JP6692210B2 - Electronic equipment and wireless power supply system - Google Patents

Description

  The present invention relates to an electronic device and a wireless power feeding system.

  2. Description of the Related Art In recent years, research has been conducted on implantable medical devices that perform sensing and treatment of biometric information by being implanted in the human body. In such an electronic device, if a primary battery is used as an operating power source, downsizing becomes difficult, and surgery for battery replacement is required, which imposes a heavy burden on the patient. Therefore, a technique of wirelessly supplying power to an electronic device embedded in the body is known (for example, refer to Patent Document 1).

JP, 2003-348774, A

  However, in the conventional wireless power feeding technology for electronic devices, for example, since the power of the AC power source is transmitted from the power feeding coil to the power receiving coil, the power receiving voltage may fluctuate when the coupling coefficient or the load connected to the power receiving coil changes. It was The coupling coefficient changes depending on the distance or angle between the two coils or the object existing between the coils. Further, the lighter the load on the electronic device, the more the received voltage increases. Therefore, in the conventional wireless power feeding technology for electronic devices, there is a possibility that the withstand voltage of the connected components may be exceeded due to an increase in the received voltage.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide an electronic device and a wireless power feeding system that can be stably operated by wireless power feeding.

In order to solve the above problems, one embodiment of the present invention is a power receiving coil that is fed from a power feeding coil included in a power feeding device, a rectifying unit that rectifies power fed to the power receiving coil into DC power, and the rectifying unit. A power storage device that stores the DC power rectified by a switching device, a switching element that is connected in series with a resistor to control discharge of the DC power, and a voltage of the DC power based on an allowable voltage of the power storage device. When the voltage becomes equal to or higher than the voltage, the switching element is caused to discharge the DC power through the resistor, and the voltage of the DC power is a second voltage lower than the first voltage and is stored in the power storage device. A charging / discharging control unit that stops discharging by the switching element when the voltage becomes equal to or lower than a second voltage higher than the minimum operating voltage of the load unit that operates by the generated power. An electronic device, characterized in that it comprises a.

  Further, in one aspect of the present invention, in the electronic device, the charge / discharge control unit includes a first detection unit that detects whether or not the voltage of the DC power is equal to or higher than the first voltage; When the second detection unit that detects whether or not the voltage of the electric power has become equal to or lower than the second voltage and the first detection unit that the voltage of the DC electric power has become equal to or higher than the first voltage In addition, while maintaining the state in which the DC power is discharged to the switching element, and when the second detector detects that the voltage of the DC power has become equal to or lower than the second voltage, the switching element And a self-holding unit for stopping the discharge.

  Further, according to one aspect of the present invention, in the above electronic device, the first detection unit includes a reference voltage generation unit that generates a reference voltage, the reference voltage generated by the reference voltage generation unit, and the DC power. A voltage comparison unit that detects whether or not the voltage of the DC power has become equal to or higher than the first voltage based on a comparison with a voltage obtained by dividing the voltage.

  Further, according to one embodiment of the present invention, in the above electronic device, the switching element is connected in parallel with the power storage device.

  Further, according to one aspect of the present invention, in the above electronic device, the rectifying unit, a diode connected between the power storage device, the switching element, between the rectifying unit and the diode, The DC power is discharged.

  Further, one embodiment of the present invention is characterized in that the above electronic device includes a power supply portion which supplies the electric power charged by the power storage device to the load portion in accordance with a predetermined condition.

  Further, according to one embodiment of the present invention, in the above electronic device, the power supply unit supplies the load unit with the power charged by the power storage device after power supply from the power supply coil to the power reception coil is stopped. It is characterized by supplying.

  Further, according to one embodiment of the present invention, in the above electronic device, a timer unit that counts a time period that is equal to or longer than a period in which the power storage device reaches full charge, and the power supply unit is configured such that the timer unit measures the time period. When the time is counted, the electric power charged by the power storage device is supplied to the load unit.

  One embodiment of the present invention is the above electronic device, which is a device embedded in a human body.

Further, according to one embodiment of the present invention, a power feeding device including a power feeding coil and an electronic device fed from the power feeding device are provided, and the electronic device includes a power receiving coil fed from the power feeding coil and the power receiving coil. A rectification unit that rectifies the supplied power to DC power, an electricity storage device that stores the DC power that is rectified by the rectification unit, a switching device that is connected in series with a resistor, and that controls the discharge of the DC power, When the voltage of the DC power becomes equal to or higher than a first voltage based on the allowable voltage of the electricity storage device, the switching element discharges the DC power via the resistor, and the voltage of the DC power is A second voltage that is lower than the first voltage and is equal to or lower than a second voltage that is higher than the minimum operating voltage of the load unit that operates by the electric power stored in the power storage device. A wireless power supply system, characterized in that it comprises a discharge control unit that stops the discharge by the switching element.

  Further, according to one embodiment of the present invention, in the above wireless power feeding system, the electronic device supplies the power charged by the power storage device after power feeding from the power feeding coil of the power feeding device to the power receiving coil is stopped. A power supply unit for supplying the load unit is provided.

  In addition, according to one embodiment of the present invention, in the above wireless power feeding system, the power feeding device includes a first timer portion that counts a first period in which the power storage device reaches a full charge, and the first timer portion is the first timer portion. After measuring one period, the power supply from the power feeding coil to the power receiving coil is stopped, the electronic device includes a second timer unit that counts a second period that is equal to or longer than the first period, and the power supply unit includes: When the second timer unit measures the second period, the electric power charged by the power storage device is supplied to the load unit.

  According to the present invention, stable operation can be performed by wireless power feeding.

It is a block diagram which shows an example of the wireless power supply system by 1st Embodiment. It is a figure explaining an example of operation | movement of the wireless power feeding system by 1st Embodiment. It is a flow chart which shows an example of operation of the wireless power feeding system by a 1st embodiment. It is a figure which shows the example of an apparatus which tests the wireless power feeding system by 1st Embodiment. It is a figure explaining the voltage change of the electrical storage device by 1st Embodiment. It is a figure explaining the electric current change of the electrical storage device by 1st Embodiment. It is a block diagram which shows an example of the wireless power supply system by 2nd Embodiment. It is a block diagram which shows an example of the wireless power supply system by 3rd Embodiment. It is a block diagram which shows an example of the wireless power supply system by 4th Embodiment.

An electronic device and a wireless power supply system according to an embodiment of the present invention will be described below with reference to the drawings.
[First Embodiment]
FIG. 1 is a block diagram showing an example of a wireless power feeding system 100 according to the first embodiment.
As shown in FIG. 1, the wireless power feeding system 100 includes a sensing device 1 and a power feeding device 2. The wireless power feeding system 100 is a system for wirelessly feeding power from the power feeding device 2 to the sensing device 1 wirelessly (non-contact), and for example, power for charging the power storage device 40 included in the sensing device 1 is supplied. It is supplied from the power supply device 2 to the sensing device 1.

The power supply device 2 is a device that wirelessly supplies power to the sensing device 1, and includes a power supply coil 21, a resonance capacitor 22, an AC power supply 23, and a power supply switch 24.
The power feeding coil 21 is a coil that supplies power to the power receiving coil 11 included in the sensing device 1 by, for example, electromagnetic induction or electromagnetic coupling.
The resonance capacitor 22 is a capacitor that is connected in series with the power feeding coil 21 and resonates with the power feeding coil 21. The power feeding coil 21 and the resonance capacitor 22 form a resonance circuit that resonates at a predetermined resonance frequency (for example, 1.5 MHz (megahertz)).

