JPH07226170A - Electron gun for color cathode ray tube - Google Patents

Abstract

PURPOSE:To enlarge a practical aperture of a main lens, and obtain excellent resolution by forming mutually opposing surfaces respectively in specific shapes in high pressure side and low pressure side cylindrical electrodes constituting the main lens of an electron gun. CONSTITUTION:The inner peripheral edge and the outer peripheral edge constituting a surface opposed to a high pressure side cylindrical electrode 6 on a peripheral wall to form an opening part on the main lens ML side of a low pressure side cylindrical electrode 5, are respectively formed in straight lines 5a to 5d in parallel to the in-line direction and such a shape as the respective tail ends of these straight lines are continued to elliptic arcs 5d and 5f. The inner and outer peripheral edges constituting a surface where the electrode 6 is opposed to the electrode 5, are formed in similar straight lines 6a to 6d and such a shape as the respective tail ends of these straight lines are continued to tube axis center circular arcs 6e and 6f. Thereby, a converging-diverging action of the main lens can be controlled, and since both astigmatism correcting electrode plates 51 and 61 are arranged separately from an opposing part, a substantial aperture of the main lens can be enlarged.

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 color cathode ray tube, and more particularly to an elliptical aperture lens which is obtained by substantially enlarging the aperture of a main lens, so that the spherical aberration of a display image can be further improved. The present invention relates to an electron gun for a color cathode ray tube which is made smaller to further improve the focus characteristic of an electron beam.

[0002]

2. Description of the Related Art A shadow mask type color cathode ray tube is widely used as a display device such as a color television receiver or a monitor of an information terminal.

A color cathode ray tube of this type is a vacuum container in which a face panel (face plate) is connected to a funnel and a neck, a fluorescent screen coated on the inner surface of the face plate, and a face plate close to the fluorescent screen. It has at least a shadow mask suspended inside and an electron gun housed in the neck. For example, three electron beams emitted from the electron gun are color-selected by the shadow mask and impinge on the phosphor. By doing so, the required image is reproduced.

The phosphor constituting the phosphor screen is
Generally, 3 embedded in a black matrix hole having various shapes such as a dot shape, a stripe shape, or a rectangular shape.
The primary color phosphors are applied to the inner surface of the face plate in a predetermined order to form the phosphor screen.

FIG. 5 is a sectional view for explaining the structure of the shadow mask type color cathode ray tube, in which 10 is a face panel, 20 is a neck, 30 is a funnel, 40 is a fluorescent screen, 50 is a shadow mask, and 60 is a mask. Frame, 7
Reference numeral 0 is a magnetic shield, 80 is a suspension spring, 90 is an in-line electron gun, 100 is a deflection yoke, 110 is an external magnetic device for centering and purity adjustment, Bc is a center electron beam, and Bs is a side electron beam.

In the figure, a vacuum envelope is constituted by the face panel 10, the neck 20 and the funnel 30, and the fluorescent surface 40 having the above-mentioned constitution is formed on the inner surface of the face panel 10 constituting the screen. Phosphor screen 4
A shadow mask 50 having electron beam passage holes corresponding to the phosphor array of 0 is arranged in proximity.

The shadow mask 50 is a mask frame 60.
The periphery of the face panel 10 is welded to the pins, and the pins are hung on the inner wall of the skirt portion of the face panel 10 via the suspension spring 80. A magnetic shield 70 that shields the funnel space from external magnetism is attached to the mask frame 60.

The two electron beams Bc and Bs emitted from the in-line electron gun 90 housed in the neck 20 are mounted on the deflection yoke 10 in the vicinity of the funnel-neck transition portion.
It is deflected horizontally and vertically by a generated magnetic field of 0, is subjected to color selection by the shadow mask 50, and is landed on each of the red, green, and blue phosphors forming the phosphor screen 40 to reproduce a desired color image.

