Stereo Camera Exposure Timing Overlap for Flicker Resistance
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Solution Overview
Problem
Existing stereo camera systems for on-vehicle applications face issues with missing information due to flicker from light emitting devices, particularly when the exposure periods of image pickup apparatuses do not overlap correctly, leading to incomplete data capture.
Innovation Solution
The proposed image pickup system involves a configuration where the exposure periods of the first and second image pickup apparatuses are repeated multiple times in one frame, with the exposure period of the first apparatus overlapping with the non-exposure period of the second apparatus and vice versa, ensuring continuous data capture and preventing information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the exposure period of the second image pickup apparatus is made longer than the exposure period of the first image pickup apparatus to countermeasures against flicker, then flicker resistance is improved, but information may be missed if the light emitting device emits light before the exposure period ends
Solution Approach 1:
The patent applies periodic action by repeating the exposure period multiple times within one frame period. The first image pickup apparatus performs exposure at different time points (first, second, third exposure periods) within one frame, allowing the system to capture images at multiple phases of the light emitting device's blinking cycle, thereby ensuring at least one successful capture despite flicker
Solution Approach 2:
The patent uses preliminary action by having the second image pickup apparatus perform exposure in advance (before the first image pickup apparatus) and use its captured image to detect the blinking state of the light emitting device. This preliminary detection allows the system to adjust timing and ensure proper exposure timing for the first apparatus
2Device complexity
If the exposure periods of the first and second image pickup apparatuses are made to coincide, then device complexity is reduced, but measurement precision deteriorates due to inability to detect light emitting device blinking state
Solution Approach 1:
The patent applies asymmetry by making the exposure periods of the first and second image pickup apparatuses different from each other. The second apparatus exposes earlier and longer than the first apparatus, creating an asymmetric timing relationship that enables the second apparatus to detect the blinking state while the first apparatus captures the main image with proper timing
Data Source
AI summary
At least one image pickup system that acquires distance information and prevents missing, or loss of, information while taking countermeasures against flicker, includes a first image pickup apparatus, a second image pickup apparatus, and a signal processing unit configured to process signals acquired from the first image pickup apparatus and the second image pickup apparatus. An exposure period of the first image pickup apparatus and an exposure period of the second image pickup apparatus are repeated a plurality of times in one frame. The exposure period of the first image pickup apparatus is overlapped with a non-exposure period of the second image pickup apparatus, and a non-exposure period of the first image pickup apparatus is overlapped with the exposure period of the second image pickup apparatus.