Abstract:
Disclosed is a charging device comprising: a DC-to-DC converter for converting electrical power obtained from a battery source into a charging current for transmission to an electronic device; a voltage latch electrically connected to the DC-to-DC converter, the voltage latch for controlling the DC-to-DC converter so as to mitigate oscillation in the battery source; and an output current control electrically connected to the DC-to-DC converter, the output current control for regulating the charging current transmitted to the electronic device.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present Application is related to Provisional Patent Application entitled “COMPACT MOBILE ELECTRONIC DEVICE CHARGER,” filed 18 Jul. 2011 and assigned filing Ser. No. 61/509,104, incorporated herein by reference in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The present invention relates to a system and method for providing a compact and mobile source of electrical power for recharging a mobile electronic device. 
       BACKGROUND OF THE INVENTION 
       [0003]    Personal mobile electronic devices are in widespread use by consumers. Most such devices operate on an internal rechargeable power source, rather than a disposable battery, and thus require periodic access to an AC charging device. Such AC charging devices typically comprise a transformer that is plugged into an AC power outlet, and a DC output cord with a plug that is connected to the charging port of the device. 
         [0004]    However, there are times when the mobile device may be low on electrical power, or has been completely discharged, and the conventional AC charging device has been misplaced or is not otherwise available. In some situations, the user of the mobile electronic device may be in a foreign country, and does not have an AC charging device configured for operation from a local electrical power socket. 
         [0005]    What is needed is an apparatus and method for recharging a mobile electronic device when the device AC charger is not available or is incompatible with a locally-available electrical power outlet. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    In one aspect of the present invention, a charging device comprises: a DC-to-DC converter for converting electrical power obtained from a battery source into a charging current for transmission to an electronic device; a voltage latch electrically connected to the DC-to-DC converter, the voltage latch for controlling the DC-to-DC converter so as to mitigate oscillation in the battery source; and an output current control electrically connected to the DC-to-DC converter, the output current control for regulating the charging current transmitted to the electronic device. 
         [0007]    In another aspect of the present invention, a charging device comprises: a DC-to-DC converter for converting electrical power obtained from a battery source into a charging current for transmission to an electronic device, the DC-to-DC converter including a first microcircuit functioning as a step-down DC-to-DC regulator; a voltage latch electrically connected to the DC-to-DC converter, the voltage latch including a second microcircuit configured as a comparator; and an output current control electrically connected to the DC-to-DC converter, the output current control including a third microcircuit functioning as a current sense monitor. 
         [0008]    In still another aspect of the present invention, a method for recharging a rechargeable electronic device comprises: obtaining a DC-to-DC converter, a voltage latch electrically attached to the DC-to-DC converter, and an output current control connected to an output of the DC-to-DC converter; electrically connecting a battery source to an input of the DC-to-DC converter; and electrically connecting the output current control to the rechargeable electronic device. 
         [0009]    The additional features and advantage of the disclosed invention is set forth in the detailed description which follows, and will be apparent to those skilled in the art from the description or recognized by practicing the invention as described, together with the claims and appended drawings. 
     
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
         [0010]    The foregoing aspects, uses, and advantages of the present invention will be more fully appreciated as the same becomes better understood from the following detailed description of the present invention when viewed in conjunction with the accompanying figures, in which: 
           [0011]      FIG. 1  is a functional block diagram of a charging device for a mobile electronic device, the charging device including a DC-to-DC converter module, a voltage latch module, an output current control module, and an optional delay timer, the charging device electrically connected between a battery and the mobile electronic device, in accordance with an aspect of the present invention; 
           [0012]      FIG. 2  is an alternate embodiment of the charging device of  FIG. 1 , including an ESD protection component, a reverse voltage protection component, and a battery indicator light; 
           [0013]      FIG. 3  is an alternate embodiment of the charging device of  FIG. 2 , including input battery terminals and an output connector for electrically connecting to the mobile electronic device; 
           [0014]      FIG. 4  is a flow chart illustrating a method of charging a mobile electronic device, in accordance with an aspect of the present invention; 
           [0015]      FIG. 5  is a detail view of the DC-to-DC convertor module of  FIG. 1 ; 
           [0016]      FIG. 6  is a detail view of the voltage latch module and the delay timer module of  FIG. 1 ; 
           [0017]      FIG. 7  is a detail view of a battery indicator light, as used in the charging device of  FIG. 2 ; 
           [0018]      FIG. 8  is a detail view of the ESD protection component of  FIG. 2 ; 
           [0019]      FIG. 9  is a detail view of the reverse voltage protection component of  FIG. 2 ; 
           [0020]      FIG. 10  is a detail view of the output current control module of  FIG. 1 ; 
           [0021]      FIG. 11  is a diagrammatical isometric view of a charge key containing one of the charging devices of  FIGS. 1-3 , in accordance with an aspect of the present invention; and 
           [0022]      FIG. 12  is an isometric rendering of an embodiment of a charge key with an end cap, containing one of the charging devices of  FIGS. 1-3  and configured in a stylized key-shape; 
           [0023]      FIG. 13  is a view of the charge key of  FIG. 11 , with the end cap of  FIG. 12  installed, and showing the battery indicator light of  FIG. 7 ; and 
           [0024]      FIG. 14  is an isometric rendering of an alternate embodiment of a charge key with an end cap, containing one of the charging devices of  FIGS. 1-3  and configured as a geometric solid. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    The following detailed description is of the best currently contemplated modes of carrying out the invention. The description is not to be taken in a limiting sense, but is made merely for the purpose of illustrating the general principles of the invention. 
