OBJECT LOCATION SYSTEM AND METHOD USING RFID AND GUARD TAGS

Abstract

A system for locating a RFID tag in a space or area having a physical barrier is disclosed herein. More specifically, the system comprises a plurality of guard tags for use in conjunction with a RFID tag disposed on an item and a RFID reader for locating the same. The system is configured to locate the RFID tag on either side of the physical barrier. The plurality of guard tags may comprise a plurality of negative encoded guard tags and a plurality of positive encoded guard tags, and an algorithm may be used to determine a probability of the RFID tag location within the physical space. A method of locating a RFID tag within a physical space, and a method of virtually shielding the physical space is also disclosed.

Claims

1. A system for locating a radio frequency identification (RFID) tag in an area comprising: a RFID tag disposed on an article in the area; a RFID reader in communication with the RFID tag; and a plurality of guard tags positioned in the area.

2. The system of claim 1, wherein the RFID reader is in wireless communication with the RFID tag and at least one of the plurality of guard tags.

3. The system of claim 1, wherein each of the plurality of guard tags is encoded with a location flag and a weight.

4. The system of claim 1, wherein at least one of the plurality of guard tags is a negative guard tag.

5. The system of claim 4, wherein at least one of the plurality of guard tags is a positive guard tag.

6. The system of claim 5, wherein a weight of the negative guard tag is heavier than a weight of the positive guard tag.

7. The system of claim 1, wherein each of the plurality of guard tags comprises a visual indicator.

8. The system of claim 1, wherein the plurality of guard tags is deployable to provide RF shielding to the area.

9. The system of claim 1, wherein the area comprises at least one physical barrier.

10. A method of locating a RFID tag within an area comprising: associating the RFID tag with an article positioned in the area; deploying a plurality of guard tags within the area to provide RF shielding; and transmitting a signal from a RFID reader to the RFID tag to locate the RFID tag within the area.

11. The method of claim 10, wherein there is at least one physical barrier located within the area.

12. The method of claim 10 further comprising the step of assessing a positioning of the plurality of guard tags to maximize the RF shielding of the area.

13. The method of claim 10, further comprising the step of using an algorithm to determine a probability of the RFID tag location within the area.

14. The method of claim 10, wherein at least one of the plurality of guard tags is a negative guard tag.

15. The method of claim 10, wherein at least one of the plurality of guard tags is a positive guard tag.

16. A method virtually RF shielding an area comprising: assessing a need for RF shielding the area; deploying a plurality of guard tags within the area to RF shield the area; and transmitting a RF signal from a RFID reader to a RFID tag to locate the RFID tag within the area.

17. The method of claim 16, wherein at least one of the plurality of guard tags is a high weight tag.

18. The method of claim 17 further comprising the step of assessing where to position the high weight tag with respect to the RFID tag in the area.

19. The method of claim 16, wherein at least one of the plurality of guard tags is a medium weight tag.

20. The method of claim 16, further comprising the step of assessing where to position the medium weight tag with respect to the RFID tag in the area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 illustrates an overhead plan view of a user using a RFID reader within a physical area containing at least one physical barrier to locate a RFID tag, and that has a relatively low probability of locating a RFID tag within said physical area because the RFID reader is being pointed away from the RFID tag.

[0018] FIG. 2 illustrates an overhead plan view of a user using a RFID reader within a physical area containing at least one physical barrier to locate a RFID tag, and that has a relatively higher probability of locating a RFID tag within said physical area because the RFID reader is being pointed in the general direction of the RFID tag.

[0019] FIG. 3 illustrates an overhead plan view of a user using a RFID reader within a physical area containing at least one physical barrier and a plurality of guard tags to locate a RFID tag, and that has a relatively higher probability of locating a RFID tag within said physical area in accordance with the disclosed architecture.

DETAILED DESCRIPTION

[0020] The innovation is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding thereof. It may be evident, however, that the innovation can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate a description thereof.

[0021] Articles, such as retail items being offered for sale in a retail store location or in inventory in a shop or warehouse, are often tagged with a RFID tag for locating and/or tracking purposes. In some cases, the RFID tag may be attached to the outside of the article with a clip, adhesive, tape, hangtag, or other means and, in other cases, the RFID tag may be inserted within the article, such as being included in the packaging, located within the container of the article, or sewn into a garment. A RFID interrogator or reader may then be used to locate or track the article by transmitting electromagnetic energy to stimulate and/or instruct the RFID tag to identify itself and, in some cases, provide additional information and/or data stored in the RFID tag. More specifically, the stimulated RFID tags act as transponders, providing information stored in the chip memory in response to the radio frequency interrogation signal received from the RFID reader. The RFID tag may be active or passive. Active RFID tags are battery powered and capable of providing a very strong signal. In the case of passive RFID tags, the energy of the interrogation signal from the RFID reader also provides the necessary energy to operate the RFID tag.

