JPH0353434A - Electron gun for color television picture tube - Google Patents

Abstract

PURPOSE:To obtain high resolution in the whole phosphor screen from low to high electric current by using quadrupole lens as prefocusing lens. CONSTITUTION:In the title electron gun, an electron beam passing hole is formed in an accelerating electrode 20, a slit hole which is long in electron beam arrangement direction in a focusing electrode side is formed, and a first focusing electrode 30, a second focusing electrode 40, and a third focusing electrode 50 are installed. A plurality of parallel plate electrodes (vertical plates) are implanted in the third focusing electrode 50 direction in the way of sandwiching the electron beam passing hole of the second focusing electrode 40 and a rim electrode 48 surrounding these parallel plate electrodes and a pair of parallel electrodes (horizontal plates) implanted in the second focusing electrode 40 direction in the way of sandwiching from rectangular direction (vertical direction) to the electron beam arrangement of the third focusing electrode 50 are installed. As a result, quadrupole lens function of a main lens owing to the current amount of an electron beam can be collected by a prefocusing quadrupole lens. In this way, high resolution in the whole phosphor screen is obtained from low to high electric currents.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an electron gun for a color picture tube equipped with an electrode structure capable of obtaining high resolution from low brightness to high brightness over the entire screen surface.

[Conventional technology]

The resolution of this type of picture tube largely depends on the spot I diameter of the electron beam and its shape. That is, high resolution cannot be achieved unless the electron beam spot, which is a bright spot generated on the screen surface of the phosphor surface by the impact of the electron beam, has a small diameter and is close to a perfect circle.

However, the electron beam trajectory from the electron gun to the phosphor screen surface becomes longer as the deflection angle of the electron beam increases, so the electron beam spot has a small diameter and a perfect circle at the center of the phosphor screen surface. If the focusing voltage is maintained at the optimum focus voltage that yields the phosphor screen surface, the periphery of the phosphor screen will be in an overfocus state, making it impossible to obtain a good electron beam spot and high resolution in the periphery. Therefore, as the deflection angle of the electron beam increases, the focus voltage is increased to weaken the main lens electric field.
However, as will be explained below, this method is not suitable for driving an in-line color picture tube.

In other words, in an in-line color picture tube in which three electron beam emitting sections are arranged in a straight line in the horizontal scanning direction,
In order to obtain a self-convergence effect, the horizontal deflection magnetic field is distorted into a pincushion shape, and the vertical deflection magnetic field is distorted into a barrel shape, so that the cross-sectional shape of the electron beam created by this distortion becomes distorted.

Since the phosphor screen surface is usually rectangular in shape, that is, the sides are long in the electron beam arrangement direction (horizontal direction), distortion is particularly large in the horizontal peripheral area.

FIG. 6 is an explanatory diagram of the relationship between the quadrupole lens magnetic field and the electron beam, where 1, 2.3 are the electron beams, 4 is the horizontal deflection magnetic field, and 5 is the direction of beam movement due to the deflection action.

FIG. 7 is an explanatory diagram of the relationship between the horizontal deflection magnetic field of the Bin cushion distribution and the electron beam, where 6 is a dipole magnetic field component, 7 is a quadrupole magnetic field component, 8 is a beam movement direction due to deflection action, and 9
is an electron beam.

FIG. 8 is an explanatory diagram of shape distortion of the beam spot, 9
H is a high brightness part (a part of the core) of the electron beam, and 9L is a low brightness part (haze part).

Hereinafter, FIGS. 6 to 8 will be explained.

In FIG. 6, three electron beams 1, 2, and 3, which have been traveling from the back side of the drawing, are deflected in the direction shown by the arrow 5 by being incident on a horizontal deflection magnetic field 4 with a pincushion distribution. Receives action. In other words, it can be considered that the horizontal deflection magnetic field 4 with the bottle cushion-like distribution is composed of a dipole magnetic field component 6 as shown in FIG. 7(a) and a quadrupole magnetic field component as shown in FIG. 7(b). , and the dipolar magnetic field 6 exerts a deflection effect on the electron beam 9 in the direction shown by the arrow 8.

The quadrupole magnetic field component 7 gives a self-conherence effect to three electron beams 1, but one electron beam 9
In order to provide a diverging effect in the horizontal direction and a converging effect in the vertical direction, the cross-sectional shape is horizontally long and flat.

