JPH05303944A - Focusing of plural electron beam and electron gun for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To set resolution between multiple electron guns of different electron beam quantities uniform. CONSTITUTION:Lens action of an electron lens 21L1 at an aperture part 21 corresponding to an electron beam of which average electron beam quantity outgoing from a cathode is the smallest among aperture parts corresponding to plural electron beams of an acceleration electrode 20 is set to be stronger than the lens action of the electron lenses at the apertures corresponding to the other electron beams. Focusing for all the multiple electron guns of different electron beam quantities is thus improved, thereby a favorable resolution can be provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiple electron beam electron gun, and more particularly to a multiple electron beam cathode ray tube such as a color television picture tube or a color display tube in which the resolution is improved over the entire phosphor screen. The present invention relates to a focusing system and an electron gun for a color cathode ray tube.

[0002]

2. Description of the Related Art A color television picture tube or a color display tube modulates each of a plurality of electron beams with color information and concentrates this on a phosphor screen made of a phosphor having a plurality of emission characteristics to obtain a desired color. Get to the display. FIG. 8 is a schematic cross-sectional view for explaining the schematic structure of the color cathode ray tube, in which 81 is a panel portion forming a face plate, 82 is a funnel portion, 83 is a neck portion, 84 is an electron gun, and 85 is a deflection yoke. , 86 is a fluorescent screen formed on the inner surface of the panel portion, 87 is a mask frame,
Reference numeral 88 is a shadow mask fixed to the mask frame.

This type of color cathode ray tube has a panel portion 81.
A vacuum container is constituted by the neck portion 83 connected to the side wall portion of the panel portion via the funnel 82. And
An electron gun 84 that emits a plurality of electron beams is installed in the neck portion 83, and a plurality of electron beams emitted from the electron gun 84 are horizontally and vertically aligned by a deflection yoke 85 mounted on the outer wall of the funnel portion 82 to the neck portion 83. A two-dimensional image is formed on the fluorescent screen 86 by deflecting and scanning.

The shadow mask 88 has a large number of apertures and is fixed to a mask frame 87 suspended on the inner wall of the panel portion 81 at a predetermined position on the peripheral edge thereof, so that each of a plurality of electron beams from the electron gun is given a predetermined aperture. It is a color selection electrode which is made to impinge on a predetermined phosphor via the electrode. The inner wall of the funnel portion 82 has a conductive film uniformly applied to a part of the neck portion 83, and the outer surface of the funnel portion 82 has an exterior conductive film and an anode terminal.

On the phosphor screen 86, phosphors of a plurality of colors, for example, phosphors of three colors of red, green and blue are applied in stripes or dots, and a plurality of phosphors, for example, 3 emitted from the electron gun are used. The electron beams R, G, B of the book are selected by the apertures formed in the shadow mask 88 and impinge on the corresponding phosphors, and the phosphors emit light to emit light of a predetermined color tone to the face of the panel portion 81. Radiates to the outer surface of the plate. In the following description, the number of electron beams is three.

FIG. 9 is a schematic cross-sectional view showing a structural example of a main part of a multiple electron beam electron gun used for a color cathode ray tube, wherein K ₁ , K ₂ and K ₃ are hot cathodes (hereinafter referred to as cathodes),
10 is a control electrode, 20 is an acceleration electrode, 30 is a focusing electrode, 4
0 indicates an anode electrode (hereinafter referred to as an anode). Also, 1
1, 12, 13 are electron beam passage openings formed in the control electrode 10, 21, 22, 23 are electron beam passage openings formed in the acceleration electrode 20, and 31, 32, 33 and 34, 35, 3
Reference numeral 6 denotes an anode side electron beam passage opening and an acceleration electrode side electron beam passage opening formed in the focusing electrode 30.
Indicates an electron beam passage opening formed on the focusing electrode side of the anode 40.

This type of electron gun generates three parallel electron beams in a horizontal horizontal line arrangement, that is, in-line arrangement, and cathodes K ₁ and K _{2 of} an electron beam generator for accelerating and controlling the electron beams. , K ₃ and a prefocus lens unit for controlling the electron beam and a main lens unit for focusing the electron beam on the fluorescent screen. The three electron beams are
The deflection yoke 85 deflects and scans the entire phosphor screen horizontally and vertically to form a two-dimensional raster.

