LED control utilizing ambient light or signal quality
First Claim
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1. A device for measuring oxygen saturation, the device comprising:
- a sensor having a light emitter and having a detector configured to provide an output corresponding to an optical property of tissue using light from the emitter;
an integration amplifier coupled to the sensor, the integration amplifier having a controllable integration time;
a processor coupled to the sensor and configured to determine a value corresponding to a signal to noise ratio for the output and configured to compare the value with a threshold and further wherein the processor is configured to compensate for ambient light using a plurality of operational states for the sensor, and wherein the operational states include a first state in which a first light of the emitter is powered on, a second state in which a second light of the emitter is powered on, and a third state in which the first light and the second light are powered off, and wherein the value is determined based on measurements during the first state, the second state and the third state; and
a control unit coupled to the processor and coupled to the integration amplifier, the control unit configured to adjust power supplied to the sensor based on the comparison and control the integration time based on the comparison, wherein controlling the integration time based on the comparison comprises incrementally increasing the integration time when the integration time is less than a maximum time period and incrementally decreasing the integration time when the integration time is greater than a minimum time period.
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Abstract
A system and method for controlling a light emitting device for an optical sensor based on signal quality and/or power consumption requirements. Drive current and/or integration time is controlled as a function of detected ambient light or signal quality. As the signal quality decreases the drive current or integration time can be adjusted to provide a more usable signal. If after some criteria for reduction, such as “time on” or high signal quality, then the drive current can be decreased.
14 Citations
34 Claims
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1. A device for measuring oxygen saturation, the device comprising:
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a sensor having a light emitter and having a detector configured to provide an output corresponding to an optical property of tissue using light from the emitter; an integration amplifier coupled to the sensor, the integration amplifier having a controllable integration time; a processor coupled to the sensor and configured to determine a value corresponding to a signal to noise ratio for the output and configured to compare the value with a threshold and further wherein the processor is configured to compensate for ambient light using a plurality of operational states for the sensor, and wherein the operational states include a first state in which a first light of the emitter is powered on, a second state in which a second light of the emitter is powered on, and a third state in which the first light and the second light are powered off, and wherein the value is determined based on measurements during the first state, the second state and the third state; and a control unit coupled to the processor and coupled to the integration amplifier, the control unit configured to adjust power supplied to the sensor based on the comparison and control the integration time based on the comparison, wherein controlling the integration time based on the comparison comprises incrementally increasing the integration time when the integration time is less than a maximum time period and incrementally decreasing the integration time when the integration time is greater than a minimum time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for measuring oxygen saturation, the method comprising:
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emitting light from a device having a sensor, the device configured to measure a parameter of a tissue using an optical property of the tissue, the light emitted from an emitter of the sensor; measuring a light signal using a detector of the sensor, the light signal corresponding to the emitted light; using a processor to determine a value corresponding to a signal to noise ratio for the light signal, wherein the processor is configured to compensate for ambient light using a plurality of operational states for the sensor, and wherein the operational states include a first state in which a first light of the emitter is powered on, a second state in which a second light of the emitter is powered on, and a third state in which the first light and the second light are powered off, and wherein the value is determined based on measurements during the first state, the second state and the third state; comparing the value with a threshold; and adjusting power consumption of the device based on the comparison and adjusting an integration time of an integration amplifier of the device, wherein adjusting the integration time based on the comparison comprises incrementally increasing the integration time when the integration time is less than a maximum time period and incrementally decreasing the integration time when the integration time is greater than a minimum time period. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A system comprising:
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an emitter configured to emit light; a detector coupled to an integration amplifier and configured to provide an output corresponding to a measured light signal based on an optical property of tissue and the emitted light, the integration amplifier having a controllable integration time, the emitter and the detector defining a sensor; a processor coupled to the detector and configured to determine a value corresponding to a measure of quality of the light signal and configured to compare the value with a threshold, wherein the processor is configured to compensate for ambient light using a plurality of operational states for the sensor, and wherein the operational states include a first state in which a first light of the emitter is powered on, a second state in which a second light of the emitter is powered on, and a third state in which the first light and the second light are powered off, and wherein the value is determined based on measurements during the first state, the second state and the third state; and a control unit coupled to the integration amplifier and configured to adjust power consumption based on the comparison and configured to control the integration time based on the comparison, wherein controlling the integration time based on the comparison comprises incrementally increasing the integration time when the integration time is less than a maximum time period and incrementally decreasing the integration time when the integration time is greater than a minimum time period. - View Dependent Claims (24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification