JPH0521016A - Color picture tube - Google Patents

Abstract

PURPOSE:To prevent picture image deterioration with the distortion of a beam spot on a phosphor screen eliminated, by generating a uniform magnetic field to electron beams, necessary to be concentrated, out of parallel beams. CONSTITUTION:Magnets 26B and 26R, for concentrating plural parallel beams on a phosphor 8, are arranged in the vicinity of an electron lens formed by an electron gun 22. The magnets 26B and 26R are composed so as to generate a uniform magnetic field to electron beams necessary to be concentrated. This can eliminate the distortion of the beam spot of electron beams, deflected and concentrated on a phosphor screen, by the magnetic field, and moreover can evade the effect of the magnetic field to the focusing of electron beams not requiring deflection, allowing the prevention of picture image deterioration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube which emits a plurality of beams, and more particularly to a color picture tube in which a magnet for concentrating the plurality of beams on a phosphor screen is arranged in an electron gun.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 7, a color picture tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, and is arranged in a neck 3 of the funnel 2. The three electron beams 5B, 5G, 5R emitted from the provided electron gun 4 are deflected by the horizontal and vertical magnetic fields generated by the deflection yoke 6 mounted on the outer side of the funnel 2 and arranged inside the panel 1. By horizontally and vertically scanning the phosphor screen 8 formed of the three-color phosphor layer formed on the inner surface of the panel 1 through the shadow mask 7,
A structure for displaying a color image is formed on the phosphor screen 8.

Among such color picture tubes, in particular, the three-color phosphor layers of the phosphor screen 8 are formed in a stripe shape, and the electron gun 4 is arranged in one row consisting of a center beam and a pair of side beams. As an in-line type that emits 5R, a non-uniform horizontal direction generated by the deflection yoke 6,
A self-convergence in-line type color picture tube that self-focuses by a vertical magnetic field is widely used.

This in-line color picture tube electron gun 4
In order to concentrate the three electron beams 5B, 5G, and 5R on one point on the phosphor screen 8, a pair of side beams are inclined and emitted in the direction of the center beam from the beginning, and the first three In some cases, the electron beams 5B, 5G, and 5R are emitted in parallel, and a pair of side beams are deflected and concentrated in the center beam direction by an asymmetric electric field formed in the middle.

However, in the former case in which a pair of side beams is inclined from the beginning, it is difficult to assemble three cathodes, and the electron beam passage holes of each electrode must be arranged along the electron beam trajectory. Therefore, there is a problem that it is difficult to obtain required electrode precision and electron gun assembly precision. In the latter case, which emits parallel first and deflects in the middle, if an asymmetric electric field is to be generated by an electrode having a deflected electron beam passage hole, an electron gun including this electrode must be assembled with a predetermined assembling accuracy. There is a problem that it is difficult.

Therefore, in order to solve such a problem, the electron beam passage holes of the electrodes sequentially arranged on the three cathodes are made coaxial with respect to the three cathodes, and the final electrode on the beam emission end side thereof is arranged. An electron gun in which a ring-shaped permanent magnet having a quadrupole component magnetic field is arranged in the center, and a pair of parallel side beams are deflected in the direction of the center beam by the magnetic field component and concentrated on the phosphor screen is disclosed. 57-1
No. 87845.

By disposing the annular permanent magnet for forming the quadrupole component magnetic field on the final electrode in this way, it becomes possible to dispose the electron beam passage holes such as the control electrode and the focus electrode corresponding to each cathode coaxially. The assembling accuracy of the electron gun can be improved. However, as shown in FIG. 8A, in order to concentrate the pair of parallel side beams 5B and 5R on the phosphor screen by the quadrupole component magnetic field 11 generated by the annular permanent magnet 10, a strong magnetic field is required. Is required, and its strong magnetic field is applied to each electron beam 5B, 5G, 5R by an arrow 12
Since a directional force is exerted, each electron beam 5B, 5G, 5R is distorted as shown in (b) and deteriorates the image drawn on the phosphor screen.

