Abstract:
A system for automatic disconnect of an AC source from a converter that includes a converter and a converter. The converter includes a power supply capable of being connected to an alternating current (AC) power source and converting an AC voltage to a direct current (DC) voltage. The portable device contains a rechargeable battery where the portable device uses the DC voltage to charge the rechargeable battery. The connection of the converter to the AC power source is automatically disconnected responsive to the rechargeable battery reaching a full charge or the portable device being disconnected from the converter and automatically reconnected responsive to the rechargeable battery being below a full charge or the portable device being reconnected to the converter.

Description:
BACKGROUND OF THE INVENTION 
     The present invention is related to converters, and more specifically to automatic disconnect of an alternating current (AC) source from a converter. 
     Due to cost and demand, efforts are constantly being made to conserve on the use of energy. This applies even to electricity used when a charging device is still connected to an AC source but the device being charged has been disconnected or is fully charged. Although a device may be disconnected from the charging device or fully charged, due to electronics today, the charging device may still be drawing power and burning energy. A charging device, such as a wall wart, receives AC power and includes a DC charging power supply with a DC converter and an isolation device between the AC source and the DC charging power supply where the DC charging power supply rectifies and steps down the AC power source to produce a suitable DC charging source usable for charging a rechargeable battery on a device. For example, existing phone chargers used to charge cell phones may use a transformer or switching converter that remains powered by the AC supply even when the phone is fully charged and no longer drawing a direct current (DC) charging current. This causes an energy consumption that adds to increased energy costs. This cost is further increased if one or more other devices are drawing unnecessary power. In many cases, a person is unaware of this unnecessary energy use. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a system for automatic AC disconnect of a converter includes a converter, the converter including a power supply capable of being connected to an alternating current (AC) power source and converting an AC voltage to a direct current (DC) voltage, and a portable device, the portable device containing a rechargeable battery, the portable device using the DC voltage to charge the rechargeable battery, wherein the connection of the converter to the AC power source is automatically disconnected responsive to the rechargeable battery reaching a full charge or the portable device being disconnected from the converter. 
     According to another aspect of the present invention, a portable device includes a rechargeable battery, and a controller, the controller capable of monitoring a charge level of the rechargeable battery and sending a signal to a converter when the rechargeable battery reaches a full charge, wherein the signal is useable at the converter for automatically disconnecting the converter from an AC power source when the rechargeable battery reaches a full charge and automatically reconnecting the converter to the AC power source when the rechargeable battery is below a full charge or the portable device is reconnected to the converter. 
     According to still a further aspect of the present invention, a converter device includes a power supply, the power supply capable of being connected to an alternating current (AC) power source and converting an AC voltage to a direct current (DC) voltage, and disconnect circuitry, the disconnect circuitry capable of receiving a signal from a portable device and automatically disconnecting the converter device from the AC power source responsive to the received signal and automatically reconnecting the converter device to the AC power source responsive to the received signal. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention is further described in the detailed description which follows in reference to the noted plurality of drawings by way of non-limiting examples of embodiments of the present invention in which like reference numerals represent similar parts throughout the several views of the drawings and wherein: 
         FIG. 1  is a diagram of a system for automatic disconnect of an AC source from a converter according to an example embodiment of the present invention; 
         FIG. 2  is a diagram of a system for automatic disconnect of an AC source from a converter according to another example embodiment of the present invention; 
         FIG. 3  is a diagram of a system for automatic disconnect of AC from a converter according to still another example embodiment of the present invention; and 
         FIG. 4  is a diagram of a wall wart for automatic disconnect of an AC source from a converter according to an example embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     As will be appreciated by one of skill in the art, the present invention may be embodied as a method, system, computer program product, or a combination of the foregoing. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment (including firmware, resident software, micro-code, etc.) or an embodiment combining software and hardware aspects that may generally be referred to herein as a “system.” Furthermore, the present invention may take the form of a computer program product on a computer-usable storage medium having computer-usable program code embodied in the medium. 
     According to embodiments of the present invention, a charging device may be equipped with a sensor (e.g., current sensor) to detect when a device is no longer pulling charge current and when a battery has been fully charged by the charger. Once this condition is detected, the converter or charger may be automatically disconnected from the AC supply. To help illustrate embodiments of the present invention, a wall wart may be used as the converter or charger, and the device having a battery to be charged may be a cellular phone. However, embodiments of the present invention are not limited by the use of a wall wart and a cellular phone as any type charger and any type device needing to be charged may be included and implemented according to embodiments of the present invention. 
     According to embodiments of the present invention, a switching device in a wall wart may be connected in series with an AC supply and automatically controlled to disconnect the wall wart from the AC supply. The automatic disconnect may occur once a battery has reached a full charge or if the device with the battery being charged has been disconnected from the wall wart. The switching device in the wall wart may be automatically controlled by the device connected to the wall wart or controlled by the wall wart. The device connected to the wall wart may also be referred to as the device to be charged. 
