Dynamic Quad Phase Angle Adjustment for 3D ToF Noise Reduction
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Solution Overview
Problem
3D time-of-flight camera systems face inaccuracies in distance calculations due to various sources of noise such as photon shot noise, pixel thermal noise, ADC noise, and ADC quantization noise.
Innovation Solution
A distance measurement system that dynamically adjusts quad phase angles to reduce noise effects, by generating modulated light signals, measuring reflected light at multiple quad phase angles, and recalculating phase angles based on initial measurements to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If fixed quad phase angles are used for measurement, then the system operation is simple, but measurement precision deteriorates due to noise
Solution Approach 1:
The patent applies dynamics by making the quad phase angles adjustable rather than fixed. The controller dynamically selects and changes the set of quad phase angles based on measured phase angles to optimize noise reduction. This transforms a static measurement system into a dynamic one that adapts to different measurement conditions, resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The patent changes the parameter of quad phase angles from fixed values to dynamically selectable values. By varying the phase angles based on the measured phase angle, the system optimizes the measurement process to reduce noise impact. This parameter change approach allows the system to improve measurement precision while managing complexity through algorithmic control.
2Measurement precision
If multiple measurement rounds with different phase angles are performed, then measurement precision improves, but measurement time increases
Solution Approach 1:
The patent applies preliminary action by first performing a measurement round with initial quad phase angles to obtain a measured phase angle. This preliminary measurement information is then used to determine optimized quad phase angles for subsequent measurement rounds. This approach allows the system to reduce noise more effectively in later rounds while minimizing the total number of measurement rounds needed, thus reducing measurement time.
Solution Approach 2:
The patent implements feedback by using the measured phase angle from one measurement round to determine the quad phase angles for the next measurement round. This feedback mechanism allows the system to adaptively optimize measurements, reducing the number of rounds needed to achieve high precision and thereby reducing overall measurement time.
3Measurement precision
If noise reduction techniques are applied, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent applies self-service by having the system use its own measurement results to optimize its subsequent measurements. The measured phase angle automatically determines the next set of quad phase angles, creating a self-optimizing system. This reduces the need for external complex control mechanisms while improving measurement precision through adaptive noise reduction.
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 dynamic adjustment of quad phase angles significantly reduces the impact of noise on distance measurements, leading to more accurate and reliable distance calculations in 3D ToF camera systems.
Implementation Method 1
3D time-of-flight (ToF) camera systems work by transmitting light with periodically varying intensity and measuring the phase of the reflected light detected by photo sensors. The amount of phase delay between the transmitted and reflected light signals is proportional to the distance between the camera system and the 3-D object.
Data Source
AI summary
A distance measurement system includes a light transmitter to generate a modulated light signal, a light sensor to generate measurement signals from reflected light among four quad phase angles with respect to a phase of the generated light signal, and a controller. The controller selects a first set of quad phase angles, and generates first measurement signals at the quad phase angles of the first set. Based on the first measurement signals, the controller computes a first phase angle between the generated light signal and the reflected light signal, generates a second set of quad phase angles based on the first phase angle, and generates second measurement signals at the quad phase angles of the second set. Further, based on the second measurement signals, the controller computes a second phase angle between the generated light signal and the reflected light signal and calculates a distance using the second phase angle.