JPH0562610A - Picture tube - Google Patents

Abstract

PURPOSE:To increase the size of the diameter of a main lens to a maximum limit, and to provide a high resolution picture tube, for which the increase in the spot diameter due to spherical aberration is suppressed without lowering the focus voltage value. CONSTITUTION:A picture tube is provided with an electron gun having a first electrode part generating a single or a plurality of electron beams of in-line arrangement, and a second electrode part comprising a plurality of main lens electrodes, by which the single or the plurality of electron beams are focused on a fluorescent screen. At least one pair of electrodes 12, 13 of the main lens electrodes are arranged to have opposed surfaces, while the cross sections of the pair of electrodes 12, 13 are to be flat in the same direction. For the electron gun, there is no partition for correcting astigmatism to separate the plurality of electron beams from one another, in the pair of electrodes 12, 13, and the degree of flatness of the high voltage application electrode 13 is greater than the low voltage application electrode 12 in cross section.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a picture tube equipped with an electron gun for generating a plurality of or a single electron beam for scanning a phosphor screen, and more particularly to a main lens composed of a main lens electrode of the electron gun. The present invention relates to a picture tube which is configured to obtain a high-resolution image by maximizing the aperture of the main lens and suppressing an increase in the spot diameter due to the spherical aberration of the main lens.

[0002]

2. Description of the Related Art A picture tube used for color image display (hereinafter,
A color picture tube) is composed of a panel section which is an image screen, a neck section which houses the electron gun, and a funnel section which connects the panel section and the neck section, and the electrons emitted from the electron gun are connected to the funnel section. A deflecting device for scanning the beam on the fluorescent surface coated and formed on the inner surface of the panel is mounted.

The electron gun housed in the neck portion has a cathode electrode for generating an electron beam, a control electrode for controlling the electron beam, focusing and accelerating the controlled electron beam,
Equipped with various electrodes for convergence.
Then, the electron beam emitted from the cathode electrode is modulated by the signal applied to the control electrode, and then the electron beam is imparted with a required cross-sectional shape and energy in the various electrodes to bring it into a convergence state. Make it hit the phosphor screen. Further, the electron beam is
On the way from the electron gun to the fluorescent screen, the deflection device provided in the funnel section receives horizontal and vertical deflections to form a desired image on the fluorescent screen.

FIG. 5 is a sectional structural view showing an example of a conventional color picture tube having the electron gun having the above-mentioned structure, which is disclosed in Japanese Patent Laid-Open No. 58-103752.

In FIG. 5, 51 is a glass envelope, and 52 is a glass envelope.
Is a face plate, 53 is a fluorescent screen, 54 is a shadow mask, 55 is a conductive film, 56, 57 and 58 are cathode electrodes, 59 is a first (G1) electrode, 60 is a second (G2) electrode, and 61 is a third electrode. (G3) electrode, 62 is the fourth (G4) electrode, 63 is a shield cup, 64 is a deflection yoke, and 65, 6
Reference numerals 6 and 67 are the central axes of the three electron beams, 68 and 69 are central axes of the openings 73 and 75, 70, 71 and 72 are openings provided in the G3 electrode 61, and 73, 74 and 75 are G4 electrodes 6.
It is an opening provided in 2.

The electron gun is arranged at the neck portion of the glass envelope 51 and has a first electrode portion for generating three electron beams corresponding to three colors of red, green and blue, and the above-mentioned three. The second electrode portion is configured to converge the electron beam of the book on the fluorescent screen 53 of the corresponding color in the face plate 52 of the glass envelope 51 (concentration).

The first electrode portion is composed of three cathode electrodes 56, 57 and 58 arranged in-line, and a G1 electrode 59 and a G2 electrode 60 common to the three electron beams, and a second electrode portion. Comprises a G3 electrode 61, a G4 electrode 62, and a shielding cup 63, which form the main lens portion. Further, the G3 electrode 61 is provided with openings 70, 71, 72 through which each electron beam passes,
The G4 electrode 62 also has an opening 7 through which each electron beam passes.
3, 74 and 75 are provided, and the shield cup 63 is also provided with openings 76, 77 and 78 through which the respective electron beams pass.

