JP5485090B2 - Contactless charging system, electronic device, and contactless communication circuit protection method - Google Patents

Description

  The present invention relates to a non-contact charging system that performs non-contact charging.

  In recent years, various electronic devices have been miniaturized and carried, and there are many cases in which a plurality of portable electronic devices are carried by one person, and the spread of these portable electronic devices is remarkable. Many portable electronic devices use secondary batteries that can be repeatedly charged and discharged. In order to charge the secondary batteries of these electronic devices, an AC adapter corresponding to each device is generally used. The AC adapter is connected to a charging connector of the electronic device and supplies power used for charging the secondary battery.

  There is also a non-contact power transmission technique using electromagnetic induction as a charging technique for portable electronic devices. In the non-contact power transmission technology, for example, there is an advantage that a contact portion of a charging connector provided in a portable electronic device is not damaged. In another example, since an open contact is unnecessary, there is an advantage that a waterproof shape can be easily adopted.

On the other hand, such a non-contact charging system using electromagnetic induction needs a countermeasure for preventing a target that is not originally assumed from receiving power. Some of the measures are designed so that the physical shape on the power transmission side and the physical shape on the power reception side correspond to each other, and only an assumed target can cause effective electromagnetic induction coupling.
Some non-contact charging systems using electromagnetic induction start charging after determining whether or not the side to be charged is a target to be originally charged using proximity non-contact communication. Such a non-contact power transmission technique is disclosed in Patent Document 1, for example.

  Patent Document 1 discloses a non-contact charging system using proximity non-contact communication for discrimination of a charging target. In Patent Document 1, a control unit is provided in each of a charger capable of performing non-contact charging and an electronic device capable of performing non-contact charging, and ID information is transmitted / received via a power transmission / reception antenna, and the charged side may be charged. It is judged (authenticated) whether it is a target. In addition, in Patent Document 1, a proximity contactless communication unit that can perform charging processing is provided separately from the control unit in both the charger and the electronic device, and after performing preliminary charging, charging processing is performed, and main charging is performed. It is comprised so that it can perform.

  Further, in the second embodiment described in Patent Document 1, a switch for disconnecting the proximity non-contact communication antenna (for charging) and the non-contact power receiving coil from each circuit and the connection of both switches are alternatively selected. And a contention control unit for controlling. The competition control unit alternatively operates the electrical connection with the antenna or the coil at the time of billing communication and at the time of charging to prevent malfunction due to each electromagnetic wave.

JP 2009-247124 A

  In recent electronic devices, it is required to have a non-contact communication unit that performs close communication. Examples of the non-contact communication technology used in the non-contact communication unit include FeliCa (registered trademark), TransferJet, and each RFID.

  In such a non-contact charging system having both a non-contact communication unit and a non-contact charging function, as described in Patent Document 1, charging processing, authentication of a charger or an electronic device, and the like are performed. Can be done using.

  Also, today's electronic devices are required to have a compact arrangement by arranging or overlapping the communication antenna (coil) of the non-contact communication unit and the power transmission / reception coil for the non-contact charging function in the vicinity. There are many.

  By the way, the IC chip that is the core of the non-contact communication unit used in FeliCa or the like is precisely manufactured, and if a voltage exceeding the compensated value is applied, it causes a stop or a failure. For this value, an electromagnetic wave signal is transmitted in consideration of the transmission side device used for non-contact communication. On the other hand, if the communication antenna receives a stronger electromagnetic wave than expected, the communication and the IC chip will be defective, and if the IC chip exceeds the allowable amount, a failure will occur.

As described above, an electronic device or a charger may employ an arrangement structure in which a charging transmission / reception coil and a communication antenna are provided in the vicinity.
In addition, electromagnetic waves used for charging generally transmit much larger power than proximity contactless communication. Some of the existing electronic devices are configured to damage the IC chip by applying an overvoltage to the communication circuit through the communication antenna when receiving such electromagnetic waves. That is, the electronic device needs to take measures when the communication antenna receives a strong electromagnetic wave such as an electromagnetic wave emitted from a charging power transmission coil.

