DESCRIPTION

CONTROL DEVICE AND POWER TRANSMITTING DEVICE [CROSS-REFERENCE TO RELATED APPLICATIONS]

This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2013-188577, filed September, 11, 2013; the entire contents of which are incorporated herein by reference.

[FIELD]

[0001]

Embodiments described herein relate generally to a control device and a power transmitting device.

[BACKGROUND]

[0002]

There has conventionally been known a wireless power transmitting device that uses a magnetic field to transmit power to a power receiving device in a non-contact manner. In the wireless power transmitting device, leakage electromagnetic fields may affect other electronic apparatuses. Accordingly, the intensities of electromagnetic fields (hereinafter referred to as intensities of leakage electromagnetic fields) leaking to the circumference of the wireless power transmitting device may need to be reduced though the necessity of reduction depends on radio frequencies.

[Citation List]

[Patent Literature]

[0003]

[Patent Literature 1]

International publication No. WO 2009/122355

[Brief Description of the Drawings]

[0004]

[FIG. 1] Fig. 1 is a schematic block diagram illustrating the configuration of a wireless power transmitting system 1 in a first embodiment.

[FIG. 2] FIG. 2 is a schematic block diagram illustrating the configuration of the power transmitting device 10 in the first embodiment.

[FIG. 3] FIG. 3 is a schematic block diagram illustrating one example of the configuration of the power receiving device 20 in the first embodiment.

[FIG. 4] FIG. 4 is an explanatory view illustrating a magnetic field quantitatively decreased by execution of phase control in the first embodiment.

[FIG. 5] FIG. 5 is a flow chart illustrating an example of the flow of processing that sets the current phase of power transmitting coils in the first embodiment.

[FIG. 6] FIG. 6 is a first placement example of the power transmitting coils and the power receivers.

[FIG. 7] FIG. 7 is a second placement example of power transmitting coils and power receivers.

[FIG. 8] FIG. 8 illustrates a third placement example of power transmitting coils and power receivers.

[FIG. 9] FIG. 9 illustrates the configuration example of shapes of power transmitting coils.

[FIG. 10] FIG. 10 illustrates a modification of the power transmitting coils.

[FIG. 11] FIG. 11 is a schematic block diagram illustrating the configuration of a power transmitting device 12 in the second embodiment.

[FIG. 12] FIG. 12 is a schematic block diagram illustrating the configuration of a power transmitting device 13 in the third embodiment.

[FIG. 13] FIG. 13 is a schematic block diagram illustrating the configuration of the controller 112c in the third embodiment. [FIG. 14] FIG. 14 illustrates a waveform example of two control signals supplied by the current phase controller 905 to two power transmitting circuits.

[FIG. 15] FIG. 15 is a flow chart illustrating an example of the flow of processing that sets the current phase of the power transmitting coils in the modification of the third embodiment. [FIG. 16] FIG. 16 is an explanatory view of the placement of the power transmitting coils according to the fourth embodiment. [FIG. 17] FIG. 17 is a first modification of the placement of the power transmitting coils.

[FIG. 18] FIG. 18 illustrates a second modification of the placement of the power transmitting coils according to the second modification of the fourth embodiment.

[FIG. 19] FIG. 19 is a schematic block diagram illustrating the configuration of the power transmitter 1501 in the fifth embodiment.

[FIG. 20] FIG. 20 is a schematic block diagram illustrating the first connection state of the power transmitter 1501 in the fifth embodiment.

[FIG. 21] FIG. 21 is a schematic block diagram illustrating the second connection state of the power transmitter 1501 in the fifth embodiment.

[FIG. 22] FIG. 22 is an explanatory view of the placement of the power transmitting coils 1601-1 to 1601-4 according to the sixth embodiment.

[Disclosure of the Invention]

[0005]

According to one embodiment, a control device controls at least one or more power transmitting circuits that transmit electric power in a non-contact manner by causing a plurality of power transmitting coils to generate electromagnetic fields. The control device ^" includes a controller that controls a phase of each current, for at least two out of the plurality of power transmitting coils, to be outputted by the power transmitting circuits to these power transmitting coils, based on a complex current passing through these power transmitting coils and a number of turns of these power transmitting coils.

Hereinbelow, embodiments of the present invention will be described in detail with reference to the drawings.

< First Embodiment

FIG. 1 is a schematic block diagram illustrating the configuration of a wireless power transmitting system 1 in a first embodiment. The wireless power transmitting system 1 includes a power transmitting device 10 and a power receiving device 20.

The power transmitting device 10 generates an electromagnetic field and transmits electric power to the power receiving device 20 in a non-contact manner. Transmission is performed by, for example, an electromagnetic induction method or a magnetic field resonance (magnetic field vibration) method. The electromagnetic induction method is adapted to pass current to one of two coils to convert energy into a magnetic field and to cause the other coil to generate electromotive force. The electromagnetic induction method is also called a magnetic field resonance method, in which a resonance frequency of coils is used as a transmission frequency to perform highly efficient transmission. The resonance frequency is adjusted by combining the coils and capacitor.

[0006]

The power receiving device 20 receives the electric power wirelessly transmitted by the power transmitting device 10. Here, the power transmitting device 10 includes power transmitters 101-1, 101-2, 101-M ("M" being an integer of 2 or larger). The power receiving device 20 includes power receivers 201-1, 201-2, 201-M ("M" being an integer of 2 or larger).

[0007] ^'

The power transmitters and the power receivers correspond to each other in one to one relation. Each of the power transmitters 101-i (i being an integer from 1 to M) generates a magnetic field and transmits electric power to each of the power receivers 201-i in a non-contact manner. For example, the power transmitter 101-1 generates a magnetic field and transmits electric power to the power receiver 201-1 in a non-contact manner. For example, the power transmitter 101-2 generates a magnetic field and transmits electric power to the power receiver 201-2 in a non-contact manner. For example, the power transmitter 101-M generates a magnetic field and transmits electric power to the power receiver 201-Ml in a non-contact manner.

[0008]

FIG. 2 is a schematic block diagram illustrating the configuration of the power transmitting device 10 in the first embodiment. The power transmitting device 10 includes: M transmitters 101-i including the power transmitters 101-1, 101-2, 101-M; and a control device 110 electrically connected to each of these M power transmitters 101-i. Hereinafter, the power transmitter 101-1, 101-2, 101-M are also generically referred to as a power transmitter/transmitters 101.

[0009]

The control device 110 in the present embodiment controls the phase of each current passing through power transmitting coils 103-i included in the power transmitters 101-i so that the entire power transmitting device 10 can reduce a magnetic field generated at an observation point used for observing a leakage magnetic field. A concrete description will be provided below.

[0010]

A description is first given of each component member.

Each of the power transmitters 101-i includes a power transmitting coil 103-i and a power transmitting circuit 104-i which is electrically connected to both ends of the power transmitting coil 103-i and is electrically connected to a controller 112 of the later-described control device 110.

[0011]

The control device 110 includes a communication aid 111 and a controller 112 which is electrically connected to the communication aid 111 and is electrically connected to each of the power transmitting circuits 104-i. Here, the controller 112 is constituted of an electronic circuit in one example.

[0012]

The number of turns of the power transmitting coils

103-1, 103-2, 103-M may be identical or may be different. Here, the power transmitting coil 103-i may be constituted with a lead wire, and may be constituted with a Litz wire. The power transmitting coil 103-i may be shaped into an arbitrary shape, such as a rectangular shape, a circular shape, and a diamond shape. Further, a ferrite may be placed in the vicinity of the power transmitting coil 103-i in order to increase an inductance value of the coil. The power transmitting coil 103-i may be made of an arbitrary coil used for wireless power transmission.

[0013]

The power transmitting circuit 104-i is configured to supply a high frequency current to the power transmitting coil 103-i by applying voltage to both the ends of the power transmitting coil 103-i. Accordingly, the power transmitting circuit 104-i transmits electric power to the power receiving device 201-i in a non-contact manner by causing the power transmitting coil 103-i to generate a magnetic field.

[0014]

The frequency of currents outputted from all the power transmitting circuits 104-i is identical. The amplitude of the current outputted from the power transmitting circuit 104-i and passed to the power transmitting coil 103-i is determined in accordance with the state of a power receiver that is an electric power transmission destination. The phase (hereinafter also referred to as current phase) of the current to be outputted from the power transmitting circuit 104-i and passed to the power transmitting coil 103-i is controlled to be a desired value by the controller 112 of the control device 110. The power transmitting circuit is a constant voltage source. The power transmitting circuit may be configured to supply to the power transmitting coil a radio frequency current determined by a load.

[0015]

For example, the power transmitting circuit 104-i detects the value of the current passing through the power transmitting coil 103-i, and outputs a current signal Sl-i indicating the value of the current to the controller 112 of the control device 110.

[0016]

For example, the power transmitting circuit 104-i acquires a control signal S-i outputted from the controller 112 of the control device 110, and controls voltage applied to both the ends of the power transmitting coil 103-i so that a current having a phase corresponding to the control signal S-i passes to the current power transmitting coil 103-i. The control signal herein refers to a signal which controls the phase of the current to be outputted by the power transmitting circuit 104-i.

[0017]

A description is now given of each part of the control device 110.

The communication aid 111 can communication with each of the power receivers 201-i by radio transmission. Radio transmission is implemented by, for example, a wireless LAN.

[0018]

A description is now given of concrete processing in the controller 112.

