Patents by Inventor Ethan Petersen
Ethan Petersen has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Publication number: 20090167205Abstract: In various embodiments, there is provided an LED drive circuit and a method for using the same. Specifically, the present disclosure is directed to an LED drive circuit for pulse oximeters. In an embodiment, the LED drive circuit includes a current mirror configured to provide drive current to an LED of a sensor. Additionally, the method includes providing current to first and second current mirrors, wherein the first and second current mirrors are configured to control first and second light sources.Type: ApplicationFiled: December 24, 2008Publication date: July 2, 2009Applicant: Nellcor Puritan Bennett LLCInventor: Ethan Petersen
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Publication number: 20090154573Abstract: A method for processing an analog composite signal in a system has the steps of receiving a composite signal with at least one first signal component and at least one interfering signal component; filtering the composite signal with a filter having a transfer function H(s); sampling the filtered composite signal in periodic intervals wherein each periodic interval has n samples; forming a matrix equation representing the composite signal wherein the matrix equation has a signal vector with the at least first one signal component and the at least one interfering signal component and a matrix comprising weighted coefficients; solving the matrix equation to determine the at least one signal component; outputting the at least one signal component.Type: ApplicationFiled: December 13, 2007Publication date: June 18, 2009Inventor: Ethan Petersen
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Publication number: 20090075248Abstract: This invention provides a novel methods and devices for measurement of particle concentration or changes in particle concentration over a wide linear range. The invention comprises one or more radiation sources and one or more detectors contained in a housing which is interfaced to a medium containing particulate matter. The one or more radiation sources are directed into the medium, scattered or transmitted by the particulate matter, and then some portion of the radiation is detected by the one or more detectors. Methods for confining the measurement to a specific volume within the medium are described. Algorithms are provided for combining the signals generated by multiple source-detector pairs in a manner that results in a wide linear range of response to changes in particle concentration. In one embodiment the sensor provides non-invasive measurements of biomass in a bioreactor. In another embodiment an immersible probe design is described, which may be suited for one-time use.Type: ApplicationFiled: July 28, 2008Publication date: March 19, 2009Inventors: Martin P. Debreczeny, Jaime Romero, Ethan Petersen
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Patent number: 7499740Abstract: Low power techniques for sensing cardiac pulses in a signal from a sensor are provided. A pulse detection block senses the sensor signal and determines its signal-to-noise ratio. After comparing the signal-to-noise ratio to a threshold, the drive current of light emitting elements in the sensor is dynamically adjusted to reduce power consumption while maintaining the signal-to-noise ratio at an adequate level. The signal component of the sensor signal can be measured by identifying systolic transitions. The systolic transitions are detected using a maximum and minimum derivative averaging scheme. The moving minimum and the moving maximum are compared to the scaled sum of the moving minimum and moving maximum to identify the systolic transitions. Once the signal component has been identified, the signal component is compared to a noise component to calculate the signal-to-noise ratio.Type: GrantFiled: January 8, 2007Date of Patent: March 3, 2009Assignee: Nellcor Puritan Bennett LLCInventors: Brad Nordstrom, William Shea, Ethan Petersen
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Publication number: 20090005662Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.Type: ApplicationFiled: July 14, 2008Publication date: January 1, 2009Applicant: Nellcor Puritan Bennett IncInventors: Ethan Petersen, William Shea, Bradford B. Chew
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Publication number: 20080221427Abstract: There is provided a system and method for canceling shunted light. The method includes transmitting electromagnetic radiation at tissue of interest and generating a signal representative of detected electromagnetic radiation. A portion of the generated signal representing shunted light is canceled from the generated signal and the remaining portion of the generated signal is used to compute physiological parameters.Type: ApplicationFiled: March 9, 2007Publication date: September 11, 2008Applicant: Nellcor Puritan Bennett LLCInventor: Ethan Petersen
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Patent number: 7400919Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.Type: GrantFiled: July 28, 2006Date of Patent: July 15, 2008Assignee: Nellcor Puritan Bennett LLCInventors: Ethan Petersen, William Shea, Bradford B. Chew
