Image Sensor Focus Detection Pixel Arrangement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional image sensors with focus detecting pixels arranged only in the horizontal direction struggle to maintain image quality during moving image photography, especially when subjects are inclined at angles greater than 45 degrees, due to the difficulty in securing sufficient image quality during mixing readout and the need for complex correction processing.
Innovation Solution
The image sensor incorporates top and bottom opening pixel lines in addition to right and left opening pixel lines, with focus detecting pixels having shifted opening positions corresponding to different color filters, allowing for coexistence of image quality and AF performance in moving image photography by performing mixing readout and correction processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detecting pixels are arranged at G-pixel positions in the same level density as R-pixels or L-pixels, then focus detection capability is improved, but image quality deteriorates due to difficulty in securing sufficient image quality in moving image photographing with mixing readout
Solution Approach 1:
The image sensor is divided into distinct regions: a first region containing focus detecting pixels (R-pixels and L-pixels) arranged at G-pixel positions, and a second region containing only imaging pixels. This segmentation allows the focus detecting pixels to be dedicated to phase difference AF without compromising overall image quality, as the imaging pixels can be read out independently for high-quality image capture.
Solution Approach 2:
Different regions of the image sensor are assigned different functions with optimized characteristics. The first region is optimized for focus detection with R-pixels and L-pixels arranged to capture phase difference information, while the second region is optimized for high-quality imaging. This local optimization resolves the contradiction by allowing each region to excel at its specific function without being constrained by the other requirements.
2Measurement precision
If only right and left opening pixel lines are arranged for focus detection, then horizontal phase difference detection is improved, but detection of subjects inclined at angles not smaller than 45 degrees deteriorates
Solution Approach 1:
The patent extends the focus detection capability from a single horizontal dimension to two dimensions by adding top opening pixels (T-pixels) and bottom opening pixels (B-pixels) in the vertical direction. This dimensional expansion allows the system to detect phase differences for subjects at various orientations, including those inclined at angles not smaller than 45 degrees, thereby improving adaptability while maintaining horizontal detection precision.
3Productivity
If mixing readout is performed with focus detecting pixels at G-pixel positions, then readout efficiency is improved, but correction processing complexity increases and image quality suffers
Solution Approach 1:
By segmenting the sensor into a first region with focus detecting pixels and a second region with imaging pixels, the patent enables independent readout paths. This segmentation reduces the need for complex correction processing during mixing readout, as the imaging pixels in the second region can be read out without interference from focus detecting pixels, thereby maintaining both readout efficiency and image quality.
Solution Approach 2:
The patent extracts focus detecting pixels from the G-pixel positions used for imaging, placing them in a dedicated first region. This extraction allows the imaging pixels in the second region to function independently without requiring complex correction processing, thus reducing overall system complexity while maintaining readout efficiency.
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
This configuration ensures sufficient image quality and accurate AF performance during moving image photography by shifting focus detecting pixel openings and using specific color filters, reducing the need for complex correction and enhancing image quality and focus detection accuracy.
Implementation Method 1
a photodiode PD and a color filter CF, the photodiode PD having a light receiving surface that is inclined with respect to the optical axis OA
Data Source
AI summary
An image sensor comprising a plurality of imaging pixels and a plurality of focus detecting pixels in which opening positions of light receiving parts are shifted from those of the imaging pixels, wherein first focus detecting pixels in which the opening positions are shifted in a first direction are arranged in a first pixel pitch at positions corresponding to first color filters for the imaging pixels, and second focus detecting pixels in which openings are shifted in a second direction different from the first direction are arranged in a second pixel pitch at positions corresponding to second color filters for the imaging pixels different from the first color filters.