GB987976A - Improvements in and relating to strip-perforating means - Google Patents

Abstract

987,976. Automatic control of registration. ASSOCIATED ELECTRICAL INDUSTRIES Ltd. Sept. 18,1961 [Sept. 16, 1960], No. 31957/60. Heading G3R. In a control arrangement for positioning strips moving longitudinally a device driven by a shaft perforates the strips in positions related to masked points on the strips and a device, responsive to signals from pick-ups sensing the perforations and marks, derives an error signal, representing the deviation of the distance between a perforation and a mark from a predetermined valve, which is used to control the drive to the shaft. As shown, perforations in a web 1 are detected by a photo-electric pick-up 26 and a registration mark 25 is detected by a pick-up 27 displaced in the direction of retrip movement A. The differentiated output from the pick-ups control an electronic switch 12 to determine the time for which an integrator 15 integrates the direct voltage output of a tachogenerator 11 coupled to the movement of the strip 1. An electronic switch 16 is triggered by the differentiated output of pick-up 27 so as to pass the output signal from the integrator which is a measure of distance between mark 25 and perforation 28, to a comparator 17 supplied with a reference voltage at terminals 20, 21, from a source, not shown. The resultant signal representative of the variation in registration, is applied through a known system to a differential gear, not shown, in the drive to a perforator, not shown. The integrator 15 is reset through a time delay device 19 from the differentiated output of pick-up 27, or, when the switch 12 is controlled by positive pulses produced by differentiating the pick-up outputs, the integrator 15 is reset by a negative pulse occurring when the trailing edge of the register mark 25 passes the device 27; the delay unit being dispensed with. The tachogenerator 11 can be replaced by a pulse generator coupled to the strip. Specification 914,819 is referred to.