Structured Light Imaging Pixel With Dual Storage Nodes
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Solution Overview
Problem
Conventional structured light imaging systems face challenges in capturing accurate 3D representations of objects due to degradation in depth resolution caused by varying ambient lighting conditions, as they typically rely on single storage nodes that are not optimized for handling rapidly changing scenes.
Innovation Solution
The implementation of pixels with multiple storage elements, synchronized with an illumination source that emits pulsed structured light, allows for continuous capture and storage of bright frames during light pulses and background frames between pulses, effectively interleaving them in time to suppress degradation from ambient lighting. This is achieved through the use of two or more storage nodes per pixel, enabling the subtraction of background frames from bright frames during readout, thereby enhancing depth resolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If single storage node pixels are used in conventional structured light imaging systems, then device complexity is reduced, but depth resolution degrades due to varying ambient lighting conditions
Solution Approach 1:
The pixel is divided into multiple storage nodes (first storage node, second storage node, third storage node) instead of using a single storage node. Each storage node captures light intensity information at different time points, allowing the system to separate and process ambient lighting variations from the structured light signal, thereby improving depth resolution without excessive complexity increase
Solution Approach 2:
The imaging system uses periodic pulsed structured light illumination where the illumination source emits light in pulses rather than continuously. The multiple storage nodes are synchronized to capture images at different phases of this periodic illumination cycle, enabling the system to distinguish between ambient lighting (captured in background frames) and structured light (captured in bright frames), thus resolving the depth resolution issue
2Measurement precision
If multiple storage nodes per pixel are implemented to capture bright frames and background frames, then depth resolution is enhanced, but device complexity increases
Solution Approach 1:
The pixel is divided into multiple storage nodes (first storage node, second storage node, third storage node) instead of using a single storage node. Each storage node captures light intensity information at different time points, allowing the system to separate and process ambient lighting variations from the structured light signal, thereby improving depth resolution without excessive complexity increase
Solution Approach 2:
The imaging system uses periodic pulsed structured light illumination where the illumination source emits light in pulses rather than continuously. The multiple storage nodes are synchronized to capture images at different phases of this periodic illumination cycle, enabling the system to distinguish between ambient lighting (captured in background frames) and structured light (captured in bright frames), thus resolving the depth resolution issue
3Ease of manufacture
If single storage element pixels are used, then ease of manufacture is improved, but reliability of 3D imaging under varying ambient lighting deteriorates
Solution Approach 1:
The pixel is divided into multiple storage nodes (first storage node, second storage node, third storage node) instead of using a single storage node. Each storage node captures light intensity information at different time points, allowing the system to separate and process ambient lighting variations from the structured light signal, thereby improving depth resolution without excessive complexity increase
Solution Approach 2:
The imaging system uses periodic pulsed structured light illumination where the illumination source emits light in pulses rather than continuously. The multiple storage nodes are synchronized to capture images at different phases of this periodic illumination cycle, enabling the system to distinguish between ambient lighting (captured in background frames) and structured light (captured in bright frames), thus resolving the depth resolution issue
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 significantly improves the accuracy of 3D representation by suppressing the effects of ambient lighting variations, resulting in enhanced depth resolution and more reliable 3D imaging performance.
Implementation Method 1
an image sensor having a photodiode that converts the stream after reflection by a scene to charge
Data Source
Figure 1~2
Figure 3A~3B
Figure 4A~5
AI summary
Structured light imaging method and systems are described. An imaging method generates a stream of light pulses, converts the stream after reflection by a scene to charge, stores charge converted during the light pulses to a first storage element, and stores charge converted between light pulses to a second storage element. A structured light image system includes an illumination source that generates a stream of light pulses and an image sensor. The image sensor includes a photodiode, first and second storage elements, first and second switches, and a controller that synchronizes the image sensor to the illumination source and actuates the first and second switches to couple the first storage element to the photodiode to store charge converted during the light pulses and to couple the second storage element to the photodiode to store charge converted between the light pulses.