The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 07, 1989
Filed:
Sep. 28, 1987
Hitachi Medical Corp., Tokyo, JP;
Abstract
An ultrasonic Doppler blood flow meter comprises a transmit-receive transducer transmitting ultrasonic wave toward and into a living body and receiving an echo signal, quadrature detectors detecting a real (R) component and an imaginary (I) component of the receiving echo signal respectively, A/D converters converting analog output signals of the quadrature detectors into digital signals respectively, a converter subjecting the R and I components to quadrature transformation to generate output signals representing the absolute value and phase angle (.theta.) respectively of the received echo signal, and a signal processing circuit calculating the mean value of the differences (.DELTA..theta..sub.i =.theta..sub.i -.theta..sub.i-1) between the phase angles (.theta..sub.i) and their preceding ones (.theta..sub.i-1) detected when the ultrasonic wave is transmitted and the echo signal is received a predetermined number of times. In the signal processing circuit, the phase angle differences (.DELTA..theta.) are each resolved into an X-axis component (cos .DELTA..theta.) and a Y-axis component (sin.DELTA..theta.), and, after calculation of the mean values X and Y of n consecutive X-axis and Y-axis components respectively, the mean Doppler shift phase angle .DELTA..theta.=tan.sup.-1 (Y/X) is calculated on the basis of the calculated mean values X and Y.