Patent Publication Number: US-2011062792-A1

Title: Power-supply control device and power-supply control method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2009-212287, filed on Sep. 14, 2009; the entire contents of which are incorporated herein by reference. 
     FIELD 
     Embodiments described herein relate generally to a power-supply control device and a power-supply control method. 
     BACKGROUND 
     There is a demand for a reduction in standby power for the purpose of a reduction in power consumption in an electric apparatus connected to a commercial power supply and used. During the stop of the electric apparatus, the standby power can be reduced to zero if a power supply plug is pulled out from a power supply socket. However, it is troublesome to pull out the power supply plug every time the electric apparatus is stopped. An excessive burden is imposed on a user. Therefore, a technology for a control device for automatically interrupting supply of electric power during the stop of a controlled-side electric apparatus is disclosed. 
     However, in the related art, because the control device is provided separately from the electric apparatus, a user may be unwilling to take the trouble to prepare the device separately from the electric apparatus. Some user feels it annoying to consider a configuration for connecting the separate device and the electric apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of the schematic configuration of electric apparatuses including power-supply control devices according to a first embodiment; 
         FIG. 2  is a flowchart for explaining a procedure for the power-supply control device to decide whether a DVD recorder is a controlling-side electric apparatus; 
         FIG. 3  is a flowchart for explaining a procedure for power supply control by the power-supply control device of the DVD recorder as the controlling-side electric apparatus; 
         FIG. 4  is a block diagram of the schematic configuration of electric apparatuses including power-supply control devices according to a second embodiment; and 
         FIG. 5  is a flowchart for explaining a procedure for an apparatus discriminating unit to discriminate, based on power consumptions, whether a connection configuration is appropriate for a reduction in standby powers. 
     
    
    
     DETAILED DESCRIPTION 
     In general, according to one embodiment, a power-supply control device is provided in an electric apparatus connected to a commercial power supply and includes: a connecting unit to which another electric apparatus different from the electric apparatus can be connected; an apparatus discriminating unit that discriminates whether the electric apparatus is a controlling-side electric apparatus that controls supply of electric power to the other electric apparatus; a switching unit that switches supply and interruption of electric power supplied from the commercial power supply to the other electric apparatus connected to the connecting unit; and a control unit that controls the supply and the interruption of electric power by the switching unit when the apparatus discriminating unit discriminates that the electric apparatus is the controlling-side electric apparatus. 
     Exemplary embodiments of a power-supply control device and a power-supply control method will be explained below in detail with reference to the accompanying drawings. The present invention is not limited to the following embodiments. 
       FIG. 1  is a block diagram of the schematic configuration of electric apparatuses including power-supply control devices according to a first embodiment. In the first embodiment, a digital versatile disc (DVD) recorder  100  and a television receiver  101  are explained as examples of the electric apparatuses. 
     In the explanation of the embodiments, a controlling-side electric apparatus means an electric apparatus to which electric power is always supplied, for example, when the electric apparatus is connected to a commercial power supply. A controlled-side electric apparatus means an electric apparatus that is connected to a connecting unit included in the controlling-side electric apparatus and receives supply of electric power via the controlling-side electric apparatus. Supply and interruption of electric power to the controlled-side electric apparatus are controlled by the controlling-side electric apparatus. 
     The DVD recorder  100  records, in a hard disk drive incorporated in the DVD recorder  100  or a DVD as a storage medium, program data and the like obtained from a broadcast signal received by a tuner. The DVD recorder  100  transmits the program data and the like read from the DVD or the hard disk drive to a display device of the television receiver  101  or the like. Components such as the hard disk drive and the tuner included in the DVD recorder  100  to realize these functions are not shown in the figure. A state in which the DVD recorder  100  records the program data and transmits the program data to the display device is referred to as operation state of the DVD recorder  100 . 
     The DVD recorder  100  enters a standby state when electric power is supplied thereto. The standby state means a state in which the DVD recorder  100  can shift to the operation state when the DVD recorder  100  receives an operation signal from a remote controller or when an operation switch provided in the DVD recorder  100  is operated. When electric power is not supplied, the DVD recorder  100  does not shift to the operation state even if the operation signal is received or the operation switch is operated. 
