JP2018157345A - Radio display system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio display system capable of suppressing occurrence of a state in which bias of the number of radio display terminals each belonging to an access point is unlikely to occur and batteries of the radio display terminals belonging to some access points are excessively consumed.SOLUTION: A radio display system 100 includes a plurality of wireless display terminals 30, a plurality of access points (AP) 20 communicating with the wireless display terminal, and a management server 10 that manages the wireless display terminal. Each of the wireless display terminals belongs to one of the APs and receives a signal transmitted from the AP to which the wireless display terminal belongs. The wireless display terminal includes a standby mode for waiting for reception of a command addressed to at least one wireless display terminal from an AP to which the wireless display terminal belongs and an active mode with power consumption larger than the standby mode for executing processing of determining whether the received command is addressed to the own terminal as an operation mode. When the bias of the number of the wireless display terminals belonging to the AP deviates from a predetermined range, the predetermined wireless display terminal executes the bias correction process.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless display system, and more specifically, to a wireless display system including a plurality of battery-driven wireless display terminals and a plurality of access points for communicating with the wireless display terminals.

  Conventionally, as in Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-140368), a plurality of battery-driven wireless display terminals, a plurality of access points that communicate with the wireless display terminals, and a management server that manages the wireless display terminals There is known a wireless display system comprising:

  The battery-driven wireless display terminal described in Patent Document 1 (Japanese Patent Laid-Open No. 2016-140368) generally has a problem of suppressing battery consumption. For example, in Patent Document 1 (Japanese Patent Laid-Open No. 2016-140368), it is determined whether or not a command is likely to be transmitted to a wireless display terminal according to ambient brightness, and it is determined that the possibility is low. In some cases, the wireless display terminal shifts to a low power consumption mode to suppress battery consumption.

  Incidentally, a wireless display terminal as described in Patent Document 1 (Japanese Patent Laid-Open No. 2016-140368) is configured to receive a command from one access point to which the wireless display terminal belongs. In addition, the wireless display terminal operates with a reduced power consumption time until the command is received. When the command is received, the wireless display terminal shifts to the wake-up state, and the received command is addressed to itself. If it is a command addressed to itself, processing such as storing information contained in the command in a memory is further performed.

  In such a wireless display system using a wireless display terminal, generally, as the number of wireless display terminals belonging to an access point increases, the wireless display terminal receives a command not addressed to itself, and whether the received command is addressed to itself. Opportunities to perform the process of determining whether or not are increased. In other words, in a wireless display system using such a wireless display terminal, the power consumption of the wireless display terminal belonging to the access point tends to increase as the number of wireless display terminals belonging to the access point increases. Therefore, when the number of wireless display terminals belonging to each of the plurality of access points is biased, there is a problem that the battery consumption of the wireless display terminals belonging to some access points is particularly likely to increase.

  In the wireless display system disclosed in Patent Document 1 (Japanese Patent Application Laid-Open No. 2016-140368), improvement in power consumption suppression of the wireless display terminal when it is determined that the possibility of a command being transmitted is low. . However, there is room for improvement with respect to the problem that the battery consumption of some of the wireless display terminals increases as the number of wireless display terminals belonging to the access point is biased.

  An object of the present invention is a wireless display system including a plurality of access points, in which the number of wireless display terminals belonging to each access point is not easily biased, and the batteries of wireless display terminals belonging to some access points An object of the present invention is to provide a wireless display system capable of suppressing the occurrence of a state where the power consumption is excessively consumed.

  A wireless display system according to a first aspect of the present invention includes a plurality of battery-driven wireless display terminals, a plurality of access points, and a management server. The access point communicates with the wireless display terminal. The management server is connected to the access point and manages the wireless display terminal. Each of the wireless display terminals belongs to one of a plurality of access points and receives a signal transmitted by the access point to which the wireless display terminal belongs. Each of the wireless display terminals has a standby mode and an active mode that consumes more power than the standby mode. The standby mode is an operation mode that waits for reception of a command addressed to at least one wireless display terminal from the access point to which the wireless display terminal belongs. The active mode is an operation mode in which at least processing for determining whether or not a command received from the access point to which the wireless display terminal belongs is addressed to itself is performed. When the deviation of the number of wireless display terminals belonging to each of the plurality of access points deviates from a predetermined range, the predetermined wireless display terminal executes the deviation elimination processing.

  Here, the command having the wireless display terminal as a destination means an instruction for causing the destination wireless display terminal to execute various processes. Here, when the deviation of the number of wireless display terminals belonging to each of the plurality of access points deviates from the predetermined range, it is determined that the number of wireless display terminals belonging to some access points is excessive. It is a state to be done.

  When the wireless display terminal receives a command from the access point to which the wireless display terminal belongs, the wireless display terminal performs at least processing to determine whether the command is addressed to the wireless display terminal. Switch to active mode. Therefore, assuming that commands for each wireless display terminal are transmitted with the same frequency to all wireless display terminals, the more the number of wireless display terminals that belong to a certain access point, This increases the chance that the operation mode of the wireless display terminals belonging to is shifted from the standby mode to the active mode, and the consumption of the batteries of these wireless display terminals increases.

  In contrast, in the wireless display system according to the first aspect, when the deviation of the number of wireless display terminals belonging to each of the plurality of access points deviates from a predetermined range, the predetermined wireless display terminal executes the bias elimination processing. To do. Therefore, it is possible to suppress the occurrence of a state where the batteries of some wireless display terminals are excessively consumed.

  A wireless display system according to a second aspect of the present invention is the wireless display system according to the first aspect, and when the deviation of the number of wireless display terminals belonging to each of a plurality of access points deviates from a predetermined range, The access point having the largest number of wireless display terminals belonging to at least transmits a distributed command related to execution of the bias elimination processing to at least a part of the wireless display terminals belonging to the access point.

  Here, it is possible to eliminate the bias in the number of wireless display terminals belonging to a plurality of access points using a distributed command transmitted from the access point.

  A wireless display system according to a third aspect of the present invention is the wireless display system according to the second aspect, wherein the access point is at least a part of the wireless display terminals belonging to the access point according to an instruction from the management server. A distributed command related to execution of the bias elimination processing is transmitted to the addressee.

  Here, since the wireless display terminal executes the bias elimination process in response to an instruction from the management server, the management server can grasp whether or not the bias elimination process is being executed on the wireless display terminal. Therefore, the management server can avoid sending another command addressed to the wireless display terminal during execution of the process for eliminating the bias of the wireless display terminal.

  A wireless display system according to a fourth aspect of the present invention is the wireless display system according to the second aspect or the third aspect, wherein the distributed command is an access point that transmits the distributed command to all access points belonging to the access point. This is a global command for transmitting a wireless display terminal as a destination.

  Here, since the distributed command related to the execution of the bias elimination processing is a global command for all wireless display terminals belonging to the access point of the transmission source, there is no need to transmit the distributed command multiple times. Therefore, unlike the case where a wireless display terminal individually transmits a distributed command to each of a plurality of wireless display terminals, the wireless display terminal receives a signal including a distributed command addressed to another wireless display terminal, and is unnecessary. It is possible to prevent the transition to the active mode.