The AC power supply 23 outputs an AC signal having a predetermined frequency (for example, 1.5 MHz). The AC power supply 23 supplies an AC signal to the power feeding coil 21 and the resonance capacitor 22 which are connected in series via the power feeding switch 24.
The power feeding switch 24 is a switch connected between the resonance capacitor 22 and the AC power supply 23. The power supply switch 24 is turned on (conducting state) when power is supplied to the sensing device 1, and is turned off when power supply to the sensing device 1 is stopped.

The sensing device 1 (an example of an electronic device) is a device that charges (stores) electric power obtained by wireless power feeding from the power feeding device 2 into the electric storage device 40 and operates by the electric power stored in the electric storage device 40. In the present embodiment, as an example, the sensing device 1 will be described as a device that is embedded in a human body and that senses (detects) biometric information by the electric power charged in the power storage device 40.
The sensing device 1 includes a power receiving coil 11, a resonance capacitor 12, a resistor 13, a switching element 14, a load unit 15, a supply switch 16, a rectifying unit 30, a power storage device 40, and a charge / discharge control unit 50. Is equipped with.

The power receiving coil 11 is a coil to which power is fed from the power feeding coil 21 included in the power feeding device 2 by, for example, electromagnetic induction or electromagnetic coupling.
The resonance capacitor 12 is a capacitor that is connected in series with the power receiving coil 11 and resonates with the power receiving coil 11. The power receiving coil 11 and the resonance capacitor 12 form a resonance circuit that resonates at a predetermined resonance frequency (for example, 1.5 MHz). The resonance circuit in which the power receiving coil 11 and the resonance capacitor 12 are connected in series is connected to a node N1 and a node N2 of the rectifying unit 30 described later.

The rectifier unit 30 is a rectifier circuit that rectifies (converts) electric power (AC power) supplied to the power receiving coil 11 into DC power. The rectifying unit 30 includes diodes 31 to 34 and a smoothing capacitor 35.
The diodes 31 to 34 are Schottky barrier diodes, for example, and form a diode bridge circuit.

Specifically, the diode 31 has an anode terminal connected to the node N1 and a cathode terminal connected to the power supply line L1. The diode 32 has an anode terminal connected to the power supply line L2 and a cathode terminal connected to the node N1. The diode 33 has an anode terminal connected to the node N2 and a cathode terminal connected to the power supply line L1. The diode 34 has an anode terminal connected to the power supply line L2 and a cathode terminal connected to the node N2. Here, the power supply line L1 (first power supply line) is a positive power supply line of DC power that is rectified by the rectifying unit 30, and the power supply line L2 (second power supply line) is a negative electrode of DC power that is rectified by the rectifying unit 30. It is a power line.
The smoothing capacitor 35 is connected between the power supply line L1 and the power supply line L2, and smoothes the DC power rectified by the rectification unit 30.

The electricity storage device 40 is connected between the power supply line L1 and the power supply line L2, and stores (charges) the DC power rectified by the rectification unit 30. The electricity storage device 40 includes, for example, an electric double layer capacitor 41 and an electric double layer capacitor 42 connected in series.
The electric double layer capacitor 41 and the electric double layer capacitor 42 have a maximum charging voltage of, for example, 2.5 V (volt), and by connecting two in series, charging of 5 V is possible.
In the present embodiment, the voltage across the electricity storage device 40 will be referred to as voltage Vc, and the current flowing into the electricity storage device 40 will be referred to as current Ic.

The resistor 13 is connected in series with the switching element 14, the first end is connected to the power supply line L1, and the second end is connected to the drain terminal of the switching element 14. The resistance value of the resistor 13 is set to, for example, a predetermined resistance value that discharges the DC power so that the voltage Vc does not exceed the allowable voltage of the diodes 31 to 34, the smoothing capacitor 35, and the power storage device 40.
Further, the sum of the resistance 13 and the on-resistance of the switching element 14 affects the heat generation and the speed of changing from voltage V1 to voltage V2 described later. For example, when the sum of the resistance 13 and the ON resistance of the switching element 14 is small, the electric power stored in the electric storage device 40 is rapidly discharged, so that the heat generation increases, but the voltage V1 changes to the voltage V2. Since the speed is high, the time until the electricity storage device 40 is fully charged is shortened. When the sum of the resistance 13 and the ON resistance of the switching element 14 is large, heat generation is small, but the speed at which the voltage V1 changes to the voltage V2 changes slowly. Becomes longer. Therefore, the ON resistance value of the switching element 14 and the resistance value of the resistor 13 are determined in consideration of these.

The switching element 14 is, for example, an NMOS transistor (N-Channel Metal Oxide Semiconductor Field Effect Transistor). The switching element 14 is connected in series with the resistor 13 and discharges DC power via the resistor 13. That is, the switching element 14 controls the discharge of the DC power (whether or not the DC power is discharged). The switching device 14 has a source terminal connected to the power supply line L2 and a drain terminal connected to the second terminal of the resistor 13. The control terminal (gate terminal) of the switching element 14 is connected to the output line of the self-holding circuit 51 described later.
The switching element 14 is turned on (conductive) when the gate terminal is in the H (high) state, and discharges the DC power via the resistor 13. The switching element 14 is turned off (non-conducting state) when the gate terminal is in the L (low) state.

The load unit 15 operates by the electric power stored in the power storage device 40, and includes, for example, a sensor (not shown) to perform sensing of biological information. The load unit 15 is connected in series with the supply switch 16 between the power supply line L1 and the power supply line L2.
The supply switch 16 (an example of a power supply unit) supplies the power charged by the power storage device 40 to the load unit 15 according to a predetermined condition. The supply switch 16 is connected between the load unit 15 and the power supply line L2, and the conduction state is controlled by, for example, a supply control unit (not shown) to supply power to the load unit 15. The supply switch 16 supplies the electric power charged by the power storage device 40 to the load unit 15 when controlled to be in the ON state (conduction state), for example.

  The charging / discharging control unit 50 causes the switching element 14 to discharge when the voltage of the DC power (for example, the voltage Vc) becomes equal to or higher than the voltage V1 (for example, 4V), and the voltage of the DC power (for example, the voltage Vc). ) Becomes a voltage V2 (for example, 3.8 V) or less, the discharge by the switching element 14 is stopped. Here, the voltage V1 (first voltage) is an upper limit voltage based on the allowable voltage of the electricity storage device 40. Further, the voltage V2 (second voltage) is a lower voltage than the first voltage and is a lower limit voltage higher than the minimum operating voltage of the load unit 15 (for example, 2.2V).

For example, the charge / discharge control unit 50 turns on the switching element 14 to discharge the voltage Vc via the resistor 13 when the voltage Vc becomes equal to or higher than the voltage V1. Further, when the voltage Vc becomes equal to or lower than the voltage V2, the charge / discharge control unit 50 turns off the switching element 14 to stop the discharge of the voltage Vc.
The charge / discharge control unit 50 also includes an upper limit voltage detection unit 60, a lower limit voltage detection unit 70, and a self-holding circuit 51.

