Device for verifying a location of a radio-frequency identification (RFID ...

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DEVICE FOR VERIFYING A LOCATION OF
A RADIO-FREQUENCY IDENTIFICATION
(RFID) TAG ON AN ITEM

TECHNICAL FIELD 5

The present invention relates to a device for verifying a location of a radio-frequency identification (RFID) tag on an item. The present invention relates more particularly to a 1Q device for verifying the location of an RFID tag on an item including: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, and where the item holder includes a non-readable 15 volume where the RF antenna cannot read or write to an RFID tag. The present invention also relates more particularly to methods of verifying the location of a radio-frequency identification (RFID) tag on an item.

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BACKGROUND OF THE INVENTION

Radio-Frequency Identification (RFID) technology has become widely used in virtually every industry, including 25 transportation, manufacturing, waste management, postal tracking, airline baggage reconciliation, and highway toll management. A typical RFID system includes a plurality of RFID tags, at least one RFID reader or detection system having an antenna for communication with the RFID tags, 30 and a computing device to control the RFID reader. The RFID reader includes a transmitter that may provide energy or information to the tags, and a receiver to receive identity and other information from the tags. The computing device processes the information obtained by the RFID reader. 35

A variety of RFID applications, systems and tags are known. For example, U.S. Patent Application Publication entitled, "Radio Frequency Identification in Document Management," (Eisenberg et al.), Publication No. 2002/0196126 Al, discloses various systems and methods of handling items with RFID tags, such as files. As another example, PCT Publication WO 00/10122 A2, "Radio Frequency Identification Systems Applications," (Garber, et al.) describes the use of RFID systems for use with items of interest having 45 RFID tags, such as in a library. As yet another example, U.S. Pat. Ser. No. 6,768,419, "Applications for Radio Frequency Identification Systems" (Garber, et al.) describes RFID devices, including handheld RFID devices, and applications for such devices. Another example, U.S. Patent Publication 50 No. 2003/0189490 Al, "Radio-Frequency Identification Tag and Tape Applicator, Radio-Frequency Identification Tag Applicator, and Methods of Applying Radio-Frequency Identification Tags" describes methods of applying a radiofrequency identification tag to tape and radio-frequency 55 identification tag and tape applicators.

One example of RFID tags is described in U.S. patent application Ser. No. 10/820,584, entitled "Variable Frequency Radio Frequency Identification (RFID) Tags," g0 (Waldner and Erickson), which describes various radio frequency identification (RFID) tags that dynamically vary their resonant frequency to reduce or eliminate the potential effects of electromagnetic "tag-to-tag" coupling. Another example of RFID tags is described in U.S. patent application 65 Ser. No. 10/807,072, "Radiofrequency Identification Tags with Compensating Circuitry."

SUMMARY OF THE INVENTION

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One aspect of the present invention provides a device for verifying a location of a radio-frequency identification (RFID) tag on an item. In one embodiment, the device comprises: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, and where the item holder includes a non-readable volume where the RF antenna cannot read or write to an RFID tag.

In another embodiment, the device for verifying a location of a radio-frequency identification (RFID) tag on an item comprises: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, where the item holder includes a non-readable volume where the RF antenna can not read or write to an RFID tag, when an RFID tag is within the readable volume of the item holder, then the RFID tag is properly located on the item, and when an RFID tag is within the non-readable volume of the holder, the RFID tag is not properly located on the item.

In yet another embodiment, the device for verifying a location of a radio-frequency identification (RFID) tag on an item comprises: an item holder; and an RF antenna attached to the item holder, where the RF antenna is designed to provide a readable volume where the RF antenna can read or write to an RFID tag, where the item holder is designed to further shape the readable volume of the RF antenna, and where if an RFID tag is within the readable volume of the RF antenna, then the device verifies that the RFID tag is properly located on the item.

