Inventory tracking using RFID

• US 10,089,505 B1
• Filed: 09/29/2015
• Issued: 10/02/2018
• Est. Priority Date: 09/29/2015
• Status: Active Grant

• Current Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Original Assignee: Amazon Technologies, Inc. (Amazon.com, Inc.)
• Inventors: Huebner, Ronald Eugene, Niranjayan, Somasundaram, Hahn, Camerin
• Primary Examiner(s): Vo, Tuyen K
• Application Number:
  US14/869,882
• Time in Patent Office: 1,099 Days
• Field of Search: 235375, 235383, 235385, 235451, 235492
• CPC Class Codes: G06K 7/10316 using at least one antenna particularly designed for interrogating the wireless record carriers antennas in general H01Q1/22
• CPC Class Codes: G06K 7/10415 the interrogation device being fixed in its position, such as an access control device for reading wireless access cards, or a wireless ATM banking machines in general G07F19/00
• CPC Class Codes: G06Q 10/087 Inventory or stock management, e.g. order filling, procurement or balancing against orders
• CPC Class Codes: G07F 11/64 in which the articles are individually suspended from stationary supports
• CPC Class Codes: G07G 1/009 the reader being an RFID reader
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• 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 13/203 Leaky coaxial lines

Abstract

A storage unit includes a support bar for hanging items and an RFID antenna provided within a predefined distance of the support bar. When the items hanging from the support bar are adorned with RFID tags, and the RFID antenna emits electromagnetic fields in a direction of the support bar, RFID signals identifying the items are transmitted from the RFID tags to the RFID antenna, thereby enabling a placement or a removal of an item to be automatically registered, or an accounting of the available items to be automatically performed. The RFID antenna may be a portion of a transmission line that uses shields and/or dielectric materials to shape the electromagnetic fields toward a predefined direction, and the locations of items bearing RFID tags on the support bar may be determined by varying the phase of the emitted radiofrequency and determining strengths of RFID signals when the electromagnetic fields are emitted at varying phases.

Claims

1. An inventory area comprising:

a panel;

a storage unit releasably mounted to the panel, wherein the storage unit comprises;

a base;

a support bar having a proximal end mounted to a front face of the base, wherein a first section comprising the proximal end of the support bar extends substantially perpendicular to the front face of the base; and

a transmission line having a proximal end mounted to the front face of the base at a predefined distance above the support bar, wherein the transmission line comprises;

an RFID antenna configured to emit an electromagnetic field in at least a radial distance of the support bar, wherein the RFID antenna is coupled to an RFID reader, and wherein the RFID antenna extends substantially perpendicular to the front face of the base and substantially parallel to the support bar;

a shield extending along a length of the RFID antenna at a predetermined distance from the RFID antenna; and

a dielectric buffer extending along the length of the RFID antenna, wherein the dielectric buffer is provided between the shield and the RFID antenna within the predetermined distance; and

an item suspended from the support bar, wherein the item comprises an RFID tag programmed to emit an RFID signal when the RFID tag senses the electromagnetic field.

2. The inventory area of claim 1, wherein the RFID antenna comprises a conductive rod formed from at least one of steel, aluminum or copper,

wherein the shield defines a cross-section surrounding at least a portion of a circumference of the conductive rod at the predetermined distance, and

wherein the dielectric buffer comprises a layer formed from at least one of acrylic or acrylonitrile butadiene styrene extending between the portion of the circumference of the conductive rod and the shield.

3. The inventory area of claim 1, wherein the cross-section of the shield has a shape of at least a portion of:

a circle;

a rectangle;

a triangle;

or

an octagon.

4. A method comprising:

emitting an electromagnetic field from a RFID transmission line comprising an RFID antenna, a support bar and a dielectric buffer, wherein the RFID antenna extends in parallel to at least a first section of a support bar, wherein the dielectric buffer extends in parallel to at least the first section of the support bar along a portion of a length of the RFID antenna, wherein the electromagnetic field is emitted in at least a first radial direction from the RFID antenna toward the support bar, wherein the dielectric buffer is provided in at least a second radial direction from the RFID antenna away from the support bar;

receiving, by the RFID antenna, a first RFID signal from a first RFID tag borne by a first item suspended from the first section of the support bar;

interpreting contents of the first RFID signal using at least one computer processor;

identifying information regarding the first RFID tag based at least in part on the interpreted contents of the first RFID signal using the at least one computer processor;

identifying a first item bearing the first RFID tag based at least in part on the information regarding the first RFID tag using the at least one computer processor;

determining that one of the first item bearing the first RFID tag is disposed on the support bar based at least in part on the first RFID signal using the at least one computer processor; and

storing first information in at least one data store, wherein the first information associates the one of the first item bearing the first RFID tag with the support bar,

wherein the RFID transmission line is configured to inhibit the electromagnetic field in at least the second radial direction, and

wherein the RFID transmission line is configured to not inhibit the electromagnetic field in at least the first radial direction.

