GB681541A - Improvements in telecinematography - Google Patents

Abstract

681,541. Television. PARAMOUNT PICTURES, Inc. Aug. 5, 1947 [March 20, 1946], No. 21239/47. Class 40 (iii). Apparatus for photographing with a standard kinematograph camera the image on the screen of a television receiver tube operating at a different standard rate comprises an electronic generator operating at the same frequency as the camera and producing pulses which blank out the cathode-ray beam during the intervals of film movement. In the system shown, for a television system producing 30 double-interlaced pictures per sec. and a camera having 24 exposures per sec., 60-cycle power frequency is rectified by a full-wave rectifier 1 and the rectified output controls a blocking oscillator 2 producing 120 pulses per second which in turn control a multi-vibrator 3 producing 24 squarewave pulses per second, each having a duration of <1>/120th of a second, the normal duration of film movement. These pulses are applied as blanking pulses to the reproducing tube 4. The camera 5 is also driven from the 60-cycle mains and produces similar pulses which are synchronized in phase with the blanking pulses with the aid of a monitor tube 6 to which both sets of pulses are fed. The shutter is removed from the camera and, to prevent light on the screen affecting the film during film movement, the screen of the tube 4 is of the short-persistence type.