Daniel R William

US Patent:

5242404, Sep 7, 1993

Filed:

Feb 12, 1992

Appl. No.:

7/834450

Inventors:

Paul G. Conley - St. Charles MO
Daniel William - Florissant MO
Peter F. Appelbaum - St. Louis MO

Assignee:

American Cyanamid Company - Stamford CT

International Classification:

A61M 3100

US Classification:

604119

Abstract:

An aspiration control system includes a motor and vacuum pump which are controlled by a system controller, in accordance with input commands to provide a precise, continuously variable vacuum or negative pressure within a vacuum chamber and surgical handpiece. The resulting vacuum is proportional to the control signal sent from the system controller to the motor. A transducer samples the vacuum output and produces a signal fed system controller. The signal is compared with a variable input signal set by a potentiometer or other signal source activated by the input commands so that the transducer signal tracks the voltage source signal. Therefore, the vacuum output of the vacuum pump and motor relates directly and predictably to the input commands. In one embodiment the motor is a brushless DC motor. The system may also include a pinch valve provided on a fluid aspiration conduit communicating between the surgical handpiece and vacuum chamber so that the fluid aspiration at the handpiece may be controlled independently from the negative pressure level created in the vacuum chamber.

US Patent:

5406503, Apr 11, 1995

Filed:

Sep 30, 1992

Appl. No.:

7/954693

Inventors:

Daniel William - Florissant MO
Kevin P. Kepley - Dellwood MO
John A. Painter - St. Charles MO

Assignee:

American Cyanamid Company - Wayne NJ

International Classification:

G01H 1108
A61B 1739

US Classification:

36457101

Abstract:

An electronic control system for determining the resonant frequency of and driving ultrasonic transducers in a phacoemulsification probe used for ophthalmic surgery. The control system includes a voltage control led oscillator, power amplifier, power monitor, and automatic gain control circuit operating under the direction of command signals received from a microprocessor-based control console. The control system operates in a constant apparent power, direct drive mode with closed loop feedback maintaining the electrical power provided to the primary of a RLC transformer at the constant level requested by the command signals from the console. The frequency of the drive signal is held at the dominant resonant frequency of the ultrasonic transducer which is being driven by the control system. This resonant frequency is determined via a calibration procedure performed when the probe is first attached to the control system. During this procedure a constant voltage drive signal is swept through a range of frequencies and the electrical power consumed by the transducer is measured and stored at selected intervals such as 100 Hertz increments.