Pulse train generator for rotating toothed wheel of rotary printer - comprises permanent magnet biassed Hall-effect sensors associated with pole surfaces, which are distributed around wheel at angles less than teeth sepn. angles

摘要

The passage of teeth (Z), arranged at uniform spacing (TZ) on the wheel (ZR), is detected by permanent-magnet-biased Hall effect transducers or sensors (S1-S10) with their outputs (A1-A10) connected to a signal-combining circuit. The spacing (TS) of the sensors is reduced w.r.t. that of the teeth in the ratio TS/TZ = (N-1)/N where N is the number of sensors. The combinatorial logic gives N pulses of output when each tooth moves into the position vacated by its predecessor. USE/ADVANTAGE - Esp. on rotary printing presses, simple tachometer or angular position encoder has high precision and resolution increasing with number of teeth to provide speed-proportional signal.