JP2010184072A - Relay device, electronic shelf label device, relay method, and relay program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce power consumption in a terminal when a communication failure occurs, and also to rapidly perform connection to a relay device after restoration of the communication failure. <P>SOLUTION: The relay device receives a synchronizing signal which includes synchronous information to be used for synchronization with an electronic shelf label device from a server and transmits the signal to the electronic shelf label device. In the relay device, when the synchronizing signal is not received from the server, an alternative synchronizing signal including the synchronous information of the synchronizing signal is generated and transmitted to the electronic shelf label device in synchronous timing. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a relay device, an electronic shelf label device, a relay method, and a relay program.

Electronic shelf label (ESL) systems installed in supermarkets, etc. are installed in the vicinity of management servers installed in backyards, several relay devices installed in stores, and products. It consists of an electronic shelf label device (hereinafter referred to as a terminal device) that displays information such as the price of goods. The terminal device performs wireless communication in synchronization with several relay devices installed in the system, and acquires information necessary for display from the server via the relay device. Since this terminal device is normally battery-driven, it is required to have low power consumption.
By the way, when a communication failure with the server occurs, the relay device cannot receive information from the server. Since the relay device of the prior art cannot receive information from the server, the information transmission to the terminal device is stopped. Communication failures with the server may occur due to causes that require repair work such as failure of communication members of the server or relay machine, incomplete connection, deterioration of radio wave quality (in the case of wireless communication), etc. Or the server is powered off. For example, even when the power of the server is turned off after the store is closed, the relay device of the conventional technology stops transmitting information to the terminal device.

  It is known that when information transmission from the relay device is stopped, the terminal device retries communication with the relay device. It is also known that the terminal device searches for another relay device that can communicate, and if another relay device is found, communicates with the relay device. It is also known that the terminal device can reduce power consumption by gradually increasing the interval of reception processing when another relay device is not found even after searching (Patent Document 1).

JP 2008-168057 A

However, when the terminal device performs a communication retry or a search for a relay device, power is consumed for these processes. When searching for a relay device, the terminal device does not know the reception frequency and reception timing of the synchronization signal from the relay device, and needs to monitor the synchronization signal from the relay device at all receivable reception frequencies and reception timings. is there. In this case, the terminal device has a drawback in that a large amount of power is generated as compared with the case where the reception frequency and reception timing of the synchronization signal are synchronized.
In addition, when the reception processing interval is gradually increased, the terminal device has a drawback that it is difficult to connect to the relay device even if the communication failure is recovered, compared to the case where the reception processing interval is not increased. there were.
As described above, the conventional technology has a drawback that when a communication failure occurs, a large amount of power is consumed in the terminal device, and after the communication failure is recovered, the terminal device cannot be quickly connected to the relay device. It was.

  The present invention has been made in view of the above points, and its purpose is to reduce the power consumption of a terminal device when a communication failure occurs, and to quickly connect to a relay device after recovery from the communication failure. It is to provide a relay device, an electronic shelf label device, a relay method, and a relay program that can be performed.

(1) The present invention has been made to solve the above problems, and the present invention receives a synchronization signal including synchronization information used for synchronization with an electronic shelf label device from a server and receives the electronic shelf. In the relay device that transmits to the tag device, when the synchronization signal cannot be received from the server, an alternative synchronization signal including synchronization information of the synchronization signal is generated and transmitted to the electronic shelf label device at the synchronization timing. This is a characteristic relay device.
According to the above configuration, when the relay device cannot receive the synchronization signal from the server, the relay device generates an alternative synchronization signal including synchronization information of the synchronization signal and transmits it to the electronic shelf label device at the synchronization timing. The electronic shelf label device can maintain synchronization with the relay device by the substitute synchronization signal, and can reduce power consumption of the electronic shelf label device compared with the case of searching for the relay device. it can. In addition, the electronic shelf label device can be quickly connected to the relay device after recovery from a communication failure, as compared with the case where the reception processing interval is gradually extended.

(2) Further, the present invention is characterized in that, in the above relay device, the alternative synchronization signal including communication state information indicating a communication state with the server is generated and transmitted.
According to the above configuration, since the relay device generates and transmits the alternative synchronization signal including communication state information indicating a communication state with the server, the electronic shelf label device includes a communication state included in the alternative synchronization signal. The connection destination can be changed according to the information. Further, it is possible to prevent the electronic shelf label device from making a communication request to the relay device whose communication state information is abnormal.

  (3) Further, the present invention provides an electronic shelf label device that receives from the relay device a synchronization signal that is a synchronization signal received from a server by the relay device and includes synchronization information used for synchronization with the relay device. The relay device of the connection destination is changed according to communication state information included in an alternative synchronization signal including synchronization information of the synchronization signal and indicating communication state between the server and the relay device. This is an electronic shelf label device.

  According to the present invention, when the synchronization signal cannot be received from the server, the alternative synchronization signal including the synchronization information of the synchronization signal is generated and transmitted to the electronic shelf label device at the synchronization timing. Synchronization with the relay device can be maintained by the synchronization signal, and the power consumption of the electronic shelf label device can be reduced as compared with the case of searching for the relay device. In addition, the electronic shelf label device can be quickly connected to the relay device after recovery from the communication failure, as compared with the case where the reception processing interval is gradually extended.

1 is a schematic diagram of an electronic shelf label system according to an embodiment of the present invention. It is a schematic timing chart of the radio signal between the relay apparatus which concerns on this embodiment, and a terminal device. It is a schematic block diagram which shows the structure of the synchronizing signal between the relay apparatus and terminal device which concern on this embodiment. It is a schematic block diagram which shows the hardware constitutions of the apparatus which the electronic shelf label system which concerns on this embodiment comprises. It is a schematic block diagram which shows the function structure of the relay apparatus which concerns on this embodiment. It is a figure which shows an example of the communication status information which concerns on this embodiment. It is a schematic block diagram which shows the function structure of the terminal device which concerns on this embodiment. It is a figure which shows an example of the relay apparatus information which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the relay apparatus which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the terminal device which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the optimal relay apparatus selection process which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the search process which concerns on this embodiment. It is a flowchart which shows an example of operation | movement of the electronic shelf label system which concerns on this embodiment.

(Embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, an electronic shelf label system and radio signals between a relay device and an electronic shelf label device (hereinafter referred to as a terminal device) will be described with reference to FIGS.