On the other hand, in Patent Document 1, as a second embodiment, a switch that disconnects a proximity non-contact communication antenna (for charging) and a non-contact power receiving coil from each circuit is operated using a competition control unit, and communication is performed. And either one of the circuits and the coil or the antenna are alternatively connected at the time of charging. Although the circuit configuration can prevent malfunction due to each electromagnetic wave, it is insufficient as a countermeasure for the above-mentioned problems.
For example, in order to operate the contention control unit, electric power for operating the contention control unit and the changeover switch is necessary, and if the secondary battery as described in Patent Document 1 is in an overdischarged state, Without operating the contention control unit and the changeover switch, the electromagnetic wave for charging is received from the communication antenna without any countermeasure. Further, when the charging coil is disconnected, there is a problem that stronger electromagnetic energy is received by the communication antenna. Further, in the flow of operation described in Patent Document 1, it is necessary to always start from charging, and it is impossible to realize an original operation such as “charging for an authenticated partner for charging”. Further, there is a possibility of damaging the IC chip during charging before authentication.
Moreover, the communication antenna and IC chip part of a non-contact communication part also have the subject which causes deterioration of communication performance by the resistance component, capacitance, and inductance connected in series. In other words, the resistance component of the switch for connecting and disconnecting the communication antenna and the frequency characteristics as a circuit become a problem.

  An object of the present invention is to provide a non-contact charging system that protects a non-contact communication circuit from undesired power induced in a communication antenna without degrading communication performance.

  In order to solve the above-described problems, a non-contact charging system according to the present invention is a non-contact charging system that transmits and receives power using electromagnetic induction and can exchange information by non-contact communication, An antenna element that receives a non-contact communication signal using electromagnetic induction from a power transmission-side apparatus, an IC chip that operates by identifying the non-contact communication signal received through the antenna element, and the antenna element A switch that electrically connects an electronic element that changes the resonance frequency band of the IC chip in parallel with the IC chip, and an input power from a receiving coil that receives an electromagnetic wave used for charging using electromagnetic induction from the power transmission side device. An electromagnetic wave detection unit that passively switches the switch using the input power when exceeding a predetermined value, and receiving an electromagnetic wave exceeding a predetermined value from the power receiving coil During, and wherein reducing the voltage induced in the IC chip by changing the resonant frequency in the communication resonance frequency band of the antenna element.

  ADVANTAGE OF THE INVENTION According to this invention, the IC chip used for non-contact communication can be protected from the electric power of the magnitude | size induced by the communication antenna at the time of charge, etc., without deterioration of communication performance. Further, the switch used for protecting the IC chip can be operated without depending on the power from the secondary battery to be charged provided in the electronic device on the power receiving side.

It is a block diagram which shows the non-contact charge system of embodiment of this invention. It is explanatory drawing which showed the change relationship of the resonant frequency and induced voltage of embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings. Note that the description of the configuration that is not related to the present invention is simplified or omitted.

FIG. 1 is a configuration diagram showing a contactless charging system according to an embodiment of the present invention.
The contactless charging system according to the present embodiment mainly includes a power transmission side device 1 that transmits charging power and a power reception side device 2 that charges the secondary battery 18 with the power transmitted from the power transmission side device 1.

  The power transmission side device 1 includes a communication antenna (communication coil) 6 and a communication circuit 4 for non-contact communication, a power transmission coil 7 and a power transmission circuit 5 for transmitting charging power, and a control unit 3 for controlling the communication circuit 4 and the power transmission circuit 5. Consists of.

  In order to charge the secondary battery 18, the power receiving side device 2 receives a power receiving coil 9, a smoothing circuit 15 that smoothes the power received by the power receiving coil 9, and the smoothed power energy into a voltage , An electromagnetic wave detection unit 16 that detects current or a combination of voltage and current, and a control unit 17 that controls charging of the secondary battery 18.

The electromagnetic wave detection unit 16 passively switches the switch 13 using the received power energy when it exceeds the predetermined power energy. The predetermined value is set to a value higher than the power received from the electromagnetic wave used for non-contact communication (electromagnetic wave that can be transmitted from the communication antenna 6) via the power receiving coil 9. Further, it is set in consideration of allowable tolerance of the IC chip 10. Moreover, it is desirable to set the initial power received from electromagnetic waves used for non-contact charging or a value lower than the initial power.
That is, the threshold is set to a value that does not exceed the power used for non-contact communication, and in addition, the received power is set not to exceed the maximum rating such as the voltage applied to the IC chip 10 of the non-contact communication unit 14. Is done.

