KR101372970B1 - Method for detecting metal foreign object on contactless power supply device, contactless power supply device, contactless power reception device, and contactless power supply system - Google Patents

Abstract

A method for detecting a metal foreign object is disclosed. A metal detection circuit (33) installed in a contactless power supply device (1) transmits an oscillation signal (Φt) to a modulation circuit (16) of an electric appliance (E), and the modulation circuit (16) of the modulation circuit (16) generates a square wave pulse signal (MP) from the oscillation signal (Φt). The cycle of the oscillation signal (Φt) received by the modulation circuit (16) changes in accordance with whether a metal piece (8) is present. The modulation circuit (16) modulates the square wave pulse signal (MP) to generate a modulated wave signal (Φm) and transmits the modulated wave signal (Φm) to the metal detection circuit (33) of the power supply device (1). The metal detection circuit (33) demodulates the modulated wave signal (Φm) and determines whether a metal piece (8) is present based on the cycle (Tn) of the demodulated signal (DMP) corresponding to the square wave pulse signal (MP). [Reference numerals] (15) Power receiving circuit; (16) Modulation module; (31) Power circuit; (32) Power supply circuit; (33) Metal detection circuit; (34) System control unit; (Z) Load

Description

METHOD FOR DETECTING METALLIC FOOT IN NON-CONTACT POWER SUPPLY DEVICES, NON-CONTACT POWER SUPPLY DEVICES, RECIPES AND CONTACTLESS POWER SUPPLY DEVICE, CONTACTLESS POWER SUPPLY DEVICE, CONTACTLESS POWER RECEPTION DEVICE, AND CONTACTLESS POWER SUPPLY SYSTEM}

The present invention relates to a method for detecting metal foreign matter in a non-contact power supply device, a non-contact power supply device, a power receiving device, and a non-contact power supply system.

In recent years, practical use of the non-contact electric power feeding system by the electromagnetic induction system is progressing.

A non-contact power feeding system by an electromagnetic induction system includes a non-contact power feeding device including a primary coil and a power receiving device including a secondary coil. In the state where the electric machine provided with a power receiving device was mounted on the mounting surface of the non-contact power feeding device, the non-contact power feeding device excites the primary coil, and energizes the secondary coil provided in the power receiving device of the electric device by electromagnetic induction. Secondary power generated in the secondary coil is converted into direct current power in the power receiving device. The DC power is supplied as a drive power source for the load of the electric device.

By the way, when a metal foreign material exists between a non-contact electric power feeding device and an electrical device (electric power receiving device), a metal foreign material may inductively heat during power feeding. Therefore, some non-contact power supply devices include a metal detection device that detects metal foreign matter. When the metal detecting device detects a metal foreign substance, the non-contact power feeding device stops feeding.

The metal detection device provided in the non-contact power supply device excites the primary coil of the non-contact power supply device at a predetermined frequency that differs from the frequency at the time of power supply, for example. When metal foreign matter exists, it is known that the inductance of the primary coil excited by the predetermined frequency changes. The metal detection device stops feeding when it detects that metal foreign matter exists by using the change in inductance (Japanese Patent Laid-Open No. 2000-295796).

However, the metal detection device excites the primary coil of the non-contact power supply device at an excitation frequency for detecting metal foreign matter, which is different from the excitation frequency at the time of power supply. Therefore, in the non-contact power supply device, it is necessary to set a plurality of excitation frequencies for exciting the primary coil, and it is necessary to switch the excitation frequency every time the metal foreign matter detection is performed. Therefore, the circuit which drives an excitation drive of a primary coil becomes complicated, and there existed a problem that a non-contact power feeding device became expensive.

In addition, the metal detecting apparatus must detect a change in inductance of the primary coil, that is, a change in resonant frequency of the oscillation circuit including the primary coil, in order to detect metal foreign matter, so that an amplifier or a processor which processes the signal at high speed Since it requires, the non-contact power feeding device became more expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problem, and its object is to detect metal foreign matters without changing the excitation frequency of the power supply coil of the non-contact power supply device, and to detect metal foreign matters of the non-contact power supply device, which can be manufactured at low cost. To provide a method.

Another object of the present invention is to provide a non-contact power supply device, a power receiving device, and a non-contact power supply system for use in a method for detecting a metal foreign substance in the non-contact power supply device.

One aspect of the present invention provides a method for detecting whether a metal foreign material is present on a non-contact power feeding device that feeds power using an electromagnetic induction phenomenon to a power receiving device included in an electric device. The method includes the non-contact power feeding device transmitting an oscillation signal to the power receiving device, detecting, from the oscillation signal received by the power receiving device, a modulated wave caused by a change in magnetic flux due to the presence of a metal foreign material, and modulating the modulation. In order to transmit the wave to the non-contact power supply device, a modulated wave signal is generated by modulating a carrier signal according to the modulated wave, and the power receiver device transmits the modulated wave signal to the non-contact power supply device, and transmits from the power receiver. Receiving said modulated wave signal, and determining whether or not a metal foreign material exists in accordance with the demodulated signal demodulated from said modulated wave signal.

In one example, the modulated wave is a square wave pulse signal having a period changed in accordance with a change in magnetic flux due to the presence of a foreign metal in the oscillation signal received by the power receiving device, the modulated wave signal is the amplitude of the carrier signal The demodulation signal is generated by amplitude modulation in proportion to the square wave pulse signal, and the demodulation signal is a square wave pulse signal generated by envelope detection of the modulated wave signal.

In one example, the carrier signal is the oscillation signal transmitted from the non-contact power feeding device to the power receiving device.

In one example, the carrier signal is an electromagnetic signal according to a feed current supplied from the primary coil of the non-contact power supply device to the secondary coil of the power receiving device by using an electromagnetic induction phenomenon, the modulated wave signal is modulated by the electromagnetic signal This is a signal that overlaps waves.

Another aspect of the present invention provides a non-contact power feeding device that feeds power using an electromagnetic induction phenomenon to a power receiving device included in an electric device. This non-contact power supply device includes an oscillation circuit for transmitting an oscillation signal to the power reception device; From the power receiving device that has received the oscillation signal, a modulated wave signal obtained by modulating the oscillation signal by a modulated wave according to a change in magnetic flux is received, detects the modulated wave signal, and demodulates the modulated wave detected by the power receiver. Detection circuit; A frequency detection circuit for detecting a frequency of the modulated wave demodulated by the detection circuit; And a determination circuit that determines whether or not a metal foreign matter exists in accordance with the frequency of the demodulated modulated wave detected by the frequency detection circuit.

In one example, the modulated wave is a square wave pulse signal having a period changed in accordance with a change in magnetic flux due to the presence of a foreign metal in the oscillation signal received by the power receiving device, wherein the modulated wave signal is the amplitude of the carrier signal. Wherein the detection circuit is configured to demodulate the square wave pulse signal by envelope detection of the modulated wave signal, and the frequency detection circuit demodulates the square wave pulse demodulated by the detection circuit. A circuit for detecting a period of the signal, wherein the determining circuit determines whether or not a metal foreign matter exists in accordance with the period of the square wave pulse signal detected by the frequency detecting circuit.