  A wireless display system according to a fifth aspect of the present invention is the wireless display system according to any one of the second to fourth aspects, wherein the distributed command includes information on a threshold value of the radio field intensity. The wireless display terminal that has received the distributed command executes the bias elimination processing when the strength of the radio wave received from the access point to which it belongs is below the threshold value.

  When the radio wave intensity received from the access point is relatively strong, a reception error of a signal transmitted from the access point is relatively unlikely to occur in the wireless display terminal. Therefore, it is difficult for the wireless display terminal belonging to the access point to operate in the active mode many times and the battery is exhausted due to the retransmission of the command accompanying the reception error.

  Here, a wireless display terminal having a relatively strong radio field intensity received from the access point does not execute the bias elimination process, and only a wireless display terminal having a relatively weak radio field intensity received performs the bias elimination process. Therefore, it is easy to realize a state in which the battery of the wireless display terminal is hardly consumed as a whole system.

  A wireless display system according to a sixth aspect of the present invention is the wireless display system according to any of the second to fifth aspects, wherein the access point periodically transmits a beacon. When the access point transmits the distributed command, the access point transmits a beacon including the distributed command.

  Here, a distributed command can be transmitted using a beacon transmitted periodically.

  A wireless display system according to a seventh aspect of the present invention is the wireless display system according to any one of the first to sixth aspects, wherein the bias elimination processing searches for an access point with which the wireless display terminal can communicate, This is a process for determining a communicable access point as an affiliation destination.

  Here, as the bias elimination process, a process of searching for an access point with which the wireless display terminal can communicate and determining the affiliation destination is performed, so the deviation of the number of wireless display terminals belonging to the access point can be eliminated. .

  A wireless display system according to an eighth aspect of the present invention is the wireless display system according to the seventh aspect, wherein the wireless display terminal determines whether or not communication with an access point is possible for a plurality of access points as a bias elimination process. Judgment is performed in a random order, and processing is performed to determine the access point that is first determined to be communicable as the affiliation destination.

  Here, the affiliation destinations are easily distributed, and the bias of the number of wireless display terminals belonging to the access points is easily eliminated.

  A wireless display system according to a ninth aspect of the present invention is the wireless display system according to the seventh aspect, in which the wireless display terminal targets an access point other than the access point to which the wireless access point has belonged so far as a bias elimination process. The wireless display terminal searches for an access point with which the wireless display terminal can communicate, and performs processing for determining an access point with which the wireless display terminal can communicate as an affiliate.

  Here, it is easy to reduce the number of wireless display terminals belonging to the access points to which they belonged.

  A wireless display system according to a tenth aspect of the present invention is the wireless display system according to the first aspect, wherein the access point is periodically related to the number of belongings related to the number of wireless display terminals belonging to the access point. Send a beacon containing information. The wireless display terminal performs a bias elimination process based on the affiliation number related information.

  Here, since the bias elimination processing is executed using a beacon that is periodically transmitted, the state in which the number of wireless display terminals belonging to a plurality of access points is biased is easily eliminated in a short time. .

  In the wireless display system according to the present invention, when the deviation of the number of wireless display terminals belonging to each of the plurality of access points deviates from a predetermined range, the predetermined wireless display terminal executes the bias elimination process. Therefore, it is possible to suppress the occurrence of a state where the batteries of some wireless display terminals are excessively consumed.

1 is an overall schematic diagram of a wireless display system according to an embodiment of the present invention. FIG. 2 is a diagram depicting an arrangement example of wireless display terminals of the wireless display system of FIG. 1. It is a figure which shows the external appearance of the wireless display terminal of the wireless display system of FIG. It is a block diagram which shows schematic structure of the radio | wireless display terminal of FIG. 6 is a flowchart for explaining an example of a method for determining an access point to which the wireless display terminal in FIG. 4 belongs (random selection of an access point to which the wireless display terminal belongs). FIG. 5 is a flowchart for explaining another example of a method for determining an access point to which the wireless display terminal of FIG. 4 belongs (selection of an access point to which the wireless display device belongs based on the number of wireless display devices belonging to the access point). 6 is a flowchart for explaining an operation when a distributed command is received by the wireless display terminal of FIG. It is a block diagram which shows schematic structure of the management server of the radio | wireless display system of FIG. 3 is a flowchart for explaining distributed command transmission processing of an access point in the wireless display system of FIG. 1.

  Hereinafter, a wireless display system 100 according to an embodiment of the wireless display system of the present invention will be described.

  The following embodiments are merely examples, and do not limit the contents of the wireless display system according to the present invention. The wireless display system of the following embodiments can be appropriately changed within a range not inconsistent with the gist of the invention.

(1) Overall Configuration The wireless display system 100 includes a plurality of wireless display terminals 30 and a management server that manages the wireless display terminals 30 displays various information on each of the wireless display terminals.

  The wireless display system 100 mainly includes a plurality of battery-driven wireless display terminals 30, a plurality of access points 20, and a management server 10 (see FIG. 1). The number of wireless display terminals 30 and access points 20 is not limited to the number depicted in FIG. Although not limited thereto, one wireless display system 100 may include a large number of wireless display terminals 30, for example, thousands or more.

  Here, the wireless display system 100 is used in a store such as a supermarket or a convenience store. However, the wireless display system according to the present invention may be used outside a store. For example, the wireless display system may be used in a warehouse, a factory, a hospital, or the like.

  The wireless display terminal 30 is a portable device. The wireless display terminal 30 can communicate with the access point 20 by radio waves. The wireless display terminal 30 can be connected to the access point 20 via a wireless LAN. Note that the wireless LAN is an example of a wireless technology used for wireless communication, and the wireless display terminal 30 and the access point 20 may be configured to be able to wirelessly communicate with other wireless technologies.

  The wireless display terminal 30 in the wireless display system 100 is a so-called electronic shelf label. The wireless display terminal 30 is arranged corresponding to each of the plurality of products P handled in the store at a store floor of the store. For example, the wireless display terminal 30 is disposed in the vicinity of the corresponding product P (see FIG. 2). Then, the wireless display terminal 30 displays product information regarding the corresponding product P. The product information related to the product P includes, for example, information such as the name and price of the product P (see FIG. 3). The wireless display terminal 30 may be attached to a moving body (article or person) that moves in a facility that uses the wireless display system 100.

  The access point 20 is connected to the management server 10 via a LAN cable 40 so that communication is possible. The access point 20 can communicate with the wireless display terminal 30 wirelessly.

  In the wireless display system 100, the wireless display terminal 30 determines one of a plurality of access points 20 as an affiliation destination and performs communication with the access point 20 to which the wireless display terminal 30 belongs. While the wireless display terminal 30 belongs to a certain access point 20, the wireless display terminal 30 receives a signal transmitted from the access point 20 and does not receive a signal transmitted from another access point 20. When the affiliated access point 20 is changed, the wireless display terminal 30 communicates with the affiliated access point 20 after the affiliation change. The management server 10 stores the access point 20 to which each wireless display terminal 30 belongs as information. Specifically, the management server 10 associates the device ID for identifying the wireless display terminal 30 with the access point ID for identifying the access point 20 of the access point 20 to which the wireless display terminal 30 belongs. I remember. Therefore, when the management server 10 transmits a command with a certain wireless display terminal 30 as a destination, the management server 10 can select which access point 20 should transmit the command. The determination of the affiliation destination of the wireless display terminal 30 to the access point 20 and the change of the affiliation destination will be described later.

