JP2638837B2 - Cathode ray tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to a cathode ray tube used for a television picture tube, a terminal display device and the like, and particularly to a color cathode ray tube.

[Summary of the Invention]

The present invention generates an electrostatic quadrupole in the main electron lens portion of the electron gun according to the dynamic focus,
Distortion of the electron beam spot around the screen due to electric field distortion in the electromagnetic deflection means so that at least one of the front electron lenses for the center beam or the side beam has an asymmetric lens action in the horizontal and vertical directions. To improve.

[Conventional technology]

In a conventional color cathode ray tube, for example, as shown in FIG. 10, a neck portion of the tube (1) is opposed to a color phosphor screen (2) formed on an inner surface of a panel portion of the cathode ray tube (1). The electron gun (3) is arranged. In this color cathode ray tube, the axial Z direction of the plurality of cathodes such as red, green, and respective cathodes K _R corresponding to the respective colors of blue, K _G and K _B are electron gun (3), the X-direction perpendicular thereto And the cathodes K _R , K _G and K _B as viewed from the fluorescent screen (2) side.
There takes a so-called in-line arrangement which is arranged on a straight line that is in-line, first in common to each of the cathodes K _R, K _G and the electron beam is taken out from the K _B K _R, K _G and K _B
A grid G ₁ , a second grid G ₂ , a third grid G ₃ , a fourth grid G ₄ , and a fifth grid G ₅ are arranged, and the third grid G _3, ie, the first anode electrode, and the fourth grid G ₄ , and the focus electrode, by the fifth grid G ₅ or second anode electrode constitutes a common unipotential type main electron lens, in substantially the center of the main electron lens, the electron beams B _R, is B _G and B _B It is made to cross. The subsequent stage of the fifth grid or second anode G _5, for example electrostatically convergence means C, which is constituted by a deflector is provided, whereby the electron beam B _R, B _G and B _B are fluorescent face (2 ) To converge. Then, the anode line pipe of this kind, the plurality of, for example, three electron beams B _R, B _G and B _B are at respective positions of the fluorescent face (2), i.e., so that the optimum convergence can be obtained even with the periphery of the screen There is a configuration that employs a so-called convergence-free deflection yoke (hereinafter referred to as CFD) in which the magnetic field distribution of the horizontal and vertical deflection means DY is distorted.

In this case, FIG. 11 schematically shows the beam spot on the fluorescent screen (2). For example, when a circular spot is obtained at the center, a horizontally long beam spot is obtained at the peripheral part, particularly at the corner part. Further, halation due to overfocusing occurs in a diagonal direction as shown by a broken line, and the beam spot size is substantially increased, resulting in a reduction in resolution.

In order to eliminate the distortion of the beam spot based on the distortion of the CFD, a quadrupole for correction for canceling the quadrupole distortion caused by the CFD is provided, and the distortion which makes the beam vertically long in advance is provided. The method of giving positively is taken. For example, as shown in FIG. 10, an electromagnetic quadrupole (4) is provided on the outer periphery of the neck portion of the tube (1) where the electron gun (3) is arranged, and a magnetic field indicated by a thin arrow in FIG. A magnetic field distortion due to the distribution is applied, a current synchronized with a deflection current applied to the deflection yoke DY is supplied to the deflection yoke DY, and a dynamic focus is applied to correct a spot distortion at a peripheral portion of the screen by CFD.

However, the provision of the electromagnetic quadrupole (4) on the outer periphery of the neck portion of the cathode ray tube (1) as in the case of such a configuration requires an accurate selection of the position. There is a problem that it becomes complicated.

In addition, since it is necessary to supply a current synchronized with the deflection current to the deflection means DY to this quadrupole, a dedicated circuit is required, resulting in an increase in cost.

Further, there is a problem that power for energizing the electromagnetic quadrupole (4) is required, and the power consumption of the cathode ray tube increases.

