Method of initializing an optical encoder

Abstract From the Canadian patent

A method of initializing the position of an optical shaft encoder without having to precisely index the encoder with respect to its shaft. The optical encoder includes an optical shutter mounted for rotation with the shaft and light emitters and light detectors associated with the optical shutter for respectively illuminating and detecting a predetermined pattern of code markings formed on the optical shutter. An electrical circuit such as a, suitably programmed microprocessor is responsive to the status of, the light emitters and light detectors for determining the angular position of the optical shutter and shaft relative to the light emitters and detectors from the detected predetermined …