WO2006080856A1 - Power reduction circuit for photo-optical physiological monitoring equipment - Google Patents

Power reduction circuit for photo-optical physiological monitoring equipment Download PDF

Info

Publication number
WO2006080856A1
WO2006080856A1 PCT/NZ2005/000028 NZ2005000028W WO2006080856A1 WO 2006080856 A1 WO2006080856 A1 WO 2006080856A1 NZ 2005000028 W NZ2005000028 W NZ 2005000028W WO 2006080856 A1 WO2006080856 A1 WO 2006080856A1
Authority
WO
WIPO (PCT)
Prior art keywords
photo
monitoring equipment
light source
physiological monitoring
output signal
Prior art date
Application number
PCT/NZ2005/000028
Other languages
French (fr)
Inventor
Christopher Bryn Sparks
Geoffrey Kennedy
Brett Robert Carpenter
Original Assignee
Senscio Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Senscio Limited filed Critical Senscio Limited
Publication of WO2006080856A1 publication Critical patent/WO2006080856A1/en

Links

Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/02—Operational features
    • A61B2560/0204—Operational features of power management
    • A61B2560/0209—Operational features of power management adapted for power saving

Definitions

  • the present invention relates to photo-optical medical monitoring equipment.
  • photo-optical medical monitoring equipment means equipment designed to receive signals from sensors incorporating light sources; said sensors being connected to or associated with a subject, to monitor one or more physiological parameters of that subject.
  • the term includes sensors, monitors, and adapters in the related field.
  • a wide range of physiological monitoring equipment is currently available, for monitoring one or more of a number of different physiological parameters. Typically these devices are used for medical monitoring. Medical monitoring equipment often has the ability to record the analysis of signals from sensors, and include an alarm system to alert medical staff of undesirable or dangerous changes in the subject's condition.
  • a sensor designed to sense the selected physiological parameter is attached to the subject and is connected to a monitor by a cable.
  • the light source components of the monitoring equipment shine through or into the target site and are transmitted or reflected in a modified form.
  • the modified transmitted or reflected light falling on a photo-detector component of the sensor causes the photo-detector to generate an electrical signal corresponding to the physiological parameter being sensed.
  • This electrical signal is transmitted directly or digitised and transmitted to the monitor by various means, including but not limited to, a conducting wire; infrared, radio- frequency, or fibre-optic connections.
  • the term 'light' as herein used includes the electromagnetic frequencies from far infra-red through visible light to extreme ultraviolet.
  • Photo-optical components require power to operate, and even relatively low-power light sources are often the major element in a sensor power budget. Therefore, the light source power consumption becomes a limiting factor in continuous operational performance life-time for photo-optical physiological monitoring devices with finite power supplies such as, but not limited to, batteries or solar cells. This limitation is particularly important in the burgeoning field of portable sensors, sensor adapters, and portable monitors.
  • Light sources are typically switched on and off rapidly for a variety of reasons including the need to utilise differing wavelength light sources, to allow ambient light sampling (a passive measurement cycle), and to conserve power. The light source on-time within an active measurement cycle is often maintained beyond the settling time of the photo-detector (i.e.
  • a further object of the invention is to reduce the on-time of the light source to, or close to, the photo-detector settling time without resorting to the use of high speed analogue to digital components or compromising the reliability and accuracy of the photo-optical physiological monitoring equipment.
  • the present invention provides a power reduction circuit for photo-optical physiological monitoring equipment, wherein said photo-optical physiological monitoring equipment is adapted to be used to measure one or more physiological properties of a subject by illuminating a portion of the subject with one or more light sources, which produces a reflected or transmitted modified light signal representative of the physiological property being measured; the modified light signal is detected by one or more photo- detectors, the or each photo-detector is adapted to produce an output signal that is representative of the modified light signal impinging on that photo-detector, characterised in that, the power reduction circuit includes an isolating switch, a capacitor and a signal buffer.
  • the power reduction circuit is arranged such that when the processing circuit requires an active measurement cycle to occur the following steps, in order, are undertaken;
  • the processing circuit reads the output signal from the buffer and processes the output signal; vii. the processing circuit closes the isolating switch;
  • one or more active measurement cycle in series or parallel, is required to measure the one or more physiological properties of the subject.
  • a first light source and a second light source are used, only the first light source or second light source is on during any single active measurement cycle.
  • the first light source and second light source are preferably of different frequencies; said frequencies being determined by the light absorption characteristics of the biological components involved in the physiological property being measured.
  • a photo-detector is optimised for use with both light sources.
