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:
Jan. 15, 1991
Filed:
Nov. 02, 1989
Andreas Schulenberg, Schonaich, DE;
Martin Schraag, Sindelfingen, DE;
Hewlett-Packard Company, Palo Alto, CA (US);
Abstract
A circuit for heartbeat detection derives the heartbeat frquency from ultrasonic signals reflected from the heart and frequency-shifted due to the Doppler effect. The circuit allows for the automatic determination of the distance between the heart and an ultrasonic transducer located on the body of the patient, so that the evaluation of the reflected ultrasonic signals can be limited to a small body range and spurious signals from other ranges can be suppressed. The circuit comprises at least two channels which are enabled by a transmitting/receiving control circuit during receiving intervals for receiving and further processing the reflected ultrasonic signals. The receiving intervals of the different channels are time shifted toward one another so that the respectively received ultrasonic signals originate from different depth ranges within the body. A comparison circuit compares the strengths of the signals corresponding to the heartbeat during each heartbeat period in the individual channels, and thus derives a gradient which indicates the direction in which the receiving intervals or transmit windows are to be shifted during the subsequent heartbeat period in order to localize the heart.