Another aspect of the present invention is provided in an electrical apparatus, and the power receiving device provides a power receiving device that receives power from a non-contact power feeding device using an electromagnetic induction phenomenon. This power receiving device includes: an oscillation signal receiving circuit that receives an oscillation signal for detecting whether there is a metal foreign material transmitted from the non-contact power supply device; A modulated wave signal generation circuit for generating a modulated wave according to a change in magnetic flux due to the presence of a foreign metal in the oscillation signal received by the oscillation signal receiving circuit; And a modulated wave signal generation circuit for generating a modulated wave signal by modulating a carrier signal according to the modulated wave to transmit the modulated wave to the non-contact power supply device.

In one example, the modulated wave is a square wave pulse signal, and the modulated wave signal generating circuit is configured to generate the square wave pulse signal having a period changed from the received oscillation signal according to a change in magnetic flux due to the presence of a metal foreign material. The modulated wave signal is generated by amplitude modulating the amplitude of the carrier signal in proportion to the square wave pulse signal, and the modulated wave signal generating circuit modulates the amplitude of the carrier signal in proportion to the square wave pulse signal. And generate the modulated wave signal.

The present invention is also suitable for a non-contact power supply system including the power receiving device and the non-contact power supply device.

Other aspects and advantages of the invention will be apparent from the following description taken in conjunction with the drawings showing examples of the principles of the invention.

The characteristics considered to be novel of this invention become clear especially in the attached Claim. BRIEF DESCRIPTION OF THE DRAWINGS The present invention with its objects and advantages is understood by referring to the accompanying drawings for description of the embodiments shown below.
1 is a perspective view of a power supply device and an electrical apparatus of a non-contact power supply system.
2 is a cross-sectional view of a power supply device and an electrical device.
3 is a block diagram of a power feeding device and an electrical device.
4 is a block diagram of a power receiving circuit installed in an electric device.
5 is a block diagram of a modulation circuit installed in an electric device.
6 is an electrical circuit diagram of a rectifier circuit and a modulation circuit included in a modulation circuit of an electric device.
7 is an electric circuit diagram of a modulated wave signal generation unit included in a modulation circuit of an electric device.
8 is a block diagram of a power supply circuit and a metal detection circuit provided in the power supply device.
9A, 9B, 9C, and 9D are waveform diagrams of an oscillation signal, a square wave pulse signal, a modulated wave signal, and a demodulation signal when a metal piece is not present.
(E), (f), (g), (h) are waveform diagrams of an oscillation signal, a square wave pulse signal, a modulated wave signal, and a demodulation signal when there is a metal piece.

EMBODIMENT OF THE INVENTION Hereinafter, the Example of the non-contact power supply system of this invention is described according to drawing.

The non-contact power supply system shown in FIG. 1 includes a non-contact power supply device (hereinafter simply referred to as a power supply device) 1 and an electric device (hereinafter referred to simply as a device) E that is contactlessly fed from the power supply device 1. Include. The housing 2 of the power feeding device 1 is formed by a rectangular box 3 having an upper opening and a ceiling plate 4 made of an insulator (for example, tempered glass) that closes and closes the opening. It is. The upper surface of the ceiling plate 4 functions as the mounting surface 5 on which the device E is mounted at the time of non-contact power feeding. In the housing 2, as shown in FIG. 2, the primary coil L1 is provided on the rear surface of the ceiling plate 4. There is one primary coil L1 in this embodiment, and it is arrange | positioned in parallel with the mounting surface 5 of the ceiling plate 4.

When the device E is mounted on the mounting surface 5, the secondary coil L2 provided in the device E is excited and energized by electromagnetic induction by the excitation of the primary coil L1 of the power feeding device 1. do. Secondary electric power induced in the secondary coil L2 by electromagnetic induction is input to the power receiving circuit 15 (see FIG. 3) installed in the device E, and is free of ripple by the power receiving circuit 15. It is converted into a DC voltage and supplied to the load Z of the device E.

Moreover, the power supply side 1st communication antenna coil (henceforth a power supply side 1st antenna coil) 6a is provided in the back surface of the ceiling board 4 so that the primary coil L1 may be enclosed. Data and / or information is transmitted by wireless communication between the power feeding side first antenna coil 6a and the power receiving side first communication antenna coil (hereinafter referred to as the power receiving side first antenna coil) 6b provided in the device E. It is sent and received.

In one example, when the device E is mounted on the mounting surface 5, data and / or information are transmitted and received by wireless communication between the power feeding side first antenna coil 6a and the power receiving side first antenna coil 6b. do.

In the present embodiment, the device E wirelessly transmits the device authentication signal ID and the excitation request signal RQ from the power receiving side first antenna coil 6b. The device authentication signal ID may include identification information of the device E receiving the power supply from the power supply device 1. The excitation request signal RQ requests the power supply device 1 to supply power. The power supply side first antenna coil 6a receives the device authentication signal ID and the excitation request signal RQ.

On the upper surface of the ceiling plate 4, that is, the mounting surface 5 (which may be the rear surface of the ceiling plate 4), the power supply side second communication antenna coil (hereinafter referred to as the power supply side second antenna coil) 7a Formed. The power feeding side second antenna coil 7a is formed on the mounting surface 5 by, for example, a known printed wiring technique. Data and / or information by wireless communication between the power feeding side second antenna coil 7a and the power receiving side second communication antenna coil (hereinafter referred to as the power receiving side second antenna coil) 7b provided in the device E. Is transmitted and received.

In one example, when the device E is mounted on the mounting surface 5, a metal piece (metal) on the mounting surface 5 between the power feeding side second antenna coil 7a and the power receiving side second antenna coil 7b. A signal is transmitted and received for detecting whether or not the foreign matter 8 is present.

In the present embodiment, the oscillation circuit 33a (see FIG. 8) of the power feeding device 1 oscillates an oscillation signal .phi.t (see FIG. 9) for detecting the metal piece 8, and this oscillation signal .phi.t. Is transmitted from the power feeding side second antenna coil 7a. The power receiving side second antenna coil 7b of the device E receives the oscillation signal .phi.t. The modulation circuit 16 (see FIG. 3) of the device E modulates the received oscillation signal .phi.t, generates a modulated signal (modulated wave signal) .phi.m (see FIG. 9). The to-be-modulated wave signal? M (see Fig. 9) is transmitted from the power receiving side second antenna coil 7b to the power feeding side second antenna coil 7a.

In the example shown in FIG. 2, a printed wiring board 10 is disposed on an inner bottom surface of the housing 2, and the printed wiring board 10 is mounted on a power supply circuit 31 and a mounting surface 5. A power supply circuit 32 for supplying electric power to the device E by electromagnetic induction, a metal detection circuit 33 for cooperatively detecting the metal piece 8 on the mounting surface 5 with the device E, and a power supply The system control part 34 which consists of microcomputers which collectively control the apparatus 1 is mounted.

