Image Sensor Flicker Detection via Variable Accumulation
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Solution Overview
Problem
Existing image capturing apparatuses face challenges in accurately detecting fluorescent light flicker, especially when the subject or the apparatus is moving, and when the frame rate ratio to flicker frequency is 1:N, leading to cancellation of the flicker signal.
Innovation Solution
An image capturing apparatus with an image sensor and a driving unit that captures image signals with different accumulation periods, allowing for accurate detection of flicker by performing relational operations between these signals to isolate and correct for flicker, even in moving subjects or apparatuses, and at frame rate ratios of 1:N.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If inter-frame relational operation is performed to cancel subject components and extract flicker, then flicker detection accuracy is improved for stationary subjects, but detection accuracy deteriorates when the subject or apparatus is moving because subject components cannot be fully canceled
Solution Approach 1:
The patent applies dynamics by making the accumulation period variable rather than fixed. The detection unit dynamically adjusts the accumulation period of image signals based on the specific detection needs, allowing the system to adapt to moving subjects and maintain detection accuracy. This dynamic adjustment enables the system to capture flicker patterns even when subjects are in motion, resolving the contradiction between stationary subject optimization and moving subject reliability.
Solution Approach 2:
The patent changes the parameter of accumulation period from a fixed value to a variable parameter that can be adjusted by the detection unit. By varying the accumulation period, the system can extract flicker components effectively regardless of subject movement, thereby improving both measurement precision and reliability under different conditions.
2Measurement precision
If frame rate ratio to flicker frequency is 1:N, then synchronization with flicker cycles is achieved, but flicker signal cancellation occurs making detection impossible
Solution Approach 1:
The patent applies partial action by using accumulation periods that are not exactly synchronized with the flicker cycle (avoiding the 1:N ratio), thereby preventing complete cancellation of the flicker signal. By intentionally using non-synchronized accumulation periods, the system ensures that some flicker information remains detectable, resolving the contradiction between synchronization benefits and signal preservation.
Solution Approach 2:
The detection unit preliminarily determines the appropriate accumulation period before image signal acquisition, selecting a period that avoids the problematic 1:N ratio with flicker frequency. This preliminary selection prevents flicker signal cancellation from occurring in the first place, maintaining detection capability.
3Illumination intensity
If accumulation period is extended to capture more light, then image signal quality is improved, but flicker variation within the frame increases making detection more difficult
Solution Approach 1:
The patent changes the accumulation period parameter to an optimized value that balances two competing requirements: it is long enough to capture sufficient light for good image signal quality, but not so long that flicker variation within the frame becomes excessive. The detection unit determines this optimal accumulation period based on the flicker frequency characteristics, resolving the contradiction between illumination intensity and detection precision.
Solution Approach 2:
The system preliminarily determines the optimal accumulation period before image capture, selecting a value that pre-balances the trade-off between light capture and flicker variation. This preliminary optimization ensures that both image quality and flicker detection precision are maintained simultaneously.
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 enables high-accuracy flicker detection and correction, reducing the influence of subject movement and allowing for flicker detection even when the frame rate and flicker frequency ratio is 1:N, thereby improving image quality.
Implementation Method 1
an image sensor... converting optical energy to electrical energy
Data Source
AI summary
An image capturing apparatus comprises an image sensor, a driving unit configured to drive the image sensor, and a detection unit configured to detect a variation in amount of light within one frame image based on a plurality of image signals obtained by driving the image sensor with different accumulation periods by the driving unit.