JP6390812B2 - Circuit switching device and switch drive circuit - Google Patents

Description

  The present invention relates to a circuit switching device and a switch drive circuit for electrically connecting or disconnecting circuits.

  As a conventional antenna device, there is a non-contact transmission device described in Patent Document 1. In this non-contact transmission device, one end of the first winding portion is connected to a common terminal and the other end is connected to a non-contact communication terminal. Further, one end of the second winding portion is connected to a contactless communication terminal, and the other end is connected to a contactless power supply terminal. The first winding portion is used as a non-contact communication coil. The first winding portion and the second winding portion are used as non-contact power supply coils.

JP2013-93429A

  In the non-contact transmission device of Patent Document 1, the first winding unit is commonly used for non-contact communication and non-contact power feeding. In this case, the contactless communication may be delayed because the contactless communication circuit is affected by the contactless power receiving circuit. For this reason, it is necessary to provide a switch so that the first winding portion is connected to one of the power receiving circuit or the communication circuit. In such a case, a microcomputer or the like for switching the switch is required, which may make it difficult to reduce costs. Moreover, when providing a microcomputer, it is necessary to provide the power source (auxiliary power supply) for microcomputers. For this reason, downsizing of the apparatus is hindered.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a circuit switching device and a switch drive circuit that can switch circuits without using an auxiliary power source.

  A circuit switching device according to the present invention includes a first coil antenna, a power receiving circuit for a non-contact power supply system connected to the first coil antenna, and short-range wireless communication connected to the first coil antenna. A communication circuit for a system; a first switch element having a first control terminal; and cutting off power supply from the first coil antenna to the power receiving circuit; and a signal received by the first coil antenna A detection circuit that detects a signal of a specific frequency, outputs a control voltage to the first control terminal, and directly drives the first switch element.

  In this configuration, when the signal received by the first coil antenna has a specific frequency, the signal is detected and a control voltage is output to the first control terminal of the first switch element. Then, normally, the first switch element that cuts off the power supply from the first coil antenna to the power reception circuit is turned on, and the power supply to the power reception circuit (load circuit) becomes possible. That is, the first switch element can be turned on without using a signal processing circuit such as a microcomputer. Therefore, the circuit switching device having the above configuration does not require a signal processing circuit (such as a microcomputer) for switching the first switch element and a power source (constant voltage circuit) for the signal processing circuit. Thereby, a circuit switching device capable of switching circuits without using an auxiliary power source can be realized.

  The circuit switching device according to the present invention includes a first coil antenna, a power receiving circuit for a non-contact power supply system connected to the first coil antenna, and a second coil magnetically coupled to the first coil antenna. An antenna, a communication circuit for a short-range wireless communication system connected to the second coil antenna, and a first control terminal, wherein a power supply from the first coil antenna to the power receiving circuit is cut off. Among the signals received by the first switch element and the first coil antenna, a signal having a specific frequency is detected, and a control voltage is output to the first control terminal to directly drive the first switch element. And a detection circuit.

  In this configuration, even if both coil antennas must be placed close to each other due to restrictions such as the space of the housing that houses the circuit switching device, the circuit can be switched without using an auxiliary power source. The influence of the circuit on the communication circuit can be suppressed.

  The detection circuit may include a double resonance circuit.

  In the case of double resonance, there are two resonance points. Sensitivity is substantially constant in the frequency band between the two resonance points. For this reason, even if the frequency of the signal received by the first coil antenna fluctuates using this frequency band, the frequency characteristics near the specific frequency can be flattened. Thereby, a signal can be detected stably and the first switch element can be turned on.

  The multi-resonant circuit may include an insulating transformer.

  In this configuration, a signal having a specific frequency can be detected without being affected by the common mode signal (noise). The first switch element can be controlled in a floating state (can be turned on and off without being directly connected to the reference potential).

  The communication circuit may include a second switch element that has a second control terminal and cuts off or connects power supply from the first or second coil antenna to the communication circuit.

  In this configuration, when the circuit switching device receives the operating frequency of the non-contact power supply system, the power supply to the communication circuit can be cut off. As a result, the communication IC of the communication circuit can be protected from overvoltage caused by non-contact power supply.

  The second switch element may have the second control terminal connected to the output side of the detection circuit.

  In this configuration, the first and second switch elements can be controlled by a single detection circuit, and a smaller circuit switching device can be realized by providing each with a signal processing circuit.

  The switch drive circuit according to the present invention includes an input unit that inputs an AC voltage from a power supply line, a filter circuit that passes a voltage of a specific frequency among the voltages input from the input unit, and the filter circuit. And a rectifier circuit that rectifies the voltage and outputs the rectified voltage to a control terminal of a switch element that electrically cuts off or connects the power supply line.

  In this configuration, when the input AC voltage has a specific frequency, the voltage passes through the filter circuit, is rectified by the rectifier circuit, and is output to the control terminal of the switch element. Normally, the switch element that cuts off the power supply line is turned on. That is, the switch element can be turned on without using a separate signal processing circuit (such as a microcomputer). And since the voltage of an electric power supply line is utilized, the switch drive circuit which can switch a switch element without using an auxiliary power supply is realizable.

