Capacitive Proximity Sensing with Balanced Paths Against Disturbance
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Solution Overview
Problem
Existing systems for detecting changes in the surroundings of an object are sensitive to disturbances such as extraneous light, air humidity, and earthing, leading to unreliable and unambiguous results, especially in capacitive solutions where charge discharge issues occur.
Innovation Solution
The system balances two measurement paths with a regulating device to ensure consistent amplitude values and couples the sensor-active region with high resistance to the drivers and amplifier, allowing for high amplification of small changes while minimizing phase and amplitude influence, thereby enhancing sensitivity and reducing disturbance sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor uses high amplification to detect small changes, then sensitivity is improved, but disturbance sensitivity increases
Solution Approach 1:
The patent divides the sensor system into two independent measurement paths (first and second measurement paths) with separate drivers and sensor-active regions. Each path processes signals independently and the results are evaluated together, allowing disturbance rejection through comparison while maintaining high amplification for sensitivity.
Solution Approach 2:
The patent implements dynamic regulation of driver power to compensate for environmental changes. The regulating device monitors amplitude values from both measurement paths and adjusts the power supplied to drivers accordingly, maintaining consistent sensitivity while rejecting disturbances caused by humidity, temperature, or earthing variations.
2Power
If the sensor couples measurement surface directly to drivers for strong signal, then signal strength is improved, but measurement precision deteriorates due to loading effects
Solution Approach 1:
The patent introduces a high-input-impedance amplifier circuit as an intermediary between the measurement surface and the evaluation circuitry. This amplifier buffers the measurement surface, allowing strong signal coupling while preventing loading effects that would distort amplitude and phase measurements.
Solution Approach 2:
The patent applies different coupling characteristics to different parts of the signal path. The measurement surface is coupled with high resistance to the amplifier input to minimize loading, while the amplifier provides high gain to restore signal strength. This localized optimization of coupling characteristics resolves the contradiction between signal strength and measurement precision.
3Difficulty of detecting and measuring
If the sensor uses capacitive coupling to detect changes, then detection capability is improved, but reliability deteriorates due to charge discharge issues from earthing and humidity
Solution Approach 1:
The patent implements a regulating device that continuously monitors the amplitude values from both measurement paths and provides feedback to adjust the driver power. This feedback mechanism compensates for charge discharge effects caused by earthing and humidity variations, maintaining reliable measurements despite environmental conditions.
Solution Approach 2:
The patent makes the sensor system dynamic by enabling real-time adjustment of driver power based on environmental conditions. The regulating device dynamically balances the measurement paths by modifying power supply to drivers, allowing the system to adapt to changing humidity and earthing conditions while maintaining detection 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 reliable detection of even the smallest changes in the surroundings, maintaining sensitivity across varying conditions and avoiding interference from environmental factors like air humidity and earthing, allowing for accurate control commands, such as opening doors automatically upon approach.
Implementation Method 1
The arrangement preferably works capacitively
Implementation Method 2
even the smallest changes in the surroundings are noticeable at the measurement surface by an amplitude and/or phase change
Data Source
AI summary
Disclosed is an arrangement for monitoring changes in an object's surrounding field, including a sensor-active region(s), a measurement path(s) with a driver for applying a variable, a receiver(s) detecting a variable, a circuit connected downstream of the receiver for determining changes in a surrounding field and generating a control and/or measurement signal, a further measurement path(s) or reference section(s) with a driver to detect changes in the variable and the measurement path(s), a clock circuit switched on at time intervals of the measurement path and the reference path a regulating device for the variable(s) introduced by the drivers in response to changes in the variable in the field, with the result that at the receiver average the same amplitude of the variable passes from the drivers and the sensor-active region to the receiver from the measurement paths the sensor-active region being coupled with high resistance to the drivers.