<About electronic shelf label system>
FIG. 1 is a schematic diagram of an electronic shelf label system according to an embodiment of the present invention.
As shown in this figure, the electronic shelf label system has a management server A1 installed in a backyard, etc., several relay devices Bn installed in a store, and prices of products etc. installed in the vicinity of products etc. Terminal devices C11 to C1x, C21 to C2y, and Cm1 to Cmz (hereinafter referred to as C11 to Cmz) that display display information such as.

  The management server A1 and the relay devices B1 to Bn are connected by a wireless or wired communication network such as a LAN (Local Area Network), for example. Further, each of the relay devices B1 to Bn and the electronic shelf label terminals C11 to Cmz perform wireless communication by, for example, WPAN (Wireless Personal Area Network) conforming to IEEE802.15.4.

  The terminal devices C11 to Cmz display the display information received from the management server A1 via the relay devices B1 to Bn. This figure shows that the terminal devices C11 to C1x, C21 to C2y, and Cm1 to Cmz are installed in a range where they can communicate with the relay devices B1 and B2, the relay device B2, the relay device Bn, and the relay device Bn, respectively. Show. That is, the terminal devices C11 to Cmz are installed in a range where communication with one or a plurality of relay devices B1 to Bn is possible.

The management server A1 outputs a data signal to the relay apparatuses B1 to Bn so that each of the relay apparatuses B1 to Bn transmits a radio signal at the timing shown in FIG. The relay apparatuses B1 to Bn modulate the data signal input from the management server A1 into a radio signal and transmit the radio signal to the terminal apparatuses C11 to Cmz. Here, the data signal output from the management server A1 includes a synchronization signal for synchronizing the relay apparatuses B1 to Bn and the terminal apparatuses C11 to Cmz.
The relay devices B1 to Bn according to the present embodiment have the same synchronization data (synchronization information) as the synchronization signal when a communication failure such as an abnormality in the network between the management server A1 or the management server A1 and the own device occurs. Is generated and transmitted to the terminal devices C11 to Cmz. The terminal devices C11 to Cmz continue to maintain synchronization with the relay devices B1 to Bn by the alternative synchronization signal.

  Hereinafter, the management server A1 is referred to as the management server a1, the relay devices B1 to Bn are referred to as the relay device b1, and the terminal devices C11 to Cmz are referred to as the terminal device c1.

<About wireless signals>
FIG. 2 is a schematic timing chart of a radio signal between the relay device b1 and the terminal device c1 according to the present embodiment. In this figure, the horizontal axis is the time axis, and the vertical axis is the relay apparatuses B1 to Bn. Wireless communication between the relay device b1 and the terminal device c1 is performed by repeating the basic frame transmission period h.

As shown in FIG. 2, the basic frame transmission period h includes a synchronization period i, a data period j, and a competition period k. The synchronization period i is a period during which the relay device b1 transmits a synchronization signal S for synchronizing the relay device b1 and the terminal device c1. The data period j is a period during which the relay apparatus b1 transmits transmission data D that is actual data addressed to the terminal apparatus c1.
The competition period k is a period during which the relay device b2 receives a radio signal from the terminal device c1. In the competition period k, for example, the terminal device c1 transmits a participation request for requesting connection to any one of the relay devices b1.

FIG. 2 shows that the synchronization signals S and transmission data D transmitted by the relay apparatuses B1 to Bn are the synchronization signals S1 to Sn and the transmission data D1 to Dn, respectively. Moreover, this figure shows that the relay apparatuses B1 to Bn transmit the synchronization signals S1 to n at the synchronization signal transmission timings Sti1 to Sti1 that are the 1st to nth transmission orders, respectively, in the synchronization period i. This figure shows that the synchronization signal S and the transmission data D transmitted by each of the relay apparatuses B1 to Bn are transmitted in a time division manner. In addition, for the competition period k, time (referred to as competition time) is allocated to each relay device B1 to Bn, and the terminal device c1 sends a signal addressed to each relay device B1 to Bn to each relay device B1 to Bn. Send in the assigned competition time.
Note that the relay device IDs of the relay devices B1 to Bn are relay device IDs “1” to “n”, respectively. That is, the symbols “1” to “n” of the synchronization signal transmission timings Sti1 to Sti-n correspond to the relay device ID.

FIG. 3 is a schematic configuration diagram illustrating a configuration of the synchronization signal S between the relay device b1 and the terminal device c1 according to the present embodiment. In this figure, the horizontal axis is the time axis.
The synchronization signal S includes information on synchronization data, transmission source information, basic frame period length, communication status bits, data transmission start time, and competition time start time. Each information is a fixed-length bit string having a predetermined number of bits.

  The synchronization data is a predetermined bit string and indicates that the synchronization signal S is started. The transmission source information is information including identification information of the management server a1 that has generated the synchronization signal S and relay device IDs (“1” to “n”) that are identification information of the relay device b1 that has transmitted the synchronization signal S. . The basic frame period length information is information indicating the time interval of the basic frame transmission period h.

  The communication status bit is information indicating the communication status detected by the relay device b1 (see FIG. 6). Specifically, in the communication status bit, “111” set as an initial value by the management server a1 indicates that communication is normal. When the relay apparatus b1 detects a communication failure, the initial value “111” (normal) is masked by the relay apparatus b1 and becomes another value. For example, the communication status bit “001” indicates the communication status “network connection not possible”. Details of the value of the communication status bit will be described later.

  The information on the data time start time is information indicating the start time of the time (data time) assigned to transmit the transmission data D by the relay device b1 that has transmitted the synchronization signal S in the data period j. For example, in FIG. 2, the data time start time of the relay device B1 is information indicating the time when transmission of the transmission data D1 is started. The information on the competition time start time is information indicating the start time of the competition time allocated for the relay apparatus b1 that has transmitted the synchronization signal S to receive the signal addressed to itself in the competition period k. For each relay device b1, the data time start time and the competition time start time are relative time information from the start time of the synchronization signal S.

<About the hardware configuration of the device>
Hereinafter, the configuration of an apparatus included in the electronic shelf label system will be described.
FIG. 4 is a schematic configuration diagram illustrating a hardware configuration of an apparatus included in the electronic shelf label system according to the present embodiment.