These openings 70 in the main lens section
The central axes of the openings 70, 71, 72, 76, 77, and 78 provided in the G3 electrode 61 and the shielding cup 63 among the central axes 65 to 6 of the corresponding electron beams 65 to 6 respectively.
It is consistent with 6, 67. However, among the openings 73, 74, 75 provided in the G4 electrode 12, the central opening 74
Although the central axes of the two correspond to the central axes 66 of the corresponding electron beams, the central axes 68 and 69 of the two outer holes do not coincide with the central axes 65 and 67 of the corresponding electron beams, respectively. , Slightly displaced outwards from them.

The applied potential of the G3 electrode 61 is set to be lower than that of the G4 electrode 62, and the G4 electrode 62 to which a high potential is applied has a shield cup 63 and a glass envelope 5.
It is the same as the applied potential of the conductive film 55 provided inside 1. Further, since the openings 71 and 74 in the central portions of the G3 electrode 61 and the G4 electrode 62 are coaxially arranged on the central axis 66 of the electron beam, the central portion between the G3 electrode 61 and the G4 electrode 62 has a main axis of symmetry. A lens is formed.

The three electron beams generated at the first electrode portion travel along the respective central axes 65, 66, 67 and enter the main lens portion. In this, the central electron beam is focused by the main lens and then travels straight along a trajectory along the central axis 66.

On the other hand, since the central axes of the outer openings 70, 73 of the G3 electrode 61 and the outer openings 70, 73 of the G4 electrode 62 are displaced from each other, the openings 70, 7 of the G3 electrode 61 and the G4 electrode 62 are displaced from each other.
A non-axisymmetric main lens is formed between the lens 3 and the openings 72 and 75. Therefore, the two outer electron beams pass through a position deviated from the lens center axis in the central electron beam direction in the divergent lens region formed on the G4 electrode 62 side in the main lens region, and At the same time as the focusing action, it receives a concentration force in the central electron beam direction. In this way, the three electron beams are focused and simultaneously concentrated on the shadow mask 4 so as to overlap with each other, and static convergence is achieved.

At this time, each electron beam is subjected to color selection by the shadow mask 54, and only the component that excites and emits the phosphor of the color corresponding to each electron beam is shadow mask 54.
To reach the fluorescent screen 53. An external magnetic deflection yoke 64 is provided to scan each electron beam on the phosphor screen 53.

In the conventional color picture tube described above, one of the factors that greatly affects the resolution of an image is the spherical aberration of the main lens. If the spherical aberration of this main lens is reduced, In order to suppress the increase of the spot diameter on the phosphor screen 53 and improve the resolution, and to reduce the spherical aberration of the main lens,
It is already known that the enlargement of the diameter of the electrode forming the main lens is effective.

However, in the conventional in-line type electron gun as shown in FIG. 5, a structure in which cylindrical main lenses corresponding to the red, green and blue electron beams are arranged in the same plane is adopted. Therefore, the diameter of each main lens must be ⅓ or less of the inner diameter of the neck portion of the glass envelope 1, and further, considering the thickness of each electrode 61, 62, 63, etc., and It is obvious that the limit value of the aperture of each main lens becomes a smaller value in consideration of the processing accuracy of each of the electrodes 61 to 63.

In this case, in order to expand the limit value,
A means for enlarging the inner diameter of the neck portion is also conceivable, but if such a means is adopted, a problem occurs that the deflection power of the deflection yoke 64 arranged outside the funnel portion increases.

Therefore, in the conventional color picture tube described above, the inner diameter of the neck portion is not increased,
Means is provided for providing a non-cylindrical main lens that effectively enlarges the aperture of the main lens above the limit value.

6A and 6B show an example of a non-cylindrical main lens in which the aperture of the main lens is effectively enlarged, and FIG. 6B is a sectional view taken along line AA of FIG. 6A. Is.

In FIG. 6, 611 is an electrode plate of the G3 electrode 61, 621 is an electrode plate of the G4 electrode 62, and 612 and 61.
3, 614 are electron beam passage openings provided in the electrode plate 611, and 622, 623, 624 are electron beam passage openings provided in the electrode plate 621. In addition, the same constituent requirements as those shown in FIG. The same code is attached.

In the above structure, the G3 electrode 6
1 and the electrode plate 6 arranged at the facing portion of the G4 electrode 62
The reference numerals 11 and 621 are provided at positions (inside the G3 electrode 61 and the G4 electrode 62) retracted from the conventional arrangement positions of the electrode plates. Such an electrode plate 6
With the arrangement configuration of 11, 621, the G3 electrodes 61 and G
The electric field penetrates deeply into the four-electrode 62, and the same effect as expanding the aperture of the main lens is produced.

