Electronic device and control method therefor

Abstract

This electronic device is used in a multi-display system in which a plurality of electronic devices are connected in a daisy chain. In the daisy chain connection, the electronic device (709) is a primary electronic device that receives a video signal first, and includes: a reception unit (7091) that receives identification data of a replica electronic device; a storage unit (7090) that stores the identification data; and an acquisition unit (7092) that determines that the replica electronic device (710, 711, 712) indicated by the identification data stored in the storage unit is connected.

Description

Electronic device and control method thereof

[0001] The present invention relates to an electronic device that can be used in a daisy-chain connected multi-display system, and a control method for the electronic device.

[0002] In a multi-display system, multiple display areas are arranged adjacent to each other vertically and horizontally, and multiple electronic devices (e.g., projectors) each project an image based on a video signal onto the target display area. By projecting an image onto each display area, a single display screen can be displayed (see, for example, Patent Document 1). In such a multi-display system, a first electronic device among the multiple electronic devices is connected via a transmission cable to a supply device that supplies a video signal, and the other electronic devices are connected to the first electronic device via electrical cables in series. The first electronic device transmits commands to each electronic device to determine its status, and can determine its status based on the response signals.

[0003] Japanese Patent Application Laid-Open No. 2005-274937

[0004] However, in such a multi-display system, the first electronic device transmits a command to the electronic device being queried via an intermediate electronic device. Therefore, when the first electronic device transmits a command to the electronic device connected most recently, the command must pass through an intermediate electronic device, and the response also passes through an intermediate electronic device. Therefore, the communication load increases as the number of electronic devices included in the multi-display system increases.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an electronic device that reduces the communication load of the electronic device used in a multi-display system, and a control method for the electronic device.

[0006] In order to solve the above-mentioned problems, one aspect of the present invention is an electronic device used in a multi-display system in which multiple electronic devices are daisy-chained, wherein in the daisy-chain connection, the electronic device is a primary electronic device that first receives a video signal, and has a receiving unit that receives identification data of a replica electronic device, a memory unit that stores the identification data, and an acquisition unit that determines that the replica electronic device indicated by the identification data stored in the memory unit is connected.

[0007] Another aspect of the present invention is a control method for electronic devices used in a multi-display system in which multiple electronic devices are daisy-chain connected, in which identification data of a replica electronic device is stored in an electronic device among the multiple electronic devices that first receives a video signal, and the replica electronic device indicated by the stored identification data is determined to be connected to the electronic device.

[0008] According to the present invention, it is possible to reduce the communication load in a multi-display system.

[0009] FIG. 1 is a schematic diagram showing the configuration of a multi-display system S according to a first embodiment. FIG. 2 is a schematic functional block diagram explaining the function of each projector in FIG. 1. FIG. 3 is a flowchart explaining the operation of the multi-display system S. FIG. 4 is a schematic diagram showing the configuration of a multi-display system Sa according to a second embodiment. FIG. 5 is a schematic functional block diagram showing a video signal supply device 102, multiple projectors, and a router 240 in the multi-display system of the second embodiment. FIG. 6 is a schematic functional block diagram explaining a state in which multiple projectors are connected in a multi-display system in a reference example. FIG. 7 is a schematic diagram showing the configuration of a primary electronic device according to a third embodiment.

[0010] A multi-display system using a primary electronic device according to one embodiment of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 is a schematic diagram showing the configuration of a multi-display system S according to a first embodiment. In the multi-display system S, each projector is connected in series. That is, the projectors are daisy-chain connected. The multi-display system S includes multiple electronic devices that display images based on video signals. The electronic devices are, for example, display devices such as projectors, liquid crystal display devices, and LED display devices. The multi-display system S includes a display device 101, a video signal supply device 102, a remote control 103, a screen 104, projectors 109, 110, 111, and 112. In this embodiment, the multi-display system S will be described as including four projectors, but the number of projectors is not limited to four and may be two, three, five, or more.

[0011] The remote control 103 transmits a control signal and a switching signal to each of the projectors (projector 109, projector 110, projector 111, and projector 112) by infrared rays. The control signal is a signal that turns the power on or off. The switching signal is a signal that switches which device receives the video signal.

[0012] Images projected from each projector (109, 110, 111, 112) are projected onto a screen 104. The screen 104 is divided into two parts both vertically and horizontally, resulting in a total of four adjacent display areas: a display area 105, a display area 106, a display area 107, and a display area 108.

[0013] In the multi-display system S, the display device 101 is connected to the video signal supply device 102 via a communication cable. The display device 101 is used as a monitor for the video signal supply device 102. The communication cable connecting the display device 101 and the video signal supply device 102 may be, for example, an HDMI (registered trademark) cable (High Definition Multimedia Interface).

[0014] The video signal supply device 102 is connected to the display device 101 via a communication cable, and is also connected to the projector 109 via a communication cable. The video signal supply terminal of the video signal supply device 102 is, for example, an HDMI output terminal, and is connected to the HDMI input terminal 109a of the projector 109 via the communication cable. The video signal supply device 102 outputs a video signal corresponding to the content to the projector 109 via the communication cable. For example, the video signal supply device 102 outputs an HDMI signal corresponding to the content via the communication cable. The HDMI signal is a signal including a video signal, an audio signal, and a control signal. This communication cable may be, for example, an HDMI (registered trademark) cable. The video signal supply device 102 also outputs the video signal and various information to the display device 101. The video signal supply device 102 is, for example, a computer. The video signal supply device 102 acquires identification data (e.g., EDID information) from the projector 109 via an HDMI (registered trademark) cable, and based on the acquired EDID information, outputs a video signal according to the optimum resolution of the projector 109 to the projector 109. The EDID information is identification data that includes information indicating the model of the electronic device itself (manufacturer name, model number, etc.) and information regarding the specifications of the electronic device itself (compatible signal formats, resolutions, etc.).

