GB456709A - Improvements in and relating to television and like systems - Google Patents

Abstract

456,709. Television. PERCIVAL, W. S., 2, Ealing Village, Hangar Lane, Ealing, London, and MANIFOLD, M. BOWMAN-, Heathcot, Worplesdon Station, Surrey. April 9, 1935, Nos. 9710/36 (divided out of 456,651) and 13733/35. [Class 40 (iii)] The beginnings of field-traversal signals for interlaced scanning are in phase with the beginnings of line-synchronizing signals in intervals between trains of picture signals, and successive field-traversal signals are of different wave form, Figs. 1 and 2 (not shown). The signals are applied negatively to valves 21, 22 to interrupt the anode current and cause triangular positive pulses across condensers 36, 37 which are greater in the case of the field-traversal signals. The cathode of a diode 33 is connected to a positive potential on a potentiometer 31 such that current flows only when a field-traversal signal is operative, and the cathode of a diode 32 is connected to a more positive potential such that only alternate longer field-traversal signals cause current to flow. Windings 34, 35 control blocking oscillators as described in Specification 455,375. According to a modification the field-traversal signals are integrated across a condenser and trigger a blocking oscillator after attaining a critical voltage in a time which differs for alternate field traversals, Fig. 3 (not shown). Specifications 425,220, 438,905, [Group XX], and 456,564 also are referred to.