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公开(公告)号：AU2005216973A1
公开(公告)日：2005-09-09
申请号：AU2005216973
申请日：2005-02-25
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , CHEW BRADFORD B , PETERSEN ETHAN
Abstract: An apparatus and method for determining if a forward voltage of an LED in a pulse oximeter is within a predetermined range. This is accomplished by measuring the current through the LED, and also by knowing the duty cycle of the pulse width modulator (PWM) drive signal to the LED.
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公开(公告)号：AU2005216956A1
公开(公告)日：2005-09-09
申请号：AU2005216956
申请日：2005-02-24
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , CHEW BRADFORD B , PETERSEN ETHAN
Abstract: 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.
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Patent Agency Ranking
公开(公告)号：AU2005216985A1
公开(公告)日：2005-09-09
申请号：AU2005216985
申请日：2005-02-24
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , PETERSEN ETHAN , CHEW BRADFORD B
Abstract: 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.
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公开(公告)号：AU2005216981A1
公开(公告)日：2005-09-09
申请号：AU2005216981
申请日：2005-02-24
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , CHEW BRADFORD B , PETERSEN ETHAN
IPC: A61B5/00
Abstract: 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.
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公开(公告)号：AU2005216975A1
公开(公告)日：2005-09-09
申请号：AU2005216975
申请日：2005-02-25
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , PETERSEN ETHAN , CHEW BRADFORD B
IPC: A61B5/00
Abstract: 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 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 other embodiment, a dual core closed bobbin shielded inductor is used.
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公开(公告)号：AU2005216974A1
公开(公告)日：2005-09-09
申请号：AU2005216974
申请日：2005-02-25
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： SHEA WILLIAM , PETERSEN ETHAN , CHEW BRADFORD B
IPC: A61B5/00
Abstract: 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.
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公开(公告)号：AU2005216959A1
公开(公告)日：2005-09-09
申请号：AU2005216959
申请日：2005-02-24
Applicant: NELLCOR PURITAN BENNETT INCORPORATED
Inventor： PETERSEN ETHAN , CHEW BRADFORD B , SHEA WILLIAM
Abstract: 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.
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