In general, in this type of color cathode ray tube, in order to make the reproduced image displayed on the fluorescent screen 40 have high brightness and high resolution, the emission amount of the electron beam projected on the fluorescent screen 40 is increased. It is necessary to reduce the spot diameter of the electron beam on the phosphor screen 40.

As a means for satisfying this, it is known that the diameter of the main lens of the electron gun is enlarged to reduce the spherical aberration of the main lens.

By the way, as described above, an electron gun provided with an electron beam generating means for generating three electron beams corresponding to each color of red (R), green (G), and blue (B), a so-called in-line type. The electron gun is composed of a pair of surrounding electrodes which are spaced apart from each other and whose peripheral portions are arranged to face each other, and three cylinders which are provided at the facing portions of the surrounding electrodes and pass electron beams of three colors respectively. The main lens is composed of the astigmatism correction electrode plate having a circular opening.

In this case, the three apertures provided in the astigmatism correction electrode plate are arranged so as to be linearly aligned corresponding to the linear array of the three electron beams. Therefore, the aperture diameter of the main lens corresponding to the three electron beams is physically limited to 1/3 or less of the inner diameter of the neck in which the electron gun is housed.

As described above, the in-line type electron gun has a problem in that the diameter of the electrode forming the main lens cannot be increased so much that the spherical aberration is naturally limited.

In order to solve this problem, the apertures (electron beam passage apertures) of the astigmatism correction electrode plate corresponding to the above three electron beams are made substantially elliptical, and the minor axes of these elliptical apertures are set. For example, Japanese Patent Laid-Open No. 58-103752 discloses a structure in which the diameter of the main lens is increased by adjusting the in-line arrangement direction of the electron beam. FIG. 6 is an explanatory view of the main part of an in-line type electron gun provided with the above-mentioned astigmatism correction electrode plate having an elliptical aperture, FIG. (B) is a front view of the low-voltage side electrode which comprises the main lens seen from the AA direction of (a), (c) is a high voltage which comprises the main lens seen from the BB direction of (a). It is a front view of a side electrode.

In the figure, 5 is a low-voltage side electrode that constitutes the main lens, 51 is an astigmatism correction electrode plate installed in this low-voltage side electrode, 51R, 51G and 51B are electron beam passage openings, and 6 Is a high voltage side electrode which constitutes the main lens, 61 is an astigmatism correction electrode plate installed in this high voltage side electrode, 6
1R, 61G and 61B are electron beam passage openings.

In addition, Br, Bg, and Bb represent the central axes of the respective electron beams.

The low voltage side electrode 5 constituting the main lens is
As shown in (b), it has an astigmatism correction electrode plate 51 installed inside a cylindrical electrode (surrounding electrode), and its opening is a symmetrical type having a long axis in a direction orthogonal to the in-line arrangement direction. Center electron beam passage opening 51G and an asymmetric side electron beam passage opening 51 having a major axis in a direction orthogonal to the in-line arrangement direction in which the outside is brought close to the inner wall of the surrounding electrode.
R and 51B are formed.

The high voltage side electrode 6 which constitutes the main lens
Has an astigmatism correction electrode plate 61 installed inside a cylindrical surrounding electrode as shown in (c), and its opening has a symmetrical shape having a long axis in a direction orthogonal to the in-line arrangement direction. Center electron beam passage opening 61G and side electron beam passage openings 61R and 61B having an asymmetrical shape having a major axis in a direction orthogonal to the in-line arrangement direction with the inner wall of the surrounding electrode as a part of the opening. Become.

As described above, the electron beam passage opening formed in the astigmatism correction electrode plate is a so-called vertically elongated elliptical shape, and these astigmatism correction electrode plates 51 and 61 form a pair of electrodes 5 constituting the main lens. By setting them so as to recede from each other from the facing portions of 6, the main lens electric field formed between the electrodes 5 and 6 can be introduced into the respective electrodes, and as a result, a large-diameter electron lens can be obtained. .