         [0026]    The disclosed compact charging device includes a DC-to-DC convertor that can be adapted for a variety of input voltages, as provided by a suitable battery source, and output voltages, as required by a particular mobile electronic device. The disclosed compact charging device can easily be carried on a user&#39;s person, or attached to a keychain, and can make use of readily available battery power sources to recharge the mobile electronic device. 
         [0027]    There is shown in  FIG. 1  a compact charging device  10 , in accordance with the present invention. The charging device  10  comprises a DC-to-DC converter  12 , a voltage latch  16 , an optional delay timer  18 , and an output current control  14 . A battery source  20  may provide an input voltage VB to the DC-to-DC converter  12  in the charging device  10  via a pair of input leads  22 . The voltage latch  16  may be connected to the DC-to-DC converter  12  so as to mitigate or prevent oscillation in the battery source  20  during operation of the compact charging device  10 . The delay timer  18  may be electrically connected to the voltage latch  16  to control the response of the voltage latch  16  to the initial connection of the input voltage VB to the DC-to-DC converter  12 , as explained in greater detail below. 
         [0028]    The DC-to-DC converter  12  in the charging device  10  may output a charging voltage of VL to a mobile electronic device  30  via a pair of output leads  32 . It should be understood that, while the disclosed charging device  10  may be particularly suitable for use with the mobile electronic device  30 , the present invention is not limited to use with mobile electronic devices, and can be configured to operate with essentially any electronic device powered with an internal rechargeable power source. The output current control  14  functions to regulate the amount of charging current transmitted to a rechargeable battery (not shown) in the mobile electronic device  30 . In an exemplary embodiment, the charging device  10  may be configured to provide a charging voltage, within a pre-specified range of voltages, to a SMARTPHONE, an ANDROID, an IPHONE, a BLACKBERRY, an ITOUCH, various types of Wi-Fi mobile devices, and various types of TABLETS, such as an IPAD. 
         [0029]    In an exemplary embodiment, the output voltage VL may be about five volts for most mobile electronic devices, and may be a voltage level other than five volts for products manufactured by Apple Corporation, for example. As can be appreciated by one skilled in the art, the optimal current level provided by the charging device  10  may vary from one device to another. Accordingly, the output current control  14  may be configured so as to provide an optimal charge current for a specific mobile electronic device. It can be appreciated by one skilled in the relevant art that the specific components and component values used in the charging device  10  are a function of the input voltage VB and the output voltage VL. 
         [0030]    In an exemplary embodiment, shown in  FIG. 2 , a charging device  40  comprises the DC-to-DC converter  12 , the voltage latch  16 , the output current control  14 , and may include the delay timer  18 . In addition, the charging device  40  may further comprise one or more of an ESD protection component  42 , a reverse voltage protection component  44 , and a battery indicator circuit  46  including a battery indicator light  48 . The ESD protection component  42  may be directly connected to the input leads  22  so as to protect the DC-to-DC converter  12  from ambient static charges. The reverse voltage protection component  44  may be electrically connected between the input voltage VB and the DC-to-DC converter  12  so as to protect the DC-to-DC converter  12  in the event that a user incorrectly reverses connection of the battery source  20  to the charging device  40 . 
