CA2374144A1 - A pulse oximeter having a low power led drive - Google Patents
A pulse oximeter having a low power led drive Download PDFInfo
- Publication number
- CA2374144A1 CA2374144A1 CA002374144A CA2374144A CA2374144A1 CA 2374144 A1 CA2374144 A1 CA 2374144A1 CA 002374144 A CA002374144 A CA 002374144A CA 2374144 A CA2374144 A CA 2374144A CA 2374144 A1 CA2374144 A1 CA 2374144A1
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- Canada
- Prior art keywords
- energy storage
- storage circuitry
- light source
- switched
- circuitry
- Prior art date
- Legal status (The legal status 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 status listed.)
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Classifications
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/1455—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters
- A61B5/14551—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using optical sensors, e.g. spectral photometrical oximeters for measuring blood gases
-
- 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
Abstract
A photometer (10) includes a light source (12) operable to direct light toward a sample (14), a detection circuit (16) operable to detect light after it has passed through the sample (14), and a drive circuit (18) for powering the light source (12). The drive circuit (18) includes an input (20) for coupling with a source of power, and energy storage circuitry (22) coupled with the input (20). The energy storage circuitry (22) is operable to store energy from the source of power when switched to a charging state, and to deliver current to the light source (12) in a ramped manner when switched to a discharge state so that the current peaks at a selected time. The drive circuit (18) delivers a controlled amount of current to the light source (12) that peaks only after the detection circuit (16) has settled so that power is not wasted at the startup of the oximeter (10).
Description
A PULSE OXIMETER HAVING A LOW POWER LED DRIVE
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to photometers such as pulse oximeters. More particularly, the invention relates to a pulse oximeter having a low power drive for efficiently powering the light source of the oximeter.
BACKGROUND OF THE INVENTION
1. Field of the Invention The present invention relates to photometers such as pulse oximeters. More particularly, the invention relates to a pulse oximeter having a low power drive for efficiently powering the light source of the oximeter.
2. Description of the Prior Art Oximeters are used to measure the oxygenated fraction of hemoglobin in blood by analyzing the absorption of light transmitted through or reflected from the blood.
A typical oximeter includes a light source such as a light emitting diode (LED) that generates and directs light toward a sample, a drive circuit for powering the LED, and a detection circuit that detects and analyzes the light from the LED after it has passed through the sample. After the LED is turned on, the detection circuit must "settle"
before an accurate reading can be made. This results in inefficient power usage in existing oximeters because power delivered to the LED is wasted while the detection circuit is settling and because much of the current generated by the LED drive circuitry dissipates in resistive components of the circuitry.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention solves the above-described problems and provides a distinct advance in the art of oximeters and other photometers. More particularly, the present invention provides a pulse oximeter having a low power LED drive that uses power more efficiently, especially during the settling time of the oximeter.
The oximeter of the present invention broadly includes a light source operable to direct light toward a sample, a detection circuit operable to detect the light after it has passed through the sample, and a drive circuit for powering the light source.
The drive circuit is configured to deliver a controlled amount of current to the LED that peaks only after the detection circuit has settled so that power is not wasted at the startup of the oximeter. The drive circuit is also configured to temporarily store and then deliver all of the energy from a source of power to the LED without dissipating much of the energy in resistive components.
The drive circuit includes an input for coupling with a source of power and energy storage circuitry coupled with the input. The energy storage circuitry is operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner when switched to a discharge state so that the current peaks at a selected time.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figure, wherein:
Fig. 1 is an electrical schematic diagram of an oximeter constructed in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to Fig. 1, an oximeter 10 constructed in accordance with a preferred embodiment of the invention is illustrated. The oximeter broadly includes a light source 12 operable to direct light toward a sample 14, a detection circuit 16 operable to detect the light after it has passed through the sample, and a drive circuit generally referred to by the numeral 18 for powering the light source. The sample may be a person's finger or other body part or a blood sample withdrawn from a patient.
The light source 12, which is conventional, is preferably a light emitting diode (LED), but may be any other light source used in photometers. The detection circuit 16, which is also conventional, may include any light sensitive sensor and detection circuitry used with oximeters or other photometers.
The drive circuit 18 is coupled with the light source 12 and a source of power such as a six-volt battery and is operable to power the light source. The drive circuit broadly includes an input 20, energy storage circuitry generally referred to by the numeral 22, switching circuitry generally referred to by the numeral 24, and current measuring circuitry generally referred to by the numeral 26.
The input 20 is configured for coupling with the source of power for delivering current from the power source to the energy storage circuitry 20 as described below.
The input may also be coupled with a current limiting resistor (not shown) and one or more capacitors (not shown) for limiting the current delivered to the energy storage circuitry.
In accordance with one aspect of the present invention, the energy storage circuitry 22 is configured to store energy from the source of power when the circuitry is switched to a charging state and to deliver current to the light source 12 in a controlled manner when switched to a discharge state. The storage circuitry preferably includes a capacitor C 1 and an inductor L 1 connected as illustrated. As described in more detail below, C 1 stores a charge delivered from the source of power when the energy storage circuitry is switched to its charging state and discharges the charge to the light source when the energy storage circuitry is switched to its discharge state. L 1 is wired between the input 20 and C 1 and is configured to charge C 1 when the energy storage circuitry is switched to its charging state and to deliver the charge from C 1 to the light source when the energy storage circuitry is switched to its discharge state.
