Short-range wireless communication device

Abstract

A short-range wireless communication device (10) comprises: a coil (20); a capacitor (31); a short-range wireless communication IC (40); and a rectification circuit (50). The short-range wireless communication IC (40) and the rectification circuit (50) are connected through a node (ND) to the coil (20). The capacitor (31) is connected between the node (ND) and the rectification circuit (50). The coil (20) constitutes a reception circuit (101), and the coil (20) and the capacitor (31) constitute a power reception circuit (102). By appropriately setting capacitance of the capacitor (31), the output impedance (Zo101) of the reception circuit (101) is set larger than the output impedance (Zo102) of the power reception circuit (102) at a communication frequency (fc), and the output impedance (Zo102) of the power reception circuit (102) is set smaller than the output impedance (Zo101) of the reception circuit (101) at a power reception frequency (fp).

Description

Technical Field

[0001] The present invention relates to a short - range wireless communication device that performs short - range wireless communication and power reception.

Background Art

[0002] Non - contact charging modules are described in Patent Documents 1 - 4. The non - contact charging modules of Patent Documents 1 - 4 have a wireless communication function. The non - contact charging modules of Patent Documents 1 - 4 individually include a coil for charging (power reception) and an antenna for wireless communication.

[0003] A passive RFID device is described in Patent Document 5. The passive RFID device of Patent Document 5 has a power reception function. The passive RFID device of Patent Document 5 uses an antenna that performs wireless communication to execute power reception. The passive RFID device of Patent Document 5 includes a switch. The passive RFID described in Patent Document 5 switches between wireless communication and power reception by switching the switch.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the configurations of Patent Documents 1-4, since the charging (power receiving) coil and the antenna for wireless communication are separate, the number of components of the device increases, making miniaturization difficult. In the configuration of Patent Document 5, wireless communication and power reception cannot be executed in parallel.

[0006] Therefore, an object of the present invention is to provide a short-range wireless communication device that can execute wireless communication and power reception in parallel using a common coil for both wireless communication and power reception, and can efficiently execute each of them.

Means for Solving the Problems

[0007] A short-range wireless communication device having a power receiving function, which is an aspect of the present invention, includes a power receiving coil, a power receiving resonance circuit, a wireless communication circuit, and a load circuit. The power receiving coil shares power reception in power supply using short-range wireless and reception in wireless communication of data using short-range wireless. The power receiving resonance circuit forms a resonance circuit with the power receiving coil and one or more resonance capacitors. The wireless communication circuit and the load circuit are electrically connected to the power receiving resonance circuit respectively, and the load circuit performs work using the received electricity.

[0008] The power receiving resonance circuit includes a receiving circuit and a power receiving circuit. The receiving circuit supplies a communication voltage from the power receiving coil to the wireless communication circuit. The power receiving circuit supplies a power receiving current from the power receiving coil to the load circuit.

[0009] At the communication frequency for performing wireless communication, the wireless communication output impedance from the receiving circuit to the wireless communication circuit is larger than the power receiving output impedance from the power receiving circuit to the load circuit. At the power receiving frequency for performing power reception, the power receiving output impedance is smaller than the wireless communication output impedance.

[0010] In this configuration, at the power receiving frequency, since the output impedance of the power receiving circuit is smaller than the output impedance of the receiving circuit, the current due to power reception is stably supplied to the load circuit at a predetermined level or higher.

[0011] On one hand, at the communication frequency, since the output impedance of the receiving circuit is larger than that of the power receiving circuit, the Q of resonance at the communication frequency by the receiving circuit and the wireless communication circuit can be set large. As a result, the load modulation level by switching the resonance state executed in the wireless communication circuit becomes large.

Advantages of the Invention

[0012] According to this invention, wireless communication and power reception can be performed in parallel using a common coil for both wireless communication and power reception, and each can be efficiently executed, and the components of the device can be reduced to achieve miniaturization.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

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Figure 16

[0014] [First Embodiment] A short-range wireless communication device according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of the short-range wireless communication device according to the first embodiment.

[0015] As shown in FIG. 1, the short-range wireless communication device 10 includes a coil 20, a capacitor 31, a short-range wireless communication IC 40, a rectifier circuit 50, and a load circuit 60. The coil 20 corresponds to the "power receiving coil" of the present invention, the capacitor 31 corresponds to the "resonance capacitor" of the present invention, and the short-range wireless communication IC 40 corresponds to the "wireless communication circuit" of the present invention. Also, a component configuration including the rectifier circuit 50 and the load circuit 60 corresponds to the "load circuit" of the present invention.

[0016] The coil 20 is, for example, a loop coil. Both ends of the coil 20 are connected to the short-range wireless communication IC 40. Also, both ends of the coil 20 are connected to the rectifier circuit 50. The coil 20 corresponds to the "power receiving coil" of the present invention.

[0017] The circuit connecting the short - range wireless communication IC40 and the coil 20 and the circuit connecting the rectifier circuit 50 and the coil 20 include the node ND.

[0018] The capacitor 31 is connected in series between one end of the coil 20 and the rectifier circuit 50. At this time, the capacitor 31 is connected on the rectifier - circuit - 50 side rather than the node ND side.

