CMOS Phase Difference Detection Pixel Distortion Correction
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Solution Overview
Problem
Imaging devices with CMOS sensors face challenges in precise focus control due to distortion caused by the rolling shutter method, especially when imaging moving subjects, leading to errors in phase difference detection without additional circuitry to mitigate these issues.
Innovation Solution
An imaging device with phase difference detection pixel pairs and imaging pixel pairs that perform correlation computations to correct for distortion, using a rolling shutter method, allowing for high-precision focus control without additional circuits by adjusting exposure and selecting appropriate pixel pairs for correlation computation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a rolling shutter method is used to read signals from phase difference detection pixels, then the imaging device can operate with standard CMOS sensor architecture, but distortion arises in images of moving subjects and errors occur in phase difference detection
Solution Approach 1:
The patent introduces imaging pixels as an intermediary element to measure and correct distortion. By using imaging pixels (which are not affected by rolling shutter distortion in the same way) to calculate distortion amounts and then correcting the phase difference detection results, the system eliminates detection errors while maintaining the simple CMOS architecture.
2Measurement precision
If additional circuits are added to correct for rolling shutter distortion, then focus detection precision can be improved, but device complexity and cost increase
Solution Approach 1:
The patent enables the imaging device to correct its own distortion using existing pixels (imaging pixels) without requiring external additional circuits. The system uses the imaging pixels' data to calculate and correct distortion in the phase difference detection pixels, achieving self-correction while maintaining simple device architecture.
3Ease of operation
If phase difference detection is performed using pixels read at different times due to rolling shutter, then the imaging device can use standard readout methods, but image movement during readout causes detection errors
Solution Approach 1:
The patent implements a feedback mechanism where imaging pixels provide information about distortion caused by rolling shutter readout, and this information is fed back to correct the phase difference detection results. This continuous correction loop ensures reliable detection despite the timing differences introduced by rolling shutter readout.
Data Source
AI summary
An imaging device includes an image pick-up device including phase difference detection pixel pairs, each formed from a pair of phase difference detection pixels respectively having their openings eccentrically formed on opposite sides of a main axis of an imaging lens, and imaging pixel pairs; a reading section that reads out signals from the pixels arrayed in the image pick-up device using a rolling shutter method; a first correlation computation section that performs correlation computation on the signals from the phase difference detection pixel pairs; a second correlation computation section that performs correlation computation on the signals from the imaging pixel pairs; a correction section that corrects a result from the first correlation computation section using a result from the second correlation computation section; and a focusing section that performs focus control using the corrected result.