JPH07211248A - Electron gun color image receiving tube - Google Patents

Abstract

PURPOSE:To make a better beam spot better and obtain stable focusing characteristic by composing an electrode having a cylindrical part out of the electrodes composing a main lens part by means of combination of the inner electrode on which cylindrical parts are formed with the outer electrode in which circular pores are formed. CONSTITUTION:As in the case of grids G3 and G4, when an electrode composing a main lens is consisting of an electrode having a cylindrical part, the electrode is composed of the inner electrodes G3ti and B4b on which cylindrical parts 20a to 20c are formed and by the outer electrodes G3to and G4bo in which circular pores 21a to 21c are formed. The inner diameters of the cylindrical parts 20a to 20c are equal to the pore diameters of the circular pores 21a to 21c, and G3to and G4to are tightly field to the electrodes G3ti and G4bi. Thereby, even if the shape of the electrodes are degraded, the stable focusing characteristic can be obtained without deforming the shape of a beam spot.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron gun for a color picture tube, and more particularly to an electron gun for a color picture tube in which an electrode structure constituting a main lens section of the electron gun for emitting three electron beams arranged in a row is improved.

[0002]

2. Description of the Related Art Generally, as shown in FIG. 5, a color picture tube has an envelope composed of a panel 1 and a funnel 2 integrally joined to the panel 1. A phosphor screen 3 including a three-color phosphor layer that emits green and red is provided, and a shadow mask 4 is arranged inside the phosphor screen 3 so as to face the phosphor screen 3. On the other hand, in the neck 5 of the funnel 2, 3 electron beams 6
An electron gun 7 that emits B, 6G, and 6R is arranged.
The electron gun 7 is usually composed of three cathodes, three heaters for heating the cathodes separately, and a plurality of electrodes arranged in order from the cathode in the phosphor screen 3 direction at predetermined intervals.

Then, the three electron beams 6B, 6G and 6R emitted from the electron gun 7 are deflected by a magnetic field generated by a deflecting device 8 mounted outside the funnel 2, so that the phosphor screen 3 is moved horizontally. It is formed so as to display a color image by performing vertical scanning.

In such a color picture tube, an electron gun which emits three electron beams 6B, 6G, 6R arranged in a row consisting of a center beam 6G passing through the same horizontal plane and a pair of side beams 6B, 6R. The in-line type color picture tube has become the mainstream color picture tube at present.

By the way, as the electron gun 7 of the in-line type color picture tube, the three electron beams 6B and 6G arranged in a line are arranged.
, 6R are finally focused on the phosphor screen 3, the focusing electrodes and the final accelerating electrodes that constitute the main lens section are arranged in a row, as shown in FIG. There is one formed in an elliptic cup shape having an integral structure having the cylindrical portions 10a, 10b and 10c.

An electrode having such a structure has been conventionally manufactured by subjecting a metal plate having a predetermined thickness to an overhanging process, an ironing process, a burring process, a drilling process and the like. for that reason,
If the above-mentioned electrodes are formed by such a molding process, in the electron gun of a compact design, the three cylindrical parts 10a, 10
Since b and 10c are located close to each other and the distances to the short side and the long side of the electrodes are different, the root portion between the cylindrical portions 10a, 10b and 10c and the short side The root part and the root part on the long side differ in the amount of processing in overhanging and ironing, and the amount of strain received is different,
The wall thickness of each root part changes. As a result, the cylindrical portion 1
0a, 10b, 10c roundness of each root portion and the shape from the electrode outer surface to each cylindrical portion 10a, 10b, 10c deteriorate (shoulder), the shape of the beam spot is distorted, and the focus characteristic deteriorates. There is.

[0007]

As described above, as an electron gun for an in-line type color picture tube, a focusing electrode which constitutes a main lens unit for finally focusing the three electron beams arranged in a row on the phosphor screen, There is one in which the final accelerating electrode is formed in the shape of an elliptic cup having an integral structure having at its bottom three cylindrical portions arranged in a row through which three electron beams pass respectively.