[0008]

As described above, in the conventional electron gun of an in-line type color picture tube, in order to concentrate the three electron beams on one point on the phosphor screen, a pair of side beams are centered from the beginning. The one that is inclined to emit in the beam direction, and the one that emits three electron beams in parallel at first and deflects a pair of side beams toward the center beam direction by an asymmetric electric field formed in the middle to concentrate them. There is. However, in the former case where the pair of side beams is inclined from the beginning, it is difficult to assemble the three cathodes, and the electron beam passage holes of each electrode must be arranged along the trajectory of the electron beam. There is a problem that it is difficult to obtain the electrode precision and the electron gun assembly precision. In the latter case, which emits parallel first and deflects in the middle, if the asymmetric electric field is formed by, for example, an electrode having a deflected electron beam passage hole, an electron gun including this electrode can be assembled with a predetermined assembling accuracy. There is a problem that it is difficult.

In order to solve such a problem, the electron beam passage holes of the electrodes sequentially arranged on the three cathodes are made coaxial with respect to the three cathodes, and four electron beam passage holes are formed on the final electrode on the beam emission end side. There is an electron gun in which an annular permanent magnet having a pole component magnetic field is arranged, and a pair of parallel side beams are deflected by the magnetic field component toward the center beam direction so as to be concentrated on the phosphor screen. However, when an annular permanent magnet that forms a quadrupole component magnetic field is arranged on the final electrode in this way, it becomes possible to coaxially arrange electron beam passage holes, such as control electrodes and focus electrodes, corresponding to each cathode. Although the gun assembly accuracy can be improved, a strong quadrupole component magnetic field is required to concentrate a pair of parallel side beams on the phosphor screen. Is distorted and the image drawn on the phosphor screen is deteriorated.

The present invention has been made in order to solve the above-mentioned problems, in which a permanent magnet is arranged in an electron gun so that a plurality of parallel beams emitted from this electron gun are made to be one point on a phosphor screen. The purpose of the present invention is to eliminate the distortion of the beam spot on the phosphor screen in the case of concentrating and to construct a color picture tube that does not deteriorate the image.

[0011]

A plurality of cathodes for emitting a plurality of parallel beams in an envelope and a plurality of electron lenses for focusing the plurality of parallel beams on a phosphor screen. A color image is formed by arranging an electron gun composed of electrodes of the above, and arranging a magnet for concentrating the plurality of parallel beams on the phosphor screen in an envelope near the electron lens formed by the electron gun. In the tube, the magnet is configured to generate a uniform magnetic field with respect to the electron beam that needs to be concentrated among the plurality of parallel beams.

[0012]

As described above, when the magnet for concentrating the plurality of parallel beams on the phosphor screen is configured to generate a uniform magnetic field for the electron beam requiring concentration, the magnetic field is deflected. As a result, the distortion of the beam spot of the electron beam concentrated on the phosphor screen can be eliminated, the influence of the magnetic field on the focusing of the electron beam which does not require deflection can be avoided, and the deterioration of the image can be prevented.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

FIG. 1 shows an in-line type color picture tube which is one of the embodiments. This color picture tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1, and the inner surface of the panel 1 is a strife-like three-color fluorescent light emitting in blue, green, and red. A phosphor screen 8 composed of a body layer is formed, and is attached to a mask body 20 having a large number of electron beam passage holes formed therein and facing the phosphor screen 8 and a peripheral portion of the mask body 20. A shadow mask 7 including a mask frame 21 is arranged. In the neck 3 of the funnel 2, a center beam 5G and a pair of side beams 5B, which pass on the same plane,
An in-line type electron gun 22 that emits three electron beams 5B, 5G, and 5R arranged in a line composed of 5Rs is arranged. Further, on the outside of the neck 3 of the funnel 2, the above-mentioned 3 electron beams 5B, 5
A deflection yoke 6 that generates a magnetic field that deflects G and 5R horizontally and vertically is mounted.

