GB1166092A - Photo-Electric Copying Systems - Google Patents

Abstract

1,166,092. Template followers. VOLGOGRADSKY NAUCHNO - ISSLEDOVATELSKY INSTITUT TEKHNOLOGII MASHINOSTROENIA. Aug. 18, 1966, No.37041/66. Heading G3N. A photo-electric copying system for controlling gas-cutting machines and machine tools comprises a non-rotatable photo-head, with a circular optical scanning light beam intersecting a drawn line, having a sensing element connected in cascade to a unidirectional limiting amplifier, a differentiating circuit and a phase synchronized time selector whereby a pulse from the differentiating circuit, corresponding to the forward point at which the light beam crosses the line, is selected and shaped to an approximately sinusoidal voltage and used to control the machine drive motors. As shown, the circular light scan of a non- rotatable photo-head 1 intersects a drawing line so that phase-modulated photo-current pulses are developed and fed through a unidirectional limiting amplifier 3 to a differentiating circuit 4. The leading edge of a pulse from the circuit 4 corresponds to the maximum of a photo-current pulse and is fed to a time selector 5 which selects the pulses corresponding to the leading point of the scan. The time selector incorporates a coincidence circuit 6, comprising a double-triode with common anode load, connected to the circuit 4 and a phase shifter 9 whereby a scan dependent pulse is selected which is fed to a multi-vibrator 7 generating a rectangular voltage which is shaped to a sinusoidal voltage in a valve-filter 8. The valve filter energizes, through a transformer, not shown, to which is coupled the phase shifter 9, phase detectors 10, formed by Scott-connected transformers deriving quadrature signals Vx, Vy which are fed to a positioning system for a machine and a copying table. The machine is positioned Fig. 2, (not shown), by D. C. motors controlled by amplidynes, feedback being applied through tachogenerator. A copying table is positioned in correspondence by selsyns.