Patent Publication Number: US-2015077641-A1

Title: Display device, display system, method for controlling display device, program, and recording medium

Description:
TECHNICAL FIELD 
     The present invention relates to a display device of a system in which a transmission device and the display device are separate. 
     BACKGROUND ART 
     In recent years, a separate television system in which a display displaying an image and a set-top box (STB) including a tuner, for example are separate has been widespread. 
     For example, Patent Literature 1 discloses a wireless communication system including a plurality of source devices (STBs) and a sync device (display) which receives image data wirelessly transmitted from the plurality of source devices. 
     CITATION LIST 
     Patent Literature 
     Patent Literature 1 
     
         
         Japanese Patent Application Publication, Tokukai, No. 2008-271008 (Publication Date: Nov. 6, 2008) 
       
    
     SUMMARY OF INVENTION 
     Technical Problem 
     In the case of an integrated television system (television receiver) in which a display and a set-top box are integrated, in order to reduce electric power consumption by the television system when the television system is off or in a standby state, the television system is generally operated in a state in which only a small microcomputer which is sufficient to, for example, receive a user&#39;s remote control operation and manage time. 
     According to a conventional separate television system which uses wireless communication, when a display is in a power off or standby state, the display receives an activation trigger by a user operation, so that the display can be activated by the activation trigger. Meanwhile, an STB of the television system needs to receive the activation trigger from the display by establishing wireless communication with the display. Therefore, the STB which is off needs to be activated by activating a wireless communication section (wireless communication control section) which is provided in the STB so as to establish wireless communication with the display. Accordingly, the conventional separate television system is generally configured such that in a state in which the STB and the display are off, the wireless communication section of the STB is active, and a wireless communication section of the display is inactive so as to save electric power. 
     Note here that, in a case where a viewing reservation, for example is made, the STB which receives broadcasting generally manages time information which is necessary when the viewing reservation is made. This causes the STB to have the activation trigger for activating the STB and the display at a time at which a reserved viewing is stared. However, according to the configuration of the conventional separate television system, the wireless communication section of the display is inactive so as to save electric power. This makes it impossible to transmit the activation trigger from the STB. Therefore, the wireless communication section of the display also needs to be active so that the display is activated when the viewing reservation is made. 
     However, when the STB and the display are in a power off or standby state, the television system in which both the wireless communication section of the STB and the wireless communication section of the display are active consumes high electric power. Therefore, when no viewing reservation is made, the television system wastefully consumes electric power in a case where the wireless communication section of the STB and the wireless communication section of the display are active. 
     The present invention has been made in view of the problem, and an object of the present invention is to provide a display device which consumes low electric power in a separate television system in which a transmission device and the display device are separate. 
     Solution to Problem 
     In order to attain the object, a display device in accordance with the present invention for displaying an image, includes: a receiving section which receives an image signal transmitted from a transmission device and indicative of the image; and determining means for, in response to an instruction from a user to change a state of the display device to a standby state, determining, in accordance with a time remaining before a reserved viewing is started, whether or not to stop supplying electric power to the receiving section. 
     In order to attain the object, a display device of the present invention for displaying an image, includes: a receiving section which receives an image signal transmitted from a transmission device and indicative of the image; and electric power supply means for, when a state of the display device is a standby state and a time remaining before a reserved viewing is started falls below a predetermined threshold, starting supplying electric power to the receiving section. 
     In order to attain the object, a method of the present invention for controlling a display device for displaying an image, the display device including a receiving section which receives an image signal transmitted from a transmission device and indicative of the image, the method includes the step of: in response to an instruction from a user to change a state of the display device to a standby state, determining, in accordance with a time remaining before a reserved viewing is started, whether or not to stop supplying electric power to the receiving section. 
     In order to attain the object, a method of the present invention for controlling a display device for displaying an image, the display device including a receiving section which receives an image signal transmitted from a transmission device and indicative of the image, the method includes the step of: when a state of the display device is a standby state and a time remaining before a reserved viewing is started falls below a predetermined threshold, starting supplying electric power to the receiving section. 
     Advantageous Effects of Invention 
     A display device in accordance with the present invention makes it possible to suitably reduce electric power consumption by the display device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of a television system. 
         FIG. 2  is a view showing an example of a power source mode of a television system. 
         FIG. 3  is a flowchart showing an example of a process in which a state of a display is changed to a power off state. 
         FIG. 4  is a flowchart showing another example of the process in which the state of the display is changed to the power off state. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present invention is specifically described below. 
     (Overview of Television System  1 ) 
     First, an overview of a television system (display system)  1  in accordance with the present invention is described with reference to  FIG. 1 .  FIG. 1  is a block diagram illustrating a configuration of the television system  1  of the present embodiment. As illustrated in  FIG. 1 , the television system  1  includes an STB (transmission device, source device)  100  and a display (display device, sync device)  200 . 
     The STB  100  and the display  200  can establish wireless communication with each other. The display  200  receives an image signal transmitted from the STB  100 , and displays an image indicated by the image signal. That is, the television system  1  is a so-called separate television system. Note that the block diagram of  FIG. 1  illustrates functions unique to the present invention of various functions which the STB  100  and the display  200  have. It goes without saying that the STB  100  and the display  200  may have functions which are not illustrated in  FIG. 1 . 
     (Overview of STB  100 ) 
     Next, an overview of the STB  100  is described with reference to  FIG. 1 . The STB  100  includes a timepiece information acquiring section  101 , a timepiece information managing section  102 , a timepiece information transmitting section  103 , a reservation time monitoring section  104 , a device power ON process section  105 , a reservation information managing section  106 , a reservation information receiving section  107 , a reservation information transmitting section  108 , a reservation presence/absence answering section  109 , a wireless communication on/off control section  110 , a device power OFF process section  111 , a standby mode requesting section  112 , a standby mode managing section  113 , a standby mode receiving section  114 , and a wireless communication control section  115 . 