  The arrangement and the number of access points 20 are designed so that the wireless display terminal 30 installed in a store floor of the store can wirelessly communicate with any of the access points 20 while suppressing the number of access points 20. . The access points 20 are attached to the ceiling of a store, for example, with an interval.

  Each access point 20 performs communication using a predetermined channel (frequency band). The access point 20 uses a plurality of channels (for example, 14 types of channels). Each access point 20 is assigned a channel so as not to cause radio wave interference with the access points 20 arranged around the access point 20.

  The access point 20 transmits a command addressed to the wireless display terminal 30 sent from the management server 10 to the wireless display terminal 30. Further, the access point 20 receives the ACK signal transmitted from the wireless display terminal 30 and transmits it to the management server 10.

  Further, the access point 20 receives a probe request transmitted when the wireless display terminal 30 searches for the access point 20 to which the wireless display terminal 30 belongs, and transmits a probe response as a response to the request to the wireless display terminal 30. The access point 20 receives a connection request transmitted when the wireless display terminal 30 requests to belong to the access point 20 and transmits a connection response as a response to the connection request to the wireless display terminal 30.

  The access point 20 transmits a signal called a beacon at a predetermined interval (for example, every 20 seconds). The beacon is used to determine whether or not the wireless display terminal 30 belonging to the access point 20 that transmits the beacon is in a state where it can communicate with the access point 20 to which it belongs. In addition, the access point 20 may transmit a beacon including information for notifying transmission of a command. The wireless display terminal 30 can determine whether or not a command is transmitted from the access point 20 following the beacon depending on whether or not the beacon includes information for notifying the transmission of the command.

  The management server 10 is a general computer that manages the wireless display terminal 30. The management server 10 is arranged, for example, in a store backyard. The management server 10 stores product information to be displayed on the wireless display terminal 30. The management server 10 transmits various commands to the wireless display terminal 30 via the access point 20.

  Note that the commands transmitted by the management server 10 include individual commands and global commands.

  The individual command is a command that specifies the wireless display terminal 30 that executes the command. The individual command is added with the device ID of the wireless display terminal 30 that executes the command, in other words, the command transmission destination, as information. For example, when the display change of a certain wireless display terminal 30 becomes necessary, the management server 10 generates a command for causing the wireless display terminal 30 to change the display contents, and sets the device ID of the wireless display terminal 30. Send the included command (individual command).

  On the other hand, the global command is a command destined for all wireless display terminals 30 belonging to the access point 20 that transmits the command. When the access point 20 wants to give instructions to the wireless display terminals 30 to which the access point 20 belongs all at once, the command is efficiently transmitted to a large number of wireless display terminals 30 by using a global command. can do.

(2) Detailed Configuration The wireless display terminal 30 and the management server 10 of the wireless display system 100 will be described in detail below.

(2-1) Wireless Display Terminal As shown in FIG. 4, the wireless display terminal 30 mainly includes a display unit 31, a communication unit 32, a storage unit 33, a control unit 34, and a battery 35.

(2-1-1) Display Unit The display unit 31 is a screen for displaying information (such as product information transmitted from the management server 10) stored in the storage unit 33 (see FIG. 3).

  The display unit 31 preferably uses various types of electronic paper such as a microcapsule method, an electronic powder fluid method, a liquid crystal method, an electrowetting method, and an electrophoresis method. That is, the display unit 31 is, for example, a dot matrix nonvolatile display unit including a plurality of pixels arranged in a matrix. By using electronic paper for the display unit 31, it is possible to hold the display content of the display unit 31 without consuming power or suppressing power consumption.

  Note that the display unit 31 may not use electronic paper, and may be a liquid crystal display, for example.

(2-1-2) Communication Unit The communication unit 32 is a functional unit that performs a wireless communication function with the access point 20.

  Although not shown, the communication unit 32 mainly includes an antenna for performing wireless communication with the access point 20, a wireless communication circuit, a baseband LSI, and the like.

(2-1-3) Storage Unit The storage unit 33 includes a memory such as a RAM, a ROM, and a flash memory. Various types of information are stored in the storage unit 33.

  For example, the storage unit 33 stores programs used by the control unit 34, programs defining communication protocols used for communication with the access point 20, and the like.

  The storage unit 33 has a plurality of storage areas for storing various types of information. The plurality of storage areas include a device ID storage area 33a and an input information storage area 33b.

  In the device ID storage area 33a, a device ID unique to each wireless display terminal 30 is stored.

  Information received by the communication unit 32 from the management server 10 via the access point 20 is stored in the input information storage area 33b. For example, the product information (particularly image data of product information) transmitted from the management server 10 is stored in the input information storage area 33b.

(2-1-4) Control unit The control unit 34 mainly includes a CPU. The control unit 34 is electrically connected to the display unit 31, the communication unit 32, the storage unit 33, and the battery 35 (see FIG. 4).

  The control unit 34 controls the operation of each component of the wireless display terminal 30 by executing the program stored in the storage unit 33. The control unit 34 performs the following control, for example.

(2-1-4-1) Determination of belonging access point When the access point 20 to which each wireless display terminal 30 belongs has not yet been determined, such as when the operation of the wireless display system 100 is started, the control unit 34 A search is made for a communicable access point 20, and one of the communicable access points 20 is determined as an affiliation destination.

  For example, the controller 34 determines the access point 20 to which it belongs using the following method (A) or (B).

(A) Random Selection of Affiliated Access Point A determination process of the assigned access point 20 using the random selection method of the assigned access point 20 will be described with reference to the flowchart of FIG.

  The plurality of access points 20 use a plurality of channels (for example, 14 types of channels) as described above. When using the random selection method of the access point 20 to which the user belongs, the control unit 34 randomly selects one channel as a communication channel from the plurality of channels (step S1).

  Next, the control unit 34 transmits a probe request from the communication unit 32 (step S2). The probe request is a signal for confirming whether or not there is an access point 20 that performs communication using the channel selected in step S <b> 1 within the reach of the radio wave transmitted from the communication unit 32. That is, by transmitting a probe request from the communication unit 32, the access point 20 that can communicate is searched.

  Next, the control unit 34 determines whether or not the communication unit 32 has received a probe response within a predetermined time (step S3). If the communication unit 32 receives a probe response within a predetermined time, the process proceeds to step S4. On the other hand, when the communication unit 32 does not receive the probe response within the predetermined time, the process returns to step S1.

  In step S4, the control unit 34 compares the radio field intensity of the signal received by the communication unit 32 with a predetermined threshold in response to the probe request. The predetermined threshold value is a value of the radio wave intensity at which it can be determined that the wireless display terminal 30 and the access point 20 can communicate with each other. If the radio wave intensity is greater than or equal to the threshold, the process proceeds to step S5. If the radio wave intensity is less than the threshold, the process returns to step S1.