         [0031]    The battery indicator circuit  46  may be electrically connected between the DC-to-DC converter  12  and the output current control  14  to provide an indication, via the indicator light  48 , as to the status of the charging operation. In an exemplary embodiment, the indicator light  48  illuminates while the battery source  20  is charging the mobile electronic device  30 . When the indicator light  48  ceases illumination, this condition may serve to inform the user that the installed battery source  20  has been depleted. Accordingly, the depleted battery source  20  can be removed and replaced with another battery source  20 , if the rechargeable battery in the mobile electronic device  30  has not been fully recharged. The replacement battery source  20  can be electrically connected to the charging device  40  so as to continue or complete the recharging process. 
         [0032]    In an exemplary embodiment, shown in  FIG. 3 , a charging device  50  may comprise the DC-to-DC converter  12 , the voltage latch  16 , the optional delay timer  18 , the output current control  14 , the optional ESD protection component  42 , the optional reverse voltage protection component  44 , the optional battery indicator  46 , a set of battery terminals such as miniature snap terminals  52   a,    52   b,  and an electronic device connector  54 . A bleeder resistor  24  may be provided across the miniature snap terminals  52   a,    52   b  to be used in conjunction with the delay timer  18 , as described in greater detail below. 
         [0033]    The miniature snap terminals  52   a,    52   b  may be used, for example, when the battery source  20  comprises a nine-volt battery in accordance with ANSI-1604A or IEC-6LR61 standards. A nine-volt battery based on a zinc-magnesium dioxide chemical system can provide a charge of from about 300 mAh (at a discharge rate of 500 to 1000 mA). A plurality of “AA” batteries may also be used, in place of the nine-volt battery, where each AA battery can provide a charge output of about 1.5 volts at about 2500 mAh. It should be understood that, if AA batteries are used, battery terminals (not shown) other than the snap terminals  52   a,    52   b  could be used on the device housing, or an adapter (not shown) could be electrically connected between the snap terminals  52   a,    52   b  and a battery holder containing the AA batteries. It can be appreciated by one skilled in the art that a typical mobile electronic device  30  may require a charging current of about 500 mA at a charge level of about five-volts. 
         [0034]    In an exemplary embodiment, the electronic device connector  54  may comprise a micro-USB connector adapted to mate with the micro-USB receptacle in a SMARTPHONE, for example. In an alternative embodiment, the electronic device connector  54  may comprise a 30-pin, I/O plug with latches, when the charging device  50  is configured for use with one or more products manufactured by the Apple Corporation. 
         [0035]    Use of the charging devices  10 ,  40 ,  50  with the mobile electronic device  30  may be described with reference to a flow diagram  60 , in  FIG. 4 . The user may obtain and electrically interconnect the DC-to-DC converter  12 , the voltage latch  16 , the delay timer  18 , and the output current control  14 , in accordance with  FIGS. 1-3 , at step  62 . One or more of the DC-to-DC converter  12 , the voltage latch  16 , the delay timer  18 , and the output current control  14  may be mounted on a substrate or circuit board (not shown) to form a basic voltage conversion circuit, as is well-known in the relevant art. 
         [0036]    The optional ESD protection component  42  may also be mounted on the substrate if desired, at step  64 . The optional reverse voltage protection component  44  may also be included in the charging device circuit, at step  66 . The optional battery indicator circuit  46  may be integrated into the circuit on the substrate, at step  68 . The set of miniature snap terminals  52   a,    52   b  may be electrically attached to the substrate at the input side of the charging circuit, at step  70 . 
         [0037]    The battery source  20  may be attached directly to the charging circuit, or to the set of miniature snap terminals  52   a,    52   b,  at step  72 , so as to provide electrical power to the DC-to-DC converter  12 . The appropriate electronic device connector  54  may be selected for compatibility with the mobile electronic device  30 , and electrically attached to the output leads  32 , at step  74 . A housing  92  (see  FIGS. 11-14 ) may be provided to enclose and secure the substrate and electronic components, at step  76 , while leaving the electronic device connector  54  sufficiently exposed to allow insertion into a charging port of the mobile electronic device  30 . The housing  92  may include a cap (see  FIGS. 12-14 ) to fit over the electronic device connector  54  for protection against dirt and moisture. The power output of the DC-to-DC converter  12  may thus be provided to the mobile electronic device  30  via the output current control  14  and the electronic device connector  54 , at step  78 . 
