Solid-state Image Pickup Element Parallel Focus Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing solid-state image pickup elements face challenges in achieving fast and highly accurate autofocus due to limitations in focus detection signal processing, particularly when using hybrid AF methods that combine phase difference and contrast detection, as they do not efficiently manage data transfer and image signal output.
Innovation Solution
A solid-state image pickup element with a pixel array that includes separate calculators for phase difference and contrast evaluation values, allowing these values to be output independently of the image signal completion, and an interpolation processor to compensate for defects in the image signal, enabling parallel processing and improved autofocus control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If signals for focus detection are read out at a high frame rate, then autofocus speed is improved, but the amount of data to be transferred to the signal processor increases
Solution Approach 1:
The patent extracts only the essential focus detection signals from the pixel array at high frame rates, while compressing or selectively transmitting other image data. This allows fast autofocus operation without proportionally increasing the total data transfer burden on the signal processor.
Solution Approach 2:
The patent segments the pixel array into different functional regions (e.g., phase difference detection pixels, contrast detection pixels, and regular image pixels), allowing independent high-speed readout of focus detection signals while managing overall data flow more efficiently.
2Measurement precision
If hybrid AF method is used combining phase difference detection and contrast detection, then in-focus accuracy is improved, but device complexity increases
Solution Approach 1:
The patent merges phase difference detection and contrast detection methods into a unified hybrid autofocus system within the solid-state image pickup element. Both detection methods share common hardware resources (pixel array, readout circuits, signal processing units), achieving high in-focus accuracy while controlling overall system complexity through resource sharing.
Solution Approach 2:
The patent designs the pixel array and signal processing circuits to serve multiple functions: the same pixel array performs both phase difference detection and contrast detection, and the signal processor handles both focus evaluation and image processing tasks, reducing the need for separate dedicated components.
3Measurement precision
If phase difference evaluation value and contrast evaluation value are calculated separately, then focus detection accuracy is improved, but processing time increases
Solution Approach 1:
The patent performs preliminary calculations for both phase difference and contrast evaluation values simultaneously during the same exposure period, rather than sequentially. This parallel processing approach maintains high focus detection accuracy while reducing the total processing time required.
Solution Approach 2:
The patent maintains continuous operation of both phase difference and contrast detection circuits throughout the image exposure and readout process, ensuring that both evaluation values are always available for immediate focus determination without interruption or sequential delays.
Data Source
AI summary
A solid-state image pickup element, including: a pixel array including a plurality of pixels; a first calculator that calculates a phase difference evaluation value for focus detection by a phase difference detection method based on signal from the pixel; and a second calculator that calculates a contrast evaluation value for focus detection by a contrast detection method based on signal from the pixel, wherein, when the first calculator completes calculation of the phase difference evaluation value, the phase difference evaluation value is output regardless of whether or not output of an image signal acquired by the pixel array is completed, and wherein, when the second calculator completes calculation of the contrast evaluation value, the contrast evaluation value is output regardless of whether or not output of the image signal acquired by the pixel array is completed.