Display device, display system, and display method

Abstract

To display a content group while synchronizing between a plurality of display devices without having a specific device that serves as a master.SOLUTION: A display device 3a includes: a transmitting unit 33a that transmits a synchronization signal to another device; a receiving unit 34a that receives the synchronization signal from the other device; a content group acquisition unit 311 that repeatedly acquires a content group for its own device from a play list; a video display unit 314 that repeatedly reproduces video based on the content group; a synchronization determination unit 312 that causes the reproduction of a current content group to be rounded up and a next content group to be reproduced when the receiving unit 34a receives the synchronization signal while the video display unit 314 is displaying the current content group; and a synchronization signal transmission control unit 313 that causes the synchronization signal to be transmitted from the transmitting unit 33a to the other device when the video display unit 314 finishes displaying the current content group.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a display device, a display system, and a display method for displaying information transmitted from an external source, for example. [Background technology]

[0002] In recent years, display devices that display information (hereinafter referred to as content) transmitted from an external source have become widespread in various fields. When displaying content on multiple display devices installed in one place, each display device displays the content using its own reference clock. The accuracy of the reference clock of each display device changes depending on the environment (e.g., temperature and individual differences in hardware). As a result, when multiple display devices are used, discrepancies in the display time of content accumulate.

[0003] To solve the above problems, conventional content display systems generally use a single master display device, in which the other multiple display devices (hereinafter referred to as slave display devices) display content according to instructions from the master display device.

[0004] However, in a method in which display is performed in accordance with a master device, if the master device goes down due to a malfunction or the like, display cannot be continued and the visibility of the content is significantly reduced.

[0005] Patent Document 1 solves this problem. The abstract of Patent Document 1 states that "the broadcast receiving unit 6 receives ID information transmitted from each of a plurality of in-vehicle video playback devices including the own device, and obtains a local time corresponding to the received time from the time management unit 10 and adds it to the ID information. The synchronization control unit 8 calculates the time adjustment amount based on the value of the local time added to each of the plurality of ID information stored in the received data management unit 7." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2015-170369 A Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the accuracy of the reference clock of each display device varies depending on the environment, which causes an accumulation of discrepancies in the content display times among a plurality of display devices. Consider a display system that repeatedly displays multiple contents (hereinafter, "content group") on multiple display devices. The number of times this display system repeatedly displays the content group is called the "display lap count." If the content group displayed by the display system differs depending on the display lap count, and if a discrepancy in the display lap count occurs on some display devices due to some factor (e.g., an unexpected restart of the display device, or power ON / OFF operation of the display device), the content group displayed on the display device where the discrepancy in the display lap count occurs will differ from the content group displayed on display devices where the discrepancy in the display lap count does not occur.

[0008] Therefore, an object of the present invention is to display a content group while maintaining synchronization among a plurality of display devices, without having a specific master device. [Means for solving the problem]

[0009] In order to solve the above-mentioned problems, the display device of the present invention includes a transmission unit that transmits a synchronization signal to another device, a reception unit that receives a synchronization signal from the other device, a content group acquisition unit that repeatedly acquires a content group for the display device itself from a playlist, a video display unit that repeatedly plays a video based on the content group, a synchronization determination unit that, when the reception unit receives a synchronization signal while the video display unit is displaying the current content group, stops playback of the current content group and plays a next content group, and a synchronization signal transmission control unit that, when the video display unit finishes displaying the current content group, causes the transmission unit to transmit a synchronization signal to the other device, and the content group acquisition unit creates a list of the presence or absence of content files from the content group, and if there is a missing content, transmits a synchronization signal to the other device by the transmission unit. Content loss The video display unit notifies the other device. Deficiency The notified content is not reproduced, and the content next to the notified content is reproduced.

[0010] a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit has finished displaying the current content group, and a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit has finished displaying the current content group, and a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit has finished displaying the current content group, and a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit has finished displaying the current content group, and the ... generates a list of the presence or absence of content files from the content group, and if there is any missing content, transmits a list of the presence or absence of content files from the content group, and if there is any missing content, transmits the list of the presence or absence of content files to the other device by the transmission unit. Content lossThe video display unit notifies the other device. Deficiency The notified content is not reproduced, and the content next to the notified content is reproduced.