However, in the above arrangement, G3
The cross-sectional shapes of the openings of the electrode 61 and the G4 electrode 62 are not axially symmetric, and the diameter in the horizontal direction is larger than the diameter in the vertical direction. Therefore, the penetration of the electric field becomes significantly large in the horizontal direction, and the lens focusing force in the horizontal direction becomes weaker than the lens focusing force in the vertical direction. This causes astigmatism in the main lens, and the cross-sectional shape of the electron beam is deformed so that the horizontal direction is longer than the vertical direction.

In order to correct the influence of this astigmatism, in the above-mentioned conventional color picture tube, the electrode plate 611,
Electron beam passage openings 612, 61 provided in 621
The shapes of 3, 614, 622, 623, and 624 are configured such that the horizontal diameter is smaller than the vertical diameter. With this configuration, the focusing electric field in the horizontal direction with respect to the electron beam is made stronger than that in the vertical direction, the focusing forces in both the horizontal and vertical directions with respect to the electron beam are balanced, and the influence of the astigmatism is removed.

[0022]

However, in the above-described conventional color picture tube, the electrode structure of the electron gun has the following problems.

That is, in order to make full use of the effect of enlarging the aperture of the main lens, it is necessary to enlarge the cross-sectional diameter of each electron beam passing through the main lens. However, when the cross-sectional diameter of each electron beam is expanded to a certain value or more, a part of the electron beam collides with the electrode plate 611 inside the G3 electrode 61, causing an undesired current in the G3 electrode 61. When this undesired current is generated, the current flows into a high-impedance power supply circuit that generates the voltage (focus voltage) of the G3 electrode 61 and lowers the focus voltage value. Therefore, when the current value is considerably large, it is normal. There is a problem that the picture tube cannot be operated under various focus conditions.

Further, in the above-mentioned main lens formed in the electron gun of the conventional color picture tube, the diameter of the main lens can be enlarged in the horizontal direction up to the limit value due to the inner diameter of the neck, but in the vertical direction the main lens is enlarged. Since a supporting rod (usually using glass) for insulating and fixing the G3 electrode 61 and the G4 electrode 62 constituting the above is arranged, it is impossible to expand to the limit value due to the inner diameter of the neck in the vertical direction. However, there is a problem that the lens aberration in the vertical direction cannot be reduced beyond a certain value.

The present invention has been devised to solve the above-mentioned problems, and its purpose is to maximize the diameter of the main lens and to reduce the focus voltage value without causing a spherical aberration. An object of the present invention is to provide a color picture tube that suppresses an increase in the spot diameter of an electron beam and obtains a high-resolution image.

[0026]

In order to achieve the above object, the present invention provides a first electrode portion arranged on one plane and generating a controlled single or plural electron beams.
A cathode ray tube comprising an electron gun comprising a plurality of main lens electrodes and having a second electrode portion for focusing a single or a plurality of electron beams from the first electrode portion on a fluorescent screen. Of at least a pair of electrodes are arranged to have opposing surfaces, the cross section of the pair of electrodes is configured to be flat in the same direction, and the inside of the pair of electrodes separates the plurality of electron beams from each other. The astigmatism correction partition does not exist at least on the one plane, and the cross section of the pair of electrodes has an electrode on the side to which a high voltage is applied as compared with an electrode on the side to which a low voltage is applied. First comprising an electron gun configured to have a high degree of flatness
Equipped with the means.

In order to achieve the above object, the present invention provides a first electrode portion arranged on a plane and generating a controlled single or plural electron beams, and a plurality of main lens electrodes. And a second electrode section for focusing a single or a plurality of electron beams from the first electrode section on a phosphor screen, the cathode ray tube comprising at least a pair of electrodes in the main lens electrode. Are arranged so as to have opposite surfaces, and the cross sections of the pair of electrodes are configured to be flat in the same direction, and the inside of the pair of electrodes is for astigmatism correction that separates the plurality of electron beams from each other. The partition is configured not to exist on at least the one plane,
Further, there is provided a second means including an electron gun having a means for flattening the cross section of the electron beam incident on the pair of electrodes in the same direction as the cross section of the pair of electrodes having the facing surface.

