Image Sensor Combining Spatial and Temporal Exposure Multiplexing
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Solution Overview
Problem
Conventional image sensors often fail to capture detailed images in scenes with varying lighting conditions due to their limited dynamic range, resulting in loss of details in shadows or overexposed areas.
Innovation Solution
The image sensor combines high dynamic range techniques such as spatial exposure multiplexing, temporal exposure multiplexing, and dual gain operation to generate images with a 20+ bit dynamic range, allowing for improved rendering of high contrast scenes by varying exposure times and gains across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional image sensors are used to capture images in scenes with varying lighting conditions, then the device complexity remains low, but the measurement precision and dynamic range are insufficient, resulting in loss of details in shadows or overexposed areas
Solution Approach 1:
The pixel array is divided into multiple regions, each with different exposure times. Specifically, a first region captures images with a first exposure time while a second region captures images with a second exposure time, allowing simultaneous capture of both bright and dark scene details within the same frame period
Solution Approach 2:
The patent introduces a spatial dimension to exposure time variation by implementing different exposure times across different spatial regions of the pixel array. This spatial multiplexing approach enables high dynamic range capture without requiring sequential temporal measurements, thus avoiding motion artifacts while expanding the measurable dynamic range
2Measurement precision
If temporal exposure multiplexing is used to increase dynamic range, then the dynamic range improves, but motion artifacts increase due to capturing multiple frames at different times
Solution Approach 1:
The pixel array is segmented into multiple regions that simultaneously capture different exposure times within the same frame period. This spatial segmentation eliminates the need for temporal sequencing, thereby preventing motion artifacts while achieving high dynamic range through parallel measurement
Solution Approach 2:
The patent maintains continuous capture of the scene by having all pixels exposed simultaneously during their respective time periods within a single frame period. This continuous spatial measurement approach avoids the discontinuous temporal sampling that causes motion artifacts, ensuring reliable image quality even in dynamic scenes
3Measurement precision
If multiple exposure times are captured sequentially to achieve high dynamic range, then the dynamic range increases, but the power consumption increases due to repeated readout operations
Solution Approach 1:
The pixel array is divided into regions with different exposure times that are all read out within a single frame period. This spatial segmentation allows simultaneous capture of multiple exposure levels without requiring multiple sequential readout operations, thereby reducing power consumption while maintaining high dynamic range capability
Solution Approach 2:
The patent implements continuous capture and single readout by having all pixel regions exposed and read out within one frame period. This eliminates the repeated readout operations required by temporal multiplexing methods, significantly reducing power consumption while maintaining the ability to capture high dynamic range scenes
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 enhances the dynamic range of image sensors, reducing motion artifacts and power consumption while enabling the capture of detailed images in a wider range of lighting conditions, achieving up to 120 dB dynamic range.
Implementation Method 1
CMOS image sensors include an array of pixels, each of which can comprise a photodetector. CMOS image sensors also include circuitry to convert light energy to an analog voltage
Data Source
AI summary
Various technologies described herein pertain to combining high dynamic range techniques to enable rendering higher dynamic range scenes with an image sensor. The image sensor can implement a combination of spatial exposure multiplexing and temporal exposure multiplexing, for example. By way of another example, the image sensor can implement a combination of spatial exposure multiplexing and dual gain operation. Pursuant to another example, the image sensor can implement a combination of temporal exposure multiplexing and dual gain operation. In accordance with yet another example, the image sensor can implement a combination of spatial exposure multiplexing, temporal exposure multiplexing, and dual gain operation.