DE102012020565B4 - Contactless power supply device - Google Patents

Abstract

Contactless power supply device (1) using an electromagnetic induction effect to supply power to a power receiving device (10) arranged in an electric device, said contactless power supply device (1) comprising:a primary coil (L1) arranged in each of one or more power supply areas (AR) defined in a setting surface on which the electrical equipment is set, the primary coil (L1) supplying secondary power by electromagnetic induction to a secondary coil (L2) of the power receiving device (10) in the corresponding power supply area (AR) supplies;a basic power supply unit circuit (4) arranged in each of the power supply areas (AR), the basic power supply unit circuit (4) exciting the primary coil (L1) in the corresponding power supply area (AR) to generate secondary power by electromagnetic induction ng, and the basic power supply unit circuit (4) sends an oscillation signal from the corresponding power supply area (AR) to the power receiving device (10), receives a modulated wave signal from the power receiving device (10), which receives a modulation wave (MP) generated by a multivibrator ( 22a) is output according to a magnetic flux change is detected from the oscillation signal, and the modulated wave signal is detected to demodulate the modulation wave (MP); anda system control unit that determines whether or not a metallic foreign matter is present in the power supply area (AR) corresponding to the basic power supply unit circuit (4) based on the modulation wave (MP) demodulated by the basic power supply unit circuit (4); wherein: the basic power supply unit circuit (4) comprises: an oscillation circuit (44a) that transmits the oscillation signal to the power receiving device (10), a primary detection coil that receives the modulated wave signal, a detection circuit that detects the modulated wave signal received from the primary detection coil, and demodulates the modulation wave (MP), andan operation time calculation circuit that calculates an operation time of the modulation wave (MP) demodulated by the detection circuit;the multivibrator (22a) has a first transistor (Q1) and a second transistor (Q2) which are selected based on a power supply voltage ( VG) of the multivibrator (22a) are driven, and outputs the modulation wave (MP) from a collector terminal of the first transistor (Q1);the multivibrator (22a) is configured such that a change in the power supply voltage (VG) has an initial value of a potential between the base and the emitter of the first transistor (Q1) changes when the first transistor (Q1) is switched from ON to OFF, and a rate of change between the base and the emitter of the second transistor (Q2) changes when the second transistor (Q2) is turned off;a time constant of the multivibrator (22) is set so that an operation time (DU) of the modulation wave (MP) increases as the power supply voltage (VG) of the multivibrator (22a) decreases when a metal piece (M) on the base power supply unit circuit (4) associated power supply area (AR),wherein the system control unit determines whether or not a metallic foreign matter is present in the power supply area (AR) corresponding to the basic power supply unit circuit (4) based on the operation time calculated by the operation time calculation circuit, and the Supplying power to the appropriate power supply area h (AR) stops when it is determined that there is a metallic foreign matter.

Description

The present invention relates to a contactless power supply device.

In a contactless power supply system that performs the electromagnetic induction method, an electric appliance including a power receiving device is placed on a seating surface of a contactless power supply device. In this state, the contactless power supply device excites its primary coil, thereby exciting a secondary coil arranged in the power receiving device of the electrical equipment by means of electromagnetic induction. Secondary power is generated by the secondary coil and converted into DC power in the power receiving device. The direct-current power is supplied to a load of the electric device as driving power.

The non-contact power supply device may include a metal detector that detects metallic foreign matter and stops supplying power when the metal detector detects a metallic foreign matter. This prevents a metallic foreign body from heating up. If a metal foreign matter is interposed between the non-contact power supply device and the electric equipment (power receiving device), the metal foreign matter may be inductively heated when power is supplied.

The document U.S. 2010/0270867 A1 relates to a contactless power supply system. The non-contact power supply system includes a power supply device for transmitting high-frequency power and a load device that receives the high-frequency power in a non-contact manner via electromagnetic induction. The power supply apparatus includes a power transmission unit having a primary power coil and an inverting circuit, a demand unit having at least a primary signal coil and an oscillation circuit, a signal detecting unit, and a control unit. The load device has a power receiving unit that magnetically couples a secondary power coil to the primary power coil, a power conversion unit, a secondary signal coil that is magnetically coupled to the primary signal coil, and a response unit that is operated by electromotive force generated in the secondary signal coil is induced. The control unit terminates power transmission when no signal is detected and performs power transmission when a signal is detected.

The document WO 2011/122348 A1 relates to a non-contact power supply system with a device and a power supply device that supplies non-contact power to the device. The energy supply device has a number of planar or linear primary coils and a number of energy supply modules. The device has a secondary coil and a transmitter circuit for transmitting an excitation request signal. Each of the power supply modules includes a high-frequency inverter circuit, a receiver circuit, and an excitation control circuit. Each of the high-frequency inverter circuits has an oscillator circuit.

Japanese Laid-Open Patent Publication No. JP 2000 - 295 796 A describes an example of a metal detector arranged in a contactless power supply device. The metal detector described in the publication excites the primary coil of the contactless power supply device at a predetermined frequency (210 kHz) different from an excitation frequency (180 kHz) when power is supplied. The metal detector detects the presence of a metallic foreign object when there is a change in the inductance of the primary coil excited at the predetermined frequency, and stops supplying power when a metallic foreign object is present.

The metal detector detects whether or not a metal foreign matter is present from a change in inductance of a primary coil, that is, a change in resonance frequency of an oscillation circuit including the primary coil. However, a change in the inductance of the primary coil also occurs when the positional relationship of the primary coil and the secondary coil changes. This leads to a case where it cannot be determined whether there is a metallic object or whether the relative positions of the primary coil and the secondary coil have changed. Consequently, the metal detector cannot accurately detect the presence of a metal foreign body unless the primary coil and the secondary coil are properly arranged to satisfy a positional relationship that is set in advance.

Further, in the metal detector, in the case where a plurality of primary coils are arranged adjacently, if there is a coil prepared to deliver power (which is excited with an initial frequency of 210 kHz or a frequency of 180 kHz to 210 kHz subsequently ), and a coil supplying power (excited at 180 kHz) produces a differential frequency signal according to the frequency difference. The differential frequency signal acts as noise on the metal detector. However, the following frequency changes and thereby changes the differential frequency signal. Consequently, a noise suppressing means becomes complicated.

Accordingly, an object of the present invention is to provide a non-contact power supply apparatus capable of accurately detecting a metallic foreign matter without changing the excitation frequency of a power supply coil arranged in a power supply area.

An embodiment of the present invention is a non-contact power supply device that uses an electromagnetic induction effect to supply power to a power receiving device arranged in an electric device. The non-contact power supply device includes a primary coil disposed in each of one or more power supply areas defined in a seating surface on which the electrical equipment is seated. The primary coil supplies secondary power to a secondary coil of the power receiving device in the corresponding power supply area by electromagnetic induction. Further, the contactless power supply device includes a basic power supply unit circuit arranged in each of the power supply areas to excite the primary coil in the corresponding power supply area to supply secondary power through electromagnetic induction. The basic power supply unit circuit further transmits an oscillation signal from the corresponding power supply area to the power receiving device, receives a modulated wave signal from the power receiving device that detects a modulation wave that is according to a magnetic flux change from the oscillation signal, and detects the modulated wave signal to the modulation wave demodulate. The non-contact power supply device also includes a system control unit that determines whether or not a metallic foreign matter is present in the power supply area, , corresponding to the base power supply unit circuit, based on the modulation wave demodulated by the base power supply unit circuit.

In one example, the basic power supply unit circuit includes an oscillation circuit that sends the oscillation signal to the power receiving device, a primary detection coil that receives the modulated wave signal, a detection circuit that detects the modulated wave signal received from the primary detection coil and demodulates the modulation wave, and an operation/ A duty calculation circuit that calculates an operation time of the modulation wave demodulated by the detection circuit. The system control unit determines whether or not a metallic foreign matter is present in the power supply section corresponding to the basic power supply unit circuit, based on the operation time calculated by the duty calculation circuit, and stops supplying power to the corresponding power supply section when determining that a metallic foreign body is present.

In one example, the power receiving device having a secondary detection coil receives a carrier signal from the basic power supply unit circuit and generates the modulation wave as an ON/OFF signal with an operation time that changes according to a magnetic flux change at the secondary detection coil. The modulated wave signal is generated by amplitude modulating an amplitude of the carrier signal with the ON/OFF signal. The detection circuit envelope-detects the modulated wave signal to demodulate the ON/OFF signal. The operation time calculation circuit detects an operation time of the ON/OFF signal demodulated by the detection circuit.

In one example, the carrier signal is the oscillation signal sent from the oscillation circuit to the power receiving device.

In one example, the basic power supply unit circuit includes an oscillation circuit that transmits the oscillation signal to the power receiving device, a primary detection coil that receives the modulated wave signal, and a detection circuit that detects the modulated wave signal received from the primary detection coil and demodulates the modulation wave. The system control unit receives the modulation wave demodulated by the detection/sensing circuit, calculates an operation time of the modulated wave, determines whether or not a metal foreign matter is present in the power supply area corresponding to the basic power supply unit circuit based on the calculated operation time, and stops the delivery of power to the corresponding power supply area when it is determined that a metallic foreign body is present.

In one example, the oscillation circuit is an excitation drive circuit that excites the primary coil and the primary detection coil is the primary coil.

In one example, the base power supply unit circuit transmits the oscillation signal with a primary detection coil that is placed independently of the primary coil used to supply the secondary power to the secondary coil.

In one example, the primary detection coil is shared between adjacent ones of the power supply regions.

In one example, the base power supply unit circuit transmits the oscillation signal with the primary coil used to supply the secondary power to the secondary coil.

The present invention allows detection of a metallic foreign body without fixing the relative position of the primary coil and the secondary coil. Furthermore, since there is no need to change the excitation frequency of the power-supply coil arranged in the power-supply region, noise can be suppressed effectively. Consequently, an increase in detection accuracy can be expected.

Additional objects and advantages of the invention will be set forth in part in the description that follows and in part will be obvious from the description. The objects and advantages of the invention will be realized and obtained by means of elements and combinations of elements particularly pointed out in the appended claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention as claimed.

