Coded Pulse Segmentation for Wide-Range Time-of-Flight Ranging
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Solution Overview
Problem
Conventional time of flight (TOF) ranging methods face challenges in achieving both an increase in ranging range and improvement in ranging accuracy, as increasing pulse width to extend the range decreases accuracy, and adding signal storage means to maintain accuracy is cumbersome.
Innovation Solution
A ranging device and method that utilize a pulse generator to emit light in unit segments with n types of packet generation codes, a solid-state image capturer to capture signals, and a distance calculator to calculate distances based on these signals, allowing for high accuracy and wide ranging by binarizing and comparing signal values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the pulse width of the light source is increased to extend the ranging range, then the ranging range increases, but the ranging accuracy decreases
Solution Approach 1:
The patent divides the ranging range into multiple unit segments and uses n types of packet generation codes to control light emission and exposure in each segment. This segmentation allows the system to achieve both wide ranging range and high accuracy by independently controlling measurement in each segment without being constrained by a single pulse width limitation.
2Length of stationary object
If the number of signal storage means is increased to maintain ranging accuracy while extending ranging range, then the ranging accuracy is maintained, but the device complexity increases
Solution Approach 1:
The patent employs a single solid-state image capturer that performs multiple functions by capturing images according to different exposure pulses corresponding to n types of packet generation codes. This universal approach eliminates the need for multiple dedicated signal storage means, reducing device complexity while maintaining the capability to measure both near and far distances with high accuracy.
3Measurement precision
If signal accumulation is performed using conventional methods with dedicated background light storage, then background light removal is achieved, but the ranging range is limited by the pulse width
Solution Approach 1:
The patent dynamically controls the light source and solid-state image capturer using n types of packet generation codes that adapt to different distance segments. This dynamic control allows the system to extend the ranging range beyond the limitation of fixed pulse width while maintaining background light removal capability through selective exposure and signal processing.
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 enables high ranging accuracy and a wide ranging range by controlling light emission and exposure in unit segments, effectively addressing the limitations of conventional methods.
Implementation Method 1
a light source that emits light according to the emission pulse; a solid-state image capturer that captures an image according to the exposure pulse
Implementation Method 2
One of the several known methods for detecting objects is the time of flight (TOF) method, which uses the time it takes light to travel to and from a target object to be measured
Data Source
AI summary
A ranging device includes: a pulse generator; a controller that controls the pulse generator according to n (n is an integer greater than or equal to 4) types of packet generation codes indicating whether or not to expose or emit light in each of unit segments corresponding to distance segments into which a ranging range is divided; a light source; a solid-state image capturer; and a distance calculator that calculates the distance based on n types of signal values per unit segment obtained from the solid-state image capturer.