JPH0750138A - Color picture tube - Google Patents

Abstract

PURPOSE:To extend the aperture of a main lens and to improve the assembly precision as well as the focusing characteristic of an electron gun by providing an auxiliary electrode and a support body, for which the electron beam passing holes of the upper focusing electrode and the positive electrode are punched out, on an elliptic thick plate. CONSTITUTION:The shorter diameter sides of electron beam passing holes 51A-51C as well as 61A-61C are extended by means of elliptic annular plate bodies 52 and 62 in the aperture of a main lens formed almost rotationally symmetric electric field which corresponds to the longer diameter can be formed by the aperture of a main lens in the range that an electron beam passes by choosing an appropriate level of the thickness of the plate bodies 52, 62. The passing holes 61A-51C, 61A-61C are formed by superimposing support bodies 501 and 602 on the back surfaces of auxiliary electrodes 500 and 600, for which only the holes of the same size as the holes 51A-51C of the electrode 50 and 61A-61C of the positive electrode 60 are punched out, on an elliptic thick plate. The mechanical strength of a main lens structure electrode is thus improved, and since the assembly precision is improved, the focusing characteristic is also improved.

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, and more particularly to a color picture tube having an in-line type electron gun with improved focus characteristics.

[0002]

2. Description of the Related Art Generally, the main lens aperture of an electron gun for a color picture tube has a great influence on the focus characteristic, and in order to obtain a suitable focus characteristic, the main lens aperture is made as large as possible,
It is also desirable to ensure mechanical strength to avoid deformation during the assembly process of the electron gun.

FIG. 1 is a cross-sectional view of the essential parts showing an example of a conventional bipotential focusing type in-line type electron gun. In the figure, 1A, 1B, and 1C are cathodes that respectively emit three electron beams from the top surface, 2 is a control electrode for controlling the electron beam, 3 is an accelerating electrode for accelerating the electron beam, and 4 is for focusing the electron beam. 2A, 2B, 2C, 3A, 3B, 3C and 4A, 4B, 4C are electron beam passage holes for three electron beams. Reference numeral 5 is an upper focusing electrode, and 6 is an anode. The upper focusing electrode 5 and the anode 6 are provided with three squeezing holes 5A, 5B, 5C and 6A, 6 facing each other on their bottom surfaces.
B and 6C form three main lenses corresponding to the three electron beams. In this case, the general operating voltage of the electron gun is 0 V to the control electrode 2, about 700 V to the acceleration electrode 3, about 7 KV to the lower focusing electrode 4 and the upper focusing electrode 5, and about 25 KV to the anode 6.

In such an electron gun configuration, the three electron beams A, B, and C, whose electron beam amounts are controlled by the signal potentials given to the three cathodes 1A, 1B, and 1C, are accelerating electrodes 3. After receiving a slight focusing action by a prefocus lens formed between each of the facing holes of the upper focusing electrode 5 and the lower focusing electrode 4, an image not shown is received by each main lens formed by the upper focusing electrode 5 and the anode 6. It is focused so as to form an image on the fluorescent surface of the tube. At the same time, the electron beams A and C on both sides are transmitted through the electron beam passage holes 6A and 6A of the anode 6, respectively.
The angle .theta.
The three electron beams A, B and C are converged at one point. In addition, 7 is a convergence electrode.

In the electron gun constructed as described above, the size of the image forming point on the fluorescent screen of the picture tube, that is, the focus characteristic, influences the sharpness of the image, so it is desirable to make it as small as possible. In addition, in order to improve focus characteristics, generally, the aperture of the main lens is increased.