     The DVD recorder  100  incorporates a power-supply control device  10 . The power-supply control device  10  includes a power supply plug  102 , a connecting unit  103 , a power-supply discriminating unit  104 , an apparatus discriminating unit  105 , a power-supply control unit (a control unit)  106 , and a switching unit  107 . 
     The power supply plug  102  of the DVD recorder  100  is inserted into a socket provided on a wall surface in a room or connected to a service socket included in the other electric apparatus. The DVD recorder  100  is connected the power supply via the power supply plug  102  and receives supply of electric power. The commercial power supply means, in general, a power supply provided to factories and homes by an electric power company. 
     The connecting unit  103  is formed in a shape same as the socket provided on the wall surface. A power supply plug of the other electric apparatus different from the electric apparatus incorporating the power-supply control device  10 , for example, a power supply plug  109  of the television receiver  101  can be inserted into the connecting unit  103 . The connecting unit  103  is called, for example, service socket. The other electric apparatus is connected to the commercial power supply via the DVD recorder  100  when the power supply plug is inserted into the connecting unit  103 . 
     When the power supply plug of the other electric apparatus is inserted, the connecting unit  103  transmits a predetermined signal (hereinafter, “controlled signal”) to the other electric apparatus via the inserted power supply plug. The controlled signal is a signal transmitted to cause the other electric apparatus to recognize that the other electric apparatus is a controlled-side electric apparatus. The connecting unit  103  can include a switch to detect that the power supply plug of the other electric apparatus is inserted or can include a detecting unit that detects a change in capacitance when the power supply plug is inserted. 
     The power-supply discriminating unit  104  discriminates whether the power supply plug  102  of the DVD recorder  100  is connected to the commercial power supply. Specifically, when electric power is supplied via the power supply plug  102  connected to the socket of the commercial power supply or the service socket of the other electric apparatus, the power-supply discriminating unit  104  discriminates whether the power supply plug  102  is connected to the commercial power supply. When electric power is supplied, the power-supply discriminating unit  104  detects presence or absence of the controlled signal received via the power supply plug  102 . When the controlled signal cannot be detected when the power supply plug  102  is inserted into the socket, the power-supply discriminating unit  104  discriminates that the power supply plug  102  is connected to the commercial power supply. On the other hand, when the controlled signal is detected when the power supply plug  102  is inserted into the socket, the power-supply discriminating unit  104  discriminates that the power supply plug  102  is not connected to the commercial power supply. The power-supply discriminating unit  104  transmits a detection result to the apparatus discriminating unit  105 . 
     The apparatus discriminating unit  105  discriminates whether the DVD recorder  100  is the controlling-side electric apparatus or the controlled-side electric apparatus. When the detection result transmitted from the power-supply discriminating unit  104  indicates that the power supply plug  102  is connected to the commercial power supply, the apparatus discriminating unit  105  decides the DVD recorder  100  as the controlling-side electric apparatus. When the detection result transmitted from the power-supply discriminating unit  104  indicates that the power supply plug  102  is not connected to the commercial power supply, the apparatus discriminating unit  105  decides the DVD recorder  100  as the controlled-side electric apparatus. The apparatus discriminating unit  105  transmits a decision result to the power-supply control unit  106 . The power-supply discriminating unit  104  and the apparatus discriminating unit  105  can be integrated. 
     If the decision result transmitted from the apparatus discriminating unit  104  indicates that the DVD recorder  100  is decided as the controlling-side electric apparatus, the power-supply control unit  106  applies power supply control to the controlled-side electric apparatus connected to the connecting unit  103 . The power supply control means control for performing, based on predetermined conditions, supply and interruption of electric power to the controlled-side electric apparatus. The power-supply control unit  106  performs the power supply control by causing the switching unit  107  to switch the supply and the interruption of electric power to the controlled-side electric apparatus. When the decision result transmitted from the apparatus discriminating unit  104  indicates that the DVD recorder  100  is decided as the controlled-side electric apparatus, the power-supply control unit  106  does not perform the power supply control. The predetermined conditions for performing the control of the supply and the interruption of electric power to the controlled-side electric apparatus are explained in detail later. 
