Patterned ToF Illumination for Low-Power 3D Depth Sensing
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Solution Overview
Problem
Existing 3D imaging systems face challenges in achieving high precision and resilience to ambient light while maintaining low power consumption, particularly in time-of-flight systems.
Innovation Solution
Employing patterned illumination with sparse light patterns that concentrate optical power density in specific areas, disabling pixels outside the illuminated pattern to enhance signal-to-noise ratio and reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If all pixels are activated for 3D imaging, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The pixel array is divided into multiple groups or blocks, and only specific groups are activated at different time periods. This segmentation allows the system to capture depth information from different regions sequentially, maintaining overall measurement precision while reducing the number of simultaneously active pixels, thereby lowering power consumption.
Solution Approach 2:
The system activates different pixel groups in a periodic manner across multiple time periods. During each period, only a subset of pixels is active, and the illumination and detection are synchronized with this periodic activation pattern. This temporal multiplexing enables complete scene coverage over time while keeping instantaneous power consumption low.
2Measurement precision
If illumination power is increased to improve signal-to-noise ratio, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The illumination source is modulated to emit light in periodic pulses that are synchronized with the selective pixel activation. During each time period, illumination is provided only when the corresponding pixel group is active, and no illumination is provided when those pixels are inactive. This periodic illumination concentrates the energy delivery into useful measurement windows, improving signal-to-noise ratio during detection while reducing overall power consumption.
Solution Approach 2:
The system ensures that illumination is continuously provided during the periods when pixels are active and detecting, maintaining optimal signal-to-noise ratio during the useful measurement intervals. By synchronizing illumination continuity with pixel activation continuity, the system maximizes detection quality during active periods while allowing power savings during inactive periods.
3Use of energy by moving object
If sequential pixel activation is implemented to reduce power consumption, then power consumption is reduced, but measurement time increases
Solution Approach 1:
The pixel array is segmented into multiple groups that can be activated in parallel within each time period. Rather than activating pixels one at a time or in small sequential sequences, multiple pixel groups are simultaneously active during their designated periods, enabling parallel measurement of different scene regions and reducing the total time required to complete a full scene scan.
Solution Approach 2:
The system uses periodic activation patterns with sufficiently short period durations that multiple complete cycles can be executed within an acceptable measurement time window. Each period activates a specific pixel group for a brief interval, and the rapid alternation between periods allows the system to cycle through all pixel groups quickly, completing full scene coverage in minimal time while maintaining low instantaneous power consumption.
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
Enhances precision and resilience to ambient light while reducing power consumption by concentrating optical power in patterned areas, improving signal-to-noise ratio and distance accuracy.
Implementation Method 1
detecting the light pattern reflected by an object in an environment
Implementation Method 2
a time-of-flight sensor of the time-of-flight system... generating a signal based on the light detected... for generation of a representation of the environment
Data Source
AI summary
A method of operating a time-of-flight system includes projecting a light pattern from an illumination source into an environment; by an array of light sensors of a time-of-flight sensor of the time-of-flight system, detecting the light pattern reflected by an object in an environment; and generating a signal based on the light detected by a subset of the light sensors of the array of light sensors, the signal being provided to one or more processors for generation of a representation of the environment.