JPH05325825A - Electron gun for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To provide the electron gun for color cathode-ray tube provided with the electrode structure, which can realize the correction of astigmatism and the correction of curvature of screen image simultaneously at a relatively low dynamic electric potential. CONSTITUTION:A fourth electrode 12 forming a main lens consists of a first member 121, a second member 122 and a third member 123, and at least one of a facing part of the first member 121 to the second member 122 and a facing part of the second member 122 to the third member 123 has correcting electrodes 1241, 1242, 1251, 1252 for forming a quadruple lens, and the electric potential to be changed synchronously with the deflecting current is applied to the first member 121 and the third member 123. Correction of astigmatism can be thereby performed with a relatively low dynamic electric potential to obtain the excellent resolution over the whole area of an image screen.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a cathode ray tube, and more particularly to a so-called in-line type electron gun for a color cathode ray tube which emits a plurality of electron beams on one plane.

[0002]

2. Description of the Related Art Generally, an electron gun used for a cathode ray tube is designed to form an electron lens for accelerating and focusing at least one electron beam along an electron beam path extending in the tube axis direction of the cathode ray tube. A plurality of electrodes are arranged at predetermined intervals in the tube axis direction. A plurality of in-line type color cathode ray tubes (usually 3
The book is equipped with an electron gun having a structure for emitting an electron beam.

FIG. 4 is a horizontal sectional view of a color cathode ray tube having a conventional structure of an in-line type electron gun. 1 is a neck portion of a glass envelope, 2 is a face plate portion which is an image display surface, and 3 is a The phosphor screen, 4 is a shadow mask, and 5 is an internal conductive film. The in-line type electron gun is housed in the neck portion 1 of the glass envelope, 6, 7, 8 are cathodes, 9 is a first electrode (G1 electrode), 10 is a second electrode (G2 electrode), 1
Reference numeral 1 is a third electrode (G3 electrode), 12 is a fourth electrode (G4 electrode), 13 is a fifth electrode (G5 electrode), 14 is a sixth electrode (G6 electrode), and 15 is a shield cup electrode.

Reference numeral 16 is a deflection yoke, 17, 18, 1
Reference numeral 9 is a central axis of each electron beam that is substantially parallel to one plane (horizontal plane). In the figure, the electron gun is arranged inside the neck portion 1 of the glass envelope, and the first electrode means, which is an electron beam generating means, and the generated electron beam are directed to the face plate portion 2 of the glass envelope. 3 supported on the inner wall
It is composed of second electrode means for focusing on the fluorescent surface 3 coated with the colored fluorescent material.

The first electrode means is composed of the cathodes 6, 7, 8 and
It is composed of a G1 electrode 9 and a G2 electrode 10. The electron beam accelerated by the first electrode means has central axes 17 arranged substantially parallel to each other on one plane, that is, a horizontal plane,
The light is incident on the main lens portion formed by the second electrode means along the lines 18 and 19. The main lens part is the main lens electrode G
A so-called unipotential focusing lens UPF (Uni-Po) composed of three electrodes 11, a G4 electrode 12, and a G5 electrode 13
tential FocusingLens), G5 electrode 13 and G6 electrode 1
It is composed of two electron lenses of a so-called bipotential type focusing lens BPF (Bipotential Focusing Lens) formed by 4 and a shield cup electrode 15.

G3 electrode 11, G4 electrode 12, G5 electrode 1
3 and the shield cup electrode 15 have openings for passing electron beams, and the central axes of the openings corresponding to the respective electron beams are all the central axes 17, 18, 1.
It agrees with 9. The central axis of the central hole of the G6 electrode 14 which is the other main lens electrode coincides with the central axis 18, but the central axis 2 of both outer holes 2
0 and 21 do not coincide with the central axes 17 and 19 and are slightly displaced outward.

The G6 electrode 14 to which a high potential is applied has the same potential as the shielding cup 15 and the internal conductive film 5 provided inside the glass envelope. The G5 electrode 13 is set to have a lower potential than the G6 electrode 14. G5 electrode 13 and G6
Since the respective apertures in the central part of the electrode 14 are coaxial, a centrally symmetric main lens is formed in the central part between the G5 electrode 13 and the G6 electrode 14, and the central electron beam is focused by the main lens. After that, go straight along the tube axis. On the other hand, since the outer holes of the G5 electrode 13 and the G6 electrode 14 are off-axis from each other, a non-axisymmetric main lens is formed in this portion. Therefore, the electron beam on the outer side passes through a portion of the main lens region, which is formed on the G6 electrode 14 side and is deviated from the lens center axis in the central beam direction, and at the same time as the focusing action by the main lens,
Receives concentration in the central beam direction.

