U.S. patent application number 12/788753 was filed with the patent office on 2011-01-27 for power receiving apparatus, power transmission system, charging apparatus and power transmission method.
This patent application is currently assigned to Sony Corporation. Invention is credited to Hiroyuki MITA.
Application Number | 20110018494 12/788753 |
Document ID | / |
Family ID | 43034564 |
Filed Date | 2011-01-27 |
United States Patent
Application |
20110018494 |
Kind Code |
A1 |
MITA; Hiroyuki |
January 27, 2011 |
POWER RECEIVING APPARATUS, POWER TRANSMISSION SYSTEM, CHARGING
APPARATUS AND POWER TRANSMISSION METHOD
Abstract
A power receiving apparatus includes: a resonance element having
a specific resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship; a rectification section
configured to rectify ac current of the resonance frequency in
response to energy received by the resonance element; and a
switching section configured to cut off a supplying path of the ac
current from the resonance element to the rectification section;
the resonance element maintaining the coupling state through the
resonance relationship to the different resonance element also when
the supplying path of the ac current to the rectification section
is blocked by the switching section.
Inventors: |
MITA; Hiroyuki; (Saitama,
JP) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Sony Corporation
Tokyo
JP
|
Family ID: |
43034564 |
Appl. No.: |
12/788753 |
Filed: |
May 27, 2010 |
Current U.S.
Class: |
320/108 ;
307/104 |
Current CPC
Class: |
H02J 50/80 20160201;
H02J 50/40 20160201; H02J 7/025 20130101; H02J 7/00034 20200101;
H02J 50/12 20160201; H02J 50/50 20160201 |
Class at
Publication: |
320/108 ;
307/104 |
International
Class: |
H02J 7/00 20060101
H02J007/00; H02J 17/00 20060101 H02J017/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 22, 2009 |
JP |
2009-170805 |
Claims
1. A power receiving apparatus, comprising: a resonance element
having a specific resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship; rectification means for
rectifying alternating current of the resonance frequency in
response to energy received by said resonance element; and
switching means for cutting off a supplying path of the alternating
current from said resonance element to said rectification means;
said resonance element maintaining the coupling state through the
resonance relationship to the different resonance element also when
the supplying path of the alternating current to said rectification
means is blocked by said switching means.
2. The power receiving apparatus according to claim 1, wherein said
resonance element holds a current path in the form of a loop to
maintain the coupling state through the resonance relationship to
the different resonance element.
3. The power receiving apparatus according to claim 1, further
comprising an excitation element adapted to couple to said
resonance element through electromagnetic induction; induction
current which flows to said excitation element through the
electromagnetic induction coupling between said resonance element
and said excitation element being supplied to and rectified by said
rectification means; said switching means being provided at a
position at which said switching means carries out cutoff control
of a supplying path of the induction current from said excitation
element to said rectification means.
4. The power receiving apparatus according to claim 1, wherein said
switching means is controlled to switch in response to a manual
operation by a user.
5. The power receiving apparatus according to claim 1, further
comprising: a load adapted to receive direct current obtained by
the rectification by said rectification means as power supply
current thereto; instruction inputting means for inputting an
instruction regarding whether or not said load should be rendered
operative; and means for controlling said switching means to a
state in which said switching means cuts off supply of current
through said supplying path to said rectification means in response
to the instruction input received through said instruction
inputting means for rendering said load inoperative.
6. The power receiving apparatus according to claim 1, further
comprising: a rechargeable battery; a charging circuit adapted to
charge said battery with direct current obtained by the
rectification by said rectification means; detection means for
detecting that said battery is charged up; and means for
controlling said switching means to a state in which said switching
means cuts off supply of current through said supplying path to
said rectification means when said detection means detects that
said battery is charged up.
7. The power receiving apparatus according to claim 1, further
comprising radio communication means; said switching means being
controlled to switch based on instruction information received by
said communication means.
8. A power transmission system, comprising: a power transmitting
apparatus; and a plurality of power receiving apparatus; said power
transmitting apparatus including a first resonance element having a
specific resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship, and frequency signal generation
means for supplying alternating current of the resonance frequency
to said first resonance element, each of said plurality of power
receiving apparatus including a second resonance element having the
resonance frequency and adapted to couple in a non-contacting
relationship to a different resonance element through a resonance
relationship, and rectification means for rectifying alternating
current of the resonance frequency in accordance with energy
received by said second resonance element, at least one of said
plurality of power receiving apparatus further including switching
means for cutting off supply of the alternating current from said
second resonance element to said rectification means, said second
resonance element maintaining a state wherein said second resonance
element couples to the different resonance element through the
resonance relationship also when the supplying path of the
alternating current to said rectification means is cut off by said
switching means, said second resonance element of the power
receiving apparatus in which said switching means is controlled to
the state wherein said switching means cuts off the supplying path
being coupled to said first resonance element of said power
transmitting apparatus or said second resonance element of a
different one of said power receiving apparatus through a resonance
relationship and also to said second resonance element of another
different one of said power receiving apparatus through a resonance
relationship to carry out repeating of transmission of the power
from said power transmitting apparatus.