[0011] The display method of the present invention includes a step of a transmitter transmitting a synchronization signal to another device, a step of a receiver receiving a synchronization signal from the other device, a step of a content group acquisition unit repeatedly acquiring a content group for the device itself from a playlist, a step of a video display unit repeatedly playing video based on the content group, a step of a synchronization determination unit cutting off playback of the current content group and playing the next content group when the receiver receives a synchronization signal while the video display unit is displaying the current content group, a step of a synchronization signal transmission control unit causing the transmitter to transmit a synchronization signal to the other device when the video display unit finishes displaying the current content group, and a step of the content group acquisition unit creating a list of the presence or absence of content files from the content group, and if there is missing content, transmitting the synchronization signal to the other device by the transmitter. Content loss a step of notifying the other device; and Deficiency The method is characterized by executing a step of not playing the notified content, and playing the content next to the notified content. Other means will be described in the description of the embodiment of the invention. Effect of the Invention

[0012] According to the present invention, it is possible to display a content group in synchronization among a plurality of display devices without having a specific master device. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing the overall configuration of a system including a display device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram of a display device. [Figure 3A] FIG. 2 is a diagram showing a basic playlist structure. [Figure 3B]FIG. 2 is a diagram showing a content group of a basic playlist. [Figure 4] FIG. 11 is a sequence diagram showing the operations of transmitting a synchronization signal between a plurality of display devices, updating the number of display laps, and real-time playback. [Figure 5A] FIG. 13 is a diagram showing the structure of a playlist of a content group to which the number of display laps has been added. [Figure 5B] FIG. 13 is a diagram showing content groups for each number of display laps. [Figure 6] 11 is a sequence diagram showing an operation of restoring a display state after a display device having a content group based on the number of display laps has reset the number of display laps due to rebooting or the like, causing a significant discrepancy. FIG. [Figure 7A] FIG. 13 shows a playlist in which a device ID is added to the conditions. [Figure 7B] FIG. 13 is a diagram showing a content group in which a device ID is added to a condition. [Figure 8A] This is a diagram showing the structure of a playlist in which multiple conditions have been added, including the number of laps to be displayed, device ID, car number, direction of travel, and train position. [Figure 8B] FIG. 2 is a diagram showing a configuration of train information. [Figure 8C] FIG. 2 is a diagram showing a configuration of a train information storage unit. [Figure 9A] 13 is a flowchart of a synchronization process. [Figure 9B] 13 is a flowchart of a synchronization process. [Figure 10] FIG. 13 is a sequence diagram showing an operation for synchronizing while displaying without compromising the design by sending a list of the presence or absence of content files and performing skipping within the display device to be synchronized when content is missing. [Figure 11A] 13 is a flowchart of a synchronization process for performing skipping when content is missing. [Figure 11B] 13 is a flowchart of a synchronization process for performing skipping when content is missing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a display system 1 including display devices 3a to 3f in this embodiment. The display system 1 includes a central unit 90 installed in one train, terminal units 4a, 4b installed in each of the cars 2a, 2b that make up the train, and display units 3a-3f installed in each of the cars 2a, 2b. Although only the cars 2a, 2b that make up one train are illustrated here, the number of cars in the train may be three or more and is not limited thereto.

[0015] The central device 90 centrally controls the display system 1. The central device 90 is connected to the train status monitoring device 81, receives train information 82 from the train status monitoring device 81, and accepts an instruction to start displaying on the display system 1. The central device 90 is also communicatively connected to a ground distribution system 92 that is wirelessly connected to a ground network 93 via an antenna 91, and receives and stores content and playlists from the ground distribution system 92. The content here is video or still images such as advertisements, news, and weather forecasts provided to train passengers. The content received from the ground distribution system 92 may include audio in addition to video. The central device 90 is connected to the terminal device 4a so as to be communicatively connected to each other.

[0016] The terminal device 4a manages the display devices 3a-3c installed in the vehicle 2a, and includes a storage unit 41a. The terminal device 4b manages the display devices 3d-3f installed in the vehicle 2b, and includes a storage unit 41b. The terminal device 4a is then connected to the terminal device 4b installed in the next vehicle 2b in sequence. The same applies to subsequent vehicles and terminal devices. This allows the central device 90 to communicate with the terminal devices 4a, 4b, etc.

[0017] The display device 3a includes a control unit 31a, a storage unit 32a, a transmission unit 33a, and a reception unit 34a. The control unit 31a is a functional unit realized by, for example, a CPU (Central Processing Unit) executing a program using a RAM (Random Access Memory). The storage unit 32a is, for example, a non-volatile large-capacity storage device such as a flash memory. The transmission unit 33a and the reception unit 34a are functional units using, for example, a NIC (Network Interface Card), and transmit and receive information between the terminal device 4a and the other display devices 3b and 3c via a communication path.