  The power receiving side device 2 is connected in parallel with the communication antenna 8 as a non-contact communication unit 14 for non-contact communication, an IC chip 10 that operates by identifying a non-contact communication signal, and the communication antenna 8. A capacitor 11 that adjusts the resonance frequency by resonance, an electronic element 12 that is a circuit that protects the IC chip 10 from the power of strong electromagnetic waves, and a switch 13 that electrically connects the electronic element 12 to the communication antenna 8 are provided.

  The electronic element 12 is an electronic element that changes the resonance frequency band of the communication antenna 8, and a capacitor or an inductance may be used. The electronic element 12 may be provided at both ends of the switch 13.

  The switch 13 is connected in series with the electronic element 12 and is disconnected to connect the electronic element 12 in parallel to the IC chip 10. The switch 13 may be a transistor or a MOSFET as a semiconductor switch. In addition, although the operation speed is slower than that of the semiconductor switch, a contact relay of a contact point can be used.

  Note that at least one set of the electronic element 12 and the switch 13 may be provided, but a plurality of electronic elements 12 and switches 13 may be connected in parallel with the IC chip 10.

  Next, the operation of the contactless charging system of this embodiment will be described.

The non-contact communication unit 14 is normally operating normally.
If the electrical energy detected by the electromagnetic wave detection unit 16 from the power induced in the power receiving coil 9 of the power receiving side device 2 is a value that does not exceed the threshold value for operating the switch 13 of the non-contact communication unit 14, the switch 13 operates. The operation according to the present invention is not performed.

  On the other hand, when an electromagnetic wave stronger than the intensity of the electromagnetic wave used for non-contact communication reaches the receiving coil 9 for some reason, the electromagnetic wave detection unit 16 receives the power energy received through the receiving coil 9 and exceeds the threshold value. Therefore, the switch 13 immediately conducts, and the electronic element 12 is connected in parallel to the IC chip 10. That is, the resonance frequency band of the communication antenna 14 is changed from the resonance frequency during communication using the conduction of the switch 13. Due to the change in the resonance frequency, the IC chip 10 can be protected without flowing more power than expected into the non-contact communication unit 14.

  In addition, when the electromagnetic wave stronger than the intensity | strength of the electromagnetic wave used for non-contact communication has arrived at the receiving coil 9, it can be said that the possibility that the strong electromagnetic wave has reached the communication antenna 14 is high.

Next, changes in the resonance frequency will be described.
FIG. 2 shows the relationship between the resonant frequency and the induced voltage. An example in which a capacitive element is used as the electronic element 12 is shown.
(A) in a figure is a curve which shows the voltage induced in the non-contact communication part 14 at the time of non-contact communication. (B) is a curve which shows the voltage induced in the non-contact communication part 14 at the time of charge. (B) represents that the capacitive element as the electronic element 12 is added to the non-contact communication unit 14 due to conduction of the switch 13 of the non-contact communication unit 14, and the resonance frequency is lowered. At this time, the voltage induced in the non-contact communication unit 14 decreases from the value indicated by Va to the value indicated by Vb.

  As described above, according to the present embodiment, with reference to the input power from the receiving coil from the power of an undesired magnitude that should be induced in the communication antenna for non-contact communication in response to the electromagnetic wave, the power The induction is reduced by passively changing the resonance frequency of the resonance circuit including the communication antenna by using the IC, and the IC chip used for the non-contact communication can be protected from the failure without causing the deterioration of the communication performance at the time of communication.

  Further, the protection does not require the use of electric power from the secondary battery of the electronic device, and the switch used for protecting the IC chip can be operated even when the secondary battery is removed.

  Further, in the present invention, the IC chip can be protected without using the switch to disconnect the connection between the communication antenna and the IC chip. This eliminates the need to provide additional components between the communication antenna and the IC chip. That is, it is possible to exclude the deterioration of proximity non-contact communication caused by inserting a switch into the communication path, which can cause factors such as a voltage drop at the time of ON and a frequency characteristic change based on the capacitance between terminals at the time of OFF. The electromagnetic wave detection unit can also obtain the above effect without particularly affecting the efficiency of the charging circuit system.

  Next, an Example is shown and this invention is demonstrated.

