Triangular Macropixel Color Filter Array for Image Sensors
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Solution Overview
Problem
In image sensors, particularly CMOS image sensors, the pixel fill factor has decreased due to reduced pixel pitch, leading to smaller photosensitive areas and increased peripheral circuitry, which affects image quality and size, especially in medical applications where high-quality images are required from compact sensors.
Innovation Solution
The use of non-rectangular, triangular macropixels with three micropixels arranged in an X, Y grid in a color filter array, which allows for a greater fill factor by reducing non-photosensitive circuitry area, enabling larger photosensitive elements and improved light collection paths in both frontside and backside illuminated image sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel pitch is reduced to increase resolution, then image resolution is improved, but photosensitive area is reduced
Solution Approach 1:
The pixel array is segmented into different pixel types (first pixels with first photosensitive elements and second pixels with second photosensitive elements) with different photosensitive areas. This segmentation allows the sensor to achieve high resolution through diverse pixel configurations rather than uniform small pixels, thereby maintaining adequate photosensitive area while improving resolution capability.
2Measurement precision
If photosensitive area is increased to improve image quality, then image quality is improved, but device size is increased
Solution Approach 1:
Different regions of the pixel array are assigned different pixel types with optimized photosensitive areas according to local requirements. First pixels and second pixels have different photosensitive element configurations tailored to their specific functional needs, allowing high image quality in critical regions without uniformly increasing device size across the entire sensor.
3Area of stationary object
If peripheral circuitry is reduced to increase fill factor, then fill factor is improved, but device functionality is reduced
Solution Approach 1:
The pixel array incorporates dynamic control mechanisms where different pixel types can be selectively activated or deactivated based on imaging conditions. This dynamic configuration allows the sensor to optimize fill factor by deactivating certain pixel types when not needed, while maintaining full functionality when diverse pixel types are required for different imaging scenarios.
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 increases the fill factor, allowing for larger photosensitive areas and enhanced image quality by minimizing the area devoted to non-photosensitive elements, resulting in improved image resolution and full well capacity without compromising rotational symmetry or addressing capabilities.
Implementation Method 1
The color filter array includes a first color filter element having a first non-rectangular shape associated with a first pixel element and a second color filter element having a second non-rectangular shape associated with a second pixel element
Data Source
AI summary
A color pixel array includes a plurality of micropixels. Each micropixel includes a photosensitive element and a color filter optically aligned with the photosensitive element to filter incident light prior to reaching the photosensitive element. The micropixels are organized into a repeating pattern of triangular macropixels each having a triangular shape within the color pixel array.