JPS61131342A - Electron gun for color picture tube - Google Patents

Abstract

PURPOSE:To obtain an electron gun, having a main lens enlarged aperture and capable of having a slantly directional non-point aberration removed, by moving back correcting electrode plates and forming the shape of lens-forming-opening parts in three-series circle. CONSTITUTION:On the facing sides of electrodes 30 and 40, with each end being bent inside with a bending height H, each of three-series circular openings 311 and 411 is formed respectively in the shape in which three circular holes are piled up and communicated to each other at the neighboring regions. The center distance between circles is identical with the arranging distance S on the beam point. Inside cup electrodes 31 and 41, correcting electrode plates 33 and 43 are installed, by welding assembly, vertically to the tube axis direction and at the position in which they are moved back in the direction apart from the respective facing sides, by the assigned distances d1 and d2. The correcting electrode plates 33 and 43 respectively consist of an elliptic opening 331, which is longer in the vertical direction and providing a passage for the central electron beams, and semi-elliptic openings 332 of cutting shape, which is longer in the vertical direction and surrounding almost half the peripheral regions of both side beams. The distance between the center of the semi-elliptic openings 332 and that of the elliptic opening 331 is identical with the S distance.

Description

Detailed Description of the Invention [Field of Application of the Invention] The present invention relates to an electron gun for a color picture tube, and in particular to a main electron gun of an in-line type electron gun that emits three electron beams in a line, which is attached to a Shabiwa mask type color picture tube. The present invention relates to the structure of an electrode forming a lens portion.

[Background of the invention]

Conventionally, as an electron gun for color picture tubes of this type with improved resolution, for example, Japanese Patent Application Laid-Open No. 57-103246
As shown in the publication, the opposing main lens electrodes each have a peripheral rim on the opposite side thereof, and an elliptical lens space is formed by the recess between the peripheral rim and the aperture forming surface that is set back. There is a known method to do this.

In this method, the potential on the electrode side facing the elliptical lens space penetrates deeply, forming one lens with a large diameter, which can reduce spherical aberration, thereby reducing the electron beam spot diameter. However, since the focused electric field penetrates through the elliptical space, astigmatism occurs due to the slot effect here.

As a solution to this problem, a horizontal slot-shaped opening is separately provided at the exit of the G electrode in order to correct the astigmatism.
Even though astigmatism in both the horizontal and vertical directions has been corrected, the problem of astigmatism in the diagonal direction has been left unaddressed.In addition, the addition of electrode parts for forming slot-shaped apertures has made it difficult to assemble the electron gun. There was also the problem that the complexity led to an increase in manufacturing costs.

[Purpose of the invention]

The present invention has been made in view of these circumstances, and its object is to have an enlarged main lens aperture.

Moreover, it is an object of the present invention to provide an electron gun for a color picture tube that can eliminate oblique astigmatism, which has not been eliminated so far, without adding any electrode parts.

[Summary of the invention]

In order to achieve such an object, the present invention.

A pair of opposing main lens electrodes is configured by being separated into a cylindrical electrode and a correction electrode plate disposed within the cylindrical electrode by retracting it so as to move away from the opposing surface of the cylindrical electrode, and the cylindrical electrode has While a vast lens space is ensured by a single aperture, the aperture has a triple circular shape in which three circular holes communicate with each other along the direction in which the electron beams are arranged.

[Embodiments of the invention]

FIG. 1 shows the main lens electrode structure of an embodiment in which the present invention is applied to a pipotential type electron gun. The figure (,) is a sectional view taken along a plane including the tube axis direction and the arrangement direction (horizontal direction) of the three electron beams, and the figure (b) is the tube axis direction and the tube axis direction and the arrangement of the electron beams. direction and the direction perpendicular to (
(c) is a front view of the electrode when viewed from the electrode side, and (d) is a cross section corresponding to the d-d section of Fig. 6). Figure, same figure (,) is 08
This is a partially cutaway perspective view showing an example of how the correction electrode plate is attached to the electrode.

