Music synthesizer keyboard

Claim 2

In an electronic system, in combination: means for providing a plurality of voltages of different values; means for selecting at least two of said voltages substantially simultaneously; mEans for providing a reference voltage; means for deriving a difference signal from the values of said reference voltage and one of the selected voltages; means for deriving an output signal from the values of said difference signal and the other of said selected voltages; and means for generating two signals having frequencies in accordance respectively with the values of said output signal and said other of said selected voltages.

Claim 3

In a system as defined in claim 1, wherein said means for providing said plurality of voltages comprises a voltage divider, and said means for selecting comprises a plurality of switching means each having an input terminal connected to a respective tap in said divider, the output terminals of all of said switching means being connected to a common bus.

Claim 4

In a system as defined in claim 2 wherein said difference signal is proportional to the voltage drop along said divider between the taps closest to opposite ends of said divider and connected to at least two corresponding switching means in closed condition.

Claim 5

In a system as defined in claim 1 wherein said output signal is a voltage and said means for generating two signals comprises a pair of voltage-controlled oscillators.

Claim 6

Electronic musical apparatus comprising, in combination: a voltage divider having a plurality of taps each adapted to have a unique voltage thereon selected in order from a set of voltage levels which progressively increase in said order from a predetermined initial minimum amplitude, a like plurality of key-operated switches each having an input terminal connected to a corresponding tap, all output terminals of said switches being coupled to a common bus, a source of reference voltage, means for summing said reference voltage with a first signal derived from the maximum voltage level on said taps when one or more of said switches are closed so as to produce a difference signal; first and second oscillators for providing output signals having frequencies variable in accordance with variations in respective control signals; means for applying to said first oscillator a first control signal derived from the lowest voltage level of the taps connected to closed ones of said switches; means for summing said difference signal with said first control signal so as to derive a second control signal; and means for applying said second control signal to said second oscillator.

Claim 7

Electronic musical apparatus comprising, in combination: a voltage divider having a plurality of taps each adapted to have a unique voltage thereon selected in order from a set of voltage levels which progressively increase in said order from a predetermined initial minimum amplitude, a like plurality of key-operated switches each having an input terminal connected to a corresponding tap, all output terminals of said switches being coupled to a common bus, a source of reference voltage, means for summing said reference voltage with a first signal derived from the maximum voltage level on said taps when one or more of said switches are closed so as to produce a difference signal; first and second oscillators for providing output signals having frequencies variable in accordance with variations in respective control signals; means for applying to said first oscillator a first control signal derived from the lowest voltage level of the taps connected to closed ones of said switches; means for summing said difference signal with said first control signal so as to derive a second control signal; and means for applying said second control signal to said second oscillator.

Claim 8

Apparatus as defined in claim 5 wherein said difference signal is proportional to the voltage drop along said divider between the tap coupled to the closed switch corresponding to the maximum voltage level selected on the divider and the tap coupled to the closed switch corresponding to said lowest voltage level.