Method of locating electronic price labels in transaction establishments

Abstract: A method of locating a misplaced electronic price label (19) in a transaction establishment which relies on known location information from other electronic price labels. The method includes the steps of receiving (64) a message from the misplaced electronic price label, determining (70) a first approximate location of the electronic price label from characteristics of the return message, selecting (72) other electronic price labels in proximity with the approximate location, receiving (74) messages from a number of the other electronic price labels whose locations are known, determining (76) which of the number of the other electronic price labels is closest to the electronic price label from characteristics of the messages from the number of the other electronic price labels, and determining (78) a second approximate location of the electronic price label based on the location of the closest electronic price label.

Description: The present invention relates to electronic price label (EPL) systems used in transaction establishments, and more specifically to a method of locating an electronic price label in a transaction establishment. EPL systems typically include a plurality of individually addressable EPLs, one 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. EPLs today may be wired, as for example described in WO-A-9 305 475, 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. It is desirable to determine the location of wireless EPLs that have been removed from their assigned shelf locations. Eventually, EPLs become displaced from their mounting brackets. An individual may accidentally knock the EPL out of its mounting bracket and place it on a different shelf. An individual may intentionally remove the EPL and place it in another location within the store, or remove it from the store. It is an object of the present invention to provide a method of locating an electronic price label in transaction establishments. According to the invention there is provided a method of locating an electronic price label in a transaction establishment characterized by the steps of: (a) receiving a message from said electronic price label; (b) determining from characteristics of the received message a first approximate location of said electronic price label; (c) selecting other electronic price labels in proximity with the first approximate location; (d) receiving messages from a number of the other electronic price labels whose locations are known; (e) determining from characteristics of the received messages which of the other electronic price labels is closest to said electronic price label; and (f) determining a second approximate location of said electronic price label based on the location of the closest other electronic price label. The invention will now be described by way of example only with reference to the accompanying drawings, in which: Fig. 1 is a block diagram of an EPL system; Fig. 2 is a block diagram of an EPL; Figs. 3 and 4 show a map of a transaction establishment, with an EPL to be located in different positions; Fig. 5 is a flow diagram illustrating the method of locating a missing EPL; Fig. 6 is a flow diagram illustrating a method of obtaining an approximate location of a missing EPL; and Fig. 7 is a sample report generated by EPL locator software. In Fig. 1, EPL system 10 includes computer 12, storage medium 14, communication base stations (CBSs) 15a-d, electronic price labels (EPLs) 18a-d, display 22, and printer 23. Computer 12 executes EPL control software 20 and EPL locator software 30. EPL control software 20 records, schedules, and transmits all messages to EPLs 18a-d through CBSs 15a-d, and receives and analyzes status messages from EPLs 18a-d through CBSs 15a-d. Such messages include queries to individual EPLs requesting an acknowledgment signal from the individual EPLs so that EPL locator software 30 can determine where the individual EPLs are located. EPL control software 20 also maintains and uses EPL data file 28, which contains item information, identification information, item price verifier information, and status information for each of EPLs 18a-d. 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 18a-d through CBSs 15a-d. 