The controller 112 controls the phase of each current, for at least two out of the plurality of power transmitting coils, to be outputted by the power transmitting circuits 104-i to these power transmitting coils 103-i, based on a complex current passing through these plurality of power transmitting coils 103-i and the number of turns of these power transmitting coils 103-i. For example, the controller 112 that, for at least two out of the plurality of power transmitting coils, controls switching timings of inverter circuits in the power transmitting circuits 104-i which output currents to these power transmitting coils 103-i, based on a complex current passing through these plurality of power transmitting coils 103-i and the number of turns of these power transmitting coils 103-i. Specifically, the controller 112 receives a current signal Sl-i outputted from each of the power transmitting circuits 104-i for example. For example, the controller 112 retains the number of turns of each of the respective transmitting coils 103-i in advance. [0019]

For example, the controller 112 calculates, for each of the power transmitters 101-i, a current-turns product which is a product of the complex current passing through the power transmitting coil 103-i indicated by the current signal Sl-i and the number of turns of the power transmitting coil 103-i retained in advance. For example, the controller 112 controls the phase of each current to be outputted by the power transmitting circuits 104-i to the plurality of power transmitting coils 103-i so as to suppress the magnitude of a resultant value of the plurality of calculated current-turns products. The details of the determination processing will be described later. For example, the controller 112 outputs a control signal S-i to the power transmitting circuit 104-i so as to control the phase of the current to be outputted by the power transmitting coil 103-i to be the determined phase of the current.

[0020]

Since the current amplitude is determined in accordance with the state of a power receiver, the controller 112 does not need to control the current amplitude.

[0021]

The power transmitting device 10 is configured as described above. Hereinbelow, a description is given of the reason why a leakage magnetic field generated from the power transmitting device 10 is reduced in the power transmitting device 10 of the present embodiment.

[0022]

The amplitude of the magnetic field generated from the power transmitting coil 103-i is proportional to a product of the current amplitude passing through the power transmitting coil 103-i and the number of turns. Here, a current which passes to the i-th power transmitting coil 103-i is defined as "Ii". The current Ii is a complex current. The number of turns of the i-th power transmitting coil 103-i is defined as "Ni".

[0023]

The phase of a magnetic field generated from the power transmitting coil 103-i corresponds to the phase of the current passing through the power transmitting coil 103-i. This implies that when the phase of the current changes by 10 degrees, the phase of the magnetic field similarly changes by 10 degrees.

[0024]

As a result, the amplitude of a magnetic field from the i-th power transmitting coil 103-i is proportional to the amplitude of a current-turns product IiNi which is a product of the current ΙΊ and the number of turns Ni. The phase of the magnetic field from the i-th power transmitting coil 103-i corresponds to the phase of the current-turns product IiNi. When M power transmitting coils 103-i are present, and the current-turns product is expressed as a vector on a complex plane, the amplitude of a combined magnetic field from these M power transmitting coils 103-i is proportional to the amplitude of a combined vector obtained by combining all of these M vectors.

[0025]

Thus, the magnetic field generated by the entire power transmitting device 10 at an observation point used for observing a leakage magnetic field depends on the amplitude and the phase of each current passing through each of the power transmitting coils 103-i and the number of turns of each of the power transmitting coils 103-i.

[0026]

The controller 112 in the present embodiment calculates the current-turns product for all the power transmitting coils in one example. For example, the controller 112 controls the phase of the current Ii (i = l to M) to be outputted by each of the power transmitting circuits 104-i to each of the power transmitting coils 103-i, so that a magnitude A of a resultant value of the plurality of current-turns products becomes equal to or below a preset threshold value. The resultant value herein refers to a combined vector obtained by combining the respective vectors when the plurality of current-turns products are expressed as a vector on a complex plane. The magnitude A of the resultant value represents the amplitude of the combined vector.

[0027]

A description is now given of the details of the combining processing. The magnitude A of the resultant value is calculated in accordance with Expression (1).

[0028]

[Expression 1]

A [0029]

Here, "Ii" represents a complex current after the current phase is controlled. In the present embodiment, the controller 112 determines the current phase so that the magnitude A of a resultant value calculated as described above becomes equal to or below a preset threshold value in one example. The current phase may be determined not as an absolute value but as a relative phase.

[0030]

For example, when it is desired to make the intensity of a combined magnetic field obtained from a plurality of power transmitting coils equal to or below the preset magnetic field intensity, the preset threshold value represents an amplitude value of a current passing through a coil of one turn that generates the preset magnetic field intensity. By setting the threshold value in this manner, the controller 112 can suppress the intensity of a combined magnetic field obtained from the plurality of power transmitting coils to be equal to or below a desired value.

[0031]

In one concrete example, the controller 112 determines the current phase as described follows. It is presumed that each current-turns product is equal to or below a threshold value. For example, the controller 112 calculates, for each of a plurality of power transmitting coils, a current-turns product by multiplying a complex current by the number of turns of the power transmitting coil. For example, the controller 112 first allocates a predetermined angle (for example, 0 degree) to a current phase corresponding to a largest current-turns product among the plurality of calculated current-turns products. Next, the controller 112 allocates a phase 180 degrees different from the predetermined angle to a current phase corresponding a second largest current-turns product among the plurality of calculated current-turns products. Subsequently, in descending order of current-turns product, the controller 112 allocates, a phase 180 degrees different from a phase of a resultant vector value of current-turns products regarding power transmitting coils whose current phases have been already allocated, to each current phase. Accordingly, the controller 112 can make the magnitude of each resultant value of the current-turns products equal to or below a threshold value.

[0032]

When the plurality of power transmitting coils 103-i are placed apart from each other, a distance to a specific observation point is different for every power transmitting coil 103-i. The phase of a magnetic field at the specific observation point is also changed by the distance from each of the respective power transmitting coils 103-i. In the present embodiment, a placement interval between the power transmitting coils 103-i is equal to or below one out of a specified wavelength value (1/100 in one example) for example. As a result, the phase change by the difference in distance can be disregarded. The wavelength herein refers to a wavelength "λ" corresponding to a frequency "f" of the current passing through the power transmitting coil 103-i (=c/f, provided "c" is a velocity of light).

[0033]

Even when the placement interval is not 1/100 wavelength but 1/50 wavelength and/or 1/20 wavelength, an effect of suppressing the magnetic field can still be achieved since a change in phase due to the difference in distance is small. [0034]

FIG. 3 is a schematic block diagram illustrating one example of the configuration of the power receiving device 20 in the first embodiment. The power receiving device 20 includes M power receivers 201-i including power receivers 201-1, 201-2, 201-M.

[0035]

Each power receiver 201-i includes a power receiving coil 203-i and a power receiving circuit 204-i electrically connected to both ends of the power receiving coil 203-i.

Each power receiver 201-i further includes a communication aid 205-i electrically connected to the power receiving circuit 204-i and a secondary battery 206-1 electrically connected to the power receiving circuit 204-i.

[0036]

Each communication aid 205-i can wirelessly communicate with the communication aid 205 of the power transmitting device 10.

[0037]

Each power receiving circuit 204-i supplies a current generated in the power receiving coil 203-i to the secondary battery 206-i. Accordingly, the secondary battery 206-i is charged with the supplied current.

[0038]

FIG. 4 is an explanatory view illustrating a magnetic field quantitatively decreased by execution of phase control in the first embodiment. In this example, the number of the power transmitting coils 103-i is set to 3.

[0039]

In a first power transmitting coil 103-1, the number of turns is 1 and the current amplitude is 2A, so that a current-turns product is equal to 2A.

In a second power transmitting coil 103-2, the number of turns is 2 and the current amplitude is 1A, so that the current-turns product is equal to 2A.

In a third power transmitting coil 103-3, the number of turns and 1 and the current amplitude is 1A, so that the current-turns product is set to 1A.

When no control is performed on the current phase, a phase relation is unknown when magnetic fields are combined. If the magnetic fields should be combined in the same phase, the magnetic field intensity corresponding to a current-turns product of 5A is obtained.

[0040]

An example in which the threshold value is set to 1A will be described below. As illustrated in FIG. 4, the controller 112 controls so that the current phase of the first power transmitting coil 103-1 is 0 degree, the current phase of the second power transmitting coil 103-2 is 180 degrees, and the current phase of the third power transmitting coil 103-3 is 0 degree. In this case, the amplitude after the current-turns product vectors are combined becomes 1A, which is equal to or below the threshold value. Therefore, the magnetic field intensity can be suppressed to be equal to or below the desired value.

[0041]

FIG. 5 is a flow chart illustrating an example of the flow of processing that sets the current phase of power transmitting coils in the first embodiment. As the number of power receivers increases or decreases, each current passing through the power transmitting coil changes. Accordingly, in the flow chart, the controller 112 resets the current phase of each power transmitting coil 103-i in accordance with increase or decrease in the number of the power receivers, and controls each power transmitting circuit 104-i to have a set current phase. Accordingly, the controller 112 can appropriately set phase control in accordance with increase or decrease in the number of the power receivers.

[0042]

(Step S101) First, the controller 112 determines whether or not the number of the power receivers is increased. Since the initial number of power receivers is 0, the controller 112 determines that the number of the power receivers is increased when one power receiver is placed for example. If it is determined that the number of the power receivers is increased (YES), the controller 112 proceeds to step S102. If it is determined that the number of the power receivers is not increased (NO), the controller 112 is kept in standby. The controller 112 retains the number of the power receivers.

[0043]

In this case, the controller 112 may use an arbitrary method for determining the increase. For example, a user may manually set a power transmitting coil 103-i that corresponds to an additionally placed power receiver 201-i. Specifically, the power transmitting device 10 further includes an input unit for example. When the input unit receives a user input that specifies a power transmitting coil 103-i corresponding to an additionally placed power receiver 201-i, input information indicative of the received input may be outputted to the controller 112. When the controller 112 receives the input information, the controller 112 may determine that the number of the power receivers is increased.

