GB920410A - Arrangement for scanning radiation-sensitive or radiation-emissive surfaces - Google Patents

Abstract

920,410. Electroluminescence. STANDARD TELEPHONES & CABLES Ltd. June 5, 1959 [June 6, 1958], No. 19314/59. Class 39 (1). [Also in Groups XXXVI, XL (b) and XL (c)] A radiation image pick-up or reproducing device has in series with each picture element of the radiation sensitive or radiation emissive surface a corresponding photo-conductive element which is optically shielded from the radiation at the surface and which when unilluminated effectively blocks an electric current to the picture element; to provide a scanning sequence each photo-conductive element is illuminated in turn by sequential excitation of an array of electroluminescent cells each including a photoconductive element as a component part. The Figure shows a panel in which the radiation sensitive or radiation emitting surface 1 (4) for an image converter or television system is backed by an array of electroluminescent cells. Each cell is composed of a pair of opposed transparent insulating blocks 55, 56, adjacent faces being coated with transparent conductive layers 32, 57 and sandwiching between them a strip 54 of electroluminescent material. The blocks 55, 56 support photo-conductive layers 15, 17 and are surrounded by light-shielding material 63. Photo-conductive layer 15 is connected at one edge to lead 49 of an electroluminescence excitation voltage supply and at the other edge to lead 61 which extends to an individual picture element area of layer 1 (4). Photo-conductive layer 17 is in contact at one edge via an opaque conductive layer between adjacent blocks 56 with the conductive layer 57 of the next cell in a row and at the opposite edge with either lead 27 or 28 (adjacent cells being connected alternately to these leads), leads 27, 28 being connected to pulse generators. These pulse generators operate alternately so that two cells virtually cannot be switched on at the same time. Alternatively, each electroluminescent element may be shunted by a further photo-conductive layer which is optically coupled to it in the same cell; after illumination due to a supply pulse the resistance of this photo-conductive layer remains low, thereby preventing re-excitation of the electroluminescent layer. Successive cells are switched on one at a time in sequence along the array of cells, a separate pulse being provided for switching on the first cell of the array. In a radar display system a row of switching electroluminescent cells mounted as a rotating arm moves over a viewing panel comprising photo-conductive and electroluminescent layers separated by an opaque conductive layer.