C 1 and L 1 are sized to form a tuned circuit that resonates such that a partial half wave of current is delivered to the light source 12 and allowed to peak once the detection circuit 16 has settled. In one embodiment, C 1 has a value of 16v, 1 OuF and L 1 has a value of 470uH.
The switching circuitry 24 preferably includes a transistor Q1, a transistor and a transistor Q3. Q1, Q2, and Q3 together switch the energy storage circuitry 22 between its charging state and its discharge state to selectively store energy in the circuitry 22 and to then deliver the stored energy to the light source 12.
Q 1 is wired between the input 20 and the energy storage circuitry 21 to selectively switch energy from the power source to the energy storage circuitry for charging the circuitry. Q 1 is preferably turned on and off by a processor 28, which can be programmed to turn Q 1 on for a selected time period for controlling the amount of energy delivered to the energy storage circuitry from the power source.
Q2 is wired between the energy storage circuitry 22 and the light source 12 to selectively switch current stored in the energy storage circuitry to the light source. Q3 is wired between the energy storage circuitry and ground to selectively ground the light source. Q2 and Q3 are preferably switched on and off by the processor 28 or by another controller. As illustrated, the input to Q3 is inverted by an inverter 30 whereas the input to Q2 is not; therefore, whenever Q2 is switched on, Q3 is switched off, and vice versa.
The current measuring circuitry 26 is coupled with the energy storage circuitry 22 and is operable for measuring the amount of current that is delivered to the light source 12. This current reading is then used as a feedback for use in calibrating the amount of time that Q 1 is switched on while charging the energy storage circuitry. The current measuring circuitry preferably includes a capacitor C2, a resistor R1, a sampling sigma delta convertor 32, and a processor 34. C2 preferably has a rating of SOv, .OluF
and R1 preferably has a rating of 3.01K ohm.
A typical oximeter includes a light source such as a light emitting diode (LED) that generates and directs light toward a sample, a drive circuit for powering the LED, and a detection circuit that detects and analyzes the light from the LED after it has passed through the sample. After the LED is turned on, the detection circuit must "settle"
before an accurate reading can be made. This results in inefficient power usage in existing oximeters because power delivered to the LED is wasted while the detection circuit is settling and because much of the current generated by the LED drive circuitry dissipates in resistive components of the circuitry.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention solves the above-described problems and provides a distinct advance in the art of oximeters and other photometers. More particularly, the present invention provides a pulse oximeter having a low power LED drive that uses power more efficiently, especially during the settling time of the oximeter.
The oximeter of the present invention broadly includes a light source operable to direct light toward a sample, a detection circuit operable to detect the light after it has passed through the sample, and a drive circuit for powering the light source.
The drive circuit is configured to deliver a controlled amount of current to the LED that peaks only after the detection circuit has settled so that power is not wasted at the startup of the oximeter. The drive circuit is also configured to temporarily store and then deliver all of the energy from a source of power to the LED without dissipating much of the energy in resistive components.
The drive circuit includes an input for coupling with a source of power and energy storage circuitry coupled with the input. The energy storage circuitry is operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner when switched to a discharge state so that the current peaks at a selected time.
BRIEF DESCRIPTION OF THE DRAWING FIGURES
A preferred embodiment of the present invention is described in detail below with reference to the attached drawing figure, wherein:
Fig. 1 is an electrical schematic diagram of an oximeter constructed in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Turning now to Fig. 1, an oximeter 10 constructed in accordance with a preferred embodiment of the invention is illustrated. The oximeter broadly includes a light source 12 operable to direct light toward a sample 14, a detection circuit 16 operable to detect the light after it has passed through the sample, and a drive circuit generally referred to by the numeral 18 for powering the light source. The sample may be a person's finger or other body part or a blood sample withdrawn from a patient.
The light source 12, which is conventional, is preferably a light emitting diode (LED), but may be any other light source used in photometers. The detection circuit 16, which is also conventional, may include any light sensitive sensor and detection circuitry used with oximeters or other photometers.
The drive circuit 18 is coupled with the light source 12 and a source of power such as a six-volt battery and is operable to power the light source. The drive circuit broadly includes an input 20, energy storage circuitry generally referred to by the numeral 22, switching circuitry generally referred to by the numeral 24, and current measuring circuitry generally referred to by the numeral 26.
The input 20 is configured for coupling with the source of power for delivering current from the power source to the energy storage circuitry 20 as described below.
The input may also be coupled with a current limiting resistor (not shown) and one or more capacitors (not shown) for limiting the current delivered to the energy storage circuitry.
In accordance with one aspect of the present invention, the energy storage circuitry 22 is configured to store energy from the source of power when the circuitry is switched to a charging state and to deliver current to the light source 12 in a controlled manner when switched to a discharge state. The storage circuitry preferably includes a capacitor C 1 and an inductor L 1 connected as illustrated. As described in more detail below, C 1 stores a charge delivered from the source of power when the energy storage circuitry is switched to its charging state and discharges the charge to the light source when the energy storage circuitry is switched to its discharge state. L 1 is wired between the input 20 and C 1 and is configured to charge C 1 when the energy storage circuitry is switched to its charging state and to deliver the charge from C 1 to the light source when the energy storage circuitry is switched to its discharge state.