[0044]

Or the controller 112 may determine increase in the number of power receivers with use of the communication aid 111.

Specifically, in the case, for example, where a power receiver 201-i is newly placed, and a current passing through a power receiving coil 203-i included in the power receiver 201-i is detected, a communication aid 205-i included in the power receiver 201-i may wirelessly notifies the addition of the power receiver 201-i to the power transmitting device 10. In that case, the controller 112 of the power receiver 201-i may determine that the number of the power receivers is increased when the communication aid 111 receives the notification regarding the addition of the power receiver 201-i.

[0045]

Or the controller 112 may intermittently operate the power transmitting circuits 104-i, and may determine whether or not the number of the power receivers is increased based on a difference in current passing through the power transmitting coils 103-i or in power consumption of the power transmitting circuits 104-i between the case where an extra power receiver is present and the case where no extra power receiver is present.

When a certain power receiver 201 - i is present, a current passes to a power transmitting coil 104-i which transmits electric power to the power receiver 201-i in a non-contact manner. When the power receiver 201-i is not present, a slight current passes to the power transmitting coil 104-i which transmits electric power to the power receiver 201-i in a non-contact manner.

[0046]

Accordingly, the controller 112 may determine that the number of the power receivers is increased in the case, for example, where a current smaller than a predetermined detection threshold value passes to the power transmitting coil 103-i when the power transmitting circuit 104-i is operated at certain time t, and a current equal to or above the predetermined detection threshold value then passes to the power transmitting coil 103-i when the power transmitting circuit 104-i is operated at time t+a ("a" being a positive value).

[0047]

If the device is so designed that a smaller current passes to the power transmitting coil 103-i when no power receiver is present, the leakage electromagnetic field in the case of no power receiver may be decreased.

[0048]

(Step S102) Next, the controller 112 suspends power transition in all the power transmitters 101-i. However, when the number of the power receivers is increased from 0 to 1 in step S101, this processing is not performed. In the case where the processing returns to step S102 due to the result of determination in later-described step SI 12, power transition is suspended in all the power transmitters 101-i. [0049]

(Step S103) Next, the controller 112 set a variable "k" for counting the number of the power receivers to k= l .

[0050]

(Step S104) Next, the controller 112 makes a k-th power transmitter 101-k perform power transmission only to a k-th power receiver 201-k in a first relative phase. In this stage, the relative phase of a power transmitting coil 103-k is not yet set. Here, since electric power is transmitted only to the power receiver 201-k, a leakage magnetic field is generated only from one power transmitting coil 103-k. Accordingly, the leakage electromagnetic field intensity at the observation point is equal to or below a predetermined restriction value. The first relative phase may be an arbitrary value. In this case, since simultaneous power transmission by a plurality of power transmitting coils 103-i is not performed, an arbitrary first relative phase may be used.

[0051]

(Step S105) Next, the controller 112 sets a current amplitude of the power transmitting coil 103-k corresponding to the k-th power receiver 201-k. Since the current amplitude changes depending on the state of the power receiver, it is necessary to set the current amplitude based on the state of the power receiver. The power transmitting circuit 104-k may directly measures the amplitude of the current passing through the power transmitting coil 103-k, and the controller 112 may set the measured amplitude as the current amplitude.

[0052]

Or a correspondence relation between power consumption of the power transmitter 101-k and the current amplitude of the power transmitting coil 103-k is measured in advance, and the controller 112 may retain the correspondence relation between power consumption of the power transmitter 101-k and the current amplitude of the power transmitting coil 103-k in advance for example. The correspondence relation may be provided in the form of an expression or in the form of a table. Then, the controller 112 may acquire the power consumption of the power transmitter 101-k and acquire the current amplitude by applying the acquired power consumption of the power transmitter 101-k to the correspondence relation. The controller 112 may set the acquired current amplitude as the current amplitude of the power transmitting coil 103-k. In this case, since the power consumption of a direct current may be measured, a measurement cost can be decreased.

[0053]

Or a correspondence relation between reception power of the a k-th power reciever 201-k and the current amplitude of the power transmitting coil 101-k is measured in advance, and the controller 112 may retain the correspondence relation between reception power of the k-th power reciever 201-k and the current amplitude of the power transmitting coil 101k for example. The correspondence relation may be provided in the form of an expression or in the form of a table. The communication aid 111 may receive the reception power of the k-th power receiver 201-k from the power receiver 201-k by wireless communication. The controller 112 may acquire the current amplitude by applying the reception power of the power receiver 201-k that is received by the communication aid 111 to the correspondence relation for example. The controller 112 may set the acquired current amplitude as the current amplitude of the power transmitting coil 103-k.

[0054]

Setting methods other than the method described above may be used as long as the controllers 112 can set the amplitude of the current passing through the power transmitting coils 103-k.

[0055]

(Step S106) Next, the controller 112 determines whether or not the value of a current variable "k" is equal to the retained number of the power receivers. If the value of the variable "k" is not equal to the number of the power receivers (NO), the controller 112 proceeds to step S107. As a consequence, the controller 112 increments the value of the variable "k" by 1 in step S107, and repeats the processing of steps S104 and S105. If the number of the variables k is equal to the number of the power receivers (YES), the controller 112 proceeds to step S108.

[0056]

(Step S107) When the value of the variable "k" is not equal to the number of the power receivers in step S106, the controller 112 increments the value of the variable "k" by 1, and returns to step S104.

[0057]

(Step S108) Next, the controller 112 uses the set current amplitude values of k power transmitting coils 103-i to set the current phases of k power transmitting coils 103-i. Since the method for setting the current phase is described before, a description thereof is omitted. The value of the variable "k" is equal to the number of the power receivers as set in step S106.

[0058]

(Step S109) Next, the controller 112 controls the current phases of k power transmitting coils 103-i to be the relative phases set in step S108, and controls k power transmitting circuits 104-i so that electric power is simultaneously transmitted to k power receivers 201-i. As a result, the controller 112 can reduce a combined leakage electromagnetic field collectively generated by all of k power transmitting coils 103-i.

[0059]

(Step S110) Next, the controller 112 determines whether or not the number of the power receivers is increased or decreased. If there is no change in the number of the power receivers (NO), the controller 112 proceeds to step Sill. If there is a change in the number of the power receivers (YES), the controller 112 proceeds to step S112.

[0060]

(Step Si ll) If there is no change in the number of the power receivers in step S110, the controller 112 continues power transmission to k power receivers 201-i.

[0061]

(Step S112) If there is a change in the number of the power receivers in step SI 10, the controller 112 determines whether or not the number of the power receivers is equal to 0. If the number of the power receivers is equal to 0 (YES), the controller 112 ends power transmission. The controller 112 then returns to the processing of step S101 to restart processing. If the number of the power receivers is not equal to 0 (NO), the controller 112 returns to step S102. The controller 112 then repeats again the aforementioned steps starting from step S103.

[0062]

According to the processing in this flow chart described above, even when the number of the power receivers is increased or decreased, the controller 112 can appropriately control the current phase of each of the power transmitting coils 103-i.

[0063]

FIG. 6 is a first placement example of the power transmitting coils and the power receivers. FIG. 6 illustrates a case where the number of power transmitters "M" and the number of the power receivers "M" are equal to 4. In the configuration example of a power transmitting device 501, power transmitting coils 502A, 502B, 502C, and 502D are all identical and are placed so as to be aligned in a direction parallel to an x-axis while a power transmitting coil surface that is a plane including the power transmitting coils is parallel to an xy plane. The power receiver side is also configured to include coils, though illustration thereof is omitted.

[0064]

When the power transmitting coils are formed into an identical shape, leakage electromagnetic fields from the respective power transmitting coils are generated in an identical vector direction on the basis of the individual power transmitting coils. Further, since each power transmitting coil surface is parallel to the xy plane, the leakage electromagnetic fields from a plurality of the power transmitting coils have an identical vector direction. As a result, when the controller 112 controls the current phase in each of the power transmitting coils, cancellation of the electromagnetic fields is effectively implemented, which can lead to reduction in leakage electromagnetic field intensity.

[0065]

Thus, in the configuration example in which the power transmitting coils are incorporated in one power transmitting device are horizontally placed, power can be transmitted to power receivers with power receiving coils being mounted on the power transmitting device. As a result, it becomes possible to effectively reduce the leakage electromagnetic field intensity.

[0066]

FIG. 7 is a second placement example of power transmitting coils and power receivers. In the configuration example of a power transmitting device 601 which is unlike the case of FIG. 6, power transmitting coils 602A, 602B, 602C, and 602D are placed on a surface parallel to an xz plane so as to be aligned in an x-axis k direction. The power transmitting coils 602A, 602B, 602C, and 602D transmit power via the surfaces of power receivers 603A, 603B, 603C, and 603D which are on a minus side of a Y axis. The power receiver side is also configured to include coils, though illustration thereof is omitted.

[0067]

FIG. 8 illustrates a third placement example of power transmitting coils and power receivers. FIG. 8 illustrates the configuration of a power transmitting device 701 which is identical to that of FIG. 6 except that two power receivers 703A and 703B are provided. In this case, since only two power transmitting coils 702A and 702C serve as a wave source of the leakage electromagnetic field, the controller 112 may control the current phase in these two power transmitting coils 702A and 702C which have power receivers. [0068]

FIG. 9 illustrates the configuration example of shapes of power transmitting coils. As illustrated in FIG. 9(A), in the present embodiment, the power transmitting coil 103-i is a planar one-turn coil 801 in one example. As illustrated in FIG. 9(B), the power transmitting coil 103-i may be a bent coil 802 formed by bending the planar one-turn coil 801 in the middle.

