CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]    The present invention is related to commonly assigned and co-pending U.S. application entitled, “Method Of Locating Electronic Price Labels In Transaction Establishments”, filed Oct. 5, 1995, invented by Goodwin, and having a Ser. No. 08/539,450. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The present invention relates to electronic price label (EPL) systems used in transaction establishments, and more specifically to a device and method for locating EPLs in a transaction establishment.  
           [0003]    EPL systems typically include a plurality of EPLs for each merchandise item in a store. EPLs typically display the price of corresponding merchandise items on store shelves and are typically attached to a rail along the leading edge of the shelves. A store may contain thousands of EPLs to display the prices of the merchandise items. The EPLs are coupled to a central server from where information about the EPLs is typically maintained in an EPL data file. Price information displayed by the EPLs is obtained from the PLU file.  
           [0004]    EPLs today may be wired or wireless. Wireless EPLs may employ infrared or radio frequency transmitters to transmit acknowledgment signals acknowledging receipt of messages and to relay acknowledgment signals from other EPLs to receiving devices coupled to a main EPL computer. An EPL only sends an acknowledgment if the message is addressed to it.  
           [0005]    Over time, EPLs may be displaced from their mounting brackets. A customer or store employee may intentionally or unintentionally remove an EPL. In any case, the store must locate and reinstall the displaced EPLs, or determine that they are not in the store and replace them.  
           [0006]    Therefore, it would be desirable to provide a device and method for locating EPLs in a transaction establishment.  
         SUMMARY OF THE INVENTION  
         [0007]    In accordance with the teachings of the present invention, a device and method for locating EPLs in a transaction establishment is provided.  
           [0008]    The locator includes an input device which records identification information distinguishing the electronic price label from other electronic price labels. A receiver receives signals from the electronic price label. Signal strength and noise level determining circuitry measures signal strengths and noise levels associated with the signals. Processing circuitry determines a direction to the electronic price label. Finally, a display displays the direction. The locator may also be portable and include a hand-held housing.  
           [0009]    It is accordingly an object of the present invention to provide a device and method for locating EPLs in a transaction establishment.  
           [0010]    It is another object of the present invention to provide a device and method for locating EPLs in a transaction establishment which determine directions to an EPL from signal strengths and noise levels associated with signals from the EPL.  
           [0011]    It is another object of the present invention to provide a device for locating EPLs in a transaction establishment which is portable and hand-held. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    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:  
         [0013]    [0013]FIG. 1 is a block diagram of an EPL system;  
         [0014]    [0014]FIG. 2 is a block diagram of an EPL;  
         [0015]    [0015]FIG. 3 is a block diagram of an EPL locator;  
         [0016]    [0016]FIG. 4 is a view of a first embodiment of the EPL locator;  
         [0017]    [0017]FIG. 5 is a view of a second embodiment of the EPL locator;  
         [0018]    [0018]FIG. 6 is a flow diagram illustrating the operation of EPL control software in conjunction with the EPL locator;  
         [0019]    [0019]FIG. 7 is a flow diagram illustrating the method of locating the wireless EPLs by EPL locator software;  
         [0020]    [0020]FIG. 8 is a first example of a map of a transaction establishment;  
         [0021]    [0021]FIG. 9 is a second example of a map of a transaction establishment; and  
         [0022]    [0022]FIG. 10 is a sample report generated by the EPL locator software. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0023]    Referring now to FIG. 1, EPL system  10  includes computer  12 , storage medium  14 , communication base station (CBS)  16 , electronic price labels (EPLS)  18 , and portable EPL locator  24 .  
         [0024]    Computer  12  executes EPL control software  20  and EPL locator software  22 . EPL control software  20  records, schedules, and transmits all messages to EPLs through CBS  16 , and receives and analyzes status messages from EPLs  18  through CBS  16 . EPL control software  20  also maintains and uses EPL data file  28 , which contains item information, EPL identification information, item price verifier information, and status information for each of EPLs  18 .  
         [0025]    EPL control software  20  primarily includes data scheduler  34  and CBS manager  36 . Data scheduler  34  schedules EPL price change messages to be sent to EPLs  18  through CBS  16 .  
         [0026]    EPL locator software  22  automatically monitors EPL system  10  for received signal strength and determines the location of identified EPLs, which it stores in EPL system configuration file  27 . EPL system configuration file  27  tells computer  12  how system  10  is configured, i.e., the addresses of EPL system components and their location within a transaction establishment relative to other components within system  10 , and the location of different types of goods in system  10 . EPL locator software  22  displays or prints location results on display  25  and printer  23 .  
         [0027]    Storage medium  14  is preferably a fixed disk drive. Storage medium  14  stores EPL system configuration file  27  and EPL data file  28 .  
         [0028]    CBS  16  preferably includes one transmit antenna  37  and up to four receive antennas  38  for transmitting and receiving messages between CBS  16  and EPLs  18 . CBS  16  includes CBS circuitry  39  which controls operation of CBS  16 . EPL system  10  preferably includes a plurality of CBSs  16  connected together in series.  
