Distance Measuring Device Foreign Material Detection
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Solution Overview
Problem
Existing distance measuring devices face errors and measurement failures due to foreign materials on the protection cover, which can cause abnormalities in light transmission and reception, leading to inaccurate distance calculations.
Innovation Solution
A distance measuring device with a mode switch that adjusts light emission intensity or photodiode gain factor to detect variations in reflected light, allowing for the determination of foreign materials on the protection cover, and includes a cleaner to remove them.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the light emission intensity is increased to improve distance measurement sensitivity, then the measurement precision is improved, but foreign material on the protection cover causes abnormal reflections that lead to measurement errors
Solution Approach 1:
The patent applies dynamics by making the light emission intensity adjustable rather than fixed. The light emission intensity adjuster dynamically changes the intensity based on operational requirements, allowing the system to use high intensity for normal distance measurement and low intensity for foreign material detection, thus resolving the contradiction between measurement sensitivity and reliability
Solution Approach 2:
The patent changes the parameter of light emission intensity to detect foreign material. By adjusting the light emission intensity to a lower level, the system can distinguish variations in reflected light intensity caused by foreign material on the protection cover, thereby improving reliability without sacrificing measurement capability
2Measurement precision
If the gain factor of the photodiode is increased to detect weak reflected light, then the measurement precision is improved, but the ability to detect foreign material on the protection cover deteriorates
Solution Approach 1:
The patent makes the photodiode gain factor dynamically adjustable through the voltage adjuster. The system can switch between high gain for detecting weak reflected light from distant objects and low gain for detecting the intensity variations caused by foreign material, thus resolving the contradiction between measurement precision and foreign material detection capability
Solution Approach 2:
The patent changes the electrical parameter (voltage applied to photodiode) to control the gain factor. By adjusting this parameter, the system optimizes the photodiode's response characteristics for different detection scenarios, enabling both high sensitivity measurement and effective foreign material detection
3Reliability
If a protection cover is added to protect the light emitter and receiver, then the reliability of the device is improved, but foreign material accumulation on the cover causes measurement errors
Solution Approach 1:
The patent converts the harmful effect of foreign material on the protection cover into a detectable signal. By analyzing variations in reflected light intensity, the system uses the presence of foreign material as an indicator to trigger cleaning operations, thus transforming a harmful factor into a useful detection mechanism that maintains long-term reliability
Solution Approach 2:
The system performs self-diagnosis by detecting foreign material on its own protection cover through optical measurements. The distance measuring device autonomously identifies contamination and initiates cleaning without external intervention, maintaining its own reliability through self-service
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 detection and removal of foreign materials, ensuring high sensitivity and reliability in distance measurements by distinguishing reflected light from the protection cover and foreign materials.
Implementation Method 1
a photoelectric conversion element including a photodiode that performs photoelectric conversion on the received reflected light to generate a light reception signal
Implementation Method 2
a light emitter that intermittently emits light; a light receiver that receives reflected light of the light emitted from the light emitter
Implementation Method 3
a distance calculator that calculates, in the first mode, a distance from a target object based on a difference between a time when the light emitter emits the light and a time when the light receiver receives the reflected light
Data Source
AI summary
A distance measuring device includes a light emitter; a light receiver; a protection cover that is located on an optical path between the light emitter and the light receiver; a mode switch that switches between a first mode and a second mode; a distance calculator that calculates a distance from a target object based on a difference between a time when light is emitted from the light emitter and a time when reflected light is received by the light receiver in the first mode; and an LD light emission intensity adjuster that adjusts a light emission intensity of the light emitter. The adjustment is performed such that a light emission intensity of the light emitter in the second mode is lower than a light emission intensity of the light emitter in the first mode.