[0069]

The number of turns may be plural. In the case of such a three-dimensional coil, the controller 112 can reduce the leakage electromagnetic field intensity in a similar manner as described in the foregoing. In the case where the plurality of power transmitting coils 103i are placed so that directions of magnetic fields, which extend through the power transmitting coils generated by the currents passing through the power transmitting coils, are parallel to each other, the directions of vectors of the leakage electromagnetic fields generated by the respective power transmitting coils 103-i at an observation point are parallel to each other. Accordingly, by controlling the current phase, the controller 112 enables the leakage electromagnetic fields generated by the currents passing through the power transmitting coils 103-i to cancel each other out. This makes it possible to enhance the effect of reducing the leakage electromagnetic field intensity.

[0070]

< Effects of First Embodiment

In the above-described first embodiment, the controller 112 controls the phase of each current, for at least two out of the plurality of power transmitting coils, to be outputted by the power transmitting circuits 104-i to athese power transmitting coils 103-i, based on a complex current passing through these plurality of power transmitting coils 103-i and the number of turns of these power transmitting coils 103-i.

[0071]

Specifically, the controller 112 calculates a current-turns product, for at least two out of the plurality of power transmitting coils, by multiplying the complex current of these power transmitting coils by the number of turns of these power transmitting coils 103-i, and controls the phase of each current to be outputted by the power transmitting circuits to these power transmitting coils so as to suppress the magnitude of a resultant value of the plurality of calculated current-turns roducts.

[0072]

Accordingly, by controlling the current phase, the controller 112 enables the leakage electromagnetic fields generated by the currents passing through the power transmitting coils 103-i to cancel each other out, so that the intensity of the leakage electromagnetic fields generated by the power transmitting device 10 can be reduced.

Since only the current phase is controlled, the control processing can be executed without changing such parameters as reception power and transmission efficiency in power transmission between the power transmitters and the power receivers.

[0073]

FIG. 10 illustrates a modification of the power transmitting coils. FIG. 10 is a schematic block diagram illustrating the configuration of a power transmitting device 11 in the modification. The power transmitting device 11 in the modification is different from the power transmitting device in the first embodiment illustrated in FIG. 2 in the following points. That is, the power transmitting coil 101-1 is changed to a square-shaped power transmitting coil lOlB-1, the power transmitting coil 101-2 is changed to a diamond-shaped power transmitting coil 101B-2, and the power transmitting coil 101-M is changed to a circular-shaped power transmitting coil 101 B-M. In relation to these changes, the power transmitters 101-i are each changed to power transmitters lOlB-i.

[0074]

As illustrated in FIG. 10, the power transmitting coils

103B-i may be configured to have arbitrary coil shapes such as a square coil, a diamond-shaped coil, and a circular coil. As illustrated in FIG. 10, the plurality of power transmitting coils may have different numbers of turns.

[0075]

In the configuration as illustrated in FIG. 10, the directions of magnetic fields penetrating the power transmitting coil 103B-1, the power transmitting coil 103B-2, and the power transmitting coil 103B-M are identical on the basis of the individual power transmitting coils. Specifically, the magnetic field directions are vertical to the surface of the power transmitting coil lOlB-i. Further, the plurality of power transmitting coils lOlB-i are placed so that the directions of the magnetic fields generated from the respective power transmitting coils are identical to each other. As a result, even when the power transmitting coils lOlB-i are different in shape from each other, the directions of the electric fields or magnetic fields generated from the respective power transmitting coils lOlB-i become identical. As a consequence, when the controller 112 controls the current phase, the intensity of the leakage electromagnetic fields at the observation point can be reduced.

[0076]

Thus, the directions of the magnetic fields generated from the respective power transmitting coils are identical on the basis of the individual power transmitting coils. The plurality of power transmitting coils are placed so that the directions of the magnetic fields generated from the respective power transmitting coils are identical to each other. Accordingly, the directions of the electric fields or magnetic fields at the observation point become identical. Therefore, when the controller 112 controls the current phase, the intensity of the leakage electromagnetic fields at the observation point can be reduced.

[0077]

<Second Embodiment

Hereinafter, a second embodiment will be described. In the first embodiment, the controller 112 controls the current phase in each of the respective power transmitting coils so that the magnitude of a resultant value of current-turns products of the current amplitudes of power transmitting coils and the numbers of turns of these power transmitting coils, calculated for the plurality of the power transmitting coils, becomes equal to or below a preset threshold value.

[0078]

In contrast, in the second embodiment, the control circuit calculates a resultant value of distance current-turns products calculated by dividing the current-turns products of current amplitudes of power transmitting coils and the numbers of turns of these power transmitting coils, calculated for the plurality of power transmitting coils, by an N-th power (N being a preset value) of transmission distances. The control circuit then controls so that the magnitude of the resultant value of distance current-turns products becomes equal to or below a preset threshold value. Accordingly, when a placement interval of the power transmitting coils is wider than a predetermined distance (for example, 1/100 wavelength), the controller 112 can effectively reduce the leakage electromagnetic field. A detailed description will be provided below.

[0079]

FIG. 11 is a schematic block diagram illustrating the configuration of a power transmitting device 12 in the second embodiment. It is to be noted that component members identical to those in FIG. 2 are designated by identical reference characters to omit a concrete description thereof. The configuration of the power transmitting device 12 in the second embodiment is different from the configuration of the power transmitting device 10 in the first embodiment in that the control device 110 is changed to a control device 110b.

[0080]

The control device 110b in the second embodiment is different from the control device 110 in the first embodiment in that a storage 113 is added and the controller 112 is changed to a controller 112b.

[0081]

The storage 113 stores a plurality of transmission distances from each of the power transmitting coils 103-i to a plurality of observation points used for observing leakage electromagnetic fields.

[0082]

The controller 112b acquires a transmission distance corresponding to each of the power transmitting coils 103-i from the storage 113, and calculates a plurality of distance current-turns products by dividing each of the plurality of current-turns products by an N-th power (N being a preset value) of each of the transmission distances corresponding to each of the power transmitting coils. The controller 112b controls the phase of each current passing through the power transmitting coils 103-i so that the magnitude of a resultant value of the plurality of calculated distance current-turns products becomes equal to or below a preset threshold value.

[0083]

Specifically, the controller 112b calculates distance current-turns products by dividing current-turns products of the current amplitudes of the power transmitting coils and the numbers of turns of these power transmitting coils by an N-th power of the transmission distances for all the power transmitting coils 103-i for example. The controller 112b controls the phase of each current passing through the power transmitting coils 103-i so that the magnitude of a resultant value of the calculated distance current-turns products becomes equal to or below a preset threshold value.

[0084]

Here, a leakage electromagnetic field from the power transmitting coil 103-i tends to attenuate in inverse proportion to the N-th power of the distance to an observation point. For example, when the power transmitting coil 103-i is a loop antenna, a leakage magnetic field is attenuated in inverse proportion to a third power of the distance. Therefore, to reduce the leakage magnetic field, the value of "N" is equal to 3 for example. A leakage electric field is attenuated in proportion to a square of the distance. Therefore, to reduce the leakage electric field, the value of "N" is equal to 2 for example.

[0085]

Here, in the case where the loop antenna is incorporated in the power transmitting device 12, an attenuation degree may change due to the influence of a casing of the power transmitting device 12. In that case, a distance characteristic may be measured in advance so as to grasp what power of a distance is the attenuation inversely proportional to. Attenuation process in an electric field is generally different from that in a magnetic field. Accordingly, a designer or a manufacturer of the power transmitting device 12 may determine the value of "N" in accordance with an electromagnetic field component that he/she desires to reduce for example. To reduce both the electric field and the magnetic field, the designer or the manufacturer of the power transmitting device 12 may determine the value of "N" in consideration of the attenuation process of both the electric field and the magnetic field

[0086]

When a placement interval of the power transmitting coils 103-i is equal to or below 1/6 of a wavelength λ corresponding to a frequency f of the current passing through the power transmitting coils (=c/f, provided "c" is a velocity of light), the amount of range attenuation from the power transmitting coil to an observation point is substantially identical in all the power transmitting coils. The reason why the placement interval is set to equal to or below 1/6 of the wavelength is as describe below. That is, assume the case where two power transmitting coils are provided which are identical in current amplitude and the number of turns but are 180 degrees different in phase from each other. If an arrangement interval is 1/6 wavelength, an effect of cancelling leakage electromagnetic fields is degraded, and its leakage electromagnetic field intensity is estimated to be identical to that in the case where only one power transmitting coil is present.

If the placement interval is over 1/6 of a wavelength, the range attenuation from the power transmitting coil to the observation point is different for every power transmitting coil. This poses a new problem that the effect of reducing the electromagnetic field is degraded.

[0087]

Contrary to this, in the present embodiment, the range attenuation can be taken into consideration by employing a distance current-turns product obtained by diving a current-turns product by an N-th power of a transmission distance. Accordingly, the controller 112b controls the current phase in each of the power transmitting coils so that the leakage electromagnetic fields cancel each other out. As a result, even when the range attenuation from the coil to the observation point is different in every power transmitting coil 103-i, the amount of cancelled electric field or magnetic field at the observation point can be increased in consideration of the range attenuation of the magnetic field or the electric field. This makes it possible to effectively reduce the leakage electromagnetic field.

[0088]

Since only the phase of each current passing through the power transmitting coils 103-i are controlled, the control can be implemented without changing power transmission between the power transmitters and the power receivers.