By the way, the above-mentioned divergence effect acts in the direction of canceling the overfocus of the electron beam spot due to the elongation of the electron beam trajectory as the electron beam deflection angle increases, so in an in-line color picture tube, the electron beam spot In the horizontal direction, optimum focus is maintained during the deflection period. However, in the vertical direction, the degree of overfocus increases significantly due to the addition of the above-mentioned focusing effect.

As a result, the electron beam spot generated at the center of the phosphor screen surface is circular as shown by "OO" in Figure 6, while the electron beam spot formed at the horizontal periphery is circular. is distorted into a non-circular shape consisting of a high brightness core part 9H and a low brightness haze part 9L, especially the haze part 9L.
The large vertical elongation of the lens has a negative effect on focusing characteristics.

In such a case, if you apply the conventional Dyna ivy focus method, this method will horizontally adjust the lens action of the main lens. Since it is weakened equally regardless of the vertical direction, even if the haze portion 9L is removed in the vertical direction, the horizontal direction, which is already in optimal focus, will be further underfocused, and the diameter in the horizontal direction will increase.

As a result, the electron beam spot becomes significantly horizontally long, and the resolution in the horizontal direction decreases.

The present applicant's application involves a picture tube device that solves these problems and can obtain high resolution over the entire area of the phosphor screen surface. [TE Gansho 63-2
No. 30116.

FIG. 9 is an explanatory diagram of the electron gun of the picture tube device according to the above proposal, in which (a) is a sectional view showing the structure of the electron gun, and (b) is a cross-sectional view showing the structure of the electron gun.
is a front view of the first focusing electrode viewed from the eight directions of arrows in (a),
(C) is a front view of the second ffl east electrode viewed from the direction of arrow B in (a).

In the figure, K. , K2, K, are hot cathodes (hereinafter simply referred to as cathodes), IO is a control electrode, 20 is an acceleration electrode, and 30 is a first
A focusing electrode, 38 a rim electrode, 40 a second focusing electrode, 50
is anode electrode 8i (hereinafter simply referred to as anode), 11.12, 13,
2]. ,22,23,3la,32a,33a,3lb
．． 32b, 33b41a, 42a, 43a. 4lb, 4
2b, 43b, 51, 52.53 are electron beam passing holes,
C is the electron gun axis, CB is the center beam, SBI, SB2
is a side beam. Then, cathodes K+, Kz, Ks arranged in a straight line in the horizontal direction, control electrodes IO,
The accelerating electrode 20, the I-th confection electrode 30, the second focusing electrode 40, and the anode 50, which is a Saihiragi accelerating electrode, constitute an in-line color picture tube electron gun.

The first focusing electrode 30 has three circular electron beam passing holes 31a, 32a, and 33a on the end surface on the second focusing electrode 40 side, and the first focusing electrode 30 has three circular electron beam passing holes 31a, 32a, and 33a. A first flat plate electrode (vertically board). Then, it surrounds the parallel flat slopes 34, 35, 36, 37 constituting the first flat plate electrode, and the tips 34a, 35a, 36,
It has a rim electrode 38 extending a certain distance from 7a to the second focusing electrode Pi40 side.

Although the rim electrode 38 is shown as being structurally connected to the first focusing electrode 30, it is connected to the first focusing electrode 30 so that it is structurally independent and electrically at the same potential. Good too.

Further, the second focusing electrode 40 has three circular electron beam passage holes 41a, 42a, . 43a, and a pair of parallel electrodes vertically stand vertically in the direction of the first focusing electrode 30, sandwiching the electron beam passage hole from the vertical direction.
It has a second flat plate electrode (horizontal plate) of ff45.46.

Three pairs of horizontal plates may be provided for each electron beam.

