EP0316073A2
Expired / Lapsed
EP
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Oximeter apparatus
Assignee: LAWRENCE MEDICAL SYSTEMS
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Filing: 1988-10-13
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Granted: —
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Expires: 2008-10-13
Abstract
Abstract An oximeter apparatus especially adapted to reflectance oximetry includes a sensor having a red LED 11, an infrared LED 11, 10 and a photosensor 12 resiliently mounted in a carrier 15 to provide constant linear pressure characteristics. The LED's 11, 10 and photodetector 12 are fixed to a flexible circuit board. The d.c. components of the reflectance signals are fed back to control the brightness of the LED's 11, 10. The a.c. components of the signals from the photodetector 12 are rejected in the determination of oxygen saturation when the red and infrared a.c. components differ by more than a determined amount. The difference between the maximum and minimum values of each pulse is employed in the determination of oxygen saturation, with two measurements being taken for each pulse.
Inventors
- 👤 Don Gorney
- 👤 Steve Taylor
- 👤 Dale Nelson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-25 00:20
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/145; A61B5/1455; A61B5/14551; A61B5/14552
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
135 words
A oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources 11, 10 respectively at different instants and signal processing means coupled to said photodetector and synchronized with said energizing menas 40, 41 for determining oxygen saturation in said tissue, characterized in that said signal processing means comprises means 35 for generating first and second feedback signals corresponding to DC component of Red and IR light respectively received by said photosensor 12, and means 34 applying said first and second signals to said first and second control circuits 40, 41 comprising means employing said feedback signals as negative feedback signals in the energization of said sorces.
Claim 2
Dependent Claim
135 words
A oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources 11, 10 respectively at different instants and signal processing means coupled to said photodetector and synchronized with said energizing menas 40, 41 for determining oxygen saturation in said tissue, characterized in that said signal processing means comprises means 35 for generating first and second feedback signals corresponding to DC component of Red and IR light respectively received by said photosensor 12, and means 34 applying said first and second signals to said first and second control circuits 40, 41 comprising means employing said feedback signals as negative feedback signals in the energization of said sorces.
Claim 3
Dependent Claim
33 words
An oximeter according to claim 1 to characterised in that said control circuits 40, 41 comprise time constant circuits, and means for varying the time constant of application of said feedback signals thereto.
Claim 4
Dependent Claim
44 words
An oximeter according to claim 1 characterised in that a source of a brightness control voltage, said control circuits 40, 41 further comprising means responsive to said brightness control voltage for controlling the energization of said red and infrared sources as a function thereof.
Claim 5
Dependent Claim
161 words
A oximeter comprisng a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources 11, 10 respectively at different instants and singal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for determining oxygen saturation in said tissue, characterised in that said signal processing means comprises filter means 50, 51 for selecting the a.c. component from the signal output of said photodetector 12, and a controllable gain circuit 52, 53 for controlling the gain of the output of said signal processing means, said gain circuit 52, 53 comprising a plurality of amplifiers 56,57 of different gain connected to simultaneously receive the same signal output for said filter mans 50, 51 an output circuit, and means 54, 55 for selectively connecting individual ones of said amplifiers to said output circuit.
Claim 6
Dependent Claim
161 words
A oximeter comprisng a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources 11, 10 respectively at different instants and singal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for determining oxygen saturation in said tissue, characterised in that said signal processing means comprises filter means 50, 51 for selecting the a.c. component from the signal output of said photodetector 12, and a controllable gain circuit 52, 53 for controlling the gain of the output of said signal processing means, said gain circuit 52, 53 comprising a plurality of amplifiers 56,57 of different gain connected to simultaneously receive the same signal output for said filter mans 50, 51 an output circuit, and means 54, 55 for selectively connecting individual ones of said amplifiers to said output circuit.
Claim 7
Dependent Claim
48 words
An oximeter according to claim 5 characterised in that plurality of amplifiers 56, 57 comprise at least four amplifiers connected to receive the a.c. component of signals corresponding to infrared light and at least four amplifiers connected to recieve the a.c. component of signals corresponding to red light.
Claim 8
Dependent Claim
24 words
An oximeter according to claim 5 characterised in that amplifiers of each group of amplifiers have relative gains of 1, 1.25, 2 and 4.
Claim 9
Dependent Claim
118 words
An oximeter a red light source 11, and infrared light source 10, a photodetector 12 for receiving light from said cources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources respectively at different instants, and signal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for producing first and second output signals corresponding respectively to reflected red light and reflected infrared light for determining oxygen saturation in said tissue, said signal processing means further comprising means for detecting relative variation in said first and second signals, and means for inhibiting the determination of oxygen saturation when said relative variation exceeds a determined level.