C 1 and L 1 are sized to form a tuned circuit that resonates such that a partial half wave of current is delivered to the light source 12 and allowed to peak once the detection circuit 16 has settled. In one embodiment, C 1 has a value of 16v, 1 OuF and L 1 has a value of 470uH.
The switching circuitry 24 preferably includes a transistor Q1, a transistor and a transistor Q3. Q1, Q2, and Q3 together switch the energy storage circuitry 22 between its charging state and its discharge state to selectively store energy in the circuitry 22 and to then deliver the stored energy to the light source 12.
Q 1 is wired between the input 20 and the energy storage circuitry 21 to selectively switch energy from the power source to the energy storage circuitry for charging the circuitry. Q 1 is preferably turned on and off by a processor 28, which can be programmed to turn Q 1 on for a selected time period for controlling the amount of energy delivered to the energy storage circuitry from the power source.
Q2 is wired between the energy storage circuitry 22 and the light source 12 to selectively switch current stored in the energy storage circuitry to the light source. Q3 is wired between the energy storage circuitry and ground to selectively ground the light source. Q2 and Q3 are preferably switched on and off by the processor 28 or by another controller. As illustrated, the input to Q3 is inverted by an inverter 30 whereas the input to Q2 is not; therefore, whenever Q2 is switched on, Q3 is switched off, and vice versa.
The current measuring circuitry 26 is coupled with the energy storage circuitry 22 and is operable for measuring the amount of current that is delivered to the light source 12. This current reading is then used as a feedback for use in calibrating the amount of time that Q 1 is switched on while charging the energy storage circuitry. The current measuring circuitry preferably includes a capacitor C2, a resistor R1, a sampling sigma delta convertor 32, and a processor 34. C2 preferably has a rating of SOv, .OluF
and R1 preferably has a rating of 3.01K ohm.
Operation In operation, the processor 28 initially switches Q1 and Q2 off (open) and switches Q3 on (closed). Because Q 1 and Q2 are off, the power source connected to the input 20 is not delivering energy to the energy storage circuitry 22, and the energy storage circuitry is not delivering a charge to the light source. Because Q3 is switched on, both lines to the light source are grounded so that no current is being delivered to the light source.
When it is desired to operate the oximeter 10, the processor 28 turns on Q1 for a very brief period to transfer energy from the power source to the energy storage circuitry 22 through L 1. The amount of energy transferred to C 1 is directly related to how long Q1 is turned on. Thus, the processor 28 is programmable to provide a selected width pulse to Q 1 to control the amount of energy delivered to C 1.
In preferred forms, the processor switches Q 1 on for approximately 5 to 1 OuS.
Once the desired amount of energy has been stored in the energy storage circuitry 22, the processor 28 switches Q I off to stop the delivery of energy to the energy storage circuitry. However, a magnetic field, which builds up in L 1 while Q 1 is on, continues to transfer energy to C1 after Q1 is turned off. This is because when Q 1 turns off, the negative side of L 1 is grounded through the substrate diode of QZ and through Q3, which is still on. Therefore, the collapsing magnetic field on L 1 transfers all of its energy (except the energy that is lost across the diode of Q2) to C
1.
After the energy storage circuitry 22 has become fully charged, the switching circuitry 24 may be selectively operated to discharge the stored energy to the light source 12 for illuminating the light source. Specifically, the processor 28 turns Q2 on and turns Q3 off so that L 1 and C 1 are connected to the light source. This causes the charge on C I to discharge to the light source through L 1 and Q2. Because L l and C 1 form a tuned circuit as described above, a partial, sinusoidal half wave of current is delivered to the light source. The drive circuit 18 is configured so that the current peaks at a selected time after the energy storage circuitry begins to discharge to the light source. This allows the current delivered to the light source to peak at the same time the detection circuitry 16 has settled so that a minimal amount of energy is wasted during the settling time of the detection circuitry.
Once the energy storage circuitry 22 discharges its energy to the light source 12, the above charging and discharging steps can be repeated when it is desired to once again operate the oximeter.
When it is desired to operate the oximeter 10, the processor 28 turns on Q1 for a very brief period to transfer energy from the power source to the energy storage circuitry 22 through L 1. The amount of energy transferred to C 1 is directly related to how long Q1 is turned on. Thus, the processor 28 is programmable to provide a selected width pulse to Q 1 to control the amount of energy delivered to C 1.
In preferred forms, the processor switches Q 1 on for approximately 5 to 1 OuS.
Once the desired amount of energy has been stored in the energy storage circuitry 22, the processor 28 switches Q I off to stop the delivery of energy to the energy storage circuitry. However, a magnetic field, which builds up in L 1 while Q 1 is on, continues to transfer energy to C1 after Q1 is turned off. This is because when Q 1 turns off, the negative side of L 1 is grounded through the substrate diode of QZ and through Q3, which is still on. Therefore, the collapsing magnetic field on L 1 transfers all of its energy (except the energy that is lost across the diode of Q2) to C
1.