[0018] When the terminal devices 4a, 4b, etc. receive the playlist and train information from the central device 90, they temporarily store them in the storage units 41a, 41b. The playlist is an arrangement of meta information indicating a group of contents to be displayed on each of the display devices 3a to 3f. The train information is information such as the car number, traveling direction, and running position of the vehicle in which the display devices 3a to 3f (own device) under the control of the terminal devices 4a, 4b, etc. are installed. The terminal device 4a transmits the playlist and train information to the display devices 3a to 3c, one or more of which are installed in the vehicle 2a. The terminal device 4b transmits the playlist and train information to the display devices 3d to 3f, one or more of which are installed in the vehicle 2b. In other words, each of the terminal devices 4a, 4b, etc. includes a train information transmitting unit that transmits train information including at least one of the car number, traveling direction, and running position of the vehicle in which the terminal device 4a, 4b, etc. is installed to each of the display devices 3a to 3f, etc.

[0019] FIG. 2 is a block diagram of the display device 3a. The display device 3a includes a control unit 31a, a storage unit 32a, a transmission unit 33a, and a reception unit 34a. The display device 3a displays information transmitted from an external device.

[0020] The control unit 31a includes a content group acquisition unit 311, a synchronization determination unit 312, a synchronization signal transmission control unit 313, and a video display unit 314. The control unit 31a performs overall control of the display device 3a. A CPU (not shown) of the control unit 31a executes a display program stored in a storage unit (not shown), thereby realizing each of these functional units.

[0021] The content group acquisition unit 311 acquires its own content group from the playlist. The synchronization determination unit 312 compares the display lap count of the synchronization signal received from one of the other display devices 3b, 3c with the display lap count of its own device (display device 3a). If the display lap count of its own device is equal to or greater than the display lap count of the synchronization signal received from the other device, the synchronization determination unit 312 sets the display lap count of the received synchronization signal as the display lap count of its own device. The synchronization determination unit 312 then adds 1 to the display lap count of its own device to update it, and rounds up the display of the current content group and displays the next content group.

[0022] Upon completing display of the entire content group, the synchronization signal transmission control unit 313 controls the synchronization signal transmission unit 332 to transmit a synchronization signal to the other display devices 3b and 3c, and to increment the number of display laps of its own device by one to update it. The video display unit 314 is, for example, a liquid crystal panel or an organic EL (Electro Luminescence) panel, and plays back each content file of the content group to display the video.

[0023] The transmission unit 33 a includes a playlist transmission unit 331 and a synchronization signal transmission unit 332 . The playlist transmission section 331 transmits the playlist to the other display devices 3b and 3c. The synchronization signal transmission unit 332 transmits the synchronization signal to the other display devices 3b and 3c.

[0024] The storage unit 32 a includes a playlist storage unit 321 , a display lap count storage unit 322 , and a train information storage unit 323 . The playlist storage unit 321 stores a playlist. The display lap count storage unit 322 stores the number of laps the current content group has been displayed. The train information storage unit 323 stores information about the train on which the display system 1 is mounted.

[0025] The receiving unit 34 a includes a playlist receiving unit 341 , a train information receiving unit 343 , and a synchronization signal receiving unit 342 . The playlist receiving unit 341 receives playlists from the other display devices 3b and 3c and the terminal devices 4a and 4b. The train information receiving unit 343 receives train information 82 from the terminal device 4a. The synchronization signal receiving unit 342 receives synchronization signals from the other display devices 3b and 3c.

[0026] FIG. 3A shows the structure of a basic playlist 1001. A content ID column 1098 and a content file name column 1099 are defined in the basic playlist 1001. The content ID column 1098 stores a content identifier. The content file name column 1099 stores the file name of the content.

[0027] If there is no condition, the content group acquisition unit 311 acquires all files in the playlist 1001 as the content group 2001 .

[0028] FIG. 3B shows a content group 2001 of the basic playlist 1001. The content group 2001 is the content indicated in the content file name column 1099 of the playlist 1001. The display device 3a repeatedly displays this content group 2001 from the beginning to the end.

[0029] Fig. 4 is a sequence diagram showing the operation of transmitting a synchronization signal between a plurality of display devices, updating the number of display laps, and instantaneous playback. Fig. 4 shows the synchronization timing in this embodiment. When the display devices 3a to 3c are started up, the display lap count for each is set to 1 (steps S10a to S10c). Then, the display devices 3a to 3c start playing the content group 2001 (steps S11a to S11c).

