Planar Capacitance Detection Device for Compact Image Reading
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Solution Overview
Problem
Existing capacitance detection devices for sheet-like targets, such as banknotes or securities, face challenges in size reduction and complexity due to their three-dimensional electrode structures, which hinder compatibility with other detection methods like image or ultrasonic sensors.
Innovation Solution
A capacitance detection device with a simplified structure featuring first and second electrodes, an oscillator circuit, and a detection circuit, where at least one of these components is formed on thin, flat boards, allowing for a reduced size and improved compatibility with other sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a three-dimensional electrode structure is used for capacitance detection, then detection precision is improved, but device size increases and structure becomes complex
Solution Approach 1:
The patent transitions from a conventional three-dimensional electrode structure to a two-dimensional planar electrode structure. The first and second electrodes are arranged in parallel planes separated by a dielectric member, with the first electrode on one side of the transfer path and the second electrode on the other side. This dimensional simplification reduces structural complexity and device size while maintaining capacitance detection capability through the planar configuration.
2Measurement precision
If a three-dimensional electrode structure with chamfered corners is used, then capacitance detection is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent eliminates the need for chamfered corners by adopting a planar electrode structure. The first and second electrodes are formed as flat, two-dimensional structures on opposite sides of the dielectric member, removing the complex three-dimensional corner chamfering requirements while maintaining effective capacitance detection between the parallel electrodes.
3Measurement precision
If a complex capacitance detection device is used, then detection accuracy is improved, but compatibility with other sensors (image, ultrasonic) is reduced
Solution Approach 1:
The planar, two-dimensional electrode structure creates a flatter, more compact device profile that facilitates integration with other sensor types such as image sensors and ultrasonic sensors. The simplified geometry allows for better spatial arrangement and compatibility in multi-sensor systems compared to complex three-dimensional electrode structures.
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
The solution enables precise capacitance detection with a compact design, enhancing compatibility with other detection methods and reducing the overall size of the device, thus addressing the limitations of previous complex structures.
Implementation Method 1
An oscillator circuit forms an electric field between a first electrode and a second electrode
Implementation Method 2
A detection circuit detects a change in capacitance between the first electrode and the second electrode
Data Source
AI summary
A capacitance detection device includes a first electrode and a second electrode that at least partially face each other on opposite sides of a transfer path. An oscillator circuit forms an electric field between the first electrode and the second electrode. A detection circuit detects a change in capacitance between the first electrode and the second electrode. At least one of the oscillator circuit and the detection circuit is included in each of a first board and a second board. The first board is disposed such that a side surface of the first board faces the first electrode in an electric field direction, and the second board is disposed such that a side surface of the second board faces the second electrode in the electric field direction.