Optical Sensor Biosignal Measurement with Dynamic Light Control
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Solution Overview
Problem
Conventional portable biosignal measurement devices face challenges in accurately measuring photoplethysmography (PPG) signals due to interference from disturbance light, especially in outdoor environments, leading to amplified system noise and reduced signal quality.
Innovation Solution
An optical sensor biosignal measurement apparatus with a light quantity adjustment member, such as a diaphragm, polymer-dispersed liquid crystal (PDLC) unit, or liquid crystal display (LCD) unit, is used to dynamically adjust the optical transmission area of the photo detector based on detected light levels, reducing the impact of disturbance light and enhancing signal accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical transmission area of the photo detector is increased to detect weak PPG signals from body portions like earlobes, then the signal detection capability is improved, but the noise from disturbance light and motion is also amplified
Solution Approach 1:
The patent applies the dynamics principle by making the optical transmission area of the photo detector adjustable rather than fixed. The controller dynamically changes the optical transmission area based on detected light conditions: increasing the area when PPG signals are weak to improve detection capability, and decreasing the area when disturbance light is strong to reduce noise. This dynamic adjustment resolves the contradiction between signal detection capability and noise reduction.
2Measurement precision
If the quantity of light is increased to improve PPG signal strength, then the signal-to-noise ratio is improved, but the impact of disturbance light is also increased
Solution Approach 1:
The patent uses dynamics by dynamically adjusting the optical transmission area in response to varying light conditions. When the PPG signal is weak, the controller increases the optical transmission area to capture more light and improve the signal-to-noise ratio. When disturbance light becomes strong, the controller decreases the optical transmission area to limit the amount of interfering light entering the photo detector. This dynamic control strategy resolves the contradiction between improving signal strength and reducing disturbance light impact.
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
The solution effectively reduces noise from external light interference, allowing for more accurate and reliable biosignal measurement without time or location restrictions, improving the signal-to-noise ratio and maintaining measurement quality across varying light conditions.
Implementation Method 1
an optical sensor having a luminous element to emit light towards the skin of a user and a photo detector to detect light from the skin of the user
Implementation Method 2
a light quantity adjustment member to adjust an optical transmission area of the photo detector... a diaphragm, polymer-dispersed liquid crystal (PDLC) unit, or liquid crystal display (LCD) unit
Data Source
AI summary
An optical sensor biosignal measurement apparatus including an optical sensor having a luminous element to emit light towards the skin of a user and a photo detector to detect light from the skin of the user; a light quantity adjustment member to adjust an optical transmission area of the photo detector; and a light quantity controller to detect the quantity of light detected by the photo detector, and control the light quantity adjustment member to adjust the optical transmission area of the photo detector according to the quantity of light is provided.