Abstract:
A master/slave outlet system includes at least one master outlet and at least one slave outlet. Moreover, the slave outlet is turned on to start the device connected to the slave outlet, while the master outlet supplies enough current to the device connected to the master outlet. Furthermore, the slave outlet is turned off to close the device connected to the slave outlet, while the device connected to the master outlet is shutdown or at sleep mode.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a master/slave outlet system; in particular, to an outlet system in which the slave outlet supplies power only when the master outlet starts to. 
   2. Description of Related Art 
   Lately people make increasing use of electronic devices, and thus the use of extension lines increases. People also pay increasing attention to convenience, security and power-saving in various electronic devices. Currently, there are several types of commercially available extension line outlets on the market, including single switch control extension line and individual switch control extension line. 
   Refer to  FIG. 1 , wherein a perspective diagram of a single switch control extension line is shown. The single switch control extension line  1  (briefly referred as conjunctively-controlled based) has a plug  10 , extension line  12  and a body  14 , in which on the body  14  there are installed multiple outlets  142  and a switch  144 . All outlets  142  installed on the body  14  are controlled by the switch  144 , and when the switch  144  is turned on, AC power is introduced from the plug  10  and sent to each outlet  142  via the extension line  12  and the conducting switch  144 , so as to allow use by various electronic devices. However, using the single switch control extension line  1  may not achieve the objectives of security and power-saving. 
   Refer to  FIG. 2 , wherein a perspective diagram of an individual switch control extension line is shown. The individual switch control extension line  2  (briefly referred as individually-controlled based) has a plug  20 , an extension line  22  and a body  24 , in which on the body  24  there are installed multiple outlets  242  and multiple switches  244 . Each outlet  242  on the body  24  is correspondingly controlled by each switch  244 , and when the switch  244  is turned on, AC power is introduced from the plug  20  and sent to each corresponding outlet  242  via the extension line  22  and the conducting switch  244 , so as to allow use by various electronic devices. 
   Refer again to  FIGS. 1 and 2 . In terms of users, in addition to more functions of outlet  242  on the individual switch control extension line  2 , each outlet  242  has respective switch  244  for control, thus, compared with the above-described single switch control extension line  1 , it comparatively resolves the problems of security and power-saving. However, since users are required to respectively turn on each switch  244  of the individual switch control extension line  2  to allow use of the corresponding outlet  242 , this may cause inconvenience for users during operations. 
   SUMMARY OF THE INVENTION 
   In view of the aforementioned issues, the present invention provides a master/slave outlet system, which has at least one master outlet and at least one slave outlet, and when the electronic device connected to the master outlet is supplied with enough current, the slave outlet will become conducting, allowing the electronic device connected to the slave outlet to be turned on accordingly. When the electronic device connected to the master outlet is turned off or enters into sleep mode, the electronic device connected to the slave outlet will be also turned off accordingly. 
   A master/slave outlet system according to a first embodiment of the present invention comprises an alternative current (AC) plug for receiving AC power; at least one master outlet, coupled to the AC plug; at least one salve outlet; a power switch, whose first end is coupled to the AC plug, and whose second end is coupled to the slave outlet; a current sensor, coupled to the master outlet, for receiving a feedback current from the master outlet, as well as outputting a sensing signal; an operational amplifier, coupled to the current sensor, for amplifying and comparing the sensing signal with a first reference voltage to output a first control signal, and for amplifying and comparing the sensing signal with a second reference voltage to output a second control signal; a power supply, coupled to the AC plug, operational amplifier and power switch, which is controlled by the first control signal, so as to convert the AC power into a supply voltage to provide to the power switch; a driver, coupled to the operational amplifier and power switch, which receives the second control signal and outputs a driving signal to the power switch, so as to control the switching of the power switch. 
   Furthermore, a master/slave outlet system according to a second embodiment of the present invention, compared with said master/slave outlet system according to the first embodiment of the present invention, additionally comprises a master control switch, coupled between the AC plug and the master outlet, power switch and power supply. The master control switch is used to control the AC power introduced by the AC plug to conduct or be switched off the master outlet, power switch and power supply, in order to provide security for use of electrical power. 
   Hence, the master/slave outlet system according to the present invention can address the issues of user convenience, security and power-saving; meanwhile, it can also satisfy the requirement for the specification of green energy (standby power &lt;1 W). 