The parallel plate tip portions 45a and 46a constituting the second plate electrode extend into the rim electrode 38 of the first focusing electrode 30, and the parallel plate tip portions 34a, 46a of the first focusing electrode 30 extend into the rim electrode 38 of the first focusing electrode 30. The electron guns 35a, 36a, and 37a are installed at a constant interval e in the axial direction of the electron gun. In addition, the anode 50
There are three circular electron beam passing holes 4lb, 4 on the side end face.
2b and 43b. Three circular electron beam passing holes 51, 52, and 53 are provided on the end face of the second collecting east electrode 40 of the anode 50, and the side electron beam passing holes are separated from the electron gun axis. The axial distance S2 is between the cathode K. , K2, Kl, the off-axis distance Ms l of the side electron beam 'Jm hole of the control electrode 10, acceleration electrode 20, first focusing electrode 30, second focusing electrode 40, S2
>3, and the second focusing electrode 40 and the anode 5
A main lens is formed between the side electron beam SB
,,SB2 is concentrated on the phosphor screen surface.

Note that the control electrode 10 and the acceleration electrode 20 each have 3
circular electron beam passing holes 11, 12, 13.21.
22. , 23, and the acceleration electrode 20 of the first focusing electrode 30
There are three circular electron beam passing holes 3lb, 3 on the side end face.
2b. 33b is formed.

The applied voltage applied to each electrode during operation is 50~
170V, Ov for control electrode, 400-800 for acceleration electrode
(2) 5 to 8 k as the voltage Vf applied to the first focusing electrode 30;
V, and the anode voltage Eb is 25 kV, and a dynamic voltage DVf that changes in synchronization with the vertical and horizontal deflection of the electron beam is applied to the second focusing electrode 40. This dynamic voltage DVf is 5 to 8 kV, which is equivalent to the voltage Vf of the first focusing electrode 30 when the amount of deflection of the electron beam is 0, and gradually increases as the amount of deflection of the electron beam increases. When is at its maximum, the potential is higher than the voltage Vf of the first focusing electrode 30 by 0.4 to L k V.

When the amount of deflection of the electron beam is 0, the first
Since there is no potential difference between the focusing electrode 30 and the second focusing electrode 40, it is attached to the parallel flat plates (first flat plate electrode: vertical plate) 34, 35, 36 inside the first focusing electrode 30 and the second focusing electrode 40. Parallel plate (second plate electrode: horizontal plate) 45
．． 46 has no influence on the electron beam, and the electron beam is focused with optimum focus at the center of the phosphor screen surface by the main lens between the second focusing electrode 40 and the anode 50.

As the amount of deflection of the electron beam increases, the potential of the second focusing electrode 40 becomes higher than the potential of the first focusing electrode 30. Therefore, the parallel plates (vertical plates) 34, 35,
36. 37 and a parallel plate attached to the second focusing electrode 40 (
A quadrupole lens electric field is formed by the horizontal plates 45 and 46, and the potential difference between the second focusing electrode 40 and the anode 50 decreases, weakening the focusing effect of the main lens.

FIG. 10 is an explanatory diagram of the quadrupole lens electric field action by the first focusing electrode and the second focusing electrode of the electron gun shown in FIG. 9, in which (a) is a partial front view of the first focusing electrode; (b) is the second
FIG. 3 is a partial cross-sectional view of a focusing electrode.

In the figure, Fh, Fv, and Fvv represent forces acting on the electron beam due to the electric field, and the same symbols as in FIG. 9 indicate the same parts.

Parallel planes (vertical plates) 34, 3 inside the first focusing electrode 30
5, 36, 37 and a parallel plate (horizontal plate) 45.46 attached to the second focusing electrode 40, the electric field is a so-called quadrupole lens electric field. 3
Between the vertical plates 34-35.35-36.36-37 (only 35-36 is shown in the figure), a focused electric field is formed that is gentle in the vertical direction and tight in the horizontal direction, and the electron beam is It is largely focused in the horizontal direction by a force of Fh-Fv (Fh>Fv). In addition, the second focusing electrode 4 in the same figure (b)
A diverging lens is formed between the horizontal plates 45 and 46 attached to the horizontal plate 45 and 46, which is tight in the vertical direction and has almost no effect in the horizontal direction, and is greatly diverged in the vertical direction by the force of FVV.

Therefore, the electron beam has an elongated cross section in the vertical direction between the first focusing electrode 30 and the second focusing electrode piA 40, and the electron beam passing through the deflection magnetic field has a quadrupole magnetic field component as explained in FIG. This has an effect opposite to the distortion to a horizontally elongated cross-sectional shape, and the horizontally elongated flattening of the electron beam spot is prevented by canceling out the effects of the first focusing electrode 30 and the second focusing electrode 40.

