GB356880A - Improvements in or relating to television and like systems - Google Patents

Abstract

356,880. Television. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.-(Assignees of Smith, T. A.; Ridgewood, New Jersey, U.S.A.) July 21, 1930, No. 22014. Convention date, July 19, 1929. [Class 40 (iii).] In the transmission of a motion-picture film moved uniformly and continuously, the frame lines between successive pictures are not scanned and a mask is interposed to restrict the scanning beam laterally to the picture portion of the film. A light beam from a source 13 passes through the apertures 19 of a scanning disc 17, and after modulation by the film 1, moved uniformly and continuously by sprockets 9, is incident on a photoelectric cell 23. The apertures 19 are arranged in a spiral of small pitch such that the radial distance between the first and last holes a, c corresponds to the width occupied by the frame lines 25, which are thus omitted from the scanning. A mask 28, which may be in front of or behind the film, is of such a width that the scanning beam is limited laterally to the picture portion of the film. An accompanying sound record 30 may be analyzed separately and transmitted simultaneously with the picture currents. The apertures of the disc 17 may be replaced by lenses or mirrors. A drum type scanning member with an internally arranged light-source or alternatively a scanning system comprising a fixed back of mirrors and a rotary scanning element as described in Specification 351,972 may be employed. At the receiving station the signals are applied to a glow lamp operating in conjunction with the usual Nipkow spiral disc.