Abstract:
There is disclosed a sleeve for holding a portable electronic device such as an MP3 player, mobile telephone, PDA and the like. The sleeve is provided with an integrally formed secondary winding that enables the sleeve to pick up magnetic flux from an inductive charging platform and associated circuitry for generating a DC charging voltage that can be used to charge a battery in the device while the device is received within the sleeve. The sleeve is formed with a connector designed to fit a power/data connection socket in the device, and may also be provided with a connection port enabling the device to be connected to a computer while it is received within the sleeve.

Description:
FIELD OF THE INVENTION 
     This invention relates to a sleeve that is designed to receive a mobile electronic device and to enable such a device to be charged by means of an inductive charging system. 
     BACKGROUND TO THE INVENTION 
     Mobile electronic devices, including mobile phones, portable music and video players, digital cameras, camcorders, computer peripherals etc. are widely used today. For environmental reasons, such devices are often powered by rechargeable batteries. 
     There exist a number of methods for charging the rechargeable batteries. As shown in  FIG. 1 , a first method is to connect the electronic devices  1  to a conventional power line through a power adaptor  2 . This method also includes the possibility of removing batteries out of the device and charging them with external chargers, or charging a battery through a USB connection  3  on a PC. No matter what kind of approach is used, the power adaptors and their cables are always cumbersome, and in the case of charging using a USB port, this is restricted by the availability of computers that can be found. Furthermore, the USB port normally can only output a power of 2.5 W which is sometimes lower than the power requirement for recharging and which can cause the charging speed to be slower than a normal battery charger, though it does have the advantage of simultaneous data exchange with the computer at the same time as battery charging. 
       FIG. 2  shows the pin definition of the connecting port  4  of an exemplary mobile electronic device and its corresponding power/data connector  9 . For simultaneous power and data transfer, there are two pins (pin  2  and pin  3 ) for data connection in addition to the pins (pin  1  and pin  4 ) used for charging. Many devices have their own charging protocol which needs some predefined voltage level at the data pins to start or continue on charging. For example, some devices need pin  2  and pin  3  to have voltage of 3 V and 2 V, respectively, so that the charging process can be maintained. This requirement can be easily met if the device is charged through a USB port because the data pins can be controlled by the computer. However, when such a device is charged by using a power adaptor  2 , a voltage divider as shown in  FIG. 2  must be used to provide the required voltage level for data pins. 
     To get rid of the power wire or the USB connector one possible solution is to use an inductive battery charging platform examples of which are disclosed in U.S. Pat. No. 7,164,255B and US20070029965A. As shown in  FIG. 3 , the mobile electronic device is inductively coupled with a charging platform  5  which eliminates the need for charging cables to the device. The charging platform  5  is provided with one or more primary windings that generate a magnetic flux that can be picked up by a secondary winding  6  which may be provided integrally with the electronic device. For example, the electronic device may be provided with an inductive energy receiving unit (IERU)  7  which includes the secondary winding  6  and the associated processing circuitry  8  as shown in  FIG. 4 . 
     As shown in  FIG. 4 , an energy receiving winding or coil  6  receives magnetic flux from the charging platform, and the received AC energy is rectified and regulated to a suitable DC voltage to charge the battery. In the prior art it is known that the IERU  7  may be integrated into the device or into the battery pack (US20070029965A) and this is the best approach for future devices. Also known is that the IERU  7  may be integrated into a new back cover for a device which may be used to replace the original (US20060061326A, US20060205381A). 
     However, there is a need to enable existing devices that are not provided with such an integral IERU—or devices where it is difficult to provide an integrated IERU—to be charged using such an inductive charging platform. One solution to this is to provide the IERU in an external module which is attachable to the back of the device (GB2399466B, US20060205381A). The output of IERU is connected to the connecting port of the device through a short wire or through a power connector. This is a straightforward approach to adapt conventional devices to the charging platform. However, the added module is an extra ‘burden’ to the devices, which has no other function or attraction to a consumer. 
