JPS6329377B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun, and more particularly to an electron gun that is attached to a shadow mask type color picture tube and that constitutes a main electron lens section of an electron gun that emits three electron beams arranged in a row. This relates to the structure of the electrode.

A shadow mask type color picture tube focuses three electron beams emitted from an electron gun mounted inside the net onto a phosphor screen via a shadow mask, and reproduces a color image on the phosphor screen. .

The above-mentioned electron gun is a bipotential type,
Unipotential type, tripotential type, etc. have been developed, and each type of electron gun has a main electron lens, and the thermionic electrons emitted from the cathode are turned into an electron beam, which is focused onto a phosphor screen by the main electron lens. It's becoming like that. This main electron lens is an electrostatic lens, and like an optical lens, its main performance is determined by the diameter of the lens.

Generally, the maximum diameter of the main electron lens of an electron gun is determined by the inner diameter of the net of the shadow mask type color picture tube and the structure of the electron gun. In this case, the limit is about 30% of the inner diameter of the neck, and furthermore, in the case of an electron gun arranged in a single row and having a one-piece structure, the limit is about 28% of the inner diameter of the neck.

That is, the maximum diameter of the main electron lens relative to the inner diameter of the net is small as described above, and recently there has been a demand for color picture tubes to have a smaller neck diameter as a means of reducing the deflection power. The maximum diameter of the electronic lens also becomes smaller. Therefore, the aberration of the electron lens increases, which increases the spread component of the electron beam, which is one of the factors that worsens the focusing of the electron beam on the phosphor screen.
It's becoming one.

Next, an example of a color picture tube device is shown in Figures 1 and 2.
As shown in the figure. That is, a face plate 2 has a phosphor screen 1 formed of dot-shaped or band-shaped phosphor layers that emit light in red, green, and blue colors, and is connected to a side wall 3 of this face plate 2 via a funnel 4. an electron gun 6 that generates three electron beams and is housed in the network 5; a stem pin 7 that applies a predetermined voltage to the electron gun 6;
A magnet 8 for adjusting the power and static convergence is arranged on the outer wall of the net 5 opposite to the electron gun 6.
, a deflection device ₉₁ attached to the outer wall from the funnel 4 to the neck 5, and a shadow mask 10 disposed opposite to the phosphor screen 1 at a predetermined distance.

The electron gun 6 consists of a plurality of electrodes and a plurality of glass support rods that support the electrodes, and the plurality of electrodes include three cathodes 6 _K1 , 6 _K2 , 6 _K3 , a first grid 6 ₁ , 2nd grid 6 ₂ , 3rd grid 6 ₃ ,
A fourth grid ₆₄ is implanted and fixed to the glass support rod in this order.

The three cathodes 6 _K1 , 6 _K2 , and 6 _K3 emit three electron beams 14 , 15 , and 16 onto the same plane.

The first grid 6 ₁ and the second grid 6 ₂ are planar electrodes arranged close to each other, each having three through holes aligned with the paths of the respective electron beams.

The third grid 6 ₃ is arranged close to the second grid 6 ₂ and consists of two joined cups 6 ₃₁ and 6 ₃₂ , and the closed end of this cup has three cups aligned with the path of each electron beam. The opening of the first cup 6 ₃₁ is equal to or slightly larger than the corresponding opening of the second grid 6 ₂ , and the opening of the first cup 6 ₃₁ is equal to or slightly larger than the corresponding opening of the second grid 6 2 . The hole is larger than the through hole of the first cup ₆₃₁ .

The fourth grid ₆₄ is formed from one cup having three through holes at its closed end, and the central through hole among the through holes is connected to the first grid _61.
to the third grid ₆₃ , and the other two holes are each slightly offset outwardly from the central hole. This eccentricity is necessary to focus the three electron beams on the electron beam hole in the shadow mask.
This is so that the electron beams 14 and 16 on both sides except for the electron beams 5 are deflected by a slightly asymmetric electric field.

This fourth grid ₆₄ is further fitted with three through holes aligned with each electron beam path and a cylindrical shield cup ₆₅ with a bottom bored at the bottom thereof.
Three valve spacers 17 projecting outward are attached to the side wall of this shield cup ₆₅ .