Claim 10
Dependent Claim
118 words
An oximeter a red light source 11, and infrared light source 10, a photodetector 12 for receiving light from said cources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources respectively at different instants, and signal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for producing first and second output signals corresponding respectively to reflected red light and reflected infrared light for determining oxygen saturation in said tissue, said signal processing means further comprising means for detecting relative variation in said first and second signals, and means for inhibiting the determination of oxygen saturation when said relative variation exceeds a determined level.
Claim 11
Dependent Claim
133 words
An oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources respectively at different instants, whereby said photodetector 12 receives pulses of reflected infrared light corresponding separately to reflected red light and reflected light, and signal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for determining oxygen saturation in said tissue, said processing circuits comprise means for sampling the maximum and minimum values of each pulse received from said photodetector, and means for producing output signal responsive to the levels of the last maxium and last minimum values of pulses corresponding to reflected red and infrared light.
Claim 12
Dependent Claim
133 words
An oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources respectively at different instants, whereby said photodetector 12 receives pulses of reflected infrared light corresponding separately to reflected red light and reflected light, and signal processing means coupled to said photodetector 12 and synchronized with said energizing means 40, 41 for determining oxygen saturation in said tissue, said processing circuits comprise means for sampling the maximum and minimum values of each pulse received from said photodetector, and means for producing output signal responsive to the levels of the last maxium and last minimum values of pulses corresponding to reflected red and infrared light.
Claim 13
Dependent Claim
26 words
An oximeter according to claim 8 characterized in that said processing circuits comprise means for determining between the maximum an munimum levels sensed for each pulse.
Claim 14
Dependent Claim
114 words
An oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources repsectively at different instants, signal processing means coupled to said photodetector 12, and synchronized with said energizing means for determining oxygen saturation in said tissue, and means for matching the d.c. levels of the output signals from said photodetector 12 corresponding to red and infrared light, said matching means comprising means of adjusting the brightness of at leas one of said sources as a function of the corresponding d.c. level output from said photodetector.
Claim 15
Dependent Claim
114 words
An oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, first and second control circuits 40, 41 for energizing said red and infrared light sources repsectively at different instants, signal processing means coupled to said photodetector 12, and synchronized with said energizing means for determining oxygen saturation in said tissue, and means for matching the d.c. levels of the output signals from said photodetector 12 corresponding to red and infrared light, said matching means comprising means of adjusting the brightness of at leas one of said sources as a function of the corresponding d.c. level output from said photodetector.
Claim 16
Dependent Claim
62 words
An oximeter according to claim 10 characterised in that said matching means comprises a brightness control circuit 30 for said sources, a feedback circuit 34 connected to feed back the d.c. components of the outputs of said photodetector 12 to said control circuit 40, 41 said control circuit 40, 41 further comprising means for controlling the relative brightness of said light sources.
Claim 17
Dependent Claim
109 words
An oximeter comprising a sensor having a red light source 11, an infrared light source 10, and a photodetector 12 for receiving light from said sources reflected from tissue, the improvement wherein said sensor comprises a housing 18, 19 having an aperture, a sensor carrier 15, said light sources 11, 10 and photodetector 12 being mounted to have active light emitting and light receiving surfaces respectively at one side of said carrier 15, an electrical connection 16 arrangement for said sources and photodetector within said housing 18, 19 and resilient means for mounting said carrier 15 in said aperture, whereby said carrier 15 floats with respect to said housing
Claim 18
Dependent Claim
109 words
An oximeter comprising a sensor having a red light source 11, an infrared light source 10, and a photodetector 12 for receiving light from said sources reflected from tissue, the improvement wherein said sensor comprises a housing 18, 19 having an aperture, a sensor carrier 15, said light sources 11, 10 and photodetector 12 being mounted to have active light emitting and light receiving surfaces respectively at one side of said carrier 15, an electrical connection 16 arrangement for said sources and photodetector within said housing 18, 19 and resilient means for mounting said carrier 15 in said aperture, whereby said carrier 15 floats with respect to said housing
Claim 19
Dependent Claim
34 words
An oximeter according to claim 12 characterised in that said resilient means comprises means for biasing said carrier 15 to have a uniform linear preasure for displacements of said carrier through a determined range.
Claim 20
Dependent Claim
22 words
An oximeter according to claim 12 characherised in that said resilient means comprises a membrane sealingly holding said darrier in said aperture.
Claim 21
Dependent Claim
52 words
An oximeter according to claim 12 characterised in that an interconnection cable 13 extending into said housing, said electrical connection 16 arrangement comprising a flexible connection board having electrical leads thereon, said sources 10, 11 and photosensor 12 bing mounted on said flexible board, said leads being connected to said cable 13.
Claim 22
Dependent Claim
24 words
An oximeter according to claim 15 characterised in that said flexible board is mounted to resiliently yield to pressure applied to said carrier 13.
Claim 23
Dependent Claim
13 words
An oximeter according to claim 16 characterised in that flexible board is U-shaped.