Next, an electrical configuration of the power supply device 1 and the device E will be described with reference to FIGS. 3 to 8.

As shown in FIG. 3, the device E includes a power receiving circuit 15 for receiving secondary power from the power feeding device 1 and a load Z for driving with secondary power received by the power receiving circuit 15. And a modulation circuit 16 for generating a modulated wave signal .phi.m for detecting a metal piece.

An example power receiving device may include a secondary coil L2 and a power receiving circuit 15. Another example of a power receiving device may include a secondary coil L2, a power receiving circuit 15, and a modulation circuit 16. Another example of a power receiving device is a device E without a load. The entire apparatus E may be called a power receiving device.

The power receiving circuit 15 receives secondary power from the primary coil L1 through the secondary coil L2 and supplies a driving voltage to the load Z. As shown in FIG. 4, the power receiving circuit 15 includes a rectifying smoothing circuit 15a, a data generating circuit 15b, and a transmitting circuit 15c.

The rectification smoothing circuit 15a is connected to the secondary coil L2. The rectification smoothing circuit 15a converts the secondary power excited by the electromagnetic induction of the primary coil L1 of the power feeding device 1 to the secondary coil L2 into a direct current voltage without ripple, This DC voltage is supplied to the load Z of the device E.

The load Z may be a device that is driven by secondary power generated by the secondary coil L2. For example, the load Z may be a device to be driven on the mounting surface 5 using the rectified DC voltage, or may be a device to be driven on the mounting surface 5 using the secondary power as an AC power source as it is. The device may be charged with a built-in rechargeable battery (secondary battery) at a rectified DC voltage.

In a non-limiting example, the rectifying smoothing circuit 15a can function as a drive source for supplying the rectified DC voltage to the data generating circuit 15b and the transmitting circuit 15c.

The data generation circuit 15b is a circuit which generates the device authentication signal ID and the excitation request signal RQ and supplies them to the transmission circuit 15c. The device authentication signal ID is an authentication signal for the purpose of the device E, which is supplied with power by the power supply device 1 to the power supply device 1. The excitation request signal RQ is a request signal for requesting the power feeding device 1 to feed power.

The data generating circuit 15b is, for example, when the rectifying smoothing circuit 15a is outputting a DC power supply or when the data generating circuit 15b can be driven by a secondary battery or the like built in the device E. And the excitation request signal RQ are generated and supplied to the transmission circuit 15c. In addition, the data generation circuit 15b generates the device authentication signal ID and the excitation request signal RQ when the power switch for driving the load Z, for example, provided in the device E is turned off. I never do that.

In addition, when the microcomputer is installed in the apparatus E, when the microcomputer is installed in the apparatus E, and it is determined that power supply is to be stopped by the microcomputer's judgment, the apparatus authentication signal ID and the excitation request signal are carried out. Do not generate (RQ).

The transmission circuit 15c is connected to the power receiving side first antenna coil 6b. The transmission circuit 15c transmits the device authentication signal ID and the excitation request signal RQ supplied from the data generation circuit 15b to the power supply device 1 via the power receiving side first antenna coil 6b.

The device E has a modulation circuit 16 which modulates the oscillation signal .phi.t transmitted from the power feeding device 1 and received by the power receiving side second antenna coil 7b. As shown in FIG. 5, the modulation circuit 16 generates a square wave pulse signal MP according to the rectifying circuit 16a for rectifying the oscillation signal .phi.t and the rectified current rectified by the rectifying circuit 16a. The oscillation signal? T is modulated according to the modulated wave signal generating circuit 16b and the square wave pulse signal MP generated by the modulating wave signal generating circuit 16b, and the modulated signal (modulated wave signal)? M It includes a modulator 16c for generating a.

In the example shown in FIG. 6, the rectifier circuit 16a is a half-wave rectifier circuit, and has a rectifier diode D0, a charge / discharge capacitor C0, and a resistor R0. The anode terminal of the rectifying diode D0 is connected to the positive terminal PT of the second antenna coil 7b on the receiving side, and the cathode terminal of the rectifying diode D0 is connected to both terminals of the charge / discharge capacitor C0. It is. The negative terminal of the charge / discharge capacitor C0 is connected to the negative electrode terminal NT of the power receiving side second antenna coil 7b. The resistor R0 is connected in parallel with the charge / discharge capacitor C0. The rectifier circuit 16a receives the oscillation signal .phi.t transmitted from the power feeding side second antenna coil 7a of the power feeding device 1 through the power receiving side second antenna coil 7b, and receives the received oscillation signal ( Φt) is half-wave rectified.

As shown in Fig. 9A, the oscillation signal? T transmitted from the power feeding device 1 can be a sinusoidal file having a constant amplitude value and a constant frequency. When the oscillation signal .phi.t received by the power receiving side second antenna coil 7b is half-wave rectified by the rectifying diode D0, the charge / discharge capacitor C0 repeats charging and discharging. For example, when the oscillation signal .phi.t is at the positive potential, the charge / discharge capacitor C0 is charged by the current from the rectifying diode D0. When the oscillation signal .phi.t is at the negative potential, the charge charged in the charge / discharge capacitor C0 is discharged through the resistor R0.

When the frequency of the oscillation signal .phi.t changes, the charge / discharge time of the charge / discharge capacitor C0 varies. For example, when the metal piece 8 exists between the power supply side 2nd antenna coil 7a and the power receiving side 2nd antenna coil 7b in the state in which the apparatus E was mounted on the mounting surface 5, The frequency of the oscillation signal .phi.t received by the side second antenna coil 7b varies from the frequency of the oscillation signal .phi.t transmitted from the power feeding device 1.

The frequency of the oscillation signal .phi.t transmitted from the power feeding device 1 may be referred to as a first frequency. The frequency of the oscillation signal .phi.t received by the power receiving side second antenna coil 7b may be referred to as a second frequency. The second frequency is the same as the first frequency when the metal piece 8 is not present, but is different from the first frequency when the metal piece 8 is present. For example, when the metal piece 8 does not exist, as shown in Fig. 9A, the oscillation signal? T having the same frequency as the first frequency oscillated by the oscillation circuit 33a is received on the power receiving side. It is received by two antenna coils 7b. On the other hand, when the metal piece 8 is present, as shown in Fig. 9E, the oscillation signal? T having a relatively low frequency, which is different from the first frequency of the oscillation circuit 33a, oscillates on the power receiving side. Two antenna coils 7b are received.

This means that the charge / discharge time (cycle of charge / discharge) of the charge / discharge capacitor C0 becomes long because the frequency of the oscillation signal .phi.t decreases due to the presence of the metal piece 8. That is, the period of the charge voltage waveform of the charge / discharge capacitor C0 when the metal piece 8 is present becomes longer than when the metal piece 8 is not present. The charging voltage Vt of this charge / discharge capacitor C0 is applied as the power supply voltage VG to the modulation wave signal generation circuit 16b.

The modulated wave signal generation circuit 16b can be configured by the unstable multivibrator 20, as shown in FIG. The unstable multivibrator 20 may be a known multivibrator composed of two transistors Q1 and Q2, two capacitors C1 and C2, and four resistors R1a, R1b, R2a, and R2b.