[0022] As noted above, retail businesses often employ RFID tags to track inventory between the stock room and the shop floor, as it is advantageous for these businesses to have an accurate accounting of inventory and where it is located. As customers purchase the items, a proper accounting allows the business to restock the retail area in a timely and efficient manner. Similarly, the businesses will be able to accurately determine the number of items in reserve in the stock room, or other storage areas, so that they do not run out of items, or order unnecessary inventory and have to store the same for prolonged periods of time, which is not only inefficient but expensive in a retail setting.

[0023] While RFID tags are extremely useful in tracking total inventory in a space, locating specific RFID tags among multitudes of tagged items can be both challenging and time consuming. As radio frequency signals typically penetrate the low adsorption construction of most physical barriers used in retail locations and shops (such as walls, ceilings, floors, partitions and the like), the actual physical location of a particular item can be difficult to ascertain. This is especially true in retail spaces with additional physical barriers such as shelving, changing rooms, etc. For example, many retail locations include a physical area having many of the previously mentioned barriers, in addition to a retail shop floor or exhibition area for displaying merchandise to customers and a back storage or stock room area for holding merchandise in reserve.

[0024] Turning now to the drawings, FIG. 1 illustrates an overhead plan view of a user using a RFID reader 104 within a physical area or space 10 containing at least one physical barrier 40 to locate a RFID tag 102, and that has a relatively low probability of locating a RFID tag within said physical space because the RFID reader is being pointed in a direction away from the RFID tag 102. Physical space 10 may include a retail space, a shop, a store, a warehouse, or the like. Accordingly, the present specification makes specific reference thereto. However, it will be appreciated by those of ordinary skill in the art that aspects of the present invention are also equally amenable to other like applications and devices.

[0025] Physical area or space 10 includes a front room or front of the store 20, such as a display area or a shop floor for displaying merchandise or other items in a plurality of display areas 30, such as racks, shelving, display cases, or the like. The physical space 10 may also further include a back room 50, such as a storage area, a warehouse, a stock room, or the like. The back room 50 may further contain a plurality of storage areas 60, such as shelves, racks, bins, etc., for retaining merchandise in reserve. Finally, the physical space 10 may further include at least one physical barrier, such as wall 40 that separates front room 20 from back room 50 and that may contain common building materials such as wood, metal, drywall, plaster, insulation and the like. As previously mentioned, such common building materials are relatively easily penetrated by radio frequency signals, therefore making it difficult to accurately and efficiently locate an article or object with an RFID tag 102 attached thereto without some means of effective RF shielding, and the use of physical RF shielding can be both expensive to procure and time consuming to install.

[0026] To locate an article 70, such as salable merchandise, within physical space 10, an employee, business owner or other user typically uses a RFID reader 104, such as a hand held scanner to scan an area of the space 10 to locate the article 70 using RFID tag received signal strength indication (RSSI) to determine if the RFID tag 102 is in relatively close proximity to the RFID reader 104, or if it is a further distance away. For example, and as best illustrated in FIG. 1, if the user is in the back room 50 of physical space 10 with the RFID reader 104 pointed in the general direction of one of the plurality of storage areas 60, there is a relatively high probability of locating the article 70 if it is directly in front of the RFID reader 104 (e.g., positioned on one of the plurality of storage areas 60). On the other hand, the probability of locating the article 70 decreases significantly if the RFID reader 104 is directed away from article 70 and its associated RFID tag 102, or if article 70 is in another room, such as front room 20, or otherwise physically separated from RFID reader 104 by a barrier such as wall 40, as best shown in FIG. 1.

[0027] FIG. 2 illustrates an overhead plan view of a user using a RFID reader 104 within a physical area 10 containing at least one physical barrier 40 to locate a RFID tag 102, wherein the RFID reader 104 is being pointed in the general direction of the RFID tag 102. More specifically and similarly to FIG. 1, physical area or space 10 includes a front room 20 having a plurality of display areas 30 (e.g., racks, shelving, display cases, or the like) for displaying articles of merchandise 70 being offered for sale with a RFID tag 102 attached thereto, and a back room 50 having a plurality of storage areas 60 for retaining merchandise in reserve. The physical space 10 further includes at least one physical barrier, such as wall 40 that separates front room 20 from back room 50 and that may contain common building materials such as wood, metal, drywall, plaster, insulation and the like.

[0028] To locate article 70 within physical space 10, an employee or business owner may use a RFID reader 104, such as a hand held scanner to scan an area of the space 10 to locate the article 70 using RFID tag received signal strength indication (RSSI) to determine if the RFID tag 102 is in relatively close proximity to the RFID reader 104, or if it is a further distance away. For example, and as best illustrated in FIG. 2, if the user is in the back room 50 of physical space 10 with the RFID reader 104 pointed in the general direction of article 70 with RFID tag 102 attached thereto, there is a relatively high probability of locating the article 70 even if the two spaces, namely front of store 20 and back room 50, are separated by a physical barrier, such as wall 40.

