US2897389A - Bulb and bulb spacer for camera tube - Google Patents

Description

July 28, 1959 F. J. sALGo '2,897,389

BULB AND BULBSPACBB B0B CAMERA TUBE Filed Aug. 24, 1956 United States Patent BULB AND BULB SPACER FR CAMERA TUBE Francis J. Salgo, Bellas, Tex., assgnor to General Electrodynamics Corporation, Garland, Tex., a `corporation of Texas Application August 24, 1956, Serial No. 606,094

I1 Claim. (Cl. 313-65) This invention pertains to a television camera tube and more particularly to a bulb and bulb spacer for such a tube.

A principal object of the invention is to provide such a tube which can `be operated in any position relative to the earths gravitational eld, i.e. base down, base up, or at any angle therebetween including horizontal.

A further object of the invention is to provide such a tube which will be able to withstand large and repeated and alternating accelerations, i.e. will be shock and vibration resistant.

Other objects and advantages of the invention will appear from the following description of a preferred embodiment thereof, reference being made to the accompanying drawings in which:

Figure 1 is an axial section through a camera tube embodying the subject invention;

Figure 2 is a section taken on line 2-2 of Figure 1; and

Figure 3 is a section taken on line 3 3 of Figure 1.

Referring now to Figure 1, there is shown a camera tube having an envelope comprising a glass bulb formed from cylindrical precision tubing. Precision tubing has an inner diameter that is held to a tolerance of no more than 0.001 inch. The tube envelope further comprises an end piece, or stem 11 closing one end of the bulb and through which (see also Figure 3) extend wires 12-18 sealed thereto and providing electrical connections to and mechanical support for the electron beam forming means inside the tube envelope. The tube envelope further comprises a flat glass face plate 23 at the other end of the bulb 10 with contact ring 24 disposed therebetween and sealed thereto.

'Ihe inner surface of face plate 23 is provided with a light distribution responsive means comprising a thin transparent electrically conductive coating 26 next to the face plate and connected to ring 24 at its outer periphery, plus a layer of photo conductive material 27 over the coating 26. The transparent conductive coating 26 is preferably a thin chloride derivative while the photoconductive layer 27 may be made of antimony trisulde.

The electron beam forming means comprises a heater coil 29 connected to wires 13 and 15. Coil 29 is disposed inside a negative electrode or cathode 30 connected to wire 14. Heat resistant insulation 31 such as aluminum oxide, separates coil 29 from cathode 30. The end 32 of the cathode is provided with material that emits electrons when heated. The cathode is further supported in a heat resisting and insulating ceramic disc 33. Disc 33 is supported between flanged metal discs 34, 34a welded inside cup shaped rst grid or electrode 35 having an opening 36 adjacent the end 32 of the cathode. Grid 35 carries three insulating support rods 37a, b, c, uniformly azimuthally spaced around the grid, the rods being secured to the grid by metal bands 38a, b, c. Band 38C is electrically and mechanically connected to wire 17 by wire 17a, while band 38a is connected (for mechanical purposes) by strips 39a, b to wires 12 and 19.

A second cup shaped grid or electrode 40 is similarly Patented July 28, 1959 Jice rods 37 by means of sleeves such as 46, 47 and is elecn trically connected to wire 18 by wire 18a.

Beyond the ends of the rods the third grid ares at 48 to a larger diameter cylindrical portion 49, the grid 45 being formed by welding smaller and larger diameter cylindrical portions to the ends of a flaring portion as shown. The end of grid 45 farthest from the base 11 is welded to a ring 49a having an outwardly extending ange 50 to which is fastened the outer periphery of a forarninous disc 51 having a mesh of 500 wires per inch, the maximum diameter of the wire being 0.0002 inch.

The enlarged end 49 of grid 45 is supported by a funnel shaped resilient metal spacer 55 having a cylindrical portion 56 fitting snugly on and welded to the grid and a stepped conical portion 57. The maximum cone diameter is .001 inch larger than the maximum inner diameter of the bulb 10 so as to insure a slight deilection of the conical part of the spacer when it is slid into the bulb. Additional spacers may be provided between the bulb 10 and grid 45 if desired. Additional spacers having holes to accommodate the rods 37 may be provided adjacent the small part of grid 45 and the grids 40 and 3S if desired.

