4T-4S Step and Repeat Pixel Diagonal Photodiode Layout
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional 4T-4S step & repeat unit pixels face errors in processing the green component and require redesigned processing circuits when a unit pixel fails, especially due to differences in photodiode arrangements, which complicates recovery algorithms and increases sensor size.
Innovation Solution
The 4T-4S step & repeat unit pixel is designed with diffusion area patterns for four photodiodes arranged in diagonal directions, allowing for reduced transistor count and enabling conventional recovery algorithms to function without changes, even when unit pixels fail, by optimizing photodiode connections and color filter placements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If photodiodes are arranged in conventional configurations for 4T-4S unit pixels, then the image sensor can process image signals, but errors occur in green component processing and require redesigned processing circuits when pixels fail
Solution Approach 1:
The patent applies asymmetry by arranging photodiodes in non-conventional diagonal positions rather than symmetric grid patterns. Specifically, first and second photodiodes are positioned at diagonal corners, and third and fourth photodiodes are positioned at opposite diagonal corners, creating an asymmetric layout that enables uniform recovery algorithm application across all pixel types without requiring redesigns for different color components.
2Manufacturing precision
If photodiodes are arranged to improve green component processing, then errors are reduced, but photodiode arrangement flexibility is constrained
Solution Approach 1:
The patent transitions from conventional two-dimensional grid arrangements to a diagonal dimensional arrangement. By positioning photodiodes along diagonal axes rather than horizontal/vertical grids, the invention achieves improved green component processing while maintaining arrangement flexibility, as the diagonal configuration naturally accommodates various color filter placements without constraining adaptability.
3Ease of manufacture
If conventional recovery algorithms are used, then processing is simplified, but they cannot be applied to failed unit pixels without redesign
Solution Approach 1:
The patent achieves universality by designing a photodiode arrangement where a single conventional recovery algorithm can handle all pixel failures regardless of position or color component. The diagonal arrangement ensures that all four photodiodes in any unit pixel have equivalent geometric relationships to their neighbors, making the recovery algorithm universally applicable without requiring different implementations for different pixel types or failure modes.
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 design minimizes errors in green component processing and allows for seamless application of conventional recovery algorithms, enhancing the reliability and efficiency of image sensors by maintaining the aperture ratio and reducing data processing errors.
Implementation Method 1
four photodiodes PD0 to PD3 for converting image signals received through the color filters into electrical signals
Data Source
AI summary
Disclosed are a 4T-4S step & repeat unit pixel used in an image sensor and an image sensor having the same. The 4T-4S step & repeat unit pixel has four diffusion area patterns for photodiodes and three diffusion area patterns for an image signal conversion circuit. An aperture ratio of the image sensor increases in maximum by using four photodiodes arranged in a diagonal direction from each other and three diffusion area patterns arranged between the photodiodes near their edges.