Abstract:
A super-capacitor-powered device is quickly recharged from an energy buffer incorporated in a USB cradle or USB dongle. That USB energy buffer itself is slowly refilled while it is connected to a USB port. The super-capacitor can be in parallel to a battery. In one embodiment, a facilitated battery changer is provided. A battery swap is performed with a recharged battery in a charger having two battery slots.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to rechargeable devices, and in particular to devices using super-capacitors or facilitated replaceable batteries. 
     Typically, rechargeable batteries can be removed from a device, such as a computer mouse, and placed in a charger. Alternately, the device itself, such as the mouse, could be placed on a recharging stand for recharging. This can be inconvenient since the mouse is not usable during the time the battery is removed or it is on the recharging stand. 
     A number of patents show systems for replacing the battery without losing power to the device. These typically include sliding one battery into the slot while pushing the other battery out the other side. See, e.g., U.S. Pat. No. 7,339,349, U.S. Pat. No. 6,936,376, U.S. Pat. No. 6,722,024 and U.S. Pat. No. 5,369,802. A device for automatic replacement of a battery in a hard-to-reach ceiling smoke alarm is shown in U.S. Pat. No. 5,617,079. 
     Another approach for wireless devices is to use induction power supply. An example of a wireless mouse with an induction power supply is shown in U.S. Pat. No. 6,633,155. 
     Other devices use super-capacitors, which can be charged up rapidly and hold enough charge to power the device for a short period of time. These devices either use a super-capacitor which is shaped like a battery and used like a battery, or a super-capacitor which is wired into the circuitry of a device. In some examples, the super-capacitor is in parallel with the batteries to provide power when the battery runs out. 
     Examples include U.S. Pat. No. 6,433,508, published application number 2003-0026092 (light with a super-capacitor), publication number 2007-0015531 (hand-held device with video for interactive movie theater, discussing short charge time in paragraph 0072), U.S. Pat. No. 7,323,849 (quick charging super-capacitor for flashlight), U.S. Pat. No. 6,700,352 (super-capacitors shaped like batteries), and U.S. Pat. No. 6,628,107 (super-capacitor in parallel with battery). 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention in one aspect provides a super-capacitor-powered device, such as a mouse. A charging circuit is provided in a USB buffer, so the super-capacitor in the device can be rapidly recharged when the device is connected to the USB buffer. 
     In one embodiment, the USB buffer is provided in a USB dongle. The buffer or charging circuit includes a super-capacitor as well, which preferably has more (e.g., twice) the capacity of the one in the device to be charged to ensure sufficient energy transfer. The USB dongle, when plugged into the computer port, charges up its super-capacitor. When the USB dongle is subsequently plugged into the portable wireless device, its super-capacitor downloads its power quickly into the super-capacitor of the wireless device. 
     In one embodiment, a super-capacitor is provided in addition to a battery. The super-capacitor can be charged when the user does not have enough time to dock and leave the device in a charging station. In one embodiment, a docking station includes contacts for both a battery and a super-capacitor. Thus, the super-capacitor is charged when the device is docked for a short time. The user can then use the device, and subsequently dock the device for a longer time to charge the batteries in addition to the super-capacitor. 
     In one embodiment, an automatic or facilitated battery charger is provided. This gives the outward appearance to the user of rapid recharging, when in fact, one battery is removed and replaced automatically with another battery. In one embodiment, this is accomplished using two slots in the device (such as the mouse) with one slot being empty and the other having the rechargeable battery. This meets up with a similarly configured pair of slots on a charger, with a fresh, recharged battery being in the slot corresponding to the empty slot of the device. A battery swap is performed, with the used battery then being recharged and being ready for the reverse swap at a later period. Alternately, a single slot in the device can be used, with a rotating chamber in the recharger for first accepting the discharged, used battery, then rotating to insert a charged battery. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a circuit diagram of a charging circuit for a USB buffer to connect to a mouse according to one embodiment of the invention. 
         FIGS. 2   a ,  2   b  illustrate a charging cradle and mouse, respectively, with multiple contacts for a battery and a super-capacitor according to one embodiment of the invention. 