[0015] Projector 109 has a light source brightness of 20,000 lm and is assigned EDID information of (Manufacturer ID 0x00, Product ID 0x00). Manufacturer ID is identification information including information that can identify the manufacturer. Product ID is specification information that indicates the product specifications. For example, a different Product ID is assigned for each product specification, and the product specifications can be identified based on the Product ID included in the EDID information. Projector 110 has a light source brightness of 20,000 lm and is assigned EDID information of (Manufacturer ID 0x00, Product ID 0x00). Projector 111 has a light source brightness of 20,000 lm and is assigned EDID information of (Manufacturer ID 0x00, Product ID 0x00). The projector 112 is a model with a light source brightness of 17,000 lm, and is assigned EDID information (Manufacturer ID 0x00, Product ID 0x01).

[0016] The projectors (109, 110, 111, 112) are each provided with an HDMI input terminal (109a, 110a, 111a, 112a), an HDBaseT IN terminal (109i, 110i, 111i, 112i), and an HDBaseT OUT terminal (109o, 110o, 111o, 112o).

[0017] The HDBaseT IN terminal 109i of the projector 109 is not connected to other electronic devices (such as the video signal supply device 102, projector 110, projector 111, and projector 112). The HDBaseT OUT terminal 109o of the projector 109 is connected to the HDBaseT IN terminal 110i of the projector 110 via a communication cable. This communication cable can be a communication cable (e.g., a LAN cable) that can communicate signals based on HDBaseT. The HDBaseT OUT terminal 110o of the projector 110 is connected to the HDBaseT IN terminal 111i of the projector 111 via a communication cable (e.g., a LAN cable).

[0018] The HDBaseT OUT terminal 111o of the projector 111 is connected via a communication cable (e.g., a LAN cable) to the HDBaseT IN terminal 112i of the projector 112. Although it is possible to connect another projector to the HDBaseT OUT terminal 112o of the projector 112 via a communication cable (e.g., a LAN cable), no other projector is connected here.

[0019] The HDMI input terminal 110a of the projector 110, the HDMI input terminal 111a of the projector 111, and the HDMI input terminal 112a of the projector 112 can each be connected to the video signal supply device 102 or a distributor via a communication cable (e.g., an HDMI (registered trademark) cable), but nothing is connected here.

[0020] In this way, projectors 109 and 110, projectors 110 and 111, and projectors 111 and 112 are connected in series by communication cables (e.g., LAN cables), and video signals are transmitted using signals based on HDBaseT. HDBaseT LANs are capable of transmitting video signals and also of exchanging LAN commands between electronic devices via a LAN network connection. Therefore, projectors 109, 110, 111, and 112 can exchange LAN commands with each other in the same way as if they were connected to each other via a router. Therefore, for example, it is also possible for projector 109 to send a command to projector 112. Signals based on HDBaseT are also called HDBaseT signals. HDBaseT can also be said to be a LAN that can transmit or receive HDMI signals, and is capable of two-way communication.

[0021] For example, projector 109 converts a video signal input from video signal supply device 102 via an HDMI (registered trademark) cable into an HDBaseT signal, which is a signal based on HDBaseT, inside projector 109 and outputs this from HDBaseT OUT terminal 109o, which is an HDBaseT-OUT. As a result, the video signal output from projector 109 is input to HDBaseT IN terminal 110i, which is an HDBaseT-IN of projector 110. Similarly, projector 110 outputs a video signal from HDBaseT OUT terminal 110o, and the video signal is input to projector 111 from HDBaseT IN terminal 111i. The projector 111 outputs a video signal from an HDBaseT OUT terminal 111o, and the video signal is input to the projector 112 from an HDBaseT IN terminal 112i.

[0022] Here, each projector (109, 110, 111, 112) is assigned a different number in advance. By recognizing its number, each projector identifies whether it is the first projector (primary electronic device) or a second or subsequent projector (replica electronic device). Furthermore, the correspondence between the number and the display area to be projected, namely, display area 105, display area 106, display area 107, and display area 108, is predetermined, and by recognizing the number, it is determined which display area the image will be projected onto.

[0023] By connecting the projectors as described above, each projector (109, 110, 111, 112) receives as input a video signal identical to the video signal supplied from the video signal supply device 102. The projector 109 discards the portions corresponding to the upper right, lower left, and lower right areas of an image corresponding to the video signal input to the HDMI input terminal 109a, enlarges only the portion corresponding to the upper left area, and displays the image by projecting it onto the display area 105 of the screen 104. The projector 110 discards the portions corresponding to the upper left, lower left, and lower right areas of an image corresponding to the video signal input to the HDBaseT IN terminal 110i, enlarges only the portion corresponding to the upper right area, and displays the image by projecting it onto the display area 106 of the screen 104. The projector 111 displays an image corresponding to the video signal input to the HDBaseT IN terminal 111i by discarding the portions corresponding to the upper left, upper right, and lower right areas and enlarging only the portion corresponding to the lower left area, and projecting it onto a display area 107 of the screen 104. The projector 112 displays an image corresponding to the video signal input to the HDBaseT IN terminal 112i by discarding the portions corresponding to the upper left, upper right, and lower left areas and enlarging only the portion corresponding to the upper left area, and projecting it onto a display area 108 of the screen 104. With this configuration, an image corresponding to the video signal supplied from the video signal supply device 102 is displayed on the display device 101, and the image displayed on the display device 101 is also displayed on the screen 104.

