US 3,986,423 A · Polyphonic music synthesizer

Abstract

An electronic music synthesizer including a keyboard control system for enabling multiple independent voice channels (voices) to be controlled by the keyboard in a musically pleasing manner. The control system responds to a keyboard of M keys to control N voices where N<M; e.g. M=64 and N=10. The voice channels are preferably identical to one another, each being comprised of voltage controlled elements such as an oscillator (VCO), amplifier (VCA) and filter (VCF). Typically, the control system selects an available voice channel and in response to a key depression, supplies a DC control voltage thereto whose level is nominally linearly related to the note corresponding to the depressed key. In addition to the control voltage, the control system supplies a gate signal to the selected voice channel indicating the time duration of the key depression. The control system is essentially comprised of keyboard control logic and channel selection logic, both common to all of the voice channels, and channel logic units, each unique to a different voice channel. The keyboard and channel selection logic operates to assign voice channels to key depressions by sequentially sampling (scanning) the keys during a scan cycle to determine whether or not each key is depressed. Scanning is performed by a key address counter driven by clock pulses. When a depressed key is first recognized, the count in the address counter is, subject to certain logic criteria, written into a register contained in the channel logic associated with the selected voice channel. Additionally, the DC control voltage and gate signal are supplied to the selected voice channel. The channel selection logic is structured to assure that no voice channel receiving an active gate signal is pre-empted by a new key depression. Whether or not more than one voice channel can be assigned to a single key is determined by a user controlled REASSIGN mode switch. The criteria employed by the channel selection logic to select a voice channel for assignment is determined by a user controlled RESET mode switch.

Claims19

Dependent claims

A music synthesizer comprising:

a plurality of M keys each capable of defining an open or closed state;
a plurality of N voice channel means where N <m;
keyboard scan means for cyclically sequentially sampling said M keys to produce a series of bit signals, each indicative of the state of a different one of said keys;
N channel logic means each including an address register;
channel selection means coupled to said channel logic means and responsive to each sampled key in a closed state for storing an address identifying that key in one of said N address registers;
each of said channel logic means including means responsive to said series of bit signals for producing a gate signal having a duration related to the number of successive scan means cycles in which the key identified by the address stored in said channel logic means is in a closed state;
each of said channel logic means including means responsive to the address stored in the address register means thereof for producing a control voltage having a level related to that stored address;
and
means for applying said gate signal and control voltage signal produced by each of said channel logic means to a different one of said N voice channels.

6 more elements

In a music synthesizer comprised of a keyboard of M keys and a plurality of N voice channels, where N<M, each voice channel being responsive to a control voltage and a gate signal applied thereto for producing a sound whose frequency and duration are determined respectively by said control voltage and gate signal, the improvement comprising a control system for monitoring the states of said keys to produce, with respect to each closed key, a control voltage and gate signal for application to one of said voice channels, said control system comprising:

counter means for cyclically producing a series of M unique addresses, each address identifying a different one of said M keys;
means responsive to each of said M addresses for sampling the state of the identified key to produce a data signal comprised of successive bit signals, each at a first or second level respectively indicative of an open or closed key state;
N channel logic means each connected to a different one of said voice channels, each of said channel logic means including register means capable of storing a key address;
channel selection means responsive to said data signal produced by said sampling means defining said second level indicative of a closed key state for storing the address identifying that key in one of said N channel logic means registers;
means in each of said N channel logic means for producing a gate signal with respect to the key identified by the address stored therein representing the time duration that the key remains in said closed state;
and
means in each of said N channel logic means for producing a control voltage having a level related to the address therein.

4 more elements

Dependencies are inferred from the claim text.

Polyphonic music synthesizer

Life of this patent

Polyphonic music synthesizer

Life of this patent

Abstract

Claims19