Optical Sensor Synchronizing to Ambient Light Flicker
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Solution Overview
Problem
Conventional optical sensors operating indoors under fluorescent lighting with flickering ambient light can incorrectly identify object motion due to unsynchronized frame rates, leading to fluctuations in image brightness.
Innovation Solution
An optical sensor system that includes a photodiode for detecting flicker pulses, a processor to count square wave signals, and adjusts the frame rate synchronization with the ambient light flicker frequency only when detection is confirmed, using a clock signal and trigger ticks to ensure consistent image frame capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the frame rate of the optical sensor is not synchronized to the flicker frequency of ambient light, then the optical sensor can operate independently without complex synchronization mechanisms, but the average brightness of image frames fluctuates between bright and dark leading to incorrect motion identification
Solution Approach 1:
The patent applies preliminary action by detecting and counting flicker pulses before adjusting the frame rate. The optical sensor first counts a predetermined number of flicker pulses using a counter, then generates a synchronized frame rate based on the counted value. This preliminary detection and counting process ensures that the synchronization is established before motion detection begins, thereby improving reliability without requiring continuous complex synchronization mechanisms during operation
Solution Approach 2:
The patent implements self-service by using the optical sensor's own photodiode to detect ambient light flicker and generate the synchronization signal. The system autonomously detects the flicker frequency, counts the pulses, and adjusts its frame rate without requiring external synchronization signals or additional dedicated synchronization hardware, thereby reducing device complexity while maintaining reliable motion identification
2Reliability
If the frame rate is continuously adjusted to synchronize with ambient light flicker, then correct motion detection is maintained, but unnecessary adjustments increase device complexity and processing overhead
Solution Approach 1:
The patent applies partial action by adjusting the frame rate only partially and only when necessary. The system continuously monitors ambient light conditions and only modifies the frame rate when flicker detection indicates a synchronization need. This selective adjustment approach maintains motion detection accuracy while avoiding unnecessary frame rate changes that would increase processing overhead and device complexity
Solution Approach 2:
The patent implements feedback by using the counted flicker pulse values to dynamically adjust the frame rate. The system counts flicker pulses, compares the counted value against expected ranges, and uses this feedback information to generate an appropriate synchronized frame rate. This closed-loop feedback mechanism ensures reliable motion detection while minimizing unnecessary adjustments by only changing frame rate when the feedback indicates actual synchronization needs
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 effectively eliminates incorrect motion identification by synchronizing image frames with the ambient light flicker frequency, reducing unnecessary adjustments and maintaining accurate motion detection.
Implementation Method 1
an individually operated photodiode for detecting flicker pulses of ambient light
Data Source
AI summary
There is provided an optical sensor including a photodiode, a wave converter, a pixel array and a processor. The photodiode detects ambient light flicker to generate sine waves. The wave converter converts the sine waves to square waves. The processor uses a sampling frequency to count the square waves, and identifies whether the ambient light flicker is well detected according to a counting value of each square wave and a counting value variation of multiple square waves within a count period to accordingly determine whether to adjust an acquiring phase of the image frame.