American Cyanamid Company

Daniel L Williams, Jr

Paul George Conley

Peter Francis Appelbaum

John A Painter

Kevin P Kepley

An aspiration control system includes a proportional control valve and a motor, for driving a 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. A pressure transducer samples the vacuum output and produces a signal which is fed to the system controller. The signal is compared with an input command, and the motor speed and valve orifice size are coordinated to control the vacuum level.

Aspiration control system

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. The resonant frequency is also determined in part by looking for the frequency at which maximum power is consumed by the probe. The stored data is also subjected to other tests to check that the peak is indeed a resonant frequency and that the probe has selected output power characteristics about this resonant frequency, thus helping to ensure that the probe is capable of operating satisfactorily when driven by the control system.

Control system for calibrating and driving ultrasonic transducer

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.

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Florissant, MO, United States of America

Daniel L Williams, Jr