[Problems to be solved by the invention]

The present invention solves the above-mentioned problems, and provides a cathode ray tube capable of achieving high resolution by reliably avoiding spot distortion based on electric field distortion of CFD with a simple configuration. I do.

[Means for solving the problem]

The present invention includes a plurality of cathodes K _R as shown in FIG. 1, K _G
And K _B are orthogonal with the axis Z direction of the electron gun (3) and which X
The cathodes K _R , K
Electron beam taken out from _G and K _B K _R, the first anode electrode G ₃ and the focus electrode G ₄ second anode electrodes constituting the unipotential type main electron lens common to K _G and K _B G ₅
In cathode ray tube bets is provided an electron gun comprising arranged sequentially on the same axis Z, and comprises a CFD, the cathode side of the main electron lens, the electron beams B _R, with respect to B _G and B _B Te, individually, in the second grid G ₂ (figure specifically the first anode electrode G ₃ for example common low voltage side of the previous stage, the first and second constituting the second grid G ₂ rear stage side end face plate of the second-stage portion G ₂₂ of the electrode portions G ₂₁ and G ₂₂ (22B))
Thus, a bi-potential type front-stage electron lens is formed. And as shown in the exploded perspective view of the front electron lens and the rear stage side electrode portion G ₂₂ ~ fifth grid G ₅ electrode G ₂ constituting the main electron lens in Figure 2, the low voltage constituting the preceding stage electron lens (end plates of the FIG. G ₂ (22B)) electrode G ₂ of the side, the electron beam penetrating apertures h _{2 RB} and a side electron beam an electron beam transmissive aperture h _2GB relates center electron beam located in the center is located on both sides Compared to h _2BB , the dimension is selected to be wider in the Y direction or narrower in the X direction, or at least one of them.

On the other hand, the focus electrode G ₄ is set to 3
The first, second, and third electrode portions G ₄₁ , G _42, and G ₄₃ are sequentially formed from the divided cathode side.

First to third electrode portions G _{41 to} G ₄₁ of the focus electrode G ₄
The ₄₃ common electron beam transmissive aperture h ₄₁ to h ₄₃ are thus provided on the central axis Z for each electron beam B _R, B _G and B _B. For the electron beam transmissive aperture h ₄₁ and h ₄₃ of the first and third electrode portions G ₄₁ and G ₄₃ of the focus electrode G _4, X
A through hole wide in the direction and narrow in the Y direction, for example, a cut circular shape having a chord along the X direction with respect to the Y direction in a circular shape,
Or elongated hole, or formed in an oval or rectangular shape or the like, the central electron beam transmissive aperture h of the second electrode portion G ₄₂
For the _42, it is formed on the X narrow and is cut circular or elongated holes or elliptical shape of the opening h ₄₁ and h ₄₃ is rotated by 90 degrees with respect to the direction or rectangular shape or the like.

Further, the second electrode portion G ₄₂ of the focus electrode G _4, first and second voltage applied to the anode electrode G _3, and G _5, i.e. the high anode voltage (i.e. the fluorescent screen potential) HV 25 to 33 applying a fixed focus voltage V _FC shown in Figure 3 of about%, the first and third electrode portions G ₄₁ and G ₄₃ contrary, gives a dynamic focus voltage. The dynamic focus voltage is selected as a voltage waveform in which a parabolic voltage having one horizontal scanning cycle is superimposed on a voltage waveform having one vertical scanning cycle.

[Action]

The electron gun in a cathode ray tube according to this configuration, by replacing the electron lens system in the optical lens system is as shown in Figure 4 when showing the schematic configuration thereof, each beam B _R, B _G
Front electron lens L _SR, L _SG and individually for and B _B
SB is constituted by the rear stage side portion (22B) and bipotential electron lens according to the first anode electrode G ₃ grid G _2, each beam B _R, a main electron lens commonly to B _G and B _B L
_M is configured. P _C1 and P _C2 is convergence prism formed by the convergence means C of the rear caster, the center electron beam B _G is located in the center, the side electron beams B _R and B _B are fluorescent located on both sides relative thereto It is made to concentrate (convergence) on the light surface (2).

