Time-of-Flight Camera Depth Motion Detection
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Solution Overview
Problem
Conventional methods for detecting depth motion using 3D cameras are slow and relatively inaccurate, as they rely on successive 3D images to determine motion towards or away from the image sensor.
Innovation Solution
A time-of-flight camera system that includes a light emitter, photodetector, and charge storage elements, which emits light pulses, detects reflections, and measures phase-shifts in the reflected light signals to determine depth motion, allowing for accurate and efficient detection of depth motion with each light pulse.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional methods use successive 3D images to detect depth motion, then depth motion detection is achieved, but the detection speed is slow and accuracy is relatively low
Solution Approach 1:
The system uses periodic light pulse emission with specific duty cycles (e.g., 50% duty cycle where light is emitted for half the period and blocked for the other half) to create time-gated measurements. Multiple phase-shifted light pulses are emitted sequentially, and reflected light is detected during specific time windows corresponding to each phase, enabling rapid depth motion detection without requiring multiple successive 3D images.
Solution Approach 2:
The patent replaces conventional mechanical or sequential image-based depth motion detection with an optical phase-shift measurement system. By measuring the phase difference of reflected light pulses relative to emitted pulses, the system directly calculates depth motion at high speed with improved accuracy, substituting the slow successive image acquisition method.
2Productivity
If light pulses are emitted continuously to improve detection speed, then detection accuracy decreases due to motion artifacts
Solution Approach 1:
The system employs periodic light pulse emission with controlled duty cycles, emitting light pulses at specific phases (e.g., 0°, 90°, 180°, 270°) within each period. By gating the detection to specific time windows corresponding to each phase and using appropriate duty cycles, the system achieves both high detection speed and maintains accuracy by preventing motion artifacts through synchronized emission and detection timing.
Solution Approach 2:
The system measures the phase shift of reflected light pulses relative to the emitted pulses and uses this feedback to determine depth motion. By continuously monitoring phase changes across multiple periodic cycles and comparing measurements, the system can detect depth motion accurately while maintaining high detection speed, using the phase information as feedback to correct for or account for motion effects.
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
Enables rapid and precise determination of depth motion, improving image quality by correcting motion artifacts and providing detailed motion information, thus overcoming the limitations of conventional methods.
Implementation Method 1
depth motion determination via time-of-flight camera
Implementation Method 2
determine a first phase-shift of the reflected light signal based on the first plurality of accumulated charges, wherein the first phase-shift indicates a depth motion of an object reflecting the first light pulse
Implementation Method 3
a photodetector configured to detect reflections of the one or more light pulses and generate a reflected light signal based on the detected reflections
Data Source
AI summary
A time-of-flight camera includes a light emitter, a photo detector, and a controller. The time-of-flight camera may determine depth motion of an object by emitting light pulses, receiving reflected light pulses from the object, and accumulating a plurality of charges based on the reflected light pulses. The depth motion may be determined by the controller through analysis of the accumulated charges.