Abstract:
A power adaptor for converting AC/DC current to DC current and providing the converted DC current to a portable device. The power adaptor includes a converter and switching means. The converter includes input ports for receiving the input current therethrough and output ports for flowing the output current therethrough. The switching means are coupled to the input ports and operative to control the flow of the input current. The switching means are adapted to be connected to and operated by the portable device such that the input current flows only when the portable device is coupled to the power adaptor.

Description:
FIELD OF THE DISCLOSURE 
       [0001]    The present disclosure relates to a power adaptor of a device, and more particularly to a power adaptor having a power-saving circuit. 
       BACKGROUND 
       [0002]    Portable devices, such as cellular phones, MP3 players, personal digital assistants (PDA), camcorders, digital cameras, laptops, and cordless and mobile phones, have become the essential electric appliances in the modern life. According to the web site http://www.energystar.gov/ia/partners/prod_development/downloads/power_supplies/PSMA.pdf (see Appendix), as many as 1.5 billion portable devices are in use in the U.S. The total energy flowing through all types of power supplies into those portable devices is about 207 billion kWh/year, which amounts to 6% of the national electric bill. Typically, a portable device has an AC/DC (alternating-current/direct-current) adaptor that receives commercial alternating AC current from a wall outlet into a low voltage DC current used to power the device. 
         [0003]    A conventional portable device has an internal rechargeable battery so that its user can run the device for several hours without connecting the device to a power outlet. The battery is charged when the portable device is electrically connected to a wall outlet via the AC/DC adaptor. Typically, when the battery is charged up, the user disconnects the device from the AC/DC adaptor, leaving the AC/DC adaptor connected to the wall outlet in an unused mode. In the unused mode, the AC/DC adaptor still uses a certain level of power, resulting in a waste of electrical energy. Considering the number of portable devices in use, the wasted electrical energy may add up to a considerable amount. As such, there is a need for an adaptor having a mechanism to reduce the waste of energy. 
       SUMMARY OF THE DISCLOSURE 
       [0004]    According to one embodiment, a power adaptor for converting an input current into an output current and providing the output current to a portable device includes a converter and switching means. The converter includes input ports for receiving the input current therethrough and output ports for flowing the output current therethrough. The switching means are coupled to the input ports and operative to control the flow of the input current. The switching means are adapted to be connected to and operated by the portable device such that the input current flows only when the portable device is coupled to the power adaptor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0005]      FIG. 1  shows a schematic diagram of a system for providing electrical power to a portable device in accordance with one embodiment of the present invention. 
           [0006]      FIG. 2A  shows a schematic cross-sectional view of the power adaptor shown in  FIG. 1 . 
           [0007]      FIG. 2B  shows schematic cross-sectional views of the adaptor plug and the portable device shown in  FIG. 1 . 
           [0008]      FIG. 3A  shows a schematic cross-sectional view of a power adaptor in accordance with another embodiment of the present invention. 
           [0009]      FIG. 3B  shows schematic cross-sectional views of an adaptor plug and a portable device of a type to be used with the power adaptor of  FIG. 3A . 
           [0010]      FIG. 4  shows a schematic cross-sectional view of a power adaptor of a type that might be used with the portable device of  FIG. 3B  in accordance with yet another embodiment of the present teachings. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0011]    Although the following detained description contains many specifics for the purposes of illustration, those of ordinary skill in the art will appreciate that many variations and alterations to the following detains are within the scope of the invention. Accordingly, the following embodiments of the invention are set forth without any loss of generality to, and without imposing limitation upon, the claimed invention. 
         [0012]      FIG. 1  is a schematic diagram of a system  10  for providing electrical power to a portable device  26  in accordance with one embodiment of the present invention. As depicted, the portable device  26  is connected to the power source outlet  12  via a power adaptor unit  14 . For simplicity, in the present document, the power source outlet  12  is shown as a wall socket that provides commercial AC current, i.e., the power adaptor unit  14  is an AC/DC adaptor. However, it should be apparent to those of ordinary skill that the power source outlet  12  is a DC power source outlet and the power adaptor unit  14  is a DC/DC adaptor. 
