Time-Gated Distance Sensing for Bad-Weather Visibility
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Solution Overview
Problem
Existing distance measuring camera systems struggle to accurately calculate distances in bad weather conditions due to light scattering from particles, requiring precise synchronization of cameras on the order of nanoseconds, which is difficult to achieve practically.
Innovation Solution
A distance measuring apparatus with a light emitter, photoelectric conversion element, and control unit that determines visibility conditions and switches range gate control based on these conditions, synchronizing light emission and exposure times to improve accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If range gate control is performed using two cameras to accurately measure distance in bad weather conditions, then measurement precision is improved, but device complexity increases due to the requirement for nanosecond-level synchronization
Solution Approach 1:
The patent combines the light source and image capturing element into a single integrated apparatus. The light emitter and photoelectric conversion element are unified in one device, eliminating the need for separate camera synchronization and reducing system complexity while maintaining distance measurement capability through the integrated structure
Solution Approach 2:
The patent employs pulsed light emission followed by timing of reflected light return. The light emitter emits light in periodic pulses, and the photoelectric conversion element measures the time interval between emission and reception, using periodic action to achieve accurate distance measurement without requiring continuous nanosecond synchronization between separate cameras
2Measurement precision
If nanosecond-level synchronization is implemented between two cameras, then measurement precision is improved, but ease of operation deteriorates due to wiring length and clock phase accuracy requirements
Solution Approach 1:
By merging the light source and detector into one apparatus, the patent eliminates the need for inter-camera synchronization wiring and clock phase coordination. The single integrated device requires no complex wiring or synchronization setup, dramatically improving ease of installation and operation while maintaining measurement precision through the unified timing mechanism
3Reliability
If light scattering from particles is captured by the camera, then visibility condition deteriorates, but the camera continues to generate image signals from scattered light
Solution Approach 1:
The patent extracts only the relevant light signals by using time-gated detection. The photoelectric conversion element is activated only during specific time windows when reflected light from the target object is expected, filtering out scattered light from particles that arrives at different times. This temporal filtering extracts useful signals while rejecting harmful scattered light interference
Solution Approach 2:
The patent uses pulsed light emission with brief duration and measures only during the specific time interval when the reflected pulse returns. By rushing through the measurement in synchronized pulses and skipping detection during other times, the system avoids capturing scattered light from particles while maintaining reliable distance measurement
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
Enables accurate distance measurement in bad weather by synchronizing light emission and exposure times, reducing the need for precise nanosecond synchronization and improving measurement accuracy.
Implementation Method 1
a light emitter 300 configured to emit pulsed light; a photoelectric conversion element 102... when calculation of a distance to an object is performed using a first photoelectric conversion signal and a second photoelectric conversion signal
Implementation Method 2
a photoelectric conversion element 102 having a plurality of pixels arranged, each pixel having a first photoelectric conversion unit configured to generate a first photoelectric conversion signal and a second photoelectric conversion unit configured to generate a second photoelectric conversion signal
Implementation Method 3
two images having a phase difference are generated by photoelectrically converting light that has passed through different pupils of an imaging optical system using a plurality of photoelectric conversion units on the image capturing surface phase difference image capturing element
Implementation Method 4
detects an amount of deviation caused by parallax of the object captured in images captured using each of the cameras, and calculates a distance to the object based on the amount of deviation
Data Source
Figure 1A~1D
Figure 2A~2C
Figure 3
AI summary
A distance measuring apparatus comprises a light emitter for emitting pulsed light in a traveling direction of a movable apparatus, a photoelectric conversion element having a plurality of pixels arranged, each pixel having a first photoelectric conversion unit configured to generate a first photoelectric conversion signal and a second photoelectric conversion unit configured to generate a second photoelectric conversion signal, wherein the first photoelectric conversion signal and the second photoelectric conversion signal have a predetermined parallax, a visibility condition determination means for determining a visibility condition of the traveling direction, and a control means for switching whether the range gate control is performed or not, based on the visibility condition, when calculation of a distance to an object using the first photoelectric conversion signal and the second photoelectric conversion signal.