Abstract:
Power devices for electronic devices, such as chargers for portable rechargeable devices and/or AC adapters, are disclosed, each power device provided with a switch for de-powering at least a portion of the power device when the electronic device is either not drawing power or is disconnected from the power device.

Description:
FIELD OF THE INVENTION 
       [0001]    The invention relates to power devices and, in particular, to power devices having an automatic shut-off feature to reduce or eliminate useless power draw from an outlet and, more particularly, to automatic shut-off power adapters and/or chargers removably connectable to electronic devices for powering by the adapters/chargers. 
       BACKGROUND 
       [0002]    Many portable electronic devices exist today for consumers. In fact, many consumers carry multiple portable devices such as music players, cellular telephones, personal data assistants, smartphones such as those marketed as a Blackberry by Research In Motion, Inc., portable global positioning system devices, etc. These portable devices are powered by a rechargeable, on-board battery. 
         [0003]    In order to charge the battery, the portable device (or possibly just the battery thereof) is connected to a power device. Typically, the power device is a combination of a charger and a power adapter so that alternating current with an input voltage is received and converted to direct current, and the voltage is stepped-down to an output voltage for which the battery is designed. It should be noted that, depending on source power and output power requirements, the power device need not always convert and step, instead being able to do one or the other, such as may be the case for a DC-DC adapter used only to step-down the input voltage to an output voltage or simply receiving input power and delivering output power to the battery. 
         [0004]    The power device typically has a first end with a pair of prongs that are received in and connected to a receptacle of a power outlet, and has a cable extending from the first end to a second end, the second end having a connector for electrical connection with the portable device. The power device also typically includes internal circuitry for the power conversion and stepping, and this circuitry requires an enlarged portion (enlarged relative to the cable of the power device). The enlarged portion is typically located at or adjacent the first end, though it may be inline and between the first and second ends or be located at the second end such as in a desktop-style or cradle-type charger. 
         [0005]    Regardless of the configuration, the usage of the power device is almost uniformly identical. Specifically, a user connects the first, prong-bearing end of the power device with a receptacle, such as a receptacle of a wall-oriented/mounted power outlet. The power device second end is placed in a convenient place for the user to reach, and the portable device is connected to the second end when recharging is needed or desired, commonly on a daily basis at the end of a day. When the user desires to use or carry it, the portable device is disconnected from the power device, and the second end is left in the convenient place. Rarely, if ever, does the user think to unplug the power device from the receptacle. One of the reasons for this is that receptacles are typically behind furniture or in another location that is difficult to reach, or it is just too much trouble to unplug when it is known that it will need to be plugged in again a relatively short period of time. 
         [0006]    There is a growing but still largely unappreciated recognition by users that leaving the power device plugged in allows the power device to continue to draw current or power from the receptacle despite no portable device being connected therewith. This power draw is referred to as phantom load. To be more precise, phantom load is residual power consumption by power devices when not connected to their host electronic device, or when the electronic device is shut off. 
         [0007]    Phantom load is becoming a greater issue for the public. Electrical devices that result in the described phantom load are continually increasing in per capita usage, populations increase exponentially, and great portions of the world&#39;s population are gaining the discretionary capital that enables the purchase of such devices. Energy is becoming more expensive on a monetary basis, and energy production overwhelmingly has an environmental impact, such as fossil fuel or nuclear energy. 
         [0008]    Extensive effort has been and continues to be put into development of energy-efficient devices of all sorts. The “Energy Star” program sponsored by the United States Environmental Protection Agency and the United States Department of Energy is well known, though principally for energy efficiency appliances and building products such as glass doors and windows. In parallel with Energy Star standards efforts, a variety of state and federal laws have been enacted that are directed toward external power-supply products, which includes power devices or chargers for portable electronic devices. The most-recent standard for such portable devices is version 2.0 and is considered a push beyond simply forcing the industry to use power efficient components and layouts, requiring more complex power devices and supplies. 