• 1 eine Perspektivansicht ist, die eine kontaktlose Leistungsversorgungsvorrichtung und ein elektrisches Gerät in einem kontaktlosen Leistungsversorgungssystem vollständig zeigt;
• 2 eine erklärende Ansicht ist, die eine Anordnung von Primärspulen zeigt;
• 3 ein elektrisches Blockschaltbilddiagramm der kontaktlosen Leistungsversorgungsvorrichtung und des elektrischen Geräts ist;
• 4 ein elektrisches Blockschaltbilddiagramm einer Leistungsempfangsschaltung ist, die in dem elektrischen Gerät angeordnet ist;
• 5 ein elektrisches Blockschaltdiagramm einer Modulationsschaltung ist, die in dem elektrischen Gerät angeordnet ist;
• 6 ein elektrisches Schaltungsdiagramm eines Gleichrichtungsschaltungsabschnitts und eines Modulationsschaltungsabschnitts in der Modulationsschaltung des elektrischen Geräts ist;
• 7 ein elektrisches Schaltungsdiagramm eines Modulationswellensignal-Erzeugungsabschnitts in der Modulationsschaltung des elektrischen Geräts ist;
• 8 ein elektrisches Blockschaltdiagramm einer Basisleistungsversorgungseinheitsschaltung ist, die in der kontaktlosen Leistungsversorgungsvorrichtung angeordnet ist;
• 9 ein elektrisches Schaltungsdiagramm einer Vollbrückenschaltung ist;
• 10A, 10B, 10C und 10D Wellenformdiagramme eines Oszillationssignals, eines EIN/AUS-Signals, eines modulierten Wellensignals und eines Demodulationssignals sind, wenn kein Metallstück vorhanden ist;
• 10E, 10F, 10G und 10H Wellenformdiagramme des Oszillationssignals, des EIN/AUS-Signals, des modulierten Wellensignals und des Demodulationssignals sind, wenn das Metallstück vorhanden ist;
• 11 ein elektrisches Blockschaltdiagramm einer Basisleistungsversorgungseinheitsschaltung in einem anderen Beispiel ist;
• 12 ein elektrisches Blockschaltdiagramm einer Leistungsempfangsschaltung in einem anderen Beispiel ist;
• 13 ein elektrisches Blockschaltdiagramm einer Basisleistungsversorgungseinheitsschaltung in einem weiteren Beispiel ist;
• 14 ein elektrisches Blockschaltdiagramm eines elektrischen Geräts in einem weiteren Beispiel ist; und
• 15 ein elektrisches Blockschaltdiagramm einer Vollbrückenschaltung in einem weiteren Beispiel ist.

The invention, together with its objects and advantages, may best be understood by reference to the following description of the presently preferred embodiment, taken in conjunction with the accompanying drawings, in which:

• 1 Fig. 12 is a perspective view entirely showing a contactless power supply device and an electric device in a contactless power supply system;
• 2 Fig. 12 is an explanatory view showing an arrangement of primary coils;
• 3 Fig. 12 is an electrical block diagram of the contactless power supply device and the electrical equipment;
• 4 Fig. 12 is an electrical block diagram of a power receiving circuit arranged in the electrical device;
• 5 Fig. 12 is an electrical block circuit diagram of a modulation circuit arranged in the electrical device;
• 6 Fig. 13 is an electric circuit diagram of a rectification circuit section and a modulation circuit section in the modulation circuit of the electric equipment;
• 7 Fig. 13 is an electric circuit diagram of a modulation wave signal generation section in the modulation circuit of the electric device;
• 8th Fig. 12 is an electric block circuit diagram of a basic power supply unit circuit arranged in the contactless power supply device;
• 9 Figure 13 is an electrical circuit diagram of a full bridge circuit;
• 10A , 10B , 10C and 10D 12 are waveform diagrams of an oscillation signal, an ON/OFF signal, a modulated wave signal and a demodulation signal when no metal piece is present;
• 10E , 10F , 10G and 10H are waveform diagrams of the oscillation signal, the ON/OFF signal, the modulated wave signal and the demodulation signal when the metal piece is present;
• 11 Fig. 14 is an electrical block circuit diagram of a basic power supply unit circuit in another example;
• 12 Fig. 14 is an electrical block circuit diagram of a power receiving circuit in another example;
• 13 Fig. 14 is an electrical block circuit diagram of a basic power supply unit circuit in another example;
• 14 Fig. 13 is an electric block circuit diagram of an electric device in another example; and
• 15 Figure 12 is an electrical block circuit diagram of a full bridge circuit in another example.

An embodiment of a contactless power supply device according to the present ing invention will now be described with reference to the drawings.

1 12 is a perspective view showing a non-contact power supply device (hereinafter referred to simply as the power supply device) 1 and an electric device (hereinafter referred to simply as an apparatus) E connected in a non-contact manner is supplied with power from the contactless power supply device.

The power supply device 1 comprises a tetragonal plate-shaped frame 2 having a flat top surface defining a seating surface 3 on which the appliance E is put. A plurality of square tetragonal service areas AR are defined in the setting area 3 . In the present embodiment, twenty-four power supply areas AR, four from left to right and six from front to back, are defined.

As in 2 1, a primary coil L<b>1 wound to have a tetragonal shape corresponding to the profile of the power supply area AR is arranged at a position corresponding to each power supply area AR in the frame 2 . Further, a primary-side metal detection coil La wound to have a circular shape (may be a tetragonal shape like the primary coil L<b>1 ) is arranged in the frame 2 corresponding to each power supply area AR. In the present embodiment, the primary-side metal detection coil La is arranged at a position above the primary coil L1 and has a smaller diameter than the primary coil L1. The primary side metal detection coil La is arranged such that its center position is aligned with a center position of the power supply area AR. Further, a signal receiving antenna coil A1 is arranged on an inner side of each primary-side metal detecting coil La arranged in each power supply area AR.

In each power supply area AR, the primary coil L1, the primary side metal detection coil La and the signal receiving antenna coil A1 are each connected to a base power supply unit circuit 4 (see 3 ) arranged in the frame 2 for each power supply area AR.

Each primary coil L<b>1 is excited and driven by the corresponding base power supply unit circuit 4 . Further, each primary coil L1 is excited and driven solely or in cooperation with another primary coil L1 to supply power to a secondary coil in the apparatus E installed in the power supply area AR in a non-contact manner.

Each primary-side metal detection coil La generates an oscillation signal φt used for metal detection when excited and driven by the corresponding basic power supply unit circuit 4 . The base power-supply unit circuit 4 detects whether or not there is a metal foreign matter on the corresponding power-supply area AR by the primary-side metal detection coil La.

As in 1 1, the device E, which receives the power supply from the power supply device 1 by electromagnetic induction, includes a secondary-side metal detection coil Lb arranged in the device E. As shown in FIG. In the present embodiment, the secondary-side metal detection coil Lb is arranged on a lower side of the secondary coil L2. When the device E is set on the setting surface 3 of the power supply device 1, signals used for metal detection are transmitted between the primary side metal detection coil La of the power supply area AR located immediately below the device E and the secondary side metal detection coil Lb of device E replaced.

The device E also includes a signal transmission antenna coil A2 disposed on an inside of the secondary-side metal detection coil Lb. When the device is placed on the setting surface 3 of the power supply device 1, data and information are exchanged through wireless communication between the signal receiving antenna coil A1 of the power supply area AR located immediately below the device E and the signal transmission antenna coil A2 of the device E.

The electrical constructions of the power supply device 1 and the device E will now be described with reference to FIG 3 described.

(Devices)

As in 3 As shown, the device E comprises a power receiving circuit 10 serving as a power receiving device for receiving secondary power from the power supply device 1 in a wireless manner, and a modulation circuit 20 which modulates the oscillation signal Φt from the power supply device 1, the received by the secondary side metal detection coil Lb is modulated.

As in 4 As shown, the power receiving circuit 10 includes a rectification smoothing circuit section 11, a DC-DC converter circuit 12, a data generation circuit section 13, and a transmission circuit section 14.

The rectification smoothing circuit section 11 is connected to the secondary coil L2. The rectification smoothing circuit section 11 converts the secondary power, which is excited in and supplied to the secondary coil L2 by electromagnetic induction that occurs when the primary coil L1 of the power supply device 1 is excited, into DC voltage free from ripples. The DC-DC converter circuit 12 DC-DC converts the DC voltage generated by the rectification smoothing circuit portion 11 to a desired voltage. The DC-DC converted DC voltage is supplied to a load Z of the device E.

The load Z can be a device driven by the secondary power generated in the secondary coil L2. For example, the load Z may be an apparatus that is driven on the support surface 3 using the DC-DC converted DC voltage as the driving power. Alternatively, the load Z may be a device that is directly driven on the support surface 3 using the secondary power as AC power. Further, the load Z may be an apparatus that drives a rechargeable battery (secondary battery) using the DC-DC converted DC power.

The DC-DC converted DC voltage is also used as a drive source of the data generation circuit section 13 and the transmission circuit section 14 .

The data generation circuit section 13 generates a device authentication signal ID and a stimulation request signal RQ and provides them to the transmission circuit section 14 . The device authentication signal ID indicates that the device E is a real device that can receive power from the power supply device 1 . The excitation request signal RQ is a signal for requesting power supply from the power supply device 1.

When the data generation circuit section 13 can be driven with the DC power supply generated by the rectification smoothing circuit section 11 or the secondary battery built in the device E, the data generation circuit section 13 generates the device authentication signal ID and the stimulation request signal RQ, for example. For example, when a power switch that drives the load Z and is arranged in the device E is OFF, the data generation circuit section 13 does not generate the device authentication signal ID and the excitation request signal RQ.

Further, when a microcomputer is arranged in the device E, the data generation circuit section 13 also does not generate the device authentication signal ID and the excitation request signal RQ when the microcomputer decides to stop the power supply.

The transmission circuit section 14 is connected to the transmission transmission antenna coil or signal transmission antenna coil A2. The transmission circuit section 14 transmits the device authentication signal ID and the excitation request signal RQ from the data generation circuit section 13 to the power supply apparatus 1 via the signal transmission antenna coil A2.

The modulation circuit 20 modulates the oscillation signal φt from the power supply device 1 received by the secondary-side metal detection coil Lb. As in 5 As shown, the modulation circuit 20 includes a matching circuit MC, a rectifier circuit 21, a modulation wave signal generation circuit section 22, and a modulation circuit section 23.

The matching circuit MC performs the impedance matching so that the secondary-side metal detection coil Lb has a resonance point near the frequency of the oscillation signal φt sent from the primary-side metal detection coil La. In the present embodiment, the matching circuit MC is constructed by a resonance capacitor Cx, for example (see FIG 6 ).

The rectifier circuit 21 is a half-wave rectifier circuit. As in 6 As shown, the rectifying circuit 21 includes a rectifying diode D0, a charging and discharging capacitor C0, and a resistor R0. An anode terminal of the rectification diode D0 is connected to a positive terminal PT of the secondary-side metal detection coil Lb via the resonance capacitor Cx of the matching circuit MC. A cathode terminal of the rectifying diode D0 is connected to a positive terminal of the charge and discharge connected to the decapacitor C0. A negative terminal of the charging and discharging capacitor C0 is connected to a negative terminal NT of the secondary side metal detection coil Lb. The resistor R0 is connected in parallel with the charging and discharging capacitor C0. The rectifier circuit 21 receives the oscillation signal φt sent from the primary-side metal detection coil La of the power supply device 1 to the secondary-side metal detection coil Lb. The rectifier circuit 21 half-wave rectifies the oscillation signal φt.