The charging voltage Vt of the charge / discharge capacitor C0 is applied as the power supply voltage VG to the power supply line 21 of the unstable multivibrator 20. The unstable multivibrator 20 of this embodiment supplies the square wave pulse signal MP (modulation wave) to the modulator 16c from the collector terminal of the transistor Q1.

That is, when the transistor Q1 of the unstable multivibrator 20 is turned on, the potential between the base and emitter of the transistor Q2 changes the power supply voltage VG at the threshold voltage (for example, 0.7 volt). The value is minus, and the transistor Q2 is turned off. Then, a current flows through the capacitor C1 through the resistor R1b, and the capacitor C1 is charged to increase the potential between the base and the emitter of the transistor Q2. Then, when the potential between the base emitter of transistor Q2 exceeds the threshold, transistor Q2 is turned on.

As the transistor Q2 is turned on, the potential between the base and emitter of the transistor Q1 becomes the value obtained by subtracting the power supply voltage VG from the threshold voltage, and the transistor Q1 is turned off. Then, a current flows through the capacitor C2 through the resistor R2b to charge the capacitor C2, and the potential between the base and the emitter of the transistor Q1 rises. When the potential of P exceeds the threshold, transistor Q1 is turned on and transistor Q2 is turned off.

By repeating this, the unstable multivibrator 20 continues to output the square wave pulse signal MP from the collector terminal of the transistor Q1 (also the transistor Q2).

At this time, in this embodiment, the time when the transistor Q1 (which is similar to the transistor Q2) turns from off to on is the time required for the potential between the base and the emitter of the transistor Q1 to exceed the threshold. Depends on In other words, the time when the transistor Q1 turns from off to on depends on the power supply voltage VG charged to the capacitor C1 through the resistor R1b.

By the way, since the unstable multivibrator 20 uses the charging voltage Vt of the charge / discharge capacitor C0 as the power supply voltage VG, the period of a power supply voltage waveform fluctuates. As a result, the period Tn of the square wave pulse signal MP output from the collector of the transistor Q1 is varied.

That is, when the metal piece 8 is not present, since the oscillation signal phi t of the frequency shown in Fig. 9A is received, the unstable multivibrator 20 has a power supply voltage having a short cycle of the power supply voltage waveform. VG) is applied. In this case, since the potential between the base emitters of the transistors Q1 and Q2 exceeds the threshold in a relatively short time, the unstable multivibrator 20 has a relatively short period Tn shown in Fig. 9B. Outputs a square wave pulse signal MP having

On the other hand, when the metal piece 8 is present, since the oscillation signal phi t of the relatively low second frequency shown in Fig. 9E is received, the unstable multivibrator 20 has a long cycle of the power supply voltage waveform. The power supply voltage VG is applied. In this case, since the potential between the base emitters of the transistors Q1 and Q2 exceeds the threshold over a relatively long time, the unstable multivibrator 20 has a relatively long period Tn shown in FIG. Outputs a square wave pulse signal MP having

As described above, when the metal piece 8 is present, the unstable multivibrator 20 supplies the square wave pulse signal MP with a longer period Tn to the collector terminal of the transistor Q1 than in the case where the metal piece 8 is not present. Output from

The unstable multivibrator 20 supplies a square wave pulse signal MP to the modulator 16c.

As shown in FIG. 6, the modulator 16c includes a transistor Q3 and a diode D1. The anode terminal of the diode D1 is connected to the anode terminal of the rectifying diode D0 of the rectifier circuit 16a and the positive terminal PT. The cathode terminal of the diode D1 is connected to the collector terminal of the transistor Q3. The base terminal of the transistor Q3 is connected to the transistor Q1 of the unstable multivibrator 20, and the emitter terminal is grounded. The transistor Q3 is turned on and off in accordance with the square wave pulse signal MP from the unstable multivibrator 20 supplied to the base terminal.

When the transistor Q3 is turned on, a part of the charging current charged in the charge / discharge capacitor C0 through the rectifying diode D0 flows through the diode D1 to the transistor Q3 (modulator 16c). On the contrary, when the transistor Q3 is turned off, the charging current charged in the charge / discharge capacitor C0 through the rectifying diode D0 does not flow to the transistor Q3 (modulator 16c), and the rectifying diode ( Flows through the charge / discharge capacitor C0 through D0).

As a result, the secondary current flowing between the two terminals PT and NT of the power receiving side second antenna coil 7b changes according to the oscillation signal .phi.t by the on / off of the transistor Q3. By the change of the secondary current, the magnetic flux generated by the power receiving side second antenna coil 7b changes, and the changed magnetic flux propagates as electromagnetic induction to the power feeding side second antenna coil 7a, and the power feeding side second The primary current flowing through the antenna coil 7a is changed.

That is, the current flowing between the two terminals PT and NT of the power receiving side second antenna coil 7b by the on / off of the transistor Q3 (by the period Tn of the square wave pulse signal MP) Oscillation signal? T is amplitude modulated. The modulated wave signal? M is transmitted from the power receiving side second antenna coil 7b to the power feeding side second antenna coil 7a.

In the illustrated example, the oscillation signal? T received by the power receiving side second antenna coil 7b constitutes a carrier signal. The square wave pulse signal MP generated according to the frequency of this carrier signal in the device E is an example of a modulated wave. The modulator 16c modulates the amplitude of the carrier signal (oscillation signal? T) in proportion to the modulated wave (square wave pulse signal MP), thereby modulating the wave to be shown in Fig. 9 (c) or (g). Generate the signal .phi.m.

For example, the modulator 16c modulates the amplitude of the carrier signal (oscillation signal .phi.t) in accordance with the square wave pulse signal MP shown in FIG. Generates a modulated wave signal Φ m. On the other hand, the modulator 16c modulates the amplitude of the carrier signal (oscillation signal .phi.t) in accordance with the square wave pulse signal MP shown in Fig. 9F, thereby modulating the wave shown in Fig. 9G. Generate the signal .phi.m.

In this way, the envelope waveform of the modulated wave signal .phi.m has a period corresponding to the period Tn of the square wave pulse signal MP (modulation wave).

In FIG. 3, the power supply device 1 has a power supply circuit 31, a power supply circuit 32, a metal detection circuit 33, and a system control unit 34.

The power supply circuit 31 has a rectifier circuit and a DC / DC converter.

The power supply circuit 31 rectifies the commercial power supplied from the outside by the rectifying circuit, converts the rectified DC voltage into a desired voltage by the DC / DC converter, and converts the DC voltage as a driving power supply to the system control unit 34, Supply to power supply circuit 32 and metal detection circuit 33.

The power supply circuit 32 has a receiving circuit 32a, a signal extraction circuit 32b, and an excitation drive circuit 32c, as shown in FIG.

The receiving circuit 32a is connected to the power feeding side first antenna coil 6a. The reception circuit 32a receives a signal transmitted from the power receiving side first antenna coil 6b of the device E mounted on the mounting surface 5 via the power supply side first antenna coil 6a, and receives the received signal. One signal is supplied to the signal extraction circuit 32b.