     The timepiece information acquiring section  101  of the STB  100  acquires timepiece information (time information) which has been externally received by an antenna (not illustrated) and is exemplified by a date, a time, and a day of the week. The timepiece information acquiring section  101  supplies the acquired timepiece information to the timepiece information managing section  102  which manages timepiece information. The timepiece information transmitting section  103  acquires the timepiece information from the timepiece information managing section  102  and transmits the acquired timepiece information via the wireless communication control section  115  to the display  200 . 
     The reservation information managing section  106  manages reservation information. Further, the reservation information managing section  106  manages a power source mode (described later). Note here that the reservation information is information indicative of, for example, a time on which a reservation for viewing of an image (program) has been made by a user (reserved viewing start time, reserved viewing termination time, etc.), a channel, and a program. 
     With reference to the timepiece information acquired from the timepiece information managing section  102  and a reservation time acquired from the reservation information managing section  106 , the reservation time monitoring section  104  monitors whether or not the reserved viewing start time has come. When the reserved viewing start time comes, the reservation time monitoring section  104  gives the device power ON process section  105  an instruction to turn on the STB  100 . The device power ON process section  105  turns on the STB  100  in accordance with the instruction from the reservation time monitoring section  104 . When the reserved viewing start time comes, the reservation time monitoring section  104  also starts transmitting, via the wireless communication control section  115  to the display  200 , the image signal received by the antenna. Note that, when the reserved viewing start time comes, the reservation time monitoring section  104  may transmit, via the timepiece information managing section  102  and the timepiece information transmitting section  103  to the display  200 , a notification that the reserved viewing start time has come. 
     The reservation information receiving section  107  receives, via the wireless communication control section  115 , reservation information which has been transmitted from the display  200  and set for the display  200  by the user, for example. The reservation information receiving section  107  supplies the reservation information to the reservation information managing section  106 . The reservation information transmitting section  108  transmits, via the wireless communication control section  115  to the display  200 , the reservation information managed by the reservation information managing section  106 . 
     With reference to the reservation information transmitted from the reservation information managing section  106  or the display  200 , the reservation presence/absence answering section  109  confirms (determines) whether or not a reservation is present. The reservation presence/absence answering section  109  supplies a result of the confirmation via the reservation information managing section  106  to the standby mode managing section  113 . The reservation presence/absence answering section  109  also transmits the result of the confirmation via the wireless communication control section  115  to the display  200 . 
     The device power OFF process section  111  receives, via the wireless communication control section  115 , a power source mode notified from the display  200 , and transmits the received power source mode to the wireless communication on/off control section  110 . Further, the device power OFF process section  111  changes a state of each of members of the STB  100  except the wireless communication control section  115  to a power off state (standby state) in accordance with the power source mode. 
     The wireless communication on/off control section  110  carries out control over whether or not to establish wireless communication. Specifically, the wireless communication on/off control section  110  which has received the power source mode from the device power OFF process section  111  carries out control over whether or not to stop supplying electric power to the wireless communication control section  115 . 
     The standby mode requesting section  112  requests, from the display  200  via the wireless communication control section  115 , a set value of a reservation standby mode which set value has been set in the display  200 . The standby mode receiving section  114  receives, via the wireless communication control section  115 , the set value of the reservation standby mode which set value has been transmitted from the display  200 , and supplies the set value of the reservation standby mode to the standby mode managing section  113 . The standby mode managing section  113  manages the set value of the reservation standby mode which set value has been received from the standby mode receiving section  114 . Note that the reservation standby mode is described later. 
     The wireless communication control section  115  carries out control so that communication with the display  200  is established. Specifically, the wireless communication control section  115  transmits, to the display  200 , the image signal received by the antenna. 
     (Overview of Display  200 ) 
     Next, an overview of the display  200  is described with reference to  FIG. 1 . The display  200  includes a reservation information receiving section  201 , a timepiece information managing section  202 , a timepiece information receiving section  203 , a reservation time monitoring section (determining means)  204 , a device power ON process section (activating means)  205 , a reservation information managing section (determining means, electric power supply means, synchronizing means)  206 , a reservation information receiving section  207 , a reservation information transmitting section  208 , a reservation presence/absence confirming section (reservation presence/absence confirming means)  209 , a wireless communication on/off control section (electric power supply means)  210 , a device power OFF process section  211 , a standby mode receiving section  212 , a standby mode managing section (standby state setting means)  213 , a standby mode transmitting section  214 , and a wireless communication control section (receiving section)  215 . 
     The timepiece information receiving section  203  of the display  200  receives, via the wireless communication control section  215 , time information transmitted from the STB  100 , and supplies the time information to the timepiece information managing section  202  which manages timepiece information. 
     The reservation information managing section  206  manages reservation information. Further, the reservation information managing section  206  manages a power source mode (described later). 
     With reference to the timepiece information acquired from the timepiece information managing section  202  and a reservation time acquired from the reservation information managing section  206 , the reservation time monitoring section  204  monitors whether or not a time remaining before a reserved viewing is started falls within a predetermined time. When the reserved viewing start time comes, the reservation time monitoring section  204  acquires, from the STB  100  via the wireless communication control section  215 , the image signal transmitted from the STB  100 . The reservation time monitoring section  204  which has received the image signal gives the device power ON process section  205  an instruction to turn on the display  200 . The device power ON process section  205  turns on the display  200  in accordance with the instruction from the reservation time monitoring section  204 . Note that, when the reserved viewing start time comes and the reservation time monitoring section  204  receives a notification that the reserved viewing start time has come, the reservation time monitoring section  204  may instruct the device power ON process section  205  to turn on the display  200 . 
     For example, the reservation time monitoring section  204  may be configured to start monitoring the reservation time and before a state of the display  200  is changed to a standby state, transmit, to the timepiece information managing section  202 , an instruction to transmit a current time. The timepiece information managing section  202  transmits the current time to the reservation time monitoring section  204  in accordance with the instruction. 
     The reservation information receiving section  201  receives reservation information inputted by the user by use of, for example, a remote controller, and supplies the reservation information to the reservation information managing section  206 . 