The upper limit voltage detection unit 60 (an example of a first detection unit) detects whether the voltage (for example, the voltage Vc) of the DC power rectified by the rectification unit 30 has become equal to or higher than the voltage V1. The upper limit voltage detector 60 includes a resistor 61, a resistor 62, a reference voltage generator 63, and a comparator 64.
The resistor 61 and the resistor 62 are connected in series between the power supply line L1 and the power supply line L2, and divide the voltage Vc between the power supply line L1 and the power supply line L2 by a predetermined resistance ratio. The resistor 61 has a first terminal connected to the power supply line L1 and a second terminal connected to the node N3. The resistor 62 has a first terminal connected to the node N3 and a second terminal connected to the power supply line L2. The resistance values of the resistors 61 and 62 are set so that the voltage of the node N3 becomes equal to a reference voltage described later when the voltage Vc is equal to the voltage V1.

The reference voltage generator 63 generates a reference voltage for comparison. The reference voltage generation unit 63 is, for example, a bandgap reference circuit having a diode or the like, and generates a reference voltage of about 1.25V, for example.
The comparator 64 (an example of a voltage comparison unit), based on the comparison between the reference voltage generated by the reference voltage generation unit 63 and the voltage obtained by dividing the voltage of the DC power (the voltage of the node N3), the voltage Vc of the DC power. Detects whether or not the voltage has become equal to or higher than V1. The + input terminal of the comparator 64 is connected to the node N3, and the − input terminal is connected to the output signal line of the reference voltage of the reference voltage generation unit 63. The output signal line of the comparator 64 is connected to the SET (set) terminal of the self-holding circuit 51.

  Further, the comparator 64 outputs the comparison result of the voltage of the node N3 and the reference voltage. For example, the comparator 64 outputs the H state to the output signal line when the voltage of the node N3 is equal to or higher than the reference voltage. Further, the comparator 64 outputs the L state to the output signal line when the voltage of the node N3 is lower than the reference voltage, for example. The comparator 64 is assumed to operate with the voltage Vc between the power supply line L1 and the power supply line L2.

The lower limit voltage detection unit 70 (an example of a second detection unit) detects whether the voltage (for example, the voltage Vc) of the DC power rectified by the rectification unit 30 has become equal to or lower than the voltage V2. The lower limit voltage detection unit 70 includes a resistor 71, a resistor 72, a resistor 73, and a transistor 74.
The resistors 71 and 72 are connected in series between the power supply line L1 and the power supply line L2, and divide the voltage Vc between the power supply line L1 and the power supply line L2 by a predetermined resistance ratio. The resistor 71 has a first terminal connected to the power supply line L1 and a second terminal connected to the node N4. The resistor 72 has a first terminal connected to the node N4 and a second terminal connected to the power supply line L2. The resistance values of the resistors 71 and 72 are set so that the voltage of the node N4 becomes equal to the threshold voltage Vth of the transistor 74 described later when the voltage Vc is equal to the voltage V2.

  The resistor 73 has a first terminal connected to the power supply line L1 and a second terminal connected to the node N5. Further, the transistor 74 has a collector terminal connected to the node N5 and an emitter terminal connected to the power supply line L2. The base terminal of the transistor 74 is connected to the node N4. The transistor 74 is turned on when the node N4 becomes equal to or higher than the threshold voltage Vth, and the node N5 is set to the L state. Further, the transistor 74 is turned off when the node N4 becomes lower than the threshold voltage Vth, and the node N5 is turned to the H state.

  In the self-holding circuit 51 (an example of the self-holding unit), the SET (set) terminal is connected to the output signal line of the comparator 64 that is the output line of the upper limit voltage detection unit 60, and the RESET (reset) terminal is the lower limit described above. It is connected to a node N5 which is an output line of the voltage detection unit 70. The self-holding circuit 51 is, for example, an SR (set / reset) latch circuit, and when the RESET terminal is in the H state, it outputs the L state to the output line to turn off the switching element 14. The self-holding circuit 51 outputs the H state to the output line when the SET terminal is in the H state, and turns on the switching element 14.

That is, the self-holding circuit 51 holds the state where the switching element 14 discharges the DC power when the upper limit voltage detection unit 60 detects that the DC power voltage becomes equal to or higher than the first voltage. In addition, the self-holding circuit 51 causes the switching element 14 to stop discharging when the lower limit voltage detection unit 70 detects that the voltage of the DC power has become equal to or lower than the second voltage.
The self-holding circuit 51 has the RESET terminal as a priority, and operates by the voltage Vc between the power supply line L1 and the power supply line L2.

Next, the operation of the wireless power supply system 100 according to the present embodiment will be described with reference to the drawings.
FIG. 2 is a diagram illustrating an example of the operation of the wireless power feeding system 100 according to the present embodiment.
In FIG. 2A, the human body BDY is fed from the power feeding device 2 to the power receiving coil 11 of the sensing device 1 embedded in the human body BDY by the waist ring type power feeding coil 21, and the power storage device 40 is charged (charged). It shows the state of performing.

  In the example shown in FIG. 2A, as a first step, power is transmitted from the waist ring type power feeding coil 21 installed so as to cover the same part of the human body BDY to the power receiving coil 11 by using, for example, electromagnetic induction. (Power is supplied), and the electricity storage device 40 of the sensing device 1 embedded in the human body BDY is charged. The power supply apparatus 2 ends the power transmission when the charging of the power storage device 40 is completed.

Next, FIG. 2B shows a state in which the sensing device 1 embedded in the human body BDY is sensing biometric information in the body using the energy stored in the power storage device 40.
In the example illustrated in FIG. 2B, the power transmission of the power feeding coil 21 is completed, and as the second step, the supply switch 16 is turned on and the load unit 15 of the sensing device 1 charges the power storage device 40 with the electric power. To start the operation. The load unit 15 senses biometric information inside the body, for example, by the electric power charged in the power storage device 40. At this time, it is assumed that power transmission (power supply) from the power feeding coil 21 to the power receiving coil 11 is stopped.

Next, FIG. 2C shows a state in which the sensing device 1 embedded in the human body BDY is transmitting the sensed biometric information outside the body.
In the example illustrated in FIG. 2C, as the third step, the load unit 15 of the sensing device 1 senses the biometric information in the body by the electric power charged in the power storage device 40, for example, via the power feeding coil 21. , To the measuring device 3 outside the human body BDY.

FIG. 3 is a flowchart showing an example of the operation of the wireless power feeding system 100 according to this embodiment.
As shown in FIG. 3, in the wireless power feeding system 100, first, power feeding is started from the power feeding device 2 (step S101). That is, as shown in FIG. 2A, the power feeding device 2 starts feeding power from the power feeding coil 21 to the power receiving coil 11 of the sensing device 1.

  Thereby, the rectification unit 30 of the sensing device 1 rectifies the AC power supplied to the power receiving coil 11 into DC power, and the DC power is stored in the power storage device 40. Since the voltage Vc is equal to or lower than the voltage V2 (for example, 3.8 V) when the power supply is started, the lower limit voltage detection unit 70 outputs the H state and the self-holding circuit 51 outputs the L state. To do. Therefore, the switching element 14 is turned off, and the voltage Vc is not discharged via the resistor 13.