[0089]

When there are multiple observation points, the controller 112b may calculate a plurality of distance current-turns products at a plurality of observation points. For each of the plurality of observation points, the controller 112b may calculate a plurality of distance current-turns products by dividing each of the plurality of current-turns products by an N-th power (N being a preset value) of each of the transmission distances corresponding to each of the power transmitting coils. Then, the controller 112b may control the phase of each current passing through the power transmitting coils 103-i so that the amplitude of a resultant value obtained by combining the plurality of calculated distance current-turns products becomes equal to or below a preset threshold value.

[0090]

Since the power transmitting coils 103-i are distanced from each other, not only the range attenuation but also the amount of phase rotation of an electromagnetic field are different. In order to obtain more cancellation effect of the magnetic fields, the controller 112b may delay the current phase of a power transmitting coil 103-i having a transmission distance longer by the phase rotation amount equivalent to a difference in transmission distance.

[0091]

For example, the controller 112b selects any one of a plurality of transmission distances as a reference and does not provide a phase rotation amount to the selected transmission distance. Assume that one power transmitting coil 103-i has a transmission distance longer by 0.1 wavelength than the reference transmission distance. In this case, the controller 112b delays the phase of the current passing through the power transmitting coil 103-i by the phase rotation amount corresponding to 0.1 wavelength.

[0092]

Specifically, the controller 112b adds -2πό/λ to the phase of the current passing through this power transmitting coil 103-i. Here, V denotes a circular constant, "d" denotes a difference in transmission distance, and "λ" denotes a free space wavelength in the frequency of the current passing through the coil. The difference in transmission distance takes a positive value if the distance is longer than the reference distance, and takes a negative value when the distance is shorter than the reference distance. In this example, the controller 112b adds -0.2π to the phase of the current passing through this power transmitting coil 103-i. Accordingly, even when the transmission distance is longer by 0.1 wavelength, the current phase is made to delay in advance by 0.1 wavelength. As a result, the phase of a magnetic field at the observation point becomes identical to the phase of a magnetic field when the transmission distance is the reference transmission distance. Thus, the controller 112b can set the phase of the magnetic field at the observation point to a desired value by delaying the phase corresponding to a distance of greater than the reference transmission distance. Therefore, the amount of cancelled magnetic fields can be increased.

[0093]

Thus, even when the power transmitting coils 103-i have different phase rotation amounts from the coils to the observation point due to the difference in transmission distance, the controller 112b controls the phase of each current passing through the power transmitting coils 103-i so that the phase of an electric field or a magnetic field at the observation point becomes a desired phase. As a result, it becomes possible to achieve an effect of further enhancing the effect of reducing the leakage electromagnetic field.

[0094]

< Effects of Second Embodiment>

As described above, in the power transmitting device 12 of the second embodiment, the storage 113 stores, for each of the power transmitting coils 103-i, a transmission distance from the power transmitting coil 103-i to an observation point used for observing a leakage electromagnetic field. The controller 112b then acquires, for each of the power transmitting coils 103-i, the transmission distance corresponding to the power transmitting coil 103-i from the storage 113, and calculates a plurality of distance current-turns products by dividing each of the plurality of current-turns products by an N-th power ("N" being a preset value) of each of the transmission distances corresponding to each of the power transmitting coils. The controller 112b controls the phase of each current passing through the power transmitting coils 103-i so as to suppress the magnitude of a resultant value of the plurality of calculated distance current-turns products.

[0095]

As a result, even when the range attenuation from the coil to the observation point is different in every power transmitting coil 103-i, the amount of a cancelled electric field or magnetic field at the observation point can be enlarged in consideration of the range attenuation of the magnetic field or the electric field. This makes it possible to effectively reduce the leakage electromagnetic fields.

[0096]

The threshold value may be a value in consideration of the range attenuation. A relation between a distance current-turns product and a leakage electromagnetic field may be measured in advance with varied transmission distances. An amplitude value of a distance current-turns product which generates a predetermined magnetic field intensity may be used as the threshold value. As a result, the leakage magnetic field intensity can be lowered to the predetermined magnetic field intensity.

[0097]

<Third Embodiment>

Hereinafter, a third embodiment will be described. In the first embodiment, the controller controls the phase of each current passing through the power transmitting coils so that the magnitude of a resultant value of the plurality of current-turns products becomes equal to or below a preset threshold value.

In the third embodiment, the controller controls the phase of each current passing through the power transmitting coils so that the magnitude of a resultant value of a plurality of current-turns product is minimized in one example.

[0098]

FIG. 12 is a schematic block diagram illustrating the configuration of a power transmitting device 13 in the third embodiment. It is to be noted that component members identical to those in FIG. 2 are designated by identical reference characters to omit a concrete description thereof. The configuration of the power transmitting device 13 in the third embodiment is different from the configuration of the power transmitting device 10 in the first embodiment in that the control device 110 is changed to a control device 110c.

[0099]

The control device 110c in the third embodiment is different from the control device 110 in the first embodiment in that a storage 113 is added and the controller 112 is changed to a controller 112c.

[0100]

A power transmitting circuit 104-i measures current amplitude of each current passing through power transmitting coils 103-i, and outputs current signals Sl-i indicative of the measured current amplitudes to a later-described current amplitude setting unit 902 of the controller 112c.

[0101]

FIG. 13 is a schematic block diagram illustrating the configuration of the controller 112c in the third embodiment. The controller 112c includes a current amplitude setting unit 902 electrically connected to each of power transmitting circuits 104-i and a current threshold setting unit 903 electrically connected to the current amplitude setting unit 902. The controller 112c further includes a current phase setting unit 904 electrically connected to the current threshold setting unit 903, and a current phase controller 905 electrically connected to the current phase setting unit 904 and electrically connected to each of the power transmitting circuits 104-i.

[0102]

The current amplitude setting unit 902 sets the amplitude of a current passing through the power transmitting coil 103-i. As described before, the current amplitude setting unit 902 may measure the value of the currents passing through the power transmitting coils 103-i, and set the measured values obtained by measurement as the current amplitudes, or may set the current amplitudes based on the power consumption of the power transmitting circuits 104-i, or may set the current amplitudes based on reception power in the power receivers 201-i.

[0103]

(Specific example of setting measured values as current amplitudes)

Out of the above stated setting methods, the method for setting the measured value as the current amplitude will be described with specific examples as shown below. For example, the current amplitude setting unit 902 may acquire current amplitudes measured in each current passing through the plurality of power transmitting coils 103-i by acquiring current signals Sl-i from the respective power transmitting circuits 104-i. The current amplitude setting unit 902 may set the acquired current amplitudes as the amplitudes of the currents passing through the plurality of corresponding power transmitting coils 103-i.

[0104]

(Specific example of setting current amplitudes based on power consumption of power transmitting circuits 104-i)

Next, a specific example for setting the current amplitudes based on the power consumption of the power transmitting circuits 104-i is as shown below. In this case, the storage 113 may store in advance a correspondence relation between the power consumption of the power transmitting circuits and the amplitudes of the currents passing through the power transmitting coils for example.

In that case, the power transmitting circuits 104-i may detect power consumption of the power transmitting circuits 104-i, and output a power consumption signal indicative of the detected power consumption to the later-described current amplitude setting unit 902 of the controller 112c.

[0105]

Further in that case, the current amplitude setting unit 902 may acquire the power consumption from the respective power transmitting circuits 104-i, and acquire the current amplitudes in the plurality of power transmitting coils 103-i by comparing the acquired power consumption of the plurality of power transmitting circuits with the correspondence relation stored in the storage 113. Then, the current amplitude setting unit 902 may set the acquired amplitudes of the currents as the amplitudes of the currents passing through the plurality of power transmitting coils 103-i .

[0106]

(Specific example for setting current amplitudes based on reception power in power receivers 201-i)

Next, a specific example for setting current amplitudes based on reception power in the power receivers 201-i is as shown below. For example, the communication aid 111 may perform communication to acquire values of reception power in a plurality of power receivers placed face to face with each of the plurality of power transmitting coils. In this case, the storage 113 may store in advance a correspondence relation between the reception power received in the power receivers 201-i placed face to face with the power transmitting coils 103-i and the current amplitudes of the power transmitting coils 103-i. Then, the controller 112c may apply the values of reception power received in the power receivers 201-i acquired by the communication aid 111 to the correspondence relation stored in the storage 113 to set the amplitudes of the currents passing through the plurality of power transmitting coils 103-i .

[0107]

The current threshold setting unit 903 sets a threshold value for the magnitude of a resultant value of the current-turns products. In addition to the methods described in the foregoing, the current threshold setting unit 903 may also use a method that sets the threshold value in accordance with a current amplitude of the power transmitting coil when a transmission power of a power transmitting circuit, which transmits electric power from a power transmission coil with a maximum number of turns among the plurality of power transmitting coils, is maximum . Specifically, the current threshold setting unit 903 may select a power transmission circuit including a power transmitting coil with a maximum number of turns, among the plurality of power transmitting coils, and set as the threshold value a current amplitude of the power transmitting coil when the selected power transmitting circuit transmits maximum transmission power. In this case, the current threshold setting unit 903 can limit the leakage electromagnetic fields, which are generated when the plurality of power transmission processes are simultaneously performed, to be equal to or below the value of a leakage electromagnetic field generated by the power transmitter having the maximum number of turns.

[0108]

When all the power transmitters 101-i are formed to be identical, the value of a current passing through the power transmitting coil 103-i included in one power transmitter 101-i at the time of maximum output of the one power transmitter 101-i may be set as the threshold value. In this case, the current threshold setting unit 903 can limit the leakage electromagnetic fields, which are generated when the plurality of power transmission processes are simultaneously performed, to be equal to or below the value of a leakage electromagnetic field generated in one power transmitter.