     The reservation information receiving section  207  receives, via the wireless communication control section  215 , reservation information which has been transmitted from the STB  100  and set for the STB  100  by the user, for example. The reservation information receiving section  207  supplies the reservation information to the reservation information managing section  206 . The reservation information transmitting section  208  transmits, via the wireless communication control section  215  to the STB  100 , the reservation information managed by the reservation information managing section  206 . 
     With reference to the reservation information or information on presence/absence of a reservation, the reservation information or the information having been transmitted from the STB  100 , the reservation presence/absence confirming section  209  confirms (determines) whether or not a reservation is present. The reservation presence/absence confirming section  209  supplies a result of the confirmation to the device power OFF process section  211 . The reservation presence/absence confirming section  209  also transmits the result of the confirmation via the wireless communication control section  215  to the STB  100 . 
     The device power OFF process section  211  transmits, to the wireless communication on/off control section  210 , a power source mode supplied from the reservation information managing section  206  via the standby mode managing section  213 . Further, the device power OFF process section  211  changes a state of each of members of the display  200  except the wireless communication control section  215  to a power off state (standby state) in accordance with the power source mode. 
     The wireless communication on/off control section  210  carries out control over whether or not to establish wireless communication. Specifically, the wireless communication on/off control section  210  which has received the power source mode from the device power OFF process section  211  carries out, in accordance with the power source mode, control over whether or not to stop supplying electric power to the wireless communication control section  215 . 
     The standby mode receiving section  212  receives a set value of a reservation standby mode which set value has been inputted by the user by use of, for example, the remote controller, and supplies the set value of the reservation standby mode to the standby mode managing section  213 . 
     The standby mode managing section  213  manages the set value of the reservation standby mode which set value has been received by the standby mode receiving section  212 . Further, the standby mode managing section  213  supplies the managed set value of the reservation standby mode to the standby mode transmitting section  214  in accordance with the request from the STB  100  for the set value of the reservation standby mode. 
     The standby mode transmitting section  214  supplies, via the wireless communication control section  215  to the STB  100 , the set value of the reservation standby mode which set value is managed by the standby mode managing section  213 . 
     The wireless communication control section  215  carries out control so that communication with the STB  100  is established. Specifically, the wireless communication control section  115  receives an image signal transmitted from the STB  100 , and supplies the image signal to a display section (not illustrated) which displays an image indicated by the image signal. 
     (Power Source Mode) 
     Next, a power source mode of the present embodiment is described with reference to  FIG. 2 .  FIG. 2  is a view showing an example of a power source mode of the television system  1 . 
     The power source mode is obtained by setting a state (power off state) in which the display  200  and the STB  100  are changed when an operation of turning off the display  200  in a power on state is carried out. A value (set value) of the power source mode is maintained (managed) by both the display  200  and the STB  100 . Note that in the STB  100 , the set value of the power source mode may be managed by the reservation information managing section  106  or any member other than the reservation information managing section  106 . Note also that in the display  200 , the set value of the power source mode may be managed by the reservation information managing section  206  or any member other than the reservation information managing section  206 . Assuming that the reservation information managing section  106  and the reservation information managing section  206  each manage the set value of the power source mode, the present example gives the description. 
     The power source mode may be set in the display  200  or the STB  100 . In order to set the power mode in the STB  100 , the user selects items in a setting menu of the STB  100  in the order of “Menu”, “Setting”, “Preparation for viewing, and “Various settings”. Then, the user sets the power mode via a user interface for setting a power mode, the user interface being located in a screen displayed in response to the selection of “Various settings”. 
     As shown in  FIG. 2 , the power source mode is divided into three power source modes: “Quick”, “Normal”, and “Standby”. Note that the power source mode is not limited to these three power source modes. 
     The power source mode “Quick” shows that, as shown in  FIG. 2 , the power off state of the display  200  is “Wireless-Ready”, the power off state of the STB  100  is “Quick”, and a recording reservation, a viewing reservation, and a power-on link can be achieved. 
     Note here that the power off state Wireless-Ready of the display  200  shows that, when the display  200  is off, the wireless communication control section  215  is in a power on state and the other members of the display  200  are in the power off state (standby state). Note that it goes without saying that the power off state Wireless-Ready of the display  200  shows a state in which a small microcomputer which is sufficient to, for example, receive a user&#39;s remote control operation and manage time is active. The following description assumes that the above microcomputer is active in a state in which the display  200  and the STB  100  are off. 
     The power off state Quick of the STB  100  shows that, when the STB  100  is off, all the members of the STB  100  can be activated as soon as the user touches a power button of the STB  100  or the STB  100  receives some instruction from the user. A state in which the power-on link can be achieved shows a state in which the STB  100  and the display  200  can be turned on so as to be linked to each other. Note that the present embodiment also refers to the power source mode “Quick” as a reservation standby state. 
     The power source mode “Normal” shows that, as shown in  FIG. 2 , the power off state of the display  200  is “Standby”, the power off state of the STB  100  is “Wireless-Ready”, and the recording reservation and the power-on link can be achieved. 
     Note here that the power off state Standby of the display  200  shows that, when the display  200  is off, all the members of the display  200  are in the standby state. In this case, the wireless communication control section  215  is in the power off or standby state. 
     The power off state Wireless-Ready of the STB  100  shows that, when the STB  100  is off, the wireless communication control section  115  is in a power on state and the other members of the STB  100  are in the power off state. 
     Note that the present embodiment also refers to the power source mode “Normal” as a normal standby state. 
     The power source mode “Standby” shows that, as shown in  FIG. 2 , the power off state of the display  200  is “Standby”, the power off state of the STB  100  is “Standby”, and the recording reservation can be achieved. 
     Note here that the power off state Standby of the STB  100  shows that, when the STB  100  is off, all the members of the STB  100  are in the standby state. In this case, the wireless communication control section  115  is in the power off or standby state. 
     The user can set these three power source modes for the television system  1 . Note that an initial value of the power off state is set for the television system  1  in advance so as to be an appropriate value in accordance with a place in which the television system  1  is to be used and/or a person for which the television system  1  is to be used. 
