Time-of-Flight Distance Measurement Ambient Light Filtering
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Solution Overview
Problem
Existing electronic apparatuses face challenges in accurately measuring distance due to errors caused by ambient light interference, which affects the time-of-flight (ToF) measurement and subsequently the accuracy of distance calculation.
Innovation Solution
The electronic apparatus employs a light receiving unit with multiple optical receivers and a processing unit that calculates the time-of-flight by selecting a time zone with a higher density of reflected light photons, reducing the influence of ambient light and enhancing the accuracy of distance measurement using the formula d = ToF * c, where c is the speed of light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-of-flight measurement is performed using all detected light signals, then measurement speed is maintained, but measurement precision deteriorates due to ambient light interference
Solution Approach 1:
The patent segments the detected light signals into different groups based on their temporal characteristics. By dividing the measurement period into multiple time bins and analyzing the distribution of photon arrival times, the system can distinguish reflected light signals from ambient light signals. This segmentation enables selective processing of valid distance measurement data while filtering out ambient light interference, thereby improving measurement precision without requiring complex hardware modifications.
2Measurement precision
If multiple optical receivers are used to detect light signals, then measurement precision improves through signal differentiation, but device complexity increases
Solution Approach 1:
The patent implements a processing unit that performs multiple functions using the same hardware components. The processing unit not only calculates time-of-flight measurements but also analyzes the temporal distribution of photon arrival times, identifies ambient light interference patterns, and filters invalid signals. This multi-functional approach allows the system to achieve high measurement precision through sophisticated signal processing while avoiding the need for additional specialized hardware, thus controlling device complexity.
3Measurement precision
If ambient light filtering is applied to improve measurement accuracy, then measurement precision improves, but loss of time occurs in signal processing
Solution Approach 1:
The patent performs preliminary analysis of light signal temporal characteristics during the measurement process itself. By continuously monitoring the distribution of photon arrival times and identifying patterns indicative of ambient light interference in real-time, the system can immediately filter invalid signals without requiring post-processing. This preliminary action approach ensures that time-consuming filtering operations are integrated into the measurement process, minimizing additional processing time while maintaining high measurement precision.
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 improves the accuracy of distance measurement by distinguishing and prioritizing the reflected light signal, thereby reducing errors and enhancing the precision of distance calculation.
Implementation Method 1
measuring unit configured to measure times from an emission of the pulsed light to detections of the reception light
Data Source
AI summary
An electronic apparatus capable of determining a distance to an object based on reflected light provided by a reflection of pulsed light on the object has detectors configured to detect reception light to measure times from an emission of the pulsed light to detections of the reception light; and processing circuitry configured to determine a duration in which the reflected light is received based on the times, determine, based on one of the times in the duration, a reception timing of the reflected light included in the reception light, and determine the distance from the electronic apparatus to the object according to the reception timing of the reflected light.