  In step S5, the control unit 34 selects the access point 20 of the probe response transmission source (the access point 20 using the channel selected in step S1) as the affiliation destination.

  Next, in step S <b> 6, the control unit 34 transmits a connection request including the device ID in the information from the communication unit 32. And the communication part 32 receives the connection response with respect to a connection request (step S7). In this way, the determination process of the access point 20 to which the wireless display terminal 30 belongs is completed.

  The connection request received by the access point 20 is also transmitted to the management server 10 together with the access point ID of the access point 20 that has received the connection request. As a result, the management server 10 can grasp to which access point 20 a certain wireless display terminal 30 (wireless display terminal 30 with a certain device ID) belongs.

  In the flowchart of FIG. 5, when the process returns from step S3 or step S4 to step S1, it has already been selected (already connected) in the next step S1 in order to eliminate waste of the process. It is preferable that a channel is selected at random from other channels.

(B) Selection of affiliation access point based on number of wireless display terminals belonging to access point Based on number of wireless display terminals 30 already belonging to access point 20 (hereinafter simply referred to as number of affiliations) A determination process of the affiliated access point 20 using selection of the affiliated access point 20 will be described with reference to the flowchart of FIG.

  Here, the control unit 34 uses all the channels used by the access point 20 in order, transmits a probe request from the communication unit 32, and attempts to receive a probe response thereto (communication access point). 20). In addition, the control unit 34 compares the radio wave intensity of the response received by the communication unit 32 with respect to the probe request with a predetermined threshold value (step S11). The predetermined threshold value is a value of the radio wave intensity at which it can be determined that the wireless display terminal 30 and the access point 20 can communicate with each other. Here, when each access point 20 transmits a probe response, the number of wireless display terminals 30 belonging to the access point 20 (the number of belongings) distributed from the management server 10 is sent together with the probe response. Shall be sent.

  Next, in step S12, the control unit 34 extracts a channel whose radio wave intensity is greater than or equal to the threshold value as a result of the process in step S11. Note that the control unit 34 excludes channels from which no probe response has been received from extraction targets.

  Next, in step S13, the control unit 34 selects the access point 20 using the channel having the smallest affiliation number among the channels extracted in step S12 as the affiliation destination.

  Next, the control unit 34 transmits a connection request including the device ID to the access point 20 selected from the communication unit 32 using the channel used by the selected access point 20 (step S14). And the communication part 32 receives the connection response with respect to a connection request (step S15). In this way, the determination process of the access point 20 to which the user belongs is completed.

  The connection request received by the access point 20 is also transmitted to the management server 10 together with the access point ID of the access point 20 that has received the connection request. As a result, the management server 10 can grasp to which access point 20 a certain wireless display terminal 30 (wireless display terminal 30 with a certain device ID) belongs.

  For example, by determining the access point 20 to which the wireless display terminal 30 belongs using the method (A) or (B) as described above, the number of wireless display terminals 30 belonging to the access point 20 is biased. Can be suppressed to some extent.

  In addition, in the determination process of the access point 20 to which the affiliation belongs using the above method (B), all the radio display terminals 30 transmit probe requests for all channels and try to receive probe responses (all channels are changed). Search). Therefore, when an access point having a radio wave intensity equal to or greater than a threshold is found, the access point 20 is determined as the affiliation destination. Compared to the determination process of the affiliation access point 20 using the method (A), The time until the affiliated access point 20 is determined tends to be long. That is, when the above method (B) is used, it takes a long time to stabilize the wireless display system 100. Further, when the above method (B) is used, the processing load on the wireless display terminal 30 increases and the power consumption tends to increase.

  Therefore, it is particularly preferable that the control unit 34 determines the access point 20 to which the wireless display terminal 30 belongs using the method (A).

  The wireless display terminal 30 determined by the affiliated access point 20 using the method as described above is in a state where it cannot communicate with the affiliated access point 20, or until a bias elimination process described later is executed. Communication is performed with the access point 20 determined as the affiliation destination. Each wireless display terminal 30 receives a signal (beacon or command) transmitted by the access point to which it belongs.

  Whether the wireless display terminal 30 cannot communicate with the access point 20 to which the wireless display terminal 30 belongs is, for example, that the communication unit 32 cannot continuously receive a beacon transmitted at a predetermined interval by the access point 20 a predetermined number of times. It is judged by whether or not. In this case, when the communication unit 32 cannot continuously receive the beacon for a predetermined number of times, it is determined that the wireless display terminal 30 cannot communicate with the access point 20 to which the wireless display terminal 30 belongs. If it is determined that the wireless display terminal 30 cannot communicate with the access point 20 to which it belongs, the wireless display terminal 30 re-executes the process for determining the access point 20 as described above.

  Here, a case has been described in which the wireless display terminal 30 transmits a probe request (performs so-called active scan), searches for a communicable access point 20, and determines the access point 20 to which it belongs. However, the search method for the affiliated access point 20 is not limited to the active scan, but may be a search using so-called passive scan.

  For example, specifically, the wireless display terminal 30 may randomly select a channel used for communication and try to receive a beacon transmitted by the access point 20 at regular intervals, as in (A) above. . And the control part 34 may determine the access point 20 which uses the channel as a affiliation at the time of the channel whose electric field intensity of the received beacon is more than a predetermined threshold.

(2-1-4-2) Switching of operation mode and operation in each operation mode The control unit 34 of the wireless display terminal 30 determined by the access point 20 to which the user belongs is mainly operated in two modes: a standby mode and an active mode. The wireless display terminal 30 is operated in the mode.

  The active mode is an operation mode that consumes more power than the standby mode. This is because in the standby mode, the state of the wireless display terminal 30 is mainly the sleep state, whereas in the active mode, the state of the wireless display terminal 30 is in the wake-up state.

  In the sleep state, the control unit 34 controls a semiconductor switch or a relay (not shown) to stop the power supply from the battery 35 to the communication unit 32, and the power supply from the battery 35 to the control unit 34 is also minimal. It is a state that is suppressed to the limit. The wireless display terminal 30 in the sleep state cannot receive a signal even if a signal is transmitted from the access point 20.

  On the other hand, in the wake-up state, the control unit 34 controls a semiconductor switch or a relay (not shown) to supply power from the battery 35 to the communication unit 32, and the power supply restriction from the battery 35 to the control unit 34 is also released. State. In the wake-up state, the wireless display terminal 30 can receive a signal transmitted from the access point 20.

  The standby mode is an operation mode that waits for reception of a command addressed to at least one wireless display terminal from the access point 20 to which the wireless display terminal 30 belongs. Most of the states of the wireless display terminal 30 in the standby mode are in the sleep state. When the operation mode of the wireless display terminal 30 is the standby mode, the control unit 34 wakes up the wireless display terminal 30 for a very short time in accordance with the timing of the beacon transmitted by the access point 20 to which the wireless display terminal 30 belongs. Transition to the state. For example, the control unit 34 changes the state of the wireless display terminal 30 from the sleep state to the wake-up state for 100 milliseconds in 20 seconds.

