GB1159127A - Improvements in or relating to Pulsometers and Arrangements Incorporating Same - Google Patents

Abstract

1,159,127. Pulsometer pick-ups. E. CHAGOURY. 6 Oct., 1966 [8 Oct., 1965], No. 44770/66. Heading H4J. A pulsometer pick-up comprises a housing M (Fig. 3), in which are mounted two spaced flexible diaphragms c, k, with a vibration transmitting fluid l therebetween, and a variable capacitor arrangement having at least one movable plate d 2 , d 2 (Fig. 5) for varying the capacitance. A rod t or other means connects one of the diaphragms c to at least one movable plate d 1 , d 2 . The plates d 1 , d 2 are preferably rings formed by metallization on the rod t. They co-operate with rings e 1 , e 2 , f (Fig. 4) acting as fixed capacitor plates formed on the interior of a casing n. The capacitor plates d 1 , d 2 , e 1 , e 2 , f are connected as a bridge network. In use the diaphragm k is placed in contact with the vibration source (e.g. the body adjacent the heart) and vibrations are transmitted to the upper diaphragm c and thus to the bridge network. The relative size of the diaphragms c and k provides amplification. The liquid I may be silicone oil, an aqueous salt solution or ethylene glycol. Local circuit.-Equilibrium of the bridge b (Fig. 1), is modified to the rhythm of pulsations at frequency f 1 . This frequency f 1 is superimposed on a carrier f 0 produced by an oscillator a. The resultant signal is amplified (g), demodulated (h) and the demodulated signal is amplified (i) for use in a visual observation or recording device or is transformed into an acoustic, oscillographic or oscilloscopic signal. Alternative capacitor arrangement.-Two movable capacitor plates q 1 , q 2 (Fig. 6) are mounted on a common operating rod t secured to a diaphragm c. The fixed capacitor plates are in the form of discs p 1 , p 2 and p 3 , apertured for passage of the rod t 1 .