Multi-channel key switch circuit

Claim 2

Switching system for an electric music system, comprising: a plurality of sequentially connected key switches; a corresponding plurality of tone sources connected respectively to said key switches; an output circuit for the system; first circuit means connecting the first of said switches in the sequence to said output circuit, characterized by said first circuit means having a nonlinear input impedance which is relatively high to tone signals when the voltage thereof is below a first predetermined threshold, and relatively low when said voltage is above said threshold; second circuit means connecting each of said key switches to said output circuit and having a nonlinear input impedance which is relatively high to tone signals below a second predetermined threshold voltage, and relatively low to signals above said threshold voltage, said second threshold voltage being substantially greater than said first threshold voltage; and the peak voltage of tone signals delivered by said tone sources being greater than said second threshold voltage.

Claim 3

Switching system for an electric music system, comprising: a plurality of sequentially connected key switches; a corresponding plurality of tone sources connected respectively to said key switches; an output circuit connected to the first of said switches in the sequence, characterized by a corresponding plurality of nonlinear impedances, each having one terminal thereof connected to a respective key switch, and characterized by a relatively high impedance when the voltage thereacross is below a predetermined minimum and a relatively low impedance when such voltage is above said minimum; and circuit means connecting all the respective other terminals of said impedances to said output circuit.

Claim 4

Switching system for an electric music system, comprising: a plurality of sequentially connected key switches; a corresponding plurality of tone sources connected respectively to said key switches; an output circuit connected to the first of said switches in the sequence, characterized by a corresponding plurality of nonlinear impedances, each having one terminal thereof connected to a respective key switch, and characterized by a relatively high impedance when the voltage thereacross is below a predetermined minimum and a relatively low impedance when such voltage is above said minimum; and circuit means connecting all the respective other terminals of said impedances to said output circuit.

Claim 5

In a key switching circuit for an electric musical instrument, comprising: a plurality of sequentially arranged, single-pole, double-throw key switches, each having a pole, a first contact, and a second contact; a corresponding plurality of electric tone signal sources connected to the respective second contacts of said key switches; an output circuit including speaker means; first circuit means including frequency divider means for connecting said output circuit to the pole of the first key switch in the sequence of key switches; second circuit means for connecting the poles of the remaining key switches respectively to the first contact of the immediately preceding key switch in the sequence, the improvement which comprises providing a plurality of voltage dropping resistors in the respective connections between said tone sources and said second contacts; providing the input of said first circuit means with a nonlinear impedance which presents a relatively high input impedance to tone signal below a first predetermined threshold voltage and a relatively low input impedance to signal above said first threshold voltage; third circuit means connected from each of the first contacts of said key switches to said output circuit and including frequency divider means, and a plurality of diodes connected respectively to said first contacts and poled to pass signal from said first contacts to said output circuit; said third circuit presenting to tone signal applied to said first contacts a nonlinear impedance which is relatively high when signal voltage is below a second predetermined threshold and relatively low when above said second predetermined threshold voltage; said second thrEshold voltage being substantially greater than said first threshold voltage; and the amplitude of signal voltage delivered from said tone sources being above said second threshold voltage.

Claim 6

In a key switching circuit for an electric musical instrument, comprising: a plurality of sequentially arranged, single-pole, double-throw key switches, each having a pole, a first contact, and a second contact; a corresponding plurality of electric tone signal sources connected to the respective second contacts of said key switches; an output circuit including speaker means; first circuit means including frequency divider means for connecting said output circuit to the pole of the first key switch in the sequence of key switches; second circuit means for connecting the poles of the remaining key switches respectively to the first contact of the immediately preceding key switch in the sequence, the improvement which comprises providing a plurality of voltage dropping resistors in the respective connections between said tone sources and said second contacts; providing the input of said first circuit means with a nonlinear impedance which presents a relatively high input impedance to tone signal below a first predetermined threshold voltage and a relatively low input impedance to signal above said first threshold voltage; third circuit means connected from each of the first contacts of said key switches to said output circuit and including frequency divider means, and a plurality of diodes connected respectively to said first contacts and poled to pass signal from said first contacts to said output circuit; said third circuit presenting to tone signal applied to said first contacts a nonlinear impedance which is relatively high when signal voltage is below a second predetermined threshold and relatively low when above said second predetermined threshold voltage; said second thrEshold voltage being substantially greater than said first threshold voltage; and the amplitude of signal voltage delivered from said tone sources being above said second threshold voltage.

Claim 7

In an electric musical instrument, comprising: a plurality of sources of audio frequency electric signals; a corresponding series of key switches; first circuit means for coupling each switch to a corresponding signal source; second circuit means for connecting said key switches together; output circuit means; first channel circuit means for connecting one end of the series of key switches to said output circuit means, whereby if and when a plurality of key switches are closed simultaneously, only that key switch in the series closest to said one end will effect the application of signal to said output circuit means; and the improvement which comprises second channel circuit means connected to said second circuit means and to said output circuit means, said second channel means including means for applying signal from a given key switch to said output circuit means only if a key switch closer to said one end than said given key switch is simultaneously closed.

Claim 8

In an electric musical instrument, comprising: a plurality of sources of audio frequency electric signals; a corresponding series of key switches; first circuit means for coupling each switch to a corresponding signal source; second circuit means for connecting said key switches together; output circuit means; first channel circuit means for connecting one end of the series of key switches to said output circuit means, whereby if and when a plurality of key switches are closed simultaneously, only that key switch in the series closest to said one end will effect the application of signal to said output circuit means; and the improvement which comprises second channel circuit means connected to said second circuit means and to said output circuit means, said second channel means including means for applying signal from a given key switch to said output circuit means only if a key switch closer to said one end than said given key switch is simultaneously closed.

Claim 9

The combination of Claim 4, wherein: said second circuit means comprises a plurality of series-connected impedances, said key switches being connected respectively to the junction points between said impedances; said second channel circuit means comprises circuit means for connecting the opposite end of said series of key switches to said output circuit means; and means connected to said first and second channel circuit means for inhibiting the signal applying operation of one of said channel circuit means when only a single key switch is closed.

Claim 10

The combination of Claim 4, wherein: said first channel circuit means comprises threshold impedance means for passing only audio frequency signals above a first predetermined threshold voltage; and said second channel circuit means comprises circuit means connected to each of said key switches and includes threshold impedance means for passing only audio frequency signals above a second predetermined threshold voltage higher than said first threshold voltage.