  According to the present invention, a circuit can be switched without using a signal processing circuit such as a microcomputer for switching the switching element and an auxiliary power source for the signal processing circuit.

FIG. 1 is a block diagram of a power supply system according to the first embodiment. FIG. 2 is a diagram illustrating experimental results according to the first embodiment. FIG. 3 is a circuit diagram of the power receiving device according to the first embodiment. FIG. 4 is a block diagram of a power receiving device in which the arrangement of the switch circuit is changed. FIG. 5 is a diagram illustrating an example of frequency characteristics of the output voltage of the switch drive circuit. FIG. 6 is a diagram showing a switch drive circuit made into one chip. FIG. 7 is a circuit diagram of the power receiving device in which the connection point of the switch drive circuit is changed. FIG. 8 is a circuit diagram of a power receiving device having a single-ended switch drive circuit. FIG. 9 is a block diagram of a power receiving device in which the communication circuit includes individual coil antennas. FIG. 10 is a circuit diagram of the power receiving device according to the second embodiment. FIG. 11 is a circuit diagram of a power receiving device according to the third embodiment. FIG. 12 is a block diagram of a power receiving device according to the fourth embodiment. FIG. 13 is a block diagram of a power receiving device in which the communication circuit according to the fourth embodiment includes individual coil antennas. FIG. 14 is a block diagram of a power receiving device in which the switch circuit is arranged to short-circuit between the power supply lines.

  FIG. 1 is a block diagram of a power supply system 100 according to the first embodiment.

  The power supply system 100 includes a power receiving device 10 and a power feeding device 20 or a communication device. The power supply system 100 operates as a contactless power supply system or a short-range wireless communication system. When operating as a non-contact power supply system, the power receiving device 10 is supplied with power from the power supply device 20. When operating as a short-range wireless communication system, the power receiving device 10 communicates with the communication device 30.

  The contactless power supply system is, for example, a contactless power supply system that uses magnetic field coupling in the near field, and includes an electromagnetic induction power supply system and a magnetic resonance power supply system. In the non-contact power supply system, for example, HF (High Frequency) band, in particular, power having a frequency in the vicinity of 6.78 MHz is transmitted from the power feeding device 20 to the power receiving device 10.

  The short-range wireless communication system is a system using NFC (Near Field Communication), for example. NFC is short-range wireless communication using magnetic field coupling in the near field, and does not include short-range wireless communication using electromagnetic waves such as Bluetooth (registered trademark). In the short-range wireless communication system, for example, a signal having a frequency in the HF band, particularly around 13.56 MHz is transmitted from the communication device 30 to the power receiving device 10 (or vice versa).

  The power feeding device 20 includes a coil antenna 21 and a power feeding circuit 22. An AC voltage is applied to the coil antenna 21 by the power feeding circuit 22. The coil antenna 21 forms a resonance circuit with a capacitor (not shown), and is magnetically coupled to a coil antenna (first coil antenna) 11 described later included in the power receiving device 10. When the coil antennas 11 and 21 are magnetically coupled, non-contact power is supplied from the power feeding device 20 to the power receiving device 10.

  The power feeding circuit 22 includes a DC-AC inverter. The DC-AC inverter generates a high-frequency AC voltage or AC current. The power feeding circuit 22 applies a 6.78 MHz AC voltage to the coil antenna 21.

  The communication device 30 includes a coil antenna 31 and a communication circuit 32. Then, similarly to the power feeding device 20, the coil antennas 31 and 11 are magnetically coupled, whereby the communication circuit 17 of the power receiving device 10 and the communication device 30 communicate wirelessly. The communication circuit 32 includes a transmission / reception circuit. The communication circuit 32 operates at 13.56 MHz.

  The power receiving device 10 includes a coil antenna 11, a matching circuit 12, a rectifier circuit 13, a switch circuit 14, a load circuit 15, a switch drive circuit 16, and a communication circuit 17. The power receiving device 10 is an example of the “circuit switching device” according to the present invention. The switch drive circuit 16 is an example of the “detection circuit” according to the present invention.

  The load circuit 15 includes, for example, a charging circuit and a secondary battery. The load circuit 15 charges the secondary battery with the power supplied from the power supply device 20 during the operation of the non-contact power supply system. The load circuit 15 is an example of the “power receiving circuit for a non-contact power supply system” according to the present invention. The communication circuit 17 is used for a short-range wireless communication system. The communication circuit 17 is an example embodiment that corresponds to the “communication circuit for near field communication system” according to the present invention.

  The matching circuit 12 of the power receiving circuit is connected to the coil antenna 11. The matching circuit 12 includes a coil antenna 11 and a resonance capacitor (not shown) that forms a resonance circuit. A resonance circuit including coil antennas 21 and 31 is configured on the power feeding device 20 and the communication device 30 side. In the matching circuit 12, the resonance frequency of the resonance circuit including the coil antenna 11 and the communication circuit 17 is set near the frequency of the non-contact power supply system.