[0020]

In the above-mentioned conventional technique, the electron beam passage opening provided in the astigmatism correction electrode plate provided in the pair of electrodes forming the main lens is formed into a substantially elliptical shape. It is possible to form a main lens that is substantially larger than the physically possible size in the limited space in the neck.

However, the electron beam passage opening provided in the astigmatism correction electrode plate installed in the pair of electrodes constituting the main lens has a substantially elliptical shape, and the installation position of the astigmatism correction electrode plate is the main lens. Even if the electrode is retracted from the facing position, it is only possible to increase the diameter within a certain range limited by the inner wall of the cylindrical electrode, and there is a limit to increasing the diameter of the main lens.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an electron gun for a color cathode ray tube in which the substantial aperture of the main lens can be further expanded to obtain a good resolution.

[0023]

In order to achieve the above object, the present invention provides an electron beam generating means for generating three electron beams arranged inline on one plane toward a fluorescent screen, and the above 3 In a color cathode ray tube electron gun having at least a main lens for focusing the three electron beams on the phosphor screen, an electrode forming the main lens has a high-voltage side having an opening through which the three electron beams pass. It is composed of a tubular electrode and a low-voltage side tubular electrode that is arranged to face the high-voltage side tubular electrode with a gap, and faces the low-voltage side tubular electrode of the peripheral wall forming the opening of the high-voltage side tubular electrode. The inner peripheral edge and the outer peripheral edge that form the surface are connected to each other by two straight lines parallel to the in-line direction, and the ends of the two straight lines are connected to a pipe axis center arc that curves outward. None, above Two straight lines whose inner peripheral edge and outer peripheral edge forming a surface facing the high voltage side tubular electrode of the peripheral wall forming the opening of the pressure side tubular electrode are parallel to the in-line direction, and these two straight lines Each of the ends has a shape connected by an outwardly curved elliptic arc.

Further, according to the present invention, an electron beam generating means for generating three electron beams arranged inline on one plane toward the fluorescent screen and the three electron beams are focused on the fluorescent screen. In a color cathode ray tube electron gun having at least a main lens, an electrode forming the main lens has a high-voltage side cylindrical electrode having an opening through which the three electron beams pass, and a high-voltage side cylindrical electrode. Low-voltage side cylindrical electrode having openings for passing the three electron beams, which are arranged facing each other with a space therebetween, and the three high-voltage side cylindrical electrodes and the low-voltage side cylindrical electrode, respectively. And an internal electrode plate installed at a position sufficiently retracted from the facing portion of the high-voltage side tubular electrode and the low-voltage side tubular electrode having an electron beam passage hole surrounding the Peripheral and outer peripheral edge among constituting the surface that faces the low-pressure side cylindrical electrode of the peripheral wall forming the mouth portion,
Two straight lines parallel to the in-line direction,
The ends of these two straight lines are connected to each other by the arc of the tube axis that curves outward, and face the high-pressure side tubular electrode of the peripheral wall forming the opening of the low-voltage side tubular electrode. The inner peripheral edge and the outer peripheral edge forming the surface are formed by connecting two straight lines parallel to the in-line direction and the ends of the two straight lines are connected by an elliptic arc curved outward, and It is characterized in that the electron beam passage hole of the electrode plate is formed in a shape having an elliptic arc or a combination of arcs and having a long axis in a direction orthogonal to the in-line direction.

Further, according to the present invention, each of the three electron beams arranged in line is sandwiched from the in-line direction in a part of the focusing electrode arranged in front of the pair of cylindrical electrodes forming the main lens. The vertical correction plate is installed along the tube axis, and the horizontal correction plate is installed along the tube axis so as to sandwich the three electron beams from the direction orthogonal to the vertical correction plate. It is characterized by having an electrostatic quadrupole lens.

The shape of the high-voltage side tubular electrode may be applied to the low-voltage side tubular electrode, or it may be applied only to the low-voltage side tubular electrode.