     SUMMARY OF THE INVENTION 
     According to the present invention there is provided a sleeve for receiving a mobile electronic device, the sleeve including a winding for receiving magnetic flux from an inductive charging system, an energy processing circuit for generating a DC output voltage from the magnetic flux, and electrical connection means for connecting the circuit to a device received within the sleeve whereby the device may be charged by placing the sleeve with the device therein on a surface of an inductive charging system. 
     Preferably the sleeve comprises at least one planar surface and the winding is a planar winding integrally formed with the surface. Electromagnetic shielding may be provided between the winding and a side of the surface facing a device when received in the sleeve. 
     Preferably the planar winding is formed on a printed circuit board, and the energy processing circuit may be formed on the same printed circuit board as the planar winding. Alternatively, the energy processing circuit and the electrical connection means are formed on one printed circuit board. 
     The connection means is preferably a combined power and data connector adapted to be received within a combined power and data socket formed in a device. 
     In one embodiment of the invention the sleeve is provided with an attachment clip and the winding is provided as part of the clip. The clip may further comprise electromagnetic shielding on a side of the clip that in use will face a device received within said sleeve. 
     The energy processing circuit may preferably include a diode provided at the output of the circuit to prevent reverse current flow. The sleeve may also be provided with a port for connecting a device received therein to an external power source such as a computer or a power adaptor. 
     Preferably means are provided for disabling either the energy processing circuit or the external power source when both are provided. When the energy processing circuit is disabled, preferably the inductive charging system may also be disabled. Preferably the energy processing circuit is provided with means for clamping data pins of said device at predetermined voltages and said clamping means is disabled when said external power source is provided. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which: 
         FIG. 1  illustrates schematically prior art methods for charging mobile electronic devices, 
         FIG. 2  illustrates a typical configuration of data and charging pins for a device to be charged via a USB port or a power adaptor, 
         FIG. 3  illustrates an inductive battery charging platform according to an example of the prior art, 
         FIG. 4  illustrates an inductive energy receiving unit for use in the prior art, 
         FIG. 5  illustrates schematically a first embodiment of the invention, 
         FIG. 6  is a view of a sleeve for use in an embodiment of the invention, 
         FIGS. 7(   a ) and ( b ) are cross-sectional views of the sleeve of  FIG. 6 , 
         FIG. 8  is a back view of the sleeve in an alternative embodiment, 
         FIG. 9  shows schematically the electrical connection between the sleeve and an electronic device, 
         FIG. 10  shows a sleeve according to a further embodiment of the invention, and 
         FIG. 11  shows schematically an alternative electrical connection between the sleeve and an electronic device. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     As will be seen from the following description, in preferred embodiments of the present invention the inductive energy receiving unit (IERU) is integrated with a sleeve that is designed to receive at least a part of an electronic device. The sleeve provides the benefits of (a) receiving inductive energy (b) protecting the mobile device, and (c) also the sleeve can be provided with a decorative pattern, or advertising or promotional material. It will be understood in this regard that the term “sleeve” is intended to cover any article that is designed to hold a mobile electronic device. 
       FIG. 5  shows a first embodiment of the invention. This embodiment includes a sleeve  10  that is of such a size that it can receive a mobile electronic device  20 . The sleeve can be made of silicone, leather, vinyl, plastic, fabric, or any other material suitable to make a sleeve for mobile electronic device protection. It will be understood that the dimensions of the sleeve will be chosen depending on the size and shape of a mobile electronic device that it is intended to receive. A range of differently sized sleeves may be provided. The sleeve should be sized such that it is sufficiently large to permit the electronic device to be inserted into and removed from the sleeve though an opening  11  provided at one end of the sleeve, while being a sufficiently tight fit that the device is held securely. The sleeve may be formed of any suitable material which may include a resilient material chosen to assist the holding of the device by the sleeve. 