       FIG. 1  shows a diagram of a system for automatic disconnect of an AC source from a converter according to an example embodiment of the present invention. The system  100  may include a device  101  that may be interconnected to a converter  102 . The device  101  and the converter  102  may be interconnected via a cable containing a polarized wire pair  108  that feeds into a charge controller  104  on the device  101 . The charge controller  104  may control charging of a rechargeable battery  103  on the device  101 . The polarized pair  108  provides a DC voltage that is used to charge the rechargeable battery  101 . The polarized pair  108  may be generated from an AC to DC converter  106  on the converter  102 . The AC to DC converter  106  may receive AC power for an AC source via a connector  107 . The converter  102  may also include disconnect circuitry  105  that may be controlled by the device  101  or by the converter  102  to automatically disconnect the AC to DC converter  106  from the connector  107  and thus the AC source when the rechargeable battery  103  has reached a full charge or when the device  101  has been disconnected from the converter  102 . The disconnect circuitry  105  may also be controlled by the device  101  or by the converter  102  to automatically reconnect the AC to DC converter  106  to the connector  107  and thus the AC source when the rechargeable battery  103  is below a full charge or when the device  101  has been reconnected to the converter  102 . In some embodiments where the device  101  controls the automatic disconnecting from the AC source, a signal  109  may be fed from the device  101  to the disconnect circuitry  105  on the converter  102 . The device  101  may be any type of device with a rechargeable battery or device that requires recharging. Further, the converter  102 , may be any type of device used to charge another device. 
       FIG. 2  shows a diagram of a system for automatic disconnect of an AC source from a converter according to another example embodiment of the present invention. The system  200  may include a wall wart  201  interconnected to a device  202  via a cable that includes a polarized wire pair  203 . The cable with the polarized wire pair  203  may include a connector  211  that mates with a second connecter  212  on the device  202 . A connect signal  204  may also be included in the connecter  211  and the connecter  212 . The connect signal  204  may be fed from the device  202  to the wall wart  201  to automatically disconnect the wall wart  201  from an AC power source. 
     The device  202  may include a charge controller  205  that feeds a voltage from the polarized pair  203  received from the wall wart  201  via the cable to a rechargeable battery  206 . The device  202  may also include a processor  207  that may receive a charge sense signal  209  from the charge controller  205  and provide a charge control signal  208  to the charge controller  205 . The charge controller  205  may also monitor a temperature of the rechargeable battery  206 . The processor  207  may also control and/or monitor other circuits on the device  202 . 
     The wall wart  201  may include a connect controller  224  that contains a low voltage DC bootstrap supply  225 , a second switching device  228 , and switch logic  226 . When connector  211  is attached to device  202  via connector  212 , a resister  213  in device  202  may provide a path for the low voltage DC bootstrap supply  225  to power switch logic  226 . The switch logic  226  in wall wart  201  may control a first switching device  227  to connect or disconnect the connector  220  to the AC power source coming into the wall wart  201  as directed by the connect signal  204  received from the device  202 . This eliminates any leakage current while device  202  is not being actively charged. When the switch logic  226  is powered on, the switch logic  226  may close a first switching device  227  to connect a DC charging power supply  221  in wall wart  201  to the connector  220  and the AC power source thereby starting up a DC charging power supply  221  and powering both the switch logic  226  as well as the device  202  from the DC charging power supply  221 . Once bootstrapped, the switch logic  226  may then open a second switch  228  and then derive its power from the DC charging power supply  221 . For safely considerations, the connect controller  224  may be electrically isolated from the DC charging power supply  221 . DC charging power supply  221  may include a transformer  222  connected between one wire of the connector  220  and the first switching device  227 . The other winding of the transformer  222  may be connected to a DC converter  223  that provides the polarized signals  203  to the device  202  via the cable to be used to charge the rechargeable battery  206 . 
     When a device  202  is initially connected to wall wart  201 , it may connect in a charging mode. However, once the device  202  has been detected that the rechargeable battery is fully charged, the device  202  may drive the connect signal  204  to a level causing the switch logic  226  to open the first switch  227  to disconnect the connector  220  from the AC power source. Moreover, if the connector  211  on the cable providing the polarized pair  203  is detached from the device  202 , this may cause the connect signal  204  line to float to a “high” level as it is no longer being pulled down by the resister  213  in device  202 . This may cause the switch logic  226  to control the first switch  227  to disconnect the connector  220  from the AC power source. A manual override switch  210  connected to the charge controller  205  of device  202  may force the device  202  to request charging, however, if the rechargeable battery  206  is fully charged or if there are other conditions preventing charging, then activation of the switch  210 . 