     The switching unit  107  is provided between the power supply plug  102  and the connecting unit  103 . The switching unit  107  switches supply and interruption of electric power, which is supplied via the power supply plug  102 , to the connecting unit  103 . When electric power is supplied to the connecting unit  103 , electric power is supplied to the controlled-side electric apparatus connected to the connecting unit  103 . When the supply of electric power to the connecting unit  103  is interrupted, the supply of electric power to the controlled-side electric apparatus connected to the connecting unit  103  is interrupted. The switching unit  107  switches, based on an instruction from the power-supply control unit  106  that performs the power supply control, the supply and the interruption of electric power to the connecting unit  103 . 
     The television receiver  101  displays a video and the like on a display unit and emits sound from a speaker based on a broadcast signal received by the tuner. The television receiver  101  displays a video and the like on the display unit and emits sound from the speaker based on program data or the like transmitted from the DVD recorder  100 . Components such as the display device and the speaker included in the television receiver  101  to realize these functions are not shown in the figure. A state in which the television receiver  101  displays a video on the display unit and emits sound from the speaker is referred to as operation state of the television receiver  101 . 
     The television receiver  101  enters a standby state when electric power is supplied thereto. The standby state means a state in which the television receiver  101  can shift to the operation state when an operation signal from a remote controller is received or an operation switch provided in the television receiver  101  is operated. When electric power is not supplied, the television receiver  101  does not shift to the operation state even if the operation signal is received or the operation switch is operated. 
     The television receiver  101  has the power supply plug  109 . The power supply plug  109  is inserted into the socket provided on the wall surface of the room and connected to the commercial power supply or connected to a connecting unit included in the other electric apparatus. Like the DVD recorder  100 , the television receiver  101  includes a power-supply control device  11 . Components and functions of the power-supply control device  11  included in the television receiver  101  are substantially the same as those of the power-supply control device  10  included in the DVD recorder  100 . Therefore, the components and the functions are denoted by the same reference numerals and detailed explanation of the components and the functions is omitted. 
       FIG. 2  is a flowchart for explaining a procedure for the power-supply control device  10  to decide whether the DVD recorder  100  is the controlling-side electric apparatus. 
     When electric power is supplied via the power supply plug  102  (step S 1 ), when the power-supply discriminating unit  104  does not detect a controlled signal (“No” at step S 2 ), the apparatus discriminating unit  105  decides the DVD recorder  100  as the controlling-side electric apparatus (step S 3 ) and transmits a decision result to the power-supply control unit  106 . When the power-supply discriminating unit  104  detects the controlled signal (“Yes” at step S 2 ), the apparatus discriminating unit  105  decides the DVD recorder  100  as the controlled-side electric apparatus (step S 4 ) and transmits a decision result to the power-supply control unit  106 . 
     The power-supply control device  11  of the television receiver  101  decides, according to the same procedure, whether the television receiver  101  is the controlling-side electric apparatus. Specifically, whichever of the DVD recorder  100  and the television receiver  101  is directly connected to the commercial power supply, decision of the controlling-side electric apparatus is appropriately performed and appropriate power supply control is performed. 
     As shown in  FIG. 1 , the DVD recorder  100  is connected to the commercial power supply and the television receiver  101  is connected to the connecting unit  103  of the DVD recorder  100 . In other words, the DVD recorder  100  is set as the controlling-side electric apparatus and the television receiver  101  is set as the controlled-side electric apparatus. Power supply control in this case is explained below. 
     In an initial state, electric power is not supplied to the television receiver  101 . The DVD recorder  100  as the controlling-side electric apparatus receives an operation signal transmitted from the remote controller to cause the television receiver  101  as the controlled-side electric apparatus to operate. When the power-supply control unit  106  of the power-supply control device  10  incorporated in the DVD recorder  100  receives the operation signal to the television receiver  101 , the power-supply control unit  106  controls the switching unit  107  to supply electric power to the television receiver  101 . 