[0024] Here, using four projectors to display an image on the screen 104 has the following advantages, for example: (a) Even if one projector attempts to project an image onto the entire screen 104, if the size of the screen 104 (e.g., 300 inches) is larger than the size that one projector can project, the image cannot be displayed. For this reason, using multiple projectors makes it possible to project an image onto the screen 104. (B) Even if one projector projects an image onto the entire screen 104, the brightness will be insufficient. For this reason, by dividing the screen 104 into multiple regions and using multiple projectors to project images onto different divided regions, the target brightness can be achieved.

[0025] In the multi-display system S, a projector that is closer to the video signal supply device 102 in the path connected thereto may be referred to as a front-stage projector, and a projector that is farther away may be referred to as a rear-stage projector. Furthermore, when a certain projector is used as a reference, a projector that is directly connected among the front-stage projectors may be referred to as a front-stage projector, and a projector that is directly connected among the rear-stage projectors may be referred to as a rear-stage projector.

[0026] Fig. 2 is a schematic functional block diagram illustrating the functions of each projector in Fig. 1. The projector 109 includes a CPU 202, an HDMI receiver 203 (HDMI RX 203), an HDBaseT receiver 204 (HDBaseT RX 204), an HDMI interface (PHY 205), an HDBaseT transmitter 206 (HDBaseT TX 206), an HDMI interface (PHY 207), and a LAN interface (LAN PHY 208). The CPU 202 controls the HDMI RX (203), HDBaseT RX (204), HDBaseT TX (206), and LAN PHY (208). Furthermore, the CPU 202 converts the HDMI signal input from the HDMI RX 203 into an HDBaseT signal, which is a signal compatible with HDBaseT, and supplies the converted HDBaseT signal to an external electronic device (for example, the PHY 215 of the subsequent projector 110) via the HDBaseT TX and the PHY 207. Here, the HDMI signal may be converted into an HDBaseT signal by another element instead of the CPU 202. The HDMI RX 203 receives a video signal supplied via an HDMI communication cable connected to the HDMI input terminal 109a.

[0027] The HDBaseT RX 204 receives an HDMI signal supplied from an external device. The PHY 205 is an interface capable of inputting a signal based on HDBaseT. The HDBaseT TX 206 transmits an HDMI signal to an external electronic device. The PHY 207 is an interface capable of outputting a signal based on HDBaseT. The LAN PHY 208 is an interface capable of transmitting and receiving control data.

[0028] The projector 110 includes a CPU 212, an HDMI RX 213, an HDBaseT RX 214, a PHY 215, an HDBaseT TX 216, a PHY 217, and a LAN PHY 218. The projector 111 includes a CPU 222, an HDMI RX 223, an HDBaseT RX 224, a PHY 225, an HDBaseT TX 226, a PHY 227, and a LAN PHY 228. The projector 112 includes a CPU 232, an HDMI RX 233, an HDBaseT RX 234, a PHY 235, an HDBaseT TX 236, a PHY 237, and a LAN PHY 238.

[0029] CPU 212, CPU 222, and CPU 232 have the same functions as CPU 202. Here, CPU 202 has functions in common with CPU 212, CPU 222, and CPU 232, but also has the function of executing processing to function as a primary electronic device. CPU 212, CPU 222, and CPU 232 each have the function of executing processing to function as a replica electronic device. Furthermore, CPU 202, CPU 212, CPU 222, and CPU 232 are all capable of executing processing to function as a primary electronic device and a replica electronic device, and when connected in a daisy chain, may be configured to execute processing as a primary electronic device or processing as a replica electronic device depending on whether it is assigned as a primary electronic device.

[0030] HDMI RX213, HDMI RX223, and HDMI RX233 have the same functions as HDMI RX203. HDBaseT RX214, HDBaseT RX224, and HDBaseT RX234 have the same functions as HDBaseT RX204. PHY215, PHY225, and PHY235 have the same functions as PHY205. HDBaseT TX216, HDBaseT TX226, and HDBaseT TX236 have the same functions as HDBaseT TX206. PHY217, PHY227, and PHY237 have the same functions as PHY207. LAN PHY 218 , LAN PHY 228 , and LAN PHY 238 have the same functions as LAN PHY 208 .

[0031] The router 240 relays data sent or received between connected electronic devices, but in this example, it is not connected to any of the projectors (109, 110, 111, 112). Therefore, the router 240 does not necessarily have to be provided. The router 240 may be a switching hub.

[0032] Here, nothing is connected to the LAN PHYs (208, 218, 228, 238) of the projectors (109, 110, 111, 112). Command transmission and reception between the projectors (109, 110, 111, 112) using the LAN is performed using the HDBaseT LAN of each projector (109, 110, 111, 112) without using the LAN PHYs.

[0033] The video signal supply device 102 supplies an HDMI signal to the projector 109. When the CPU 202 of the projector 109 inputs an HDMI signal via the HDMI RX 203, it supplies the HDMI signal to the HDBase RX 204. The HDBase RX 204 supplies the HDMI signal to the HDBaseT TX (206). The HDBaseT TX (206) supplies the HDMI signal from the PHY (207) to the HDBaseT RX (214) via the PHY (215) of the projector 110. The HDBaseT RX (214) supplies the HDMI signal to the HDBaseT TX (216). The HDBaseT TX (216) supplies the HDMI signal from the PHY (217) to the HDBaseT RX (224) via the PHY (225) of the projector 111. The HDBaseT RX (224) supplies the HDMI signal to the HDBaseT TX (226). The HDBaseT TX (226) supplies the HDMI signal from the PHY (227) to the HDBaseT RX (234) via the PHY (235) of the projector 112.

