Capacitance Sensor Electrode Asymmetry for Field Stabilization
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Solution Overview
Problem
Existing electrostatic capacitance detection devices face challenges in stabilizing the electric field between electrodes, particularly when dealing with three-dimensional electrodes, and lack effective methods for processing such electrodes to maintain consistent output.
Innovation Solution
The electrostatic capacitance detection device incorporates first and second electrodes with intersecting shapes and floating electrodes, along with electric field adjusters, to stabilize the electric field and improve output stability, allowing for effective detection of changes in electrostatic capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If three-dimensional electrodes are used in electrostatic capacitance detection devices, then the detection capability is improved, but the electric field between electrodes becomes unstable and output varies
Solution Approach 1:
The patent applies asymmetry by providing guard electrodes with different potentials than the measurement electrodes. Specifically, the guard electrodes are set to potentials different from both the first and second measurement electrodes, creating an asymmetric potential distribution that stabilizes the electric field. This asymmetric configuration prevents edge effects and ensures uniform electric field distribution between the measurement electrodes, thereby improving reliability while maintaining detection capability.
Solution Approach 2:
The guard electrodes serve as intermediaries between the measurement electrodes and the surrounding environment. By introducing these intermediate electrodes with controlled potentials, the patent mediates the electric field distribution, preventing direct interaction between the measurement electrodes and external electrical interference. This intermediary structure stabilizes the electric field and reduces output variation.
2Reliability
If guard electrodes with different potentials are introduced, then electric field stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the guard electrode structure with the existing measurement electrode structure. The guard electrodes are positioned adjacent to the measurement electrodes and share the same physical space, combining multiple functions into a compact configuration. This merging approach stabilizes the electric field without proportionally increasing device complexity, as the guard electrodes utilize the same structural framework.
Solution Approach 2:
The guard electrodes serve multiple functions: they stabilize the electric field, shield against external electrical interference, and define the measurement region. By making these electrodes multi-functional, the patent achieves improved electric field stability without requiring separate components for each function, thereby limiting the increase in device complexity.
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 stabilizes the electric field and reduces variations in electric field strength, enabling reliable detection of changes in electrostatic capacitance and effective identification of detection targets, such as bank notes or securities.
Implementation Method 1
an oscillation circuit causes an electric field to be formed between the first electrode and the second electrode
Implementation Method 2
A detection circuit detects a change in electrostatic capacitance between the first electrode and the second electrode
Data Source
AI summary
An electrostatic capacitance detection device includes a first electrode, and a second electrode at least a part of which is opposed to the first electrode across a transport path extending in a transport direction in which a detection target having a sheet shape is transported. The first electrode and the second electrode extend in a cross direction intersecting the transport direction and have mutually different shapes. Alternatively, the electrostatic capacitance detection device further includes a first floating electrode disposed on the side of the first electrode opposite to the transport path, and a second floating electrode disposed on the side of the second electrode opposite to the transport path. Alternatively, at least one of the first electrode or the second electrode is provided with a first electric field adjuster or a second electric field adjuster.