Optical Sensor Flicker Detection for Synchronized Image Frames
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Solution Overview
Problem
Conventional optical sensors fail to synchronize their frame rate with the flicker frequency of ambient light, leading to incorrect motion identification due to fluctuations in light intensity, particularly in indoor environments with fluorescent lighting.
Innovation Solution
An optical sensor equipped with a photodiode, wave converter, and digital backend that detects ambient light flicker, generates square wave signals, and adjusts frame ticks based on the consistency and frequency of these signals to synchronize with the flicker frequency, ensuring accurate motion detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical sensor operates with a fixed frame rate, then the device complexity is low, but the motion detection accuracy deteriorates due to ambient light flicker
Solution Approach 1:
The system performs preliminary detection of ambient light flicker characteristics before motion detection. The photodiode detects flicker pulses and the digital backend identifies flicker frequency in advance, allowing the frame rate to be synchronized to match the flicker frequency, thereby eliminating light intensity fluctuations before they affect motion detection accuracy
Solution Approach 2:
The system implements a feedback mechanism where the detected ambient light flicker frequency is used to dynamically adjust the frame rate of the optical sensor. The digital backend continuously monitors flicker pulses and generates synchronized frame ticks, creating a closed-loop system that maintains accurate motion detection by adapting to changing lighting conditions
2Measurement precision
If the frame rate is synchronized to ambient light flicker frequency, then the motion detection accuracy is improved, but the device complexity increases due to additional synchronization components
Solution Approach 1:
The photodiode serves multiple functions: it acts as both the primary light detection element for image capture and the flicker detection sensor. The digital backend performs dual roles by processing both the flicker synchronization signals and the motion detection algorithms, reducing the need for separate dedicated components and thereby limiting the increase in device complexity
Solution Approach 2:
The system merges the flicker detection and motion detection functions into a unified processing architecture. The frame ticks generated for synchronization are integrated with the image capture timing, and the digital backend combines flicker frequency analysis with motion detection processing, consolidating multiple functions into shared hardware and software resources
3Ease of operation
If the optical sensor captures frames at arbitrary intervals, then the frame rate is simple to control, but the average brightness fluctuates causing incorrect motion identification
Solution Approach 1:
The system implements periodic frame capture synchronized to the ambient light flicker cycle. By generating frame ticks at intervals that match the flicker frequency (e.g., capturing one frame per flicker cycle or at specific phases), the system ensures that each frame captures a consistent phase of the light cycle, eliminating brightness fluctuations that would otherwise cause incorrect motion identification
Solution Approach 2:
The system dynamically changes the frame rate parameter based on the detected flicker frequency. Instead of using a fixed frame rate, the frame ticks are generated at intervals that correspond to the identified flicker frequency, adapting the temporal parameters of image capture to match the environmental lighting conditions and ensure reliable motion identification
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
The solution effectively eliminates the influence of ambient light flicker by maintaining a consistent frame rate, reducing incorrect motion identification and ensuring stable image capture under varying AC mains frequencies.
Implementation Method 1
The photodiode is configured to detect ambient light flicker to generate a light signal
Implementation Method 2
The wave converter is configured to receive the light signal and to generate a square wave signal
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 recognize a frequency of ambient light flicker and adjust an acquiring phase of the image frame.