         [0009]    A recent development that arose during the preparation of the present application is a prototype device from Nokia that operates with a mechanical switch. Specifically, the Nokia device has a first end receivable in a power receptacle and including a housing for internal circuitry that provides the charger/adapter functions. The Nokia device is turned on by depressing a button on the housing; when the internal circuitry recognizes the electronic device is fully charged, the button is released and the Nokia device is turned off. 
         [0010]    While it is believed to have been developed after conception of the invention of present application, the Nokia device highlights some interesting points about efforts in this arena. For instance, the button of the Nokia device is a mechanical button and requires some type of mechanism for releasing the button for the “off” state. The button is also located on a housing for the internal circuitry that is separate from the electronic device connector, the connector being a two-terminal device (that is, having “+” and “−” terminals). The Nokia device also requires some type of mechanism for determining when the device should be shut down. 
         [0011]    As discussed above, most people do not bother to unplug their power devices when they remove the portable electronic device therefrom. The Nokia device certainly relieves a user from having to plug and un-plug the device, but it still requires a user to reach to wherever the device is received in a receptacle in order to turn on the device. 
         [0012]    In order to be a true “zero-energy” device, the power input (i.e., AC input) to the power device must be cut. That is, the point in the power device circuitry where the circuit is broke is important: a switch or the like simply on a end-point terminal of the power device may cut the power being delivered to an electronic device connected thereto that is fully charged, but, such allows the internal circuitry to draw power so that the effect of such would be no different than simply removing the electronic device itself. 
         [0013]    Towards this end, the Nokia device displays a uniform manner of thinking in the industry: a switch for connecting or disconnecting the AC power must be co-located with or closely proximate to the AC input such as the power prongs. 
         [0014]    Accordingly, it is desirable and there is a need for an improved power device, charger or otherwise, for reducing phantom load when a portable electrical device is disconnected from the power device or otherwise not intended to be drawing power from the power device. 
       SUMMARY 
       [0015]    In a first aspect, a power device for supplying power to a portable rechargeable electronic device is disclosed including a first portion for receiving electrical input power from a source, the input having an input voltage, a second portion for delivering electrical output power to the electronic device, the output power having an output voltage, a connector located on the second portion and removably connectable with the electronic device, and a switch assembly located remote from the first portion, the switch assembly having a member movable to and between first and second positions corresponding to respective “on” and “off” states, wherein the power device receives the input power in the “on” state, and the power device draws no input power in the “off” state. 
         [0016]    In a form, the switch assembly member is a throw. In some forms, the throw may be a toggle or rocker throw. 
         [0017]    In some forms, the switch assembly member is a sheath longitudinally movable to and between the first and second positions. 
         [0018]    In some forms, the switch assembly member is manually movable to both the first and second positions by a user. 
         [0019]    In some forms, the power device further includes a cable extending between the first portion and the second portion, and the first portion includes first and second prongs for electrical communication with a receptacle of a power outlet, circuitry electrically connected to the prongs and to the cable for changing the input power to the output power, and a housing from which the prongs and cable extend, the circuitry disposed within the housing, and the cable includes a first pair of wires for delivering power to the electronic device and a second pair of wires for communicating with the switch assembly. The second pair of wires may be connected such that the switch in the second position disconnects a prong from at least a portion of the circuitry to prevent power from being drawn by the power device. The switch assembly may be located proximate the second portion and connector thereof. 
         [0020]    In another aspect, a power device for supplying power to a portable rechargeable electronic device is disclosed including a first portion for receiving electrical input power from a source, the input having an input voltage, a second portion for delivering electrical output power to the electronic device, the output power having an output voltage, circuitry for converting the input power voltage to the output power voltage and for determining an “off” state of the circuitry, a connector located on the second portion and removably connectable with the electronic device, and a switch assembly having powered terminals, the switch assembly responsive to movement of at least a movable portion thereof to electrically connect the terminals and to provide an output signal to activate the circuitry to the “on” state, wherein the circuitry automatically turns the circuitry to the “off” state, the circuitry drawing no power when in the “off” state. 
