Improvements relating to photo-conductive targets and especially television pick-up tubes and analogous image pick-up devices

摘要

794,332. Photo-electric devices. ELECTRIC & MUSICAL INDUSTRIES, Ltd. Aug. 11, 1954, No. 29574/57. Divided out of 794,331. Class 37. [Also in Group XL (a)] A photo-conductive target comprises a transparent conductive film 4, a deposit 5 of N-type photo-conductive or semi-conductive material in contact with one surface of the film, the deposit being at least partially transparent to light, and another deposit 6 of N-type photoconductive material in contact with the first deposit. The deposit 5 preferably is of thickness large compared with the deposit 6 and has a long range for electrons compared with the material of deposit 6; this enables the capacity to be kept low without impeding the charging process, which is by conduction of electrons from the low-velocity scanned face of 6 to the signal plate 4. Deposit 5 may be Rochelle salt or an alkali halide, for example a single crystal. Deposit 6 may be photo-conductive antimony trisulphide. In a modification to improve the colour response deposit 5 may also be photo-conductive for example cadmium sulphide sensitve to blue light, which passes on the red light to the red-sensitive deposit 6. Reference has been directed by the Comptroller to Specification 705,533.