The electrode having such a structure has conventionally been manufactured by subjecting a metal plate having a predetermined thickness to overhanging, ironing, burring, and boring. for that reason,
When the electrodes are formed by such a molding process, in the compact design electron gun, the three cylindrical parts are located close to each other,
In addition, since the distance to the short side and the long side of the electrode is different, the root part between each cylindrical part, the root part on the short side and the root part on the long side are overhanging or The amount of ironing is different, the amount of strain received is different,
The thickness of each root changes. As a result, there is a problem that the roundness of each root portion of the cylindrical portion and the shape from the electrode outer surface to the cylindrical portion are deteriorated, the shape of the beam spot is distorted, and the focus characteristic is deteriorated.

As a means for solving such a problem, a lower die or an upper die of a mold conventionally used for forming the electrode,
Alternatively, the roundness of each root of the cylindrical portion and the shape from the outer surface of the electrode to the cylindrical portion have been improved by adjusting the shape of the punch and the processing speed. However, with such a method, even if some results are obtained, due to the reproducibility when manufacturing the die and punch itself, and the variation in the plate thickness of the material to be processed, the trueness of each root part of the cylindrical part There is a problem that it is difficult to keep the circularity and the shape from the outer surface of the electrode to the cylindrical portion stable and constant.

The present invention has been made in view of the above problems, and an object of the present invention is to construct an electron gun for a color picture tube which has a good beam spot shape and stable focus characteristics.

[0011]

At least one of a plurality of electrodes constituting a main lens unit for finally focusing a row of three electron beams from an electron beam generating unit on a phosphor screen has three electrons. In an electron gun for a color picture tube comprising an electrode having three cylindrical portions arranged in a row through which the beams pass separately, an electrode having the cylindrical portion is provided with three electrodes arranged in a row through which three electron beams pass through each separately. It is composed of an inner electrode having a cylindrical portion formed therein and an outer electrode fitted to the inner electrode and having three circular holes arranged in a line coaxially with the three cylindrical portions of the inner electrode at the bottom portion.

[0012]

As described above, the inner electrode having the three cylindrical portions arranged in a row, the inner electrode having the three cylindrical portions arranged in a row through which the three electron beams individually pass, and the inner electrode , And the outer electrode formed with three circular holes of the inner electrode coaxially arranged on the bottom and three circular holes arranged in a line on the bottom, the characteristics of the electrode with respect to three electron beams are: It is determined by the shape of the hole and its periphery from the outer surface of the outer electrode to the circular hole. Moreover, the shape of the circular hole of the outer electrode and the peripheral portion reaching the circular hole can be formed accurately and satisfactorily. Therefore, when the electrode is constructed by combining the inner electrode having the cylindrical portion and the outer electrode having the circular hole, the electron gun having a stable focus characteristic is formed by eliminating the distortion of the shape of the beam spot. be able to.

[0013]

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

FIG. 1 shows an electron gun of an in-line type color picture tube which is one of the embodiments. This electron gun has three cathodes KB, KG, KR arranged in a line on the same horizontal plane.
Three heaters (not shown) for separately heating the cathodes KB, KG, KR, the cathodes KB, KG, KR
From the first to fourth grids G1 to G4, which are sequentially arranged in the direction of the phosphor screen, and shield shields Sc attached to the phosphor screen side of the fourth grid G4, the cathodes KB, KG, KR, the heater, and the first to fourth grids G1 to G4 are integrally fixed by a pair of rod-shaped insulating supports (not shown).

This electron gun is a bipotential type electron gun, and includes cathodes KB, KG and KR and first and second grids G that are successively adjacent to the cathodes KB, KG and KR.
1 and G2 control the electron emission from each of the cathodes KB, KG and KR, and constitute an electron beam generator which focuses the emitted electrons to form a three electron beam. In this electron gun, the third grid G3 is the focusing electrode and the fourth grid G3 is
4 forms the final accelerating electrode, and these third and fourth grids G
3 and G4 form a main lens unit for finally focusing the three electron beams from the electron beam generating unit on the phosphor screen.

