Mechanical Key RFID Films for Eddy-Current-Free Dual-Side Reading
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Solution Overview
Problem
Existing radio-based access control systems face challenges in retrofitting existing mechanical key systems with radio transmission devices due to economic constraints and manufacturer specifications, particularly when the devices need to function on both sides of electrically conductive surfaces, where eddy currents and interference hinder effective communication.
Innovation Solution
A passive radio transmission device is arranged on both sides of an electrically conductive carrier plate, featuring a first film with a microchip and antenna on one side and a second film with an antenna on the other, connected via a flexible web, along with a ferrite film to direct magnetic flux and prevent eddy currents, allowing reliable communication regardless of orientation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a passive radio transmission device is arranged on an electrically conductive carrier plate, then radio communication is enabled, but eddy currents and interference hinder effective communication
Solution Approach 1:
A ferrite layer is introduced as an intermediary between the electrically conductive carrier plate and the passive radio transmission device. This ferrite layer acts as a magnetic flux guide that directs the magnetic field lines through itself rather than allowing them to induce eddy currents in the conductive plate, thereby eliminating interference while maintaining radio communication functionality
Solution Approach 2:
The patent changes the magnetic properties of the system by introducing ferrite material with specific magnetic permeability characteristics. This parameter change allows the magnetic flux to be concentrated and directed through the ferrite layer, preventing it from interacting with the electrically conductive carrier plate and thus eliminating eddy current effects
2Adaptability or versatility
If the radio transmission device needs to function on both sides of the carrier plate, then communication independence from orientation is improved, but device complexity increases
Solution Approach 1:
The radio transmission device is segmented into two separate functional layers: a first film with a first antenna and microchip, and a second film with a second antenna. These segments are connected via a flexible web, allowing each film to be positioned on opposite sides of the carrier plate while maintaining electrical connectivity through the flexible connection
Solution Approach 2:
The patent transitions from a single-plane antenna arrangement to a three-dimensional configuration where antennas are distributed on both sides of the carrier plate. This spatial dimensionality change ensures that at least one antenna remains accessible for communication regardless of the carrier plate's orientation in space
3Adaptability or versatility
If existing mechanical key systems are retrofitted with radio transmission devices, then access control functionality is extended, but manufacturer specifications and economic constraints prevent modification
Solution Approach 1:
The radio transmission device is designed as a complete, pre-assembled unit comprising first and second films with antennas, a flexible web connection, and a ferrite layer. This preliminary preparation of the radio transmission component allows for simple attachment to existing mechanical keys without requiring modification of the key itself, thereby enabling retrofitting while respecting manufacturer specifications
Solution Approach 2:
The radio transmission device structure allows the second film to be positioned behind the first film, with the ferrite layer situated between the carrier plate and the radio transmission device. This nested arrangement enables the entire radio transmission assembly to be attached to the surface of an existing mechanical key without interfering with the key's mechanical functionality or requiring key modification
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 radio communication on both sides of the carrier plate without mechanical reworking, improving the reliability and independence from spatial orientation, thus facilitating the conversion of mechanical keys into transponders without altering the key's structure.
Implementation Method 1
a layer for conducting the magnetic flux, which is designed as a ferrite foil, is arranged between the carrier plate and the radio transmission device
Implementation Method 2
the RFID antennas pick up electromagnetic waves from the receiver, which induces an induced current in their coils, allowing a signal from the transmitter—often referred to as a radio tag—to be transmitted to the receiver
Data Source
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AI summary
A passive radio transmission device is specified that is arranged on a front and a back of an electrically conductive carrier plate, wherein the radio transmission device comprises, on the front of the carrier plate, a first film having a first antenna and having a microchip coupled to the first antenna and, on the back, a second film having a second antenna, wherein the first film is coupled to the second film via a flexible web, routed around an end face of the carrier plate, that connects the front to the back, so that the second antenna is connected to the first film via at least one connecting line running along the web in order to transmit information from the microchip using both the first antenna and the second antenna, wherein the first film, the second film and the web are combined as one component.