Image Sensor with Split Sensitivity for Dynamic Range
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Solution Overview
Problem
Conventional image sensors have a limited dynamic range, making it difficult to capture images with both bright and dark portions effectively, as adjusting exposure time alone is insufficient to compensate for a narrow dynamic range when both strong and weak optical signals are received simultaneously.
Innovation Solution
Dividing unit sensors into high-sensitivity and low-sensitivity sensors, where the high-sensitivity sensor accumulates electric charge and the low-sensitivity sensor outputs a signal value, allowing for the determination of incident signal intensity by combining the quantity of accumulated charge and signal value from both sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If exposure time is adjusted to compensate for narrow dynamic range, then signal level can be maintained for single intensity conditions, but the sensor cannot capture both strong and weak optical signals simultaneously
Solution Approach 1:
The image sensor is divided into multiple sensor units with different sensitivity levels. Each sensor unit is further segmented into first photoelectric conversion units (higher sensitivity) and second photoelectric conversion units (lower sensitivity). This segmentation allows different portions of the scene with varying intensity levels to be captured simultaneously by appropriate sensor units, thereby expanding the overall dynamic range while maintaining signal accuracy.
Solution Approach 2:
Different sensor units are assigned different sensitivity characteristics tailored to specific local requirements. High-sensitivity sensor units are used for capturing dark regions, while low-sensitivity sensor units are used for bright regions. This local quality differentiation ensures that each region of the image is captured with optimal sensitivity, solving the contradiction between maintaining signal level accuracy and expanding dynamic range.
2Adaptability or versatility
If self-reset operation is used to expand dynamic range by accumulating electric charges multiple times, then dynamic range is expanded, but additional elements (comparator, counter, memory) are required increasing device complexity
Solution Approach 1:
The patent merges the functions of multiple sensor units with different sensitivities into a single integrated sensor structure. By combining first and second photoelectric conversion units within the same sensor unit, the system achieves expanded dynamic range capability without requiring separate comparison circuits, counters, and memory units that would be needed for multiple independent self-reset operations. The different sensitivity levels provide built-in dynamic range expansion.
Solution Approach 2:
Each sensor unit is designed to perform multiple functions: it can operate in high-sensitivity mode for dark regions, low-sensitivity mode for bright regions, and can switch between modes as needed. This multi-functionality eliminates the need for dedicated separate circuits for each sensitivity level, reducing overall device complexity while maintaining expanded dynamic range capability.
3Adaptability or versatility
If multiple sensors with different sensitivities are used to expand dynamic range, then both bright and dark portions can be captured, but the unit sensor size and number of output ports must be increased
Solution Approach 1:
Instead of expanding dynamic range by adding more sensors in the spatial dimension (which would increase unit sensor area), the patent introduces a sensitivity dimension by creating sensor units with different sensitivity levels. This allows multiple sensitivity channels to coexist within the same spatial footprint, achieving expanded dynamic range without proportionally increasing the physical area of each sensor unit.
Solution Approach 2:
The patent nests first and second photoelectric conversion units within the same sensor unit structure. The higher-sensitivity and lower-sensitivity units are integrated in a nested or shared configuration, allowing both sensitivity levels to occupy overlapping or adjacent spatial regions efficiently. This nesting approach maximizes the use of available sensor area while providing multiple sensitivity options for dynamic range expansion.
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 approach expands the dynamic range of image capture, enabling the generation of images with both bright and dark regions accurately, simplifying the structure of the image photographing apparatus by using the reset operation of both sensors to determine signal intensity.
Implementation Method 1
a sensor unit to optically sense a light beam incident on a sub-defined region of the sensor unit, of a plurality of sub-defined regions of the sensor unit, with the sub-defined region including a plurality of sensors with at least two different sensitivities, and to convert the sensed light beam into a plurality of electrical signals respectively corresponding to at least the plurality of sensors
Data Source
AI summary
An image photographing apparatus and method, and more particularly, an image photographing apparatus and method that may divide each unit sensor of an image sensor into a high-sensitivity sensor and a low-sensitivity sensor and sense an incident optical signal using the high-sensitivity sensor and the low-sensitivity sensor. The image photographing apparatus may include a light reception unit receiving an optical signal, a sensor unit sensing the optical signal, which is incident to a pixel region, using a plurality of sensors with different sensitivity and converting the sensed optical signal into a plurality of electrical signals, and a signal extraction unit extracting the quantity of accumulated electric charge for the optical signal, which was sensed by each of the sensors, with reference to each of the electrical signals.