Image Number 3 for United States Patent #4833317.
An optically powered resolver for detecting an optical property of an encoder at a plurality of encoding sites on the encoder, to permit determination of the position or other state of the encoder. Each encoding site is capable of receiving an optical encoder input signal and of modulating the encoder input signal to produce an optical encoder output signal. The resolver includes a photocell for converting the optical input signals into corresponding electrical input signals, and an energy storage circuit for storing a portion of the energy of the electrical input signals. The resolver also includes an interrogation circuit for interrogating a selected encoding site with an encoder input signal in response to the receipt of an optical input signal by the resolver. Interrogation means provides an optical output signal corresponding to the resulting encoder output signal. The interrogation circuit sequentially changes the selected encoding site as optical input signals are received, and the resolver preferably operates without any external source of electrical power.