FIG. 10 is an explanatory view of the distribution pattern of the deflection magnetic field generated by the deflection yoke, in which 60 is a horizontal deflection magnetic field, 61 is a vertical deflection magnetic field, and 62 is an electron beam which is deflected. As shown in the figure, the deflection magnetic field of the deflection yoke 85 has a pincushion-like distortion 60 in the horizontal direction (XX) and a barrel-like distortion 61 in the vertical direction (YY).

FIG. 11 is a schematic diagram for explaining how the deflection magnetic field acts on the electron beam. The electron beam 62 deflected and scanned around the phosphor screen is the electron indicated by the arrow 63 in FIG. In addition to the action of deflecting the beam, the electron beam on the fluorescent screen is distorted due to the horizontal diverging action 64 and the vertical focusing action 65 as shown by arrows 64 and 65 in FIG. This will form an elliptical spot.

FIG. 12 is a schematic explanatory view of the electron beam spot shape on the phosphor screen generated by the above-mentioned distortion of the deflection magnetic field. 66 is a raster formed on the phosphor screen 86,
62C indicates a core portion of the electron beam spot, and 62H indicates a halo portion thereof. As shown in the figure, the electron beam spot 00 generated in the central portion of the phosphor screen is circular, whereas the electron beam spot generated in the peripheral portion has a high brightness core portion 62C and a low brightness. The non-circular shape including the halo portion 62H has a distortion. In particular, the halo portion 62
The large elongation of H in the vertical direction (Y-Y) adversely affects the focus characteristics.

In order to prevent the deterioration of the focus characteristic, conventionally, the main lens is provided with a distorted lens structure in which the electron beam is vertically elongated, or the uniformity of the focus and the high resolution are provided over the entire surface of the fluorescent screen. Therefore, a means such as optimizing the electron beam diameter in the main lens by a prefocus system has been adopted. As a disclosure of this type of conventional technique, for example, Japanese Patent Laid-Open No. 57-36707 can be cited.

[0012]

When the red, green, and blue phosphors are irradiated with electron beams emitted from the cathodes of the three electron guns to emit white light, the electrons emitted from the electron guns are emitted. The beam amount is different. In particular, in products such as color display tubes that use a small amount of current, the difference in the amount of electron beam that must be applied to the red, green, and blue phosphors is large. This depends on the type of phosphor and the color tone of the white light to be displayed, but the relationship among the electron beam amounts of red, green, and blue, that is, the electron beam current amounts R, G, and B is: R≈G> B, R <G >> B,
There is a relation of R>G> B, and the electron beam amount B of the blue phosphor is the smallest. That is, the average electron beam amount is smaller for the blue phosphor than for the other phosphors.

FIG. 13 is a schematic diagram for explaining the state of the electron beam trajectory depending on the amount of the electron beam. When the electron beam emitted from the cathode K passes through the control electrode 10 and the acceleration electrode 20, the amount of the electron beam is increased. Thus, the crossover point P at which the cross-sectional diameter of the electron beam becomes the smallest is at the position P ₁ when the electron beam amount is small, and at the position P ₂ when the electron beam amount is large. Then, due to the difference in the crossover points, the angle at which the electron beam is incident on the main lens ML formed by the focusing electrode 30 and the anode 40 is different,
The virtual object point I viewed from the main lens ML is located at the position I ₁ when the electron beam amount is small, and at the position I ₂ when the electron beam amount is large.

That is, during the operation of the color cathode ray tube, the focus voltage applied to the focusing electrode 30 is usually fixed and used, the lens magnification of the main lens ML is constant, and it depends on the amount of the electron beam. Since the virtual object points are different, the image point distance from the main lens ML is the position I _{1 with a} small amount of electron beams and the position I _{2 with} a large amount of electron beams.
There was a problem that the resolution was deteriorated due to the difference in lens magnification = focus voltage depending on the electron beam amount.

