Photoelectric position detector for angular position encoding device - comprises annular semiconductor diode onto which beam of light is deflected from semi-transparent mirror

摘要

The annular photodiode is constructed with a resistance around its outer rim from which a large number of electrically conductive layers extend inwards at uniform angular spacing as far as the inner rim. Output electrodes (35) are arranged at intervals of 45 deg. and connected to the resistance and numbered in clockwise order. The position of a spot of light on the photodiode corresponds to the deg. of rotation about an axis through the centre of the annulus. ADVANTAGE - Point of impact of spot of light on ring can be detected in any region with high precision.