Active Pixel Sensor Array Pitch Uniformity
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Solution Overview
Problem
Conventional CMOS image sensors with shared read-out circuitry suffer from reduced photoelectric conversion efficiency and image quality due to small light conversion areas and uneven pitches between photoelectric conversion elements.
Innovation Solution
The design includes an active pixel array with unit active pixels featuring a first active area with multiple photoelectric conversion regions and a second elongate active area, where the readout circuitry is shared between photoelectric conversion regions, and the pitch between adjacent regions is standardized in both column and row directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple photoelectric conversion elements share common readout circuitry to increase pixel density, then the number of pixels per unit area increases, but the photoelectric conversion area of each element becomes small and pitches become uneven, reducing conversion efficiency and image quality
Solution Approach 1:
The active pixel array is divided into multiple unit active pixels, each containing multiple photoelectric conversion elements (e.g., four elements arranged in a 2x2 pattern). This segmentation allows each unit to have dedicated readout circuitry while maintaining compact spacing, thereby increasing overall pixel density without compromising individual element performance or pitch uniformity.
Solution Approach 2:
Each photoelectric conversion element within a unit active pixel is configured with substantially equal pitch dimensions in both row and column directions. This local uniformity ensures consistent photoelectric conversion efficiency across all elements, even as pixel density increases through the multi-element unit structure.
2Quantity of substance
If photoelectric conversion elements are arranged with small pitches to increase density, then more elements fit in the same area, but the pitches become unequal in row and column directions, adversely impacting image quality
Solution Approach 1:
The unit active pixel employs a symmetric 2x2 arrangement of photoelectric conversion elements, creating equal pitch dimensions in both row and column directions. This symmetric configuration within each unit ensures uniform spacing while achieving high density through the compact four-element structure.
Solution Approach 2:
Instead of simply increasing element count along a single dimension, the invention arranges multiple elements in a two-dimensional 2x2 grid within each unit active pixel. This dimensional approach allows density increase while maintaining equal pitch in both directions, avoiding the pitch uniformity problems of linear arrangements.
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 pixel density and maintains consistent conversion efficiency and image quality by standardizing the pitch and sharing readout circuitry, improving the overall performance of the image sensor.
Implementation Method 1
a first active area including a plurality of photoelectric conversion regions
Data Source
AI summary
In one aspect, an image sensor is provided which includes an array of unit active pixels. Each of the unit active pixels comprises a first active area including a plurality of photoelectric conversion regions, and a second active area separated from the first active area. The first active areas are arranged in rows and columns so as to define row and column extending spacings there between, and the second active areas are located at respective intersections of the row and column extending spacings defined between the first active areas.