  The control unit 34 displays the wireless display when the beacon received when the wireless display terminal 30 is shifted to the wake-up state during the operation in the standby mode includes information for notifying the transmission of the command. The operation mode of the terminal 30 is changed to the active mode. When the operation mode of the wireless display terminal 30 is changed to the active mode, the control unit 34 maintains the state of the wireless display terminal 30 in the wake-up state. Then, the control unit 34 receives a command transmitted from the access point 20 to which it belongs following the beacon including information for notifying the transmission of the command.

  Further, the control unit 34 executes processing for determining whether or not the received command is a command addressed to itself. Specifically, the control unit 34 determines whether the received command is a global command or an individual command. If the received command is a global command, the control unit 34 determines that the command is addressed to itself. On the other hand, if the received command is an individual command, the control unit 34 compares the device ID included in the received individual command with the device ID stored in the device ID storage area 33a. Then, the control unit 34 determines that the command is addressed to itself when both device IDs match, and is not addressed to itself when both device IDs do not match.

  When determining that the command is addressed to itself, the control unit 34 further executes processing according to the command.

  For example, in the case of a distributed command that is a type of received global command, the control unit 34 determines whether or not it is necessary to execute bias cancellation processing, and when it is determined that it is necessary, the bias cancellation processing Execute. The process of the control unit 34 when the received command is a distributed command will be described later.

  Further, for example, when the received command is an individual command for processing the display change of the display unit 31 addressed to itself, the control unit 34 sends an ACK signal from the communication unit 32 to the access point 20 to which it belongs. Send. Further, when the received command is a command for instructing a change in the product information displayed on the display unit 31, the control unit 34 stores the product information (image data of the product information) included in the command. The information is stored in the input information storage area 33b of the unit 33, and the display content of the display unit 31 is changed to the received product information. Thereafter, the control unit 34 shifts the operation mode of the wireless display terminal 30 to the standby mode.

  In addition, when the control unit 34 determines that the received command is not a command addressed to itself, the control unit 34 shifts the operation mode of the wireless display terminal 30 to the standby mode.

(2-1-4-3) Operation at the time of receiving a distributed command The processing (operation of the wireless display terminal 30) of the control unit 34 at the time of receiving a distributed command will be described with reference to the flowchart of FIG.

  First, the distributed command will be briefly described. Note that when the distributed command is transmitted from the access point 20 will be described later.

  The distributed command is a command related to execution of the bias elimination processing. The distributed command is a command for instructing at least a part of the wireless display terminal 30 that has received the distributed command to execute the bias elimination processing. The dispersion command preferably includes information on a threshold value of the radio wave intensity. The threshold value of the radio wave intensity may be a fixed value or a value determined by the management server 10 according to a predetermined standard when transmitting the distributed command.

  When the communication unit 32 receives the distributed command, the control unit 34 determines that the received radio wave intensity of the distributed command (the intensity of the radio wave received from the access point 20 to which it belongs) sets the threshold value of the radio wave intensity included in the distributed command. It is determined whether it is below (step S21). When the received radio wave intensity of the distributed command is below the threshold value of the radio wave intensity included in the distributed command, the process proceeds to step S22. On the other hand, when the received radio wave intensity of the distributed command is equal to or higher than the threshold value of the radio wave intensity included in the distributed command, the control unit 34 shifts the operation mode of the wireless display terminal 30 to the standby mode, and The process at the time of reception ends.

  In step S22, the wireless display terminal 30 executes a bias elimination process. The bias elimination process is a process of searching for an access point 20 with which the wireless display terminal 30 can communicate, and determining the access point 20 with which communication is possible as an affiliate. That is, the bias elimination process is the same process as the determination of the access point to which the above (2-1-4-1) belongs.

  For example, in step S <b> 22, the control unit 34 determines the affiliated access point 20 by using the above-described (A) random selection method of the affiliated access point as the bias elimination process. That is, in step S22, the control unit 34 determines whether or not communication with the access point 20 is possible in a random order with respect to the plurality of access points 20, and the access point 20 determined to be able to communicate first is assigned to The process to decide is performed.

  Alternatively, in step S22, the control unit 34 uses the wireless display terminal as a target for the access points 20 other than the access point 20 that belonged so far (that is, the access point 20 that transmitted the distributed command) as the bias elimination process. Is searched for the access point 20 that can communicate, and the access point that can communicate is determined to belong to. Note that the control unit 34 randomly determines whether or not communication with the access point 20 is possible for the access points 20 other than the access point 20 to which the control unit 34 has belonged so far. It is particularly preferable to perform the process of determining the access point 20 that is determined in order and first determined to be communicable as the affiliation destination.

  In the present embodiment, the distributed command includes information on the threshold value of the radio field intensity, but is not limited to this. The distributed command may instruct execution of the bias elimination processing to all the wireless display terminals 30 that have received the distributed command from the access point 20 to which they belong.

(2-1-5) Battery The battery 35 supplies power to each unit of the wireless display terminal 30. The battery 35 is, for example, a lithium battery.

(2-2) Management Server The management server 10 is a computer that manages the wireless display terminal 30. The management server 10 is connected to the access point 20 via the LAN cable 40 and transmits various commands to the wireless display terminal 30.

  The management server 10 mainly includes a server communication unit 11, a server output unit 12, a server input unit 13, a server storage unit 14, and a server control unit 15 (see FIG. 8).

(2-2-1) Server Communication Unit The server communication unit 11 mainly includes a communication circuit that enables communication between the management server 10 and the access point 20 (not shown). The server communication unit 11 communicates with a plurality of access points 20 via the LAN cable 40.

  The management server 10 may be configured to be able to communicate with devices outside the wireless display system 100 via the server communication unit 11. For example, the management server 10 is connected to a server and a store controller of a POS system installed in a store together with the wireless display system 100 via the server communication unit 11 in order to acquire product information to be displayed on the wireless display terminal 30. Preferably it is.

(2-2-2) Server Output Unit The server output unit 12 serves as an interface for displaying information to the system administrator. The server output unit 12 includes, for example, a liquid crystal display.

(2-2-3) Server Input Unit The server input unit 13 is an example of an input unit. The server input unit 13 serves as an interface through which an instruction from the system administrator is input. The server input unit 13 includes, for example, a keyboard and a mouse.

(2-2-4) Server storage unit The server storage unit 14 includes a ROM, a RAM, a hard disk, and the like.

  The server storage unit 14 stores, for example, a program executed by the server control unit 15 and a program in which a communication protocol used for communication with other devices is defined.

  The server storage unit 14 has a plurality of storage areas for storing various types of information. The information stored in the server storage unit 14 includes a product master storage area 14a and a terminal master storage area 14b (see FIG. 8).

(2-2-4-1) Product Master Storage Area The product master storage area 14a is information relating to the product P handled by the wireless display system 100. The information regarding the product P includes, for example, a product name, a sales price, a sales unit price, a discount rate, and the like. Further, the information related to the product P may include information mainly used by store employees such as sales volume and inventory quantity. In the product master storage area 14a, product information is stored for each product ID (barcode information) of the product P. The contents of the merchandise master storage area 14a are updated when the server communication unit 11 receives information from an external device (for example, a POS system (not shown)) or when the server input unit 13 receives input of information.