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 the transaction establishment relative to other components within system 10, and the location of different types of goods in the system. EPL locator software 30 automatically monitors EPL system 10 for received signal strength and determines the location of missing EPLs. EPL locator software 30 displays on display 22, prints using printer 23, and/or stores in missing EPL action file 29 the search results. The search results may indicate that no acknowledgment messages have been received from the missing EPL, indicating that it is not functioning or not located within the transaction establishment. Storage medium 14 is preferably a fixed disk drive. Storage medium 14 stores EPL system configuration file 27, EPL data file 28, and missing EPL action file 29. CBSs 15a-d are connected together in series. Here, only four CBSs are shown. CBSs 15a-d each include one transmit antenna 37 and one to four receive antennas 38 for transmitting and receiving messages between CBSs 15a-d and EPLs 18a-d. CBSs 15a-d each include CBS circuitry 39 which controls operation of each CBS. CBS manager 36 schedules the actual transmission of price change messages to EPLs 18a-d and the reception of status messages from EPLs 18a-d for predetermined time slots. Turning now to Fig. 2, EPLs 18a-d each include battery 40, transmit and receive antenna 42, display 46, memory 47, and EPL circuitry 48. Battery 40 provides power to EPLs 18a-d. Transmit and receive antenna 42 receives price change and status messages from CBSs 15a-d. Transmit and receive antenna 42 transmits responses to price change and status messages to CBSs 15a-d. Display 46 displays price and possibly additional information. Display 46 is preferably a liquid crystal display and includes glass 49, but could be a flexible material such as plastic rather than glass, and may comprise a liquid crystal display (LCD). Memory 47 stores price verifier information and other display information, such as promotional information. Preferably, the price verifier information is a checksum of the displayed price. EPL circuitry 48 controls the internal operation of EPLs 18a-d. Turning now to Fig. 3, a map of a transaction establishment illustrates the location of shelf blocks 50 (shown shaded)separated by aisles 52. The shelf blocks 50 carry a large number of EPLs 18a-d. The locations of EPLs 18a-d are referenced to a two-dimensional coordinate system in which rows are identified by numerals and columns are identified by letters. There are four transmit antennas 37, located respectively at positions 5C, 5F, 5I and 5L. Each antenna is surrounded by four receive antennas 38; for example the transmit antenna at 5C is surrounded by receive antennas 38 at locations 3A, 3D, 7D, 7A and the transmit antenna at 5F is surrounded by receive antennas 38 at locations 3E, 3G, 7G and 7E. The four receive antennas are at the corners of a rectangle with the associated transmit antenna approximately in its centre; the rectangles associated with each transmit/receive system do not overlap. Conveniently, the antennas are installed in the ceiling space of the transaction establishment, and are cable-connected to the CBS awaiting 39 (see Fig.1). In Figure 3, a misplaced EPL 19 to be located is illustrated at 3D, on the right hand side of the shelf block as viewed. To locate the EPL 19, a message addressed to that EPL is transmitted by each transmit antenna 37 in turn and by each CBS 15 in turn. Suppose the only receive antenna 38 to detect an acknowledgment message from EPL 19 is the antenna located at position 3D. Thus 3D is a primary fix for the misplaced EPL. If from the information in EPL configuration file 27 it is known that position 3D is at the back of the soft drinks aisle', then it is also known that an approximate location for EPL 19 is at the back of the soft drinks aisle', and an operator then visits that area and searches for the EPL 19 by eye. In this example, only one receive antenna 38 at position 3D hears the acknowledgment of EPL 19. The primary fix for EPL 19 is position 3D. A less accurate approximation for the fix for EPL 19 is any one of positions 2C, 2D, 2E, 3C, 3E, 4C, 4D, or 4E that surround the primary fix. Turning now to Fig. 4, the misplaced EPL 19 is at position 4D, but on the opposite side of the shelf block 50 in comparison with Fig. 3. Suppose now that three receive antennae 38 at positions 3D, 3A, and 7D hear the acknowledgment of EPL 19. Antenna 3D reports a relative signal strength of "60", and antennae 3A and 7A report relative signal strengths of "30". By calculation from the relative signal strengths, the primary approximation for the fix for EPL 19 is position 4C. A secondary approximation for the fix for EPL 19 is any one of positions 3B, 3C, 3D, 4B, 4D, 5B, 5C, or 5D that surround the primary fix. Here, one of the secondary approximate fixes, 4D, is more accurate, but the 4C fix indicates which aisle 52 is relevant. Turning now to Fig. 5, the method of the present invention and the operation of EPL locator software 30 are explained in more detail, beginning with START 60. In step 62, EPL locator software 30 works with EPL control software 20 to cause CBSs 15a-d to transmit a query message to a particular missing EPL, such as EPL 19. In step 64, EPL locator software 30 listens for an acknowledgment message from the missing EPL. If an acknowledgment message is not received, the method proceeds to step 66. In step 66, EPL locator software 30 determines whether the maximum number of transmission retries has been exceeded. Preferably, sixteen is the maximum retry level, but other retry levels may be chosen as the maximum by an operator. If it has not been exceeded, the method returns to step 62 to transmit the query