JP2966053B2 - Electron gun for color picture tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-run type electron gun which is mounted on a shadow mask type color picture tube and emits three electron beams in a line in a horizontal direction. The present invention relates to an in-line type electron gun for a color picture tube having an improved structure of a pair of cylindrical electrodes constituting a main electron lens.

[Prior Art] Generally, in this type of electron gun for a color picture tube, at least two cylindrical electrodes (for example, G3 and G3 of a BPF type electron gun) are used.
4 electrodes or G5 and G6 electrodes of EA-UB and EA-DF electron guns)
Are arranged so as to face each other with the gap therebetween.

FIG. 4 shows a configuration example of a BPF (bipotential focus) type electron gun as an example of a general electron gun for a color picture tube to which the present invention is applied. The electron gun has heater, cathode, G1, G2, G3, G4, and shield cup electrodes. In this BPF type electron gun, an electron lens is constituted by the G3 electrode and the G4 electrode which are arranged to face each other with a gap therebetween. The cathode and the G1 to G4 electrodes are fixed to a pair of bead glasses with a bead support (not shown). Each cylindrical electrode has a flat shape in which the diameter in the horizontal direction is longer than the diameter in the vertical direction, and has three openings formed on the opposing surface for individually passing three electron beams (for example, Japanese Patent Application Laid-Open No. 57-143250). And Japanese Patent Publication No. Sho 59-11176) and one in which one elliptical hole common to three electron beams is formed.

On the other hand, in order to improve the focusing characteristics of the electron lens, it is conceivable to increase the aperture of the aperture formed in the above electrode to increase the lens aperture. As a method of enlarging the effective aperture, there is known a method in which an electrode plate (plate-like electrode) forming an opposing surface of a cylindrical electrode and having an opening is retreated so as to be away from the opposing position. In this case, since the horizontal cross section of the outer peripheral section of the cylindrical electrode is longer than the vertical direction, the lens focusing power differs between horizontal and vertical, and astigmatism occurs. In order to correct this aberration, the opening formed in the electrode plate (plate-like electrode) has an elliptical shape whose rectangular shape is horizontal and whose major axis is vertical. This is called the "EA type (Elliptical Aperture) large-diameter electron gun." This electron gun is described in JP-A-59215640 as an example.

By the way, the applicant of the present application has previously described a plate-shaped electrode (also referred to as a correction electrode) in this type of EA type electron gun, as described above.
The main lens diameter is enlarged by disposing the main lens electrode by retreating it from the opposing position of the cylindrical electrode, and furthermore, an elliptical peripheral rim (guide portion) is formed at the opposing position to constitute the main lens electrode. did. This proposal will be described with reference to FIG.

FIG. 2 (a) is a horizontal sectional view of the main electron lens portion of the proposed electron gun (for example, an EA-BPF type is shown),
FIG. 2 (b) is a vertical sectional view of the same. FIG. 2 (a),
In (b), 111 is a G3 electrode, 131 is a G4 electrode, and the gap g
The G3 electrode 111 comprises a welded assembly of a cylindrical electrode (hereinafter referred to as “cup electrode”) 101 and a lower electrode 102, and the G4 electrode 131 has a shield cap 122 above the cup electrode 121. Has a welded structure.

On the opposing surface side of the G3 and G4 electrodes 111 and 131, the peripheral edge is bent inward at a bending height h, respectively,
Oval holes 101a and 121a having peripheral burring (cut and raised) of this height h are formed. This oval hole 101a
121a has the same dimensions as the G3 and G4 electrodes 111 and 131, and has a flattened shape in which the horizontal aperture is longer than the vertical aperture, forming a common aperture for the three electron beams. I have. From each opposing surface of the G3 and G4 electrodes in a retracted position away from each other by a predetermined distance d ₁ and d _2, the correction electrode plates having the shape shown in FIG. 2 (c) perpendicular to the tube axis direction 103 and 123 are provided by welding assembly. This correction electrode has a central elliptical opening 103b and semicircular portions 103a, 103 on both sides.
c (substantially elliptical apertures when attached to the cup-shaped electrodes 101, 121), each aperture allowing the passage of three electron beams.

When assembling the electron gun, first, the G3 electrode 111 and the G4 electrode are individually formed, and then these electrodes are integrally formed with a gap g therebetween. For example, when welding the correction electrode plate 103 to the G3 electrode 111, a jig as shown in FIG.
The edge of one oval opening 101a is cut and raised, that is, the rim (height h) is fitted as a guide into the base 201d of the jig 201,
Further, a hole or semicircular portion 103a, 103b, 103 of the correction electrode plate 103
c to the jig projections 201a, 201b, 201c
Weld at a position retracted by _one . Generally, the electrode assembly accuracy of an electron gun for a color picture tube greatly affects the performance of the electron gun. In particular, since the main lens electrode is formed by assembling a plurality of electrode parts as described above, the assembling accuracy affects the characteristics of the electronic lens.

