Image Pickup Autofocus Control with Flicker Reduction
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Solution Overview
Problem
Existing image pickup apparatuses face challenges in performing high-speed autofocus detection due to the influence of flicker, which is generated by the rolling electronic shutter and fluorescent lighting, leading to line flicker and area flicker, necessitating dedicated control for flicker elimination.
Innovation Solution
An image pickup apparatus with a focus detector capable of detecting the focus state using phase difference between images in multiple directions, a flicker reduction mechanism, and a controller that adjusts the focal point based on phase difference before flicker reduction, allowing for high-speed autofocus detection independent of flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase difference focus detection is performed using focus detection pixels arranged in the image pickup element, then autofocus detection capability is provided, but high-speed autofocus detection cannot be achieved before flicker detection due to the need for dedicated flicker control
Solution Approach 1:
The patent divides the image pickup element into imaging pixels and focus detection pixels with pupil division function. The focus detection pixels are arranged at predetermined intervals to perform phase difference focus detection independently, allowing high-speed autofocus detection to proceed without waiting for flicker detection and control operations.
Solution Approach 2:
The patent performs phase difference focus detection using focus detection pixels before executing flicker detection and elimination operations. By preparing the focus detection result in advance, the system achieves high-speed autofocus detection without being delayed by subsequent flicker control procedures.
2Productivity
If focus detection pixels are arranged in the image pickup element, then phase difference focus detection is enabled, but the area corresponds to a defect part of imaging pixels requiring interpolation
Solution Approach 1:
The image pickup element is segmented into distinct imaging pixels and focus detection pixels. The focus detection pixels with pupil division function are specifically arranged to perform phase difference detection, while imaging pixels handle image capture. This segmentation allows each pixel type to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the image pickup element are assigned different functions: imaging pixels for image capture and focus detection pixels for phase difference measurement. The focus detection pixels are arranged at predetermined intervals where they serve the specific purpose of autofocus detection, while maintaining overall imaging quality through selective use of pixel data.
3Productivity
If rolling electronic shutter is used in the image pickup element, then continuous reading of image signals is enabled for live view mode, but horizontal-striped flicker is generated in the imaging screen
Solution Approach 1:
The patent extracts the focus detection function from the imaging process by using dedicated focus detection pixels with pupil division. This allows phase difference focus detection to be performed independently from the rolling shutter imaging process, enabling high-speed autofocus detection without being affected by line flicker generated during continuous image signal reading.
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
Enables high-speed autofocus detection without being influenced by flicker, improving the reliability and accuracy of focus detection in live view mode.
Implementation Method 1
an image pickup element 107 having a plurality of imaging pixels configured to perform a photoelectric conversion of an image formed by a light beam from an image pickup optical system
Data Source
AI summary
An image pickup apparatus of the present invention includes an image pickup element having imaging pixels and focus detection pixels, and configured to read a signal for which a photoelectric conversion has been performed in a first direction, a focus detector capable of detecting a focus state using a phase difference of a pair of images in the first direction and a pair of images in a second direction based on outputs of the focus detecting pixels, a flicker reduction portion configured to reduce the flicker, and a controller configured to control a focal point in accordance with the focus state obtained from a phase difference of the pair of images in the first direction before an operation of the flicker reduction portion.