  The management server a1 includes a CPU (Central Processing Unit) a11, a RAM (Random Access Memory) a12, a storage medium a13, a clock a14, a display unit a15, a LAN connection I / F (interface) a16, and an operation unit a17. Is done. The CPU a11, RAM a12, storage medium a13, clock a14, display unit a15, LAN connection I / F (interface) a16, and operation unit a17 are connected via a bus and can communicate with each other. The CPU a11 is a central processing unit and controls the processing of the management server a1 by reading and executing a program stored in the storage medium a13. The RAMa12 is a read / write memory as needed. The clock a14 includes a crystal resonator and outputs a signal having a constant frequency to the CPU a11. The operation unit a17 is an input device such as a keyboard or a mouse. The LAN connection I / Fa 16 communicates with the relay device b1 via the LAN. The display unit a15 is a display device such as a liquid crystal display or a CRT (Cathode Ray Tube) display.

  The relay device b1 includes a CPU b11, a RAM b12, a storage medium b13, a clock b14, a LAN connection I / Fb15, and a short-range wireless I / Fb16. The CPU b11, the RAM b12, the storage medium b13, the clock b14, the LAN connection I / Fb15, and the short-range wireless I / Fb16 are connected via a bus and can communicate with each other. The CPU b11 is a central processing unit, and controls the operation of the relay device 2 by reading and executing a program stored in the storage medium b13. The storage medium b13 is a semiconductor memory, and stores a program executed by the CPU b11, a relay device ID of the own device, communication state information (FIG. 6), and the like. The RAM b12 is a read / write memory as needed. The clock a14 includes a crystal resonator and outputs a signal having a constant frequency to the CPU a11. The LAN connection I / Fb 15 communicates with the management server a1 via the LAN. The short-range wireless I / Fb 16 performs wireless communication with the terminal device c1.

  The terminal device c1 includes a CPU c11, a RAM c12, a storage medium c13, a clock c14, a display unit c15, a participation switch c16, a short-range wireless I / Fc 17, and a battery c18. The CPU c11, RAM c12, storage medium c13, clock c14, display unit c15, participation switch c16, short-range wireless I / Fc 17, and battery c18 are connected via a bus and can communicate with each other.

  The CPU c11 is a central processing unit, and controls the operation of the terminal device c1 by reading and executing a program stored in the storage medium c13. The storage medium c13 is a semiconductor memory, and stores a program executed by the CPU c11, relay device information (FIG. 8), and the like. The RAM c12 is a read / write memory as needed. The clock a14 includes a crystal resonator and outputs a signal having a constant frequency to the CPU a11. The display part c15 is comprised from LCD and LED, and displays display information, such as a price of goods. The participation switch c16 is a relay device b1 that relays communication with the management server a1, and is a switch for starting a search for a communicable relay device b1. The short-range wireless I / Fc 17 performs wireless communication with the relay device b1. The battery c18 supplies power for operating each unit of the terminal device c1.

<Regarding Functional Configuration of Relay Device b1>
FIG. 5 is a schematic block diagram illustrating a functional configuration of the relay device b1 according to the present embodiment. The relay device b1 includes a communication state storage unit b131, a communication state detection unit b111, a management server communication unit b151, a relay device ID storage unit b132, a signal control unit b112, a synchronization unit b141, a synchronization signal information storage unit b121, and terminal device communication. Part b161 is included.
The signal control unit b112 includes a communication state bit generation unit b1121, a synchronization signal generation unit b1122, and a transmission data generation unit b1123.

  The communication state storage unit b131 stores communication state information (FIG. 6) in which the communication state bit and the communication state information of the relay device b1 are associated with each other. As described above, the communication status bit is a bit string included in the synchronization signal S (see FIG. 3). The communication state information is information indicating the communication state detected by the relay device b1. An example of the communication status information will be described later.

The communication state detection unit b111 monitors the information input from the management server communication unit b151 and the state of the management server communication unit b151, and detects the communication state. The communication state detection unit b111 outputs information on the detected communication state to the communication state bit generation unit b1121.
The management server communication unit b151 communicates with the management server a1.
The relay device ID storage unit b132 stores the relay device ID of the own device.

  The communication state bit generation unit b1121 reads the communication state storage unit b131, and generates a bit string of communication state bits corresponding to the communication state information input from the communication state detection unit b111. Note that the communication state bit generation unit b1121 does not generate a bit string of communication state bits when the communication state information input from the communication state detection unit b111 indicates “normal”. The communication state bit generation unit b1121 outputs the generated bit string to the synchronization signal generation unit b1122.

The synchronization signal generation unit b1122 is a data signal input from the management server a1 when no bit string is input from the communication state bit generation unit b1121, that is, when the communication state information is “normal”. The data signal in which the information shown in FIG. 3 is set is used as it is for the synchronization signal. The communication state bit included in this signal is set to “111” which is an initial value set by the management server a1 and indicates that the communication state is normal. The synchronization signal generation unit b1122 sets the relay device ID of the own device read from the relay device ID storage unit b132 in the transmission source information included in the data signal input from the management server a1, and generates the synchronization signal S.
The synchronization signal generation unit b1122 outputs the generated synchronization signal S to the terminal device communication unit b161, and stores the information of the synchronization signal S in the synchronization signal information storage unit b121. That is, the synchronization signal information storage unit b121 stores information on the latest synchronization signal S output by the synchronization signal generation unit b1122 when the communication state information is “normal”. The information on the synchronization signal S is information indicating the bit string of the synchronization signal and the synchronization signal transmission timing. The information indicating the synchronization signal transmission timing is the timing at which the synchronization signal S generated by the synchronization signal generation unit b11 is output to the terminal device communication unit b161 and the basic frame transmission period h included in the synchronization signal S. The timing obtained by multiplying the basic frame transmission period h by an integer with respect to the timing at which the synchronization signal S is output is the synchronization signal transmission timing.

On the other hand, the synchronization signal generation unit b1122 reads the information of the synchronization signal S stored in the synchronization signal information storage unit b121 when a bit string is input from the communication state bit generation unit b1121. The synchronization signal generation unit b1122 masks the communication state bit (value is “111”) included in the read synchronization signal S, so that the bit string input from the communication state detection unit b111 to the communication state bit of the synchronization signal S To generate an alternative synchronization signal.
The synchronization signal generation unit b1122 outputs the generated alternative synchronization signal as the synchronization signal S to the terminal device communication unit b161 at the synchronization signal transmission timing indicated by the signal input from the synchronization unit b141 described later. The output synchronization signal S is transmitted to the terminal device c1 via the terminal communication unit b161 at the synchronization signal transmission timing of the relay device b1.
Moreover, the signal control part b112 transmits the signal received from the terminal device c1 to the management server a1.