The present invention also provides a system for verifying a location of a radio-frequency identification (RFID) tag on an item. In one embodiment, the system comprises: an item holder; an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, where the item holder includes a non-readable volume where the RF antenna can not read or write to an RFID tag; and an item having an RFID tag attached to the item associated with the item holder where if the RFID tag is within the readable volume of the item holder, then the system verifies that the RFID tag is properly located on the item, and where if the RFID tag is not within the readable volume of the item holder, then the system verifies that the RFID tag is not properly located on the item.

In one aspect of the embodiments mentioned above, the device or system further includes an RFID reader in operative connection to the RF antenna, where the RF antenna transmits read or write command signals to RFID tags from the RFID reader. In another aspect of the embodiments mentioned above, when an RFID tag is within the readable volume, the RFID tag is properly located on an item, and when an RFID tag is within the non-readable volume of the holder, the RFID tag is not properly located on an item. In another aspect of the embodiments mentioned above, the device signals to a user if the RFID tag is properly located on an item. In yet another aspect of the embodiments mentioned above, the item holder further comprises metal in the non-readable volume. In another aspect of the embodiments mentioned above, the device or system further comprises a sensor attached to the item holder, when the sensor is activated, the RF antenna transmits read or write command signals to RFID tags. In yet another aspect of the embodiments mentioned above, the device or system further 3

comprises a file having an RFID tag attached to the file associated with the item holder.

The present invention also provides a method of verifying the location of a radio-frequency identification (RFID) tag on an item. In one embodiment, the method comprising the steps of: providing a device for verifying a location of a radio-frequency identification (RFID) tag on an item, comprising: an item holder; and an RF antenna attached to the item holder, where the item holder includes a readable volume where the RF antenna can read or write to an RFID tag, and where the item holder includes a non-readable volume where the RF antenna cannot read or write to an RFID tag; attaching an RFID tag to an item; inserting the item into the device; transmitting write command signals to the RFID tags; and verifying the proper location of the RFID tag on the item, if the signals were successfully read or written on the RFID tag.

In one aspect of the above method, the device further comprises an RFID reader in operative connection to the RF antenna, where the transmitting step includes the RF antenna transmitting read or write command signals to RFID tags from the RFID reader. In another aspect of the above method, the verifying step further comprises signaling that the RFID tag is in a proper location on the item when the signals were successfully read or written on the RFID tag. In another aspect of the above method, the verifying step further comprises verifying the proper location when the RFID tag on the item is within the readable volume of the item holder, and signaling that the RFID tag is not in a proper location on the item when the RFID tag on the item is not within the readable volume of the holder. In yet another aspect of the above method, the item holder further comprises metal in the non-readable volume. In another aspect of the above method, the device further comprises a sensor attached to the item holder, and when the sensor is activated, the RF antenna transmits read or write command signals to RFID tags. In yet another aspect of the above method, the attaching step comprises attaching the RFID tag to a file.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be further explained with reference to the appended Figures, wherein like structure is referred to by like numerals throughout the several views, and wherein:

FIG. 1 is a front perspective view of a file tracking system;

FIG. 2 is a side view of a row of files stored on a shelf in the file tracking system of FIG. 1;

FIG. 3 is a side view of a file having an RFID tag;

FIG. 4 is a side view of one embodiment of the device of the present invention for verifying a location of a radiofrequency identification tag on an item, and an item inserted into the device, such as the file of FIG. 3; and

FIG. 5 is a perspective view of the device of FIG. 4.

DETAILED DESCRIPTION OF THE
INVENTION

A variety of items or objects are now being tagged with radio frequency identification (RFID) tags for use in RFID systems that will assist in identifying the item and tracking the item through various processes. The present invention provides a device and methods for verifying a location of a RFID tag on an item or object. For a variety of applications and processes, it may be necessary to have the RFID tag located in a particular area on the item and not located in

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other areas on the item, and where it is desirable to have an RFID tag attached to the item in a predictable location, depending on the application or process. If the RFID tag is not located in its proper location on the object, the RFID

5 system may fail to read the RFID tag and as a result, the information stored on the RFID tag will not be recorded by the RFID system and it will affect the performance of the RFID system and systems or persons relying upon information read by the RFID system. Therefore, there is a need to

10 provide a device and methods that assist a user in verifying whether or not an RFID tag is properly located on an item or object.