In this way, the three electron beams are focused and simultaneously focused on the shadow mask 4 so as to overlap each other. The operation of concentrating each beam is called static convergence (hereinafter, abbreviated as STC). Further, each electron beam is subjected to color selection by the shadow mask 4, and only the component that excites and emits the phosphor of the color corresponding to each electron beam passes through the aperture of the shadow mask and reaches the phosphor screen. Further, the electron beam is two-dimensionally scanned on the fluorescent screen by the deflection magnetic field formed by the magnetic deflection yoke 16 installed outside the envelope.

By combining the in-line type electron gun in which the three electron beam passages are arranged on one horizontal plane as described above and a so-called self-convergence deflection yoke that forms a special non-uniform magnetic field distribution, the center of the fluorescent screen is obtained. It is known that if the STC is obtained in a part (center of the screen), it is possible to achieve convergence over the entire screen.

However, in general, the self-convergence deflection yoke has a problem that the deflection aberration is large due to the inhomogeneity of the magnetic field and the resolution is lowered in the peripheral portion of the screen.
FIG. 5 is a schematic diagram showing how the electron beam spot on the screen is deformed by the deflection aberration.
511 to 513 are cores and 521 to 523 are halos.

As shown in the figure, in the center of the screen, the high-intensity part (core 511) of the electron beam shown by the slanted line and the low-brightness part (halo 521) shown by the solid line are both circular and exhibit good resolution. However, in the peripheral area of the screen, cores 512 and 513
Spread in the horizontal direction and the halos 522 and 523 spread in the vertical direction, and the resolution is degraded. One means for solving the above problem is disclosed in JP-A-1-137540.

FIG. 6 is a schematic view showing a structural example of the conventional electron gun disclosed in the above publication, and is a horizontal sectional view showing one electron beam. In the figure, the same reference numerals as those in FIG. 4 correspond to the same parts, 131 is a first member forming a fifth electrode (G5 electrode), and 132 is a second member.
It is a member. In this figure, this electron gun is formed by dividing a G5 electrode, which constitutes a focusing electrode, into a first member 131 and a second member 132 from the cathode 7 toward the phosphor screen. The end face of the first member 131 facing the second member 132 is provided with a single laterally long opening 1311, and the end face of the second member 132 facing the first member 131 has three electron beam passage holes. The first member 131 so that the upper and lower parts (vertical direction) are rubbed and rubbed.
A pair of flat plate-shaped correction electrodes 1331, 13 extended in the direction
32 is connected, and a voltage that dynamically changes in synchronization with the deflection current supplied to the deflection yoke, that is, a dynamic voltage Vd is superimposed on the focusing voltage Vf and given.

When the deflection amount of the electron beam is large (when scanning the peripheral portion of the screen), the first member 131 and the second member 132 are used.
The potential difference between the plate-shaped correction electrodes 1331, 13
The quadrupole lens formed by 32 becomes stronger,
Large astigmatism occurs in the electron beam spot on the screen. If the potential of the second member 132 is higher than that of the first member 131, the astigmatism produced in the electron beam has the effect of lengthening the core vertically and the halo horizontally, and thus is shown in FIG. Astigmatism associated with electron beam deflection can be canceled, and the resolution at the peripheral portion of the screen can be improved.

On the other hand, when the electron beam is not deflected (when the central portion of the screen is being scanned), the dynamic voltage Vd superimposed on the second member 132 is lowered to make the first member 131 and the second member 132. Since the quadrupole lens is not formed by eliminating the potential difference between and, and the condition that astigmatism does not occur in the central portion of the screen can be obtained, deterioration of resolution does not occur.

Further, in the color cathode ray tube, since the distance from the main lens to the peripheral portion of the screen is longer than the distance from the main lens to the central portion of the screen, the conditions for electron beam focusing in the central portion and the peripheral portion. However, when the electron beam is focused in the central part, it is not focused in the peripheral part and the resolution deteriorates. This is called field curvature. However, in the conventional technique shown in FIG. 6, when the electron beam is deflected to the periphery of the screen, the potential of the second member 132 is increased, so the potential difference from the acceleration voltage Eb of the acceleration electrode (G6) 14 is reduced and the main lens is reduced. Lens strength weakens. For this reason, the electron beam focusing point is extended in the screen direction, and the electron beam can be focused on the screen even in the peripheral portion of the screen, and also in this point, deterioration of the resolution in the peripheral portion of the screen can be prevented. That is,
Dynamic astigmatism correction and field curvature correction can be realized at the same time.

