Read State Retention Circuit for RFID Tags
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Solution Overview
Problem
In RFID systems, the inability to maintain the 'read state' of RFID tags leads to inefficient search processes due to repeated readings of tags that have already been identified, causing prolonged search times and failure to retrieve required identification data.
Innovation Solution
A read state retention circuit comprising a charge storage unit, a charging circuit, a sensing circuit, and a state indicator, utilizing an NMOS transistor and voltage doubler to maintain the 'read state' by charging a capacitor and sensing voltage levels, ensuring the state is retained even when RF energy is not present.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the reader continues reading RFID tags without maintaining read state, then the reader can process more tags, but the search efficiency decreases due to repeated readings of already-read tags
Solution Approach 1:
The patent applies preliminary action by setting the read state bit to 1 before the actual reading process completes. This preliminary marking allows the system to quickly identify and skip already-read tags in subsequent operations, preventing repeated readings and improving search efficiency without extending search time
Solution Approach 2:
The patent implements feedback through the read state bit that provides information about the reading status of each tag. This feedback mechanism allows the reader to adjust its reading strategy by checking the read state bit before processing, thereby avoiding redundant operations and optimizing the search process
2Reliability
If the read state is not maintained during search time, then the circuit operates simpler, but RFID tags are read repeatedly causing data retrieval failure
Solution Approach 1:
The patent extracts the read state maintenance function into a separate, dedicated bit within the memory structure. This extracted read state bit can be independently managed and maintained without complicating the overall memory circuit design, ensuring reliable state retention while keeping the circuit relatively simple
Solution Approach 2:
The patent uses the read state bit as an intermediary element that mediates between the reading operation and the memory data. This intermediary bit carries the state information without requiring complex circuitry, as it can be set and cleared through simple control signals during normal read operations
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 effectively maintains the 'read state' of RFID tags, reducing repeated readings and enhancing search efficiency by ensuring the 'read state' is correctly maintained for an extended period without electric leakage, thus improving data retrieval speed and accuracy.
Implementation Method 1
charging a capacitor by an NMOS transistor in response to the raised voltage level of the read signal
Implementation Method 2
charging a capacitor by an NMOS transistor
Data Source
AI summary
A read state retention circuit and method are disclosed. The read state retention circuit comprises a charge storage unit, charging unit, sensing circuit and state indicator. The charging circuit is coupled to the charge storage unit for charging the charge storage unit. The sensing circuit is coupled to the charge storage unit for sensing a voltage level of the charge storage unit. The state indicator is coupled to the sensing circuit for outputting an indication signal in response to the voltage level.