In the same figure (a), the G8 electrode 30 and the G4゛ awakening electrode 40 face each other with an interval g, and the G8 electrode 30 is a cylindrical electrode (
The electrode 40 consists of a welded assembly of a cup electrode 31 (hereinafter referred to as a cup electrode) and a lower trough 32, and the electrode 40 is provided with a 7-fold cup 50 on the upper part of the cup electrode 41.

On the opposing surfaces of G, G, and fi poles 3G and 40, the edges were bent inward at a bending height H, and three circular holes overlapped and communicated between adjacent parts. It has one triple circular aperture 311, 411. These three circular apertures 311 and 411 have exactly the same dimensions, and the distance between the centers of each circle matches the array interval S of the beam passages. Additionally, G8 and 04 cup electrodes 31.41
Inside, correction electrode plates 33 and 43 are provided by welding and assembling perpendicularly to the tube axis direction at positions spaced apart from each other by a predetermined distance d1+dl from the opposing surfaces. As shown in the same figure (, ), this correction electrode plate 33, 43 has a vertically long elliptical opening 331 that serves as the center electron beam path among the three electron beams, and a periphery of the beams on both sides. It has a semi-elliptical opening 332 in the form of a vertically long notch that surrounds approximately half of the opening, and the distance between the center of the semi-elliptic opening 332 and the center of the elliptical opening 331 matches the S dimension.

Note that the four circular holes 333 serve as assembly standards when assembling the cup electrode and the correction electrode plate by welding. G.
The correction electrode plate 43 on the electrode side also has a completely similar configuration.

In the above configuration, the correction electrode plates 33 and 43 are moved back from each other, which has the effect of enlarging the main lens aperture and reducing spherical aberration. That is, in the same figure (b), the counter electrode potential penetrates deeply in the spatial region including the triple circular openings 311, 411 extending from the electrode opposing end face to the correction electrode plate 33, 43.

A vast lens space is formed. In other words, the G4 electrode potential enters the G electrode lens space area 312, and the G electrode potential enters the G electrode lens space area 412 continuously into the triple circular apertures 311 and 411, respectively. For.

A much larger lens aperture can be obtained compared to the three independent cylindrical lenses formed by the main lens electrode of a conventional general electron gun.

Next, the relationship between the astigmatism that occurs when such an electron beam passes through the main lens aperture region and the aperture shape will be explained using FIG. 2. The figure (-) is an electrode plan view showing three independent cylindrical lenses commonly used in the past, and in this aperture, astigmatism does not occur due to its cylindrical shape. On the other hand, FIG. 6B is a plan view showing the shape of the aperture of the electron gun main lens electrode described in the document mentioned above as a known example.

In this case, the focused electric field is continuous in the aperture region of the oblong recess,
The electron beam passing through this area has a circular aperture, and the distance from the center of the electron beam to the outer line is different in each direction. Since the shapes are not all equal, that is, symmetrical about the axes in each direction, astigmatism occurs in the horizontal, vertical, and oblique directions. For example, in this hole shape, the vertical dimension V is smaller than the horizontal dimension, so
The lens strength of the main electron lens produces a slot effect that is stronger in the vertical direction than in the horizontal direction. As mentioned earlier, we attempted to correct this by creating a separate horizontal slot-shaped opening and making the diverging lens effect there stronger in the vertical direction than in the horizontal direction. However, in any case, astigmatism in the oblique direction remains.

On the other hand, the same figure (,) is a plan view showing the aperture shape of the main lens electrode in the embodiment of the present invention, in which the large-diameter lens forming area is shaped like a triple circle. Therefore, in the oblique direction, each point on the outer shape is at the same distance TK from the center through which the electron beam passes, and no astigmatism occurs, except for the nine continuous portions where the three circular holes overlap each other. In other words, no means for astigmatism correction is required in the oblique direction.