The transmission data generation unit b1123 outputs the data signal input from the management server a1 and transmitted in the data period j to the terminal device communication unit b161 as transmission data D.
The synchronization unit b141 reads information indicating the synchronization signal transmission timing from the synchronization signal information storage unit b121, generates a signal indicating the synchronization signal transmission timing, and outputs the signal to the synchronization signal generation unit b1122.
The terminal device communication unit b161 performs wireless communication with the terminal device c1.

<About communication status information>
The communication status information is managed by a relational database.
FIG. 6 is a schematic diagram illustrating an example of communication state information according to the present embodiment. As shown in the figure, the communication status information is two-dimensional tabular data composed of rows and columns, and includes columns of communication status bits and items of communication status information.

  For example, in the first communication state information of FIG. 6, the communication state bit “000” is the communication state “application connection impossible”. In this communication state, services below the application layer of the OSI (Open Systems Interconnection) reference model can be used normally, but due to application bugs and high database processing load, the service at the application layer cannot be used. Indicates that there is. In the second communication status information in FIG. 6, the communication status bit “001” is the communication status “network connection is not possible”, and services in layers below the network layer can be used normally. Indicates that the network layer service cannot be used due to concentration of access.

Further, the third communication status information in FIG. 6 indicates that the communication status bit “010” is the communication status “physical connection impossible (LAN cable)”, and the line connection is made such that the LAN cable of the relay device b1 is disconnected. In some cases, the physical layer is not available. Further, the fourth communication state information in FIG. 6 is that the communication state bit “011” is the communication state “physical connection impossible (radio wave quality)”, and the received signal strength of the radio signal from the management server a1 in the relay device b1 This indicates that the physical layer cannot be used when wirelessly connected, such as low wireless communication.
Although not included in the communication status information of FIG. 6, the communication status bit “111” indicates the communication status “normal”. As described above, the initial value of the communication state bit included in the data signal from the management server a1 is the communication state bit “111”.

<Regarding Functional Configuration of Terminal Device c1>
FIG. 7 is a schematic block diagram illustrating a functional configuration of the terminal device c1 according to the present embodiment. The terminal device c1 includes a relay device communication unit c171, a display unit c151, a reception unit c111, a synchronization unit c141, a signal generation unit c113, and a relay device information storage unit c131.
The signal generation unit c113 includes a relay device selection unit c1131 and a participation processing unit c1132.

  The relay device communication unit c171 performs wireless communication with the relay device b1. The relay device communication unit c171 down-converts the radio frequency signal received from the relay device b1 into a baseband signal and outputs the baseband signal to the reception unit c111. Also, the relay device communication unit c171 up-converts the baseband signal input from the signal generation unit c113 into a radio frequency signal and transmits the signal to the relay device b1.

The receiving unit c111 demodulates the signal input from the relay device communication unit c171 and detects received data. Here, the reception unit c111 detects the bit string of the synchronization data of the synchronization signal S included in the reception data. The receiving unit c111 identifies the start of the synchronization signal S from the detected bit string of the synchronization data, and detects information included in the synchronization signal S based on the information of the bit string of the synchronization signal S stored in advance. Of the detected information, the reception unit c111 outputs information on the relay device ID, the basic frame period length, the data time start time, and the competition time start time included in the transmission destination information to the synchronization unit c141.
As will be described later, when the synchronization unit c141 synchronizes with the basic frame period h, the relay device ID may be detected based on the timing at which the synchronization signal is received, that is, the synchronization signal transmission timing Sti1 to n.

The receiving unit c111 detects the received signal strength of the received signal from the relay device b1, and outputs the detected received signal strength to the relay device information storage unit c131. The receiving unit c111 outputs the relay device ID and the communication state bit included in the transmission destination information among the information detected from the received data together with the received signal strength to the relay device information storage unit c131.
Further, the reception unit c111 selects the reception timing of the transmission data based on a signal indicating the data time start time input from the synchronization unit c141 described later, and demodulates the transmission data D addressed to itself. The reception unit c111 causes the display unit c151 to display the demodulated transmission data D addressed to the own device.

The synchronization unit c141 determines which of the synchronization signal transmission timings Sti1 to Sti-n of the received synchronization signal is based on the relay device ID input from the reception unit c111. Specifically, when the relay device ID input from the reception unit c111 is “p”, the synchronization unit c141 determines that the synchronization signal transmission timing of the received synchronization signal is Sti “p”. The synchronization unit c141 calculates the start time of the next basic frame period h based on the determined synchronization signal transmission timing Sti “p” and the basic frame period length. Accordingly, the synchronization unit c141 synchronizes with the basic frame period h. The synchronization unit c141 generates a signal indicating the start time of the basic frame period h based on the signal of the clock c14 in FIG. 4 and outputs the signal to the reception unit c111.
Further, the synchronization unit c141 is a signal indicating the data time start time of the relay device of this relay device ID, based on the relay device ID, the data time start time, and the competition time start time information input from the reception unit c111, And the signal which shows competition time start time is produced | generated, and it outputs to the receiving part c111 and the signal generation part c113.

The relay device information storage unit c131 stores relay device information (FIG. 8) in which the relay device ID, the received signal strength, and the communication state bit are associated with each other. An example of the relay device information will be described later.
The relay device selection unit c1131 selects the relay device b1 to be connected based on the relay device information stored in the relay information storage unit c131. Details of the processing of the relay device selection unit will be described later together with the description of the operation of the terminal device c1. The relay device selection unit c1131 outputs the relay device ID of the selected relay device b1 to the participation processing unit c1132.

  When the participation switch c16 in FIG. 4 is pressed and when the relay device ID is input from the relay device selection unit c1131, the participation processing unit c1132 performs a participation process for connecting to the relay device b1. When the relay device ID is input, the participation processing unit c1132 generates a participation request for requesting participation to the relay device b1 having the relay device ID. The participation processing unit c1132 outputs the generated participation request to the relay device communication unit c171 based on a signal indicating the competition time start time of the relay device ID. The output participation request is transmitted from the relay device communication unit c171 at the competition time start time of the relay device ID. On the other hand, when the participation switch c16 is pressed, the participation processing unit c1132 performs a participation process that is a participation process involving a search process for the relay device b1. Details of the search processing of the participation processing unit c1132 will be described later together with the description of the operation of the terminal device c1.

The relay device information is managed by a relational database.
FIG. 8 is a schematic diagram illustrating an example of relay device information according to the present embodiment. As shown in the figure, the relay device information is two-dimensional tabular data composed of rows and columns, and includes columns for each item of the relay device ID, the received signal strength, and the communication status bit. Here, the received signal strength is a relative value in which the highest value of the range assuming the radio wave strength of the synchronization signal is 100 and the lowest value is 0.