The signal extraction circuit 32b extracts the device authentication signal ID and the excitation request signal RQ from the transmission signal. When the signal extraction circuit 32b extracts two signals of the device authentication signal ID and the excitation request signal RQ from the transmission signal, the signal extraction circuit 32b supplies the permission signal EN to the system control unit 34. In addition, when the signal extraction circuit 32b extracts only one of the device authentication signal ID and the excitation request signal RQ, or both signals are not extracted, the signal control circuit 32b sends the permission signal EN to the system control unit 34. Do not supply).

The excitation drive circuit 32c is connected to the primary coil L1, and in this embodiment, this half coil circuit is comprised by this primary coil L1. Therefore, the excitation drive circuit 32c has switching transistors such as two MOS transistors.

The excitation signals PS1 and PS2 each consisting of pulse signals for turning on and off are supplied from the system control unit 34 to the gate terminals of the two transistors. The excitation signals PS1 and PS2 respectively input to the gate terminals of the two transistors are complementary signals, and when one transistor is turned on in response to one excitation signal, the other transistor is turned off in response to the other excitation signal. .

In one example, while the device E is mounted on the mounting surface 5, and the signal extraction circuit 32b continues to supply the permission signal EN to the system control unit 34, the system control unit 34 performs the excitation signal. Continue to supply (PS1, PS2). In this case, therefore, the excitation drive circuit 32c continuously excites the primary coil L1.

In addition, when the device E is not mounted on the mounting surface 5, the system control unit 34 intermittently outputs the excitation signals PS1 and PS2 for a predetermined period. In this case, therefore, the excitation drive circuit 32c intermittently drives the primary coil L1 at regular intervals.

The intermittent excitation drive of the primary coil L1 is not secondary power that can immediately drive the load Z of the device E when the device E is mounted on the mounting surface 5. The secondary power supply is enough to charge the charger of (Z). Then, the data generation circuit 15b and the transmission circuit 15c of the device E for performing wireless communication between the power supply devices 1 are driven in accordance with the charging voltage.

Moreover, even if the metal piece 8 exists in the mounting surface 5, this intermittent excitation drive of this primary coil L1 does not make the metal piece 8 inductively heat, and makes it high temperature.

In addition, when the signal extraction circuit 32b is not outputting the permission signal EN, the excitation drive circuit 32c has a primary order as in the case where the device E is not mounted on the mounting surface 5. The coil L1 is intermittently excited.

In addition, the excitation drive circuit 32c is not equipped with the device E on the mounting surface 5 when the metal presence signal ST is being supplied from the metal detection circuit 33 to the system control unit 34. As in the case, the primary coil L1 is intermittently excited. Therefore, even if the metal piece 8 exists in the mounting surface 5, since the primary coil L1 is an intermittent excitation drive, it does not inductively heat the metal piece 8 to high temperature.

The metal detection circuit 33 has the oscillation circuit 33a, the detection circuit 33b, the frequency detection circuit 33c, and the determination circuit 33d, as shown in FIG.

The oscillation circuit 33a is constituted by a clap oscillation circuit in this embodiment. The oscillation circuit 33a oscillates in synchronization with the intermittent excitation drive of the excitation drive circuit 32c. And the oscillation circuit 33a equips the mounting surface 5 with the oscillation signal (phi) which consists of a sine wave with constant amplitude value and frequency shown to Fig.9 (a) from the feed side 2nd antenna coil 7a. It transmits toward the power receiving side 2nd antenna coil 7b of (E).

The oscillation signal .phi.t oscillated from the oscillation circuit 33a functions as a carrier signal. That is, the device E generates the square wave pulse signal MP in accordance with the frequency of the received oscillation signal .phi.t. The amplitude of the received carrier signal (oscillation signal .phi.t.) Is measured by the square wave pulse signal. The modulated wave signal? M amplitude-modulated in proportion to is transmitted from the power receiving side second antenna coil 7b.

And the modulated wave signal (phi) shown in FIG.9 (c) or (g) modulated by the apparatus E is received by the 2nd power supply side 2nd antenna coil 7a of the power feeding device 1, It is supplied to the detection circuit 33b via the oscillation circuit 33a.

The detection circuit 33b is, for example, an envelope detection circuit, and detects a modulated wave signal .phi.m received from the device E through the oscillation circuit 33a. The detection circuit 33b generates an envelope waveform signal (demodulation signal DMP) surrounding the outside of the modulated wave signal .phi.m from the modulated wave signal .phi.m, that is, a square wave pulse signal generated by the device E. Demodulate (MP). The detection circuit 33b supplies a demodulation signal DMP to the frequency detection circuit 33c.

The frequency detection circuit 33c detects the frequency of the demodulated signal DMP. In this embodiment, the frequency detecting circuit 33c detects the rise and fall of the square wave pulse signal MP, counts the rise and fall times, and measures the period of the square wave pulse signal MP. For example, the frequency detection circuit 33c includes a differential circuit, a rectifier circuit and a timer.

The differential circuit detects the rise and fall of the square wave pulse signal MP. The rectifier circuit makes a derivative signal having a negative potential among the differential signals differentiated by the differential circuit as a differential signal of positive potential, and a timer counts between the differential signal and the differential signal output from the rectifier circuit.

The frequency detecting circuit 33c supplies the time determined by the timer to the determining circuit 33d as the period Tn of the square wave pulse signal MP.

The determination circuit 33d determines whether or not the metal piece 8 exists in accordance with the period Tn of the square wave pulse signal MP supplied from the frequency detection circuit 33c. For example, the determination circuit 33d includes the reference period Tk stored in advance in the memory built into this determination circuit 33d and the period Tn of the square wave pulse signal MP supplied from the frequency detection circuit 33c. It is judged whether or not a metal piece exists by comparing with.

In one example, the reference period Tk is a modulated wave signal Φ m from the device E in a state in which there is no metal piece 8 between the mounting surface 5 of the power feeding device 1 and the device E. Is the period Tn of the square wave pulse signal MP counted by the frequency detection circuit 33c when the power supply device 1 receives it.

Therefore, in the state where the metal piece 8 exists in the mounting surface 5 of the electric power feeding device 1, the frequency of the oscillation signal (phi) which the apparatus E received is low, and the period of the square wave pulse signal MP is low. (Tn) becomes long. As a result, the determination circuit 33d, when the period Tn of the square wave pulse signal MP from the frequency detection circuit 33c exceeds the reference period Tk, the mounting surface 5 of the power supply device 1 ), It is determined that the metal piece 8 exists. When the period Tn of the square wave pulse signal MP from the frequency detection circuit 33c is equal to or less than the reference period Tk, the determination circuit 33d is provided with a metal piece 8 on the mounting surface 5 of the power feeding device 1. ) Does not exist.

