METHOD OF AND APPARATUS FOR THE GENERATION OF SOUNDS, 1925. Here is the original Theremin theremin patent.
Visual display for music generated via electric apparatus, 2000. Visual aid for performers.
KEYBOARD OPERATED ELECTRICAL MUSICAL INSTRUMENT, 1959. Uses keyboard, sliding pitch for sound similar to theremin.
Synthesizer for sounds in response to three dimensional displacement of a body, 1992. Three ultrasonic transducers sense position of body in a region, drives a music synthesizer.
Musical expression pedal, 1984. Pedal uses proximity detector instead of electromechanical mechanism.
Electronic musical re-performance and editing system, 1996. Untrained instrumentalists signal pre-stored music.
Control apparatus for electronic musical instrument, 1988. Three sensors measure motion along orthogonal axes, converted to MIDI for instrument control.
Musical tone control apparatus using a detector, 1994. Very general patent.
Prop input device and method for mapping an object from a two-dimensional camera image to a three-dimensional space, 2004. Eyetoy.
Method for color transition detection, 2006. Eyetoy. A hand-manipulated prop is viewed by single video camera, and the position determined by software procedures.Can be used for game play, as well as theremin-like instrument.
Device for detecting musical gestures using collimated light, 2004. Gestures interrupt laser,controlling MIDI output.
PRACTICE KEYBOARD AND METHOD OF PRODUCING THE SAME, 1932. Claims to be useful for theremin practice as well. (Doubtful.)
TONE FREQUENCY CONTROL SYSTEM FOR ELECTRONIC MUSICAL INSTRUMENTS, 1966. Attempts to accurately reproduce human voice sound on a keyboard instrument, with portamento.
Three dimensional baton and gesture sensor, 1996. An electronic drum has two or more batons,each baton having a transmitter which transmits a distinct radio frequency signal at a position in space.