Non-contact Antenna Resonant Frequency Control via Variable Capacitance
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Solution Overview
Problem
The resonant frequency of antennas in non-contact communication systems fluctuates due to manufacturing variations, usage environments, and aging, making it challenging to maintain stable communication characteristics.
Innovation Solution
A non-contact communication apparatus comprising an antenna resonant unit with a variable-capacitance capacitor, an oscillation unit, a measurement unit, and a control unit that detects and controls the resonant frequency by adjusting the capacitance to maintain optimal communication characteristics, even in the presence of fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the resonant frequency is fixed during manufacturing, then the initial communication characteristics are satisfactory, but the resonant frequency fluctuates due to manufacturing variations, usage environments, and aging
Solution Approach 1:
The patent applies dynamics by making the resonant frequency adjustable through a variable capacitor controlled by a control unit. The system dynamically adapts the resonant frequency during operation to compensate for fluctuations caused by manufacturing variations, environmental factors, and aging, thereby maintaining reliable communication characteristics throughout the device lifecycle.
Solution Approach 2:
The patent changes the electrical parameter (capacitance) of the resonant circuit by using a variable capacitor. The control unit adjusts the capacitance value to shift the resonant frequency, enabling the system to compensate for frequency drift and maintain optimal communication performance under varying conditions.
2Reliability
If the resonant frequency is adjusted to compensate for fluctuations, then communication characteristics are maintained, but the device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent implements feedback by having the control unit monitor communication state information and automatically adjust the resonant frequency accordingly. The system receives feedback about communication quality and dynamically modifies the capacitance to maintain optimal resonance, enabling autonomous compensation without complex external intervention mechanisms.
Solution Approach 2:
The system performs self-service by automatically detecting communication state changes and adjusting its own resonant frequency without external assistance. The control unit autonomously manages the frequency compensation process, reducing the need for manual calibration and simplifying the overall system architecture.
3Stability of the object's composition
If a variable capacitor is added to adjust resonant frequency, then frequency stability is improved, but the manufacturing cost and device complexity increase
Solution Approach 1:
The variable capacitor unit serves multiple functions: it adjusts the resonant frequency, compensates for manufacturing variations, counteracts environmental effects, and maintains communication performance throughout the device lifecycle. This multi-functionality justifies the added component by consolidating multiple compensation needs into a single adjustable element.
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 solution enables the apparatus to maintain satisfactory communication characteristics by automatically adjusting the resonant frequency, reducing noise and improving signal quality, and can be applied to both communication and feeding systems.
Implementation Method 1
a transmission signal output from a transmission antenna (resonant circuit) of a reader/writer (hereinafter, referred to as R/W) apparatus dedicated to the system is received by a reception antenna, which provided in a non-contact IC (Integrated circuit) card, using an electromagnetic induction action
Implementation Method 2
The antenna resonant unit includes an antenna coil L3, and a capacitor unit including a variable-capacitance capacitor VC1... controls a resonant frequency of the antenna resonant unit 110 by the use of a control value of a control signal for controlling a capacitance of the variable-capacitance capacitor VC1
Data Source
AI summary
A non-contact communication apparatus 100 includes an antenna resonant unit 110 and an antenna drive unit 130. In the antenna drive unit 130, for example, a measurement unit consisting of an differential amplifier A3 measures an output current from an oscillation unit 131. A control unit 140 detects a minimum value or maximum value of the output current. The resonant frequency is controlled by the use of an optimal control value corresponding to the minimum value or maximum value. Therefore, even if the resonant frequency fluctuates due to variations in antenna characteristics in manufacture or a usage environment or aging, satisfactory communication characteristics at a set resonant frequency can be obtained.