In order to correct astigmatism in a range outside these areas, that is, in the horizontal and vertical directions, similar to the case shown in FIG. In .43, the central electron beam passage aperture is a vertically long elliptical opening 331,431, and the inner half of each side beam passage aperture is formed by a vertically long notch-shaped semi-elliptical aperture 332.432. . This results in
The lens strength in the correction electrode plate is stronger in the horizontal direction than in the vertical direction, and by appropriately setting the ratio of the major axis and minor axis of the ellipse dimension, it is possible to balance the aforementioned vast lens space area and make it possible to Point aberrations are removed. In addition, G3. G
The inward bending of the edges of the triple circular apertures 311.411 that each of the four cup electrodes 31.41 has is intended to enhance the high voltage characteristics of the electron gun electrode. It is also effective in increasing the strength of the 41 parts.

Here, the silent convergence method of statically converging the two outer beams onto the center beam in this embodiment will be explained while comparing it with a conventional example.

First of all, FIG. 3 is intended to explain the silent convergence method in a conventionally known electron gun.
It is slightly wider than the width B of the recess 121 of the electrode 120. When the width of the concave portion of the 04 electrode is displaced to be larger than the width of the concave portion of the 03 electrode in this way, the beams on both sides are bent inward due to the tilted electrostatic lens action between the opposing end surfaces of both electrodes.
The well-known silent convergence takes place. At this time, the amount of bending is A,! :H ratio is constant, generally G3 electrode 120
The width B of the recess 121 of the G4 electrode 11G is kept constant, and the width A of the recess 111 of the G4 electrode 11G is used depending on the screen size of the color picture tube. Therefore, a different G4 electrode component is required for each displacement amount, in other words, for each screen size, resulting in the problem of increased electrode component manufacturing cost. Note that in the conventional example, the depths of the recesses indicated by the two dimensions are the same for both the G3 and G4 electrodes.

On the other hand, FIG. 4 is for explaining the silent convergence method in the electron gun of this embodiment, and shows G3 in FIG.
, This is a sectional view corresponding to an enlarged view of the facing part of the G4 electrode, but in the same figure, the amount of retraction d of the correction electrode plate 33 on the G3 electrode side is 3, while the correction electrode plate 43 on the G4 electrode side The amount of retreat is d s -2. In this case, as mentioned above, the counter electrode potential penetrates deeply into each of the three circular apertures and the space area following it, forming a vast lens space. , due to the influence of the walls of the edges of the triple circular apertures, the penetration of the counter potential becomes shallower than in the vicinity of the central beam passage opening. As a result, since the electron beams on both sides of 1 encounter the inclined equipotential lines 60 in the vast lens space of the G3 electrode, they are concentrated by the inclined electrostatic lens action here, and the outer electron beams 8.10 bend inward. However, in this case, as in the conventional example, the retraction amount d on the 04 electrode side matches do (d, -d
1=F), even if the electron beams 8 and 10 are bent inward at the G3 electrode, they encounter similarly inclined equipotential lines 70 in the vast lens space of the G4 electrode. The above-mentioned inward concentration effect is offset by the diverging lens effect. Therefore, in this embodiment, d is changed to dl
1Ial+ shallower than that of the G4 electrode, and the slope of the equipotential line 70 in the G4 electrode side spatial region is made gentler than that of the G3 side equipotential line 60. As a result, the beam concentrating effect on the G3 electrode side becomes dominant over the beam diverging effect on the G4 electrode side, resulting in quiet convergence. Even if the screen size of the receiver tube changes, the retraction amount dl +
This can be handled by selecting G appropriately.

In this way, in this embodiment, static convergence suitable for each screen size is performed by changing the amount of retraction of the correction electrode plate, so the dimensions of the triple circular openings of the cup electrode are independent of the screen size. However, it is possible to use uniform electrode parts.

This has a very large effect in reducing the manufacturing cost of electrode parts.

In other words, container-shaped parts such as cup electrodes.