[0006]

FIG. 2 shows the upper focusing electrode 5
FIG. 3 is a plan view of a main part showing the upper surface of FIG. In the figure, the diameter D
The three electron beam passage holes 5A, 5B and 5C are arranged in a straight line at intervals S in a straight line. The electron beam passage holes 5A, 5B, 5 for increasing the diameter of the main lens are provided as means for improving focus characteristics.
It is necessary to increase the diameter D of C. However, the electron beam passage holes 5A, 5B and 5C of the upper focusing electrode 5 formed by pressing a non-magnetic metal having a thickness of about 0.3 mm, such as a stainless steel plate, have withstand voltage characteristics with the anode 6 shown in FIG. For improvement, it is necessary to have a throttle hole structure. Further, in order to prevent deterioration of the rotational symmetry of the electric field of the main lens, the aperture depth l is required to be 1/2 or more of the diameter D of the holes. Limited to 1.0 mm smaller dimensions. Also, increasing the hole spacing S increases the convergence error at each point on the fluorescent screen during operation of the picture tube, and the horizontal dimension L between the upper focusing electrode 5 forming the main lens and the anode 6 is reduced. There is a problem that the withstand voltage characteristic deteriorates as the size increases and the inner wall of the valve neck accommodating the electron gun is approached.

In order to obtain good focus characteristics,
Roundness error of the beam passage holes 5A, 5B, 5C, etc. (major axis-
It is said that the minor axis) is preferably about 0.5% or less of the pore diameter D. Therefore, in the assembly of the electron gun, each electrode component is held on a jig (not shown) having three cores penetrating each beam passage hole, and the heated multiform glass 8 is pressure-bonded to the support body 9. Done. In this case, the three cored bars have an error in the hole pitch S and the hole diameter D of each electrode component, and therefore are set to be thinner than the hole diameter D by about 0.02 to 0.03 mm. Therefore, the deformation of the cup-shaped body is caused by the error at the time of manufacturing each electrode part and the stress at the time of crimping the multi-form glass 8, and the beam passage holes 5A, 5B, which are formed by the diaphragm holes,
The roundness error measured in a state in which it spreads over 5C and is removed from the jig is about 0.05 mm in an extreme case, that is, the hole diameter D.
== 3.9 mm, it may reach about 1.3%. As described above, there is a serious drawback that the electric field of the main lens is distorted due to the decrease in circularity, and astigmatism is generated in the electron beam, and the focus characteristic is impaired.

Therefore, the present invention has been made in view of the above-mentioned conventional drawbacks, and an object of the present invention is to reduce the above-mentioned side effects, enlarge the main lens aperture, and improve the electron gun assembly accuracy. Another object of the present invention is to provide a color picture tube having an electron gun with improved and improved focus characteristics.

[0009]

In order to achieve such an object, the present invention provides a color picture tube having an in-line type electron gun for generating three electron beams in-line on a common plane. The main lens is formed by two electrodes that are spaced apart, and each of the two electrodes is
At least an elliptical ring-shaped portion serving as a common envelope for the three electron beams, and an elliptical disk-shaped portion provided with a passage hole for passing each of the three electron beams, The elliptical plate-shaped portion has a central hole having an elliptical shape having a major axis in a direction perpendicular to the in-line direction, and the outer sides of the holes on both sides are arcs, and the elliptical ring-shaped portions face each other at intervals. The inner diameter of the elliptical ring-shaped portion in the in-line direction is substantially equal to the distance between the outer sides of both side holes of the elliptical plate-shaped portion.

[0010]

