Communication system, terminal device, and method for controlling communication system

In a display system, one tablet terminal transmits control information to another tablet terminal. If the another tablet terminal receives the control information from the one tablet terminal, the another tablet terminal starts executing an application and starts communicating with a projector. The one tablet terminal transmits, to the projector, display instruction information instructing the another tablet terminal to display information. The projector receives the display instruction information from the one tablet terminal and transmits the display instruction information to the another tablet terminal currently connected to the projector. The another tablet terminal displays, on a touch panel, information designated by the display instruction information, if the another tablet terminal receives the display instruction information from the projector while executing the application.

The entire disclosure of Japanese Patent Application No. 2017-163068, filed Aug. 28, 2017 is expressly incorporated by reference herein.

BACKGROUND

1. Technical Field

The present invention relates to a communication system, a terminal device, and a method for controlling a communication system.

2. Related Art

According to the related art, a system which allows a plurality of terminals to operate is known (see, for example, JT-A-2003-36218). The system disclosed in JP-A-2003-36718 includes a teacher terminal used by a teacher and a plurality of student terminals used by students. A server multicasts and distributes teaching material information designated by the teacher terminal. The student terminals show a display based on the teaching material information.

In the related-art system, before starting operation, each terminal needs to be ready to communicate with the other terminals and the server. For example, JR-A-2003-36218 discloses that the system needs work such as turning on the power of the student terminals and thus starting up the student terminals before starting a lesson, setting a destination address for the student terminals, and having the students start the student terminals to get ready for the lesson. Such work puts a heavy burden on the user using a terminal or a technical expert carrying out work in place of the user.

SUMMARY

An advantage of some aspects of the invention is that, in a system which allows a plurality of devices including a terminal to operate, the work of getting the terminal ready to communicate with the other devices can be carried out more easily.

An aspect of the invention is directed to a communication system including: a display device; a first terminal which has a display unit displaying an image and a control unit executing an application and which communicates with an external device including the display device; and a second terminal which communicates with the first terminal and the display device. The second terminal transmits control information to the first terminal. If the first terminal receives the control information from the second terminal, the first terminal starts executing the application via the control unit, causes the control unit to connect to the display device by a function of the application, and starts communicating with the display device. The second terminal transmits, to the display device, display instruction information instructing the first terminal to display information. The display device receives the display instruction information from the second terminal and transmits the display instruction information to the first terminal currently connected to the display device. The first terminal causes the display unit to display information designated by the display instruction information, if the first terminal receives the display instruction information from the display device while executing the application.

This configuration enables the second terminal to cause the first terminal to start executing the application and thus enables the first terminal to connect to the display device, based on a function of this application. Thus, with the use of the second terminal, the first terminal can easily be enabled to communicate with the display device. Also, transmitting the display instruction information from the second terminal to the display device enables the first terminal to display information. After the first terminal is connected to the display device, transmitting information from the second terminal to the display device enables the first terminal to operate. This can be realized even if the processing capability of the second terminal is low. Thus, a system can be realized in which an operation of the second terminal by the user can cause an application installed in the first terminal to operate.

The aspect of the invention may be configured such that the first terminal is able to execute a normal operation state where the control unit can execute the application and a power-saving state where the execution of the application and the display by the display unit are stopped, and the first terminal shifts to the normal operation state and executes the application, if the first terminal receives the control information from the second terminal when in the power-saving state.

This configuration enables the second terminal to cause the first terminal to start executing the application from the power-saving state. Thus, the operation to return the first terminal from the power-saving state to the normal operation state can be omitted. Even if the first terminal is scheduled to be used, there is no need to return the first terminal to the normal operation state from the power-saving state in advance. Therefore, the first terminal can wait in the power-saving state, thus saving power.

The aspect of the invention may be configured such that, if the first terminal is connected to the display device by a function of the application, the display device generates connection information indicating the first terminal currently connected to the display device, and the display device transmits the display instruction information to the first terminal, based on the connection information, if the display device receives the display instruction information from the second terminal.

With this configuration, the display device generates connection information about the first terminal and transmits the display instruction information to the first terminal, based on the connection information, thus causing the first terminal to display information. Thus, the display device can efficiently manage the connection state with the first terminal.

The aspect of the invention may be configured such that the first terminal has an operation unit, and after starting executing the application, the first terminal shifts to an operation limiting mode where acceptance of an operation by the operation unit is limited, based on a function of the application.

This configuration can prevent an operation on the first terminal from disturbing the state of control by the second terminal and the display device.

The aspect of the invention may be configured such that the second terminal transmits information to be displayed by the first terminal and the display instruction information to the display device, and the first terminal causes the display unit to show a display based on the information, according to the display instruction information received from the display device.

This configuration enables the first terminal to execute the display, based on the information transmitted from the second terminal to the display device. Therefore, the load on the second terminal can be reduced when the information to be displayed by the first terminal needs to be distributed from the second terminal.

The aspect of the invention may be configured such that the second terminal transmits the display instruction information designating information to be displayed by the first terminal, to the display device, and the first terminal acquires the information designated by the display instruction information received from the display device and cause the display unit to show a display based on the acquired information.

With this configuration, the second terminal designates the information to be displayed by the first terminal and this causes the first terminal to show a display. Therefore, the load on the second terminal when causing the first terminal to display information can be reduced further.

The aspect of the invention may be configured such that the first terminal, after causing the control unit to start executing the application, transmits information representing content of display on the display unit to the display device, based on a function of the application.

This configuration enables the display device to process the content to be displayed by the first terminal.

Another aspect of the invention is directed to a terminal device including a communication unit capable of communicating with a display device and an external terminal device, a display unit, and a control unit executing an application. The terminal device can execute a normal operation state where the control unit can execute the application and a power-saving state where the execution of the application and a display by the display unit are stopped. If the communication unit receives control information transmitted from the external terminal device when the terminal device is in the power-saving state, the control unit shifts to the normal operation state. The control unit starts executing the application. The terminal device connects to the display device and starts communicating, based on a function of the application. If display instruction information s transmitted from the display device during the execution of the application, the terminal device causes the display unit to display information designated by the display instruction information.

This configuration enables the external terminal device to cause the terminal device to start executing the application and thus enables the terminal device to connect to the display device, based on a function of this application. Thus, with the use of the external terminal device, the terminal device can easily be enabled to communicate with the display device.

