1. Field of the Invention
The present invention relates to an improved mechanism for generating harmony in an electronic organ, and more particularly, pertains to an organ system controlled by digital logic circuitry wherein played notes of the accompaniment keyboard can be automatically octavely rearranged so as to be positioned in a specified relationship to the lowest note played on the solo manual.
2. Description of the Prior Art
A variety of devices for generating harmony or other fill-in notes are known in the prior art. For example, U.S. Pats. No. 3,240,857--Munch U.S. Pat. No. 3,470,306--Hadden, U.S. Pat. No. 3,509,262--Munch, U.S. Pat. No. 3,558,794--Hadden, all assigned to the same assignee as the present invention, all disclose systems which generate notes associated with the pedal division of an organ based upon keys played on the accompaniment manual of the organ. These systems accomplish this result variously by means of arrays of multiple contact switches, preference circuitry, and frequency dividers. A similar system is disclosed in U.S. Pat. No. 3,565,995--Bunger, assigned to the same assignee as the present invention, which pertains to a system for causing played accompaniment notes to be sounded through the filters associated with the solo keyboard by means of FET gates under the control of DC circuitry which is triggered by the playing of a key on the solo manual.
In addition, for example, U.S. Pat. No. 3,929,051 to Moore, et al. discloses a system which uses time division multiplexing to transmit key switch information to appropriate tone generators. The Moore system generates harmony notes by producing "supplementary" pulses on the signal which carries Moore's key switch information. These pulses are added to the signal by passing through an electronic window when a pulse associated with a played accompaniment note coincides with the window. U.S. Pat. No. 3,283,056 to Cookerly, and U.S. Pat. No. 3,247,310 to Stinson both disclose devices for generating fill-in notes via an array of ganged switches which are disposed between the tone signal sources and the output system. The playing of a solo key closes one or more switches which enable a section of the solo keyboard, and the playing of an accompaniment key causes one or more of the enabled solo notes to sound.
Copending application, Ser. No. 40,107, filed May 18, 1979, for "Automatic Control Apparatus For Chords And Sequences," issued into U.S. Pat. No. 4,292,874 on Oct. 6, 1981(assigned to the same assignee as the present invention) shows an apparatus for generating chords and sequences based upon a single tonic note selected by the instrumentalist, using stored digital representations of the tonic note and the chords and sequences. However, this apparatus does not generate fill-in notes based on certain played notes for sounding in a position dependent upon other played notes.
Thus, none of the prior art systems uses digital storage of played key data to generate fill-in notes responsive to at least two played keys.