[0027]

With the above configuration of the present invention, the distribution of the lens electric field entering the opening through which the side electron beam of the high-voltage side cylindrical electrode forming the main lens passes becomes gentle,
That is a substantial increase in diameter.

Further, the astigmatism correction electrode plate installed inside each of the pair of electrodes (high voltage side electrode and low voltage side electrode) forming the main lens is moved back from the corresponding position of both electrodes. The equipotential lines of the main lens electric field formed between both electrodes penetrate into the inside of each of the electrodes, and the diameter of the main lens is substantially expanded.

When the astigmatism correction electrode plate is installed in the main lens electrode, the main lens corresponding to the side electron beam is affected by the inner wall of the cylindrical electrode (outer electrode) to generate the side electron beam. The equivalent aperture of the corresponding main lens is slightly reduced, the equivalent aperture of the main lens corresponding to the side electron beam does not match the equivalent aperture of the main lens corresponding to the center electron beam, and the center electron is focused on the phosphor screen. This causes a difference in the ratio of the focus to the beam and the side electron beam.

In order to eliminate this difference in focus, the equivalent diameter of the main lens corresponding to the center electron beam may be left unchanged and the equivalent diameter of the main lens corresponding to the side electron beam may be expanded. It is physically impossible to make the substantially elliptical aperture of the corresponding astigmatism correction electrode plate larger than the above because it is limited by the inner diameter of the neck tube as described above.

Therefore, as in the configuration of the present invention, the inner peripheral edge and the outer peripheral edge of the peripheral wall forming the opening of the high-voltage side tubular electrode facing the low-voltage side tubular electrode are respectively in the in-line direction. With the two straight lines parallel to each other and the ends of these two straight lines being connected by the arc of the tube axis center that curves outward, the equivalent diameter of the main lens corresponding to the side electron beam is Expanded.

As a result, the equivalent aperture of the main lens corresponding to the side electron beam and the equivalent aperture of the main lens corresponding to the center electron beam match, and the center electron beam and the side electron beam focused on the fluorescent screen are focused. The color cathode ray tube having a good resolution can be obtained.

[0033]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a structural view of an essential part for explaining one embodiment of an electron gun for a color cathode ray tube according to the present invention, in which (a) is a sectional view taken along the tube axis of a low voltage side tubular electrode, (b). ) Is a front view seen from the main lens ML of FIG.
(C) is a cross-sectional view along the tube axis of the high-voltage side tubular electrode,
(D) is a front view seen from the main lens ML of (c) in the arrow direction. In the figure, 5 is a low-voltage side tubular electrode (low-voltage side surrounding electrode) that constitutes the main lens, 51 is an astigmatism correction electrode plate installed inside the low-voltage side tubular electrode, and 6 is the main lens. The high-voltage side tubular electrode (high-voltage side surrounding electrode) 61 constituting the above is a reference numeral 61 is an astigmatism correction electrode plate installed inside the high-voltage side tubular electrode.

As shown in (a) and (b), an astigmatism correction electrode plate 51 is installed inside the low voltage side tubular electrode 5 at a position away from the main lens ML. With this astigmatism correction electrode plate 51, a center electron beam passage opening 51G having a substantially elliptical shape whose major axis is orthogonal to the in-line direction is formed.
And the astigmatism correction electrode plate 51 and the low-voltage side cylindrical electrode 5
Side electron beam passage opening 51 composed of the inner wall of the
r and 51b are formed inside the low-voltage side tubular electrode 5.

The surface of the peripheral wall (race track) forming the opening on the main lens ML side of the low-voltage side tubular electrode (low-voltage side surrounding electrode) 5 is opposed to the high-voltage side tubular electrode 6. Two straight lines 5a and 5b whose inner and outer peripheral edges are parallel to the in-line direction, and an elliptic arc 5e in which the respective ends of the two straight lines 5a and 5b are curved outward.
It is formed in a shape connected by 5f.