  For example, in the first relay device information in FIG. 8, the received signal strength of the radio signal from this relay device is “40%” for the relay device with the relay device ID “1” (relay device B1 in FIG. 1). It shows that. Also, this relay device information indicates that the status bit of the relay device with the relay device ID “1” is “001”, that is, the communication state is “application connection impossible” (see FIG. 6). Further, in the second and third relay device information in FIG. 8, the communication status bits are “111” and the communication status is “normal” for the relay devices with the relay device IDs “2” and “3”, respectively. It shows that. Further, this relay device information indicates that the received signal strengths of radio signals from the relay devices with the relay device IDs “2” and “3” are “90%” and “60%”, respectively.

Hereinafter, operations of the relay device b1 and the terminal device c1 will be described.
<About operation of relay device b1>
FIG. 9 is a flowchart showing an example of the operation of the relay device b1 according to the present embodiment.
(Step S101) The relay device b1 transmits inquiry data for making an inquiry about the communication state to the management server a1. Thereafter, the process proceeds to step S102.
(Step S102) The relay device b1 confirms whether or not response data from the management server a1 has been received. Thereafter, the process proceeds to step S103.
(Step S103) If it is determined in step S102 that response data has been received (success), the process proceeds to step S104. On the other hand, if it is determined in step S102 that no response data has been received (failure), the process proceeds to step S106.

(Step S <b> 104) The relay device b <b> 1 obtains a data signal that is a <b> 1 input from the management server and has a synchronization signal or transmission data information set therein. Thereafter, the process proceeds to step S105.
(Step S105) The relay device b1 sets the relay device ID of its own device in the data signal acquired in Step S104, and generates the synchronization signal S. Thereafter, the process proceeds to step S106.
(Step S106) The relay device b1 stores the information of the synchronization signal S generated in Step S105. Thereafter, the process proceeds to step S115.

(Step S107) The relay device b1 confirms the communication state of the own device. For example, the relay device b1 checks whether or not the LAN cable of its own device is disconnected, or whether or not the received signal strength of the radio signal from the management server a1 is equal to or less than a predetermined value. Thereafter, the process proceeds to step S108.
(Step S108) When it is determined in Step S107 that the communication state of the own apparatus is abnormal (Yes), the process proceeds to Step S112. For example, the relay device b1 determines that it is abnormal when the LAN cable of its own device is disconnected or when the received signal strength of the radio signal from the management server a1 is not more than a predetermined value. On the other hand, when it is determined in step S107 that the communication state of the own apparatus is normal (No), the process proceeds to step S109.

(Step S109) The relay device b1 counts up the number of times of failure, which is the number of times determined as failure in S103. Then, it progresses to step S110.
(Step S110) The relay device b1 checks whether or not the number of failures counted up in S109 is equal to or less than a predetermined value (for example, 3 times). Then, it progresses to step S111.
(Step S111) If it is determined in step S110 that the number of failures is equal to or less than a predetermined value (OK), the process proceeds to step S113. On the other hand, when it is determined in step S110 that the number of failures is greater than a predetermined value (NG), the process proceeds to step S112.
Note that the processing in steps S109 to S111 may be immediately restored if there is no abnormality in the relay device b1, that is, if there is an abnormality in the management server a1 or the network between the management server a1 and the relay device b1. There is a process to wait for the recovery. During the period of waiting for the restoration, the relay device b1 transmits a communication state bit indicating that the communication state is normal to the terminal device c1, and does not cause the terminal device c1 to perform a participation process performed when the communication state is not normal. Process. Therefore, in the process of S111, when it is determined that the number of failures is equal to or less than a predetermined value (OK), in step S114 described later, the communication status bit is set to “111” (normal) and an alternative synchronization signal is set. Generate.

(Step S112) The relay device b1 detects a communication state, and determines a communication state bit indicating the detected communication state. The communication status bit determined in step S112 is a communication status bit other than “111” (normal). Thereafter, the process proceeds to step S113.
(Step S113) The relay device b1 reads the information of the synchronization signal S stored in Step S106. Thereafter, the process proceeds to step S114.
(Step S114) The relay device b1 sets the communication state bit determined in Step S112 to the bit string of the synchronization signal S of the information read in Step S113, and generates an alternative synchronization signal. Thereafter, the process proceeds to step S115.

(Step S115) The relay device b1 transmits the synchronization signal S generated in Step S105 and the transmission data D acquired in S104 or the alternative synchronization signal generated in Step S114 as the synchronization signal S to the terminal device c1. Thereafter, the process proceeds to step S116.
(Step S116) The relay device b1 receives the response data from the terminal device c1. Then, it returns to step S101.

<Operation of Terminal Device c1>
FIG. 10 is a flowchart showing an example of the operation of the terminal device c1 according to the present embodiment.
(Step S201) The terminal device c1 receives the synchronization signal S or transmission data from the plurality of relay devices b1. Thereafter, the process proceeds to step S202.
(Step S202) The terminal device c1 performs a reception process of the synchronization signal S from the connection destination relay apparatus b1 (referred to as a connection destination relay apparatus) connected by the prior participation process. Thereafter, the process proceeds to step S203.
(Step S203) When the synchronization signal S from the connection destination relay device b1 can be received in Step S202 (successful reception), the process proceeds to Step S204. On the other hand, when the synchronization signal S from the connection destination relay apparatus b1 cannot be received in step S202 (reception failure), the process proceeds to step S207.

(Step S204) The terminal device c1 detects the received signal strength of the received synchronization signal S. Thereafter, the process proceeds to step S205.
(Step S205) The terminal apparatus c1 confirms whether or not the communication state of the connection destination relay apparatus b1 is normal based on whether or not the communication bit included in the received synchronization signal S is “111” (normal). To do. Thereafter, the process proceeds to step S206.
(Step S206) When it is determined in step S205 that the communication state of the connection destination relay apparatus b1 is normal, the process proceeds to step S210. On the other hand, if it is determined in step S205 that the communication state of the connection destination relay apparatus b1 is normal, that is, if the communication bit is not “111” (normal), the process proceeds to step S213.