Still another aspect of the invention is directed to a method for controlling a communication system including: a display device; a first terminal which has a display unit displaying an image and a control unit executing an application and which communicates with an external device including the display device; and a second terminal which communicates with the first terminal and the display device. The method includes: causing the second terminal to transmit control information to the first terminal; causing the first terminal to receive the control information from the second terminal, start executing the application via the control unit, cause the control unit to connect to the display device by a function of the application, and start communicating with the display device; causing the second terminal to transmit, to the display device, display instruction information instructing the first terminal to display information; causing the display device to receive the display instruction information from the second terminal and transmit the display instruction information to the first terminal currently connected to the display device; and causing the first terminal to receive the display instruction information transmitted from the display device while the first terminal is executing the application, and display, via the display unit, information designated by the display instruction information received from the display device.

This configuration enables the second terminal to cause the first terminal to start executing the application and thus enables the first terminal to connect to the display device, based on a function of this application. Thus, with the use of the second terminal, the first terminal can easily be enabled to communicate with the display device. Also, transmitting the display instruction information from the second terminal to the display device enables the first terminal to display information. After the first terminal is connected to the display device, transmitting information from the second terminal to the display device enables the first terminal to operate. This can be realized even if the processing capability of the second terminal is low. Thus, a system can be realized in which an operation of the second terminal by the user can cause an application installed in the first terminal to operate.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

FIG. 1shows a schematic configuration of a display system1(communication system).

The display system1has a projector100(display device) which projects an image on a screen SC. In the display system1, a tablet terminal2and a tablet terminal3are connected to the projector100in such a way as to be able to communicate data. The number of tablet terminals2and3forming the display system1is not limited. Each of the tablet terminal2and the tablet terminal3may be a single tablet terminal or may come in a plural number. This embodiment shows an example where the display system1includes one tablet terminal2and a plurality of tablet terminals3.

The tablet terminal2and the tablet terminal3are an example of a portable computer used by a user. Each of the tablet terminals2,3is a mobile terminal having a flat plate-like main body with a built-in battery (not illustrated). Each of the tablet terminals2,3has at least an operation unit operated by the user, a display unit which displays an image or the like, and a control unit which executes a control function. Specifically, the tablet terminal2has a touch panel201as an operation unit and display unit, and has a control unit210. The tablet terminal3has a touch panel301as an operation unit and display unit, and has a control unit310.

The tablet terminal2corresponds to a second terminal. The tablet terminal3corresponds to a first terminal.

The tablet terminal2and the tablet terminal3are allocated, for example, to users having different roles. The user operating the tablet terminal2is, for example, moderator. The user using the tablet terminal3is participant. For example, if the display system1is used in an education, the user diving the education (for example, a teacher) uses the tablet terminal2and the user receiving the education (for example, a student) uses the tablet terminal3.

The projector100projects an image based on data transmitted from the tablet terminal2or the tablet terminal3. The projector100may be connected to an image supply device such as a PC (personal computer) or a media playback device for playing back a DVD or the like, and may project an image based on an image signal outputted from the image supply device.

Each of the touch panels201,301includes a display panel having a liquid crystal display panel or organic EL panel, and a touch sensor for detecting a touch operation, on top of the display panel. The tablet terminals2,3detect a touch of a user's finger or hand on the touch panels201,301and execute an operation based on the detected touch position. The touch panel301is equivalent to the display unit of the tablet terminal3.

In the display system1, the projector100and the tablet terminal2are connected in such a way as to be able to communicate with each other, and the projector100and the tablet terminal3are connected in such a way as to be able to communicate with each other. The tablet terminal2and the tablet terminal3can also communicate with each other. As a configuration example, the display system1includes a communication device4. The communication device4forms a wireless communication network including the tablet terminals2,3. The communication device4and the projector100are connected in such a way as to be able to communicate with each other via a cable.

The communication method between devices in the display system1is not limited to the above configuration. The tablet terminal2and the tablet terminal3may execute, for example, direct communication in an ad-hoc mode of wireless LAN (local area network) The projector100may be configured to execute wireless communication with the tablet terminal2and/or the tablet terminal3, without having the communication device4in the display system1. The projector100may also be configured to execute wireless communication with the communication device4.

FIG. 2is a functional block diagram of the tablet terminal2and the tablet terminal3.

The tablet terminal has a communication I/F (interface) unit203and an I/F (interface) unit204. The communication I/F unit203executes communication with an external device. The communication I/F unit203may be configured to execute wired communication such as Ethernet (trademark registered). However, in this embodiment, the communication I/F unit203executes wireless communication such as wireless LAN (including WiFi (trademark registered)) or Bluetooth (trademark registered). The tablet terminal2executes wireless communication with the communication device4via the communication I/F unit203. As described above, the tablet terminal2may execute direct wireless communication with the tablet terminal3via the communication I/F unit203.

The I/F unit204is an interface connecting an external device to the tablet terminal2. The I/F unit204is, for example, a wired communication interface which has a connector for wired connection to connect to the external device via a wire, and an interface circuit supporting this connector. Specifically, IEEE 1394, USB (universal serial bus) or the like can be employed. Also, MHL (trademark registered) (mobile high-definition link), HDMI (trademark registered) (high-definition multimedia interface) or the like may be employed.

The tablet terminal2includes a control unit210, a display unit205, an input unit206, and a storage unit220. These units, along with the communication I/F unit203and the I/F unit204, are connected to each other via a bus207.

The control unit210has a processor (not illustrated) such as a CPU (central processing unit) or microcomputer. The control unit210causes the processor to execute a program, thus controlling each part of the tablet terminal2. The control unit210may have a ROM (read only memory) which stores a control program executed by the processor in a non-volatile manner, and a RAM (random access memory) forming a work area of the processor. The control unit210causes the processor to execute the program stored in the ROM and a program stored in the storage unit220and thus implements various functions of the tablet terminal2by the collaboration of the software and hardware.

The display unit205and the input unit206are connected to the touch panel201. The display unit205displays various screens on the touch panel201under the control of the control unit210. The input unit206detects a touch operation on the touch panel201and outputs coordinate data representing the position of the detected operation to the control unit210.

If the tablet terminal2has hardware keys such as a power button (not illustrated) and a home button (not illustrated), the input unit206detects an operation of these hardware keys and outputs an operation signal representing the operated key to the control unit210.

The storage unit220stores a program executed by the control unit210and various data in a non-volatile manner. The storage unit220stores an OS (operating system)221, an application program222, communication setting data223, terminal management data224, and content data225.

The OS221is a program executed by the control unit210. The OS221is loaded and executed by the control unit210at the startup of the tablet terminal2and executes basic functions of the tablet terminal2. The OS221provides various basic functions as a platform where the application program222is executed. For example, as the control unit210executes the application program222, the application program222invokes the function of the OS221is an API (application programming interface) or the like and thus operates.