Conventionally, the focus voltage is set to the middle of the just focus of the three electron guns or to the electron gun having the largest current, and the other electron guns are set to the focus voltage deviated from the just focus voltage. ,
The focus characteristics of the electron gun, which has the smallest amount of current, are sacrificed. An object of the present invention is to solve the above-mentioned problems of the prior art, improve the focus of all multi-electron guns having different electron beam amounts, and obtain good resolution, and a multiple electron beam focusing system and an electron gun for a color cathode ray tube. To provide.

[0016]

In order to achieve the above object, the present invention is directed to a plurality of cathodes for emitting a plurality of electron beams arranged in a row and a plurality of cathodes facing each other. At least a control electrode having a plurality of openings arranged in a horizontal row, an acceleration electrode, a focusing electrode, and an anode are provided, and a plurality of a plurality of electron beams for concentrating the plurality of electron beams on the phosphor screen are provided between the electrodes. In the multiple electron beam focusing method of an electron gun having an electron lens, the lens action of the electron lens of the opening corresponding to the electron beam having the smallest average electron beam amount emitted from the cathode among the plurality of openings of the accelerating electrode. Is characterized by adopting an electron beam focusing method which is stronger than the lens action of the electron lens in the opening corresponding to another electron beam.

Then, in a three-electron gun having three electron beams, three cathodes emitting three electron beams arranged in one horizontal line and one horizontal line facing each of the three cathodes are arranged. At least a control electrode having three apertures arranged, an acceleration electrode, a focusing electrode, and an anode, and three electrons for concentrating the three electron beams on the phosphor screen between the electrodes, respectively. In an electron gun for a color cathode ray tube having an electron gun having a lens, among the three openings of the accelerating electrode, an electrode in the tube axis direction of the opening corresponding to the electron beam having the smallest average electron beam amount emitted from the cathode. It is characterized in that the length is made longer than other openings.

Further, according to the present invention, among the three openings of the accelerating electrode, the opening diameter of the opening corresponding to the electron beam having the smallest average electron beam emitted from the cathode is changed to the opening diameter of the other opening. It is characterized by being made smaller. further,
The present invention is characterized in that a slit concave portion having a long axis in the arrangement direction of the three electron beams is formed in the focusing electrode side opening of the accelerating electrode, and among the three accelerating electrode openings, The width of the concave portion of the opening corresponding to the electron beam having the smallest average electron beam amount emitted from the cathode in the short axis direction is made narrower than the width of the other openings in the short axis direction.

Needless to say, the present invention is not limited to the type in which three electron guns are arranged in one direction, but can be applied to a so-called delta-arranged three electron gun.

[0020]

[Function] By making the lens strength of the accelerating electrode of an electron gun having a small average electron beam amount stronger than the lens strength of the accelerating electrodes of other electron guns, the bundle of electron beams incident on the accelerating electrode from the cathode is The diameter of the electron beam incident on the main lens can be reduced by receiving a stronger focus than the electron beam emitted from the electron gun.

Therefore, when the electron beam is deflected and scanned over the entire phosphor screen, the influence of the deflection magnetic field is reduced, and uniform focus characteristics can be obtained over the entire phosphor screen.
Further, by narrowing the diameter of the electron beam, the depth of focus on the phosphor screen becomes deeper, and even if the just focus point is displaced from other electron guns, the influence of focus deterioration is small.

When the diameter of the electron beam in the main lens is reduced, the effect of space charge increases and the diameter of the beam spot on the phosphor screen increases, but the electron beam amount is larger than that of other electron guns. Therefore, the deterioration of resolution is not significantly affected.

[0023]

Embodiments of the present invention will now be described in detail with reference to the drawings. FIG. 1 is a schematic diagram for explaining the first embodiment of the present invention, in which K _1, K _{2, and} K ₃ are cathodes, 10 is a control electrode, 20 is an accelerating electrode, 30 is a focusing electrode, 40 is an anode,
1, 12 and 13 are openings 21, 22 and 22 of the control electrode 10.
23 is the opening of the accelerating electrode 20, 31, 32, 33 is the anode side opening of the focusing electrode 30, 34, 35, 36 are the accelerating electrode side openings of the focusing electrode 30, and 41, 42, 43 are the anodes 40.
11L ₁ , 11L ₂ , 11L ₃ are control electrodes 1
An electronic lens having openings 0, 12, 13 of 0, 21L ₁ ,
21L ₂ and 21L ₃ are openings 21 and 2 of the acceleration electrode 20.
₂ , 23 electronic lenses, 31L ₁ , 31L ₂ , 31L ₃
Is an electron lens of the openings 31, 32, 33 of the focusing electrode 30, 34L ₁ , 35L ₂ , 36L ₃ is an electron lens of the openings 34, 35, 36 of the focusing electrode 30, 41L ₁ , 42L
₂ , 43L ₃ are electron lenses formed by the openings 41, 42, 34 of the anode 40.