The determination circuit 33d notifies the system control unit 34 of the determination result. For example, when the determination circuit 33d determines that the metal piece 8 is present on the mounting surface 5 of the power feeding device 1, the determination circuit 33d supplies the metal presence signal ST to the system control unit 34. When the determination circuit 33d determines that the metal piece 8 does not exist on the mounting surface 5 of the power feeding device 1, the determination circuit 33d does not supply the metal presence signal ST to the system control unit 34.

The system control unit 34 supplies the excitation signals PS1 and PS2 to the excitation drive circuit 32c in response to the permission signal EN received from the signal extraction circuit 32b. In the illustrated example, when the signal extraction circuit 32b extracts two signals, the device authentication signal ID and the excitation request signal RQ, the system control unit 34 transmits the excitation signal (the excitation drive circuit 32c). PS1 and PS2 are supplied, and primary coil L1 is driven continuously.

The system control unit 34 intermittently supplies the excitation signals PS1 and PS2 to the excitation drive circuit 32c. For example, when the signal extraction circuit 32b extracts only one of the device authentication signal ID and the excitation request signal RQ, or both signals are not extracted, the system control unit 34 performs the excitation drive. The excitation signals PS1 and PS2 are intermittently supplied to the circuit 32c, and the primary coil L1 is intermittently excited.

The system control unit 34 excites the excitation drive circuit 32c in response to the permission signal EN from the signal extraction circuit 32b while the metal presence signal ST is supplied from the determination circuit 33d. The signals PS1 and PS2 are intermittently supplied, and the primary coil L1 is intermittently excited.

Moreover, the system control part 34 intermittently operates the oscillation circuit 33a of the metal detection circuit 33, and transmits oscillation signal (phi) intermittently from the power supply side 2nd antenna coil 7a.

Next, the operation of the power feeding device 1 will be described.

When a power supply switch (not shown) is turned on and commercial power is supplied to the power supply circuit 31, the power supply circuit 31 supplies a DC voltage as a drive power supply to the system control unit 34, the power supply circuit 32, and the metal detection circuit ( 33).

The system control unit 34 intermittently supplies the excitation signals PS1 and PS2 to the excitation drive circuit 32c when the drive power is supplied from the power supply circuit 31. The excitation drive circuit 32c intermittently drives the primary coil L1 in response to the intermittent excitation signals PS1 and PS2. The power feeding device 1 waits for the device E to be mounted on the mounting surface 5.

In addition, the system control unit 34 intermittently operates the oscillation circuit 33a of the metal detection circuit 33. Therefore, the intermittent oscillation signal .phi.t is transmitted from the power feeding side second antenna coil 7a.

And when the apparatus E is mounted on the mounting surface 5, the secondary coil L2 of the apparatus E receives secondary electric power by the intermittent excitation drive of the primary coil L1. In the device E, the data generation circuit 15b of the power receiving circuit 15 generates the device authentication signal ID and the excitation request signal RQ in accordance with this secondary power, and generates the signals ID and RQ. Supply to the transmission circuit 15c. The transmitting circuit 15c transmits the device authentication signal ID and the excitation request signal RQ from the power receiving side first antenna coil 6b toward the power feeding side first antenna coil 6a of the power feeding device 1. .

In the power supply device 1, the signal extraction circuit 32b extracts the device authentication signal ID and the excitation request signal RQ from the signals received through the power supply side first antenna coil 6a and the reception circuit 32a. do. When the signal extraction circuit 32b is able to extract the device authentication signal ID and the excitation request signal RQ, the signal extraction circuit 32b supplies the permission signal EN to the system control unit 34.

The system control unit 34 continuously supplies the excitation signals PS1 and PS2 to the excitation drive circuit 32c in response to the permission signal EN. The excitation drive circuit 32c continuously excites the primary coil L1 in response to the continuous excitation signals PS1 and PS2. As a result, the device E mounted on the mounting surface 5 of the power feeding device 1 receives the secondary power according to the continuous excitation driving of the primary coil L1 through the secondary coil L2.

Thereby, in the apparatus E, the power supply for driving the load Z from the power receiving circuit 15 (commutation smoothing circuit 15a) to the load Z is supplied.

On the other hand, the power receiving side second antenna coil 7b provided in the device E receives the oscillation signal .phi.t from the power feeding side second antenna coil 7a. The power receiving side second antenna coil 7b supplies the received oscillation signal .phi.t to the rectifier circuit 16a of the modulation circuit 16. The rectifier circuit 16a half-wave rectifies the oscillation signal .phi.t.

The half-wave rectified oscillation signal .phi.t is charged and discharged by the charge / discharge capacitor C0 and the resistor R0 provided in the rectifier circuit 16a. The charging voltage Vt of the charge / discharge capacitor C0 is applied to the modulation wave signal generation circuit 16b (unstable multivibrator 20) as the power supply voltage VG.

Here, the charge / discharge time of the charge / discharge capacitor C0 varies depending on the frequency of the oscillation signal? T, that is, whether or not the metal piece 8 is present on the mounting surface 5.

The frequency of the oscillation signal .phi.t is relatively high as shown in Fig. 9A when the metal piece 8 is not present on the mounting surface 5. On the contrary, when the metal piece 8 exists in the mounting surface 5, the frequency of oscillation signal (phi) is relatively low as shown to Fig.9 (e). Therefore, the charge / discharge time of the charge / discharge capacitor C0 becomes longer in the case where the metal piece 8 exists than in the case where the metal piece 8 does not exist in the mounting surface 5.

As a result, the period Tn of the square wave pulse signal MP output from the modulated wave signal generation circuit 16b (unstable multivibrator 20) does not have the metal piece 8 in the mounting surface 5. In this case, it becomes relatively short, as shown to Fig.9 (b). On the other hand, when the metal piece 8 exists in the mounting surface 5, the period Tn of the square wave pulse signal MP becomes relatively long, as shown to Fig.9 (f). As described above, the period Tn of the square wave pulse signal MP is longer in the metal fragment 8 in the side where the metal fragment 8 is present, depending on whether or not the metal fragment 8 is present on the mounting surface 5.

The square wave pulse signal MP is supplied to the gate terminal of the transistor Q3 of the modulator 16c to turn the transistor Q3 on and off.

By the on / off (square wave pulse signal MP) of the transistor Q3, the current (oscillation signal? T) flowing through the power receiving side second antenna coil 7b is amplitude modulated to be a modulated wave signal? M. The power transmission side second antenna coil 7b is transmitted to the power supply side second antenna coil 7a.

In the case where the metal piece 8 is not present on the mounting surface 5, the edge having the waveform shown in Fig. 9C in accordance with the period Tn of the square wave pulse signal MP shown in Fig. 9B. The harmonic signal .phi.m is generated. On the other hand, when the metal piece 8 exists in the mounting surface 5, it has the waveform shown to Fig.9 (g) according to the period Tn of the square wave pulse signal MP shown to Fig.9 (f). The modulated wave signal .phi.m is generated.

The power feeding side second antenna coil 7a receives the modulated wave signal .phi.m transmitted from the power receiving side second antenna coil 7b. The modulated wave signal? M received by the power feeding side second antenna coil 7a is supplied to the detection circuit 33b via the oscillation circuit 33a.