According to the above-mentioned means, the main lens aperture can be expanded as much as possible without causing side effects such as electrode processing problems and withstand voltage characteristics, so that the focus characteristics are improved and the electron gun is also improved. Assembling accuracy is also improved.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 3 shows an upper focusing electrode of an electron gun showing an embodiment of a color picture tube according to the present invention. FIG. 3 (a) is a plan view of a main part and FIG. 3 (b) is a sectional view thereof. In the figure, the upper focusing electrode 50 is configured by joining an oval plate member 51 having a thickness of about 2 mm, which is provided with three electron beam passage holes, and an oval ring plate member 52 having a thickness t. ing. And
The electron beam passage hole 51B in the center of the elliptical plate-like body 51 is an elliptical hole having a long diameter Dl and a short diameter Ds, and the electron beam passage holes 5 on both sides.
1A and 51C are holes that connect a semicircle of radius Dl / 2 on the outside and a semi-ellipse of the same size as the center hole 51B on the inside, and the centers of the holes are arranged at intervals S, respectively. By thus setting the minor axis direction of the elliptical plate-like body 51 as the major axis direction of the electron beam passage holes, the major axis Dl can be made larger than the hole pitch S. In addition, since the elliptical thick plate is pressed unlike the conventional throttle hole, the dimensions of the bridge portion between the electron beam passage holes 51A, 51B and 51C and the dimensions of the holes 51A and 51C on both sides and the outer long diameter end are also measured. Since it can be reduced to about 0.5 mm,
It is not necessary to increase the horizontal dimension L. However, when the main lens is formed only with such an elliptical plate-like body 51, the electron beam passage holes 51A, 51B, and 51C are elliptical and have irregular shapes in which semicircles and semi-ellipses are connected. The electron beam undergoes astigmatism that is strongly affected by the focusing action in the minor axis direction. Therefore, the elliptical ring plate 5
2 is provided for this correction. The oval ring plate-like body 52 has the same outer shape as the oval plate-like body 51, and has oval-shaped holes 52A connecting the semicircles similar to the both-side holes 51A and 51C of the oval-plate-like body 51, respectively. The semicircles of are aligned and joined to the main lens forming surface side.

FIG. 4 is a cross-sectional view of the main part of an electron gun in which an anode 60 having the same structure as the upper focusing electrode 50 is opposed to each other. In the figure, the diameter of the main lens is such that the short diameter sides of the electron beam passage holes 51A to 51C and 61A to 61C are widened by the oval ring plate members 52 and 62, so that the oval ring plate members 52 and 62 are widened. By selecting the thickness t to be an appropriate value, a substantially rotationally symmetric electric field corresponding to the major diameter Dl of the main lens aperture in the range through which the electron beam passes is formed.

In FIG. 4, the electron gun including the upper focusing electrode 50 and the anode 60 has a focusing electrode 50 and an anode 60.
Since the plate thickness for punching the electron beam passage holes 51A to 51C and 61A to 61C with high accuracy is about 2 mm,
If the hole diameter is about 4 mm or more, the thickness of about 1/2 or more cannot be satisfied, so that the hole 51A of the focusing electrode 50 is formed on the oval thick plate.
.About.51C and holes 61A to 61C of the anode 60, only the holes equivalent to the holes 61A to 61C are punched out, and the supports 501 and 601 are stacked on the back surfaces of the auxiliary electrodes 500 and 600.

According to this structure, the mechanical strength of the main lens-constituting electrode is strengthened, so that the shape will not be deformed by the stress due to the pressure bonding of the multi-form glass during the assembly of the electron gun. Therefore, the diameter of the main lens is equivalently enlarged, and the assembling accuracy is improved, so that the electron gun with improved focus characteristics can be obtained.

The convergence of the electron beams on both sides is shown by the plan view of the anode 60 in FIG.
The pitch S'of A and 61C is set to the both side holes 5 of the upper focusing electrode 50.
0.1 to 0.15, for example, than the pitch S of 1A and 51C
It can be performed by setting a large value in the range of mm. In this case, the electric fields of the main lenses on both sides are distorted, so that the electron beams A and C on both sides tend to be vertically longer than the central electron beam B. For this correction, for example, the minor diameter Ds ′ of the central elliptical hole 61B is made slightly larger than the minor diameter Ds of the central elliptical hole 51B of the upper focusing electrode 50,
The central electron beam B is vertically aligned to the same extent as the electron beams A and C on both sides, and the thickness t of the elliptical ring plate members 52 and 62 of the upper focusing electrode 50 and the anode 60 is modified to be slightly thicker. The electron beam shape of the book can be adjusted to be round.

When there is a difference in shape between the central electron beam B and the two side electron beams A and C, the central elliptical hole 51 of the upper focusing electrode 50 and the anode 60 shown in FIGS.
B and 61B minor radii Ds / 2 and Ds' / 2,
The three electron beams can be finely adjusted to be round by appropriately selecting the short-side radius Ds / 2 of the inner semi-ellipse of the both-side holes 51A, 51C and 61A, 61C.