[Problems to be Solved by the Invention] In the above-mentioned proposed technology, a plate-shaped correction electrode is built in a cylindrical electrode as a main electron lens portion of an electron gun. A rim portion (cut-and-raised portion, burring, guide) is provided on the periphery of the oval opening facing the cylindrical electrode. When the height h of the rim portion is low, the guide function cannot be sufficiently performed at the time of assembling, and the cylindrical electrode is easily inclined. Therefore, there is a problem that the accuracy when the correction electrode plate is arranged in the cylindrical electrode is reduced. is there. In order to enhance the guide function, it is better to increase the height h of the rim portion of the cylindrical electrode.

However, it has been found that when the height of the rim portion of the cylindrical electrode is increased, the astigmatism of the large-diameter electron lens increases, and it becomes difficult to correct the astigmatism. In particular, as the influence of the rim, the central portion (linear portion) of the rim in the horizontal direction gives relatively large astigmatism to the central electron beam.

Accordingly, it is an object of the present invention to overcome the above-mentioned problems of the prior art, to obtain a highly accurate electrode structure by a sufficient guiding function of the rim portion, and to influence the rim portion on the electron beam. An object of the present invention is to provide a color picture tube electron gun having a main electron lens free of astigmatism by minimizing the above.

[Means for Solving the Problems] In order to achieve the above object, the in-line type color picture tube electron gun of the present invention has a main lens portion in which cylindrical electrodes are arranged to face each other with a gap in the tube axis direction. And having a horizontally elongated elongated oval opening on the opposing surface of the cylindrical electrode, and a rim protruding inward from the opposing surface at the periphery of the oval opening, from the opposing surface. The correction electrode is provided at a position inside a predetermined dimension, and the height of the rim portion from the opposing surface is higher at the arcuate portions on both sides than at the center in the horizontal direction of the oblong hole.

[Operation] An operation based on the above configuration will be described.

According to the present invention, in a pair of cylindrical electrode portions constituting a main electron lens of an in-line type color picture tube electron gun,
Since the height of the peripheral rim portion of the oval opening that functions as a guide member at the time of assembly can be made sufficiently high at the semicircular portions on both sides in the horizontal direction, the cylindrical electrode does not tilt with respect to the jig. In addition, the correction electrode plate can be attached to the cylindrical electrode with high accuracy. In particular, the function of the guide depends more on the semicircular part on both sides than on the linear part at the center in the horizontal direction, so even if the height of the rim at this central linear part is low, the guide function is affected. I will not do it.

On the other hand, the astigmatism of the electron beam, particularly the height of the rim at the central linear portion which causes astigmatism in the central electron beam, can be sufficiently reduced by the present invention, so that the astigmatism is reduced. And a good focus characteristic can be obtained. Since the influence of the rim portion on the potential beams on both sides is originally small, there is no problem even if the height on both sides of the rim portion is high.

Thus, according to the present invention, the guide function at the time of welding and assembling the correction electrode is improved, and a main electron lens with a reduced spherical aberration and an enlarged main lens diameter can be obtained.
The influence of astigmatism on the electron beam of the guide member (rim member) can be reduced, and the focus characteristic can be further improved.

[Embodiment] An embodiment in which the present invention is applied to an EA type bipotential focus (BPF) type electron gun for an in-line color picture tube will be described below with reference to the drawings.

FIG. 1 shows an electrode structure of a main electron lens portion constituting the electron gun, and other electrode portions are omitted for simplicity. FIG. 2A is a cross-sectional view taken along a plane including the tube axis direction and the arrangement direction (horizontal direction) of three RGB electron beams, and FIG. 2B is a direction perpendicular to the tube axis direction and the electron beam arrangement direction ( (C), a cross-sectional view taken along a plane including (vertical direction).
2 is a front view of the G3 electrode viewed from the G4 electrode side, and FIG. 2D is a partially broken perspective view of the G3 electrode.

This embodiment has the same structure as that described in FIG. 2 except for the structure of the rim portion (guide portion, burring provided on the periphery of the oval opening). That is, 11 is a G3 electrode, 31 is a G4 electrode,
The electrodes 11 and 31 are opposed to each other with a gap g, and the electrode 11 is composed of a welded assembly of a cylindrical electrode (cup electrode) 1 and a lower electrode 2. The electrode 31 is formed of a cylindrical electrode (cup electrode) 21 and a shield cup. Consists of 22. From the surface facing the G3 electrode 11 and the G4 electrode 31 only incoming ivy location distance d ₁ and d ₂ inwardly, a plate-like correction electrodes 3 and 23 respectively are welded. Correction electrode 3,23
Has a central elliptical opening 3b and arcuate parts on both sides,
When attached to the cylindrical electrodes 1, 21, individual passage holes 3a, 3b, 3c for three electron beams are formed. 1a and 21a are oblong holes formed in the opposing surfaces of the cylindrical electrodes 1 and 21, and as shown in FIG. 1 (c), have an elongated shape in the horizontal direction and a straight central portion in the horizontal direction. Both sides are arc-shaped. 1b, 21b
Is a rim (guide portion, burring portion, inward bent portion) formed to protrude inward (in a direction away from the opposing surface) at the periphery of the oblong holes 1a, 21a. is there.
The oval openings 1a and 2a have the same dimensions as each other in the G3 and G4 electrodes 11 and 31.