     The sleeve  10  may also be provided with one or more further openings  12  to allow a user to access the device  20  when it is received therein including accessing any control buttons, touch screen or the like, or to enable any camera, microphone or the like that forms part of the device to function properly. The sleeve is formed integrally with the IERU such that the sleeve may receive energy inductively when it is placed on or in proximity with the charging platform  30 . For example, one or more secondary windings may be formed in the back face  13  of the sleeve with the associated power electronics being provided at a suitable location as will be described further below. 
     As can be seen from  FIG. 6 , which is a top view of the sleeve, at the end of the sleeve remote from the opening  11  through which the device is inserted into the sleeve, there is provided a power/data connector  14 . When the mobile electronic device is inserted into the sleeve  10 , the power/data connector  14  engages the connecting port  4  of the mobile electronic device.  FIG. 6  also shows the associated energy processing circuitry  15 . Processing circuitry  15  may comprise a printed circuit board  17  (PCB) with electronic components mounted on it including the rectifier and regulator as shown in  FIG. 4 . The rectifier rectifies the received high frequency AC signal to DC and may take any suitable form including a full-bridge rectifier, voltage doubler, current doubler, center-tap rectifier or forward rectifier. In the embodiment shown in  FIG. 6  the processing circuitry  15  is adjacent the power/data connector  14  but it will be understood that this is not essential. 
     Detailed examples of two possible structures for the sleeve in particular with regard to the location of the processing circuitry  15  are shown in  FIGS. 7(   a ) and ( b ) which are cross-sectional views of the sleeve  10  together with a mobile electronic device  20  inserted inside. For simplicity, only a part of the back face  13  of the sleeve  10  is shown. In this context it should be noted that the term ‘back’ means the side intended to face the inductive battery charging platform in a charging operation. 
     In the embodiment of  FIG. 7(   a ) the energy processing circuitry  15  is placed beside the power/data connector  14 . The energy processing circuitry  15  and the power/data connector  14  may, but not are limited thereto, share the same PCB  17 . The input of the energy processing circuitry is the received AC energy from a secondary energy receiving winding layer  31 , while its output is a DC supply that is connected to the connector  14  which is inserted in the connecting port  4  of the device  20 . One important design issue of this structure is to make the back wall of the sleeve as thin as possible. To achieve this goal, the thickness of the winding layer  31  as well as the shielding layer  32  must be minimized. The energy receiving winding layer  31  may take the form of one or more conductive windings formed on a PCB which may have a thickness of only a few hundred microns. The other structures for the winding layer  31  are possible however and may include one or more windings in the form of a planar spiral coil. The shielding layer  32  is important as it is designed to prevent magnetic flux leakage into the device and which may detrimentally influence the operation of the device. The shielding layer  32  may be a double-layer shielding structure which contains a layer of soft-magnetic material and a layer of conductive material as described in U.S. Pat. No. 6,501,364B and U.S. Pat. No. 6,888,438B. Such a structure can have a thickness of only a few hundred microns and can still provide acceptable shielding effectiveness. 
     Another possible structure is shown in  FIG. 7(   b ) in which the energy processing circuitry  15  is placed beside the winding and shielding layers  31 ,  32 , instead of the connector  14 . This embodiment has the advantage of reducing the minimum length of the sleeve, compared to  FIG. 7(   a ). However, this approach can only be implemented if the height of the components in the energy processing circuitry is low enough. In this embodiment, the energy processing circuitry  15  and the winding layer  31  may, but are not limited thereto, share the same PCB. 
     Another embodiment is shown in  FIG. 8  which is a back view of a sleeve  10 . The sleeve  10  is provided with a clip  16  at the back which may be used for attaching the sleeve to a bag or a belt or the like. As shown in  FIG. 8 , the winding and shielding layers  31 , 32  can be formed as part of the clip  16 . The only limitation is the size of the belt clip which must be large enough to contain the winding and shielding layers  31 ,  32 . 