[0034] When the projectors are connected as shown in Fig. 2, projector 109 is the primary electronic device, projector 110 is the first replica electronic device, projector 111 is the second replica electronic device, and projector 112 is the third replica electronic device. Also, in Fig. 2, the projectors (109, 110, 111, 112) are connected in series using an HDBaseT interface, and this connection method can be called a video daisy chain connection. The same video signal is input to each of the projectors (109, 110, 111, 112) connected in this video daisy chain via the HDBaseT interface.

[0035] Here, when the PHY (207) of the projector 109 and the PHY (215) of the projector 110 are connected, in order to output a video signal, the HDBaseT TX (206) acquires EDID information, including a manufacturer ID and a product ID, stored in the register of the HDBaseT RX (214) via the PHY (207) and the PHY (215) of the projector 110. The HDBaseT TX (206) then stores the acquired EDID information in its own register. The value of this register can be acquired from the CPU (202). The manufacturer ID and product ID in this EDID are acquired when a video signal is output within the HDBaseT system.

[0036] Similarly, between the projectors 110 and 111, the HDBaseT TX (216) of the projector 110 acquires EDID information including the manufacturer ID and product ID of the HDBaseT RX (224) via the PHY (217) and the PHY (225) of the projector 111. The HDBaseT TX (216) stores the acquired EDID information in its register.

[0037] Similarly, between the projectors 111 and 112, the HDBaseT TX (226) of the projector 111 acquires EDID information including the manufacturer ID and product ID of the HDBaseT RX (234) via the PHY (227) and the PHY (235) of the projector 112. The HDBaseT TX (226) stores the acquired EDID information in its register.

[0038] Next, the operation of the multi-display system S will be described with reference to Fig. 3. Fig. 3 is a flowchart illustrating the operation of the multi-display system S.

[0039] When processing starts (step S401), the CPU (202) determines whether or not EDID data including the manufacturer ID and product ID of the first replica electronic device stored in the register of the HDBaseT TX (206) has been acquired (step S402). If the EDID data has been acquired (YES in S402), the CPU (202) recognizes that the first replica electronic device has been connected (S403). If the EDID information has not been acquired (NO in S402), the CPU (202) ends processing. The CPU (202) may end processing, or may execute processing again from step S402 after a certain period of time has elapsed.

[0040] Here, the CPU (202) of the primary electronic device (projector 109) recognizes that the first replica electronic device is connected to the primary electronic device if it can obtain the EDID information of the first replica electronic device from the HDBaseT RX in the primary electronic device. When the primary electronic device and the first replica electronic device are connected using HDBaseT, the EDID information is transmitted from the first replica electronic device to the primary electronic device, and the EDID information of the first replica electronic device is stored in the primary electronic device. By using the EDID information stored in this manner, the primary electronic device does not need to send a new LAN command to confirm whether it is connected to the first replica electronic device, thereby reducing the communication load on the LAN and preventing a decrease in CPU processing speed. In other words, the primary electronic device does not need to periodically poll using a LAN command to confirm whether the first replica electronic device is connected.

[0041] Upon recognizing that the first replica electronic device has been connected, the CPU (202) sets the internal variable n to 1 (step S404). The CPU (202) then determines whether a predetermined wait time for a notification from the nth replica electronic device has timed out (step S405). Here, n is 1, so the CPU (202) waits for a notification from the first replica electronic device (projector 110). If the wait time has timed out (step S405—YES), the CPU (202) proceeds to step S409. On the other hand, if the wait time has not timed out (step S405—NO), the CPU of the nth replica electronic device attempts to acquire EDID information (including manufacturer ID and product ID) of the (n+1)th replica electronic device, the connection partner of the nth replica electronic device (step S406). In HDBaseT, when an electronic device is connected, EDID information (including Manufacturer ID and Product ID) is transmitted from the subsequent electronic device to the preceding electronic device via the HDBaseT LAN. At this point, n=1, so if the first replica electronic device acquires EDID information including the Manufacturer ID and Product ID of the second replica electronic device (YES in step S406), the CPU (212) of the first replica electronic device recognizes that the second replica electronic device has been connected to the first replica electronic device. The CPU (212) of the first replica electronic device then transmits the Manufacturer ID and Product ID of the second replica electronic device to the primary electronic device (projector 109) via the HDBaseT LAN (step S407).

[0042] On the other hand, if the CPU (212) of the first replica electronic device is unable to acquire EDID information from the second replica electronic device (step S406-NO), the process proceeds to step S408.

[0043] After step S407, the CPU (202) of the primary electronic device adds 1 to the internal variable n (step S408), and the process proceeds to step S405.

[0044] The CPU (202) of the primary electronic device then waits for a notification from the n-th replica electronic device. In this case, n is 2, so the CPU (202) waits for a notification from the second replica electronic device (step S405).

[0045] If EDID information including the manufacturer ID and product ID of the third replica electronic device, which is the connection destination of the HDBaseT TX in the CPU (222), is obtained from the CPU (222) of the second replica electronic device (step S406—YES), the CPU (222) of the second replica electronic device recognizes that the third replica electronic device is connected to the second replica electronic device.The second replica electronic device then notifies the primary electronic device (projector 109) of the manufacturer ID and product ID of the third replica electronic device via the HDBaseT LAN via the projector 110 (step S407).Again, no polling signal from the primary electronic device is required.

[0046] Then, when the primary electronic device acquires the Manufacturer ID and Product ID of the third replica electronic device from the second replica electronic device, it adds 1 to the internal variable n and proceeds to step S405. Here, adding 1 to the internal variable n makes n = 3. The CPU (202) of the primary electronic device then waits for a notification from the nth replica electronic device. Here, n is 3, so it waits for a notification from the third replica electronic device (step S405).