(2-2-4-2) Terminal Master Storage Area The terminal master storage area 14b is information that associates the device ID for identifying the wireless display terminal 30 with the product ID of the product P. By storing the device ID and the product ID in association with each other in the terminal master storage area 14b, the wireless display terminal 30 and the product P corresponding to the wireless display terminal 30 are linked. In other words, by storing the device ID and the product ID in association with each other in the terminal master storage area 14b, it is specified which product P should be displayed on a certain wireless display terminal 30. The device ID and the product ID are associated with each other by, for example, an operator such as a store clerk performing a link operation using a handy terminal (not shown).

  In the terminal master storage area 14b, the device ID of the wireless display terminal 30 and the access point ID of the access point 20 to which the wireless display terminal 30 belongs are stored in association with each other. By storing the device ID and the access point ID in association with each other in the terminal master storage area 14b, it is specified from which access point 20 the command should be transmitted when a command is transmitted to a certain wireless display terminal 30. The

  The management server 10 receives a connection request transmitted from the wireless display terminal 30 to the access point 20 from the access point 20 together with the access point ID of the access point 20, so that the device ID, the access point ID, Can be associated.

(2-2-5) Server Control Unit The server control unit 15 controls the operation of the management server 10 by executing a program stored in the server storage unit 14. Further, the server control unit 15 controls the operation of the wireless display terminal 30 by controlling the operation of the management server 10.

  For example, when the server communication unit 11 receives the device ID of the electronic shelf label to be associated and the product ID of the product P transmitted from the handy terminal (not shown), the server control unit 15 receives the device ID and the product ID. Are stored in the terminal master storage area 14b.

  For example, when the display change of a certain wireless display terminal 30 is necessary, the server control unit 15 instructs the display change including the image data of the display content and the device ID of the wireless display terminal 30 that needs the display change in the information. Generate commands to Then, the server control unit 15 refers to the terminal master storage area 14b and transmits the generated command to the wireless display terminal via the access point 20 having the access point ID associated with the device ID of the transmission destination wireless display terminal 30. 30. Note that the display change of the wireless display terminal 30 is necessary when, for example, the contents of the product master storage area 14a or the association between the device ID and the product ID stored in the terminal master storage area 14b is updated. is there.

  Further, the server control unit 15 determines whether or not the deviation of the number of the wireless display terminals 30 belonging to each of the plurality of access points 20 is out of a predetermined range. When the deviation of the number of wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from a predetermined range (hereinafter, sometimes referred to as occurrence of deviation), the server control unit 15 A distributed command is transmitted from the access point 20. In particular, when the bias occurs, the server control unit 15 performs the bias elimination process from the access point 20 having at least the largest number of wireless display terminals 30 belonging to at least a part of the wireless display terminals 30 belonging to the access point 20. Command and send distributed commands related to execution. That is, in response to an instruction from the management server 10, the access point 20 transmits a distributed command related to execution of the bias elimination process to at least a part of the wireless display terminals 30 belonging to the access point 20.

  Note that the state in which the number of wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from a predetermined range (when the unevenness occurs) is, for example, a wireless display terminal 30 belonging to a certain access point 20. This means that the number of is greater than a predetermined value.

  Further, the occurrence of bias means, for example, a state where the ratio of the wireless display terminals 30 belonging to a certain access point 20 is larger than a predetermined ratio with respect to the total number of wireless display terminals 30.

  Also, when a bias occurs, for example, when the standard deviation value of the number of wireless display terminals 30 belonging to each of the access points 20 is larger than a predetermined value, the deviation of the number of wireless display terminals 30 deviates from a predetermined range. It is determined that it is in a state.

  The distributed command transmission process from the access point 20 will be described with reference to the flowchart of FIG.

  Since the bias elimination processing requires a search for access points 20 that can be communicated by the wireless display terminal 30, particularly when the number of wireless display terminals 30 is large, until the wireless display system 100 is stabilized (all wireless display A certain amount of time is required until the access point 20 to which the terminal 30 belongs is determined. For this reason, it is preferable that the bias elimination process is not executed at a timing when there is a high possibility that a display change or the like of the wireless display terminal 30 is necessary. Therefore, the management server 10 determines whether or not the present time is a predetermined timing (for example, a predetermined time such as 3 o'clock at midnight when work in the store is not performed) (step S31). The process of step S31 is repeatedly performed until it is determined that the predetermined timing is reached. Note that step S31 can be omitted from the processing flow.

  When it is determined in step S31 that the predetermined timing is reached, the server control unit 15 refers to the terminal master storage area 14b, and determines the number of wireless display terminals 30 belonging to each of the plurality of access points 20. It is determined whether or not the deviation deviates from a predetermined range (step S32). For example, the server control unit 15 refers to the terminal master storage area 14b to grasp the number of wireless display terminals 30 belonging to the access point 20, and whether or not there is an access point 20 whose number is greater than a predetermined value. Determine. If there are access points 20 to which the number of wireless display terminals 30 belonging is larger than a predetermined value, the deviation of the number of wireless display terminals 30 belonging to each of the plurality of access points 20 is out of the predetermined range. Determine and proceed to step S33. On the other hand, when the number of wireless display terminals 30 belonging to the access point 20 is less than or equal to a predetermined value, the number of wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from the predetermined range. If it is not determined, the process returns to step S31. Note that the server control unit 15 may determine whether or not the deviation of the number of the wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from a predetermined range by another method. For example, when the ratio of the number of wireless display terminals 30 belonging to a certain access point 20 to the total number of wireless display terminals 30 is greater than a predetermined ratio, the server control unit 15 or the wireless belonging to each of the access points 20 When the standard deviation value of the number of display terminals 30 is larger than a predetermined value, it may be determined that the deviation is out of the predetermined range.

  In step S33, the server control unit 15 determines that the number of wireless display terminals 30 to which the server belongs is excessive (for example, the number of wireless display terminals 30 to which it belongs exceeds the predetermined value). Instructs the command to be sent. Then, it returns to step S31.

(3) Features (3-1)
The wireless display system 100 according to the embodiment includes a plurality of battery-driven wireless display terminals 30, a plurality of access points 20, and a management server 10. The access point 20 communicates with the wireless display terminal 30. The management server 10 is connected to the access point 20 and manages the wireless display terminal 30. Each of the wireless display terminals 30 belongs to one of the plurality of access points 20 and receives a signal transmitted by the access point 20 to which the wireless display terminal 30 belongs. Each of the wireless display terminals 30 has a standby mode and an active mode that consumes more power than the standby mode as operation modes. The standby mode is an operation mode that waits for reception of a command addressed to at least one wireless display terminal 30 from the access point 20 to which the wireless display terminal 30 belongs. The active mode is an operation mode in which at least processing for determining whether a command received from the access point 20 to which the wireless display terminal 30 belongs is addressed to itself is executed. When the deviation of the number of the wireless display terminals 30 belonging to each of the plurality of access points 20 has deviated from the predetermined range, the predetermined wireless display terminal 30 executes the deviation elimination processing.