The aforementioned electron gun 6 is installed inside the network 5, and a high voltage from the anode terminal is applied to the fourth grid ₆₄ via the internal conductive film, the valve spacer 17, and the convergence cup ₆₅ , and the other A predetermined voltage is applied to the electrode from outside the tube via the stem pin 18, so that a main electron lens is formed between the third grid ₆₃ and the fourth grid ₆₄ .

FIG. 3 is a view of the through hole on the main electron lens side of the third grid ₆₃ , viewed from the fourth grid ₆₄ side.
Each electron beam hole 2 bored in the plane part 21
2, 23, and 24 have a perfect circular shape or a shape close to a perfect circle, and these electron beam apertures 22, 2
The diameter 25 of each electron beam hole 22, 24 is primarily defined by the inner diameter of the neck 5, and furthermore, for reasons of electrode manufacturing, the diameter 25 of each electron beam hole 22, 23,
24 and a center-to-center distance 26 .

For example, in a color picture tube with a net outer diameter of 29.1 mm, due to the above-mentioned regulations, the diameter of each electron beam aperture 22, 23, 24 of the electron gun inserted into the net is the same as that of the electron beam aperture. Center distance of 6.6
When expressed as mm, the maximum limit is 5.5 mm.
This is mainly caused by the bridge 2 between the electron beam apertures.
This is due to the machining requirements when forming 7. For this reason, the diameter of the electron lens cannot be made sufficiently large, and it has been difficult to reduce the spherical aberration of the electron lens.

The present invention has been made in view of the above-mentioned conventional problems, and in order to increase the diameter of the electron lens, the diameter of the hole in the electron beam hole is made larger than the diameter of the hole in the same plane direction.
By increasing the aperture diameter in the direction perpendicular to this and making the shape like this, the diameter of the electron lens increases, but the electron beam with astigmatism is created by making the electron beam's low potential electrode and relative to it. It is an object of the present invention to provide an electron gun that can be corrected by changing the aperture ratio of the above-mentioned electron beam aperture of a high potential electrode provided therein.

In other words, in the present invention, in an electron lens formed by two electrodes, a low potential electrode and a high potential electrode, a strong focusing effect works in the low potential part and a weak divergent action works in the high potential part. Astigmatism is corrected in the high potential section.

Next, an embodiment of the electron gun of the present invention will be described.
The components other than the opposing electrodes forming the main electron lens are substantially the same as those of a conventional electron gun, so illustrations and explanations will be omitted.

Next, the low potential side electrode, ie, the third grid 40, adapted to one embodiment of the electron gun of the present invention will be explained with reference to FIG. 4, and the high potential side, ie, the fourth grid 50, will be explained with reference to FIG.

First, in FIG. 4, the third grid 40 is the plane part 4.
Each electron beam hole 42, 43,
The diameter of the hole 44 is defined by the horizontal axis connecting the centers of these electron beam holes, that is, the intersection line of the plane where the three electron beams are arranged and the plane part 41, the X ₁ -X' ₁ axis, and this X ₁ -
When the vertical axis that is perpendicular to the X′ ₁ axis and passes through the central electron beam hole 43 is the Y ₁ −Y′ ₁ axis, the hole diameter b ₁ in the Y ₁ −Y′ ₁ axis direction is the diameter of each electron beam hole. 42,43,4
4, and s ₁ and the hole diameter a ₁ in the X ₁ -X' ₁ axis direction of each electron beam hole 42, 43, 44 are approximately equal, and b ₁ / _a It has a track field shape formed so that ₁ = 1.06 or more. In this case, each electron beam aperture 42,
Shielding plates 45 and 46 made of other members are provided in the overlapping portions of 43 and 44, and the shielding plates 45 and 46 are provided on the end surfaces of the electron beam passage portions 42 and 44 on the X ₁ -X′ ₁ axis. The electron beam passage portion 4 has a length of 46.
It has been removed from 2.44.

