Nano-Photonic Microlens Array for Small-Pixel Image Sensors
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Solution Overview
Problem
As image sensor resolution increases, the degradation of image quality in low-light environments and the need for improved auto-focusing become significant challenges due to the reduction in pixel size and the inefficiency of light utilization.
Innovation Solution
An image sensor incorporating a nano-photonic microlens array with a two-dimensional arrangement of nano-structures that condense light and include isolation structures for photosensitive cells, enhancing light utilization and auto-focusing capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the image sensor is increased, then the image quality in low-light environment deteriorates
Solution Approach 1:
Each pixel is divided into multiple photosensitive cells (e.g., four cells in a 2×2 arrangement), allowing the sensor to capture light more efficiently while maintaining high resolution. The segmentation enables each cell to contribute to the overall signal, improving low-light performance without sacrificing resolution.
Solution Approach 2:
The patent introduces a vertical dimension by stacking multiple photosensitive cells within each pixel location, transitioning from a two-dimensional pixel array to a three-dimensional structure. This allows multiple cells to capture light from different angles or wavelengths, improving light utilization efficiency.
2Measurement precision
If the pixel size is decreased, then the light utilization efficiency deteriorates
Solution Approach 1:
Each pixel is segmented into multiple photosensitive cells, allowing the small pixel area to be utilized more effectively. Each cell captures a portion of the incident light, and their combined signals provide sufficient light utilization efficiency despite the small overall pixel size.
Solution Approach 2:
Multiple photosensitive cells are nested within each pixel structure, with isolation structures organizing them in a compact arrangement. This nesting allows maximum light capture within the constrained pixel area.
3Loss of energy
If multiple photosensitive cells are bound to form one pixel, then the auto-focusing function deteriorates
Solution Approach 1:
The pixel is segmented into multiple photosensitive cells that can independently sense light, enabling phase-detection auto-focusing by comparing signals from different cells. The segmentation provides both improved light utilization and preserved auto-focusing capability.
Solution Approach 2:
The multiple photosensitive cells provide feedback signals that are processed to generate auto-focusing information. By comparing the signals from different cells, the system can determine focus accuracy and adjust accordingly.
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
The nano-photonic microlens array improves light efficiency and auto-focusing performance by optimizing light phase profiles and pixel arrangements, leading to enhanced image quality in various lighting conditions.
Implementation Method 1
a nano-photonic microlens array arranged to face a light incident surface of the sensor substrate, the nano-photonic microlens array including a plurality of nano-photonic microlenses configured to condense the incident light
Implementation Method 2
each nano-photonic microlens of the plurality of nano-photonic microlenses includes a plurality of nano-structures that are configured to output light having a convex phase profile
Implementation Method 3
a plurality of photosensitive cells that are two-dimensionally arranged in a first direction and a second direction perpendicular to the first direction and are configured to independently sense the incident light
Data Source
AI summary
An image sensor includes a sensor substrate including a plurality of pixels for sensing incident light, and a nano-photonic microlens array arranged to face a light incident surface of the sensor substrate, and including a plurality of nano-photonic microlenses for condensing incident light. Each of the plurality of pixels includes a plurality of photosensitive cells that are two-dimensionally arranged in a first direction and a second direction perpendicular to the first direction and are configured to independently sense the incident light, and an isolation for electrically isolating the plurality of photosensitive cells, each of the nano-photonic microlenses includes a plurality of nano-structures that are arranged such that the light transmitting each of the nano-photonic microlenses has a convex phase profile, and the plurality of nano-structures are arranged in the form of a two-dimensional array in a diagonal direction between the first direction and the second direction.