  The rectifier circuit 13 is connected to the matching circuit 12 by two power supply lines 101A and 102A through which an AC signal flows. The rectifier circuit 13 rectifies the voltage induced in the coil antenna 11 that is magnetically coupled to the coil antenna 21 of the power feeding device 20.

  The switch circuit 14 is connected to the rectifier circuit 13. A smoothing capacitor Co and a load circuit 15 are connected to the switch circuit 14. When the switch circuit 14 is on, the rectifier circuit 13, the load circuit 15 and the smoothing capacitor Co are electrically connected. When the switch circuit 14 is off, the rectifier circuit 13, the load circuit 15 and the smoothing capacitor Co are electrically disconnected. That is, the switch circuit 14 switches between power supply to the load circuit 15 and interruption of the power supply. When the control voltage is not applied, the switch circuit 14 is off and is turned on by a switch drive circuit 16 described later.

  The switch drive circuit 16 is connected to the power supply lines 101A and 102A. When the voltage between the power supply lines 101A and 102A has a specific frequency, the switch drive circuit 16 outputs a control voltage to the switch circuit 14 and turns on the switch circuit 14. The switch drive circuit 16 directly drives the switch circuit 14. In this embodiment, the specific frequency is 6.78 MHz. That is, the switch drive circuit 16 turns on the switch circuit 14 during the operation of the non-contact power supply system. When the output voltage from the matching circuit 12 is not a specific frequency, the switch drive circuit 16 maintains the off state without turning on the switch circuit 14. The case where the output voltage is not a specific frequency is, for example, a case where the frequency is 13.56 MHz. That is, the switch drive circuit 16 does not turn on the switch circuit 14 during the operation of the short-range wireless communication system.

  The communication circuit 17 is connected to the power supply lines 101A and 102A. The communication circuit 17 receives a signal voltage induced in the coil antenna 11 that is magnetically coupled to the coil antenna 31 of the communication device 30. In this case, the communication circuit 17 becomes a receiving circuit. As described above, during the operation of the short-range wireless communication system, the switch circuit 14 is off, and the received 13.56 MHz signal (carrier wave + modulation component) is blocked by the switch circuit 14. That is, during operation of the short-range wireless communication system, unnecessary power supply to the load circuit 15 and the smoothing capacitor Co due to the communication signal voltage is suppressed, and the signal is efficiently transmitted to the communication circuit 17. Therefore, the communication circuit 17 operates without being affected by unnecessary power supply to the load circuit 15 and the smoothing capacitor Co.

  When a communication signal is transmitted from the power receiving device 10 to the communication device 30, the communication circuit 17 becomes a transmission circuit and applies a communication signal voltage to the coil antenna 11. In this case, the switch circuit 14 is off, and power supply to the load circuit 15 and the smoothing capacitor Co is cut off. Therefore, the communication circuit 17 operates without being affected by the power supply to the load circuit 15.

  FIG. 2 shows the result of measuring the detection distance of the non-contact IC card by operating the NFC system in this embodiment. Here, the communication circuit 17 was set to Reader / Writer mode, the non-contact IC card was brought close to the coil antenna 11, and the distance at which the non-contact IC card was recognized was measured. Also, the detection distance was confirmed for four types of representative cards. Card 1 uses Topaz, Card 2 uses Mifare UL, Card 3 uses Octpus, and Card 4 uses Mifare desfire. Mifare is a registered trademark. In FIG. 2, the configuration of the present application is a power receiving device 10 in which the communication device 30 is realized by a non-contact IC card and the short-range wireless communication system is realized by an NFC system. The configuration of Comparative Example 1 is a configuration in which a frequency detector 161 described later is excluded from the configuration of the present application. The configuration of Comparative Example 2 is an NFC system including a communication device 30 and a communication circuit 17 realized by a non-contact IC card. As can be seen from FIG. 2, the detection distance is greatly reduced by connecting the load circuit 15 for power transmission to the communication circuit 17 (see the results in the configurations of Comparative Example 1 and Comparative Example 2). , The influence of the load circuit 15 and the smoothing capacitor Co can be reduced, the communication distance can be suppressed, and communication can be performed more reliably (results in the configuration of the present application and the configuration of Comparative Example 1). reference).

  FIG. 3 is a circuit diagram of the power receiving device 10 according to the first embodiment.

  The power receiving circuit matching circuit 12 includes capacitors C21 and C22. The capacitors C21 and C22 and the coil antenna 11 constitute a resonance circuit.

  The communication circuit 17 includes capacitors C31, C32, C33, C34, C35, C36, inductors L31, L32, and a communication IC 171. The capacitors C31 to C34 constitute a communication circuit matching circuit between the communication IC 171 and the coil antenna 11, and are connected to the power supply lines 101A and 102A. The capacitor C35 and the inductor L31, and the capacitor C36 and the inductor L32 constitute a low-pass filter, and are provided between the communication circuit matching circuit and the communication IC 171. The low-pass filter removes harmonic components of a frequency used when the communication circuit 17 operates as a transmission circuit. The low-pass filter can be used as a part of a communication circuit matching circuit between the communication IC 171 and the coil antenna 11.

  The rectifier circuit 13 is a diode bridge circuit.

