Pulse oximeter with sigma-delta converter
First Claim
Patent Images
1. An oximeter apparatus comprising:
- sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation;
converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and
signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject,said converter means includinga first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof,a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, anda digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals,said digital filter processor including programming for digitally filtering said sample signals in order to produce said first and second digital signals, and for controlling the input sampling rate from said modulators and controlling the filter corner frequency and output update rate of said first and second digital signals.
1 Assignment
0 Petitions
Accused Products
Abstract
A preferred oximeter detects the transillumination by red and infrared light of a portion of an in vivo subject and produces analog signals representative thereof on two channels. Sigma-delta modulators sample the analog signals on each channel. A digital filter processor digitally filters the sample signals from both modulators to produce respective digital signals with multi-bit resolution.
242 Citations
55 Claims
-
1. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said digital filter processor including programming for digitally filtering said sample signals in order to produce said first and second digital signals, and for controlling the input sampling rate from said modulators and controlling the filter corner frequency and output update rate of said first and second digital signals. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
-
-
25. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said converter means including gain adjusting means for adjusting the gains of said modulators in response to variations in said first and second analog signals, said adjusting means including programming within said digital filter processor, said converter means including signal amplifiers for amplifying said first and second analog signals, said gain adjusting means including switching means for selectively switching resistance in connection with said amplifiers for adjusting the gains thereof. - View Dependent Claims (26)
-
-
27. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said converter means including gain adjusting means for adjusting the gains of said modulators in response to variations in said first and second analog signals, said first and second analog signals including respective first and second current signals, said converter means including means connecting said first and second current signals directly to amplifiers of said first and second sigma-delta modulators respectively without current to voltage conversion of said current signals. - View Dependent Claims (28, 29, 30, 31)
-
-
32. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said converter means including gain adjusting means for adjusting the gains of said modulators in response to variations in said first and second analog signals, said modulators including respective ground sensing amplifiers as first integrators and second integrators biased to a reference voltage between ground and supply voltage, said supply voltage being no greater than about +5 V.
-
-
33. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining a blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said oximeter further including first and second light emitting diodes for producing said respective first and second wavelengths, a drive circuit for selectively activating said diodes, and deactivating means for determining the occurrence of a short circuit connected to said diodes and responsive thereto for deactivating said diodes.
-
-
34. An oximeter apparatus comprising:
-
sensor means for producing first and second analog signals respectively representative of the transillumination of a body portion of an in vivo subject by respective first and second wavelengths of radiation; converter means for receiving and converting said first and second analog signals into respective first and second digital signals; and signal processing means for receiving and processing said first and second digital signals for determining blood oxygen saturation of the subject, said converter means including a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and a digital filter processor having means for receiving both of said first and second sample signals and responsive thereto for digitally filtering said sample signals in order to produce said respective first and second digital signals, said sensor means including a detachable probe configured for disposition onto a surface of a subject, said probe having first and second light emitting diodes for producing said first and second wavelengths of light respectively in the red and infrared bands and having a photo detector for producing said first and second analog signals, a drive circuit having means for selectively activating said diodes, and encoding means for providing analog encoded signals indicative of the wavelengths of light emitted by said diodes and including an impedance element included as part of said probe and operable for producing a voltage as said analog encoded signals, said apparatus further including a third sigma-delta modulator having means for receiving said analog encoded signals and for producing a third sample signal representative thereof, said digital signal filter processor having means for receiving said third sample signal and responsive thereto for digitally filtering said third sample signal for producing a digital encoded signal, said signal processing means including means for receiving and processing said digital encoded signal for use in calibrating said apparatus.
-
-
35. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a) producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b) converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the steps of using programming in said digital filter processor for digitally filtering said sample signals in order to produce said first and second digital signals, and for controlling the input sampling rate from said modulators and controlling the filter corner frequency and output update rate of said first and second digital signals. - View Dependent Claims (36, 37, 38, 39, 40, 41, 42, 43, 44, 45)
-
-
46. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a) producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b) converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the step of adjusting the gains of said modulators in response to variations in said first and second analog signals, step (b) further including the step of using amplifiers for amplifying said first and second analog signals and selectively adjusting the gain of said amplifiers, said method further including the step of selectively switching resistance in connection with said amplifiers for adjusting the gains thereof. - View Dependent Claims (47)
-
-
48. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a) producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b) converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the step of adjusting the gains of said modulators in response to variations in said first and second analog signals, step (b) further including the step of providing feedback from said digital filter processor to said modulators and adjusting said feedback in order to selectively adjust the gains of said modulators. - View Dependent Claims (49)
-
-
50. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a) producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b) converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the step of adjusting the gains of said modulators in response to variations in said first and second analog signals, said first and second analog signals including respective first and second current signals, step (b) further including the step of connecting said first and second current signals to amplifiers of said first and second sigma-delta modulators respectively without current to voltage conversion of said current signals. - View Dependent Claims (51, 52)
-
-
53. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the step of adjusting the gains of said modulators in response to variations in said first and second analog signals, step (b) further including the step of providing feedback signals in the nature of square waves having respective pulse widths as feedback from said digital filter processor to said modulators, and selectively adjusting said pulse widths in order to selectively adjust the gains of said modulators. - View Dependent Claims (54)
-
-
55. A method of determining the blood oxygen saturation of an in vivo subject comprising the steps of:
-
(a) producing first and second analog signals respectively representative of the transillumination of a body portion of the subject by respective first and second wavelengths of light; (b) converting said first and second analog signals into respective first and second digital signals; and (c) processing said first and second digital signals for determining the blood oxygen saturation of the subject, step (b) further including the steps of using a first sigma-delta modulator for receiving said first analog signal and for producing a first sample signal representative thereof, using a second sigma-delta modulator for receiving said second analog signal and for producing a second sample signal representative thereof, and providing both of said first and second sample signals to a digital filter processor and therein digitally filtering said sample signals in order to produce said respective first and second digital signals, step (b) further including the step of adjusting the gains of said modulators in response to variations in said first and second analog signals, step (b) further including the steps of using first and second light emitting diodes for producing said respective first and second wavelengths, using a drive circuit for selectively activating said diodes, and determining the occurrence of a short circuit connected to said diodes and responsive thereto for deactivating said diodes.
-
Specification