Improvements in or relating to function generators and resolvers

摘要

897,302. Electric selective signalling systems. CANADA, MINISTER OF NATIONAL DEFENCE. Sept. 16, 1958, No. 29648/58. Class 40 (1). A device for producing a number of pulses proportional to a desired function of an angular displacement comprises a photo-electrically sensed disc, Fig. 2, having marks spaced in accordance with the derivative of the desired function. As described, the desired function is sin # and the marks on track 22, Fig. 2, are spaced in accordance with cos #. To generate sin # a pick-up cell is arranged on the zero line to sense track 22 and the disc is then turned through the angle #. The number of marks sensed by the cell is then proportional to sin # and a second cell positioned over a track 23 indicates whether the marks are to be counted positively or negatively. In the preferred embodiment a fixed cell and also an angularlydisplaceable cell are provided and it is arranged that the disc be given a complete revolution but that counting of the marks sensed on track 23 occurs only for the period between the sensing of the zero mark by the fixed cell and its sensing by the angularly-displaced cell. Thus for each revolution of the disc sin # is entered once into a counter so that by rotating the disc A times it is possible . to form the product A sin #. Cos # can also be generated by a sensing cell over track 22 displaced from the sin # cell by 90 degrees. An outer track on the disc contains evenly-spaced marks, which, by being counted, give the actual angle turned through by the disc.