Sub-Pixel Lens Array for Wide Dynamic Range Image Sensors
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Solution Overview
Problem
Current image sensors face challenges in achieving improved image quality across varying luminance levels due to limitations in dynamic range and light sensitivity, particularly in low-light conditions.
Innovation Solution
The image sensor design incorporates a pixel structure with two sub-pixels of different sizes and micro lenses, where the first sub-pixel has a larger area and a micro lens with a depression, and the second sub-pixel has a smaller area and a single micro lens, optimizing light reception and sensitivity across different luminance levels by adjusting the lens array configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single uniform micro lens structure is used for all pixels, then the device complexity is low and manufacturing is easy, but the image quality and dynamic range cannot be optimized for different luminance levels
Solution Approach 1:
The pixel array is divided into two types of pixels (first pixels and second pixels) with different micro lens configurations. The first pixels have micro lenses with depressions while the second pixels have conventional micro lenses, allowing optimized light reception for different luminance levels without requiring complete redesign of all pixels
Solution Approach 2:
Different micro lens structures are applied to different pixel locations based on their functional requirements. The first pixels with depression-type micro lenses are positioned where enhanced light sensitivity is needed, while second pixels with standard micro lenses are positioned elsewhere, creating local optimization without uniform complexity throughout the entire array
2Use of energy by moving object
If larger micro lenses are used to increase light sensitivity, then low-light performance improves, but the dynamic range is reduced and overexposure occurs in bright conditions
Solution Approach 1:
The pixel array is segmented into two types with different micro lens characteristics. First pixels have larger micro lenses with depressions that enhance light sensitivity for low-light conditions, while second pixels have smaller conventional micro lenses that prevent overexposure in bright conditions, together providing extended dynamic range
Solution Approach 2:
The micro lens parameters (size, shape, presence of depression) are changed between different pixel types to optimize performance. First pixels use larger lenses with depression features for enhanced sensitivity, while second pixels use smaller standard lenses for balanced performance, allowing the system to handle varying luminance levels effectively
3Use of energy by moving object
If multiple micro lenses are used per sub-pixel area to improve light reception, then the light sensitivity increases, but the manufacturing precision and alignment difficulty increase
Solution Approach 1:
Each sub-pixel area is segmented into multiple micro lenses arranged in specific patterns (e.g., 2x2 grids). This segmentation allows light to be collected from multiple angles and focused onto the photodiode, improving light reception while maintaining manageable manufacturing complexity through standardized repeating units
Solution Approach 2:
Multiple micro lenses are merged within each sub-pixel area to work together as a unified light collection system. The combined effect of multiple lenses improves light reception efficiency while the lenses are positioned and sized to maintain compatibility with standard manufacturing processes
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 the dynamic range and light sensitivity, allowing for improved image quality by effectively capturing a wider range of light intensities, thereby addressing the limitations of existing image sensors.
Implementation Method 1
The photodiode may serve to convert incident light thereto into an electrical signal
Implementation Method 2
a lens array including a first sub-lens area on the first sub-pixel of each unit pixel and a second sub-lens area on the second sub-pixel of each unit pixel
Data Source
AI summary
In one embodiment, an image sensor includes unit pixels, each of the unit pixel including a first sub-pixel and a second sub-pixel adjacent to the first sub-pixel in a plan view of the image sensor; and a lens array including a first sub-lens area on the first sub-pixel of each unit pixel and a second sub-lens area on the second sub-pixel of each unit pixel. The first sub-lens area may include a first micro lens, and the second sub-lens area includes a second micro lens. In addition, the first micro lens may include a depression defined in a central area thereof.