Diffusion Element Light Sheet for Raindrop Detection
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Solution Overview
Problem
Existing camera-based rain detection systems face challenges in sensitivity due to insufficient illumination area and light intensity loss associated with the use of light guides, which affects the reliability and effectiveness of rain detection.
Innovation Solution
A device comprising a camera, a lighting source, and a diffusion element that emits a light sheet, where the diffusion element disperses light from the lighting source, such as LEDs, to create a uniformly illuminated area on the windshield, allowing for improved rain detection by distinguishing between light reflections from the inner and outer windshield surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a light guide is used to illuminate the detection area on the windshield, then the illumination area is increased, but light intensity is lost
Solution Approach 1:
The patent removes the light guide component from the illumination system and replaces it with a diffusion element directly coupled to the LED array. This extraction eliminates the light intensity losses associated with light guide transmission while maintaining the ability to illuminate a sufficient detection area on the windshield through direct LED illumination and diffusion.
Solution Approach 2:
The patent introduces a diffusion element as an intermediary between the LED light source and the windshield. This diffusion element disperses the light from the LEDs to create uniform illumination across the detection area without the light intensity losses inherent in light guide systems. The diffusion element mediates between the point-source LEDs and the extended detection area requirement.
2Area of stationary object
If the aperture angle of illumination is increased to cover a larger detection area, then the detection area is expanded, but the light intensity reaching the camera is reduced
Solution Approach 1:
The patent applies local quality by using multiple discrete LED sources arranged in an array, where each LED illuminates a specific local region of the windshield. The diffusion element then combines these local illuminations to create a uniformly lit detection area. This approach maintains high light intensity in each local region while achieving comprehensive area coverage.
Solution Approach 2:
The patent transitions from a single-point light source to a distributed array of LED sources across multiple dimensions. This dimensional expansion allows the system to illuminate a larger detection area on the windshield while maintaining sufficient light intensity through the combined output of multiple LEDs, with the diffusion element ensuring uniform distribution.
3Area of stationary object
If a diffusion element with higher density is used to increase dispersion, then the detection area is enlarged, but transmission loss increases
Solution Approach 1:
The patent applies partial action by using a diffusion element with moderate density that provides sufficient light dispersion to illuminate the required detection area without excessive transmission losses. The diffusion element is designed to achieve the minimum necessary dispersion to cover the detection area while minimizing energy loss, rather than using maximum density diffusion.
Solution Approach 2:
The patent optimizes the diffusion element's physical parameters (density, material composition, thickness) to achieve the desired balance between dispersion and transmission. By carefully selecting and tuning these parameters, the system achieves adequate light dispersion to cover the detection area while minimizing transmission losses and maintaining sufficient light intensity for rain detection.
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 provides reliable and cost-effective rain detection with improved sensitivity, using inexpensive components and maintaining effective performance across various windshield angles and inclinations, while allowing for integration with other driver assistance functions.
Implementation Method 1
The light emitted by the lighting source emerges as a light sheet from the diffusion element
Implementation Method 2
the camera can detect a signal from the light or an imaging of the light sheet which is emitted by the lighting source, impinges through the diffusion element on the pane and is reflected by the pane
Data Source
AI summary
A device for detecting rain on a pane includes a camera, a lighting source for emitting light and a diffusion element. The light emitted by the lighting source is diffused through and emerges as a light sheet from the diffusion element. The camera, the lighting source and the diffusion element are configured and arranged so that the camera can detect a signal from an image of the light sheet that is emitted by the lighting source, diffused through the diffusion element, impinges on the pane and is reflected or scattered by the pane and/or a raindrop on the pane. The signal detected by the camera is evaluated to detect whether there is rain on the pane.