[0047] If the CPU (232) of the third replica electronic device can acquire EDID information, including the manufacturer ID and product ID, of the fourth replica electronic device, which is the connection partner of the HDBaseT TX in the CPU (232), from the CPU (232) of the third replica electronic device (step S406—YES), the CPU (232) of the third replica electronic device recognizes that the fourth replica electronic device is connected to the third replica electronic device. However, in this case, no other replica electronic device is connected downstream of the third replica electronic device (projector 112). Therefore, the CPU (232) of the third replica electronic device cannot acquire EDID information of the replica electronic device connected downstream (step S406—NO), and the process proceeds to step S408.

[0048] The CPU (202) of the primary electronic device adds 1 to the internal variable n (here, n is 3) (step S408) and proceeds to step S405. The CPU (202) of the primary electronic device then waits for a notification from the nth replica electronic device. Here, n is 4, so it waits for a notification from the fourth replica electronic device (step S405). However, no other replica electronic devices are connected downstream of the third replica electronic device (projector 112). Therefore, no notification from the fourth replica electronic device arrives, resulting in a timeout (step S405—YES). The process then proceeds to step S409. Here, the replica electronic devices acquire EDID information from the replica electronic devices connected downstream. Therefore, the replica electronic device connected at the very end cannot acquire EDID information from the downstream device. Therefore, it is possible to determine the number of replica electronic devices connected in the daisy chain based on the lack of EDID information.

[0049] When the wait time set for the notification from the third replica electronic device times out, the CPU (202) of the primary electronic device recognizes that up to the third replica electronic device has been connected (step S409). Here, if the nth (n is a natural number greater than or equal to 2) replica electronic device can acquire the EDID information of the replica electronic device (the n+1th (n is a natural number greater than or equal to 2) replica electronic device) connected downstream from the HDBaseT RX of the nth (n is a natural number greater than or equal to 2) replica electronic device, it can recognize that a downstream replica electronic device has been connected. The nth (n is a natural number greater than or equal to 2) replica electronic device can then notify the primary electronic device that the n+1th (n is a natural number greater than or equal to 2) replica electronic device has been connected. This allows the CPU (202) of the primary electronic device (projector 109) to recognize that the n+1th (n is a natural number greater than or equal to 2) replica electronic device has been connected. This eliminates the need for the primary electronic device to transmit LAN commands to each of the daisy-chained replica electronic devices to transmit EDID information, thereby reducing the communication load on the LAN and reducing a decrease in CPU processing speed. In other words, the primary electronic device does not need to check whether the first replica electronic device is connected by periodically polling using LAN commands.

[0050] Next, the CPU (202) of the primary electronic device determines whether or not there is a Product ID different from the Product ID of the primary electronic device among the EDID information acquired from each replica electronic device (step S410). If there is no Product ID different from the Product ID of the primary electronic device among the EDID information acquired from each replica electronic device (step S410-NO), the CPU (202) of the primary electronic device ends the process.

[0051] On the other hand, if the CPU (202) of the primary electronic device finds a Product ID in the EDID information acquired from each replica electronic device that is different from the Product ID of the primary electronic device (step S410—YES), it transmits a LAN command to the brighter projector to dim the brightness to match the projector with the lowest brightness (step S411). For example, if the Manufacturer ID included in the EDID information of the projectors (110, 111, 112) is the same as the Manufacturer ID included in the EDID information of the projector (109) (primary electronic device) and the Product ID included in the EDID information of the projectors (110, 111, 112) is different from the Product ID included in the EDID information of the projector (109) (primary electronic device), this indicates that the products are from the same manufacturer but have different brightness levels.

[0052] For example, if the CPU 202 of the projector 109 (primary electronic device) recognizes that the brightness indicated by the Product IDs of the projectors 109, 110, and 111 is 20,000 lm and that the brightness indicated by the Product ID of the projector 112 is 17,000 lm, the CPU 202 reduces the brightness of the projector 109 to 17,000 lm and transmits commands to the projectors 110 and 111 via the HDBaseT LAN to reduce the brightness to 17,000 lm. As a result, the brightness of the projectors 109, 110, and 111 becomes 17,000 lm, which is the same as the brightness of the projector 112. This makes it possible to uniformize the brightness of the images projected onto the screen 104 from each projector without manually adjusting the brightness of each projector from a menu using a remote control or the like.

[0053] According to the embodiment described above, the CPU (201) of the primary electronic device (projector 109) can recognize that the first replica electronic device (projector 110), the second replica electronic device (projector 111), and the third replica electronic device (projector 112) are connected by obtaining the EDID information stored in the register from the HDBaseT RX (204) in the primary electronic device and receiving two notifications via HDBaseT LAN from the first replica electronic device and the second replica electronic device. In the embodiment described above, a multi-display system S with four connected projectors has been described. However, the above-described effects can be achieved with any number of projectors, including two, three, five, or more. Furthermore, the projectors may be arranged vertically and horizontally, or may be stacked vertically.

[0054] Second Embodiment Next, a multi-display system according to the second embodiment will be described. Fig. 4 is a schematic diagram showing the configuration of a multi-display system Sa according to the second embodiment. The multi-display system Sa according to the second embodiment adds a router 240 to the multi-display system S according to the first embodiment, and the method of connecting devices is different. In the multi-display system Sa in Fig. 4, parts corresponding to those in Fig. 1 are given the same reference numerals and their description will be omitted, with the differences being mainly described.

