Keyboard attachment for pianos and similar instruments - has series of twenty seven keys arranged in three rows

摘要

A keyboard attachment for a piano or similar instrument constructed on a system of tone octaves, of which two are provided for each piano etc producing completely separate sounds has the tone octave encompassing 27 notes, 7 ground notes of the diatonic scale, 10 harmonic-natural neighbour notes and 10 half stage notes. The keyboard is arranged in three layers (1, 2, 3) of which the lowest row (3) produces the 7 base notes plus notes of the harmonic-natural group. The middle row (2) represents the remaining harmonic natural group plus one half stage note. The upper row (1) contains only half stage notes. Each note can only be depressed as far as the rest plane of the corresponding note one row lower.