Methods and systems for providing power to light sources of a physiological monitor

Patent metadata

Field	Value
Publication number	US-2016081602-A1
Application number	US-201514857710-A
Country	US
Kind code	A1
Filing date	Sep 17, 2015
Priority date	Sep 18, 2014
Publication date	Mar 24, 2016
Grant date	—

Abstract

Systems and methods for providing power to a light source of a physiological system and for generating a desired signal. The physiological system may comprise a light drive circuit that may provide a digital signal to the light source of the physiological system. The digital signal may comprise a plurality of pulses. The plurality of pulses may include one or more features that may be adjustable to vary the power provided to the light source. For example, the pulses may have a varying width. The light drive circuit may be configured to provide power to the light source during each pulse of the plurality of pulses. The system may further comprise a front end circuit configured to receive the light generated by the light source in response to the plurality of pulses, where the light is attenuated by a body tissue of a patient. The front end circuit may comprise a response time. The at least one period of the plurality of pulses may be substantially shorter than the response time of the front end channel circuit.

First claim

1 . A photoplethysmography (PPG) system, the system comprising:
a light drive circuit configured to provide a digital signal that provides power to a light source, the digital signal comprising a plurality of pulses, wherein at least one feature of the plurality of pulses is adjustable to vary the power provided to the light source, the light drive circuit being further configured to provide power to the light source during each pulse of the plurality of pulses, and wherein the plurality of pulses comprises one or more periods; a front end channel circuit configured to receive light generated by the light source in response to the plurality of pulses after the light has been attenuated by a body tissue, wherein the front end channel circuit comprises a response time; and wherein the one or more periods of the plurality of pulses are substantially shorter than the response time of the front end channel circuit.

2 . The system of claim 1 , wherein the at least one adjustable feature of the plurality of pulses comprises at least one of a width of the plurality of pulses, a frequency of the plurality of pulses, a density of the plurality of pulses, an amplitude of the plurality of pulses, a position of the plurality of pulses, and pulse code of the plurality of pulses.

3 . The system of claim 1 , wherein the light drive circuit is further configured to provide no power or reduced of power to the light source during intervals between the plurality of pulses.

4 . The system of claim 1 , wherein the power provided by the light drive circuit comprises at least one of fixed voltage and fixed current during each pulse of the plurality of pulses.

5 . The system of claim 1 , wherein the front end channel circuit is further configured to integrate the received light to generate a desired analog pulse.

6 . The system of claim 5 , wherein the desired analog pulse comprises at least one of a sinusoidal wave and a shaped square wave.

7 . The system of claim 1 , wherein the light drive signal comprises pulses that are dithered with respect to the at least one adjustable feature.

8 . The system of claim 1 , wherein the light source comprises two LEDs in a back-to-back configuration.

9 . The system of claim 8 , wherein the light drive circuit comprises a plurality of transistors in an H-bridge configuration, such that the light drive circuit is capable of separately providing power to each of the two LEDs.

10 . The system of claim 1 , wherein the light drive circuit comprises at least one of a buck regulator, a linear regulator, a boost regulator, a buck/boost regulator, a charge pump, and a low-dropout regulator for varying the power provided to the light source.

11 . The system of claim 1 , wherein a pulse skipping template is applied to the digital signal.

12 . A photoplethysmography (PPG) system, the system comprising:
a light drive configured to provide a digital signal that provides power to a light source, the digital signal comprising a plurality of pulses, the light drive being further configured to provide power to the light source during each pulse of the plurality of pulses; and a front end channel configured to receive pulses of light generated by the light source in response to the plurality of pulses of the digital signal, the pulses of light being attenuated by a body tissue, and wherein the front end channel is further configured to integrate the pulses of light to generate a desired analog pulse.

13 . The system of claim 12 wherein the plurality of pulses of the digital signal comprises at least one adjustable feature to vary the power provided to the light source, and wherein the pulses of light comprise one or more periods, and wherein the front end channel comprises a response time, and wherein the one or more periods of the pulses of light are substantially shorter than the response time of the front end channel.

14 . The system of claim 13 , wherein the adjustable feature of the plurality of pulses of the digital signal comprises at least one of a width of the plurality of digital pulses, a frequency of the plurality of digital pulses, a density of the plurality of digital pulses, an amplitude of the plurality of digital pulses, a position of the plurality of digital pulses, and a pulse code of the plurality of digital pulses.

15 . A method for providing power to a light source of a photoplethysmography (PPG) device, the method comprising:
providing power to the light source according to a digital signal, the digital signal comprising a plurality of pulses, wherein at least one feature of the plurality of pulses is adjustable to vary the power provided to the light source, wherein the power is provided to the light source during each pulse of the plurality of pulses, and wherein the plurality of pulses comprises one or more periods; receiving, by a front end channel of the PPG device, light generated by the light source in response to the plurality of pulses after the light has been attenuated by a body tissue, wherein the front end channel comprises a response time, and wherein the one or more periods of the plurality of pulses are substantially shorter than the response time of the front end channel.

16 . The method of claim 15 , wherein the at least one adjustable feature of the plurality of pulses comprises at least one of a width of the plurality of pulses, a frequency of the plurality of pulses, a density of the plurality of pulses, an amplitude of the plurality of pulses, a position of the plurality of pulses, and a pulse code of the plurality of pulses.

17 . The method of claim 15 , further comprising integrating the light received by the front end channel to generate a desired analog pulse.

18 . A method for providing power to a light source of a photoplethysmography (PPG) device, the method comprising:
providing a digital signal that provides power to the light source, the signal comprising a plurality of pulses, wherein the power is provided to the light source during each pulse of the plurality of pulses; receiving, by a front end channel of the PPG device, pulses of light generated by the light source in response to the plurality of pulses of the digital signal, the pulses of light being attenuated by a body tissue; and integrating the pulses of light to generate a desired analog pulse.

19 . The method of claim 18 wherein the plurality of pulses of the digital signal comprises at least one adjustable feature to vary the power provided to the light source, wherein the pulses of light comprise one or more periods, and wherein the front end channel comprises a response time, and wherein the one or more periods of the pulses of light are substantially shorter than the response time of the front end channel.

20 . The method of claim 19 , wherein the adjustable feature of the plurality of pulses of the digital signal comprises at least one of a width of the plurality of digital pulses, a frequency of the plurality of digital pulses, a density of the plurality of digital pulses, an amplitude of the plurality of digital pulses, a position of the plurality of digital pulses and a pulse code of the plurality of digital pulses.

21 - 40 . (canceled)

Assignees

• Covidien Lp

Inventors

• Lisogurki Daniel
• Meehan Christopher
• Dean William Kit

Classifications

• A61B5/14551 Primary

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• A61B5/6898

  Portable consumer electronic devices, e.g. music players, telephones, tablet computers · CPC title

• A61B5/7228

  Signal modulation applied to the input signal sent to patient or subject; Demodulation to recover the physiological signal · CPC title

• A61B5/742

  using visual displays (displays for heart-related electrical signals, e.g. ECG, A61B5/339) · CPC title

• A61B5/7475

  User input or interface means, e.g. keyboard, pointing device, joystick · CPC title