Here, it is assumed that the electron beam amount of the electron beam B ₁ is smaller on average than the electron beam amounts of the other electron beams B _{2 and} B ₃ . Then, the lens 2 formed by the opening 21 of the acceleration electrode 20 corresponding to the electron beam B ₁
The lens action of 1L ₁ is set stronger than the lens actions of the lenses 21L _{2 and} 21L ₃ formed by the openings 22 and 23 of the acceleration electrode 20 corresponding to the other electron beams B _{2 and} B ₃ .

In the figure, a plurality of electron beams B _1, B _{2 and} B ₃ emitted from cathodes K _1, K _{2 and} K _{3 are} emitted from control electrode 10, acceleration electrode 20, focusing electrode 30 and anode 40, respectively. Each opening 11, 12, 13, 21, 22, 23, 34, 3
5, 36, 31, 32, 33, and 41, 42, 43
Electron lenses 11L ₁ , 11L ₂ , 1 formed by
1L ₃ , 21L ₁ , 21L ₂ , 21L ₃ , 34L ₁ , 3
5L ₂ , 36L ₃ , 31L ₁ , 31L ₂ , 31L ₃ , 4
It is deflected in the deflection magnetic field through 1L ₁ , 42L ₂ and 43L ₃ to reach the phosphor screen.

At this time, the electron beam B ₁ is emitted from the electron lens 2
When passing 1 L ₁ , the electron beams B _{2 and} B ₃ emitted from other electron guns are more strongly focused and the diameter of the electron beam incident on the main lens becomes smaller. Therefore, when the electron beam is deflected and scanned over the entire phosphor screen, the influence of the deflection magnetic field due to the amount of the electron beam is reduced, and uniform focus characteristics can be obtained over the entire phosphor screen, and the resolution is improved. It

FIG. 2 is a constitutional view for explaining the second embodiment of the present invention. (A) is a front view of the main part of the acceleration electrode 20 on the focusing electrode side, (b) is a sectional view taken along the line A--A of (a). And the opening 2
The electron beam quantity of the electron beam passing through 1 is
It is assumed that the electron beam amount passing through 23 is smaller than the electron beam amount on average. In addition, X represents a horizontal direction (electron gun arrangement direction), Y represents a vertical direction, and Z represents a tube axis direction. The electron beam passing through the opening 21 is a blue electron beam having the smallest electron beam amount, and the electron beams passing through the other openings 22 and 23 are green electron beams (or red electron beams).

In the figure, the accelerating electrode 20 has openings 21, 22, 23 arranged in a line in the horizontal direction and concave portions 211, 212, 213 formed around these openings, and The electrode lengths l _1, l _2, l ₃ of the tubes 21, 22, 23 in the tube axis (Z) direction are set to l ₁ > l ₂ = l ₃ .
FIG. 3 is a schematic diagram for explaining the focusing state of the electron beam at the main lens position according to the configuration of the second embodiment of the present invention. The ↑ side of the line BB is the upper half of the blue electron gun, and the ↓ side is the green side. The lower half of the electron gun (or red electron gun) is shown.

The electron beam of the blue electron gun has an electron beam passage opening 21 of the accelerating electrode 20 whose length l ₁ in the tube axis direction is another electron beam. Is longer than the tube axial lengths l _{2 and} l ₃ . For this reason, the strength of the electrostatic lens, that is, the lens action becomes stronger than that of the acceleration electrodes of the electron guns of the green electron beam and the red electron beam.