[0019] The short - range wireless communication IC40 and the rectifier circuit 50 are connected to the load circuit 60.

[0020] The short - range wireless communication IC40 is, for example, what is called an NFC IC and performs communication using the coil 20.

[0021] The rectifier circuit 50 rectifies the current and voltage consisting of an alternating current of a predetermined frequency received by the coil 20 and converts it into direct current, and outputs it to the load circuit 60. The load circuit 60 performs a predetermined circuit operation according to the output voltage and output current of the rectifier circuit 50. An example of a specific circuit operation of the load circuit 60 will be described later.

[0022] FIG. 2 is a functional block diagram showing the configuration of the short - range wireless communication system according to the first embodiment. As shown in FIG. 2, the short - range wireless communication system 1 includes a transmission device 90 and a short - range wireless communication device 10.

[0023] The transmission device 90 includes a voltage conversion circuit 91, a transmission control circuit 92, and a coil 900. The voltage conversion circuit 91 converts the voltage level of the input voltage from the external power supply 99 and supplies it to the transmission control circuit 92. The transmission control circuit 92 converts the DC voltage supplied from the voltage conversion circuit 91 into an AC voltage of a predetermined frequency and applies it to the coil 900. At this time, the predetermined frequency is, for example, 13.56 MHz in the ISM band. Note that this frequency is an example, and other frequencies may be used.

[0024] The coil 900 is, for example, a loop coil. The coil 900 passes an alternating current corresponding to the applied AC voltage and generates an alternating magnetic field.

[0025] The short - range wireless communication device 10 is arranged such that the coil 20 is coupled to the alternating magnetic field generated by the coil 900. Thereby, the coil 20 induces electromagnetic induction with the alternating magnetic field generated by the coil 900 to generate an alternating current. The current generated in the coil 20 is output to the short - range wireless communication IC 40 and the rectifier circuit 50.

[0026] Here, the capacitor 31 constitutes a series resonance circuit with the coil 20. The resonance frequency of the series resonance circuit of the coil 20 and the capacitor 31 is set to the above - mentioned predetermined frequency (for example, 13.56 MHz in the ISM band). Thereby, a magnetic resonance state using the coil 20 and the coil 900 can be realized, and the rectifier circuit 50 is supplied with the received current with low loss. Therefore, power reception with low loss and high efficiency becomes possible. In this way, the power reception circuit 102 is constituted by the coil 20 and the capacitor 31.

[0027] On the other hand, the short - range wireless communication IC 40 can switch the state of its own impedance. Thereby, the Q of resonance of the circuit formed by the coil 20 and the short - range wireless communication IC 40 can be switched.

[0028] FIG. 3(A) and FIG. 3(B) are diagrams for conceptually explaining communication using the short - range wireless communication IC. FIG. 3(A) shows a state where the Q of resonance is high, and FIG. 3(B) shows a state where the Q of resonance is low. FIG. 4 is a conceptual diagram showing the change state of the Q of resonance, where the horizontal axis represents frequency and the vertical axis represents the current value flowing through the reception circuit.

[0029] As shown in FIG. 3(A) and FIG. 3(B), the short - range wireless communication IC 40 includes a parallel circuit of a capacitor C40 and a switch SW40. Note that the short - range wireless communication IC 40 is not limited to this configuration and has other circuit configurations, but as the minimum configuration for adjusting the Q of resonance, it has the configuration shown in FIG. 3(A) and FIG. 3(B).

[0030] In the first state, as shown in FIG. 3(A), the short-range wireless communication IC 40 opens the switch SW40 (sets it to the off state). In this state, a parallel circuit of the open resistance R40off of the switch SW40 and the capacitor C40 is formed in the short-range wireless communication IC 40. Since the open resistance R40off is very large, the current flowing from the coil 20 to the short-range wireless communication IC 40 flows into the capacitor C40 of the short-range wireless communication IC 40. As a result, a resonance circuit composed of the coil 20 and the capacitor C40 is formed. And since the resonance circuit is composed only of the coil 20 and the capacitor C40, the Q of the resonance becomes high (see the solid line in FIG. 4).

[0031] In the second state, as shown in FIG. 3(B), the short-range wireless communication IC 40 closes the switch SW40 (sets it to the on state). In this state, a parallel circuit of the conduction resistance R40on of the switch SW40 and the capacitor C40 is formed in the short-range wireless communication IC 40. Since the conduction resistance R40on is very small, the current flowing from the coil 20 to the short-range wireless communication IC 40 mainly flows into the conduction resistance R40on of the short-range wireless communication IC 40. Therefore, a resonance circuit composed only of the coil 20 and the capacitor C40 cannot be realized, and the Q of the resonance becomes low (see the dashed line in FIG. 4). As a result, the circuit composed of the coil 20 and the short-range wireless communication IC 40 can switch the Q of the resonance.

[0032] By switching the Q of this resonance, the short-range wireless communication device 10 realizes load modulation. That is, the short-range wireless communication device 10 switches the coupling state between the coil 20 and the coil 900 by switching the Q of the resonance. At this time, as shown by the dashed arrows in FIGS. 3(A) and 3(B), a stable current flows through the power receiving circuit 102 without depending on the resonance state of the receiving circuit 101 and the short-range wireless communication IC 40 (details will be described later).