[0029] The system and methods described herein help to alleviate or reduce the need to have the RFID reader 104 pointed directly at the article 70 (with RFID tag 102 attached thereto) to successfully identify the article 70, and its precise location within a physical space. More specifically, FIG. 3 generally illustrates an area or space 10 that may be virtually RF shielded by a plurality of guard tags 106 to improve the accuracy of locating a RFID tag 102 positioned somewhere within the space 10, even if the space 10 contains one or more barriers, such as wall 40.

[0030] In one embodiment system 100 for locating an RFID tag 102 is described. The system 100 contains an RFID tag 102 attachable to or otherwise disposed on or in an item or article 70 to be located and/or tracked, and a RFID reader 104 in wireless communication with the RFID tag 102. The RFID reader 104 may be configured as a handheld and phased array/multiple read point unit, such as the type manufactured and sold by Avery Dennison Corporation of Pasadena, Calif. RFID reader 104 may be located in a back room 50 of space 10, and capable of reading RFID tags 102 attached to articles of merchandise 70 located in a front room 20. The system 100 further contains a plurality of guard tags 106 located throughout space 10 and in wireless communication with the RFID reader 104 to provide location filtering enhancement, as physical shielding is expensive and structural barriers, such as a physical barrier wall 40, positioned between the front of the store 20 and the back room 50 cannot be accurately relied upon to provide effective RF shielding.

[0031] More specifically, the system 100 utilizes the plurality of spaced apart and strategically positioned guard tags 106 to create a more effective virtual RF shielding than is currently available through the use of physical barriers and/or electromagnetic shielding materials, such as copper, sheet metal, metal screen, and metal foam, each of which can be expensive to purchase and time consuming to install. Further, the virtual RF shielding created by the use of positive and negative guard tags 106 eliminates or significantly reduces the problems historically associated with any holes or openings in the physical electromagnetic shielding materials of the prior art discussed supra.

[0032] The virtual RF shielding also enables the retailer, shop owner or other user to determine the location of a RFID tag 102 from a different location within physical space 10 (i.e., a different room or sub-space), such as the back room 50. The plurality of guard tags 106 may include at least one negative guard tag 108, and/or at least one positive guard tag 110. Each of the plurality of guard tags 106 is locatable throughout the space 10, preferably in spaced apart orientation as best shown in FIG. 3. For example, the guard tags 106 may be located on or affixed to walls, the ceiling or shelving 60 in the back room 50, and deployable on the physical barrier or wall 40. Additional guard tags 106 may be located on or affixed to other walls, the ceiling, the floor or other structures, such as racks/display units 30 in the front of store 20. Further, depending on how each of the plurality of guard tags 106 is being read or not being read by the RFID reader 104, it is possible to assign a probability of a particular RFID tag 102 (and the article 70 to which it is attached) being located in the back room 50 or the front of the store 20.

[0033] Each of RFID tags 102 and guard tags 106 may be active or passive in nature and include labels and inlays, such as those commonly manufactured and sold by Avery Dennison Corporation of Pasadena, Calif. As the guard tags 106 are effectively standard labels, or low cost metal tags, such as, but not limited to, AD460 or AD454 tags, or the like, the RFID guard tags 106 may be easily stuck to walls or other structures within physical space 10. Low cost on-metal tags, such as the AD460 RFID tags, are desirable as they reduce reflection effects, and permit relatively easy mounting in a store and stock room without the need for additional mounting materials, hardware, and/or tools. Further, the number of RFID guard tags 106 used and their strategic placement within physical space 10 will help boost the location determination probability that a particular RFID tag 102 (and the article 70 to which it is attached) will be identified and located by RFID reader system 104 within physical space 10.

[0034] Additionally, each of the plurality of guard tags 106 may be encoded with a location/direction flag, a weighting (e.g., shop floor tags may have a higher weight than that which is assigned to a wall tag), RSSI level at threshold, sensitivity, etc. The weight or weighting RSSI level at threshold is based on whether the particular guard tag 106 is a negative tag 108 or a positive tag 110. The plurality of guard tags 106 is deployable to shield the physical space 10. Typically, the negative guard tags 108 have relatively higher weights, and are preferably deployed in the shop floor or front of the store 20. Conversely, the positive guard tags 110 have medium weights (or weights less than the negative guard tags 108), and are preferably deployed in the stock or back room 50. Additionally, each of the plurality of guard tags 106 may include a visual indicator, such as a color coding or other physical marking that enables an installer of the guard tags 106 to easily differentiate between the negative guard tags 110 and the positive guard tags 110 during the installation process.

