GB1481982A - Camera tubes - Google Patents

Abstract

1481982 Image pick-up tube PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd 24 Oct 1974 [27 Oct 1973] 46027/74 Heading H1D A camera tube target 9 scanned on one side by electron beam 20 and exposed on the other to a pattern of e.m. or corpuscular radiation 24 comprises a Si layer 21, preferably etched away in its central region, and with a preferably vapour deposited intrinsic vitreous layer 22, comprising at least one chalcogen (S, Se, Te) and at least one Group IVb element (Ge, Si, Sn), the atomic proportions of the Group IVb element to the chalcogen lying between 1 : 1 and 1 : 2. With the target a few volts positive relative to tube cathode, scanning charges layer 22 to cathode potential, the charge leaking subsequently in illuminated area through reverse-biased rectifying junction 23, to be replaced in the next scan. Charge leakage current provides signal p.d. across A-B. Preferred composition of layer 22 on low-ohmic N- type Si is GeS or an intermediate between GeSe and GeSe 2 ; a thin outer layer of GaSe on the GeS may be added. An outer layer of Sb 2 S 3 may b used to suppress secondary emmission. A thin SiO 2 layer may separate the Si layer 21 from layer 22. The formed target may be heat treated below 450‹ C.