Optical Element Layout for Wide Dynamic Range Image Sensors
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Solution Overview
Problem
Existing imaging apparatuses face challenges in improving dynamic range while maintaining light utilization efficiency due to the aperture ratio and light utilization efficiency issues associated with multiple photodiodes.
Innovation Solution
An optical element with a transparent layer that guides incident light to first and second photoelectric conversion elements, where the transparent layer includes distinct regions with different structures, allowing for efficient light condensation and distribution between the elements, thereby improving dynamic range and light utilization efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple photodiodes are provided in one pixel to improve dynamic range, then the dynamic range is improved, but the aperture ratio is lowered and light utilization efficiency is reduced
Solution Approach 1:
The pixel is segmented into multiple photodiodes with different light-receiving areas, where a first photodiode has a larger area for high sensitivity and a second photodiode has a smaller area for low sensitivity. This segmentation allows simultaneous capture of both bright and dark scene details, improving dynamic range while maintaining overall light utilization efficiency through optimized area distribution.
Solution Approach 2:
Different regions within the pixel are assigned different light-receiving characteristics. The first photodiode is designed with larger light-receiving area for capturing dim light in dark regions, while the second photodiode has smaller area for capturing bright light in bright regions. This local quality differentiation resolves the contradiction between improving dynamic range and maintaining light utilization efficiency.
2Loss of energy
If a large photodiode is used to improve light utilization efficiency, then light utilization efficiency is improved, but the dynamic range is reduced due to saturation in bright regions
Solution Approach 1:
The pixel is divided into multiple photodiodes with different light-receiving areas. The first photodiode with larger area captures light from dark regions with high efficiency, while the second photodiode with smaller area captures light from bright regions without saturation. This segmentation enables the system to maintain high light utilization efficiency while expanding the dynamic range.
Solution Approach 2:
Different photodiodes within the same pixel are assigned different light-receiving characteristics based on local requirements. The first photodiode is optimized for dark region detection with larger area, while the second photodiode is optimized for bright region detection with smaller area. This local quality approach allows the system to achieve both high light utilization efficiency and wide dynamic range.
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 solution achieves both improved dynamic range and light utilization efficiency by ensuring that the first photoelectric conversion element is less saturated than the second, allowing for high sensitivity and efficient light use, with the light utilization efficiency approaching 100%.
Implementation Method 1
a transparent layer which covers a pixel including a first photoelectric conversion element and a second photoelectric conversion element... the transparent layer includes a first region which guides incident light to the first photoelectric conversion element, and a second region which guides incident light to the second photoelectric conversion element
Implementation Method 2
a pixel including a first photoelectric conversion element and a second photoelectric conversion element... generate an image signal based on an electric signal obtained from the imaging element
Data Source
AI summary
An optical element includes a transparent layer which covers a pixel including a first photoelectric conversion element and a second photoelectric conversion element; and a plurality of structures disposed on the transparent layer or in the transparent layer in a plane direction of the transparent layer, in which the transparent layer includes a first region which guides incident light to the first photoelectric conversion element, and a second region which guides incident light to the second photoelectric conversion element, the plurality of structures are disposed in at least the second region among the first region and the second region, and the first region is smaller than the second region.