It is needless to say that the above-mentioned electron gun is an example, and there are other electron guns having various structures.

[0017]

In the above prior art, the means for correcting the field curvature is the G5 electrode 13 and the G5 electrode.
In order to realize a dynamic deflection aberration correction in the peripheral portion of the screen with a single lens formed between the six electrodes 14,
There is a problem that a circuit means for generating a relatively high dynamic potential is required.

An object of the present invention is to provide an electron gun for a color cathode ray tube having an electrode structure capable of simultaneously performing astigmatism correction and field curvature correction with a relatively low dynamic potential.

[0019]

To achieve the above object, the present invention generates a plurality of electron beams and directs these electron beams along initial paths that are parallel to each other on one plane. In the electron gun for a color cathode ray tube, comprising: a first electrode means for directing the electron beam to the fluorescent screen, and a second electrode means constituting a main lens for focusing each electron beam on the fluorescent screen, the second electrode means The third electrode 11, the fourth electrode 12, and the fifth electrode 13 are sequentially arranged in the direction of the fluorescent surface from the side of the first electrode means, and a high potential is applied to the third electrode 11 and the fifth electrode 13. And a medium potential is applied to the fourth electrode 12, and the fourth electrode 12 moves from the side of the first electrode means toward the fluorescent surface toward the first member 121,
The quadrupole lens is divided into three parts, that is, a second member 122 and a third member 123, and at least one of the facing portion of the first member 121 and the second member 122 and the facing portion of the second member 122 and the third member 123. Electrodes 1241 and 124 for forming
2, 1251 and 1252, each of which changes independently of the first member 121 and the third member 123 in synchronization with a deflection current supplied to a deflection yoke provided for scanning the electron beam. Is applied to the quadrupole lens and the lens strength formed between the third electrode 11 and the first member 121 and between the fifth electrode 13 and the third member 123 is the deflection angle of the electron beam. It is characterized in that the configuration is changed according to.

Further, according to the present invention, the electron beam passage hole 127 of the second member 122 is a single opening, and the first member 121 or the first member 121 having a facing surface in the single opening 127 of the second member 122 or Upper and lower sides (vertical direction) of the electron beam passage holes 126 and 129 of the third member 123 or both members.
The plate-shaped correction electrode 12 extended in the direction of the second member 122
It is characterized by having a structure in which 41, 1242, 1251, 1252 are connected.

Further, according to the present invention, the diameter on one plane in each plane of the electron beam passage holes 127 and 128 provided in the second member 122 is smaller than the diameter of each vertical aperture. And the first member 12 having the facing surface.
1 or 3rd member 123, or 2nd member 1 of both members
It is characterized in that the diameter of each electron beam passage hole on the surface opposed to 22 on the one plane is larger than the diameter of each hole perpendicular to the one plane.

The present invention is characterized in that the potentials applied to the first member 121 and the third member 123 are common. That is, the main lens portion is connected to the third electrode 11 (G
3 electrodes), 4th electrode 12 (G4 electrode), 5th electrode 13
(G5 electrode), the third electrode 11 (G3 electrode)
And a high potential (anode potential Eb) on the fifth electrode 13 (G5 electrode)
Is a so-called UPF electron lens that applies a medium potential to the fourth electrode 12 (G4 electrode).

In order to correct the field curvature, when the potential of the fourth electrode 12 (G4 electrode) is raised when the electron beam is deflected to the peripheral portion of the screen, the third electrode 11 (G3 electrode) and the fourth electrode 12 (G3 electrode) are raised.
Since the two lens strengths formed between the electrodes 12 (G4 electrodes) and between the fourth electrode 12 (G4 electrodes) and the fifth electrode 13 (G5 electrodes) are weakened at the same time, correction is performed with a conventional single lens. Compared to the case, it can be corrected with a lower voltage.

When astigmatism correction is performed at the same time, the fourth electrode 12 (G4 electrode) is replaced with the first member 121 and the second member 12.
2, by dividing into a third member 123 and forming two quadrupole lenses between the first member 121 and the second member 122 and between the second member 122 and the third member 123, a single quadrupole Astigmatism correction can be performed with a lower voltage than in the case of a lens.

As an example of the quadrupole lens structure, a single laterally elongated opening is provided on both end surfaces of the second member 122, and the first member 1
21 and the third member 123, plate-shaped correction electrodes 1241, 1 extending in the direction of the second member 122 above and below the electron beam passage holes 126, 129 on the end faces facing the second member 122.
242, 1251, 1252 are connected to each other, and the second member 122
In this configuration, the dynamic voltage Vd, which changes in synchronization with the deflection current, is applied to the first member 121 and the third member 123 while keeping the potential of the constant.

