Abstract: A key signature actuator for a musical keyboard eases playing from music written with difficult key signatures by automatically actuating the sharps or flats in the key signatures. The keyboard has five back digitals per octave span, like the traditional keyboard, except that the back digitals are de-emphasized as landmarks by making them light gray, and musical notes are associated with movable landmarks, rather than with fixed digitals. When in written music a key signature is indicated, the landmarks are electronically shifted so that the key note of that key signature is played by a tonic digital (a fixed front digital to the immediate left of a group of two back digitals). At the same time the tonic digital is made to sound the key tone corresponding to that key signature by adjusting the overall pitch of the musical output by means of a uniform pitch changer. The number of electrically changeable landmark elements is minimized and binary coding is used to simplify the electrical connections.

Abstract: An electrically-keyed musical instrument has a double-row keyboard in which back digitals alternate with front digitals throughout the keyboard. The keyboard is provided with two sets of landmarks to assist playing from either the traditional notation or a six-tone notation. The musical instrument has an electronic key signature actuator apparatus which may be set to physically actuate any key signature of music written in the traditional notation, so that the diatonic tones in the selected key can be played entirely on the front digitals of the keyboard. The other five tones of the chromatic scale must be played on back digitals of the keyboard. The electronic apparatus also allows the front digitals to play the whole-tone scale or a hexachord scale, and to play the hexachord scale in any selected one of twelve different hexachord keys. A person trained on the instrument in a six-tone notation can, by throwing a switch, easily play music written in the traditional notation.

Abstract: The organ plays either a hexatonic scale or the diatonic scale on its front digitals. The organ has a tone transposition apparatus comprising a scale selector apparatus, a key selector apparatus and an absolute pitch changer switch. The key selector apparatus includes a hexachord key selector switch in cascade with a diatonic key selector switch. Each key selector switch is formed by two linear arrays of movable contacts sliding along two linear arrays of stationary contacts. Either of these key selector switches can be set to physically activate key signatures of written music. The key selector apparatus operates on the top octave of tones; lower tones are derived from the top octave by frequency division.