Segmented Mirror for RFID Scanner
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Solution Overview
Problem
Existing optical scanners for identification documents with metal mirrors interfere with radio waves, preventing reliable reading of RFID transponders due to signal attenuation by the metal layer, making it difficult to perform both optical and electrical scanning effectively.
Innovation Solution
A scanner design with a mirror having a metal layer divided into small, separated mirror segments that minimize eddy currents, allowing for reliable radio wave transmission and reception without significant optical information loss, enabling both optical and electrical scanning of documents with integrated transponders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a continuous metal layer mirror is used for optical scanning, then optical reflection quality is improved, but radio wave transmission is attenuated due to eddy currents
Solution Approach 1:
The continuous metal layer mirror is divided into multiple separate mirror segments (e.g., 4 segments) that are electrically isolated from each other. This segmentation prevents the formation of large eddy currents while maintaining optical reflection functionality, as each small segment generates minimal eddy currents that do not significantly attenuate radio waves passing through the mirror structure.
2Device complexity
If the mirror is placed in proximity to the antenna for compact design, then device complexity is reduced, but reading reliability of RFID transponders deteriorates due to signal attenuation
Solution Approach 1:
By segmenting the mirror into electrically isolated sections, the patent enables the mirror to be positioned close to the antenna without significant radio wave attenuation. The segmented structure minimizes eddy current effects, allowing reliable RFID transponder reading even at reduced distances, thus maintaining compact device design while ensuring reading reliability.
3Manufacturing precision
If mirror segments are spaced closely to maintain optical resolution, then manufacturing precision is improved, but eddy current formation increases
Solution Approach 1:
The patent implements a segmented mirror design where multiple small mirror segments are arranged to provide sufficient optical resolution. The segments are electrically isolated and sized such that they maintain the required optical precision while being small enough to minimize eddy current formation. The segmentation itself prevents large-scale eddy currents from forming across the mirror surface.
Solution Approach 2:
Each mirror segment is designed with specific local properties (size, spacing, electrical isolation) that optimize both optical performance and electromagnetic compatibility. The local segmentation creates zones of minimal eddy current generation while maintaining overall optical reflection quality across the mirror surface.
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 scanner effectively scans documents optically and electrically without impairing radio waves, ensuring reliable data extraction from transponders, even at high resolutions, by using mirror segments spaced closely enough to prevent eddy currents, thus combining optical and electrical data for further processing.
Implementation Method 1
an optical scanning device that can scan the document lying on the glass plate by means of a mirror arranged below the glass plate. The mirror typically possesses a reflecting metal layer.
Implementation Method 2
at least one antenna for transmission of electromagnetic signals to the transponder and for reception of electromagnetic signals from the transponder
Implementation Method 3
the transmission power and reception power would be significantly attenuated by the metal layer of the mirror since they form exposures in the metal layer due to the radio waves
Data Source
AI summary
In a scanner for optical and electrical scanning of a document having a transponder associated therewith a glass plate is provided for placement of the document. An optical scanning device scans the document via a mirror. At least one antenna for transmission of electromagnetic signals to the transponder and for reception of electromagnetic signals from the transponder is provided.