Image Sensor Symmetric Pixel Blocks Reduce Fixed Pattern Noise
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Solution Overview
Problem
Existing image sensors with shared pixel structures face differences in image signals due to varying distances between unit pixels and driving circuits, leading to fixed pattern noise (FPN) and reduced image resolution.
Innovation Solution
The image sensor employs a pixel array with sub-pixel arrays having symmetric planar configurations and color filter arrays where unit pixels of the same color have consistent distances to the driving circuits, minimizing signal differences and enhancing resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If unit pixels are arranged in a shared pixel structure with varying distances to the driving circuit, then the device complexity is reduced, but fixed pattern noise increases and image resolution deteriorates
Solution Approach 1:
The patent applies asymmetry by intentionally creating symmetric patterns in an asymmetric context. Specifically, adjacent pixel blocks are designed with symmetric planar configurations (mirrored layouts) within an otherwise asymmetric shared pixel structure. This symmetric arrangement of unit pixels relative to their driving circuits compensates for the inherent asymmetry of the shared structure, ensuring consistent signal paths and reducing fixed pattern noise while maintaining the compactness of the shared design.
2Ease of manufacture
If unit pixels have varying distances to the driving circuit, then manufacturing is simplified, but signal uniformity deteriorates leading to fixed pattern noise
Solution Approach 1:
The patent segments the pixel array into multiple pixel blocks, where each block contains unit pixels with controlled symmetric arrangements. This segmentation allows the complex requirement of uniform signal paths across the entire array to be broken down into manageable symmetric patterns within each block, simplifying the manufacturing process while ensuring signal consistency through the repeated symmetric configurations.
3Productivity
If a shared pixel structure is used to reduce device complexity, then productivity increases, but fixed pattern noise increases due to signal differences
Solution Approach 1:
The patent applies local quality by maintaining different configurations at different locations within the pixel array. Specifically, while the overall structure is a shared pixel design, each pixel block is designed with specific symmetric planar configurations tailored to its position. This local optimization ensures that each region contributes to reduced fixed pattern noise while maintaining the high productivity of the shared structure.
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 effectively minimizes signal differences between unit pixels, reducing fixed pattern noise and improving high-resolution image output.
Implementation Method 1
a light reception unit including a plurality of unit pixels which generate photocharges in response to incident light
Data Source
AI summary
An image sensor may include a pixel array. The pixel array may include a plurality of sub pixel arrays arranged two-dimensionally. Each of the plurality of sub pixel arrays may include a first pixel block and a second pixel block adjacent to the first pixel block in a row direction. Each of the first and second pixel blocks may include a light reception unit including first to fourth unit pixels arranged in a 2×2 matrix structure and a driving circuit. The driving circuit of the first pixel block may be positioned at an upper side of the light reception unit of the first pixel block, and the driving circuit of the second pixel block may be positioned at a lower side of the light reception unit of the first pixel block. The upper side of the first pixel block and an upper side of the second pixel block may be aligned with each other in the row direction, and a lower side of the first pixel block and the lower side of the second pixel block may be aligned with each other in the row direction.