The application program222is a program executed by the control unit210and implements functions of the tablet terminal2. The application program222corresponds to one or a plurality of functions of the tablet terminal2. The tablet terminal2can be configured to have a plurality of application programs222corresponding to a plurality of functions. For example, the tablet terminal2has application programs222corresponding to the functions of playing back the content data225, managing the tablet terminal3, various settings, sending and receiving messages, editing documents, viewing documents, drawing, and the like.

A plurality of application programs222can be installed in the tablet terminal2. In this case, the storage unit220stores an execution file forming the application programs222installed in the tablet terminal2, and a setting file which defines an environment or the like for execution.

In this embodiment, the application program222for managing the tablet terminal3is installed in the tablet terminal2. By causing the control unit210to execute the application program222for managing the tablet terminal3, the tablet terminal2can execute the function of transmitting information to the tablet terminal3and the projector100, or the like.

The control unit210executes the application programs222according to an operation on the touch panel201, a preset schedule, or a command or the like received via the communication I/F unit203or the I/F unit204.

The communication setting data223is setting data for communicating with the projector100via the communication unit203. Specifically, communication setting data223includes information used by the tablet terminal2to access the projector100and establish communication with the projector100. For example, the communication setting data223includes the network address of the projector100in the communication network including the projector100and the tablet terminal2. The communication setting data223may include an ID and/or password for authentication transmitted to the projector100from a terminal such as the tablet terminal2, or other information, when the projector100authenticates the terminal such as the tablet terminal2. The communication setting data223may also include information for authentication used by the tablet terminal2to authenticate the projector100.

The terminal management data224includes information about the tablet terminal3forming the display system1. Specifically, the terminal management data224includes, for example, a unique ID of each tablet terminal3as information that can identify each tablet terminal3. The terminal management data224may also include the network address of each tablet terminal3in the communication network including the tablet terminal2and the tablet terminal3. The terminal management data224may also include an ID or password for authentication used by the tablet terminal3to authenticate the tablet terminal2or by the tablet terminal2to authenticate the tablet terminal3.

The display system1may use only one or some of the tablet terminals3forming the display system1in an event (lesson) carried out by the moderator operating the tablet terminal2. in this case, the terminal management data224includes information about the tablet terminal3that is used.

The content data225is data for display made up of a still image or dynamic image (video). The content data225may also include audio data.

The control unit210has an input processing unit211, a communication control unit212, a display control unit213, and a power-supply control unit214, as functional blocks representing functions of the control unit210. These functional blocks are implemented by the collaboration of the software and hardware as the processor of the control unit210executes a program stored in the storage unit220or the ROM (not illustrated). For example, the OS221may include the functions of the input processing unit211, the communication control unit212, the display control unit213, and the power-supply control unit214. A part or these functional blocks may be implemented by the application program222.

The input processing unit211specifies the content of an input, based on the operation position of a touch operation detected by the input unit206. If an operation signal representing an operation of a hardware key is inputted from the input unit206, the input processing unit211detects the operation of the hardware key.

The communication control unit212controls the communication I/F unit203and the I/F unit204and thus executes communication between the tablet terminal2and an external device. The communication control unit212executes, for example, wireless communication with the tablet terminal3or the projector100via the communication I/F unit203.

The display control unit213controls and causes the display unit205to display various images on the touch panel201. The display control unit213carries out processing to change the display on the touch panel201according to the input content specified by the input processing unit211. The display control unit213also executes processing to play back the content data225stored in the storage unit220and causes the display unit205to display an image based on the content data225.

The power-supply control unit214controls the operation state of each part of the tablet terminal2. Specifically, the power-supply control unit214switches the operation state of the tablet terminal2between a normal operation state, a standby state (power-saving state), and a halt state. The halt state is the state where the power of the tablet terminal2is off. The standby state is the power-saving state of the tablet terminal2and is also called a sleep state. In the tablet, terminal2in the standby state, the I/F unit204, the display unit205, and the input unit206stop, and the control unit210and the storage unit220operate intermittently. This reduces power consumption.

The tablet terminal3is a terminal device configured similarly to the tablet terminal2. The tablet terminal3has a communication I/F unit303, an I/F unit304, a display unit305, an input unit306, a control unit310, and a storage unit320. These units are connected to each other via a bus307.

The communication I/F unit303(communication unit) is configured, for example, similarly to the communication I/F unit203and executes communication with an external device such as the projector100or the tablet terminal2. The communication I/F unit303may execute communication via the communication device4or may execute direct wireless communication with the tablet terminal2or the projector100.

The I/F unit304is an interface connecting an external device to the tablet terminal3and is configured, for example, similarly to the I/F unit204.

The control unit310has a processor (not illustrated) such as a CPU or microcomputer. The control unit310causes the processor to execute a program, thus controlling each part of the tablet terminal3. The control unit310may have a ROM which stores a control program executed by the processor in a non-volatile manner, and a RAM forming a work area of the processor. The control unit310causes the processor to execute the program stored in the ROM and a program stored in the storage unit320and thus implements various functions of the tablet terminal3by the collaboration of the software and hardware.

The display unit305and the input unit306are connected to the touch panel301. The display unit305displays various screens on the touch panel301under the control of the control unit310. The input unit306detects a touch operation on the touch panel301and outputs coordinate data representing the position of the detected operation to the control unit310.

If the tablet terminal3has hardware keys such as a power button (not illustrated) and a home button (not illustrated), the input unit306detects an operation of these hardware keys and outputs an operation signal representing the operated key to the control unit310.

The storage unit320stores a program executed by the control unit310and various data in a non-volatile manner. The storage unit320stores an OS321, an application program322, communication setting data323, and terminal management data324.

The OS321is a program executed by the control unit310. The OS321is loaded and executed by the control unit310at the startup of the tablet terminal3and executes basic functions of the tablet terminal3. The OS321provides various basic functions as a platform where the application program322is executed. For example, as the control unit310executes the application program322, the application program322invokes the function of the OS321via an API and thus operates.

The application program322(application) is a program executed by the control unit310and implements functions of the tablet terminal3. The application program322corresponds to one or a plurality of functions of the tablet terminal3. The tablet terminal3can be configured to have a plurality of application programs322corresponding to a plurality of functions. For example, the tablet terminal3has application programs322corresponding to the functions of managing the tablet terminal3, various settings, sending and receiving messages, editing documents, viewing documents, drawing, and the like.