  • a separate power reduction circuit is associated with each photo- detector such that both light sources and the photo-detector and the power reduction circuit form a detection circuit. Each said detection circuit produces an output signal which is processed by the processing circuit separately or in conjunction with output signals produced during other measurement cycles.
  • the or each photo-detector and the or each light source are simultaneously or independently controlled by the processing circuit at any stage during any active measurement cycle.
  • the or each light source is selected from an incandescent lamp, a fluorescent lamp, a photo chemical light source, an organic light source, a light emitting diode, a laser, a neon or other gas discharge lamp and an arc lamp. It is highly preferred that the light source is a light emitting diode.
  • the processing circuit carries out more than one processing step during the light source off-time using the output signal held in the signal buffer.
  • each pair of light sources is associated with a respective photo-detector and power reduction circuit, such that when an active measurement cycle occurs the processing circuit is adapted to access the output from each power reduction circuit in parallel.
  • the photo-optical physiological monitoring equipment is a pulse oximeter.
  • the pulse oximeter is a wireless device, either mono- or bi-directional, in this context wireless includes optical and electromagnetic transmission.
  • the processing circuit includes an analogue to digital converter, and transmits the digital signal to an external receiver at regular intervals.
  • Figure 1 is a graph showing the typical on time of a light source for a photo-optical physiological monitoring device as compared to the on time for a device incorporating the invention; the light source in this case is a light emitting diode (LED).
  • LED light emitting diode
  • Figure 1a is a graph showing the output signal held by the signal buffer over an active measurement cycle and the light source on-time for both the invention and without the invention.
  • Figure 2 is a block diagram of the invention.
  • Figure 3 is a flowchart showing a method of using the invention.
  • Figure 4 is a block diagram of a second embodiment of the invention which includes two light sources.
  • Figure 5 is a block diagram of a further embodiment of the invention which includes additional signal processing of the output signal.
  • Figure 6 is a block diagram of a further embodiment of the invention which includes an estimation circuit.
  • the invention includes a photo-detector (1), a light source (2), an isolating switch (3) and a processing circuit (4).
  • the light source (2) is adapted to illuminate a portion of a subject (5) for a period of time, the light from the light source (2) interacts with the portion of the subject (5) and is modified.
  • the photo-detector (1) is adapted to respond to certain properties of this modified light and generate an output signal, the properties of the output signal being dependent upon the modified light received.
  • the photo-detector (1) is connected to the isolating switch (3), which is controlled by the processing circuit (4).
  • the isolating switch (3) is connected to a signal buffer (10) and capacitor (11); the buffer (10) is further connected to the processing circuit (4).
  • the light source (2) is connected to and controlled by the processing circuit (4).
  • the processing circuit (4) commences an active measurement cycle (20).
  • the processing circuit (4) commences a sampling step (21).
  • the sampling step (21) starts when the processing circuit (4) turns on the light source (2); this allows the photo-detector (1) to generate the output signal which passes from the photo-detector (1) through the isolating switch (3) into the capacitor (11) and signal buffer (10). Due to the physical properties of the photo-detector (1) the output signal takes a short time to settle to a stable level, (the settling time). Once this stable level has been achieved the sampling step (21) is completed and the processing circuit (4) opens the isolating switch (3) and turns the light source (2) off. The output signal is then maintained by the capacitor (11) at this stable level, and is passed to the signal buffer (10) for accessing by the processing circuit (4).
  • the processing circuit (4) reads the output signal in the signal buffer (10) as many times as necessary to complete signal processing during the active measurement cycle (20), the capacitor (11) maintains the output signal level in the signal buffer (10) at the originally measured stable level until the active measurement cycle (20) is complete.
  • the light source (2) is two or more separate light sources (2, 2a). Each of the light sources (2, 2a) has a different output frequency and is used for a separate active measurement cycle (20). Each of these active measurement cycles (20) can occur in series or, if additional isolating switches (3), capacitors (11) and signal buffers (10) are present, in parallel. One or more light source (2, 2a) may be used during any individual active measurement cycle (20) to produce the light spectra required for that measurement.
  • the invention in a further embodiment, as shown in Figure 5, includes signal conditioning circuits (30) to filter noise and other undesirable signals from the output signal.
  • the invention is combined with other power saving devices and procedures, such as, but not limited to, powering down the light source (2) driving circuitry, the isolating switch (3) and the photo-detector (1) once the isolating switch (3) is opened.
  • the power reduction circuit includes an estimation circuit (31) that predicts the stable level of the photo-detector (1) prior to the photo-detector (1) reaching that level and is adapted to feed that level to the capacitor (11) and signal buffer (10) and then instruct the processing circuit (4) to open the isolating switch (3) and turn off the light source (2) .
  • the estimation circuit (31) only operates after the light source (2) output has stabilised.

