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Medical sensor with amplitude independent output

  • US 5,560,355 A
  • Filed: 12/17/1993
  • Issued: 10/01/1996
  • Est. Priority Date: 12/17/1993
  • Status: Expired due to Fees
First Claim
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1. A pulse oximeter system comprising:

  • (a) a sensor for attachment to a patient includinga first light emitter for emitting light of a first wavelength,a second light emitter for emitting light of a second wavelength,a light to frequency converter integrated on a single semiconductor chip, said light to frequency converter including a photodetector and a current to frequency converter, and providing a frequency output signal,an automatic gain control circuit for separately adjusting the gain of said frequency output signal for said first and second wavelengths,a transmitter for transmitting said frequency output signal; and

    (b) a pulse oximeter monitor includinga receiver input for receiving said transmitted frequency output signal,a bus connected directly to said receiver input to receive said frequency output signal as a digital signal without any analog to digital conversion,a microprocessor, coupled to said bus, for analyzing said frequency output signal as a digital signal to determine a corresponding amplitude value represented by said frequency output signal, said microprocessor being programmed to measure oxygen saturation.

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