Antenna design and interrogator system

• US 10,032,103 B2
• Filed: 03/12/2013
• Issued: 07/24/2018
• Est. Priority Date: 07/13/2012
• Status: Active Grant

• Current Assignee: SATO Holdings Corporation
• Original Assignee: SATO Holdings Corporation
• Inventors: Murdoch, Graham Alexander Munro, Zollinger, Heinz
• Primary Examiner(s): Zimmerman, Brian
• Assistant Examiner(s): Lau, Kevin
• Application Number:
  US13/795,398
• Publication Number:
  US 20140015648A1
• Time in Patent Office: 1,960 Days
• Field of Search: None
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 7/10336 the antenna being of the near field type, inductive coil
• CPC Class Codes: G06K 7/10376 the interrogation device being adapted for being moveable
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 1/2225 used in active tags, i.e. provided with its own power source or in passive tags, i.e. deriving power from RF signal
• CPC Class Codes: H01Q 7/00 Loop antennas with a substantially uniform current distribution around the loop and having a directional radiation pattern in a plane perpendicular to the plane of the loop

Abstract

The present invention relates to the identification of RFID devices that are arranged closely together and placed on shelving for logistical and storage purposes. Furthermore, the aspects of the present invention relate to an arrangement and/or layout of antenna coils for example in an interrogator. There is disclosed a RFID interrogator and/or method of interrogating comprising an antenna, when activated, being adapted to radiate an interrogation signal in a first area, means adapted to shift the antenna within a second area, the second area being larger than the first area. The antenna may be mechanically moveable.

Claims

1. An RFID interrogator moveable linearly along a movement path in a first direction to read a plurality RFID tags disposed along said movement path, comprising:

an antenna having one or more coils, each coil oriented in an area defined by said first direction and a second direction orthogonal to said first direction, and said one or more coils, when activated, being adapted to radiate an interrogation signal in a third direction that is substantially orthogonal to said first and second directions and within a volume defined by a first area and extending in said third direction, the first area being within a larger second area extending along said movement path;

a switching mechanism for sequential activation of said one or more coils to interrogate RFID tags within the volume defined by said first area; and

a motorized mechanism adapted to move the antenna linearly in at least said first direction to a series of positions within the second area,

whereby said antenna, when moved to each position by said motorized mechanism, and said one or more coils, when each coil is sequentially activated at each position, acts to mimic a process of sequentially switching of the coils in a coil array of an antenna formed with a plurality of coils sufficient to cover the second area, whereby said plurality of RFID tags are sequentially interrogated.

2. The RFID interrogator as claimed in claim 1, wherein the antenna is configurable to operate as a virtual antenna having an area larger than the first area.

3. The RFID interrogator as claimed in claim 2, wherein the virtual antenna has an area less than the second area.

4. The RFID interrogator as claimed in claim 1, wherein the antenna is adapted to be shifted in at least one, or in any combination, of the x, y and z directions.

5. The RFID interrogator as claimed in claim 1, wherein the antenna comprises a single coil.

6. The RFID interrogator as claimed in claim 1, wherein the area of the one or more coils is smaller in size than the first area.

7. The RFID interrogator as claimed in claim 1, wherein the antenna is shifted to a series of positions along said movement path within the second area, and where at each position, interrogation is undertaken or activated.

8. The RFID interrogator as claimed in claim 1, wherein the antenna comprises at least two coils.

9. The RFID interrogator as claimed in claim 8, wherein the coils are sequentially switched, and when activated each coil is adapted to radiate an interrogation signal in the first area.

10. The RFID interrogator as claimed in claim 1, wherein antenna movement includes movement that is at least one from among continuous movement and discrete movement.

15. The RFID interrogator as claimed in claim 1, wherein the antenna comprises a first layer of parallel spaced conductors for two-dimensional operations.

16. The RFID interrogator as claimed in claim 15, wherein the antenna comprises a second parallel layer of orthogonally oriented parallel spaced conductors, said first and second parallel layers being arranged for three-dimensional operations.