     In a case where the user sets the power source mode in the STB  100 , the reservation information managing section  106  of the STB  100  manages information indicative of the set power source mode (power source mode information). The STB  100  transmits the set power source mode information to the display  200 . For example, when the STB  100  and the display  200  are HDMI-connected, the STB  100  can transmit the set power source mode information by use of a CEC command, for example. Note that a method for transmitting the set power source mode information is not limited to such a method. The set power source mode information can also be transmitted by use of another communication method. 
     A timing at which the STB  100  and the display  200  are synchronized in terms of the power source mode is not limited to a timing at which the setting of the power source mode is completed. Alternatively, the STB  100  and the display  200  which are being connected may be constantly synchronized or may be synchronized at regular time intervals. 
     Note that, also in a case where the power source mode is set in the display  200 , transmission of the power source mode information from the display  200  to the STB  100  allows the STB  100  and the display  200  to be synchronized as described earlier. 
     (Change to Power Off State) 
     Next, the following description discusses a process in which a state of each of the STB  100  and the display  200  of the television system  1  is changed to a power off state. 
     The state of the display  200  which has been turned off by, for example, a touch by the user of a power button of the display  200  is changed to a power off state in accordance with the set power source mode. For example, in a case where the power source mode of the television system  1  has been set as “Normal”, the state of the display  200  is changed to the standby state as shown in  FIG. 2 . 
     In a case where an automatic power off (off timer, for example) is set for each of the display  200  and the STB  100 , and the automatic power off operates, the state of each of the display  200  and the STB  100  is changed to the power off state in accordance with the set power source mode. 
     The state of the STB  100  which has been turned off by, for example, the touch by the user of the power button of the STB  100  is changed to the standby state regardless of the power source mode. Note that in this case, an LED showing a power source state of the STB  100  indicates red (the power off state). Note also that a power source state of the display  200  is not changed. 
     When a wireless connection between the STB  100  and the display  200  is cut off, the state of the STB  100  is changed to the power off state Quick or Standby. In this case, the LED showing the power source state of the STB  100  indicates orange (the standby state). Note also that the power source state of the display  200  is not changed. 
     In a case where the user touches the power button of the STB  100  when the power off state of the STB  100  is Wireless-Ready, the state of the STB  100  is changed to the standby state. 
     (Change from Power Off State) 
     Next, the following description discusses a process in which the power off state of each of the STB  100  and the display  200  of the television system  1  is changed to a power on state. 
     When the user touches the power button of the display  200  which is in the power off state, the state of the display  200  is changed to the power on state. In this case, when the STB  100  is not in the standby state, i.e., the power off state of the STB  100  is Quick or Wireless-Ready, the state of the STB  100  is also changed to the power on state (subjected to the power-on link). 
     The STB  100  which is in the standby state is changed to the power on state in a case where the user touches the power button of the STB  100 . In this case, the LED showing the power source state of the STB  100  indicates green (the power on state). However, the state of the STB  100  which cannot be wirelessly connected with the display  200  within a predetermined time (e.g., within one minute) is automatically changed to Wireless-Ready. In this case, the LED showing the power source state of the STB  100  indicates orange. 
     (Setting of Reservation Standby Mode) 
     Next, the following description discusses a setting of the reservation standby mode. The reservation standby mode is information indicating that the power source mode is set as “Quick” or “Normal” when a viewing reservation is made. The user can set the reservation standby mode for the television system  1 . 
     For example, the user sets the reservation standby mode for the television system  1  via a user interface for setting on/off of the reservation standby mode, the user interface being located in a setting menu of the display  200 . The standby mode receiving section  212  of the display  200  receives a set value of the reservation standby mode which set value has been inputted by the user (information indicative of on/off), and supplies the set value to the standby mode managing section (a sub-microcomputer)  213 . By transmitting, to the STB  100 , the set value of the reservation standby mode which set value is managed by the standby mode managing section  213 , the standby mode transmitting section  214  synchronizes the STB  100  and the display  200  in terms of the reservation standby mode managed by each of the STB  100  and the display  200 . 
     In a case where the reservation standby mode is set as “on” by the user, until a viewing reservation time comes, a state of the television system  1  is changed to the power off state of the power source mode which has been set as “Quick” or “Normal” (described earlier). Note that, in a case where the reservation standby mode is not set as “on” when the viewing reservation is made, the STB  100  and/or the display  200  may warn that the reservation standby mode is not set as “on”. 
     Note that the above description discusses a case where the reservation standby mode is set in the display  200 . Alternatively, the reservation standby mode may be set in the STB  100 . 
     The above description also discusses a case where the reservation standby mode is set by the user. Alternatively, the reservation standby mode may be automatically set. First, the reservation information transmitting section  108  of the STB  100  transmits, to the display  200 , the reservation information managed by the reservation information managing section  106 , and the reservation information receiving section  207  of the display  200  receives the reservation information. By supplying the received reservation information to the reservation information managing section  206 , the reservation information receiving section  207  synchronizes the STB  100  and the display  200  in terms of the reservation information managed by each of the STB  100  and the display  200 . Alternatively, the reservation information transmitting section  208  of the display  200  transmits, to the STB  100 , the reservation information managed by the reservation information managing section  206 , and the reservation information receiving section  107  of the STB  100  receives the reservation information. By supplying the received reservation information to the reservation information managing section  206 , the reservation information receiving section  107  synchronizes the STB  100  and the display  200  in terms of the reservation information managed by each of the STB  100  and the display  200 . 
     Then, the reservation presence/absence answering section  109  of the STB  100  determines, from the reservation information managed by the reservation information managing section  106 , whether or not a viewing reservation is present. The reservation presence/absence answering section  109  transmits a result of the determination via the wireless communication control section  115  to the display  200 . The reservation presence/absence confirming section  209  of the display  200  confirms, through the received result of the determination, whether or not a viewing reservation is present. Thereafter, the reservation presence/absence confirming section  209  supplies a result of the confirmation via the device power OFF process section  211  to the standby mode managing section  213 . 