         FIG. 3  is a diagram of a USB dongle having both a recharging circuit and a wireless receiver according to one embodiment of the invention. 
         FIG. 4  is a diagram of a mouse and battery swapping cradle with multiple slots according to an embodiment of the invention. 
         FIG. 5  is a diagram of a mouse and a battery swapping cradle having a rotating chamber according to an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 1  is a diagram of a mouse and buffer charging circuit according to an embodiment of the invention. The wireless device, a mouse in this example, includes a circuit  10  with a super-capacitor  12  for providing power to the mouse circuitry. The electricity from the super-capacitor is provided through a low dropout (LDO) linear regulator or DC-DC converter  14 . A rectifier  16  (preferably a Schottky diode) is connected between a first contact  18  and super-capacitor  12 . A second contact  20  is also provided. 
     When the mouse is docked in a charging cradle, it comes in contact with a USB buffer charging circuit  22 . The buffer charging circuit is connected to USB leads  24  and  26 . A resistor  28  connects to one end of a larger super-capacitor  30 . Super-capacitor  30  has more (e.g., twice) the capacity of super-capacitor  12  of the wireless mouse. When the mouse is connected, an outrush current limiter  32  is provided between capacitor  30  and a contact  34  to prevent sparking while allowing an ultrafast recharge after a few tens of milliseconds. A second contact  36  connects with mouse contact  20 . Resistor  28  is sized to limit the amount of current drain when charging the super-capacitor  30  so that it remains within the USB specifications. 
     An advantage of the super-capacitor charging circuit is that there is no voltage issue. In particular, there is no need to step up the buffer voltage to recharge a battery, and no charge circuitry. There is also no permanent current drain from the USB. The current tends toward 0 as soon as the buffer super-capacitor approaches full charge. The circuitry itself is a very simple electronic circuit, with no complicated recharge design required. 
     An advantage of buffering through a reservoir storage (either made of a supercap or any other electricity storage device) is the ability to slowly accumulate trickle energy from a source that would not be able to deliver a big charge current by itself, and then transfer it, when needed, at a (much) faster rate. Another advantage of the supercap when used both as reservoir capacitor in the buffer and as energy storage in the device is its unique ability to accomplish a very fast delivery (and absorption) of the energy. An ultra fast energy transfer translates into a short docking time, which means a short time the device is unavailable for use. 
       FIG. 2A  shows a docking and recharging cradle  40  having battery contacts  42  and  44 . In addition, it includes super-capacitor charging contacts  46  and  48 . 
       FIG. 2B  shows the bottom of a wireless mouse  50  with an optical sensor  52 . It includes battery recharging contacts  54  and  56 . In addition, it includes super-capacitor recharging contacts  58  and  60 . 
     In one embodiment, using the mouse and charging cradle of  FIG. 2A , both the battery and the super-capacitor are charged at the same time. The user can thus decide to operate with only the super-capacitor being charged by only leaving the mouse in the cradle for a short period of time. This will provide the user with a limited amount of use time for the mouse, until such a time as the user can leave the mouse in the cradle for a longer time to recharge the batteries as well. 
     In an alternate embodiment, only a single set of contacts are used, with circuitry inside the mouse or other wireless device for providing the charging current to both the batteries and to the super-capacitor. Alternately, the mouse may have only a super-capacitor, with the battery contacts being used to charge the super-capacitor. 
       FIG. 3  shows an embodiment of a USB dongle  70  according to an embodiment of the present invention. The dongle has a USB connector  72  and a wireless receiver circuit  74  with an antenna  76 . Such dongles are used to provide wireless reception at the USB port of a computer for a wireless mouse or other input device. Dongle  70  of  FIG. 3  in addition includes a super-capacitor recharging circuit  78 . 
     Circuit  78  of  FIG. 3  can be the same circuit as circuit  22  of  FIG. 1 . However, the same USB contact is not used for both charging and discharging. There are technical and USB standards reasons: among others, the USB standard does not allow giving back current or even voltage to an USB port, especially when the PC is OFF or in suspend mode. Instead, the present invention adds a non standard 5th contact  71  in the dongle plug, to connect to discharging contact  34  of the circuit of  FIG. 1 , from which only a specially designed mouse or other apparatus could take its power. The normal VBus contact  73  connects to charging contact  24  of  FIG. 1 . 
