US2146994A

US2146994A - Television screen

Info

Publication number: US2146994A
Application number: US119715A
Authority: US
Inventors: Schroter Fritz; Knoll Max; Bartels Bernhard
Original assignee: Telefunken AG
Current assignee: Telefunken AG
Priority date: 1935-12-23
Filing date: 1937-01-09
Publication date: 1939-02-14
Anticipated expiration: 1956-02-14

Description

Feb.n 14, 1939. A

Filed Jan. 9, 1937 fwwl/L/ ATTORNEY NNNNNN O R5 FRITZ SCHROTER MAX KNOLL BY7 @Q10 BARTELSl F. scHRTER ETAL 2,146,994

Patented Feb. 14, 1939 UNITED! STATES PLA-TENT" oFFl-e TELEVISION SCREEN Applicationl January 9, 1937; Serial# No. 119,715 InA Germany December 23, 1935 6 Claims.

This invention relates broadlyV toA television scanning apparatus, and more particularly to a grid screen of the type used in cathode rayvimage scannersy of the formA wherein the electronic charge imageis formedf on one side of the grid screen and the cathode" ray scanning device operates and impinges on the other side of the grid screen. Such screens have, in the prior art, been termed double side grid screens and broadly are Well known.

It has been usual in the prior art to form the screen of a metallic supporting structure which is multi-apertured, that is to say, is formed in a net or sieve-like form. Through each of the f apertures, a conducting element is passed, and on one extremity of the conducting element is deposited a photoelectric material, and the other extremity is subject to the electron bombardment from the cathode ray. It is, therefore, obvious that these conducting elements must be insulated both from each other and from the net or sievelike metallic body which acts as the supporting structure.

Heretofore it has been diicult in the manufacture of these screens to provide adequate insulating means between the conducting elements hereinbefore referred to, which carry a photoelectric deposit, in such a manner that the screens could be made practicable from a commercial standpoint.

It is, therefore, one of the objects of this invention to provide a grid screen of such a nature as to be comparatively easy to manufacture and a screen which will have adequate and desirable insulating means for electrically separating the conducting elements passing through the apertures therein.

Our invention will be best understood by reference to the figure which illustrates one embodiment.

Referring to the figure, the metallic supporting structure I0 may consist of a material Whose oxide is an electric insulator as, for instance, tungsten, molybdenum, aluminum or tantalum. The aluminum is especially desirable since its oxide has a high resistance not only to mechanical stresses which may take place when the conducting elements are inserted, but due to the fact that its oxide forms a very good insulator. For forming the oxide on aluminum, it is usually preferable to produce the insulating layer by means of electrolytic oxidation. Tantalum possesses the advantage that its oxide when formed in a layer or by oxidation,has a very high (Cl. Z-27.5)

ohmic resistance' and itsadhesion to the metal itself is very great.

Adhering to the` metallic support Ill isV a layer of the oxide of themetaliwhich is used, the said oxide being formed in Well known manners as, for instance, by. electrolytic oxidation or direct oxidation. The oxide layer II will then cover the outer surface of the metal I0 and will line the apertures I2 through which the conducting elements I3 pass. The conducting element I3 may in general be in the form of a pin, one of whose ends is formed of a frustro-conical section, and on the outer face of this section is deposited a layer of photoelectric material I4. 'Ihe pin then passes through the aperture and on its opposite side is subject to electronic bombardment on the surface I5.

For the purposes of clarity, there has been illustrated only one section of the screen greatly enlarged. It will be appreciated that these conducting pins are sufficiently great in number so that the outer surface of the frustro-conical section which holds the photoelectric material will be sufliciently close to that of the next pin so as to form a close fitting photoelectric mosaic.

It is possible also to provide the insulating surface on the sieve or net-shaped metal body by chemical or electrolytic methods using a metal other than the supporting sieve whose oxide is an insulator as, for instance, barium, caesium or magnesium. These substances may be evaporated in a vacuum and deposited on the metal netshaped support, and by subsequent oxidation, a successful and desirable insulating layer is formed.

What We claim is:

l. A cathode ray tube screen comprising a multi-apertured planar metallic supporting structure, a uniform layer of the oxide of said metal formed integral with said metallic support in the apertures therein, a plurality of conducting members each held in one of the apertures of the support structure, said members being of larger cross-sectional area at one end thereof than the other end thereof, and a deposit of photoelectric material on the enlarged areas of each of said members.

2. A cathode ray tube screen comprising a multi-apertured planar tungsten supporting structure, a uniform vlayer of tungsten oxide formed integral with said support, a plurality of conducting members each held in one of the apertures of said supporting structure, said members being of a pin formation and having one end thereof of greater cross-sectional area than the other end thereof, and a deposit of photoelectric material on the enlarged areas of each of said members.

3. A cathode ray tube screen comprising a multi-apertured aluminum supporting structure, a uniform layer o'f planar aluminum oxide formed integral with said support, a plurality of conducting members each held in one of the apertures of said supporting structure, said members being of a pin formation and having one end thereof of greater cross-sectional area than the other end thereof, and a deposit of photoelectric material on the enlarged areasl of each of said members.

4. A cathode ray tube screen comprising a multi-apertured molybdenum supporting structure, a layer of uniform planar molybdenum oxide formed integral with said support, a plurality of conducting members each held in one of the apertures of said supporting structure, said members being of a pin formation and having one end thereof of greater cross-sectional area than the other end thereof, and a deposit of photoelectric material on the enlarged areas of each of said members.

5. A cathode ray tube screen comprising a multi-apertured metallic supporting structure, a uniform layer of a planar metallic oxide formed integral With said metallic support and in the apertures therein, a plurality of conducting members each held in one of the apertures of the supporting structure, said members being of a pin formation and having one end thereof of greater cross-sectional area than the other end thereof, and a deposit of photoelectric material on the enlarged areas of each of said members.

6. The method of forming a double mosaic screen structure which comprises the steps of producing a planar metallic electrode, perforating said electrode with a plurality of minute apere tures therein according to a predetermined regular pattern, oxidizing the surface of the electrode includingthe apertured areas therein to provide