[0030] Here, the display device 3b finishes displaying the content group 2001 first and transmits a synchronization signal including the number of display revolutions to the display devices 3a and 3c (step S12). Next, the display device 3b increments the number of display revolutions by 1, acquires the next content group 2001, and displays the acquired content group (step S13b).

[0031] The display devices 3a and 3c compare the display lap count of the received synchronization signal with the display lap count of their own devices. If the display lap count of the synchronization signal is equal to or greater than the display lap count of their own devices, the display devices 3a and 3c update the display lap count of their own devices to the display lap count of the synchronization signal, and then increment the display lap count by one.

[0032] The display devices 3a and 3c stop displaying the current content group 2001, acquire the next content group 2001, and start displaying the acquired content group 2001 (steps S13a and S13c).

[0033] Note that the playlist 1001 shown in Fig. 3A and the content group 2001 shown in Fig. 3B are intended to repeatedly play the same content regardless of the number of display cycles. Therefore, in such a case, the number of display cycles may not be included in the synchronization signal, and the display device that first finishes playing the content group may simply transmit the synchronization signal to the other display devices.

[0034] FIG. 5A shows the structure of a playlist 1002 of a content group to which a display loop count column has been added. In the playlist 1002, in addition to a content ID column 1098 and a content file name column 1099, a display lap count column 1097 is defined. The content ID column 1098 stores a content identifier. The content file name column 1099 stores a content file name. The display lap count column 1097 describes the condition for the display lap count for playing back this content.

[0035] This playlist 1002 is for the case where the number of display cycles is set as a condition for creating a content group. In this case, the content group acquisition unit 311 acquires excerpts of content according to the number of display cycles as the content groups 2021 to 2023.

[0036] FIG. 5B is a diagram showing the correspondence between the display lap count and the content group. When the display lap count is 1, the content group acquisition unit 311 acquires the content group 2021. This content group 2021 includes b.mpg as the second file. When the number of display laps is 2, the content group acquisition unit 311 acquires the content group 2022. This content group 2022 includes c.mpg as the second item. When the display lap count is 3, the content group acquisition unit 311 acquires the content group 2023. This content group 2023 includes d.mpg as the second content.

[0037] FIG. 6 is a sequence diagram showing the operation of restoring the display state of a display device 3c having a content group based on the number of display laps after the number of display laps is reset due to a reboot or the like, resulting in a significant discrepancy with the other display devices 3a and 3b.

[0038] The display lap count for the display devices 3a to 3c is set to 2 (steps S20a to S20c). Then, the display devices 3a to 3c start playing the next content group (steps S21a to S21c).

[0039] Then, while the display device 3c is playing back the content group, an unexpected restart occurs (step S22). The display device 3c sets the number of display laps to 1 (step S23) and plays back the content group (step S24).

[0040] Next, when the display device 3b finishes the second display rotation, it transmits a synchronization signal to the other display devices 3a and 3c (step S25) and plays back the next content group (step S26b).

[0041] When the display device 3a sets the number of display laps to 3 in response to the synchronization signal received from the display device 3b, the display device 3a interrupts the reproduction of the current content group and reproduces the next content group (step S26a).

[0042] The display device 3c, whose display lap count is 1, sets the display lap count to 3 in response to the synchronization signal received from the display device 3b, so that the display device 3c interrupts the playback of the current content group and displays the next content group 2023 (step S26c). This allows the display device 3c to synchronize the playback again.

[0043] Also, consider a case where the display device 3c finishes displaying the content group first and transmits a synchronization signal including information on the display cycle count of 1 to the display devices 3a and 3b. The display devices 3a and 3b do not interrupt the playback of the content group because the display cycle count of their own devices is smaller than the display cycle count of the received synchronization signal.

[0044] FIG. 7A shows a playlist 1003 in which a device ID has been added as a condition. In the playlist 1003, a content ID column 1098, a content file name column 1099, and a device ID column 1096 are defined. The content ID column 1098 stores an identifier of the content. The content file name column 1099 stores a file name of the content. And the device ID column 1096 stores an identifier of the display device on which the content is to be played. A.mpg is played on all the display devices. Meanwhile, B.mpg is played on the display device with a device ID of 1, C.mpg is played on the display device with a device ID of 2, and D.mpg is played on the display device with a device ID of 3. In this way, for example, when a display device with a device ID of 1, a display device with a device ID of 2, and a display device with a device ID of 3 are installed side by side, and B.mpg, C.mpg, and D.mpg are respectively on the left, center, and right side of the panoramic video, the entire panoramic video can be played on these three display devices.