(Step S207) The terminal device c1 counts up the number of failures, which is the number of times it has been determined that reception has failed in S203. Thereafter, the process proceeds to step S208.
(Step S208) The terminal device c1 checks whether or not the number of failures counted up in S207 is equal to or less than a predetermined value (for example, once). Thereafter, the process proceeds to step S209.
(Step S209) When it is determined in step S208 that the number of failures is equal to or less than a predetermined value (OK), the process proceeds to step S201. On the other hand, if it is determined in step S208 that the number of failures is greater than a predetermined value (NG), the process proceeds to step S213. Note that the processing of step S207 to step S209 is a process for waiting for the recovery, similarly to the processing of step S109 to S111 in FIG. 9, and the process of step S213 is not performed during the period of waiting for the recovery. It is processing of.

(Step S210) The terminal device c1 detects the received signal strength of the synchronization signal S from the plurality of relay devices b1 received in Step S201. The terminal device c1 compares the detected received signal strengths with respect to the connection destination relay device b1 and the relay device b1 other than the connection destination. Then, it progresses to step S211. Note that the terminal device c1 stores the detected received signal strength in association with the relay device ID as relay device information.
(Step S211) If the received signal strength of the connection destination relay device b1 is the highest (no change) in Step S210, it is determined not to change the connection destination relay device b1, and the connection with the current connection destination relay device b1 is continued. To do. In this case, the process proceeds to step S212. On the other hand, if there is a relay device b1 having the highest received signal strength other than the connection destination relay device b1 in step S210 (changed), it is determined that the connection destination relay device b1 is changed to the relay device b1 having the highest received signal strength. The In this case, the process proceeds to step S213.

(Step S212) The terminal device c1 transmits transmission data when transmitting data to the connection destination relay device b1. Thereafter, the process returns to step S201.
(Step S213) The terminal device c1 performs an optimum relay device selection process to be described later. Thereafter, the process returns to step S201.

  In addition, although the terminal device c1 which concerns on this embodiment has received the synchronizing signal S or transmission data from the some relay apparatus b1 in FIG.10 S201, this invention is not limited to this, For example, a terminal device Normally, c1 does not need to receive the synchronization signal S or the transmission data from other than the currently connected relay device (the steps S210 and S211 are also not performed). In this case, after the terminal device c1 starts receiving failure in step S203 (or after the number of failures becomes one less than the specified value in step S208), the terminal device c1 performs step S201 after step S209. The synchronization signal S or the transmission data may be received from the plurality of relay devices b1. In this way, when the terminal device c1 performs normal communication with the relay device b1, unnecessary communication such as receiving the synchronization signal S or transmission data from the plurality of relay devices b1 is omitted, and the terminal device Power consumption can be reduced.

FIG. 11 is a flowchart showing an example of the operation of the optimum relay device selection process (step S213 in FIG. 10) according to the present embodiment.
(Step S301) The terminal device c1 checks whether or not any relay device ID is stored in the relay device information. That is, it is confirmed whether or not there is no relay device b1 that has received the synchronization signal S. Thereafter, the process proceeds to step S302.
(Step S302) If it is determined in step S301 that the relay device ID is not stored in the relay device information (Yes), the process proceeds to step S309. On the other hand, if it is determined in step S301 that the relay device ID is stored in the relay device information (No), the process proceeds to step S303.
(Step S303) The terminal device c1 confirms whether or not the communication state of the connection destination relay device b1 is normal based on whether or not the communication bit included in the received synchronization signal S is “111” (normal). To do. Thereafter, the process proceeds to step S304.

  (Step S304) When it is determined in Step S303 that there is at least one relay device b1 whose communication state is normal (normal), that is, there is a relay device b1 whose communication bit is “111” (normal) The process proceeds to step S305. On the other hand, when it is determined in step S303 that there is no relay device b1 whose communication state is normal (all abnormal), the process proceeds to step S308.

(Step S305) The terminal device c1 selects the relay device b1 having the maximum received signal strength among the relay devices b1 whose communication state confirmed in Step S303 is normal. Thereafter, the process proceeds to step S306.
(Step S306) When the relay device b1 selected in Step S305 is the connection destination relay device b1, the process proceeds to Step S308. On the other hand, if the relay device b1 selected in step S305 is a relay device b1 other than the connection destination relay device b1, the process proceeds to step S307.

(Step S307) The terminal device c1 transmits a participation request to the relay device b1 selected in Step S305, and performs a process of changing the connection-destination relay device b1.
(Step S308) The terminal device c1 maintains synchronization with the current connection destination relay device b1, and transmits and receives radio signals.
(Step S309) The terminal device c1 performs a participation process that is a participation process involving a search process of the relay apparatus b1 described later.

<About search processing>
FIG. 12 is a flowchart showing an example of the operation of the search process according to the present embodiment. This search process is the same as the process performed when the participation switch c16 in FIG. 4 is pressed, and is the process when the terminal device c1 searches for the relay device b1.
In the present embodiment, the relay device b1 and the terminal device c1 perform wireless communication using any of channels 11ch (channels) to 26ch having different frequencies.

(Step S401) The terminal device c1 checks whether or not a channel (designated channel) designated in advance that is a channel used by the device itself for wireless communication is stored. Thereafter, the process proceeds to step S402.
(Step S402) If it is determined in step S401 that the designated channel is stored (Yes), the process proceeds to step S408. On the other hand, when it is determined in step S401 that the designated channel is not stored (none), the process proceeds to step S403.

(Step S403) The terminal device c1 sets 11ch, which is the smallest channel among the channels used for wireless communication. Thereafter, the process proceeds to step S404.
(Step S404) The terminal device c1 performs the reception process of the synchronization signal S on the channel set in Step S403, and confirms whether or not the synchronization signal S has been received. Thereafter, the process proceeds to step S405.
(Step S405) When it is determined in step S404 that the synchronization signal S has been received (success), the process proceeds to step S412. On the other hand, when it is determined in step S404 that the synchronization signal S has not been received (failure), the process proceeds to step S406.

(Step S406) The terminal device c1 sets a channel increased by one channel to the channel for which the reception process has been performed in Step S404. For example, if reception processing is performed on 11ch in step S404, 12ch is set. Thereafter, the process proceeds to step S407.
(Step S407) The terminal device c1 determines whether or not the channel set in step S406 is 26 ch or less. If the channel is 26 ch or less (26 ch or less), the process returns to step S404. On the other hand, if the channel is larger than 26ch (larger than 26ch), the process proceeds to step S411.

(Step S408) The terminal device c1 determines the channel as the designated channel confirmed in S401. Thereafter, the process proceeds to step S409.
(Step S409) The terminal device c1 performs the reception process of the synchronization signal S on the channel set in Step S409, and confirms whether or not the synchronization signal S has been received. Thereafter, the process proceeds to step S410.
(Step S410) If the synchronization signal S can be received in step S409 (success), the process proceeds to step S412. On the other hand, when the synchronization signal S cannot be received in step S409 (failure), the process proceeds to step S411.

