Method and apparatus for optically sensing the position and velocity of piano keys

摘要: An electronic keyboard musical instrument is provided having optical emitters and detectors both positioned beneath each of the instrument's keys, whereby energy emitted upon bottom reflective surface key reflected light detected. The distance between optoelectronic sensor detected by detector which produces an analog output signal and, measuring time a first second threshold crossing, key's velocity can be determined. two thresholds are preferably chosen to measure rising voltage as depressed, values at 50% travel 75% travel. By use these thresholds, relatively clean useful waveform available crossings, particularly since mechanical movement has nearly reached its terminal velocity. Electronics in sequentially scan voltages produced their corresponding so that single microprocessor all position values. A set utilized for keys instrument, if desired, or have own individual depending calibration zero span conditions. interval crossings determined, turn used determine it being depressed. Once known, volume particular tone controlled sound engine, well other characteristics, such timbre, attack, envelope.