[0028]

According to the present invention, in the conventional picture tube, the astigmatism correction partition wall (electrode plate) which separates the plurality of electron beams from each other and which is disposed inside the pair of electrodes is removed. Therefore, even when the diameter of the cross section of each electron beam is sufficiently expanded in order to increase the diameter of the main lens, each electron beam does not approach the partition wall (electrode plate). Therefore, each electron beam never collides with the partition wall (electrode plate), and the focus potential does not decrease.

Further, according to the present invention, since the electrode supporting rod which supports and fixes the main lens electrode is removed at least in the constituent parts of the main lens, the vertical direction in the main lens is close to the limit value due to the inner diameter of the neck portion. It is possible to increase the aperture in the direction, and it is possible to reduce aberrations by the amount of the increase.

Further, it is known that the increase in electron beam spot diameter due to spherical aberration is proportional to the cube of the beam incident angle with respect to the main lens. Therefore, even if the aperture of the main lens in the vertical direction cannot be sufficiently expanded, spherical aberration can be reduced by reducing the beam incident angle in the vertical direction. Therefore, in the present invention, the electron beam incident on the main lens is strongly focused in advance in the vertical direction as compared with the horizontal direction, and the electron beam is expanded in the horizontal direction in the main lens portion as compared to the vertical direction. Since the incident angle of the electron beam in the vertical direction with respect to the main lens can be reduced, spherical aberration can be reduced.

[0031]

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

FIG. 1 is a schematic block diagram showing an embodiment of a picture tube according to the present invention.

In FIG. 1, 1 is a panel portion, 2 is a funnel portion, 3 is a neck portion, 4 is a fluorescent screen, 5 is a shadow mask, 6 is a magnetic shield, 7 is a deflection yoke, 8 is a purity adjusting magnet, and 9 is A center beam static convergence adjustment magnet, 10 is a side beam static convergence adjustment magnet, 11 is an electron gun, Bc is a center beam, and Bs is a side beam.

To adjust the convergence of the picture tube (static convergence), first, two side beams B are used.
After the convergence of s and Bs is taken, the center beam Bc and the convergence point of the side beam Bs are concentrated.

If necessary, a thin film, such as SnO ₂ or In, is formed on the outer surface of the panel 31 to prevent reflection and electrification.
A thin film containing ₂ O ₃ or the like is formed in a single layer or multiple layers. Further, although not shown, the funnel portion 2 and the neck portion 3
An inner conductive film made of graphite or the like is deposited on the inner surface of the, and this conductive film electrically connects a high-voltage terminal (not shown) and the electron gun 11.

FIG. 2 is a cross-sectional view (a) showing an embodiment of the arrangement of the main lens electrodes of the electron gun used in the picture tube, and a vertical cross-section view (b) taken along the line A--A. ).

In FIG. 2, 12 is a G3 electrode and 13 is a G3 electrode.
Four electrodes, 14 are cup electrodes, and 15 is an electrode support rod.

The G3 electrode 12 and the G4 electrode 13 are arranged in such a manner that they have opposing surfaces. In this embodiment,
G4 electrode 1 goes deep inside the opening of G3 electrode 12
3 has an arrangement configuration in which the opening portion of 3 is inserted and arranged to form the facing surface.
The astigmatism correction partition wall (electrode plate) arranged near the respective openings of the G4 electrode 13 and the G4 electrode 13 is omitted. Also, G
A focus voltage of about 5 to 10 Kv is applied to the third electrode 12, and a high voltage of about 20 to 33 Kv is applied to the G4 electrode 13, so that a main lens is formed between the G3 electrode 12 and the G4 electrode 13. Further, the diameter of the G3 electrode 12 in the vertical direction is reduced at both ends, and an electrode support rod 15 that supports the G3 electrode 12 and the G4 electrode 13 is arranged in the reduced portion. On the other hand, in the portion where the main lens is formed, the diameter of the G3 electrode 12 in the vertical direction is enlarged, and the electrode support rod 15 in this portion is removed. Then G
Each of the 3rd electrode 12 and the G4 electrode 13 is configured to have a so-called flat shape whose cross-sectional shape is long in the horizontal direction and short in the vertical direction.

The main lens electrode shown in FIG. 2 operates as described below.