After the energy storage circuitry 22 has become fully charged, the switching circuitry 24 may be selectively operated to discharge the stored energy to the light source 12 for illuminating the light source. Specifically, the processor 28 turns Q2 on and turns Q3 off so that L 1 and C 1 are connected to the light source. This causes the charge on C I to discharge to the light source through L 1 and Q2. Because L l and C 1 form a tuned circuit as described above, a partial, sinusoidal half wave of current is delivered to the light source. The drive circuit 18 is configured so that the current peaks at a selected time after the energy storage circuitry begins to discharge to the light source. This allows the current delivered to the light source to peak at the same time the detection circuitry 16 has settled so that a minimal amount of energy is wasted during the settling time of the detection circuitry.
Once the energy storage circuitry 22 discharges its energy to the light source 12, the above charging and discharging steps can be repeated when it is desired to once again operate the oximeter.
To deliver the optimum amount of current to the light source 12 to achieve the above-described results, the programmable width pulse delivered to Q 1 by the processor 28 must be selected. Because the optimum amount of current delivered to the light source is dependent on the characteristic voltage drop of the light source itself, the voltage drop of the light source must be measured to calibrate the width of the pulse delivered to Q1. This is done by measuring the current delivered from the energy storage circuitry 22 to the light source that results from a given pulse width.
This current measurement is derived from the current flowing through C2 which, with R1, is in parallel with C1. Because the value of R1 is so low it can be essentially ignored, C2 is essentially in parallel with C 1. Furthermore, because C 1 is 1,000 times larger than C2, the current flowing through C2 is 1/1000 the current flowing through C1. R1 converts the current through C2 to a voltage that can be measured by the sampling sigma delta convertor 32 and the processor 34. The measured voltage is then used as feedback to the processor 28 to vary the width if the pulse delivered to Q1 to selectively vary the amount of energy that is delivered to the energy storage circuitry 22 and that is eventually discharged to the light source 12.
Once properly calibrated, the drive circuitry 18 delivers a controlled amount of current to the light source 12 that peaks only after the detection circuit 16 has settled.
This reduces the amount of power that is wasted by the light source during the initial settling time of the detection circuit. Additionally, because the energy storage circuitry 22 includes a capacitor and an inductor but no resistive components, very little power is dissipated during the charging and discharge states of the circuitry.
Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawing figure, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. For example, although the drive circuit of the present invention has been illustrated and described as being used with a pulse oximeter, it may also be used with other photometer devices for driving the light sources thereof.
Having thus described the preferred embodiment of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
This current measurement is derived from the current flowing through C2 which, with R1, is in parallel with C1. Because the value of R1 is so low it can be essentially ignored, C2 is essentially in parallel with C 1. Furthermore, because C 1 is 1,000 times larger than C2, the current flowing through C2 is 1/1000 the current flowing through C1. R1 converts the current through C2 to a voltage that can be measured by the sampling sigma delta convertor 32 and the processor 34. The measured voltage is then used as feedback to the processor 28 to vary the width if the pulse delivered to Q1 to selectively vary the amount of energy that is delivered to the energy storage circuitry 22 and that is eventually discharged to the light source 12.
Once properly calibrated, the drive circuitry 18 delivers a controlled amount of current to the light source 12 that peaks only after the detection circuit 16 has settled.
This reduces the amount of power that is wasted by the light source during the initial settling time of the detection circuit. Additionally, because the energy storage circuitry 22 includes a capacitor and an inductor but no resistive components, very little power is dissipated during the charging and discharge states of the circuitry.
Although the invention has been described with reference to the preferred embodiment illustrated in the attached drawing figure, it is noted that equivalents may be employed and substitutions made herein without departing from the scope of the invention as recited in the claims. For example, although the drive circuit of the present invention has been illustrated and described as being used with a pulse oximeter, it may also be used with other photometer devices for driving the light sources thereof.
Having thus described the preferred embodiment of the invention, what is claimed as new and desired to be protected by Letters Patent includes the following:
Claims (15)
1. A photometer comprising:
a light source operable to direct light toward a sample;
a detection circuit operable to detect the light after it has passed through the sample; and a drive circuit for powering the light source, the drive circuit including --an input for coupling with a source of power, and energy storage circuitry coupled with the input and operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner so that the current peaks at a selected time when switched to a discharge state.
a light source operable to direct light toward a sample;
a detection circuit operable to detect the light after it has passed through the sample; and a drive circuit for powering the light source, the drive circuit including --an input for coupling with a source of power, and energy storage circuitry coupled with the input and operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner so that the current peaks at a selected time when switched to a discharge state.
2. The photometer as set forth in claim 1, the drive circuit further including switching circuitry for selectively switching the energy storage circuitry between the charging state and discharge state.
3. The photometer as set forth in claim 1, the energy storage circuitry including:
a capacitor for storing a charge when the energy storage circuitry is switched to the charging state and for discharging the charge to the light source when the energy storage circuitry is switched to the discharge state; and an inductor wired between the input and the capacitor for charging the capacitor when the energy storage circuitry is switched to the charging state and for delivering the charge from the capacitor to the light source when the energy storage circuitry is switched to the discharge state.
a capacitor for storing a charge when the energy storage circuitry is switched to the charging state and for discharging the charge to the light source when the energy storage circuitry is switched to the discharge state; and an inductor wired between the input and the capacitor for charging the capacitor when the energy storage circuitry is switched to the charging state and for delivering the charge from the capacitor to the light source when the energy storage circuitry is switched to the discharge state.