Next, on the high potential side, that is, the fourth grid 50 shown in FIG. , that is, the intersection line of the plane on which the three electron beams are arranged and the plane part 51 is defined as the X ₂ -X′ ₂ axis,
When the vertical axis that is perpendicular to this X ₂ −X′ ₂ axis and passes through the central electron beam hole 53 is the Y ₂ −Y′ ₂ axis, Y ₂ −
The hole diameter b ₂ in the Y′ _2- axis direction is for each electron beam passage portion 52,
The distance between the centers of 53 and 54 is greater than s ₂ , and s ₂
and X ₂ − of each electron beam aperture 52, 53, 54
The aperture diameter a ₂ in the X' _2- axis direction is approximately equal, and b ₂ /a ₂ is the astigmatism caused by the non-circular electron beam passage part of the third grid on the low potential side as shown in Fig. 4. In order to eliminate aberrations, the track field is formed to be larger than b ₁ /a ₁ by 2% or more. In the electron beam formed by two electrodes, a low potential part and a high potential part, there is a strong focusing effect in the low potential part and a weak diverging effect in the high potential part, so the astigmatism generated in the low potential part This is because it can be corrected in the high potential section.

In addition, a shielding plate 5 made of other material is provided at the overlapping portion of each electron beam aperture 52, 53, 54.
5 and 56 are provided, and the electron beam through hole 5
As in the case of FIG. 4, the X ₂ -axis end faces of Nos. 2 and 54 are removed from the electron beam apertures 52 and 54 by the length of the shielding plates 55 and 56.

By forming the main electron lens with the third grid 40 and the fourth grid 50 as described above, the main electron lens aperture becomes large, and an electron gun structure is obtained that emits an electron beam with little astigmatism and spherical aberration. I can do it.

Next, to describe a specific example, the hole diameters of the electron beam holes of the first grid and the second grid are
0.67 mm, the hole diameter of the electron beam passage part of the first cup of the third grid is 1.7 mm, and the hole diameter a 1 of the second cup of the third grid, that is, the _one in FIG. 5, is 6.57 mm.
The hole diameter b ₁ is 6.96 mm, the hole diameter a ₂ of the fourth grid, that is, the one in Fig. 6, is 6.77 mm, the hole diameter b ₂ is 7.31 mm, the length of the third grid is 14.3 mm, and the distance between the third grid and the fourth grid. 1.0mm, for example, on the 4th grid.
Good results were obtained when 25KV was applied to the third grid, 5KV was applied to the third grid, and other predetermined voltages were applied to the other electrodes.

Although the above-mentioned embodiment has been described with respect to a bipotential type electron gun structure, it can also be applied to a tripotential type, quadrapotential type, etc. electron gun structure. Of course, a cylindrical body may also be provided.

[Brief explanation of the drawing]

Fig. 1 is an explanatory sectional view showing a typical example of a color picture tube, Fig. 2 is an enlarged sectional view of the vicinity of the electron gun structure in Fig. 1, and Fig. 3 shows the third grid in Fig. 2 facing the fourth grid. 4 and 5 are diagrams showing electrodes adapted to an embodiment of the electron gun assembly of the present invention, and FIG. 4 is a plan view of the third grid, and FIG.
The figure is a plan view of the fourth grid. 6 ₃ , 50 ... 3rd grid, 6 ₄ , 60 ... 4th grid, 22, 23, 24, 42, 43, 4
4, 52, 53, 54...Electron beam hole.

Claims (1)

[Scope of Claims] 1. Three electrodes arranged on the same plane and forming a main electron lens that emits three electron beams at the center and on both sides and focuses the electron beams, each of which has a predetermined hole diameter. In an electron gun constituted by a one-piece structure having an electron beam passage section, the diameter of the hole in the same direction as the plane of the electrode on the low potential side of the pair of electrodes forming the main electron lens. is a ₁ , the distance between the centers of adjacent electron beam holes is s ₁ , the hole diameter in the direction perpendicular to the plane is b ₁ , and the electrode on the high potential side of the pair of electrodes forming the main electron lens is When the diameter of the hole in the same direction as the plane is a ₂ , the distance between the centers of adjacent electron beam holes is s ₂ , and the diameter of the hole in the direction perpendicular to the plane is b ₂ , b ₁ /a ₁ >1.06 s ₁ ≒a ₁ An electron gun characterized in that b ₂ /a ₂ >b ₁ /a ₁ +0.02 s ₂ ≒a ₂ is satisfied.