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Patent number: 7373192Abstract: A pulse oximeter with drive lines for driving red and IR LEDs, and a drive circuit for driving those drive lines. A processor controls the drive circuit using a red zero output line and an IR zero output line directly connected between the processor and the drive circuit. This allows a control signal to directly control the turning off of either the red or IR drive transistors to prevent forward current flow through the red and IR LEDs by overriding the ongoing programmable logic state machine control of the drive transistors. The effects of crosstalk and capacitive coupling are reduced as a result.Type: GrantFiled: February 25, 2004Date of Patent: May 13, 2008Assignee: Nellcor Puritan Bennett Inc.Inventors: Bradford B. Chew, Ethan Petersen, William Shea
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Patent number: 7355539Abstract: There is provided a pulse oximeter circuit including a feedback circuit configured to receive a digital output signal of a multi-bit sigma-delta modulator and generate a pulse width modulated signal (PWM). The PWM signal is directed to a first switching circuit and a D flip-flop. The first switching circuit provides a first or second reference voltage as a feedback signal to the multi-bit sigma-delta modulator. The D flip-flop generates a sample and hold signal. The sample and hold signal controls a second switching circuit coupled to the input of the multi-bit sigma-delta modulator.Type: GrantFiled: November 27, 2006Date of Patent: April 8, 2008Assignee: Nellcor Puritan Bennett Inc.Inventors: Ethan Petersen, William Shea, Bradford B. Chew
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Publication number: 20070208240Abstract: Low power techniques for sensing cardiac pulses in a signal from a sensor are provided. A pulse detection block senses the sensor signal and determines its signal-to-noise ratio. After comparing the signal-to-noise ratio to a threshold, the drive current of light emitting elements in the sensor is dynamically adjusted to reduce power consumption while maintaining the signal-to-noise ratio at an adequate level. The signal component of the sensor signal can be measured by identifying systolic transitions. The systolic transitions are detected using a maximum and minimum derivative averaging scheme. The moving minimum and the moving maximum are compared to the scaled sum of the moving minimum and moving maximum to identify the systolic transitions. Once the signal component has been identified, the signal component is compared to a noise component to calculate the signal-to-noise ratio.Type: ApplicationFiled: January 8, 2007Publication date: September 6, 2007Applicant: Nellcor Puritan Bennett Inc.Inventors: Brad Nordstrom, William Shea, Ethan Petersen
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Publication number: 20070132618Abstract: There is provided a pulse oximeter circuit including a feedback circuit configured to receive a digital output signal of a multi-bit sigma-delta modulator and generate a pulse width modulated signal (PWM). The PWM signal is directed to a first switching circuit and a D flip-flop. The first switching circuit provides a first or second reference voltage as a feedback signal to the multi-bit sigma-delta modulator. The D flip-flop generates a sample and hold signal. The sample and hold signal controls a second switching circuit coupled to the input of the multi-bit sigma-delta modulator.Type: ApplicationFiled: November 27, 2006Publication date: June 14, 2007Applicant: Nellcor Puritan Bennett Inc.Inventors: Ethan Petersen, William Shea, Bradford Chew
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Patent number: 7215985Abstract: A method and apparatus for reducing cross-talk in an oximeter. The oximeter includes a band pass filter. The amount of cross-talk through the band pass filter is estimated. Based on this estimate, the corner frequencies of the band pass filter are adjusted when it is designed to minimize the cross-talk. In one embodiment, a calibration mode is performed when a sensor is attached to the oximeter. In the calibration mode, the signals are measured with first only the red LED on and then with only the IR LED on. Any signal measured in the off channel is assumed to be a result of cross-talk from the other channel. The magnitude of the cross-talk is determined as a percentage, and subsequently the percentage is multiplied by the actual signal and subtracted from the other LED signal as cross-talk compensation.Type: GrantFiled: February 25, 2004Date of Patent: May 8, 2007Assignee: Nellcor Puritain Bennett Inc.Inventors: Ethan Petersen, Bradford B. Chew, William Shea
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Patent number: 7212847Abstract: A method and apparatus for providing a substantially real-time representation of an analog representation of a physiological signal is provided. The waveform signal from the sensor is converted into digital form. A delta-sigma modulator is used as a simple Digital-to-analog Converter (DAC). The output can then be provided through a simple hardware filter to give an analog output signal in nearly real-time, which can be used for other instruments, synchronization, display, etc.Type: GrantFiled: February 25, 2004Date of Patent: May 1, 2007Assignee: Nellcor Puritan Bennett LLCInventors: Ethan Petersen, William Shea, Bradford B. Chew
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Patent number: 7190985Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.Type: GrantFiled: February 25, 2004Date of Patent: March 13, 2007Assignee: Nellcor Puritan Bennett Inc.Inventors: Ethan Petersen, William Shea, Bradford B. Chew