The main electron lens L _M is a lens system formed by the first anode electrode G ₃ and a lens system L _M1 and the focus electrode G ₄ formed by the focus electrode G ₄ and the second anode electrode G ₅
Configuring the focusing lens system according composite lens system consisting of L _M2 is the same as the lens arrangement of a conventional uni-potential type, the present invention further configuration, the main electron lens L in _M, 3
The electrode portions G ₄₁ ~G ₄₃ of the split focus electrode, the electrostatic quadrupole lens L _Q is formed. In other words, the electron beam B _R, when B _G and B _B is in the scanning position of the screen center, the first to third electrode portions G ₄₁ ~G ₄₃ three electrodes be in substantially the same voltage of the focus electrode G ₄ portion G ₄₁ electric field distribution in the X-Z cross section defined by ~G ₄₃ becomes rotationally symmetric with respect to the axis Z, the electron beam B (B _R as shown in FIG. 5 a, B _G,
Cross-sectional shape of the B _B) is shown a circular, during scanning of the peripheral portion of the screen, the electron beam transmissive aperture h ₄₂ of the central electrode portions G ₄₂ as illustrated in FIG. 5 B, and both side electrode portions G ₄₁ Due to the influence of the narrow portions of the electron beam transmission apertures h ₄₁ and h ₄₃ of the G _43, a quadrupole effect occurs in the electric field distribution, and the force that spreads in the Y direction and is narrowed in the X direction is applied to the electron beam B Given, it becomes vertical. Thus, the quadrupole electric field in the focus electrode G ₄ beam shape prior to entering the deflection magnetic field, the beam spot at the periphery by a vertical so as to correct the distortion in advance CFD, CFD
Is corrected to a spot shape approaching the corrected circular shape.

In other words, this configuration automatically corrects the beam spot distortion due to the CFD magnetic field by positively generating the distortion rotated by 90 ° with respect to the quadrupole distortion due to the CFD by the dynamic focus voltage. .

However, in practice, the main electron lens L _M incident on the electron beam B _R, B _G and B _B are side electron beams B _R, located on both sides of the center electron beam B _G is located in the center, and B and in of _B, the main electron lens L the center electron beam B _G and the side electron beams in the periphery of the screen by quadruple electron lenses L _Q described above by the dynamic focusing voltage by the incident angle is different to _M B _R and B _B And the optimum focus condition is different. That is, each electron beam B _R at the periphery of the Hotarukomen (2) in FIG. 6 A, B each beam spot S _{PR G} and B _B, S _PG and the center electron beam to indicate S _PB B _G When the spot S _PG is to have selected the focus condition indicating small circular strained good, spots S _PR and S _PB of side electron beams B _R and B _B is an elongated spot shape becomes over-focused state with respect to the X direction At the same time, halation occurs in the X direction on the fluorescent screen due to overfocus as shown by broken lines. Further, as shown in FIG. 6B, if the side electron beam spots _SPR and _SPB are selected to have a good circular shape with little distortion around the fluorescent surface (2), the center electron beam Becomes an underfocus state in the X direction, and becomes a spot that is long in the X direction, that is, a horizontally long spot.
However in the present invention configuration, the electron beam B _R as described above, B _G and B individually in front electron lens L _SR against _B, L _SG
Beam transmission aperture _{h2GB of} the low-voltage side electrode constituting the _LSB and _LSB is the electron beam transmission aperture for the side electron beam
h compared to _2RB and h _2BB, either wider in the Y direction as shown in FIG. 7 A, at least one of the dimensional relationship or width is narrower in the X direction as shown in FIG. 7 B front electron lens L _SG about the center electron beam B _G by the selection, the side electron beams B _R and front electronic lens L _SR and the main electron lens weakens a focusing lens action in the Y-direction than in L _SB about B _B or spots of the center electron beam B _G before entering the L _M are made to the vertically long having a major axis in the Y direction or the side electron beams B _R and B _B
For all the electron beams by being formed in a horizontally long spot having a major axis in the X-axis direction before the focusing lens effect in the X direction is incident weakened relative to the main electron lens L _M B _R, B _G, and B the main electron lens L electrostatic quadrupole lens in the _M L _Q in can match the focus condition whereby distortion correcting all the electron beams B _R of the beam spot at the peripheral portion of the fluorescent screen described above for _B, B _G and B
_B can be corrected well.

