US2627585A - Electron gun for cathode-ray tubes - Google Patents

Description

Feb. 3, 1953 w, VAN ORNUM 2,627,585

ELECTRON GUN FOR CATHODE-RAY TUBES Filed Sept. 1, 1950 F/gi WESLEY H. VAN ORNUM INVENTOR.

/-//s ATTORNEY Patented Feb. 3, 1953 UNITED STATES PATENT O FF I CE W s e en O e q a a o liarlaeeqcmraiina wreeiaiicec Application eptember 1, 1950, Serial No. 182,774 .3 cla ms} (01. ,3::

This invention relates a to electron guns for cathode-ray tubes or the like, and morepart-icularly to a novel supporting arrangement for the electrodes constituting an electron gun.

A conventional cathode-ray tube electron gun comprises a plurality of tubular electrodes, including first and second grids and an anode, arranged in predetermined mutually spaced relation to direct and control an electron beamorigihating at an indirectly heated cathode. It is customary practice to provide studs extending outwardly from each of the tubular electrodes at correspondingly spaced peripheral intervals and to affix rigid insulating spacer-support members to longitudinally aligned studs in order to support the second grid and the anode from the first grid. To this end, the outwardly-extending studs are individually welded to the respective tubular electrodes; this welding operation is both timeconsuming and costly.

It is theobi f e resentinv n t Pr vide a new and improved electron gun, for a cathode-ray tube or the like, in which, th several electrodes are supported in a desired predetermined mutually-spaced relation in a simple and economical manner.

In accordance with the invention, an electron gun for a cathode-ray tube comprises first and second tubular electrodes. outwardly-extending studs are supported by the respective first and second electrodes, at least one of the studs being in the form of an integral projection struck from one of the electrodes. A rigid insulating spacersupport member is affixed to the studs to support the two electrodes in predetermined longitudinally spaced relation with respect to each other.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claims. The invention, together with further objects and advantages thereof, may best be understood, however, by reference to the following description taken in connection with the accompanying drawing, in the several figures of which like reference numerals indicate like elements, and in which:

Figure 1 is a fragmentary view, partly in section, of a cathode-ray tube comprising an electron gun constructed in accordance with the present invention;

Figure 2 is an elevational View, partly in section and taken in a direction at right angles to the showing of Figure 1, of the electron gun structure; and

Figure 3 is a plan view of one of the electrodes.

As shown in Figure 1, a cathode-ray tube may 2 comprise an evacuated envelope l0 having an electron gun-for directing a focussed electron beam to a fluorescent screen (not shown) provided at one end I. I of the envelope. The electron gun comprises three tubular electrodes [2, l3 and It, conventionally designated the first grid, the second grid, and the anode respectively. A conductive coating iii is applied to the inner wall of the envelope Ii! toprovide a field-free path for the electron beam in its progress from the electron gun to the fluorescent screen, and conductive coating I 5 is maintained ata common potential with anode M, by

-means of-a plurality of resilient metal contacts 136. As best shown in Figure 2, a thermionic cathode I 1, preferably of the indirectly-heated type, is supported within the first grid [2 by means of an insulating spacer [8.

Each of the electrodes l2, l3 and I4 is provided with a plurality-of outwardly-extending studs [9, 2t, and 2! respectively, and a pair of rigid insulating spacer- support members 22 and 23 are affixed to longitudinally aligned studs i9, 29 and 2| supported by the several electrodes. In this manner, the electrodes are maintained in a desired predetermined mutually-spaced relation, the second grid I3 and the anode It being supported by the first grid l2 which in turn may be held firmly within the evacuated envelope Ill by means of support members 24 (Figure 1) extending inwardly from the base of the tube.

In accordance with the invention, some or all of the studs I9, 25], and 2| are constructed as integral projections struck from the respective electrodes [2, I3. and It. In order to obtain increased rigidity, it is preferred that the projections be folded or channeled as indicated in Figure 3. In this manner, the necessity of welding separate stud members to the electrodes is obviated.

The striking and channeling operations may readily be performed by automatic equipment by the use of properly cut dies, in order to render the fabrication of the electrodes feasible for large scale production. As indicated in Figure 3, a generally rectangular aperture 25 may be cut in the electrode cylinder, 1eaving the material intact at each end of the aperture. A cross-cut may be made at an intermediate position indicated by the dotted line 26, and the two cars thus formed may readily be bent up and channeled to form the finished studs 2 I It has been found that the provision of one or more apertures 25 in the tubular electrodes permits the formation of the desired stud configuration without detrimentally afiecting the formation or focussing of the electron beam. Unclesirable discontinuities in the electrostatic fields existing within the respective electrodes are substantially avoided so long as the total area of the removed material is small relative to the total circumferential area of the electrode.

While the illustrated embodiment employs a pair of oppositely disposed rigid insulating spacersupport members 22 and 23, it is, of course, possible and within the scope of the invention to provide three or more of such spacer-support members; in any event, it is preferred that the studs extending outwardly from the several electrodes be spaced at substantially equal peripheral intervals. In this manner, the rigidity of the composite structure against subsequent deformation in any direction is optimized,

The particular electron gun structure illustrated in Figures 1 and 2 is of the type in which 'the anode is laterally offset from the first and trodes are maintained in accurate coaxial alignment.

While a particular embodiment of the present invention has been shown and described, it is apparent that various changes and modifications may be made, and it is therefore contemplated in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

I claim:

1. In an electron gun for a cathode-ray tube: first and second tubular electrodes; a stud supported by said first electrode and extending outwardly therefrom; at least one stud in the form of an integral projection struck from said second electrode and extending outwardly therefrom; and a rigid insulating spacer-support member afiixed to said studs to support said second electrode in predetermined longitudinally spaced relation with said first electrode.

2. In an electron gun for a cathode-ray tube: first and second tubular electrodes; a stud supported by said first electrode and extending outwardly therefrom; at least one stud in the form of a channeled integral projection struck from said second electrode and extending outwardly therefrom; and a rigid insulating spacer-support member affixed to said studs to support said second electrode in predetermined longitudinally spaced relation with said first electrode.

3. In an electron gun for a cathode-ray tube:

" a plurality of tubular electrodes including a first grid, a second grid, and an anode; a plurality of studs supported by said first grid and extending outwardly therefrom at substantially equal peripheral intervals a plurality of studs supported by said second grid and extending outwardly therefrom at peripheral intervals correspending to those of said first-mentioned studs; a plurality of studs in the form of integral projections struck from said anode and individually extending outwardly therefrom in substantial longitudinal alignment with corresponding studs supported by said first and second grids; and a plurality of rigid insulating spacer-support members individually aflixed to longitudinally aligned studs supported by said first and second grids and by said anode.

WESLEY H. VAN ORNUM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date Re. 22,378 Bowie Sept. 21, 1943 1,550,768 Weinhart Aug. 25, 1925 2,096,415 Weinhart Oct. 19, 1937 2,096,466 Painter Oct. 19, 1937 2,129,005 Hudec Sept. 6, 1938 2,163,233 Brown June 20, 1939 2,436,264 OLarte et a1 Feb. 17, 1948 2,441,315 Forgue May 11, 1948 2,451,323 Foulker Oct. 12, 1948 2,487,592 Rishell Nov. 8, 1949

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