[0045] FIG. 7B is a diagram showing content groups 2041a to 2041c for each number of display laps. The display device 3a is assigned a device ID of 1. The display device 3b is assigned a device ID of 2. The display device 3c is assigned a device ID of 3. In the case where the playlist 1003 has a device ID as a condition, the content group acquisition unit 311 of the display device 3a acquires an excerpt of video corresponding to the device ID as the content group 2041a. Similarly, the content group acquisition unit 311 of the display device 3b acquires an excerpt of video corresponding to the device ID as the content group 2041b. The content group acquisition unit 311 of the display device 3c acquires an excerpt of video corresponding to the device ID as the content group 2041c. From an operational standpoint, it is desirable that the display devices 3a to 3c have the same playback times for the content groups 2041a to 2041c.

[0046] FIG. 8A shows the structure of a playlist 1004 in which multiple conditions including the number of laps to be displayed, the device ID, the car number, the direction of travel, and the train position have been added. The playlist 1004 contains a content ID column 1098, a content file name column 1099, a display lap count column 1097, and a device ID column 1096, as well as a car number column 1084, a direction of travel column 1085, and a train position column 1086. The playlist 1004 is for a case where multiple conditions are met, and is defined by information consisting of train information 82 received from the train status monitoring device 81, such as the car number, direction of travel, and train position.

[0047] The content ID field 1098 stores a content identifier. The content file name field 1099 stores a content file name. The display lap count field stores the number of laps the content has been displayed. The device ID field 1096 stores an identifier of a device on which the content is being played.

[0048] Furthermore, the car number column 1084 stores information about the car in which the display device is installed. The running direction column 1085 stores the running direction of the train. The train position column 1086 stores information about the position of the train.

[0049] FIG. 8B is a diagram showing the configuration of the train information 82. As shown in FIG. The train information 82 includes car information, traveling direction information, and train position information. This train information 82 is transmitted from the terminal devices 4a and 4b shown in Fig. 1 to each of the display devices 3a to 3f. Of the train information 82, the traveling direction and train position information are transmitted from the train status monitoring device 81 to the terminal devices 4a and 4b via the central device 90. Of the train information 82, the car information is set by the terminal devices 4a and 4b.

[0050] FIG. 8C is a diagram showing information in the train information storage unit 323. The train information storage unit 323 stores the contents of the train information 82 described above with an apparatus ID added thereto. The content group acquisition unit 311 of each display device can acquire an appropriate content group according to the current situation from the display lap count storage unit 322 and the train information 82 stored in the train information storage unit 323. Specifically, for example, according to the train position, the content group acquisition unit 311 can acquire advertisement content of a store corresponding to this train position. Therefore, the display system 1 can display appropriate advertisement content to train passengers.

[0051] 9A and 9B are flowcharts of the synchronization process. The display devices 3a to 3f start displaying content when some start condition is satisfied. In practical operation, it is desirable for each of the display devices 3a to 3f to satisfy the start condition at the same timing. The following flowchart of the synchronization process will be explained using the display device 3a as an example. In step S30, the content group acquisition unit 311 of the control unit 31a acquires the content group for the display lap count from the train information and the playlist.

[0052] In step S31, the synchronization determination unit 312 of the control unit 31a determines whether all the contents in the content group have been displayed. If not all the contents have been displayed (No), the control unit 31a proceeds to step S32. Then, the video display unit 314 displays the next content in the content group.

[0053] If all contents have been displayed in step S31, the synchronization signal transmission control unit 313 transmits a synchronization signal including the display lap count of the own device to all other devices (step S33).Then, the synchronization signal transmission control unit 313 adds 1 to the display lap count (step S34) and returns to the process of step S30.

[0054] 9B, when the display device 3a receives the synchronization signal transmitted by the other device in step S33 (step S40), the synchronization determination unit 312 determines whether the display lap count of the received synchronization signal is equal to or greater than the display lap count of the display device itself (step S41). If the display lap count of the synchronization notification is less than the display lap count of the display device itself (No), the display device 3a continues the operation before receiving the synchronization signal (step S42).

