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:
Jul. 06, 1993
Filed:
Jan. 17, 1992
Scott W Newell, Ipswich, MA (US);
Siemens Medical Electronics, Inc., Danvers, MA (US);
Abstract
An automatic blood pressure gauge uses two pulse width modulated solenoid valve to achieve a substantially linear deflation curve. The solenoid valves are controlled by a valve switching signal that has a fixed fundamental frequency. The gauge samples and digitizes the cuff pressure signal. To eliminate artifacts related to the valve switching signal, a microprocessor in the gauge filters the sampled data pressure signal using a third-order Chebychev 2 filter having a zero at the frequency of the valve switching signal. A single timing source used for controlling the microprocessor is also used for developing both the valve switching signal and the sampled data pressure signal, in order to achieve high attenuation of the valve switching signal components in the pressure signal via the Chebychev filter. In addition, the analog to digital converter which develops the digital samples is a sigma-delta type converter which has a Nyquist frequency greater than the frequency of the valve switching signal and which includes a low pass filter that further attenuates the switching signal artifacts relative to the patient's blood pressure pulse signal. Additionally, one of the solenoid valves is used when relatively low flow rates are desired from a relatively highly pressurized cuff while the other valve is used when relatively high flow rates are desired from a cuff having a relatively low fluid pressure.