17. The RFID interrogator as claimed in claim 1, wherein the mimicked process of sequentially switching of the antenna comprises a spatial relationship of sequentially switched currents chosen to provide at different times tangential and normal magnetic fields produced at substantially a same location.

18. The RFID interrogator as claimed in claim 1, wherein the motorized mechanism is powered by at least one onboard battery that is configured to be recharged in response to the RFID interrogator docking with a base station within the second area.

19. The RFID interrogator as claimed in claim 18, wherein the interrogator is configured to automatically dock itself with the base station for charging the battery with power.

11. A method of interrogating a plurality of RFID tags by an RFID interrogator that is moveable linearly along a movement path in a first direction to read the plurality RFID tags disposed along said movement path, the method comprising:

providing an antenna having one or more coils oriented in an area defined by said first direction and a second direction orthogonal to said first direction and adapted to radiate an interrogation signal in a third direction that is substantially orthogonal to said first and second directions and within a volume defined by a first area and extending in said third direction, the first area being within a larger second area extending along said movement path;

moving the antenna linearly along said movement path to a series of positions within the second area by a motorized mechanism;

switching an activation of the one or more coils at each position; and

interrogating at least one RFID tag at each of the series of positions to mimic a process of sequentially switching of the antenna as a coil array,

whereby said antenna, when moved to each position by said motorized mechanism, and said one or more coils, when each coil is sequentially switched to an activated condition at each position, acts to mimic a process of sequentially switching of the coils in a coil array of an antenna formed with a plurality of coils sufficient to cover the second area, whereby said plurality of RFID tags are sequentially interrogated.

12. The method as claimed in claim 11, wherein the antenna is adapted to be shifted in at least one, or in any combination of the x, y and z directions.

20. The method of interrogating by an RFID interrogator as claimed in claim 11, further comprising arranging the plurality of RFID tags on items arranged on a shelf extending along said movement path and wherein the antenna is linearly moved along said movement path using an onboard battery powered motorized mechanism.

21. The method of interrogating by an RFID interrogator as claimed in claim 20, further comprising recharging the onboard battery in response to the RFID interrogator docking with a base station within the second area.

13. A logistics system comprising:

a plurality of RFID tags; and

an RFID interrogator moveable linearly along a movement path in a first direction to read a plurality RFID tags disposed along said movement path, said RFID interrogator comprising;

an antenna having one or more coils oriented in an area defined by said first direction and a second direction orthogonal to said first direction, and when activated, being adapted to radiate an interrogation signal in a third direction that is substantially orthogonal to said first and second directions and within a volume defined by a first area and extending in said third direction, the first area being within a larger second area extending along said movement path;

a switching mechanism for sequential activation of said one or more coils to interrogate RFID tags within the volume defined by said first area; and

a motorized mechanism adapted to move the antenna linearly in said first direction to a series of positions within the second area to mimic the process of sequentially switching of the antenna as a coil array to cover the series of positions in the second area by sequentially switching of the one or more coils in the antenna to achieve such coverage, whereby said plurality of RFID tags are sequentially interrogated,

wherein said system is adapted to identify each of a plurality of items having an associated RFID tag and being disposed at least one of above and below a storage shelf, and

wherein the RFID interrogator is moveable in the movement direction and adapted to radiate the interrogation signal in a direction at least one of above and below the shelf and to identify each item by interrogating the associated RFID tag,

whereby said antenna, when moved to each position by said motorized mechanism, and said one or more coils, when each coil is sequentially switched to an activated condition at each position, acts to mimic a process of sequentially switching of the coils in a coil array of an antenna formed with a plurality of coils sufficient to cover the second area, whereby said plurality of RFID tags are sequentially interrogated.

14. The system as claimed in claim 13, further comprising a memory adapted to store a correspondence between the RFID tag and the item.

22. The system as claimed in claim 13, wherein said RFID interrogator is moveable within said shelf.

23. The system as claimed in claim 13, wherein said RFID interrogator is operative to read RFID tags on both sides of the shelf.

24. The system as claimed in claim 23, wherein the RFID antenna is a screened antenna operable to read an RFID tag on one side of a shelf and not another side of the shelf.