MOS Imaging Element Flicker Detection via Segmented Exposure
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Solution Overview
Problem
Existing imaging apparatuses using the rolling shutter method face difficulties in accurately detecting flicker, especially when capturing bright objects, due to halation issues and the need for specific exposure times that are not always feasible.
Innovation Solution
An imaging apparatus with a MOS imaging element and a flicker detection unit that compares captured image signals from different frame periods to detect flicker, allowing for arbitrary frame rates and adjusting signal reading periods to prevent halation and ensure accurate detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the exposure time is set to a natural number multiple of 1/100 seconds or 1/120 seconds to detect flicker, then flicker detection capability is improved, but halation occurs in the entire captured image data when capturing bright objects
Solution Approach 1:
The patent divides the imaging element into multiple scanning line groups (first group and second group) with different exposure timing. By comparing image data from these segmented groups, the system can detect flicker patterns without requiring the entire image to be exposed at specific time intervals, thereby avoiding halation while maintaining detection accuracy.
Solution Approach 2:
Different scanning line groups are assigned different exposure timing characteristics. The first scanning line group uses exposure timing synchronized with one flicker cycle, while the second group uses timing synchronized with another cycle. This local differentiation allows flicker detection across multiple frequencies without requiring uniform exposure timing across the whole image, preventing halation.
2Adaptability or versatility
If the rolling shutter method is used to control charge accumulation time for each scanning line, then imaging flexibility is improved, but uneven horizontal stripes (flicker) are generated when capturing under fluorescent lamps
Solution Approach 1:
The patent implements periodic exposure timing for different scanning line groups, where the first group is exposed during one phase of the flicker cycle and the second group during another phase. By periodically alternating the exposure timing of different line groups, the system captures flicker patterns that can be detected and corrected, maintaining the flexibility of the rolling shutter method while eliminating the harmful flicker effect.
Data Source
AI summary
Provided are an imaging apparatus, a flicker detection method, and a flicker detection program that can accurately detect a flicker even in a case in which an image of a bright object is captured. A digital camera directs a MOS imaging element 5 to perform a plurality of imaging operations at an arbitrary frame rate and compares captured image signals which are read from the imaging element 5 for frame periods F1 and F2 based on the frame rate to detect whether a flicker has occurred. The end time of a signal reading period in the frame period F1 is before the end time of the frame period F1 and the end time of a signal reading period in the frame period F2 coincides with the end time of the frame period F2.