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Method of maintaining constant movement of a cutting blade on an ultrasonic waveguide

  • US 8,197,502 B2
  • Filed: 03/25/2011
  • Issued: 06/12/2012
  • Est. Priority Date: 12/03/2007
  • Status: Active Grant
First Claim
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1. A method of maintaining a constant movement of a cutting blade of an ultrasonic waveguide, which comprises:

  • providing;

    an ultrasonic transducer operable to convert a received motional current into a movement of a cutting blade of an ultrasonic waveguide, the ultrasonic transducer having a first capacitance in a parallel configuration with a series configuration of a resistance, an inductance, and a second capacitance, wherein the motional current flows through the series configuration;

    a measurement circuit connected in a parallel configuration with the ultrasonic transducer and comprising a third capacitance in a parallel configuration with the first capacitance;

    supplying current through a set of connection points of the parallel configuration with a variable power source to, thereby, create the motional current in the ultrasonic transducer, the variable power source being coupled to the third capacitance and the ultrasonic transducer; and

    regulating the motional current with a current controller by varying an output of the power source based upon a product of the current flowing through the third capacitance multiplied by a ratio between a value of the first capacitance and a value of the third capacitance subtracted from a total current flowing into the ultrasonic transducer, thereby maintaining a substantially constant rate of movement of the cutting blade across a variety of cutting loads.

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