[0055] Video signal supply device 102 is connected to distributor 303 via a communication cable (for example, an HDMI (registered trademark) cable) and supplies an HDMI signal to distributor 303. Distributor 303 is connected to video signal supply device 102 via a communication cable. Distributor 303 is also connected to projector 109, projector 110, projector 111, and projector 112 via different communication cables. The communication cables used to connect distributor 303 to each projector may be, for example, an HDMI (registered trademark) cable.

[0056] The distributor 303 has a first terminal 303a, a second terminal 303b, a third terminal 303c, and a fourth terminal 303d. The first terminal 303a is connected to the HDMI input terminal 109a of the projector 109 via a communication cable. The second terminal 303b is connected to the HDMI input terminal 110a of the projector 110 via a communication cable. The third terminal 303c is connected to the HDMI input terminal 111a of the projector 111 via a communication cable. The fourth terminal 303d is connected to the HDMI input terminal 112a of the projector 112 via a communication cable. The communication cables connecting the distributor 303 and each projector can be, for example, HDMI (registered trademark) cables.

[0057] The distributor 303 supplies the HDMI signal output from the video signal supply device 102 to the projector 109, the projector 110, the projector 111, and the projector 112. That is, the distributor 303 distributes the video signal output from the video signal supply device 102 to each of the four projectors.

[0058] The router 240 is connected to the LAN PHY terminals (109p, 110p, 111p, 112p) between the projectors, respectively, and connects the projectors so that data can be communicated bidirectionally via the LAN.

[0059] 5 is a schematic functional block diagram showing the video signal supply device 102, multiple projectors, and router 240 in the multi-display system of the second embodiment. In this figure, the same functions as those in FIG. 2 are assigned the same reference numerals and their explanation will be omitted, and different functions will be mainly described.

[0060] The distributor 303 is connected to the HDMI RX 203 of the projector 109, the HDMI RX 213 of the projector 110, the HDMI RX 223 of the projector 111, and the HDMI RX 233 of the projector 112, respectively, and supplies an HDMI signal.

[0061] A terminal 240a of the router 240 is connected to the LAN PHY 208 of the projector 109. A terminal 240b of the router 240 is connected to the LAN PHY 218 of the projector 110. A terminal 240c of the router 240 is connected to the LAN PHY 228 of the projector 111. A terminal 240d of the router 240 is connected to the LAN PHY 238 of the projector 112.

[0062] In the first embodiment shown in Fig. 2, the projectors are connected to each other via an HDBaseT LAN for communication, but in the second embodiment shown in Fig. 4 and Fig. 5, the projectors are not directly connected to each other but are connected via a router 240. Therefore, in the second embodiment, the LAN cable between the PHY (207) of the projector (109) and the PHY (215) of the projector (110), the LAN cable between the PHY (217) of the projector (110) and the PHY (225) of the projector (111), and the LAN cable between the PHY (227) of the projector (111) and the PHY (235) of the projector (112) are not connected.

[0063] The LAN PHY (208) of the projector (109), the LAN PHY (218) of the projector (110), the LAN PHY (228) of the projector (111), and the LAN PHY (238) of the projector (112) are each connected to a router (240). The CPU 202 can communicate bidirectionally with the CPU via the LAN PHY of the communication partner projector among the projectors 110, 111, and 112 via the LAN PHY (208) and the router 240.

[0064] Here, the projectors (109), (110), (111), and (112) are assigned an order on the transmission path that is determined so that they are serially connected with the primary electronic device (projector 109) as the reference. Therefore, each projector can identify which projector is connected to the preceding or succeeding stage based on the number indicating this order. In other words, by assigning an order on the path that is serially connected to the primary electronic device (projector 109), the replica electronic devices (projector 110, projector 111, projector 112) are logically daisy-chain connected. Therefore, even if each projector is physically connected in parallel via the router 240, it is possible to identify which projector is the succeeding stage and obtain the EDID.

[0065] In this way, communication between the projectors can be performed via the router 240, making it possible to send and receive commands between the projectors. Operation in this configuration can be performed according to the flowchart shown in FIG. 3. Therefore, as in the first embodiment, it is possible to reduce a decrease in CPU processing speed. In other words, the primary electronic device does not need to check whether the first replica electronic device is connected by periodically polling using a LAN command.

[0066] <<Reference Example>> Next, a reference example will be described. Fig. 6 is a schematic functional block diagram illustrating a state in which multiple projectors are connected in a multi-display system in the reference example. The multi-display system in Fig. 6 is similar to Fig. 2 in terms of the configuration in which multiple projectors are connected, but differs in the processing and functions for transmitting or receiving EDID information. The same or similar functions are assigned the same reference numerals as Fig. 2 and their description will be omitted, and the following description will mainly focus on the parts that are different from Fig. 2. The multi-display system in the reference example includes projectors (509, 510, 511, 512).

[0067] A first replica electronic device (projector 510), a second replica electronic device (projector 511), and a third replica electronic device (projector 512) are connected to a projector (509), which is an example of a primary electronic device. The CPU (202) of the projector (509) polls the CPU of each replica electronic device by sending a LAN command to the CPU of each replica electronic device in the subsequent stage to determine whether or not the replica electronic device is connected to the subsequent stage.

[0068] The route by which the CPU (202) makes an inquiry to the CPU (211) of the projector (510), which is the first replica electronic device, is the route in the order of CPU (202), HDBaseT TX (206), PHY (207), PHY (215), HDBaseT RX (214), and CPU (212).Next, the route by which a reply is sent from the first replica electronic device to the primary electronic device is the route in the order of CPU (212), HDBaseT RX (214), PHY (215), PHY (207), HDBaseT TX (206), and CPU (202).

