Time-of-Flight Light Distance Measurement with Multi-Interval Capture
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Solution Overview
Problem
Traditional time-of-flight distance measurement techniques using light face challenges in accurately determining distances, especially in environments with varying light conditions and complex surface movements, due to limitations in capturing and processing light pulses.
Innovation Solution
The system employs a plurality of light sensors with storage elements that capture light pulses at different time intervals, calculating distance based on phase differences and ratios of stored energy, using a comparator/limiter circuit to prevent over-saturation and enhance accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional time-of-flight light measurement is used, then distance measurement is achieved, but measurement precision deteriorates in environments with varying light conditions and complex surface movements
Solution Approach 1:
The patent divides the measurement process into multiple discrete time intervals (first time interval, second time interval, third time interval) for capturing light pulses. By segmenting the measurement into phased intervals and comparing results across these segments, the system achieves more precise distance measurement that is resistant to varying light conditions and surface movements.
2Length of stationary object
If light capture is extended to improve measurement range, then measurement range increases, but aliasing issues worsen
Solution Approach 1:
The patent employs periodic light pulse emission and capture at specific intervals. By using periodic action with defined time intervals between pulses and captures, the system extends measurement range while maintaining reliability by preventing aliasing through the structured temporal pattern of light emission and detection.
Solution Approach 2:
The system uses feedback by comparing light capture amounts across multiple time intervals. The comparison of captured light from different intervals provides feedback that enables the system to determine accurate distance measurements and identify surface movements, thereby maintaining measurement reliability across extended ranges.
3Measurement precision
If multiple light sensors are used to improve measurement accuracy, then measurement accuracy improves, but device complexity increases
Solution Approach 1:
The patent makes each light sensor multi-functional by having it capture light pulses during multiple different time intervals. Each sensor serves universal purposes: capturing light in the first interval, second interval, and third interval, thereby contributing to multiple measurement aspects without requiring separate dedicated sensors for each function, thus reducing overall device complexity.
Solution Approach 2:
The patent merges the functions of multiple measurements into a unified system where light sensors and processing circuits work together in an integrated manner. By combining the capture of light at different intervals and processing these signals through a unified comparison mechanism, the system achieves high measurement accuracy while managing device complexity through functional integration.
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 allows for precise distance measurement and surface profiling, enabling effective identification of movement and location of objects, even in complex environments, by overcoming aliasing issues and improving measurement range and accuracy.
Implementation Method 1
A distance between objects can be measured by emitting light and measuring a time-of-flight of the light between the objects
Implementation Method 2
A phase difference in the captured pulses of light may be determined based on an amount of light captured at different time intervals during a cycle of the predetermined frequency
Data Source
AI summary
In some embodiments, a distance between the at least one light sensor and the surface may be calculated using a ratio representative of the phase difference using time-of-flight of light. The distance may be within a distance range defined by a distance of light travel during a modulation period of the predetermined frequency. The distance may be based on the ratio defined by an amount of energy stored from captured light during a first time interval and a second time interval, and a comparison of an amount of light stored from captured light during at least a third time interval. The first, second, and third time intervals are different, but may overlap in some instances. In some embodiments, the amount of ambient light may be identified and subtracted from the inputs of the ratio. A switch may be used to prevent oversaturation of a storage element storing the stored energy.