     In accordance with the result of the confirmation which result has been supplied from the reservation presence/absence confirming section  209 , the standby mode managing section  213  sets the reservation standby mode as “on” in a case where a viewing reservation is present, and the standby mode managing section  213  sets the reservation standby mode as “off” in a case where no viewing reservation is present. In a case where the reservation standby mode is set as “on”, the power source mode of the television system  1  is set as “Quick” or “Normal”. By transmitting, to the STB  100 , the set value of the reservation standby mode which set value is managed by the standby mode managing section  213 , the standby mode transmitting section  214  synchronizes the STB  100  and the display  200  in terms of the reservation standby mode managed by each of the STB  100  and the display  200 . 
     Note that a timing at which the reservation presence/absence answering section  109  determines whether or not a viewing reservation is present is not particularly limited. The reservation presence/absence answering section  109  may determine, when a viewing reservation is made, whether or not a viewing reservation is present. Alternatively, the reservation presence/absence answering section  109  may determine, in a background at regular time intervals while the display  200  is active, whether or not a viewing reservation is present. The reservation presence/absence answering section  109  may also determine, before the state of the display  200  is changed to the power off state after the display  200  is turned off by the user, whether or not a viewing reservation is present. 
     (Change to Power Off State when Reservation Standby Mode is Set) 
     Next, the following description discusses, with reference to  FIG. 3 , how the state of the television system  1  is changed to the power off state when the reservation standby mode (described earlier) is set as “on”, i.e., when the information managed by the standby mode managing section  213  is information indicating that the state of the display  200  is to be changed to the standby state in which the display device can start automatically at a reservation time.  FIG. 3  is a flowchart showing an example of a process in which the state of the display  200  of the television system  1  is changed to the power off state. 
     When the user gives an instruction to turn off the STB  100  and the display  200  (to change the state of each of the STB  100  and the display  200  to the standby state), the wireless communication control section  215  determines whether or not the instruction has been received (step S 31 , hereinafter referred to merely as S 31 ). In a case where the instruction has not been received (NO at S 31 ), the wireless communication control section  215  repeats S 31 . In a case where the instruction has been received (YES at S 31 ), with reference to the timepiece information acquired from the timepiece information managing section  202  and the reservation time acquired from the reservation information managing section  206  which manages reservation information, the reservation time monitoring section  204  of the display  200  determines whether or not the time remaining before the reserved viewing is started falls within a predetermined time (S 32 ). Similarly, the reservation time monitoring section  104  of the STB  100  also determines whether or not the time remaining before the reserved viewing is started falls within the predetermined time. 
     When the reservation time monitoring section  204  determines that the time remaining before the reserved viewing is started does not fall within the predetermined time (NO at S 32 ), the reservation information managing section  206  sets the power source mode of the display  200  as “Normal” (normal standby state) (S 33 ). Then, the reservation information managing section  206  notifies the device power OFF process section  211  via the standby mode managing section  213  that the power source mode of the display  200  has been set as the normal standby state. Further, the reservation information managing section  206  notifies the STB  100  via the reservation information transmitting section  208  that the power source mode of the display  200  has been set as the normal standby state. 
     Thereafter, the device power OFF process section  211  changes the state of each of the members of the display  200  except the wireless communication control section  215  to the standby state in accordance with the set power source mode. The wireless communication on/off control section  210  stops supplying electric power to the wireless communication control section  215  (S 34 ). Note that, in a case where the supply of electric power to the wireless communication control section  215  has been stopped, the wireless communication on/off control section  210  continues to stop supplying electric power to the wireless communication control section  215 . 
     The device power OFF process section  111  of the STB  100  changes the state of each of the members of the STB  100  except the wireless communication control section  115  to the standby state in accordance with the power source mode (“Normal”) notified from the display  200 . Note that the wireless communication on/off control section  110  continues to supply electric power to the wireless communication control section  115 . Note also that the device power OFF process section  111  of the STB  100  may change the state of each of the members of the STB  100  except the wireless communication control section  115  to the standby state in accordance with the power source mode set by the reservation information managing section  106  based on a result of the determination by the reservation time monitoring section  104 . 
     Thereafter, the process returns to S 32 , at which the reservation time monitoring section  204  redetermines whether or not the time remaining before the reserved viewing is started falls within the predetermined time. 
     When the reservation time monitoring section  204  determines that the time remaining before the reserved viewing is started falls within the predetermined time (YES at S 32 ), the reservation information managing section  206  sets the power source mode of the display  200  as “Quick” (reservation standby state) (S 35 ). Then, the reservation information managing section  206  notifies the device power OFF process section  211  via the standby mode managing section  213  that the power source mode of the display  200  has been set as the reservation standby state. Further, the reservation information managing section  206  notifies the STB  100  via the reservation information transmitting section  208  that the power source mode of the display  200  has been set as the reservation standby state. 
     Note that a timing at which the reservation time monitoring section  204  determines the time remaining before the reserved viewing is started is exemplified by, but not limited to (1) a timing at which the reservation time monitoring section  204  is instructed by the user to change the state of the television system  1  to the standby state, and (2) at regular time intervals after the state of the display  200  has been changed to the normal standby state (described earlier). Alternatively, the reservation time monitoring section  204  may carry out the determination at any time. 
     Thereafter, the device power OFF process section  211  changes the state of each of the members of the display  200  except the wireless communication control section  215  to the standby state in accordance with the set power source mode. The wireless communication on/off control section  210  supplies electric power to the wireless communication control section  215  (S 36 ). Note that, in a case where electric power is being supplied to the wireless communication control section  215 , the wireless communication on/off control section  210  continues to supply electric power to the wireless communication control section  215 . 
     In accordance with the power source mode (“Quick”) notified from the display  200 , the device power OFF process section  111  of the STB  100  changes the state of each of the members of the STB  100  except the wireless communication control section  115  to a state (Quick state) in which the members of the STB  100  except the wireless communication control section  115  can be immediately activated. Note that the wireless communication on/off control section  110  continues to supply electric power to the wireless communication control section  115 . Note also that the device power OFF process section  111  of the STB  100  may change the state of each of the members of the STB  100  except the wireless communication control section  115  to the Quick state in accordance with the power source mode set by the reservation information managing section  106  based on the result of the determination by the reservation time monitoring section  104 . 