[0055] If the display lap count of the synchronization notification is equal to or greater than the display lap count of the own device (Yes), the synchronization determination unit 312 determines whether the display lap count of the synchronization signal of the other device received in step S40 matches the display lap count of the own device (step S43). If the display lap count of the synchronization signal received from the other device does not match the display lap count of the own device, the synchronization determination unit 312 updates the display lap count of the device with the display lap count of the received synchronization signal (step S44). Thereafter, the synchronization determination unit 312 adds 1 to the display lap count of the own device (step S45), and acquires the content group with the display lap count from the playlist (step S46). Then, the synchronization determination unit 312 stops displaying the current content group (step S47), and returns to the process of step S31.

[0056] FIG. 10 is a sequence diagram showing an operation for synchronizing while displaying content when content is missing by sending a content file presence / absence list information and performing skipping within the display device to be synchronized. The figure illustrates a synchronization process when the content group 2001 is displayed on the display devices 3a to 3c, and the content B of the display device 3a cannot be displayed due to a file loss. The display devices 3a to 3c acquire the content group 2001 for the number of revolutions, check whether all files described in the content group 2001 are present in their own devices, and create content file presence / absence list information. At this time, the display device 3a is missing content B and cannot display it, so it adds information that content B is not present in the content file presence / absence list information and that other contents are present, and notifies the display devices 3b and 3c. The display devices 3b and 3c have no content loss, so it adds information that all contents are present in the content file presence / absence list information, and notifies the display devices 3a, 3c, and the display devices 3b and 3c. The display device 3a does not have content B, so it displays content C after displaying content A. Moreover, the display devices 3b and 3c display content C without displaying content B after displaying content A based on the content file presence / absence list information. Through this process, the display devices 3a to 3c commonly skip content B. Furthermore, when the display of the current content group ends, the next content group is obtained and a list of the presence or absence of content files is created, so that even when the content group is switched according to the number of display laps, the display of any content that is missing on any of the display devices is skipped, thereby achieving synchronization between the display devices.

[0057] 11A and 11B are flowcharts of a synchronization process for performing skipping when content is missing. A flowchart of a synchronization process performed when skip processing is performed due to a content loss will be described below with the display device 3a as the main operating unit.

[0058] The display device 3a starts displaying the content when some start condition is satisfied. In practical operation, it is desirable for each display device to satisfy the start condition at the same time. Then, in step S70, the content group acquisition unit 311 of the control unit 31a acquires the content group of the display loop count from the playlist. Then, the content group acquisition unit 311 checks whether it has the content file described in the content group, and creates content file presence / absence list information (step S71).

[0059] Thereafter, the content group acquisition unit 311 notifies the other apparatus with which the content file exists or does not exist of the content file list information (step S72). Thereafter, the content group acquisition unit 311 receives the content file existence or absence list information from the other apparatus with which the content file exists or does not exist (step S72).

[0060] The control unit 31a judges whether or not display of all contents in the content group has been completed (step S74). If display of all contents has not been completed (No), the control unit 31a proceeds to step S75, and judges whether or not all other devices to be synchronized have the file of the next content from the content file presence / absence list information. If display of all contents has been completed (Yes), the control unit 31a proceeds to step S82 in FIG. 11B.

[0061] If all the other devices have the file of the next content (Yes), the control unit 31a proceeds to step S77. If any of the other devices does not have the file of the next content (No), the control unit 31a proceeds to step S76, notifies all the other display devices (other devices) to be synchronized of the next and subsequent contents held by them, and proceeds to step S77. In other words, the video display unit 314 does not play the content notified of the loss by the other devices, but plays the content following this content.

[0062] In step S77, the control unit 31a determines whether the next content is the last content in the current content group. If the next content is the last content (Yes), the control unit 31a proceeds to the parallel processing of FIG. 11B, and if the next content is not the last content (No), the control unit 31a proceeds to step S78.

[0063] In step S78, the control unit 31a displays the next content in the content group on the video display unit 314, and then returns to the process of step S74.

[0064] 11B includes a process in which the video display unit 314 displays content (step S79), a process in which the content group acquisition unit 311 notifies other devices with which the content file exists or does not exist list information (step S80), and a process in which the content file existence or absence list information is received from the other devices with which the content file exists or does not exist list information (step S81). This allows the display device 3a to share information related to a newly occurring content file loss with the other devices.

[0065] In step S82, the synchronization signal transmission control unit 313 transmits the synchronization signal to which the display lap count of the own device is added to all other devices. Then, the synchronization signal transmission control unit 313 adds 1 to the display lap count (step S83), and returns to the process of step S70.

