GB363103A - Improvements in and relating to photo-electric apparatus - Google Patents

Abstract

363,103. Dis c h a r g e apparatus. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Hitchcock, W. J. ; 203, Alexander Avenue, Scotia, New York, U.S.A.) Nov. 25, 1930, No. 35477. Convention date, Nov. 26; 1929. [Class 39 (i).] A tube for use in the transmission of pictures has a cathode 11, Fig. 1, an anode 18, and a photoelectric element 17 scanned by a concentrated ray and interposed between the cathode and anode, the photo-electric element consisting of photoelectric material deposited on a number of small conducting sections mounted on vitreous supports or thin vitreous threads of such size and spacing as to have small capacity and high insulation. As shown in Fig. 2, the anode 18 consists of transverse wires, and the element 17 consists of caesium deposited on sections of silver, copper, or material known under the registered Trade Mark " Aquadag," mounted on mesh of vitreous material. A screen 21 and an accelerating anode 22 are mounted near the cathode 12, and the beam is deflected by electrodes 13, 14 so as to scan the element 17 on which a picture is projected through a lens 31. A gas is introduced so that the resulting positive ions concentrate the beam into a pencil of a diameter less than 1 mm. In order to prevent the discharge of the element 17 by the beam, an auxiliary cathode is provided and maintained at a lower potential than the cathode so as to produce a ray distributed over the element 17 and cause it to assume the potential of the auxiliary cathode. A control electrode 16 and a control electrode 15 at a lower potential than the electrode 16 are mounted near the element 17 so as to retard the rays from the cathode 12 and prevent the formation of positive ions near the photo-electric surface. The anode is connected through a resistance 26 and batteries 27, 25, 24 with the cathode, and through a condenser 29 with the input of a wireless transmitter 28.