As shown in FIG. 2, the electron gun 22 has three cathodes K arranged in a row, three heaters (not shown) for heating the cathodes K, and the cathodes K in sequence. The first to fifth grids G1 to G5 having an integral structure are arranged in the phosphor screen direction. This 1st to 5th
In the grids G1 to G5, three electron beam passage holes are provided coaxially with the three cathodes K, respectively. An electron lens for controlling electron emission from each cathode K by applying a predetermined voltage to the cathode K and each grid G1 to G5 and focusing the emitted electron into an electron beam, and its electron beam The electron lens for accelerating and focusing is formed to emit parallel three electron beams 5B, 5G, 5R arranged in a row toward the phosphor screen.

Further, in this color picture tube, the cup electrode 24 constituting the fifth grid G5 which is the final electrode of the electron gun 22 is made of a non-magnetic material, and a pair of side beams passing through it are formed at the bottom of the cup electrode 24. A pair of plate-shaped magnets 26B, 26R are arranged opposite to each other with the holes 25B, 25R sandwiched therebetween. As shown in FIG. 3, each pair of magnets 26B and 26R has opposite magnetic poles, and one side beam passage hole 25B and the other side beam passage hole 25R have opposite magnetic poles. It has become.

By the way, as described above, a pair of side beam passage holes 25B are provided inside the cup electrode 24 constituting the final electrode.
, 25R, and the pair of magnets 26B, 26R are arranged so that the opposite surfaces have opposite magnetic poles, the side beam passage hole 25B between the opposite magnetic poles of the pair of magnets 26B, 26R is arranged as shown in FIG. , 25R forms a magnetic field 27. Therefore, by appropriately setting the strength of the magnetic field 27, the pair of side beams 5B, 5R are deflected in the direction of the center beam 5G and the three electron beams 5B, 5G, 5R are concentrated on the phosphor screen 8. You can Moreover, since the magnetic field 27 formed between the opposing magnetic poles of the pair of magnets 26B and 26R can be made uniform as indicated by the broken lines in parallel, the phosphor screen 8
It is possible to prevent the upper beam spot from being distorted. Therefore, it is possible to prevent the deterioration of the image due to the distortion of the beam spot.

Next, another embodiment will be described.

In the above embodiment, the pair of plate-shaped magnets are arranged inside the pair of side beam passage holes formed in the bottom portion of the cup electrode forming the fifth grid, and the pair of side beam passage holes are arranged inside the hole, as shown in FIG. a) shows the pair of side beam passage holes 25B.
, 25R, and a pair of magnets 26B and 26R sandwiching them, and a cylindrical magnetic seal 28 around the center beam passage hole 25G.
Is provided. In this way the center beam passage hole
If a magnetic seal 28 is provided around 25G, each pair of magnets
The magnetic field formed by 26B and 26R can be sufficiently shielded so as not to affect the center beam 5G.
5G distortion can be effectively prevented.

In FIG. 4B, instead of arranging a pair of plate-shaped magnets with a pair of side beam passage holes sandwiched therebetween as in each of the above-described embodiments, the magnetic poles have a pair of side beam passage holes 25B.
, 25R, and a pair of U-shaped magnets 29 are arranged so as to face each other. In addition, in FIG. 4C, a pair of U-shaped magnetic bodies 30 are arranged in place of the U-shaped magnets, and a magnet having both ends as magnetic poles is provided on each back surface of the pair of U-shaped magnetic bodies 30. 31 is arranged. Even if the U-shaped magnet 29 or the U-shaped magnetic body 30 is arranged in this way, a uniform magnetic field can be formed on the pair of side beam passage holes 25B and 25R, and the same effect as the above embodiment can be obtained. can get.

FIG. 5 shows an example applied to an electron gun which emits three electron beams of Δ arrangement, and each electron beam passage hole 25B is provided between three electron beam passage holes 25B, 25G and 25R of Δ arrangement.
, 25G and 25R, the three arc-shaped magnets 32 are arranged so that the opposing magnetic poles are opposite magnetic poles. In this way, the magnet 32 is placed between each electron beam passage hole 25B, 25G, 25R.
Is arranged, three electron beam passage holes 25B of Δ array,
A uniform magnetic field can be formed on 25G and 25R, and the arrow
As shown by 33, the three electron beams 5B, 5G, and 5R in the Δ array can be deflected toward the center of the array, and can be concentrated on one point on the phosphor screen without distorting each electron beam.