Therefore, the blue electron beam is strongly focused, and the electron beam diameter R ₀ in the main lens ML is smaller than the electron beam diameters R of the green electron beam and the red electron beam (R ₀ <R ₁ ). Therefore, the beam diameter of the blue electron beam entering the deflection magnetic field becomes small, and the influence of the deflection magnetic field can be reduced compared with the beam diameters of the green electron gun and the red electron gun.

Therefore, when the electron beam is deflected and scanned over the entire phosphor screen, the influence of the deflection magnetic field due to the amount of the electron beam is reduced, and uniform focus characteristics can be obtained over the entire phosphor screen. 4A and 4B are configuration diagrams illustrating a third embodiment of the present invention, in which FIG. 4A is a front view of a main portion of the acceleration electrode 20 on the focusing electrode side, and FIG. 4B is a sectional view taken along line AA of FIG. It is assumed that the electron beam amount of the electron beam passing through the opening 21 is, on average, smaller than the electron beam amount of the electron beam passing through the other openings 22 and 23, as in the above embodiment.

In the figure, the accelerating electrode 20 has openings 21, 22, 23 arranged in a line in the horizontal direction and recesses 211, 212, 213 formed around each of the openings. The apertures 21 of the accelerating electrode 20 corresponding to the beam, the apertures 22 of the accelerating electrode 20 corresponding to the green electron beam, and the apertures 23 of the accelerating electrode 20 corresponding to the red electron beam, d _1, d _2, d ₃ Is set to d ₁ <d ₂ = d ₃ .

FIG. 5 is a schematic diagram for explaining the focusing state of the electron beam at the main lens position according to the configuration of the third embodiment of the present invention. The ↑ side of the line BB is the upper half of the blue electron gun.
The ↓ side shows the lower half of the green electron gun (or red electron gun). The electron beam of the blue electron gun has an electron beam passage opening 21 of the accelerating electrode 20 having an aperture diameter d ₁ of another electron beam, that is, a green electron beam and a red electron beam.
It is smaller than the opening diameters d _{2 and} d _{3 of 2 and} 23. Therefore, the strength of the electrostatic lens, that is, the lens action is stronger than that of the acceleration electrodes of the electron guns of the green electron beam and the red electron beam.

Therefore, the blue electron beam is strongly focused, and the electron beam diameter R ₀ in the main lens ML becomes smaller than the electron beam diameters R of the green electron beam and the red electron beam (R ₀ <R ₁ ). Therefore, the beam diameter of the blue electron beam entering the deflection magnetic field becomes small, and the influence of the deflection magnetic field can be reduced compared with the beam diameters of the green electron gun and the red electron gun.

For this reason, when the electron beam is deflected and scanned over the entire phosphor screen, the influence of the deflection magnetic field due to the amount of the electron beam is reduced, and uniform focus characteristics can be obtained over the entire phosphor screen. 6A and 6B are configuration diagrams illustrating a fourth embodiment of the present invention. FIG. 6A is a front view of a main part of the acceleration electrode 20 on the focusing electrode side, and FIG. 6B is a sectional view taken along line AA of FIG. An example in which the accelerating electrode 20 is provided with a non-axisymmetric lens system (quadrupole lens) will be described.

In this embodiment, a vertically narrow rectangular slit 25 having a long axis in the horizontal direction is formed around the electron beams 21, 22, 23 on the side of the focusing electrode 30 of the accelerating electrode 20.
26 and 27 are provided. The slit may be an ellipse having a major axis in the horizontal direction. In the figure, when the horizontal width of each slit 25, 26, 27 is H and the vertical width is w _1, w _2, w ₃ , the vertical widths w _1, w _2, w ₃ are w ₁
<W ₂ = w ₃ is set.

The electron beam amount of the blue electron beam passing through the opening 21 of the accelerating electrode 20 is on average smaller than the electron beam amounts of the green electron beam and the red electron beam passing through the other openings 22 and 23. The electron beam passing through the opening 21 is a blue electron beam having the smallest electron beam amount,
The electron beam passing through the other openings 22 and 23 is a green electron beam (or a red electron beam).