4. The photometer as set forth in claim 3, wherein the capacitor and the inductor form a tuned circuit operable to resonate such that a partial half wave of current is allowed to peak while the energy storage circuitry is in the discharge state.
5. The photometer as set forth in claim 2, the switching circuitry including a first transistor wired between the input and the energy storage circuitry for switching energy from the power source to the energy storage circuitry.
6. The photometer as set forth in claim 5, the switching circuitry further including a second transistor wired between the energy storage circuitry and the light source for switching current from the energy storage circuitry to the light source.
7. The photometer as set forth in claim 1, the light source comprising a light emitting diode.
8. A drive circuit for powering a light source in a photometer, the drive circuit comprising:
an input for coupling with a source of power; and energy storage circuitry coupled with the input and operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner so that the current peaks at a selected time when switched to a discharge state.
an input for coupling with a source of power; and energy storage circuitry coupled with the input and operable to store energy from the source of power when switched to a charging state and to deliver current to the light source in a ramped manner so that the current peaks at a selected time when switched to a discharge state.
9. The drive circuit as set forth in claim 8, further including switching circuitry for selectively switching the energy storage circuitry between the charging state and discharge state.
10. The drive circuit as set forth in claim 8, the energy storage circuitry including:
a first capacitor for storing a charge when the energy storage circuitry is switched to the charging state and for discharging the charge to the light source when the energy storage circuitry is switched to the discharge state; and an inductor wired between the input and the first capacitor for charging the first capacitor when the energy storage circuitry is switched to the charging state and for delivering the charge from the first capacitor to the light source when the energy storage circuitry is switched to the discharge state.
a first capacitor for storing a charge when the energy storage circuitry is switched to the charging state and for discharging the charge to the light source when the energy storage circuitry is switched to the discharge state; and an inductor wired between the input and the first capacitor for charging the first capacitor when the energy storage circuitry is switched to the charging state and for delivering the charge from the first capacitor to the light source when the energy storage circuitry is switched to the discharge state.
11. The photometer as set forth in claim 10, wherein the capacitor and the inductor form a tuned circuit operable to resonate such that a partial half wave of current is allowed to peak while the energy storage circuitry is in the discharge state.
12. The photometer as set forth in claim 9, the switching circuitry including a first transistor wired between the input and the energy storage circuitry for switching energy from the power source to the energy storage circuitry.
13. The photometer as set forth in claim 12, the switching circuitry further including a second transistor wired between the energy storage circuitry and the light source for switching current from the energy storage circuitry to the light source.
14. The photometer as set forth in claim 8, the light source comprising a light emitting diode.
15. The photometer as set forth in claim 10, further including a second capacitor coupled with the first capacitor for measuring the current delivered to the light source when the energy storage circuitry is switched to the discharge state.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/320,145 | 1999-05-26 | ||
| US09/320,145 US6226539B1 (en) | 1999-05-26 | 1999-05-26 | Pulse oximeter having a low power led drive |
| PCT/US2000/008870 WO2000072749A1 (en) | 1999-05-26 | 2000-04-04 | A pulse oximeter having a low power led drive |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2374144A1 true CA2374144A1 (en) | 2000-12-07 |
Family
ID=23245073
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002374144A Abandoned CA2374144A1 (en) | 1999-05-26 | 2000-04-04 | A pulse oximeter having a low power led drive |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US6226539B1 (en) |
| EP (1) | EP1180961A4 (en) |
| JP (1) | JP4641626B2 (en) |
| CA (1) | CA2374144A1 (en) |
| WO (1) | WO2000072749A1 (en) |
Families Citing this family (98)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6018673A (en) | 1996-10-10 | 2000-01-25 | Nellcor Puritan Bennett Incorporated | Motion compatible sensor for non-invasive optical blood analysis |