In recent years, a color picture tube has a tendency that the diameter of the neck tube is reduced for the purpose of reducing the deflection power, and the electron gun accommodated therein is downsized so that the main lens aperture is reduced and the focus characteristic is improved. Therefore, the demand for improvement is extremely high. For this reason, the main lens dimensions of the electron gun currently manufactured with a neck diameter of about 22.5 mm are hole pitch S = 4.75 mm and hole diameter D = 3.9 mm. Focusing electrode 50
Is hole pitch S = 4.75 mm, major axis Dl = 5.0 mm,
Minor diameter Ds = 4.0 mm, anode 60 has hole pitch S ′ = 4.
85 mm, major axis Dl = 5.0 mm, minor axis Ds' = 4.3
At 0 mm, the thickness of the elliptical ring plates 52 and 62 is t = 1.2 mm, and the equivalent main lens aperture is 5.0 mm, which is about 1.3 times larger than that of the conventional electron gun. The focus characteristics could be improved to be almost equal to those of a color picture tube having a large size of 29 mm.

The elliptical plate members 51, 61 and the elliptical ring plate members 52, 62 constituting the upper focusing electrode 50 and the anode 60 are limited in plate thickness and have a large hole diameter when manufactured by a press working method. In case of about 1/2 of required hole diameter
Although it was difficult to integrally form the above-mentioned thickness, a thick metal component can be easily obtained by the powder metallurgy method of compressing and then sintering the metal powder. The formation of the plate-like body constituting each of the electrodes 50 and 60 by the powder metallurgy method is performed by press-molding with a predetermined die by adding a binder such as acrylic resin to metal powder such as stainless steel as a non-magnetic material, and vacuum forming. After pre-sintering at 600 to 700 ° C in a medium or reducing atmosphere, further sintering in a vacuum at 1200 to 1300 ° C or in a reducing atmosphere, and re-pressing the minute dimensional change due to sintering with a finishing die. As a result, it is possible to obtain a highly accurate component that surpasses the conventional thin plate pressed component.

FIG. 6 shows an upper focusing electrode of an electron gun showing another embodiment of the color picture tube according to the present invention. FIG. 6 (a) is a plan view of a main part and FIG. 6 (b) is a sectional view thereof. . In the figure, three electron beam passage holes 54A and 54 similar to those in FIG. 3 are provided in the elliptical plate-like body 54 which constitutes the upper focusing electrode 53.
B and 54C are provided, and a groove 54D having a width W and a depth h is provided on the surface on the oval ring plate-like body 55 side. In such a configuration, the width W of the groove 54D is equal to or less than the major axis Dl of the hole, and the depth h is also astigmatic by selecting an appropriate value in relation to the thickness t ₁ of the elliptical ring plate member 55. Aberration can be corrected.

The shape of the groove 54D may be formed by a plurality of curved lines or straight lines.

FIG. 7 shows an upper focusing electrode of an electron gun showing still another embodiment of the color picture tube according to the present invention. FIG. 7 (a) is a plan view of a main part and FIG. 7 (b) is a sectional view thereof. is there.
In the figure, the upper focusing electrode 56 is composed of an elliptical plate 57 and an elliptical ring plate 58 having three electron beam passage holes 57A, 57B and 57C similar to those in FIG. . In such a configuration, the oval ring plate-like body 58
58A of the elliptical plate 57 is formed on both sides 57A and 5A.
Although a semicircle slightly larger than the outer semicircle of 7C is formed as a hole, astigmatism can be similarly corrected.

Although the bipotential focusing type electron gun has been described in the above-mentioned embodiments, the present invention is not limited to this, and other electron guns such as unipotential type and multi-stage focusing type electron guns can be used. Needless to say, the same effect as described above can be obtained even when applied to the main lens forming electrode.