FIG. 7 is a schematic diagram for explaining the focusing state of the electron beam at the main lens position according to the configuration of the fourth embodiment of the present invention. The ↑ side of line BB is the upper half of the blue electron gun.
The ↓ side shows the lower half of the green electron gun (or red electron gun). In the electron beam of the blue electron gun, the slit 25 of the electron beam passage opening 21 of the accelerating electrode 20 has a vertical width w _{1 which} is another electron beam. It is narrower than the vertical widths w _{2 and} w _{3 of} 26 and 27. Therefore, the strength of the electrostatic lens in the vertical direction, that is, the lens action is stronger than that of the acceleration electrodes of the electron guns of the green electron beam and the red electron beam.

Therefore, the blue electron beam is strongly focused, and the electron beam diameter R ₀ in the main lens ML becomes smaller than the electron beam diameters R of the green electron beam and the red electron beam (R ₀ <R ₁ ). The beam diameter of the blue electron beam entering the deflection magnetic field becomes smaller, and the influence of the vertical focusing effect of the deflection magnetic field can be reduced compared to the beam diameters of the green electron gun and the red electron gun. The halo component of the blue electron beam in the vertical direction can be reduced as compared with the green electron beam and the red electron beam.

Therefore, when the electron beam is deflected and scanned over the entire phosphor screen, the influence of the deflection magnetic field due to the amount of the electron beam is reduced, and uniform focus characteristics can be obtained over the entire phosphor screen. In the above-mentioned second and third embodiments, the explanation has been made assuming that the concave portions 211, 212, 213 are provided around the electron beam passage opening of the acceleration electrode, but the present invention is not limited to such a structure. However, the present invention can be applied to an electron gun having an electrode having a structure not having the above-mentioned recessed portion, and can be applied to an electron gun other than the above-described electrode array type electron gun.

When the color cathode ray tube equipped with the above-mentioned electron gun is operated, the applied voltage applied to each electrode constituting the electron gun is 50 to 170 V on the cathodes K _1, K _{2 and} K ₃ , and the control electrode 10. Is 0 V, the acceleration electrode 20 is 400 to 800 V, the focusing electrode 30 is 5 to 8 kV, and the anode electrode is 25 to 30 kV.

[0042]

As described above, according to the present invention,
By making the lens strength of the accelerating electrode of an electron gun with an average small amount of electron beams stronger than the lens strength of the accelerating electrodes of other electron guns, the bundle of electron beams entering the accelerating electrode from the cathode is It receives a stronger focus than the emitted electron beam and can reduce the diameter of the electron beam incident on the main lens, which reduces the influence of the deflection magnetic field when the electron beam is deflected and scanned over the entire fluorescent screen, In, it is possible to obtain a uniform focus characteristic of the front electron beam.

Further, by narrowing the electron beam diameter of an electron beam having a small amount of electron beams on average, the depth of focus on the fluorescent screen becomes deep, and focus deterioration occurs even in a state where the just focus point is displaced with respect to other electron guns. As the effect is reduced, the effect of space charge becomes larger and the beam spot diameter on the phosphor screen becomes larger, which does not greatly affect the deterioration of resolution, and a small electron beam current over the entire phosphor screen surface. It is possible to provide an electron gun for a cathode ray tube having an excellent function capable of obtaining a resolution in a wide range from to high current.

[Brief description of drawings]

FIG. 1 is a schematic diagram illustrating a first embodiment of the present invention.

FIG. 2 is a configuration diagram illustrating a second embodiment of the present invention,
(A) is a front view of a main part of an accelerating electrode on a focusing electrode side, and (b) is a sectional view taken along line AA of (a).

FIG. 3 is a schematic diagram illustrating a focused state of an electron beam at a main lens position according to the configuration of the second embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating a third embodiment of the present invention,
(A) is a front view of a main part of an accelerating electrode on a focusing electrode side, and (b) is a sectional view taken along line AA of (a).

FIG. 5 is a schematic diagram illustrating a focusing state of an electron beam at a main lens position according to a configuration of a third embodiment of the present invention.

FIG. 6 is a configuration diagram illustrating a fourth embodiment of the present invention,
(A) is a front view of a main part of an accelerating electrode on a focusing electrode side, and (b) is a sectional view taken along line AA of (a).