When an electron beam is incident on this main lens electrode, the electron beam becomes horizontally long at the G3 electrode 12 and vertically long at the G4 electrode 13 due to the flat shape of the cross section of the G3 electrode 12 and the G4 electrode 13. The lens action like that works on each electron beam. As aforementioned,
Since a lower potential is applied to the G3 electrode 12 than the G4 electrode 13, the velocity of the electron is slow and the staying time is long in the region of the G3 electrode 12. For this reason,
Flatness of G3 electrode 12 and G4 electrode 13 (flatness)
Is the same, the electron beam is strongly affected by the lens action in the G3 electrode 12 and is deformed so that the cross section becomes horizontally long as a whole, and strong astigmatism is generated in the main lens.

In order to correct this astigmatism, in the present embodiment, regarding the cross-sectional shapes of the G3 electrode 12 and the G4 electrode 13, the flatness on the G4 electrode 13 side is larger than that on the G3 electrode 12 side. It has a simple structure. G4 electrode 1
When the flatness on the 3 side is increased, the lens action for making the electron beam in the G4 electrode 13 into a vertically elongated shape becomes stronger, and the lens action to make the electron beam in the G3 electrode 12 into a horizontally elongated shape is canceled out. Aberration can be corrected. In addition, in this embodiment,
Since the astigmatism correction partition wall (electrode plate) is omitted,
When the electron beam has a horizontally elongated cross section at the G3 electrode 12, a part of the electron beam collides with the astigmatism correction partition wall (electrode plate), causing an undesired current of the G3 electrode 12 or focusing. It does not reduce the voltage.
Further, since the electrode support rod 15 supporting the G3 electrode 12 and the G4 electrode 13 is removed from the outer portion of the G3 electrode 12 on which the main lens is formed, the vertical diameter of the main lens can be made conventional. It becomes possible to expand in comparison.

FIG. 3 is a graph showing the relationship between the flatness ratio R between the G3 electrode 12 and the G4 electrode 13 and the astigmatism voltage ΔVf obtained by three-dimensional electron beam analysis.

Here, as shown in FIG. 2B, the flatness ratio R is such that the horizontal inner diameters of the G3 electrode 12 and the G4 electrode 13 are H3 and H4, and the vertical inner diameters thereof are V3 and V4, respectively. Then, (V3 / H3) / (V4 / H
4). The astigmatism voltage ΔVf is the difference (Vf) between the focus voltage Vfh that minimizes the diameter of the electron beam in the horizontal direction and the focus voltage Vfv that minimizes the diameter of the electron beam in the vertical direction.
h-Vfv).

In FIG. 3, if the astigmatism voltage ΔVf becomes zero, the focusing conditions in the horizontal and vertical directions match,
Astigmatism will be corrected. The astigmatism voltage ΔVf takes a positive value when the flatness ratio R is larger than a certain value (about 1.49), and the flatness ratio R has a certain value (about 1.49).
Positive values increase with larger values. On the other hand, if the flatness ratio R is smaller than a certain value (about 1.49), it takes a negative value, and as the flatness ratio R becomes smaller than a certain value (about 1.49), the negative value also increases. I understand that

Here, an example of specific values of the inner diameters H3, H4, V3 and V4 that satisfy the astigmatism correction condition is as follows.

V3 = 13.2 mm, H3 = 21 mm, V4 = 7.6 mm, H4 = 18 mm However, the above values are merely examples in the case of satisfying the astigmatism correction condition. The invention is not limited to the values given above, of course other values are possible.

As described above, in the above-described embodiment shown in FIG. 2, although the aperture of the main lens can be enlarged, the degree of improvement of the spherical aberration in the vertical direction of the main lens is in the horizontal direction. Since the degree of improvement in spherical aberration is inferior, the phenomenon that the spot shape of the electron beam on the phosphor screen becomes vertically long may occur.

The embodiments described below are configured to improve such an unnatural phenomenon.

FIG. 4 is a cross sectional view (a) showing another embodiment of the arrangement of the main lens electrodes of the electron gun used for the picture tube, and a vertical cross sectional view taken along the line A--A ( b).

In FIG. 4, 16 is a G3 electrode and 17 is a G3 electrode.
4 electrodes, 18 is a G5 electrode, 19 is a G6 electrode, and the same components as those of the embodiment shown in FIG. 2 are denoted by the same reference numerals.

