A portable, body-worn pulsemeter which displays the wearer's pulse rate by processing signals corresponding to the pulse beat of the wearer. This device has a piezo-electric transducer adapted to produce an output signal responsive to the force produced by the wearer's pulsebeat. The output signal operates...http://www.google.de/patents/US4409983?utm_source=gb-gplus-sharePatent US4409983 - Pulse measuring device