Each of the first and second grids G1 and G2 is composed of a plate-shaped electrode having an integral structure.
In the grids G1 and G2, three circular electron beam passage holes are formed in a line corresponding to the cathodes KB, KG and KR. Each of the third and fourth grids G3 and G4 is a tubular electrode formed by abutting two cup-shaped electrodes G3b, G3t, G4b and G4t. The cup-shaped electrode G3b of the third grid G3 and the cup-shaped electrode G of the fourth grid G4.
The cathodes KB, KG, K are provided on the surface facing the 4t adjacent electrode.
Corresponding to R, three circular electron beam passage holes are formed in a line.

On the other hand, the cup-shaped electrode G3t of the third grid G3 and the cup-shaped electrode G4b of the fourth grid G4.
Is particularly shown in FIG. 2 (illustrated for electrode G3t),
Each of the cup-shaped inner electrodes G3ti and G4bi is closely fitted to the outside of the inner electrodes G3ti and G4bi at the bottom and side surfaces thereof, and the cup-shaped outer electrodes G3to and G4bo are welded at a plurality of peripheral welding points. Consists of. Its inner electrode G
At the bottom of 3ti and G4bi, as shown in FIG. 3, three cylindrical portions 20a, 20b and 20c, through which three electron beams respectively pass, are formed in a row corresponding to the cathodes KB, KG and KR. ing. On the other hand, as shown in FIG. 4, cathodes KB, KG, KR are provided on the bottoms of the outer electrodes G3to, G4bo.
Corresponding to, the cylindrical portion 20 of the inner electrodes G3ti, G4bi
Coaxial with a, 20b and 20c, three circular holes 21a, 21b and 21c through which the three electron beams pass respectively are formed in a line. Inner electrodes G3ti, G4bi of the cylindrical portions 20a, 20b, 20c of inner diameter φi and outer electrode G3to
, G4bo circular holes 21a, 21b, 21c hole diameter φo
Is equal to, and φi = φo.

Such cup-shaped electrodes G3t, G4b are manufactured by subjecting the inner electrodes G3ti, G4bi to forming processes such as overhanging, ironing, burring and drilling. On the other hand, the outer electrode G3to,
G4bo is manufactured by overhanging and boring, and its inner electrode G3ti, G4bi and outer electrode G3to,
It is manufactured by fitting G4bo and welding the peripheral parts.

By the way, the third and fourth grids G3,
Like G4, the electrode that constitutes the main lens that finally focuses the three electron beams arranged in a row on the phosphor screen is
In the case of an electrode having three cylindrical portions arranged in a row through which the three electron beams pass respectively, the inner electrodes G3ti, G4bi having three cylindrical portions 20a, 20b, 20c arranged in a row are used as the electrodes. , The outer electrodes G3to and G4bo having the circular holes 21a, 21b and 21c closely fitted to the inner electrodes G3ti and G4bi, respectively.
0a, 20b, 20c and circular holes 21a, 21b, 21c
Are coaxial and the inner diameters φi of the cylindrical portions 20a, 20b, 20c are equal to the hole diameters φo of the circular holes 21a, 21b, 21c, the circularity of the root portion of the cylindrical portion is the same as the conventional electrode having the cylindrical portion. Even if the shape from the outer surface of the electrode to the cylindrical portion is deteriorated, it is possible to easily manufacture an electron gun having stable focus characteristics without distorting the shape of the beam spot on the phosphor screen.

That is, as described above, the three cylindrical parts 20
Inner electrode G having a, 20b and 20c arranged in a line
3ti, G4bi and the outer electrodes G3to, G4bo in which the circular holes 21a, 21b, 21c are formed, the outer electrodes G3to, G4bo are formed in the circular holes 21a, 21c.
The circularity of b, 21c and the circular holes 21a, 21b, 21c from the outer surface of the outer electrodes G3to, G4bo to the circular holes 21a, 21b, 21c.
The shape of the peripheral portion of a, 21b, and 21c can be easily manufactured with high precision. Moreover, the cylindrical portion 2 of the inner electrodes G3ti, G4bi
Roundness of 0a, 20b, 20c and inner electrodes G3ti, G4b
It is possible to eliminate the influence on the electric field of the main lens portion having a shape from the outer surface of i to the cylindrical portions 20a, 20b, 20c, and to obtain an electron gun having stable focus characteristics without distorting the shape of the beam spot. it can. Moreover, it is not necessary to manufacture the mold for molding the inner electrodes G3ti, G4bi with high precision as in the conventional case, while the outer electrodes G3to, G4
Since the mold for molding 4bo has a relatively simple structure,
It becomes easy to manufacture the die with high precision, and the die can have a long life.

