GB783812A - Improvements in or relating to solid-state image intensifiers - Google Patents

Abstract

783,812. Colour television. PHILIPS ELECTRICAL INDUSTRIES, Ltd. June 7, 1955 [June 10, 1954], No. 16343/55. Class 40 (3). [Also in Group XL (a)] The layer 7 (Fig. 1) between the photo-conductive layer 6 and the electroluminescent layer 8 of a solid plate image intensifier is of powdered magnesium oxide or titanium oxide. A glass support 11 is coated with a thin transparent electrode layer 2 of tin oxide having a thickened edge 3 to which a ter. minal wire is connected, followed by a further transparent conductive layer 5 and a photo-conductive layer 6, 100 microns thick, of selenium, germanium zinc sulphide lead sulphide, lead monoxide or lead selenide. On the other side of the intermediate layer 7 are the electroluminescent layer 8, a transparent electrode 9 with thickened terminal part 11 and a glass plate 10. The whole is housed in awooden frame 13and kept together by resilient rubber strip 14. An insulating transparent layer 100Á thick of mica glass, foam glass, melamine or nylon may be provided either between the photo-conductive layer 6 and its electrode or between the electroluminescent layer 8 and electrode layer 9. An alternating voltage is applied to the electrodes. Two screens may be used in cascade, the image being projected by lenses (Fig. 3, not shown); or three screens may be contiguously mounted with common electrode layers between them, one pole of the voltage source being connected to the first and third electrode and the other pole to the second and fourth electrodes (Fig. 4, not shown). The intensifier screen may also be mounted between the luminescent layer and the end wall of a cathode-ray tube or an electron microscope (Fig. 5, not shown). Colour images may be amplified by mounting identical multi-line colour filters 61, 62 adjacent the electrode layers of the photo-conductive and electroluminescent layers 66, 68 respectively, Fig. 6, or alternatively at a distance therefrom. The filters may have different colours for corresponding lines for colour correction or colour reversal purposes. Instead of using colour filters, the electroluminescent screen may be composed of lines or dots of different materials with red-green and blue responses. The materials are respectively copper-activated zinc selenide and two copper-activated zinc sulphides. The screen is scanned by a light spot from a C.R.T. which is colour modulated to the line pattern of electroluminescent layers (Fig. 7, not shown). Alternatively the photo-conductive layer may be of line or dot pattern of materials with different colour sensitivities, e.g. cadmium sulphide, zinc sulphide and a mixed crystal thereof. A colour picture is projected on to the photo-conductive layer and the resultant electroluminescent image modulated by the colour information is projected on to the photo-sensitive electrode of a television pick-up tube (Fig. 8, not shown). Three separate intensifier screens each with a different colour filter may be utilized and combined to give a colour picture.