[0066] (Effects of this embodiment) The embodiment described above has the following advantages (A) to (F). (A) This embodiment makes it possible to display a group of content in synchronization among a plurality of display devices, without having a specific master device. (B) In the event that a discrepancy in the number of display rotations occurs on some display devices, it is possible to perform synchronized display in accordance with the display devices on which no discrepancy in the number of display rotations occurs, and further, the display device on which the discrepancy in the number of display rotations occurs can display a group of contents in accordance with the display rotation number of the display device on which no discrepancy in the number of display rotations occurs.

[0067] (C) According to this embodiment, there is no need for a master device to issue a timing signal to synchronize multiple display devices, and it is possible to continue synchronous display in accordance with the display device that completes displaying a group of content first.

[0068] (D) In ​​the event that a discrepancy in the number of display cycles occurs on some display devices, display devices on which no discrepancy in the number of display cycles occurs can resume synchronous display at the timing when the display of the content group is completed, and at the same timing, display devices on which a discrepancy in the number of display cycles occurs can match the number of display cycles with the display devices on which no discrepancy in the number of display cycles occurs, and can display the content group in accordance with the number of display cycles.

[0069] (E) It is possible to play back an advertisement video in accordance with the number of times the video has been displayed by only recording the number of times the video has been displayed on one's own device, without recording information on a plurality of other display devices.

[0070] (F) Since communication for the purpose of synchronization only notifies the number of laps to be displayed after the roll ends, the load on the network is small, making this a method of synchronization that is not subject to the constraints of network performance.

[0071] (Modification) The present invention is not limited to the above-described embodiment, and includes various modified examples. For example, the above-described embodiment has been described in detail to clearly explain the present invention, and is not necessarily limited to those having all of the configurations described. It is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. In addition, it is also possible to add, delete, or replace a part of the configuration of each embodiment with another configuration.

[0072] The above configurations, functions, processing units, processing means, etc. may be realized in part or in whole by hardware such as an integrated circuit. The above configurations, functions, etc. may be realized by software by a processor interpreting and executing a program that realizes each function. Information such as the program, table, file, etc. that realizes each function can be stored in a recording device such as a memory, a hard disk, or an SSD (Solid State Drive), or a recording medium such as a flash memory card or a DVD (Digital Versatile Disk).

[0073] In each embodiment, the control lines and information lines are those that are considered necessary for the explanation, and not all control lines and information lines in the product are necessarily shown. In reality, it may be considered that almost all components are connected to each other. As modified examples of the present invention, for example, the following (a) to (k) are available.

[0074] (a) The train information receiving unit 343 and the train information storage unit 323 do not necessarily need to be synchronized. (b) In the present embodiment, the central device 90 and the terminal devices 4a and 4b are described, but these are not necessarily required for synchronization.

[0075] (c) In the present embodiment, the playlists 1001-1004 transmitted from the terrestrial distribution system 92 are communicated via the central device 90 and the terminal devices 4a and 4b. However, the terrestrial distribution system 92, the central device 90, and the terminal devices 4a and 4b are not necessarily required, and any method can be used as long as the playlists 1001-1004 can be stored in the playlist storage units 321 of the display devices 3a-3f.

[0076] (d) In this embodiment, the train status monitoring device 81 is provided, but this is not necessarily required for synchronous display. (e) In this embodiment, three display devices 3a to 3f are provided for each of the vehicles 2a and 2b, but this does not necessarily have to be three, and any number may be used. (f) In the present embodiment, all display devices within the vehicle are synchronized, but it is also possible to divide the devices to be synchronized within the vehicle using device IDs or the like.

[0077] (g) In this embodiment, synchronization is performed when all the contents in the content group have been completed. However, it is also possible to enable synchronization on a content basis by using the number of displayed contents in the content group in addition to the number of display laps. (h) In this embodiment, an information display system is described that is installed on a train. However, the present invention is not limited to this and may also be applied to information display systems installed in station buildings, shopping centers, and the like, and is not limited thereto. (i) The display system of this embodiment acquires a content group based on train information. However, the content group may be acquired based on environmental information such as weather, air pressure, humidity, and temperature, or date and time information such as days of the week, holidays, and anniversaries, without being limited to train information. (j) In the display system of this embodiment, when the same content group continues to be played back regardless of the number of display cycles, the synchronization signal does not need to include the number of display cycles. In this case, when the receiving unit receives a synchronization signal while the video display unit is displaying the current content group, the synchronization determination unit cuts off the playback of the current content group and plays the next content group. In addition, when the video display unit finishes displaying the current content group, the synchronization signal transmission control unit causes the transmitting unit to transmit a synchronization signal to another device. (k) In the display system of the present embodiment, the display lap count is updated by adding 1 each time a content group is displayed. However, this is not limited to this, and the display lap count may be updated by adding any integer number, and is not limited thereto. [Explanation of symbols]