Next, the power supply from the power supply device 2 is stopped (step S102). That is, the power is sufficiently stored in the power storage device 40, and the power feeding device 2 stops the power feeding from the power feeding coil 21.
Next, the power supply to the load unit 15 is started (step S103). That is, the supply switch 16 is turned on by a predetermined procedure, and the power supply from the power storage device 40 to the load unit 15 is started. As a result, the load unit 15 starts operating with the electric power charged in the power storage device 40.

Next, the load unit 15 detects (sensing) biometric information (step S104). That is, the load unit 15 detects (sensing) biometric information, as shown in FIG.
Next, the load part 15 outputs biometric information (step S105). That is, as shown in FIG. 2C, the load unit 15 transmits the detected biological information to the measuring device 3 outside the body, for example, via the power feeding coil 21. After the process of step S105, the sensing device 1 ends the process.

Next, with reference to FIG. 4, an example of an experimental environment when the sensing device 1 is artificially embedded in a human body and is operated will be described.
FIG. 4 is a diagram showing an example of a device for testing the wireless power feeding system 100 according to the present embodiment.
FIG. 4A is a sectional view showing an example of an experimental environment simulating a torso of an adult male. In addition, FIG. 4B is a side view showing an example of the experimental environment simulating the torso of an adult male. Note that, in FIG. 4, the cross section of the simulated body is the XY plane, and the direction perpendicular to the cross section is the Z direction.

As shown in FIG. 4, the experiment environment includes an acrylic container AQ and a waist ring type feeding coil 21.
The acrylic container AQ is, for example, a cylindrical container having a diameter of 240 mm in the XY plane, and is filled with a 0.25 w / v% (weight / volume%) sodium chloride aqueous solution. Inside the acrylic container AQ, the power receiving coil 11 of the sensing device 1 is arranged so as to be coaxial with the power feeding coil 21.

In addition, the power feeding coil 21 is formed, for example, by winding a conducting wire around a 290 mm acrylic cylinder 15 times. Further, the power receiving coil 11 has, for example, 15 mm × 20 mm and a thickness of 2.68 mm, and is formed by stacking three flat layers of 22 cores directly connected to each other.
The operation of the sensing device 1 of the present embodiment will be described based on such changes in the voltage Vc and the current Ic measured in the experimental environment.

FIG. 5 is a diagram illustrating a voltage change of the electricity storage device 40 according to the present embodiment.
In the graph shown in FIG. 5, the vertical axis represents the voltage Vc across the power storage device 40 measured in the experimental environment shown in FIG. 4, and the horizontal axis represents time. In addition, in this figure, it is the measurement result of the voltage Vc when the load part 15 is substituted by a resistance of 270 Ω (ohm).

  At time T1, the power feeding switch 24 of the power feeding device 2 is turned on, and power is supplied from the power feeding coil 21 to the power receiving coil 11 of the sensing device 1. The rectification unit 30 rectifies the electric power (AC power) supplied to the power receiving coil 11 into DC power, and charging of the power storage device 40 is started. As a result, the voltage Vc gradually increases as shown by the waveform W1.

  Next, at time T2, the voltage Vc reaches the voltage V1 (= 4.0V), the upper limit voltage detection unit 60 detects that the voltage Vc has become equal to or higher than the voltage V1, and the SET terminal of the self-holding circuit 51. The H state is output to. As a result, the self-holding circuit 51 outputs the H state, and the switching element 14 is turned on. As a result, the voltage Vc is discharged through the resistor 13 and drops.

  When the voltage Vc decreases and reaches the voltage V2 (= 3.8V), the lower limit voltage detection unit 70 detects that the voltage Vc has become equal to or lower than the voltage V2, and the lower limit voltage detection unit 70 causes the RESET terminal of the self-holding circuit 51 to operate. Output H state. As a result, the self-holding circuit 51 outputs the L state and the switching element 14 is turned off. As a result, the voltage Vc rises again. As described above, in the sensing device 1, the charge / discharge control unit 50 (the upper limit voltage detection unit 60, the lower limit voltage detection unit 70, and the self-holding circuit 51) causes the voltage Vc to be the voltage V1 (the upper limit voltage) and the voltage V2 (the lower limit voltage). Voltage) and maintained between.

Next, at time T3, the power supply switch 24 of the power supply device 2 is turned off, the power supply to the power receiving coil 11 is stopped, and the supply switch 16 is turned on by a predetermined procedure so that the power storage device 40 Power supply to the load unit 15 is started.
As a result, the electric power charged in the electricity storage device 40 is consumed by the load unit 15, and the voltage Vc gradually decreases.

Next, at time T4, when the operation minimum voltage Vmin (= 2.2V) of the load unit 15 is reached, the operation of the load unit 15 is stopped.
Note that in FIG. 5, the period TR1 is a charging period and the period TR2 is a discharging period.

In addition, FIG. 6 is a diagram illustrating a current change of the electricity storage device 40 according to the present embodiment.
In the graph shown in FIG. 6, the vertical axis represents the current Ic flowing into the electricity storage device 40 measured in the experimental environment shown in FIG. 4, and the horizontal axis represents time. In this figure, time T1, time T2, time T3, and time T4 are the same as in FIG. 5 described above.

A waveform W2 illustrated in FIG. 6 indicates a current Ic flowing into the power storage device 40, and the rectifier unit 30 rectifies the power supplied from the power supply device 2 into a direct current during the period TR1 from the time T1 to the time T2. , Indicating that the electricity storage device 40 is being charged.
In the period from time T2 to time T3, the charging / discharging control unit 50 (the upper limit voltage detection unit 60, the lower limit voltage detection unit 70, and the self-holding circuit 51) controls the ON state and the OFF state of the switching element 14, The current Ic of the electricity storage device 40 is repeatedly charged and discharged.
Further, in period TR2 from time T3 to time T4, current Ic of power storage device 40 is discharged by load unit 15.

  As described above, the sensing device 1 (electronic device) according to the present embodiment includes the power receiving coil 11, the rectifying unit 30, the power storage device 40, the switching element 14, and the charge / discharge control unit 50. The power receiving coil 11 is fed with power from a power feeding coil 21 included in the power feeding device 2. The rectifying unit 30 rectifies the power supplied to the power receiving coil 11 into DC power. The electricity storage device 40 stores the DC power rectified by the rectification unit 30. The switching element 14 controls the discharge of DC power. The charging / discharging control unit 50 causes the switching element 14 to discharge when the voltage of the DC power (for example, the voltage Vc) becomes equal to or higher than the voltage V1 (first voltage) based on the allowable voltage of the power storage device 40, and the DC The voltage of the electric power (for example, the voltage Vc) is a voltage V2 (second voltage) lower than the voltage V1 and is equal to or lower than a voltage V2 higher than the operation minimum voltage Vmin of the load unit 15 operated by the electric power stored in the electric storage device 40. Then, the discharge by the switching element 14 is stopped.

