1. Field of the Invention
The invention relates to a device for driving an actuator. Furthermore, the invention relates to a system consisting of such a device, an actuator and a transmission device as well as a transmission device for use in such a system. Moreover, the invention relates to a method for driving an actuator.
2. Description of Related Art
Triggering an actuator in a contactless manner is already known. Such actuators are used, for example, in electronic lock cylinders, with the actuator in the case of such an application being configured as a locking magnet controlled by an electronic circuit.
Document DE 103 48 569 A1 describes a device for driving an actuator based on a contactless communication of a transponder with a transmission device. The transponder shown in this document receives control signals via an antenna device, wherein the transponder is able to trigger the actuator depending on the control signals. The power transmitted by the transmission device via the contactless communication is in this case supplied to a power storage device in the transponder. The power of the power storage device is used for triggering the actuator. In this case, it may happen that the power storage device is not yet sufficiently charged to trigger the actuator when a control signal for triggering the actuator is received. In such a case, the actuator is not triggered by the control signal.
Today, NFC technology (NFC=Near Field Communication) is often used for contactless communication between a reading device and a transponder. In this regard, a method by means of which a transponder can transmit information to a reading device about the strength of the reading field is described in the standard ISO/IEC 14443-4. Corresponding bits of the INF field are being used by so-called WTX requests for this purpose. In most contactless applications, such as, for example, the use of RFID chips in passports or credit cards, information relating to the strength of the reading field is not, however, transmitted or even required.
It is the object of the invention to enable a contactless triggering of an actuator in a simple and reliable manner.
The device according to the invention comprises a power storage device, for example in the form of a capacitor, for supplying an actuator, an antenna device by means of which power for charging the power storage device and one or more control signals, which comprise a triggering command for triggering the actuator, can be received from a transmission device via a contactless communication, in particular based on the NFC technology, and a control unit for controlling the power supply from the power storage device to the actuator depending on the control signals. In this case, the device according to the invention is configured such that, during operation of the device, the charge state of the power storage device is determined after receiving the triggering command, wherein, in the case of a charge state of the power storage device lower than a charge state threshold value sufficient for triggering the actuator, a response signal for continuing the contactless communication is transmitted via the antenna device for reception by the transmission device, and wherein, in the case of a charge state of the power storage device higher than or equal to the charge state threshold value, the control device controls the power supply from the power storage device to the actuator such that a triggering of the actuator is enabled.
The invention is based on the idea of maintaining a contactless communication between a driving device and a transmission device until reaching a charge state value of the power storage device sufficient for triggering the controlled actuator, in order thus to ensure the triggering of the actuator even if a sufficient charge state of the power storage device has not yet been reached when the triggering command is received. By maintaining the contactless communication, the reception of power for charging the power storage device is continued, so that the actuator can finally be triggered when a sufficient charge state has been reached. The device according to the invention is advantageous in that a transmitted triggering command is always suitably processed, without an error message which is due to a power storage device that is not sufficiently charged being returned. The charge state threshold value sufficient for triggering the actuator can in this case be determined such that it ensures the triggering of the actuator with certainty, i.e. the charge state threshold value can also lie below the lower threshold value below which it is not possible to trigger the actuator. For example, the charge state threshold value can be substantially 100% charge of the power storage device. However, the charge state threshold value of the power storage device can also be determined such that the actuator cannot be triggered if the charge state of the power storage device is below this charge state threshold value.
In a preferred embodiment, the device is configured such that it transmits a confirmation signal via the antenna device for reception by the transmission device after the actuator is triggered. Preferably, the response signal in this case is an instruction for extending or restarting a waiting time during which the transmission device waits for the confirmation signal. The instruction for extending or restarting the waiting time can in particular be a WTX request in accordance with the ISO/IEC 14443-4 standard. The use of an instruction for extending or restarting a waiting time in particular has the advantage that the waiting time, and thus the contactless communication, can be extended on the level of the transmission protocol without the transmission device having to know special codes for continuing the contactless communication. However, it is also possible that the response signal is a special repeat instruction to cause the transmission device to retransmit the triggering command.
In a preferred variant of the device according to the invention, the charge state of the power storage device is determined by a charge state measuring unit for measuring the charge state, wherein the control unit is able to query the charge state of the power storage device from the charge state measuring unit, preferably via a measurement data interface. The use of such a charge state measuring unit is advantageous in that information regarding the charge state of the power storage device can optionally also be transmitted in the response signal.