A plurality of application programs322can be installed in the tablet terminal3. In this case, the storage unit320stores an execution file forming the application programs322installed in the tablet terminal3, and a setting file which defines an environment or the like for execution.

In this embodiment, the application program322for connecting to the projector100is installed in the tablet terminal3. By causing the control unit310to execute the application program322, the tablet terminal3connects to and establishes wireless communication with the projector100. The tablet terminal3also displays an image on the touch panel301based on the terminal management data324or the like, according to a command transmitted from the projector100.

The control unit310executes the application programs322according to an operation on the touch panel301, a preset schedule, or a command or the like received via the communication I/F unit303or the I/F unit304.

The communication setting data323is setting data for communicating with the projector100via the communication I/F unit303. Specifically, the communication setting data323includes information used by the tablet terminal3to access the projector100and establish communication with the projector100. For example, the communication setting data323includes the network address of the projector100in the communication network including the projector100and the tablet terminal3. The communication setting data323may include an ID and/or password for authentication transmitted to the projector100from a terminal such as the tablet terminal3, or other information, when the projector100authenticates the terminal such as the tablet terminal3. The communication setting data323may also include information for authentication used by the tablet terminal3to authenticate the projector100.

The terminal management data324is data for the tablet terminal3to display an image or the like on the touch panel301. The terminal management data324is made up of, for example, image data, video data, document data, or the like and is stored in a file format. The storage unit320can store a plurality of terminal management data324and can univocally specify the terminal management data324, based on the file name of the terminal management data324and its file path in the storage unit320. For example, the terminal management data324is a PDF (portable document format) file or presentation file.

The tablet terminal3may store the terminal management data324having a file path and a file name that are designated in advance, and the tablet terminal2may have the file path and the file name of the terminal management data324. In this case, the terminal management data224stored in the tablet terminal2includes information specifying the tablet terminal3and the file path and the file name of the terminal management data324stored in the tablet terminal3.

The tablet terminal3may also acquire data from the projector100, the tablet terminal2or other devices via the communication I/F unit303or the I/F unit304, and store the acquired data as the terminal management data324.

The control unit310has an input processing unit311, a communication control unit312, a display control unit313, and a power-supply control unit314, as functional blocks representing functions the control unit310. These functional blocks are implemented by the collaboration of the software and hardware as the processor of the control unit310executes a program stored in the storage unit320or the ROM (not illustrated). For example, the OS321may include the functions of the input processing unit311, the communication control unit312, the display control unit313, and the power-supply control unit314. A part of these functional blocks may be implemented by the application program322.

The input processing unit311specifies the content of an input, based on the operation position of a touch operation detected by the input unit306. If an operation signal representing an operation of a hardware key is inputted from the input unit306, the input processing unit311detects the operation of the hardware key.

The communication control unit312controls the communication I/F unit303and the I/F unit304and thus executes communication between the tablet terminal3and an external device. The communication control unit312executes, for example, wireless communication with the tablet terminal2or the projector100via the communication I/F unit303.

The display control unit313controls and causes the display unit305to display various images on the touch panel301. The display control unit313carries out processing to change the display on the touch panel301according to the input content specified by the input processing unit311.

The power-supply control unit314controls the operation state of each part of the tablet terminal3. Specifically, the power-supply control unit314switches the operation state of the tablet terminal3between a normal operation state, a standby state, and a halt state. The halt state is the state where the power of the tablet terminal3is off. The standby state is the power-saving state of the tablet terminal3. In the tablet terminal3in the standby state, the I/F unit304, the display unit305, and the input unit306stop, and the control unit310and the storage unit320operate intermittently. This reduces power consumption.

In the standby state, the tablet terminal3can receive a command via the communication I/F unit303. That is, in the standby state, the communication I/F unit303is enabled to detect and receive a wireless signal. To receive a wireless signal, the communication I/F unit303executes a reception operation of periodically trying to receive a wireless signal. Specifically, the communication I/F unit303executes an intermittent reception operation in which a period of trying to receive a wireless signal (hereinafter referred to as a window period) and a period of not receiving are periodically repeated. The duration of the window period of the communication I/F unit303, and the duty of the window period in one cycle of the intermittent reception operation can be changed under the control of the control unit310.

In the standby state, at least one of the duration of the window period and the duty of the window period is changed in such a way that more power is saved than in the normal operation. Specifically, the window period is set to be shorter or the duty of the window period is set to be smaller than in the normal operation state.

If control unit310detects a predetermined command via the communication I/F unit303after shifting from the normal operation state to the standby state, the control unit310returns to the normal operation state from the standby state.

If the detect command designates the execution of an application program322, the control unit310executes the designated application program322.

FIG. 3is a functional block diagram of the projector100.

The projector100has an I/F unit11, a communication I/F unit12, and an image unit13, as interfaces to connect to an external device. The I/F unit11has, for example, connector for wired connection to an external device, and an interface circuit corresponding to this connector. Specifically, an interface conforming to IEEE 1394, USB or the like can be employed.

The communication I/F unit12is a communication interface which executes communication with an external device, and is made up of a wired communication interface or a wireless communication interface. For example, the communication I/F unit12supports a wireless LAN (including WiFi) Bluetooth, Miracast (trademark registered) or the like. The communication I/F unit12communicates with the tablet terminal2and/or the tablet terminal3via the communication device4. The communication I/F unit12may also be configured to execute direct wireless communication with the tablet terminals2,3without using the communication device4.

The image I/F unit13is configured as an image input interlace of DVI, D terminal, S terminal, composite, D-Sub or the like. The image I/F unit13may have an interface to which audio data is inputted. The image I/F unit13is connected, for example, to the foregoing image supply device. Digital image data or an analog image signal is inputted to the image I/F unit13.

For example, the wireless communication interface including an antenna, an RF circuit, and a modulation/demodulation circuit may be employed.

The projector100has a projection unit20which forms an optical image. The projection unit20has a light source unit21, a light modulation device22, and a projection system23. The light source unit21has a light source made up of a xenon lamp, ultra-high-pressure mercury lamp, LED or laser light source.

The light modulation device22modulates light emitted from the light source unit21, thus generates image light, and emits the image light to the projection system23. The light modulation device22has, for example, three transmission-type liquid crystal panels corresponding to the three primary colors of RGB and modulates light transmitted through these liquid crystal panels.

The projection system23guides the image light modulated by the light modulation device22into the direction of the screen SC and forms an image on the screen SC. The projection system23may also have a zoom mechanism which enlarges and reduces a projection image, and a focusing adjustment mechanism which adjusts the focusing.