[0069] The route for making an inquiry to the second replica electronic device (projector 511) follows the order of CPU (202), HDBaseT RX (206), PHY (207), PHY (215), HDBaseT RX (214), HDBaseT TX (216), PHY (217), PHY (225), HDBaseT RX (224), and CPU (222). The response path from the second replica electronic device (projector 511) to the primary electronic device follows the order of CPU (222), HDbBaseT RX (224), PHY (225), PHY (217), HDBaseT TX (216), HDBaseT RX (214), PHY (215), PHY (207), HDBaseT TX (206), and CPU (202).

[0070] The route for making an inquiry to the third replica electronic device (projector 512) follows the order of CPU (202), HDBaseT RX (206), PHY (207), PHY (215), HDBaseT RX (214), HDBaseT TX (216), PHY (217), PHY (225), HDBaseT RX (224), HDBaseT TX (226), PHY (227), PHY (235), HDBaseT RX (234), and CPU (232). The response path from the third replica electronic device (projector 512) to the primary electronic device follows the order of CPU (232), HDBaseT RX (234), PHY (235), PHY (227), HDBaseT TX (226), HDBaseT RX (224), PHY (225), PHY (217), HDBaseT TX (216), HDBaseT RX (214), PHY (215), PHY (207), HDBaseT TX (206), and CPU (202).

[0071] In other words, the CPU (202) of the primary electronic device (projector 509) must make inquiries via the above-mentioned path to grasp the status of each of the first, second, and third replica electronic devices. Therefore, an inquiry command is issued to each of the first, second, and third replica electronic devices, and a corresponding response command is issued in return, resulting in six commands. Furthermore, the need for polling at regular intervals creates a communication load due to the LAN commands. Furthermore, the long path required places a heavy processing load on each of the CPUs belonging to this path: the CPU (202) of the primary electronic device, the CPU (212) of the first replica electronic device, the CPU (222) of the second replica electronic device, and the CPU (232) of the third replica electronic device. Furthermore, if a remote control operation (e.g., a command) is input to the primary electronic device from the remote control during polling, an interrupt process must be performed to transfer the operation from the primary electronic device to each replica electronic device. Therefore, when an operation input is received from the remote control, the transfer of the operation input to the replica electronic devices via the LAN is delayed.

[0072] In contrast, according to the first and second embodiments, the number of communications and communication load due to LAN commands can be reduced, and a decrease in CPU processing speed can be reduced. Furthermore, according to the first and second embodiments, polling at regular intervals using LAN commands is not performed, so even when operation details of the remote control are input from the remote control 103 to the projector 109, which is the primary electronic device, an interruption to the LAN command processing does not occur. Therefore, even if operation details are input from the remote control to the primary electronic device, a delay in the transfer of the operation details of the remote control to the replica electronic device via the LAN can be avoided.

[0073] Third Embodiment Next, a primary electronic device according to the third embodiment will be described. FIG. 7 is a schematic diagram showing the configuration of a primary electronic device according to the third embodiment. The primary electronic device 709 is connected to the video signal supply device 102 on its upstream side via a communication cable and to at least one replica electronic device on its downstream side, constituting a multi-display system capable of projecting an image based on a video signal onto a screen. Here, for example, three replica electronic devices, replica electronic device 710, replica electronic device 711, and replica electronic device 712, are connected to the primary electronic device 709. The replica electronic devices are connected to each primary electronic device 709 via a communication cable in a daisy chain configuration. All or part of the video signal is transmitted from the primary electronic device 709 to the downstream replica electronic device.

[0074] Each of the multiple replica electronic devices (710, 711, 712) transmits identification data assigned to itself to the replica electronic device or primary electronic device connected to the primary electronic device in the daisy-chain connection. When the replica electronic device or replica electronic device is connected to the preceding device, the replica electronic device transmits the identification data assigned to itself to the preceding device. Here, the identification data includes a manufacturer ID and a product ID. The replica electronic device may transmit the identification data when it detects that the primary electronic device or replica electronic device is connected to the preceding device via a communication cable. For example, the replica electronic device and the preceding device may detect that the two devices are connected to each other by a communication cable when both devices are powered on. Alternatively, the replica electronic device and the preceding device may detect that the two devices are connected to each other by a communication cable when at least one of the replica electronic device and the preceding device is powered off, and then the two devices are connected to each other by a communication cable when both devices are powered on. In this case, the identification data is transmitted without the preceding device transmitting a command to transmit the identification data to the succeeding device. Such identification data can be transmitted using, for example, a function included in HDBase T. Primary electronic device 709, replica electronic device 710, replica electronic device 711, and replica electronic device 712 may each be a projector or another display device such as a liquid crystal display device or an LED display device.

[0075] The primary electronic device 709 has a storage unit 7090, a receiving unit 7091, an acquiring unit 7092, and a first control unit 7093. The storage unit 7090 stores various data. The storage unit 7090 is configured by a storage medium such as a hard disk drive (HDD), flash memory, an electrically erasable programmable read-only memory (EEPROM), a random access read / write memory (RAM), a read-only memory (ROM), or any combination of these storage media. This storage unit 7090 can be, for example, a non-volatile memory.

[0076] The receiving unit 7091 receives identification data of the replica electronic device transmitted from the replica electronic device in response to the connection of the replica electronic device. The received identification data is stored in the storage unit 7090. The receiving unit 7091 may acquire identification data from each replica electronic device after receiving a video signal from the video signal supply device 102. Here, the electronic device closer to the primary electronic device in the daisy chain connection is the preceding electronic device, and the electronic device closer to the terminal replica electronic device is the succeeding electronic device.

[0077] A plurality of electronic devices (primary electronic device, replica electronic device) are connected to other electronic devices using an HDBaseT interface. A receiving unit 7091 receives identification data via the HDBaseT interface.

