) in the vertical direction Y.

At this time, αix (7) <αiiy (7). Therefore, the relationship between the magnification Mx (7) in the horizontal direction X and the magnification My (7) in the vertical direction Y is Mx (7)> My (7). That is, the shape of the beam spot around the phosphor screen is horizontally long. However, as described in FIG. 5B, the auxiliary lens 22 and the main lens 2
With the action of 0, the deterioration of magnification when the distance between the electron gun structure and the phosphor screen is increased is suppressed, and the horizontal diameter of the beam spot in the peripheral portion of the phosphor screen is the beam in the central portion of the phosphor screen. It is possible to prevent the spot from becoming significantly larger than the horizontal diameter.

The incident angles αix (7) and αiy (7) on the phosphor screen 3 in the horizontal direction X and the vertical direction Y shown in FIG. 5 (c) are the phosphors shown in FIG. 5 (b). When compared with the incident angle αi (6) on the screen 3, there is a relationship of αix (7) <αi (6) <αiy (7). As described above, when αi (6) is α1 (6) ≈αi (5), αix (7) <αi (6) ≈αi (5), and Mx (7)> M (6) ≈M As a result of (5), the lens magnification in the horizontal direction is improved as compared with the conventional example. Therefore, significant lateral distortion can be improved. Furthermore, if αi (6)> αi (5), then αix (7) ≈αi (5) and Mx (7) ≈M (5). That is, the horizontal lens magnification in the peripheral portion of the phosphor screen can be made substantially equal to that in the screen center. Therefore, the beam spot on the entire surface of the phosphor screen is as shown in FIG. By applying this electron gun structure as shown in FIG.
The beam spot in the peripheral portion of the phosphor screen can be reduced not only in the horizontal direction diameter but also in the vertical direction diameter as compared with the conventional example shown in FIG.

The reduction of the beam spot leads to the improvement of the resolution, but if the vertical diameter of the beam spot is reduced more than necessary, moiré may occur due to the relationship between the hole pitch of the shadow mask and the scanning line interval. In this case, this is improved by increasing the amount of change in the dynamic voltage (Vf2 + Vd) and setting the vertical direction of the beam spot in an underfocus state. Further, in the horizontal direction of the beam spot, when the amount of change in the dynamic voltage (Vf2 + Vd) is increased, the focusing effect of the auxiliary lens 22 is weakened, and the focal length is increased by increasing the lens aperture of the main lens 20, The focal length reduction due to the strengthening of the lens action of the quadrupole lens in the electron gun structure is offset. Therefore, in the horizontal direction of the beam spot, even if the amount of change in the dynamic voltage (Vf2 + Vd) is increased, the just focus state can be maintained and the spot diameter does not change.

Therefore, the beam spot shape on the phosphor screen is as shown in FIG. 7B, and it is possible to form a substantially uniform beam spot over the entire area of the phosphor screen.

As described above, according to the cathode ray tube device of the present invention, the defocus that occurs when the electron beam is deflected toward the peripheral portion of the phosphor screen is located on the electron beam generating portion side of the main lens. Since the lens strength of the lens is changed (weakened) in synchronization with the deflection to compensate, deterioration of the lens magnification can be suppressed. Further, when the lens strength of the auxiliary lens is weakened, the aberration of the main lens can be reduced by enlarging the substantial lens aperture of the main lens.

Therefore, it is possible to form a beam spot having a substantially uniform size over the entire area of the phosphor screen. Moreover, since the beam spot size can be sufficiently reduced, the display quality can be improved and the resolution can be improved.

[0095]

As described above, according to the present invention, it is possible to reduce the horizontal diameter of the beam spot in the peripheral portion of the phosphor screen and form a uniform beam spot on the entire surface of the phosphor screen. A cathode ray tube device capable of being provided can be provided.

[Brief description of drawings]

FIG. 1 is a horizontal cross-sectional view schematically showing an example of the configuration of an electron gun assembly applied to a cathode ray tube device of the present invention.

2 (a) schematically shows a structure of a surface of a first segment of a fifth grid facing a second segment of a fifth grid applied to the electron gun assembly shown in FIG. FIG. 2B is a front view schematically showing the structure of the surface of the second segment of the fifth grid facing the first segment of the fifth grid.

FIG. 3 is a horizontal sectional view schematically showing the configuration of a color cathode ray tube device according to an embodiment of the cathode ray tube device of the present invention.

FIG. 4 is a diagram showing a relationship between a voltage applied to each electrode of the electron gun assembly shown in FIG. 1 and a deflection current supplied to a deflection yoke.

5A is an optical lens model for explaining a lens action of the electron gun structure shown in FIG. 1 when an electron beam is focused on a central portion of a phosphor screen in a non-deflected state. 5 (b) is an optical lens model for explaining the lens action when the distance between the electron gun structure and the phosphor screen is larger than that in the non-deflected state, and FIG. 5 (c) is an electron beam model. FIG. 6 is an optical lens model for explaining the lens action when deflected toward the peripheral portion of the phosphor screen.

6 is a diagram for explaining a method for enlarging the substantial aperture of the main lens in the electron gun assembly shown in FIG.