[0024]

As described above, according to the color picture tube according to the present invention, the main lens aperture of the electron gun can be enlarged without any side effects such as electrode processing problems and withstand voltage characteristics. Therefore, it has an extremely excellent effect that the focus characteristic is improved and an image with high sharpness can be obtained.

[Brief description of drawings]

FIG. 1 is a main-portion cross-sectional view showing a structure and an operating state of a conventional in-line type electron gun.

FIG. 2 is a main part plan view showing a conventional upper focusing electrode.

FIG. 3A is a plan view of a main part showing an upper focusing electrode of an electron gun relating to a color picture tube according to the present invention, and FIG. 3B is a cross-sectional view of the main part.

FIG. 4 is a cross-sectional configuration diagram of main parts of an electron gun showing an embodiment of the color picture tube according to the present invention.

5A is a plan view of the anode shown in FIG. 4, and FIG. 5B is a sectional view thereof.

FIG. 6 (a) is a plan view of a main part showing another embodiment of the upper focusing electrode according to the present invention, and FIG. 6 (b) is a sectional view thereof.

FIG. 7A is a plan view of a main part showing still another embodiment of the upper focusing electrode according to the present invention, and FIG. 7B is a sectional view thereof.

[Explanation of reference numerals] 50, 53, 56 ... Upper focusing electrode 51, 54, 57 ... Oval plate-like body 51A, 51B, 51C, 54A, 54B, 54C, 5
7A, 57B, 57C ... Electron beam passage hole 52, 55, 58 ... Elliptical ring plate-like body 52A, 55A, 58A ... Ellipse hole 54D ... Groove 60 ... Anode 61 ... Oval plate-like body 61A, 61B, 61C ... Electron beam passage hole 62 ... Oval ring plate-like body 62A ... Oval hole 500,600 ... Auxiliary electrodes 501,601 ... Support.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akio Yamaguchi 3300 Hayano, Mobara-shi, Chiba Hitachi Ltd. Mobara factory

Claims (6)

[Claims] 1. A color picture tube having an in-line type electron gun for generating three electron beams in-line on a common plane, wherein a main lens of the electron gun is formed by two electrodes which are spaced apart from each other, and Each of the electrodes has an elliptical ring-shaped portion serving as a common envelope for the three electron beams, and an elliptical plate-shaped portion provided with a through hole for passing each of the three electron beams. The elliptical plate-shaped portion is an elliptical shape having a central hole having a major axis in a direction perpendicular to the in-line direction, and the holes on both sides are arcuate in outer directions, and the elliptical ring-shaped portions are mutually A color picture tube having an in-line type electron gun, which is opposed to each other at a distance. 2. The in-line type electron gun according to claim 1, wherein the holes on both sides of the elliptical plate-like portion are deformed circular shapes having a compound curvature in which the outer curvature is smaller than the inner curvature. A color picture tube having. 3. A color picture tube having an in-line type electron gun according to claim 2, wherein the major axis of the central hole and the major axis of the side hole are substantially equal to each other. 4. A collar having an in-line type electron gun according to claim 3, wherein the elliptical plate-shaped portion has a groove in the in-line direction on the side of the joint surface with the elliptical ring-shaped portion. Picture tube. 5. The inner diameter of the elliptical ring-shaped portion in the in-line direction is substantially equal to the distance between the outer sides of the both side holes of the elliptical plate-shaped portion, and the in-line direction of the elliptical ring-shaped portion. 4. A color picture tube having an in-line type electron gun according to claim 3, wherein the inner diameter in the direction perpendicular to the direction substantially coincides with the major diameter of the central hole or both side holes of the elliptical plate-shaped portion. 6. The inner diameter of the elliptical ring-shaped portion in the in-line direction is larger than the distance between the outer sides of the both side holes of the elliptical plate-shaped portion, and is equal to the in-line direction of the elliptical ring-shaped portion. 4. A color picture tube having an in-line type electron gun according to claim 3, wherein an inner diameter in a direction perpendicular to the right-hand side is larger than a long diameter of the central hole or both side holes of the elliptical plate-shaped portion.