  As a result, the sensing device 1 according to the present embodiment causes the electricity storage device 40 to store electricity, and as shown from time T2 to time T3 in FIG. 5, by discharging the switching element 14, the voltage of the DC power (for example, the voltage Vc ) Can be maintained within the allowable voltage range of the electricity storage device 40 (and the rectifying unit 30). That is, the sensing device 1 according to the present embodiment causes the switching element 14 to discharge the voltage of DC power (for example, the voltage Vc), so that the power storage device 40 and the rectifying unit 30 are damaged by a voltage exceeding the allowable voltage. Can be suppressed. In the sensing device 1 according to the present embodiment, for example, even when the coupling coefficient changes due to the positional relationship between the power feeding coil 21 and the power receiving coil 11, a voltage exceeding the allowable voltage of the power storage device 40 and the rectifying unit 30 is detected. This can be suppressed. Therefore, the sensing device 1 according to the present embodiment can be stably operated by wireless power feeding.

Further, since the sensing device 1 according to the present embodiment can maintain the voltage of the DC power (for example, the voltage Vc) to be equal to or lower than the allowable voltage of each component used, the withstand voltage (allowable voltage) of each component used is reduced. can do. Therefore, the sensing device 1 according to the present embodiment can use a component having a low breakdown voltage, and can be downsized.
Further, in the sensing device 1 according to the present embodiment, for example, the load unit 15 that performs sensing of biological information is operated by the power stored (charged) in the power storage device 40, so that the power receiving coil 11 can be downsized. Thus, for example, when the sensing device 1 is embedded in the human body, the sensing device 1 according to the present embodiment can obtain a large operating power from the power storage device 40 while reducing the influence of the heat generation on the human body. You can

In addition, in the present embodiment, the charge / discharge control unit 50 includes an upper limit voltage detection unit 60 (first detection unit), a lower limit voltage detection unit 70 (second detection unit), and a self-holding circuit 51 (self-holding unit). Is equipped with. The upper limit voltage detection unit 60 detects whether or not the voltage of the DC power (for example, the voltage Vc) has become equal to or higher than the voltage V1. The lower limit voltage detection unit 70 detects whether or not the voltage of the DC power (for example, the voltage Vc) has become equal to or lower than the voltage V2. When the upper limit voltage detector 60 detects that the voltage Vc has become equal to or higher than the voltage V1, the self-holding circuit 51 holds the state in which the switching element 14 is discharged with the DC power, and the lower limit voltage detector 70 causes the self-holding circuit 51 to discharge. , When it is detected that the voltage Vc becomes equal to or lower than the voltage V2, the switching element 14 is caused to stop discharging.
With this, the sensing device 1 according to the present embodiment can maintain the voltage of the DC power (for example, the voltage Vc) within the range of the allowable voltage of the power storage device 40 and the rectification unit 30 with a simple configuration.

In addition, in the present embodiment, the upper limit voltage detection unit 60 includes a reference voltage generation unit 63 and a comparator 64 (voltage comparison unit). The reference voltage generator 63 generates a reference voltage. Based on the comparison between the reference voltage generated by the reference voltage generating unit 63 and the voltage obtained by dividing the voltage of the DC power, the comparator 64 determines whether the voltage of the DC power (for example, the voltage Vc) becomes the voltage V1 or more. Detect whether or not.
Thereby, in the sensing device 1 according to the present embodiment, the voltage of the DC power (for example, the voltage Vc) becomes equal to or higher than the voltage V1 based on the reference voltage generated by the reference voltage generation unit 63 even in the wireless power feeding. It can be accurately detected. Therefore, the sensing device 1 according to the present embodiment can be operated more stably by wireless power feeding.

Further, in the present embodiment, the switching element 14 is connected in parallel with the electricity storage device 40. The sensing device 1 according to the present embodiment is a device that is embedded in the human body.
As a result, the sensing device 1 according to the present embodiment discharges the voltage of the DC power (for example, the voltage Vc) by causing the switching element 14 to discharge the power storage device 40 (and the rectification unit 30). Can be maintained within the allowable voltage range. Therefore, the electricity storage device 40 is repeatedly charged and discharged for a short period of time, and the DC power supplied from the power supply device 2 is not continuously discharged by the switching element 14 for a long period of time. Further, even during the discharging by the switching element 14, the power for operating the charge / discharge control unit 50 is supplied from the power feeding device 2, so that the power fed from the power feeding device 2 can be effectively used and the power is fed from the power feeding device 2. The total amount of power can be reduced. Therefore, the sensing device 1 according to the present embodiment can reduce the heat generation of the power receiving coil 11. Therefore, the sensing device 1 according to the present embodiment can be stably operated in the human body by wireless power feeding.

  In addition, the wireless power feeding system 100 according to the present embodiment includes the power feeding device 2 including the power feeding coil 21, and the sensing device 1 fed from the power feeding device 2. The sensing device 1 includes a power receiving coil 11, a rectifying unit 30, a power storage device 40, a switching element 14, and a charge / discharge control unit 50. The power receiving coil 11 is fed with power from a power feeding coil 21 included in the power feeding device 2. The rectifying unit 30 rectifies the power supplied to the power receiving coil 11 into DC power. The electricity storage device 40 stores the DC power rectified by the rectification unit 30. The switching element 14 controls the discharge of DC power. The charging / discharging control unit 50 causes the switching element 14 to discharge when the voltage of the DC power (for example, the voltage Vc) becomes equal to or higher than the voltage V1 (first voltage) based on the allowable voltage of the power storage device 40, and the DC The voltage of the electric power (for example, the voltage Vc) is a voltage V2 (second voltage) lower than the voltage V1 and is equal to or lower than a voltage V2 higher than the operation minimum voltage Vmin of the load unit 15 operated by the electric power stored in the electric storage device 40. Then, the discharge by the switching element 14 is stopped.

  As a result, in the wireless power feeding system 100 according to the present embodiment, similarly to the sensing device 1 described above, the power storage device 40 and the rectification unit 30 are operated by causing the switching element 14 to discharge the voltage of the DC power (for example, the voltage Vc). It is possible to suppress a failure caused by a voltage exceeding the allowable voltage. Therefore, the wireless power feeding system 100 according to the present embodiment can be stably operated by wireless power feeding.

[Second Embodiment]
Next, with reference to FIG. 7, a wireless power feeding system 100a and a sensing device 1a according to the second embodiment will be described.
In the present embodiment, an example will be described in which the timer device (17, 25) causes the sensing device 1a to operate the load unit 15 after the power feeding device 2a stops feeding power to the sensing device 1a.

FIG. 7 is a block diagram showing an example of the wireless power feeding system 100a according to the present embodiment.
As shown in FIG. 7, the wireless power feeding system 100a includes a sensing device 1a and a power feeding device 2a. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

  The power supply device 2a is a device that wirelessly supplies power to the sensing device 1a, and includes a power supply coil 21, a resonance capacitor 22, an AC power supply 23, a power supply switch 24, and a timer circuit 25. The power feeding device 2a is the same as the power feeding device 2 of the above-described first embodiment except that the timer circuit 25 is provided.

The timer circuit 25 (an example of a first timer unit) measures a period (first period) when the power storage device 40 reaches full charge. The timer circuit 25 clocks a period for reaching full charge (for example, 180 seconds (seconds)) after turning on the power switch 24, and turns off the power switch 24 when the period reaches full charge. Put in a state.
As described above, in the present embodiment, the power feeding device 2a stops the power feeding from the power feeding coil 21 to the power receiving coil 11 after the timer circuit 25 clocks the first period described above.