         [0029]    CBS manager  36  schedules transmission of price change messages to EPLs  18  and the reception of status messages from EPLs  18  for predetermined time slots.  
         [0030]    Turning now to FIG. 2, EPLs  18  are illustrated.  
         [0031]    EPLs  18  each include battery  40 , transmit and receive antenna  42 , display  46 , memory  47 , and EPL circuitry  48 .  
         [0032]    Battery  40  provides power to EPLs  18 .  
         [0033]    Transmit and receive antenna  42  receives price change and status messages from CBS  16 .  
         [0034]    Transmit and receive antenna  42  transmits responses to price change and status messages to CBS  16 .  
         [0035]    Display  46  displays price and possibly additional information. Display  46  is preferably a liquid crystal display (LCD).  
         [0036]    Memory  47  stores price verifier information, EPL type information, and may additionally store promotional information. Preferably, the price verifier information is a checksum of the displayed price.  
         [0037]    EPL circuitry  48  controls the internal operation of EPLs  18 .  
         [0038]    Turning now to FIG. 3, portable EPL locator  24  includes sensors  50 , receiver  52 , keypad  54 , communications port  56 , signal strength and noise measuring circuitry  58 , processing circuitry  60 , and display  62 .  
         [0039]    Sensors  50  may include antennas for RF systems and photodetectors for IR systems.  
         [0040]    Receiver  52  receives signals from EPLs  18  through sensors  50 .  
         [0041]    Keypad  54  records entry of EPL identification numbers by an operator.  
         [0042]    Alternatively, EPL identification information and optional approximate EPL fix information determined by EPL locator software  22  may be obtained by coupling communications port  56  to computer  12 .  
         [0043]    Signal strength and noise measuring circuitry  58  determines the signal-to-noise ratios for signals received through each of sensors  50 .  
         [0044]    Processing circuitry  60  determines a direction to EPL  18  from the signal-to-noise ratios.  
         [0045]    Display  62  displays direction information, EPL identification information, and approximate fix information.  
         [0046]    Turning now to FIG. 4, a first embodiment of EPL locator  24  is illustrated in more detail.  
         [0047]    EPL locator  24  is preferably portable. Here, EPL locator  24  is generally rectangular in shape and includes antennae  70  for receiving RF acknowledgment signals sent by EPLs  18  to CBS  16 . To obtain optimal fix information, antennae  70  are preferably located on three different sides of EPL locator  24 . Since antennae  70  are small, they can be located inside of EPL locator  24 . EPL locator  24  may also include a carrying strap  72 .  
         [0048]    Display  62  displays information about a particular EPL, which may include a serial or other identification number entered into EPL locator  24  by a user, an approximate location of the EPL entered into EPL locator  24  by the user, the signal strength and noise  78  of the signal from the EPL, and a direction arrow  76  pointing to the EPL. The approximate location of the EPL is preferably determined by the EPL locator software  22  in accordance with the method of FIG. 7.  
         [0049]    Turning now to FIG. 5, a second embodiment of EPL locator  24  is illustrated in more detail.  
         [0050]    This embodiment is also preferably portable. Here, EPL locator  24  includes a gun-like handle  74 , but is otherwise similar to the first embodiment.  
         [0051]    Turning now to FIG. 6, the operation of portable EPL locator  24  in conjunction with EPL control software  20  is explained in more detail, beginning with START  80 .  
         [0052]    In steps  82 - 90 , EPL control software  20  determines whether a particular EPL  18  is out of the store or not functioning.  
         [0053]    In step  82 , EPL control software  20  transmits an existence message addressed to EPL  18 .  
         [0054]    In step  84 , EPL control software  20  waits for an acknowledgment message from EPL  18 .  
         [0055]    If an acknowledgment message is not received, EPL control software  20  determines whether the maximum number of existence message transmission retries has been attempted in step  88 .  
         [0056]    If the maximum number of existence message retries has not been reached, EPL control software  20  increments a retry counter in step  86  and returns to step  82 .  
         [0057]    If the maximum number of existence message retries has been reached, EPL control software  20  stops transmitting existence messages and provides an indication to an operator to replace EPL  18  in step  90 , since EPL  18  is either not operating or outside the range (i.e., outside of the transaction establishment) of CBS  16 . The method ends in step  108 .  
         [0058]    Returning to step  84 , if an acknowledgment is received from EPL  18 , the method proceeds to step  92 . In step  92 , EPL locator software  22  obtains an approximate location of EPL  18  in accordance with the steps illustrated in FIG. 7.  
         [0059]    Steps  96 - 106  reflect the operation of EPL locator  24  in conjunction with EPL control software  20 . The present invention envisions that such steps may be performed independently of steps  80 - 92  and where a rough estimate of the location of EPL  18  is not desired from EPL locator software  22  by an operator.  
         [0060]    In step  96 , EPL software  20  transmits existence messages addressed to EPL  18  for a predetermined number of retries.  
         [0061]    In step  98 , EPL locator  24  displays signal-to-noise data for the acknowledgment signals transmitted by EPL  18 .  