The projection unit20is connected to a light source drive unit45which turns on the light source unit21under the control of a control unit30, and a light modulation device drive unit46which actuates the light modulation device22under the control of the control unit30. The light source drive unit45may have the function of switching on and off the light source unit21and adjusting the amount of light of the light source unit21.

The projector100has an image processing system which processes an image projected by the projection unit20. The image processing system includes the control unit30controlling the projector100, a storage unit60, an input accepting unit17an image processing unit40, the light source drive unit45, and the light modulation device drive unit46. A frame memory41may be connected to the image processing unit40. The frame memory41may be included in the image processing system.

The control unit30has a processor (not illustrated) such as a CPU or microcomputer. The control unit30causes the processor to execute a program, thus controlling each part of the projector100. The control unit30may have a ROM which stores a control program executed by the processor in a non-volatile manner, and a RAM forming a work area of the processor. The control unit30causes the processor to execute the program stored in the ROM and a program stored in the storage unit60and thus implements various functions of the projector100by the collaboration of the software and hardware.

The storage unit60stores a program executed by the control unit30and various data processed by the control unit30, in a non-volatile manner.

The data stored in the storage unit60includes display data61and communication setting data62.

The display data61is data received from the tablet terminal2or the tablet terminal3via the communication I/F unit12and displayed by the projection unit20. The display data61is made up of image data or dynamic image data.

The communication setting data62(connection information) is data about the tablet terminal3with which the projector100can communicate via the communication I/F unit12. That is, the communication setting data62is necessary setting data for the projector100to communicate with the tablet terminal3. Specifically, the communication setting data62includes the network address of the tablet terminal3in the communication network including the projector100and the tablet terminal3. The communication setting data62may also include an ID and/or password for authentication transmitted to the projector100from the tablet terminal3, or other information, when the projector100authenticates the tablet terminal3.

The image processing unit40processes image data under the control of the control unit30and outputs an image signal to the light modulation device drive unit46. The processing executed by the image processing unit40includes discrimination between a 3D (stereo) image and a 2D (planar) image, resolution conversion, frame rate conversion, distortion correction, digital zoom, color tone correction, luminance correction, and the like. The image processing unit40executes processing designated by the control unit30and uses a parameter inputted from the control unit30, when necessary, to carry cut the processing. Of course, a combination of a plurality of types of the foregoing processing can be executed.

The image processing unit40is connected to the frame memory41. The image processing unit40processes image data inputted to the image I/F unit13, as input image data. If the control unit30transfers image data inputted to the I/F unit11to the image processing unit40, the image processing unit40processes the image data transferred by the control unit30, as input image data. The image data inputted to the I/F unit11includes, for example, the display data61acquired by the projector100from an external device under the control of the control unit30.

The image processing unit40loads the input image data into the frame memory41and draws an image in the frame memory41. The image processing unit40executes the foregoing various types of processing on the image loaded in the frame memory41.

The image processing unit40reads out the processed image data from the frame memory41, generates R, G, B image signals corresponding to this image data, and outputs the image signals to the light modulation device drive unit46, if the image data inputted to the image I/F unit13is, for example, dynamic image made up of sequential frames, the image processing unit40loads each frame into the frame memory41. In this case, the image processing unit40successively loads frames inputted from the image I/F unit13into the frame memory41and causes the projection unit20to project the frames.

The light modulation device drive unit45is connected to the liquid crystal panels of the light modulation device22. The light modulation device drive unit46drives the liquid crystal panels, based on the image signals inputted from the image processing unit40and thus causes an image to be drawn on each liquid crystal panel.

The input accepting unit17is connected to a remote controller light receiving unit18and an operation panel19and detects an operation on the remote controller light receiving unit18and the operation panel19. The remote controller light receiving unit18and the operation panel19function as an input device.

The remote controller light receiving unit18receives an infrared signal transmitted from a remote controller (not illustrated) used by the user of the projector100, in response to a button operation. The remote controller light receiving unit18decodes the infrared signal received from the remote controller, generates operation data representing the content of the operation on the remote controller, and outputs the operation data to the control unit30.

The operation panel19is provided on the outer casing of the projector100and has various switches and an indicator lamp. The input accepting unit17, under the control of the control unit30, properly turns on and off the indicator lamp on the operation panel19according to the operation state and the setting state of the projector100. When a switch on the operation panel19is operated, operation data corresponding to the operated switch is outputted from the input accepting unit17to the control unit30.

The control unit30reads out and executes a control program stored in the storage unit60. The control unit30thus implements the functions of a projection control unit31and a communication control unit32and controls each part of the projector100.

The projection control unit31acquires the content of an operation carried out by the user operating the remote controller, based on operation data inputted from the input accepting unit17. The projection control unit31controls the image processing unit40, the light source drive unit45, and the light modulation device drive unit46according to the operation carried out by the user and thus causes an image to be projected on the screen SC.

The projection control unit31also controls and causes the image processing unit40to execute the foregoing processing such as discrimination between a 3D (stereo) image and a 2D (planar) image, resolution conversion, frame rate conversion, distortion correction, digital zoom, color tone correction, and luminance correction. The projection control unit31also controls the light source e drive unit45according to the processing by the image processing unit40and thus controls the amount of the light source unit21.

The communication control unit32communicates with an external device via the I/F unit11and the communication I/F unit12.

In the display system1thus configured, the tablet terminal2executes the application program222and thus functions as a moderator machine used by a moderator. Specifically, the tablet terminal2wirelessly communicates with the projector100and causes the projector100to display an image displayed on the touch panel201by the tablet terminal2.

The tablet terminal2also designates content to the tablet terminal3and instructs the tablet terminal3to display the content. For example, the tablet terminal2transmits to the tablet terminal3a command which designates the terminal management data324to be displayed by the tablet terminal3and a part to be displayed of the terminal management data324. The tablet terminal3displays on the touch panel301an image based on the terminal management data324designated by the command transmitted from the tablet terminal2.

Also, transmitting a command from the tablet terminal2to the tablet terminal3after the tablet terminal3shifts to the standby state can return the tablet terminal3from the standby state to the normal operation state. In this case, the tablet terminal3executes the application program322designated by the tablet terminal2.

FIG. 4is a sequence chart showing operations of the display system1.FIGS. 5, 6, 7, 8, and 9show display examples shown by the tablet terminal2when the operations shown inFIG. 4are executed.

The display system1executes the operations ofFIG. 4in the state where the tablet terminal2, the tablet terminal and the communication device4have not established communication with each other.