[0078] 1 Display System 2a, 2b Vehicles 3a~3f Display device 31a to 31f Control section 311 Content Group Acquisition Unit 312 Synchronization Judgment Unit 313 Synchronization signal transmission control section 314 Video display unit 32a~32f Storage section 321 Playlist Storage 322 Display number of laps storage section 323 Train Information Storage Department 33a~33f Transmitter 331 Playlist Storage 332 Synchronization signal transmitter 34a~34f Receiving section 341 Playlist Receiver 342 Synchronization signal receiver 343 Train Information Receiving Unit 4a, 4b Terminal equipment 41a,41b Storage section 90 Central unit 81 Train status monitoring device 82 Train information 91 Antenna 93 Terrestrial Network 92 Terrestrial Distribution System 1001~1004 Playlist 1098 Content ID field 1099 Content File Name Column 1099a Advertising Content Section 1097 Display lap count column 1096 Device ID column Car No. 1084 1085 Direction column 1086 Train position column 2001, 2021~2023, 2041a~2041c Content Group

Claims

1. A transmitter that transmits a synchronization signal to another device; a receiving unit for receiving a synchronization signal from the other device; a content group acquisition unit that repeatedly acquires a content group for the device itself from a playlist; a video display unit that repeatedly plays back videos based on the content group; a synchronization determination unit that, when the receiving unit receives a synchronization signal while the video display unit is displaying a current content group, cuts off playback of the current content group and plays a next content group; a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit finishes displaying a current group of contents; Equipped with the content group acquisition unit creates a list of the presence or absence of a content file from the content group, and if there is a content loss, notifies the other device of the content loss by the transmission unit; the video display unit does not play the content notified of the loss by the other device, and plays the next content of the content. A display device comprising:

2. The transmission unit is a playlist transmission unit that transmits a playlist to the other device; A synchronization signal transmission unit that transmits a synchronization signal to the other device.

2. The display device according to claim 1 .

3. The receiving unit is a playlist receiving unit that receives a playlist from the other device; A synchronization signal receiving unit that receives a synchronization signal from the other device.

2. The display device according to claim 1 .

4. the content group acquisition unit acquires a content group corresponding to the identifier of the own device from a playlist; 2. The display device according to claim 1 .

5. A central unit installed in one train, A terminal device installed in each car constituting the train and capable of communicating with the central device; a plurality of display devices installed in each carriage of the train, connected to the terminal device and to each other via a network, and repeating playback of the content group while synchronizing with the timing at which the earliest playback of the content group is completed; Equipped with The display device includes: A transmitter that transmits a synchronization signal to another device; a receiving unit for receiving a synchronization signal from the other device; a content group acquisition unit that repeatedly acquires a content group for the device itself from a playlist; a video display unit that repeatedly plays back videos based on the content group; a synchronization determination unit that, when the receiving unit receives a synchronization signal while the video display unit is displaying a current content group, cuts off playback of the current content group and plays a next content group; a synchronization signal transmission control unit that causes the transmission unit to transmit a synchronization signal to the other device when the video display unit finishes displaying a current group of contents; Equipped with the content group acquisition unit creates a list of the presence or absence of a content file from the content group, and if there is a content loss, notifies the other device of the content loss by the transmission unit; the video display unit does not play the content notified of the loss by the other device, and plays the next content of the content. A display system comprising:

6. The terminal device includes a train information transmitting unit that transmits to each of the display devices train information including at least one of a car number, a traveling direction, and a running position of the car in which the terminal device is installed, 6. The display system according to claim 5.

7. A transmitting unit transmits a synchronization signal to another device; A receiving unit receives a synchronization signal from the other device; a content group acquisition unit repeatedly acquiring a content group for the own device from a playlist; a video display unit repeatedly playing back the video based on the content group; a synchronization determination unit cutting off playback of the current content group and playing a next content group when the receiving unit receives a synchronization signal while the video display unit is displaying the current content group; a synchronization signal transmission control unit causing the transmission unit to transmit a synchronization signal to the other device when the video display unit finishes displaying the current content group; the content group acquisition unit creating a list of the presence or absence of content files from the content group, and if there is a content loss, notifying the other device of the content loss by the transmission unit; a step of the video display unit not playing the content notified of the loss by the other device, and playing a content next to the content; A display method comprising:

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