Liquid velocity measuring system
US4122713A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 19, 1977 |
| Grant date | Oct 31, 1978 |
| Priority date | — |
| Expiry date | May 19, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N2291/02836
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A liquid velocity measuring system is described utilizing ultrasonic waves to measure the velocity of a liquid and in particular, the velocity of blood as directed through a conduit external of the patient's body. The liquid velocity measuring system comprises an ultrasonic soundwave transmitting transducer energized by a continuous wave generator, preferably at a frequency of 3.13 MHz. The transmitting transducer is disposed with respect to the conduit such that the transmitted ultrasonic waves are backscattered or reflected from ultrasonic reflection centers in the blood. This signal is received and detected by a second ultrasonic transducer. The reflected ultrasonic wave is frequency-shifted dependent upon the velocity of the liquid directed through the conduit and is detected by the second transducer to be amplified and demodulated subsequently, before being applied to a microbubble detection circuit in accordance with the teachings of this invention. In particular, the microbubble detection circuit rectifies and filters the backscattered signal before applying it to a comparator circuit. In the presence of microbubbles within the liquid, the reflected ultrasonic wave will incr…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.