In addition, as the amount of deflection of the electron beam increases, the lens magnification of the main lens becomes weaker, so the degree to which the electron beam with the increased amount of deflection becomes OHA focus on the phosphor screen surface is reduced, and the phosphor screen surface Not only the central part of
The electron beam can be focused with optimum focus even in the peripheral area, and a nearly perfect circular electron beam spot can be obtained.

[Problem to be solved by the invention]

In the technique J/PI mentioned above, the amount of correction for the peripheral part of the phosphor screen surface varies depending on the amount of electron beams emitted from the cathode, and there is a difference between large current (high brightness) and small current (low brightness). The resolution will be different. Hereinafter, the problems of the above-mentioned conventional technology will be explained with reference to the drawings.

Figure 1 is an explanatory diagram of changes in the shape of the electron beam spot due to differences in the current distribution of the spirit beam, and Figure 12 is an illustration of the force acting on the electron beam 1 between the cathode K and the phosphor screen. It is an explanatory diagram.

At the time of large current, the vertical plates 34 and 35 of the first focusing electrode 30
, 36.37 and the horizontal of the second focusing electrode 40 +Jli45.
If the beam spot at the periphery of the phosphor screen is made small in diameter and close to a perfect circle as shown in (a-1) in Figure 8(a) by optimizing 46, at a small current As shown in (a-2) of Fig. 8(a), there is horizontal overfocus, and the halo becomes horizontally elongated. In addition, when the current is small, the spot shape can be small in diameter and close to a perfect circle as shown in (b-1) of the same figure (b), but when the current is large, the spot shape can be made horizontally as shown in (b-2). becomes the underfocus and becomes the core of the oblong ellipse. this is,
This is thought to be because the force of repulsion between the electron beams differs depending on the amount of current.

Normally, the dynamic focus voltage DVf applied to the second focusing electrode 40 is applied to the first focusing electrode 40 in order to achieve optimum focus by erasing the vertical halo of the heam spot at the periphery of the phosphor screen. 30 vertical plates 34, 35, 36, 37 and a horizontal plate 4 of the second focusing electrode 40.
5.46 is optimized to minimize the horizontal beam spot diameter around the phosphor screen surface. At this time, the horizontal action on the electron beam is the quadrupole lens action (Fh) between the first focusing electrode and the second focusing electrode, and the action of deflection distortion (
Effect of deflection magnetic field: Fh+), repulsion effect between electron beams (
There are three possible space charge repulsion effects: Fh2), and in order to obtain the optimum focus at the periphery of the phosphor screen, the 12th
As shown in figure (a), the action Fh of the quadrupole lens is the deflection distortion Fh
, (divergence effect) and repulsion effect between the electron beam Fh2
(divergence effect) is balanced, and a beam spot with a round cross section is obtained at the periphery of the phosphor screen surface. On the other hand, at a small current, the repulsion Fh2 between the electron beams weakens (Fh2 is set to zero in the figure), as shown in the same figure (b), and the horizontal direction becomes overfocused due to the focusing effect Fh of the quadrupole lens. . Therefore, in the prior art, there is a problem in that it is difficult to optimize the shape of the beam spot around the phosphor screen surface due to changes in the amount of current of the electron beam.

An object of the present invention is to adopt a quadrupole lens as a prefocus lens other than the main lens constituting an electron gun, and also to provide a third focusing electrode whose focus voltage changes according to the deflection angle of the electron beam. An object of the present invention is to provide an electron gun for a color picture tube that can obtain high resolution from small currents to large currents over the entire area of the phosphor screen surface by providing the electron gun between the accelerating electrode and the I-th focusing electrode.

[Means to solve the problem]

The above purpose is to create a cathode that emits multiple electron beams arranged in one direction. In an electron gun having a control electrode, an accelerating electrode, a focusing electrode, and an anode, the accelerating electrode is provided with an electron beam i111 hole corresponding to the number of electron beams, and
A slit 7'l long in the electron beam array direction on the focusing electrode side
A first focusing electrode having an electron beam passing hole corresponding to the number of electron beams is provided. The second focusing field and the third
A plurality of upright parallel flat slope electrodes (vertical plates) and these parallel flat temporary electrodes are arranged in the direction of the third focusing electrode so as to sandwich the electron beam passing hole of the second focusing electrode from the electron beam arrangement direction. A rim electrode surrounding the electron beam, and a pair of parallel plate electrodes (horizontal plates) placed in the direction of the second focusing electrode so as to be sandwiched therebetween from a direction perpendicular to the electron beam arrangement direction of the third focusing electrode (vertical direction) are provided. Achievement is achieved by having a strong structure.

