Image Sensor Pixel Layout for Balanced Phase Detection
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Solution Overview
Problem
Conventional image sensors experience biased performance in on-imaging plane phase difference focus detection due to non-1:1 aspect ratios, leading to decreased focus detection accuracy, especially when subject textures are horizontal or vertical.
Innovation Solution
The image sensor is designed with pixel portions where the length in one direction is longer than the other, featuring microlenses arranged in a matrix and photoelectric conversion portions configured for higher electric charge crosstalk rates in one direction compared to the other, optimizing focus detection accuracy based on the sensor's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If photoelectric conversion portions are arranged in a single direction (horizontal or vertical) for pupil division, then the structure is simple, but focus detection accuracy decreases when subject textures are parallel to the arrangement direction
Solution Approach 1:
The patent transitions from one-dimensional photoelectric conversion portion arrangement to two-dimensional arrangement. Specifically, photoelectric conversion portions are arranged in both horizontal and vertical directions relative to the microlens, enabling pupil division in multiple directions simultaneously. This dimensional expansion allows the system to detect focus accuracy for subject textures in any orientation, resolving the limitation of single-direction arrangements.
2Adaptability or versatility
If the image sensor has a non-1:1 aspect ratio, then the sensor can be optimized for specific imaging formats, but on-imaging plane phase difference focus detection performance becomes biased toward one direction
Solution Approach 1:
The patent introduces asymmetric design in the photoelectric conversion portion arrangement that matches the sensor's aspect ratio. When the sensor has a non-1:1 aspect ratio, the photoelectric conversion portions are arranged with different spacing or numbers in horizontal versus vertical directions, creating an asymmetric configuration that compensates for the aspect ratio bias and maintains balanced focus detection accuracy across both directions.
Solution Approach 2:
The patent applies different arrangement characteristics to different regions of the pixel structure. The photoelectric conversion portions have varying spacing, sizes, or numbers depending on their position (horizontal vs. vertical) relative to the microlens. This local differentiation allows the system to optimize each direction's photoelectric conversion efficiency according to the sensor's overall aspect ratio, thereby achieving balanced performance.
3Productivity
If photoelectric conversion portions are densely arranged to improve light utilization, then imaging efficiency increases, but electric charge crosstalk between adjacent portions increases
Solution Approach 1:
The patent optimizes multiple parameters of the photoelectric conversion portions simultaneously, including size, spacing, and arrangement pattern. By carefully adjusting these parameters, the system achieves high light utilization efficiency while maintaining sufficient separation to minimize electric charge crosstalk. The parameter optimization is particularly tailored to the sensor's aspect ratio to ensure balanced performance in both directions.
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 enhances the focus detection accuracy by adjusting the electric charge crosstalk rates in accordance with the sensor's aspect ratio, thereby improving the performance of phase difference focus detection across different orientations of subject textures.
Implementation Method 1
a plurality of microlenses arranged in a matrix in the first direction and the second direction
Implementation Method 2
photoelectric conversion portions provided for each microlens of at least some of the plurality of microlenses and configured to perform photoelectric conversion on light that has entered the photoelectric conversion portions via the each microlens
Data Source
AI summary
An image sensor in which a length of a pixel portion in a first direction is longer than a length of the pixel portion in a second direction orthogonal to the first direction. The pixel portion includes: a plurality of microlenses arranged in a matrix in the first direction and the second direction, and a plurality of photoelectric conversion portions provided for each microlens of at least some of the plurality of microlenses and configured to perform photoelectric conversion on light that has entered the photoelectric conversion portions via the each microlens. The plurality of photoelectric conversion portions are arranged in at least one of the first and second directions, and an electric charge crosstalk rate between a plurality of photoelectric conversion portions arranged in the first direction is higher than that between a plurality of photoelectric conversion portions arranged in the second direction.