The circuit configuration of this example is the same as that of the above embodiment. In this embodiment, the frequency band for non-contact communication is 13.56 MHz widely used for IC cards and the like, and the same frequency band is used for non-contact charging. The resonance frequency of the non-contact communication unit 14 at the time of non-contact communication is calculated from the inductor component of the communication coil 8, the capacitor 11 and the internal capacitance of the IC chip 10, and is designed to be around 13.56 MHz.
The communication antenna 8 and the power receiving coil 9 are overlapped. A capacitor is used for the electronic element 12 and a semiconductor switch is used for the switch 13. The electromagnetic wave detection unit 16 is configured to detect the output voltage of the smoothing circuit 15 and use a passive element so that power sufficient to drive the switch 13 reaches the switch 13 when the voltage value exceeds a predetermined value. Has been. In other words, when the output voltage of the smoothing circuit 15 exceeds a predetermined value, the electric circuit is configured so that the switch 13 is passively driven by the electric power flowing through the smoothing circuit 15 and the electromagnetic wave detection unit 16. .
Further, the power transmission side device 1 controls the control unit 3 to selectively drive the communication circuit 4 for non-contact communication and the power transmission circuit 5 that sends out the charging power.

  At the time of charging, the control unit 3 and the power transmission circuit 5 sequentially increase the output power from a predetermined initial power, and send out electromagnetic waves used for non-contact charging with a predetermined value or power specified from the electronic device side. In addition, the frequency at the time of charge is a frequency band equivalent to the frequency band used for non-contact communication as described above. And the power transmission side apparatus 1 detects the other party apparatus which should be charged (for example, refer to electromagnetic induction coupling), and after authenticating the other party apparatus (power receiving side apparatus 2) which should be charged using non-contact communication, An electromagnetic wave will be transmitted to prevent erroneous power transmission. In addition, the power receiving side device 2 (electronic device) performs authentication with the power transmitting side device 1 (charger) by the non-contact communication unit 14, and then receives the transmitted electromagnetic wave for charging by the power receiving coil 9. The secondary battery 18 is charged.

Next, the operation of the embodiment will be described.
The power transmission side device 1 starts polling of non-contact communication using an arbitrary protocol in order to authenticate a partner to be charged. When the power receiving side device 2 to be charged enters the non-contact communication range, authentication is performed between the non-contact communication unit 14 and the control unit 3 of the power transmission side device 1.
At this time, the voltage detected by the electromagnetic wave detection unit 16 from the power induced in the power receiving coil 9 of the power receiving device 2 is set to a value that does not exceed the threshold for operating the switch 13 with the power of non-contact communication. Therefore, it does not exceed. Therefore, the non-contact communication part 14 can perform authentication correctly, maintaining communication quality using the designed frequency body. After the authentication is correctly performed, the power transmission side device 1 starts transmitting the charging power according to the result of the authentication operation. The threshold value set as the electromagnetic wave detection unit 16 is a value at which the voltage applied to the IC chip 10 of the non-contact communication unit 14 does not exceed the maximum rated voltage of the IC chip 10.

When the charging side device 1 starts transmitting the charging power, the power receiving side device 2 receives the power transmitted from the power transmission coil 7 of the power transmission side device 1 via the power receiving coil 9 and is smoothed by the smoothing circuit 15. Is charged to the secondary battery based on the charging control of the control unit 17. In parallel with this, the voltage detected by the electromagnetic wave detection unit 16 exceeds the operation threshold value of the switch 13 by the arrival of the strong electromagnetic wave to the power receiving coil 9.
At this time, the resonance frequency of the non-contact communication unit 14 at the time of non-contact communication is instantaneously determined by the capacitance of the capacitor as the electronic element 12 in addition to the inductor component of the communication coil 8 and the capacitor 11 and the internal capacitance of the IC chip 10. As shown in FIG. 2, the frequency shifts to a frequency lower than 13.56 MHz.
Therefore, even if a high voltage assumed by the charging power is induced in the power receiving coil 9, a high voltage is not induced in the non-contact communication unit 14, and a failure of the IC chip 10 due to the charging electromagnetic wave is caused. Can be prevented.

  When the switch 13 of the non-contact communication unit 14 is turned on to add a capacitor capacity to the non-contact communication unit 14 and the resonance frequency is lowered, the voltage induced at 13.56 MHz is changed from Va to Vb in FIG. It falls like this. For example, if the Q of the communication coil is about 30, when the resonance frequency is shifted from 13.56 MHz to about 5 MHz, the induced voltage value can be reduced to about 1/20.

