Dual Pitch Focus Detection Pixels for Image Sensor
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Solution Overview
Problem
Existing imaging devices with pupil division-type focus detection pixels face challenges in accurately detecting focus adjustment states due to high interpolation errors when focus detection pixels are densely disposed over a long range, which affects image quality and defocus amount detection.
Innovation Solution
The implementation of a dual focus detection pixel group with different array pitches and directions, where the first focus detection pixel group has a finer pitch for high-accuracy focus detection and the second group has a coarser pitch for large defocus detection, along with optimized photoelectric conversion units and micro-lens configurations, allows for improved focus detection accuracy and reduced interpolation errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If focus detection pixels are disposed densely over a long range to enable accurate focus detection and large defocus amount detection, then focus detection accuracy and detection range are improved, but interpolation errors increase significantly affecting image quality
Solution Approach 1:
The image sensor is segmented into distinct functional regions: imaging pixel regions and focus detection pixel regions. The focus detection pixels are further divided into multiple groups with different array pitches. This segmentation allows each region to be optimized independently - focus detection pixels can be densely arranged for accurate measurement without compromising the overall image quality, as they are spatially separated from the imaging pixels that require interpolation.
Solution Approach 2:
Different regions of the image sensor are assigned different local qualities and functions. The focus detection pixel regions have high density and long-range coverage optimized for focus measurement, while the imaging pixel regions maintain their own optimization for image capture. This local quality differentiation resolves the contradiction by allowing dense focus detection pixels without forcing interpolation errors into the imaging pixel regions.
2Measurement precision
If focus detection pixels are disposed densely to achieve fine image detection pitch for accurate focus detection, then focus detection precision is improved, but the number of focus detection pixels increases requiring longer array length
Solution Approach 1:
The focus detection pixels are segmented into multiple groups with different array pitches rather than using a single uniform dense array. This segmentation reduces the overall complexity by dividing the detection function across multiple specialized sub-arrays, each optimized for specific detection ranges while maintaining high precision through their respective fine pitches.
Solution Approach 2:
The patent introduces an additional dimension of organization by creating multiple focus detection pixel groups with different array pitches along the same detection line. This multi-dimensional approach allows the system to achieve both fine detection precision and comprehensive coverage without requiring a single excessively long and complex pixel array.
3Adaptability or versatility
If focus detection pixels are arrayed over a long range to enable detection of large image shift amount when greatly defocused, then defocus detection range is improved, but interpolation errors increase affecting surrounding imaging pixels
Solution Approach 1:
The image sensor is divided into separate imaging pixel regions and focus detection pixel regions. This segmentation allows the focus detection pixels to be arrayed over a long range for detecting large defocus amounts without interfering with the imaging pixels. The interpolation process is applied only to the focus detection pixel regions, preventing interpolation errors from affecting the surrounding imaging pixel signals.
Solution Approach 2:
The focus detection pixel groups act as intermediary elements between the optical system and the final focus determination. By using multiple groups with different array pitches, the system can detect both small and large image shift amounts accurately. The interpolation is confined to these intermediary focus detection regions, protecting the primary imaging pixel regions from interpolation-related quality degradation.
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 approach enables simultaneous high-accuracy focus detection and large defocus amount detection while maintaining image quality, by minimizing interpolation errors and ensuring sufficient light sensitivity across various brightness levels.
Implementation Method 1
imaging pixels that convert an image formed via an optical system to image signals, and a first focus detection pixel group and a second focus detection pixel group respectively made up with an array of first focus detection pixels and an array of second focus detection pixels, with the first focus detection pixels and the second focus detection pixels used to receive an image light flux via the optical system
Data Source
AI summary
An image sensor includes imaging pixels that convert an image formed via an optical system to image signals and a first focus detection pixel group and a second focus detection pixel group respectively made up with an array of first focus detection pixels and an array of second focus detection pixels, with the first focus detection pixels and the second focus detection pixels used to receive an image light flux via the optical system to detect a focus adjustment state at the optical system through a pupil division-type method. An image detection pitch of the first focus detection pixel group and an image detection pitch of the second focus detection pixel group are different from each other.