Wearable PPG Sensor Layout for Wireless Charging Compatibility
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Solution Overview
Problem
Current smart wearable devices face limitations in heart rate detection accuracy due to the compact layout of photoplethysmograph (PPG) systems, which restricts modulation depth and compatibility with wireless charging functions.
Innovation Solution
The smart wearable device arranges light emitting and measuring parts into a polygon configuration, increasing the distance between them to enhance modulation depth and accommodates additional devices at the central position, such as a wireless charging coil or electrocardiograph electrode, to improve detection accuracy and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a straight-line single-PD solution is used with PD in the middle and LEDs at both sides, then the layout is compact and light utilization is highly efficient, but the distance between LEDs and PD is excessively small leading to insufficient modulation depth and conflict with wireless charging function design
Solution Approach 1:
The patent transitions from a one-dimensional straight-line arrangement to a two-dimensional polygonal arrangement of LEDs and PDs. By distributing multiple LEDs and PDs around the periphery of a polygon rather than lining them up, the design increases the effective distance between light sources and detectors while maintaining compact overall footprint, thereby improving modulation depth without sacrificing layout efficiency
Solution Approach 2:
The patent divides the single-PD configuration into multiple PDs distributed around the polygon periphery, with multiple LEDs similarly distributed. This segmentation allows each PD to receive light from its corresponding LED at an optimized distance, improving individual measurement quality while the collective arrangement maintains compactness
2Use of energy by moving object
If PD is disposed in the middle of the device, then light utilization is highly efficient, but the central position is occupied preventing accommodation of wireless charging coil or other devices
Solution Approach 1:
The patent redistributes PDs from a centralized middle position to a distributed peripheral arrangement around a polygon. This spatial reconfiguration frees the central region for wireless charging coils or other components while maintaining light detection functionality through the peripheral PDs that still receive reflected light from LEDs along the polygon edges
Solution Approach 2:
The polygonal periphery configuration serves multiple functions: it accommodates both the PPG light detection system (with LEDs and PDs arranged around the perimeter) and the wireless charging system (with coil in the center), allowing the device to perform both optical measurement and wireless charging operations simultaneously without functional conflict
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 configuration increases the accuracy of heart rate and blood oxygen detection results while allowing for efficient wireless charging and electrocardiograph measurement by optimizing the placement of components within the device.
Implementation Method 1
A basic principle of the reflective mode is: A light emitting diode (LED) emits light; the light is reflected by hemoglobin in a blood vessel inside a human tissue; and the reflected light is received by a photodiode (PD)
Implementation Method 2
the light is reflected by hemoglobin in a blood vessel inside a human tissue
Implementation Method 3
the wireless charging device includes an electromagnetic coil and a magnet
Data Source
AI summary
A smart wearable device includes a detection apparatus and a case, the detection apparatus specifically includes one set of measuring parts and a plurality of sets of light emitting parts; the one set of measuring parts and the plurality of sets of light emitting parts are inlaid into the case and arranged into a polygon, where each of the plurality of sets of light emitting parts and the one set of measuring parts each occupies one of a plurality of angles of the polygon, and a central position of the polygon is at a specified distance to each angle of the polygon. A specific embodiment of the present invention provides a smart wearable device. One set of measuring parts and a plurality of sets of light emitting parts are disposed into a case and arranged into a polygon.