[0033] The transmission control circuit 92 of the transmission device 90 includes a voltage monitoring unit (not shown). The voltage monitoring unit monitors the input voltage of the coil 900. Here, as described above, when the coupling state between the coil 20 and the coil 900 changes due to the switching of the resonance Q by the short-range wireless communication device 10, the input voltage of the coil 900 changes accordingly.

[0034] FIG. 5(A) and FIG. 5(B) are waveform diagrams showing an example of the input voltage. FIG. 5(A) shows the case of the present invention, and FIG. 5(B) shows the case of a comparative example. The comparative example is, for example, an example in which the parameter settings of the specific receiving circuit 101 of the present invention described later are not performed.

[0035] In the open state (off state) of the switch SW40, the resonance Q is high, the coil 20 and the coil 900 are in a resonant state, and as shown in FIG. 5(A), the amplitude of the input voltage Voff becomes large. When the switch SW40 is in the conducting state (on state), the resonance Q is low, the coupling degree between the coil 20 and the coil 900 decreases, the current flowing through the coil 900 decreases, and the amplitude of the input voltage Von becomes small. Thus, the input voltage of the coil 900 changes according to the change between the open state and the conducting state of the switch SW40, that is, the state transition. The voltage monitoring unit detects this change in the input voltage.

[0036] When the short-range wireless communication device 10 performs data communication with the transmission device 90, it associates the bits of the communication data with the change in the resonance Q. The transmission device 90 can demodulate the bits of the communication data by detecting the change in the input voltage of the coil 900.

[0037] Thereby, the short-range wireless communication device 10 and the transmission device 90 can realize the transmission and reception of communication data, that is, wireless communication, by using the electromagnetic induction between the coil 900 and the coil 20. Thus, the receiving circuit 101 is constituted by the coil 20. And the "power receiving resonance circuit" of the present invention is constituted by this receiving circuit 101 and the above-described power receiving circuit 102.

[0038] In such a short-range wireless communication device 10 and short-range wireless communication system 1, the short-range wireless communication device 10 further has the following characteristics.

[0039] At the above-mentioned predetermined frequencies, in other words, at the power reception frequency fp and the communication frequency fc, the output impedance Zo102 of the power reception circuit 102 is smaller than the output impedance Zo101 of the reception circuit 101. Conversely, the output impedance Zo101 of the reception circuit 101 is larger than the output impedance Zo102 of the power reception circuit 102.

[0040] More specifically, at the power reception frequency fp, the output impedance Zo102 of the power reception circuit 102 is smaller than the output impedance Zo101 of the reception circuit 101. Further, at the communication frequency fc, the output impedance Zo101 of the reception circuit 101 is larger than the output impedance Zo102 of the power reception circuit 102.

[0041] Here, the output impedance Zo101 of the reception circuit 101 is the impedance of the output terminal from the reception circuit 101 to the short-range wireless communication IC 40. Also, the output impedance Zo102 of the power reception circuit 102 is the impedance of the output terminal from the power reception circuit 102 to the rectifier circuit 50.

[0042] FIG. 6 is a graph showing an example of the frequency characteristics of the output impedance.

[0043] The reception circuit 101 is composed of the coil 20. Therefore, as shown in FIG. 6, the output impedance Zo101 of the reception circuit 101 increases as the frequency increases.

[0044] The power reception circuit 102 is composed of a series resonance circuit of the coil 20 and the capacitor 31, and is set so that the resonance frequency coincides with the communication frequency fc and the power reception frequency fp. Therefore, as shown in FIG. 6, the output impedance Zo102 of the power reception circuit 102 changes to be minimized at the communication frequency fc and the power reception frequency fp.

[0045] Here, by appropriately setting the capacitance of the capacitor 31, as shown in FIG. 6, at the communication frequency fc and the power reception frequency fp, the output impedance Zo102 of the power reception circuit 102 can be made smaller than the output impedance Zo101 of the reception circuit 101. Conversely, in other words, the output impedance Zo101 of the reception circuit 101 can be made larger than the output impedance Zo102 of the power reception circuit 102.

[0046] With such a configuration, at the power reception frequency fp, the current output from the coil 20 mainly flows as a power reception current to the power reception circuit 102 and is supplied to the rectifier circuit 50. At this time, the output impedance Zo102 of the power reception circuit 102 is small (low).

[0047] Thereby, the loss in the power reception circuit 102 is suppressed, and the power reception current is supplied to the rectifier circuit 50 with low loss. Thereby, the short-range wireless communication device 10 can achieve excellent power reception characteristics.

[0048] Furthermore, with such a configuration, at the communication frequency fc, the Q of the resonance between the coil 20 and the short-range wireless communication IC 40 can be appropriately set.

[0049] More specifically, the output impedance Zo101 of the reception circuit 101 can be made larger, rather than being made smaller to the extent of the output impedance Zo102 of the power reception circuit 102. Thereby, the resonance state at the communication frequency fc can be appropriately set.