  When the wireless display terminal 30 receives a command from the access point 20 to which the wireless display terminal 30 belongs, the wireless display terminal 30 performs at least processing for determining whether the command is addressed to itself. Transition to a relatively large active mode. Therefore, if it is assumed that a command for each wireless display terminal 30 is transmitted with the same frequency to all the wireless display terminals 30, the number of wireless display terminals 30 belonging to a certain access point 20 increases. The chance that the operation mode of the wireless display terminal 30 belonging to the access point 20 shifts from the standby mode to the active mode increases, and the consumption of the battery 35 of these wireless display terminals 30 increases.

  On the other hand, in the wireless display system 100, when the deviation of the number of the wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from the predetermined range, the predetermined wireless display terminal 30 executes the unevenness cancellation processing. To do. Therefore, it is possible to suppress the occurrence of a state in which the batteries 35 of some of the wireless display terminals 30 are excessively consumed.

(3-2)
In the wireless display system 100 according to the embodiment, when the deviation of the number of wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from a predetermined range, at least the number of wireless display terminals 30 to which the wireless display terminal 30 belongs is the largest. The access point 20 transmits a distributed command related to execution of the bias elimination process to at least a part of the wireless display terminals 30 belonging to the access point 20.

  Here, it is possible to eliminate the bias in the number of wireless display terminals 30 belonging to a plurality of access points 20 by using a distributed command transmitted from the access point 20.

(3-3)
In the wireless display system 100 according to the above-described embodiment, the access point 20 is distributed in accordance with the instruction from the management server 10 to at least a part of the wireless display terminal 30 belonging to the access point 20 regarding the execution of the bias elimination process. Send a command.

  Here, since the wireless display terminal 30 executes the bias elimination process in accordance with an instruction from the management server 10, the management server 10 can grasp whether or not the bias elimination process is being executed in the wireless display terminal 30. Therefore, the management server 10 can avoid sending another command addressed to the wireless display terminal 30 during execution of the bias elimination processing of the wireless display terminal 30.

(3-4)
In the wireless display system 100 according to the embodiment, the distributed command is a global command in which the access point 20 that transmits the distributed command transmits all the wireless display terminals 30 belonging to the access point 20 as destinations.

  Here, since the distributed command related to the execution of the bias cancellation processing is a global command for all the wireless display terminals 30 belonging to the access point 20 that is the transmission source, it is not necessary to transmit the distributed command multiple times. Therefore, unlike the case where the wireless display terminal 30 individually transmits a distributed command to each of the plurality of wireless display terminals 30, the wireless display terminal 30 receives a signal including a distributed command addressed to another wireless display terminal 30. Thus, it is possible to prevent unnecessary transition to the active mode.

(3-5)
In the wireless display system 100 according to the above-described embodiment, the distributed command includes information on the threshold value of the radio wave intensity. The wireless display terminal 30 that has received the distributed command executes a bias elimination process when the strength of the radio wave received from the access point 20 to which the wireless display terminal 30 belongs is below the threshold value.

  When the radio wave intensity received from the access point 20 is relatively strong, a reception error of a signal transmitted from the access point 20 in the wireless display terminal 30 is relatively unlikely to occur. Therefore, it is difficult for the wireless display terminal 30 belonging to the access point 20 to operate in the active mode many times and the battery 35 is exhausted due to the retransmission of the command accompanying the reception error.

  Here, the wireless display terminal 30 having a relatively strong radio field intensity received from the access point 20 does not execute the bias eliminating process, and only the wireless display terminal 30 having a relatively weak radio field intensity received performs the bias eliminating process. Therefore, it is easy to realize a state in which the battery of the wireless display terminal 30 is hardly consumed as a whole system.

(3-6)
In the wireless display system 100 according to the above-described embodiment, the bias elimination process is a process of searching for an access point 20 with which the wireless display terminal 30 can communicate and determining the access point 20 with which communication is possible as an affiliation destination.

  Here, as the bias elimination process, the access point 20 with which the wireless display terminal 30 is communicable is searched and the affiliation destination is determined. Therefore, the deviation in the number of the wireless display terminals 30 belonging to the access point 20 is eliminated. can do.

(3-7)
The wireless display system 100 according to the above embodiment determines whether the wireless display terminal 30 can communicate with the access point 20 in a random order as a bias elimination process in a random order, and performs communication first. A process of determining the access point 20 determined to be possible as the affiliation destination is performed.

  Here, the affiliation destinations are easily distributed, and the deviation of the number of the wireless display terminals 30 belonging to the access point 20 is easily eliminated.

(3-8)
In the wireless display system 100 according to the above embodiment, the wireless display terminal 30 is an access point with which the wireless display terminal 30 can communicate as a target for the access point 20 other than the access point 20 to which the wireless display terminal 30 has belonged so far. 20 is searched, and a process of determining a communicable access point 20 as an affiliation destination is performed.

  Here, it is easy to reduce the number of wireless display terminals 30 belonging to the access point 20 that has belonged so far.

(4) Modifications Modifications of the above embodiment will be described below. Note that the modifications described below may be combined as appropriate within a range that does not contradict each other.

(4-1) Modification A
In the wireless display system 100 according to the above-described embodiment, the access point 20 transmits a distributed command after transmitting a beacon including information for notifying transmission of a command. However, the present invention is not limited to such a mode. . For example, the access point 20 may transmit a beacon including the distributed command when transmitting the distributed command.

(4-2) Modification B
In the wireless display system 100 according to the above-described embodiment, when the number of wireless display terminals 30 belonging to each of the plurality of access points 20 deviates from a predetermined range, some access points 20 become wireless display terminals 30. A distributed command is sent to the server.

  However, the access point 20 is not limited to this, and the access point 20 belongs to the number of wireless display terminals 30 belonging to the access point 20 instead of or in addition to the transmission of the distributed command. You may transmit the beacon containing number related information.

  For example, the access point 20 includes affiliation number related information regarding the number of wireless display terminals 30 belonging to the access point 20 periodically (every day, at a time when the store is not open (for example, 3:00 midnight)). Send a beacon. The access point 20, for example, in response to an instruction from the management server 10 (the instruction includes information on the number of wireless display terminals 30 belonging to the access point 20) Send. The affiliation number related information may be the affiliation number itself, or may be information indicating whether the affiliation number of the wireless display terminal 30 belonging to the access point 20 is excessive.

  And the radio | wireless display terminal 30 which received the beacon containing affiliation number relevant information should just perform a bias elimination process based on affiliation number relevant information. For example, when the affiliation number related information is information on the affiliation number, the wireless display terminal 30 executes the bias elimination process when the value of the affiliation number related information exceeds a predetermined value. For example, when the affiliation number related information is information indicating whether or not the number of wireless display terminals 30 belonging to the access point 20 is excessive, the wireless display terminal 30 belongs to the access point 20. In response to reception of information indicating that the number of wireless display terminals 30 is excessive, a bias elimination process is executed.