[Effect]

A quadrupole lens electric field is formed by parallel plate electrodes (vertical plates) sandwiching the electron beam passage hole of the second focusing electrode and parallel plate electrodes (horizontal plates) sandwiching the electron beam passage hole of the third focusing electrode. In addition, a quadrupole lens electric field is formed between the first focusing electrode and the slit 1 of the accelerating electrode, and the quadrupole lens effect is large when the electron beam amount is small and becomes smaller as the electron beam amount increases. changes.

In addition, the first focusing electrode and the third! By changing the voltage applied to the J east electrode so as to increase as the deflection angle of the electron beam increases, the action of the quadrupole lens increases as the deflection angle of the electron beam increases.

As described above, the quadrupole lens effect of the main lens due to the current amount of the electron beam can be corrected by the quadrupole lens of the prefocus lens, and the resolution can be improved over the entire area of the phosphor screen without causing a decrease in resolution due to changes in the current star of the electron beam. resolution is obtained.

〔Example〕

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

FIG. 1 is an explanatory diagram of a first embodiment of an electron gun for a color picture tube according to the present invention. It is a front view seen from eight directions, K,, K2K, are hot cathodes (hereinafter simply cathodes), 10 is a control electrode, 20 is an acceleration electrode, 30 is a first focusing electrode, 40 is a second focusing electrode, 48 is a rim electrode, 50 is a third focusing electrode, 60 is an anode electrode (hereinafter simply referred to as an anode), 1
1, 12, 13, 21, 22, 23, 31.32 3
3.41a, 42a, 43a, 4lb. 42b, 43b
, 51a, 52a, 53a, 51b 52b, 53b, 6
1, 62, 63 indicates the electron beam passing hole, 44, 45
, 46.47 is a vertical plate, 48 is a rim electrode, 54 (55)
indicates horizontal {reverse.

Also, C is the electron gun axis, CB is the center beam, SB. ，
S.B. is a side beam. The cathodes K, , K. are arranged in a straight line in the horizontal direction. ．． K,, control electrode IO,
Accelerating electrode 20, No. I! a bundle electrode 30, a second focusing electrode 40,
The third focusing electrode 50 and the anode 60, which is the final accelerating electrode, constitute an in-line color picture tube electron gun.

The accelerating electrode 20 has three circular electron beam passing holes 21 and 2.
2.23, and slit holes 24, 25, and 26 that are long in the electron beam arrangement direction are formed on the first focusing electrode 30 side. These slit holes are shown as three independent holes, but instead of this, as illustrated in FIG. They may be made independent and connected so that they have the same electrical potential.

FIG. 2 is an explanatory diagram of another example of slits and holes provided in the accelerating electrode in FIG. ~<f) indicates that a common slit hole is provided for all electron beams.

The figure (a) shows an electron beam passing hole 21 in the accelerating electrode 20,
22. Rectangular openings 241, 242, 243 larger than 23
The electrode 200 with a slit formed therein is integrated to effectively form a slit hole.

In FIG. 3B, electrodes 341, 342, and 343 in the shape of oblong frames that individually surround each electron beam are attached to the accelerating electrode 20 to give the effect of a slit hole.

The same figure (c) is structurally separated from the accelerating electrode 20,
Individual horizontal apertures 401, 402, 403 for each electron beam
In this example, electrodes 400 having a structure formed thereon are arranged in close proximity to each other.

In FIG. 4(d), a horizontally long slit 500 common to all electron beams is formed on the first focusing electrode 30 side of the accelerating electrode 20.

In FIG. 6(e), an electrode 600 having a horizontally long aperture 601 common to all the droplet beams is placed close to the accelerating electrode 20.