It is generally produced by press drawing processing, but the press mold used to produce this type of drawn parts is used for punching parts made by punching out a simple flat plate, such as a correction electrode plate. Since it requires a large number of processing steps, the mold production cost is several times higher. Therefore, in this embodiment, the manufacturing cost of the correction electrode plate itself is added, but since the correction electrode plate can be made of uniform parts regardless of the screen size like the cup electrode, the manufacturing cost can be reduced compared to the conventional example. We were able to reduce this by approximately 50%.

Note that the auxiliary electrode plate 33 does not necessarily have to be integrally molded from the beginning into the shape shown in FIG. It goes without saying that the structure may be constructed by dividing or dividing into three parts and assembling such parts.

In addition, there is another method for astigmatism between the horizontal and vertical directions.
For example, if the above-mentioned slot-shaped opening is provided to solve the problem, a circular electron beam passage opening 331B such as 33B shown in FIG. 6 may be used. The same applies to the auxiliary polarization plate 43.

〔Effect of the invention〕

As explained above, according to the present invention, by retracting the correction electrode plate, resolution is improved by enlarging the lens aperture of the main lens electrode, and the shape of the large-diameter lens forming aperture is made into a triple circular shape. By doing so, it is possible to correct astigmatism in the oblique direction. For example, by making the aperture of the correction electrode plate elliptical with a long vertical direction, astigmatism between the horizontal and vertical directions can be further corrected. It is possible to obtain a spot without distortion. Further, in this case, all astigmatism correction is performed within the main lens electrode, and no separate correction parts are required, so that the electron gun assembly is not as complicated as in the past.

Further, the opposing cylindrical electrodes may have exactly the same dimensions including the triple circular apertures.

In addition, since it may be constant regardless of the screen size, manufacturing costs can be reduced.

[Brief explanation of the drawing]

Figures 1 (,) and (b) are cross-sectional views of the main lens' polarization showing an embodiment of the present invention, Figures (,) are front views of main parts, and Figures (d) are cross-sectional views. (,) is a partially cutaway perspective view, 112
The figure is a diagram to explain the difference in the effect depending on the aperture shape of the main lens forming part, Figures 3 and 4 are diagrams to explain silent convergence, and Figures 5 and 6 are diagrams of the correction electrode plate. A front view showing another configuration example. 31.41...Cup electrode (cylindrical electrode). 33, 33A, 33B, 43... Correction electrode plate, 311, 411... Triple circular opening, 312
, 412...lens space area, 331, 431
...Oval opening, 332, 432...Semi-elliptical opening (notch). Figure 1 (Q) (C) ■ Figure 2 (Q) (b) (c) Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] A collar comprising an electron beam source that emits one or three electron beams in a line, and a main electron lens unit that focuses the electron beam from the electron beam source onto a phosphorescent surface. In the picture tube, the main electron lens section has two cylindrical electrodes that are arranged facing each other at a constant interval in the tube axis direction, and each of these cylindrical electrodes has an edge on the opposing surface side. A single 3-hole structure with the sections bent inward and three circular holes overlapping at adjacent ends.
A series of circular apertures are provided, and a space inside the cylindrical electrode following the apertures is spaced apart from the tip of the bent portion and perpendicular to the tube axis direction, and together with the three series of circular apertures constitutes an electron beam passage opening. An electron gun for color picture tubes characterized by having an auxiliary electrode plate arranged therein. 2. The electron gun for a color picture tube according to claim 1, wherein the triple circular apertures of the pair of opposed cylindrical electrodes have the same size. 3. The auxiliary electrode plate has an elliptical aperture having a long diameter in a direction perpendicular to the arrangement direction of the electron beams, which serves as a path for the central electron beam among the three electron beams, and the above-mentioned aperture that surrounds approximately half the circumference of the electron beams on both sides. It is characterized by comprising a semi-elliptical notch having a long axis in the vertical direction, and electron beam paths on both sides are formed by the notch and both ends of the triple circular opening of the cylindrical electrode. An electron gun for a color picture tube according to claim 1.