     At a point when the operation signal is transmitted from the remote controller, because electric power is not supplied to the television receiver  101 , the television receiver  101  cannot shift to the operation state. Therefore, the power-supply control unit  106  causes, after supplying electric power to the television receiver  101 , a not-shown transmitting unit to transmit the operation signal to the television receiver  101  again and causes the television receiver  101  to shift to the operation state. When the television receiver  101  immediately shifts to the operation state not through the standby state when electric power is supplied thereto, it is unnecessary to transmit the operation signal again. 
     The DVD recorder  100  receives a standby signal transmitted from the remote controller to shift the operating television receiver  101  to the standby state. When the power-supply control unit  106  receives the standby signal, the power-supply control unit  106  controls the switching unit  107  to interrupt the supply of electric power to the television receiver  101 . To interrupt the supply of electric power after processing for shift to the standby state in the television receiver  101  is surely completed, delay means can be provided such that the supply of electric power can be interrupted when a fixed time elapses after the standby signal is received. 
     Therefore, in the first embodiment, an instruction for shift to the operation state and an instruction for shift to the standby state given to the television receiver  101  are the predetermined conditions for the power-supply control unit  106  to perform the control for supply and interruption of electric power. 
       FIG. 3  is a flowchart for explaining a procedure of power supply control by the power-supply control device  10  of the DVD recorder  100  as the controlling-side electric apparatus. 
     When a receiving unit of the DVD player  100  receives an operation signal transmitted from the remote controller to the television receiver  101  (step S 21 ), the power-supply control unit  106  causes the switching unit  107  to start supply of electric power to the television receiver  101  (step S 22 ). Thereafter, the power-supply control unit  106  causes the transmitting unit to transmit the operation signal to the television receiver  101  (step S 23 ). When the television receiver  101  is in the operation state, the receiving unit receives a stop signal from the remote controller (step S 24 ). The power-supply control unit  106  causes the switching unit  107  to interrupt the supply of electric power to the television receiver  101  (step S 25 ). 
     As explained above, the power-supply control devices  10  and  11  included in the DVD recorder  100  and the television receiver  101  discriminate and decide, according to connection destinations of the power supply plugs, whether the DVD recorder  100  and the television receiver  101  are the controlling-side electric apparatus or the controlled-side electric apparatus. Therefore, the user can use the electric apparatuses without worrying about connection order of the electric apparatuses. 
     Because supply and interruption of electric power are controlled according to a state of the controlled-side electric apparatus, it is possible to reduce standby power without pulling out and inserting the power supply plug and reduce a burden on the user. Because the power-supply control device is incorporated in the electric apparatus, a control device does not have to be provided separately from the electric apparatus. The user can easily install the electric apparatus. 
     A method of discriminating, with the power-supply discriminating unit  104 , whether the electric apparatus is connected to the commercial power supply is not limited to the method explained above. For example, the power-supply discriminating unit  104  can discriminate, when a predetermined signal transmitted from the socket of the commercial power supply is received when electric power is supplied, that the electric apparatus is connected to the commercial power supply and discriminate, when the predetermined signal is not received, that the electric apparatus is not connected to the commercial power supply. In this case, the connecting unit  103  only has to be configured not to transmit the controlled signal when the power supply plug is inserted. In recent years, in some case, information communication is performed by using a power line under the standards such as HD-PLC, HomePlug, AV, and Universal Power line Association (UPA). For example, it is possible to determine whether the electric apparatus is connected to the commercial power supply using information transmitted and received via a power line laid in a home as predetermined information under such power line communication standards. 