[0109]

The current phase setting unit 904 controls the current phase of the power transmitting coil 103-i based on the current amplitude of the power transmitting coil 103-i set in the current amplitude setting unit 902. Specifically, the current phase setting unit 904 controls the current phase in each of the plurality of power transmitting coilsl03-i so that the magnitude of a resultant value of current-turns products is equal to or below a threshold value for example

[0110]

In the present embodiment, the current phase setting unit 904 sets the current phase in each of the plurality of power transmitting coils 103-i so that the magnitude of a resultant value as one example becomes equal to or below the threshold value and also becomes smallest in one example. Thus, by minimizing the magnitude of a resultant value of the current-turns products, the effect of reducing the leakage electromagnetic fields can be maximized.

[0111]

Specifically, when vectors of two current-turns products are combined, the current phase setting unit 904 calculates the magnitude of a resultant value of the current-turns products whenever a phase difference between these two current-turns products is changed in units of 10 degrees for example. The current phase setting unit 904 then sets as the current phase a value that becomes equal to or below the threshold value and that also becomes smallest among the calculated plurality of resultant values.

[0112]

< First Modification of Current Phase Setting Unit 904> In a first modification of the current phase setting unit 904, the current phase setting unit 904 may use a method in which only two values of 0 degree and 180 degrees are set as the current phase value. Since the current phase is a relative value, a pair of 20 degrees and 200 degrees, and/or a pair of 50 degrees and 230 degrees may also be used. Thus, the current phase setting unit 904 sets a phase of each current passing through the plurality of power transmitting coils 103-i to one of a first relative phase and a second relative phase that is opposite to the first relative phase. The opposite phase is a phase 180 degrees different from the other phase.

Accordingly, since only two phases are involved, an effect of facilitating the method for controlling the current phase is obtained. Although only two values are provided, their phases are 180 degrees different from each other, which can provide the effect of sufficiently reducing the intensity of leakage electromagnetic fields.

[0113]

<Second Modification of Current Phase Setting Unit 904> A second modification of the current phase setting unit 904 will be described below. First, the current phase setting unit 904 may number the power transmitting coils 103-i in an ascending order of the amplitude of the current passing through the power transmitting coils 103-i for example. Next, the current phase setting unit 904 may define the phase of a current amplitude of the power transmitting coil 103-i numbered number 1 as a first relative phase for example. Next, the current phase setting unit 904 may define the phase of a current amplitude of the power transmitting coil 103-i numbered number 2 as a second relative phase for example. More specifically, when the power transmitting coils 103-i are arranged in the ascending order of the amplitudes of the current passing through these power transmitting coils 103-i, the current phase setting unit 904 sets the phase of one power transmitting coil, out of the power transmitting coils the numbers of which are adjacent to each other, as the first relative phase, while setting the phase of the other power transmitting coil as the second relative phase that is opposite to the first relative phase.

For example, the current phase setting unit 904 may set relative phases of the target power transmitting coils numbered number three and onward to be opposite to the relative phase of a resultant value of current-turns products of the power transmitting coils the numbers of which are smaller than the number of the target power transmitting coils. Such simple algorithm enables the current amplitude after vector combination to be smaller.

[0114]

<Third Modification of Current Phase Setting Unit 904>

A third modification of the current phase setting unit 904 will be described below. The current phase setting unit 904 may alternately allocate a first relative phase and a second relative phase that is opposite to the first relative phase (180 degrees different in phase) to the power transmitting coils 103-i in order from the power transmitting coil 103-i placed at the end. When the current phase setting unit 904 sets the current phase in this way, the leakage electromagnetic fields from adjacent power transmitting coils 103-i are in a relation of cancelling each other out.

[0115]

Without being limited thereto, the current phase setting unit 904 may set the phase of one power transmitting coil, out of the power transmitting coils 103-i adjacent to each other, as a first relative phase, while setting the phase of the other power transmitting coil as a second relative phase that is opposite to the first relative phase. When the current phase setting unit 904 sets the current phase in this way, the leakage electromagnetic fields from the adjacent power transmitting coils 103-i are in a relation of cancelling each other out.

[0116]

In this case, the shorter the placement interval between the power transmitting coils is, the smaller a difference in transmission distance extending from the power transmitting coil 103-i to an observation point becomes. Accordingly, since a difference in the range attenuation and the phase between the plurality of leakage electromagnetic fields generated at the observation point becomes smaller, the effect of reducing the leakage electromagnetic field intensity can be enhanced.

[0117]

Here, when the plurality of power transmitters 101-i are placed so as to be aligned, the current phase setting unit 904 may alternately set a first relative phase and a second relative phase that is opposite to the first relative phase in this order from the end.

[0118]

In the case where X power transmitters are arranged in an x-axis direction and Y power transmitters are arranged in a y-axis direction on an xy plane, the current phase setting unit 904 may similarly set so that a phase difference between the power transmitting coils adjacent in the x-axis direction and a phase difference between the power transmitting coils adjacent in the y-axis direction are equal to 180 degrees.

[0119]

In the case where X power transmitters are arranged in the x-axis direction, ^' Y power transmitters are arranged in the y-axis direction, and Z power transmitters are arranged in a z-axis direction in an xyz space, the current phase setting unit may similarly set so that a phase difference between the power transmitting coils adjacent in the x-axis direction, a phase difference between the power transmitting coils adjacent in the y-axis direction, and a phase difference between the power transmitting coils adjacent in the z-axis direction are equal to 180 degrees.

[0120]

<Fourth Modification of Current Phase Setting Unit 904> A fourth modification of the current phase setting unit

904 will be described below. In the fourth modification, when a current passing through each power transmitting coil has a harmonic component, the controller 112c can reduce the intensity of leakage electromagnetic fields generated by the harmonic component.

[0121]

A description is given of a processing example in the case of reducing the magnetic fields attributed to the harmonic component in each current passing through the power transmitting coils 103-i in the present modification. Here, it is premised that the number of turns is 1 in all the power transmitting coils 103-i in one example. The power transmitting device 13 further includes a current amplitude-harmonic correspondence storing unit that stores a correspondence relation between the current amplitudes of the power transmitting coil and intensities of magnetic fields (or intensities of electric fields), at a point spaced apart at a predetermined distance from each of the power transmitting coils, generated by a harmonic component of each current passing through the power transmitting coils. [0122]

The current phase setting unit 904 acquires, for example, a current amplitude of each of the plurality of power transmitting coils 103-i. For example, the current phase setting unit 904 then reads out, for each of the power transmitting coils 103-i, a magnetic field intensity (or electric field intensity) corresponding to the acquired current amplitude of each of the power transmitting coils 103-i.

[0123]

For example, the current phase controller 905 controls the phase of each current to be outputted by the power transmitting circuits 104-i to the plurality of power transmitting coils 103-i so as to suppress the magnitude of a resultant value of the read plurality of magnetic intensities (or electric intensities). In that case, the current phase controller 905 controls, for example, the phase of each current to be outputted by the power transmitting circuits 104-i to the plurality of power transmitting coils 103-i, so that the magnitude of a resultant value is equal to or below a preset second threshold value. Accordingly, the controller 112c can reduce the intensity of leakage electromagnetic fields generated due to the harmonic component.

[0124]

When the plurality of the power transmitting coils 103-i include power transmitting coils having a different number of turns, the magnetic fields attributed to the harmonic component in each current passing through the power transmitting coils 103-i may be reduced as shown below. In that case, the amplitude-harmonic correspondence storing unit may store a correspondence relation between the current amplitude of each power transmitting coils 103-i, and the number of turns of each power transmitting coils 103-i, and the intensity of magnetic fields generated due to a harmonic component of the current passing through each power transmitting coils at a point distanced from each of the power transmitting coils by a predetermined distance. [0125]

In that case, the current phase setting unit 904 may acquire the current amplitude in each of the plurality of power transmitting coils for example. The current phase setting unit 904 may read out, for each of the power transmitting coils, the magnetic field intensity corresponding to a pair of the acquired current amplitude of a power transmitting coil and the number of turns of the power transmitting coil for example.

[0126]

The current phase controller 905 may control the phase of each current to be outputted by the power transmitting circuits 104-i to the plurality of power transmitting coils 103-i so as to suppress the magnitude of a resultant value of a plurality of read magnetic intensities. In that case, the current phase controller 905 may control, for example, the phase of each current to be outputted by the power transmitting circuits 104-i to the plurality of power transmitting coils 103-i, so that the magnitude of the resultant value is equal to or below a preset third threshold value. Accordingly, the controller 112c can reduce the intensity of the leakage magnetic fields generated by the harmonic component.

[0127]

The current phase controller 905 generates control signals S-l, S-2, S-M in accordance with the phase set by the current phase setting unit 904. The current phase controller 905 then outputs the generated control signals to the power transmitting circuits 104-1 to 104-M which supply the currents synchronized with the control signals S-l, S-2, S-M to the corresponding power transmitting coils 103-1 to 103-M.

[0128]

Specifically, the current phase controller 905 supplies to the power transmitting circuits 104-i the control signals each having a cycle identical to that of each current passing through the respective power transmitting coils 103-i corresponding to the respective power transmitting circuits 104-i, the control signals being switched between a high level and a low level with a time difference corresponding to the phase set in the current phase setting unit 904 for example.

[0129]

FIG. 14 illustrates a waveform example of two control signals supplied by the current phase controller 905 to two power transmitting circuits. The abscissa of FIG. 14 represents time while the ordinate represents voltage. FIG. 14 illustrates a control signal waveform 1001 for first relative phase control and a control signal waveform for second relative phase control in the case of controlling the current in two current phases, a relative phase of 0 degree and a relative phase of 180 degrees. The control signal for first relative phase control and the control signal for second relative phase control are identical in cycle and are 180 degrees different in phase from each other.

