An optical analog rocker in which mechanical movements of a manipulated control rod of the rocker are converted into electronic signals by means of an infrared emitter and an infrared receiver. The infrared receiver shifts relative to the infrared emitter when the control rod is swayed in different directions...http://www.google.es/patents/US5640177?utm_source=gb-gplus-sharePatente US5640177 - Optical analog rocker