         [0038]    As can be appreciated by one skilled in the art, the charging devices  10 ,  40 ,  50  are thus (i) small and compact for placement on a user&#39;s keychain, for example, when enclosed in an appropriate housing, such as shown in  FIGS. 11-14  below, (ii) configured to be used with battery sources readily-available world-wide, and (iii) of relatively low cost as the charging devices  10 ,  40 ,  50  do not require battery storage compartments, as it is not necessary that the battery source  20  be retained in any of the charging devices  10 ,  40 ,  50  between charging sessions. In an exemplary embodiment, the battery source  20  comprises a nine-volt battery configured in a rounded rectangular package with male and female snap connectors at one end configured for mating with the set of miniature snap terminals  52   a,    52   b.  Alternatively, the battery voltage VB supplied to the compact charging device  10 ,  40 ,  50  may be greater or less than nine volts, and accordingly, may utilize one or more commercially-available battery products for providing charging power, other than a nine-volt battery. 
         [0039]    In an exemplary embodiment, the DC-to-DC converter  12 , shown in  FIG. 5 , may comprise a voltage converter microcircuit (U 1 ), or equivalent electronic components, the microcircuit U 1  commercially available as a step-down DC-to-DC regulator MCP16301 manufactured by Microchip Technology Inc. of Chandler, AZ. Power from the battery source  20  may be provided to an input voltage pin of the voltage converter microcircuit U 1  via an input line  82 . An enable logic-level signal may be provided to an EN pin via an enable line  84  to enable or disable the voltage converter microcircuit U 1 . Output voltage is provided via a power line  86  from a SW pin on the voltage converter microcircuit U 1 , where a switch node may also include an inductor (L 1 ) and a Schottky diode (D 1 ). 
         [0040]    In an exemplary embodiment, the voltage latch  16 , shown in  FIG. 6 , may comprise (i) a microcircuit (U 2 ), or equivalent electronic components, the microcircuit U 2  commercially available as a comparator with integrated reference voltage MCP65R46T-2402E/CHY, and (ii) a microcircuit (U 3 ), or equivalent electronic components, the microcircuit U 3  commercially available as a voltage regulator MCP1702, both microcircuits manufactured by Microchip Technology Inc. of Chandler, Ariz. The output of the microcircuit U 2  may provide the enable signal transmitted to the DC-to-DC converter  12  via the enable line  84 . The microcircuit U 3  may receive an input voltage signal from the battery source  20  via an input voltage line  88 . 
         [0041]    The microcircuit U 3 , here shown as a five-volt regulator, functions to convert a voltage (VIN) at the input voltage VB level (e.g., nine volts) into a voltage (VOUT) at the output voltage VL level (e.g., five volts). The delay timer  18  functions to impose a time delay before the output voltage (VOUT) of the microcircuit U 3  is provided to the microcircuit U 2  in the voltage latch  16 . In an exemplary embodiment, a delay timer microcircuit (U 5 ), or equivalent electronic components, may be used in the delay timer  18  to enable a time interval delay of about 0.5 seconds. The microcircuit U 5  may comprise a 74LVC2G14 dual-inverting Schmidt trigger with five-volt tolerant inputs, such as may be available from NXP Semiconductors of San Jose, Calif. As described above, the Schmidt trigger component may function to selectively disable the EN (enable) pin on the DC-to-DC converter  12  for the pre-determined period of time set by the delay timer  18  time delay. 
         [0042]    Under some operating conditions, when a battery is inserted into battery terminals, such as the miniature snap terminals  52   a,    52   b,  the physical action may generate electrical noise that causes voltage converter microcircuit U 1  in the DC-to-DC converter  12  to latch “OFF.” The purpose of the delay timer  18  is to protect the DC-to-DC converter  12  against such electrical noise by providing an initial time interval during which the enable port (EN) on the voltage converter microcircuit U 1  is disabled, and consequently, will not respond to electrical noise as an input signal. The delay timer  18  may be reset after the bleeder resistor  24  has caused a discharge of capacitors C 1  and C 7  in the DC-to-DC converter  12 . 
         [0043]    In an exemplary embodiment, the battery indicator  46 , shown in  FIG. 7 , may comprise a resistor (R 6 ) on the power line  86 , in series with a light-emitting diode (D 3 ) functioning as the battery indicator light  48 . As shown in  FIG. 8 , the ESD protection component  42  may comprise a bi-directional power Zener diode voltage suppressor, or equivalent component, on the input line  82 , the diode commercially available as 1SMA1OCAT3G manufactured by ON Semiconductor of Phoenix, Ariz. 