That is, the elliptic arcs forming the inner peripheral edge and the outer peripheral edge of the low-voltage side tubular electrode 5 are arranged in an inline arrangement.
The distance from the line connecting the centers of the individual electron beam passage openings to the straight line 5a forming the inner peripheral edge is l ₁ , the distance to the straight line 5c forming the outer peripheral edge is l ₂ , and the major axis of the elliptic arc 5e to the elliptic arc 5e. When the distance to is assumed to be l ₅ , the inner elliptic arc ・ ・ ・ (X ² / l ₄ ) + (Y ² / l ₁ ) = 1 outer elliptic arc ・ ・ ・ (Y ² / l ₅ ) + ( Y ² / l ₅ ) = 1.

Further, the peripheral wall (race track) of the high-voltage side cylindrical electrode (high-voltage side surrounding electrode) 6 forming the opening on the side of the main lens ML constitutes a surface facing the low-voltage side cylindrical electrode 5. Two straight lines 6a and 6b whose inner peripheral edge and outer peripheral edge are parallel to the in-line direction, and these two straight lines 6 respectively.
Pipe axis center arc 6e in which the respective ends of a and 6b are curved outward,
It is formed in a shape connected with 6f.

That is, the inner arc 6e connecting the ends of the two straight lines 6a, 6b has a radius R ₁ centered on the center of the center electron beam passage opening 61G, and the two straight lines 6c,
The outer arc 6f connecting the ends of 6d has a radius R ₂ centered on the center of the center electron beam passage opening 61G.

As described above, by making the opening shapes of the facing portions of the pair of main lens constituent electrodes in which the astigmatism correction electrode plates forming the substantially elliptical electron beam passage opening are different, It is possible to control the convergence and divergence actions of the main lens ML.

That is, the elliptical aperture corresponding to the side electron beam formed by the astigmatism correction electrode plate is less affected by the inner wall of the cylindrical electrode, that is, the surrounding electrode, and the elliptical aperture corresponding to the side electron beam is formed. The equivalent aperture of the lens and the equivalent aperture of the lens formed by the elliptical aperture corresponding to the center electron beam match, and the side electron beam focused on the phosphor screen and the focus ratio of the center electron beam match.

Further, since the astigmatism correction electrode plate installed inside the pair of cylindrical electrodes forming the main lens is installed at a position sufficiently separated from the facing portion of the pair of cylindrical electrodes, The equipotential line (electric field) formed in the lens ML portion deeply penetrates into the inside of each tubular electrode, and the substantial aperture of the main lens is enlarged.

FIG. 2 is a schematic cross-sectional view taken along the tube axis for explaining an example of the overall structure of the electron gun for a color cathode ray tube according to the present invention, in which 1 is a first electrode, 2 is a second electrode, and 3 is a third electrode. Electrodes, 4 is a 4th electrode, 5 is a 5th electrode, 51 is an astigmatism correction electrode plate installed in the 5th electrode, 6 is a 6th electrode, 61 is an astigmatism correction electrode installed in the 6th electrode A plate, 7 is a shield cup, and 8R, 8G, and 8B are cathodes.

In the figure, cathodes 8R, 8G, 8B
The first electrode 1 and the second electrode 2 form an electron beam generating means, and the third electrode 6 to the sixth electrode 6 form a focusing and accelerating lens. The fifth electrode (low voltage side electrode) 5
And the sixth lens (high-voltage side electrode) 6 facing each other, the main lens ML.
Is formed.

The astigmatism correction electrode plates 51 and 61 installed inside the fifth electrode 5 and the sixth electrode 6 are the main lens ML.
The fifth electrode 6 and the sixth electrode 6 are formed at a position largely retracted in a direction away from each other.

The opposite edges of the fifth electrode 5 and the sixth electrode 6 are provided with the shape described with reference to FIG. As a result, the above-described substantial enlargement of the aperture of the main lens ML and the matching of the focus conditions are achieved, and the resolution of the cathode-ray tube using this electron gun can be greatly improved.