         [0013]    The power adaptor unit  14  includes a power adaptor  18 , pins/blades  16 , an electrical cable  20 , and an adaptor plug  22  disposed at the distal end of the cable  20  and configured to engage the jack  24  of the device  26 . It is noted that the power adaptor unit  14  may have other configurations. For example, the power adaptor unit  14  may have an additional plug (not shown in  FIG. 1  for brevity) disposed at the proximal end of the power adaptor via another electrical line, and pins are prominently secured to the plug. In another example, the power adaptor unit  14  may include three pins/blades, where one of the pins is connected to a ground during operation. 
         [0014]    The power adaptor  18  converts AC current received from the power source outlet  12  via the pins  16  into DC current.  FIG. 2A  shows a schematic cross-sectional view of the power adaptor  18  shown in  FIG. 1 .  FIG. 2B  shows schematic cross-sectional views of the adaptor plug  22  and the portable device  26  shown in  FIG. 1 . As depicted, one pin  16   a  is electrically coupled to an input port  31   a  of a converter  30  of the power adaptor  18  via an input line  32   a.  The other pin  16   b  is electrically connected to the other input port  31   b  of the converter  30  via another input line  32   b,  where the input line  32   b  is open. More specifically, the input line  32   b  includes an indentation and electrical lines  34   a  and  34   b  are respectively connected to the ends of the indentation and extend to the distal end of the adaptor plug  22 . It is noted that the converter  30  collectively refers to a circuit that converts AC (or DC) current to DC current. For example, the converter  30  may include a transformer and several diodes to rectify the input AC current. In another example, the converter  30  may further include a capacitor for smoothing the pulsating current from the rectifier. 
         [0015]    Two output lines  36   a,    36   b  respectively extend from output ports  33   a,    33   b  of the converter  30  to the adaptor plug  22 . The cable  20  includes the four lines  34   a,    34   b,    36   a,  and  36   b  disposed therein. The adaptor plug  22  is disposed at the distal end of the cable  20  and has a salient portion  41  that engages the jack  24  of the portable device  26 . 
         [0016]    The device  26  includes a rechargeable battery  40  and a connector  42 , where the connector  42  is formed of a conducting material, such as metal. The battery  40  may include one or more commercially available batter cells, such as Li-Ion, NiCd, and NiMH battery cells. When the user inserts the salient portion  41  into the jack  24 , the two ends of the connector  42  are respectively connected to the electrical wires  34   a,    34   b  to thereby close the input line  32   b.  Also, the electrodes of the battery  40  are respectively connected to the two output lines  36   a,    36   b.    
         [0017]    In the charging mode, the user respectively inserts the pins  16  and the adaptor plug  22  into the power source outlet  12  and the jack  24 . Then, the battery  40  is charged by the DC current transmitted from the converter  30  through the output lines  36   a,    36   b.  In the unused mode, the pins  16  may remain inserted into the power source outlet  12  while the portable device  26  is disconnected from the power adaptor  14 . In this mode, the line  34   a  is disconnected from the line  34   b,  i.e., the input line  32   b  is open, such that the input port  31   b  of the converter  30  is disconnected from the power source outlet  12 . Thus, the power adaptor  18  does not consume any electrical power in the unused mode even if the user leaves the pins in the power source outlet  12 . Stated differently, the electrical lines  34   a,    34   b  form a switch to open/close the input line  32   b  and the connector  42  functions as the switch operator. 
