US 4,136,595 A · Single bus keyboard

Abstract

An inexpensive single bus keyboard circuit for voltage controlled electronic musical instruments. The keyboard signal voltage is sampled and stored after each depression of a key, or release of a key when other keys are held in a depressed state, and a gate detector is provided to prevent sampling and change of stored voltage when all keys are released, to thereby insure that the last stored signal voltage is retained when all keys are released. A program counter establishes the timing relationships between the generated control signals and provides adaptive timing to prevent response to spurious key switch signals. The circuit distinguishes in a simple manner between keyboard sample voltages corresponding to the depression of one or more keys and those corresponding to the condition in which no keys are depressed.

Claims7

Dependent claims

A control circuit for electronic musical instruments, comprising

A. means responsive to the playing of one or more notes on a musical instrument to generate signal levels indicative of each note, as well as at least one non-zero signal level indicative of the playing of no notes,
B. level change detection means responsive to said level generating means and providing an output in response to changes in said levels,
C. gating means responsive to said level generating means to provide a gating signal indicative of the playing of no note, and
D. means responsive to both said level change detection means and said gating means for generating a control signal only when at least one note is played and maintaining said control signal when all keys are released.

1 more element

Dependencies are inferred from the claim text.

Single bus keyboard

Life of this patent

Single bus keyboard

Life of this patent

Abstract

Claims7