RFID Presence Detection Device Using Electromagnetic Shielding
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Solution Overview
Problem
Existing presence detection systems, such as infrared and microwave-based systems, consume high power and require frequent battery replacement or dedicated power sources, making them inefficient for continuous operation in detection applications like forklift passage in docking zones.
Innovation Solution
A presence detection device utilizing passive or active RFID tags that emit identification signals at specific frequencies, with an RFID interrogator and directional or omnidirectional antennas, where the presence of an object is detected by reflected signals, reducing power consumption to approximately 10 mA at 12V by leveraging electromagnetic shielding and calibrated transmission power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared or microwave detection techniques are used to detect object presence, then detection capability is achieved, but power consumption increases to 60 mA at 12V
Solution Approach 1:
The patent replaces active infrared or microwave detection systems with a passive RFID-based detection system. Instead of using high-power electromagnetic sources to detect objects, the system uses RFID tags that are energized by the interrogator's electromagnetic field, allowing detection with much lower power consumption (10 mA at 12V versus 60 mA at 12V).
Solution Approach 2:
The RFID interrogator emits electromagnetic waves periodically to energize passive RFID tags, rather than maintaining continuous high-power emission. This periodic activation allows the system to achieve detection capability while significantly reducing average power consumption compared to continuous infrared or microwave emission.
2Reliability
If high power is used in presence detection systems, then detection range and reliability are improved, but battery life decreases and dedicated power sources are required
Solution Approach 1:
The system replaces high-power continuous emission systems with low-power periodic RFID interrogation. The electromagnetic shielding ensures that power is only transferred to tags within the detection zone, and the periodic nature of RFID communication extends battery life while maintaining reliable detection through the insulating plate's directional control.
3Use of energy by moving object
If electromagnetic shielding is used to reduce power consumption, then power efficiency improves, but detection area coverage may be reduced
Solution Approach 1:
The insulating plate creates localized electromagnetic shielding that confines energy transfer to specific detection zones rather than blocking all electromagnetic fields. Each RFID tag's detection area is locally optimized with shielding that prevents energy waste in areas where tags are not present, maintaining power efficiency while preserving coverage where needed.
Solution Approach 2:
The insulating plate acts as an intermediary that selectively controls electromagnetic field distribution. It shields areas where RFID tags are not present from receiving energy, thereby reducing overall power consumption, while allowing field penetration in detection zones where tags may be located, maintaining effective coverage.
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 solution enables low-energy presence detection with improved directionality and reduced overlap between detection areas, allowing for efficient detection of objects within defined zones while extending battery life and eliminating the need for dedicated power sources.
Implementation Method 1
the presence of the object in a determined detection area results from the reception by the RFID interrogator after being reflected by the object of the identification signal emitted by the corresponding RFID tag
Implementation Method 2
an insulating plate electromagnetically shielding the antenna from a direct emission of the identification signal
Implementation Method 3
the identification signal is emitted in response to an electromagnetic wave received from the RFID interrogator via the at least one antenna and used for energized said passive RFID tag with the determined RFID frequency
Data Source
AI summary
A presence detection device (10) for detecting the presence of an object (24) in a determined detection area, comprising at least one RFID tag (12A, 12B) that emits an identification signal at a determined RFID frequency; an RFID interrogator (16) receptive of the identification signal via at least one antenna (18); and an insulating plate (20) electromagnetically shielding the antenna from a direct emission of the identification signal,wherein the presence of the object in a determined detection area results from the reception by the RFID interrogator after being reflected by the object of the identification signal emitted by the corresponding RFID tag.