It will be :apparent that the foraminous disc or screen 51 closes o the end of grid portion 49 and that spacer 55 closes olf the annulus between portion 49 and the bulb. The term closes olf is used in the sense that both screen 51 and spacer 55 are impervious to the passage of any particles of maximum dimension over about 0.001 inch so that photo conductive layer 27 of the light distribution responsive means is separated from the rest of the tube. Therefore any debris in the rest of the tube such as powder from ceramic disc 33 or flakes from the electron emitting material 32 on the end of the cathode, or fragments of the aluminum oxide insulation 31, or bits of weld spatter at the various electrode seams and junctures, all of which form and `are freed as the tube is repeatedly heated up and cooled, are kept from falling onto photo conductive layer 27 regardless of the inclination and direction of the tube axis. This is very important, for when the electron beam, produced by the electron beam forming means hereinbefore described, is caused to scan the light distribution responsive means, any debris on the latter will render inoperative the portion covered by such debris with the result that black or white spots will be formed in any picture reproduced from the output of the camera tube.

It is the use of precision tubing for the bulb which makes possible the use of the spacers herein described. rThe electrodes on which the spacers are mounted are of very thin gauge, eg. 0.003 inch thick, so that they cannot withstand jamming any coarse force fit spacers into place. The spacers are of similar thin gauge, c g. 0.003 inch thick. Without a close t the grid will not only not be sealed off on the outside but will be loose in the bulb. The spacer herein described securely holds the electron beam forming means in position in the bulb so that there is no relative motion between the electron beam forming means and the light distribution responsive means. The spacer construction allows the tube to withstand shocks and at the same time is not resonantly responsive to vibrations as are the usual spring type mountings used with ybulbs made of non-precision tubing.

While a preferred embodiment of the invention has been shown and described, many modifications thereof can be rnade by one skilled in the art without departing from the spirit of the invention and it is desired to protect by Letters Patent all fonns of the invention falling within the sCOpeOfthe followingclaim; v

A. television camera tube comprising a. cylindricaL 5 bu1b made ofprecision tubing having an internal diam-` etentolerance lof the orderof plus `or` minus a thousandth of an inch, an end piece closing oneendofsaid bulb,` al light distribution responsive means closing the-other endV of said bulb, an electron beam formingmeans dis-V posed inside saidrbulb andincluding at one end thereof a' cylindrical electrode portion, said ,portionrbeing spaced, Aradially inward and separated fromisaid glass bulb, said electrode portionbeing madeof thin gauge sheet metal, ofthe order of magnitude of a few thousandthsof 311,; inch thick, foraminous means extendingtransversely oiv the O saidcylindrical,electrodeportion closing olfV the space inside `said portion against passage therethrough 5 of any particles ,of a size ofthe `order of a thousandthf of an inch in maximum dimension or larger, means supporting said beam forming means atthe other` end.` thereofffrom saidend piece, andmeans supportingzsaid bearnvforming means near the first said end thereofrand. blocking off the annulus between said cylindrical portion and the inside ofsaid vbulb to prevent passage therethrough of particles of the aforesaidsize, the last,

said means comprising a `ring of resilient sheet metal of a thin gauge of the order of magnitude of a few thousandths of an inch thick, said ring having a sleeve portion tted snugly around said cylindrical electrode portion and secured thereto and a barrier portion flaring from said sleeve portion into engagement with the inside of said bulb, the maximumldiamheter of said flaring por- ,4 tionA when' unstressed'- exceeding the internal diameter of said bulb providing a light force tit therebetween.-

References Cited in the le of this patent UNITED STATES 'PATENTS 1,972,611 Warren Sept. 4, 1934 2,062,663 Kautter et al. Dec. 1, 1936 2,245,998 Pietsch June 17, 1941 2,452,620- Weimer ..k Nov. 2, ,1,948 2,506,018-, Fiery, et al; May 2, 19,5107 2,580,250 Smith Dec. 25,195.1, 2,640,162-V Espenschield vet-al. May 2,6,\ 19,53 2,644,9M` Bondley, July, 1, k195sY 2,654,352y Y CCL. 6, 1.953 2,710,7813v-, Forgue 7 r l June 14, 1955. 2;,-f '47,1 f3yi Weimers MayV 2,2, l 1956 218,023 15,; 195:7 f

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