Water Content Sensor Using Dual-Wavelength Signal Ratio
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Solution Overview
Problem
Conventional water content sensors for detecting road surface conditions face accuracy issues due to interference from moving objects, such as vehicles, which block infrared rays used for measurement.
Innovation Solution
A water content sensor that emits light with specific wavelength bands, including detection light with high water absorption and reference light with low absorption, and uses a computation processor to determine water amount based on the signal ratio between reflected light signals, minimizing the impact of moving objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If infrared light is used for water content detection, then water absorption is enhanced, but detection accuracy deteriorates due to blocking by mobile bodies
Solution Approach 1:
The patent segments the infrared spectrum into multiple wavelength bands (first wavelength band with high water absorption, second wavelength band with low water absorption). By dividing the detection into multiple spectral components, the system can differentiate between water absorption effects and blocking effects from mobile bodies, thereby resolving the contradiction between enhanced water detection and reduced interference.
2Device complexity
If single wavelength infrared detection is used, then device complexity is reduced, but measurement precision deteriorates due to inability to distinguish water from mobile bodies
Solution Approach 1:
The patent introduces a new dimension for detection by using multiple wavelength bands instead of a single wavelength. This dimensional expansion in the spectral domain allows the system to distinguish between water content and mobile body interference, improving measurement precision while maintaining relatively simple device structure through optical filtering.
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
This approach enhances the accuracy of water content detection on road surfaces by distinguishing between signal changes caused by water and moving objects, leading to more reliable measurements.
Implementation Method 1
a light emitter that emits light toward a road surface, the light including detection light having a first wavelength band in which absorption by water is greater than a predetermined value and reference light having a second wavelength band in which the absorption by water is less than or equal to the predetermined value
Implementation Method 2
a first light receiver that receives the detection light reflected by the road surface and converts the detection light to a first electric signal; a second light receiver that receives the reference light reflected by the road surface and converts the reference light to a second electric signal
Implementation Method 3
detection light having a first wavelength band in which absorption by water is greater than a predetermined value and reference light having a second wavelength band in which the absorption by water is less than or equal to the predetermined value
Implementation Method 4
a first light receiver that receives the detection light reflected by the road surface and converts the detection light to a first electric signal
Data Source
AI summary
A water content sensor includes: a light emitter that emits detection light having a first wavelength band and reference light a second wavelength band toward a road surface; a first light receiver that converts the detection light reflected by the road surface to a first electric signal; a second light receiver that converts the reference light reflected by the road surface to a second electric signal; and a computation processor that detects the amount of water based on a signal ratio between the first electric signal and the second electric signal. The computation processor detects the amount of water based on the signal ratio obtained when the signal intensity of at least one of the first electric signal and the second electric signal is within a predetermined range defined relative to a reference value.