Patent Publication Number: US-2013229743-A1

Title: Energy efficient power adapter

Description:
RELATED APPLICATION 
     This application is related to and claims priority to U.S. Provisional Patent Application Ser. No. 61/140,456 filed Dec. 23, 2008, titled “Energy Efficient Power Adapter,” which is hereby incorporated by reference in its entirety herein. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to a power adapter and, in particular, to an energy efficient power adapter. 
     BACKGROUND 
     Standby power, also referred to as vampire power, ghost load, idle current, phantom load, or leaking electricity, refers to the electrical power consumed by electronic appliances while switched off or in a standby mode. A common example of an “electricity vampire” is an AC power adapter or wall wart that has no power-off switch. For example, an AC power adapter for a cellular telephone will continue to supply a charge even if the batteries are fully charged or if the cellular telephone is not plugged in. Other electrical devices consume standby power for functional reasons, which are at times justified (e.g., a temperature sensor on a refrigerator) or unjustified (e.g., displaying a digital clock on a radio when nobody is present). The wasted standby power of household electronic devices is typically very small for any one particular device, but in the aggregate the power consumed by all such devices within a household becomes significant. 
     According to the United States Department of Energy, “Many appliances continue to draw a small amount of power when they are switched off. These ‘phantom’ loads occur in most appliances that use electricity, such as VCRs, televisions, stereos, computers, and kitchen appliances. In the average home, 75% of the electricity used to power home electronics is consumed while the products are turned off. This can be avoided by unplugging the appliance or using a power strip and using the switch on the power strip to cut all power to the appliance.” US Department of Energy, “Home Office and Home Electronics,” 15 Jan. 2008 available at http://www1.eere.energy.gov/consumer/tips/home_office.html, last accessed on Dec. 3, 2008. 
     SUMMARY 
     According to one embodiment, an AC power adapter for providing voltage to an electrically-operated device includes a power converter module electrically coupled to a power source via at least one hot lead and at least one neutral lead. The power converter module is configured to convert voltage received from the power source to voltage suitable for use by the electrically-operated device. The AC power adapter also includes a relay circuit coupled to the hot lead to control the voltage passing from the power source to the power converter module. 
     The above summary of the present invention is not intended to represent each embodiment or every aspect of the present invention. The detailed description and Figures will describe many of the embodiments and aspects of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing and other advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. 
         FIG. 1  illustrates a circuit diagram for a conventional AC power adapter. 
         FIG. 2  illustrates a circuit diagram for an AC power adapter according to one embodiment. 
         FIG. 3  illustrates a circuit diagram for an AC power adapter according to another embodiment. 
     
    
    
