Image Pickup Pixels Flicker Correction and Focus Detection
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Solution Overview
Problem
Existing image pickup apparatuses with pixels functioning as both focus detection and imaging pixels face challenges in accurately correcting flicker caused by fluorescent light, leading to luminance unevenness and inaccurate defocus calculations due to incorrect flicker correction gain values and excessive corrections.
Innovation Solution
An image pickup apparatus is designed with a flicker correction system that includes a luminance generating unit, evaluation value generating unit, flicker detecting unit, and flicker correction value generating unit to detect and correct flicker in the image pickup signal, performing correlation calculations before and after flicker correction to ensure precise focus detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If pixels are used as both focus detection pixels and imaging pixels, then device complexity is reduced, but measurement precision deteriorates due to luminance unevenness affecting focus detection accuracy
Solution Approach 1:
The patent divides pixels into distinct functional groups: imaging pixels for capturing image signals and focus detection pixels for obtaining object distance information. This segmentation allows each pixel type to be optimized for its specific function, preventing luminance unevenness from affecting focus detection accuracy while maintaining a relatively simple overall device structure.
Solution Approach 2:
The patent extracts the focus detection function from the imaging pixels by designating specific pixels as focus detection pixels. These extracted pixels are专门 used for obtaining object distance information through phase difference detection, separating this measurement function from the imaging function to eliminate the interference of luminance unevenness.
2Object-affected harmful factors
If flicker correction is performed using conventional methods, then illumination flicker is addressed, but measurement precision deteriorates due to incorrect correction gain values causing excessive or insufficient correction
Solution Approach 1:
The patent implements a feedback mechanism where the system detects the actual flicker component in the image signal, calculates an appropriate correction gain value based on this detected flicker, and applies the correction. This closed-loop feedback approach ensures that the correction gain is accurately matched to the actual flicker conditions, preventing both excessive and insufficient correction.
Solution Approach 2:
The patent dynamically adjusts the correction gain value parameter based on the detected flicker component characteristics. By changing this parameter according to actual measurement conditions rather than using fixed conventional values, the system achieves precise flicker correction that adapts to varying illumination conditions and object motion.
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
The apparatus achieves high-accuracy flicker correction, minimizing luminance unevenness and improving defocus calculation accuracy by generating and applying appropriate correction gain values, even in the presence of object motion and fluorescent light characteristics.
Implementation Method 1
a plurality of pixels which function as both a plurality of imaging pixels for performing photoelectric conversion on a light beam from an image pickup optical system
Data Source
AI summary
An image pickup apparatus 100 includes an image pickup element 101 that includes a plurality of pixels that function as both imaging pixels and focus detection pixels, which is configured so that an image pickup signal that is obtained by performing photoelectric conversion in a first direction, an evaluation value generating unit 107 that generates an evaluation value of the image pickup signal, a flicker detecting unit 108 that detects variation information of illumination intensity based on the evaluation value, a flicker correction value generating unit 109 that generates a flicker correction value for performing a flicker correction for the image pickup signal based on the variation information, a multiplier 105 that performs the flicker correction for the image pickup signal based on the flicker correction value, and a vertical correlation calculating unit 114 that performs a correlation calculation in the first direction after the flicker correction is performed.