Moreover, in another variant of the device according to the invention, a charging current measuring unit for measuring the charging current of the power storage device is provided, wherein information about the charging current can also be transmitted in the response signal to the transmission device. If the ISO/IEC 14443-4 standard is used, the information about the charge state or the charging current of the power storage device can be coded particularly simply by the bits of the WTX requests already provided for a power level indication.
In a particularly preferred embodiment, the control unit provided in the device according to the invention is an integrated circuit, in particular a chip for chip cards, whereby particularly compact dimensions of the device are obtained. In a preferred variant, the actuator is a component of a locking device, with the locking and opening of the locking device being triggered by the actuator.
Apart from the device just described, the invention further relates to a system comprising a transmission device, an actuator and the above-described driving device according to the invention, wherein the actuator can be triggered by the driving device via a contactlessly transmitted triggering command of the transmission device. Preferably, the system is configured such that the actuator can only be triggered after a successful authentication between the driving device and the transmission device, so that the system can also be used for security-sensitive applications.
The system according to the invention is preferably used in combination with a driving device which uses an instruction for extending or restarting a waiting time as a response signal for continuing the contactless communication. In this case, the transmission device, after receiving this instruction, contactlessly transmits a confirmation response to the driving device, which subsequently determines the charge state of the power storage device again, wherein, in the case of a charge state of the power storage device lower than the charge state threshold value, an instruction for extending or restarting the waiting time is transmitted again via the antenna device to the transmission device, and wherein, in the case of a charge state of the power storage device higher than or equal to the charge state threshold value, the control unit of the driving device supplies the power from the power storage device to the actuator for triggering the actuator. Preferably, the WTX response known from the ISO/IEC 14443-4 standard is used as a confirmation response in this case, wherein the WTX response is transmitted by the transmission device after receipt of the corresponding WTX request.
In a further embodiment of the system according to the invention, the transmission device is configured such that in the case where a repeat instruction is transmitted as a response signal by the driving device, the transmission device transmits the triggering command again.
Apart from the above-described system, the invention moreover comprises a transmission device for use in such a system, wherein the transmission device comprises a processing unit for a contactlessly received response signal for continuing the contactless communication, wherein the processing unit transmits a confirmation response in response to the response signal or transmits the triggering command again.
Preferably, the processing unit of the transmission device is capable of processing contactlessly received information about the charge state and/or the charging current of the power storage device if this information is transmitted. In this case, the processing unit preferably includes a signaling unit for signaling the charge state and/or the charging current for a user. In this case, the signaling unit can be a display panel or a display or also an acoustical signaling unit. The use of such a signaling unit is advantageous in that a user is informed about the current charge state of the power storage device and is able to see how much time is still required until the actuator is triggered. A user can also initiate appropriate countermeasures if an insufficient charging current is displayed, e.g., he can dispose the transmission device closer to the actuator in order to increase the charging current. Preferably, the processing unit is able to automatically increase the transmitting power of the transmission device if the charging current drops below a predetermined value.
Moreover, the invention includes a method for driving an actuator with a driving device, wherein power for charging a power storage device of the driving device and a triggering command for triggering the actuator is transmitted to the driving device from a transmission device via a contactless communication, wherein the charge state of the power storage device is determined after receiving the triggering command in the driving device, and, in the case of a charge state of the power storage device lower than a charge state threshold value sufficient for triggering the actuator, a response signal for continuing the contactless communication is transmitted from the driving device to the transmission device, whereas, in the case of a charge state of the power storage device higher than or equal to the charge state threshold value, the driving device connects the power storage device to the actuator, thus triggering the actuator.
Exemplary embodiments of the invention are described below with reference to the attached figures.
In the figures:
The invention will be described below based on a so-called NFC communication (NFC=Near Field Communication), in which signals are exchanged wirelessly or contactlessly between a transponder comprising an RFID chip (RFID=Radio Frequency Identification) and a corresponding NFC reading device. Here, the transponder corresponds to the driving device and the NFC reading device to the transmission device in the sense of the claims.
The circuit arrangement 1 comprises a rectifier 4 which on its AC side is connected to the antenna coil 2. A charging circuit 5, which on the output side can be connected to a capacitor 7 via a switch 6, is connected downstream from the rectifier 4 on its DC side. As an alternative to the charging circuit 5, the capacitor 7 can be connected to the actuator 3 via the switch 6. The switching state of the switch 6 is controlled by a transponder circuit 8 connected in parallel to the charging circuit. In this case, the transponder circuit is, in particular, an integrated circuit in the form of a chip for chip cards, e.g. of a smart card chip.
