GB577120A - Improvements relating to oscillographic apparatus - Google Patents

Abstract

577,120. Cathode-ray oscillographs. COSSOR, Ltd., A. C., and MELCHIOR, A. N. April 19, 1944, No. 7267. [Class 37] Apparatus for marking a time-scale on oscillograph films comprises a luminescent screen subjected to bombardment by an electron current whose intensity may be varied, and means for focussing the light from this source upon the film alongside and at the same time as the oscillographic trace. The source 3 comprises a cathode 10 and heater 11, the modulating grid 12 and anodes 13, which are provided with holes through which a beam of electrons impinges on the luminescent screen 9. The illuminated spot so formed is focussed by lenses 4, 8 and prisms 5, 6 upon the camera drum 2, adjacent to the image produced from the oscillograph tube 1 by the lens system 7. The heater of the tube 3 may be supplied with A.C. from the transformer 14 which is provided with an H.T. winding supplying the rectifier 15 and smoothing circuit comprising resistance 17 and condensers 16. One end of the smoothing circuit is connected to the anodes 13. The cathode 3 is connected to an adjustable tapping 22 on the potentiometer 21 to provide a brightness control, and the grid 12 via a limiting resistance 19 and the resistance 20 to the negative supply. The modulation is applied across the resistance 20 and may be derived from a sinisoidal source connected to the terminals 23, 24 by means of an amplifier 25 and limiter 26. Alternatively pulses from a synchronised pulse generator may be used, or the modulation may be derived from a mechanical interruptorcontrolled by apparatus under test. A switching circuit 27 may be provided and so connected to contacts on the drum 2 and to the oscillograph 1 and amplifier 25 that the light sources are only switched on during a single revolution of the drum.