System and method for electronic inventory

• US 7,035,818 B1
• Filed: 06/01/1999
• Issued: 04/25/2006
• Est. Priority Date: 11/21/1997
• Status: Expired due to Term

• Current Assignee: Symbol Technologies, LLC (Zebra Technologies Corporation)
• Original Assignee: Symbol Technologies, Inc. (Zebra Technologies Corporation)
• Inventors: Bandy, William R., Arneson, Michael R., Williams, Robert A.
• Primary Examiner(s): Myhre, James W.
• Application Number:
  US09/323,206
• Time in Patent Office: 2,520 Days
• Field of Search: 705/22, 705/23, 705/28
• US Class Current: 705/28
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders
• CPC Class Codes: G06Q 20/203 Inventory monitoring
• CPC Class Codes: G06Q 20/208 Input by product or record sensing, e.g. weighing or scanner processing

Abstract

A system and method for conducting an inventory of tags, wherein each tag is assigned a Tag ID and a manufacturer number. Each tag can be attached to an item to take inventory of those items. A tag reader transmits a wake-up signal followed by at least one clock signal. Each tag increments a first tag count in response to the clock signals, and transmits the Tag ID assigned to the tag when the first tag count corresponds to the Tag ID assigned to the tag. The tag reader records the transmitted Tag IDs. When more than one tag transmits simultaneously, the tag stores the Tag ID in order to resolve the contention when the first read cycle is complete. In the second read cycle, the tag reader transmits the contended Tag ID followed by at least one clock signal. Each tag that contended for the transmitted Tag ID increments a second tag count in response to the clock signals, and transmits the manufacturer number assigned to the tag when the second tag count corresponds to the manufacturer number assigned to the tag. The tag reader records the transmitted Tag IDs, completing the inventory of the tags.

Claims

1. An automated, real-time electronic inventory system, comprising:

(A) a plurality of radio frequency identification (RFID) tags, wherein each tag is assigned a first permanent identification number and a second permanent identification number, wherein said RFID tags are configured to receive and transmit signals;

(B) a tag reader having means for transmitting a signal to said RFID tags and means for resolving contention between multiple RFID tags that respond to said signal; and

(C) wherein said RFID tags are configured to receive said signal from said reader, evaluate said first or second permanent identification numbers in response to receiving said signal, and reply to said signal if appropriate.

2. The electronic inventory system of claim 1, wherein at least one of said plurality of RFID tags has a sensor;

and means for transmitting the contents of said sensor.

3. The electronic inventory system of claim 1, wherein said signal is a clock signal, and said tag reader emits a series of clock signals, wherein each clock signal defines a time slot.

4. The electronic inventory system of claim 3, wherein each RFID tag counts said clock signals and when the count is equivalent to said first permanent identification number, transmits its reply to said tag reader.

5. The electronic inventory system of claim 4, wherein said tag reader accumulates said replies of each tag that responded.

6. The electronic inventory system of claim 5, wherein said tag reader polls all tags whose reply conflicted with another tag.

7. The electronic inventory system of claim 1, wherein said first and second permanent identification numbers are a tag identification number (Tag ID) and a manufacturer number, wherein said signal is a clock signal, wherein each tag further comprises:

means for receiving a wake-up signal followed by a first clock signal;

means for incrementing a first tag count in response to said first clock signal;

means for transmitting said Tag ID assigned to said tag when said Tag ID corresponds to said first tag count;

means for receiving a second clock signal;

means for incrementing a second tag count in response to said second clock signal; and

means for transmitting said manufacturer number assigned to said tag when said manufacturer number of said tag corresponds to said second count.

8. The electronic inventory system of claim 1, wherein said first and second permanent identification numbers are a tag identification number (Tag ID) and a manufacturer number, wherein said signal is a clock signal, wherein said tag reader comprises:

means for transmitting a wake-up signal followed by a first clock signal;

means for incrementing a first reader count in response to said first clock signal,

means for receiving a Tag ID transmitted by a tag in response to said first clock signal;

means for storing a given first reader count when more than one tag responds to said first clock signal that corresponds to said given first reader count;

means for transmitting said given first reader count followed by a second clock signal; and

means for receiving a manufacturer number transmitted by a tag in response to said second clock signal.

9. The electronic inventory system of claim 1, wherein at least one of said plurality of RFID tags is manufactured on a flexible substrate.