In the above embodiment, the case where the third grid is the focusing electrode, the fourth grid is the final accelerating electrode, and the third and fourth grids forming these main lens portions are cylindrical electrodes have been described. The present invention can also be applied to the case where the electrode forming the main lens portion is a cup-shaped electrode.

In the above embodiment, the bipotential type electron gun having the third grid as the focusing electrode and the fourth grid as the final accelerating electrode has been described. However, the present invention is not limited to the bipotential type electron gun. It can also be applied to an electrode forming the main lens of an electron gun or a compound electron gun.

[0023]

According to the present invention, at least one of the plurality of electrodes forming the main lens unit for finally focusing the three electron beams arranged in a row from the electron beam generating unit on the phosphor screen is three.
In a color picture tube electron gun consisting of a cup-shaped or tube-shaped electrode having three cylindrical portions arranged in a row, through which the electron beams pass separately, three electron beams individually pass through the electrode having the cylindrical portion at the bottom. And an inner electrode formed with three cylindrical portions arranged in a row, and three circular holes arranged in a row coaxially with the three cylindrical portions of the inner electrode were formed in the bottom portion by fitting the inner electrodes. When configured with the outer electrode, the characteristics of the electrode with respect to the three electron beams are determined by the shape of the circular hole of the outer electrode and the peripheral portion of the circular hole extending from the outer surface of the outer electrode to the circular hole. Moreover, since the shape of the circular hole of the outer electrode and the peripheral portion thereof can be formed accurately and satisfactorily, distortion of the shape of the beam spot can be eliminated, and an electron gun having excellent focusing characteristics can be constructed. Moreover, with such a structure, it is not necessary to manufacture the mold for molding the inner electrode with high precision as in the conventional case, while the mold for molding the outer electrode has a relatively simple structure. It is easy to manufacture the mold with high precision, and it is possible to obtain a long life of the mold.

[Brief description of drawings]

FIG. 1 (a) is a cross-sectional plan view showing the configuration of an electron gun for a color picture tube which is an embodiment of the present invention, and FIG. 1 (b).
Is also a side view.

FIG. 2 (a) is a plan view showing the structure of the third grid, and FIG. 2 (b) is a sectional view thereof.

FIG. 3 (a) is a plan view showing a structure of an inner electrode of the third grid, and FIG. 3 (b) is a sectional view thereof.

FIG. 4 (a) is a plan view showing a structure of an outer electrode of the third grid, and FIG. 4 (b) is a sectional view thereof.

FIG. 5 is a diagram showing a configuration of a color picture tube.

FIG. 6 (a) is a plan view showing a structure of an electrode of a conventional electron gun for a color picture tube, and FIG. 6 (b) is a sectional view thereof.

[Explanation of symbols]

 20a, 20b, 20c ... Cylindrical part 21a, 21b, 21c ... Circular hole G1 ... 1st grid G2 ... 2nd grid G3 ... 3rd grid G3ti ... Inner electrode G3to ... Outer electrode G4 ... 4th grid G4bi ... Inner electrode G4bo ... Outer electrodes KB, KG, KR ... Cathode SC ... Shield cup

Claims (1)

[Claims] 1. At least one of a plurality of electrodes constituting a main lens unit for finally focusing the three electron beams arranged in a row from the electron beam generating unit on a phosphor screen, each of the three electron beams being In an electron gun for a color picture tube, comprising an electrode having three cylindrical portions arranged in a row and passing separately, the electrode having the cylindrical portion has three cylindrical portions arranged in a row through which the above three electron beams respectively pass. And an outer electrode fitted to the inner electrode and having three circular holes arranged in a row coaxially with the three cylindrical portions of the inner electrode at the bottom. An electron gun for color picture tubes.