| US6675031B1 (en) | 1999-04-14 | 2004-01-06 | Mallinckrodt Inc. | Method and circuit for indicating quality and accuracy of physiological measurements |
| CA2405825C (en) | 2000-04-17 | 2010-11-09 | Nellcor Puritan Bennett Incorporated | Pulse oximeter sensor with piece-wise function |
| US8224412B2 (en) | 2000-04-17 | 2012-07-17 | Nellcor Puritan Bennett Llc | Pulse oximeter sensor with piece-wise function |
| AU2001228255B2 (en) * | 2001-02-07 | 2005-05-19 | Ao Technology Ag | Method for establishing a three-dimensional representation of bone X-ray images |
| US6697658B2 (en) | 2001-07-02 | 2004-02-24 | Masimo Corporation | Low power pulse oximeter |
| US6654621B2 (en) | 2001-08-29 | 2003-11-25 | Bci, Inc. | Finger oximeter with finger grip suspension system |
| US6748254B2 (en) | 2001-10-12 | 2004-06-08 | Nellcor Puritan Bennett Incorporated | Stacked adhesive optical sensor |
| US6674269B1 (en) * | 2002-09-23 | 2004-01-06 | Xerox Corporation | Light emitting diode driver and image forming device including the same |
| US7190986B1 (en) | 2002-10-18 | 2007-03-13 | Nellcor Puritan Bennett Inc. | Non-adhesive oximeter sensor for sensitive skin |
| US7019662B2 (en) * | 2003-07-29 | 2006-03-28 | Universal Lighting Technologies, Inc. | LED drive for generating constant light output |
| US7215985B2 (en) * | 2004-02-25 | 2007-05-08 | Nellcor Puritain Bennett Inc. | Oximeter cross-talk reduction |
| US7120480B2 (en) * | 2004-02-25 | 2006-10-10 | Nellcor Puritan Bennett Inc. | LED forward voltage estimation in pulse oximeter |
| US7212847B2 (en) * | 2004-02-25 | 2007-05-01 | Nellcor Puritan Bennett Llc | Delta-sigma modulator for outputting analog representation of physiological signal |
| US7373192B2 (en) * | 2004-02-25 | 2008-05-13 | Nellcor Puritan Bennett Inc. | Oximeter red and IR zero calibration control |
| US7142142B2 (en) * | 2004-02-25 | 2006-11-28 | Nelicor Puritan Bennett, Inc. | Multi-bit ADC with sigma-delta modulation |
| US7190985B2 (en) | 2004-02-25 | 2007-03-13 | Nellcor Puritan Bennett Inc. | Oximeter ambient light cancellation |
| US7120479B2 (en) * | 2004-02-25 | 2006-10-10 | Nellcor Puritan Bennett Inc. | Switch-mode oximeter LED drive with a single inductor |
| US7162288B2 (en) * | 2004-02-25 | 2007-01-09 | Nellcor Purtain Bennett Incorporated | Techniques for detecting heart pulses and reducing power consumption in sensors |
| EP1860993B1 (en) | 2005-03-01 | 2019-01-23 | Masimo Laboratories, Inc. | Noninvasive multi-parameter patient monitor |
| US7590439B2 (en) | 2005-08-08 | 2009-09-15 | Nellcor Puritan Bennett Llc | Bi-stable medical sensor and technique for using the same |
| US7657294B2 (en) | 2005-08-08 | 2010-02-02 | Nellcor Puritan Bennett Llc | Compliant diaphragm medical sensor and technique for using the same |
| US7657295B2 (en) | 2005-08-08 | 2010-02-02 | Nellcor Puritan Bennett Llc | Medical sensor and technique for using the same |
| US20070060808A1 (en) | 2005-09-12 | 2007-03-15 | Carine Hoarau | Medical sensor for reducing motion artifacts and technique for using the same |
| US7904130B2 (en) | 2005-09-29 | 2011-03-08 | Nellcor Puritan Bennett Llc | Medical sensor and technique for using the same |
| US8092379B2 (en) | 2005-09-29 | 2012-01-10 | Nellcor Puritan Bennett Llc | Method and system for determining when to reposition a physiological sensor |
| US7869850B2 (en) | 2005-09-29 | 2011-01-11 | Nellcor Puritan Bennett Llc | Medical sensor for reducing motion artifacts and technique for using the same |
| US7899510B2 (en) | 2005-09-29 | 2011-03-01 | Nellcor Puritan Bennett Llc | Medical sensor and technique for using the same |
| US7555327B2 (en) | 2005-09-30 | 2009-06-30 | Nellcor Puritan Bennett Llc | Folding medical sensor and technique for using the same |
| US7881762B2 (en) | 2005-09-30 | 2011-02-01 | Nellcor Puritan Bennett Llc | Clip-style medical sensor and technique for using the same |
| US7483731B2 (en) | 2005-09-30 | 2009-01-27 | Nellcor Puritan Bennett Llc | Medical sensor and technique for using the same |
| US7486979B2 (en) | 2005-09-30 | 2009-02-03 | Nellcor Puritan Bennett Llc | Optically aligned pulse oximetry sensor and technique for using the same |
| US8233954B2 (en) | 2005-09-30 | 2012-07-31 | Nellcor Puritan Bennett Llc | Mucosal sensor for the assessment of tissue and blood constituents and technique for using the same |
| US8062221B2 (en) | 2005-09-30 | 2011-11-22 | Nellcor Puritan Bennett Llc | Sensor for tissue gas detection and technique for using the same |
| US20070091813A1 (en) * | 2005-10-19 | 2007-04-26 | Guy Richard | Automatic channel switching method for low-power communication devices |
| US7400310B2 (en) | 2005-11-28 | 2008-07-15 | Draeger Medical Systems, Inc. | Pulse signal drive circuit |