As in 10 As shown, the oscillation signal φt in the present embodiment is a sine wave having a constant amplitude value and constant frequency. Consequently, when the rectifying diode D0 half-wave rectifies the oscillation signal φt received from the secondary-side metal detection coil Lb, the charging and discharging capacitor C0 repeats charging and discharging. In other words, the charging and discharging capacitor C0 is charged with current from the rectification diode D0 when the oscillation signal φt has a positive electric potential. The charged charging and discharging capacitor C0 is discharged through the resistor R0 when the oscillation signal φt has a negative electric potential.

When an object (load) is present between the primary-side metal detection coil La and the secondary-side metal detection coil Lb, the object (load) that is spatially coupled changes the value of the current flowing to the secondary-side metal detection coil Lb.

For example, the amplitude of the oscillation signal Φt, as in 10A shown, maximum when nothing is placed on the support surface 3, i.e. in an open condition free of loads. Consequently, the value of the current flowing to the secondary-side metal detection coil Lb becomes maximum.

When a metal piece M is set on the setting surface 3, the frequency of the oscillation signal φt changes and the amplitude of the oscillation signal φt becomes minimum, such as in FIG 10E shown. Consequently, the value of the current flowing to the secondary-side metal detection coil Lb becomes small.

In other words, when nothing is set on the setting surface 3, a charging voltage Vt of the charging and discharging capacitor C0 takes a maximum value. In contrast, when the metal piece M is set on the setting surface 3, the charging voltage Vt of the charging and discharging capacitor C0 becomes a minimum value.

As in 5 1, the charging voltage Vt of the charging and discharging capacitor C0 is applied to the modulation wave signal generation circuit portion 22 as a power supply voltage VG. When the positional relationship of the primary-side metal detection coil La relative to the secondary-side metal detection coil Lb changes, the inductances of the primary-side metal detection coil La and the secondary-side metal detection coil Lb change, and the amplitude value and frequency of the oscillation signal φt change accordingly. In this case, the amount of change in the amplitude value and the frequency is large compared to a change in the amplitude value and the frequency caused by the displacement of the primary-side metal detection coil La and the secondary-side metal detection coil Lb when the metal piece M is interposed. Consequently, a change in the oscillation signal Φt allows a displacement between the coils La and Lb to be distinguished from a metal piece M present between the coils La and Lb.

As in 7 1, the modulation wave signal generation circuit section 22 is formed by, for example, an astable multivibrator (hereinafter referred to simply as the multivibrator) 22a. The multivibrator 22a is a typical multivibrator constructed by two transistors Q1 and Q2, two capacitors C1 and C2, and four resistors R1a, R1b, R2a and R2b.

The multivibrator 22a is connected to a power line 25 . The charging voltage Vt is applied from the charging and discharging capacitor C0 of the rectifying circuit 21 to the power line 25 as the power supply voltage VG. The multivibrator 22a of the present invention outputs an ON/OFF signal M (modulation wave) from a collector terminal of the transistor Q1. The ON/OFF signal MP is provided to the modulation circuit section 23 .

The multivibrator 22a controls a duty DU (DU=t1/Tn) of the ON/OFF signal MP with a value of the present power supply voltage VG. This is because a change in the power supply voltage VG changes an initial value of a potential between the base and the emitter when the transistor Q1 is turned from ON to OFF, and a rate of change between the base and the emitter changes when the transistor Q2 is turned OFF.

As in 10B shown, the multivibrator 22a generates the ON/OFF signal MP so that the Duty time DU (DU=t1/Tn) decreases, that is, an OFF time t1 is shortened relative to a period Tn, as the value of the power supply voltage VG increases.

In contrast, when the multivibrator 22a as in 10F shown generates the ON/OFF signal such that the duty time DU (DU = t1/Tn) increases, that is, the ON time t1 is lengthened relative to the period Tn, the value of the power supply voltage VG decreases when the metal piece is placed on the setting surface 3.

In other words, the multivibrator 22a outputs the ON/OFF signal MP with a long operation time from the collector terminal of the transistor Q1 when there is a metal M, compared to when there is no metal M.

As in 5 1, the ON/OFF signal MP output from the collector terminal of the transistor Q1 of the multivibrator 22a is provided to the modulation circuit portion 23. FIG.

As in 6 1, the modulation circuit portion 23 includes a transistor Q3 and a diode D1. The diode D1 has an anode terminal connected to the anode terminal of the rectifying diode D0 of the rectifier circuit 21 and to the resonance capacitor Cx, and a cathode terminal connected to a collector terminal of the transistor Q3. A base terminal of the transistor Q3 is connected to the collector terminal of the transistor Q1 of the multivibrator 22a. An emitter terminal of the transistor Q3 is grounded.

The transistor Q3 is turned ON and OFF by the ON/OFF signal MP from the multivibrator 22a provided to the base terminal.

Consequently, when the transistor Q3 is turned ON, some of the charging current that charges the charging and discharging capacitor C0 flows to the modulation circuit section 23 through the rectifying diode D0, that is, to the transistor Q3 via the diode D1. On the other hand, when the transistor Q3 is turned OFF, the charging current that charges the charging and discharging capacitor C0 via the rectifying diode D0 flows through the rectifying diode D0 to the charging and discharging capacitor C0 without flowing to the transistor Q3 (modulation circuit section 23). .

As a result, the value of the secondary current flowing between the terminals PT and NT of the secondary-side metal detection coil Lb is changed based on the oscillation signal φt by the ON/OFF of the transistor Q3. The change in the secondary current changes the magnetic flux emitted from the secondary-side metal detection coil Lb. The changed magnetic flux is propagated to the primary-side metal detection coil La as electromagnetic induction. This changes the value of the primary current flowing to the primary-side metal detection coil La.

Consequently, the ON/OFF of the transistor Q3 (by the duty DU of the ON/OFF signal MP) modulates the amplitude of the current (oscillation signal φt) flowing between the terminals PT and NT of the secondary-side metal detection coil Lb and generates the modulated wave signal φm . The modulated wave signal Φm is transmitted from the secondary-side metal detection coil Lb to the primary-side metal detection coil La.

In other words, the oscillation signal φt received from the secondary-side metal detection coil Lb acts as a carrier signal. In the device E, the charging voltage Vt, that is, the power supply voltage VG is generated based on the amplitude value of the carrier signal, and the ON/OFF signal MP of the duty DU corresponding to the value of the power supply voltage VG is generated as the modulation wave signal. This in 10C and 10G The modulated wave signal Φm shown is generated by modulating the amplitude of the carrier signal (oscillation signal Φt) with the modulation wave signal (duration-controlled ON/OFF signal MP).

For example, if there is no piece of metal M in the power supply area AR, the in 10C shown modulated wave signal Φm generated by the oscillation signal Φt with the in 10B shown ON/OFF signal MP is modulated.

When the metal piece M is present in the power supply area AR, the in 10G shown modulated wave signal Φm generated by the oscillation signal Φt with the in 10F shown ON/OFF signal MP is modulated.

Consequently, an envelope waveform of the modulated wave signal Φm is represented by a waveform relative to the duty time DU of the ON/OFF signal MP (modulation wave).

(power supply device 1)

As in 3 As shown, the power supply device 1 comprises a common unit section 30 and a base unit section 40.

The common unit section 30 includes a power supply circuit 31 that supplies power to the base unit section 40, a system control unit 32 that centrally controls the base unit section 40, and a non-volatile memory 33 that stores various kinds of data.

The power supply circuit 31, which includes a rectifier circuit and a DC-DC converter (both not shown), rectifies commercial power supplied from the outside into DC voltage with the rectifier circuit. The power supply circuit 31 converts the DC voltage into a desired DC voltage Vdd with the DC-DC converter. The DC voltage Vdd is supplied to the system controller 32, the non-volatile memory 33 and the base unit section 40 as driving power.

The system control unit 32, which includes a microcomputer, controls the base unit section 40. The non-volatile memory 33 stores various kinds of data used when the system control unit 32 performs various determination processes.

As in 3 As shown, the base unit section 40 includes the base power supply unit circuits 4 for the power supply area AR (primary coils L1). The basic power supply unit circuit 4 exchanges data with the system controller 32 under the control of the system controller 32 .

The basic power supply unit circuits 4 have the same structure. Thus, for the sake of brevity, one of the basic power supply unit circuits 4 will be explained with reference to FIG 8th described.

As in 8th As shown, the basic power supply unit circuit 4 comprises a receiving circuit section 41, a signal extraction circuit section 42, a power supply coil excitation drive circuit section 43, and a metal detection circuit section 44.

The receiving circuit section 41 is connected to the signal receiving antenna coil A1. The reception circuit section 41 receives a transmission signal from the signal transmission antenna coil A2 of the device E set on the seating surface 3 through the signal reception antenna coil A1. The reception circuit section 41 provides the received transmission signal to the signal extraction circuit section 42 .

The signal extraction circuit section 42 extracts the device authentication signal ID and the stimulation request signal RQ from the transmission signal received from the reception circuit section 41 . The signal extraction circuit section 42 transmits a permission signal EN to the system control unit 32 after extracting both the device authentication signal ID and the excitation request signal RQ. The signal extraction circuit section 42 does not transmit the permission signal EN to the system control unit 32 when only either the device authentication signal ID or the excitation request signal RQ is extracted or when both signals are not extracted.

The power supply coil excitation drive circuit section 43 is connected to the primary coil L1. In the present embodiment, the power supply coil excitation drive circuit section 43 includes a full bridge circuit 43a that excites the primary coil L1, a drive circuit 43b that drives the full bridge circuit 43a, and a presence detection circuit 43c. The presence detection circuit 43c is an example of a detection circuit.

The full bridge circuit 43a is a typical full bridge circuit. As in 9 As shown, the full bridge circuit 43a includes four MOS transistors Qa, Qb, Qc and Qd. A pair of MOS transistors Qa and Qd is cross-connected to a pair of MOS transistors Qb and Qc through a series connection of the primary coil L1 and the resonance capacitor C. The two pairs are turned ON and OFF alternately to energize the primary coil L1.

The drive circuit 43b receives an excitation control signal CT from the system control unit 32 of the common unit section 30 and generates drive signals PSa, PSb, PSc and PSd. The drive signals PSa, PSb, PSc and PSd are provided to the gates of the MOS transistors Qa, Qb, Qc and Qd.

When power is supplied to the device E, the drive circuit 43b generates the drive signals PSa, PSb, PSc and PSd to turn ON and OFF the two pairs of the full bridge circuit 43a based on the excitation control signal CT from the system controller 32. In this way, the driving circuit 43b excites the primary coil L1 by the full bridge operation of the circuit 43a.

