RFID Tag Placement on Conductive Edges
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Solution Overview
Problem
RFID tags often fail to function properly when placed on electrically conductive materials, such as foil-lined packaging, due to interference with radio-frequency energy, leading to increased costs for reliable operation and aesthetically unpleasing solutions like thick non-conductive spacers.
Innovation Solution
Securing an RFID tag to the external peripheral edge of an electrically conductive object with a planar substrate, where one portion of the antenna overlies a conductive area and another portion does not, allowing capacitive coupling tuning to enhance power reception and rectification, while maintaining a non-intrusive design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standard passive RFID tag is placed on foil-lined packaging, then the tag cost remains low, but the tag cannot adequately rectify RF energy and fails to function properly
Solution Approach 1:
A non-conductive adhesive layer is introduced between the RFID tag antenna and the conductive foil packaging. This intermediary layer prevents direct contact between the antenna and conductive surface, allowing the tag to adequately rectify RF energy while maintaining cost-effectiveness. The adhesive layer acts as a mediator that resolves the conflict between low cost and reliable functionality.
Solution Approach 2:
The invention changes the electrical parameter of the tag-packaging interface by introducing a non-conductive layer with specific dielectric properties. This parameter change (from direct conductive contact to insulated contact) enables the antenna to function properly by preventing energy loss to the conductive surface, thereby improving tag reliability without increasing cost.
2Reliability
If a thick non-conductive spacer is placed between the container and RFID tag, then the tag can function properly, but the solution is visually noticeable and aesthetically unpleasing
Solution Approach 1:
The invention uses a thin non-conductive adhesive film instead of a thick spacer. This thin film maintains the necessary electrical isolation between the antenna and conductive surface for proper tag functionality, while being visually imperceptible and aesthetically pleasing. The thin film approach eliminates the unsightly appearance of thick spacers.
3Reliability
If a thick non-conductive spacer is used, then RFID tag operation is improved, but the number of containers that can be displayed on a shelf is reduced
Solution Approach 1:
The thin adhesive film maintains proper tag functionality while occupying minimal space. This allows containers to be displayed at normal density on shelves without the space-consuming thick spacers, thereby preserving display capacity while ensuring reliable RFID operation.
4Use of energy by moving object
If the RFID tag antenna completely overlies the conductive surface, then maximum power reception might be achieved, but capacitive coupling interference prevents proper operation
Solution Approach 1:
The non-conductive adhesive layer serves as an intermediary that enables the antenna to be positioned close to the conductive surface for maximum power reception, while simultaneously preventing capacitive coupling interference. This mediator allows both objectives to be achieved: the antenna maintains optimal positioning for energy harvesting without suffering from conductive interference.
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
Enables reliable RFID tag operation near conductive surfaces without visual disturbance or space reduction, using standard, inexpensive tags, and preserving original design aesthetics.
Implementation Method 1
a first portion of the RFID tag's antenna proximally overlies an electrically-conductive portion of the first non-coplanar side of the object while a second portion of the RFID tag's antenna does not proximally overlie any electrically-conductive portion of the object
Data Source
AI summary
An RFID tag is secured to an electrically-conductive object having an external peripheral edge where first and second non-coplanar sides of the object meet one another, wherein at least the first non-coplanar side comprises electrically-conductive material. By one approach the RFID tag is secured to the first non-coplanar side of the object at the external peripheral edge such that a first portion of the RFID tag's antenna proximally overlies an electrically-conductive portion of the first non-coplanar side of the object while a second portion of the RFID tag's antenna does not proximally overlie any electrically-conductive portion of the object. Determining the size of the first portion of the RFID tag's antenna that will overlie the first non-coplanar side of the object comprises tuning the capacitive coupling between the first portion of the RFID tag's antenna and the object to thereby achieve a desired range and/or degree of RFID tag performance.