GB1270178A - Camera tube having a target formed by an array of phototransistors - Google Patents

Abstract

1,270,178. Image pick-up tubes; semiconductor targets. VARIAN ASSOCIATES. 23 Oct., 1969 [23 Oct., 1968], No. 52061/69. Headings H1D and H1K. The quantum efficiency of the target of a vidicon type tube comprising an array of transistors is improved by providing capacitance between the exposed terminals of the transistors and a fixed potential point. In one arrangement, Fig. 3 (not shown), the surface of the target facing the electron beam is coated with insulation such as silicon dioxide in which holes are etched to expose the transistor terminals; a metallic film, e.g. of gold, is deposited over the insulation and earthed to provide the required capacitance. In another arrangement, Fig. 4, each transistor terminal 16 is provided with an annular region 25 of opposite conductivity type which forms a junction capacitance which is connected to an earthed metallic film 28 separated by insulation 26 from the rest of the target body. The area 16 may be n-type and form the emitter of the transistor which includes a p-type base 17 and an n-type collector substrate (not shown) on a conductive coating attached to the inside of a glass face plate; alternatively the conductivity types may be reversed and the exposed electrode 16 is then the collector.