Laser Range Finder Erroneous Detection Restraining Circuit
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Solution Overview
Problem
Existing laser range finders face challenges in accurately distinguishing between human bodies and fog or dirt on the cover, leading to erroneous detection and reduced precision in adverse weather conditions.
Innovation Solution
An erroneous detection restraining circuit for laser range finders that adjusts the threshold and amplification factor of the comparator based on time measurement values, preventing close-range erroneous detection by differentiating between fog and human bodies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed threshold is used for detection, then the device complexity is low, but the measurement precision deteriorates due to inability to distinguish fog from human bodies
Solution Approach 1:
The patent applies dynamics by making the threshold and amplification factor time-dependent rather than fixed. The threshold is dynamically adjusted based on the elapsed time since laser emission, with different threshold values applied at different time intervals. This dynamic adjustment allows the system to distinguish between close-range fog reflections and distant human body reflections, improving detection precision without requiring complex additional hardware.
Solution Approach 2:
The patent changes the parameter values of the comparator threshold and amplification factor based on time measurement. By varying these parameters according to the time elapsed since laser emission, the system can differentiate between reflections from different distances. This parameter change strategy enables precise detection of human bodies while filtering out fog interference, resolving the contradiction between simplicity and precision.
2Area of stationary object
If close-range detection is enabled, then the detection area is expanded, but erroneous detection increases due to fog and dirt reflections
Solution Approach 1:
The patent applies preliminary action by pre-setting time-dependent threshold values and amplification factors that are automatically applied based on the time elapsed since laser emission. This preliminary configuration allows the system to automatically differentiate between close-range fog reflections and distant human body reflections, enabling expanded detection area while maintaining high reliability by preventing erroneous detection of fog as human bodies.
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
Simplifies the process of identifying human bodies by reducing the need for complex differentiation between fog and human bodies at close range, enhancing detection precision and reliability in foggy conditions.
Implementation Method 1
a light receiving element for receiving the reflected light and for outputting a light-reception output according to an amount of received light
Implementation Method 2
distance information to the at least one object is acquired based on an amount of time from a light emission starting time for the pulsed laser light to an output starting time from the light receiving element
Data Source
AI summary
In a laser range finder, each reflected light reflected by at least one object of pulsed laser light emitted by a light emitting element reaches a light receiving element, and distance information to the at least one object is acquired based on an amount of time from a light emission starting time for the pulsed laser light to an output starting time from the light receiving element. An erroneous detection reducing circuit for the laser range finder includes: a comparator receiving as inputs a threshold and a light-reception output from the light receiving element; a time measuring section measuring time elapsed since the light emission starting time for the pulsed laser light; and a setting changing section changing either one or both of the threshold and an amplification factor of the comparator for the light-reception output in accordance with a time measurement value obtained by the time measuring section.