7 (a) and 7 (b) are views showing an example of a beam spot formed on a phosphor screen in the cathode ray tube device of the present invention.

FIG. 8 is a diagram showing an example of a beam spot formed on a phosphor screen in a conventional electron gun assembly.

FIG. 9 is a diagram schematically showing a configuration of a conventional electron gun assembly.

10A is a schematic view showing a structure of a surface of the first segment of the third grid facing the second segment of the third grid applied to the electron gun assembly shown in FIG. 9; It is a front view, FIG.10 (b) shows the 2nd of 3rd grid.
It is a front view which shows roughly the structure of the opposing surface with the 1st segment of the 3rd grid of a segment.

11 (a) is an optical lens model for explaining a lens action in a conventional electron gun assembly in a non-deflected state, and FIG. 11 (b) is an electron gun assembly-phosphor screen. FIG. 11C is an optical lens model for explaining the lens action when the inter-distance is enlarged compared to when it is not deflected, and FIG. 11C is an optical lens model for explaining the lens action when deflected.

FIG. 12 is a diagram showing an example of a beam spot formed on a phosphor screen in a conventional electron gun assembly.

[Explanation of symbols]

1 ... panel 2 ... Funnel 3 ... Phosphor screen 4 ... Shadow mask 5 ... neck 6 (R, G, B) ... electron beam 7 ... Electron gun structure 8 ... Deflection yoke 20 ... Main lens 21 ... Quadrupole lens 22 ... Auxiliary lens 101 ... Dividing resistor K (R, G, B) ... Cathode G1 ... 1st grid G2 ... Second grid G3 ... 3rd grid G4 ... 4th grid G5 ... Fifth grid G5-1 ... 1st segment G5-2 ... Second segment G6 ... 6th grid GM1 ... First additional electrode GM2 ... second additional electrode

Claims (5)

[Claims] 1. An electron beam generator that generates an electron beam, at least one auxiliary lens that prefocuses the electron beam generated by the electron beam generator, and an electron beam that is prefocused by the auxiliary lens. Cathode line having an electron gun assembly having a main lens for focusing on a phosphor screen, and a deflection yoke for generating a deflection magnetic field for deflecting an electron beam emitted from the electron gun assembly in horizontal and vertical directions. In the tube device, the electron gun structure includes focus electrodes that constitute the main lens and are sequentially arranged along a traveling direction of an electron beam,
At least two additional electrodes and an anode electrode are provided, and a constant focus voltage is applied to the focus electrode at all times, and an anode voltage that is always constant and higher than the focus voltage is applied to the focus electrode. A parabolic dynamic voltage that is higher than the focus voltage and lower than the anode voltage and that decreases with an increase in the deflection amount of the electron beam is applied to the first additional electrode disposed on the side, and is disposed on the side of the anode electrode. The second additional electrode is applied with a voltage which is always higher than the dynamic voltage and which is substantially equal to the anode voltage when the electron beam is focused on the central portion of the phosphor screen without deflection, and the electron beam is applied to the periphery of the phosphor screen. A voltage that decreases with an increase in the deflection amount of the electron beam is applied during the deflection to deflect toward the At least one of the auxiliary lens La, a cathode ray tube apparatus characterized by focusing force decreases with increasing amount of deflection of the electron beam. 2. The electron gun assembly comprises a quadrupole lens between the electron beam generator and the main lens, the quadrupole lens compensating the astigmatism exerted on the electron beam by the deflection magnetic field. The cathode ray tube device according to claim 1. 3. A voltage applied to the second additional electrode via a voltage dividing resistor for dividing the anode voltage applied to the anode electrode, and a voltage applied to the second additional electrode is The cathode ray tube according to claim 1, wherein the parabolic voltage induced by the dynamic voltage applied to the first additional electrode changes in a parabolic shape as the deflection amount of the electron beam increases. apparatus. 4. The at least one auxiliary lens includes a first electrode, a second electrode, and a third electrode, which are sequentially arranged in a traveling direction of an electron beam, the first additional electrode and the second electrode. An electrode is electrically connected to the first electrode and the third electrode, a voltage substantially equal to the focus voltage is applied to the first electrode and the third electrode when no deflection is performed, and at least one of the first electrode and the third electrode is applied. Is
2. A parabolic voltage that decreases with an increase in the deflection amount of the electron beam is induced by the parabolic dynamic voltage applied to the second electrode.
The cathode ray tube device according to. 5. An electron beam generator that generates an electron beam, at least one auxiliary lens that prefocuses the electron beam generated by the electron beam generator, and an electron beam that is prefocused by the auxiliary lens. Cathode line having an electron gun assembly having a main lens for focusing on a phosphor screen, and a deflection yoke for generating a deflection magnetic field for deflecting an electron beam emitted from the electron gun assembly in horizontal and vertical directions. In the tube device, the electron gun structure includes focus electrodes that constitute the main lens and are sequentially arranged along a traveling direction of an electron beam,
At least two additional electrodes and an anode electrode are provided, and a means for enlarging the substantial lens aperture of the main lens as the electron beam deflection amount increases is provided. At least with the increase
A cathode ray tube device comprising means for reducing the focusing power of one auxiliary lens.