Band-pass filter for light receiving element minimizing sunlight interference
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Solution Overview
Problem
Conventional methods fail to adequately remove ambient sunlight interference in outdoor environments, affecting the accuracy of image pick-up devices and distance measuring devices.
Innovation Solution
A band-pass filter for light receiving elements is designed to minimize the energy density ratio of ambient light to signal light, maximizing the signal-to-noise ratio by optimizing the transmittance characteristics of the filter, particularly using infrared signal light and known spectral distributions of sunlight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a conventional band-pass filter is used to reduce ambient light influence, then some ambient light can be removed, but the filter cannot sufficiently remove strong sunlight interference outdoors
Solution Approach 1:
The patent changes the key parameter of the band-pass filter from conventional visible light range to infrared wavelength range (780nm-1mm). This parameter change exploits the fact that infrared signal light is imperceptible to human eye and experiences less sunlight interference, thereby sufficiently removing strong ambient light interference while maintaining reliable distance measurement and object detection accuracy outdoors
Solution Approach 2:
The patent transitions from the visible light dimension to the infrared dimension for signal transmission. By operating in the infrared wavelength range instead of visible light, the system accesses a different spectral dimension where sunlight radiation illuminance is lower, enabling effective outdoor operation with sufficient ambient light rejection
2Illumination intensity
If visible light is used for signal transmission, then the signal can be perceived by human eye, but sunlight interference is significantly stronger
Solution Approach 1:
The patent changes the wavelength parameter of signal light from visible light range to infrared range (780nm-1mm). This parameter change makes the signal imperceptible to human eye but simultaneously reduces sunlight interference, as infrared radiation from sunlight is significantly weaker than visible light radiation
Solution Approach 2:
The patent converts the potential disadvantage of infrared being imperceptible to human eye into a benefit by operating in a spectral region where environmental interference (sunlight) is reduced. The 'harm' of reduced visibility is transformed into the 'benefit' of reduced ambient light interference
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 significantly enhances the accuracy of signal reception and distance measurement by reducing ambient light interference, thereby improving the signal-to-noise ratio and ensuring high-precision device performance in outdoor conditions.
Implementation Method 1
a band-pass filter which passes through light in a wavelength range of the signal light is used
Implementation Method 2
determining N1 when energy density of ambient light in the light receiving element is represented as N1; determining N2 when energy density of signal light in the light receiving element is represented as N2; obtaining N1/(N2) 2
Data Source
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AI summary
Disclosed is a filter for a light receiving element, which can sufficiently eliminate disturbance due to sunlight and the like out of doors. A filter for a light receiving element according to one embodiment of the present invention is used for a light receiving element which receives signal light having a known spectral distribution. The filter for a light receiving element according to one embodiment of the present invention is configured so that when the energy density of the ambient light in the light receiving element is represented by N1 and the energy density of the signal light in the light receiving element is represented by N2, N1/(N2)2 is minimized under constraints.