[0130]

In the example of FIG. 14, the control signal for first relative phase control is supplied to the power transmitting circuit 104-1, and the control signal for second relative phase control is supplied to the power transmitting circuit 104-2 for example. The power transmitting circuit 104-1 supplies to the power transmitting coil 103-1 a current having a cycle and a phase identical to those of the control signal for first relative phase control in one example. In this case, the power transmitting circuit 104-2 supplies to the power transmitting coil 103-2 a current having a cycle and a phase identical to those of the control signal for second relative phase control in one example. Accordingly, the current of the power transmitting coil 103-1, and the current of the power transmitting coil 103-2 are identical in cycle and opposite in phase. As a result, electromagnetic fields at the observation point also have opposite phases, so that they cancel each other out.

[0131]

This example is effective in the case of an inverter circuit in which the power transmitting circuits 104-i operate in accordance with the control signals inputted from the current phase controller 905. The phase of each high frequency current supplied from the power transmitting circuits 104-i to the power transmitting coils 103-i is synchronized with the phase of each control signal supplied from the current phase controller 905 to the power transmitting circuits 104-i. As a result, the current phase controller 905 can control the phase of the high frequency current to be the current phase set in the current setting unit 904.

[0132]

In this example, it is necessary to supply control signals to the power transmitting circuits 104-i. Since the current phase controller 905 controls only the phases thereby, the current phase controller 905 does not cause any change in the operation of the power transmitting circuits 104-i themselves. Therefore, since the current phase controller 905 changes only the phase of each current passing through the power transmitting coils 103-i, there is an advantage that transmission power and transmission efficiency of the power transmitters themselves are not changed.

[0133]

As described in the foregoing, the current phase controller 905 can control the phase of each current passing through the power transmitting coils 103-i and can cancel out leakage electromagnetic fields at the observation point by such simple control operation.

[0134]

In the above-described third embodiment, the current phase setting unit 904 sets the current phase in each of the plurality of power transmitting coils so that the magnitude of a resultant value becomes equal to or below the threshold value and also becomes smallest. The current phase controller 905 generates control signals that control the phase of each current to be outputted by the power transmitting circuits 104-i in accordance with the phases set by the current phase setting unit 904 and outputs the generated control signals to the power transmitting circuits 104-i. [0135]

Consequently, the phases of high frequency currents supplied from the power transmitting circuits 104-i to the power transmitting coils 103-i are synchronized with the phases of the control signals supplied from the current phase controller 905 to the power transmitting circuits 104-i. As a result, the current phase controller 905 can control the phases of the high frequency currents to be the current phases set in the current setting unit 904. As a result, the current phase controller 905 can maximize the effect of cancelling out the leakage electromagnetic fields at the observation point.

[0136]

<Modification of Third Embodiment

A modification of the controller 112c is described as a modification of the third embodiment. The controller 112c in this modification sets a current phase difference between the plurality of power transmitting coils 103-i and then resets the current phases of the plurality of power transmitting coils 103-i after a lapse of a predetermined period set in advance. In short, the controller 112c controls the phase of each current at predetermined time intervals. Thus, the controller 112c resets the current phases, so that the intensity of leakage electromagnetic fields can be reduced even when the transmission power to the power receivers changes in time. When it is considered a general case where electric power is transmitted to a power receiver to charge a secondary battery, the present invention can cope with such a case since charge power changes with time.

[0137]

FIG. 15 is a flow chart illustrating an example of the flow of processing that sets the current phase of the power transmitting coils in the modification of the third embodiment. Since steps S201 to S212 are identical to steps S101 to S112 of FIG. 5, a description thereof is omitted.

[0138]

(Step S213) The controller 112c determines whether or not predetermined time elapsed after power transmission. If predetermined time elapsed (YES), the controller 112c returns to step S202. If the predetermined time does not elapse (NO), the controller 112c returns to step S210.

[0139]

Even when there is no change in the number of the power receivers, adding the processing of step S213 enables the controller 112c to control the current phase in response to the current amplitude in each of the power transmitting coils 103-i which changes in time.

[0140]

As a premise, time variations of supply power to a power receiver and time variations of the amplitude of a current flowing to a corresponding power transmitting coil may be measured in advance. The predetermined time may be the time sufficiently shorter than the time taken for the amount of the time variations of the amplitude of the current to become equal to or more than a predetermined amount. When charging of a secondary battery is assumed, the amount of time variations of the amplitude of the current also changes in accordance with capacity and/or performance of the secondary battery. Therefore, the amount of time variations needs to be measured in advance.

[0141]

For example, when the amplitude of each current passing through the power transmitting coils 103-i changes, the magnitude of a resultant value may become larger. In that case, the magnitude of the resultant value may exceed the threshold value. To cope with such situations, in the modification of the third embodiment, a current phase difference between the plurality of power transmitting coils 103-i is reset after a lapse of the time sufficiently shorter than the time taken for the amount of time variations of the current amplitude to become equal to or more than a predetermined amount. This makes it possible to prevent the magnitude of the resultant value from exceeding the threshold value. [0142]

Modification in Case Where Current Amplitude Changes in Time>

A modification of the method for reducing the leakage electromagnetic fields even when the current amplitude changes in time will be described in detail below. Assume the case of charging a secondary battery included in each power receiver 201-i. In this case, the amplitude of each current passing through the power transmitting coils 103-i decreases as time elapses. A description will be given of this case as an example.

[0143]

For example, it is premised that the storage 13 stores a present charge amount of the secondary battery in association with a predictive value of the current amplitude of each power transmitting coil after a lapse of predetermined time. Under the premise, the communication aid 111 of the power transmitting device 13 acquires a present charge amount of the secondary battery included in each power receiver 201-i by wireless communications for example. The current phase setting unit 904 predicts a current amplitude of the power transmitting coil after a lapse of predetermined time based on the present charge amount of the secondary battery acquired by the communication aid 111. Specifically, the current phase setting unit 904 acquires from the storage 13 a predictive value of the current amplitude of the power transmitting coil after a lapse of the predetermined time corresponding to the acquired present charge amount of the secondary battery.

[0144]

The current phase setting unit 904 generates a first resultant value of current-turns products with use of the amplitude of each current passing through the present power transmitting coils. At the same time, the current phase setting unit 904 generates a second resultant value of the current-turns products with use of an obtained predictive value of the current amplitude in each of the power transmitting coils after a lapse of the predetermined time. The current phase setting unit 904 sets the current phase of each power transmitting coil 103-i so that both the first resultant value and the second resultant value are equal to or below the predetermined threshold value. By setting the current phase in this way, the current phase setting unit 904 can make the intensity of leakage electromagnetic fields equal to or below a preset restriction value even after a lapse of the predetermined time.

[0145]

<Fourth Embodiment>

Hereinafter, a forth embodiment will be described. The power transmitting device in the fourth embodiment is different from the power transmitting device 10 in the first embodiment in placement of the power transmitting coils.

[0146]

FIG. 16 is an explanatory view of the placement of the power transmitting coils according to the fourth embodiment. FIG. 16 illustrates an example in which the power transmitting coils are placed on a two-dimensional plane. The example of FIG. 16 includes four power transmitting coils 1202A, 1202B, 1202C, and 1202D aligned in an x-axis directions on a y-axis plus side, and four power transmitting coils 1202E, 1202F, 1202G, and 1202H aligned in the x-axis direction on a y-axis minus side. Thus, total eight power transmitting coils are arranged in two lines. In the presentembodiment, four power transmitting coils on the y-axis plus side are incorporated in one casing 1201A, while four power transmitting coils on the y-axis minus side are incorporated in one casing 1201B.

[0147]

FIG. 17 is a first modification of the placement of the power transmitting coils. This is also an example in which the power transmitting coils are placed in two dimensions. The example of FIG. 17 includes four power transmitting coils 1302A, 1302B, 1302C, and 1302D aligned in the x-axis direction on a z-axis minus side, and four power transmitting coils 1302E, 1302F, 1302G, and 1302H aligned in the x-axis direction on a z-axis plus side. Thus, total eight power transmitting coils are arranged in two lines. In the first modification, four power transmitting coils 1302A, 1302B, 1302C, and 1302D on the z-axis minus side are incorporated in one casing 1301A, while four power transmitting coils 1302E, 1302F, 1302G, and 1302H on the z-axis plus side are incorporated in one casing 1301B.

[0148]

FIG. 18 illustrates a second modification of the placement of the power transmitting coils according to the second modification of the fourth embodiment. Two lines of four power transmitting coils extend in the x-axis direction, and two lines extend in the z-axis direction, so that total sixteen power transmitting coils are provided. In the second modification, four pairs of the power transmitting coils are respectively incorporated in casings 1401A, 1401B, 1401C, and 1401D.

[0149]

< Fifth Embodiment

Hereinafter, a fifth embodiment will be described. A power transmitting device 10 in the fifth embodiment is different from the power transmitting device 10 in the first embodiment in that the power transmitters 101-1 to 101-M are changed to power transmitters 1501-1 to 1501-M. Hereinafter, the power transmitters 1501-1 to 1501-M are generically referred to as a power transmitter/transmitters 1501.

[0150]

FIG. 19 is a schematic block diagram illustrating the configuration of the power transmitter 1501 in the fifth embodiment. The power transmitter 1501 includes at least a power transmitting coil 1502, a power transmitting circuit 1504, and a connection switching circuit 1503.

