Offset Microlens Array Layout for Oblique-Light Image Sensors
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Solution Overview
Problem
Image sensors face inefficiencies in photoelectric conversion due to varying incident angles of light, causing misalignment of focus within pixels, which affects conversion efficiency.
Innovation Solution
The image sensor design includes a microlens array layer with offset microlenses and varying inclinations based on incident angles, ensuring focused light is directed to the corresponding pixel regions, enhancing photoelectric conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If microlenses are positioned directly above pixel regions with uniform inclination, then manufacturing is simple, but photoelectric conversion efficiency deteriorates due to light focusing errors at oblique incident angles
Solution Approach 1:
The patent applies local quality by making microlenses have different inclinations based on their position in the array. Central microlenses have smaller inclinations while peripheral microlenses have larger inclinations, with each microlens inclined toward the optical axis. This local differentiation compensates for oblique light incidence at different positions, improving photoelectric conversion efficiency without requiring completely complex manufacturing processes.
Solution Approach 2:
The patent changes the inclination parameter of microlenses based on their position in the array. By varying the inclination angle from center to periphery and adjusting the offset distance, the optical path is optimized for different incident angles. This parameter adjustment allows uniform light focusing across the entire sensor array while maintaining a manageable structural complexity.
2Manufacturing precision
If microlenses are offset from pixel regions, then light focusing accuracy improves for oblique incident angles, but manufacturing precision deteriorates due to alignment difficulty
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-setting the optimal offset distance and inclination angle for each microlens based on the sensor's field of view and incident angle characteristics. This preliminary design phase establishes the exact positioning requirements, which then guides the manufacturing process. The offset distance and inclination are determined in advance to compensate for oblique light incidence, improving focusing accuracy while providing clear manufacturing specifications.
Solution Approach 2:
The patent introduces an additional dimensional parameter by tilting microlenses in the vertical dimension rather than only adjusting horizontal positioning. By adding the inclination angle as a new degree of freedom, the system can compensate for oblique incident angles more effectively. This dimensional change allows light focusing accuracy to improve without requiring extremely precise horizontal alignment, thus easing manufacturing constraints.
3Device complexity
If uniform microlens inclination is used across the array, then device complexity is low, but photoelectric conversion efficiency deteriorates at peripheral pixel regions
Solution Approach 1:
The patent applies local quality by making microlenses have different inclinations based on their position in the array. Central microlenses have smaller inclinations while peripheral microlenses have larger inclinations, with each microlens inclined toward the optical axis. This local differentiation compensates for oblique light incidence at different positions, improving photoelectric conversion efficiency without requiring completely complex manufacturing processes.
Solution Approach 2:
The patent applies asymmetry by breaking the uniformity of microlens inclination across the array. Instead of all microlenses having the same inclination, the patent creates an asymmetric distribution where inclination angles vary from center to periphery. This asymmetric configuration matches the asymmetric incident angle distribution in real imaging scenarios, improving overall system performance while maintaining reasonable device complexity.
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 design improves photoelectric conversion efficiency by aligning incident light with the optimal focus areas within each pixel, thereby increasing the sensor's overall performance.
Implementation Method 1
a microlens array layer on the substrate region, the microlens array including a first microlens and a second microlens respectively corresponding to the first pixel region and the second pixel region
Data Source
AI summary
An image sensor that includes a substrate region including first and second pixel regions; and a microlens array layer on the substrate region and including a first microlens and a second microlens respectively corresponding to the first and second pixel regions. The first pixel region and the second pixel region are respectively adjacent to a center and an edge of the microlens array layer. The first microlens is offset from the first pixel region and has a first inclination. The second microlens is offset from the second pixel region and has a second inclination greater than the first inclination. A degree to which the first and second microlenses are offset from the first and second pixel regions, and the first and second inclinations are based on an incident angle of incident light to the first and second microlenses.