〔Example〕

Further, an example of the cathode ray tube according to the present invention will be described. First
In the figure, parts corresponding to those in FIG. 10 are denoted by the same reference numerals, and redundant description will be omitted.

Cathode K _G is the axis Z of the center electron beam in this example
The cathodes K _R and K _{B of} the side electron beams are arranged in the XZ plane at a required angle with respect to the cathodes K _R , K _G and K _B in this example. these cathodes K _R, respectively on the end surface plate opposite to the K _G and K _B, the electron beam penetrating apertures h _1R, first grid G _1R, G _1G and G _1B are arranged to h _1G and h _1B are bored , first to fifth grids G ₁ ~G ₅ are sequentially arranged on the same axis Z in common to further each of the cathodes K _R, K _G and K _B. The second grid G ₂ is the cathodes K _R, opposing portions husband and K _G and K _B s first
Grid G _1R, a first electrode portion G ₂₁ to G _1G and G _1B substantially parallel-formed consist of parallel plate portions here each electron beam transmissive aperture h _2R1, h _2G1 and h _2B1 is bored, made of a second electrode portion G ₂₂ disposed in the subsequent stage. This second electrode portion G
₂₂ is a an end surface plate (22B) opposed to the end face plates (22F) and the third grid G ₃ facing the first electrode portion G _21. The end face plate (22F) has a plate portion parallel to the portion having the electron beam transmissive aperture h _2R1, h _2G1 and h _2B1 of the first electrode portion G _21, respectively to these people the electron beam penetrating apertures h _2RF, h _2GF and h
_2BF is drilled. In addition, as shown in FIG.
Each beam B _R even in B), B _G and B _B electron beam transmissive aperture h _{2 RB} for transmitting, h _2GB and h _2BB is, the electron beam transmission aperture h _2RF as shown in FIG. 1, h _2GF and h _2BF It is drilled facing. And have the side electron beams B _R and sides of the electron beam transmissive aperture h _{2 RB} and h _2BB about B _B for example, basic shape as shown in FIG. 7 A opposed along the X direction with respect to the Y-direction has a circular shape and smaller than the diameter of the basic circular spacing of these edges, that is, selected from the width of the X-direction in the small, the electron beam aperture h _{2 RB} related to the center beam B _G opening
a circular opening of a diameter corresponding to the basic circle diameter h _2GB and h _2BB. Alternatively the side electron beam transmissive aperture h _{2 RB} and h _2BB, as shown in FIG. 7 B circular and without, with respect to the electron beam transmissive aperture h _2GB center with respect to even the X direction as a basic shape similar circular It has opposing sides along the Y direction, and the distance between these opposing sides is selected to be smaller than the diameter of the basic circle, that is, smaller than the X direction.

Electron beam transmissive aperture h _{2 RB} in Figure 7 A, a minor axis length of the electron beam transmissive aperture h _2GB in h _2BB or FIG. 7 B, when the major axis length and phi _L, the 0.7φ _L ~0.85φ _L Select.

Further, the third grid (the first anode), the end face plate on the side facing the second grid G ₂ (23), a circular-shaped electron beam transmissive aperture h _3R having a sufficient large inner diameter, h _3G and h _3B
Is drilled.