         [0018]      FIG. 3A  shows a schematic cross-sectional view of a power adaptor  50  in accordance with another embodiment of the present invention.  FIG. 3B  shows schematic cross-sectional views of an adaptor plug  63  and a portable device  64  that might be used with the power adaptor  50  of  FIG. 3A . As depicted, the power adaptor  50  is similar to the power adaptor  18  in  FIG. 1 , with the differences that a switch  54  is disposed in the power adaptor  50  and opens or closes one of the input line  56   b.  The switch  54  is preferably, but not limited to, a relay switch. When the user inserts the adaptor plug  63  into a jack  66  of the portable device  64 , the electrical terminals of a battery  68  of the portable device  64  are connected to the two output lines  60   a,    60   b  of the converter  52 . Also, the electrical terminals of the battery  68  are connected to the two electrical lines  58   a,    58   b  so that the electrical power remaining in the battery  68  activates the switch  54  and thence the input line  56   b  is closed. As such, the battery  68  functions as an operator of the switch  54 . 
         [0019]    During the charging mode, the user inserts the pins into a power source outlet. Then, a converter  52  in the power adaptor  50  receives AC current through input lines  56   a,    56   b  and transmits DC current to the battery  68  via the output lines  60   a,    60   b.  In the charging mode, a portion of the output DC current from the converter  52  is used to maintain the switch  54  in the closed state. In the unused mode, the portable device  64  is disconnected from the adaptor plug  63 , causing the switch  54  to open the input line  56   b.  Thus, in the unused mode, the power adaptor  50  does not consume any electrical power even if the user leaves the pins in the power source outlet. 
         [0020]    Optionally, a light-emitting-diode (LED)  59  may be included in the power adaptor  50 . The LED  59  is lit only when the switch  54  is activated by the electrical power of the battery  68 , to thereby notify the user of the charging status. 
         [0021]      FIG. 4  shows a schematic cross-sectional view of a power adaptor  80  of a type that might be used with the portable device  64  of  FIG. 3B  in accordance with yet another embodiment of the present teachings. The power adaptor  80  is similar to the power adaptor  50  of  FIG. 3A , with the difference that the power adaptor  80  includes a manual switch  82  arranged in parallel with a relay switch  84 . For simplicity, the adaptor plug of the power adaptor  80 , which has the same structure as the adaptor plug  63  of  FIG. 3B , is not shown in  FIG. 4 . 
         [0022]    In the case where the battery  68  has sufficient electric power to activate the relay switch  84  via the two electrical lines  90   a,    90   b,  the switch  84  is closed when the user inserts the adaptor plug into the jack  66  of the portable device  64 . In this case, the power adaptor  80  operates in the same manner as the power adaptor  50 . However, if the remaining power in the battery  68  is not sufficient to activate the switch  84 , a user may press the manual switch  82  to close one of the input lines  83  in the charging mode. The user may press the manual switch  82  for a short time interval until the relay switch  84  is activated by the output DC current from the converter  86 . Once the relay switch  84  is activated to close the input line  83 , the battery  68  is charged via the output lines  88   a,    88   b  even when the user releases the manual switch  82 . 
         [0023]    In the unused mode, the user disconnects the portable device  64  from the power adaptor  80 , causing the relay switch  84  to be open. In this mode, even if the pins remain inserted into the power source outlet, the power adaptor  80  does not consume any electrical power insofar as the user does not press the manual switch  82 . 
         [0024]    Optionally, an LED  92  may be included in the power adaptor  80 . The LED  92  is lit only when the relay switch  84  is activated by the electrical power of the battery  68 , to thereby notify the user of the charging status. 
         [0025]    It is noted that the devices  26  and  64  in  FIGS. 1-4  include conventional portable devices, such as cellular phones, MP3 players, personal digital assistants (PDA), camcorders, digital cameras, laptops, and cordless and mobile phones, etc. However, it should be apparent to those of ordinary skill in the art that the devices are not necessarily limited to portable devices and that the devices include any suitable electric appliances powered via power adaptors. 
         [0026]    While the present invention has been described with reference to the specific embodiments thereof, it should be understood that the foregoing relates to preferred embodiments of the invention and that modifications may be made without departing from the spirit and scope of the invention as set forth in the following claims.