     It can be discriminated, based on resistance at a destination to which the power supply plug is connected, whether the electric apparatus is connected to the commercial power supply. In this case, the power-supply discriminating unit  104  measures the resistance at the destination to which the power supply plug is connected. For example, when the measured resistance is equal to or smaller than a reference value, the power-supply discriminating unit  104  discriminates that the electric apparatus is connected to the commercial power supply. When the measured resistance is larger than the reference value, the power-supply discriminating unit  104  discriminates that the electric apparatus is not connected to the commercial power supply. The reference value of the resistance as a reference for discrimination and a magnitude relation between the resistance and the reference value can be changed as appropriate according to the type and the configuration of the electric apparatus, the configuration of the power line for providing the commercial power supply, and the like. 
     The user can set whether the electric apparatus is connected to the commercial power supply in advance or connected to the service socket of the other electric apparatus. For example, the user can perform the setting with the switch provided in the DVD recorder  100  or can perform the setting by operating the electric apparatus with the remote controller or the like. In this case, when electric power is supplied via the power supply plug  102 , the apparatus discriminating unit  105  only has to decide, based on the setting of the switch or the remote controller, whether the electric apparatus is the controlling-side electric apparatus or the controlled-side electric apparatus. When this configuration is adopted, the power-supply discriminating unit  104  can be made unnecessary. 
     The predetermined conditions for the power-supply control unit  106  to control supply and interruption of electric power are not limited to the reception of the operation and standby signals for the television receiver  101 . For example, power consumption of the television receiver  101  is measured by the power-supply control unit  106 . When the power supply is smaller than a reference value, it is possible to determine that the television receiver  101  shifts to the standby state and perform control for interrupting electric power. 
     When operation for using the television receiver  101 , for example, operation for instructing playing of a DVD is applied to the DVD recorder  100 , the power-supply control unit  106  can perform control for supplying electric power to the television receiver  101 . It goes without saying that, when operation for stopping the use of the television receiver  101 , for example, operation for stopping a DVD being played is performed, the power-supply control unit  106  can perform control for interrupting electric power to the television receiver  101 . 
       FIG. 4  is a block diagram of the schematic configuration of an electric apparatus including a power-supply control device according to a second embodiment. In the second embodiment, as in the first embodiment, a DVD recorder  300  and a television receiver  301  are explained as examples of the electric apparatuses. Components same as those explained in the first embodiment are denoted by the same reference numerals and detailed explanation of the components is omitted. As in the first embodiment, in the explanation of the second embodiment, a connection configuration in which the DVD recorder  300  is a controlling-side electric apparatus and the television receiver  301  is a controlled-side electric apparatus is adopted. 
     In the second embodiment, a power-supply control device  20  of the DVD recorder  300  and a power-supply control device  21  of the television receiver  301  include communication units  209 , information transmitting units  210  and  213 , and recording units  211 . The communication units  209  allow the electric apparatuses to transmit and receive various kinds of information to and from each other. For example, when the DVD recorder  300  and the other electric apparatus are connected by wire as in communication standards such as HDMI, IEEE1394, USB, and Ethernet (registered trademark), connectors or the like for connecting a communication line correspond to the communication units  209 . When information is transmitted and received by wire as in communication standards such as Wireless LAN, Bluetooth, and UWB, antennas or the like correspond to the communication units  209 . 
     The information transmitting unit  210  performs transmission and reception of information with the other electric apparatus at predetermined timing via the communication unit  209 . The information transmitting unit  210  can store the information transmitted by the information transmitting unit  210  or the recording unit  211  or a hard disk drive explained later can store the information. The information transmitting units  210  and  213  transmit and receive information indicating power consumptions in the standby state of the electric apparatuses, i.e., standby powers. 
     The apparatus discriminating units  105  compare, separately from the decision of the controlling-side electric apparatus, the power consumptions transmitted and received by the information transmitting units  210  and  213 . When the power consumption of the DVD recorder  300  is larger than the power consumption of the television receiver  301 , an effect of a reduction in the standby powers is larger when power supply control is performed with the DVD recorder  300  set as the controlled-side electric apparatus. In this case, the apparatus discriminating units  105  notify a user that it is desirable to adopt a connection configuration in which the television receiver  301  as the controlled-side electric apparatus in the current connection configuration is set as the controlling-side electric apparatus. Specifically, the apparatus discriminating units  105  can cause a display unit of the television receiver  301  to display indication “please connect the television receiver to the socket of the commercial power supply”. The information transmitting units  210  and  211  function as power-information acquiring units that acquire information indicating the standby powers. The information transmitting units  210  and  213  also function as notifying units that notify a comparison result of the standby powers. The power-information acquiring units and the notifying units can be separately provided. 