Also, the first to third electrode portions G ₄₁ of the focus electrode G ₄
~G ₄₃ is the end opposite the second electrode portion G ₄₂ of the central,
Each of the end plates (11) and (13) can be formed into a cup shape having a cylindrical peripheral wall surface. It forms a cut circular shape cut by a straight line along the X direction with respect to the Y direction with respect to the circle, that is, opposing sides S _1a and S _1b , S _3a
And _S3b are selected to have a width less than the diameter of their base circle. Also, the central electrode part _G42 is
Formed by a metal plate facing the end face plates (11) and (13) of the first and third electrode portions G ₄₁ and G _43, the electron beam transmissive aperture h ₄₂ at its center is bored. The electron beam transmissive aperture h ₄₂ is 90 ° rotated for example the basic shape the shape of the opening h ₄₁ and h ₄₃ is a circular cutting circular, the sides S _2a and S _2b which faces along the Y direction with respect to the X direction Are formed such that the distance between them is smaller than the diameter of the basic circle.

Also, these electrode portions G ₄₁ ~G _43, each of these, for example, a pair of support pins by integrally or welded to the outer peripheral portion (15) These and is projected another electrode e.g.
With support pins (15) for G ₁ , G ₂ , G ₃ , G ₅
The required positional relationship is set by being embedded in the beading glass (16) of the book. Also, (17) indicates that each of the electrode portions G _{41 to} G _41
43 shows a projection for setting the position in the rotation direction of ₄₃ .

The first and third electrode portions of the focus electrode G _4
G41 and _G43 are electrically connected to each other by a lead (18) as shown in FIG. Is coupled from the central electrode portions G ₄₂ and the side electrodes G ₄₁ and G ₄₃ of the focus electrode G ₄ in each example terminal pins provided on the neck portion rear end of the cathode ray tube (14), the terminal pin (14) It required fixed voltage V _FC and dynamic focus voltage V _FD described above from
Is given.

Note that the relationship between the major axis length A and the minor axis length (that is, the interval between the straight sides) B of the electron beam transmission apertures h _{41 to} h ₄₃ is B = 0.8 A
When it was selected to be ~ 0.95A, it was confirmed that the quadrupole intensity was well balanced by dynamic focus and that a good spot could be obtained.

In the arrangement described above, the total beam B _R, for B _G and B _B, is converged at the same time by the main electron lens by the common electrode G ₃ ~G _5, the quadrupole above also, the three beams B _R , B
Is common for the _G and B _B, each beam B _R, to set the same time optimum conditions for B _G and B _B is set in the Z direction position of the main surface of the quadrupole in the focus electrode G ₄ are important In the above configuration, when the lengths of the respective electrode portions G ₄₁ , G _42, and G ₄₃ of the focus electrode G _{4 in} the axial direction are l ₁ , l ₂ , and l ₃ , l ₁ > l ₃ > selected on the relationship _{l 2, l 1: l 3} = 17: 15~19: 1
It is desirable to select 3. That is, the following phenomenon occurred when the relationship of l ₁ ≦ l ₃ was satisfied.

(I) the side beams B _R and B _B spot in the beam spot at the center portion of the fluorescent face (2) is distorted in a crescent shape as shown in FIG. 8.

(Ii) side beam spot B _R and B _B when changing the dynamic focusing voltage V _FD is moved symmetrically in the X direction.

The phenomenon (i) affects the resolution, and the phenomenon (ii) causes a problem that misconvergence occurs around the screen when dynamic focus is applied.

