초록 ▼

An article inventory control system for articles, such as books, uses RFID tags attached to each article. Each tag has a unique identification or serial number for identifying the individual article. An inventory database tracks all of the tagged articles and maintains circulation status information

An article inventory control system for articles, such as books, uses RFID tags attached to each article. Each tag has a unique identification or serial number for identifying the individual article. An inventory database tracks all of the tagged articles and maintains circulation status information for each article. Articles are checked out of the library using a patron self-checkout system. Checked out articles are returned to the library via patron self-check in devices. The shelves are periodically scanned with a mobile RFID scanner for updating inventory status.

대표청구항 ▼

An article inventory control system for articles, such as books, uses RFID tags attached to each article. Each tag has a unique identification or serial number for identifying the individual article. An inventory database tracks all of the tagged articles and maintains circulation status information

An article inventory control system for articles, such as books, uses RFID tags attached to each article. Each tag has a unique identification or serial number for identifying the individual article. An inventory database tracks all of the tagged articles and maintains circulation status information for each article. Articles are checked out of the library using a patron self-checkout system. Checked out articles are returned to the library via patron self-check in devices. The shelves are periodically scanned with a mobile RFID scanner for updating inventory status. 3. The proximity detector of claim 2 wherein said threshold signal and said tracking signal are interchanged in response to changes in state of said comparator output signal. 4. The proximity detector of claim 1 wherein said comparator is responsive to said tracking signal and has hysteresis by which said predetermined amount is established. 5. The proximity detector of claim 1 wherein said tracking signal is brought to substantially the same level as said magnetic field signal in response to changes in state of said comparator output signal. 6. The proximity detector of claim 1 wherein said magnetic field signal is brought to substantially the same level as said tracking signal in response to changes in state of said comparator output signal. 7. The proximity detector of claim 1 wherein said tracking signal is brought to a level which is at a fixed offset from said magnetic field signal in response to changes in state of said comparator output signal. 8. The proximity detector of claim 1 wherein said magnetic field signal is brought to a level which is at a fixed offset from said tracking signal in response to changes in state of said comparator output signal. 9. The proximity detector of claim 1 wherein said peak detector comprises: a comparator responsive to said magnetic field signal and to said tracking signal for generating a feedback signal; a counter for providing a count signal in response to said feedback signal; and a DAC coupled to said counter for converting said count signal into an analog signal. 10. The proximity detector of claim 9 wherein said tracking signal is provided by said analog signal. 11. The proximity detector of claim 9 wherein said peak detector further comprises an offset generator for generating said tracking signal at a predetermined offset with respect to said analog signal. 12. The proximity detector of claim 1 wherein said peak detector comprises a capacitor across which said tracking signal is provided. 13. A method for detecting a ferrous article comprising the steps of: generating a magnetic field signal indicative of an ambient magnetic field; generating a tracking signal which substantially follows said magnetic field signal; generating an output signal which changes state when said magnetic field signal varies from said tracking signal by a predetermined amount; and forcing at least one of said magnetic field signal and said tracking signal towards the other one of said magnetic field signal and said tracking signal in response to transitions of said output signal. 14. The method of claim 13 wherein said forcing step comprises bringing said tracking signal to substantially the same level as said magnetic field signal in response to transitions of said output signal. 15. The method of claim 13 wherein said forcing step comprises bringing said magnetic field signal to substantially the same level as said tracking signal in response to transitions of said output signal. 16. The method of claim 13 wherein said forcing step comprises bringing said tracking signal to a level which is at a fixed offset from said magnetic field signal in response to transitions of said output signal. 17. The method of claim 13 wherein said forcing step comprises bringing said magnetic field signal to a level which is at a fixed offset from said tracking signal in response to transitions of said output signal. 18. The method of claim 13 wherein the step of generating said tracking signal comprises: comparing said magnetic field signal to said tracking signal to generate a feedback signal; counting with a counter in response to said feedback signal to provide a count signal; and converting said count signal to said tracking signal. 19. The method of claim 18 further comprising the step of generating a threshold signal at a predetermined offset with respect to said tracking signal and using said threshold signal to generate said output signal. 20. The method of claim 19 wherein said trackin