The drive circuit 43b supplies the drive signals PSa, PSd having the same pulse waveform to the gates of the MOS transistors Qa and Qd, respectively. The drive circuit 43b also supplies the drive signals PSb and PSc, which have the same pulse waveform and pulse waveform, respectively, to the gates of the MOS transistors Qb and Qc. The pulses of the drive signals PSa and PSd are signals complementary to the pulses of the drive signals PSb and PSc.

Accordingly, when power is supplied to the device E, the pair of MOS transistors Qa and Qd and the pair of MOS transistors Qb and Qc are alternately turned ON/OFF (full bridge operation), and the primary coil L1 is excited.

In a standby state, the drive circuit 43b generates the drive signals PSa, PSb, PSc and PSd to change the operation of the full bridge circuit 43a exciting the primary coil L1 from the full bridge operation to the half bridge operation based on the excitation control signal CT from the system controller 32.

In the half-bridge operation, for example, the MOS transistor Qa and the MOS transistor Qb are alternately turned ON and OFF in a state where the MOS transistor Qd is turned ON and the MOS transistor Qc is turned OFF .

For example, when the MOS transistors Qa, Qb, Qc and Qd are N-channel types, the drive circuit 43b provides a high-level drive signal PSd to the MOS transistor Qd and generates and provides a low-level drive signal PSc to the MOS transistor Qc. Further, the drive circuit 43b provides the complementary drive signals PSa and PSb to the MOS transistors Qa and Qb, respectively, so that the MOS transistor Qa and the MOS transistor Qb are turned ON and OFF alternately.

During the standby state, the full-bridge circuit 43a operates as a half-bridge to excite the primary coil L1 and reduce interference caused by magnetic coupling between adjacent primary coils L1. This increases the accuracy for detecting the presence of the device E set to the power supply area AR during the standby state.

When an object is placed in the power supply area AR, the spatially coupled object (load) changes the value of current flowing to the primary coil L1. As described above, when nothing is set in the power supply area AR (open state in which the load is absent), the value of the current flowing to the primary coil L1 becomes maximum. In contrast, when the object is placed in the power supply area AR (when the load is present), the value of the current flowing to the primary coil L1 decreases as the load increases.

The drive circuit 43b continues to output the drive signals PSa, PSb, PSc and PSd when the system controller 32 outputs the excitation control signal CT to operate the full bridge circuit 43a as a full bridge. Consequently, in this case, the full bridge circuit 43a continuously excites and drives the primary coil L1.

In contrast, when the system controller 32 outputs the excitation control signal CT, the drive circuit 43b intermittently outputs the drive signals PSa, PSb, PSc and PSd for every predetermined period (e.g., a fixed period) to operate the full bridge circuit 43a as a half bridge. Consequently, the full bridge circuit 43a intermittently excites and drives the primary coil L1.

The secondary power supplied to the power receiving device (device E) by intermittently exciting and driving the primary coil L1 is not sufficient to drive the load Z of the device E immediately when the device E is on the setting surface 3 is set, but is sufficient to charge the rechargeable battery of load Z. In this case, the data generation circuit section 13 and the transmission circuit section 14 of the device E are driven by the secondary power, and wireless communication is performed between the device E and the power supply device 1 .

Further, when the system control unit 32 determines that a metal piece M is set on the power supply area AR, the excitation drive circuit 43 intermittently excites and drives the primary coil L1 based on the excitation control signal CT. Consequently, although the rechargeable battery of the load Z can be charged while intermittently exciting and driving the primary coil L1, the temperature of the metal piece M set on the power supply area AR is prevented from being greatly increased by inductive heating.

Further, the excitation driving circuit 43 intermittently excites and drives the primary coil L1 in the same manner as when the apparatus is not set to the power supply area AR based on the excitation control signal CT even when the signal extraction circuit section 42 does not output the permission signal EN to the system control unit 32.

The presence detection circuit 43c detects the current flowing to the primary coil L1 and generates the voltage corresponding to the current value of the detected current as a presence detection voltage Vx. The presence detection voltage Vx is supplied to the system control unit 32 . The presence detection voltage Vx serves as a detection signal.

When the primary coil L1 is detected and driven, as long as there is no object (load) on the primary coil L1 (power supply area AR), there is no object (load) that is spatially coupled. Consequently, the value of the current flowing to the primary coil L1 becomes high. When an object (load) is present in the primary coil L1 (load supply area AR), the object (load) that is spatially coupled decreases the current flowing to the primary coil L1.

Consequently, the presence detection circuit 43c increases the value of the presence detection voltage Vx when there is no object on the primary coil L1 (power supply area AR). The presence detection circuit 43c decreases the value of the presence detection voltage Vx when the object (load) is present on the primary coil L1 (power supply area AR).

The system control unit 32 receives the presence detection voltage Vx and determines that something is set to the power supply area AR when the presence detection voltage Vx is between a lower reference voltage Vk1 and an upper reference voltage Vk2 as determined in advance (Vk1<Vx<Vk2).

When the presence detection voltage Vx is greater than or equal to the upper reference voltage Vk2, the system controller 32 determines that nothing is set to the power supply area AR. If the presence detection voltage Vx is less than or equal to the lower reference voltage Vk1, the system control unit 32 determines that something is set on the power supply area AR, and that the object (load) that is placed does not appear to be the device E that supplies power should be.

The lower reference voltage Vk1 and the upper reference voltage Vk2 are set in advance to values obtained through experiments, tests, calculations and the like, and are stored in the non-volatile memory 33 of the common unit section 30 in advance. The system controller 32 reads the lower reference voltage Vk1 and the upper reference voltage Vk2 from the non-volatile memory 33 and compares them with the presence detection voltage Vx.

As in 8th As shown, the metal detection circuit section 44 includes an oscillation circuit 44a, a signal extraction circuit 44b, and an on-time calculation circuit 44c.

The oscillation circuit 44a is connected to the primary-side metal detection coil La. In the present embodiment, the oscillation circuit 44a and the primary-side metal detection circuit La construct a Colpitts oscillation circuit. The oscillating circuit 44a performs the oscillating operation based on the DC voltage applied from the power supply circuit 31 . The oscillating circuit 44a transmits the oscillating signal φt transmitted by an in 10A shown sine wave having a fixed amplitude and frequency is formed from the primary-side metal detecting coil La toward the secondary-side metal detecting coil Lb of the device E set on the setting surface 3 .

The oscillation signal φt oscillated by the oscillation circuit 44a constructs a carrier signal as described above. In other words, the device E generates the ON/OFF signal MP based on the amplitude value of the oscillation signal φt. The device E generates the modulated wave signal Φm by amplitude-modulating the carrier signal with the ON/OFF signal MP having an operation time corresponding to the amplitude value, and the device E sends the modulated wave signal Φm from the secondary-side metal detection coil Lb If the positional relationship of the primary-side metal detection coil La relative to the secondary-side metal detection coil Lb changes, the inductances of the primary-side metal detection coil La and the secondary-side metal detection coil Lb change, and the amplitude value and frequency of the oscillation signal φt change accordingly. In this case, the amount of change in the amplitude value and the frequency when the metal piece M is sandwiched between the primary-side metal detecting coil La and the secondary-side metal detecting coil Lb is large compared to the change in the amplitude value and the frequency caused by the shift between the primary-side metal detection coil La and the secondary side metal detection coil Lb. Consequently, the change in the oscillation signal Φt allows the displacement of the coils La and Lb to be distinguished from the presence of a metal piece M between the coils La and Lb.

The modulated wave signal Φm obtained in 10C or 10G 1 and generated in the device E is received by the primary-side metal detection coil La of the power supply apparatus 1 and supplied to the signal extraction circuit 44b via the oscillation circuit 44a.

The signal extraction circuit 44b includes an envelope detection circuit that detects the modulated wave signal Φm provided via the oscillation circuit 44a. The signal extraction circuit 44b (envelope detection circuit) demodulates an envelope waveform signal (demodulation signal DMP) of the modulated wave signal Φm, that is, the ON/OFF signal MP, from the modulated wave signal Φm. The signal extraction circuit 44b (envelope detection circuit) includes a waveform shaping circuit that waveforms the demodulation signal DMP (ON/OFF signal MP).

The duty calculation circuit 44c calculates the duty DU of the demodulation signal DMP (ON/OFF signal MP). In the present embodiment, the duty calculation circuit 44c obtains the period Tn and the ON time of the demodulation signal DMP (ON/OFF signal MP). The duty calculation circuit 44c calculates the duty time DU (DU=t1/Tn) from the period Tn and the ON time t1. The duty calculation circuit 44c supplies the system control unit 32 with the duty DU of the ON/OFF signal MP obtained as a calculation value.

The system control unit 32 determines whether or not a metal piece M is present based on the duty time DU of the demodulation signal DMP (ON/OFF signal MP) from the duty time calculation circuit 44c. For example, the system control unit 32 compares a reference operation time DUk stored in advance in the non-volatile memory 33 of the common unit section 30 and the operation time DU of the demodulation signal DMP (ON/OFF signal MP) to determine whether the metal piece M is present is or not.

The reference duty time DUk is a duty time DU calculated in the duty time calculation circuit 44c based on the modulated wave signal Φm received from the metal detection circuit section 44 in a state where the metal piece M is not interposed between the power supply area AR and the device E. The reference operation time DUk is set to a value obtained in advance through experiments, tests, calculations and the like and stored in the non-volatile memory 33 in advance.

Consequently, in a state where the metal piece M is placed in the power supply area AR, the amplitude of the oscillation signal φt becomes smaller, and the duty time DU of the ON/OFF signal MP becomes longer. As a result, the system control unit 32 determines that there is no metal piece M in the power supply area AR when the duty time DU from the duty time calculation circuit 44c is greater than the reference duty time DUk. In contrast, the system control unit 32 determines that there is no metal piece in the power supply area AR when the duty time DU from the duty time calculation circuit 44c is less than or equal to the reference duty time DUk.

The system control unit 32 receives the presence detection voltage Vx from the presence detection circuit 43c and waits for the ON/OFF signal duty DU to be provided by the duty calculation circuit 44c after determining that the presence detection voltage Vx is between the lower reference voltage Vk1 and the upper reference voltage Vk2 is. If it is then determined that the metal piece M is not present in the power supply area AR, the system control unit 32 waits for the permission signal EN from the signal extraction circuit section 42. If it receives the permission signal EN from the signal extraction circuit section 42 in this state, the system control unit 32 sets the excitation control signal and excitation control control signal CT, which is for the full bridge operation, to the power supply coil excitation drive circuit section 43 of the basic power supply unit circuit 4, respectively.

When the presence detection voltage Vx from the presence detection circuit 43c is not between the lower reference voltage Vk1 and the upper reference voltage Vk2, the system control unit 32 does not provide the excitation control signal CT, which is for full bridge operation, to the power supply coil excitation drive circuit section 43. In this case, the system control unit 32 provides the excitation control signal CT, which is for the half-bridge operation, to the power-supply coil excitation drive circuit section 43, and intermittently excites and drives the primary coil L1.

