Patent Application
20070018611
The invention relates to a method and arrangement for changing information between a battery element and a battery-powered electronic device. Especially the invention concerns an electrical interface between a battery element and an electronic device such that information related to a battery element can be transferred to an electronic device.
The widespread use of battery-powered electronic devices (e.g. cellular mobile phones, laptops, palmtops) with high performance relies on efficient battery utilization. These kinds of devices typically use re-chargeable batteries like lithium-ion, nickel-cadmium or nickel metal hydride batteries. New battery technology gives longer working time to battery-powered devices through providing a wider voltage range. A new-technology battery can be charged up to a higher voltage and/or it can be discharged down to a lower voltage than a corresponding older generation battery. Many times the users of battery-powered devices are willing to use not only batteries made by the vendor of a device but also batteries made by third parties. For example, a user may want to have an additional backup battery for his battery-powered device. A spare part battery manufactured by a third party and representing older-generation battery technology may be considerably cheaper than a new-technology battery manufactured by the vendor of the electronic device. Therefore, at certain times a new-technology battery is used with a battery-powered electronic device while at certain other times an older-generation battery is used with the same electronic device. A system for controlling charging of a battery or a part of the system is many times integrated into an electronic device, like in a case of e.g. a mobile phone. A system for charging control has to be able to identify new technology batteries from conventional technology batteries that have lower full charging voltage. If a battery realized with a conventional technology is charged using too high voltage it will be overcharged. An overcharged battery may cause a safety hazard and it may even explode.
One traditional method is to design a mechanical coupling between a battery element and an electronic device in a way that only the battery elements made by the vendor of the device are able to fit with the device e.g. with a cellular mobile phone. The advantage reached by this method is, however, only temporary because a third party battery manufacturer may copy the mechanical shape of a battery element. If a third party battery maker does not copy the technology inside a battery element, a copied battery element causes a serious safety risk when used with the electronic device.
where Ub is the battery voltage produced by the battery cell unit 125, R_BSI is the resistance [Ω] of the BSI resistor 124 and R_up is the resistance [Ω] of the pull-up resistor 123. Voltage Um is measured by a control element 104.
The type of the battery element 102 is identified by the control element 104 based on the value of the measured voltage Um.
The battery cell unit 125 is charged by an external source of electrical energy 128 that is connected to the device 101 via galvanic contact elements 114 and 115. Charging current and/or voltage applied to the battery cell unit 125 are/is controlled by a switch 129 and a regulator element 126 that are controlled by the control element 104. The control element selects a suitable charging algorithm according to the identified type of the battery element 102. The selected charging algorithm determines, among others, the maximum allowable values of charging current and charging voltage. The maximum allowable values may be functions of e.g. a charging state of the battery cell unit 125. The charging state can be measured for example by opening the switch 129 at certain time intervals and by measuring the voltage produced by the battery cell unit 125. The charging algorithm may also determine what kind of phenomenon is used for indicating a full charge state. A usable indicator for a full charge state depends on the chemistry of a battery cell. For example, with certain battery types a level of voltage produced by the battery cell unit can be used as an indicator for a full charge state.
When the battery element 102 is removed the BSI resistor 124 is disconnected and the pull-up resistor 123 pulls the measured voltage Um up to voltage of a positive rail 121. The detection of the removal of the battery element 102 is based on the resulting step-wise increase on the measured voltage Um. In order to detect the removal of the battery element 102 correctly, the voltage of the positive rail 121 has to be maintained for a time period long enough after an electrical connection via the galvanic contact element 112 is broken. This can be accomplished by designing the galvanic contact elements 111, 112, and 113 in a way that when the battery element 102 is removed the electrical connection via the galvanic contact element 112 is broken earlier than electrical connections via the galvanic contact elements 111 and 113, e.g. by using a shorter pin in the galvanic contact element 112 than in the galvanic contact elements 111 and 113. Another alternative is to use a capacitive energy storage 127 that maintains the voltage of the positive rail 121 after the removal of the battery element 102 for so long a time period that the removal of the battery element 102 can be correctly detected.
A drawback of distinguishing new-technology battery elements from older-generation battery elements based on the measured voltage Um is the fact that for third parties it is very straightforward to produce battery elements whose BSI resistors are similar to those of new-technology battery elements but a battery cell unit represent older-generation technology. In other words, there is a significant risk that on the market there will be such counterfeit battery elements that from the viewpoint of the distinguishing method resemble new-technology battery elements but that actually are older-generation battery elements. This kind of counterfeit battery element causes a serious safety risk when used with an electronic device.
