Patent US 6,392,131

A device for input of musical notes and chords, each triad including a plurality of musical notes and being classified into types according to a number of notes in the chord and the tonal relationship among the notes, includes a plurality of input devices each associated with a note. The input devices are arranged in spatial relationship to each other such that the spatial relationship of input devices required to play a type of chord is the same for all triads of that type.