In the same way, when the permission signal EN is not received from the signal extraction circuit section 42, the system control unit 32 supplies the excitation control signal CT, which is for the half-bridge operation, to the power con supply coil excitation drive circuit section 43, and intermittently excites and drives the primary coil L1.

In the same way, when it is further determined that a piece of metal is present in the power supply area AR, the system control unit 32 provides the excitation control signal CT, which is for the half-bridge operation, to the power supply coil excitation drive circuit section 43, and excites and drives the primary coil L1 intermittently .

The operation of the power supply device 1 will now be described.

When a power switch (not shown) is turned ON and commercial power is supplied to the power supply circuit 31, the power supply circuit 31 supplies DC voltage as driving power to the system controller 32, the non-volatile memory 33 and each basic power supply unit circuit 4.

When the drive power is received from the power supply circuit 31, the system control unit 32 provides the excitation control signal CT, which is for the half-bridge operation of the full-bridge circuit 43a of the basic power supply unit circuit 4, to the drive circuit 43b.

The drive circuit 43b of the basic power supply unit circuit 4 operates the full bridge circuit 43a as a half bridge, and intermittently excites and drives the primary coil L1 in response to the excitation control signal CT.

Then, the power supply device waits for the device E to be set in the power supply area AR of the setting area 3 . In this state, the system control unit 32 repeatedly performs (a) the presence detection processing operation, the metallic foreign body detection processing operation, and (3) a machine type detection processing operation.

In the presence detection processing mode, the system control unit 32 controls the basic power supply unit circuit 4 (power supply coil excitation drive circuit section 43) and detects whether or not an object is set on/in the power supply area AR.

In the metal foreign matter detection processing operation, the system control unit 32 controls the basic power supply unit circuit 4 (metal detection circuit section 44) and performs the detection of the metal piece M in the power supply area AR.

In the machine type detection processing operation, the system control unit 32 controls the basic power supply unit circuit 4 (receiving circuit section 41 and signal extraction circuit section 42) and performs detection of a power supply request of the device E.

The presence detection processing operation, the metal foreign body detection processing operation, and the machine type detection processing operation will now be described in detail.

(presence detection processing operation)

The presence detection circuit 43c, which is arranged in the power supply coil excitation drive circuit section 43 of each basic power supply unit circuit 4, detects the value of the current flowing to the corresponding primary coil L1 as the presence detection voltage Vx. Each presence detection circuit 43c supplies the presence detection voltage Vx to the system control unit 32.

When receiving the presence detection voltage Vx from the presence detection circuit 43c, the system control unit 32 determines whether or not the presence detection voltage Vx is between the lower reference voltage Vk1 and the upper reference voltage Vk2. When the presence detection voltage Vx is between the lower reference voltage Vk1 and the upper reference voltage Vk2, the system control unit 32 determines that an object is present in the power supply area AR to which the presence detection circuit 43c belongs.

When the presence detection voltage Vx is greater than or equal to the upper reference voltage Vk2, the system control unit 32 determines that there is no object in the power supply area AR to which the presence detection circuit 43c belongs.

(Metal Foreign Matter Detection Processing Operation)

The oscillating circuit 44a of the metal detecting circuit section 44 in each basic power supply unit circuit 4 is oscillated based on the application of the DC voltage and transmits the oscillating signal φt from the corresponding primary-side metal detecting coil La.

The secondary-side metal detection coil Lb of the device E receives the oscillation signal φt from the primary-side metal detection coil La. The rectification circuit 21 of the modulation circuit 20 half-wave rectifies the oscillation signal φt received from the secondary-side metal detection coil Lb (see FIG 6 ).

The DC voltage obtained by half-wave rectifying the oscillation signal φt is supplied as the charging voltage Vt (power supply voltage VG) to the modulation wave signal generating circuit section 22 (multivibrator 22a) (see FIG 7 ).

The value of the DC voltage (power supply voltage VG) generated by the rectifier circuit 21 is modulated by the amplitude value of the oscillation signal φt, that is, according to whether or not a metal piece M is present in the power supply area AR.

When no piece of metal is set in the power supply area AR, the oscillation signal φt oscillates as shown in FIG 10A shown. On the other hand, when a metal piece M is set in the power supply area AR, the oscillation signal φt oscillates as shown in FIG 10E shown. Consequently, when the metal piece M is not set in the power supply area AR, the amplitude value of the oscillation signal φt, that is, the charging voltage value Vt becomes large compared to when the metal piece M is present.

As a result, the duty DU of the ON/OFF signal MP output from the multivibrator 22a becomes as shown in FIG 10B shown when no piece of metal is set on the power supply area AR, and is as shown in FIG 10F shown when a metal piece M is set in the power supply area AR. That is, as in 10B and 10F 1, the duty time DU of the ON/OFF signal MP becomes long when a metal piece M is put on the power supply area AR, compared to when no metal piece is put on.

The ON/OFF signal MP is applied to the gate of the transistor Q3 of the modulation circuit portion 23 to turn the transistor Q3 ON and OFF. By turning ON and OFF the transistor Q3, the current (oscillation signal φt) flowing to the secondary-side metal detection coil Lb is amplitude-modulated and generated as the modulated wave signal φm. The modulated wave signal Φm is transmitted from the secondary-side metal detection coil Lb to the primary-side metal detection coil La.

In this case, when the metal piece M is not set in the power supply area AR, the waveform of the modulated wave signal Φm becomes as shown in FIG 10C shown, according to the operating time DU of the in 10B generated ON/OFF signal shown. When the metal piece M is set in the power supply area AR, the waveform of the modulated wave signal Φm becomes as shown in FIG 10G shown, according to the operating time DU of the in 10F generated ON/OFF signal shown.

The primary-side metal detection coil La receives the modulated wave signal Φm transmitted from the secondary-side metal detection coil Lb. The modulated wave signal Φm received from the primary-side metal detection coil La is provided to the signal extraction circuit 44b (detection circuit) through the oscillation circuit 44a.

The signal extraction circuit 44b (detection circuit) demodulates the envelope waveform signal (demodulation signal DMP) that envelopes the outside of the modulated wave signal Φm, that is, the ON/OFF signal MP, from the modulated wave signal Φm. The signal extraction circuit 44b (detection circuit) supplies the demodulation signal DMP (ON/OFF signal MP) to the duty calculation circuit 44c.

Consequently, the duty cycle DU of the demodulation signal DMP (ON/OFF signal MP) generated from the signal extraction circuit 44b becomes as shown in FIG 10D shown when no metal piece M is set in the power supply area AR, and as in FIG 10H shown when the metal piece M is set in the power supply area AR. That is, the duty time DU of the demodulation signal DMP (ON/OFF signal MP) when no metal piece is set becomes as shown in FIG 10B and 10F shown, large compared to when a piece of metal is set in the power supply area AR.

The signal extraction circuit 44b (detection circuit) supplies the demodulation signal DMP (ON/OFF signal MP) to the duty calculation circuit 44c. The duty calculation circuit 44c calculates the duty time DU of the demodulation signal DMP (ON/OFF signal MP) and provides the calculation value (DU) to the system control unit 32 .

The system control unit 32 compares the duty cycle DU of the demodulation signal DMP (ON/OFF signal MP) provided from each basic power supply unit circuit 4 with the reference duty cycle DUk.

The system control unit 32 determines that a metal piece M is present in the power supply area AR immediately above the primary-side metal detection coil La excited by the corresponding metal detection circuit section 44 when the duty time DU of the demodulation signal DMP (ON/OFF signal MP) is greater than the Reference operating time DUk is.

When the duty time DU of the ON/OFF signal is less than or equal to the reference duty time DUk, the system control unit 32 determines that there is no metal piece M in the power supply area AR immediately above the primary-side metal detection coil La excited by the corresponding metal detection circuit section 44. when the duty time DU of the ON/OFF signal MP is less than or equal to the reference duty time DUk.

(Detection processing operation for machine type)

When the device E is set in the power supply area AR, the secondary coil L2 of the device E receives the secondary power based on the intermittent exciting and driving of the primary coil L1. Based on the secondary power, the device E generates the device authentication signal ID and the excitation request signal RQ with the data generation circuit section 13 of the power receiving circuit 10. The transmission circuit section 14 sends the device authentication signal ID and the excitation request signal RQ from the signal transmission antenna coil A2 toward the signal reception antenna coil A1 of the power supply device 1.

The signal extraction circuit section 42 of the power supply device 1 extracts the device authentication signal ID and the excitation request signal RQ from the transmission signal received from the reception circuit section 41 through the signal reception antenna coil A<b>1 . The signal extraction circuit section 42 provides the permission signal EN to the system control unit 32 after both the device authentication signal ID and the extraction request signal RQ are extracted.

When the permission signal EN is received from the signal extraction circuit section 42, the system control unit 32 determines that the equipment E, which is of an engine type that can be powered by the power supply device 1, enters the power supply area AR to which the signal extraction circuit section 42 belongs. is set.

When the permission signal EN is not received from the signal extraction circuit section 42, the system control unit 32 determines that the device E or an object that cannot be supplied with power from the power supply device 1 is set in the power supply area AR, even if determined in the presence detection processing operation became that an object is set.

(power supply for device E)

The system control unit 32 repeats the presence detection processing operation, the metallic foreign body detection processing operation, and the machine type detection processing operation. The system control unit 32 continuously excites and drives the primary coil L1 located immediately below the power supply area AR when the presence of the object is detected in any of the power supply areas AR, determining that the metal piece M is not present and the permission signal EN generated when the object is device E is received. In other words, the system control unit 32 supplies the excitation control signal CT, which operates the full bridge circuit 43a as a full bridge, to the drive circuit 43b of the basic power supply unit circuit 4 of the power supply area AR in which the device E is set.

When the primary coil L1 is continuously excited and driven, the device E placed on the power supply area AR of the power supply device 1 receives the secondary power via the secondary coil L2 based on the continuous exciting and driving of the primary coil L1. The device E supplies the power for driving the load Z from the power receiving circuit 10 (rectification smoothing circuit section 11 and DC-DC converter circuit 12) to the load Z.

The system control unit 32 stops the supply of power to the device E when it is detected in the metal foreign matter detection processing operation that a metal piece M is present in the power supply area AR to which power is supplied. In this case, the system control unit 32 switches the exciting operation of the primary coil L<b>1 of the power supply area AR from the continuous exciting and driving to the intermittent exciting and driving. In other words, the system control unit 32 supplies the excitation control signal CT, which operates the full bridge circuit 43a as a half bridge, to the driving circuit 43b of the basic power supply unit circuit 4 ready, which is located immediately below the device E.