One example where RFID tag placement on items or objects could be important are on products that are being

15 further processed by a customer. For example, pallets being delivered to Wal*mart stores are now required to each have RFID tags that identify the products on the pallet. The Wal*mart stores may have specific methods of reading the RFID tags with particular RFID readers and particular

20 methods of unloading the products from the pallet. To meet Wal*mart's requirements for further processing, the provider of the products may need to attach the RFID tag in a particular location on the pallet to make it easier for Wal*mart to further process the pallet and the items thereon

25 at their locations.

As another example, many parts are being provided with RFID tags where the parts are later assembled into a final product or assembly by a customer. When the parts are supplied to the customer, the placement of the RFID tag

30 could be important when it comes time for the customer to assemble their final product. The customer may require that the part include the RFID tag in a particular location, so that when the final product is assembled the RFID tag can be easily read. Otherwise, if the RFID tag is in the wrong

35 location, the RFID tag may not be readable when the final part is assembled.

As yet another example, an item or object may require multiple RFID tags in different locations each having a different frequency. For example, a pallet may require one

40 RFID tag having a frequency of 13.56 MHz and another RFID tag having a frequency of 915 MHz. The 915 MHz tag has a longer read range and may be read in the warehouse, when the pallet is being stored. The 13.56 MHz tag has a shorter read range and may be read along a conveyor belt as

45 it is being transported to the manufacturing line.

Another example of items having an RFID tag attached to them is files. Despite some interest in converting offices to paperless environments in which paper documents are entirely replaced by electronic versions of those documents,

50 a number of industries continue to rely heavily on paper documents. Examples include law offices, government agencies, and facilities for storing business, criminal, and medical records. In some instances these records are stored in enclosed filing cabinets. In other instances, the files 40 are

55 positioned on open shelves 38 of the type shown in FIG. 1. Documents and files can also be found in other locations, including on desks and tables, in drawers, on carts, or stacked on the floor.

At least three patent publications describe the use of radio

60 frequency identification (RFID) systems for document or file management: 1) U.S. Pat. Ser. No. 5,689,238 (Cannon, Jr. et al.); 2) PCT Published patent application Ser. No. WO 00/16280; and 3) U.S. Patent Application Publication entitled, "Radio Frequency Identification in Document Man

65 agement," (Eisenberg et al.), Publication Ser. No. 2002/ 0196126 Al, which is assigned to the assignee of the present invention and the contents of which are incorporated by 5

reference herein. Although the various aspects of the present invention will largely be described in the context of files or documents or both, the device of the present invention may be used in verifying the location of RFID tags on other items including books, video tapes, optically-recorded media, or 5 retail items, pallets, containers, or other assets, as appropriate, whether or not each of these items is specifically called out as an alternative application.

RFID tags or labels 42 are made by various manufacturers including Texas Instruments of Dallas Tex., under the des- 10 ignation "Tag-it". Another type of RFID tag is actually a combination tag that includes an RFID element and a magnetic security element, and is described in U.S. Pat. No. 6,154,137, which is assigned to the assignee of the present invention, the contents of which is incorporated by reference 15 herein. Yet another type of RFID tag is described in U.S. patent application Ser. No. 10/820,584, entitled "Variable Frequency Radio Frequency Identification (RFID) Tags," (Waldner and Erickson), which is assigned to the assignee of the present invention, the contents of which is incorporated 20 by reference herein. An RFID tag typically includes an integrated circuit with a certain amount of memory, a portion of which may be used by the manufacturer to write certain information to the tag (and perhaps lock it to protect it from being changed or overwritten), and another portion of which 25 may be used by a purchaser to store additional information to the tag. The integrated circuit is operatively connected to a radio frequency (RF) antenna that receives RF energy from a source and also backscatters RF energy in a manner well known in the art. It is this backscattered RF energy that 30 provides a signal that may be received by an interrogator or reader to obtain information about the RFID tag, and the item with which it is associated. RFID tags may operate in one or more different frequency ranges, such as the Tag-it RFID tags sold by Texas Instruments, which operate at 13.56 35 MHz.