[0050] That is, according to the capacitor or the like of the short-range wireless communication IC 40, the inductance of the coil 20 can be set so as to obtain a high Q of resonance at the communication frequency fc. Thereby, the short-range wireless communication device 10 can appropriately set a state with a high Q of resonance and a state with a low Q of resonance between the reception circuit 101 and the short-range wireless communication IC 40 at the communication frequency fc as shown in FIG. 4. Therefore, the short-range wireless communication device 10 can achieve excellent communication characteristics. More specifically, the short-range wireless communication device 10 can achieve a high load modulation level.

[0051] At this time, it is preferable that the short-range wireless communication device 10 appropriately sets the inductance of the coil 20 so that the change rate of the impedance of the receiving circuit 101 in load modulation is 30% or more, and more preferably about 50%. Thereby, the short-range wireless communication device 10 can achieve more excellent communication characteristics.

[0052] As described above, by having the above-described configuration, the short-range wireless communication device 10 can perform power reception and reception (communication) in parallel using only the coil 20. Thereby, the short-range wireless communication device 10 can reduce the number of components of the device and achieve miniaturization. Further, the short-range wireless communication device 10 can individually set the power reception characteristics and the communication characteristics, and can achieve both excellent power reception characteristics and excellent communication characteristics.

[0053] (An example of the application of the load circuit 60) FIG. 7 is a functional block diagram showing a configuration example of a short-range wireless communication device including an example of a load circuit. In FIG. 7, the description of the portions other than the load circuit 60 in the short-range wireless communication device 10 has been described above, and new descriptions of these portions are omitted.

[0054] As shown in FIG. 7, the load circuit 60 includes a voltage conversion circuit 61, a charging circuit 62, a secondary battery 63, a voltage conversion circuit 64, a charge control circuit 620, and a discharge control circuit 640.

[0055] The voltage conversion circuit 61 converts the voltage level of the output voltage of the rectifier circuit 50. The voltage conversion circuit 61 outputs the converted voltage to the charging circuit 62.

[0056] The charging circuit 62 generates a charging voltage from the DC voltage from the voltage conversion circuit 61 and charges the secondary battery 63. At this time, the charging circuit 62 outputs a charging voltage in accordance with a charging control signal from the charge control circuit 620. The charge control circuit 620 generates a charging control signal by referring to, for example, a charging instruction from the short-range wireless communication IC 40. Note that the charging circuit 62 can also output the charging voltage to the voltage conversion circuit 64.

[0057] The voltage conversion circuit 64 converts the voltage level of the output voltage from the charging circuit 62 or the secondary battery 63 to the voltage level for the short-range wireless communication IC 40. The voltage conversion circuit 64 supplies the converted voltage to the short-range wireless communication IC 40. At this time, the voltage conversion circuit 64 supplies the converted voltage to the short-range wireless communication IC 40 in accordance with a discharge control signal (power supply control signal) from the discharge control circuit 640. Note that the discharge control circuit 640 generates a discharge control signal (power supply control signal) by referring to, for example, a charging instruction from the short-range wireless communication IC 40 and a monitoring state of the voltage level at a predetermined location of the load circuit 60.

[0058] (An example of the structure of the short-range wireless communication device 10) FIG. 8 is a side cross-sectional view showing an example of the structure of the short-range wireless communication device of the present invention. As shown in FIG. 8, the short-range wireless communication device 10 includes a support substrate 11, a magnetic sheet 12, a coil 20, an electronic component 191, and an electronic component 192. In FIG. 8, one electronic component 191 and one electronic component 192 are shown, but the electronic component 191 and the electronic component 192 exist in a number that can form the circuit of the short-range wireless communication device 10.

[0059] The support substrate 11 is a flat plate or a flat film, mainly made of an insulating material, and a conductor pattern for realizing the circuit of the short-range wireless communication device 10 is formed thereon.

[0060] The coil 20 is composed of a wound linear conductor pattern having a predetermined number of turns. The coil 20 is formed on one main surface of the support substrate 11. The magnetic sheet 12 is disposed on one main surface of the support substrate 11 so as to include the formation region of the coil 20.

[0061] The electronic component 191 is an electronic component having solder bumps formed on the mounting surface. The electronic component 192 is an electronic component having terminal electrodes at both ends of the housing. The electronic component 191 is, for example, the short-range wireless communication IC 40, the IC of the rectifying circuit 50, and the IC of the load circuit 60. The electronic component 192 is, for example, the capacitor 31, various passive elements of the rectifying circuit 50, and various passive elements of the load circuit 60.

[0062] The electronic component 191 and the electronic component 192 are mounted on one main surface of the support substrate 11. Note that at least a part of the electronic component 191 and the electronic component 192 may be mounted on the other main surface of the support substrate 11.

[0063] With such a configuration, the short-range wireless communication device 10 can be formed in a thin shape. Further, by providing the magnetic sheet 12, the magnetic flux density of the coil 20 can be increased. Thereby, the short-range wireless communication device 10 can increase the power reception energy and the communication energy.

[0064] Note that the load circuit 60 does not necessarily include the secondary battery 63. However, by providing the secondary battery 63, the short-range wireless communication device 10 can store energy and realize stable operations of the short-range wireless communication IC 40, the load circuit 60, and the like.

