JPH0481296B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mesh electrode support structure for an image pickup tube, in which a mesh electrode is insulated and supported on the opening edge of a focusing electrode using a ceramic ring as an insulating support means.

Conventional configurations and their problems In electrostatic focusing type or electromagnetic focusing type image pickup tubes, a mesh electrode is insulated and supported on the opening edge of the focusing electrode, and a potential difference is applied between the two electrodes to generate a lens electric field. It is. In this case, the lens electric field allows the electron beam to be incident on the photoconductive film substantially perpendicularly, and not only can good photoelectric conversion characteristics be obtained, but also deflection distortion can be reduced.

Incidentally, a ceramic ring is generally used as an insulating support means for the focusing electrode of the mesh electrode. To explain this with reference to Fig. 1, a cylindrical focusing electrode 1 made of a stainless steel plate, a nickel-chromium alloy plate, a nickel-copper alloy plate, etc. with a thickness of 0.125 mm to 0.2 mm is placed on the outer circumferential surface of its opening edge. Insert ceramic ring 2 into the
The ceramic ring 2 is immovably supported by first and second band-shaped metal rings 3 and 4 that are wound around or fitted into the focusing electrode 1 and welded so as to come into contact with both end faces of the ceramic ring 2. ing. Then, a metal cylinder 6 that welds and fixes the mesh electrode 5 at its peripheral edge is fitted onto the outer peripheral surface of the ceramic ring 2, and the claws 6a and 6b of the metal cylinder 6 engage with both end surfaces of the ceramic ring 2. As a result, the mesh electrode 5 is insulated and supported on the opening edge of the focusing electrode 1.

In the conventional mesh electrode support structure constructed in this manner, unless thick plates are used for the first and second band-shaped metal rings 3 and 4, the stopping action against the ceramic ring 2 is insufficient. However, while pressing a metal ring with a thickness of about 0.18 mm to 0.25 mm onto the outer peripheral surface of the focusing electrode 1,
It is not easy to perform spot welding at 15 to 15 locations, and there is a risk that the metal rings 3, 4 and the focusing electrode 1 will be deformed due to the high temperatures during welding. In particular, if a portion of the metal ring lifts off the outer circumferential surface of the focusing electrode 1, it may come close to or come into contact with the metal cylinder 6, threatening electrical insulation with the mesh electrode 5, so the number of welding points should be reduced. I can't even do that.

OBJECTS OF THE INVENTION Therefore, an object of the present invention is to be able to provide a sufficient stopping action to a ceramic ring while using a metal ring with a relatively small plate thickness, and to provide a welding point for attaching the metal ring. An object of the present invention is to provide a mesh electrode support structure capable of reducing the number of points to four points.

Structure of the Invention According to the present invention, a ceramic ring is fitted onto the outer peripheral surface of the opening edge of a cylindrical focusing electrode, and a ceramic ring is provided on the outer peripheral surface of the focusing electrode so as to be in contact with both end surfaces of the ceramic ring. and a mesh electrode fixing metal cylinder fitted onto the outer peripheral surface of the ceramic ring, at least one of the first and second metal rings. a cylindrical part that is spot-welded in contact with the focusing electrode; and a plurality of protrusions that are bent from a portion of the cylindrical part that avoids the vicinity of the spot-welded area and abut on one end surface of the ceramic ring. This will be explained in detail below together with the embodiments shown in the drawings.

DESCRIPTION OF THE EMBODIMENTS As shown in FIGS. 2 and 3, a cylindrical focusing electrode 1 has a ceramic ring 2 fitted onto the outer peripheral surface of its opening edge. The metal cylinder for fixing the mesh electrode is fitted and fixed onto the outer peripheral surface of the ceramic ring 2, as in the conventional case. However, the first electrode is provided on the outer peripheral surface of the focusing electrode 1 so as to come into contact with both end surfaces of the ceramic ring 2.
and the second metal rings 7 and 8 have a thickness of 0.06 mm to 0.06 mm, which is smaller than the plate thickness of the focusing electrode 1 (0.125 mm to 0.2 mm).
The cylindrical part 7 has a plate thickness of about 0.15 mm and is spot-welded in contact with the focusing electrode 1, as shown in FIG.
a, 8a, and a plurality of protruding portions 7b, 8b which are bent from portions of the cylindrical portions 7a, 8a, avoiding the vicinity of spot welding areas, and abut against one end surface of the ceramic ring 2. However, the spot welding areas refer to the four areas marked with an x in FIG. 4.

In the embodiment shown in FIG. 5, the plurality of protrusions 7b are formed into a substantially L-shaped cross section by extrusion shaping. Further, in the embodiment shown in FIG. 6, the plurality of protrusions 7b are obtained by folding back approximately 180 degrees.
In each of the embodiments, there are four protrusions 7b, 8b and four spot welding areas, but the number may be three.

In this way, the first and second metal rings 7,
8 has completely annular cylindrical portions 7a, 8a, and the portions between three or four protruding portions 7b, 8b are cut out, so that it fits well on the outer circumferential surface of the focusing electrode 1. Although the plate has a relatively small thickness, it provides a sufficient stopping action to the ceramic ring 2. Furthermore, since the heat capacity of the spot welding area is small, spot welding at three or four locations using a small current is sufficient, and the metal ring and focusing electrode will not be deformed due to high temperatures during welding. In addition,
A conventional structure may be applied to either the first or second metal ring.

Effects of the Invention Since the present invention is constructed as described above, it is possible to provide a sufficient stopping action to the ceramic ring while using a metal ring with a relatively small plate thickness, and moreover, a small current of about 3 or 4 points can be applied. By spot welding, the metal ring can be reliably and stably attached to the focusing electrode, and there is no risk of deformation of the metal ring or the focusing electrode due to the high temperatures during welding, which is an excellent practical effect.

[Brief explanation of the drawing]

FIG. 1 is a side sectional view of the electron gun head of a conventional image pickup tube, FIG. 2 is a partially cutaway side view of the main part of the image pickup tube in which the present invention is implemented, and FIG. 3 is a front view of the main part. FIG. 4 is a perspective view of a metal ring of the same essential part, FIG. 5 is a perspective view of a metal ring according to another embodiment of the present invention, and FIG. 6 is a part of a metal ring according to another embodiment of the present invention. FIG. 1... Focusing electrode, 2... Ceramic ring, 5
...Mesh electrode, 6...Metal cylinder, 7,8...
Metal ring, 7a, 8a...cylindrical part of metal ring, 7b, 8b... protruding part of metal ring.

Claims (1)

[Claims] 1. A ceramic ring fitted onto the outer peripheral surface of the opening edge of the cylindrical focusing electrode, and first and second ceramic rings provided on the outer peripheral surface of the focusing electrode so as to come into contact with both end surfaces of the ceramic ring. A metal ring and a mesh electrode fixing metal cylinder fitted onto the outer circumferential surface of the ceramic ring, the mesh electrode being spot-welded to at least one of the first and second metal rings in contact with the focusing electrode. and a plurality of protrusions that are bent from a portion of the cylindrical portion that avoids the vicinity of the spot welding area and abut on one end surface of the ceramic ring. mesh electrode support structure;