RFID tags may be associated with or applied to items of interest, as described above. The tag may even be embedded within the item or the packaging of the item so that the tag is at least substantially imperceptible, which can help to 40 prevent detection and tampering. Thus, it would be possible to "source-mark" items with an RFID tag, such as inserting an RFID tag into or applying an RFID tag to an item during its manufacture, as with a book, compact disc, consumer product, file folder, pallet, carton, box-sealing tape, shipping 45 label, or the like.

In conventional RFID systems, RFID tags may interfere with one another when the RFID tags are placed in close proximity to one another. It has been determined that electromagnetic coupling between such tags may result in a shift 50 of the resonant frequencies of the tags. This shifted resonant frequency may not provide a given one of the RFID tags with a sufficient induced current to power the tag, thereby causing the RFID tag to be out of the detectable frequency range of the interrogation device. 55

In general, the magnitude of the resulting frequency shift is dependent upon the distance between the RFID tags, the size of the tags, the amount of coplanar overlapping that occurs between the tags, and the total number of tags that overlap. Some exemplary measurements of frequency shift 60 due to "tag-to-tag" coupling are shown in Table 1 below when multiple tags where placed within a fixed proximity of each other in an overlapping position. In Table 1, A is the height of the tag, B is the width of the tag, N is the number of overlapping tags, X is the distance between consecutive 65 tags, and F is the resultant resonant frequency of the tag. Although the exemplary measurements shown in Table 1 are

One method of overcoming the tag-to-tag interaction is to reduce the degree to which adjacent tags overlap each other. This can be done by increasing the distance between adjacent tags. Alternatively, tag-to-tag interaction may be reduced by systematically staggering the locations of RFID tags associated with file folders, documents, containers, or other items so that it is very unlikely that the tags on two adjacent items would overlap each other to any substantial degree. Use of the device 10 of the present invention to verify the proper placement in a systematically staggered tag system would also help ensure proper functioning of such a system.

However, it may not always be possible to increase the distance between adjacent tags on items, such as requiring fixed file storage spacers, because it may require additional filing space that may be expensive to maintain. It also may not always be possible to stagger the locations of the RFID tags because although this method may initially reduce the tag-to-tag interaction when the files are first stored on the shelf, due to the insertion and removal of files over time, the files may become unordered and ultimately lead to the overlapping of tags and thus, tag-to-tag interaction.

The inventors of the present invention have discovered that the magnitude of the resulting frequency will tend to stabilize after a certain number of tags on various items have been successively overlapped. As a result, if a series of similar items each having an RFID tag attached to them in relatively the same general area are stacked either vertically or horizontally relative to each other (for example, RFID tagged files stored on a shelf illustrated in FIG. 2), such that the RFID tags on the items overlap causing tag-to-tag interaction, then it is possible to predict and control the magnitude of the resulting resonant frequency. For example, if ten items each having an RFID tag of approximately the same general area and the antennas of the RFID tags are tuned to approximately 20 MHz, then an RFID reader operating at 13.56 MHz will be able to successfully read the majority of the RFID tags when the items are adjacent one another. However, to achieve the desired resonant frequency that is a result of the tag-to-tag interaction in an application such as closely spaced files, it is desirable to attach the RFID tags to the items in the same general area. For example, the files 40 illustrated on the shelf 38 in FIG. 2 each have an RFID tag 42 that is attached in approximately the same area of the file 40, such that when the files are aligned and stored