Instrumentation for monitoring blood circulation
Discrete frequency colorimeter
Constant current-pulse led drive circuit
Apparatus for measuring electrical or magnetic fields by absorption spectrum change
Blood constituent measuring device and method
Calibrated optical oximeter probe
ApplicationNo. 07/106747 filed on 10/08/1987
US Classes:356/41, Oximeters600/323Oxygen saturation, e.g., oximeter
ExaminersPrimary: McGraw, Vincent P.
Attorney, Agent or Firm
International ClassesA61B 5/00 (20060101)
A61B 5/024 (20060101)
AbstractA pulse oximeter is provided including two light emitting diodes. Each LED is energized by a unique modulation signal. Light produced by the LEDs passes through the tissue of a subject and is detected by a photodiode. The photodiode signal is separated by tuned circuits resonant at the two modulation signal frequencies and physiological information signals are recovered from the separated signals by amplitude demodulation. The inventive arrangement provides identification of back-to-back coupled LEDs and narrow band filtering for good noise immunity.