Abstract

A power reduction circuit for photo-optical physiological monitoring equipment, wherein said photo-optical physiological monitoring equipment is adapted to be used to measure one or more physiological properties of a subject by illuminating a portion of the subject with one or more light sources, which produces a reflected or transmitted modified light signal representative of the physiological property being measured; the modified light signal is detected by one or more photo-detectors, the or each photo-detector is adapted to produce an output signal that is representative of the modified light signal impinging on that photo-detector, characterised in that, the power reduction circuit includes an isolating switch, a capacitor and a signal buffer, wherein the capacitor is adapted to maintain the output signal level in the signal buffer when the isolating switch is opened during an active measurement cycle thus reducing the required light source on time to a minimum.

Description

Power Reduction Circuit for Photo-optical Physiological Monitoring Equipment
Technical Field
The present invention relates to photo-optical medical monitoring equipment. As used herein, the term "photo-optical medical monitoring equipment" means equipment designed to receive signals from sensors incorporating light sources; said sensors being connected to or associated with a subject, to monitor one or more physiological parameters of that subject. The term includes sensors, monitors, and adapters in the related field.
A wide range of physiological monitoring equipment is currently available, for monitoring one or more of a number of different physiological parameters. Typically these devices are used for medical monitoring. Medical monitoring equipment often has the ability to record the analysis of signals from sensors, and include an alarm system to alert medical staff of undesirable or dangerous changes in the subject's condition.
Background Art
In the most commonly used types of photo-optical physiological monitoring equipment, a sensor designed to sense the selected physiological parameter is attached to the subject and is connected to a monitor by a cable. In use, the light source components of the monitoring equipment shine through or into the target site and are transmitted or reflected in a modified form. The modified transmitted or reflected light falling on a photo-detector component of the sensor causes the photo-detector to generate an electrical signal corresponding to the physiological parameter being sensed. This electrical signal is transmitted directly or digitised and transmitted to the monitor by various means, including but not limited to, a conducting wire; infrared, radio- frequency, or fibre-optic connections. It should be noted that the term 'light' as herein used includes the electromagnetic frequencies from far infra-red through visible light to extreme ultraviolet.
Photo-optical components require power to operate, and even relatively low-power light sources are often the major element in a sensor power budget. Therefore, the light source power consumption becomes a limiting factor in continuous operational performance life-time for photo-optical physiological monitoring devices with finite power supplies such as, but not limited to, batteries or solar cells. This limitation is particularly important in the burgeoning field of portable sensors, sensor adapters, and portable monitors. Light sources are typically switched on and off rapidly for a variety of reasons including the need to utilise differing wavelength light sources, to allow ambient light sampling (a passive measurement cycle), and to conserve power. The light source on-time within an active measurement cycle is often maintained beyond the settling time of the photo-detector (i.e. the time taken for the output signal from the photo-detector to stabilise), so that the signal is available to the processing circuit as needed throughout the entire measurement cycle (see Figure 1.). Therefore in many presently available monitors the reduction of the minimum light source on-time is achieved by increasing the processing speed, which forces the use of very fast analogue to digital converter (ADC) components. Unfortunately as the speed of the analogue to digital converter components is increased the power usage and heat produced increases, thus at some point the power saving from shortening the light source on-time is equalled by the increased power consumption of the analogue to digital converter components which limits further savings by this method. Furthermore, even the fastest processing circuits are not instantaneous and can only reduce the light-source on-time to a theoretical minimum; this minimum will in part be determined by the time taken for the light source to stabilise, but is more dependent on the photo-detector settling time plus the residual post-settling processing time.