   The general summary set out supra as well as the detailed description illustrated infra are simply exemplary, which are presented to further explain the true scope of the present invention. Other objectives and advantages of the present invention will be construed in the following detailed description and appended drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  shows a perspective diagram of a single switch control extension line; 
       FIG. 2  shows a perspective diagram of an individual switch control extension line; 
       FIG. 3  shows a perspective diagram of a first embodiment according to the present invention; 
       FIG. 4  shows a circuit block diagram of the first embodiment according to the present invention; 
       FIG. 5  shows a perspective diagram of a second embodiment according to the present invention; and 
       FIG. 6  shows a circuit block diagram of the second embodiment according to the present invention. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Refer to  FIG. 3 , wherein a perspective diagram of a first embodiment according to the present invention is shown. From the prospect of the first embodiment according to the present invention, it can be seen that the illustrated master/slave outlet system  3  comprises an AC plug  30 , an extension line  32  and a body  31 , wherein on the body  31  there is installed at least one master outlet  34 , at least one slave outlet  36  and at least one power outlet  37  directly connected to AC plug  30 , and inside the body  31  there is installed a control circuit  35 ; besides, said master outlets  34 , slave outlets  36  and the directly connected power outlets  37  are all coupled to the control circuit  35 . Thereby, when the electronic device connected to the master outlet  34  has been supplied with sufficient current, the slave outlet  36  will become conducting, allowing turning on the electronic device connected to the corresponding slave outlet. Besides, when the electronic device connected to the master outlet  34  is turned off or enters into sleep mode, the electronic device connected to the slave outlet  36  will accordingly be turned off. 
   In conjunction with  FIG. 3 , refer to  FIG. 4 , in which a circuit block diagram of the first embodiment according to the present invention is shown. In said first embodiment according to the present invention, the circuit blocks of the master/slave outlet system  3  consist of an AC plug  30 , master outlets  34 , slave outlets  36 , directly connected power outlets  37  and a control circuit  35 . At the same time, the control circuit  35  comprises a current sensor  350 , a power switch  351 , an operational amplifier  352 , a driver  354  and a power supply  356 . 
   In the first embodiment, the AC plug  30  is used to receive AC power (AC). The master outlet  34  and directly connected power outlet  37  are all coupled to the AC plug  30 . Whereas the slave outlet  36  are coupled to the AC plug  30  by means of the power switch  351 . Besides, in the control circuit  35 , the current sensor  350  is coupled to the master outlet  34  and, thus, can receive a feedback current IFB from the master outlet  34 , and outputs a sensing signal S 1 . The operational amplifier  352  is coupled to the current sensor  350 , and receives a first reference voltage VR 1  and a second reference voltage VR 2 . The operational amplifier  352  amplifies and compares the sensing signal S 1  with the first reference voltage VR 1  so as to output a first control signal SC 1 , and also amplifies and compares the sensing signal S 1  with the second reference voltage VR 2  to output a second control signal SC 2 . In the aforementioned texts, the first reference voltage VR 1  is smaller than the second reference voltage VR 2 . 
   The power supply  356  is coupled to the AC plug  30 , operational amplifier  352  and power switch  351 , which is controlled by the first control signal SC 1  to convert the AC power into a supply voltage to allow use by the power switch  351 . The driver  354  is coupled top the operational amplifier  352  and power switch  351  for receiving a second control signal SC 2 , and also outputs a driving signal SD 1  to the power switch  351  for controlling the switching in the power switch  351 . 
   Referring again to  FIG. 4 , the power supply  356  receives the first control signal SC 1  from the operational amplifier  352  via a first optically coupled (OC) switch  353 . Moreover, the driver  354  receives the second control signal SC 2  from the operational amplifier  352  through a current extracting component  355 . Additionally, the power switch  351  is preferred to be a relay; meanwhile, the driver  354  is preferred to be a transistor (BJT) or a Field Effect Transistor (FET), while an AC/DC converter is a preferable choice for the power supply  356 . 