[0065] [Second Embodiment] A short-range wireless communication device according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 9 is a functional block diagram showing the configuration of the short-range wireless communication device according to the second embodiment. FIGS. 10(A) and 10(B) are diagrams for conceptually explaining communication using a short-range wireless communication IC. FIG. 10(A) shows a state where the Q of resonance is high, and FIG. 10(B) shows a state where the Q of resonance is low.

[0066] As shown in FIG. 9, the short-range wireless communication device 10A according to the second embodiment is different from the short-range wireless communication device 10 according to the first embodiment in that it includes a reception circuit 101A and a power reception circuit 102A. Other configurations of the short-range wireless communication device 10A are the same as those of the short-range wireless communication device 10, and descriptions of the same parts are omitted.

[0067] The reception circuit 101A includes a coil 20 and a capacitor 71. The coil 20 and the capacitor 71 are connected in parallel.

[0068] The power receiving circuit 102A includes a coil 20, a capacitor 71, and a capacitor 31A. The parallel circuit of the coil 20 and the capacitor 71 is common to the receiving circuit 101A. The capacitor 31A is serially connected between the node ND and the rectifying circuit 50.

[0069] In such a configuration, the output impedance Zo101A of the receiving circuit 101A is set by the parallel circuit of the coil 20 and the capacitor 71. The output impedance Zo102A of the power receiving circuit 102A is set by the parallel circuit of the coil 20 and the capacitor 71 and the capacitor 31A.

[0070] Then, by appropriately setting the capacitance of the capacitor 71 and the capacitance of the capacitor 31A, at the communication frequency fc, the output impedance Zo101A of the receiving circuit 101A can be set to be larger than the output impedance Zo102A of the power receiving circuit 102A, and at the power receiving frequency fp, the output impedance Zo102A of the power receiving circuit 102A can be set to be smaller than the output impedance Zo101A of the receiving circuit 101A.

[0071] At the communication frequency fc, since the output impedance Zo101A of the receiving circuit 101A is larger than the output impedance Zo102A of the power receiving circuit 102A, the short-range wireless communication device 10A switches the current path for communication as shown in FIGS. 10(A) and 10(B), and similar to the short-range wireless communication device 10 of the first embodiment, increases the difference in the Q of resonance and can realize a desired load modulation level.

[0072] At the power receiving frequency fp, since the output impedance Zo102A of the power receiving circuit 102A is smaller than the output impedance Zo101A of the receiving circuit 101A, a current at a level sufficient for power supply can be supplied with low loss from the power receiving circuit 102A to the rectifying circuit 50 and the load circuit 60.

[0073] As a result, the short-range wireless communication device 10A can perform power reception and communication in parallel, can individually set the power reception characteristics and the communication characteristics, and can achieve both excellent power reception characteristics and excellent communication characteristics.

[0074] Furthermore, in the short-range wireless communication device 10A, by providing the capacitor 71, impedance matching between the coil 20 and the short-range wireless communication IC 40 can be achieved without changing the inductance of the coil 20 and the capacitance of the short-range wireless communication IC 40, etc. As a result, the short-range wireless communication device 10A can achieve a high resonance Q for communication while suppressing transmission loss.

[0075] [Third Embodiment] The short-range wireless communication device according to the third embodiment of the present invention will be described with reference to the drawings. FIG. 11 is a functional block diagram showing the configuration of the short-range wireless communication device according to the third embodiment. FIGS. 12(A) and 12(B) are diagrams for conceptually explaining communication using a short-range wireless communication IC. FIG. 12(A) shows a state where the resonance Q is high, and FIG. 12(B) shows a state where the resonance Q is low.

[0076] As shown in FIG. 11, the short-range wireless communication device 10A according to the third embodiment is different from the short-range wireless communication device 10A according to the second embodiment in that it includes a reception circuit 101B and a power reception circuit 102B. Other configurations of the short-range wireless communication device 10B are the same as those of the short-range wireless communication device 10A, and descriptions of the same parts will be omitted.

[0077] The reception circuit 101B includes a coil 20, a capacitor 71, and a capacitor 72. The capacitor 72 is connected to one end of the coil 20 and one end of the capacitor 71, and the connection point between the capacitor 72 and the capacitor 71 (the node between the capacitors) is connected to one node ND. The connection point between the other end of the coil 20 and the other end of the capacitor 71 (the node between the coil 20 and the capacitor 71) is connected to the other node ND.

[0078] The power receiving circuit 102B includes a coil 20, a capacitor 71, a capacitor 72, and a capacitor 31B. The circuit composed of the coil 20, the capacitor 71, and the capacitor 72 is common to the receiving circuit 101B. The capacitor 31B is serially connected between the node ND and the rectifying circuit 50.

[0079] In such a configuration, the output impedance Zo101B of the receiving circuit 101B is set by the circuit composed of the coil 20, the capacitor 71, and the capacitor 72. The output impedance Zo102B of the power receiving circuit 102B is set by the circuit composed of the coil 20, the capacitor 71, the capacitor 72, and the capacitor 31B.