(Step S411) The terminal device c1 determines that the search for the relay device b1 has failed, and starts the process of step S401 again after a certain period of time, for example.
(Step S412) The terminal device c1 determines that the search for the relay device b1 has succeeded, and transmits a participation request to the relay device b1 of the relay device ID included in the synchronization signal S during the competition time of the relay device b1. To do.

<Operation of the electronic shelf label system>
FIG. 13 is a flowchart showing an example of the operation of the electronic shelf label system according to the present embodiment. This figure shows an operation when communication failure occurs in the connection-destination relay device B1 and communication becomes impossible. This figure is a diagram showing the operation of the terminal device C1, which is one of the management server A1, the relay devices B1 and B2, and the terminal devices C11 to C1x in FIG.
This figure also shows the operation in four basic frame transmission periods h1 to h4. The basic frame transmission periods h1 to h4 are synchronized periods i1 to i4, data periods j1 to j4, and competition periods k1 to k4, respectively. It is composed of
This figure is a diagram when the terminal device C1 is connected to the relay device B1 and is synchronized, and is a diagram when the predetermined specified value of the number of failures in FIG. 9 is “1”.

(Step S5011) The management server A1 transmits a data signal including the information of the synchronization signal S to the relay device B1 (relay device ID “1”). Thereafter, the process proceeds to step S5012.
(Step S5012) The management server A1 transmits a data signal including the information of the synchronization signal S to the relay device B2 (relay device ID “2”). Thereafter, the process proceeds to step S5021.

(Step S5021) The relay device B1 receives the signal transmitted in Step S5011 and duplicates the received data signal to generate the synchronization signal S1. The relay device B1 transmits the generated synchronization signal S1 to the terminal device C1. Thereafter, the process proceeds to step S5022. The synchronization signal S1 is transmitted at the synchronization signal transmission timing Sti1 in the synchronization period i1.
(Step S5022) The relay apparatus B2 receives the signal transmitted in Step S5012, duplicates the received data signal, and generates the synchronization signal S. The relay device B2 transmits the generated synchronization signal S to the terminal device C1. Thereafter, the process proceeds to step S5031. The synchronization signal S1 is transmitted at the synchronization signal transmission timing Sti2 in the synchronization period i1.

(Step S5031) The management server A1 transmits a data signal including synchronization signal information to the relay device B1. This data signal is a signal that cannot be received by the relay device B1 due to a communication failure based on a network failure between the management server A1 and the relay device B1. Thereafter, the process proceeds to step S5032.
(Step S5032) The management server A1 transmits a data signal including synchronization signal information to the relay device B2. Thereafter, the process proceeds to step S5041.

(Step S5041) The relay device B1 reads the synchronization signal S transmitted in Step S5021, and generates an alternative synchronization signal. The relay device B1 transmits the generated alternative synchronization signal at the synchronization timing of the synchronization signal S. Thereafter, the process proceeds to step S5042.
Here, in step S5041, not in the case where there is an abnormality in the relay device B1 (in the case of “No” in step S108 in FIG. 9), the number of failures (one time) is equal to or less than a predetermined value (one time). Since this is the case (in the case of “OK” in step S111 of FIG. 9), the process of step S112 of FIG. 9 is not performed. That is, the communication status bit of this alternative synchronization signal is “111” (normal). The terminal device C1 that has received this alternative synchronization signal determines that the communication state of the relay device B1 is “normal” (determines “normal” in step S206 in FIG. 10), and immediately selects the optimum relay device in step S213. No processing is performed.
(Step S5042) The relay device B2 receives the signal transmitted in Step S5032, and duplicates the received data signal to generate the synchronization signal S. The relay device B2 transmits the generated synchronization signal S to the terminal device C1. Thereafter, the process proceeds to step S5051.

(Step S5051) The management server A1 transmits a data signal including information on the synchronization signal to the relay device B1. This data signal is a signal that cannot be received by the relay device B1 due to a communication failure based on a network failure between the management server A1 and the relay device B1. Thereafter, the process proceeds to step S5052.
(Step S5052) The management server A1 transmits a data signal including information on the synchronization signal to the relay device B2. Thereafter, the process proceeds to step S5061.

(Step S5061) The relay device B1 reads the synchronization signal S transmitted in Step S5021, and generates an alternative synchronization signal. The relay device B1 transmits the generated alternative synchronization signal at the synchronization timing of the synchronization signal S. Thereafter, the process proceeds to step S5062.
Here, in step S5061, it is not the case where there is an abnormality in the relay device (in the case of “No” in step S108 of FIG. 9), but the number of failures (2 times) is larger than a predetermined value (1 time). (In the case of “NG” in step S111 of FIG. 9), the process of step S112 of FIG. 9 is performed. That is, the communication status bit of this alternative synchronization signal is a bit string other than “111” (normal).
(Step S5062) The relay device B2 receives the data signal transmitted in Step S5032, and duplicates the received data signal to generate the synchronization signal S. The relay device B2 transmits the generated synchronization signal S to the terminal device C1. Thereafter, the process proceeds to step S507.

  (Step S507) The terminal device C1 receives the alternative synchronization signal transmitted in step S5061. The terminal device C1 determines that the communication status of the connection destination relay device b1 is abnormal based on the communication status bit of the received alternative synchronization signal (determines “abnormal” in step S206 in FIG. 10), and selects the optimum relay device. I do. The terminal device C1 selects the relay device B2 as a new connection destination relay device (step S305 in FIG. 11). The terminal device C1 transmits a participation request to the relay device B2 in order to change the connection destination relay device from the relay device B1 to the relay device B2. This participation request is transmitted to the management server A1 via the relay device B2. Thereafter, the process proceeds to step S5081.

  Since the processes of steps S5081, S5082, S5091, and S5092 are the same as the processes of steps S5051, S5052, S5061, and S5062, respectively, description thereof will be omitted.

(Step S510) The management server A1 determines whether or not to join the terminal device C1 that has transmitted the participation request, that is, whether or not to connect this terminal device C1 via the relay device B1. When it is determined that the terminal device C1 is allowed to participate, the management server A1 generates a data signal including information on transmission data addressed to the terminal device C1. The management server A1 transmits the generated data signal to the relay device B2. Thereafter, the process proceeds to step S511.
(Step S511) The management server A1 receives the data signal transmitted in step S510, duplicates the received data signal, and generates participation permission (transmission data D2). The management server A1 transmits the generated participation permission to the terminal device C1.