  The sensing device 1 a (an example of an electronic device) is a device that charges (stores) electric power obtained by wireless power feeding from the power feeding device 2 a in the power storage device 40 and operates by the power stored in the power storage device 40. The sensing device 1a includes a power receiving coil 11, a resonance capacitor 12, a resistor 13, a switching element 14, a load unit 15, a supply switch 16, a rectifying unit 30, a power storage device 40, and a charge / discharge control unit 50. , And a timer circuit 17. The sensing device 1a is the same as the sensing device 1 of the first embodiment described above except that the timer device 17 is provided.

  The timer circuit 17 (an example of a second timer unit) measures a time period (second period) that is equal to or longer than a period (first period) when the power storage device 40 reaches full charge. The timer circuit 17 starts timing when power feeding from the power feeding device 2a is started, and turns on the supply switch 16 when the timing reaches a timing period (second period) longer than the period (first period). Put in a state. The timer circuit 17 is assumed to operate with the voltage Vc between the power supply line L1 and the power supply line L2.

The supply switch 16 (an example of an electric power supply unit) supplies the electric power charged by the power storage device 40 to the load unit 15 when the timer circuit 17 clocks the above-described timing period (second period). That is, the supply switch 16 supplies the electric power charged by the power storage device 40 to the load unit 15 according to a predetermined condition that the timer circuit 17 clocks the above-described time counting period (second period).
In this way, the supply switch 16 automatically supplies the power charged by the power storage device 40 to the load unit 15 after the power supply from the power supply coil 21 to the power reception coil 11 is stopped.

As described above, the sensing device 1a according to the present embodiment includes the timer circuit 17 (timer unit) that counts the time counting period that is equal to or longer than the period when the power storage device 40 reaches full charge. Then, the supply switch 16 supplies the electric power charged by the power storage device 40 to the load unit 15 when the timer circuit 17 clocks the timing period.
With this, the sensing device 1a according to the present embodiment can stably operate the load unit 15 after the power storage device 40 is fully charged by the simple configuration of the timer circuit 17.

Note that the sensing device 1a according to the present embodiment supplies the electric power charged by the power storage device 40 to the load unit 15 according to a predetermined condition (for example, the condition that the timer circuit 17 clocks the above-described clock period). The power supply switch 16 (power supply unit) is provided. That is, the supply switch 16 supplies the power charged by the power storage device 40 to the load unit 15 after the power supply from the power supply coil 21 to the power reception coil 11 is stopped.
As a result, in the sensing device 1a according to the present embodiment, the load unit 15 operates after the power supply from the power feeding coil 21 to the power receiving coil 11 is stopped, so that the wireless power carrier by wireless power feeding operates the load unit 15 (for example, It is possible to prevent the adverse effect on the sensing of biological information). Therefore, the sensing device 1a according to the present embodiment can stably operate the load unit 15 (for example, sensing biometric information) without being affected by the wireless power carrier generated by wireless power feeding.

The wireless power feeding system 100a according to the present embodiment includes the power feeding device 2a and the sensing device 1a. The power feeding device 2a includes a timer circuit 25 (first timer unit) that clocks a first period in which the power storage device 40 reaches full charge. After the timer circuit 25 clocks the first period, the power feeding coil 21 moves to the power receiving coil 11. To stop the power supply. Further, the sensing device 1a includes a timer circuit 17 (second timer unit) that measures a second period that is equal to or longer than the first period. Then, the supply switch 16 supplies the electric power charged by the power storage device 40 to the load unit 15 when the timer circuit 17 clocks the second period.
As a result, the wireless power feeding system 100a according to the present embodiment prevents the wireless power carrier from wireless power feeding from adversely affecting the operation of the load unit 15 (for example, sensing of biological information), as in the above-described sensing device 1a. can do. Therefore, the wireless power feeding system 100a according to the present embodiment can stably operate the load unit 15 (for example, sensing biometric information) without being affected by the wireless power carrier generated by wireless power feeding.

[Third Embodiment]
Next, with reference to FIG. 8, a wireless power supply system 100b and a sensing device 1b according to the third embodiment will be described.
In the present embodiment, the sensing device 1b includes the diode 18 connected between the rectifying unit 30 and the power storage device 40, and the switching element 14 discharges DC power in front of the diode 18 as an example. explain.

FIG. 8 is a block diagram showing an example of the wireless power feeding system 100b according to the present embodiment.
As shown in FIG. 8, the wireless power feeding system 100b includes a sensing device 1b and a power feeding device 2. In this figure, the same components as those shown in FIG. 1 are designated by the same reference numerals and the description thereof will be omitted.

  The sensing device 1b (an example of an electronic device) includes a power receiving coil 11, a resonance capacitor 12, a resistor 13, a switching element 14, a load unit 15, a supply switch 16, a rectifying unit 30, and a power storage device 40. The charging / discharging control unit 50 and the diode 18 are provided. The sensing device 1b is the same as the sensing device 1 of the above-described first embodiment, except that the sensing device 1b includes a diode 18 and the position where the resistor 13 and the switching element 14 are connected is different.

  The diode 18 is, for example, a Schottky barrier diode, and is connected between the rectifying unit 30 and the power storage device 40 (between the power supply line L11 and the power supply line L12). In the present embodiment, the power supply line L1 shown in FIG. 1 is described as the power supply line L11 on the front side (rectifying unit 30) side of the diode 18 and the power supply line L12 on the rear side (charge / discharge control unit 50) side of the diode 18. To do. The diode 18 has an anode terminal connected to the power supply line L11 and a cathode terminal connected to the power supply line L12.

  Further, in the present embodiment, the resistor 13 and the switching element 14 are connected between the power supply line L11 and the power supply line L2 on the preceding stage (rectifying unit 30) side of the diode 18. That is, the switching element 14 discharges DC power between the rectifying unit 30 and the diode 18. In the present embodiment, the voltage between the power supply line L11 and the power supply line L2 will be referred to as the voltage Vr, and the voltage between the power supply line L12 and the power supply line L2 will be referred to as the above-described voltage Vc.

Next, the operation of the sensing device 1b according to this embodiment will be described.
In the sensing device 1b according to the present embodiment, when the voltage Vc rectified by the rectifying unit 30 and supplied through the diode 18 reaches the voltage V1 (= 4.0V), the upper limit voltage detecting unit 60 changes the voltage Vc to It detects that the voltage has become equal to or higher than V1 and outputs the H state to the SET terminal of the self-holding circuit 51. As a result, the self-holding circuit 51 outputs the H state, and the switching element 14 is turned on.
As a result, the voltage Vr between the rectifying unit 30 and the diode 18 is discharged via the resistor 13 and drops. However, since the voltage Vc passes through the diode 18, the voltage Vc is not discharged through the resistor 13 and the output voltage of the power storage device 40 is maintained. The voltage Vc gradually decreases due to the power consumed by the charge / discharge control unit 50.

  Next, when the voltage Vc decreases and reaches the voltage V2 (= 3.8V), the lower limit voltage detection unit 70 detects that the voltage Vc has become equal to or lower than the voltage V2, and the RESET terminal of the self-holding circuit 51. The H state is output to. As a result, the self-holding circuit 51 outputs the L state and the switching element 14 is turned off. That is, the switching element 14 maintains the ON state until the power storage device 40 is in the chargeable state (the voltage Vc is equal to or lower than the voltage V2), and is set to the OFF state in the chargeable state. As a result, the voltage Vr rises again, and the charging of the electricity storage device 40 is restarted. As described above, in the sensing device 1b, the charge / discharge control unit 50 (the upper limit voltage detection unit 60, the lower limit voltage detection unit 70, and the self-holding circuit 51) intermittently discharges the voltage Vr, and the voltage Vc becomes the voltage V1 ( It is maintained between the upper limit voltage) and the voltage V2 (lower limit voltage).

