Microstrip Spin Resonance Sensor for Fast Banknote Testing
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Solution Overview
Problem
Existing devices for testing data carriers with spin resonance features, such as banknotes, face challenges in achieving a good signal-to-noise ratio, particularly when dealing with fast-moving items and in the presence of external interference signals.
Innovation Solution
A sensor element with a microstrip line resonator is used, which includes a magnetic core, a static magnetic flux generator, and a modulated magnetic field, optimized for CW, pulsed, or rapid-scan methods, featuring a microstrip line resonator with a conducting structure on a printed circuit board, and a shielding element to reduce interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional resonators are used for spin resonance measurement, then the device structure is simple, but the signal-to-noise ratio is poor and external interference signals cannot be effectively reduced
Solution Approach 1:
A shielding element is introduced as an intermediary component between the resonator and the external environment. This shielding element acts as a mediator that blocks external interference signals from reaching the resonator, thereby improving the signal-to-noise ratio without fundamentally changing the resonator's operating principle
Solution Approach 2:
The shielding element is positioned in advance to prevent external interference signals from affecting the resonator before the measurement takes place. By placing the shielding element around the resonator, the system proactively counteracts potential interference rather than attempting to filter it after it has contaminated the signal
2Productivity
If the data carrier moves quickly through the measurement zone, then productivity increases, but the measurement time decreases leading to poor signal-to-noise ratio
Solution Approach 1:
The resonator is designed to continuously generate and maintain the oscillating magnetic field throughout the measurement zone, ensuring that the spin resonance excitation is ongoing without interruption. This continuous action allows for effective measurement even as the data carrier moves through the zone at high speed
Solution Approach 2:
The problem of short measurement time due to fast movement is addressed by extending the interaction in the time dimension through prolonged field exposure. The resonator maintains continuous oscillating field action throughout the data carrier's passage, effectively stretching the measurement interaction time without reducing productivity
3Measurement precision
If a static magnetic field is applied to achieve spin resonance, then the resonance condition is met, but external interference signals affect the measurement accuracy
Solution Approach 1:
The shielding element serves as an intermediary barrier between the static magnetic field system and external interference sources. It allows the static magnetic field to penetrate and establish the resonance condition while blocking external interference signals from corrupting the measurement
Solution Approach 2:
The shielding element, which might seem to obstruct the magnetic field, actually benefits the measurement by selectively blocking harmful external interference signals while allowing the beneficial static magnetic field to pass through and establish the resonance condition
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 provides a high signal-to-noise ratio and efficient testing of spin resonance features even in fast-moving data carriers, with improved measurement accuracy and reduced interference.
Implementation Method 1
a resonator (32) for exciting the spin resonance feature of the data carrier under test
Implementation Method 2
exciting the spin resonance feature of the data carrier under test
Implementation Method 3
an element for generating a static magnetic flux in the air gap
Implementation Method 4
a modulation device for generating a modulated magnetic field parallel to the static magnetic flux in the air gap
Implementation Method 5
a shielding element to reduce interference
Data Source
AI summary
A sensor element for testing a flat data carrier, in particular a banknote, has a spin resonance feature. The sensor element contains a magnetic core having an air gap, into which the flat data carrier can be inserted for testing, an element for generating a static magnetic flux in the air gap, and a resonator for exciting the spin resonance feature of the data carrier to be tested. The resonator is formed by a microstrip line resonator which is arranged in the air gap of the magnetic core and comprises a flat carrier having an upper side and a conducting structure which is arranged on the upper side of the carrier with a characteristic length.