In this embodiment, the G3 electrodes 16 and G
A focus voltage is applied to the fifth electrode 18, a low voltage of about 0.5 to 1.0 Kv is applied to the G4 electrode 17, and a high voltage is applied to the G6 electrode 19 and the shield cup 14, respectively.
A main lens is constituted by 4, 16 to 19.
In this case, G3 electrode 16, G4 electrode 17, G5 electrode 18
The front lens is formed in the first half of the
A rear lens is formed in the latter half of the above, the G6 electrode 19, and the shielding cup 14.

The electrode plate 20 arranged in the opening of the G4 electrode 17 in the front lens is provided with three horizontally long slits 21, 22 and 23. By installing these slits 21 to 23, the slits are formed. Each electron beam passing through 21 to 23 is deformed so that the diameter of the cross section becomes laterally long. Further, the rear lens has the same configuration as that of the embodiment shown in FIG. 2, but in the present embodiment, the G5 electrode 18 and the G6 electrode 19 have a configuration arrangement in which they have opposing surfaces. That is, the arrangement is such that the opening of the G6 electrode 19 is inserted and arranged deep inside the opening of the G5 electrode 18 to form the facing surface.

By the way, in the above-described embodiment shown in FIG. 2, the cause of the imbalance in the degree of improvement of the spherical aberration in the horizontal and vertical directions in the main lens is caused by the vertical direction as compared with the horizontal direction. This is due to the small aperture of the lens. Therefore, in this embodiment, in the front lens, the diameter of the electron beam in the cross section in the vertical direction is reduced and the diameter in the horizontal direction is increased, and specifically, the opening of the G4 electrode 17 is formed. Three slits 21, 22, 2 that are long in the horizontal direction are arranged on the electrode plate 20 arranged.
By providing 3, the vertical in the aperture of the main lens,
This is to improve the imbalance in the degree of improvement of spherical aberration in both horizontal directions.

That is, in the present embodiment, the ratio of the vertical and horizontal apertures of the main lens and the ratio of the vertical and horizontal reductions and expansions of the electron beam cross section have a constant relationship. In addition, since the pre-stage lens and the post-stage lens are respectively configured, the spread of the diameter of the cross section of the electron beam based on the imbalance of the degree of improvement of the spherical aberration of the main lens becomes substantially constant in the vertical direction and the horizontal direction, It becomes possible to bring the spot of the electron beam on the fluorescent screen close to a perfect circle. In addition, since the configuration of the rear lens is the same as the configuration of the above-described example shown in FIG. 2 in this example, the same effect as that of the above-described example is exhibited.

In the above description, G4 of the front lens is used.
Three slits 2 of the electrode plate 20 arranged on the electrode 17
Although the example in which the cross-section of the electron beam is deformed by 1, 22, and 23 has been described, the present invention is not limited to the above-described example, and the G3 electrode 16 or the G5 electrode 18 of the front lens is not axially arranged. It is also possible to have a symmetrical shape, where the cross section of the electron beam is deformed as described above.
In addition, the same effect can be obtained even if the cross section of the electron beam is deformed as described above in the portion before the front lens, that is, in the G1 to G3 electrodes that generate the electron beam.

In the above-described embodiment shown in FIG. 4, when the cross section of the electron beam incident on the main lens is deformed so as to be expanded more in the horizontal direction than in the vertical direction, it is compared with the direction vertical to the main lens. In some cases, it may be necessary to add astigmatism to focus the light more strongly in the horizontal direction and cancel the influence of the deformation by the astigmatism. In such a case, when the main lens is constructed, the asperity ratio R shown in FIG. 3 is set to be larger than a certain value (about 1.49), and the astigmatism voltage ΔVf
Should be positive by a predetermined value.

In each of the above embodiments, the picture tube according to the present invention has been described as having the color in-line arrangement electron gun. However, the present invention is not limited to the picture tube including the in-line arrangement electron gun. The same configuration is also applied to a picture tube having an electron gun for generating a single electron beam, such as a picture tube capable of obtaining a monochromatic image or a projection picture tube used for a projection display. The same effect can be obtained.

[0058]

According to the present invention, since the flatness on the G4 electrode 13 side is larger than that on the G3 electrode 12 side, the lens action of making the electron beam in the G4 electrode 13 longitudinally elongated. Becomes stronger, the lens action for making the electron beam in the G3 electrode 12 into a laterally long shape can be canceled, and astigmatism occurring in the main lens can be corrected. Further, since the astigmatism correction partition wall (electrode plate) used in the conventional main lens electrode is omitted, G3
When the electron beam has a horizontally elongated cross section at the electrode 12, a part of the electron beam collides with the astigmatism correction partition wall (electrode plate), causing an undesired current of the G3 electrode 12,
The focus voltage is not lowered. Furthermore, since the electrode support rod 15 supporting the G3 electrode 12 and the G4 electrode 13 is removed from the outer portion of the G3 electrode 12 on which the main lens is formed, the vertical diameter of the main lens can be made conventional. There is an effect that it can be enlarged in comparison.