         [0062]    In step  100 , EPL locator  24  calculates a direction to EPL  18  using basic radar tracking methods to determine the location of EPL  18 .  
         [0063]    In step  102 , EPL locator  24  displays a direction to EPL  18 .  
         [0064]    In step  104 , if an operator has found the displaced EPL  18 , the method ends in step  108 . The operator may then reinstall and reactivate the displaced EPL  18 .  
         [0065]    If the operator has not yet found EPL  18 , the method continues to step  106 , in which the operator may choose to discontinue the search. If the operator chooses to discontinue the search, the method ends in step  108 . If the operator chooses to continue the search, the method returns to step  96  to allow the operator to home in on the displaced EPL  18 .  
         [0066]    Turning now to FIG. 7, the operation of EPL locator software  22  represented by step  92  of FIG. 6 is explained in more detail, beginning with START  110 .  
         [0067]    In step  112 , the locations of antennas  38  are determined. As an optional step, the locations of CBSs  16  may be plotted on the map of FIG. 8, but are included in configuration file  27  at installation time.  
         [0068]    In step  114 , the locations of EPLs  18  are determined. As an optional step, the locations of EPLs  18  may be plotted on the map of FIG. 8. This information is available in EPL configuration file  27 , but is not reliable in a running system since changes occur often.  
         [0069]    In step  115 , EPL control software causes CBSs  16  to transmit a query message to a particular EPL, such as EPL  18 .  
         [0070]    In step  116 , EPL locator software  22  listens for an acknowledgment message from the EPL.  
         [0071]    In step  118 , EPL locator software  22  determines the signal strengths of any acknowledgment message from the EPL  18  to one of antennas  38  within CBSs  16 . If multiple antennas  38  receive the acknowledgment message, EPL locator software  22  uses basic radar tracking methods to determine the location of the EPL.  
         [0072]    In step  119 , EPL locator software  22  determines whether signal strength information for the last of antennas  38  has been determined. If all CBSs  16  have been polled for signal strength information about their antennas  38 , the method continues to step  120 . If a CBS has not been polled, the method returns to step  118 .  
         [0073]    In step  120 , EPL locator software  22  determines the primary and secondary estimates of fixes to the antennas  38  on the map in FIG. 8.  
         [0074]    In step  122 , EPL locator software  22  optionally converts the fixes to types of goods using information in EPL configuration file  27 .  
         [0075]    In step  124 , EPL locator software  22  displays or prints primary and secondary estimates of the location coordinates and/or types of goods where the desired EPL is most likely located. A sample report is shown in FIG. 10.  
         [0076]    If store personnel determine that the location of the EPL does not correspond to its location in EPL configuration file  27  (e.g., because a child has removed it and placed it somewhere else), they can place the EPL in its proper location.  
         [0077]    In step  126 , the method ends.  
         [0078]    Turning now to FIG. 8, a map of a transaction establishment illustrates the location of shelves  50  and EPLs  18 .  
         [0079]    The locations of EPLs  18  are referenced to a two-dimensional coordinate system in which rows are identified by numerals and columns are identified by letters.  
         [0080]    In this example, EPL  19  is sought after and is located at position  3 D. Receive antennas  38  are located at  3 A,  7 A,  3 D,  7 D,  3 E,  7 E,  3 G,  7 G,  3 H,  7 H,  3 J,  7 J,  3 K,  7 K,  3 M, and  7 M. Transmit antennas  37  are located at  5 C,  5 F,  5 I, and  5 L.  
         [0081]    If from the information in EPL configuration file  27  it is known that position  3 D is ‘in back of the pop aisle’, then it is also known that EPL  19  is ‘in back of the pop aisle’.  
         [0082]    In this example, only one receive antenna  38  at position  3 D hears the acknowledgment of EPL  19 . The primary fix for EPL  19  is position  3 D. A less accurate fix for EPL  19  is any one of positions  2 C,  2 D,  2 E,  3 C,  3 E,  4 C,  4 D, or  4 E that surround the primary fix.  
         [0083]    Turning now to FIG. 9, three receive antennae  38  at positions  3 D,  3 A, and  7 D hear the acknowledgment of EPL  19 . Antenna  3 D reports a relative signal strength of “ 60 ”, and antennae  3 A and  7 D report relative signal strengths of “ 30 ”. The primary fix for EPL  19  is position  4 C. A secondary fix for EPL  18  is any one of positions  3 B,  3 C,  3 D,  4 B,  4 D,  5 B,  5 C, or  5 D that surround the primary fix. Here, EPL  19  is actually located in one of the secondary fixes,  4 D.  
         [0084]    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.
An electronic price label locator which uses signal strength and noise level information associated with signals from the electronic price label. The locator includes an input device which records identification information distinguishing the electronic price label from other electronic price labels. A receiver receives signals from the electronic price label. Signal strength and noise level determining circuitry measures signal strengths and noise levels associated with the signals. Processing circuitry determines a direction to the electronic price label. Finally, a display displays the direction. The locator may also be portable and include a hand-held housing.