As a feature of this embodiment, as shown in FIG. 1 (a), the rim portions 1b and 21b are such that the height H2 at both sides in the horizontal direction is higher than the height H1 at the central portion. Thus, at the time of assembling the electrodes, the cylindrical electrodes 1, 21 are formed by the method shown in FIGS.
When welding the correction electrode plates 3 and 23 to the jig, the cylindrical electrodes 1 and 21 can be guided to the jig by the rims on both sides where the height H2 is sufficient, so that the cylindrical electrodes may be inclined. Therefore, the correction electrode plate can be attached with high accuracy. In addition, the main electron lens portion assembled in this manner has a sufficiently low height H1 at the central portion of the rim portions 1b and 21b, and thus has little effect on the electron beam, especially the central electron beam, and has no astigmatism. Beam can be obtained.

On the design side, the horizontal outer diameter W of the cylindrical electrodes 1 and 3 is 22 m
m, the gap length g is slightly more than 1 mm, and d ₁ and d ₂ are 3 to 4 mm,
The results were good when H2 was about 2 mm to 3 times (1 mm to 2 mm) of H1.

In the above embodiment, BPF has been described an electron gun having (Baipotenshiyaru type Fuokasu, Fuokasu a is 20% of the applied voltage E _b of electrodes G4 voltage E _f of the electrode G3) type electron lens, other those having an electron lens form, for example, Hi-Fo type that the voltage E _f of the electrode G3 and 28% of the voltage of the electrode G4 (Hythe Oka single voltage BP
F), Hi-UPF type that gives 38% of the voltage E _f of the applied voltage E _b of the G3 and G5 electrodes to the G4 electrode (Hythe Oka single-voltage uni potentiation dial Fuo Kas), the G3, G5 electrode, G4, G6 Voltage E _{f of} about 28 to 33% of the applied voltage E _b of the electrode
The give B-U type (Baipotenshiyaru-Yunipotenshiyaru), G3, G5-electrodes give 28-33% of the voltage E _f of the applied voltage E _b of the G6 electrode to the same potential to the G4 electrode and the G2 electrode U- The same can be applied to a B type (unipotential / bipotential) and the like.

Further, in the above embodiment, the inner diameter of the rim base portions 1c, 21c of the oblong holes 1a, 21a can be expanded by making the funnel taper.

[Effects of the Invention] As described in detail in the above embodiments, according to the present invention, in an in-line type color picture tube electron gun, a pair of cylindrical electrodes forming an electron lens portion are formed on opposing surfaces. The height of the rim around the periphery of the oval hole is reduced at the center and increased at both sides, so the guide function by the rim when welding and assembling the correction electrode is improved, and a high-precision electron lens electrode assembly is realized. In addition, the effect of the rim on the astigmatism of the electron beam can be reduced, and the focus characteristic can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an electrode structure of a main electron focus portion of an electron gun according to an embodiment of the present invention, FIG. 2 is a configuration diagram of an electrode structure of a main electron focus portion of a conventional electron gun, and FIG. FIG. 4 is an overall configuration diagram of a general BPF type electron gun which is an example of a picture tube electron gun to which the present invention is applied. 1,21 ... cylindrical electrode, 2 ... lower electrode, 3, 23 ... correction electrode, 11 ... G3 electrode, 22 ... shield cup, 31 ... G4 electrode, 1a, 21a ... oval opening , 1b, 21b ... rim part (elliptical hole bending part), H1, H2 ... rim part height.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Satoru Miyamoto 3300 Hayano Mobara-shi, Chiba Pref. Mochi Plant, Hitachi, Ltd. (56) References JP-A-61-27047 (JP, A) (58) Survey Field (Int.Cl. ⁶ , DB name) H01J 29/46-29/68

Claims (1)

(57) [Claims] 1. An in-line type color picture tube electron gun in which a cylindrical electrode is opposed to a tube axis direction with a gap interposed therebetween to form a main lens portion. A rim portion protruding inward from an opposing surface at a peripheral portion of the oval opening, and a correction electrode provided at a position inside a predetermined dimension from the opposing surface; Wherein the height from the opposing surface is higher at the arcuate portions on both sides than at the center in the horizontal direction of the oblong hole.