Abstract A keyboard type electronic musical instrument, having a group of twelve keys per octave for playing the even tempered scale, is adapted to sound the quarter tone between two notes of the even tempered scale when the keys corresponding to said two notes are simultaneously operated. The instrument employs a voltage controlled oscillator, a voltage source having output voltages proportional to the frequencies of the notes of the scale, a group of key operated switches and series resistors for selectively connecting the oscillator to the voltage source. The resistors of operated switches form a voltage divider when two keys are simultaneously operated and a voltage equal to the average of the converted voltages is applied to the oscillator to produce the intermediate tone.
In a keyboard electronic musical instrument comprising a keyboard provided with at least one group of twelve keys for one octave, in combination, an electrical power source having a plurality of output points delivering a plurality of output voltages proportional to the frequencies of the tones corresponding to said keys, a switch for each key operated by the key, a resistor connected in series with each switch, the resistances of said resistors being substantially equal to each other and large compared to the impedance of the power source and a voltage controlled oscillator having a control voltage input terminal, each switch and series connected resistor being separately connected between said control voltage input terminal and the power source terminal corresponding to the switch and associated key, whereby actuation of the keys individually applies corresponding voltages to the voltage controlled oscillator and simultaneous actuation of two keys applies a voltage intermediate the voltages of the switch connected points to the voltage controlled oscillator.
Claim 2
Dependent Claim
162 words
In a keyboard electronic musical instrument comprising a keyboard provided with at least one group of twelve keys for one octave, in combination, an electrical power source having a plurality of output points delivering a plurality of output voltages proportional to the frequencies of the tones corresponding to said keys, a switch for each key operated by the key, a resistor connected in series with each switch, the resistances of said resistors being substantially equal to each other and large compared to the impedance of the power source and a voltage controlled oscillator having a control voltage input terminal, each switch and series connected resistor being separately connected between said control voltage input terminal and the power source terminal corresponding to the switch and associated key, whereby actuation of the keys individually applies corresponding voltages to the voltage controlled oscillator and simultaneous actuation of two keys applies a voltage intermediate the voltages of the switch connected points to the voltage controlled oscillator.
Claim 3
Dependent Claim
37 words
A circuit for a keyboard type electronic musical instrument according to claim 1 in which said power source includes a plurality of resistors connected in series with the junctions between the resistors connected to said output points.