FIG. 7 is a schematic diagram illustrating a focused state of an electron beam at a main lens position according to a configuration of a fourth embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view for explaining a schematic structure of a color cathode ray tube.

FIG. 9 is a schematic sectional view showing a structural example of a main part of a multiple electron beam electron gun used for a color cathode ray tube.

FIG. 10 is an explanatory diagram of a distribution pattern of a deflection magnetic field generated by a deflection yoke.

FIG. 11 is a schematic diagram illustrating how a deflection magnetic field acts on an electron beam.

FIG. 12 is a schematic explanatory diagram of an electron beam spot shape on a phosphor screen generated by distortion of a deflection magnetic field.

FIG. 13 is a schematic diagram illustrating a state of an electron beam trajectory depending on the amount of electron beam.

[Explanation of symbols]

K _1, K _2, K ₃ Cathode 10 Control electrode 20 Accelerating electrode 30 Focusing electrode 40 Anode 11, 12, 13 Control electrode opening 21, 22, 23 Accelerating electrode opening 31, 32, 33 Anode side of focusing electrode Apertures 34, 35, 36 Accelerating electrode side apertures of focusing electrodes 41, 42, 43 Anode apertures 11L ₁ , 11L ₂ , 11L ₃ Electron lenses 21L ₁ , 21L ₂ , 21L ₃ accelerating electrodes of control electrode apertures Electron lens 31L ₁ , 31L ₂ , 31L ₃ Electron lens at opening of focusing electrode 34L ₁ , 35L ₂ , 36L ₃ Electron lens at opening of focusing electrode 41L ₁ , 42L ₂ , 43L ₃ Anode opening Electronic lens formed by.

Claims (4)

[Claims] 1. A plurality of cathodes that emit a plurality of electron beams arranged in a horizontal row, a control electrode having a plurality of openings arranged in a horizontal row facing each of the plurality of cathodes, and accelerating. At least an electrode, a focusing electrode, and an anode,
In a multiple electron beam focusing method of an electron gun having a plurality of electron lenses for focusing the plurality of electron beams on the phosphor screen between the respective electrodes, a plurality of openings of the accelerating electrode are emitted from a cathode. Multiple electron beam focusing method characterized in that the electron lens action of the aperture corresponding to the electron beam having the smallest average electron beam amount is made stronger than the electron lens action of the aperture corresponding to other electron beams. 2. A control electrode having three cathodes for emitting three electron beams arranged in a row in a row, and three openings arranged in a row in a row so as to face each of the three cathodes. , An electron gun for a color cathode ray tube having at least an accelerating electrode, a focusing electrode and an anode, and an electron gun having three electron lenses for concentrating the three electron beams on a fluorescent screen between the electrodes. In one of the three openings of the accelerating electrode, the electrode length in the tube axis direction of the opening corresponding to the electron beam having the smallest average electron beam amount emitted from the cathode is made longer than the other openings. An electron gun for a color cathode ray tube. 3. A control electrode having three cathodes for emitting three electron beams arranged in a row in a row and three openings arranged in a row in a row so as to face each of the three cathodes. , An electron gun for a color cathode ray tube having at least an accelerating electrode, a focusing electrode and an anode, and an electron gun having three electron lenses for concentrating the three electron beams on a fluorescent screen between the electrodes. In one of the three openings of the accelerating electrode, the opening diameter of the opening corresponding to the electron beam having the smallest average electron beam amount emitted from the cathode is made smaller than the opening diameters of the other openings. An electron gun for color cathode ray tubes. 4. A control electrode having three cathodes for emitting three electron beams arranged in a row in a row and three openings arranged in a row in a row so as to face each of the three cathodes. , An electron gun for a color cathode ray tube having at least an accelerating electrode, a focusing electrode and an anode, and an electron gun having three electron lenses for concentrating the three electron beams on a fluorescent screen between the electrodes. In the opening of the accelerating electrode on the side of the focusing electrode, a slit recess having a long axis in the arrangement direction of the three electron beams is formed, and among the three openings of the accelerating electrode, from the cathode, An electron gun for a color cathode ray tube, characterized in that the width of the recessed portion of the opening corresponding to the electron beam having the smallest average electron beam amount emitted is narrower than the widths of the other openings in the short axis direction.