Time-of-Flight Ranging Device With Delayed Histogram Integration
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Solution Overview
Problem
Existing time-of-flight ranging devices face challenges in achieving accurate distance measurement while balancing integration time and storage requirements, leading to increased costs and errors when objects approach each other.
Innovation Solution
A time-of-flight ranging device and method that employs a light source, sensing array, and time-to-digital converter, with adaptive integration periods and mathematical operations on histogram data to enhance accuracy without increasing storage space or total sensing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the integration time of the time-to-digital converter is decreased to improve distance resolution, then the number of bins in the histogram increases, which requires increased storage space and increases processing chip costs
Solution Approach 1:
The patent divides the measurement process into multiple integration periods with different delay times. Each integration period generates a separate histogram with fewer bins, and these histograms are then combined through mathematical operations to achieve high distance resolution without requiring a single large histogram that would consume excessive storage space.
Solution Approach 2:
The patent dynamically adjusts the delay time between integration periods to optimize the measurement process. By varying the delay times across different integration periods, the system can capture multiple histograms that, when combined, provide high resolution information without requiring each individual histogram to have a large number of bins.
2Ease of manufacture
If the integration time of the time-to-digital converter is increased to reduce processing chip costs, then the distance resolution drops and measurement error increases
Solution Approach 1:
The patent combines multiple histograms obtained from different integration periods through mathematical operations. By merging these multiple lower-resolution histograms with different delay times, the system achieves high distance resolution without requiring a single integration period with a large number of bins, thus reducing processing chip costs while maintaining measurement precision.
Solution Approach 2:
The patent performs continuous measurements across multiple integration periods, accumulating useful measurement data throughout the total measurement time. This continuous action allows the system to achieve high resolution by combining multiple measurements rather than relying on a single long integration period that would require expensive high-resolution processing.
3Measurement precision
If the number of bins in the histogram is increased to improve distance resolution, then the storage space requirement increases, leading to higher processing chip costs
Solution Approach 1:
The patent segments the histogram data collection into multiple smaller histograms obtained from different integration periods. Each smaller histogram requires less storage space and simpler processing, but when combined through mathematical operations, they provide the same or better distance resolution than a single large histogram would provide.
Solution Approach 2:
The patent dynamically varies the delay time between integration periods to optimize the distribution of measurement data across multiple histograms. This dynamic approach allows the system to achieve high resolution without requiring any single histogram to have a large number of bins, thereby reducing the complexity and cost of the processing chip.
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 solution provides accurate distance measurements by dynamically adjusting integration periods and performing mathematical operations on histogram data, resulting in improved sensing accuracy and reduced errors.
Implementation Method 1
direct time of flight (D-ToF) sensing
Implementation Method 2
a plurality of rays of reflected pulse light generated when the sensing target reflects the laser pulse signals
Data Source
AI summary
A time-of-flight ranging device and a time-of-flight ranging method are provided. The time-of-flight ranging device includes a light source, a sensing array, and a time-to-digital converter. The light source sequentially emits a plurality of laser pulse signals towards a sensing target. The sensing array senses rays of reflected pulse light generated when the sensing target reflects the laser pulse signals. The time-to-digital converter performs integration operations on a plurality of sensing results of a plurality of sensing units during a plurality of consecutive ranging periods to generate a plurality of pieces of first histogram data. The control circuit performs a mathematical operation on the pieces of first histogram data to generate second histogram data. The ranging periods have delay periods among one another, such that a plurality of periods of start time of the pieces of first histogram data are sequentially delayed by a plurality of time lengths.