  The switch circuit 14 includes a switch element (first switch element) Q1 and a gate resistor R1. The switch element Q1 is an n-type MOS-FET. The switch element Q1 is connected in series to a power supply line (hot line) 101B that connects the rectifier circuit 13 and the load circuit 15. When the switch element Q1 is not receiving high-frequency power at the operating frequency of the non-contact power supply system, the switch element Q1 is off because no voltage is applied from the switch drive circuit 16 to the gate and the source. The rectifier circuit 13, the load circuit 15, and the smoothing capacitor Co are electrically disconnected. Further, when a voltage is applied between the gate and the source by the switch drive circuit 16, the switch is turned on. The rectifier circuit 13, the load circuit 15, and the smoothing capacitor Co are electrically connected.

  The switch circuit 14 may be connected between the smoothing capacitor Co and the load circuit 15, and in that case, signal inflow to the load circuit 15 can be reduced. The switch element Q1 and the gate resistor R1 of the switch circuit 14 may be connected in series to a reference potential line (cold line) 102B that connects the rectifier circuit 13 and the load circuit 15. Further, instead of the switch circuit 14, a switch circuit 14 </ b> C composed of a bidirectional switch circuit is connected in series between the rectifier circuit 13 and the connection CP where the switch drive circuit 16 is connected to the power supply lines 101 </ b> A and 102 </ b> A. It may be connected. FIG. 4 shows a power receiving device 10C in which the switch circuit 14C is connected to the power supply lines 101A and 102A. In this configuration, an EMI (ElectroMagnetic Interference) filter 18 is connected between the connection portion CP and the rectifier circuit 13, and a switch circuit 14 </ b> C is connected between the connection portion CP and the EMI filter 18. Since the switch circuit 14C needs to cut off the alternating current, the switch circuit 14C is configured by a bidirectional switch circuit as described above. The bidirectional switch circuit is a circuit in which two switch elements such as FETs are used so as to be opposite to each other. At this time, the influence of the capacitance component of the rectifier circuit 13 can be reduced by using an element having a small parasitic capacitance for the switch circuit 14C. Therefore, the influence of the parasitic capacitance on the communication circuit 17 can be further reduced.

  As shown in FIG. 3, the switch drive circuit 16 has input parts In1, In2 and output parts Out1, Out2. The input unit In1 is connected to the power supply line 101A via the capacitor C41. The input unit In2 is connected to the power supply line 102A via the capacitor C42. Capacitors C41 and C42 have the same capacitance. Capacitors C41 and C42 form a voltage dividing circuit with C11 described later, and divide the voltage between the power supply lines 101A and 102A. Therefore, the voltage between the power supply lines 101A and 102A is divided and input by the capacitors C41, C42 and C11 to the switch drive circuit 16. The output units Out1 and Out2 are connected to the gate and source (control terminal, first control terminal) of the switch element Q1 of the switch circuit 14.

  The switch drive circuit 16 includes a frequency detector 161 and a rectifying / smoothing circuit 162. The frequency detector 161 is an example of the “filter circuit” according to the present invention. The rectifying / smoothing circuit 162 is an example embodiment that corresponds to the “rectifying circuit” according to the present invention.

  The rectifying / smoothing circuit 162 is connected to the frequency detector 161. The rectifying / smoothing circuit 162 includes a diode D1 and a capacitor C13, and rectifies and smoothes the voltage output from the frequency detector 161. The voltage rectified and smoothed by the rectifying and smoothing circuit 162 is output from the output units Out1 and Out2, and is applied between the gate and source of the switch element Q1. Note that the rectifying / smoothing circuit 162 may not include the capacitor C13. Further, instead of the capacitor C13, the input capacitance of the switch element Q1 may be used.

  The frequency detector 161 includes capacitors C11 and C12 and an insulating transformer T. The capacitor C11 is connected between the input parts In1 and In2. The primary coil L11 of the insulation transformer T is connected in parallel to the capacitor C11. A capacitor C12 is connected in parallel to the secondary coil L12 of the insulation transformer T. By connecting in parallel, the voltage across the coil can be taken out as the drive voltage. The capacitor C11 and the primary coil L11 of the insulating transformer T constitute a resonance circuit. The capacitor C12 and the primary coil L11 of the insulating transformer T also form a resonance circuit.

  In the present embodiment, the resonance circuit constitutes a parallel resonance circuit, but may be a series resonance circuit or a combination thereof. Further, in the parallel resonance circuit and the series resonance circuit, the parallel resonance circuit is preferable because the parallel resonance circuit can easily obtain a higher voltage.

  These two parallel resonance circuits are set to have a constant value so as to coincide with a specific frequency of signals flowing through the power supply lines 101A and 102A, and constitute a mutually coupled multiple resonance circuit. FIG. 5 shows the output voltage frequency characteristics of the switch drive circuit 16 in this embodiment. In this embodiment, the specific frequency is 6.78 MHz. The output voltage frequency characteristic of the switch drive circuit 16 has a peak at a specific frequency of 6.78 MHz.

