Electronic Device Light Sensing Speed Precision Trade-off
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electronic devices for photoplethysmography face challenges in achieving both speed and accuracy in sensing ambient and target light levels, which affects the reliability of photoplethysmography signals used for monitoring blood vessel changes.
Innovation Solution
The electronic device employs a light source, light sensor, and controller that operate in both coarse and fine modes to sense ambient light, cancel coarse ambient light, and accurately measure target light, using ADCs to convert signals into different bit numbers for enhanced precision and speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the light source is turned off to sense ambient light in coarse mode, then the sensing speed is improved, but the measurement precision of target light is worsened
Solution Approach 1:
The patent segments the light sensing process into three distinct modes: coarse ambient light sensing (light source off), fine ambient light sensing (light source off), and target light sensing (light source on). This segmentation allows each mode to be optimized independently, with coarse mode providing quick ambient light data and fine mode providing precise correction, thereby resolving the contradiction between speed and precision.
Solution Approach 2:
The patent performs preliminary coarse ambient light sensing before target light sensing to establish a baseline. This preliminary action allows the system to quickly compensate for ambient light changes and provides a reference for subsequent precise target light measurement, improving overall sensing speed without sacrificing precision.
2Measurement precision
If the light source is turned on to sense target light, then the measurement precision is improved, but the sensing speed is worsened
Solution Approach 1:
The patent applies different quality levels of sensing to different parts of the measurement process. Coarse ambient light sensing uses lower precision but faster measurement, while fine ambient light sensing uses higher precision for correction. This local differentiation of quality allows the system to achieve high overall precision without requiring all measurements to be slow and highly precise.
3Measurement precision
If both coarse and fine ambient light sensing are performed, then the measurement precision is improved, but the device complexity is worsened
Solution Approach 1:
The patent makes the light sensor multi-functional by using it for three different purposes: coarse ambient light sensing, fine ambient light sensing, and target light sensing. This universal use of a single sensor eliminates the need for separate sensors for each function, reducing device complexity while maintaining high measurement precision through the combination of multiple sensing modes.
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 approach enables improved speed and accuracy in photoplethysmography signal generation, allowing for more reliable detection of blood vessel changes and health monitoring.
Implementation Method 1
a light sensor... senses an amount of a coarse ambient light by turning off the light source and performing sensing in a coarse mode by using the light sensor
Data Source
AI summary
An electronic device includes a light source, a light sensor, and a controller that senses an amount of a coarse ambient light by turning off the light source and performing sensing in a coarse mode by using the light sensor and senses an amount of a fine ambient light by performing sensing in a fine mode by using the light sensor. The controller senses an amount of a target light by turning on the light source and performing sensing by using the light sensor while the light source emits a light, and outputs information based on the amount of the coarse ambient light, the amount of the fine ambient light, and the amount of the target light.