Polarized Light Wearing Detection for Wearable Biosignals
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Solution Overview
Problem
Existing wearing detection technologies for electronic devices, particularly wearable devices, are ineffective during intense user movement and loose wear states, often mistakenly detecting non-living objects and generating noise during vigorous exercise, leading to inaccurate biosignal measurements.
Innovation Solution
An electronic device equipped with LEDs emitting light of specific polarization directions and photodiodes with applied polarizers, allowing for precise determination of wearing information based on luminous intensity differences, effectively distinguishing between reflection and absorption of light by a living object.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PPG sensor uses a green LED to measure biosignal, then a stable signal is obtained even with user movement, but skin permeability is relatively low resulting in weak signal intensity
Solution Approach 1:
The patent changes the polarization state parameter of light to resolve the contradiction. By using polarized light from the green LED and detecting it with polarizers at different orientations, the system maintains signal stability while improving signal intensity and skin permeability measurement capability
2Use of energy by moving object
If a PPG sensor uses a red LED or infrared LED to measure biosignal, then skin permeability is relatively high, but the measured signal is weak and susceptible to user movement
Solution Approach 1:
The patent applies polarization parameter changes to enhance the performance of red or infrared LEDs. By incorporating polarizers and detecting polarized light, the system achieves both high signal intensity from the LEDs and movement-resistant signal stability
3Measurement precision
If wearing detection is performed using light reflection from object surface, then wearing on living objects can be detected, but false detection occurs on non-living objects such as bananas or teddy bears
Solution Approach 1:
The patent uses polarization state as an additional detection parameter. Living objects alter the polarization state of reflected light differently than non-living objects, enabling the system to distinguish between them and eliminate false detections while maintaining wearing detection accuracy
4Reliability
If wearing detection is performed using typical optical methods, then detection can be performed, but detection fails during intense user movement and loose wear states
Solution Approach 1:
The patent introduces polarization state measurement as an additional parameter to traditional optical detection. This enables the system to maintain both detection reliability during movement and loose wear, and measurement precision for wearing state determination
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 solution enables continuous and stable wearing detection, even during user movement and loose wear, while accurately measuring biosignals by selectively using photodiodes with appropriate polarizers, reducing noise and improving measurement precision.
Implementation Method 1
An electronic device equipped with LEDs emitting light of specific polarization directions and photodiodes with applied polarizers, allowing for precise determination of wearing information based on luminous intensity differences
Data Source
AI summary
An electronic device is provided. The electronic device includes a lighting-emitting diode (LED) module configured to emit light of a first polarization direction, a first photodiode configured to receive the light emitted from the LED module through a first polarizer having the first polarization direction, a second photodiode configured to receive the light emitted from the LED module through a second polarizer having a second polarization direction perpendicular to the first polarization direction, and a processor configured to determine wearing information of the electronic device based on luminous intensity of light sensed from each of the first photodiode and the second photodiode.