     Thereafter, when the reserved viewing start time comes, the reservation time monitoring section  104  starts transmitting, via the wireless communication control section  115  to the display  200 , the image signal received by the antenna. Note that the reservation time monitoring section  104  may transmit, to the display  200 , a notification that the reserved viewing start time has come. 
     The wireless communication control section  215  of the display  200  confirms whether or not the reserved viewing start time has come (S 37 ). Specifically, the wireless communication control section  215  confirms whether or not the image signal and/or the notification that the reserved viewing start time has come have/has been received. In a case where the reserved viewing start time has not come (NO at S 37 ), the wireless communication control section  215  repeats S 37 . In a case where the reserved viewing start time has come (YES at S 37 ), the wireless communication control section  215  transmits, to the device power ON process section  205 , information that the reserved viewing start time has come. Then, the device power ON process section  205  turns on the members of the display  200  (S 38 ). 
     In a case where the reservation standby mode is set, a viewing reservation is registered in the television system  1 . The reservation time monitoring section  204  determines whether or not the time remaining before the reserved viewing registered as the viewing reservation is started falls within a predetermined time. The reservation information managing section  206  determines the power source mode in accordance with a result of the determination. That is, the reservation information managing section  206  causes the display  200  to be in the standby state by determining, in accordance with whether or not the time remaining before the reserved viewing is started falls within the predetermined time, whether the supply of electric power to the wireless communication control section  215  is to be stopped (the state of the display  200  is to be changed to the normal standby state) or whether the supply of electric power to the wireless communication control section  215  is not to be stopped (the state of the display  200  is to be changed to the reservation standby state). Then, the state of the display  200  is changed to an electric power mode thus determined. 
     This prevents the supply of electric power to the wireless communication control section  215  of the display  200  from being stopped when the time remaining before the reserved viewing start is started falls within the predetermined time. Therefore, the display  200  can receive, from the STB  100 , information such as information that the display  200  is to be activated when a time at which the reserved viewing is started comes. In a case where the time remaining before the reserved viewing is started does not fall within the predetermined time, it is possible to stop supplying electric power to the wireless communication control section  215  of the display  200 . This makes it possible to suitably reduce electric power consumption by the display  200 . 
     After the state of the display  200  has been changed to the normal standby state, i.e., after the supply of electric power to the wireless communication control section  215  has been stopped, the reservation time monitoring section  204  determines whether or not the time remaining before the reserved viewing registered as the viewing reservation is started falls within the predetermined time. The reservation information managing section  206  determines the power source mode in accordance with a result of the determination. That is, in accordance with whether or not the time remaining before the reserved viewing is started falls within the predetermined time, the reservation information managing section  206  determines whether the supply of electric power to the wireless communication control section  215  is not to be started (the state of the display  200  continues to be the normal standby state) or whether the supply of electric power to the wireless communication control section  215  is to be started (the state of the display  200  is to be changed to the reservation standby state). 
     This causes the supply of electric power to the wireless communication control section  215  of the display  200  to be stopped until the time remaining before the reserved viewing is started falls within the predetermined time. It is not until the time remaining before the reserved viewing is started falls within the predetermined time that the supply of electric power to the wireless communication control section  215  of the display  200  is started. This makes it possible to reduce electric power consumption by the display  200  also in a case where a viewing reservation is made. 
     [Modification] 
     Next, the following description discusses, with reference to  FIG. 4 , a modification of a process in which the state of the display  200  is changed to the reservation standby state in a case where the reservation standby mode is set and the display  200  is in the standby state.  FIG. 4  is a flowchart showing another example of the process in which the state of the display  200  of the television system  1  is changed to the power off state. 
     The present modification assumes that the display  200  is in the standby state for, for example, the reason that (1) the state of the display  200  has been changed to the normal standby state, (2) the power button of the display  200  was touched by the user when the power source mode was “Normal” or “Standby” mode, or (3) an off timer operated when the power source mode was “Normal” or “Standby” mode. In this case, the supply of electric power to the wireless communication control section  215  of the display  200  has also been stopped. 
     The reservation information managing section  206  of the display  200  determines, by use of, for example, a counter, whether or not the time remaining before the reserved viewing is started falls below a predetermined threshold (S 41 ). In this case, the reservation information managing section  206  instructs the device power ON process section  205 , at regular time intervals, to activate the members of the display  200  including the wireless communication control section  215  in the background. In a case where the device power ON process section  205  temporarily activates the members of the display  200  in the background at regular time intervals, the reservation information managing section  206  can receive program information such as a start time changed by, for example, a change in program schedule of a program reserved for viewing. Further, the reservation information managing section  206  can receive the timepiece information via the timepiece information managing section  202 . This makes it possible to correct a time lag occurring in the counter. 
     The reservation information managing section  206  which has received the timepiece information and the program information on the program reserved for viewing instructs the device power OFF process section  211  via the standby mode managing section  213  to change the state of the display  200  to the standby state. 
     Note that, in a case where information of the counter has been lost by the change in state of the display  200  to the standby state, the reservation information managing section  206  may synchronize the counter with the display  200  by reinstructing the device power ON process section  205  to activate the display  200  in the background. 
     In a case where the time remaining before the reserved viewing is started does not fall below the predetermined threshold (NO at S 41 ), the reservation information managing section  206  repeats S 41 . 
     When the time remaining before the reserved viewing is started falls below the predetermined threshold (YES at S 41 ), the reservation information managing section  206  gives the wireless communication on/off control section  210  an instruction to supply electric power to the wireless communication control section  215 . Then, in accordance with the instruction, the wireless communication on/off control section  210  starts supplying electric power to the wireless communication control section  215  (S 42 ). 
     Thereafter, when the reserved viewing start time comes, the reservation time monitoring section  104  starts transmitting, via the wireless communication control section  115  to the display  200 , the image signal received by the antenna. Note that the reservation time monitoring section  104  may transmit, to the display  200 , a notification that the reserved viewing start time has come. 
