Improved position encoder

摘要

A sensor failure detection circuit for a position encoder, the sensor failure detection circuit receiving from a first set of at least one position sensor position signals (51a-c) which change state at a high resolution and from a second set of at least one position sensor position signals (52a-c) which change state at a lower resolution, the detection circuit monitoring a count for the position signals at the high resolution between states of the position signals at the lower resolution and comparing the count with a predetermined range which represents an expected count for the position signals at the high resolution between the states of the position signals at the lower resolution. <IMAGE>