The figure (f) shows that the shape of the accelerating electrode 20 is formed into a horizontally long groove shape bent in the arrangement direction of the electron beam passing holes 21, 22, 23 as shown in the figure, and a wall extending toward the first focusing electrode 30 side is formed. 700
This gives the effect of a slit hole.

In addition, the actual slit holes are not limited to the above-mentioned examples, and the opening shape is also an oblong Sui circle. Alternatively, it may be a diamond shape or the like.

The first focusing electrode 30 has circular electron beam passing holes 31 and 32.
．． 33, and is electrically connected to the third focusing electrode 50 to which a focusing voltage Vf is applied. Further, the electron beam passing hole of the first focusing electrode 30 does not necessarily have the same hole diameter as the electron beam passing hole of the 20 examples of accelerating electrodes and the electron beam passing hole of the second focusing electrode 40 side.
The hole diameter of the electron beam passage hole on the 0 side may be smaller or larger than the hole diameter on the second converging lightning pole 40 side.

3 and 4 are explanatory diagrams of the second and third embodiments of the present invention, where Ecl is the voltage applied to the control electrode 10;
Ec2 is the voltage applied to the accelerating electrode 20, Vf is the focus voltage, and DVf is the Guinamilk focus voltage.

In each figure, a first focusing electrode 30 and a second focusing electrode 40
An auxiliary electrode 70 having three electron beam IFFL holes is provided between the accelerating electrode 20 and the auxiliary electrode 70 in FIG.
The accelerating voltage Ec2 applied to the accelerating electrode 20, which is lower than the voltage applied to the focusing electrode 40, is applied to the auxiliary electrode 70.

FIG. 4 also shows that the auxiliary electrode 70 is connected to the first focusing electrode 30. Second
An anode voltage Eb that is higher than the voltage applied to the focusing electrode 40 is applied.

The explanation will be given again with reference to FIG.

The second focusing electrode 40 has three circular electron beam passing holes 4lb, 42b, 43b on the end face on the third focusing electrode 50 side, and faces the third focusing electrode 50 and has the electron beam passing holes. A first flat plate electrode (vertical) consisting of four parallel flat plates 44, 45, 46, and 47 vertically planted in the direction of the third focusing electrode 50 with the electron beam passing hole horizontally sandwiched from the end face of the shape. version). Parallel flats 4Ii. constituting the first flat plate electrode. 44.45.46.47
, and the tips 44a, 45a46 of this parallel plate
a. It has a rim electrode 48 extending a certain distance from 47a to the third focusing electrode 50 side. Although the rim electrode 48 is shown as being structurally integrated with the second focusing electrode 40, it may alternatively be constructed as an electrode that is structurally independent from the second focusing electrode 40 and electrically connected to the second focusing electrode 40. to the second focusing electrode 4
It can also be configured to be connected to 0.

Further, the third focusing electrode 50 is provided on the end surface of the second focusing electrode 40.
circular electron beam passing holes 51a. 52a, 53a, a pair of parallel flat plates 54.54. , 55 (horizontal Fi.). Incidentally, a separate pair of horizontal plates (that is, three pairs) may be provided for each electron beam.

The tips 54a and 55a of the parallel plates constituting the second plate electrode (horizontal plate) extend into the rim electrode 48 of the second focusing electrode 40, and the tips of the parallel plates of the second focusing electrode 40 Section 44a. 45a. They are installed at a constant interval 1 in the axial direction of the electron gun with respect to 46a and 47a. Also,
Three circular electron beam passing holes 5 are provided on the end face of the 60 anodes.
1b52b and 53b. Three circular electron beam passing holes 61, 62, and 63 are provided on the end face of the third focusing electrode 50 of the anode 60, and the off-axis distance S2 of the side electron beam passing holes from the electron gun axis is is the cathode K. which is the front stage electrode. , K2K3, the off-axis distance S of the side electron beam passage holes of the control electrode 10, the acceleration electrode 20, the first focusing electrode 30, the second focusing electrode 40, and the third focusing electrode 50, the relationship S2 > S+. A main lens is formed between the third focusing electrode 50 and the anode 60 to concentrate the side electron beams SB, SB2 on the phosphor screen surface.

Note that the control electrode 10 and the acceleration electrode 20 each have 3
circular electron beam passing holes 11, 12.1.3, 21
, 22.23, and the acceleration electrode 20 of the first focusing electrode 30
Three electron beam passing holes 3lb, 32b.
33b is formed.