         [0021]    In some forms, the switch assembly movable portion is biased to a first position and is movable to a second position by force applied by the user, cessation of the force permitting the movable portion to return to the first position, the switch assembly producing the output signal only when in the second position. 
         [0022]    In some forms, the switch assembly movable portion is a pushbutton spring-biased to a first position and is movable to a second position by force applied by the user, the pushbutton in the second position electrically connecting the terminals to produce the output signal, the output signal being a momentary signal from a momentary connection of the terminals, and releasing the pushbutton permits return thereof to the first position. 
         [0023]    In some forms, the switch assembly movable portion is an orientation-dependent switch. 
         [0024]    In some forms, the switch assembly movable portion is a motion-sensing switch. 
         [0025]    In some forms, the circuitry includes a timer programmed with a predetermined time period, the timer providing a timer signal to the circuitry at the conclusion of the time period, and the circuitry automatically changes to the “off” state in response to the timer signal. 
         [0026]    In some forms, the circuitry includes a power sensing portion programmed with a predetermined threshold power level, wherein the circuitry automatically changes to the “off” state in response to the output power being at or below the threshold power level. 
         [0027]    In some forms, the circuitry includes a latching relay that is closed in response to the switch assembly output signal, the latching relay being opened in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0028]    In some forms, the circuitry includes a solid state switch element that opens in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0029]    In some forms, the switch assembly is located remote from the first portion. The switch assembly may be located proximate the second portion. 
         [0030]    In a further aspect, a power device for supplying power to a portable rechargeable electronic device is disclosed including a first portion for receiving electrical input power from a source, the input having an input voltage, a second portion for delivering electrical output power to the electronic device, the output power having an output voltage, circuitry for converting the input power voltage to the output power voltage and for determining an “off” state of the circuitry, a connector located on the second portion and removably connectable with the electronic device, and a switch assembly located remote from the first portion and having powered terminals, the switch assembly responsive to movement of at least a movable portion thereof to electrically connect the terminals and activate the circuitry to the “on” state, wherein the circuitry automatically turns the circuitry to the “off” state, the circuitry drawing no power when in the “off” state. 
         [0031]    In some forms, circuitry includes a timer programmed with a predetermined time period, the timer providing a timer signal to the circuitry at the conclusion of the time period, and the circuitry automatically changes to the “off” state in response to the timer signal. 
         [0032]    In some forms, the circuitry includes a power sensing portion programmed with a predetermined threshold power level, wherein the circuitry automatically changes to the “off” state in response to the output power being at or below the threshold power level. 
         [0033]    In some forms, the switch assembly provides an output signal to activate the circuitry to the “on” state, and the circuitry includes a latching relay that is closed in response to the switch assembly output signal, the latching relay being opened in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0034]    In some forms, the circuitry includes a solid state switch element that opens in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0035]    In an additional aspect, a power device for supplying power to a portable rechargeable electronic device is disclosed including a first portion for receiving electrical input power from a source, the input having an input voltage, a second portion for delivering electrical output power to the electronic device, the output power having an output voltage, circuitry for converting the input power voltage to the output power voltage and for determining an “off” state of the circuitry, a connector located on the second portion and removably connectable with the electronic device, and a switch assembly having powered terminals to change the circuitry to the “on” state, wherein the circuitry automatically turns the circuitry to the “off” state, the circuitry drawing no power when in the “off” state. 
         [0036]    In some forms, the switch assembly movable portion is biased to a first position and is movable to a second position by force applied by the user to change the circuitry to the “on” state. Cessation of the force may permit the movable portion to return to the first position. 
         [0037]    In some forms, the circuitry includes a timer programmed with a predetermined time period, the timer providing a timer signal to the circuitry at the conclusion of the time period, and the circuitry automatically changes to the “off” state in response to the timer signal. 
         [0038]    In some forms, the circuitry includes a power sensing portion programmed with a predetermined threshold power level, wherein the circuitry automatically changes to the “off” state in response to the output power being at or below the threshold power level. 