  When the voltage between the power supply lines 101 </ b> A and 102 </ b> A is 6.78 MHz, the input voltage to the switch driving circuit 16 passes through the frequency detector 161 and is rectified and smoothed by the rectifying and smoothing circuit 162. The voltage is applied between the gate and source of the switch element Q1, and the switch element Q1 is turned on. That is, when operating in a non-contact power supply system with a drive frequency of 6.78 MHz, the switch drive circuit 16 turns on the switch element Q1 and supplies power to the load circuit 15.

  On the other hand, when the voltage between the power supply lines 101A and 102A is different from 6.78 MHz, for example, 13.56 MHz, the input voltage to the switch drive circuit 16 is blocked by the frequency detector 161. Therefore, no voltage is output from the frequency detector 161, and the switch element Q1 is not turned on. That is, when operating in a short-range wireless communication system with a drive frequency of 13.56 MHz, the switch drive circuit 16 does not turn on the switch element Q1, and unnecessary power supply to the load circuit 15 by the communication signal voltage is cut off. The

  As described above, when the power receiving device 10 is magnetically coupled to the communication device 30, the load circuit is cut only when unnecessary power supply to the load circuit 15 by the communication signal voltage is cut off and magnetically coupled to the power feeding device 20. 15 can be supplied with power. Thereby, the power receiving apparatus 10 can perform non-contact power supply or short-range wireless communication using the common coil antenna 11. In addition, since the common antenna can be used, the degree of freedom in arranging the antenna to the power receiving device can be increased and the number of connection portions between the antenna and the circuit can be reduced.

  Note that when the power receiving device 10 and the power feeding device 20 are magnetically coupled, power is also supplied to the communication circuit 17. However, when operating in a non-contact power supply system, since the impedance of the communication circuit 17 is higher than the impedance of the power receiving circuit, the current flowing into the communication circuit 17 is small and the power loss in the communication circuit 17 is small. That is, the influence of the power supply to the communication circuit 17 on the power supply to the load circuit 15 is small.

  The switch drive circuit 16 applies a voltage between the rectified and smoothed power supply lines 101A and 102A between the gate and the source of the switch element Q1 to turn on the switch element Q1. Therefore, the switch driving circuit 16 does not require a complicated signal processing circuit (such as a microcomputer for performing complicated processing) and can be realized with a simple circuit configuration. In addition, since a power source for the switch drive circuit 16 is not required, downsizing of the power receiving device 10 is not hindered. Further, when the secondary battery of the power receiving device 10 is discharged and the signal processing circuit mounted with the power receiving device 10 on the electronic device or the like is not activated, the switch driving circuit 16 receives the high frequency power of 6.78 MHz. Operates and can be charged and charged.

  Further, the switch drive circuit 16 is connected in parallel to the power supply lines 101A and 102A. For this reason, a loss can be reduced compared with the case where the switch drive circuit 16 is provided in the middle of the power supply lines 101A and 102A.

  Further, the frequency detector 161 of the switch drive circuit 16 uses multiple resonances in order to detect (pass) an AC voltage having a specific frequency. In the case of double resonance, there are two resonance points. In the frequency band between the two resonance points, the sensitivity of the frequency detector 161 can be made substantially constant. For this reason, if this frequency band is used, even if the frequency of the AC voltage to be detected varies, the AC voltage can be detected stably and the switch circuit 14 can be turned on.

  Furthermore, since the frequency detector 161 is composed of the insulating transformer T, the influence of the common mode signal (noise) can be reduced. Furthermore, the switch element Q1 can be controlled in a floating state. That is, the switch element Q1 can be controlled without being directly connected to the ground potential. Note that the frequency detector 161 may be an LC filter that is set to a constant so that an AC voltage of a specific frequency passes. Alternatively, a low-pass filter, a high-pass filter, or a band rejection filter may be used.

  The switch drive circuit 16 may be configured by mounting each element on a circuit board, or may be formed on a single chip.

  FIG. 6 is a diagram showing the switch drive circuit 16 made into one chip.

  The switch drive circuit 16 includes a laminated body 160 in which a plurality of insulator layers such as ferrite are laminated and sintered. In the laminate 160, coils 160A and 160B are formed by a conductor pattern printed on an insulator layer. The coils 160A and 160B are formed to be magnetically coupled, for example, with the same winding axis. The coil 160A corresponds to the primary coil L11 of the insulation transformer T shown in FIG. 3, and the coil 160B corresponds to the secondary coil L12 of the insulation transformer T. On one main surface of the multilayer body 160, elements constituting the switch drive circuit 16, such as capacitors C11 and C12 and a diode D1, are mounted. Each element is wired by a via conductor and a conductor pattern (not shown).

  Thus, by making the switch drive circuit 16 into one chip, the occupied area on the substrate on which the switch drive circuit 16 is mounted can be reduced. For this reason, the freedom degree of the layout at the time of design improves. Further, the nonlinearity of the magnetic material can be used to give the output voltage nonlinearity.

  That is, when the input level is low, the input / output voltage ratio responds linearly, and when the input level is high, the input / output voltage ratio is set to decrease. Thereby, overvoltage of the output voltage can be prevented, and the range of the input voltage can be expanded.