In addition to this, according to the present invention, means for reducing the diameter of the electron beam in the vertical direction and enlarging the diameter of the electron beam in the horizontal direction is provided in the front lens or before the front lens. There is also an effect that it is possible to correct the imbalance of the divergence in the vertical and horizontal directions of the diameter of the cross section of the electron beam based on the imbalance in the degree of improvement of the spherical aberration in the vertical and horizontal directions.

From these points, the present invention can maximize the diameter of the main lens, suppress the increase of the electron beam spot diameter due to spherical aberration, and improve the resolution of the picture tube. it can.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing an embodiment of a picture tube of the present invention.

FIG. 2 is a cross-sectional view showing an example of the configuration of a main lens electrode used in the picture tube of FIG.

FIG. 3 is a graph showing the relationship between the aspect ratio of the main lens electrode and the astigmatism voltage.

4 is a cross-sectional view showing another embodiment of the configuration of the main lens electrode used in the picture tube of FIG.

FIG. 5 is a sectional view showing an example of the configuration of a conventional color picture tube.

FIG. 6 is a sectional view showing an example of the configuration of a main lens electrode used in a conventional color picture tube.

[Explanation of symbols]

1 Panel Part 2 Funnel Part 3 Neck Part 4 Fluorescent Screen 5 Shadow Mask 6 Shielding Shield 7 Deflection Yoke 8 Purity Adjusting Magnet 9 Center Beam Static Convergence Adjusting Magnet 10 Side Beam Static Convergence Adjusting Magnet 11 Electron Gun 12, 16 G3 Electrode 13, 17 G4 electrode 14 Shielding cup 15 Electrode support rod 18 G5 electrode 19 G6 electrode 20 Electrode plate 21, 22, 23 Slit Bc Center beam Bs Side beam

Claims (4)

[Claims] 1. A first electrode section arranged on a plane and generating a plurality of controlled electron beams, and a plurality of main lens electrodes, wherein a plurality of electron beams from the first electrode section are provided. In a picture tube equipped with an electron gun having a second electrode section for focusing on a phosphor screen, at least a pair of electrodes in the main lens electrode are arranged so as to have opposing surfaces,
The cross-sections of the pair of electrodes are configured to be flat in the same direction, and the astigmatism correction partition wall that separates the plurality of electron beams from each other is present at least on the one plane inside the pair of electrodes. In addition, the cross section of the pair of electrodes includes an electron gun configured such that the degree of flatness of the electrode on the side to which the high voltage is applied is greater than that on the side to which the low voltage is applied. A picture tube characterized by being. 2. A first electrode portion arranged on one plane and generating a plurality of controlled electron beams, and a plurality of main lens electrodes, wherein a plurality of electron beams from the first electrode portion are provided. In a picture tube equipped with an electron gun having a second electrode section for focusing on a phosphor screen, at least a pair of electrodes in the main lens electrode are arranged so as to have opposing surfaces,
The cross-sections of the pair of electrodes are configured to be flat in the same direction, and the astigmatism correction partition wall that separates the plurality of electron beams from each other is present at least on the one plane inside the pair of electrodes. And an electron gun having means for flattening the cross section of the electron beam incident on the pair of electrodes in the same direction as the cross section of the pair of electrodes. .. 3. A first electrode part for generating a controlled single electron beam, and a plurality of main lens electrodes,
In a picture tube equipped with an electron gun having a second electrode section for focusing an electron beam from an electrode section on a fluorescent screen, at least a pair of electrodes in the main lens electrode are arranged so as to have opposite surfaces, and The cross section of the pair of electrodes is configured to be flat in the same direction, and the electron having means for flattening the cross section of the electron beam incident on the pair of electrodes in the same direction as the cross section of the pair of electrodes A picture tube having a gun. 4. The image receiving device according to claim 2, wherein the second electrode portion is provided with an electron gun having means for correcting the degree of flatness of the cross section of the electron beam incident on the pair of electrodes. tube.