Heart Rate Sensor Array Using Multi-Wavelength Light for Motion Noise Reduction
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Solution Overview
Problem
Current PPG systems have insufficient dynamic range due to single pixel usage, leading to high signal-to-noise ratio and decreased detection accuracy in heart rate monitoring.
Innovation Solution
A heart rate detecting module incorporating a CMOS sensor array and processor to generate displacement information of light intensity gravity centers and calculate light intensity variance, utilizing multiple light sources and wavelengths to enhance dynamic range and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pixel is used in the PPG system, then the device complexity is reduced, but the dynamic range is insufficient and detection accuracy decreases
Solution Approach 1:
The patent divides the detection function into multiple pixels arranged in an array, where each pixel detects light intensity at a specific location. This segmentation allows the system to capture spatial variations in light absorption while maintaining manageable device complexity through standardized pixel architecture.
Solution Approach 2:
The patent transitions from single-point detection to two-dimensional spatial detection by arranging pixels in an array. This dimensional expansion enables the system to capture both temporal heart rate variations and spatial distribution patterns, significantly improving dynamic range and detection accuracy.
2Device complexity
If a single pixel is used in the PPG system, then the structure is simplified, but the signal-to-noise ratio is high and detection accuracy decreases
Solution Approach 1:
The patent combines the detection outputs from multiple pixels to generate a composite signal. By merging individual pixel signals that each contain noise, the system achieves noise cancellation through statistical averaging, improving the overall signal-to-noise ratio while maintaining relatively simple individual pixel structures.
Solution Approach 2:
The patent uses multiple identical or similar pixel units arranged in an array, where each pixel serves as a copy of the detection function. This replication allows the system to obtain multiple independent measurements that can be processed to eliminate noise, improving reliability without requiring complex individual pixel designs.
3Measurement precision
If multiple light wavelengths are used, then the dynamic range is improved, but the device complexity increases
Solution Approach 1:
The patent implements multiple light sources emitting different wavelengths (e.g., red and infrared) to illuminate the skin simultaneously or sequentially. Each wavelength provides complementary information about blood volume changes, expanding the dynamic range of detection. The same pixel array handles all wavelengths, avoiding the need for separate detection systems for each wavelength.
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 reduces noise interference and improves detection accuracy by providing a broad dynamic range and two-dimensional displacement data, resulting in more precise heart rate measurements.
Implementation Method 1
a PPG (photoplethysmogram) system is used to detect the heart rate according to the light brightness (light absorption) using a pulse oximeter which illuminates the skin and measures the changes in light absorption
Implementation Method 2
measures the changes in light absorption when the heart contracts that has the maximum peripheral blood volume and light absorption
Data Source
AI summary
This instant disclosure provides a heart rate detecting device which includes an image sensor. The image sensor generates a first mixed signal within a first interval and generates a second mixed signal within a second interval, wherein the first mixed signal contains light information of first multiple light wavelengths having a first intensity ratio from one another, and the second mixed signal contains light information of second multiple light wavelengths having a second intensity ratio, different from the first intensity ratio, from one another.