In the past, physiological monitoring devices have had comparatively large power supplies such as mains supply or large batteries. With the recent development of very small portable and wireless monitoring devices and adapters it has become desirable to avoid these energy sources. This has meant that the portable monitoring device often has a short operational life before the battery must be recharged or replaced. This recharging or replacing disturbs the subject and may mean that valuable monitoring data is lost during the changeover. Therefore means for achieving significant power savings need to be implemented to extend the useful operational life. It is also desirable to use cheap low power components, which often precludes the use of high speed analogue to digital converter or other components, which tend to be expensive and have higher power demands. Disclosure of Invention
It is therefore an object of the present invention to provide the means to reduce the power consumption of light source components of photo-optical physiological monitoring equipment, by limiting the on-time of said components without significantly reducing the performance specification for the equipment. A further object of the invention is to reduce the on-time of the light source to, or close to, the photo-detector settling time without resorting to the use of high speed analogue to digital components or compromising the reliability and accuracy of the photo-optical physiological monitoring equipment.
The present invention provides a power reduction circuit for photo-optical physiological monitoring equipment, wherein said photo-optical physiological monitoring equipment is adapted to be used to measure one or more physiological properties of a subject by illuminating a portion of the subject with one or more light sources, which produces a reflected or transmitted modified light signal representative of the physiological property being measured; the modified light signal is detected by one or more photo- detectors, the or each photo-detector is adapted to produce an output signal that is representative of the modified light signal impinging on that photo-detector, characterised in that, the power reduction circuit includes an isolating switch, a capacitor and a signal buffer.
Preferably the power reduction circuit is arranged such that when the processing circuit requires an active measurement cycle to occur the following steps, in order, are undertaken;
i. the or each light source is turned on; ii. the or each photo-detector produces the output signal; iii. the output signal passes through the isolating switch, charges up the capacitor and is fed to the signal buffer; iv. the output signal is allowed to settle and then the processing circuit opens the isolating switch and turns off the or each light source; v. the capacitor retains the output signal while the isolating switch is open, and supplies the output signal to the signal buffer; vi. the processing circuit reads the output signal from the buffer and processes the output signal; vii. the processing circuit closes the isolating switch;
one or more active measurement cycle, in series or parallel, is required to measure the one or more physiological properties of the subject.
Preferably to measure the one or more physiological properties of the subject two light sources, a first light source and a second light source are used, only the first light source or second light source is on during any single active measurement cycle. The first light source and second light source are preferably of different frequencies; said frequencies being determined by the light absorption characteristics of the biological components involved in the physiological property being measured. In a preferred form a photo-detector is optimised for use with both light sources. In a further preferred form a separate power reduction circuit is associated with each photo- detector such that both light sources and the photo-detector and the power reduction circuit form a detection circuit. Each said detection circuit produces an output signal which is processed by the processing circuit separately or in conjunction with output signals produced during other measurement cycles.
Preferably the or each photo-detector and the or each light source are simultaneously or independently controlled by the processing circuit at any stage during any active measurement cycle.
Preferably the or each light source is selected from an incandescent lamp, a fluorescent lamp, a photo chemical light source, an organic light source, a light emitting diode, a laser, a neon or other gas discharge lamp and an arc lamp. It is highly preferred that the light source is a light emitting diode.
Preferably the processing circuit carries out more than one processing step during the light source off-time using the output signal held in the signal buffer.
Preferably there is more than one light source and more than one photo-detector, where each pair of light sources is associated with a respective photo-detector and power reduction circuit, such that when an active measurement cycle occurs the processing circuit is adapted to access the output from each power reduction circuit in parallel. Preferably the photo-optical physiological monitoring equipment is a pulse oximeter.