It would be technically possible to block out all except those battery elements that are made by the vendor of an electronic device. This kind of arrangement is shown in
Publication U.S. Pat. No. 6,018,228 presents a method and arrangement for battery identification and for obtaining charging parameters. Also in this method a battery element comprises a module that contains digital identification data plus charging parameter values, such as maximum allowable voltage and maximum allowable current. A controller element within an electronic device reads the identification data and the charging parameters. Blocking out battery elements made by third parties can be avoided by defining a default charging program that is used if the communication between the battery element and the electronic device fails. A feature of this method is the fact that the default-charging program has to be so light-handed that a battery element based on any technology does not cause a safety risk. Another feature is the fact that the widespread battery removal detection method described above is not supported.
In the view of various limitations of battery identification according to prior art, it would be desirable to avoid or mitigate these and other drawbacks and limitations associated with the prior art.
It is an objective of the present invention to provide an interface arrangement and a method for reliable battery identification and for removal detection, the invention allowing the drawbacks associated with the prior art to be eliminated or reduced.
The objectives of the invention are achieved with a combined analogue and digital interface between a battery element and an electronic device so that both analogue and digital data can be transferred from a battery element to an electrical device. Reliable digital authentication is used for determining if a battery element connected to an electronic device represents new battery technology. An analogue signalling scheme is used for identifying different battery elements representing older-generation battery technologies and for detecting battery removals.
In this document a term ‘digital data’ means a piece of information that can represent only a finite number of different values. A term ‘analogue data’ means a piece of information that may represent infinite number of different values. For example, a value of voltage Um in
Signals carrying analogue data and signals carrying digital data are transferred via electrical coupling elements between a battery element and an electronic device in a way that there is no need for any additional electrical coupling element compared to a case in which only analogue data is transferred. Various signals carried by a common propagation path may be separated from each other in many known ways. For example, separation can be based on frequency division when different signals occupy different bands in the frequency domain, separation can be based on time division when different signals are transferred during different non-overlapping time intervals, or separation can be based on a combination of these two methods.
The invention yields appreciable benefits compared to prior art solutions:
An interface arrangement according to the invention between a battery element and an electronic device comprises at least two electrical coupling elements between the battery element and the electronic device, and the combined analogue and digital interface is characterized in that it comprises:
The above-mentioned electronic device can be, for example, a mobile phone.
In this document those parts of communication means for transferring analogue/digital data that are located in a battery element are called communication means for making analogue/digital data accessible to an electronic device. Correspondingly, those parts of communication means for transferring analogue/digital data that are located in the electronic device are called communication means for reading analogue/digital data from the battery element to the electrical device.
A battery element according to the invention comprises at least one rechargeable battery cell and at least two electrical coupling elements for forming electrical connections to an electronic device, and the battery element is characterized in that it comprises:
An electronic device according to the invention comprises at least two electrical coupling elements for forming electrical connections to a battery element, and the electronic device is characterized in that it comprises:
A method according to the invention for identification a battery element electrically connected to an electronic device via at least two electrical coupling elements is characterized in that the method comprises:
A software product according to the invention for identification a battery element electrically connected to an electronic device via at least two electrical coupling elements is characterized in that the software product comprises:
Features of various advantageous embodiments of the invention are listed in the appended depending claims.
The exemplary embodiments of the invention presented in this document are not to be interpreted to pose limitations to the applicability of the appended claims. The verb “to comprise” is used in this document as an open limitation that does not exclude the existence of also unrecited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated.
The invention and its other advantages are explained in greater detail below with reference to the preferred embodiments presented in a sense of examples and with reference to the accompanying drawings, in which
a-4c show timing diagrams of an exemplary line code for transferring digital data from a battery element to an electronic device,
In this embodiment of the invention, combining digital data transfer with the above-described analogue interface is accomplished in a cost effective way with using only a small amount of additional electrical components compared with a case shown in
A transfer of digital data using only a small amount of additional electrical components is based on the fact that in addition to ‘plus’ and ‘minus’ electrical conductors 321 and 322 between the electronic device 301 and the battery element 302 there is a third electrical conductor 325 an impedance of which with respect to the ‘plus’ and ‘minus’ conductors 322 and 321 is so high that its voltage can be altered by the identification circuit 303 and by the control element 304. The impedance of conductor 325 with respect to the ‘plus’ and ‘minus’ conductors 321, 322 is substantially the resistance of a parallel connection of the BSI resistor 324 and the pull-up resistor 323. The resistance of a serial connection of the BSI resistor 324 and the pull-up resistor 323 has to be high, because otherwise a power loss in the serial connection of these two resistors would be too high for a battery-powered device. The resistance of the BSI resistor 324 has to be so high compared with the resistance of the pull-up resistor 323 that the voltage across the BSI-resistor 324 can be measured with a reasonable accuracy. It is assumed here that also the resistance of the pull-up resistor 323 is reasonably high. If this is not the case the situation can be treated by arranging a switching system that disconnects the pull-up resistor 323 while digital data is transferred (not shown in
In this document a conductor whose voltage with respect to ‘plus’ and ‘minus’ poles of a battery cell unit is varied for transferring digital data is said to be the conductor via which the digital data is transferred. For example, in the system shown in
A one-wire data transfer arrangement is used for transferring digital data via conductor 325 from the identification circuit 303 to the control element 304. An example of a one-wire data transfer arrangement for transferring digital data via the conductor 325 is described below. Terminal 327 of the control element 304 is either in a low impedance state (Low-Z) or in a high impedance state (Hi-Z) with respect to the ‘minus’ conductor 322. Correspondingly, terminal 326 of the identification circuit 303 is either in a low impedance state or in a high impedance state. A Low-Z impedance of the terminal 327 is substantially bigger than that of the terminal 326. Both the Low-Z impedance of the terminal 327 and the Low-Z impedance of the terminal 326 are substantially smaller than the resistance of a parallel connection of the BSI resistor 324 and the pull-up resistor 323. Both a Hi-Z impedance of the terminal 327 and a Hi-Z impedance of the terminal 326 are substantially bigger than the resistance of a parallel connection of the BSI resistor 324 and the pull-up resistor 323. With this kind of impedance arrangement the control circuit 304 is able to give commands to the identification circuit 303 by forcing voltage Um up/down when the identification circuit is in the high impedance state. A possible down forcing of voltage Um accomplished by the control circuit 304 overpowers the pulling up by the pull-up resistor 323. The identification circuit 303 can respond by using its own means for changing the potential of conductor 325; a possible down forcing overpowers also the pulling up by the pull-up resistor 323.