FIG. 6 shows an annular magnet 34 having four magnetic poles around the three electron beam passage holes 25B, 25G and 25R arranged in a row and corresponding to the pair of side heme passage holes 25B and 25R.
And a pair of plate-shaped magnetic bodies 35B and 35R sandwiching a pair of side heme passage holes 25B and 25R, and a cylindrical magnetic seal 28 provided around the center beam passage hole 25G. is there. With this configuration,
The magnetic field 27 formed by the annular magnet 34 as shown by the broken line
Is molded into a uniform magnetic field by each pair of plate-shaped magnetic bodies 35B and 35R, and the magnetic seal 28 shields the magnetic field 27 formed by the annular magnet 34, and the same effect as that of the above-described embodiment can be obtained.

In each of the above-mentioned embodiments, magnets that have been magnetized in advance are attached to the electrodes of the electron gun and arranged in the color picture tube. However, these magnets are attached to the electrodes of the electron gun in advance and the magnets are installed in the color picture tube. After assembling the color picture tube, it may be magnetized from the outside.

Further, in the above embodiment, the magnet is arranged at the final electrode located at the tip of the electron gun, but the arrangement of this magnet is not limited to the final electrode, and the electrons formed in the electron gun are not limited to this. Any position may be used as long as it does not adversely affect the electron beam near the lens. In addition, such a magnet has a field that is conventionally used to adjust the deflection sensitivity for three electron beams arranged in a row by appropriately changing the shape and arranging the magnet at a position where the leakage magnetic field of the deflection yoke reaches. -It can also function as a controller.

[0025]

The electron gun is an electron gun that emits a plurality of parallel beams, and a magnet for concentrating the plurality of parallel beams on the phosphor screen is arranged in the vicinity of the electron lens formed by the electron gun. In such a color picture tube, if the magnet is configured to generate a uniform magnetic field for an electron beam that needs to be concentrated among a plurality of parallel beams, the electron beam passage holes of each electrode are coaxial and the assembly accuracy is high. The electron gun can be assembled, and multiple beams can be concentrated on the phosphor screen without changing the focus voltage, etc. Moreover, the distortion of the beam spot on the phosphor screen is eliminated and the image is deteriorated. Can be prevented.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a color picture tube which is an embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an electron gun that emits three electron beams arranged in a line.

FIG. 3 is a diagram showing the arrangement of magnets for the electron gun.

4 (a) to 4 (c) are diagrams showing different magnet arrangements for an electron gun that emits three electron beams arranged in a row.

FIG. 5 is a view showing the arrangement of magnets with respect to an electron gun that emits three electron beams in a Δ array.

FIG. 6 is a view showing a different arrangement of magnets for an electron gun that emits three electron beams arranged in a row.

FIG. 7 is a diagram showing a configuration of a conventional color picture tube.

FIG. 8A is a diagram showing the arrangement of magnets in a conventional color picture tube, and FIG. 8B is a diagram for explaining the influence of the magnetic field formed by the magnets on the beam spot.

[Explanation of symbols]

 1 ... Panel 2 ... Funnel 3 ... Neck 5B, 5G, 5R ... 3 Electron beam 22 ... Electron gun 25B, 25R ... Pair of side beam passage holes 25G ... Center beam passage holes 26B, 26R ... Magnet 28 ... Magnetic shield 29 ... Magnet 30 ... Magnetic substance 31 ... Magnet 32 ... Magnet G1 ... First grid G2 ... Second grid G3 ... Third grid G4 ... Fourth grid G5 ... Fifth grid K ... Cathode

Claims (1)

Claim: What is claimed is: 1. An envelope is provided with a plurality of cathodes for emitting a plurality of parallel beams and an electron lens for focusing the plurality of parallel beams on a phosphor screen. An electron gun composed of a plurality of electrodes is arranged, and a magnet for concentrating the plurality of parallel beams on the phosphor screen is arranged in an envelope near an electron lens formed by the electron gun. The color picture tube according to claim 1, wherein the magnet is configured to generate a uniform magnetic field for an electron beam that needs to be concentrated among the plurality of parallel beams.