again. If it has been exceeded, the method proceeds to step 68. In step 68, EPL locator software 30 displays, prints, and/or stores a message indicating that the missing EPL cannot be located. The EPL is either not in the store or not functioning. The method ends in step 79. Returning to step 64, if an acknowledgment is received, EPL locator software 30 determines an approximate location of the missing EPL in step 70. In step 72, EPL locator software 30 selects other EPLs within the determined approximate location by reading EPL system configuration file 27. In step 74, EPL locator software 30 works with EPL control software 20 to cause CBSs 15a-d to transmit a query message to the missing EPL and to the selected EPLs. In step 76, EPL locator software 30 determines which of the other EPLs is closest to the missing EPL by examining relative signal strengths from all receive antennae that obtain a response. Often normalized signals are used in the calculation, taking account of received noise also. In step 78, EPL locator software 30 displays, prints, and/or stores the location of the missing EPL. An operator may then visit the determined location, retrieve the missing EPL, and reinstall it in the correct location. In step 79, the method ends. In an additional use of the step 76, the EPL locator software 30 reads previous location information in EPL configuration file 27 and directs the operator to where the missing EPL should be placed once it is found. Turning now to Fig. 6, step 70 of Fig. 5 is explained in more detail, beginning with START 80. Additionally, if for some reason in step 76 previous location information is not available in EPL configuration file 27, then 76 would use the process in Fig. 5 as well. In step 82, the locations of antennas 38 are determined. As an optional step, the locations of CBSs 15a-d may be plotted on the map of Fig. 3, but are included in configuration file 27 at installation time. Thus step 82 is performed when the system is installed. In step 84, the locations of EPLs 18a-d are determined. As an optional step, the locations of EPLs 18a-d may be plotted on the map of Fig. 3. This information is available in EPL configuration file 27, thus step 84 must be performed regularly since changes occur often, but not necessarily for every location of a misplaced EPL. In step 85, EPL control software causes CBSs 15a-d to transmit a query message to a particular missing EPL, such as EPL 19. In step 86, EPL locator software 30 listens for an acknowledgment message from the missing EPL. In step 88, EPL locator software 30 determines the signal strengths of any acknowledgment message from the missing EPL to one of antennas 38 within CBSs 15a-d. In step 89, EPL locator software 30 determines whether signal strength information for the last of antennas 38 has been determined. If all CBSs 15a-d have been polled for signal strength information about their antennas 38, the method continues to step 90. If a CBS has not been polled, the method returns to step 88. In step 90, EPL locator software 30 determines the primary and secondary estimates of fixes to the antennas 38 on the map in Figs. 3 and 4. If multiple antennas 38 receive the acknowledgment message, EPL locator software 30 uses relative signal strengths, e.g. triangulation technique, to determine the approximate location of the missing EPL. In step 92, EPL locator software 30, using information in EPL configuration file 27, optionally converts the approximate locations to types of goods on the shelves 50. In step 94, EPL locator software 30 displays, prints, and/or stores in missing EPL action file 29 the 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. 7. In step 96, the method ends.

Claims: A method of locating an electronic price label (19) in a transaction establishment characterized by the steps of: (a) receiving (64) a message from said electronic price label; (b) determining (70) from characteristics of the received message a first approximate location of said electronic price label; (c) selecting (72) other electronic price labels in proximity with the first approximate location; (d) receiving (74) messages from a number of the other electronic price labels whose locations are known; (e) determining (76) from characteristics of the received messages which of the other electronic price labels is closest to said electronic price label; and (f) determining (78) a second approximate location of said electronic price label based on the location of the closest other electronic price label. A method according to claim 1, characterized by receiving the return message from said electronic price label by a number of receive antennas, and determining said first approximate location of said electronic price label from the relative signal strengths of the received messages.

Inventors: GOODWIN JOHN C III, ZIMMERMAN TERRY L, GOODWIN, JOHN C., III, ZIMMERMAN, TERRY L.
Applicants: NCR INT INC, NCR INTERNATIONAL INC.
Application year: 1997
Main classification: G09F9
IPC codes: G06Q30, G08B13, G07G1, G09F3