   Referring again to  FIG. 4 , when the electronic device connected to the master outlet starts to operate, the current sensor  350  receives from the master outlet  34  the feedback current IFB generated during the operation of the electronic device, and converts the received feedback current IFB into the sensing signal S 1  for output. Next, the operational amplifier  352  first compares the sensing signal S 1  with the first reference voltage VR 1 , and then compares the sensing signal S 1  with the second reference voltage VR 2 . In case the voltage of the sensing signal S 1  is higher than the first reference voltage VR 1 , the operational amplifier  352  sends a first control signal SC 1  to the power supply  356 ; at this moment, the power supply  356  will be under the control of the first control signal SC 1 , thus outputting the supply voltage DC to the power switch  351 , so as to provide required power for operations to the power switch  351 . 
   Subsequently, when the sensing signal S 1  raises up to an extent that the voltage thereof exceeds the second reference voltage VR 2 , the operational amplifier  352  sends the second control signal SC 2  to the driver  354 . The driver  354  is now controlled by the second control signal SC 2 , and outputs the driving signal SD 1  to the power switch  351  for controlling the conductance of the power switch  351 . At this time, AC power will be introduce via the AC plug  30 , flowing through the conducting power switch  351 , into the slave outlet  36 , so as to provide the use of electrical power by the electronic device connected to the salve outlet  36 . 
   Referring once again to  FIG. 4 , when the electronic device connected to the master outlet  34  is turned off or enters into sleep mode, the feedback current IFB from the master outlet  34  becomes almost zero, thus the sensing signal S 1  sent by the current sensor  350  is accordingly also almost zero. Therefore, the voltage of the sensing signal S 1  is smaller than the second reference voltage VR 2 , thus the operational amplifier  352  transfers the second control signal SC 2  to the driver  354 . The driver  354  is now under the control of the second control signal SC 2 , outputting the driving signal SD 1  to the power switch  351 , which controls the power switch  351  to be turned off. At this time, the provision of the AC power introduced from the AC plug will be stopped, preventing the electronic device connected to the slave outlet  36  from use of electrical power. 
   Next, when the voltage of the sensing signal S 1  drops below the first reference voltage VR 1 , the operational amplifier controls the power supply  356  to stop outputting the supply voltage DC to the power switch  351 . Hence, the master/slave outlet system  3  according to the present invention may resolve said problems of convenience, security and power-saving, and simultaneously meet the requirements specified in the standard of green energy (standby power &lt;1 W). 
   In conjunction with  FIG. 3 , refer to  FIG. 5 , wherein a perspective diagram of a second embodiment according to the present invention is shown. The components depicted in the second embodiment according to the present invention are identical to the ones shown in the first embodiment according to the present invention, which are all marked with the same reference numbers or symbols. The circuit operation principles and effects achieved thereby found in both the first and the second embodiments are the same, whereas their major differences lie in: from the prospect of the master/slave outlet system  3 ′ of the second embodiment according to the present invention, it further comprises an active switch  33 , in which the active control switch  33  is installed on the body  31 , coupled to the control circuit  35  inside the body  31 . 
   In conjunction with  FIG. 4 , refer to  FIG. 6 , wherein a circuit block diagram of the second embodiment according to the present invention is shown. The components depicted in the second embodiment according to the present invention are identical to the ones shown in the first embodiment according to the present invention, which are all marked with the same reference numbers or symbols. The major differences there between are: the master/slave outlet system  3 ′ of the second embodiment according to the present invention further comprises an active switch  33  coupled between the AC plug  30  and the master outlet  34 , directly connected power outlet  37 , power switch  351  and power supply  356 . The active control switch  33  is used to control the introduction of AC power from the AC plug  30 , conducting or switching off the master outlet  34 , directly connected power outlet  37 , power switch  351  and power supply  356 , so as to provide secure use of electrical power. 
   In summary, the master/slave outlet system according to the present invention provides master outlets and slave outlets, and when the electronic device connected to the master outlet is supplied with enough current, the slave outlet will become conducting, allowing the electronic device connected to the slave outlet to be turned on accordingly. When the electronic device connected to the master outlet is turned off or enters into sleep mode, the electronic device connected to the slave outlet will be also turned off accordingly. In this way, the master/slave outlet system according to the present invention can resolve the problems of convenience, security and power-saving, and at the same, meets the requirements set by the specification of green energy (standby power &lt;1 W). 
   The aforementioned descriptions simply illustrate the preferred embodiments of the present invention, but the features and characteristics of the present invention are by no means restricted thereto. All possible modifications or alternations that any skilled persons of the relevant arts may conveniently consider are deemed to be encompassed within the scope of the present invention delineated by the claims set out hereunder.