LOAD-SENSITIVE GENERATOR FOR DRIVING PIEZO-ELECTRIC TRANSDUCERS

• US 3,668,486 A
• Filed: 01/08/1971
• Issued: 06/06/1972
• Est. Priority Date: 01/08/1971
• Status: Expired due to Term

• Current Assignee: Ultrasonic Power Corporation
• Original Assignee: Joseph Silver
• Inventors: Silver, Joseph
• Primary Examiner(s): Duggan, D. F.
• Application Number:
  US05/104,957
• Time in Patent Office: 515 Days
• Field of Search: 331/116R,158,159 318/114,116,118 310/8.1,26
• US Class Current: 318/116
• CPC Class Codes: B06B 1/0261 taken from a transducer or electrode connected to the driving transducer
• CPC Class Codes: B06B 2201/55 Piezoelectric transducer

Abstract

An oscillatory circuit, operating in the ultrasonic or high sonic frequencies, generates power for a piezo-electric transducer in proportion to mechanical resistances or loadings encountered by the transducer. High sensitivity and instantaneous power adjustment to a wide variety of loads is obtained, and instant '"'"''"'"''"'"''"'"'turn-on'"'"''"'"''"'"''"'"' and '"'"''"'"''"'"''"'"'turn-off'"'"''"'"''"'"''"'"' at the adjusted power settings are secured, by a circuit in which the input to the first stage of a two-stage oscillatory circuit comprises the sum of three feedback components plus a DC forward bias.

Claims

1. An electrical generator for supplying power to a piezoelectric transducer, comprising an oscillatory circuit having an input and output connectable respectively to a power source and a transducer to be driven, said circuit including a feedback component taken from the output and sensitive to changes in the output voltage of said circuit, said component developing a proportionately adjusted voltage feeding back into the input end of said circuit for oscillation thereof, said generator including first and second amplifier stages in said circuit, said generator further including means for starting up said circuit under load, said means including a second feedback voltage component taken from the output of the first stage and extending as a loop back to the first stage input.

2. A generator as in claim 1 further including a third feedback component inductively derived from the output of said second stage and feeding back to the input of the first stage to adjust current feeding into the first stage in proportion to mechanical loadings imposed on said transducer.

3. A generator as in claim 2, further including a first transformer connected with said second stage and a second transformer connected between the first transformer and the transducer, the primary inductance of said second transformer being in series between the first transformer and transducer to develop varying resonance voltages, which voltages are a sensitive function of varying mechanical loadings imposed upon the transducer and hence are productive of said one feedback component, said third component being taken from said second transformer.

4. A generator as in claim 3 wherein said second transformer includes a secondary winding in which said third feedback component is developed as a transformed fraction of the resonance voltage present in said primary inductance.

5. A generator as in claim 4 wherein the first and second stages are coupled by a third transformer having a secondary winding in which said second feedback component is developed.

6. A generator as in claim 5 wherein the main power source is a DC bias current feeding directly into said first stage.

7. A generator as in claim 6 wherein there is a summing of the several feedback components and the DC bias at the input of the first stage.

8. An electrical generator for supplying power to a piezo-electric transducer, comprising an oscillatory circuit having an input and output connectable respectively to a power source and a transducer to be driven, said circuit including a feedback component taken from the output and sensitive to changes in the output voltage of said circuit, said component developing a proportionately adjusted voltage feeding back into the input end of said circuit for oscillation thereof, said generator further includinG a DC bias current feed to the resonant circuit and an on-off control for the resonant circuit in the form of a relay having normally closed contacts opening responsive to energizing of the relay, said contacts when closed grounding the feed of DC bias current to the resonant circuit while leaving the biasing circuit in a stand-by condition, said contacts when opened breaking the grounding connection to initiate feed of the bias current to the resonant circuit without production of heavy line voltage current surge normally occurring in said DC bias current in the presence of start-up conditions.

9. A generator as in claim 8 wherein said DC bias includes a main on-off switch whereby closure of the main switch permits charging of the DC bias to put the same in stand-by condition with accompanying elimination of heavy line current surges during subsequent operation of the relay contacts to open positions, and a second on-off switch controlling the energization of the relay in the closed condition of the first switch so as to in turn control application of the DC bias to the resonant circuit.