  The connection point of the switch drive circuit 16 may not be provided between the matching circuit 12 and the rectifier circuit 13. FIG. 7 shows a power receiving device 10D in which connection points are set so that the matching circuit 12D is divided in capacity. Matching circuit 12D includes capacitors C21 to C24. Connection points of the switch drive circuit 16 are provided between the capacitor C21 and the capacitor C23 and between the capacitor C22 and the capacitor C24. In this configuration, the voltage input to the switch drive circuit 16 can be increased without increasing the capacitances of the capacitors C41 and C42.

  Further, the circuit configuration of the switch drive circuit may be a single end configuration. FIG. 8 shows a power receiving device 10E including a switch driving circuit 16E having a single end configuration. The switch drive circuit 16E has a frequency detector 161E including a transformer TE to which a primary coil L11 and a secondary coil L12 are connected. In the single-ended configuration, it is not necessary to use an isolation transformer, and the circuit can be reduced in size and simplified.

  The non-contact power supply system and the short-range wireless communication system use a common coil antenna, but may include individual coil antennas. FIG. 9 shows a power receiving device 10F provided with individual coil antennas 11 and 11F. A coil antenna (second coil antenna) 11 </ b> F is connected to the communication circuit matching circuit 172 of the communication circuit 17. The communication circuit matching circuit 172 includes capacitors C31 to C34 (see FIG. 3). The low-pass filter 173 includes capacitors C35 and 36 and inductors L31 and L32 (see FIG. 3).

  When both coil antennas 11 and 11F have to be disposed close to each other due to restrictions such as a space of a housing that houses the power receiving device 10F, magnetic field coupling occurs between the coil antennas 11 and 11F. Since both coil antennas 11 and 11F are coupled to each other, the power transmission circuit (load circuit 15 and smoothing capacitor Co) affects the communication characteristics of the communication circuit 17 in the same manner as when the common coil antenna is provided. May give. Therefore, by adding the switch drive circuit 16 and the switch circuit 14 to the power transmission circuit, unnecessary power supply to the load circuit 15 and the smoothing capacitor Co is cut off, and the power supply device 20 (see FIG. 1) is magnetically coupled. Only when the power is supplied to the load circuit 15, the influence of the load circuit 15 and the smoothing capacitor Co can be suppressed.

(Embodiment 2)
The power receiving device according to the second embodiment is different from the first embodiment in the configuration of a switch circuit that switches between supplying power to the load circuit and shutting off the power.

  FIG. 10 is a circuit diagram of the power receiving device 10A according to the second embodiment.

  An EMI filter 18 is provided between the matching circuit 12 and the rectifier circuit 13.

  The switch circuit 14A has switch elements Q2 and Q3. The switch element Q2 is a p-type MOS-FET. The switch element Q2 is provided on the power supply line 101B. The switch element Q3 is an n-type MOS-FET. The drain of the switch element Q3 is connected to the gate of the switch element Q2. The source of the switch element Q3 is connected to the reference potential. The gate of the switch element Q3 is connected to the output unit Out1 of the switch drive circuit 16.

  Input portions In 1 and In 2 of the switch drive circuit 16 are connected between the coil antenna 11 and the matching circuit 12. That is, a voltage induced in the coil antenna 11 is input to the switch drive circuit 16 without passing through the matching circuit 12. As a result, a higher voltage is input to the switch drive circuit 16. The output part Out1 of the switch drive circuit 16 is connected to the gate of the switch element Q3. The output unit Out2 is connected to the reference potential.

  As in the first embodiment, when the voltage between the power supply lines 101A and 102A is 6.78 MHz, the switch drive circuit 16 rectifies and smoothes the voltage. Then, the switch drive circuit 16 applies the rectified and smoothed voltage between the gate and the source of the switch element Q3. The switch element Q3 is turned on, the gate of the switch element Q2 is connected to the reference potential, and the switch element Q2 is turned on. As a result, the rectifier circuit 13 and the load circuit 15 are electrically connected, and power is supplied to the load circuit 15.

  In this configuration, since the output terminal (output unit Out2 side) of the frequency detector 161 is connected to the reference potential, the reference potential of the signal processing circuit can be shared. If the output end (output unit Out1 side) of the frequency detector 161 is connected to a signal processing circuit (a voltage dividing circuit or the like is inserted as appropriate), the arrival state of power at a specific frequency can be monitored.

  Even in this configuration, when the power receiving device 10A operates in the short-range wireless communication system, the power receiving device 10A blocks unnecessary power supply to the load circuit 15 by the communication signal voltage and operates in the non-contact power supply system. Only when this is done, power can be supplied to the load circuit 15. The switch drive circuit 16 does not require a signal processing circuit (such as a microcomputer) that requires power supply and performs complicated processing, and can be realized with a simple circuit configuration. In addition, since a power source for the switch drive circuit 16 is not required, downsizing of the power receiving device 10A is not hindered. Further, even when the secondary battery of the power receiving device 10A is discharged and the signal processing circuit is not activated, when the high frequency power of 6.78 MHz is received, the switch driving circuit operates and can be fed and charged.

(Embodiment 3)
The power receiving device according to the third embodiment is different from the first embodiment in the configuration of a switch circuit that switches between power supply to the load circuit and interruption thereof.