| US20070129617A1 (en) * | 2005-12-02 | 2007-06-07 | Michel Noel | Light source drive algorithm |
| US8073518B2 (en) | 2006-05-02 | 2011-12-06 | Nellcor Puritan Bennett Llc | Clip-style medical sensor and technique for using the same |
| US8145288B2 (en) | 2006-08-22 | 2012-03-27 | Nellcor Puritan Bennett Llc | Medical sensor for reducing signal artifacts and technique for using the same |
| US8219170B2 (en) | 2006-09-20 | 2012-07-10 | Nellcor Puritan Bennett Llc | System and method for practicing spectrophotometry using light emitting nanostructure devices |
| US8396527B2 (en) | 2006-09-22 | 2013-03-12 | Covidien Lp | Medical sensor for reducing signal artifacts and technique for using the same |
| US8175671B2 (en) | 2006-09-22 | 2012-05-08 | Nellcor Puritan Bennett Llc | Medical sensor for reducing signal artifacts and technique for using the same |
| US8195264B2 (en) | 2006-09-22 | 2012-06-05 | Nellcor Puritan Bennett Llc | Medical sensor for reducing signal artifacts and technique for using the same |
| US7869849B2 (en) | 2006-09-26 | 2011-01-11 | Nellcor Puritan Bennett Llc | Opaque, electrically nonconductive region on a medical sensor |
| US7574245B2 (en) | 2006-09-27 | 2009-08-11 | Nellcor Puritan Bennett Llc | Flexible medical sensor enclosure |
| US7796403B2 (en) | 2006-09-28 | 2010-09-14 | Nellcor Puritan Bennett Llc | Means for mechanical registration and mechanical-electrical coupling of a faraday shield to a photodetector and an electrical circuit |
| US7890153B2 (en) | 2006-09-28 | 2011-02-15 | Nellcor Puritan Bennett Llc | System and method for mitigating interference in pulse oximetry |
| US8175667B2 (en) | 2006-09-29 | 2012-05-08 | Nellcor Puritan Bennett Llc | Symmetric LED array for pulse oximetry |
| US7680522B2 (en) | 2006-09-29 | 2010-03-16 | Nellcor Puritan Bennett Llc | Method and apparatus for detecting misapplied sensors |
| US7684842B2 (en) | 2006-09-29 | 2010-03-23 | Nellcor Puritan Bennett Llc | System and method for preventing sensor misuse |
| US8068891B2 (en) | 2006-09-29 | 2011-11-29 | Nellcor Puritan Bennett Llc | Symmetric LED array for pulse oximetry |
| US7476131B2 (en) | 2006-09-29 | 2009-01-13 | Nellcor Puritan Bennett Llc | Device for reducing crosstalk |
| US8265724B2 (en) | 2007-03-09 | 2012-09-11 | Nellcor Puritan Bennett Llc | Cancellation of light shunting |
| US7894869B2 (en) | 2007-03-09 | 2011-02-22 | Nellcor Puritan Bennett Llc | Multiple configuration medical sensor and technique for using the same |
| US8280469B2 (en) | 2007-03-09 | 2012-10-02 | Nellcor Puritan Bennett Llc | Method for detection of aberrant tissue spectra |
| EP2139383B1 (en) | 2007-03-27 | 2013-02-13 | Masimo Laboratories, Inc. | Multiple wavelength optical sensor |
| US8374665B2 (en) | 2007-04-21 | 2013-02-12 | Cercacor Laboratories, Inc. | Tissue profile wellness monitor |
| US8346328B2 (en) | 2007-12-21 | 2013-01-01 | Covidien Lp | Medical sensor and technique for using the same |
| US8352004B2 (en) | 2007-12-21 | 2013-01-08 | Covidien Lp | Medical sensor and technique for using the same |
| US8366613B2 (en) | 2007-12-26 | 2013-02-05 | Covidien Lp | LED drive circuit for pulse oximetry and method for using same |
| US8577434B2 (en) | 2007-12-27 | 2013-11-05 | Covidien Lp | Coaxial LED light sources |
| US8452364B2 (en) | 2007-12-28 | 2013-05-28 | Covidien LLP | System and method for attaching a sensor to a patient's skin |
| US8442608B2 (en) | 2007-12-28 | 2013-05-14 | Covidien Lp | System and method for estimating physiological parameters by deconvolving artifacts |
| US8897850B2 (en) | 2007-12-31 | 2014-11-25 | Covidien Lp | Sensor with integrated living hinge and spring |
| US8070508B2 (en) | 2007-12-31 | 2011-12-06 | Nellcor Puritan Bennett Llc | Method and apparatus for aligning and securing a cable strain relief |
| US8199007B2 (en) | 2007-12-31 | 2012-06-12 | Nellcor Puritan Bennett Llc | Flex circuit snap track for a biometric sensor |
| US8092993B2 (en) | 2007-12-31 | 2012-01-10 | Nellcor Puritan Bennett Llc | Hydrogel thin film for use as a biosensor |
| US9560994B2 (en) | 2008-03-26 | 2017-02-07 | Covidien Lp | Pulse oximeter with adaptive power conservation |
| US8437822B2 (en) | 2008-03-28 | 2013-05-07 | Covidien Lp | System and method for estimating blood analyte concentration |
| US8112375B2 (en) | 2008-03-31 | 2012-02-07 | Nellcor Puritan Bennett Llc | Wavelength selection and outlier detection in reduced rank linear models |
| US7887345B2 (en) | 2008-06-30 | 2011-02-15 | Nellcor Puritan Bennett Llc | Single use connector for pulse oximetry sensors |
| US8071935B2 (en) | 2008-06-30 | 2011-12-06 | Nellcor Puritan Bennett Llc | Optical detector with an overmolded faraday shield |
| US7880884B2 (en) | 2008-06-30 | 2011-02-01 | Nellcor Puritan Bennett Llc | System and method for coating and shielding electronic sensor components |
