GB1459797A - Electronic storage tubes - Google Patents

Abstract

1459797 Cathode-ray storage tubes SONY CORP 7 Dec 1973 [8 Dec 1972] 56918/73 Heading H1D [Also in Division B6] A storage target for use in a tube having an electrical input and output, or in a camera tube, includes a conductive electrode 9 formed on a base 1a-e.g. the tube envelope-a storage material 10, and an electrode 12 in the form of spaced strips. For an electrical input tube, the layer 10 is of insulator, e.g. SiO or SiO 2 , formed as the oxidized surface of the chromium electrode 9, the electrode 11 being of aluminium. The tube includes a scanning electron gun and a beam landing adjusting grid (G 4 , Fig. 4, not shown). To erase the target and prepare it for uniting, the potential V T of electrode 9 is held at 200 volts and that of electrode 12, V P , at 180 volts, whereby scanning the target with the electron beam gives a secondary electron emission ratio greater than unity and raises the insulator surface potential, V S , to 180 volts. To unite upon the target, V P is raised to 220 volts, and the target scanned with the density modulated writing beam, to give V S equal to 180 volts still over the unwritten areas, but 220 volts over the written areas, whereby although V S varies over 40 volts, the potential difference across the insulator 10 does not exceed 20 volts. To read the target, V T is set at - 20 volts and V P at 10 volts, whereby the beam reaching the electrode 12 is modulated by the surface potential of the adjacent regions of insulator. In a modified target, Fig. 7, insulator 10 is of increased depth beneath the electrode 12, and a method of producing this structure by etching, without undue attack on the sidewalls of the depressions in the insulator, is disclosed (see Division B6), in which the insulator 10 is formed of three successive layers of MgF 2 or CaF 2 , of Al 2 O 3 , and of SiO 2 . Reference is also made to a target formed by applying electrodes to opposite surfaces of a thin glass plate. When employed as a camera tube, electrode 9 is transparent, and storage layer 10 is a photoconductor, the incidence of an optical image producing a corresponding pattern of potential V C at the opposite surface of the photoconductor, again to modulate the receipt of a writing beam by the electrode 12; since charging and discharging currents are not employed in the read-out process, the latter may be repeated without image exhaustion.