[0080] Then, by appropriately setting the capacitance of the capacitor 71, the capacitance of the capacitor 72, and the capacitance of the capacitor 31B, at the communication frequency fc, the output impedance Zo101B of the receiving circuit 101B can be set to be larger than the output impedance Zo102B of the power receiving circuit 102B, and at the power receiving frequency fp, the output impedance Zo102B of the power receiving circuit 102B can be set to be smaller than the output impedance Zo101B of the receiving circuit 101B.

[0081] At the communication frequency fc, since the output impedance Zo101B of the receiving circuit 101B is larger than the output impedance Zo102B of the power receiving circuit 102B, the short-range wireless communication device 10B switches the current path for communication as shown in FIGS. 12(A) and 12(B), and similar to the short-range wireless communication devices 10 and 10A of the first and second embodiments, the difference in the Q of resonance can be increased, and a desired load modulation level can be realized.

[0082] At the power receiving frequency fp, since the output impedance Zo102B of the power receiving circuit 102B is smaller than the output impedance Zo101B of the receiving circuit 101B, a current at a level sufficient for power supply can be supplied to the rectifying circuit 50 and the load circuit 60 from the power receiving circuit 102B with low loss.

[0083] As a result, the short-range wireless communication device 10B can perform power reception and communication in parallel, can individually set the power reception characteristics and the communication characteristics, and can achieve both excellent power reception characteristics and excellent communication characteristics.

[0084] Furthermore, in the short-range wireless communication device 10B, by providing the capacitor 71 and the capacitor 72, impedance matching between the coil 20 and the short-range wireless communication IC 40 can be achieved without changing the inductance of the coil 20 and the capacitance of the short-range wireless communication IC 40. As a result, the short-range wireless communication device 10B can achieve a high resonance Q for communication while suppressing transmission loss.

[0085] [Fourth Embodiment] A short-range wireless communication device according to a fourth embodiment of the present invention will be described with reference to the drawings. FIG. 13 is a functional block diagram showing the configuration of the short-range wireless communication device according to the fourth embodiment. FIGS. 14(A) and 14(B) are diagrams for conceptually explaining communication using a short-range wireless communication IC. FIG. 14(A) shows a state where the resonance Q is high, and FIG. 14(B) shows a state where the resonance Q is low.

[0086] As shown in FIG. 13, the short-range wireless communication device 10C according to the fourth embodiment is different from the short-range wireless communication device 10 according to the first embodiment in that it includes a reception circuit 101C and a power reception circuit 102C. Other configurations of the short-range wireless communication device 10C are the same as those of the short-range wireless communication device 10, and descriptions of the same parts are omitted.

[0087] The reception circuit 101C includes a coil 20 and a capacitor 32C. The coil 20 and the capacitor 32C are connected in series. The capacitor 32C is connected in series between the node ND and the short-range wireless communication IC 40. The capacitor 32C corresponds to the "second resonance capacitor" of the present invention.

[0088] The power receiving circuit 102C includes a coil 20 and a capacitor 31C. The coil 20 is common to the receiving circuit 101C. The capacitor 31C is serially connected between the node ND and the rectifying circuit 50. The capacitor 31C corresponds to the "first resonant capacitor" of the present invention.

[0089] In such a configuration, the output impedance Zo101C of the receiving circuit 101C is set by the series circuit of the coil 20 and the capacitor 32C. The output impedance Zo102C of the power receiving circuit 102C is set by the series circuit of the coil 20 and the capacitor 31C.

[0090] And by setting the capacitance of the capacitor 31C to be larger than the capacitance of the capacitor 32C, at the communication frequency fc, the output impedance Zo101C of the receiving circuit 101C can be set to be larger than the output impedance Zo102C of the power receiving circuit 102C, and at the power receiving frequency fp, the output impedance Zo102C of the power receiving circuit 102C can be set to be smaller than the output impedance Zo101C of the receiving circuit 101C.

[0091] At the communication frequency fc, since the output impedance Zo101C of the receiving circuit 101C is larger than the output impedance Zo102C of the power receiving circuit 102C, the short-range wireless communication device 10C switches the current path for communication as shown in FIGS. 14(A) and 14(B), and similar to the short-range wireless communication device 10 of the first embodiment, the difference in the Q of resonance can be increased, and a desired load modulation level can be realized.

[0092] At the power receiving frequency fp, since the output impedance Zo102C of the power receiving circuit 102C is smaller than the output impedance Zo101C of the receiving circuit 101C, a current at a level sufficient for power supply can be supplied with low loss from the power receiving circuit 102C to the rectifying circuit 50 and the load circuit 60.

[0093] As a result, the short-range wireless communication device 10C can perform power reception and communication in parallel, can individually set the power reception characteristics and the communication characteristics, and can achieve both excellent power reception characteristics and excellent communication characteristics.

[0094] [Fifth Embodiment] The short-range wireless communication device according to the fifth embodiment of the present invention will be described with reference to the drawings. FIG. 15 is a functional block diagram showing the configuration of the short-range wireless communication device according to the fifth embodiment.

[0095] As shown in FIG. 15, the short-range wireless communication device 10D according to the fifth embodiment has a configuration in which the short-range wireless communication device 10A according to the second embodiment and the short-range wireless communication device 10C according to the fourth embodiment are appropriately combined. Hereinafter, only the parts different from the short-range wireless communication device 10A according to the second embodiment will be described.