         [0039]    In some forms, the circuitry includes a latching relay that is closed in response to the switch assembly changing the circuitry to the. “on” state, the latching relay being opened in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0040]    In some forms, the circuitry includes a solid state switch element that opens in response to the output power being at or below a threshold power level to change the circuitry to the “off” state. 
         [0041]    In some forms, the switch assembly is located remote from the first portion. 
         [0042]    In some forms, the switch assembly is located proximate the second portion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0043]    In the Figures,  FIG. 1  is a partially fragmentary view of a first form of a power device of the present invention, the power device having a first end for connecting with a power source, a second end for connecting with an electrical device, and an in-line two-position switch; 
           [0044]      FIG. 2  is a fragmentary view of the power device of  FIG. 1  showing line designations for wires of a cable of the power device; 
           [0045]      FIG. 3  is a simplified circuit diagram for the fragmentary portion of the power device of  FIG. 2 ; 
           [0046]      FIG. 4  is a representational view of a cross-section of a first form of the cable of the power device of  FIG. 1 ; 
           [0047]      FIG. 5  is a representational view of a cross-section of second form of the cable of the power device of  FIG. 1 ; 
           [0048]      FIG. 6  is a representational view of a form of the power device including an outer sheath positioned proximate a connector, the sheath being movable to and between first and second positions, the sheath being in a first position when the connector is not connected to an electrical device and in a second, retracted position relative to the connector when the connector is joined with an electronic device, the second position causing an electrical circuit to be closed; 
           [0049]      FIG. 7  is a representational view of a form of the power device including a mechanically actuated switch, which may also include an integrated circuit coupled with the mechanically actuated switch; 
           [0050]      FIG. 8  is a circuit diagram illustrating aspects of different forms of a power device of the current invention; 
           [0051]      FIG. 9  is a partial circuit diagram showing an optional form of internal circuitry including a relay switch; 
           [0052]      FIG. 10  is a circuit diagram of an exemplary form of the power device showing a switch provided to open the circuit at or proximate one of prongs to prevent power from being drawn by the power device; 
           [0053]      FIG. 11  is a circuit diagram of an exemplary form of the power device showing a power-on or activating switch, such as a solid state switch, a portion of the circuit monitoring the transformer secondary pulses to create a voltage proportional to the load current to drive an auto-shutoff switch; 
           [0054]      FIG. 12  is a circuit diagram of an exemplary form of the power device showing an electromechanial relay provided to open and close the circuit at or proximate one of prongs to prevent power from being drawn by the power device, the electromechanical relay being connected with a switch for activating and closing the relay and the circuit; and 
           [0055]      FIG. 13  is a circuit diagram of an exemplary form of the power device showing a switch for determining the state of the power device with a current sensing circuit. 
       
    
    
     DETAILED DESCRIPTION 
       [0056]    Generally stated, the present invention includes a power device, such as a charger or adapter, for providing power to an electrical device that is designed to shut off or at least reduce power draw from a power source when the electrical device does not need power. In a more finite form of the invention, the power device is an AC-DC charger and converter for a portable rechargeable electronic device that is connectable with a connector on the power device. In the preferred forms, the power device has a housing co-located at a first end with prongs for connecting with an electrical sources such as an outlet, has a cable extending from the housing to a second end, and has the connector located at the second end for connecting with the portable electronic device. In a more preferred form, the second end includes switch components for switching the power device from an “off” state (when the electronic device is fully-charged or not connected to the connector) to an “on” state allowing power to be delivered to a connected electronic device. In one form, the switch components operate to cut power on the AC portion of the internal circuitry of the power device so that the power draw is zero or negligible (i.e., measured in microwatts). In another form, the switch components operate to initiate a power device “on” state while a timer circuit, a power sense circuit or other circuit means in the power device are used to switch the power device to an “off” state so that the power draw is zero or negligible. 