  FIG. 11 is a circuit diagram of the power receiving device 10B according to the third embodiment.

  The switch circuit 14B included in the power receiving device 10B includes a switch element Q4. The switch element Q4 is an n-type MOS-FET. The drain of the switch element Q4 is connected to the power supply line 101B via the capacitor C5. The source of the switch element Q4 is connected to the reference potential line 102B. The gate of the switch element Q4 is connected to the output unit Out1 of the switch drive circuit 16.

  Similarly to the first embodiment, when the AC voltage between the power supply lines 101A and 102A is 6.78 MHz, the switch drive circuit 16 rectifies and smoothes the voltage. Then, the switch drive circuit 16 applies the rectified and smoothed voltage to the gate of the switch element Q4. When the switch element Q4 is turned on, the capacitor C5 is connected between the power supply lines 101A and 102A. As a result, the voltage supplied to the load circuit 15 is charged and smoothed by charging the capacitor C5, so that stable power supply to the load circuit 15 can be achieved. Conversely, when the AC voltage has a frequency other than 6.78 MHz, the switch element Q4 does not conduct, and thus the capacitor C5 is disconnected from the rectifier circuit 13. As a result, when operating in the short-range wireless communication system, the communication circuit 17 operates while reducing the influence of unnecessary power supply to the capacitor C5. Therefore, a decrease in communication distance can be suppressed and communication can be performed more reliably.

  Further, the switch drive circuit 16 rectifies and smoothes the AC voltage between the power supply lines 101A and 102A and applies it to the gate of the switch element Q4 to turn on the switch element Q4. For this reason, the switch drive circuit 16 does not require a signal processing circuit (such as a microcomputer) for performing complicated processing, and can be realized with a simple circuit configuration. In addition, since a power source for the switch drive circuit 16 is not required, downsizing of the power receiving device 10B is not hindered. Further, even when the secondary battery of the power receiving device 10B is discharged and the signal processing circuit is not activated, when the high frequency power of 6.78 MHz is received, the switch driving circuit 16 operates to supply and charge.

(Embodiment 4)
The power receiving device according to the fourth embodiment is different from the first embodiment in the configuration of the communication circuit and the connection between the switch drive circuit and the communication circuit.

  FIG. 12 is a circuit diagram of a power receiving device 10G according to the fourth embodiment.

  The communication circuit 17G included in the power receiving device 10G includes a switch circuit 14G. The switch circuit 14G is disposed between the communication circuit matching circuit 172 and the low-pass filter 173, and electrically disconnects the communication circuit matching circuit 172, the low-pass filter 173, and the communication IC 171 in order to protect the communication IC 171. . The switch circuit 14G operates by the voltage output from the switch drive circuit 16. The switch circuit 14G includes a switch element having a control terminal, and is configured by, for example, a bidirectional switch circuit. The switch element is an example of a “second switch element” according to the present invention, and the control terminal is an example of a “second control terminal” according to the present invention.

  For example, when the power receiving device 10G is not receiving high-frequency power at the operating frequency of the non-contact power supply system, the switch circuit 14G is off, and when the high-frequency power at the operating frequency of the non-contact power supply system is received, The circuit 14G is turned on, and the line before the low-pass filter 173 is configured to be short-circuited. In this configuration, the communication IC 171 can be protected from overvoltage caused by non-contact power supply.

  The switch circuit 14G may be disposed between the low-pass filter 173 and the communication IC 171 or may be built in the communication IC 171.

  In addition, the power receiving device according to the fourth embodiment may not include a common coil antenna in the contactless power supply system and the short-range wireless communication system, and may include individual coil antennas. FIG. 13 shows a receiving apparatus 10H provided with individual coil antennas 11 and 11F. A coil antenna 11F is connected to the communication circuit matching circuit 172. Even with this circuit configuration, unnecessary power supply to the load circuit 15 and the smoothing capacitor Co can be cut off by the switch drive circuit 16 and the switch circuit 14. Thus, power is supplied to the load circuit 15 only when magnetically coupled to the power supply device 20 (see FIG. 1), and the influence of the load circuit 15 and the smoothing capacitor Co on the communication circuit 17G can be suppressed. Further, the switch driving circuit 16 and the switch circuit 14G can protect the communication IC 171 from overvoltage caused by non-contact power supply.

  In Embodiments 1 to 4 described above, the power receiving device is described as a device that operates in the non-contact power supply system and the short-range wireless communication system. However, the short-range wireless communication system using different frequency bands operates. It may be a device that performs. In this case, the power receiving apparatus includes a communication circuit that performs communication using the first frequency and a communication circuit that performs communication using the second frequency. Then, the switch circuit is switched according to the frequency of the signal received by the power receiving device by the switch drive circuit described above. Similarly, the power receiving device may be a device in which a non-contact power supply system using different frequency bands operates.

  In addition, although the example of 6.78 MHz was shown as a non-contact electric power supply system, it is applicable also to the non-contact electric power feeding system using the electromagnetic induction of low frequency 10kHz-500kHz.

