Pixel Sensing Module Sub-Pixel Segmentation for CMOS Image Sensors
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Solution Overview
Problem
CMOS image sensors face issues with light sensitivity due to residual electronic charges in large light-sensing components, leading to image sticking and crosstalk between light paths caused by misalignment of pixel sensing units and collimators.
Innovation Solution
The pixel sensing unit is divided into sub-pixel components with smaller light-sensing areas, and a collimating unit with aligned openings ensures that light only hits the sensing areas, preventing crosstalk and enhancing charge drainage, thereby improving light sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the light-sensing component has a large light-sensing area to achieve specific light sensing capability, then the light sensitivity is improved, but the electronic charges are not completely drained out causing residual charges and image sticking effect
Solution Approach 1:
The pixel sensing unit is divided into multiple sub-pixel light-sensing components (e.g., first, second, third, and fourth sub-pixel light-sensing components). Each sub-pixel has a smaller light-sensing area compared to a single large light-sensing component. This segmentation allows the converting circuit to completely drain electronic charges from each sub-pixel, preventing residual charges and image sticking effect, while the combined area of all sub-pixels maintains the required light sensitivity.
2Device complexity
If the pixel sensing unit uses a single light-sensing component, then the structure is simple, but the light sensitivity is insufficient and charge drainage is incomplete
Solution Approach 1:
Instead of using a single light-sensing component, the invention divides it into multiple sub-pixel light-sensing components (first, second, third, and fourth sub-pixels). Each sub-pixel is associated with its own converting circuit. This segmentation increases the total light-sensing area and improves light sensitivity while maintaining manageable structural complexity through systematic arrangement.
Solution Approach 2:
Each sub-pixel light-sensing component serves dual purposes: it contributes to the total light-sensing area for improved sensitivity, and its smaller size enables complete charge drainage by the converting circuit. The multiple sub-pixels work together as a unified pixel sensing unit, achieving both high light sensitivity and reliable charge drainage.
3Ease of manufacture
If the pixel sensing unit and collimator are not perfectly aligned, then the manufacturing is easier, but crosstalk exists between light paths
Solution Approach 1:
The pixel sensing unit is divided into multiple sub-pixels with smaller light-sensing areas. This segmentation reduces the impact of misalignment between the collimator and the pixel unit, as each sub-pixel has a smaller target area that is less sensitive to angular deviations. The segmented structure maintains better light path isolation even with manufacturing tolerances.
4Illumination intensity
If the light-sensing area is increased to improve light sensitivity, then more light can be captured, but the electronic charges are not easy to be completely drained out
Solution Approach 1:
The large light-sensing area is divided into multiple smaller sub-pixel light-sensing areas. Each sub-pixel has a smaller area that allows the converting circuit to completely drain electronic charges efficiently. The combined light-sensing area of all sub-pixels maintains the required light sensitivity, while the segmented structure improves charge drainage efficiency for each individual sub-pixel.
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 light sensitivity by ensuring that light is focused only on the sensing areas, reducing residual charges and crosstalk, resulting in improved image quality and reduced image sticking effects.
Implementation Method 1
the photo diode stores the electronic charges caused by the light in the potential well of the photo diode
Implementation Method 2
The collimator is configured to project the light onto the pixel sensing unit
Data Source
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AI summary
The present application provides a pixel sensing module comprising a pixel light-sensing unit, receiving light at a light receiving side and outputting a pixel value, the pixel light-sensing unit comprising a plurality of sub-pixel light-sensing components configured to output a plurality of sub-pixel values; and an integrating unit, coupled to the pixel light-sensing unit configured to output the pixel value according to the plurality of sub-pixel values; and a collimating unit having a plurality of openings, wherein the plurality of openings are aligned with an area of the pixel light-sensing unit, and projections of the plurality of openings onto the light receiving side lie within the area of the pixel light-sensing unit at the light receiving side.