         [0057]    Referring initially to  FIGS. 1-3 , a relatively basic form of a power device  10  is shown. The power device  10  has a first end  12  for connection with a receptacle of a power outlet (not shown), the power outlet providing electrical power to the power device first end  12  via prongs  14  that are inserted within the receptacle. The power device  10  also has a second end  16  for connecting with a receptacle  21  of an electronic device  20  (see  FIG. 7 ). The electronic device  20  may be any type of device that may be connected or disconnected, for example a portable device such as a cellular telephone or music player or the like that is connected for charging and generally disconnected for use, though these electronic devices  20  are often left connected for longer durations of time than are necessary for fully charging the electronic device  20 . 
         [0058]    Towards this end, the power device  10  includes electronic circuitry  30 , discussed below and shown in  FIG. 8 , for altering input power from the receptacle at the prongs  14  to output power delivered to the electronic device  20 . The circuitry  30  is generally located within a housing  32  preferably positioned proximate to the first end  12 . For instance, the power device  10  may receive 120 VAC at the prongs  14  and, after conversion and stepping, delivers 5 VDC from the ground G and current output D, discussed below. 
         [0059]    The power device  10  includes a connector  40  providing the ground G and current output D. In some forms, the connector  40  is directly connected to the electronic device receptacle  21 , though there may also be an intermediate connector  23  (see  FIG. 7 ). The intermediate connector  23  includes a receptacle  23   a  for receiving the connector  40  and a secondary connector  23   b  for receipt into the electronic device receptacle  21 . In a preferred form, a plurality of intermediate connectors  23  may be provided, and a user is able to select an intermediate connector  23  for a specific corresponding electronic device  20 . In this manner, features of the present power device  10  are enabled and supported while still allowing the use of any type of connector  40  (and connection with the electronic device  20 ). 
         [0060]    As can be seen in  FIGS. 1 and 2 , the power device  10  includes a cable  42  generally extending between and connected with the housing  32  and the connector  40 . As also can be seen, a switch assembly  50  is provided in-line with the cable  42 . In  FIG. 1 , a preferred form of the connector  40  is shown as a mini-USB connector having four wires  44   a - 44   d,  though other connectors  40  (standard or not) may be used, and, as discussed above, the connector  40  may be used with the intermediate connector  23  so that the secondary connector  23   b  is provided for use with the electronic device  20 . 
         [0061]    As is readily recognized, the switch assembly  50  includes a rocker or toggle throw  52  having two positions for connecting or disconnecting power to the connector  40 . In a first position, the throw  52  is in an “on” state so that a circuit is closed across switch terminals  50   a  and  50   b  (see  FIG. 3 ), and power is conducted to the electronic device  20  when connected to the connector  40 , while the throw  52  is in an “off” state when in the second position with the circuit being open across terminals  50   a  and  50   b  and no power is conducted to the electronic device  20 . 
         [0062]    Turning to  FIG. 3 , it can be seen that cable  42  includes the wires  44   a - 44   d  for, respectively, direct current output D, first live L 1 , second live L 2 , and ground G, as are known for use with a mini-USB. The lives L 1  and L 2  are connected to the throw  52  such that they are connected when the throw  52  is in the “on” state, and such that they are disconnected when the throw  52  is in the “off” state. The output D and ground G pass through the switch assembly  50  for connection to their respective pins of the mini-USB connector  40 . In comparison to  FIG. 8  showing the entire circuit including the alternating current input at the prongs  14 , the lives L 1  and L 2  have terminals  100  and  102 , respectively, while the output D and ground G are labeled as such and are at the second end  16 . When the connector  40  is used with the intermediate connector  23 , the secondary connector  23   b  thereof need only be provided with electrical connection with the output D and ground G terminals. 