[0035] In other embodiments, a method of virtually shielding a physical area 10 having at least one physical barrier 40 (e.g., walls, floors, ceilings, partitions and the like) is disclosed. Generally stated, the method includes the following steps: (a) assessing a need for RF shielding a physical area 10 having at least one barrier 40; (b) deploying a plurality of guard tags 106 to RF shield the physical area 10; and (c) transmitting a RF signal from a RFID reader 104 to a RFID tag 102 to locate the RFID tag 102 within the physical area 10 and to confirm the RF shielding of the physical area 10. At least one of the plurality of guard tags 106 is preferably a negative guard tag 108 with a location flag and a relatively high weight, and at least one of the plurality of guard tags 106 is preferably a positive guard tag 110 with a location flag and having a weight that is preferably less than the weight of the negative guard tag 108.

[0036] The number of guard tags 106 that need to be deployed may vary depending on the existing and/or natural RF shielding of the space 10, such as physical barriers 40 that may provide some degree of RF shielding between a back room 50 and a shop floor or front of the store 20. For example, if adequate natural or existing RF shielding already exists, no guard tags 106 may be required. On the other hand, if little to no existing or natural RF shielding exists, several guard tags 106 may need to be placed throughout the space 10 (e.g., on walls, ceilings, fixtures, etc.).

[0037] The method of virtually RF shielding a physical area 10 may further include assessing where to position the high weight negative guard tags 108 and/or the lesser weight positive guard tags 110 with respect to the RFID tag 102 to maximize the benefits of the RF shielding, and to improve location accuracy. In one example of assessing where to place the plurality of guard tags 106, an installer may elect to place a negative guard tag 108 in the front of the store 10 at a location that is relatively near to the article 70 to be tracked or located in the future.

[0038] In still other embodiments, a method of locating an object or article 70 with a RFID tag 102 attached thereto in an area 10 including at least one physical barrier 40 (e.g., walls, floors, ceilings, partitions and the like) is disclosed. In some embodiments, the method includes: (a) associating an RFID tag 102 with an item or article 70 to be located or tracked within a physical area 10 having at least one physical barrier 40; (b) deploying a plurality of guard tags 106 within the physical area 10 having at least one barrier 40; and (c) transmitting a RFID signal from a RFID reader 104 to the RFID tag 102 to locate the RFID tag 102 within the physical area 10. The deployment of the plurality of guard tags 106 within the space 10 creates a virtual RF shielding effect that is more effective and efficient than the physical RF shielding of the prior art.

[0039] The method may further include assessing the positioning of the plurality of guard tags 106 within the physical area 10 to maximize the shielding of the physical area 10, and/or using an algorithm to determine a probability of the RFID tag 102 location within the physical area 10. At least one of the plurality of guard tags 106 is preferably a negative guard tag 108 with a location flag and a relatively high weight, and at least one of the plurality of guard tags 106 is preferably a positive guard tag 110 with a location flag and having a weight that is less than the weight of the negative guard tag 108.

[0040] For example, hand held RFID reader 104 can be used to read guard tags 106, assess the amount of RF penetration within space 10 and recommend a label deployment. The method may further include using an algorithm 112 to determine the probability of the location of the RFID tag 102 within the space. In one embodiment, the probability of the RFID tag 102 being in either the front room 20 or the back room 50 can be determined by the following algorithm 112, with various inputs possible. For example:

[0041] If P.sub.L=the probability that a particular RFID tag 102 is located in the back room 50; and

[0042] If T.sub.W=Tag weight (RSSI, Read Rate, Tag sensitivity), then

[0043] P.sub.L=Product tag (T.sub.W)−Guard tag (T.sub.W).

So, if the T.sub.W of the RFID tag 102 for the item 70 is high, and the T.sub.W of the guard tag 106 is low (e.g., the RFID reader 104 is not pointing toward the front room 20 or attenuation from the infrastructure is high), the probability of the RFID tag 102 being in the back room 50 is high.

[0044] Conversely, if the T.sub.W of the RFID tag 102 for the item 70 is medium or low, and the T.sub.W of the guard tag 106 is high (e.g., the RFID reader 104 is pointing toward the front room 20 or attenuation from the infrastructure is high), the probability of the RFID tag 102 being in the back room 50 is low. Additionally, data gathered by the RFID reader 104 can also be sent to a host for post processing, or, for example, if the guard tag 106 being read is on the shop floor in the front room 20, the user may reduce the RFID reader 104 output power until the RFID reader 104 stops reading. For a particular RFID tag 102, the probability may be an integral over time, given that the RFID reader 104 is being moved about.

[0045] What has been described above includes examples of the claimed subject matter. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the claimed subject matter, but one of ordinary skill in the art may recognize that many further combinations and permutations of the claimed subject matter are possible. Accordingly, the claimed subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.