Wrist-worn Light Sensor Array for Accurate Ambient Measurement
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Solution Overview
Problem
Existing wrist-worn devices for sensing ambient light intensity suffer from directional sensitivity issues, leading to inadequate measurement of ambient lighting and its influence on human circadian rhythms, as the main axis of sensitivity is often orthogonal to the user's gaze and does not accurately represent the primary light sources in most environments.
Innovation Solution
A wrist-worn device with multiple light receivers arranged in different orientations and positions to achieve quasi-omni-directional light measurement, where each receiver's axis of maximum receptivity lies in various spatial directions, allowing for better estimation of ambient light intensity by counterbalancing directional receptivity and combining signals to identify the maximum intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single light receiver is mounted with its sensitivity axis orthogonal to the display surface, then the device structure is simple, but the measurement accuracy of ambient light intensity is insufficient
Solution Approach 1:
The single light receiver is segmented into multiple light receivers (first, second, third, and fourth receivers) arranged at different positions and orientations on the display surface. Each receiver measures light intensity from a specific direction, and the central processing unit combines these measurements to calculate the ambient light intensity, thereby improving measurement accuracy while maintaining manageable device complexity.
2Reliability
If the light receiver's main sensitivity axis is orthogonal to the display surface, then the device structure is simple, but the correlation with user's actual light exposure is poor
Solution Approach 1:
Different regions of the display surface are assigned different sensor orientations to capture light from different directions. The first and second receivers are arranged with their sensitivity axes in a first direction, while the third and fourth receivers are arranged with their sensitivity axes in a second direction different from the first. This local variation in sensor orientation ensures that at least one receiver always captures light from the user's actual exposure direction, improving reliability of circadian rhythm estimation.
3Adaptability or versatility
If multiple light receivers are arranged in different orientations, then the quasi-omni-directional measurement is achieved, but the device complexity increases
Solution Approach 1:
The light receivers are arranged in an asymmetric pattern on the display surface rather than uniform distribution. The first and second receivers are positioned and oriented differently from the third and fourth receivers, creating an asymmetric configuration that achieves quasi-omni-directional coverage with fewer components than a symmetric arrangement would require.
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 enhances the accuracy of ambient light intensity measurement, reducing the influence of directional sensitivity and providing a more comprehensive assessment of light exposure, which is essential for synchronizing the body clock and diagnosing mood and sleep disorders.
Implementation Method 1
The light receivers are light sensors that collect light and convert the received light intensity into a corresponding electric signal that can be further processed
Data Source
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AI summary
The invention relates to a wrist-worn device (10) for sensing ambient light intensity, comprising a plurality of light receivers arranged at different positions of the wrist-worn device (10) in different orientations to receive light from different directions (+X, -X; +Y, -Y;+Z, -Z).