[0026]

With the electrode structure according to the present invention, when the electric potentials of the first member 121 and the third member 123 are increased during deflection,
Since the third electrode 11 (G3 electrode) and the first member 121 and the fifth electrode 13 (G5 electrode) and the third member 123 are directly opposed to each other, the action of weakening the lens strength, that is, the field curvature is reduced to 2
It can be corrected in one place.

Further, the second member 122 and the first member 121,
By changing the potential difference with the third member 123 so as to be synchronized with the deflection current, astigmatism due to deflection can be corrected at two places. Therefore, a circuit that generates a relatively low dynamic potential can be used. The quadrupole lens may be provided between the third electrode 11 (G3 electrode) and the first member 121 and between the fifth electrode 13 (G5 electrode) and the third member 123. It goes without saying that the field curvature correction and the astigmatism correction can be improved as compared with the above-mentioned conventional technique.

[0028]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic view for explaining an embodiment of an electron gun for a color cathode ray tube according to the present invention, which is a horizontal cross-sectional view showing one electron beam. Also,
FIG. 2 shows the direction of arrow AA ′ and arrow (B) — of FIG.
FIG. 1B is a cross-sectional view seen from the direction (B ′),
62 and 1263 are electron beam passage openings provided in the first member,
(1291), (1292), and (1293) are electron beam passage openings provided in the third member.

The same reference numerals as those in FIG. 6 correspond to the same parts, and reference numerals 121, 122 and 123 denote the first, second and third members constituting the fourth electrode 12 (G4 electrode) which is a focusing electrode. , 1241 and 1242 are correction electrodes connected to the first member 121, and 1251 and 1252 are correction electrodes connected to the third member 123. As shown in FIG. 1, the fourth electrode 12 (G4 electrode), which is a focusing electrode, is divided into a first member 121, a second member 122, and a third member 123.
2 has a single horizontally long opening 12 as an electron beam passage hole.
7,128 are provided on both end faces.

Further, as shown in FIG. 2, the first member 121
Are provided with three circular electron beam passage holes 1261, 1262, and 1263 on the end surface facing the second member 122, and a flat plate shape extending in the direction of the third member 123 is provided above and below these electron beam passage holes. The correction electrodes 1241 and 1242 are connected. In addition, the third member 123 has three circular electron beam passage holes 1291, 1 on the end surface facing the second member 122.
292 and 1293 are provided, and flat plate-shaped correction electrodes 1251 and 1252 extending in the direction of the first member 121 are connected above and below these electron beam passage holes.

A constant first focusing voltage Vf ₁ is applied to the second member 122, and a constant second focusing voltage Vf ₂ is superimposed on the first member 121 and the third member 123 to apply a dynamic voltage Vd. To do. When the electron beam is deflected, the dynamic voltage Vd is increased as the deflection amount increases.
As the dynamic voltage Vd rises, the second member 122
The strength of the quadrupole lens formed at the facing portion of the first member 121 and the third member 123 is increased, and astigmatism due to electron beam deflection can be corrected.

At the same time, the third electrode 1 which is the acceleration electrode
1 (G3 electrode) and the fifth electrode 13 (G5 electrode) and the acceleration voltage Eb applied to the first member 121 and the third member 123 due to the reduction of the potential difference between the reduction of the main lens strength, the main lens. Since the distance between the electron beam focusing point and the electron beam focusing point becomes long, the electron beam can be well focused even in the peripheral portion of the screen. That is, the dynamic astigmatism correction and the field curvature correction are simultaneously performed.

The electron beam passage hole 127 of the second member 122 is a single opening, and the first member 121 or the third member 123 has a surface facing the single opening 127 of the second member 122. , Or flat plate correction electrodes 1241 and 12 extending in the direction of the second member 122 above and below (vertical direction) the electron beam passage holes 126 and 129 of both members.
A structure in which 42, 1251, and 1252 are connected is added.

Further, the diameter on one plane in each plane of the electron beam passage holes 127, 128 provided in the second member 122 is smaller than the diameter of each vertical opening, and The diameter on the one plane of each electron beam passage hole of the first member 121 or the third member 123 having the facing surface or the facing surface of the both members facing the second member 122 is each opening perpendicular to the one surface. The structure should be larger than the diameter of the hole. Then, a common potential is applied to the first member 121 and the third member 123.