Preferably the pulse oximeter is a wireless device, either mono- or bi-directional, in this context wireless includes optical and electromagnetic transmission.
Preferably the processing circuit includes an analogue to digital converter, and transmits the digital signal to an external receiver at regular intervals.
Brief Description of Drawings
Figure 1 : is a graph showing the typical on time of a light source for a photo-optical physiological monitoring device as compared to the on time for a device incorporating the invention; the light source in this case is a light emitting diode (LED).
Figure 1a : is a graph showing the output signal held by the signal buffer over an active measurement cycle and the light source on-time for both the invention and without the invention.
Figure 2 : is a block diagram of the invention.
Figure 3 : is a flowchart showing a method of using the invention.
Figure 4 : is a block diagram of a second embodiment of the invention which includes two light sources.
Figure 5 : is a block diagram of a further embodiment of the invention which includes additional signal processing of the output signal.
Figure 6 : is a block diagram of a further embodiment of the invention which includes an estimation circuit.
Best Mode for Carrying out the Invention
Referring to Figure 2, the invention includes a photo-detector (1), a light source (2), an isolating switch (3) and a processing circuit (4). The light source (2) is adapted to illuminate a portion of a subject (5) for a period of time, the light from the light source (2) interacts with the portion of the subject (5) and is modified. The photo-detector (1) is adapted to respond to certain properties of this modified light and generate an output signal, the properties of the output signal being dependent upon the modified light received.
The photo-detector (1) is connected to the isolating switch (3), which is controlled by the processing circuit (4). The isolating switch (3) is connected to a signal buffer (10) and capacitor (11); the buffer (10) is further connected to the processing circuit (4). In addition the light source (2) is connected to and controlled by the processing circuit (4).
Referring to Figures 1a and 3, in operation, at a predetermined time, the processing circuit (4) commences an active measurement cycle (20). At the start of the active measurement cycle the processing circuit (4) commences a sampling step (21). The sampling step (21) starts when the processing circuit (4) turns on the light source (2); this allows the photo-detector (1) to generate the output signal which passes from the photo-detector (1) through the isolating switch (3) into the capacitor (11) and signal buffer (10). Due to the physical properties of the photo-detector (1) the output signal takes a short time to settle to a stable level, (the settling time). Once this stable level has been achieved the sampling step (21) is completed and the processing circuit (4) opens the isolating switch (3) and turns the light source (2) off. The output signal is then maintained by the capacitor (11) at this stable level, and is passed to the signal buffer (10) for accessing by the processing circuit (4).
The processing circuit (4) reads the output signal in the signal buffer (10) as many times as necessary to complete signal processing during the active measurement cycle (20), the capacitor (11) maintains the output signal level in the signal buffer (10) at the originally measured stable level until the active measurement cycle (20) is complete.
Once the processing circuit (4) has completed processing the output signal the isolating switch (3) is closed ready to commence a next active measurement cycle (23).
In a second embodiment, as shown in Figure 4, the light source (2) is two or more separate light sources (2, 2a). Each of the light sources (2, 2a) has a different output frequency and is used for a separate active measurement cycle (20). Each of these active measurement cycles (20) can occur in series or, if additional isolating switches (3), capacitors (11) and signal buffers (10) are present, in parallel. One or more light source (2, 2a) may be used during any individual active measurement cycle (20) to produce the light spectra required for that measurement.
In a further embodiment the invention, as shown in Figure 5, includes signal conditioning circuits (30) to filter noise and other undesirable signals from the output signal.
In a still further embodiment (not shown) the invention is combined with other power saving devices and procedures, such as, but not limited to, powering down the light source (2) driving circuitry, the isolating switch (3) and the photo-detector (1) once the isolating switch (3) is opened.
In a further embodiment, as shown in Figure 6, the power reduction circuit includes an estimation circuit (31) that predicts the stable level of the photo-detector (1) prior to the photo-detector (1) reaching that level and is adapted to feed that level to the capacitor (11) and signal buffer (10) and then instruct the processing circuit (4) to open the isolating switch (3) and turn off the light source (2) . The estimation circuit (31) only operates after the light source (2) output has stabilised.

