Transducer drive circuit and signal generator

Claim 2

An audio signal generator for operation from a power supply, comprising in combination: a transducer operative to provide a damped output signal alternating between successively decreasing maximum values thereof when electrically energized; a switching means connected to said transducer for applying an in-phase, boosting signal to said transducer; means actuating said switching means when said output signal approaches a maximum value, said actuating means including means providing a threshold signal whose voltage is less than that of said maximum value of said transducer output signal, and wherein said switching means includes a comparison means operable to provide said in-phase boosting signal when the voltage on said transducer substantially equals the voltage of said threshold signal; and means connecting the power supply to said transducer, said switching means and said actuating means.

Claim 3

An audio signal generator as recited in claim 1, wherein said transducer comprises a piezoelectric element.

Claim 4

An audio signal generator as recited in claim 1, wherein said threshold signal means includes a timing circuit which produces an outPut voltage which increases with respect to time in synchronism with said output signal, and said comparison means in said switching means includes at least one semi-conductor element having first and second electrodes respectively connected to said timing circuit and to said transducer, said semi-conductor element remaining non-conductive until the voltages on said two electrodes become substantially equal.

Claim 5

An audio signal generator as recited in claim 3, wherein said semiconductor element comprises a programmable unijunction transistor having a gate electrode connected to said transducer element and an anode electrode connected to said timing means.

Claim 6

An audio signal generator as recited in claim 3, wherein said semiconductor element comprises a silicon controlled switch having a gate electrode connected to said transducer element and an anode electrode connected to said timing means.

Claim 7

A signal generator comprising in combination: an electrically sensitive transducer means including a piezoelectric element; timing circuit means; power supply means connected to said transducer means and timing circuit means; and signal comparison and switch means connected to said transducer means, said timing circuit means and said power supply means, said timing circuit means including means providing a signal having a voltage which rises to the voltage on said transducer means as the voltage on said transducer means is approaching a maximum value, and said comparison and switch means includes means operative when the voltage on said transducer means substantially equals the voltage of said timing signal to apply an in-phase, boosting signal to said transducer means.

Claim 8

A signal generator comprising in combination: an electrically sensitive transducer means including a piezoelectric element; timing circuit means; power supply means connected to said transducer means and timing circuit means; and signal comparison and switch means connected to said transducer means, said timing circuit means and said power supply means, said timing circuit means including means providing a signal having a voltage which rises to the voltage on said transducer means as the voltage on said transducer means is approaching a maximum value, and said comparison and switch means includes means operative when the voltage on said transducer means substantially equals the voltage of said timing signal to apply an in-phase, boosting signal to said transducer means.

Claim 9

A signal generator as recited in claim 6, wherein said signal comparison and switch means includes at least one semiconductor element having first and second electrodes respectively connected to the timing circuit means and to the transducer means, said element remaining non-conductive until the voltages on said two electrodes become substantially equal.

Claim 10

A signal generator as recited in claim 6, wherein said semiconductor element is maintained non-conductive during at least 50 percent of each cycle of said transducer means.

Claim 11

A signal generator as recited in claim 6, wherein said transducer means forms part of a sonic signal generator.

Claim 12

A sonic signal generator comprising in combination: power supply means having first and second terminals; a transducer element including a piezoelectric crystal having first and second electrodes; first and second impedance elements connecting said first and second electrodes to said first and second terminals of said power supply means; first circuit means including a capacitor having a first side connected to said first electrode, said first circuit means further including means connecting a second side of said capacitor to said first terminal of said power supply means; and second circuit means including a semiconductor element having a first electrode connected to said second terminal of said power supply means and second and third electrodes respectively connected to said second side of said capacitor and to said second electrode of said transducer element, said semiconductor element thereby being maintained non-conductive until the voltages on its said second and third electrodes are substantially equal.

Claim 13

A sonic signal generator comprising in combination: power supply means having first and second terminals; a transducer element including a piezoelectric crystal having first and second electrodes; first and second impedance elements connecting said first and second electrodes to said first and second terminals of said power supply means; first circuit means including a capacitor having a first side connected to said first electrode, said first circuit means further including means connecting a second side of said capacitor to said first terminal of said power supply means; and second circuit means including a semiconductor element having a first electrode connected to said second terminal of said power supply means and second and third electrodes respectively connected to said second side of said capacitor and to said second electrode of said transducer element, said semiconductor element thereby being maintained non-conductive until the voltages on its said second and third electrodes are substantially equal.

Claim 14

A sonic signal generator as recited in claim 10, wherein said connecting means in said first circuit means further comprises a third impedance element connecting said capacitor to said power supply means so that the rate of charge of said capacitor is less than the rate of voltage increase on said transducer element.

Claim 15

A sonic signal generator as recited in claim 10, wherein said semiconductor element comprises a programmable unijunction transistor having an anode electrode connected to said semiconductor''s second electrode and a gate electrode connected as said semiconductor''s third electrode.

Claim 16

A sonic signal generator as recited in claim 10, wherein said semiconductor element comprises a silicon control switch having an anode electrode connected as said semiconductor''s second electrode and a gate electrode connected as said semiconductor''s third electrode.