A MAGNETOOPTICAL TACHOMETER FOR ANTI-LOCK BRAKING SYSTEMS USING PLASTIC OPTICAL-FIBER

A magneto-optical tachometer specially designed for an automotive anti -lock braking system is described. It employs a plastic optical fibre for the bidirectional data transmission and its transducing mechanism is magneto-optical. It uses a Bi-substituted iron garnet as sensor ele ment and a ferromagnetic tooth gear, which produces 46 pulses per turn . Owing to its compact design and its constitutive materials it is sui table for withstanding all the environmental hazards present in the ca r. The tachometer can measure car speeds of 0-400 km h-1 with a signal variation less than 0.6 dB throughout the whole range.