       FIG. 5  is a flowchart for explaining a procedure for the apparatus discriminating unit  105  to discriminate, based on power consumptions, whether a connection configuration is appropriate for a reduction in standby powers. When the power supply plug  109  of the television receiver  301  is connected to the connecting unit  103  of the DVD recorder  300  (step S 51 ), information indicating standby powers of the apparatuses are transmitted and received (step S 52 ). The apparatus discriminating unit  105  on the television receiver  301  side compares the standby powers (step S 53 ). When the standby power of the DVD recorder  300  as the controlling-side electric apparatus is larger (“Yes” at step S 54 ), the television receiver  301  notifies the user that it is desirable to set the television receiver  301  as the controlling-side electric apparatus (step S 55 ). When the standby power of the DVD recorder  300  as the controlling-side electric apparatus is smaller (“No” at step S 54 ), because necessity for changing the connection configuration of the electric apparatuses is low, notification to the user is not performed (step S 56 ). 
     It goes without saying that the apparatus discriminating unit  105  on the DVD recorder  300  side can discriminate, in the same procedure, whether a connection configuration of the electric apparatuses is appropriate and notify the user of a result of the discrimination. For example, the apparatus discriminating unit  105  on the DVD recorder  300  side can cause a display unit of a remote controller of the DVD recorder  300  to display indication that the connection configuration is inappropriate. 
     In this way, the standby power of the electric apparatus as the controlling-side electric apparatus and the standby power of the electric apparatus as the controlled-side electric apparatus are compared. Therefore, it is possible to propose to the user a connection configuration of the electric apparatuses that can more efficiently reduce the standby powers. Further, it is automatically discriminated whether a connection configuration of the electric apparatuses is appropriate for a reduction in the standby powers. Therefore, it is possible to make it less likely that the user feels it annoying to select an appropriate connection configuration. 
     Information transmitted and received by the information transmitting units  210  and  213  is not limited to the information indicating the standby powers. Examples of the information transmitted and received by the information transmitting unit  210  are explained below. 
     Information indicating presence or absence of the power-supply control devices  20  and  21 , i.e., presence or absence of a function of the electric apparatuses for performing power supply control can be transmitted and received. Even when the standby power of the controlling-side electric apparatus is larger as a result of comparing the standby powers as shown in  FIG. 5 , unless the function for performing power supply control is present in the controlled-side electric apparatus, it is desirable not to change a connection configuration of the electric apparatuses. Therefore, it is possible to cause the apparatus discriminating unit  105  to determine, based on presence or absence of the function for performing power supply control, whether notification for urging the user to change the connection configuration should be performed. 
     When the DVD player  300  is decided as the controlling-side electric apparatus, the information transmitting unit  210  on the DVD player  300  side can transmit information for notifying that the television receiver  301  is the controlled-side electric apparatus. The television receiver  301  can be set not to perform discrimination of the controlling-side electric apparatus when this information is received. Therefore, it is possible to realize simplification of a procedure for discriminating the controlling-side electric apparatus. 
     The information transmitting unit  210  on the DVD recorder  300  side can transmit, when power supply control is performed, permission information for obtaining permission for supply and interruption of electric power. The information transmitting unit  213  on the television receiver  301  side that receives the permission information can transmit reply information indicating whether the supply and the interruption of electric power can be permitted. When update of firmware is performed in the television receiver  301  when the permission information is received, the information transmitting unit  213  transmits replay information for not permitting the interruption of electric power. This makes it possible to prevent a situation in which electric power is interrupted during the update of the firmware, the update ends incomplete, and a deficiency in terms of a system occurs. 