     The wireless communication control section  215  of the display  200  confirms whether or not the reserved viewing start time has come (S 43 ). Specifically, the wireless communication control section  215  confirms whether or not the image signal and/or the notification that the reserved viewing start time has come have/has been received. In a case where the reserved viewing start time has not come (NO at S 43 ), the wireless communication control section  215  repeats S 43 . In a case where the reserved viewing start time has come (YES at S 43 ), the wireless communication control section  215  transmits, to the device power ON process section  205 , information that the reserved viewing start time has come. Then, the device power ON process section  205  turns on the members of the display  200  (S 44 ). 
     As described earlier, when the display  200  is in the standby state and the time remaining before the reserved viewing is started falls below the predetermined threshold, electric power is supplied to the wireless communication control section  215  of the display  200 . This makes it possible to more suitably reduce electric power consumption by the display  200 . 
     Note that the image signal recited in the claims is not limited to image signals which are supplied from broadcasting sources such as terrestrial digital broadcasting, CS broadcasting, and BS broadcasting. The image signal recited in the claims is also exemplified by image signals which are supplied from communication sources such as IPTV and VOD, medium sources such as a hard disk drive and an optical disc drive, and application sources such as a web browser and a USB application (an application which plays back content stored in a USB memory). The image signal recited in the claims is not limited to an image signal indicative of a moving image, but may also be an image signal indicative of a still image. The image signal recited in the claims may also be an image signal indicative of a UI (user interface) such as an image signal which is supplied from an application source. 
     The present embodiment discusses an example in which the STB  100  and the display  200  establish wireless communication. Alternatively, the STB  100  and the display  200  may be configured to establish communication by, for example, being HDMI-connected. 
     The present invention is not limited to the description of the embodiments above, but may be altered by a skilled person within the scope of the claims. An embodiment based on a proper combination of technical means disclosed in different embodiments is encompassed in the technical scope of the present invention. 
     [Software Implementation Example] 
     Finally, control blocks of the television system  1  may be realized by a logic circuit (hardware) provided in an integrated circuit (IC chip) or may be realized by software as executed by a CPU (Central Processing Unit). 
     In the latter case, the television system  1  includes: a CPU that executes instructions of a program realizing the foregoing functions; memory devices (storage media) including a ROM (Read Only Memory) storing the program, a RAM (Random Access Memory) that develops the program in executable form, and a memory storing the program and various kinds of data. The object of the present invention can also be achieved by making available to the television system  1  a storage medium computer-readably storing program codes (an executable program, an intermediate code program, and a source program) of a control program of the television system  1  which control program is software realizing the foregoing functions, and by causing a computer (or CPU or MPU) of the television system  1  to retrieve and execute the program codes stored in the storage medium. 
     The storage medium may be, for example, a tape, such as a magnetic tape or a cassette tape; a magnetic disk, such as a floppy (Registered Trademark) disk or a hard disk, or an optical disc, such as CD-ROM/MO/MD/DVD/CD-R; a card, such as an IC card (including a memory card) or an optical card; a semiconductor memory, such as a mask ROM/EPROM/EEPROM (Registered Trademark)/flash ROM; or a logic circuit, such as PLD (Programmable logic device) or FPGA (Field Programmable Gate Array). 
     The program codes may be made available over a communications network by arranging the television system  1  to be connectable to the communications network. Such a communications network is not particularly limited provided that the communications network can transfer the program codes. The communications network may be, for example, the Internet, an intranet, extranet, LAN, ISDN, VAN, CATV communications network, virtual dedicated network (Virtual Private Network), telephone line network, mobile communications network, or satellite communications network. A transfer medium which makes up the communications network is not limited to a transfer medium of a specific structure or type provided that the transfer medium can transfer the program codes. The transfer medium may be, for example, a wired system, such as IEEE 1394, a USB, an electric power line, a cable TV line, a telephone line, or an ADSL (Asymmetric Digital Subscriber Line) line; or a wireless system, such as infrared radiation (IrDA, remote control), Bluetooth (Registered Trademark), IEEE 802.11 wireless, HDR (High Data Rate), NFC (Near Field Communication), DLNA (Digital Living Network Alliance), a mobile telephone network, a satellite line, or a terrestrial digital network. The present invention encompasses a computer data signal in which the program codes are embodied electronically and which is embedded in a carrier wave. 
     CONCLUSION 
     As described earlier, a display device in accordance with an embodiment of the present invention for displaying an image, includes: a receiving section which receives an image signal transmitted from a transmission device and indicative of the image; and determining means for, in response to an instruction from a user to change a state of the display device to a standby state, determining, in accordance with a time remaining before a reserved viewing is started, whether or not to stop supplying electric power to the receiving section. 
     According to the configuration, in response to the instruction from the user to change the state of the display device to the standby state, the determining means determines whether or not the time remaining before the reserved viewing is started falls within a predetermined time. In a case where the time remaining before the reserved viewing is started is longer than the predetermined time, the determining means determines that the supply of electric power to the receiving section is to be stopped. In a case where the time remaining before the reserved viewing is started falls within the predetermined time, the determining means determines that the supply of electric power to the receiving section is not to be stopped. Then, the state of the display device is changed to the standby state in accordance with the determination by the determining means. 
     This prevents the supply of electric power to the receiving section of the display device from being stopped when the time remaining before the reserved viewing is started falls within the predetermined time. Therefore, the display device can receive, from the transmission device, information such as information that the display device is to be activated when a time at which the reserved viewing is started comes. In a case where the time remaining before the reserved viewing is started does not fall within the predetermined time, it is possible to stop supplying electric power to the receiving section of the display device. This makes it possible to suitably reduce electric power consumption by the display device. 
     The display device of an embodiment of the present invention is preferably configured such that, after stopping supplying electric power to the receiving section, the determining means determines, in accordance with the time remaining before the reserved viewing is started, whether or not to start supplying electric power to the receiving section. 
     This causes the supply of electric power to the receiving section of the display device to be stopped until the time remaining before the reserved viewing is started falls within the predetermined time. It is not until the time remaining before the reserved viewing is started falls within the predetermined time that the supply of electric power to the receiving section of the display device is started. This makes it possible to more suitably reduce electric power consumption by the display device. 