[0151]

The connection switching circuit 1503 includes a first coil terminal 1505 connected to one end of the power transmitting coil 1502, and a second coil terminal 1506 connected to the other end of the power transmitting coil 1502.

The connection switching circuit 1503 further includes a first circuit terminal 1507 connected to a first output of the power transmitting circuit 1504, and a second circuit terminal 1508 connected to a second output of the power transmitting circuit 1504.

[0152]

A description is now given of first connection state and a second connection state of the power transmitter 1501 with reference to FIGS. 20 and 21. FIG. 20 is a schematic block diagram illustrating the first connection state of the power transmitter 1501 in the fifth embodiment. FIG. 21 is a schematic block diagram illustrating the second connection state of the power transmitter 1501 in the fifth embodiment.

[0153]

As illustrated in FIG. 20, the connection switching circuit 1503 has a first connection state in which the first coil terminal 1505 and the first circuit terminal 1507 are connected, while the second coil terminal 1506 and the second circuit terminal 1508 are connected. More specifically, in the first connection state, one end of the power transmitting coil 1502 and the first output of the power transmitting circuit 1504 are connected, while the other end of the power transmitting coil 1502 and the second output of the power transmitting circuit 1504 are connected.

[0154]

As illustrated in FIG. 21, the connection switching circuit 1503 has a second connection state in which the first coil terminal 1505 and the second circuit terminal 1508 are connected, while the second coil terminal 1506 and the first circuit terminal 1507 are connected. More specifically, in the second connection state, one end of the power transmitting coil 1502 and the second output of the power transmitting circuit 1504 are connected, while the other end of the power transmitting coil 1502 and the first output of the power transmitting circuit 1504 are connected.

[0155]

The connection switching circuit 1503 switches the first connection state and the second connection state based on a control signal S-i from the controller 112. Specifically, the connection switching circuit 1503 asserts the first connection state when the control signal S-i is high-level, and asserts the second connection state when the control signal S-i is low-level for example.

[0156]

Thus, when the connection switching circuit 1503 switches the connection state, two current phases of the power transmitting coil 1502, the first current phase and the second current phase that is opposite to the first current phase, can be implemented. Therefore, it becomes possible to control the phase of each current passing through the power transmitting coils 1502 to be one of two phases: 0 degrees and 180 degrees, while keeping the phase of each current to be outputted by the power transmitting circuits 1504 identical. In this case, supply voltage supplied to the power transmitting coils 1502 by the power transmitting circuits 1504 can be made identical in all the power transmitting circuits 1504.

[0157]

<Sixth Embodiment

Hereinafter, a sixth embodiment will be described. As compared with the power transmitting device 10 in the first embodiment, the power transmitting device 10 in the sixth embodiment includes a plurality of power transmitters including a plurality of power transmitting coils 1601-i, wherein an identical current is passed to the plurality of power transmitting coils 1601-i. Further, in the power transmitting device 10 in the sixth embodiment, the plurality of power transmitting coils 1601-i are placed at identical intervals on a one-dimensional straight line or a two-dimensional plane or in three-dimensional cubic space, so that directions of magnetic fields, which extend through the power transmitting coils generated by each current passing through the power transmitting coils, are parallel to each other. Further, winding directions of the plurality of power transmitting coils placed adjacent to each other are different from each other. [0158]

When the plurality of power transmitting coils are identical and the amplitudes of the passing currents are identical, the effect of canceling out the leakage electromagnetic fields is maximized if the current phases of the adjacent power transmitting coils are made identical. Even when the current amplitudes are different, the effect of cancelling out the leakage electromagnetic fields can be implemented to some degree.

[0159]

FIG. 22 is an explanatory view of the placement of the power transmitting coils 1601-1 to 1601-4 according to the sixth embodiment. FIG. 22 illustrates an example in which four power transmitting coils are provided. From the left end side, there are placed a power transmitting coil 1601-1 of a left turn on an xy plane, a power transmitting coil 1601-2 of a right turn on the xy plane, a power transmitting coil 1601-3 of a left turn on the xy plane, and a power transmitting coil 1601-4 of a right turn on the xy plane in this order. The winding directions of the adjacent power transmitting coils are different from each other.

[0160]

In the above-described sixth embodiment, the power transmitting device 10 includes a plurality of power transmitting coils, and at least one or more power transmitting circuits that transmits electric power in a non-contact manner by causing the plurality of power transmitting coils to generate electromagnetic fields. The plurality of power transmitting coils are placed at identical intervals on a one-dimensional straight line, or a two-dimensional plane, or in three-dimensional cubic space. The directions of magnetic fields, which extend through the power transmitting coils generated by each current passing through the power transmitting coils, are parallel to each other. Further, the winding directions of two power transmitting coils placed adjacent to each other are different from each other.

[0161]

Thus, since the winding directions of two power transmitting coils placed adjacent to each other are made different from each other, the power transmitting device 10 can cause the phases of electric fields or magnetic fields generated at the observation point by the currents passing through these two power transmitting coils to be opposite to each other. Accordingly, since two electric fields or magnetic fields generated at the observation point cancel each other out, the power transmitting device 10 can reduce the leakage electromagnetic fields at the observation point.

[0162]

When a current passing through the power transmitting coil is equal to or below a predetermined threshold value, the controller 112 does not need to calculate a current-turns product. In that case, a preset threshold value may be set as a third threshold value that is smaller than the value obtained by combining all the current-turns products. In this relation, the controller 121 may calculate the current-turns product only in the case when a current passing through the power transmitting coil 1601-i exceeds the predetermined threshold value. The controller 121 may control the current phase of each power transmitting coil 1601-i so that the magnitude of a resultant value of the calculated current-turns products becomes smaller than the third threshold value.

[0163]

Thus, the controller 121 calculates current-turns products, for at least two of the plurality of power transmitting coils, which are products of the value of a current passing through these power transmitting coils and the number of turns of these power transmitting coil and controls the phase of each current to be outputted by the power transmitting circuits to these power transmitting coils, based on the plurality of calculated current-turns products.

[0164]

In each of the embodiments, the frequency of each current passing through each power transmitting coil is described to be identical in one example. However, the frequency may have a deviation within a specified range.

[0165]

In each of the embodiments, the power transmitting circuits cause the power transmitting coil to generate a magnetic field by outputting current to corresponding in one to one relation to a power transmitting coil and thereby transmit electric power in a non-contact manner. However, the present invention is not limited to this configuration. One arbitrary power transmitting circuit may output current to all the power transmitting coils, or a plurality of power transmitting circuits may share the operation of outputting currents to all the power transmitting coils. Therefore, at least one or more power transmitting circuits may cause a plurality of power transmitting coils to generate magnetic fields and to transmit electric power in a non-contact manner.

[0166]

Moreover, in each of the embodiments, a plurality of power transmitting coils are placed so that the directions of magnetic fields, which extend through the power transmitting coils generated by the currents passing through the power transmitting coils, are parallel to each other. However, the present invention is not limited to this configuration. The directions of magnetic fields, which extend through the power transmitting coils generated by the currents passing through the power transmitting coils, may not be parallel to each other. In that case, since the directions of magnetic fields or electric fields at the observation point are different from each other, the controller may control so that the intensity of a combined magnetic field, which is formed by spatially combining magnetic field or electric field vectors, becomes equal to or below a predetermined threshold value.

[0167]

In each of the embodiments, the power transmitting coil may be wound around a core.

[0168]

The magnetic field observed at the observation point is proportional to the area of a power transmitting coil. Accordingly, in addition to the complex current passing through the power transmitting coil and the number of turns of the power transmitting coil, the controller may also use the area of the power transmitting coil as a basis of controlling the phase of each current to be outputted by the power transmitting circuits to the plurality of power transmitting coils. Specifically, the controller may calculate, for two out of the plurality of power transmitting coils, a second current-turns product by multiplying the complex current by the number of turns and the area of the power transmitting coil. The controller may control the phase of each current to be outputted by the power transmitting circuits to the plurality of power transmitting coils so as to suppress the magnitude of a resultant value of the plurality of calculated second current-turns products.

[0169]

In a system including a plurality of devices, these plurality of devices may dispersedly execute the respective processes of the control device in each of the embodiments.

The above-stated various processes according to the control device in each of the embodiments may be executed by recording a program, which is adapted to execute each process of the control device in each of the embodiments, on a computer-readable recording medium, and causing a computer system to read and execute the program stored in the recording medium.

[0170]

The "computer system" used herein may refer to a system including hardware, such as an OS and peripheral equipment. In the case where a WWW system is used, the "computer system" includes a homepage provision environment (or a display environment). Moreover, the "computer-readable recording medium" refers to: a writable nonvolatile memory such as a flexible disk, a magneto-optical disk, a ROM, and a flash memory; a portable medium such as a CD-ROM; and a memory device such as a hard disk incorporated in a computer system.

[0171]

Further, the "computer-readable recording medium" includes media that hold a program for a definite period of time like a volatile memory (for example, a dynamic random access memory (DRAM)) inside a computer system used as a server or a client when the program is transmitted via a network such as the Internet and/or a communication line such as a telephone line. The program may be transferred from a computer system, which stores the program in its storage device and the like, to another computer system via a transfer medium or via a transmission wave in the transmission medium. The "transfer medium" that transfers the program herein refers to a medium having a function of transferring information, such as a network (communication network) such as the Internet and a communication line (communication link) such as a telephone line. The program may also be adapted to implement a part of the above-stated function. Further, the program may be so-called a differential file (differential program) which can implement the above-stated function in combination with a program already recorded on the computer system.

[0172]

While certain embodiments have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fall within the scope and spirit of the inventions.