Abstract:
An inventory management system which determines item location and time spent on a shelf. The system includes an electronic shelf label (ESL) system including an ESL, a radio frequency identification (RFID) label interrogator associated with the ESL, RFID labels attached to items associated with the ESL, and a computer. The computer uses the ESL system to activate RFID labels on the items, obtains RFID label information from the RFID labels through the ESL system, and stores the RFID label information in a record. The computer completes repeats the process and compares the latest RFID label information with previous RFID label information to determine which items have been added or removed from the shelf.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to radio frequency identification devices and electronic price label systems, and more specifically to a system and method of managing inventory. 
     ESL systems typically include a plurality of ESLs for merchandise items in a transaction establishment. ESLs typically display the price of corresponding merchandise items on store shelves and are typically attached to a rail or shelf channel along the leading edge of the shelves. A transaction establishment may contain thousands of ESLs to display the prices of the merchandise items. The ESLs are coupled to a central server from where information about the ESLs is typically maintained in an ESL data file. Price information displayed by the ESLs is obtained from a price look-up (PLU) data file. 
     RFID technology provides an alternative to bar code reader technology for distinguishing and recording items for purchase. Some of the uses of RFID technology are disclosed in U.S. Pat. No. 6,019,394 assigned to the assignee of the present invention. This patent is hereby incorporated by reference. 
     Store associates must perform routine tasks throughout the store and require information to support operation of the store. Back room inventory management is on routine task which can be labor intensive. Store associates must routinely track movement of stock in and out of the back room, including time and location on back room shelves. 
     Therefore, it would be desirable to combine the communication capabilities of electronic price label systems with RFID technology in order to perform back room inventory management. 
     SUMMARY OF THE INVENTION 
     In accordance with the teachings of the present invention, a system and method of managing inventory is provided. 
     The system includes an electronic shelf label (ESL) system including an ESL, a radio frequency identification (RFID) label interrogator associated with the ESL, first and second groups of RFID labels attached to first and second groups of items associated with the ESL, and a computer. 
     The computer obtains identification information and location information for the ESL, sends a first message to the ESL to activate the first group of RFID labels, obtains first RFID label information from the first RFID labels through the ESL system, stores the first RFID label information in a record, sends a second message to the ESL to activate second group of RFID labels, obtains second RFID label information from the second RFID labels through the ESL system, compares the first and second RFID label information, removes third RFID label information within the first RFID label information from the record if the second RFID label information does not contain the third RFID label information, and adds fourth RFID label information representing a difference between the first and second RFID label information to the record. 
     The computer may additionally store first times in the record with the first RFID label identification, determine second times with the second RFID label information, and subtract the first times from the second times to determine third times spent by the first items on a shelf. 
     The computer may additionally determine an average time spent on the shelf by the first items from the third times. 
     It is accordingly an object of the present invention to provide a system and method of managing inventory. 
     It is another object of the present invention to provide a system and method of managing back room inventory which combines communication capabilities of electronic price label systems with RFID technology. 
     It is another object of the present invention to reduce the amount of time spent in manually tracking time and location information for items. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Additional benefits and advantages of the present invention will become apparent to those skilled in the art to which this invention relates from the subsequent description of the preferred embodiments and the appended claims, taken in conjunction with the accompanying drawings, in which: 
     FIG. 1 is a block diagram of a transaction processing system; 
     FIG. 2 illustrates the contents of example data files; and 
     FIG. 3 is a flow diagram illustrating the method of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, back room system  10  primarily includes server  12 , electronic shelf label (ESL) system  14 , and radio frequency identification (RFID) system  16 . 
     Server  12  executes inventory management software  18  which tracks locations of inventory items on back room shelves inventory management software  18  additionally tracks time spent on back room shelves by such inventory items. Inventory management software  18  may also generate an order stock to replace items which have been removed from back room shelves. 
     Inventory management software  18  stores inventory information within inventory data file  20 . Inventory management software  18  obtains the inventory information from RFID system  16 . 
     Inventory management software  18  provides reports which may be displayed by display  22  or printed by printer  24 . A store employee may manage reporting and data entry through input device  26 , which may include a keyboard. 
     ESL system  14  includes ESL computer  30  and ESLs  32 . Communication between ESL computer  30  and ESLs  32  may be wireless or wired communication. 
     ESL computer  30  executes ESL software  34 . ESL software  34  is responsible for scheduling and transmitting messages to ESLs  32 . ESL software  34  maintains ESL data file  44  which includes ESL identification information, item identification information, and price verification information. ESL software  34  stores ESL data file  44  within storage medium  46 . 
     ESL software  34  periodically sends messages to ESLs  32  requesting information about items associated with ESLs  32 . ESLs  32  obtain the information using RFID system  16 . ESL software  34  forwards received information to inventory management software  18 . 
     ESLs  32  are mounted to back room shelves. ESts include control circuitry  40  and memory  42 . Control circuitry  40  controls operation of ESL  32 . Control circuitry  40  receives incoming messages from ESL computer  30  and acknowledges messages from ESL computer  30 . Control circuitry  40  also receives information from RFID system  16  and stores the shelf inventory information in memory  42  until it can be sent to ESL computer  30 . 
     RFID system  16  includes RFID interrogators  50  and RFID labels  52 . 
     RFID interrogators  50  are coupled to ESLs  32 . RFID interrogators  50  are mounted on shelves with ESLs  32 . Alternatively, RFID interrogators  50  may be built into ESLs  32 . RFID interrogators  50  receive RFID label information from bearing RFID labels  52  on nearby items associated with ESLs  32 . 