The system control unit 32 also stops the power supply to the device E when it is detected in the presence detection processing operation that the device E has been removed from the power supply area AR being powered. Here, the system control unit 32 switches the exciting operation of the primary coil L<b>1 of the power supply area AR from the continuous exciting and driving to the intermittent exciting and driving in the same manner. In other words, the system control unit 32 provides the excitation control signal CT for the half-bridge operation of the full-bridge circuit 43a to the drive circuit 43b for exciting the primary coil L1, which is located directly below the device E.

In addition, the system control unit 32 also stops the power supply to the device E even if it is detected in the machine type detection processing operation that the excitation request signal RQ is no longer output from the device E being powered and the permission signal EN is absent . Also in this case, the system control unit 32 switches the energizing operation of the primary coil L1 located immediately under the power supply area AR from the continuous energizing and driving to the intermittent energizing and driving. In other words, the system control unit 32 provides the excitation control signal CT, which operates the full bridge circuit 43a as a half bridge, to the drive circuit 43b, which excites the primary coil L1 located immediately below the device E.

• (1) Eine Vielzahl von Leistungsversorgungsbereichen AR ist in der Auflage- bzw. Setzfläche 3 der Leistungsversorgungsvorrichtung 1 definiert, und die Primärspule L1 ist in jedem Leistungsversorgungsbereich AR angeordnet. Folglich wird die Primärspule L1 des Leistungsbereichs AR, in den das Gerät E gesetzt ist, ungeachtet des Leistungsversorgungsbereichs AR der Setzfläche 3, in den das Gerät E gesetzt ist, angeregt und angetrieben. Dies erlaubt, dass die Leistungsversorgungsvorrichtung 1 ungeachtet des Leistungsversorgungsbereichs AR der Setzfläche 3, in den das Gerät E gesetzt ist, Leistung an das Gerät E liefert.
• (2) Die primärseitige Metalldetektionsspule La zum Durchführen der Metalldetektion ist in jedem Leistungsversorgungsbereich AR angeordnet. Folglich kann die Leistungsversorgungsvorrichtung 1 das Metallstück M ungeachtet des Leistungsversorgungsbereichs AR der Setzfläche 3, in den das Metallstück M gesetzt ist, detektieren.
• (3) Die Leistungsversorgungsvorrichtung 1 bestimmt mit der Betriebszeit DU des EIN/AUS-Signals MP, ob ein Metallstück M vorhanden ist oder nicht. Mit anderen Worten wird das EIN/AUS-Signal MP als eine Modulationswelle erzeugt. Somit wird die Metalldetektion, selbst wenn die benachbarten Primärspulen L1 miteinander interferieren, womit sie die Anregungsfrequenz in der Leistungsversorgungsvorrichtung 1, in der eine Vielzahl von Primärspulen 1 benachbart angeordnet sind, ändern, mit hoher Genauigkeit durchgeführt und wird fast unmerklich durch Änderungen der Anregungsfrequenz beeinträchtigt.
• (4) Die Systemkontrolleinheit 32 bestimmt basierend auf der Betriebszeit DU, die von dem Metalldetektionsschaltungsabschnitt 44 jeder Basisleistungsversorgungseinheitsschaltung 4 berechnet wird, ob in jedem Leistungsversorgungsbereich AR ein Metallstück M vorhanden ist oder nicht. In diesem Aufbau bestimmt die Systemkontrolleinheit 32 einfach durch Vergleichen der Betriebszeit DU von dem Metalldetektionsschaltungsabschnitt 44 jeder Basisleistungsversorgungseinheitsschaltung 4 mit der Referenzbetriebszeit DUk, ob ein Metallstück M vorhanden ist oder nicht. Als ein Ergebnis kann die Last der Systemkontrolleinheit 32 drastisch verringert werden.
• (5) Die Information, die angibt, ob ein Metallstück M vorhanden ist oder nicht, das heißt, das EIN/AUS-Signal MP, wird in dem Gerät E erzeugt. Dies vereinfacht den Schaltungsaufbau und verringert die Verarbeitungslast für die Leistungsversorgungsvorrichtung 1. Folglich kann eine kostengünstige kontaktlose Leistungsversorgungsvorrichtung realisiert werden.
• (6) Wenn das modulierte Wellensignal Φm erzeugt wird, wird das Oszillationssignal Φt von der Oszillationsschaltung 44a des Metalldetektionsschaltungsabschnitts 44 als ein Trägersignal verwendet. Dies erlaubt das Eliminieren einer Oszillationsschaltung, die das Trägersignal getrennt erzeugt.
• (7) Das modulierte Wellensignal Φm wird durch Amplitudenmodulation erzeugt. Folglich hat die Schaltung zum Erzeugen des modulierten Wellensignals Φm im Vergleich dazu, wenn es durch andere Frequenzmodulationen oder ähnliches erzeugt wird, einen einfachen Aufbau, und die Schaltung kann kostengünstig aufgebaut werden. Die Signalextraktionsschaltung 44b (Detektionsschaltung), die das modulierte Wellensignal Φm demoduliert, kann auch leicht und kostengünstig aufgebaut werden.
• (8) Die Ladespannung Vt des Lade- und Entladekondensators C0 der Gleichrichterschaltung 21 wird als die Leistungsversorgungsspannung VG an den Multivibrator 22a des Modulationswellensignal-Erzeugungsschaltungsabschnitts 22 geliefert. In diesem Aufbau wird die Betriebszeit DU des EIN/AUS-Signals MP des Multivibrators 22a durch die Leistungsversorgungsspannung VG geändert, die sich dementsprechend ändert, ob ein Metallstück M vorhanden ist oder nicht. Folglich wird die Modulationswelle (EIN/AUS-Signal MP), die anzeigt, ob ein Metallstück M vorhanden ist oder nicht, mit dem Multivibrator 22a, der einen einfachen Schaltungsaufbau hat, erzeugt.
• (9) Die Leistungsversorgungsvorrichtung 1 ändert die Anregungsfrequenz der Primärspule L1 zum Liefern von Leistung in jeder Basisleistungsversorgungseinheitsschaltung 4, wenn die Metalldetektion durchgeführt wird. Als ein Ergebnis braucht in der Primärspule L1 keine Vielzahl von Anregungsfrequenzen festgelegt werden, und die Anregungsfrequenz der Primärspule braucht nicht, wann immer die Metalldetektion durchgeführt wird, umgeschaltet werden. Eine komplexe und teure Kontrollschaltung wird auf diese Weise unnötig. Dies realisiert eine kostengünstige kontaktlose Leistungsversorgungsvorrichtung.
• (10) Die Leistungsversorgungsvorrichtung betreibt die Vollbrückenschaltung 43a während eines Bereitschaftszustands als Halbbrücke. Folglich werden Interferenzen, die durch die magnetische Kopplung zwischen benachbarten Primärspulen bewirkt werden, in einem Bereitschaftszustand verringert. Dies verbessert die Genauigkeit der Präsenzdetektion des Geräts E, das auf den Leistungsversorgungsbereich AR gesetzt ist.

The contactless power supply device of the first embodiment has the advantages described below.

• (1) A plurality of power supply areas AR are defined in the seating surface 3 of the power supply device 1, and the primary coil L1 is arranged in each power supply area AR. Consequently, the primary coil L1 of the power area AR in which the tool E is set is excited and driven regardless of the power supply area AR of the setting surface 3 in which the tool E is set. This allows the power supply device 1 to supply power to the device E regardless of the power supply area AR of the setting area 3 in which the device E is set.
• (2) The primary-side metal detection coil La for performing metal detection is arranged in each power supply area AR. Consequently, the power supply device 1 can detect the metal piece M regardless of the power supply area AR of the setting surface 3 in which the metal piece M is set.
• (3) The power supply device 1 determines whether or not a metal piece M is present with the duty time DU of the ON/OFF signal MP. In other words, the ON/OFF signal MP is generated as a modulation wave. Thus, even if the adjacent primary coils L1 interfere with each other to change the excitation frequency in the power supply apparatus 1 in which a plurality of primary coils 1 are arranged adjacently, the metal detection is performed with high accuracy and is almost imperceptibly affected by changes in the excitation frequency.
• (4) The system control unit 32 determines whether or not a metal piece M is present in each power supply area AR based on the operation time DU calculated by the metal detection circuit section 44 of each basic power supply unit circuit 4 . In this configuration, the system control unit 32 determines whether or not a metal piece M is present simply by comparing the operation time DU from the metal detection circuit section 44 of each basic power supply unit circuit 4 with the reference operation time DUk. As a result, the load on the system control unit 32 can be reduced drastically.
• (5) The information indicating whether or not a metal piece M is present, that is, the ON/OFF signal MP is generated in the device E. FIG. This simplifies the circuit configuration and reduces the processing load for the power supply device 1. Consequently, an inexpensive contactless power supply device can be realized.
• (6) When the modulated wave signal φm is generated, the oscillation signal φt from the oscillation circuit 44a of the metal detection circuit section 44 is used as a carrier signal. This allows elimination of an oscillation circuit that separately generates the carrier signal.
• (7) The modulated wave signal Φm is generated by amplitude modulation. Consequently, the circuit for generating the modulated wave signal φm has a simple structure as compared with when it is generated by other frequency modulations or the like, and the circuit can be constructed at low cost. The signal extraction circuit 44b (detection circuit) which demodulates the modulated wave signal Φm can also be constructed easily and inexpensively.
• (8) The charging voltage Vt of the charging and discharging capacitor C0 of the rectifier circuit 21 is supplied to the multivibrator 22a of the modulation wave signal generation circuit section 22 as the power supply voltage VG. In this structure, the operation time DU of the ON/OFF signal MP of the multivibrator 22a is changed by the power supply voltage VG which changes according to whether a metal piece M is present or not. Consequently, the modulation wave (ON/OFF signal MP) indicative of whether or not a metal piece M is present is generated with the multivibrator 22a having a simple circuit construction.
• (9) The power supply device 1 changes the excitation frequency of the primary coil L1 for supplying power in each basic power supply unit circuit 4 when metal detection is performed. As a result, a plurality of excitation frequencies need not be set in the primary coil L1, and the excitation frequency of the primary coil need not be switched whenever the metal detection is performed. A complex and expensive control circuit is thus unnecessary. This realizes an inexpensive contactless power supply device.
• (10) The power supply device operates the full bridge circuit 43a as a half bridge during a standby state. Consequently, interference caused by the magnetic coupling between adjacent primary coils is reduced in a standby state. This improves the accuracy of the presence detection of the device E set to the power supply area AR.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. In particular, it should be understood that the present invention can be embodied in the following forms.

In the embodiment described above, the signal receiving antenna coil A1 is arranged in each power supply area AR of the power supply apparatus 1, and the signal transmission antenna coil A2 is arranged in the equipment E. However, the antenna coils A1 and A2 can be omitted.