         [0044]    The reverse voltage protection component  44  may comprise a p-channel FET on the input line  82 , as shown in  FIG. 9 , the FET commercially available as FDN308P manufactured by Fairchild Semiconductor of San Jose, Calif., or an equivalent electronic component. In an exemplary embodiment, the output current control module  14 , shown in  FIG. 10 , may comprise a microcircuit (U 4 ) or equivalent electronic components, on the power line  86 , with shunt resistors, and with capacitance to ground at the microcircuit output, the microcircuit U 4  commercially available as a current sense monitor ZXCT1009FTA, manufactured by Diodes Incorporated of Dallas, Tex. 
         [0045]    In an exemplary embodiment, any of the compact charging devices  10 ,  40 ,  50  may be fabricated on a suitable substrate or circuit board (not shown) and enclosed in the housing  92 , shown in  FIG. 11 . The housing  92  may be fabricated from a rugged, moisture-resistant material such as a high-impact plastic, to form a compact “charge key” device  90 . The set of miniature snap terminals  52   a,    52   b  are exposed in the housing  92  so as to enable attachment of the nine-volt battery. 
         [0046]    It can be appreciated that the configuration of the housing  92  physically retains the battery source outside the housing  92 . That is, the housing  92  does not include a battery compartment. Accordingly, because ambient air can provide cooling to the battery source, the heat buildup in the battery source is at a lesser rate than if the battery source were enclosed in a battery compartment. This feature allows the user to remove the battery source from the set of miniature snap terminals  52   a,    52   b  when the battery indicator light  48  goes out, allow the battery source to cool, and then re-install the battery source to more completely drain off any charge that may be remaining in the battery source. 
         [0047]    The electronic device connector  54 , here configured as a micro-USB connector, extends from one end of the charge key device  90 , and is thus accessible to allow for insertion into a charge port of the mobile electronic device  30 . An optional cap (shown in  FIG. 12 ) may be provided to fit over the electronic device connector  54 . In an alternative embodiment (not shown), the housing  92  may be configured so as to allow the electronic device connector  54  to be retracted into the housing  92 . 
         [0048]    An opening  94  may be provided in the charge key device  90  to allow for attachment to a key ring, for convenient access by a user. In an alternative embodiment, shown in  FIG. 12 , a charge key device  100  may include a cap  102  for covering and protecting the electronic device connector  54  (not shown). The charge key device  100  may comprise any of the charging devices  10 ,  40 ,  50  disclosed above. It can be appreciated that the cap  102  may also be used on the charge key device  90 , as shown in  FIG. 13 . The battery indicator light  48  may be located in a convenient position on the respective housing of either the charge key device  90 , as shown, or the charge key device  100 , such that the charging device user can monitor the charging process. 
         [0049]    It should be understood that the present invention is not limited to a housing  92 , shown in  FIG. 11 , having the size and shape of a key. For example, a charge key device  104  may have the general shape of a geometric solid, such as the parallelepiped configuration shown in  FIG. 14 . Other shapes and sizes can be used for configuring a housing for enclosing any of the charging devices  10 ,  40 ,  50 . A geometrically-compatible cap  106  may be provided with the charge key device  104  to cover the electronic device connector  54  (not shown). The charge key device  104  may comprise any of the charging devices  10 ,  40 ,  50  described above, and may also include the battery indicator light  48  on the device housing. 
         [0050]    It can be appreciated that the electronic components used in any of the charging devices  10 ,  40 ,  50  can be mounted to a substrate of essentially any shape and configuration, limited only by circuitry requirements. Preferably, the charging device battery connectors and electronic device connector are positioned on the substrate or circuit board so as to allow a user external access to the battery connectors, so as to retain the battery outside the device housing, and so as to allow the charging device user to access the electronic device connector for insertion into an electronic device. 
         [0051]    It can be appreciated that the electronic component substrate used for any of the charging devices  10 ,  40 ,  50  may be enclosed in a housing of essentially any size and shape, as may be envisioned by a product designer. For example, the sizes and shapes available for housing miniature external hard drives, commonly referred to as “thumb” drives or “travel” drives, can be adapted for use with any of the charging devices  10 ,  40 ,  50 . A miniature external hard drive similarly includes a protruding or retractable electronic device connector, such as a USB connector, and is similar in size to any of the charging devices  10 ,  40 ,  50 . Accordingly, the array of housing designs adapted for use with miniature external hard drives may be appropriated for use with any of the charging devices  10 ,  40 ,  50 . 
         [0052]    It is to be understood that the description herein is exemplary of the invention only and is intended to provide an overview for the understanding of the nature and character of the disclosed illumination systems. The accompanying drawings are included to provide a further understanding of various features and embodiments of the method and devices of the invention which, together with their description serve to explain the principles and operation of the invention.