     RFID labels  52  store information about items and communicate the information to RFID interrogators  50 . One embodiment of RFID label  52  is active and includes RFID communicator  56 , memory  58 , and power source  60 . RFID communicator  56  sends item information stored in RFID memory  58  to RFID interrogators  50 . RFID communicator  56  may include an RF transceiver. 
     Memory  58  stores the information and may include a read-only memory (ROM) for one-time use, or a programmable ROM (EPROM) for repeated use. 
     Power source  60  may include a battery. 
     RFID label  52  may also be a passive label. Passive RFID labels use very little energy and may only include RFID communicator  56 . Power may be derived from radio waves. 
     RFID communicator  56  may include a reflective antenna which has a frequency which is unique among RFID labels  52 . RFID communicator  56  communicates RFID label identification information which must be cross-referenced to obtain item identification information. RFID communicator  56  may include a number of antennas, such as conductive ink antennas. 
     RFID labels  52  may vary in size, depending upon product size, and may be visible or hidden when attached to products. RFID label  52  may be removably or permanently attached to products. 
     Turning now to FIG. 2, inventory data file  20  and ESL data file  44  are shown in more detail. 
     Inventory data file  20  includes records for each ESL  32 . The entries include ESL ID, ESL LOC, AVE TIME, RFID, INIT TIME, and END TIME. 
     Entry ESL ID identifies ESL identification information. 
     Entry ESL LOC identifies ESL location information. 
     Entry AVE TIME identifies average time of an item on a back room shelf. 
     Entry RFID identifies RFID label identification information. 
     Entry START TIME identifies start time of an item on a back room shelf. 
     Entry END TIME identifies end time of an item on a back room shelf. 
     Inventory data file  20  may additionally include entry ITEM ID, which identifies an item associated with ESL  32 . Item identification information may come from RFID label  52  or from ESL data file  44  or by manually entered using input device  26 . 
     ESL data file  44  includes records for each ESL  32 . The entries include ESL ID, ITEM ID, and ESL PRICE. 
     Entry ESL ID identifies ESL identification information. 
     Entry ITEM ID identifies an item associated with ESL  32 . 
     Entry ESL PRICE identifies a price verifier. 
     Turning now to FIG. 3, the inventory management method is illustrated in more detail beginning with START  70 . 
     In step  72 , inventory management software  18  obtains current ESL identification information and ESL location information from ESL data file  44  and updates inventory data file  20  with additions and deletions. 
     In steps  74 - 90 , inventory management software  18  compares each piece of RFID label information listed in an ESL record in inventory data file  20  to received RFID label information. 
     In step  74 , inventory management software  18  reads an ESL record from inventory data file  20 . 
     In step  76 , inventory management software  18  causes ESL system  14  to obtain RFID label information for a product associated with an ESL  32  on a back room shelf. ESL system  14  sends messages to ESL  32  with instructions to activate RFID interrogator  50 , obtain RFID label information, and return the RFID label information. RFID interrogator  50  obtains the RFID label information from memories  58  of RFID labels  52  on the products and forwards the identification information to ESL  32  for transmission back to ESL computer  30 . 
     The RFID label information preferably includes RFID label identification information, but may also include item identification information. Item identification information for products having passive RFID labels  52  may be entered manually in inventory data file  20  and cross-referenced to RFID label identification information by inventory management software  18 . 
     ESL software  34  forwards the RFID label information to inventory management software  18 . 
     In step  80 , inventory management software  18  reads an RFID entry in the record. 
     In step  82 , inventory management software  18  determines whether it received a piece of RFID label information for the RFID label  52  in the record. If not, operation proceeds to step  84 . Otherwise, operation proceeds to step  86 . 
     In step  84 , inventory management software  18  assumes RFID label  52  is no longer on the shelf and determines the time the item associated with RFID label  52  was first logged into inventory data file  52 . 
     In step  86 , inventory management software  18  determines whether the record is the last record. If not, operation returns to step  80 . Otherwise, operation proceeds to step  88 . 
     In step  88 , inventory management software  18  determines a new average time on the shelf for the item associated with ESL  32  and stores it within inventory data file  20 . 
     In step  90 , inventory management software  18  removes the records for RFID labels  52  no longer on the shelf from inventory data file  20 . 
     In steps  92 - 98 , inventory management software  18  identifies new pieces of RFID label information. 
     In step  92 , inventory management software  18  examines a piece of received RFID label information. 
     In step  94 , inventory management software  18  determines whether the piece of received of RFID label information is already stored within inventory data file  20 . If so, operation proceeds to step  98 . Otherwise, operation proceeds to step  96 . 
     In step  96 , inventory management software  18  stores the piece of RFID label information and a current date and time in inventory data file  20 . 
     In step  98 , inventory management software  18  determines whether the piece of RFID label information is the last piece. If not, operation returns to step  92 . Otherwise, operation proceeds to step  100 . 
     In step  100 , inventory management software  18  determines whether the ESL record is the last ESL record. If not, operation returns to step  74 . Otherwise, operation proceeds to step  102 . 
     In step  102 , operation ends. 
     Using the information in inventory data file  20 , store management can easily track locations of items bearing RFID labels  52 . They can also track time spent on shelves by such items. 
     Although the present invention has been described with particular reference to certain preferred embodiments thereof, variations and modifications of the present invention can be effected within the spirit and scope of the following claims.