Solid-State Imaging Apparatus Flicker Artifact Reduction
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Solution Overview
Problem
Solid-state imaging apparatuses using the rolling shutter method experience flicker artifacts in moving images captured under fluorescent lighting due to the periodic change in light source luminance, especially at high frame rates where the read-out time is shorter than the flicker cycle, making it difficult to reduce flicker effectively.
Innovation Solution
A solid-state imaging apparatus that calculates exposure amounts for each frame based on the flicker frequency of the light source, adjusting the charge accumulation period and gain to minimize the influence of flicker, by determining the average exposure amount across frames and adjusting the gain to maintain appropriate exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frame rate is increased to capture high-speed moving images, then the productivity is improved, but the flicker artifacts become more severe because the read-out time becomes shorter than the flicker cycle
Solution Approach 1:
The patent applies periodic action by setting the charge accumulation period to an integral multiple of the half cycle of the flicker frequency. This synchronization ensures that each frame accumulates charge during identical phases of the light source's periodic luminance variation, causing flicker components to align and cancel out when frames are combined, thereby eliminating flicker artifacts while maintaining high frame rates
Solution Approach 2:
The patent merges multiple frames that have been captured with synchronized charge accumulation periods. By combining these frames through addition or averaging, the periodic flicker components that are identical across frames reinforce each other in a controlled manner, while random noise components cancel out, resulting in high-quality images free from flicker artifacts
2Manufacturing precision
If the charge accumulation period is extended to improve exposure, then the image quality is improved, but the read-out time increases making it difficult to maintain high frame rates
Solution Approach 1:
The patent segments the charge accumulation process by dividing it into multiple shorter accumulation periods across different frames, where each frame accumulates charge for a brief period synchronized to the flicker cycle. This segmentation allows the total effective exposure time to be extended while keeping individual frame read-out times short, thereby maintaining high frame rates while improving overall image quality
Solution Approach 2:
The patent maintains continuity of useful action by continuously capturing frames with charge accumulation periods synchronized to the flicker cycle. This continuous capture process ensures that exposure is effectively extended over multiple frames without interruption, allowing high frame rates to be maintained while achieving improved image quality through accumulated exposure
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 effectively reduces flicker artifacts in high-frame-rate moving images by optimizing exposure settings per frame, ensuring adequate image quality and reducing power consumption.
Implementation Method 1
a pixel unit configured to perform imaging of a plurality of frames by a photoelectric conversion
Data Source
AI summary
A solid-state imaging apparatus includes: a pixel unit (1) configured to perform imaging of a plurality of frames by a photoelectric conversion; an exposure amount calculating unit (9) configured to calculate exposure amounts of the plurality of frames imaged in a flicker cycle of a light source; and a control unit (12) configured to control the exposure amount of each of the frames imaged by the pixel unit based on the exposure amounts of the plurality of frames calculated by the exposure amount calculating unit.