Low-Power Optical Measurement with Adaptive PPG LED Control
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Solution Overview
Problem
Wearable devices consume excessive power due to constant operation of light sources like LEDs, leading to inaccurate physiological data readings and reduced battery life, especially when alternative light sources create uncontrolled optical interfaces.
Innovation Solution
Adjust the power output of LEDs based on real-time signal quality metrics using ambient light as an additional or alternative source, dynamically optimizing LED power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light sources operate at constant power levels, then physiological data collection is maintained, but battery life is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from constant power operation to dynamic power adjustment. The light source controller continuously monitors signal quality metrics and adjusts the light source power level in real-time, making the system adaptive to changing measurement conditions. This resolves the contradiction by maintaining reliable data collection when needed while reducing power consumption when alternative light sources suffice.
Solution Approach 2:
The patent changes the power parameter of the light source based on signal quality metrics. By monitoring parameters such as signal strength, noise levels, and quality indicators, the system adjusts the light source power level accordingly. This parameter change strategy allows the system to maintain data collection reliability when high-quality measurements are required while extending battery life when ambient light provides sufficient signal quality.
2Reliability
If light sources operate at constant power levels, then physiological data collection is maintained, but power consumption increases
Solution Approach 1:
The patent implements feedback control by continuously monitoring signal quality metrics from the photodetector and using this information to adjust light source power levels. The feedback loop compares current signal quality against thresholds and adjusts power consumption accordingly, maintaining reliable data collection while optimizing energy usage based on actual measurement needs rather than operating at constant high power.
Solution Approach 2:
The system transitions from static constant power operation to dynamic power adjustment based on real-time signal quality assessment. The light source controller dynamically modifies power levels in response to changing environmental conditions and measurement requirements, resolving the contradiction between maintaining reliable data collection and reducing overall power consumption.
3Use of energy by moving object
If ambient light is used as alternative source, then power consumption is reduced, but optical interface control is lost
Solution Approach 1:
The patent introduces a light source controller as an intermediary that coordinates between the light source, photodetector, and signal quality metrics. This intermediary manages the optical interface by adjusting light source characteristics based on signal quality feedback, enabling the system to use ambient light when appropriate while maintaining control over measurement quality through active management of the optical interface conditions.
Solution Approach 2:
The system changes optical interface parameters such as light source power level, wavelength, and intensity based on signal quality metrics. By dynamically adjusting these parameters, the system maintains control over the optical interface even when using ambient light sources, resolving the contradiction between power reduction and control retention.
4Duration of action of moving object
If LED power is dynamically adjusted, then battery life is extended, but measurement accuracy may be affected
Solution Approach 1:
The patent uses feedback control to monitor signal quality metrics in real-time and adjust LED power levels accordingly. The feedback loop ensures that measurement precision is maintained by detecting when signal quality degrades and responding by increasing light source power, while extending battery life by reducing power when signal quality is sufficient. This resolves the contradiction by making measurement precision a controlled variable rather than a fixed constraint.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances measurement accuracy while reducing power consumption, thereby extending battery life and improving data reliability.
Implementation Method 1
a photodetector (PD) to measure a photoplethysmogram (PPG) signal
Implementation Method 2
The light sources of a wearable device (e.g., LEDs or the like)
Data Source
AI summary
Methods, systems, and devices for adjusting a power output level of a light source on a wearable device are described. A photodetector on the wearable device may measure a first photoplethysmography (PPG) signal derived from an ambient light source that is powered externally to the wearable device. The wearable device may calculate a quality metric of the first PPG signal based on measuring the first PPG signal. The wearable device may adjust the power output level of the light source powered by the wearable device based on the quality metric of the first PPG signal.