The charging circuit 5 comprises a regulating circuit 9 which is connected to the DC side of the rectifier 4 and controls a first variable resistor 10 as well as a second variable resistor 11. The first variable resistor 10 is connected in parallel to the DC side of the rectifier 4. The second variable resistor 11 connects one of the terminals of the DC side of the rectifier 4 to the switch 6 via a diode 12.
In contrast to the device shown in document DE 103 48 569 A1, the circuit arrangement 1 additionally comprises a charge state measuring unit 13 connected in parallel to the capacitor 7 and serving for measuring the charge state of the capacitor 7. For example, the measuring apparatus 13 is an analog-to-digital converter with which the voltage at the capacitor 7 can be measured. Moreover, a measurement data interface 15 is provided between the charge state measuring unit 13 and the transponder circuit 8, wherein the transponder circuit is able to query the charge state measured by the measuring unit 13 via this interface. The charge state measured via the measuring unit 13 is in this case used for controlling the triggering of the actuator 3, as will be explained in more detail below. Furthermore, a charging current measuring unit 14, which measures the charging current flowing through the capacitor, is connected in series with the capacitor 7, wherein the measured charging current can also be queried by the transponder circuit 8 via an interface (not shown).
The device shown in
In the device of
In order to trigger the actuator 3 of
If the transponder according to the invention arrives in the response field of the reading device 21, a communication relationship between the transponder and the reading device is first established by the instruction sequence “Request→Anticollision→ATS”. The establishment of the communication relationship is represented schematically by a corresponding rectangle C in
Immediately after the successful completion of authentication, the reading device transmits a triggering command (“activate actuator”) to the transponder to activate the actuator. This command is transmitted at the point in time T5. In the scenario shown in
The first transmission of this WTX request from the transponder, according to
According to
A preferred variant of the invention provides that information about the charge state and the charging current are also transmitted with the WTX requests sent by the transponder, wherein the charge state and the charging current, respectively, can be measured by the measuring devices 13 and 14, respectively, of
A representation of the charge state of 100% is not required because the actuator is immediately triggered in this state.
The structure of a WTX request in accordance with the ISO/IEC 14443-4 standard is shown in
b8=0, b7=0: Device does not support power level indication
b8=0, b7=1: Insufficient power for full functionality
b8=1, b7=0: Sufficient power for full functionality
b8=1, b7=1: More than sufficient power for full functionality.
The interpretation of the “power level indication” by the reading device is optional in this case. According to the invention, the bit assignments are preferably interpreted based on the above table.
Possibly, the field strength of the alternating magnetic field emitted by the reading device is too low to generate a sufficient charging current for charging the charge storage device. It can therefore be provided, according to the above table, that the state of an insufficient charging current is signaled to the reading device by means of a corresponding coding of bit 7 and bit 8 in the WTX request (see coding “bit 8=0, bit 7=1”). Consequently, the reading device may increase its transmission power if possible. In those cases in which it is not possible to increase the transmission power, e.g., when the reading device is provided in a battery-powered mobile phone device, the user of the reading device can be given a signal that the charging current is insufficient, so that, consequently, the user better aligns the antenna of the reading device in relation to the batteryless actuator in order thus to improve the power transmission between the reading device and the transponder. A corresponding signalling of an insufficient charging current or of the progress in charging the capacitor can be given, for example, by an acoustic signal or a display field on the reading device. A variant of the display of the charging progress by means of a bar was already described above with reference to
In a variant of the invention, a special return code can optionally be sent instead of the WTX request from the transponder, instead of the above-described use of the WTX requests or WTX responses for ensuring a sufficient charge state for triggering the actuator. The information that the previously sent triggering command of the reading device could not be executed is coded in the return code. Consequently, the reading device then sends the command “activate actuator” again, with this mechanism, in analogy to the use of the WTX request and the WTX response, being repeated until the charge storage device is sufficiently charged and the triggering command can finally be executed successfully by activating the actuator. Optionally, the charge state of the charge storage device as well as the charging current can also be transmitted in the return code. The charge state of the charge storage device and, optionally, the charging current can also be signaled on the reading device in this variant, again, for example, on the display of the mobile phone device into which the reading device is integrated.
The particulars contained in the above description of sample embodiments should not be construed as limitations of the scope of the invention, but rather as exemplifications of preferred embodiments thereof. Accordingly, the scope of the invention should be determined not by the embodiments illustrated, but by the appended claims and their legal equivalents.
Number | Date | Country | Kind |
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10 2008 005 059.8 | Jan 2008 | DE | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP2009/050474 | 1/16/2009 | WO | 00 | 7/16/2010 |