GB783161A - Improvements in or relating to electron discharge devices - Google Patents

Abstract

783,161. Image dissector tubes. ELECTRIC & MUSICAL INDUSTRIES, Ltd. Jan. 25, 1954 [Jan. 24, 1953], No. 2109/53. Class 39(1). An image of a scene is projected on to photocathode 2 so as to release an electron image of the scene which is then scanned over a target electrode structure 4, the scanning motion and the construction of the target electrode structure (for example the provision of four spaced apertures 5) being such that the electron images is divided into separate juxtaposed areas which are simultaneously scanned, individual trains of electrical signals being derived which are representative of the separate areas. The time taken to scan the entire scene, which may be a target area, is thus reduced while the scanning speed is not increased and thus the signal/noise ratio is not reduced. As shown the target electrode 4 is backed by sets of multiplier electrodes 8 and screens 9 each set terminating in an output electrode 10 ; or the multiplier electrodes may be common to both streams so long as the streams are separate, and screens for this purpose may be provided. Another modification, Fig. 2 (not shown), uses a common output electrode and the signals from the various apertures are separated, in accordance with Specification 783,163, by modulating the stream leaving each aperture at a different high frequency by means of a grid; frequency discriminators in the ouput circuit will then separate the signals. In this form the first few multiplier stages may be individual to each stream, and a reducing electron lens may be inserted between these stages and later common stages of smaller size, Fig. 3 (not shown).