[0096] As shown in FIG. 15, the short-range wireless communication device 10D according to the fifth embodiment is different from the short-range wireless communication device 10A according to the second embodiment in that it includes a reception circuit 101D and a power reception circuit 102D. Other configurations of the short-range wireless communication device 10D are the same as those of the short-range wireless communication device 10A, and the description of the same parts will be omitted.

[0097] The reception circuit 101C includes a coil 20, a capacitor 71, and a capacitor 32D. The capacitor 32D is connected in series between the node ND and the short-range wireless communication IC 40. The capacitor 32D corresponds to the "second resonance capacitor" of the present invention.

[0098] The power reception circuit 102D includes a coil 20, a capacitor 71, and a capacitor 31D. The coil 20 and the capacitor 71 are common to the reception circuit 101D. The capacitor 31D is connected in series between the node ND and the rectifier circuit 50. The capacitor 31D corresponds to the "first resonance capacitor" of the present invention.

[0099] In such a configuration, the output impedance Zo101D of the receiving circuit 101D is set by a circuit including the coil 20, the capacitor 71, and the capacitor 32D. The output impedance Zo102D of the power receiving circuit 102D is set by a circuit including the coil 20, the capacitor 71, and the capacitor 31D.

[0100] By setting the capacitance of the capacitor 31D to be larger than the capacitance of the capacitor 32D, at the communication frequency fc, the output impedance Zo101D of the receiving circuit 101D can be set to be larger than the output impedance Zo102D of the power receiving circuit 102D, and at the power receiving frequency fp, the output impedance Zo102D of the power receiving circuit 102D can be set to be smaller than the output impedance Zo101D of the receiving circuit 101D.

[0101] At the communication frequency fc, since the output impedance Zo101D of the receiving circuit 101D is larger than the output impedance Zo102D of the power receiving circuit 102D, the short-range wireless communication device 10D can switch the current path for communication as shown in each of the above embodiments, and similar to the short-range wireless communication device 10A of the second embodiment, increase the difference in the Q of resonance and realize a desired load modulation level.

[0102] At the power receiving frequency fp, since the output impedance Zo102D of the power receiving circuit 102D is smaller than the output impedance Zo101D of the receiving circuit 101D, a current at a level sufficient for power supply can be supplied to the rectifying circuit 50 and the load circuit 60 from the power receiving circuit 102D with low loss.

[0103] Thereby, the short-range wireless communication device 10D can perform power receiving and communication in parallel, can set the power receiving characteristics and the communication characteristics individually, and can achieve both excellent power receiving characteristics and excellent communication characteristics.

[0104] [Sixth Embodiment] A near - field wireless communication device according to a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 16 is a functional block diagram showing the configuration of the near - field wireless communication device according to the sixth embodiment.

[0105] As shown in FIG. 16, the near - field wireless communication device 10E according to the sixth embodiment has a configuration that appropriately combines the near - field wireless communication device 10B according to the third embodiment and the near - field wireless communication device 10C according to the fourth embodiment. Hereinafter, only the parts different from the near - field wireless communication device 10B according to the third embodiment will be described.

[0106] As shown in FIG. 16, the near - field wireless communication device 10E according to the sixth embodiment is different from the near - field wireless communication device 10B according to the third embodiment in that it includes a receiving circuit 101E and a power receiving circuit 102E. Other configurations of the near - field wireless communication device 10E are the same as those of the near - field wireless communication device 10B, and the description of the same parts will be omitted.

[0107] The receiving circuit 101E includes a coil 20, a capacitor 71, a capacitor 72, and a capacitor 32E. The capacitor 32E is connected in series between the node ND and the near - field wireless communication IC 40. The capacitor 32E corresponds to the "second resonance capacitor" of the present invention.

[0108] The power receiving circuit 102E includes a coil 20, a capacitor 71, a capacitor 72, and a capacitor 31E. The coil 20, the capacitor 71, and the capacitor 72 are common to the receiving circuit 101E. The capacitor 31E is connected in series between the node ND and the rectifying circuit 50. The capacitor 31E corresponds to the "first resonance capacitor" of the present invention.

[0109] In such a configuration, the output impedance Zo101E of the receiving circuit 101E is set by a circuit including the coil 20, the capacitor 71, the capacitor 72, and the capacitor 32E. The output impedance Zo102E of the power receiving circuit 102E is set by a circuit including the coil 20, the capacitor 71, the capacitor 72, and the capacitor 31E.

[0110] Then, by setting the capacitance of the capacitor 31E to be larger than the capacitance of the capacitor 32E, at the communication frequency fc, the output impedance Zo101E of the receiving circuit 101E can be set to be larger than the output impedance Zo102E of the power receiving circuit 102E, and at the power receiving frequency fp, the output impedance Zo102E of the power receiving circuit 102E can be set to be smaller than the output impedance Zo101E of the receiving circuit 101E.

[0111] At the communication frequency fc, since the output impedance Zo101E of the receiving circuit 101E is larger than the output impedance Zo102E of the power receiving circuit 102E, the short - range wireless communication device 10E can switch the current path for communication as shown in each of the above - mentioned embodiments, and similar to the short - range wireless communication device 10B of the third embodiment, increase the difference in the Q of resonance and realize a desired load modulation level.

