Refrigerator RFID Monitoring for Door-State Product Tracking
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Solution Overview
Problem
The existing radio-frequency transmission systems in refrigerators often experience destructive interference and field weakening due to the metal enclosure, leading to reduced detectability of transponders, making it difficult to monitor the presence and movement of products effectively.
Innovation Solution
A method that involves detecting time-based door opening and closing events, using short time intervals to determine transponder presence and absence, and employing RFID technology with internal and external antennas to differentiate between insertion and removal events by assigning reference statuses to transponder identification codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If radio-frequency transmission systems are used to monitor transponders in a refrigerator with metal enclosure, then transponder communication is enabled, but destructive interference and field weakening occur reducing detectability
Solution Approach 1:
The patent employs multiple antennas positioned at different locations within the refrigerator compartment, allowing the system to dynamically select or combine signals from different antennas depending on which provides the strongest or clearest transponder response, thereby overcoming static field weaknesses caused by metal enclosure interference
Solution Approach 2:
The patent introduces a door state detection mechanism that acts as an intermediary to identify when door opening/closing causes field disturbances, allowing the system to adjust its monitoring strategy or alert the user about potential detection failures caused by the metal enclosure's interference
2Ease of operation
If the refrigerator door is opened to allow product insertion/removal, then user access is enabled, but transponder detectability becomes unreliable due to changing field distribution
Solution Approach 1:
The patent performs transponder detection at multiple periodic intervals - both when the door is closed and during the door opening/closing process - allowing the system to capture transponder presence information at different moments and reconcile any discrepancies that arise due to field changes during door movement
3Area of stationary object
If multiple reflections occur due to high reflectivity of refrigerator walls, then signal coverage is extended, but mutual cancellation and field-weakening interference patterns occur
Solution Approach 1:
The patent divides the single transponder detection task into multiple parallel detection channels, each using a different antenna with distinct spatial characteristics. This segmentation allows the system to process signals from multiple paths simultaneously and identify the most reliable detection result, overcoming the reliability issues caused by reflective interference patterns
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
This method ensures maximum reliability and safety in monitoring transponders, allowing for accurate tracking of product presence and movement within the refrigerator, even in areas with potential zero-field zones and interference patterns.
Implementation Method 1
radio frequency transmission systems designed to communicate with transponders that are placed on the food products stored in the refrigerator
Implementation Method 2
The fields generated by the transmission system and the transponders in the refrigerator can superimpose themselves on one another, creating destructive interference patterns
Implementation Method 3
the high reflectivity of the refrigerator walls can cause a given signal to travel to a certain point inside the refrigerator through a multitude of different reflections
Data Source
AI summary
Method for monitoring products in a refrigerator, wherein the refrigerator (1) comprises at least a compartment (2) for containing products (3), a door (4) adapted to close said compartment (2) and radio frequency transmission means (5) adapted to communicate with a plurality of transponders (6) associated with said products (3) to detect the presence of said transponders (6) into the compartment (2), each transponder (6) being able to send a specific identification code, the method comprises: detecting said transponders in static condition of closed door (C1), detecting said transponders during a time period (T1) which represents a dynamic phase of door opening (C2), detecting said transponders during a second time period (T2) which represents a dynamic phase of closing door (F2), comparing said transponders (6) detected in static condition (C1) and in dynamic condition (F1, F2), and their time events of detection for determining the transponders introduced and extracted, respectively, from the refrigerator during the condition of open door (C2).