The detection circuit 33b generates an envelope waveform signal (demodulation signal DMP) surrounding the outside of the modulated wave signal .phi.m from the modulated wave signal .phi.m, i.e., demodulates a square wave pulse signal MP. The detection circuit 33b supplies a demodulation signal DMP to the frequency detection circuit 33c.

Therefore, the period Tn of the demodulation signal DMP generated by the detection circuit 33b is relatively as shown in FIG. 9D when the metal piece 8 is not present on the mounting surface 5. short. On the other hand, when the metal piece 8 exists in the mounting surface 5, as shown in FIG.9 (h), the period Tn of the demodulation signal DMP becomes comparatively long. As described above, the period Tn of the demodulation signal DMP is longer in the metal piece 8 than in the case where the metal piece 8 is not present in the mounting surface 5.

The detection circuit 33b supplies a demodulation signal DMP to the frequency detection circuit 33c.

The frequency detecting circuit 33c detects the rise and fall of the demodulated signal DMP to count the period Tn of the demodulated signal DMP. At this time, the period Tn of the counted demodulation signal DMP is longer when the metal piece 8 is present than when the metal piece 8 is not present on the mounting surface 5.

The frequency detection circuit 33c supplies the period Tn of the counted demodulation signal DMP to the determination circuit 33d. The determination circuit 33d inputs the period Tn of the input demodulation signal DMP, and compares the period Tn with the reference period Tk.

The determination circuit 33d determines that the metal piece 8 exists on the mounting surface 5 of the power feeding device 1 when the period Tn of the demodulation signal DMP exceeds the reference period Tk, The metal present signal ST is supplied to the system controller 34.

Moreover, when the period Tn of the square wave pulse signal MP is a value below the reference period Tk, the determination circuit 33d does not have the metal piece 8 in the mounting surface 5 of the power feeding device 1. It is determined that there is no, and the metal presence signal ST is not supplied to the system control unit 34.

When the system control unit 34 receives the metal presence signal ST, the system control unit 34 switches the excitation signals PS1 and PS2 to the excitation drive circuit 32c from the continuous output to the intermittent output. Thereby, since the primary coil L1 is intermittently excited, it does not inductively heat the metal piece 8 which the metal detection circuit 33 detected. On the other hand, if the system control unit 34 does not receive the metal presence signal ST, the system control unit 34 continues the continuous output of the excitation signals PS1 and PS2 to the excitation drive circuit 32c. Thereby, since the primary coil L1 continues continuous excitation, drive power is continuously supplied to the load Z of the apparatus E. As shown in FIG.

The rectifier circuit 16a is an example of an oscillation signal receiving circuit. The modulator 16c and the unstable multivibrator 20 are examples of a modulated wave signal generation circuit.

According to the first embodiment, the following effects can be obtained.

(1) According to the above embodiment, the oscillation circuit 33a of the metal detection circuit 33 provided in the power feeding device 1 transmits the oscillation signal .phi.t to the modulation circuit 16 of the device E. The modulation circuit 16 of the device E generates a square wave pulse signal MP from the received oscillation signal .phi.t. At this time, the modulation circuit 16 changes the period Tn of the square wave pulse signal MP according to whether the metal piece 8 is present, modulates the square wave pulse signal MP, and modulates the modulated wave signal .phi.m. And the modulated wave signal .phi.m is transmitted to the metal detection circuit 33.

The metal detection circuit 33 of the power feeding device 1 measures the period of the demodulation signal DMP generated from the modulated wave signal Φm, that is, the period Tn of the square wave pulse signal MP, so that the metal piece 8 Determine if it exists.

In this way, when protruding the metal piece 8, the power feeding device 1 does not have to change the exciting frequency of the primary coil L1 for power feeding. Therefore, since it is unnecessary to set a plurality of excitation frequencies of the primary coil L1 in the power supply device 1, a complicated and expensive control circuit for switching the excitation frequency is unnecessary, and a cheap non-contact power supply device can be realized. have.

In addition, since the power supply device 1 only needs to receive the demodulated signal Φ m from the device E and demodulate it to obtain the period Tn, an expensive circuit for performing high-speed signal processing is not required. Do not. Therefore, an inexpensive non-contact power supply device can be realized.

(2) According to the above embodiment, the device E generates information indicating whether the metal piece 8 is present, that is, a square wave pulse signal MP. Therefore, the circuit structure and load of the power supply device 1 side can be reduced by that, and a cheap non-contact power supply device can be realized further.

(3) According to the above embodiment, when generating the modulated wave signal .phi.m, since the oscillation signal .phi.t from the oscillation circuit 33a of the metal detection circuit 33 is used as a carrier signal, a carrier signal is generated. Dedicated oscillation circuit can be omitted.

(4) According to the above embodiment, since the modulated wave signal .phi.m is an amplitude modulated signal, the circuit for generating the modulated wave signal .phi.m is simple and inexpensive compared to other modulations such as frequency modulation. For the same reason, the detection circuit 33b for demodulating the modulated wave signal .phi.m has a simple structure and is inexpensive.

(5) According to the above embodiment, the unstable multivibrator 20 of the modulated wave signal generation circuit 16b in which the charge voltage Vt of the charge / discharge capacitor C0 of the rectifier circuit 16a is the power supply voltage VG. ). Then, the oscillation period of the unstable multivibrator 20 is changed by the power supply voltage VG that changes due to the presence of the metal piece 8, and the period Tn is changed depending on whether the metal piece 8 is present. A square wave pulse signal (MP) was generated.

Therefore, a modulated wave (square wave pulse signal MP) for detecting the presence of the metal piece 8 can be generated by a simple circuit configuration called the unstable multivibrator 20.

You may change an Example as follows.

According to the above embodiment, the oscillation signal? T transmitted by the oscillation circuit 33a of the power supply device 1 is used as the carrier signal. However, the carrier signal may be generated on the device E side. In this case, for example, an oscillation circuit for a carrier signal is provided in the modulation circuit 16, and the carrier signal generated by the oscillation circuit is modulated into a square wave pulse signal MP (modulation wave) to generate a modulated wave signal. You may transmit to the power supply device 1.

According to this embodiment, the modulated wave signal .phi.m is transmitted from the power receiving side second antenna coil 7b to the power feeding side second antenna coil 7a. This is fed to the secondary coil L2 of the device E by using the electromagnetic induction phenomenon from the primary coil L1 of the power feeding device 1 by using the modulated wave signal Φm generated by the modulation circuit 16. The superimposed signal is superimposed on the electromagnetic wave signal corresponding to the feeding current, the superimposed signal is received through the primary coil L1, and the modulated wave signal is detected from the superimposed signal by the detection circuit 33b of the metal detection circuit 33. You may implement so as to demodulate (phi).

According to the above embodiment, the frequency detecting circuit 33c detects the rise and fall of the square wave pulse signal MP, counts the time of rise and fall, and measures the period Tn of the square wave pulse signal MP. It was a circuit. The square wave pulse signal MP is sampled using a sampling signal of a very short period, and the square wave is obtained from the number of sampling at the high potential (high level) and the number of sampling at the low potential (low level) of the square wave pulse signal MP. The period Tn of the pulse signal MP may be obtained.