         [0063]      FIG. 3  also shows the wiring of the wires  44   a - 44   d , while  FIGS. 4 and 5  illustrate how the wires  44   a - 44   d  in a single jacket  46  ( FIG. 4 ) or in a pair of jackets  46  ( FIG. 5 ) separated by a bridge  48  to provide additional isolation. Preferably,  26  American Wire Gauge (AWG) is used for the lives L 1  and L 2 , while  22  AWG may be used for the ground G and output D wires. It is preferred that total isolation between the lives L 1 , L 2  and the ground G/output D pairs is minimally 3 kV. 
         [0064]    In a preferred form of the power device  10 , the switch assembly  50  is located proximate to the connector  40 . In this manner, a user may easily manually switch the throw  52  between the “on” and “off” states when the electronic device  20  is connected or removed. In a preferred form, the switch assembly  50  includes a rocker switch, minimum rated at 2.5 A, to which the lives L 1  and L 2  are connected and including the throw  52 . The cable  42  is preferably in the order of 6 feet in length. 
         [0065]    More importantly, by utilizing the four-wire form described for the cable  42 , the switch assembly  50  opening or closing the switch terminals  50   a ,  50   b  on wires  44   b  and  44   c  (for the lives L 1  and L 2 ) are able to cut power anywhere in the power device  10 . In greater detail and with reference to  FIG. 8 , the power device  10  receives an input power at the prongs  14 . The portion of a charger/adapter that is most directly responsible for power draw or phantom load are a switcher IC chip  210  (see  FIG. 8 ), a transformer T (see  FIG. 8 ), and components downstream therefrom. As can be seen in  FIGS. 3 and 8 , the switch terminals  50   a  and  50   b  are generally remote from the other circuit components of the power device  10 . However, the wires  44   b  and  44   c  are connected with the circuit diagram of  FIG. 8  before the transformer T. Therefore, if the circuit is open across terminals  50   a  and  50   b , the power in the power device  10  is cut, the transformer T is unable to draw power, and the phantom load for the power device  10  is virtually eliminated. In an alternate form shown also shown in  FIG. 8 , lives L 1 ′ and L 2 ′ are provided, substituting for lives L 1  and L 2  as shown, and are able to cut power in the power device  10  before the rectifying diode bridge  420  by being opened at the switch terminals  50   a  and  50   b.    
         [0066]    Turning to  FIG. 6 , a second form of the power device is shown as power device  100 , also including a mini-USB connector  140 . More specifically, a different form of switch assembly  50  is shown. For simplicity, the power device  100  is shown having a cable  102  and a second end  104 , and it is understood that a first end and circuitry for the power conversion and step down would be incorporated into the power device  100  despite not being illustrated. In this form, the switch assembly  50  is shown as a sheath  110  provided on a portion of the cable  102 . The sheath  110  is longitudinally movable to and between a first position, illustrated in dashed lines, and a second position, illustrated in solid lines, wherein the first and second positions respectively corresponds to the “on” and “off” states discussed above. The sheath  110  is slid rearwardly and away from an end  140   a  of the connector  140  when an electronic device  20  is connected thereto. In so doing, a contact  112  positioned on the sheath  110  is moved into electrical connection with first and second terminals T (also corresponding to terminals  50   a  and  50   b  in  FIGS. 3 and 8 ) to close the circuit and allow the power device  100  to deliver power from the connector  140 . Preferably, the sheath  110  is biased forwardly so that, when the electronic device  20  is disconnected, the sheath  110  automatically turns the power device to the “off” state. 
         [0067]    In another form,  FIG. 7  illustrates a power device  200  including a mechanical motion-sensing switch  202  located proximate a connector  240 . In one form, the switch  202  may be a position-dependent switch, such as a mercury switch, so that the switch state (“on” or “off”) is dependent on the orientation of the switch  202  and the connector  240 . In another form, the switch  202  may be connected to an integrated circuit (IC)  210  (see, e.g.,  FIG. 8 ) so that, with a brief connection across terminals T, the IC  210  activates the switch  202  to the “on” state. Such brief connection-type switch  202  may be a mercury switch, may be a cantilever-contact switch, or another type of switch. 