As described above, the sensing device 1b according to the present embodiment includes the diode 18 connected between the rectifying unit 30 and the power storage device 40. Then, the switching element 14 discharges DC power between the rectifying unit 30 and the diode 18.
As a result, in the sensing device 1b according to the present embodiment, the electricity storage device 40 is not discharged due to the discharge of the switching element 14 through the resistor 13, so that the number of times the electricity storage device 40 is charged and discharged can be reduced. Therefore, the sensing device 1b according to the present embodiment can extend the life of the electricity storage device 40. Therefore, the sensing device 1b according to the present embodiment can be stably operated by wireless power feeding.

  In addition, the sensing device 1b according to the present embodiment causes the voltage of the DC power (for example, the voltage Vc and the voltage Vr) to be stored in the power storage device 40, and the storage device 40 (and the rectification unit 30) by discharging the switching element 14. Can be maintained within the allowable voltage range. That is, the sensing device 1b according to the present embodiment causes the switching element 14 to discharge the voltage of the DC power (for example, the voltage Vr), and the power storage device 40 and the rectifying unit 30 are damaged by the voltage exceeding the allowable voltage. Can be suppressed.

[Fourth Embodiment]
Next, a wireless power feeding system 100c and a sensing device 1c according to the fourth embodiment will be described with reference to FIG.
In the present embodiment, as in the second embodiment, in the sensing device 1c, after the power feeding from the power feeding coil 21 to the power receiving coil 11 is stopped, the electric power charged by the power storage device 40 is automatically loaded into the load unit 15. Next, another example of supplying to the above will be described.

FIG. 9 is a block diagram showing an example of the wireless power feeding system 100c according to the present embodiment.
As shown in FIG. 9, the wireless power feeding system 100c includes a sensing device 1c and a power feeding device 2. In this figure, the same components as those shown in FIGS. 1 and 8 are designated by the same reference numerals, and the description thereof will be omitted.

The sensing device 1c (an example of electronic equipment) includes a power receiving coil 11, a resonance capacitor 12, a resistor 13, a switching element 14, a load unit 15, a supply switch 16, a rectifying unit 30, and a power storage device 40. The charging / discharging control unit 50, the diode 18, and the power feeding detection unit 80 are provided. The sensing device 1c is the same as the sensing device 1 of the first embodiment described above except that the diode 18 and the power feeding detection unit 80 are provided.
The diode 18 is similar to the sensing device 1b of the second embodiment described above.

  The power feeding detection unit 80 (an example of a third detection unit) detects whether or not power is being fed from the power feeding device 2 to the power receiving coil 11. When detecting that the power feeding device 2 is not feeding power to the power receiving coil 11, the power feeding detection unit 80 turns on the supply switch 16. In addition, the power feeding detection unit 80 includes a resistor 81, a resistor 82, a resistor 83, and a transistor 84.

  The resistors 81 and 82 are connected in series between the power supply line L11 and the power supply line L2, and divide the voltage Vr between the power supply line L11 and the power supply line L2 by a predetermined resistance ratio. The resistor 81 has a first terminal connected to the power supply line L11 and a second terminal connected to the node N6. The resistor 82 has a first terminal connected to the node N6 and a second terminal connected to the power supply line L2. The resistance values of the resistors 71 and 72 are such that the voltage of the node N6 becomes equal to or higher than the threshold voltage Vth of the transistor 84 described later when the voltage Vr is supplied with power from the power receiving coil 11 via the rectifying unit 30. Has been defined.

  The resistor 83 has a first terminal connected to the power supply line L12 and a second terminal connected to the node N7. The transistor 84 has a collector terminal connected to the node N6 and an emitter terminal connected to the power supply line L2. The base terminal of the transistor 84 is connected to the node N6. The transistor 84 is turned on when the node N6 becomes equal to or higher than the threshold voltage Vth, and the node N7 is set to the L state. In addition, the transistor 84 is turned off when the node N6 is lower than the threshold voltage Vth, and the node N7 is in the H state.

  The power supply switch 16 according to the present embodiment is turned on when the power supply detection unit 80 detects that the power supply device 2 is not supplying power to the power receiving coil 11, and supplies the power charged by the power storage device 40 to the load unit. Supply to 15. Further, the supply switch 16 is turned off when the power supply detection unit 80 detects that power is being supplied from the power supply device 2 to the power receiving coil 11, and the load unit of the power charged by the power storage device 40. The supply to 15 is stopped.

As described above, the sensing device 1c according to the present embodiment includes the supply switch 16 (power supply unit) that supplies the electric power charged by the power storage device 40 to the load unit 15 according to a predetermined condition, and supplies the electric power. The switch 16 supplies the power charged by the power storage device 40 to the load unit 15 after the power supply from the power feeding coil 21 to the power receiving coil 11 is stopped.
Accordingly, in the sensing device 1c according to the present embodiment, as in the second embodiment, the load unit 15 operates after the power feeding from the power feeding coil 21 to the power receiving coil 11 is stopped, so that the wireless power carrier by wireless power feeding is generated. It is possible to prevent the operation of the load unit 15 (for example, sensing of biological information) from being adversely affected. Therefore, the wireless power feeding system 100c and the sensing device 1c according to the present embodiment can stably operate the load unit 15 (for example, sensing biometric information) without being affected by the wireless power carrier generated by wireless power feeding.

In addition, the sensing device 1c according to the present embodiment includes a power supply detection unit 80 (third detection unit) that detects whether or not the power supply device 2 is supplying power to the power reception coil 11, and the supply switch 16 includes the power supply detection unit 80. Detects that the power feeding device 2 is not feeding the power receiving coil 11, the power charged by the power storage device 40 is supplied to the load unit 15.
Accordingly, the sensing device 1c according to the present embodiment can accurately detect that the power feeding device 2 is not feeding power to the power receiving coil 11 with a simple configuration.

It should be noted that the present invention is not limited to each of the above-described embodiments, and can be modified within a range not departing from the spirit of the present invention.
For example, although each of the above-described embodiments has been described as an example of performing each independently, the present invention is not limited to this and may be performed by combining some of the embodiments. For example, when the third embodiment and the fourth embodiment are combined, the resistor 81 and the resistor 82 may be used instead of the resistor 13 and connected in series with the switching element 14. In this case, the resistors 81 and 82 and the switching element 14 can detect whether the power feeding device 2 is feeding power to the power receiving coil 11 while discharging the voltage Vr.

  Further, in each of the above-described embodiments, the example in which the switching element 14 is connected in series with the resistor 13 has been described, but the present invention is not limited to this, and the resistor 13 may not be provided. When the resistor 13 is not provided, the switching element 14 uses the on-resistance of the switching element 14 to discharge DC power. That is, the resistor 13 may be included in the ON resistance of the switching element 14.

