Rain Detection Camera Monochromatic Illumination Background Noise
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing rain detection systems for vehicle windshields face challenges in accurately distinguishing raindrops from background changes, leading to incorrect evaluations and insensitive wiper activation due to insufficient compensation of background influences.
Innovation Solution
A device and method using a camera with color filters and a monochromatic illumination source, where the camera captures and separates signals from monochromatic light reflected from the windshield, allowing for precise background subtraction and improved spatial resolution of wetting signals by utilizing specific color patterns and normalization techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If temporal modulation of illumination is used to reduce background influences, then signal-to-noise ratio is improved, but background changes during driving (especially when cornering) are insufficiently compensated leading to incorrect evaluation
Solution Approach 1:
The patent segments the detection process by spatially separating the measurement beam path from the reference beam path. The measurement beam passes through the windshield to detect raindrops on the outer surface, while the reference beam reflects off the inner surface. This spatial segmentation allows independent evaluation of each beam's light quantity, enabling accurate rain detection even when background scenery changes during cornering, as the reference beam provides a stable baseline unaffected by external conditions.
2Reliability
If threshold for detecting wet windshield is provided with sufficient tolerance to avoid erroneous triggering, then false positives are reduced, but sensitivity of wiper activation becomes correspondingly less
Solution Approach 1:
The patent implements a feedback mechanism by continuously monitoring the light quantity of both the measurement beam and reference beam, calculating their ratio, and using this ratio to control the wiper activation. The evaluation unit compares the calculated ratio against a reference ratio with hysteresis bands (upper and lower thresholds), creating a feedback-controlled system that adjusts wiper activation based on the detected rain condition while avoiding erroneous triggering through the hysteresis effect.
3Adaptability or versatility
If conventional driver assistance cameras with color resolution are used, then visible wavelength range is fully captured, but infrared light is blocked by infrared blocking filters and cannot be detected
Solution Approach 1:
The patent applies local quality by using a Bayer filter pattern on the image sensor, where different pixels have different color filtering properties (red, green, blue). The evaluation unit specifically utilizes the blue channel pixels for rain detection, as blue light has optimal scattering characteristics for detecting raindrops on the windshield. This localized use of specific color channel properties enables effective rain detection while maintaining the camera's full color capture capability.
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 enables accurate detection of raindrops with enhanced sensitivity and reduced false triggers by effectively isolating the rain signal from background influences, allowing for reliable windshield wiper control.
Implementation Method 1
the camera can capture a signal from the monochromatic light with which the illumination source illuminates a pane. In particular, the signal detected by the camera correlates with monochromatic light from the illumination source reflected and/or scattered on the inside or outside of the pane and/or on the raindrop.
Implementation Method 2
a camera with an image sensor and color filters for pixels of the image sensor in a plurality of filter primary colors. The monochromatic light is in a visible wavelength range, which is transmitted by the first filter primary color and is blocked by the other filter primary colors.
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The invention relates to a device and method for detecting rain (4). The device for detecting rain comprises a camera with an image sensor (5) and colour filters for pixels of the image sensor in a number of primary filter colours (R; G; B) and an illumination source (3) for producing monochrome light (h) of a first primary filter colour. The monochrome light is located in a visible wavelength range which is transmitted by the first primary filter colour and blocked by the other primary filter colours. The camera and the illumination source (3) are designed and arranged in such a manner that the camera can detect a signal from the monochrome light (r1, r2') with which the illumination source illuminates a plate (2).