Claims

1. A power reduction circuit for photo-optical physiological monitoring equipment, wherein said photo-optical physiological monitoring equipment is adapted to be used to measure one or more physiological properties of a subject by illuminating a portion of the subject with one or more light sources, which produces a reflected or transmitted modified light signal representative of the physiological property being measured; the modified light signal is detected by one or more photo-detectors, and the or each photo-detector is adapted to produce an output signal that is representative of the modified light signal impinging on that photo-detector; characterised in that, the power reduction circuit includes an isolating switch, a capacitor and a signal buffer, wherein the capacitor is adapted to maintain the output signal level in the signal buffer when the isolating switch is opened during an active measurement cycle.
2. Photo-optical physiological monitoring equipment which includes one or more detection circuit, the or each detection circuit includes the power reduction circuit as claimed in claim 1 , one or more light source and one or more photo-detector.
3 The photo-optical physiological monitoring equipment as claimed in claim 2 characterised in that it further includes a processing circuit.
4. The photo-optical physiological monitoring equipment as claimed in claim 2, characterised in that to measure the one or more physiological properties of the subject two light sources, a first light source and a second light source are used.
5. The photo-optical physiological monitoring equipment as claimed in claim 4, characterised in that only the first light source or second light source is on during any single active measurement cycle.
6. The photo-optical physiological monitoring equipment as claimed in claim 4, characterised in that the first light source and second light source are of different frequencies; said frequencies being determined by the light absorption characteristics of the biological components involved in the physiological property being measured.
7. The photo-optical physiological monitoring equipment as claimed in claim 6, characterised in that the or each photo-detector is optimised for use with both light sources.
8. The photo-optical physiological monitoring equipment as claimed in claim 3, characterised in that the or each detection circuit is adapted to produce an output signal which is processed by the processing circuit separately or in conjunction with output signals produced during other measurement cycles.
9. The photo-optical physiological monitoring equipment as claimed in claim 3, characterised in that the or each photo-detector and the or each light source are adapted to be simultaneously or independently controlled by the processing circuit at any stage during any active measurement cycle.
10. The photo-optical physiological monitoring equipment as claimed in claim 3, characterised in that the processing circuit is adapted to carry out more than one processing step during the light source off-time using the output signal held in the signal buffer.
11. The photo-optical physiological monitoring equipment as claimed in claim 2, characterised in that the there is more than one light source and more than one photo-detector, where each pair of light sources is associated with a respective photo-detector and power reduction circuit, such that when an active measurement cycle occurs the processing circuit is adapted to access the output from each power reduction circuit in parallel.
12. The photo-optical physiological monitoring equipment as claimed in claim 2, characterised in that the photo-optical physiological monitoring equipment is a pulse oximeter.
13. The pulse oximeter as claimed in claim 12, characterised in that the pulse oximeter is a wireless device, either mono- or bi-directional.
14. The photo-optical physiological monitoring equipment as claimed in claim 3, characterised in that the processing circuit includes an analogue to digital converter.
15. The analogue to digital converter as claimed in claim 14, characterised in that the analogue to digital converter is adapted to transmit a digital signal to an external receiver at regular intervals.
16. The photo-optical physiological monitoring equipment as claimed in claim 2, characterised in that the or each light source is selected from the list consisting of an incandescent lamp, a fluorescent lamp, a photo chemical light source, an organic light source, a light emitting diode, a laser, a neon or other gas discharge lamp and an arc lamp.
17. A method for using the power reduction circuit for photo-optical physiological monitoring equipment as claimed in claim 1 , characterised in that when the processing circuit requires an active measurement cycle to occur the following steps, in order, are undertaken;
i. the or each light source is turned on; ii. the or each photo-detector produces the output signal; iii. the output signal passes through the isolating switch, charges up the capacitor and is fed to the signal buffer; iv. the output signal is allowed to settle and then the processing circuit opens the isolating switch and turns off the or each light source; v. the capacitor retains the output signal while the isolating switch is open, and supplies the output signal to the signal buffer; vi. the processing circuit reads the output signal from the buffer and processes the output signal; vii. the processing circuit closes the isolating switch.
18. The photo-optical physiological monitoring equipment as claimed in claim 2 characterised in that one or more active measurement cycle, in series or parallel, is required to measure the one or more physiological properties of the subject.
PCT/NZ2005/000028 2005-01-31 2005-02-24 Power reduction circuit for photo-optical physiological monitoring equipment WO2006080856A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NZ538013 2005-01-31
NZ53801305 2005-01-31

Publications (1)

Publication Number Publication Date
WO2006080856A1 true WO2006080856A1 (en) 2006-08-03

Family

ID=36740787

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/NZ2005/000028 WO2006080856A1 (en) 2005-01-31 2005-02-24 Power reduction circuit for photo-optical physiological monitoring equipment

Country Status (1)