FIG. 9 shows the quadrupole Z in the fourth grid G ₄ on the horizontal axis.
The position on the axis, the negative cathode side the center position of the fourth grid G ₄ 0, fluorescent face (2) side positively taken the movement on the fluorescent face of the side beams B _R and B _B (2) FIG. 9 plots the case where the focus voltage V _FC at each position is changed (1 KV) with the amount as the vertical axis.
The distance between G ₄₁ , G ₄₂ and G ₄₃ was 0.5 mm, and l ₂ was fixed at 0.5 mm. Plot group a is for l ₁ = 4 mm, l ₃ = 4 mm, plot group b is for l ₁ = 4.5 mm, l ₃ = 3.5 mm, and plot group c
Is the case where l ₁ = 5 mm and l ₃ = 3 mm. According to this, l ₁ =
4.5 mm, as l ₃ = 3.5 mm, a quadrupole position, when moving from the center of the focus electrode G ₄ in 0.5mm fluorescent face (2) side, the side beams B _R, the motion of the beam spot B _B Is almost 0 (zero). At the same time, it was confirmed that distortion of the side beam spot was eliminated, and a good spot was obtained. The practicable range is the range L, and l ₁ = 4.
From the condition of 25 mm, l ₃ = 3.75 mm, it is found that it is desirable to select l ₁ = 4.75 mm, l ₃ = 3.25 mm, that is, l ₁ : l ₃ = 17:15 to 19:13. Was.

In the above configuration, the anode voltage HV = 27 kV, the cutoff voltage Ekco = 95 V, the cathode current Ik = 200 μA, l ₁ = 4.5 mm, l ₂ =
0.5 mm, the beam spot diameter on the fluorescent face (2) of the case of the l ₃ = 3.5 mm, each beam B _R, B _G, the diameter of the average of each the X and Y directions for B _B, A similar average diameter of a peripheral spot in the Y direction at the center in the X direction at 0.54 mm is X
0.57mm each in the direction and the Y direction, and X at the center of the Y direction.
The average spot diameter around the periphery in the direction is
Each spot was 0.40 mm, 0.75 mm in the X direction, and 0.42 mm in the Y direction and 0.78 mm in the X direction at the corner of the fluorescent screen (2). This spot is
The result was equivalent to the case where the electromagnetic quadrupole (4) described in FIG. 10 was accurately provided at a predetermined position.

Then, in the configuration described above, the fixed focus voltage, to select the 25 to 33% of the anode voltage HV, in less than 25%, results in shortening the overall length of the focusing electrode G _4,
When the quadrupole interferes with the main electron lens, a problem arises. When the ratio exceeds 33%, the power is supplied to the stem (1) on the stem side terminal pin at the rear end of the neck tube of the tube (1) by increasing the focus voltage. (14) The power supply from the side causes a problem from the viewpoint of the withstand voltage.

The first and third electrode portions G ₄₁ of the focus electrode G ₄
And dynamic focus voltage applied to the G _43, when the average voltage V _FDM as shown in FIG. 3 is a voltage different fixed focus voltage V _FC to the second electrode portion G ₄₂ are both DC voltage Two kinds of voltages, V _FDM and V _FC , are supplied from a flyback transformer in a driving circuit of a cathode ray tube, for example.
The need to take out one tap complicates the power supply circuit. In order to avoid this, the average voltage V _FDM of the dynamic focus voltage applied to the first and third electrode portions G ₄₁ and G ₄₃ and the fixed focus voltage V _FC applied to the second electrode portion G ₄₂ must be the same. desired. However in this case, the dynamic focus voltage at the scanning position of the screen center of the electron beam by a lower voltage relationship than the fixed voltage V _FC, the electrostatic quadrupole is formed by the focus electrode G _4, the second sides S which faces the opening h ₄₂ of the electrode portion G _42
The sides _2a and S _2b are on the high voltage side, and opposing sides S _1a S _1b , S of the openings h ₄₁ and h ₄₃ of the first and third electrode portions G ₄₁ and G _{43.
When the 3a} and S _3b sides are on the low voltage side, the electron beam cross-sectional shape has an inverse relationship with respect to the X and Y directions as shown in FIG. 5B, that is, a force that spreads in the X direction and narrows in the Y direction. That is, the electron beam cross section tends to be horizontally long with the major axis in the X direction. In this case, therefore, in order for the shape correction, the fifth grid (second anode) G _5, the electron beam of the third electrode portion G ₄₃ on the opposite side of the fourth grid (focus electrode) G ₄ Lord in response to transmission opening h ₄₃ to apply the configuration proposed in to form an electron beam transmissive aperture h ₅ wide in the Y direction, that the applicant's 1987 September 7 date patent application "cathode ray tube" it is possible to compensate for the above-mentioned disadvantages based on the in electron lens L _M was Me brought diffusion electron lens effect with respect to the Y direction Te is matched with the voltage V _{FD M} and V _FC.