         [0068]    In some forms, which may or may not be incorporated into the power device  200  of  FIG. 7 , the IC  210  may control a switch  340  located therein For instance, the IC  210  may include a timer for shifting the switch  340  to the “off” state, or the IC  210  may control the switch  340  in the form of an electromechanical relay or a solid state equivalent such as a MOSFET switch, as will be appreciated by one skilled in the art. To return the switch  340  to the “on” state, a number of means may be employed, such as a mechanical switch depressed briefly by a user, a position-dependent switch, a quick or brief connection switch that communicates with the IC  210 , as mere examples. 
         [0069]    In another form using the IC  210  and switch  340 , a load sensing device  400  may be incorporated within the IC  210 , as also shown in  FIG. 8 . The load sensing device  400  measures the power or load (i.e., watts or amperage) being drawn from the power device  10 . The load is markedly higher when the electronic device  20  is connected thereacross and drawing power than when the electronic device  20  is either removed or is powered off, or not charging it&#39;s battery. Accordingly, the IC  210  and load sensing device  400  recognize power draw or a lack thereof. The IC  310  can then open the switch  340  and/or possibly a switch external to the IC, to cease the current draw when it is recognized that no electronic device  20  is drawing therefrom. Preferably, such a form for the IC  210  includes a timer so that a slight pause in power or brief disconnect between the electronic device  20  and the connector at the ground G and output D does not cause the IC  210  to shut the power off by opening the switch  340 . As an example, the load sensing device  400  senses the pulse width and recognizes how slow or fast the pulse is repeated to determine the load. As such, when the battery  20   a  of the electronic device  20  ceases to draw power, the power device  10  can be calibrated to switch to the “off” state. 
         [0070]    It should be noted that the IC  210  and switch  340  and load sensing device  400  may be on-line or off-line and may be in a variety of configurations. As an example, the load sensing device  400  and IC  210  may be a pulse-width modulation (PWM) or other type of switch that carries its own IC, the PWM device shutting off a portion of the power device  10  while allowing a small portion (such as an incoming diode bridge  420  and input filter capacitors  422 , see  FIG. 8 ) to remain powered by a low current. Pressing a switch (discussed above) can be used to communicate with the small portion (ie., the incoming diode bridge  420  and filter capacitors  422 ) to re-actuate and power-up the power device  10 . In such a case, the PWM itself is also shut off until the power device is re-actuated. Therefore, while the power device  10  is not completely off, it is in a ultra-low power consumption state and is able to power-up more quickly. 
         [0071]    To be more specific with respect to pressing a switch,  FIG. 9  illustrates portions of a circuit diagram showing such usage and arrangement. In detail, it can be seen that the circuit  500  includes an input  502  and a rectifying diode bridge  504  that leads to filter capacitors  506 , which in turn lead to an optical isolation coupler  508  and nodes  510  for connection to IC  210  and transformer T (see  FIG. 8 ). As can be appreciated, an entire power device circuit is not illustrated, though the other portions of such are shown and described elsewhere herein, or would be understood by one skilled in the art. 
         [0072]    The circuit  500  includes a start switch  520 , which may be any type of switch for making at least a brief electrical connection. Preferably, the start switch  520  is a push-button switch so that, upon releasing, the contacts of the start switch  520  are disconnected and the start switch  520  is open. Upon brief electrical connection by the start switch  520  (such as by being depressed), a relay electrical contact  530  is connected. To detail, closing the start switch  520  causes electrical connection thereacross and, resultingly, powers a relay coil  532 . The relay coil  532  is akin to a solenoid so that it physically moves, this movement bring the plates  530   a  and  530   b  of the relay  530  together. The relay  530  is a latching-type relay so that it remains closed until otherwise instructed, powered or not. As can be seen, the relay coil  532  is connected to the start switch  520  by a closing diode  536  to effect this; the relay coil  532  is also connected to an opening diode  538  that is reversed in operation to the closing diode  536 . As will be discussed, when the power device  10  recognizes a sufficiently low power draw, a transistor  540  is activated to cause power to flow through the opening diode  538  and, thus, reverse the physical movement of the relay coil  532 , which in turn opens the relay plates  530   a ,  530   b.  In this manner, the power device  10  is returned to its “off” state. 