Country Link
WO (1) WO2006080856A1 (en)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2644094A1 (en) * 2012-03-26 2013-10-02 General Electric Company Sensor, gas analyzer and method for measuring concentration of at least one respiratory gas component
US9241676B2 (en) 2012-05-31 2016-01-26 Covidien Lp Methods and systems for power optimization in a medical device
US9241643B2 (en) 2012-05-31 2016-01-26 Covidien Lp Methods and systems for power optimization in a medical device
US9351688B2 (en) 2013-01-29 2016-05-31 Covidien Lp Low power monitoring systems and method
US9560994B2 (en) 2008-03-26 2017-02-07 Covidien Lp Pulse oximeter with adaptive power conservation

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3799672A (en) * 1972-09-15 1974-03-26 Us Health Education & Welfare Oximeter for monitoring oxygen saturation in blood
US4781195A (en) * 1987-12-02 1988-11-01 The Boc Group, Inc. Blood monitoring apparatus and methods with amplifier input dark current correction
US5954644A (en) * 1997-03-24 1999-09-21 Ohmeda Inc. Method for ambient light subtraction in a photoplethysmographic measurement instrument
US6720734B2 (en) * 2002-08-08 2004-04-13 Datex-Ohmeda, Inc. Oximeter with nulled op-amp current feedback

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3799672A (en) * 1972-09-15 1974-03-26 Us Health Education & Welfare Oximeter for monitoring oxygen saturation in blood
US4781195A (en) * 1987-12-02 1988-11-01 The Boc Group, Inc. Blood monitoring apparatus and methods with amplifier input dark current correction
US5954644A (en) * 1997-03-24 1999-09-21 Ohmeda Inc. Method for ambient light subtraction in a photoplethysmographic measurement instrument
US6720734B2 (en) * 2002-08-08 2004-04-13 Datex-Ohmeda, Inc. Oximeter with nulled op-amp current feedback

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US9560994B2 (en) 2008-03-26 2017-02-07 Covidien Lp Pulse oximeter with adaptive power conservation
EP2644094A1 (en) * 2012-03-26 2013-10-02 General Electric Company Sensor, gas analyzer and method for measuring concentration of at least one respiratory gas component
US10052025B2 (en) 2012-03-26 2018-08-21 Ge Healthcare Finland Oy Sensor, gas analyzer and method for measuring concentration of at least one respiratory gas component
US9241676B2 (en) 2012-05-31 2016-01-26 Covidien Lp Methods and systems for power optimization in a medical device
US9241643B2 (en) 2012-05-31 2016-01-26 Covidien Lp Methods and systems for power optimization in a medical device
US9517018B2 (en) 2012-05-31 2016-12-13 Covidien Lp Methods and systems for power optimization in a medical device
US9538961B2 (en) 2012-05-31 2017-01-10 Covidien Lp Methods and systems for power optimization in a medical device
US9351688B2 (en) 2013-01-29 2016-05-31 Covidien Lp Low power monitoring systems and method

Similar Documents

Publication Publication Date Title
US11885672B2 (en) Wireless battery-powered daylight sensor
EP2438798B1 (en) Wake-up of light sensor in a lighting system
US9743868B2 (en) Circuitry to allow low current operation of a device capable of determining a blood property
US7639158B2 (en) Monitoring terminal device
WO2006080856A1 (en) Power reduction circuit for photo-optical physiological monitoring equipment
TWI651516B (en) Photoelectric detector, photoelectric detection method and heart rate detecting device using same
US20150289791A1 (en) Pulse Oximeter Using Burst Sampling
US20100163713A1 (en) Electromagnetic wave sensing apparatus
WO2006083180A1 (en) Ambient light auto-zero circuit for photo-optical physiological monitoring equipment
JP5362631B2 (en) Wireless transmission device
CN114034384B (en) Photoelectric sampling assembly and wearable equipment
JP2011251007A (en) Bio-pulse wave sensor and bio-pulse wave measuring device
JP2005203275A (en) Luminaire
JP2009210565A (en) Light quantity monitor sensor and image processing system equipped with this
CN108811255A (en) A kind of infrared induction night-light and control mode
CN216247679U (en) Control circuit for optical interference type methane measuring instrument and optical interference type methane measuring instrument
CN209845382U (en) Infrared induction control lamp and refrigeration equipment

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 05710979

Country of ref document: EP

Kind code of ref document: A1