Optical encoder with integrated monitor

摘要

A sensor head for sensing light modulated by a moveable member, such as a code wheel or code strip, in an optical encoder. The sensor head has at least one monitor optical sensor and a primary optical sensor positioned to receive light modulated by a modulation track on the moveable member. The monitor optical sensor provides a monitor signal that is compared in a signal comparator to the output from the primary optical sensor to detect light at the primary sensor.