For example, as in 11 As shown, the input terminal of the receiving circuit section 41 and the input terminal of the presence detection circuit 43c are connected to the primary coil L1. In this case, the receiving circuit section 41 can extract the device authentication signal ID and the excitation request signal RQ from the modulated excitation signal received from the primary coil L1.

In this configuration, the presence detection circuit 43c can detect the value of the current flowing to the primary coil L1 as the presence detection voltage Vx and determine whether or not an object is present in the power supply area AR.

If, as in 12 As shown, the antenna coils A1 and A2 are omitted, the output terminal of the transmission circuit section 14 is connected to the secondary coil L2 in the device E. In this case, the transmission circuit section 14 transmits the device authentication signal ID and the stimulation request signal RQ from the data generation circuit section 13 to the primary coil L1 of the power supply device 1 through the secondary coil L2.

Specifically, in the same manner as in the metal detection method, in the modulation circuit section 23, the excitation signal from the primary coil L1 received from the secondary coil L2 is modulated to include bits of the signals ID and RQ based on the device authentication signal ID and the Excitation request signal RQ generated by the data generation circuit section 13. FIG. The device authentication signal ID and the stimulation request signal RQ can be extracted from the modulated stimulation signal received from the primary coil L1.

The primary side metal detection coil La and the signal receiving antenna coil A1 of each power supply area AR and the secondary side metal detection coil Lb and the signal transmission antenna coil A2 of the device can be omitted.

For example , as in 13 As shown, the input terminal of the receiving circuit section 41, the input terminal of the presence detection circuit 43c, and the input terminal of the signal extraction circuit 44b are connected to the primary coil L1. In this case, instead of the primary side metal detection coil La, the primary coil L1 acts as a primary detection coil, and the full bridge circuit 43a acts as an excitation drive circuit. The reception circuit section 41 can accept the device authentication sig Extract nal ID and excitation request signal RQ from the modulated excitation signal received from primary coil L1. The presence detection circuit 43c can detect the value of the current flowing to the primary coil L1 as the presence detection voltage Vx and determine whether or not an object is present in the power supply area AR.

The signal extraction circuit 44b receives the modulated wave signal φm through the primary coil L1. The signal extraction circuit 44b demodulates the envelope waveform signal (demodulation signal DMP), that is, the ON/OFF signal MP enveloping the outside of the modulated wave signal Φm, from the modulated wave signal Φm. The signal extraction circuit 44b (detection circuit) supplies the demodulation signal DMP (ON/OFF signal MP) to the duty calculation circuit 44c.

If, as in 14 As shown, the coils La, Lb, A1 and A2 are omitted, the input terminal of the modulation circuit 20 is connected to the secondary coil L2 in the device E. In this case, the secondary coil L2 acts as a secondary detection coil instead of the secondary-side metal detection coil Lb. The modulation circuit 20 sends the modulated wave signal Φm generated by the amplitude modulation to the primary coil L1 through the secondary coil L2.

Specifically, when the metal detection is performed using the primary coil L1 and the secondary coil L2, the modulation wave signal generation circuit section 22 generates the ON/OFF signal MP based on the power supply voltage supplied from the rectification smoothing circuit section 11 of the power reception circuit 10 and provides provides the ON/OFF signal MP to the modulation circuit section 23.

The modulation circuit section 23 amplitude-modulates the secondary current flowing through the secondary coil L2 with the ON/OFF signal MP (duty time DU of the ON/OFF signal MP) and sends the amplitude-modulated excitation signal L2, that is, the modulated wave signal Φm, from the secondary coil L2 to the primary coil L1. The metal detection circuit section 44 of the basic power supply unit circuit 4 calculates the duty time DU of the ON/OFF signal MP based on the excitation signal (modulated wave signal (Dm)) received from the primary coil L1.

This allows the primary side metal detection coil La and the signal receiving antenna coil A1 of each power supply section and the secondary side metal detection coil Lb and the signal transmission antenna coil A2 of the device to be omitted and allows an inexpensive power supply apparatus 1 to be realized.

In the embodiment described above, the metal detection circuit section 44 of each basic power supply unit circuit 4 calculates the duty time DU of the ON/OFF signal MP and provides the calculated value (DU) to the system controller 32 to reduce the load on the system controller 32. Instead, the metal detection circuit section 44 of each basic power supply unit circuit 4 may provide the demodulation signal DMP of the modulated wave signal Φm to the system control unit 32 . The system control unit 32 can then calculate the duty time DU of the demodulation signal DMP, that is, the ON/OFF signal MP, and determine whether or not a metal piece M is present based on the calculation value (DU) (metal foreign matter detection processing operation).

In the embodiment described above, the center of the primary side metal detection coil La is aligned with the center of the power supply area AR. However, the center of the primary side metal detection coil La may deviate from the center of the power supply area AR.

In the embodiment described above, the oscillating circuit 44a of the metal detecting circuit section 44 is a Colpitts oscillating circuit, but is not limited to a Colpitts oscillating circuit and may be another oscillating circuit such as a Hartley oscillating circuit or the like.

In the embodiment described above, the shape of the primary coil L1 and the secondary coil L2 is tetragonal, but need not be tetragonal. For example, the primary coil L1 and the secondary coil L2 may have a shape other than tetragonal, and may be polygonal, circular, etc. The size of the primary coil L1 and the secondary coil L2 is also not particularly limited. For example, the size of the primary coil L1 may be different relative to the size of the secondary coil L2.

The shapes of the primary-side metal detection coil La and the secondary-side metal detection coil Lb are not limited to the shapes described in the above embodiment, and may be other shapes such as a polygon including a square, or an ellipse or the like other than a circle it's his.

It is obvious that the shapes of the signal receiving antenna coil A1 and the signal transmitting antenna coil A2 are not limited to the shapes described in the above embodiment, and other shapes such as a polygon including a square or an ellipse and the like which is not a circle , could be.

In the embodiment described above, the number of primary coils L1 is the same as the number of primary-side metal detection coils La. In other words, a primary side metal detecting coil La is arranged for a primary coil L1, that is, a primary side metal detecting coil La is arranged in a power supply area AR. However, the number of primary coils L1 need not be the same as the number of primary-side metal detection coils La.

For example, the number of primary-side metal detection coils La can be smaller than the number of primary coils L1. For example, a primary side metal detection coil La may be associated with a plurality of (e.g. four) primary coils L1. In this case, the size of a primary side metal detection coil La is increased so that metal detection can be performed on a plurality of power supply areas AR corresponding to a plurality of primary coils.

In the embodiment described above, the primary coil L1 is formed tetragonally according to the power supply area AR, and the primary coils L1 are arranged in a lattice shape. However, the shape and arrangement of the primary coil L1 are not limited to the embodiment described above. For example, the shape of the primary coil L1 may be a hexagon, and the primary coils L1 may be arranged in a honeycomb shape.

In the embodiment described above, until the device E is set on the setting surface 3, (1) the presence detection processing operation -> (2) the metal foreign body detection processing operation -> (3) the machine type detection processing operation -> (1 ) the presence detection processing operation -> (2) the metal foreign matter detection processing operation -> (3) the machine type detection processing operation, and so on are repeatedly executed.

The repetition may be in the order of (1) the presence detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign body detection processing operation -> (1) the presence detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign matter detection processing operation -> and so on can be performed.

Further, repetition may be performed in the order of (1) the presence detection processing operation -> (2) the metal foreign matter detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign matter detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign matter detection processing operation -> (3) the machine type detection processing operation -> and so on. In this case, when the presence is detected in the first presence detection processing operation, the metal foreign matter detection processing operation and the machine type detection processing operation may be repeated thereafter to stop the excitation of the primary coil L1.

Moreover, repetition can be performed in the order of (1) the presence detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign body detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign matter detection processing operation -> (3) the machine type detection processing operation -> (2) the metal foreign matter detection processing operation, and so on. In the same way, in this case, when the presence is detected in the first presence detection processing operation, the metal foreign object detection processing operation and the machine type detection processing operation can be repeated thereafter to stop the excitation of the primary coil L1.

In the embodiment described above, the common unit portion 30 includes the non-volatile memory 33, and the non-volatile memory 33 stores the reference operation time DUk for determining whether or not a metal piece M is present. Instead, the duty calculation circuit 44c of each power supply unit circuit 4 may store the reference duty time DUk.

In this case, the duty calculation circuit 44c of each power supply unit circuit 4 compares the duty time DU with the reference duty time DUk to determine whether a piece of metal M is present or not. That is, whether or not there is a metal piece M is determined in each basic power supply unit circuit 4 . The operation time calculation circuit 44c notifies the system control unit 32 of the determination result.

The system control unit 32 performs the energization control of the primary coil L1 of each base power supply unit circuit 4 based on the determination result. This reduces the load on the system control unit 32.

Further, the lower reference voltage Vk1 and the upper reference voltage Vk2 for determining whether or not the object (load) is set in the power supply area AR are stored in the non-volatile memory 33 . For example, the presence detection circuit 43c of each power supply unit circuit 4 can store the lower reference voltage Vk1 and the upper reference voltage Vk2.

In this case, the presence detection circuit 43c of each basic power supply unit circuit 4 determines whether or not an object (load) is present in the power supply area AR by comparing the presence detection voltage Vx with the lower reference voltage Vk1 and the upper reference voltage Vk2. That is, the determination as to whether or not an object (load) is present is performed in each power-supply unit circuit 4 . The presence detection circuit 43 notifies the determination result to the system control unit 32 .

The load on the system control unit 32 is thus further reduced/reduced. Further, if the storage of the reference duty time DUk, the lower reference voltage Vk1, and the upper reference voltage Vk2 from the non-volatile memory 33 is omitted, the non-volatile memory 33 becomes unnecessary. This reduces the cost of the contactless power supply device 1.

In the embodiment described above, the operation of the full-bridge circuit 43a is switched from the full-bridge operation to the half-bridge operation when the power-supply device 1 changes to a standby state. For example, instead of the half-bridge operation, all four MOS transistors Qa, Qb, Qc, and Qd of the full-bridge circuit 43a may be turned OFF during a standby state. Obviously, the upper two MOS transistors Qa and Qc can be turned OFF and the lower two MOS transistors Qb and Qd can be turned ON and controlled to couple with other magnetic fluxes.

The four MOS transistors Qa, Qb, Qc and Qd are only required to be controlled such that the current line of the power supply circuit 31 and the ground are not short-circuited by the full bridge circuit 43a during a standby state. The optimal control pattern in this case can be obtained in advance through experiments or the like.

In this structure, the power supply voltage Vdd is blocked to the adjacent primary coil L1 when the primary-side metal detection coil La oscillates to detect a metal piece M during a standby state. Consequently, generation of a regenerative current by the series connection of the primary coil L1 and the resonance capacitor C is suppressed. That is, the magnetic coupling with the adjacent primary side metal detection coil La oscillating to detect a metal piece M is suppressed by blocking the power supply voltage Vdd to the primary coil L1.