     The display device of an embodiment of the present invention is preferably configured to further include: standby state setting means for, in response to the instruction from the user to change the state of the display device to the standby state, setting whether or not to change the state of the display device to the standby state, when the state of the display device is set, by the standby state setting means, to be changed to the standby state, the determining means determining whether or not to stop supplying electric power to the receiving section. 
     This makes it possible to suitably reduce electric power consumption by the display device without changing the state of the display device to the standby state at a timing which is not intended by the user. 
     The display device of an embodiment of the present invention is preferably configured to further include: reservation presence/absence confirming means for confirming whether or not the reserved viewing is present, in a case where it has been confirmed by the reservation presence/absence confirming means that the reserved viewing is present, the standby state setting means setting the state of the display device to be changed to the standby state in which the display device can start automatically at a reservation time. 
     According to this, in a case where the reserved viewing is present, it is possible to set the state of the display device to be changed to the standby state in which the display device can start automatically at a reservation time. This makes it possible to more suitably reduce electric power consumption by the display device. 
     A display device in accordance with an embodiment of the present invention for displaying an image, includes: a receiving section which receives an image signal transmitted from a transmission device and indicative of the image; and electric power supply means for, when a state of the display device is a standby state and a time remaining before a reserved viewing is started falls below a predetermined threshold, starting supplying electric power to the receiving section. 
     According to the configuration, when the state of the display device is the standby state and the time remaining before the reserved viewing is started falls below the predetermined threshold, electric power is supplied to the receiving section of the display device. Therefore, when the time remaining before the reserved viewing is started falls below the predetermined threshold, the display device can receive, from the transmission device, information such as information that the display device is to be activated when a time at which the reserved viewing is started comes. Meanwhile, when the time remaining before the reserved viewing is started does not fall below the predetermined threshold, no electric power is supplied to the receiving section of the display device. This makes it possible to suitably reduce electric power consumption by the display device. 
     The display device of an embodiment of the present invention is preferably configured to further include: synchronizing means for temporarily activating the display device in a background at regular time intervals, and synchronizing with the transmission device in terms of a time at which the reserved viewing is started, the synchronizing means changing the state of the display device to the standby state after synchronizing with the transmission device in terms of the time at which the reserved viewing is started. 
     According to the configuration, in a case where the display device synchronizes with the transmission device at regular time intervals in terms of the time at which the reserved viewing is started, even if the time at which the reserved viewing is started is changed by, for example, a change in program schedule of a program reserved by the user for viewing, the electric power supply means supplies no electric power to the receiving section until a time remaining before the program reserved by the user for viewing is started falls below the predetermined threshold. This makes it possible to more suitably reduce electric power consumption by the display device. 
     The display device of an embodiment of the present invention is preferably configured such that: the receiving section receives, from the transmission device, information indicating that a reserved viewing start time has come, 
     the display device further including: activating means for activating the display device when the receiving section receives the information. 
     The information indicating that a reserved viewing start time has come, the information being transmitted from the transmission device which receives the image signal, is, for example, a notification that a reserved viewing start time has come or an image signal indicative of a program reserved for viewing. 
     In a case where the receiving section has received such information from the transmission device, even if the time at which the reserved viewing is started is changed by, for example, the change in program schedule of the program reserved by the user for viewing, the display device can be in the standby state until the program reserved by the user for viewing is started. This makes it possible to more suitably reduce electric power consumption by the display device. 
     A method of an embodiment of the present invention for controlling a display device for displaying an image, the display device including a receiving section which receives an image signal transmitted from a transmission device and indicative of the image, the method includes the step of: in response to an instruction from a user to change a state of the display device to a standby state, determining, in accordance with a time remaining before a reserved viewing is started, whether or not to stop supplying electric power to the receiving section. 
     The configuration yields an effect similar to that yielded by a display device in accordance with the present invention. 
     A method of an embodiment of the present invention for controlling a display device for displaying an image, the display device including a receiving section which receives an image signal transmitted from a transmission device and indicative of the image, the method includes the step of: when a state of the display device is a standby state and a time remaining before a reserved viewing is started falls below a predetermined threshold, starting supplying electric power to the receiving section. 
     The configuration yields an effect similar to that yielded by a display device in accordance with the present invention. 
     Note that a system including: a transmission device which transmits an image signal; and a display device mentioned above also falls under the category of the present invention. 
     A program for causing a computer to operate as a display device mentioned above, the program causing the computer to function as each means of the display device, and a computer-readable storage medium storing therein the program also fall under the category of the present invention. 
     INDUSTRIAL APPLICABILITY 
     The present invention is suitably usable for a separate television system in which an STB and a display are separate. 
     REFERENCE SIGNS LIST 
     
         
         
           
               1  Television system (display system) 
               100  STB (transmission device, source device) 
               101  Timepiece information acquiring section 
               102  Timepiece information managing section 
               103  Timepiece information transmitting section 
               104  Reservation time monitoring section 
               105  Device power ON process section 
               106  Reservation information managing section 
               107  Reservation information receiving section 
               108  Reservation information transmitting section 
               109  Reservation presence/absence answering section 
               110  Wireless communication on/off control section 
               111  Device power OFF process section 
               112  Standby mode requesting section 
               113  Standby mode managing section 
               114  Standby mode receiving section 
               115  Wireless communication control section 
               200  Display (reception device, sync device) 
               201  Reservation information receiving section 
               202  Timepiece information managing section 
               203  Timepiece information receiving section 
               204  Reservation time monitoring section (determining means) 
               205  Device power ON process section (activating means) 
               206  Reservation information managing section (determining means, electric power supply means, synchronizing means) 
               207  Reservation information receiving section 
               208  Reservation information transmitting section 
               209  Reservation presence/absence confirming section (reservation presence/absence confirming means) 
               210  Wireless communication on/off control section (electric power supply means) 
               211  Device power OFF process section 
               212  Standby mode receiving section 
               213  Standby mode managing section (standby state setting means) 
               214  Standby mode transmitting section 
               215  Wireless communication control section (receiving section)