Offset Antenna Coil for RFID Battery Pack
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Solution Overview
Problem
In communication terminal devices like mobile phones, conductive bodies interfere with the induction magnetic field, limiting the communication distance in HF band RFID systems, and existing solutions that minimize this interference often result in larger antenna coil and magnetic material core sizes.
Innovation Solution
The antenna device features a conductive body with a coil aperture portion and a magnetic material core that is offset, allowing the magnetic material core to pass through the aperture, with the center of the coil aperture positioned off-center and the magnetic core ends located along the side or opposite surface, enabling a smaller form factor while maintaining a sufficient communication distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the antenna coil and magnetic material core are configured to minimize the influence of conductive bodies, then the communication distance is improved, but the size of the antenna coil and magnetic material core increases
Solution Approach 1:
The patent applies asymmetry by positioning the magnetic material core off-center relative to the antenna coil. Specifically, the center of the magnetic material core is positioned at a position offset from the center of the antenna coil in the width direction, allowing the core to extend closer to one side surface of the circuit substrate. This asymmetric configuration enables the magnetic field to be concentrated in a specific direction away from the conductive body, improving communication distance while reducing the overall size of the antenna assembly.
Solution Approach 2:
The patent utilizes the width direction dimension of the circuit substrate to optimize the antenna configuration. By positioning the magnetic material core offset in the width direction and allowing it to extend toward the side surface, the design effectively uses the available spatial dimension to create an optimized magnetic field distribution pattern that reduces size requirements while maintaining communication performance.
2Reliability
If the whole width direction of the circuit substrate is used to avoid conductive body influence, then the communication performance is improved, but the antenna device size increases
Solution Approach 1:
The patent applies local quality by concentrating the magnetic material core in a specific offset position rather than distributing it uniformly across the width direction. The core is positioned to extend toward one side surface of the circuit substrate, creating a localized region of enhanced magnetic field strength in the direction away from the conductive body. This localized concentration of magnetic material achieves good communication performance without requiring the antenna device to occupy the entire width of the circuit substrate, thereby reducing overall device volume.
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 allows for a reduced size of the antenna coil and magnetic material core while utilizing the conductive body as a magnetic focusing element, securing a sufficient communication distance and effectively forming a large magnetic field loop.
Implementation Method 1
utilizing the conductive body as a magnetic focusing element, securing a sufficient communication distance and effectively forming a large magnetic field loop
Implementation Method 2
an antenna coil on an RFID tag side and an antenna coil on a reader/writer side are coupled with each other mainly through an induction magnetic field
Data Source
AI summary
A battery pack having a main surface and a side surface, and the external appearance thereof is an approximately rectangular parallelepiped shape. An antenna coil is provided on the main surface. The antenna coil is obtained by forming a coil conductor pattern on a flexible substrate. A substantially slit-shaped aperture is formed on the flexible substrate, and a magnetic material core is inserted into the aperture. In the antenna coil, the center of the coil aperture portion is offset from the center of the main surface of the battery pack in the outside edge portion direction of the main surface. A first end in the magnetic path direction of the magnetic material core is stretched along the side surface of the battery pack, and the second end of the magnetic material core is opened toward the center of the main surface of the battery pack.