10. The electronic inventory system of claim 1, wherein said tag reader includes a PCMCIA card that is configured for a specific application.

11. An automated, real-time electronic inventory system, comprising:

(A) a plurality of radio frequency identification (RFID) tags, wherein each tag is assigned a plurality of identification numbers, wherein said RFID tags are configured to receive and transmit signals;

(B) a tag reader having means for transmitting a signal to said RFID tags and means for resolving contention between multiple RFID tags that respond to said signal; and

(C) wherein said RFID tags are configured to receive said signal from said tag reader, evaluate one or more of said plurality of identification numbers, and reply to said signal if appropriate.

12. The electronic inventory system of claim 11, wherein said tag reader can initiate an immediate read of said RFID tags, a specific RFID tag read, or a timed broadcast read of said RFID tags.

13. The electronic inventory system of claim 11, wherein at least one of the plurality of RFID tags has a sensor.

14. The electronic inventory system of claim 11, wherein at least one of said plurality of RFID tags is manufactured on a flexible substrate.

15. The electronic inventory system of claim 11, wherein said tag reader includes a PCMCIA card that is configured for a specific application.

16. A system for locating a tag, wherein each tag is assigned a first permanent identification number and a second permanent identification number, the system comprising:

a tag reader configured to transmit a first value corresponding to the first permanent identification number of a tag to be located and a second value corresponding to the second permanent identification number of a tag to be located; and

a tag that transmits, in response to receiving said first value, the first permanent identification number assigned to said tag when the first permanent identification number assigned to said tag corresponds to said first value, wherein said tag further transmits, in response to receiving said second value, the second permanent identification number assigned to said tag when the second permanent identification number assigned to said tag corresponds to said second value.

17. The system of claim 16, wherein said tag includes a sensor.

18. The system of claim 16, wherein said tag is manufactured on a flexible substrate.

19. The system of claim 16, wherein said tag reader includes a PCMCIA card that is configured for a specific application.

20. A radio frequency identification tag, wherein each tag is assigned a first permanent identification number and a second permanent identification number, wherein the tag is interrogated by a tag reader having means for transmitting a first clock signal and for incrementing a first reader count in response to the first clock signal, means for storing the first reader count when more than one tag responds to the first clock signal that corresponds to the first reader count, and means for transmitting the stored first reader count followed by a second clock signal, the tag comprising:

means for incrementing a first tag count in response to the first clock signal,

means for transmitting the first permanent identification number assigned to the tag when the permanent identification number of the tag corresponds to said first tag count,

means for incrementing a second tag count in response to receiving the second clock signal, and

means for transmitting the second permanent identification number assigned to the tag when the second permanent identification number of the tag corresponds to said second tag count.

21. The radio frequency identification tag of claim 20, wherein the tag further includes a sensor.

22. The radio frequency identification tag of claim 20, wherein the tag is manufactured on a flexible substrate.

23. A method for conducting an inventory of tags, wherein each tag is assigned a first permanent identification number and a second permanent identification number, the method comprising the steps of:

at a tag reader, transmitting a first clock signal, waiting for a reply from a plurality of the tags, and transmitting a first reader count followed by a second clock signal;

at each tag,

incrementing a first tag count in response to said first clock signal and

transmitting the first permanent identification number assigned to said tag when the first permanent identification number of said tag corresponds to said first tag count; and

at each tag that responds to said transmitted first reader count,

incrementing a second tag count in response to said second clock signal, and

transmitting the second permanent identification number assigned to said tag when the second permanent identification number of said tag corresponds to said second tag count.

24. A method for conducting an electronic inventory of radio frequency identification tags, the method comprising the steps of:

(A) transmitting a first signal to a plurality of radio frequency identification (RFID) tags, wherein each tag is assigned a first identification number and a second identification number, wherein said RFID tags are configured to receive and transmit signals;

(B) receiving a reply from said plurality of RFID tags, said tags responding to said first signal based on the value of said first identification number; and

(C) resolving contention between multiple RFID tags if there is a conflict between at least two of said RFID tags subsequent to said RFID tags responding to said first signal, including transmitting a second signal to said plurality of RFID tags.

25. The method of claim 24, wherein at least one of said RFID tags includes a sensor, the method further including receiving sensor data from at least one RFID tag.

26. The method of claim 25, further comprising receiving a reply to said second signal from at least one RFID tag based on the value of said second identification number.