Although the embodiments of the present invention have been described with reference to the drawings, the present invention is not limited to the above, but may be modified with the appended claims and equivalents.

Claims (13)

A method for detecting whether a metal foreign material is present on a non-contact power feeding device that performs power feeding by using an electromagnetic induction phenomenon for a power receiving device included in an electric device,
The non-contact power feeding device transmits an oscillation signal to the power receiving device,
In the oscillation signal received by the power receiving device, a modulated wave according to a change in magnetic flux due to the presence of foreign metals is detected.
In order to transmit the modulated wave to the non-contact power feeding device, a modulated wave signal is generated by modulating a carrier signal according to the modulated wave, and the power receiving device transmits the modulated wave signal to the non-contact power feeding device,
And the non-contact power feeding device receives the modulated wave signal transmitted from the power receiving device, and determines whether metal foreign matter exists in accordance with the demodulated signal demodulated from the modulated wave signal. The method of claim 1,
The modulated wave is a square wave pulse signal having a period changed in response to a change in magnetic flux due to the presence of foreign metals in the oscillation signal received by the power receiving device,
The modulated wave signal is generated by amplitude modulating the amplitude of the carrier signal in proportion to the square wave pulse signal,
And said demodulation signal is a square wave pulse signal generated by envelope detection of said modulated wave signal. 3. The method according to claim 1 or 2,
And the carrier signal is the oscillation signal transmitted from the non-contact power feeding device to the power receiving device. The method of claim 1,
The carrier signal is an electromagnetic wave signal according to a feed current supplied from a primary coil of the non-contact power feeding device to a secondary coil included in the power receiving device by using an electromagnetic induction phenomenon.
And said modulated wave signal is a signal obtained by superposing said modulated wave on said electromagnetic wave signal. A non-contact power feeding device for feeding power to a power receiving device included in an electric device by using an electromagnetic induction phenomenon,
An oscillation circuit for transmitting an oscillation signal to the power receiving device;
From the power receiving device that has received the oscillation signal, a modulated wave signal obtained by modulating the oscillation signal by a modulated wave according to a change in magnetic flux is received, detects the modulated wave signal, and demodulates the modulated wave detected by the power receiving device. Detection circuit;
A frequency detection circuit for detecting a frequency of a modulated wave demodulated by the detection circuit; And
A determination circuit for determining whether a metal foreign material exists according to the frequency of the demodulated modulated wave detected by the frequency detection circuit
And the non-contact power feeding device. 6. The method of claim 5,
The modulated wave is a square wave pulse signal having a period changed in accordance with a change in magnetic flux due to the presence of foreign metal in the oscillation signal path received by the power receiving device,
The modulated wave signal is generated by amplitude modulation of a carrier signal in proportion to the square wave pulse signal,
The detection circuit is configured to demodulate the square wave pulse signal by envelope detecting the modulated wave signal,
The frequency detection circuit is configured to detect a period of the square wave pulse signal demodulated by the detection circuit,
And the determination circuit determines whether or not metal foreign matter exists in accordance with a period of the square wave pulse signal detected by the frequency detection circuit. The method according to claim 6,
And the carrier signal is the oscillation signal transmitted by the oscillation circuit to the power receiving device. A power receiving device installed in an electric device and receiving power from a non-contact power supply device using an electromagnetic induction phenomenon,
An oscillation signal receiving circuit that receives an oscillation signal for detecting whether a metallic foreign substance exists, which is transmitted from the non-contact power supply device;
A modulated wave signal generation circuit for generating a modulated wave according to a change in magnetic flux due to the presence of foreign metals from the oscillation signal received by the oscillation signal receiving circuit; And
A modulated wave signal generation circuit for generating a modulated wave signal by modulating a carrier signal according to the modulated wave to transmit the modulated wave to a non-contact power supply device
Power receiving device comprising a. 9. The method of claim 8,
The modulated wave is a square wave pulse signal,
The modulated wave signal generation circuit is configured to generate the square wave pulse signal having a period changed from the received oscillation signal according to a change in magnetic flux due to the presence of a foreign metal material.
The modulated wave signal is generated by amplitude modulating the amplitude of the carrier signal in proportion to the square wave pulse signal.
And the modulated wave signal generation circuit is configured to generate the modulated wave signal by amplitude modulating the amplitude of the carrier signal in proportion to the square wave pulse signal. 10. The method of claim 9,
And the carrier signal is the oscillation signal transmitted from the non-contact power supply device to the oscillation signal receiving circuit. A non-contact power feeding system comprising a power receiving device included in an electrical device and a non-contact power feeding device that feeds power to the power receiving device using electromagnetic induction.
The non-contact power feeding device includes:
An oscillation circuit for transmitting an oscillation signal of a predetermined frequency to the power receiving device for detecting whether a metal foreign matter is present;
From the power receiving device that has received the oscillation signal, a modulated wave signal obtained by modulating the oscillation signal by a modulated wave according to a change in magnetic flux is received, detects the modulated wave signal, and demodulates the modulated wave detected by the power receiving device. Detection circuit;
A frequency detection circuit for detecting a frequency of the modulated wave demodulated by the detection circuit; And
A determination circuit that determines whether or not a metal foreign matter exists according to the frequency of the modulated wave detected by the frequency detection circuit.
Lt; / RTI >
The power receiving device,
An oscillation signal receiving circuit that receives the oscillation signal transmitted from the non-contact power supply device;
A modulated wave signal generation circuit for generating a modulated wave according to a change in magnetic flux due to the presence of foreign metals from the oscillation signal received by the oscillation signal receiving circuit; And
A modulated wave signal generation circuit for generating a modulated wave signal by modulating a carrier signal according to the modulated wave to transmit the modulated wave to a non-contact power supply device
And a contactless power supply system. 12. The method of claim 11,
The modulated wave is a square wave pulse signal,
The modulated wave signal generating circuit of the power receiving device is configured to generate the square wave pulse signal having a period changed in accordance with a change in magnetic flux due to the presence of metal foreign matter in the received oscillation signal,
The modulated wave signal is generated by amplitude modulating the amplitude of the carrier signal in proportion to the square wave pulse signal,
The modulated wave signal generating circuit of the power receiving device is configured to amplitude modulate the amplitude of the carrier signal in proportion to the square wave pulse signal to generate the modulated wave signal,
The detection circuit of the non-contact power supply device is configured to demodulate the square wave pulse signal by envelope detection of the modulated wave signal.
The frequency detection circuit of the non-contact power supply device is configured to detect a period of the square wave pulse signal demodulated by the detection circuit,
And the determination circuit of the non-contact power supply device determines whether or not a metal foreign matter exists in accordance with a period of the square wave pulse signal detected by the frequency detection circuit. 13. The method according to claim 11 or 12,
And the carrier signal is the oscillation signal transmitted from the oscillation circuit of the non-contact power feeding device to the oscillation signal receiving circuit of the power receiving device.

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