[0078] If the identification data is stored in the storage unit 7090, the acquisition unit 7092 determines that the replica electronic device indicated by the identification data has been connected. In other words, upon receiving the identification data, the acquisition unit 7092 determines that the replica electronic device has been connected. Furthermore, the acquisition unit 7092 acquires the number of connected replica electronic devices based on the number of pieces of identification data received. The acquisition unit 7092 determines whether the time set as the waiting time has expired, and acquires the number of connected replica electronic devices based on the number of pieces of identification data that were received before the expiration of the waiting time.

[0079] The first control unit 7093 controls the primary electronic device and the replica electronic device so that their brightness levels are the same based on the product IDs included in the identification data received from the replica electronic devices. Specifically, the first control unit 7093 determines whether the product IDs included in the identification data received from the replica electronic devices are the same as the product IDs included in the identification data assigned to the primary electronic device. If they are different, the first control unit 7093 controls the primary electronic device to project at the lowest brightness level indicated by the product IDs. Here, the product IDs are also replica electronic device specification information. Furthermore, if the first control unit 7093 determines that the brightness levels are different, it sends a command to the replica electronic device to project at the lowest brightness level indicated by the product IDs.

[0080] The receiving unit 7091, the acquiring unit 7092, and the first control unit 7093 may be configured by a processing unit such as a CPU (Central Processing Unit) or a dedicated electronic circuit.

[0081] In addition, in the first to third embodiments described above, examples of multi-display systems are disclosed in International Application No. PCT / JP2023 / 034504, the disclosure of which is incorporated herein by reference in its entirety and is incorporated herein by reference as part of this specification.

[0082] 1 may be recorded on a computer-readable recording medium, and the program may be read into a computer system and executed to perform construction management. Note that the term "computer system" here includes hardware such as the OS and peripheral devices.

[0083] Furthermore, if a WWW system is used, the term "computer system" also includes the homepage provision environment (or display environment). Furthermore, "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into computer systems. Furthermore, "computer-readable recording medium" also includes devices that retain programs for a certain period of time, such as volatile memory within a computer system that serves as a server or client. The program may be one that realizes part of the aforementioned functions, or it may be one that realizes the aforementioned functions in combination with a program already stored in the computer system. The program may also be stored on a designated server, and distributed (e.g., downloaded) via a communication line in response to requests from other devices.

[0084] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0085] 101... Display device 102... Video signal supply device 103... Remote control 104... Screen 105, 106, 107, 108... Display area 109, 110, 111, 112, 509, 510, 511, 512... Projector 109a, 110a, 111a, 112a... HDMI input terminal 109i, 110i, 111i, 112i... IN terminal 109o, 110o, 111o, 112o... OUT terminal 109p, 110p, 111p, 112p... LAN PHY terminal 203, 213, 223, 233... HDMI receiver (HDMI RX) 204, 214, 224, 234... HDBaseT receiver (HDBaseT RX) 205, 215, 225, 235... HDMI interface (PHY) 206, 216, 226, 236... HDBaseT transmitter (HDBaseT TX) 207, 217, 227, 237... HDMI interface (PHY) 208, 218, 228, 238... LAN interface (LAN PHY) 240... Router 240a, 240b, 240c, 240d... Terminals 303... Distributor 303a... First terminal 303b... Second terminal 303c... Third terminal 303d... Fourth terminal 709... Primary electronic device 710, 711, 712... Replica electronic devices 7090... Storage unit 7091... Receiving unit 7092... Acquisition unit 7093... First control unit S, Sa... Multi-display system

Claims

1. An electronic device used in a multi-display system in which multiple electronic devices are daisy-chained, wherein in the daisy-chain connection, the electronic device is a primary electronic device that first receives a video signal, and has: a receiving unit that receives identification data of a replica electronic device; a memory unit that stores the identification data; and an acquisition unit that determines that the replica electronic device indicated by the identification data stored in the memory unit is connected.

2. The electronic device according to claim 1, wherein the replica electronic device comprises a first replica electronic device and a second replica electronic device connected downstream of the first replica electronic device, and the receiving unit receives identification data of the first replica electronic device and identification data of the second replica electronic device.

3. The electronic device according to claim 2, wherein the receiving unit receives the identification data of the second replica electronic device via the first replica electronic device.

4. The electronic device according to claim 2, wherein the acquisition unit acquires the number of connected replica electronic devices based on the number of pieces of identification data stored in the storage unit.

5. The electronic device according to claim 2, further comprising a control unit that compares first specification information included in the identification data of the first replica electronic device with second specification information included in the identification data of the second replica electronic device, and controls the brightness of the replica electronic device with a high brightness specification so that the brightness of the first replica electronic device and the brightness of the second replica electronic device are the same.

6. The electronic device according to claim 2, wherein the electronic device is connected to the replica electronic device using an HDBaseT interface, and the receiving unit receives the identification data via the HDBaseT interface.

7. The electronic device according to any one of claims 1 to 6, wherein the electronic device is a display device.

8. A control method for electronic devices used in a multi-display system in which a plurality of electronic devices are daisy-chained, the method comprising: storing identification data of a replica electronic device in an electronic device among the plurality of electronic devices that first receives a video signal; and determining that the replica electronic device indicated by the stored identification data is connected to the electronic device.

9. The method for controlling electronic devices according to claim 8, wherein the replica electronic device has a first replica electronic device and a second replica electronic device connected downstream of the first replica electronic device, and receives identification data of the first replica electronic device and identification data of the second replica electronic device.

10. The method of controlling an electronic device according to claim 9, wherein the identification data of the second replica electronic device is received via the first replica electronic device.

11. The method for controlling an electronic device according to any one of claims 8 to 10, wherein the electronic device is a display device.

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