AIR BUBBLE DETECTOR
First Claim
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1. A bubble detection system comprising:
- a fluid path;
a piezoelectric transmitter and a piezoelectric receiver disposed adjacent the fluid path for detecting bubbles therein;
control circuitry for operating the transmitter and receiver comprising;
a circuit for generating a wide range frequency sweep in the transmitter;
a circuit for analyzing the receiver output and determining a resonant frequency for the piezoelectric transmitter and receiver and fluid path;
memory for storing the resonant frequency; and
a circuit for operating the transmitter at a reduced frequency range at the resonant frequency in order to thereby detect bubbles in the fluid path.
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Abstract
Air bubbles may be characterized by an air bubble detector by choosing an optimum set of frequencies and then comparing a return signal from a sensor receiving those frequencies against an internal reference. The number of pulses that exceed the internal reference represents a width and may be counted. The width, as counted, may be correlated to bubble characteristics including volume.
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Citations
18 Claims
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1. A bubble detection system comprising:
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a fluid path; a piezoelectric transmitter and a piezoelectric receiver disposed adjacent the fluid path for detecting bubbles therein; control circuitry for operating the transmitter and receiver comprising; a circuit for generating a wide range frequency sweep in the transmitter; a circuit for analyzing the receiver output and determining a resonant frequency for the piezoelectric transmitter and receiver and fluid path; memory for storing the resonant frequency; and a circuit for operating the transmitter at a reduced frequency range at the resonant frequency in order to thereby detect bubbles in the fluid path. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A bubble detection system comprising:
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a fluid path; a piezoelectric sensor coupled with the fluid path and configured for detection of bubbles in the fluid path; an internal receiver signal reference; and a comparator circuit configured to detect bubbles and determine bubble size within the fluid path by determining the length of time an output signal of the sensor exceeds the internal reference. - View Dependent Claims (8, 9)
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10. A method of detecting bubbles comprising:
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sending an ultrasonic signal through a fluid path by an ultrasonic transmitter; reporting a detected signal by an ultrasonic receiver; selecting an internal receiver signal reference; determining the amount of time the detected signal exceeds the internal reference; and calculating bubble size based on the amount of time the detected signal exceeds the internal reference.
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11. A method of detecting bubbles in a fluid path comprising:
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transmitting a broad frequency range of ultrasonic signals through a fluid path; receiving the broad range ultrasonic signals after transmission through the fluid path; determining a sympathetic frequency for the fluid path based on the strength of the received broad range signals; storing the sympathetic frequency; transmitting a narrow frequency range of ultrasonic signals surrounding the sympathetic frequency through the fluid path to detect bubbles; and receiving the narrow range ultrasonic signals to detect bubbles. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18)
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Specification