At the start of the operations ofFIG. 4, the tablet terminal3is already started up and in the normal operation state or in the standby state. Particularly in this embodiment, the tablet terminal3is in the standby state, waiting for access from an external device (step S1).

If the tablet terminal2is instructed to connect to the projector100by an operation on the touch panel201(step S11), the tablet terminal2sends a connection request to the projector100(step S12). The projector100responds to this connection request and thus establishes communication between the tablet terminal2and the projector100(step S13).

FIGS. 5 and 6show display examples of an operation screen401displayed by the tablet terminal2.

The operation screen401shown inFIG. 5has a display area403showing a list of projectors (including the projector100) to which the tablet terminal2can connect. An instruction button404is arranged on the operation screen401. The instruction button404is a button which designates the execution of a “simultaneous operation mode” in which a plurality of tablet terminals3forming the display system1simultaneously displays an image. The instruction button404is configured as a GUI (graphical user interface) on the touch panel201.

The user carries out a touch operation on the touch panel201and operates the instruction button404. This causes the tablet terminal2to switch the screen displayed on the touch panel201to an operation screen411shown inFIG. 6. The operation screen411ofFIG. 6shows the operation screen401and an instruction window413superimposed thereon, with the parts other than the instruction window413being grayed out.

The instruction window413has an instruction button414, which is a button to designate connection to the projector100, and a cancel button415to designate the cancelation of an operation. A touch operation of the cancel button415causes the tablet terminal2to erase the display of the instruction window413and shift to the operation screen401.

An operation of the instruction button414by the user corresponds to the operation of step S11. A touch operation of the instruction button414by the user causes the tablet terminal2to execute the operation of step S12in response to this touch operation.

Back toFIG. 4, after establishing communication with the projector100in step S13, the tablet terminal2transmits a command (control information) to the tablet terminal3(step S14). In Step S14, the tablet terminal2may decide a destination of a command, based on information included in the terminal management data224, and then transmit the command. In this case, the command is transmitted to the tablet terminal3whose information is included in the terminal management data224. The tablet terminal2may also transmit a command by a so-called broadcast packet, which can be received by all the devices belonging to the communication network including the tablet terminal2.

The tablet terminal3receives the command transmitted from the tablet terminal2, starts up from the standby state, and shifts to the normal operation state (step S15). The tablet terminal3causes the control unit310to start executing the application program322(step S16).

The tablet terminal3may be set in advance to shift to the normal operation state and start executing the application program322on receiving a command from the tablet terminal2in the standby state. In this case, the command transmitted from the tablet terminal2in step S14may be any command that the tablet terminal3can receive. The command may be, for example, a magic packet used in the known Wake-on-LAN technique. The command transmitted from the tablet terminal2in step S14may also include a command designating a shift to the normal operation state and a command designating the execution of the application program322.

The tablet terminal3, by the function of the application program322, tries to communicate with the projector100and request the projector100to connect to the tablet terminal3(step S17). The application program322is, for example, a program to automatically try to communicate with the projector100after startup. The application program322may use information of the projector100included in the communication setting data323when trying communication.

After the tablet terminal3sends connection request to the projector100in step S17, the projector100responds to the connection request and thus establishes communication between the tablet terminal3and the projector100(step S18).

The projector100updates the communication setting data62in such a way that the communication set data62eludes information about the tablet terminal3with which the projector100has established communication (step S19).

If the display system1includes a plurality of tablet terminals3, the tablet terminal2may transmit a command to the plurality of tablet terminals3in step S14, and the plurality of tablet terminals3may send a connection request to the pro tor100in step S17. In this case, the projector100establishes, in step S18, communication with each of the plurality of tablet terminals3requesting connection, and updates the communication setting data62in such a way that the communication setting data62includes information about each tablet terminal3.

FIG. 7shows a display example of an operation screen421displayed by the tablet terminal3.

The operation screen421is displayed on the touch panel301when the tablet terminal3executes the application program322in step S16. The operation screen421includes a connection guide display422showing that communication with the projector100is being tried, and a disconnection instruction button423designating the disconnection of communication with the projector100. Also, a content designation section425for selecting content stored in the tablet terminal3may be arranged on the operation screen421.

The tablet terminal3displays the operation screen421from the start of the execution of the application program322in step S16until communication with the projector100is established in step S18.

Back toFIG. 4, after establishing communication with the projector100, the tablet terminal3switches on an operation limitation mode (step S20). The operation limitation mode is an operation mode of the tablet terminal3in which touch operations on the touch panel301are disabled. As the operation limitation is started, the input processing unit311disables touch operations on the touch panel301detected by the input unit306. Therefore, during the execution of the operation limitation mode, the tablet terminal3cannot be operated by touch operations on the touch panel301. In the operation limitation mode, the control unit310may switch the operation screen421(FIG. 7) displayed on the touch panel301to grayout.

If the tablet terminal3has hardware keys (not illustrated) and the input unit306detects an operation on a hardware key in the operation limitation mode, the input processing unit311may be able to cancel the operation limitation mode in response to this operation. Also, though not illustrated, the tablet terminal3may switch off the operation limitation mode in response to a command transmitted from the tablet terminal2which instructs the tablet terminal3to cancel the operation limitation mode. In this case, the tablet terminal3becomes operable via the touch panel301.

Subsequently, in the display system1, the tablet terminal2can control the content displayed by the tablet terminal3.

As a first example, the case where the user operating the tablet terminal2designates a display based on the terminal management data324stored in the tablet terminal3is described. In this example, the user carries out an operation (step S31), and in response to this operation, the tablet terminal2transmits to the tablet terminal3a display instruction command (display instruction information) designating data to be displayed (step S32). The display instruction command transmitted in step S32includes, for example, a file path of the terminal management data324stored in the storage unit320of the tablet terminal3. The file path is information designating a file that forms the terminal management data324. The file path includes a path in the storage area of the storage unit320.

FIG. 8shows a display example of an operation screen431displayed by the tablet terminal2.

The operation screen431shown inFIG. 8includes a file display section432showing a list of files and folders or directories) stored in the storage unit320of the tablet terminal3. The configuration of the files, folders, or directories displayed in the file display section432represents the configuration in the storage unit320. The tablet terminal2may store, for example, information about the configuration in the storage unit320as included in the terminal management data224. Also, in a part of the storage unit220of the tablet terminal2, a folder configuration (directory configuration) shared with the storage area for the terminal management data324in the storage unit320may be arranged.

In the state where the tablet terminal2displays the operation screen431on the touch screen201, the user can carry out an operation of designating the terminal management data324by a touch operation on the touch panel201. The tablet terminal generates a display instruction command including the path of a file designated by the touch operation and transmits the display instruction command in step S32.