A timing diagram of an exemplary line code for transferring digital data from the identification circuit 303 to the control circuit 304 is shown in
Therefore, the system is back at a beginning of phase 1 and the same operation restarts with an incremented bit-pointer. By repeating this operation the bits of the digital data can be read to the control element 304 in a serial form.
The bit-pointer can be arranged to wrap around when the number of bits transferred reaches the total number of bits to be transferred. A need for initialization the bit-pointer at the beginning of a data transfer may be avoided e.g. with an arrangement in which first bits at the beginning of the digital data represent a special delimiter bit-pattern for indicating the beginning of the digital data. This delimiter can be used for tracking the beginning of the data even if the reading is started at an arbitrary point (i.e. with an arbitrary value of the bit-pointer).
A flow chart representing a battery identification method according to another embodiment of the invention is shown by
In an embodiment of the invention digital data read from a battery element to an electronic device is used for selecting a charging algorithm. The selected charging algorithm determines charging parameters, for example, the maximum allowable values of charging current and charging voltage. The maximum allowable values may be functions of e.g. a charging status of the battery cell unit. The charging status can be detected, for example, by measuring voltage produced by the battery cell unit at certain time intervals. The charging algorithm may also determine what kind of phenomenon is used for indicating a full charge state. A usable indicator for a full charge state depends on the chemistry of a battery cell. For example, with certain battery types a level of voltage produced by a battery cell unit can be used as an indicator for a full charge state. In an embodiment of the invention the digital data can contain information about a battery discharge curve. The discharge curve can, for example, express the amount of utilizable energy stored in a battery element as a function of voltage level produced by the battery element. This makes it possible to improve the accuracy of a user interface that informs a user of an electronic device about remaining battery capacity. In an embodiment of the invention digital data read from a battery element to an electronic device comprises a serial number of the battery element. This serial number can be stored in a memory element being in the electronic device. The serial number can be used, for example, in possible future authentication purposes.
In the presented embodiments of the invention shown in
In the presented embodiments of the invention the control element 304, 504, 804 and 904 can be realized with a programmable processor plus a software product comprising software means stored on a readable medium for execution by the processor, the software means for performing and/or controlling the above-mentioned functions like reading digital data from a battery element to an electronic device, reading analogue data from a battery element to an electronic device, controlling the battery identification process, controlling charging of a battery cell unit, and illustrating battery charging status via a user interface. As another option a control element can be realized with one or more dedicated circuits that is/are designed to perform the above mentioned operations. In this case electrical connections between logic ports and other elements of a circuit form the intelligence that controls the operations. A dedicated circuit can be e.g. an application specific integrated circuit (ASIC). A control element can also be realized with one or more field programmable gate array (FPGA) components. A FPGA component is configured before its operation with configuration software to emulate a dedicated circuit. Furthermore, a control element can be a hybrid construction comprising at least two from the following list: a programmable processor plus a corresponding software product, a dedicated circuit, a field programmable gate array component plus appropriate configuration software.
Electrical coupling elements between a battery element and an electronic device are preferably galvanic contact elements. In principle the one or more of electrical coupling elements between the battery element can be based on a capacitive or inductive coupling or both, but this leads to a more complex technical solution with d.c-a.c. conversions, because d.c. power/signal cannot be transferred through an inductive or capacitive electrical contact element.
It is obvious to a person skilled in the art that the invention and its embodiments are thus not limited to the above-described examples, but may vary within the scope of the independent claims. For example, an analogue interface between an electronic device and a fuel cell battery element can be supplemented according to the invention by a digital interface.