     The information transmitting unit  210  on the DVD recorder  300  side can inquire about a type and content of information that should be recorded by the recording unit  211  on the DVD recorder  300  side. The information transmitting unit  210  on the television receiver  301  side transmits information indicating the type and the content of the information that should be recorded by the recording unit  211  on the DVD recorder  300  side. For example, the information transmitting unit  210  transmits, as the information indicating the type and the content of the information that should be recorded by the recording unit  211  on the DVD recorder  300  side, time information, scheduled viewing information, and the like that are likely to be lost because of interruption of electric power. 
     When supply of electric power to the television receiver  301  is started, the information transmitting unit  210  on the DVD recorder  300  side transmits the time information recorded in the recording unit  211 . The television receiver  301  can reset, based on these kinds of information, time of a clock incorporated therein. The user does not need to perform time setting and the like every time electric power is supplied to the television receiver  301 . Therefore, it is possible to improve convenience of use of the DVD recorder  300  and the television receiver  301 . 
     The power-supply control unit  106  of the DVD recorder  300  can perform power supply control using the information recorded in the recording unit  211 . For example, the power-supply control unit  106  can be configured to supply, referring to the scheduled viewing information recorded in the recording unit  211 , electric power to the television receiver  301  when viewing start time comes. 
     The information transmitting unit  213  on the television receiver  301  side can transmit information indicating maximum power consumption of the television receiver  301 . The power-supply control unit  106  of the DVD recorder  300  can discriminate whether the maximum power consumption of the television receiver  301  as a target of power supply control is within permissible power. When the power-supply control unit  106  discriminate that the maximum power consumption of the television receiver  301  is larger than the permissible power of the DVD recorder, the power-supply control unit  106  can urge the user to directly connect the television receiver  301  to the socket of the commercial power supply. For example, the power-supply control unit  106  can cause the display unit of the television receiver  301  or the display unit of the remote controller to display warning indication. 
     The information transmitting unit  213  on the television receiver  301  side can transmit information indicating a communication standard and information indicating a communication protocol of the remote controller of the television receiver  301 . The DVD player  300  performs various kinds of setting based on, for example, the received information indicating the communication standard such that the DVD player  300  can receive and understand an operation signal and the like sent from the remote controller of the television receiver  301  to the television receiver  301 . Consequently, even when the DVD recorder  300  uses, between the DVD recorder  300  and a remote controller thereof, a communication protocol different from that of the remote controller of the television receiver  301 , the DVD recorder  300  can understand an operation instruction from the remote controller of the television receiver  301  and perform power supply control and the like. 
     The electric apparatuses can transmit and receive identification information with which the electric apparatuses can identify the electric apparatuses each other. Examples of information with which the electric apparatuses can identify the electric apparatuses each other include MAC addresses, global IDs, and identification numbers. The received identification information can be recorded in the recording unit  211 . The recording unit  211  is a recording medium that records various kinds of information such as the identification information. In the DVD recorder  300 , a hard disk drive that records program information and the like can also be used as the recording unit  211 . A recording medium can be separately provided. All the kinds of information as the examples of the information to be transmitted and received can be recorded in the recording unit  211 . 
     When transmission and reception of identification information is performed, the information transmitting unit  210  compares the identification information already recorded in the recording unit  211  and the received identification information. When the identification information already recorded in the recording unit  211  and the received identification information coincide with each other, the information transmitting unit  210  determines that the electric apparatus connected to the connecting unit  103  is not changed from the electric apparatus connected to the connecting unit  103  when electric power is supplied before. For example, when the information transmitting unit  210  determines that the electric apparatus is not changed, the reset of the communication protocol of the remote controller, the comparison of the permissible power and the maximum power consumption, and the like are not performed. This makes it possible to realize simplification of a control procedure. 
     In the embodiment explained above, each of the power-supply control device  20  and  21  has only one connecting unit. However, the power-supply control device can have a plurality of connecting units. For example, it is possible to provide a plurality of connecting units in the DVD player  300  and simultaneously connect a speaker and an amplifier besides the television receiver to perform power supply control. 
     While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel devices and methods described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the devices and methods described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.