Dual-Pixel Imaging Layout for High Dynamic Range Capture
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Solution Overview
Problem
Conventional imaging devices face challenges in achieving high dynamic range photography due to limitations in sensitivity and saturation electrons, leading to image distortion and noise issues when trying to capture both bright and dark subjects simultaneously.
Innovation Solution
The imaging device incorporates a first pixel with a low-sensitivity, high-capacitance image pickup cell for high saturation and a second pixel with high-sensitivity, low-capacitance image pickup cell, along with a feedback circuit to suppress noise, allowing for independent exposure and readout timing to extend the dynamic range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single pixel uses a photoelectric converter with large area to increase sensitivity, then sensitivity is improved, but saturation electrons are limited causing image distortion in bright regions
Solution Approach 1:
The imaging device divides a single pixel into multiple image pickup cells (first image pickup cell with small area and second image pickup cell with large area). This segmentation allows each cell to have different sensitivities and saturation characteristics, enabling the system to handle both bright and dark regions without distortion by selecting appropriate cells for different luminance levels.
Solution Approach 2:
Different regions within the pixel are assigned different photoelectric converter areas to match local luminance requirements. The first image pickup cell with smaller area is optimized for bright regions where high saturation electrons are needed, while the second image pickup cell with larger area is optimized for dark regions where high sensitivity is required. This local quality differentiation resolves the contradiction between sensitivity and image distortion.
2Reliability
If a single pixel uses a photoelectric converter with small area to increase saturation electrons, then saturation electrons are improved, but sensitivity decreases causing noise in dark regions
Solution Approach 1:
The pixel is segmented into multiple image pickup cells with different areas. The first image pickup cell has a smaller photoelectric converter area which provides higher saturation electrons for bright regions, while the second image pickup cell has a larger photoelectric converter area which provides higher sensitivity for dark regions. This segmentation resolves the contradiction between saturation electrons and sensitivity.
Solution Approach 2:
Different photoelectric converter areas are assigned to different regions within the pixel based on local luminance requirements. The smaller area in the first cell provides high saturation for bright regions, while the larger area in the second cell provides high sensitivity for dark regions, eliminating noise in dark regions while maintaining saturation in bright regions.
3Reliability
If multiple images with different exposure times are synthesized to achieve high dynamic range, then dynamic range is improved, but time consumption increases
Solution Approach 1:
Multiple image pickup cells within a single pixel simultaneously capture images with different exposure characteristics during the same exposure period. The first image pickup cell captures bright regions with shorter effective exposure, while the second image pickup cell captures dark regions with longer effective exposure. This merging of multiple cells into one pixel eliminates the need for sequential multi-exposure shooting, reducing time consumption while maintaining high dynamic range.
Solution Approach 2:
The different exposure characteristics are prepared in advance by designing image pickup cells with different photoelectric converter areas and charge storage node capacitances. This preliminary configuration allows simultaneous capture of multiple exposure levels in a single shot, eliminating the time required for sequential exposure and synthesis of multiple images.
4Reliability
If images from multiple pixels with different sensitivities are synthesized to extend dynamic range, then dynamic range is improved, but device complexity increases
Solution Approach 1:
Multiple image pickup cells with different sensitivities are merged within a single pixel structure, sharing common components such as microlenses and color filters. This integration extends dynamic range while minimizing device complexity by reusing existing pixel infrastructure rather than adding separate pixel arrays.
Solution Approach 2:
The pixel structure is designed with multi-functionality, where a single pixel performs both standard imaging and high dynamic range imaging through its multiple image pickup cells. This universal design eliminates the need for separate HDR pixel arrays, reducing device complexity while achieving extended 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
This configuration enables the capture of images with a dynamic range higher by about two and a half orders of magnitude, reducing noise and maintaining image quality by separating the sensitivity and saturation electron levels between the two pixels.
Implementation Method 1
a first photoelectric converter that converts incident light into first signal charges
Data Source
AI summary
An imaging device includes: a first pixel including a first photoelectric converter that converts incident light into first signal charges, and a first charge storage node that accumulates the first signal charges; and a second pixel including a second photoelectric converter that converts incident light into second signal charges, and a second charge storage node that accumulates the second signal charges. An area of the second photoelectric converter is greater than an area of the first photoelectric converter in a plan view. Capacitance of the first charge storage node is greater than capacitance of the second charge storage node.