Claim 24
Dependent Claim
102 words
An oximeter comprising a sensor having a red light source 11, an infrared light source 10, and a photodetector 12 for receiving light from said sources 11,10 reflected from tissue, the improvement wherein said sensor comprises a housing 18, 19 comprising a sensor carrier 15, said light sources 11, 10 and photodetector 12 being mounted to have active light emitting and light receiving surfaces respectively at one side of said carrier 15 externally of said housing 18, 19, and light barrier means coating said sources 11, 10 and photodetector 12 on substantially all surfaces except said active light emitting and receiving surfaces.
Claim 25
Dependent Claim
102 words
An oximeter comprising a sensor having a red light source 11, an infrared light source 10, and a photodetector 12 for receiving light from said sources 11,10 reflected from tissue, the improvement wherein said sensor comprises a housing 18, 19 comprising a sensor carrier 15, said light sources 11, 10 and photodetector 12 being mounted to have active light emitting and light receiving surfaces respectively at one side of said carrier 15 externally of said housing 18, 19, and light barrier means coating said sources 11, 10 and photodetector 12 on substantially all surfaces except said active light emitting and receiving surfaces.
Claim 26
Dependent Claim
16 words
An oximeter according to claim 18 characterised in that said light barrier means comprises silver paint.
Claim 27
Dependent Claim
96 words
A sensor arrangement for a reflectance oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, and a housing 18 19 having a sensor carried 13, said light sources 11,10 and photodetector 12 being mounted in said carrier 15 to have active light emitting and light receiving surfaces respectively externally of said houding 18,19 said sources 11, 10 and photosensor 12 being positioned along a straight line with the infrared source 10 being positioned between said red source 11 and photosensor 12.
Claim 28
Dependent Claim
96 words
A sensor arrangement for a reflectance oximeter comprising a red light source 11, an infrared light source 10, a photodetector 12 for receiving light from said sources reflected from tissue, and a housing 18 19 having a sensor carried 13, said light sources 11,10 and photodetector 12 being mounted in said carrier 15 to have active light emitting and light receiving surfaces respectively externally of said houding 18,19 said sources 11, 10 and photosensor 12 being positioned along a straight line with the infrared source 10 being positioned between said red source 11 and photosensor 12.
Claim 29
Dependent Claim
27 words
A sensor arrangement according to claim 20 characterised in that the axis of said infrared sensor 10 is substantially 0.128 inches from the axis of said photosensor.
Claim 30
Dependent Claim
29 words
A sensor arrangement according to claim 20 characterised in that the axis of said red sensor 11 is substantially 0.085 inches from the axis of said infrared sensor 10.
Claim 31
Independent Claim
80 words
A method for reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said sources 11, 10 is sensed to produce red and infrored reflectance signals respectively, said method characterised in that separating the a.c. and d.c. components of said reflectance signals, determining oxygen saturation from said a.c. signals, and rejecting said signals for oxygen saturation determination when the difference between the red and infrared a.c. reflectance signals exceeds a given amount.
Claim 32
Independent Claim
80 words
A method for reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said sources 11, 10 is sensed to produce red and infrored reflectance signals respectively, said method characterised in that separating the a.c. and d.c. components of said reflectance signals, determining oxygen saturation from said a.c. signals, and rejecting said signals for oxygen saturation determination when the difference between the red and infrared a.c. reflectance signals exceeds a given amount.
Claim 33
Independent Claim
75 words
A method of reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said sources 11, 10 is sensed tp produce red and infrared reflectance signals respectively, said method characterising in that separating the a.c. and d.c. components of said reflectance signals, determining oxygen saturation from said a.c. signals, and adjusting the brightness of light from said sources to maintain said a.c. signals within a predetermined range.
Claim 34
Independent Claim
75 words
A method of reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said sources 11, 10 is sensed tp produce red and infrared reflectance signals respectively, said method characterising in that separating the a.c. and d.c. components of said reflectance signals, determining oxygen saturation from said a.c. signals, and adjusting the brightness of light from said sources to maintain said a.c. signals within a predetermined range.
Claim 35
Independent Claim
81 words
A method of reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said source 11,10 is sensed to produce red and infrored reflectance signals respectively, said method characteristic in that separating the a.c. and d.c. components of said reflectance signals, determining the difference between the maximum and minimum values of each pulse of a.c. component, and determining oxygen saturation from said difference by comparison of said difference with a look up table.
Claim 36
Independent Claim
81 words
A method of reflectance oximetry wherein red and infrared light sources 11, 10 are separately sequentially energized, and reflected light from said source 11,10 is sensed to produce red and infrored reflectance signals respectively, said method characteristic in that separating the a.c. and d.c. components of said reflectance signals, determining the difference between the maximum and minimum values of each pulse of a.c. component, and determining oxygen saturation from said difference by comparison of said difference with a look up table.
Claim 37
Dependent Claim
25 words
A method according to claim 25 characterised in that said step of determining said difference comprises determining said difference twice for each of said pulse.
References Cited (Backward Citations)
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