Imaging Pixel Array Structure for Fast, Sensitive Event Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In solid-state imaging elements with mixed pixels for gradation and event detection, the rapidity of event detection is compromised, making it difficult to accurately detect weak changes in light intensity due to shorter exposure times for event detection pixels compared to gradation signal pixels.
Innovation Solution
The design includes a pixel array unit with first and second pixels, where the second pixel for event detection has a larger photoelectric conversion volume, a charge accumulation portion separate from the floating diffusion region, and a trench structure that increases light reflection surfaces and guides light efficiently, enhancing light receiving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the exposure time of event detection pixels is made much shorter than that of gradation signal pixels to enhance the rapidity of event detection, then the detection speed is improved, but the detection accuracy of weak changes in light amount deteriorates
Solution Approach 1:
The patent transitions from a two-dimensional pixel arrangement to a three-dimensional structure by increasing the photoelectric conversion portion volume in event detection pixels. This vertical dimension expansion allows these pixels to collect more photons during the short exposure period, improving detection accuracy without compromising detection speed. The larger volume compensates for the reduced exposure time by increasing the light collection capacity per unit time.
Solution Approach 2:
The patent applies different structural qualities to different pixel types within the same pixel array. Event detection pixels are given a larger photoelectric conversion portion volume compared to gradation signal pixels, creating local structural differentiation. This allows event detection pixels to have higher light sensitivity specifically tailored for their function, while gradation pixels maintain their original design for continuous tone capture.
2Measurement precision
If the photoelectric conversion portion volume of event detection pixels is increased to improve light receiving sensitivity, then the detection accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent segments the pixel array into distinct regions with different functional requirements. Event detection pixels are grouped together in specific regions (such as regions with higher incident light amounts) and given enlarged photoelectric conversion portions, while other pixels maintain their standard design. This segmentation allows the complexity to be localized only where needed for event detection, rather than increasing the complexity of the entire pixel array.
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 improves the light receiving sensitivity of event detection pixels, allowing for more accurate detection of light changes and increased sensitivity across a wider range, while maintaining efficient manufacturing processes.
Implementation Method 1
a first pixel for obtaining a gradation signal indicating an intensity of received light and a second pixel for detecting that a change in an amount of received light exceeds a predetermined threshold value
Data Source
AI summary
A solid-state imaging element according to the present technology includes a pixel array unit in which a plurality of pixels each having a photoelectric conversion portion is arranged, the pixel array unit includes, as the pixels, a first pixel for obtaining a gradation signal indicating an intensity of received light and a second pixel for detecting that a change in an amount of received light exceeds a predetermined threshold value, and a volume of a photoelectric conversion portion included in the second pixel is larger than a volume of a photoelectric conversion portion included in the first pixel.