  Further, although the electric storage device 40 has been described as an example in the case of being an electric double layer capacitor (EDLC), it may be another type of capacitor, for example, a secondary battery (storage battery) such as a lithium ion battery. It may be. Further, although the electric storage device 40 has been described as an example in which the electric double layer capacitor 41 and the electric double layer capacitor 42 are stacked in two stages in series, the present invention is not limited to this, and one stage or three stages. It may be more than a step.

  Further, in each of the above embodiments, the example in which the rectifying unit 30 is a full-wave rectifying circuit including the diodes 31 to 34 that are Schottky barrier diodes has been described, but the present invention is not limited to this. For example, the rectification unit 30 may use another type of diode instead of the Schottky barrier diode, or may be a half-wave rectification circuit.

Further, in each of the above-described embodiments, the charge / discharge control unit 50 has been described as an example in which the resistor 13 and the switching element 14 are not included, but a configuration including the resistor 13 and the switching element 14 may be used. Further, in the fourth embodiment described above, the charging / discharging control unit 50 has been described as an example that does not include the power feeding detection unit 80, but the present invention is not limited to this, and may include the power feeding detection unit 80. ..
Further, the configuration of the charge / discharge control unit 50 is not limited to the configuration described in each of the above embodiments, and may have another configuration.

Further, in each of the above-described embodiments, the example in which the upper limit voltage V1 is 4.0 V and the lower limit voltage V2 is 3.8 V has been described, but the present invention is not limited to this. V1 and voltage V2 may have other voltage values.
Further, in each of the above-described embodiments, the example of the sensing device 1 (1a to 1c) embedded in the body has been described as an example of the electronic device, but the present invention is not limited to this and is used for other purposes. It may be an electronic device.

  The above-mentioned sensing device 1 (1a-1c) has a computer system inside. The process of controlling the charging / discharging of the sensing device 1 (1a to 1c) described above is stored in a computer-readable recording medium in the form of a program, and when the computer reads and executes the program, The above processing is performed. Here, the computer-readable recording medium refers to a magnetic disk, a magneto-optical disk, a CD-ROM, a DVD-ROM, a semiconductor memory, or the like. Further, the computer program may be distributed to the computer via a communication line, and the computer that receives the distribution may execute the program.

  Further, some or all of the functions of the charge / discharge control unit 50 described above may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each of the functions described above may be individually implemented as a processor, or part or all of the functions may be integrated and implemented as a processor. Further, the method of circuit integration is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. Further, in the case where an integrated circuit technology that replaces the LSI appears due to the progress of semiconductor technology, an integrated circuit according to the technology may be used.

1, 1a, 1b, 1c Sensing device 2, 2a Power feeding device 3 Measuring device 11 Power receiving coil 12, 22 Resonant capacitor 13, 61, 62, 71, 72, 73, 81, 82, 83 Resistor 14 Switching element 15 Load part 16 Supply switch 17, 25 Timer circuit 21 Power supply coil 23 AC power supply 24 Power supply switch 30 Rectification unit 18, 31, 32, 33, 34 Diode 35 Smoothing capacitor 40 Storage device 41, 42 Electric double layer capacitor 50 Charge / discharge control unit 51 Self-holding Circuit 60 Upper limit voltage detection unit 63 Reference voltage generation unit 64 Comparator 70 Lower limit voltage detection unit 74, 84 Transistor 80 Power feeding detection unit 100, 100a, 100b, 100c Wireless power feeding system BDY Human body AQ Acrylic container

Claims (12)

A power receiving coil that is fed from a power feeding coil included in the power feeding device,
A rectifying unit that rectifies the power supplied to the power receiving coil into DC power,
An electricity storage device that stores the DC power rectified by the rectification unit,
A switching element that is connected in series with a resistor and that controls the discharge of the DC power;
When the voltage of the DC power becomes equal to or higher than a first voltage based on the allowable voltage of the electricity storage device, the switching element discharges the DC power via the resistor, and the voltage of the DC power is When the voltage is a second voltage that is lower than the first voltage and is equal to or lower than a second voltage that is higher than the minimum operating voltage of the load unit that operates by the electric power stored in the power storage device, the charging by which the discharge by the switching element is stopped is stopped. An electronic device comprising: a discharge control unit. The charge and discharge control unit,
A first detection unit that detects whether or not the voltage of the DC power is equal to or higher than the first voltage;
A second detection unit that detects whether or not the voltage of the DC power has become equal to or lower than the second voltage;
When the first detector detects that the voltage of the DC power is equal to or higher than the first voltage, the switching device holds the state of discharging the DC power, and the second detector detects The electronic device according to claim 1, further comprising: a self-holding unit that causes the switching element to stop the discharge when it is detected that the voltage of the DC power has become equal to or lower than the second voltage. .. The first detector is
A reference voltage generator that generates a reference voltage,
Based on a comparison between the reference voltage generated by the reference voltage generation unit and a voltage obtained by dividing the voltage of the DC power, it is detected whether the voltage of the DC power is equal to or higher than the first voltage. The electronic device according to claim 2, further comprising: a voltage comparison unit.   The electronic device according to any one of claims 1 to 3, wherein the switching element is connected in parallel with the power storage device. Comprising a diode connected between the rectifying unit and the electricity storage device,
The electronic device according to any one of claims 1 to 3, wherein the switching element discharges the DC power between the rectifying unit and the diode. The electronic device according to any one of claims 1 to 5, further comprising: a power supply unit that supplies the electric power charged by the power storage device to the load unit according to a predetermined condition. .. The electronic device according to claim 6, wherein the power supply unit supplies the power charged by the power storage device to the load unit after the power supply from the power supply coil to the power reception coil is stopped. .. The power storage device includes a timer unit that counts a time counting period that is equal to or longer than a period when it reaches full charge,
The electronic device according to claim 6, wherein the power supply unit supplies the power charged by the power storage device to the load unit when the timer unit counts the time period.   The electronic device according to any one of claims 1 to 8, which is a device embedded in a human body. A power feeding device having a power feeding coil, and an electronic device fed from the power feeding device,
The electronic device is
A receiving coil fed from the feeding coil,
A rectifying unit that rectifies the power supplied to the power receiving coil into DC power,
An electricity storage device that stores the DC power rectified by the rectification unit,
A switching element that is connected in series with a resistor and that controls the discharge of the DC power;
When the voltage of the DC power becomes equal to or higher than a first voltage based on the allowable voltage of the electricity storage device, the switching element discharges the DC power via the resistor, and the voltage of the DC power is When the voltage is a second voltage that is lower than the first voltage and is equal to or lower than a second voltage that is higher than the minimum operating voltage of the load unit that operates by the electric power stored in the power storage device, the charging by which the discharge by the switching element is stopped is stopped. A wireless power supply system comprising: a discharge control unit. The electronic device is
The power supply unit configured to supply the power charged by the power storage device to the load unit after the power supply from the power supply coil to the power reception coil of the power supply apparatus is stopped. Wireless power supply system. The power feeding device includes a first timer unit that counts a first period in which the power storage device reaches full charge, and after the first timer unit clocks the first period, power feeding from the power feeding coil to the power receiving coil is performed. Stop,
The electronic device includes a second timer unit that counts a second period that is equal to or longer than the first period,
The wireless power supply device according to claim 11, wherein the power supply unit supplies the electric power charged by the power storage device to the load unit when the second timer unit counts the second period. Power supply system.

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