Inventory tracking using RFID

Patent metadata

Field	Value
Publication number	US-10037449-B1
Application number	US-201514869876-A
Country	US
Kind code	B1
Filing date	Sep 29, 2015
Priority date	Sep 29, 2015
Publication date	Jul 31, 2018
Grant date	Jul 31, 2018

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.

First claim

What is claimed is:

1. An inventory area of a materials handling facility comprising:
a panel having a plurality of horizontally extending knuckles provided on a front side of the panel;
a storage unit releasably mounted to the panel, wherein the storage unit comprises:
a base;
a horizontally aligned bolt mounted to an upper portion of the base,

wherein the bolt is rotatably inserted into one of the horizontally aligned knuckles of the panel;
a support bar having a proximal end mounted to a front face of the base and a free distal end;
an RFID antenna having a proximal end mounted to the front face of the base above the support bar, wherein the RFID antenna is configured to emit an electromagnetic field having a standing wave in a phase determined based at least in part on an impedance of the RFID antenna, and wherein the RFID antenna is coupled to an RFID reader, and
a phase shifter coupled to a distal end of the RFID antenna, wherein

the phase shifter comprises at least one resistor for establishing the impedance of the RFID antenna;
an item suspended from the support bar, wherein the item comprises:
an extension having an upper portion and a lower portion;
an RFID tag provided in the upper portion of the extension, wherein the RFID tag is programmed to transmit an RFID signal when the RFID tag senses the electromagnetic field emitted by the RFID antenna; and
a hole provided in a lower portion of the extension, wherein the support bar is extended through the hole,

wherein the upper portion of the extension is positioned between the RFID antenna and the support bar.

2. The storage area of claim 1 , further comprising at least one computer device configured to at least:
cause the RFID antenna to emit the electromagnetic field with a standing wave in a first phase based at least in part on a first impedance of the RFID antenna;
establish a second impedance of the RFID antenna using the phase shifter, wherein establishing the second impedance comprises increasing or decreasing a resistance of the RFID antenna;
cause the RFID antenna to emit the electromagnetic field with the standing wave in a second phase based at least in part on the second impedance of the RFID antenna;
receive, by the RFID antenna, the RFID signal emitted by the RFID tag in response to at least one of the electromagnetic field with the standing wave in the first phase or the electromagnetic field with the standing wave in second phase;
interpret contents of the RFID signal; and
identify the item based at least in part on the interpreted contents of the RFID signal.

3. The storage area of claim 2 , wherein the at least one computer device is further configured to at least:
determine a strength of the RFID signal emitted by the RFID tag in response to at least one of the electromagnetic field with the standing wave in the first phase or the electromagnetic field with the standing wave in the second phase;
determine that the strength of the RFID signal exceeds a predetermined threshold;
determine that the item is suspended from the support bar based at least in part on the strength of the RFID signal; and
store first information associating the item with the support bar in at least one data store.

4. The storage area of claim 2 , wherein the electromagnetic field is caused to be emitted with the standing wave in the first phase for a first predetermined period of time,
wherein the resistance of the RFID antenna is increased or decreased in accordance with a predetermined schedule, and
wherein the electromagnetic field is caused to be emitted with the standing wave in the second phase for a second predetermined period of time.

5. A method comprising:
emitting an electromagnetic field with a first standing wave in a first phase from an RFID antenna using at least one computer processor, wherein a first section of the RFID antenna is separated from a first section of a support bar by at least a first predefined distance;
emitting the electromagnetic field with a second standing wave in a second phase from the RFID antenna using the at least one computer processor;
receiving, by the RFID antenna, at least a first RFID signal from a first RFID tag, wherein the first RFID signal is received in response to at least one of the electromagnetic field with the first standing wave in the first phase or the electromagnetic field with the second standing wave in the second phase;
interpreting contents of at least the first RFID signal using the 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.

6. The method of claim 5 , wherein the electromagnetic field is emitted with the first standing wave in the first phase with an impedance of the RFID antenna at a first level,
wherein the electromagnetic field is emitted with the second standing wave in the second phase with an impedance of the RFID antenna at a second level, and
wherein the method further comprises:
shifting the impedance of the RFID antenna from the first level to a second level by a phase shifter using the at least one computer processor.

7. The method of claim 6 , wherein shifting the impedance of the RFID antenna from the first level to the second level by the phase shifter further comprises:
increasing or decreasing at least one of a resistance, a capacitance or an inductance of the RFID antenna by the phase shifter.

8. The method of claim 6 , wherein the electromagnetic field is emitted with the first standing wave in the first phase for a first period of time, and
wherein the electromagnetic field is emitted with the second standing wave in the second phase for a second period of time.

9. The method of claim 6 , wherein the impedance of the RFID antenna is shifted from the first level to the second level at a predetermined time interval or in accordance with a predetermined schedule.

10. The method of claim 6 , wherein the first phase differs from the second phase by a predetermined angular extent.

11. The method of claim 5 , wherein determining that the one of the first item bearing the RFID tag is disposed on the support bar further comprises:
determining a first strength of the first RFID signal using the at least one computer processor;
determining that the first strength of the first RFID signal exceeds a predetermined threshold; and
determining that the first item is disposed on the support bar based at least in part on the first strength of the first RFID signal.

12. The method of claim 5 , 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.

13. The method of claim 5 , wherein the first item further comprises a first extension having a first opening in a lower portion of the first extension and the first RFID tag in an upper portion of the first extensi

Assignees

• Amazon Tech Inc

Inventors

• Hahn Camerin
• Niranjayan Somasundaram
• Huebner Ronald Eugene

Classifications

• G06K7/0008 Primary

  General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer · CPC title

• G06Q10/087

  Inventory or stock management, e.g. order filling, procurement or balancing against orders · CPC title

• G06K7/10415 Primary

  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 title

• G06K19/07749

  the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card · CPC title

• G06K7/10009

  sensing by radiation using wavelengths larger than 0.1 mm, e.g. radio-waves or microwaves · CPC title