RFID Coil Antenna Structure for Tire-Embedded Communication
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Solution Overview
Problem
RFID tags embedded in tires with carbon black experience impaired communication due to the material's high impedance and relative permittivity, leading to reduced communicable distances and durability issues caused by tire expansion and contraction.
Innovation Solution
A coil-based RFID tag design featuring a pattern coil and a substrate with a coupling transformer, where the coil is wound around the substrate, with one end extending as a first element and the other as a second element, both parallel and of different lengths, to set a low input impedance and maintain communication sensitivity, even when embedded in tires with carbon black.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an RFID tag using a dipole antenna system is embedded in rubber product containing carbon black, then the RFID tag can be attached to tire for management purposes, but a resistor having high resistance (several ten kilo-ohms to several 100 kilo-ohms) is connected between two power feeding points, greatly affecting impedance and effective electrical length of antenna, thereby impairing communication performance
Solution Approach 1:
The patent extracts the antenna system from the conventional dipole configuration and implements a coil-based antenna design that operates independently of the carbon black-containing rubber medium. By using a coil structure with controlled windings and dimensions, the antenna achieves reliable communication without being adversely affected by the high resistance introduced by carbon black particles between power feeding points.
Solution Approach 2:
The patent changes the fundamental parameters of the antenna system by transitioning from a dipole antenna with fixed power feeding points to a coil-based antenna with adjustable winding parameters. By controlling the number of windings, coil diameter, and wire thickness, the antenna impedance and electrical characteristics can be optimized to compensate for the effects of carbon black, thereby maintaining communication performance.
2Duration of action of stationary object
If coating rubber for coating electronic component is blended with large amount of carbon black from viewpoint of improvement in durability, then durability is improved, but influence occurs in communication performance of RFID tag so that satisfactory communication may be impossible
Solution Approach 1:
The patent introduces a coil-based antenna structure as an intermediary element that mediates between the carbon black-containing rubber medium and the RFID communication function. The coil structure, with its specific geometric parameters, acts as a buffer that isolates the communication system from the adverse electrical effects of carbon black, allowing both high carbon black content for durability and reliable communication to coexist.
3Adaptability or versatility
If RFID tag is embedded in tire, then tire management information can be stored and read, but distortion in tire during vehicle traveling concentrates on boundary surface between coating rubber and adjacent member, causing crack to occur between electronic component and adjacent member
Solution Approach 1:
The patent employs a flexible substrate to mount the coil-based antenna and RF chip. This flexible substrate can accommodate the distortion and deformation that occurs in the tire during vehicle traveling, preventing cracks from developing at the boundary surfaces between the electronic component and adjacent tire members. The flexibility allows the embedded RFID tag to maintain structural integrity under dynamic loading conditions.
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 coil design enhances communication characteristics and durability by stabilizing the RFID tag's position and maintaining connectivity during tire deformation, ensuring effective data transmission and management of tire information.
Implementation Method 1
the coil and the pattern coil constitute a coupling transformer
Implementation Method 2
a resonance circuit having a predetermined resonance frequency, and a radiation plate to which the power feeding circuit board is affixed or in proximity of which the power feeding circuit board is arranged and that radiates a transmission signal fed from the power feeding circuit
Data Source
AI summary
To provide a coil that has satisfactory characteristics even when the coil is used by being attached to or embedded in a tire, the coil forming an RFID tag in combination with a substrate on which an RF chip and a pattern coil connected to the RF chip are mounted. A coil 30 is held in a housing 75 accommodating a substrate 90 and is wound around the substrate 90. A first end of the coil 30 extends from the substrate 90 and forms a first element 50 of an antenna. A second end of the coil 30 extends from the substrate 90 and forms a second element 60 of the antenna. The first element 50 and the second element 60 are arranged in parallel to each other, and the first element 50 has a longer extension length than the second element 60. The coil 30 and a pattern coil 40 form a coupling transformer 20. The number of windings in the coil 30 is smaller than the number of windings in the pattern coil 40.