Proximity Sensor Phase Switching Parasitic Reflections
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Solution Overview
Problem
Existing proximity sensors face challenges in accurately measuring distance due to interference from parasitic reflections and limited range, which affects measuring accuracy and introduces ambiguity in phase angle determination, especially at greater distances.
Innovation Solution
A proximity sensor that emits a transmission signal with switched phasing, allowing separation of free-field reflections from parasitic reflections, and uses a waveguide with a TE11 mode to achieve high linearity and independence from target permeability, along with a mixer to generate a mixing signal for distance determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If phase angle determination is used for distance measurement, then measuring range can be extended, but ambiguity in phase angle determination increases at greater distances
Solution Approach 1:
The patent applies periodic phase switching of the transmission signal to resolve phase angle ambiguity. By periodically switching the phase of the transmitted signal and measuring the corresponding changes in the reflected signal, the system can determine distance unambiguously even at greater distances where conventional phase angle determination fails. This periodic modulation allows the system to distinguish between multiple possible phase angles that would otherwise be indistinguishable.
2Measurement precision
If conventional reflection measurement is used, then distance can be determined from reflection factor, but parasitic reflections from surrounding conditions and installation situations affect measuring accuracy
Solution Approach 1:
The patent converts the harmful effect of parasitic reflections into a useful measurement signal. By periodically switching the phase of the transmission signal and measuring the corresponding phase changes in the reflected signal, the system can distinguish between the desired reflection from the target and parasitic reflections from surrounding structures. The periodic modulation allows the system to identify and eliminate parasitic components that do not exhibit the expected phase relationship.
Solution Approach 2:
The patent introduces dynamic phase switching to the otherwise static reflection measurement process. By continuously varying the phase of the transmitted signal in a controlled periodic manner and measuring the dynamic response of the reflected signal, the system can separate the target reflection from static parasitic reflections. This dynamic approach transforms a static measurement problem into a dynamic one that can be solved through time-varying signal analysis.
3Measurement precision
If waveguide with TE11 mode is used, then linearity of distance determination is improved and independence from target permeability is achieved, but device complexity increases
Solution Approach 1:
The patent uses a waveguide with TE11 mode as an intermediary structure to achieve linear distance determination that is independent of target permeability. The waveguide structure with its specific TE11 mode characteristics acts as a mediator between the transmission signal and the target, providing a measurement mechanism that is insensitive to variations in target material properties. This intermediary structure transforms the measurement problem into one that is governed by the waveguide's known modal characteristics rather than the unknown target properties.
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 measuring accuracy by minimizing the influence of surrounding conditions and installation situations, providing a clear and unambiguous distance measurement independent of target properties and reducing errors caused by parasitic reflections.
Implementation Method 1
emits a transmission signal as a free-field transmission wave that is reflected on the target and, as a free-field reflection wave, is received by the proximity sensor as a reflection signal
Implementation Method 2
a waveguide is provided for emitting the free-field transmission wave. The coupling-in of the transmission signal as the waveguide transmission signal into the waveguide is provided by a wave mode that leads to detaching the waveguide transmission wave at the aperture on the front end of the waveguide into the free-space transmission wave
Data Source
AI summary
A proximity sensor measures the distance of a target and a method operates the proximity sensor. The proximity sensor emits a transmission signal as a free-field transmission wave, which is reflected at the target and as a free-field reflection signal is received by the proximity sensor as a reflection signal, wherein the determining of the distance is provided from the phasing of the reflection signal in relation to the phasing of the transmission signal. The proximity sensor shifts the phasing of the transmission signal chronologically.