As a result, the oscillation energy of the primary-side metal detection coil La is not weakened by the magnetic coupling. Further, no situation arises where the astable multivibrator 22a of the modulation wave signal generating section 22 in the modulation circuit 20 of the device E cannot be driven. Consequently, the detection accuracy of the metal piece M does not decrease.

The full bridge circuit 43a can, as in 15 shown, be constructed. As in 15 As shown, a reverse current prevention diode Dx is connected with a node N1 between the drains of the two upper MPS transistors Qa and Qc. An anode terminal of the reverse current preventing diode Dx is connected to the power line of the power supply circuit 31 . A cathode terminal of the reverse current preventing diode Dx is connected to the node N1. Therefore, the DC voltage Vdd is applied to the full bridge circuit 43a via the reverse current preventing diode Dx.

Free wheeling diodes Da, Db, Dc and Dd are connected in parallel to the MOS transistors Qa, Qb, Qc and Qd, respectively. Even if the diodes Da, Db, Dc, and Dd are omitted, substantially equivalent MOS transistors Qa, Qb, Qc, and Qd can be obtained as long as they have body diodes.

In the full bridge circuit 43a constructed as described above, the upper two MOS transistors Qa and Qc are turned OFF, and the lower two MOS transistors Qb and Qd are turned ON. This blocks the power supply voltage Vdd to the primary coil L1 to suppress the magnetic coupling with the adjacent primary-side metal detection coil La oscillating to detect the metal piece M .

Also, the reverse current preventing diode Dx is connected between the full bridge circuit 43a and the power line of the power supply circuit 31 . Consequently, the flow of current induced on the primary coil L1 by the magnetic coupling with the primary-side metal detection coil La is prevented to the power line of the power supply circuit 31 by the reverse current preventing diode Dx even if the impedance decreases and the potential in the power line of the power supply circuit 31 from the for one reason or another. That is, the oscillation energy of the primary-side metal detection coil La can be prevented from flowing as a current through the primary coil L<b>1 to the power line of the power supply circuit 31 .

As a result, the oscillation energy of the primary-side metal detection coil La is not weakened, and the detection accuracy of the metal piece M is not lowered.

In the embodiment described above, the determination as to whether or not a metal piece M is present is performed by comparing the duty time DU calculated by the duty time calculation circuit 44c and the reference duty time DUk.

However, the ON time t1 (duty time DU) of the ON/OFF signal MP may differ significantly between when no metal piece M is unloaded and when a metal piece M is loaded. For example, the ON time t1 of the ON/OFF signal MP can be very short when no metal piece M is set, and the ON time t1 of the ON/OFF signal MP can be very long when a metal piece is set.

In this case, instead of determining whether or not a metal piece M is present based on the duty time DU of the demodulation signal DMP, the determination of whether or not a metal piece M is present may be performed based on a determination result as to whether the ON (high level -) period of the demodulation signal DMP is long or the OFF (low level) period is long. In the case of such determination control, the DU does not need to be calculated. Consequently, the determination of whether or not there is a metal piece M can be determined by a simple method.

In the embodiment described above, the modulation wave signal generation circuit section 22 of the modulation circuit 20 is constructed by an astable multivibrator 22a, but may be constructed by a comparator. In this case, the comparator can compare the power supply voltage VG from the rectifier circuit 21 and the predefined voltage to generate the ON/OFF signal MP.

In the embodiment described above, the matching circuit MC of the modulation circuit 20 is constructed by the resonance capacitor Cx, but may have other circuit constructions. The rectifying circuit 21 of the modulation circuit 20 is constructed by the half-wave rectifying circuit, but may be constructed by other rectifying circuits. Further, the modulation circuit section 23 of the modulation circuit 20 is constructed by the transistor Q3 and the diode D1, but may have other circuit constructions.

In the embodiment described above, 24 power supply areas AR are formed in the setting surface 3, but the number of power supply areas AR is not limited to a specific number. In other words, the present invention is applicable to the power supply device 1 having one or more power supply areas AR.

Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications could be made therein without departing from the spirit and scope of the invention.

Claims (8)

Contactless power supply device (1) using an electromagnetic induction effect to supply power to a power receiving device (10) arranged in an electric device, said contactless power supply device (1) comprising: a primary coil (L1) arranged in each of one or more power supply areas (AR) defined in a setting surface on which the electrical equipment is set, the primary coil (L1) supplying secondary power to a secondary by electromagnetic induction coil (L2) of the power receiving device (10) in the corresponding power supply area (AR); a basic power supply unit circuit (4) arranged in each of the power supply areas (AR), the basic power supply unit circuit (4) exciting the primary coil (L1) in the corresponding power supply area (AR) to supply secondary power by electromagnetic induction, and the basic power supply unit circuit (4 ) sends an oscillation signal from the corresponding power supply area (AR) to the power receiving device (10), receives a modulated wave signal from the power receiving device (10), which outputs a modulation wave (MP) from a multivibrator (22a) according to a magnetic flux change, detected from the oscillation signal, and detecting the modulated wave signal to demodulate the modulation wave (MP); and a system control unit that determines whether or not a metal foreign matter is present in the power supply area (AR) corresponding to the basic power supply unit circuit (4) based on the modulation wave (MP) demodulated by the basic power supply unit circuit (4); wherein: the basic power supply unit circuit (4) comprises: an oscillation circuit (44a) which transmits the oscillation signal to the power receiving device (10), a primary detection coil which receives the modulated wave signal, a detection circuit which detects the modulated wave signal received from the primary detection coil and demodulates the modulation wave (MP), and an operation time calculation circuit that calculates an operation time of the modulation wave (MP) demodulated by the detection circuit; the multivibrator (22a) has a first transistor (Q1) and a second transistor (Q2) which are driven based on a power supply voltage (VG) of the multivibrator (22a), and the modulation wave (MP) from a collector terminal of the first transistor (Q1 ) outputs; the multivibrator (22a) is configured such that a change in the power supply voltage (VG) changes an initial value of a potential between the base and the emitter of the first transistor (Q1) when the first transistor (Q1) is switched from ON to OFF, and a rate of change between the base and the emitter of the second transistor (Q2) changes when the second transistor (Q2) is turned off; a time constant of the multivibrator (22) is set so that an operation time (DU) of the modulation wave (MP) increases as the power supply voltage (VG) of the multivibrator (22a) decreases when a metal piece (M) on the base power supply unit circuit (4) associated power supply area (AR), wherein the system control unit determines whether or not a metallic foreign matter is present in the power supply area (AR) corresponding to the basic power supply unit circuit (4) based on the operation time calculated by the operation time calculation circuit, and supplying power to the corresponding power supply area (AR) stops when it is determined that a metallic foreign matter is present. Contactless power supply device (1) according to claim 1 , wherein: the power receiving device (10) having a secondary detection coil receives a carrier signal from the basic power supply unit circuit (4), and the multivibrator (22a) of the power receiving device (10) receives the modulation wave (MP) as an ON/OFF signal with an operation time varying changes according to a magnetic flux change at the secondary detection coil; the modulated wave signal is generated by amplitude-modulating an amplitude of the carrier signal with the ON/OFF signal; the detection circuit envelope-detects the modulated wave signal to demodulate the ON/OFF signal; and the operation time calculation circuit detects an operation time of the ON/OFF signal demodulated by the detection circuit. Contactless power supply device (1) according to claim 2 , wherein the carrier signal is the oscillation signal sent from the oscillation circuit (44a) to the power receiving device (10). Contactless power supply device (1) using an electromagnetic induction effect to supply power to a power receiving device (10) arranged in an electric device, said contactless power supply device (1) comprising: a primary coil (L1) arranged in each of one or more power supply areas (AR) defined in a setting surface on which the electrical equipment is set, the primary coil (L1) supplying secondary power by electromagnetic induction to a secondary coil (L2) of the power receiving device (10) in the corresponding power supply area (AR) delivers; a basic power supply unit circuit (4) arranged in each of the power supply areas (AR), the basic power supply unit circuit (4) excites the primary coil (L1) in the corresponding power supply area (AR) to supply secondary power by electromagnetic induction, and the basic power supply unit circuit (4) sends an oscillation signal from the corresponding power supply area (AR) to the power receiving device (10). receives a modulated wave signal from the power receiving device (10), which detects a modulation wave (MP) output from a multivibrator (22a) according to a magnetic flux change from the oscillation signal, and detects the modulated wave signal to demodulate the modulation wave (MP). ; and a system control unit that determines whether or not a metal foreign matter is present in the power supply area (AR) corresponding to the basic power supply unit circuit (4) based on the modulation wave (MP) demodulated by the basic power supply unit circuit (4); wherein: the basic power supply unit circuit (4) comprises: an oscillation circuit (44a) which transmits the oscillation signal to the power receiving device (10), a primary detection coil which receives the modulated wave signal, and a detection circuit which detects the modulated wave signal received from the primary detection coil and demodulates the modulation wave (MP); the multivibrator (22a) has a first transistor (Q1) and a second transistor (Q2) which are driven based on a power supply voltage (VG) of the multivibrator (22a), and the modulation wave (MP) from a collector terminal of the first transistor (Q1 ) outputs; the multivibrator (22a) is configured such that a change in the power supply voltage (VG) changes an initial value of a potential between the base and the emitter of the first transistor (Q1) when the first transistor (Q1) is switched from ON to OFF, and a rate of change between the base and the emitter of the second transistor (Q2) changes when the second transistor (Q2) is turned off; a time constant of the multivibrator (22a) is set so that an operation time (DU) of the modulation wave (MP) increases as a power supply voltage (VG) of the multivibrator (22a) decreases when a metal piece (M) on the base power supply unit circuit (4) associated power supply area (AR) is present, the system control unit receives the modulation wave (MP) demodulated by the detection circuit, calculates the operation time of the modulated wave, based on the calculated operation time, determines whether there is a metal foreign matter in the power supply area (AR) associated with the basic power supply unit circuit ( 4) is present or not, and the supply of power to the corresponding power supply area (AR) stops when it is determined that a metal foreign matter is present. Contactless power supply device (1) according to one of Claims 1 or 4 wherein: the oscillation circuit (44a) is an excitation driving circuit which excites the primary coil (L1); and the primary detection coil is the primary coil (L1). Contactless power supply device (1) according to one of Claims 1 or 4 wherein the basic power supply unit circuit (4) transmits the oscillation signal with a primary detection coil arranged independently of the primary coil (L1) used to supply the secondary power to the secondary coil (L2). Contactless power supply device (1) according to claim 6 , wherein the primary detection coil is shared by adjacent ones of the power supply areas (AR). Contactless power supply device (1) according to one of Claims 1 or 4 , wherein the base power supply unit circuit (4) sends the oscillation signal with the primary coil (L1) used to supply the secondary power to the secondary coil (L2).

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