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Patent number: 7162288Abstract: Low power techniques for sensing cardiac pulses in a signal from a sensor are provided. A pulse detection block senses the sensor signal and determines its signal-to-noise ratio. After comparing the signal-to-noise ratio to a threshold, the drive current of light emitting elements in the sensor is dynamically adjusted to reduce power consumption while maintaining the signal-to-noise ratio at an adequate level. The signal component of the sensor signal can be measured by identifying systolic transitions. The systolic transitions are detected using a maximum and minimum derivative averaging scheme. The moving minimum and the moving maximum are compared to the scaled sum of the moving minimum and moving maximum to identify the systolic transitions. Once the signal component has been identified, the signal component is compared to a noise component to calculate the signal-to-noise ratio.Type: GrantFiled: February 25, 2004Date of Patent: January 9, 2007Assignee: Nellcor Purtain Bennett IncorporatedInventors: Brad Nordstrom, William Shea, Ethan Petersen
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Patent number: 7142142Abstract: An oximeter uses a sigma-delta modulator and a multi-bit ADC with PWM feedback enabling high precision multi-bit conversion. Demodulation is done in software, thus requiring only a single hardware path for both red and IR. Multiple capacitors are switched into the integrator in the sigma-delta modulator, with different capacitors for red, IR and dark signals, thus enabling the use of the single hardware path. A switching circuit at the input of the sigma-delta modulator acts as a sample and hold, controlled by the PWM feedback.Type: GrantFiled: February 25, 2004Date of Patent: November 28, 2006Assignee: Nelicor Puritan Bennett, Inc.Inventors: Ethan Petersen, William Shea, Bradford B. Chew
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Publication number: 20060264721Abstract: A pulse oximeter method and apparatus which provides (1) a notch filter at a distance between a modulation frequency and a common multiple of commonly used power line frequencies (50, 60, 100 and 120) and also (2) a demodulation frequency greater than a highest pulse rate of a person and lower than any harmonic of 50, 60, 100 or 120 Hz, to filter ambient light interference, while choosing an optimum demodulation frequency that avoids interference from the notch filter or from harmonics of the line interference. Also, ambient light for any low frequency interference, such as power line interference, is measured both before and after each of the light emitter wavelengths and the average of the ambient light is then subtracted from the detected signal.Type: ApplicationFiled: July 28, 2006Publication date: November 23, 2006Applicant: Nellcor Puritan Bennett Incorporated a corporation of DelawareInventors: Ethan Petersen, William Shea, Bradford Chew
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Publication number: 20060264720Abstract: A light emitter drive circuit for an oximeter which utilizes a single inductor for driving multiple light emitters. The inductor is connected to a switching circuit to multiple energy storage circuits, such as capacitors. These are alternately charged up, using the same inductor. Subsequently, the capacitors are alternatively discharged for their corresponding light emitters through he same inductor. Also, the magnetic susceptibility of the LED drive circuit is reduced by using magnetic flux canceling in the inductor. In one embodiment, a toroidal inductor is used with geometric symmetry and its magnetic flux. In other embodiment, a dual core closed bobbin shielded inductor is used.Type: ApplicationFiled: July 26, 2006Publication date: November 23, 2006Applicant: Nellcor Puritan Bennett Incorporated a corporation of DelawareInventors: Bradford Chew, Ethan Petersen, William Shea
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Patent number: 7120479Abstract: A light emitter drive circuit for an oximeter which utilizes a single inductor for driving multiple light emitters. The inductor is connected to a switching circuit to multiple energy storage circuits, such as capacitors. These are alternately charged up, using the same inductor. Subsequently, the capacitors are alternately discharged for their corresponding light emitters through the same inductor. Also, the magnetic susceptibility of the LED drive circuit is reduced by using magnetic flux canceling in the inductor. In one embodiment, a toroidal inductor is used with geometric symmetry and its magnetic flux. In another embodiment, a dual core closed bobbin shielded inductor is used.Type: GrantFiled: February 25, 2004Date of Patent: October 10, 2006Assignee: Nellcor Puritan Bennett Inc.Inventors: Bradford B Chew, Ethan Petersen, William Shea
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Publication number: 20050187447Abstract: A light emitter drive circuit for an oximeter which utilizes a single inductor for driving multiple light emitters. The inductor is connected to a switching circuit to multiple energy storage circuits, such as capacitors. These are alternately charged up, using the same inductor. Subsequently, the capacitors are alternately discharged for their corresponding light emitters through the same inductor. Also, the magnetic susceptibility of the LED drive circuit is reduced by using magnetic flux canceling in the inductor. In one embodiment, a toroidal inductor is used with geometric symmetry and its magnetic flux. In another embodiment, a dual core closed bobbin shielded inductor is used.Type: ApplicationFiled: February 25, 2004Publication date: August 25, 2005Applicant: Nellcor Puritan Bennett Inc.Inventors: Bradford Chew, Ethan Petersen, William Shea