[0112] At the power receiving frequency fp, since the output impedance Zo102E of the power receiving circuit 102E is smaller than the output impedance Zo101E of the receiving circuit 101E, a current at a level sufficient for power supply can be supplied to the rectifying circuit 50 and the load circuit 60 from the power receiving circuit 102E with low loss.

[0113] Thereby, the short - range wireless communication device 10E can perform power reception and communication in parallel, can set the power reception characteristics and the communication characteristics individually, and can achieve both excellent power reception characteristics and excellent communication characteristics.

[0114] In the configuration of each of the above-described embodiments, the case where the communication frequency fc and the power reception frequency fp are the same is shown. However, even if the communication frequency fc and the power reception frequency fp are different, if the magnitude relationship between the output impedance of the above-described reception circuit and the output impedance of the power reception circuit can be ensured, the above-described effects can be achieved. In this case, by adopting the configurations of the short-range wireless communication devices 10C, 10D, and 10E according to the above-described fourth, fifth, and sixth embodiments, the output impedances of the reception circuit and the power reception circuit can be individually adjusted, which is effective.

[0115] Also, when the communication frequency fc and the power reception frequency fp are different, it is preferable that at least a part of the communication frequency band including the communication frequency fc and the power reception frequency band including the power reception frequency fp overlap. Thereby, by providing at least a capacitor in the power reception circuit, the magnitude relationship between the output impedance of the above-described reception circuit and the output impedance of the power reception circuit can be ensured.

Explanation of Reference Numerals

[0116] 1: Short-range wireless communication system 10, 10A, 10B, 10C, 10D, 10E: Short-range wireless communication devices 11: Support substrate 12: Magnetic sheet 20: Coil 31, 31A, 31B, 31C, 31D, 31E, 32C, 32D, 32E: Capacitors 40: Short-range wireless communication IC 50: Rectifier circuit 60: Load circuit 61: Voltage conversion circuit 62: Charging circuit 63: Secondary battery 64: Voltage conversion circuit 71, 72: Capacitors 90: Transmitter 91: Voltage conversion circuit 92: Transmission control circuit 99: Power supply 101, 101A, 101B, 101C, 101D, 101E: Reception circuits 102, 102A, 102B, 102C, 102D, 102E: Power receiving circuit 191, 192: Electronic components 620: Charging control circuit 640: Discharging control circuit 900: Coil ND: Node R40off: Open resistance R40on: Conductive resistance SW40: Switch Voff: Input voltage Von: Input voltage Zo101, Zo101A, Zo101B, Zo101C, Zo101D, Zo101E: Output impedance of receiving circuit Zo102, Zo102A, Zo102B, Zo102C, Zo102D, Zo102E: Output impedance of power receiving circuit

Claims

1. A power receiving coil that shares power reception in power feeding using short-range wireless communication and reception in wireless communication of data using the short-range wireless communication; A power receiving resonance circuit that forms a resonance circuit with the power receiving coil and one or more resonance capacitors; A wireless communication circuit and a load circuit that performs work using electricity, each electrically connected to the power receiving resonance circuit; Comprising: The power receiving resonance circuit: A receiving circuit that supplies a voltage for communication from the power receiving coil to the wireless communication circuit; A power receiving circuit that supplies an electric current for power reception from the power receiving coil to the load circuit; Comprising: At the communication frequency for performing the wireless communication, the wireless communication output impedance that supplies a voltage for communication from the receiving circuit to the wireless communication circuit is larger than the power receiving output impedance that supplies an electric current for power reception from the power receiving circuit to the load circuit; At the power receiving frequency for performing the power reception, the power receiving output impedance is smaller than the wireless communication output impedance. A short-range wireless communication device having a power receiving function.

2. At least a part of each of the frequency bands of the communication frequency and the power receiving frequency overlaps. The short-range wireless communication device having the power receiving function according to Claim 1.

3. The communication frequency and the power receiving frequency have the same frequency band. The short-range wireless communication device having the power receiving function according to Claim 2.

4. The resonance capacitor is provided only in the power receiving circuit. The short-range wireless communication device having the power receiving function according to Claim 1.

5. The resonance capacitor: A first resonance capacitor provided in the power receiving circuit; A second resonance capacitor provided in the receiving circuit; Comprising: The resonance capacitance of the first resonance capacitor is larger than the resonance capacitance of the second resonance capacitor. The short-range wireless communication device having the power receiving function according to Claim 1.

6. Comprising a support base material that supports the power receiving coil and the power receiving resonance circuit; The power receiving coil and the power receiving resonance circuit are arranged on the same plane. The short-range wireless communication device having the power receiving function according to Claim 1.

7. Comprising a magnetic sheet that overlaps the power receiving coil. The short-range wireless communication device having the power receiving function according to Claim 6.

8. The load circuit includes a secondary battery. The short-range wireless communication device having the power receiving function according to Claim 1.

9. The receiving circuit has a change rate of impedance due to load modulation of the wireless communication of 30% or more. The short-range wireless communication device having a power receiving function according to claim 1.

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