Pulse oximeter sensor control system
First Claim
1. An oximeter system, including first and second controllable light sources and optical receiver means for producing an electrical signal in response to the reception of light from said sources comprising:
- means for producing a first frequency signal modulated by a second frequency, and a third frequency signal modulated by said second frequency;
means for energizing said first light source in response to said first modulated signal and for energizing said second light source in response to said third modulated signal;
means responsive to said electrical signal for producing a fourth signal including said first frequency signal components and for producing a fifth signal including said third frequency signal components; and
means for demodulating said fourth and fifth signals.
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Accused Products
Abstract
A 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.
294 Citations
9 Claims
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1. An oximeter system, including first and second controllable light sources and optical receiver means for producing an electrical signal in response to the reception of light from said sources comprising:
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means for producing a first frequency signal modulated by a second frequency, and a third frequency signal modulated by said second frequency; means for energizing said first light source in response to said first modulated signal and for energizing said second light source in response to said third modulated signal; means responsive to said electrical signal for producing a fourth signal including said first frequency signal components and for producing a fifth signal including said third frequency signal components; and means for demodulating said fourth and fifth signals. - View Dependent Claims (2, 3, 4)
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5. An oximeter system comprising:
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means for producing first and second carrier signals; means for amplitude modulating said carrier signals in a time interleaved manner; first and second controllable light sources which are respectively controlled by said modulated carrier signals; means responsive to light from said source which has been subjected to a physiological phenomenon for producing an electrical signal containing said carrier signals and physiological information signals; means for separating said carrier signals and physiological information signals from undesired signal components; and means for demodulating said carrier signals and physiological information signals to recover said physiological information.
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6. An oximeter system, including at least one controllable light source and optical receiver means for producing an electrical signal in response to the reception of light from said source comprising:
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a source of frequency reference signals; means for producing a modulated waveform; means for coupling said reference signals to said modulated waveform producing means in a direct-current isolated manner; means for energizing said light source in response to said modulated waveform; demodulator means for demodulating components of said electrical signal containing a frequency of said modulated waveform; and means for coupling said electrical signal to said demodulator means in a direct-current isolated manner. - View Dependent Claims (7, 8, 9)
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Specification