Back toFIG. 4, in step S32, the tablet terminal2transmits the display instruction command to the projector100. The projector100receives the display instruction command from the tablet terminal2and transmits the received display instruction command to the tablet terminal3, based on the communication setting data62(step S33). The communication setting data62includes information about the tablet terminal3with which the projector100has established communication in step S18. Therefore, the display instruction command transmitted from the tablet terminal2is transferred to the tablet terminal3which has established communication with the projector100.

The tablet terminal3receives the display instruction command from the projector100and reads the terminal management data324designated by the received display instruction command, from the storage unit320(step S34). The tablet terminal3displays an image or characters based on the terminal management data324thus read, on the touch panel301(step S35).

As a second example, the case where the user operating the tablet terminal2designates a shift from the displayed page when the tablet terminal3shows a display based on the terminal management data324is described. In this example, the user carries out an operation (step S41), and in response to this operation, the tablet terminal2transmits a display instruction command including an instruction to shift from the displayed page (step S42). The display instruction command transmitted in step S42includes, for example, data designating a display target page of the terminal management data324displayed by the tablet terminal3.

FIG. 9shows a display example of an operation screen441displayed by the tablet terminal2.

The operation screen441shown inFIG. 9includes a thumbnail display section443showing a list of thumbnail images of pages included in the terminal management data324displayed by the tablet terminal3. The operation screen441also includes a page display section445where the thumbnail image of the page displayed by the tablet terminal3is displayed. The operation screen441also includes a page shift instruction section446. In the page shift instruction section446, buttons to designate a shift from the displayed page, such as page feed and page back, are arranged.

In the state where the tablet terminal2displays the operation screen441on the touch panel201, the user can carry out an operation of designating a page to be displayed of the terminal management data324by a touch operation on the touch panel201. For example, if the user touches an arbitrary thumbnail image in the thumbnail display section443, the tablet terminal2generates a display instruction command designating the display of the page corresponding to the touched thumbnail image. If the user touches an arbitrary button in the page shift instruction section446, the tablet terminal2generates a display instruction command designating a page shift corresponding to the touched button.

Back toFIG. 4, in step S42, the tablet terminal2transmits the display instruction command to the projector100. The projector100receives the display instruction command from the tablet terminal2and transmits the received display instruction command to the tablet terminal3, based on the communication setting data62(step S43).

The tablet terminal3receives the display instruction command from the projector100and updates the display on the touch panel301, based on the page designated by the received display instruction command, of the currently displayed terminal management data324(step S44).

The operations of step S41to S44are not limited to the case of designating a display on a page basis. For example, the tablet terminal2may designate an area on one page or an area across a plurality of pages of the terminal management data324, and the tablet terminal3may display an image or characters based on the designated area, on the touch panel301. The operations of steps S41to S44may also be applied to display the terminal management data324that is not configured on a page basis.

As a third example, the case of causing the tablet terminal3to show a display based on data that is not stored in the storage unit320of the tablet terminal3is described.

This operation is executed when the user operating the tablet terminal2instructs the tablet terminal3to display data that is not stored in the storage unit320. In response to an operation by the user (step S51), the tablet terminal transmits a display instruction command including an instruction for the tablet terminal3to display data, and the data to be displayed (step S52). In step S52, the tablet terminal2transmits the display instruction command and the data to the projector100.

The projector100receives the display instruction command and the data from the tablet terminal2and transmits the received display instruction command to the tablet terminal3, based on the communication setting data62(step S53). The projector100also transmits the data received from the tablet terminal2to the tablet terminal3(step S54).

The tablet terminal3receives the display instruction command and the data from the projector100and displays an image or characters based on the received data, on the touch panel301(step S55).

The display instruction command transmitted from the tablet terminal2may include information (file name, content title or the like) specifying the data to be displayed by the tablet terminal3. In this case, if the data designated by the information included in the display instruction command is stored in the storage unit320of the tablet terminal3, the transmission of the data from the projector100to the tablet terminal3may be omitted. For example, if the data designated by the information included in the display instruction command transmitted from the projector100is stored in the tablet terminal3, the tablet terminal3may transmit control data to that effect to the projector100in this case, based on the control data transmitted from the tablet terminal3, the projector100specifies the tablet terminal3in which the corresponding data is stored. The projector100, in step S54, transmits data to the tablet terminal3in which the corresponding data is not stored. The projector100transmits only the display instruction command to the tablet terminal3having the corresponding data stored in the storage unit320. In this example, the traffic between the projector100and the tablet terminal3can be restrained.

In steps S35, S44, and S55, the tablet terminal3may transmit data representing the display state to the projector100, after displaying an image or characters on the touch panel301or updating the display. In this case, the projector100may cause the projection unit20to project an image or characters on the screen SC, based on the data received from the tablet terminal3. For example, the projector100can project on the screen SC a copy of the screen displayed on the touch panel301by the tablet terminal3.

For example, the tablet terminal2may transmit to the projector100a display instruction command including an instruction that one of the tablet terminals3as a target should transmit data representing the display state to the projector100. In this case, the target tablet terminal3, of the tablet terminals3receiving the display instruction command, transmits data representing the display state to the projector100.

In this case, an operation on the tablet terminal2can show the screen displayed by one of the tablet terminals3to a plurality of users via the screen SC.

As described above, the display system1according to the embodiment of the invention includes the projector100, the tablet terminal2, and the tablet terminal3. The tablet terminal3has the touch panel301, which displays an image, and the control unit310, which executes the application program322. The tablet terminal3communicates with external devices including the projector100. The tablet terminal2communicates with the tablet terminal3and the projector100. The tablet terminal2transmits a command to the tablet terminal3. On receiving the command from the tablet terminal2, the tablet terminal3causes the control unit310to start executing the application program322. In the tablet terminal3, the control unit310connects to the projector100by the function of the application program322and starts communicating with the projector100. The tablet terminal2transmits to the projector100a display instruction command instructing the tablet terminal3to display information. The projector100receives the display instruction command from the tablet terminal2and transmits the display instruction command to the tablet terminal3currently connected to the projector100. If the tablet terminal3receives the display instruction command from the projector100while executing the application program322, the tablet terminal3displays the information designated by the display instruction command on the touch panel301.