     The 5th contact is located behind the normal VBus contact (i.e. deeper in the USB plug) as shown in  FIG. 3 , where the VBus contact in a standard USB socket has no chance to ever touch it. However, alternate embodiments could put the contact in other positions. Dotted line  75  shows the area where the 4 contacts in a legacy USB socket normally expect to encounter a track on the plug PCB. The 5th contact  71  would only come in contact with a custom socket for the mouse, capable of reaching the contact  71 . 
       FIG. 4  is a diagram of an embodiment of a wireless mouse and a recharging cradle where the mouse has two receptacles or slots. As shown in  FIG. 4 , a mouse  80  is inserted into a cradle  82 . The mouse has an empty slot  84  and a second slot with a battery  86 . The cradle  82  has two slots with the battery  88  in the mirror image, and slot  90  being empty. 
     When the mouse is connected into the cradle, a protrusion  92  on the cradle engages a release switch  94  on the mouse, which causes battery  86  to be ejected into slot  90 . At the same time, a plunger or other mechanism can eject battery  88  into slot  84  of mouse  80 . The process can be repeated some time later when battery  86  is charged and battery  88  has run down. At that time, the reverse operation will occur, with battery  88  being ejected from the mouse and battery  86  being injected into the empty slot of the mouse. 
     In one embodiment, protrusion  92  on charger  82  contacts a quick release battery button  94 . Such a button mechanism can be similar to that used on Logitech&#39;s G7 gaming mouse, which allows quick release for replacement of batteries. Since it is easier to have the mouse eject the battery than to pull it out with some mechanism on the charger stand, this embodiment takes advantage of that feature on the mouse. The mouse can engage a catch or other restraining mechanism to hold it against the charger so it won&#39;t be dislodged by the force of the battery being ejected or injected. 
       FIG. 5  shows an alternate embodiment of a charger  100  with as rotating barrel  102  having multiple chambers. A mouse  104  is inserted into charger  100 , with its nose up against an overhang  106  which holds the mouse in place while a battery is injected or ejected. When the mouse is docked, a protrusion  108  engages a battery release button  110 , causing the battery to be ejected from chamber  112  into a chamber  114 . A motor  116  then rotates chamber  102 , positioning a battery which has been recharged into the chamber below mouse chamber  112 . A solenoid plunger mechanism  118 , or other mechanical mechanism, then forces the battery into chamber  112  of the wireless mouse  104 . As shown, there are electrical contacts  120  and  122  on the left chamber of the rotating chamber  102  for recharging a battery. No contacts are needed for the injection/ejection portion on the right side of rotating chamber  102 . 
     In the embodiments of  FIGS. 4 and 5 , a spring-released battery cover door covers the openings to the battery chamber on the wireless mouse. In one embodiment, the door can be engaged by a protrusion or pin on the charger to open the door when the mouse is inserted into the chamber. Alternately, battery release button  110  can cause the door to open, as well as ejecting the battery. After the battery has been ejected and a new one injected, upon removal, the pin releases the spring-loaded door, causing it to close. The inside of a spring-loaded door would include one of the contacts for the battery. 
     As will be understood by those skilled in the art, the present invention may be embodied in other specific forms without departing from the essential characteristics thereof. For example, alternate mechanisms for replacing a battery could be used, such as injecting a battery from one side and causing the battery to be ejected out the other side by the force of the injected battery. Also, although a mouse is described as an example of a device, any other device could be used, such as any human interface device, including a trackball, gamepad, remote control, keyboard, mobile phone, PDA, MP3 player, etc. In addition to the ejection and swapping of legacy batteries or battery packs, the invention can provide for the ejection and swapping of supercaps, or composite elements (packs). A pack can contain a supercap rather than a battery, and incorporate circuitry such as resistor  28  and current limiter  32  in addition to the supercap. This would thus protect the capacitor from unwanted potential shorts. Accordingly, the foregoing description is intended to be illustrative, but not limiting, of the scope of the invention which is set forth in the following claims.