DISPOSITIVO OTTICO PER DETERMINARE LA POSIZIONE DI UN ORGANO MOBILE

1515467 Position measurement SOC D'APPLICATIONS GENERALES D'ELECTRICITE ET DE MECANIQUE 4 May 1976 [7 May 1975] 18064/76 Heading H3H] The relative position of a scale carried by a first member and detector carried by a second is determined by the position of the image, formed by system 9, 12, of a scale mark 15 on the detector 13. The detector comprises a linear matrix of photosensitive devices which extend over the image length of one scale interval, the scale mark being identified by reference 16 which is also read by the detector. In the embodiment the mark and binary reference number are read by a linear array of 256 photodiodes 19 which in turn are serially scanned by clock pulses, a shift register takes the most recent results and a pattern recognizer halts scanning pulses incrementing counter 35 when the scale mark is found. Scanning continues to read the identification code into the register in response to gating pulses derived from division circuits 40. The contents of the register 26 are transferred to register 48, which together with register 47 connected to counter 35 form the output stage.