GB445372A - Cathode ray tubes for television apparatus - Google Patents

Abstract

445,372. Discharge apparatus. SHORNEY, A. B., Shebbear, Beaworthy, Devon. Nov. 30, 1934, No. 34410. [Class 39 (i)] A cathode-ray tube for television transmitting apparatus has a photo-electric screen consisting of a cellular anode 8, Fig. 1, and a cellular photo-electric cathode member 7, an insulated conductor 12 extending into each pair of cells 9, 14, the anode cells 14 being closed by a plate 15 which is impervious to actinic rays and is provided with apertures closed by material 16 pervious to X-rays but not to cathode rays, the arrangement being such that when the screen is scanned by cathode rays, X-rays are produced in the anode cells and discharge the energy stored in those cells. The cathode member 7 may be of glass with conical or pyramidal cells, the lower ends of which are each formed with an aperture. The walls of each cell 9 are silvered and coated with sodium, the part near the aperture being left free of coating. In a modification, the deposits are formed only on the inner surface of the cover plate 13 and in the upper ends of the walls, connection between the cells and a terminal being obtained by metal strips 17, Fig. 3. The conductors 12 are of wire coated with lead glass, and are secured in the apertures by enamel, a part of the glass coating being removed by chemical action. The anode 8 consists of a sheet of lead or lead alloy with rectangular cells, and is closed by a metal plate. The apertures containing material 16 pervious to X-rays are in line with the conductors 12. The anode cells may contain gas or a metallic oxide which becomes conductive on exposure to X-rays. A thin film of metal may be deposited on the outer surface of the plate and of the material 16. The parts of the conductors inside the cathode cell acquire a positive charge as the other ends are negatively charged by induction from the anode. A picture focused on the cathode produces electrons which pass to the conductors, and the charge on the conductors is caused to leak through the gas &c. filling by X-rays produced in the anode cells by the scanning cathode rays. In another arrangement, the cathode member 7 is of metal and is insulated from the anode.