       FIG. 3  shows a diagram of a system for automatic disconnect of AC from a converter according to still another example embodiment of the present invention. The system  300  may include a device  302  and a charging device  301 . The device  302  may include a rechargeable battery (not shown). In this example embodiment, the device  302  may not provide a connect signal to the charging device  301  to automatically disconnect the charging device from an AC source. In this example embodiment, a positive supply lead of a polarized wire pair  314  may be used for signaling a charged state. For example, a processor  303  in the device  302  may control a switch  306  to pulse thereby connecting a resister  304  across the polarized wire pair  314 . This may induce current pulses in the positive supply lead of the polarized wire pair  314  that may be received by a coil  315  and a current sensed by the op-amp  321  at the charging device  301 . The current pulses detected by the coil  315  and the op-amp  321  may be cause the generation of a connect signal  320  by the op-amp  321  that may be fed to switch logic  318 . The switch logic  318  may decode and validate the current pulse series to distinguish valid “charge on” (i.e., connect to AC source) and “charge off” (i.e., disconnect from AC source) states from normal noise. Similar to other embodiments, the connect signal  320  may be used to cause switch logic  318  to open a switching device  319  in charging device  301  to disconnect a connector  310  from an AC power source. The switch logic  318  may be included in a controller  316  where the controller may also include a “super capacitor” circuit  317  that may store energy to power the switch logic  318  and the amplifier  321  during a bootstrap operation. As with previous embodiments, the charger device  301  may include a DC charging power supply  311  that includes a transformer  312  with one winding connected between the connector  310  and the switching device  319  and the other winding connected to a DC converter  313  that provides the polarized wire pair signals  314  to the device  302 . 
     In another example embodiment of the present invention, the device  302  may not include the switching device  306  or the resister  304  and may not generate pulses to the charging device  301  via the polarized signals  314 , but instead, the coil  315  may sense a current level remaining low or at zero suggesting that the device  302  has been disconnected from the charging device  301 . Similarly, when a rechargeable battery at device  302  is fully charged, a current drain may be sensed by the current sensor to be at a low or zero level. In these cases when a current level or a current drain remains low or at zero, as noted previously, switch logic  318  may control the switching device  319  to disconnect the connector  310  from the AC power source via opening the switching device  319 . When the device  302  is reconnected to charging device  301  or when battery charging of the rechargeable battery at device  302  resumes, the coil  315  and op-amp  321  may sense a current level rise above a specified minimum threshold. This may cause the amplifier  321  to generate a connect signal  320  that may then be fed into the switch logic  318  causing the switch logic  318  to close the switching device  319  and connect the charging device  301  to the AC power source. In this embodiment, the super capacitor circuit  317  in the controller  316  may store energy to power the switch logic  318  and operational amplifier  321  during a bootstrap operation. 
       FIG. 4  shows a diagram of a wall wart for automatic disconnect of an AC source from a converter according to an example embodiment of the present invention. The wall wart may include a DC charging power supply  402  that includes a transformer  403  and a DC converter  404 . The DC converter  404  provides polarized wire pair signals  412  via a connector  413  to a device requiring to be charged. The transformer  403  may have one winding connected between a first signal line of a connector  401 , which receives signals from an AC power source, and one end of a first switching device  409 . The other end of the first switching device  409  may be connected to a second signal line of the connector  401 . The switching device  409  may be controlled to disconnect the connector  401  from the AC power source. The other winding of the transformer  403  may be connected to the DC converter  404 . The wall wart  400  may also include a controller  405  that may include a low voltage DC bootstrap power supply  406  connected to a second switching device  408  that controlled by switch logic  407 . Further, the wall wart  400  may include an external push button switch  411  that when depressed may start a charging cycle by causing the switch logic  407  to close the first switching device  409  connecting the wall wart  400  to the AC power source. When charging is active, a light emitting diode (LED)  410  may illuminate. When a current drain on the output of the DC charging power supply  402  is zero or below a specified threshold, charging may terminate. The switch logic  407  may open the first switching device  409  to disconnect the connector  401  from the AC power source, and the LED  410  light may be extinguished. The switch logic  407  may remain reset until the push button switch  411  is pressed again. 
     The flowcharts and block diagrams in the Figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods and computer program products according to various embodiments of the present invention. In this regard, each block in the flowchart or block diagrams may represent a module, segment, or portion of code, which comprises one or more executable instructions for implementing the specified logical function(s). It should also be noted that, in some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures. For example, two blocks shown in succession may, in fact, be executed substantially concurrently, or the blocks may sometimes be executed in the reverse order, depending upon the functionality involved. It will also be noted that each block of the block diagrams and/or flowchart illustration, and combinations of blocks in the block diagrams and/or flowchart illustration, can be implemented by special purpose hardware-based systems which perform the specified functions or acts, or combinations of special purpose hardware and computer instructions. 
     The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. 
     Although specific embodiments have been illustrated and described herein, those of ordinary skill in the art appreciate that any arrangement which is calculated to achieve the same purpose may be substituted for the specific embodiments shown and that the invention has other applications in other environments. This application is intended to cover any adaptations or variations of the present invention. The following claims are in no way intended to limit the scope of the invention to the specific embodiments described herein.