In the display system1, to which the communication system and the method for controlling the communication system according to the invention are applied, the tablet terminal2can cause the tablet terminal3to start executing the application program322. The tablet terminal2can also cause the tablet terminal3to connect to the projector100, based on the function of the application program322. Therefore, with the use of the tablet terminal2, the tablet terminal3can easily be enabled to communicate with the projector100. Also, transmitting the display instruction command from the tablet terminal2to the projector100enables the tablet terminal3to display information. After the tablet terminal3is connected to the projector100, transmitting information from the tablet terminal2to the projector100enables the tablet terminal3to operate. This can be realized even if the processing capability of the tablet terminal2is low. Thus, a system can be realized in which an operation of the tablet terminal2by the user can cause the application program322installed in the tablet terminal3to operate.

The tablet terminal3, to which the terminal device according to the invention is applied, has the communication I/F unit303capable of communicating with the projector100and an external terminal device, the touch panel301, and the control unit310, which executes the application program322. The tablet terminal3can execute the normal operation state, where the control unit310can execute the application program322, and the standby state, where the execution of the application program322and the display on the touch panel301are stopped. If a command is received via the communication I/F unit303in the standby state, the control unit310shifts to the normal operation state and starts executing the application program322. The control unit310connects to the projector100and starts communicating with the projector100, based on the function of the application program322. If a display instruction command is transmitted from the projector100during the execution of the application program322, the control unit310displays the information designated by the display instruction command on the touch panel301.

The tablet terminal3can execute the normal operation state, where the control unit310can execute the application program322, and the standby state, where the execution of the application program322and the display on the touch panel301are stopped. If the tablet terminal3receives a command from the tablet terminal2in the standby state, the tablet terminal3shifts to the normal operation state and executes the application program322.

With this configuration, the tablet terminal2can cause the tablet terminal3to start executing the application program322from the standby state. Thus, the operation to return the tablet terminal3from the standby state to the normal operation state can be omitted. Even if the tablet terminal3is scheduled to be used, there is no need to return the tablet terminal3to the normal operation state from the standby state in advance. Therefore, the tablet terminal3can wait in the standby state, thus saving power.

If the tablet terminal3is connected to the projector100by the function of the application program322, the projector100generates or updates the communication setting data62representing the tablet terminal3currently connected to the projector100. If the projector100receives a display instruction command from the tablet terminal2, the projector100transmits the display instruction command to the tablet terminal3, based on the communication setting data62.

With this configuration, the projector100can cause the tablet terminal3to display information, by transmitting the display instruction command to the tablet, terminal3, based on the communication setting data62. Thus, the projector100can efficiently manage the connection state with the tablet terminal3.

The tablet terminal3has the touch panel301as an operation unit. After starting executing the application program322, the tablet terminal3shifts to the operation limitation mode, in which the acceptance of an operation on the touch panel301is limited, based on the function of the application program322. Thus, an operation on the tablet terminal3can be prevented from disturbing the state of control by the tablet terminal2and the projector100.

The tablet terminal2can transmit data to be displayed by the tablet terminal3and a display instruction command, to the projector100. In this case, the tablet terminal3shows a display on the touch panel301, based on the display instruction command and the data received from the projector100. Therefore, the tablet, terminal3can execute display based on the data transmitted from the tablet terminal2to the projector100. Thus, the load on the tablet terminal2can be reduced when the information to be displayed by the tablet terminal3needs to be distributed from the tablet terminal2.

The tablet terminal2may transmit a display instruction command designating information to be displayed by the tablet terminal3, to the projector100. In this case, the tablet terminal3acquires the information designated by the display instruction command received from the projector100, for example, from the storage unit320, and shows a display on the touch panel301based on the acquired information. Thus, the load on the tablet terminal2when causing the tablet terminal3to display information can be reduced further.

The tablet terminal3may download the data designated by the display instruction command from a device other than the tablet terminal2and the projector100, for example, from an external server device. In this case, the display instruction command may include a URL (uniform resource locator) for the tablet terminal3to download the data from the server device.

After the control unit310starts executing the application program322, the tablet terminal3may transmit information representing the content of display on the touch panel301to the projector100, based on the function of the application program322. In this case, the projector100can process the content displayed by the tablet terminal3.

The foregoing embodiment is simply an example of specific form of the invention and should not limit the invention. The invention can also be applied in difference forms.

For example, while the foregoing embodiment describes a configuration where one projector100establishes communication with a plurality of tablet terminals3, configuration where a plurality of tablet terminals3connect to and communicate with each of a plurality of projectors100may be employed. In this case, the tablet terminal2may transmit a display instruction command to the plurality of projectors100, and the display instruction command may be transmitted to the tablet terminal3which communicates to one of the plurality of projectors100.

The display device according to the invention is not limited to the projector100projecting an image on the screen SC as described above. For example, the invention can also be applied to a liquid crystal monitor or liquid crystal television which displays an image on a liquid crystal display panel, or a monitor device or television receiver which displays an image on a PDP (plasma display panel). The invention can also be applied to a self-emission display device such as a monitor device or television receiver which displays an image on an organic EL display panel called OLED (organic LED) or OEL (organic electro-luminescence). The invention can also be applied to various other display devices.

The functional blocks shown inFIGS. 2 and 3represent the functional configurations of the tablet terminals2,3and the projector100and should not limit the specific forms of installation of these elements. That is, hardware corresponding to the illustrated functional blocks need not be installed. As a matter of course, one processor can implement the functions of a plurality of functional units by executing a program. Also, a part of the functions implemented by software in the embodiment may be implemented by hardware, and a part of the functions implemented by hardware may be implemented by software.

The terminal device according to the invention is not limited to the tablet terminals2,3. For example, any device that can display an image, such as a desktop computer, a mobile phone including a smartphone, or a video/music player, may be employed. Also, for example, a server device connected to the tablet terminals2,3and the projector100via a communication line may be provided. In this case, for example, the tablet terminal3may be configured to acquire the terminal management data324or the like from the server device. Moreover, specific details of the other parts of the devices forming the display system1can be changed arbitrarily without departing from the spirit of the invention.

The invention may also be configured in the form of a program executed by a computer to implement a method for controlling the tablet terminals2,3, a recording medium on which this program is recorded in a computer-readable manner, or a transmission medium which transmits this program. The invention may also be configured in the form of a data signal or the like which embodies this program within a carrier wave.

As the recording medium, a magnetic or optical recording medium, or a semiconductor memory device can be used. Specifically, a portable recording medium such as a flexible disk, HDD, CD-ROM, DVD, Blu-ray (trademark registered) disc, magneto-optical disk, flash memory, or card-type recording medium, or a fixed recording medium can be used. The recording medium may also be a non-volatile storage device such as a RAM, ROM, or HDD, which is an internal storage device provided in each device in the display system1or provided in an external device connected to each device.