GB666485A - Facsimile synchronizing signal generator - Google Patents

Abstract

666,485. Electric synchronous movements. TRIGGS, W. W. (Faximile, Inc.). Jan. 2, 1948, No. 148/48. Class 40 (iii). [Also in Group XL (c)] A facsimile synchronizing signal generator comprising a source of periodic synchronizing signals, a switching device for passing predetermined ones of said signals to a utilization device, and an element for conditioning said switching device to pass said predetermined signals, is characterized in that a storage element is connected between said switching device and said conditioning element in order to mask irregularities in the operation of the latter. A synchronizing segment 11 (Fig. 2), driven by the shaft of a facsimile transmitter applies positive bias over a timing circuit 15, 16, to the control electrode 9 of a thyratron 5. The next pulse from a square-wave generator 22 therefore fires the thyratron 5 and produces a square output pulse for synchronization purposes. The timing circuit 15, 16 maintains the control electrode at a sufficient potential even in the presence of poor rotary switch contact, so that the thyratron will still fire when the next generator pulse arrives. In a second embodiment (Fig. 4) the synchronizing segment 11 removes negative bias from a thyratron 26 to allow the next square-wave from a generator 30 to pass and so condition a second thyratron 37 to conduct when it receives a square-wave from a second generator 44. The square-waves from the second generator 44 arrive slightly later in time than those of the first generator 30. Synchronizing pulses are taken from the cathode resistor 43.