GB474970A - Improved scanning method for television and like systems - Google Patents

Abstract

474,970. Television. SCOPHONY, Ltd., and OKOLICSANYI, F. VON. Feb. 5, 1936, Nos. 3456 and 10856. [Class 40 (iii)] A liquid, in which compressional waves of supersonic frequency travel, is illuminated at an angle to the direction of the waves, either the part of the emergent light which maintains its original direction or the part which is deviated is selected to form a moving image of the waves on a screen 25, and electric impulses at the line frequency so control either the duration of the illumination or the active length of the waves, or both, that the elemental areas of one line are periodically illuminated at the line frequency for a time which is equal to the duration of a line divided by the number of elements in the line. Received television signals control a Kerr cell 21, and synchronizing signals, which have been modified in a circuit 29, Figs. 4 and 5 (not shown), to have a duration equal to that of an elemental area, modulate a high-frequency 31 and are applied to a quartz crystal in the liquid in a cell 22, as described in Specification 439,236. Undeflected light from the source 20 is blocked by a stop 23, but light corresponding to diffraction images caused by the compressional wave form, on the screen 25, a moving spot of light which is modulated by the Kerr cell. The lower speed component of scanning is given by a mirror drum 26, or by an additional compressional wave cell, Fig. 19 (not shown). The two cells may be interchanged, when compressional waves corresponding to a whole line occur at one time in the liquid and are illuminated at intervals by the Kerr cell. The Kerr cell may be replaced by a second cell carrying compressional waves, Fig. 8 (not shown), and the two sets of waves preferably move in opposite directions, Fig. 10 (not shown). The two cells may be combined in a single container, Fig. 11 (not shown). The undeflected light may be used instead of the deflected light, and the excitation of the cells suitably reversed. The apparatus may be used in a direct transmitter, Fig. 18 (not shown), or in a transmitter of kinema films, Figs. 16 and 17 (not shown). Light valves, Fig. 13. To use the whole aperture of the lens 24, a plurality of crystals 80 face in different directions 86 ... 88. The signals are applied in parallel, and the cell is illuminated from a source 76 through a similar plurality of apertures 77, each of which gives a beam at right-angles to one of the sets of compressional waves 86 ... 88. A similar number of stops 82 is also provided. Specification 433,945 also is referred to.