PPG Terminal Multi-PD Delay Circuit Signal Quality
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Solution Overview
Problem
Current PPG terminals face challenges in accurately collecting health status data due to poor signal quality, especially in scenarios where the photo diode (PD) cannot be in full contact with the skin.
Innovation Solution
The terminal employs a plurality of PDs and a delay circuit to obtain a target signal with good quality, allowing for accurate determination of human health status. The delay circuit performs delay processing on one electrical signal, enabling the AFE chip to select independent electrical signals for better signal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single PD is used to collect PPG signals, then the device structure is simple, but the signal quality deteriorates when the PD cannot be in full contact with the skin
Solution Approach 1:
The patent divides the single PD into multiple PDs (first PD and second PD) that work in parallel. Each PD independently collects optical signals from different contact areas on the skin, ensuring that at least one PD maintains good contact. This segmentation resolves the contradiction by improving signal quality through multiple independent collection channels while keeping each individual PD structure simple.
Solution Approach 2:
The patent merges the output signals from multiple PDs through a delay circuit and AFE chip. The signals are combined in such a way that they are processed independently and then integrated, allowing the system to leverage the advantages of multiple PDs while maintaining a unified processing architecture. This merging approach improves overall signal quality without excessively complicating the device structure.
2Measurement precision
If multiple PDs are connected in parallel without delay circuit, then the device complexity is low, but the electrical signals from different PDs interfere with each other, reducing measurement precision
Solution Approach 1:
The patent applies preliminary action by introducing a delay circuit that processes the electrical signal from the first PD before it reaches the AFE chip. The delay circuit adjusts the timing of the first electrical signal to ensure it does not interfere with the second electrical signal from the second PD. This preliminary timing adjustment prevents signal interference and improves measurement precision while adding only moderate circuit complexity.
Solution Approach 2:
The delay circuit acts as an intermediary between the first PD and the AFE chip. It mediates the timing relationship between signals from different PDs, ensuring that they are processed independently without interference. This intermediary component resolves the contradiction by enabling precise signal separation while maintaining a relatively simple overall circuit structure.
3Measurement precision
If electrical signals from multiple PDs are processed simultaneously without delay, then the processing is efficient, but the signals are not independent, affecting the accuracy of target signal selection
Solution Approach 1:
The delay circuit performs preliminary timing adjustment on the first electrical signal before it reaches the AFE chip for target signal selection. By pre-adjusting the timing, the system ensures that signals from different PDs are properly separated and can be independently evaluated. This preliminary action improves target signal selection accuracy while minimizing additional processing time through efficient circuit-based delay rather than software processing.
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 enhances the accuracy of health status data collection by ensuring independent and high-quality electrical signals are obtained, thereby improving user experience and data reliability.
Implementation Method 1
the PD receives an optical signal emitted by the LED and reflected by skin of a user, and converts the optical signal into an electrical signal
Data Source
AI summary
Embodiments of this application provide a terminal based on photo plethysmo graph PPG. The terminal includes an LED, an AFE chip, a processor, a delay circuit, and a plurality of PDs, the first PD is configured to receive a second optical signal reflected by the skin of the user, and convert the second optical signal into a first electrical signal; the second PD is configured to receive the second optical signal reflected by the skin of the user, and convert the second optical signal into a second electrical signal; the delay circuit is configured to perform delay processing on the first electrical signal; the AFE chip is configured to determine a target signal based on the second electrical signal and the first electrical signal subjected to the delay processing; and the processor is configured to process the target signal to obtain a health status of the user.