The applied voltage applied to each electrode during operation is 50~
170V, OV to control electrode. 400-800 for accelerating electrode
V, 5 to 8 k as the voltage Vf applied to the second focusing electrode 40
V, and the anode voltage Eb is 25 kV, and a dynamic voltage DVf that changes in synchronization with the vertical and horizontal deflection of the electron beam is applied to the first focusing electrode 30 and the third focusing electrode 50. This da/f naq voltage DVf is 5 to 8 kV, which is equivalent to the voltage f of the second focusing electrode 40 when the electron beam deflection amount is O, and gradually increases as the electron beam deflection amount increases. However, when the amount of deflection of the electron beam is maximum, the potential becomes higher than the voltage vr of the 24th J flux electrode 40 by 0.4 to 1 kV.

When the amount of deflection of the electron beam is Q, as described above, the first
Focusing electrode 30, second focusing electrode 40, and third focusing electrode 5
Since there is no potential difference between the parallel plate (first plate electrode: vertical plate) 44.4.5, 4 inside the second focusing electrode 40
6.47 and the parallel plate (second plate electrode; horizontal plate) 54.55 attached to the third focusing electrode 50 have no influence on the electron beam, and the electron beam is connected to the third focusing electrode 50 and the anode 60. The main lens in between focuses the phosphor at the center of the screen surface with optimal focus.

When the amount of deflection of the electron beam increases, the first focusing electrode 30 and the third focusing electrode 30
Since the potential of the focusing electrode 50 is higher than the potential of the second focusing electrode 40, the parallelism inside the second focusing electrode 40
4 by the vertical plate) 44,/15.4647 and the parallel plate (horizontal temporary) 54.55 attached to the third focusing pole 50.
As a polar lens electric field is formed, the potential difference between the third focusing electrode 50 and the anode 60 decreases, and the focusing effect of the main lens becomes weaker, and the above-mentioned quadrupole effect causes the electron beam in the peripheral area of the phosphor screen to be focused. Horizontal flattening is prevented.

At the same time, when the potential of the first focusing electrode 30 increases, the potential difference between the accelerating electrode 20 and the first focusing electrode 30 increases, and the quadrupole lens action of the slit holes 24, 25, 26 of the accelerating electrode 20 becomes stronger.

FIG. 5 is an explanatory diagram of the accelerating electrode 20, first focusing electrode 30, and quadrupole lens action of the electron gun shown in FIG. Cathode and control electrode in the tube axis direction. Cross-sectional view of the accelerating electrode and the first focusing electrode, (
b) is a cross-sectional view similar to the above when the amount of deflection of the electron beam is increased.

In the figure, the electron beam emitted from the cathode K2 is accelerated and focused through the control electrode IO, the acceleration electrode 20, and the first focusing electrode 30, once forms a crossover, and enters the main lens. The position of this crossover varies depending on the amount of current of the electron beam, and when the amount of current is small, it is at a distance of L on the cathode side, and when the amount of current is large, it is at a distance of L2 on the first focusing electrode 30 side. Change.

In addition, since the slit hole 25 of the accelerating electrode 20 has a narrow opening in the vertical direction of the tube axis and a wide opening in the horizontal direction, the electron beam is focused vertically and weakly in the horizontal direction, resulting in a horizontally long cross-sectional shape. Become. However, as mentioned above, the position of the crossover changes depending on the amount of current of the electron beam, and the quadrupolar action due to the slits 1 and holes of the accelerating electrode differs, and when the amount of electron beam current is small, the crossover is on the cathode side. Therefore, the quadrupole lens effect due to the slit hole is strongly applied, resulting in a beam shape with a horizontally long elliptical cross section, and when the current beam is large, the position of the cross-over becomes closer to the first focusing electrode 30, so the quadrupole lens effect becomes weaker. This results in a beam shape with a horizontally oblong elliptical cross section that is close to a circle.

