Automatically displaceable cleaning device
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Solution Overview
Problem
Existing automatically displaceable cleaning devices with optical triangulation systems for distance measurement face issues due to low transmittance of bandpass filters, leading to reduced signal strength and the need for error-prone manual electrical connections between separate circuit boards.
Innovation Solution
The use of a band stop filter with high reflectance (>90%) replaces the bandpass filter, allowing the detector to be situated on the same circuit board as the optical filter, eliminating the need for a second circuit board and improving signal quality, and optionally using a reflector to further enhance light detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a bandpass filter is used to filter scattered light in the optical triangulation system, then ambient light is blocked, but the transmittance is low (at most 90%), reducing signal strength and detection accuracy
Solution Approach 1:
The patent inverts the conventional bandpass filter approach by using a band stop filter (notch filter) that blocks ambient light wavelengths while transmitting the laser wavelength. This inversion of the filtering strategy maintains high signal strength for the measurement light while effectively rejecting ambient light interference, thereby resolving the contradiction between noise rejection and measurement precision.
Solution Approach 2:
The patent changes the spectral parameters of the optical filter from a bandpass configuration (transmitting only a narrow wavelength range) to a band stop configuration (blocking only specific ambient light wavelengths). This parameter change allows the filter to achieve both high ambient light rejection and high transmittance for the measurement signal, eliminating the trade-off between these two requirements.
2Object-affected harmful factors
If a bandpass filter with high selectivity is used, then ambient light is effectively blocked, but the detector must be placed on a separate circuit board perpendicular to the filter, requiring manual soldering and increasing assembly errors
Solution Approach 1:
The patent merges the filter and detector onto a single circuit board by using a band stop filter that allows the measurement light to pass through to the detector on the same board. This eliminates the need for a second perpendicular circuit board and manual soldering of multi-core connections, significantly simplifying manufacturing while maintaining effective ambient light rejection.
3Measurement precision
If a bandpass filter is used in the optical triangulation system, then spectral filtering is achieved, but signal loss occurs due to reflection and absorption, reducing the detected signal strength
Solution Approach 1:
The patent inverts the filtering approach from bandpass to band stop, changing the mechanism from selective transmission to selective reflection/blocking. The band stop filter reflects or absorbs only the ambient light wavelengths while transmitting the measurement laser wavelength with high efficiency, thereby achieving spectral filtering capability with minimal signal loss.
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 configuration enhances signal intensity, reduces assembly errors, and achieves a more compact design by eliminating the need for a second circuit board, while maintaining or improving measurement accuracy for both strong and weakly scattering objects.
Implementation Method 1
the optical filter is a band stop filter with a reflectance of at least 90% in relation to at least one wavelength of the scattered light
Implementation Method 2
light emitted by the light source in the propagation direction is first scattered by the object
Data Source
AI summary
An automatically movable cleaning device, in particular an electric-motor-driven vacuuming and/or wiping robot, comprising a distance-measuring device for measuring the distance of the cleaning device from an object, wherein the distance-measuring device has an optical triangulation system, which has a light source, an optical filter, and a detector, which are arranged in such a way that light in a propagation direction, emitted by the light source, is first scattered by the object, wherein at least a portion of the scattered light is then spectrally filtered by means of the optical filter and wherein the filtered light is finally detected by the detector. For advantageous development, the optical filter according to the invention is a band-stop filter having a reflectivity of at least 90% with respect to at least one wavelength of the scattered light, and/or the optical filter is a band-pass filter, a reflector being arranged after the band-pass filter in the transmission direction, and/or the optical filter is a cut-off filter having a reflectivity of at least 90% with respect to at least one wavelength of the scattered light.