FIG. 3 is a schematic sectional view taken along the tube axis for explaining another example of the entire structure of the electron gun for color cathode ray tubes according to the present invention, and FIG. 4 is a perspective view showing the electrode structure of the electrostatic quadrupole in FIG. It is a figure and the same code as FIG. 2 respond | corresponds to the same part,
41 and 42 are multi-divided focusing electrodes, 41a is a vertical correction plate, and 42a is a horizontal correction plate.

In FIG. 3, a main lens is formed at the portion where the fifth electrode 5 and the sixth electrode 6 face each other, the fifth electrode 5 is a low voltage side electrode, and the sixth electrode 6 is a high voltage side electrode. Astigmatism correction electrode plates 51 and 61 are installed inside the fifth electrode 5 and the sixth electrode 6 forming the main lens, respectively.
The peripheral edge facing the fifth electrode 5 is provided with the structure described with reference to FIG.

In this electron gun, the focusing electrodes 41 and 4 are
An electrostatic quadrupole lens for correcting the field curvature is formed at the opposing portion of 2. This electrostatic quadrupole lens is shown in FIG.
As shown in (a), the vertical correction plate 41a provided on the sixth electrode 6 side of the fifth electrode 5 and the fifth electrode 5 side of the sixth electrode 6 as shown in FIG. And a horizontal correction plate 42a provided on the.

The vertical correction plate 41a is composed of a pair of substantially rectangular plate members installed so as to sandwich the electron beam passage opening of the fifth electrode 5 from the vertical direction, and the horizontal correction plate 42a is formed of the sixth electrode 6. It is composed of a plurality of substantially rectangular plate bodies installed so as to sandwich each of the electron beam passage openings from the horizontal direction.

These vertical correction plate 41a and horizontal correction plate 4
2a are combined with each other to form an electrostatic quadrupole, as shown in FIG.

Then, a fixed focus voltage Vf ₁ is applied to the third electrode 3 and the electrode 42, and a fixed voltage Vf ₂ is applied to the electrode 42 and the fifth electrode 5 as an alternating voltage dVf which varies in synchronization with the deflection amount of the electron beam. Apply.

With the above structure, the cross-sectional shape of the electron beam at the time of focusing can be controlled, and the astigmatism described in the above embodiment can be corrected to obtain a color cathode ray tube with higher resolution.

The installation position of the electrostatic quadrupole is not limited to the above-mentioned position, but the focusing electrode system can be divided into a plurality of parts and installed at any position.

[0055]

As described above, according to the present invention,
Formed by an astigmatism correction electrode plate by changing the opening shape of the facing part of the pair of main lens constituent electrodes inside which an astigmatism correction electrode plate that forms an approximately elliptical electron beam passage is installed The elliptical aperture corresponding to the side electron beam is less affected by the inner wall of the cylindrical electrode, that is, the outer electrode, and the elliptical aperture corresponding to the side electron beam and the ellipse corresponding to the center electron beam are used. The equivalent aperture of the lens due to the aperture matches, and the focusing ratios of the side electron beam and the center electron beam focused on the phosphor screen match.

Further, since the astigmatism correction electrode plate installed inside the pair of cylindrical electrodes forming the main lens is installed at a position sufficiently separated from the facing portion of the pair of cylindrical electrodes, The equipotential line (electric field) formed in the lens ML portion deeply penetrates into the inside of each tubular electrode, and the substantial aperture of the main lens is enlarged.

As a result, it is possible to provide an electron gun for a color cathode ray tube capable of displaying a high resolution image.

[Brief description of drawings]

FIG. 1 is a main part structural view for explaining an embodiment of an electron gun for a color cathode ray tube according to the present invention.

FIG. 2 is a schematic cross-sectional view taken along the tube axis for explaining an example of the overall configuration of the electron gun for a color cathode ray tube according to the present invention.