  Moreover, although Embodiment 1-4 demonstrated above demonstrated separating the rectifier circuit, a load circuit, and a smoothing capacitor at the time of operation | movement of a short-distance radio | wireless communications system, it is not this limitation. It is sufficient that at least the coil antenna, the load circuit and the smoothing capacitor are electrically disconnected, and the switch circuit may be provided between the coil antenna and the rectifier circuit.

  In Embodiments 1 to 4 described above, the rectifier circuit, the load circuit, and the smoothing capacitor are configured so that no current flows between the rectifier circuit, the load circuit, and the smoothing capacitor during the operation of the short-range wireless communication system. It has been described that the current path between is disconnected, but this is not the case. During operation of the short-range wireless communication system, it is sufficient to prevent unnecessary power from being supplied to the load circuit and the smoothing capacitor by at least the signal voltage for communication from the coil antenna. For example, the stage before the load circuit and the smoothing capacitor, or the rectifier circuit In the preceding stage, power may be prevented from being supplied to the load circuit and the smoothing capacitor by short-circuiting the two power supply lines so that no voltage is applied to the load circuit and the smoothing capacitor. FIG. 14 shows a power receiving device 10I in which a switch circuit 14I is connected between a power supply line 101B and a reference potential line 102B. In this circuit configuration, the switch circuit 14I is configured to be turned on when no control voltage is applied (that is, the output of the rectifier circuit 13 is short-circuited). The switch circuit 14I is turned off when a voltage is applied between the gate and the source by the switch drive circuit 16. The switch drive circuit 16 inputs a voltage across the coil antenna 11, and the communication circuit 17 divides the resonance capacitors (capacitors C21 to C24) of the matching circuit 12D of the power transmission system instead of the both ends of the coil antenna 11. Connect to the point. With this configuration, the influence of the parasitic capacitance of the rectifying unit can be eliminated.

C11, C12, C13 ... capacitors C21, C22, C23, C24 ... capacitors C31, C32, C33, C34, C35, C36, ... capacitors C41, C42 ... capacitor C5 ... capacitor Co ... smoothing capacitor CP ... connection part D1 ... diode 171 ... Communication IC
In1, In2 ... input L11 ... primary coil L12 ... secondary coils L31, L32 ... inductor Out1, Out2 ... output Q1, Q2, Q3, Q4 ... switch element R1 ... gate resistance T, TE ... transformer 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10I ... Power receiving device (circuit switching device)
DESCRIPTION OF SYMBOLS 11, 11F ... Coil antenna 12, 12D ... Matching circuit 13 ... Rectifier circuit 14, 14A, 14B, 14C, 14G, 14I ... Switch circuit 15 ... Load circuit 16, 16E ... Switch drive circuit 17, 17G ... Communication circuit 18 ... EMI Filter 20 ... Feeding device 21 ... Coil antenna 22 ... Feeding circuit 30 ... Communication device 31 ... Coil antenna 32 ... Communication circuit 100 ... Power supply system 101A, 102A ... Power supply line 102A ... Power supply line 102B ... Line for reference potential 160 ... Laminates 160A, 160B ... Coils 161, 161E ... Frequency detector (filter circuit)
162 ... Rectifier smoothing circuit (rectifier circuit)

Claims (8)

A first coil antenna;
A power receiving circuit for a non-contact power supply system connected to the first coil antenna;
A communication circuit for a short-range wireless communication system connected to the first coil antenna;
A first switch element having a first control terminal and blocking power supply from the first coil antenna to the power receiving circuit;
A detection circuit that detects a signal of a specific frequency among signals received by the first coil antenna, outputs a control voltage to the first control terminal, and directly drives the first switch element;
A circuit switching device comprising: A first coil antenna;
A power receiving circuit for a non-contact power supply system connected to the first coil antenna;
A second coil antenna magnetically coupled to the first coil antenna;
A communication circuit for a short-range wireless communication system connected to the second coil antenna;
A first switch element having a first control terminal and blocking power supply from the first coil antenna to the power receiving circuit;
A detection circuit that detects a signal of a specific frequency among signals received by the first coil antenna, outputs a control voltage to the first control terminal, and directly drives the first switch element;
A circuit switching device comprising:   The circuit switching device according to claim 1, wherein the detection circuit has a double resonance circuit.   The circuit switching device according to claim 3, wherein the multiple resonance circuit includes an insulating transformer.   2. The circuit switching device according to claim 1, wherein the communication circuit includes a second switch element that has a second control terminal and cuts off or connects power supply from the first coil antenna to the communication circuit. .   The circuit switching device according to claim 2, wherein the communication circuit includes a second switch element that has a second control terminal and cuts off or connects power supply from the second coil antenna to the communication circuit. .   The circuit switching device according to claim 5 or 6, wherein the second switch element has the second control terminal connected to the output side of the detection circuit. An input unit for inputting an AC voltage from the power supply line;
Among the voltages input from the input unit, a filter circuit that passes a voltage of a specific frequency;
A rectifier that rectifies the voltage passing through the filter circuit and outputs the rectified voltage to a control terminal of a switch element that electrically disconnects or connects the power supply line;
A switch driving circuit comprising:

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