  Further, according to the present embodiment, even when the secondary battery of the power receiving device is in an overdischarged state, the power for operating the switch 13 can be secured, and the IC of the non-contact communication unit 14 can be obtained from the large power during charging. The chip 10 can be appropriately protected.

  The present invention is suitable for a system that authenticates an object to be charged by non-contact communication and performs non-contact charging by configuring the non-contact charging system described above. In addition, it is possible to construct a non-contact charging system in which an electronic device whose secondary battery is dead is charged only after charging without first temporarily charging an electronic device whose secondary battery is dead.

DESCRIPTION OF SYMBOLS 1 Power transmission side apparatus 2 Power receiving side apparatus 3 Control part (for charge)
17 Control unit (for charging)
4 communication circuit 5 power transmission circuit 6, 8 communication coil 7 power transmission coil 9 power reception coil 10 IC chip 11 capacitor 12 electronic element (capacitive or dielectric)
13 Switch 14 Non-contact communication unit 15 Smoothing circuit 16 Electromagnetic wave detection unit (voltage detection unit, power detection unit, current detection unit)
18 Secondary battery (battery)

Claims (8)

A non-contact charging system that transmits and receives power using electromagnetic induction and can exchange information by non-contact communication,
In the receiving device,
An antenna element that receives a non-contact communication signal using electromagnetic induction from the power transmission side device; an IC chip that operates by identifying the non-contact communication signal received via the antenna element;
A switch for electrically connecting an electronic element for changing a resonance frequency band of the antenna element in parallel with the IC chip;
An electromagnetic wave detection unit that receives input power from a receiving coil that receives electromagnetic waves used for charging using electromagnetic induction from the power transmission side device and passively switches the switch using the input power when the input power exceeds a predetermined value And
While receiving an electromagnetic wave exceeding a predetermined value from the power receiving coil, a voltage induced in the IC chip is reduced by changing a resonance frequency band of the antenna element from a resonance frequency during communication. Contact charging system. The contactless charging system according to claim 1,
The said electromagnetic wave detection part sets the said predetermined value to the value higher than the electric power received from the electromagnetic waves used for non-contact communication, The non-contact charge system characterized by the above-mentioned. The contactless charging system according to claim 2,
The said electromagnetic wave detection part sets the said predetermined value to the initial power received from the electromagnetic waves used for non-contact charge, or a value lower than initial power, The non-contact charge system characterized by the above-mentioned. The contactless charging system according to claim 3,
The non-contact charging system, wherein the electronic element that changes the resonance frequency band of the antenna element is a capacitor or an inductance. The contactless charging system according to claim 4,
The non-contact charging system, wherein a frequency at the time of charging is equal to a frequency band used for the non-contact communication. The contactless charging system according to claim 5,
The power transmission side device is:
A non-contact charging system comprising a control unit that selectively controls a power transmission circuit that transmits electromagnetic waves for charging and a communication circuit that transmits and receives electromagnetic waves for non-contact communication. An electronic device that can perform non-contact charging of electric power using electromagnetic induction and can exchange information by non-contact communication,
At least having an IC chip used for non-contact communication and a communication coil connected to the IC chip,
At least one set of switches, and a capacitor connected in series with the switches, a non-contact communication unit connected in parallel with the IC chip,
A voltage detection unit that detects a voltage obtained by smoothing the electric power received by the power reception coil and switches the switch so as to connect the capacitor in parallel with the IC chip based on the detected voltage; Electronic equipment characterized by A method of protecting a non-contact communication circuit provided in an electronic device capable of receiving power using electromagnetic induction and performing non-contact charging capable of receiving and transmitting information by non-contact communication,
Electronic equipment,
An antenna element that receives a non-contact communication signal using electromagnetic induction, and an IC chip that operates by identifying the non-contact communication signal received from the antenna element, a resonance frequency band of the antenna element is set in parallel with the IC chip. Connect the electronic elements to be changed via a switch,
When the input power from the power receiving coil that receives the electromagnetic wave used for charging using electromagnetic induction exceeds a predetermined value, the switch is electrically connected to the electronic device passively using the input power. Switch to
While receiving an electromagnetic wave exceeding a predetermined value from the power receiving coil, a voltage induced in the IC chip is reduced by changing a resonance frequency band of the antenna element from a resonance frequency during communication. Contact communication circuit protection method.

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