FIG. 3 is a schematic sectional view along the tube axis for explaining another example of the overall configuration of the electron gun for a color cathode ray tube according to the present invention.

FIG. 4 is a perspective view showing an electrode configuration of the electrostatic quadrupole in FIG.

FIG. 5 is a sectional view illustrating the structure of a shadow mask type color cathode ray tube.

FIG. 6 is a principal part explanatory view of an in-line type electron gun provided with an astigmatism correction electrode plate having an elliptical aperture.

[Explanation of symbols]

 1 1st electrode 2 2nd electrode 3 3rd electrode 4 4th electrode 5 5th electrode 51 Astigmatism correction electrode plate installed in the 5th electrode 6 6th electrode 61 Astigmatism correction installed in the 6th electrode Electrode plate 7 Shield cup 8R, 8G, 8B Cathode.

Claims (3)

[Claims] 1. An electron beam generating means for generating three electron beams, which are arranged in-line on a plane toward a fluorescent screen, and a main lens for focusing the three electron beams on the fluorescent screen. In an electron gun for a color cathode ray tube having at least the above, an electrode forming the main lens is opposed to a high-voltage side tubular electrode having an opening through which the three electron beams pass, with a gap from the high-voltage side tubular electrode. An inner peripheral edge and an outer peripheral edge that form a surface facing the low-voltage side tubular electrode of the peripheral wall forming the opening of the high-voltage side tubular electrode, respectively. And two end lines of the two straight lines are connected to each other by a tube axis center circular arc that curves outward, and the peripheral wall of the peripheral wall forming the opening of the low voltage side tubular electrode is formed. The high-pressure side cylinder An inner peripheral edge and an outer peripheral edge that form a surface facing the electrode have a shape in which two straight lines parallel to the in-line direction and respective ends of the two straight lines are connected by an elliptic arc curved outward. An electron gun for a color cathode ray tube, which is characterized in that 2. An electron beam generating means for generating three electron beams arranged in-line on a plane toward the fluorescent screen and a main lens for focusing the three electron beams on the fluorescent screen. In an electron gun for a color cathode ray tube having at least the above, an electrode forming the main lens is opposed to a high-voltage side tubular electrode having an opening through which the three electron beams pass, with a gap from the high-voltage side tubular electrode. Placed 3
A low-voltage side cylindrical electrode having an opening for passing three electron beams, and an electron beam passage hole surrounding each of the three electron beams inside the high-voltage side cylindrical electrode and the low-voltage side cylindrical electrode. And the internal electrode plate installed at a position sufficiently retracted from the facing portion of the high-voltage side tubular electrode and the low-voltage side tubular electrode, and the low-voltage side of the peripheral wall forming the opening of the high-voltage side tubular electrode. The inner peripheral edge and the outer peripheral edge that form the surface facing the cylindrical electrode are composed of two straight lines parallel to the in-line direction, and a tube axis center arc in which the ends of the two straight lines curve outward. Two inner peripheral edges and outer peripheral edges of the peripheral wall forming the opening of the low-voltage side tubular electrode facing the high-voltage side tubular electrode are parallel to the in-line direction. Straight line and these two A shape in which each end of the wire is connected by an elliptic arc that curves outward, and the electron beam passage hole of the internal electrode plate has an elliptic arc or a combination of arcs and has a long axis in a direction orthogonal to the in-line direction. An electron gun for a color cathode ray tube characterized in that 3. The focusing electrode according to claim 1 or 2, wherein the focusing electrode arranged in front of the pair of cylindrical electrodes constituting the main lens is divided into a plurality of electrodes, and at least one of the plurality of divided electrodes is formed. Secondly, an electron gun for a color cathode ray tube comprising an electron lens for applying a voltage which fluctuates in synchronization with the deflection of the electron beam and changing the cross-sectional shape of the electron beam in accordance with the change in the deflection amount. .