| US8577431B2 (en) | 2008-07-03 | 2013-11-05 | Cercacor Laboratories, Inc. | Noise shielding for a noninvasive device |
| US20100030040A1 (en) | 2008-08-04 | 2010-02-04 | Masimo Laboratories, Inc. | Multi-stream data collection system for noninvasive measurement of blood constituents |
| US8364220B2 (en) | 2008-09-25 | 2013-01-29 | Covidien Lp | Medical sensor and technique for using the same |
| US8417309B2 (en) | 2008-09-30 | 2013-04-09 | Covidien Lp | Medical sensor |
| US8423112B2 (en) | 2008-09-30 | 2013-04-16 | Covidien Lp | Medical sensor and technique for using the same |
| US8914088B2 (en) | 2008-09-30 | 2014-12-16 | Covidien Lp | Medical sensor and technique for using the same |
| US8452366B2 (en) | 2009-03-16 | 2013-05-28 | Covidien Lp | Medical monitoring device with flexible circuitry |
| US8221319B2 (en) | 2009-03-25 | 2012-07-17 | Nellcor Puritan Bennett Llc | Medical device for assessing intravascular blood volume and technique for using the same |
| US8509869B2 (en) | 2009-05-15 | 2013-08-13 | Covidien Lp | Method and apparatus for detecting and analyzing variations in a physiologic parameter |
| US8634891B2 (en) | 2009-05-20 | 2014-01-21 | Covidien Lp | Method and system for self regulation of sensor component contact pressure |
| US9010634B2 (en) | 2009-06-30 | 2015-04-21 | Covidien Lp | System and method for linking patient data to a patient and providing sensor quality assurance |
| US8505821B2 (en) | 2009-06-30 | 2013-08-13 | Covidien Lp | System and method for providing sensor quality assurance |
| US8311601B2 (en) | 2009-06-30 | 2012-11-13 | Nellcor Puritan Bennett Llc | Reflectance and/or transmissive pulse oximeter |
| US8391941B2 (en) | 2009-07-17 | 2013-03-05 | Covidien Lp | System and method for memory switching for multiple configuration medical sensor |
| US8417310B2 (en) | 2009-08-10 | 2013-04-09 | Covidien Lp | Digital switching in multi-site sensor |
| US8428675B2 (en) | 2009-08-19 | 2013-04-23 | Covidien Lp | Nanofiber adhesives used in medical devices |
| US9839381B1 (en) | 2009-11-24 | 2017-12-12 | Cercacor Laboratories, Inc. | Physiological measurement system with automatic wavelength adjustment |
| GB2487882B (en) | 2009-12-04 | 2017-03-29 | Masimo Corp | Calibration for multi-stage physiological monitors |
| US9241643B2 (en) | 2012-05-31 | 2016-01-26 | Covidien Lp | Methods and systems for power optimization in a medical device |
| US9241676B2 (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 |
| US20150289791A1 (en) * | 2014-04-11 | 2015-10-15 | Colin Rhodes Marcus | Pulse Oximeter Using Burst Sampling |
| US9743868B2 (en) * | 2014-11-20 | 2017-08-29 | Qualcomm Incorporated | Circuitry to allow low current operation of a device capable of determining a blood property |
| US20180360359A1 (en) * | 2017-06-14 | 2018-12-20 | Analog Devices Global | Systems and Methods for Measuring Oxygen in a Patient's Bloodstream |
| US10680454B2 (en) * | 2018-06-04 | 2020-06-09 | Simplex Quantum Inc. | Power supply circuit for biological signal measurement circuit and biological signal measuring apparatus |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5190038A (en) * | 1989-11-01 | 1993-03-02 | Novametrix Medical Systems, Inc. | Pulse oximeter with improved accuracy and response time |
| US5995855A (en) * | 1998-02-11 | 1999-11-30 | Masimo Corporation | Pulse oximetry sensor adapter |
| JP3165983B2 (en) * | 1992-06-15 | 2001-05-14 | 日本光電工業株式会社 | Light emitting element driving device for pulse oximeter |
| US5697367A (en) * | 1994-10-14 | 1997-12-16 | Somanetics Corporation | Specially grounded sensor for clinical spectrophotometric procedures |
| US5974338A (en) * | 1997-04-15 | 1999-10-26 | Toa Medical Electronics Co., Ltd. | Non-invasive blood analyzer |
| US6028694A (en) * | 1997-05-22 | 2000-02-22 | Schmidt; Gregory W. | Illumination device using pulse width modulation of a LED |
| US5983122A (en) * | 1997-12-12 | 1999-11-09 | Ohmeda Inc. | Apparatus and method for improved photoplethysmographic monitoring of multiple hemoglobin species using emitters having optimized center wavelengths |
-
1999
- 1999-05-26 US US09/320,145 patent/US6226539B1/en not_active Expired - Lifetime
-
2000
- 2000-04-04 CA CA002374144A patent/CA2374144A1/en not_active Abandoned
- 2000-04-04 WO PCT/US2000/008870 patent/WO2000072749A1/en active Application Filing
- 2000-04-04 JP JP2000620865A patent/JP4641626B2/en not_active Expired - Fee Related
- 2000-04-04 EP EP00921640A patent/EP1180961A4/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| JP2003500147A (en) | 2003-01-07 |
| EP1180961A1 (en) | 2002-02-27 |
| US6226539B1 (en) | 2001-05-01 |
| WO2000072749A1 (en) | 2000-12-07 |
| JP4641626B2 (en) | 2011-03-02 |
| EP1180961A4 (en) | 2004-11-24 |
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| EEER | Examination request | ||
| FZDE | Discontinued |