  If the wireless display terminals 30 belonging to a certain access point 20 execute the bias elimination processing all at once, it may be difficult to control the number of wireless display terminals 30 belonging to the access point 20. Therefore, for example, only a part of the wireless display terminal 30 that has received the affiliation number related information may be configured to execute the bias elimination processing. For example, a predetermined radio field strength threshold value is stored in advance in the storage unit 33 of the wireless display terminal 30, and the radio display terminal 30 determines that the radio field intensity received from the access point 20 to which the user belongs belongs to the predetermined radio field intensity threshold value. It may be configured to execute the bias elimination processing only when the ratio is lower.

(4-3) Modification C
In the above embodiment, the access point 20 transmits a distributed command in response to an instruction from the management server 10, but the present invention is not limited to this. For example, the access point 20 may be configured to determine whether or not the number of wireless display terminals 30 belonging to the access point 20 is excessive and transmit a distributed command.

(4-4) Modification D
In the above embodiment, the distributed command is a global command for all the wireless display terminals 30 belonging to the access point 20, but is not limited to this. For example, when the bias occurs, the management server 10 refers to the terminal master storage area 14b and identifies the wireless display terminal 30 belonging to the access point 20 that is determined to have an excessive number of wireless display terminals 30. A part may be determined as a transmission target of a distributed command (individual command). And you may instruct | indicate the transmission of the dispersion | distribution command with respect to the wireless display terminal 30 determined to the transmission point of a dispersion | distribution command to the access point 20 judged that the number of affiliations of the wireless display terminal 30 is excessive. In this case, the distributed command may be configured not to include the information on the threshold value of the radio wave intensity, and all the wireless display terminals 30 that have received the distributed command execute the bias elimination process.

  Note that after the management server 10 transmits a distributed command to some wireless display terminals 30 belonging to a certain access point 20, the number of wireless display terminals 30 belonging to the access point 20 is still excessive. If it is determined that the distributed command is transmitted, the distributed command may be further transmitted to a target other than the wireless display terminal 30 that previously transmitted the distributed command. Then, the management server 10 may repeat such processing until the number of wireless display terminals 30 belonging to the access point 20 is not excessive.

  The management server 10 repeats such processing and belongs to the access point 20 even after sending a distributed command to all the wireless display terminals 30 belonging to the access point 20 once. If it is determined that the number of wireless display terminals 30 is still excessive, transmission of further distributed commands may be stopped. Alternatively, the management server 10 issues a distributed command to a part of the wireless display terminals 30 belonging to the access point 20 until the number of wireless display terminals 30 belonging to the access point 20 is not excessive. You may repeat the process to transmit.

(4-5) Modification E
For example, in the wireless display system, the distributed command may be transmitted from the access point 20 to the wireless display terminal 30 in the following manner.

  In the wireless display system of Modification E, the wireless display terminal 30 is first based on, for example, (B) the number of wireless display terminals belonging to an access point described in (2-1-4-1) of the above embodiment. The affiliated access point 20 is determined using the affiliated access point selection method. In the wireless display system of Modification E, when the wireless display terminal 30 executes the above method (B), the received radio wave intensity of each channel is measured, and the measurement result is transmitted to the access point 20 (management server). 10) configured to transmit. The management server 10 stores the received radio wave intensity information of each channel for each wireless display terminal 30. When the management server 10 determines that a part of the wireless display terminal 30 belonging to a certain access point 20 should execute the bias elimination processing when the biased state occurs, the management server 10 displays the wireless display belonging to the access point 20. For the terminal 30, information on the measurement result of the received radio wave intensity of each channel received in advance is referred to. Then, the management server 10 distributes the command to instruct the wireless display terminal 30 that has a channel with a stronger received radio wave strength than the received radio wave strength of the channel of the access point 20 to which it currently belongs to execute the bias elimination process. Send. Here, the dispersion command may not include information on the threshold value of the radio wave intensity.

  In such a configuration, since the distributed command is transmitted to the wireless display terminal 30 where the access point 20 to which the affiliation belongs is likely to be changed, the number of affiliations of the wireless display terminals 30 between the access points 20 can be efficiently determined. The bias can be eliminated.

  The wireless display system according to the present invention is less likely to be biased in the number of wireless display terminals belonging to an access point, and is unlikely to cause a state in which the batteries of wireless display terminals belonging to some access points are excessively consumed. Useful as a system.

10 management server 20 access point 30 wireless display terminal 100 wireless display system

JP 2016-140368 A

Claims (10)

A plurality of battery-powered wireless display terminals;
A plurality of access points for communicating with the wireless display terminal;
A management server connected to the access point and managing the wireless display terminal;
With
Each of the wireless display terminals belongs to one of a plurality of the access points, receives a signal transmitted by the access points to which the wireless display terminals belong,
Each of the wireless display terminals is in a standby mode waiting for reception of a command destined for at least one of the wireless display terminals from the access point to which the wireless display terminal belongs, and the wireless display terminal belongs to The command received from the access point has at least a process of determining whether or not it is addressed to the active mode, and has an active mode with a higher power consumption than the standby mode as an operation mode,
When the deviation of the number of the wireless display terminals belonging to each of the plurality of access points has deviated from a predetermined range, the predetermined wireless display terminal executes the bias elimination processing;
Wireless display system. When the deviation in the number of the wireless display terminals belonging to each of the plurality of access points deviates from the predetermined range, at least the access point having the largest number of wireless display terminals belonging to the access point belongs to the access point A distributed command related to the execution of the bias cancellation process is transmitted to at least a part of the wireless display terminal.
The wireless display system according to claim 1. The access point transmits the distributed command related to the execution of the bias cancellation processing to at least a part of the wireless display terminal belonging to the access point according to an instruction from the management server.
The wireless display system according to claim 2. The distributed command is a global command in which the access point that transmits the distributed command transmits all the wireless display terminals belonging to the access point as destinations.
The wireless display system according to claim 2 or 3. The dispersion command includes information on a threshold value of radio field intensity,
The wireless display terminal that has received the distributed command executes the bias cancellation process when the strength of radio waves received from the access point to which the wireless command terminal belongs belongs below the threshold value.
The wireless display system according to any one of claims 2 to 4. The access point periodically sends a beacon,
When the access point transmits the distributed command, the access point transmits a beacon including the distributed command.
The wireless display system according to any one of claims 2 to 5. The bias elimination process is a process of searching for the access point with which the wireless display terminal can communicate, and determining the access point with which communication is possible as an affiliation destination.
The wireless display system according to claim 1. The wireless display terminal determines whether or not communication with the access point is possible as the bias elimination processing in a random order for the plurality of access points, and belongs to the access point that is initially determined to be communicable Do the process that decides first,
The wireless display system according to claim 7. The wireless display terminal searches the access point with which the wireless display terminal can communicate, targeting the access points other than the access point to which the wireless display terminal has belonged, as the bias elimination processing, and the accessible communication Perform the process of determining points as affiliations,
The wireless display system according to claim 7. The access point periodically transmits a beacon including affiliation number related information regarding the number of wireless display terminals belonging to the access point,
The wireless display terminal performs the bias elimination processing based on the affiliation number related information.
The wireless display system according to claim 1.

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