5. The method of claim 4, wherein the RFID antenna defines a first axis, and

wherein the RFID transmission line further comprises:

a shield, wherein at least a portion of the shield is provided at a first distance from at least a portion of a circumference of the RFID antenna in parallel to the first axis,

wherein the dielectric buffer extends in parallel to at least the first section of the support bar between the portion of the RFID antenna and the shield along at least the portion of the circumference of the RFID antenna.

6. The method of claim 5, wherein the RFID transmission line defines a cross-section having a shape of one of:

a sector, wherein the shield defines at least a portion of an arc of the sector;

a triangle, wherein the shield defines at least a portion of two of the sides of the triangle;

a rectangle, wherein the shield defines at least a portion of three of the sides of the rectangle.

7. The method of claim 6, wherein the arc of the sector subtends an angle of one of forty-five degrees, ninety degrees, one hundred thirty-five degrees, one hundred eighty degrees, two hundred twenty-five degrees or two hundred seventy degrees.

8. The method of claim 5, wherein the dielectric buffer is formed from at least one of:

an acrylic;

a paper;

a polyamide;

a polycarbonate;

a polychloroprene;

a polyester;

a polyethylene;

a polypropylene;

a polystyrene;

a polytetrafluoroethylene;

a polyvinyl chloride;

a porcelain;

a resin;

a rubber;

a silicone;

a styrene;

or

a wax.

9. The method of claim 4, further comprising:

wherein storing the first information comprises at least one of;

adding an identifier of the first item to a record of inventory stored in the at least one data store;

or

increasing a quantity of the first item in the record of inventory stored in the at least one data store.

10. The method of claim 4, wherein the RFID antenna and at least the first section of the support bar are separated by a first predefined vertical distance, and

wherein the method further comprises:

selecting a strength of the electromagnetic field based at least in part on the first predefined vertical distance.

11. The method of claim 4, further comprising:

determining that the first RFID signal is no longer received by the RFID antenna;

determining that the one of the first item bearing the first RFID tag is no longer disposed on the support bar based at least in part on the first RFID signal; and

storing second information in at the at least one data store, wherein the second information dissociates the one of the first item bearing the first RFID tag from the support bar.

12. The method of claim 11, wherein storing the second information comprises at least one of:

decreasing a quantity of the first item in a record of inventory stored in the at least one data store;

removing an identifier of the first item from the record of inventory stored in the at least one data store.

13. The method of claim 4, further comprising:

determining a first location of the support bar on a panel using at least one computer processor; and

storing a second indication that the first item bearing the first RFID tag is disposed on the support bar at the first location.

14. The method of claim 13, wherein the panel comprises a plurality of antenna connections, and

wherein determining the first location of the support bar on the panel further comprises:

receiving, at a detection circuit, a voltage signal corresponding to a voltage level at one of the plurality of antenna connections;

identifying the one of the plurality of antenna connections to which the voltage signal corresponds using the at least one computer processor;

determining that the one of the plurality of antenna connections is associated with the location using the at least one computer processor; and

determining that the one of the first item is disposed on the support bar at the location based at least in part on the voltage signal using the at least one computer processor.

15. The method of claim 4, wherein the first item further comprises a first extension having a first opening, and

wherein the first RFID tag is affixed to the first extension between the first opening and an upper edge of the first extension.

16. The method of claim 15, further comprising:

extending a free distal end of the support bar through the first opening of the first extension, and

causing the first item to be suspended from the support bar,

wherein the first RFID tag is positioned between the RFID antenna and the support bar when the first item is suspended from the support bar.

17. A storage unit comprising:

a base; and

a leaky transmission line comprising;

an RFID antenna comprising a conductive rod having a proximal end mounted to a front face of the base;

a shield having a proximal end mounted to the front face of the base, wherein the shield is provided at a first predetermined distance from at least a first portion of a circumference of the RFID antenna; and

a dielectric buffer provided between the RFID antenna and an inner surface of the shield; and

a support bar having a proximal end mounted to the front face of the base beneath a second portion of the circumference of the RFID antenna,

wherein the leaky transmission line is configured to radially emit an electromagnetic field from the RFID antenna in at least a direction corresponding to the second portion of the circumference of the RFID antenna.

18. The storage unit of claim 17, further comprising:

a coaxial connector extending from a rear face of the base,

wherein the coaxial connector comprises a compressible spring-biased cylinder and a pin within the cylinder,

wherein the coaxial connector is coupled the RFID antenna, and

wherein the coaxial connector is configured to receive radiofrequency energy from an external source and to transfer the radiofrequency energy to the RFID antenna.

19. The storage unit of claim 17, wherein the support bar comprises a first section including the proximal end mounted to the front face of the base and a second section including a free distal end of the support bar,

wherein the first section of the support bar extends from the front face of the base in parallel to the RFID antenna, and

wherein the second section of the support bar is canted upward at an acute angle with respect to the first section.

20. The storage unit of claim 17, wherein the shield defines a shape corresponding to at least a portion of at least one of:

a circle;

a rectangle;

a triangle;

a hexagon;

a pentagon;

or

an octagon, and

wherein the dielectric buffer is formed from at least one of an acrylic or an acrylonitrile butadiene styrene.