     While the invention is susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. 
     DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS 
     Referring to  FIG. 1 , a circuit diagram is illustrated for a conventional AC power adapter  100  for connecting an electrically-operated device  102  to a power grid  104 . The conventional power adapter  100  includes two contacts  106 , 108  such as, for example, pins, prongs and/or blades that mechanically and electrically couple to corresponding holes and/or slots in an electrical wall socket connected to the power grid  104 . One of the contacts is a hot contact  106 , which passes AC voltage to the power adapter  100 , and the other contact is a neutral contact  108 , which returns AC voltage from the power adapter  100 . It is contemplated that in some instances, the power adapter  100  may include two or more hot contacts  106  and/or an additional contact for grounding the housing of the power adapter  100 . It is further contemplated that the contacts may be configured according to any suitable configuration so as to allow for mechanical and electrical coupling with a corresponding wall socket connected to the power grid. For example, the contacts of the power adapter can be configured to meet any standard domestic or international adapter and socket configuration including, but not limited to, NEMA 1-15, NEMA 5-15, JIS C 8303, CEE 7/16, CEE 7/17, BS 4573, BS 546, CEE 7/4, Gost 7396, CEE 7/7, BS 1363, SI 32, AS 3112, CPCS-CCC, IRAM 2073, SEV 1011, CEI 23-16/VII, and CEI 23-5. 
     The power adapter  100  further includes a power converter module  110 . The power converter module  110  includes electronic circuitry for converting the power supply from the power grid  104  into a power supply suitable for use by the electrically-operated device  102 . Many electrically-operated devices  102  require a DC power source. In such instances, the power converter module  110  can include electronic circuitry such as, for example, a transformer, a rectifier circuit, a capacitor, a switch, a linear regulator, combinations thereof and/or the like. On the other hand, some electrically-operated devices require an AC power source operating at a different voltage or frequency than that of the power grid. In those instances, the power converter module can include electronic circuitry such as, for example, step-down transformer or step-up transformer circuits. 
     The power converter module  110  is electrically coupled to the hot contact  106  and the neutral contact  108  by a hot source lead  112  and a neutral source lead  114 . The power converter module  110  is electrically coupled to the electrically-operated device  102  by a hot device lead  122  and a neutral device lead  124 . 
     In some instances, the power converter module  110  is located within a housing of the electrically-operated device  102 . In other instances, the hot contact  112 , the neutral contact  114 , and the power converter module  110  are built into a housing that is separate from the housing of the electrically-operated device  102 . The ends of device leads  122 , 124  opposite the power converter module  110  may be formed into a male or female plug for connecting to a corresponding socket in the electrically-operated device  102 . Such a configuration is commonly referred to as a “wall wart” or “power brick.” In still other instances, the power converter module  110  is located in a housing that is separated from the electrically-operated device  102  and the contacts  112 , 114 . Again, the ends of device leads  122 , 124  opposite the power converter module  110  may be formed into a male or female plug for connecting, at one end, to a corresponding socket in the electrically-operated device  102 . Optionally, the other ends of the device leads may be formed into a male or female plug for connecting to a corresponding socket in the power conversion module  110 . Similarly, the ends of the source leads  112 , 114  opposite the contacts  106 , 108  may be formed into a male or female plug for connecting to a corresponding socket in the power converter module  110 . 
     Referring to  FIG. 2 , a circuit diagram is illustrated for a power adapter  200  for connecting an electrically-operated device  202  to a power grid  204  according to one embodiment of the present concepts. The power adapter  200  includes at least one hot contact  206  and hot source lead  212 , at least one neutral contact  208  and neutral source lead  214 , a power converter module  210 , at least one hot device lead  222  and at least one neutral device lead  224  as described above with respect to  FIG. 1 . The power adapter  200  further includes a relay circuit  216  for selectively isolating the voltage passing through the hot source lead  212  from the hot contact  206  to the power converter circuit  210 . The relay circuit  216  is electrically coupled to a switch circuit  218 . When the switch  218  is activated (i.e., closed), a current passes to the relay circuit  216 , which in turn causes the hot source lead  212  to pass the voltage from the hot contact  206  to the power converter module  210 . When the switch  218  is deactivated (i.e., open), the relay circuit  218  prohibits the hot source lead  212  from passing voltage from the hot contact  206  to the power converter module  210 . Thus, when the switch circuit  218  is deactivated, no voltage is drawn from the power grid  204 . 
     Any suitable relay circuit  216  can be utilized such as, for example, a solid-state relay, an electromechanical relay, latching relay, reed relay, mercury-wetted relay, polarized relay, machine tool relay, contactor relay, buchholz relay, forced-guided contacts relay, combinations thereof and/or the like. The relay circuit  216  can be located within the same housing as the power converter module  210  or external thereto. Similarly, any suitable switch can be utilized such as, for example, a single pole-single throw switch, a single pole-double throw switch, a single pole changeover switch, a double pole-single throw switch, a double pole-double throw switch, a double pole changeover switch, an intermediate switch, a biased switch, a mercury tilt switch, a knife switch, a transistor, a centrifugal switch, a DIP switch, a Hall-effect switch, an inertial switch, a membrane switch, a toggle switch, a transfer switch, combinations thereof and/or the like. The switch circuit  218  can be located in the same housing as the power converter module  210 , external to the housing of the power converter module  210 , and/or in the housing of the electrically-operated device  202 . It is contemplated that according to some embodiments, the switch circuit  218  can be electrically and/or mechanically coupled to a power ON/OFF button or dial located in or on the electrically-operated device  202 . In accord with other embodiments, the switch  218  is a remotely-operated switch that can be activated and/or deactivated, for example, via an infrared signal, an ultraviolet signal, combinations thereof and/or the like. In accord with still other embodiments, the switch  218  is activated and/or deactivated by a timer. 
     It is further contemplated that electrically-operated devices  202  may include electronic circuitry that automatically deactivates and/or activates the switch circuit  218  depending upon whether power is required for the electrically-operated device  202 . For example, a cellular telephone continues to draw power from the power grid when connected to a conventional power adapter regardless of whether the cellular telephone battery is completely charged. It is contemplated that the switch circuit  218  can be connected to electronic circuitry within the cellular telephone that deactivates the switch circuit  218  once the battery becomes fully charged and reactivates the switch once the battery loses a threshold quantity of charged energy. As another example, televisions typically require standby power to enable instant power-up by remote control. It is contemplated that the television can include a small battery for maintaining the television in standby mode and electronic circuitry for activating and deactivating the switch circuit  218  when the battery needs to be recharged (e.g., when the battery charge falls below a predetermined threshold). 
     According to an alternative embodiment, the switch circuit  218  of the embodiment illustrated in  FIG. 2  can be omitted as shown in  FIG. 3 . Referring to  FIG. 3 , a power adapter  300  includes at least one hot contact  306  and hot source lead  312 , at least one neutral contact  308  and neutral source lead  314 , a power converter module  310 , at least one hot device lead  322 , at least one neutral device lead  324  and a relay circuit  316  as described above with respect to  FIG. 2 . The power adapter further includes relay leads  320  coupled to the relay circuit  316  at one end. The other end of the relay leads  320  are formed into a male or female plug  326  with the hot device lead  322  and the neutral device lead  324  for electrical and mechanical coupling with a corresponding socket  328  in an electrically-operated device  302 . According to this embodiment, whenever the plug  326  is connected to the socket  328  of the electrically-operated device  302 , a current is passed to the relay circuit  316  via the relay leads  320 . The relay circuit  316  closes allowing the hot source lead  312  to pass voltage from the hot contact  306  to the power converter module  310 . Conversely, whenever the plug  326  is removed from the socket  328 , no current is passed to the relay circuit  316 . Thus, when an electrically-operated device is not connected to the power adapter  300 , no voltage is drawn from the power grid  304 . 
     A power adapter  300  according to this embodiment may be particularly useful in situations where an electrically-operated device is only connected to the power adapter  300  for battery charging purposes. For example, a conventional power adapter for a cellular telephone continuously draws power from the power grid when the power adapter is plugged into the wall socket regardless of whether the cellular phone is connected to the power adapter. This is because the power converter module forms a closed circuit drawing power from the power grid. When a power adapter  300  according to this embodiment is utilized, no power is drawn from the power grid when the cellular phone is not connected for charging. 
     While the present invention has been described with reference to one or more particular embodiments, those skilled in the art will recognize that many changes may be made thereto without departing from the spirit and scope of the present invention. Each of these embodiments and obvious variations thereof is contemplated as falling within the spirit and scope of the invention, which is set forth in the following claims.