〔The invention's effect〕

As described above, according to the present invention, it is possible to avoid providing a special electromagnetic quadrupole (4) for correction on the outer periphery of the neck tube,
The main electron lens has a structure in which the focus electrode is divided into three
It is possible to improve the spot shape by forming the electrostatic quadrupole lens L _Q to L _M.

According to the configuration of the present invention, the focus electrode G _{4 is set} to 3
Since it is intended to divide, these electrode portions G ₄₁ ~G ₄₃ may take the assembly manufacturing incorporated with other electrodes to each other by similarly beading glass and another electrode (16),
The number of man-hours does not increase and the complexity of manufacturing and assembling is remarkably reduced as compared with the case where a special quadrupole is precisely placed at a predetermined position outside the neck tube as before, and the cost is low. Can be achieved.

Further, according to the present invention, the generation of spot distortion based on the difference in incident angle between the center electron beam and side electron beams incident on the electrostatic quadrupole lens L _Q provided front lens system, asymmetric lens action to As a result, the spot distortion is compensated for, so that a better spot shape can be obtained on the phosphor screen, and a cathode ray tube capable of projecting a high-resolution, high-quality image. Can be configured.

[Brief description of the drawings]

FIG. 1 is a structural view of an example of a cathode ray tube according to the present invention, FIG. 2 is an exploded perspective view of a main part thereof, FIG.
FIG. 4 is a view showing the arrangement of the lens system of the electron gun, FIGS. 5A and 5B are electric field diagrams in the focus electrode section, FIG. 6 is an explanatory view of the beam cross-sectional shape, and FIGS. FIG. 8 is a front view of the grid, FIG. 8 is an explanatory diagram of a beam spot shape, FIG. 9 is a diagram showing a relationship between a quadrupole position and a side beam spot position, and FIG. 10 is a schematic configuration diagram of a conventional cathode ray tube. ,
FIG. 11 is a diagram showing a beam spot on the fluorescent screen, and FIG. 12 is a diagram showing the configuration of an electromagnetic quadrupole. (1) is a cathode ray tube tube (2) is Hotarukomen, (3) an electron gun, G ₁ ~G ₅ the first first to the first to fifth grids, G ₄₁ ~G ₄₃ focus electrode 3 is an electrode part.

Claims (1)

(57) [Claims] 1. A plurality of cathodes are arranged on an XZ plane including one axis Z direction and an X direction orthogonal thereto, and a unipotential type main is commonly used for electron beams extracted from each cathode. An electron gun in which a first anode electrode, a focus electrode, and a second anode electrode constituting an electron lens are sequentially arranged on the same axis Z, and a fluorescent field is formed by distorting the magnetic field distribution. A cathode ray tube having horizontal and vertical deflection means adapted to perform convergence correction around the surface, wherein a front stage electron lens is individually formed for each electron beam on the cathode side of the main electron lens; The electron beam transmission aperture for the center electron beam located at the center of the low voltage side electrode forming the electron lens is the electron beam transmission aperture for the side electron beams located on both sides. In contrast, the focus electrode is selected to be wider in the Y direction orthogonal to the X direction and the Z direction or narrower in the X direction. The first and third electrode portions on both sides are divided into three portions in the Z direction, and the first and third electrode portions on both sides are wide in the X direction and narrow in the Y direction. A central second electrode portion having an electron beam transmission opening narrow in the X direction and wide in the direction on the axis Z; and a second electrode portion of the focus electrode. A cathode ray tube, wherein a fixed focus voltage is applied to an electrode portion, and a dynamic focus voltage is applied to the first and third electrode portions.