A method for the production of several line periods by means of permanent image repetition - or zeilenzugwechselimpulsen for television via support with a continuous line synchronizing means of a lead

摘要

448,031. Television. CORK, E. C., 50A, Kenilworth Road, Ealing, London, MANIFOLD, M. BOWMAN-, Heathcot, near Worplesdon Station, Woking, Surrey, and BROWNE, C. O., 29, Monk's Drive, West Acton, London. Aug. 31, 1934, Nos. 25181/34, 29874/34, and 7205/35. [Class 40 (iii)] The framing-signals in an interlaced scanning system have leading edges at a multiple of the strip frequency which is equal to the number of partial scans in a complete scan, and some of the leading edges are in phase with the strip signals. When there are two partial scans to a complete scan, each mirror on a drum 77 sweeps the image of an illuminated aperture 64 over photo-electric cells 81, 68, 69 in succession. The cell 69 is connected to an amplifier in one sense to produce stripsynchronizing signals, and the cells 68, 81 are connected in an opposite sense to produce suppressing-impulses, which occur just before the strip impulses and mid-way between these positions. Long framing-impulses in the same sense as the strip impulses are applied across terminals 72. A valve 71 has grid-bias 73 such that the suppressing-impulses are cut off except during the framing-impulses, and grid current through a high resistance 74 cuts off the strip signals during the framing impulses, Fig. 6 (not shown). According to modifications : the synchronizing-signals are generated as described in Specification 445,912, Figs. 9-12 (not shown) ; or by an apertured disc, Figs. 15-16 (not shown); the synchronizing signals and the suppressing- impulses, which are generated as described in Specification 442,938, are mixed in a hexode and a tetrode valve in parallel, Fig. 14 (not shown). Specifications 438,905, [Group XX], 443,699, and 448,065 also are referred to.