         [0073]    With respect to the above-described sufficiently low power draw, it is noted that the power device  10  may be calibrated for the amount of load by an electronic device  20  or amount of load when no electronic device  20  is connected. The amount of power being drawn, as discussed above, can be measured by the size and frequency of the pulses. The voltage can be measured across a capacitor within a circuit that connects to a transformer output winding of the electronic device  20 . In one form, when the power load is sufficiently small, the capacitor will drain faster than the recharging thereof, eventually resulting, in the transistor  540  being charged to open the relay plates  530   a ,  530   b.  In another form, the capacitor can be connected to a comparator (such as a simple IC) so that the comparator switches to a state that again charges the transistor  540 . 
         [0074]    In other related forms, intermittent monitoring for the presence of the electronic device  20  may be performed. In one form, for instance, the IC  210  and switch  340  may intermittently monitor the load via the load sensing device  400 . For instance, the IC  210  may shut down most of the power device, yet power up the load sensing  400  periodically (i.e., every couple minutes) for a fraction of a second to determine if the electronic device  20  is present (which would be recognized by the load characteristics across the ground G and output D). 
         [0075]    As described, various power devices are described having a variety of features that may be selected and/or combined within the scope of the present invention to provide a means for low-power consumption of phantom load, or intermittent power consumption, or no power consumption. As can be seen, some of these power devices are dependent in operation on the presence or absence of the electronic device, such as would be best suited for a portable, rechargeable device that is removed when charged, while others are independent of the presence or absence of the electronic device, such as would be useful for a computer which is commonly left plugged in and connected to a power device (i.e., power brick) when turned off. 
         [0076]    It should be noted that a variety of the features discussed herein may be combined with other features discussed herein. Towards this end,  FIG. 8 , for instance, shows a number of features which are not necessary for practicing the invention in all its forms. As described above,  FIG. 9  is directed towards a form of the power device utilizing a relay  530  driven to close the circuit, and  FIG. 12  shows a similar form of a circuit for such power device utilizing a relay  530 ′ driven by a relay coil  532 ′, the relay  530 ′ being located in the circuit at a position so that opening the relay  530 ′ disconnects all power consumption for the power device.  FIG. 10  shows a relatively simple circuit architecture in which a switch  50  connects at or proximate one of the prongs  14  for disconnecting the input power before the power-consuming components, resulting in a zero current draw. As noted in  FIG. 10 , the switch  50  may be integrated into the cable  42  so that the switch  50  is remote from the other circuitry, as has been discussed above.  FIG. 11  shows a circuit architecture for the power device wherein the Gain and Level Detection operates to monitor pulses from a transformer secondary winding SW to drive a Primary Switch in the with a voltage proportional to the load current. The form of  FIG. 11  utilizes a momentary connection at switch  50  to activate the power device, via a brief current resulting from the connection, and Controls operate the Primary Switch as an automatic shut-off feature when the power device is to be turned off, such as due to the electronic device being charged or disconnected. It should be noted that the Gain and Level Detection, the Control, and the Primary Switch may be included in an IC not shown or in the IC shown in the  FIG. 11 .  FIG. 13  shows the switch  50  preferably being a solid state switch, and the power device circuit architecture is designed so that upon momentary connection (including connection and subsequent release) a small current through the switch  50  is recognized to power on or activate the device from an “off” state, and current at resistor R sense  is recognized by Gain and Level Detection to control the Primary Switch, voltage below a threshold being used to determine and switch to an “off” state for the power device. 
         [0077]    While the invention has been described with respect to specific examples including presently preferred modes of carrying out the invention, those skilled in the art will appreciate that there are numerous variations and permutations of the above described systems and techniques that fall within the spirit and scope of the invention as set forth in the appended claims.