When the cage beam is deflected, the potential of the first focusing electrode 30 becomes higher than when the deflection angle is O, so the quadrupole lens effect becomes stronger, and the horizontally elongated ellipse of the electron beam becomes even more horizontally long. For this reason, the second focusing electrode 40 and the third focusing electrode 50
When the vertical plate and horizontal plate of the electron beam are optimized when the beam current amount of the electron beam is large, the horizontal OHA focus of the periphery of the phosphor screen surface when the beam current amount is small is expressed by the horizontally oblong elliptical cross-sectional shape shown above. The beam spot of the second focusing electrode 40. By making the beam incident on the quadrupole lens of the third focusing electrode 50, the Oha focus can be corrected and a beam spot close to 71 circles can be obtained. It is possible to correct the quadrupole lens effect between the two.

〔Effect of the invention〕

As explained above, according to the present invention, an electron gun for a color picture tube is proposed which has an excellent function and can obtain high resolution from a small current range to a large current range of the electron beam over the entire area of the phosphor screen surface. I can cheat.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the electron gun for a color picture tube according to the present invention, FIG. 2 is an explanatory diagram of another example of the slit hole provided in the accelerating electrode in FIG. 1, and FIGS. The figures are explanatory diagrams of the second and third embodiments of the present invention, and Fig. 5 is a diagram 191 of a theory of the four-plum lens action by the accelerating electric current of the electron gun shown in Fig. 1 and the first focusing electrode. Figure 6 is an explanatory diagram of the relationship between the quadrupole lens magnetic field and the electron beam, Figure 7 is an explanatory diagram of the relationship between the horizontal deflection magnetic field of pincushion distribution and the electron beam, and Figure 8 is an explanatory diagram of the relationship between the horizontal deflection magnetic field of the pincushion distribution and the electron beam.
9 is an explanatory diagram of the shape distortion of a beam spot, FIG. 9 is an explanatory diagram of an electron gun of a picture tube device according to the prior art, and FIG.
FIG. 11 is an explanatory diagram of the quadrupole lens electric field effect caused by the first and second focusing electrodes of the electron gun shown in the figure. FIG. 12 is an explanatory diagram of the force acting on the electron beam. ■0... Discipline electrode, 20... 30... First focusing electrode, 40... Focusing electrode, 48... Rim electrode, 50 3 Focusing electrode, 60... Anode Electrode, ・Auxiliary spiritual pole.・Acceleration electrode, ...Volume 2...No. 70... (b) Fig. 3 Condolence 4 Fig. 5 (Sound amount I movement n) Condolence 6 Fig. 4 Fig. 8 Fig. 9 Fig. 9 (b) (C) Figure 10 (a) Whistle (b)

Claims (1)

[Claims] 1. A cathode for emitting three electron beams arranged in one direction, and at least a control electrode, an acceleration electrode, a focusing electrode, and an anode electrode for this cathode in this order. In the electron gun for a color picture tube arranged in the tube axis direction, the focusing electrode extends from the accelerating electrode side to the anode electrode, and includes a first focusing electrode;
It consists of a second focusing electrode and a third focusing electrode, and the second focusing electrode has a vertical parallel plate on its end face facing the third focusing electrode, which horizontally sandwiches the electron beam passing hole, and the third focusing electrode is provided with a horizontal parallel plate vertically sandwiching an electron beam passing hole formed on the end face facing the second focusing electrode, and an electron beam passing hole is provided in the electron beam passing hole of the accelerating electrode facing the first focusing electrode. On the other hand, a slit hole is provided that is narrow in the vertical direction and wide in the horizontal direction, and a constant focus voltage is applied to the second focusing electrode, and the focus voltage is applied to the first focusing electrode and the third focusing electrode as the deflection angle of the electron beam increases. An electron gun for a color picture tube characterized by being configured to apply a voltage that changes to a higher value. 2. The electron gun for a color picture tube according to claim 1, wherein the slit hole is constituted by an electrode separate from the accelerating electrode. 3. In the electron gun for a color picture tube according to claim 1, a voltage lower than the focus voltage applied to the first focusing electrode and the second focusing electrode is applied between the first focusing electrode and the second focusing electrode. An electron gun for a color picture tube, characterized by being provided with an auxiliary electrode. 4. In the electron gun for a color picture tube according to claim 1, a voltage higher than a focus voltage applied to the first focusing electrode and the second focusing electrode is applied between the first focusing electrode and the second focusing electrode. An electron gun for a color picture tube, characterized by being provided with an auxiliary electrode.