  As described above, according to the present embodiment, when the relay device b1 cannot receive the synchronization signal from the management server a1, the alternative synchronization signal including the synchronization information of the synchronization signal is generated and is transmitted to the terminal device c1 at the synchronization timing. Send. Thereby, the terminal device c1 can maintain the synchronization with the relay device b1 by the alternative synchronization signal, and the power consumption of the terminal device c1 can be reduced compared with the case where the relay device b1 is searched. Further, as compared with the case where the terminal device c1 gradually increases the interval of the reception process, the terminal device c1 can be quickly connected to the relay device b1 after the communication failure is recovered.

As described above, the terminal device c1, the relay device b1, and the management server a1 according to the present embodiment are installed in a store such as a supermarket. In such a store, it is preferable to turn off the power of the management server a1 from the viewpoint of power saving and device load reduction after the store is closed.
According to the present embodiment, even when the power of the management server a1 is turned off, the relay device b1 generates the alternative synchronization signal including the synchronization information of the synchronization signal and sends it to the terminal device c1 at the synchronization timing. Send. Thereby, the terminal device c1 can turn off the power of the management server a1 without maintaining the synchronization with the relay device b1 and increasing the power consumption, and the power consumption of the management server a1 after the store is closed, for example Reduction and load reduction.

Further, for example, when the power of the management server is turned off, it is conceivable that the power of the terminal device is also turned off to prevent the terminal device from consuming power due to the search for the relay device. However, one terminal device such as an electronic shelf label is installed for one type of product in a store, for example. In particular, in a large supermarket or the like that handles various types of products, it is necessary to turn off and on the power of a large number of terminal devices, which takes a lot of work. In addition, when there are a large number of terminal devices, there may be a terminal device that forgets to turn on the power when the store is opened.
According to the present embodiment, the terminal device c1 can turn off the management server a1 without maintaining the synchronization with the relay device b1 to increase power consumption, and the terminal device c1 can be turned off and off. It is possible to prevent an increase in the number of work steps to be turned on and the occurrence of forgetting work.
Further, according to the present embodiment, the relay device b1 generates and transmits an alternative synchronization signal including communication state information indicating a communication state with the management server a1. Thereby, the terminal device c1 can change the connection destination according to the communication state information included in the alternative synchronization signal. For example, communication state information whose communication state information is expected to take time to recover and communication state information that is expected to take less time to recover are distinguished and stored in the terminal device c1 in advance. If there is no relay device b1 whose communication state information is normal in step S304 of FIG. 11, it is confirmed whether or not there is a relay device 1b having expected communication state information that does not take time to recover. In this case, the process proceeds to step S307, and the terminal device c1 can change the connection destination to the relay device b1 whose communication state information is expected to take less time to recover. Further, it is possible to prevent the terminal device c1 from making a participation request to the relay device b1 whose communication state information is abnormal.
Moreover, according to this embodiment, the relay apparatus b1 produces | generates and transmits the synchronous signal containing the communication status information which shows a communication status. As a result, the terminal device c1 can detect a relay device in a normal communication state, change the connection destination to the detected relay device, and can reliably receive information from the management server a1.

  Note that a part of the relay device b1 and the terminal device c1 in the embodiment described above, for example, the communication state detection unit b111, the communication state bit generation unit b1121, the synchronization signal generation unit b1122, the relay device selection unit c1131, and the participation processing unit c1132. May be realized by a computer. In that case, the program for realizing the control function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read by a computer system and executed. Here, the “computer system” is a computer system built in the relay device b1 or the terminal device c1, and includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” is a medium that dynamically holds a program for a short time, such as a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line, In such a case, a volatile memory inside a computer system serving as a server or a client may be included, and the one holding a program for a certain period of time may be included. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  As described above, the embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to the above, and various design changes and the like can be made without departing from the scope of the present invention. It is possible to

A1, a1 ... management server (server), B1-B3, b1 ... relay device, C11-C1x, C21-C2y, Cm1-Cmz, c1, C1 ... terminal device (electronic shelf label device), S, S1 to Sn ... synchronization signal, D, D1 to Dn ... transmission data, b131 ... communication state storage unit, b111 ... communication state detection unit, b151 ... management server communication unit, b132 ... Relay device ID storage unit, b112 ... Signal control unit, b141 ... Synchronization unit, b121 ... Synchronization signal information storage unit, b161 ... Terminal device communication unit, b1121 ... Communication status bit Generation unit, b1122 ... Synchronization signal generation unit, b1123 ... Transmission data generation unit, c171 ... Relay device communication unit, c151 ... Display unit, c111 ... Reception unit, c141 ... Synchronization unit , C11 ... signal generator, c131 ... relay device information storage unit, C1131 ... relay device selecting unit, C1132 ... joining process component

Claims (5)

In the relay device that receives the synchronization signal including the synchronization information used for synchronization with the electronic shelf label device from the server and transmits it to the electronic shelf label device,
When the synchronization signal cannot be received from the server, an alternative synchronization signal including synchronization information of the synchronization signal is generated and transmitted to the electronic shelf label device at the synchronization timing.   The relay apparatus according to claim 1, wherein the substitute synchronization signal including communication state information indicating a communication state with the server is generated and transmitted. In the electronic shelf label device that receives from the relay device a synchronization signal that is a synchronization signal received from the server by the relay device and includes synchronization information used for synchronization with the relay device,
The relay device of the connection destination is changed according to communication state information included in an alternative synchronization signal including synchronization information of the synchronization signal and indicating communication state between the server and the relay device. Electronic shelf label device. An electronic shelf comprising: a server; an electronic shelf label device; and a relay device that receives a synchronization signal including synchronization information used for synchronization with the electronic shelf label device from the server and transmits the synchronization signal to the electronic shelf label device In the bill system,
The relay device is
When the synchronization signal cannot be received from the server, an alternative synchronization signal including synchronization information of the synchronization signal is generated and transmitted to the electronic shelf label device at the synchronization timing. In a relay method in a relay device that receives a synchronization signal including synchronization information used for synchronization with an electronic shelf label device from a server and transmits the synchronization signal to the electronic shelf label device,
When the relay device cannot receive the synchronization signal from the server, the relay device has a process of generating an alternative synchronization signal including synchronization information of the synchronization signal and transmitting it to the electronic shelf label device at the synchronization timing. Relay method.

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