3D Imaging Sensor Decision Tree Pulse Selection
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Solution Overview
Problem
Existing 3D imaging sensor devices using direct time-of-flight measurements face challenges in achieving high uniformity, low pile-up distortion, and efficient resource sharing, particularly in LIDAR systems, which often result in tradeoffs between pixel count and detection speed, and are prone to interference and high power consumption.
Innovation Solution
A 3D imaging sensor device with a decision tree-based pulse selection unit and a shared time-to-digital converter, where each detector unit selects the earliest detection signal pulse using a first-come win-all policy, allowing continuous operation of the time-to-digital converter and reducing skew, and providing virtually calibration-free operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If resource sharing is implemented in 3D imaging sensor devices, then device complexity is reduced, but detection speed and pixel count performance deteriorate
Solution Approach 1:
The decision tree is segmented into multiple stages with decision makers at each stage, allowing parallel processing of detection signals from multiple detector units. This segmentation enables the system to handle multiple pixels simultaneously while sharing the time-to-digital converter resource, thus maintaining detection speed while reducing device complexity.
Solution Approach 2:
The decision tree performs preliminary selection of the earliest detection signal pulse before it reaches the shared time-to-digital converter. By pre-selecting which signal to process first, the system prepares the data flow in advance, allowing the shared converter to operate continuously without waiting or idle time, thereby maintaining high detection speed with reduced complexity.
2Quantity of substance
If multiple detection signals are processed simultaneously, then pixel count increases, but pile-up distortion increases
Solution Approach 1:
The decision tree performs preliminary selection to identify and select only the earliest detection signal pulse from multiple simultaneous signals before they reach the time-to-digital converter. This pre-selection prevents multiple signals from being processed at the same time in the converter, eliminating pile-up distortion while allowing the system to accept inputs from multiple detector units (high pixel count).
Solution Approach 2:
The decision tree acts as an intermediary between multiple detector units and the single time-to-digital converter. It mediates the multiple detection signals by selecting only the earliest one, thus preventing the converter from being overwhelmed by simultaneous signals and eliminating pile-up effects while maintaining support for multiple pixels.
3Productivity
If time-to-digital converter operates continuously, then detection speed improves, but power consumption increases
Solution Approach 1:
The decision tree extracts and selects only the earliest detection signal pulse from multiple simultaneous signals before passing it to the time-to-digital converter. This extraction allows the converter to operate continuously without idle time (maintaining high detection speed) while processing only one signal at a time (reducing power consumption compared to processing all signals simultaneously).
Solution Approach 2:
By having the decision tree continuously pre-select the earliest signal, the time-to-digital converter can operate continuously without waiting for signal arrival or being reset between detections. This continuous operation improves detection speed while the converter processes only one signal at a time, optimizing power consumption.
4Measurement precision
If skew is reduced in signal propagation, then measurement precision improves, but device complexity increases
Solution Approach 1:
The decision tree is segmented into stages where each decision maker handles a specific comparison task. This segmentation allows each stage to be optimized for minimal propagation delay and uniform timing, reducing skew in signal propagation. The modular structure achieves high measurement precision without requiring a monolithic complex circuit.
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
The solution enables high uniformity and low dead time between detections, maintaining performance with reduced power dissipation and calibration efforts, while effectively handling multiple detection signals and providing accurate distance information.
Implementation Method 1
Each of the plurality of detector units is associated to one of a plurality of single-photon avalanche diodes
Implementation Method 2
single-photon avalanche diodes (SPAD)
Implementation Method 3
direct time-of-flight measurement for light signal pulses
Data Source
AI summary
A photon detecting 3D imaging sensor device for detecting a distance information for pixels in an image includes an array of detector units. Each detector unit is configured to receive a light signal pulse and to provide a detection signal pulse on receipt of the light signal pulse. The 3D imaging device further includes a pulse selection unit including a decision tree with one or more stages. Each of the stages has one or more decision makers which are cascaded to propagate the earliest detection signal pulse of one of a respective detector unit as a timing signal. The 3D imaging device further includes a time-to-digital converter configured to receive the timing signal and to provide a time stamp depending on the timing signal. The time stamp indicates the distance information for a pixel of the image.