In the electrode structure shown in FIG. 1, the first member 12
Since the quadrupole lens is formed at the facing portion of the first and second members 122 and the second member 122 and the third member 123, efficient astigmatism correction is performed. This allows the use of circuits that generate relatively low dynamic potentials. An example of each electrode length and applied voltage is shown below for one embodiment of the present invention shown in FIG.

Acceleration voltage Eb: 30 KV Focusing voltage Vf: 8.4 KV G3 electrode 11 length: 2.1 mm G4 electrode first member 121 length: 16.0 mm G4 electrode second member 122 length: 12.0 mm G4 electrode third member 123 length: 10.0 mm G5 electrode 13 length: 7.5 mm Main lens-screen center distance: 340 mm Plate-shaped correction electrodes 124,125 second member direction extension amount: 3.0 mm Here, there are two quadrupole lenses. Although the number is increased, one quadrupole lens may be used and the size thereof may be changed to increase the strength. A configuration in which the number of quadrupole lenses is increased to three or more is also possible.

FIG. 3 is a schematic view similar to FIG. 1 for explaining another embodiment of the electron gun for a color cathode ray tube according to the present invention, and is an explanatory view of a constitutional example in which one quadrupole lens is used. In the figure, the only difference from the embodiment described with reference to FIG. 1 is that the quadrupole lens is formed only between the second member and the third member forming the fourth electrode 12, Other configurations are the same as those in FIG.

In this structure, the plate-shaped correction electrodes 1251 and 1252 forming the quadrupole lens have the first dimension.
By extending in the member direction or narrowing the distance between the two, it is possible to simultaneously perform dynamic astigmatism correction and field curvature correction, as in the configuration described in FIG. The quadrupole lens is used as the first member 121 and the second member 1.
It is also possible to make it between 22.

[0039]

As described above, according to the present invention,
By using the same dynamic voltage generation circuit as in the prior art, it is possible to correct the astigmatism associated with the electron beam deflection to the peripheral portion of the screen of the color cathode ray tube and simultaneously realize the dynamic focus. In addition, the first member and the third member that form the fourth electrode
Since the dynamic voltage is applied to the member, the quadrupole lens strength can be increased and the main lens strength can be reduced at the facing portions of the first member, the third member, and the second member, so that the deflection is performed at a relatively low dynamic potential. It is possible to provide an electron gun for a color cathode ray tube having an excellent function by solving the problems of the above-mentioned conventional techniques such as correction of aberration.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating one embodiment of an electron gun for a color cathode ray tube according to the present invention.

FIG. 2 is an arrow AA ′ direction and an arrow (B) — of FIG.
It is sectional drawing seen from the (B ') direction.

FIG. 3 is a schematic view similar to FIG. 1 for explaining another embodiment of the electron gun for a color cathode ray tube according to the present invention.

FIG. 4 is a horizontal sectional view of a color cathode ray tube having a conventional structure of an in-line type electron gun.

FIG. 5 is a schematic diagram showing how an electron beam spot on a screen is deformed by deflection aberration.

FIG. 6 is a schematic diagram showing a structural example of an electron gun according to a conventional technique.

[Explanation of symbols]

7 Cathode 9 1st electrode 10 2nd electrode 11 3rd electrode 12 4th electrode 13 5th electrode 15 Shielding cup electrode 121 1st member 122 2nd member 123 3rd member 1241,1242,1251,1252 Plate-shaped correction electrode 1261, 1262, 1263 Electron beam passage opening provided in the first member 121 1291, 1292, 1293 Electron beam passage opening provided in the third member 123

Claims (1)

[Claims] 1. A first electrode means for generating a plurality of electron beams and directing these electron beams to a phosphor screen along initial paths parallel to each other on one plane, and each of the electron beams described above. In the electron gun for a color cathode-ray tube, comprising: a second electrode means which constitutes a main lens for focusing on the first lens means, the second electrode means are sequentially arranged from the first electrode means side in the fluorescent surface direction. And a third electrode, a fourth electrode, and a fifth electrode. A high potential is applied to the third electrode and the fifth electrode, an intermediate potential is applied to the fourth electrode, and the fourth electrode is the first electrode. The first member, the second member, and the third member are divided into three parts from the electrode means side in the fluorescent surface direction, and the first member and the second member face each other, and the second member and the third member face each other. A correction electrode forming a quadrupole lens on at least one of the parts A potential that independently changes in synchronization with a deflection current supplied to a deflection yoke provided for scanning the electron beams is applied to each of the first member and the third member, and the quadrupole lens and An electron gun for a color cathode ray tube, characterized in that lens strengths formed between the third electrode and the first member and between the fifth electrode and the third member are changed according to the deflection angle of the electron beam. ..