Electrode Approach Sensing Circuit With Compensation Feedback
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Solution Overview
Problem
Existing sensor systems for detecting objects approaching an electrode device are sensitive to disturbing influences and prone to overloading, limiting their sensitivity and dynamic range.
Innovation Solution
A circuit that generates an alternating electric field between a transmitting and receiving electrode, with a compensation method using a microcontroller to adjust the compensation signal, keeping the signal change in the linear range even with high generator voltages, thereby enhancing sensor sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the generator voltage is increased to achieve higher sensor sensitivity, then the sensor sensitivity is improved, but the amplifier stage becomes overloaded and the dynamic range is limited
Solution Approach 1:
The patent applies preliminary anti-action by introducing a compensation signal that anticipates and counteracts the saturation effect before it occurs. The compensation signal is adjusted to compensate for the saturation of the amplifier stage, allowing the generator voltage to be increased beyond the traditional saturation point without losing measurement accuracy. This pre-compensation approach enables higher sensor sensitivity while maintaining amplifier reliability.
2Measurement precision
If the sensor sensitivity is increased to detect smaller changes, then the detection capability is improved, but the circuit becomes prone to overloading and disturbing influences
Solution Approach 1:
The patent converts the harmful saturation effect into a beneficial compensation mechanism. By intentionally allowing the amplifier to operate in its saturation region and then compensating for the known saturation characteristics using the compensation signal, the system transforms what was previously a limiting factor into a tool for enhancing detection capability. This approach allows the circuit to handle higher generator voltages without overloading, thereby improving detection capability while maintaining circuit stability.
3Power
If the generator voltage is set high to maximize signal change, then the signal amplitude is improved, but the amplifier operates in non-linear range
Solution Approach 1:
The patent implements feedback by continuously monitoring the amplifier output and using this information to adjust the compensation signal. The compensation signal is fed back to counteract the non-linear saturation effects, ensuring that the overall system response remains linear even when operating with high generator voltages. This feedback mechanism allows the system to maintain both high signal amplitude and signal linearity simultaneously.
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 increases sensor sensitivity, allowing for longer sensor electrodes and potentially eliminating the need for electrode segmentation, while simplifying and cost-reducing the production process, and providing robustness against environmental influences.
Implementation Method 1
an alternating electric field in the frequency range of preferably 80 to 150 kHz is generated between a transmitting electrode (Tx) and a receiving electrode (Rx). If the conductive object, e.g. a part of the body, enters this field between the electrodes, the field is partially absorbed by this body and the received signal
Data Source
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AI summary
The invention is directed at a method and a circuit for sensing the approach of an object, particularly of a person, to an electrode device on the basis of electrical-field interaction effects. The invention is based on the object of providing solutions which allow an object to approach an electrode device in a manner which is relatively insensitive toward other interfering influences. This object is achieved in line with the first aspect of the present invention by a circuit for generating a signal which is indicative of the approach of an object to an observation area, having a transmission electrode device, a generator circuit for applying an AC voltage to the transmission electrode device; a reception electrode device which extends in or along the observation area, and an output circuit, for generating an output signal correlating to the field applied to the reception electrode device, this circuit being distinguished in that a compensation circuit is provided for the purpose of adding a compensation current i2 to a signal current i1 flowing from the reception electrode device.