     In all the above embodiments, the power/data connector  14  is always connected with the connecting port  4  when the device  20  is inserted in the sleeve  10 . To avoid energy leakage from the device (battery) to the energy processing circuitry  15 , especially when the device is not being charged, a diode (D 0  in  FIG. 9 ) is added at the output of the energy processing circuitry  15  to prevent any reverse current. In addition, in  FIG. 9 , R 1 -R 4  are four resistors that provide required voltage levels to the data pins of the power/data connector  14  as discussed above with reference to  FIG. 2 . If other charging protocols are required by the data pins, a corresponding method for providing controlled voltages to the data pins can be provided. 
     It will be understood that in the above embodiments when a device  20  is put into the sleeve  10 , the connecting port  4  of the device is occupied by the power/data connector  14  of the sleeve  10 . It would therefore not be possible to connect the device  20  to a computer (or to a dock) through a USB connector for data transfer while the device is in the sleeve  10  as there would be no usable port. A straightforward solution for all the above embodiments is to take the device  20  out of the sleeve and connect it through a USB cable to a USB port in a computer in a conventional manner. However this is cumbersome for many users and frequent plug and unplug of the connectors in the sleeve may shorten its life. 
     A better solution is shown in the embodiment of  FIG. 10 . Compared to  FIG. 5-FIG .  8 , the sleeve in  FIG. 10  further has an external port  21  through which the device can be connected to a computer (or another external charger if needed). The external port  21  can be a part of the energy processing circuitry  15  or may be placed anywhere on the sleeve. With this external port  21 , a user can place the sleeve  10  (including the device  20 ) on an inductive charging platform for charging or connect the device  20  to a computer without taking the device  20  out of the sleeve  10 . 
     However, if a user were to simultaneously place the sleeve  10  (including device  20 ) on the charging platform and connect it to a computer, problems may arise. Firstly, the received energy from the IERU may destroy the USB port of a computer. Secondly, the voltage level of the data pins (pin  2  and pin  3  in  FIG. 9 ) are clamped at 3 V and 2 V, respectively, so that data transfer is disabled. To solve these potential problems, the energy from one input (IERU or external port) must be disabled. A possible embodiment of a circuit to implement this idea is shown in  FIG. 11 . In  FIG. 11 , a switch, S 1  is an added switch to select the energy input from the energy processing circuitry  15  or from the external port  21 . S 1  is normally at the position of ‘c’, when no energy is input. When the DC output of energy processing circuitry  15  is high, S 1  is controlled to be at the position of ‘a’. The device is solely powered by IERU. When pin  1  of the external port  21  is high, (which means that it has been connected to a computer) S 1  is controlled to be at the position of ‘b; and the device is solely powered by the external port. Pin  1  at high also has the function to turn off S 2  which is another added switch. When the device is connected to a computer, data pins (pin  2  and pin  3 ) are solely controlled by the computer so that data transfer is enabled. D 1  and D 2  are two diodes added to avoid the voltage at the data pins from going back into the R 1 -R 4  circuit. 
     In a possible situation that the DC output of energy processing circuitry  15  and pin  1  of external port  21  are both high, the following possibilities exist:
     1) Position ‘a’ of switch S 1  has higher priority. No matter whether the device is connected to a computer or not, it is always powered by the inductive charging platform. This approach has the advantage of simultaneously charging with higher power (than 2.5 W of USB) and data transfer (because S 2  has been turned off).   2) Position of ‘b’ of switch S 1  has higher priority. No matter whether the device is placed on an inductive charging platform or not, it is always powered by the external port. Furthermore, (not shown in  FIG. 11 ), under this condition, the status of pin  1  of the external port can be fed into a MCU (Micro Controller Unit) of the energy processing circuitry  15 . If pin  1  of the external port is high, the MCU may also send information back to the charging platform through a suitable communication method to stop the power transfer at all, which further saves energy.   

     The above two possibilities can be chosen based on the requirement of customers.