| 摘要 |
<p>The device determines cardiovascular values by photo transparency measurements of variations in section of peripheral arteries caused by systolic cardiac waves. The efficiency of blood flow at this level is thus found. The appts. has a photoelectric pickup (5) in the form of a clamp having two jaws (6,7) maintained in pressure one against the other by a spring (8) associated with manoeuvring lugs (9). The end of a finger (10) is placed between the jaws and against a block (12). One jaw (6) contains an IR emitting diode (13), while the other jaw, forming the receiver, has an optical filter (14) and IR phototransistors (15). The pickup is connected to an analysis system which has a pulse generator to supply the emitter and a filter whose resonance corresponds to the generator frequency, to eliminate signals other than those from the receiver. An automatic gain control amplifier compensates for signal amplitude variations due to finger thickness variations. A fast amplitude variation detection system produces a signal proportional to absorption variations created by arterial pulsations, and an electronic analysis device counts the pulses, controls their amplitude and gives a visual display.</p> |
