Patent ID: 7940181

Claim:
A method, implemented at least in part by a computing device, for determining product availability of products on a product display unit using radio-frequency identification (RFID), the method comprising: determining whether a RFID tag is detectable by a RFID reader; and based on the determination, setting a product availability condition indicating product availability of a product on the product display unit; wherein the RFID tag is associated with the product display unit, wherein the RFID tag is not attached to the product, and wherein distance between the RFID tag and an antenna of the RFID reader changes as quantity of the product on the product display unit changes; wherein the RFID tag is movably attached to the product display unit, wherein the RFID tag moves closer to the antenna of the RFID reader as quantity of the product is added to the product display unit, and where the RFID tag moves farther from the antenna of the RFID reader as quantity of the product is removed from the product display unit; and wherein as quantity of the product is added to the product display unit, the product pushes the RFID tag closer to the antenna of the RFID reader, and wherein as quantity of the product is removed from the product display unit, the RFID tag is pushed farther from the antenna of the RFID reader.