Capacitive blood pressure meter with frequency transducer - has capacitor with parallel plates connected to moving parts

摘要

A pressure measurement device, esp for blood, has a pressure sensor in which the position of a first part undergoes a reversible position change w.r.t. a second part during a pressure change. It enables larger adjustments of the device or its evaluation section without sacrificing accuracy. A pressure to frequency transducer contains an RC oscillator with a triggered threshold controlled charge-discharge circuit. The RC element contains a measurement air capacitor with plane parallel electrodes (33, 34). The electrodes (33, 34) are coupled to respective moving parts (27, 28) so that when the parts move w.r.t each other the electrodes move w.r.t each other along their common surface normal direction. The capacitance variation causes a frequency variation used to control an indicator.