9. The power transmission system according to claim 8, wherein each
of said power receiving apparatus further includes an excitation
element for coupling to said second resonance element through
electromagnetic induction; induction current which flows to said
excitation element by the electromagnetic induction coupling
between said second resonance element and said excitation element
being supplied to and rectified by said rectification means, said
switching means being provided at a position at which said
switching means cuts off supply of the induction current from said
excitation element to said rectification means.
10. A charging apparatus for charging a rechargeable battery of a
power receiving apparatus which includes a first resonance element
having a specific resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship, rectification means for
rectifying alternating current of the resonance frequency in
response to energy received by the first resonance element,
switching means for cutting off supply of the alternating current
from the first resonance element to the rectification means, the
rechargeable battery, and a charging circuit adapted to charge the
battery with direct current obtained by the rectification by the
rectification means, the first resonance element maintaining a
state wherein the first resonance element couples to the different
resonance element through the resonance relationship also when the
supplying path of the alternating current to the rectification
means is cut off by the switching means, said charging apparatus
comprising: a second resonance element having a particular
resonance frequency and adapted to couple in a non-contacting
relationship to a different resonance element through a resonance
relationship; frequency signal generation means for supplying
alternating current of the resonance frequency to said second
resonance element; and a mounting table capable of receiving a
plurality of power receiving apparatus placed thereon such that
said second resonance element is coupled to the first resonance
elements of the power receiving apparatus placed on said mounting
table through a resonance relationship.
11. The charging apparatus according to claim 10, wherein the power
receiving apparatus includes: detection means for detecting that
the battery is charged up; and means for controlling said switching
means to cut off the supplying path when said detection means
detects that the battery is charged up.
12. The charging apparatus according to claim 10, further
comprising: radio communication means for communicating with the
power receiving apparatus by radio; and means for producing
information for controlling switching operation of the switching
means of the power receiving apparatus based on information
received from the power receiving apparatus by said radio
communication means and supplying the produced information to the
power receiving apparatus through said radio communication means to
control switching operation of the switching means of the power
receiving apparatus.
13. The charging apparatus according to claim 10, wherein said
mounting table has indications provided thereon for indicating
recommendable mounting positions at which the power receiving
apparatus should be placed.
14. A power transmission method for a power transmission system
which includes a power transmitting apparatus including a first
resonance element having a specific resonance frequency and adapted
to couple in a non-contacting relationship to a different resonance
element through a resonance relationship and frequency signal
generation means for supplying alternating current of the resonance
frequency to the first resonance element, and a plurality of power
receiving apparatus each including a second resonance element
having the resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship and rectification means for
rectifying alternating current of the resonance frequency in
accordance with energy received by the second resonance element, at
least one of the power receiving apparatus further including
switching means for cutting off supply of the alternating current
from the second resonance element to the rectification means, the
second resonance element maintaining a state wherein the second
resonance element couples to the different resonance element
through the resonance relationship also when the supplying path of
the alternating current to said rectification means is cut off by
the switching means, said power transmission method comprising the
step of: controlling the switching means to the state in which the
switching means cuts off the supplying path to couple the second
resonance element of the power receiving apparatus in which the
supplying path is cut off by the switching means to the first
resonance element of the power transmitting apparatus or the second
resonance element of a different one of the power receiving
apparatus through a resonance relationship and also to the second
resonance element of another different one of the power receiving
apparatus through a resonance relationship to carry out repeating
of transmission of the power from the power transmitting apparatus.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] This invention relates to an apparatus and a method for
transmitting power by radio utilizing resonance of an
electromagnetic field.
[0003] 2. Description of the Related Art
[0004] As a technique for transmitting power by radio, a technique
is well known which utilizes electromagnetic induction. In the
power transmission which utilizes electromagnetic induction,
current is supplied to one of two coils positioned closely to each
other such that electromagnetic force is generated in the other
coil by intermediation of magnetic fluxes generated from the one
coil.
[0005] However, according to the power transmission which utilizes
the electromagnetic induction, the two coils must be positioned
closely to each other. Therefore, the power transmission has a
problem that the distance over which the power can be transmitted
is restricted. Further, if the axes of the coils upon
electromagnetic induction coupling are brought out of alignment
with each other, then the transmission efficiency is degraded.
Therefore, the alignment upon coupling is significant.
[0006] In the meantime, a method wherein resonance of an
electromagnetic field is utilized to transmit power has been
proposed recently. According to the resonance type radio power
transmission, power can be transmitted over such a distance as
three to four meters and besides high power can be transmitted.
Therefore, resonance type radio power transmission has an advantage
that also a system which does not have a secondary cell, that is, a
rechargeable battery, on the reception side can be constructed
readily.
[0007] Further, the resonance type radio power transmission has
little influence on any other electronic apparatus because energy
is not transmitted if it has no resonating mechanism. Further,
there is an advantage also in that, even if the alignment upon
coupling is not very good, the transmission efficiency does not
drop very much.
[0008] A power transmission system which uses a resonance
phenomenon in a magnetic field is disclosed, for example, in U.S.
Published Patent Application No. 2007/0222542 (hereinafter referred
to as Patent Document 1).
[0009] An example of a configuration of the power transmission
system which uses a magnetic field resonance phenomenon is shown in
FIG. 9. FIG. 9 particularly shows an example of a system
configuration where a power transmitting apparatus 10 of a
supplying source of power and a power receiving apparatus 20 of a
supplying destination or receiving side of power are provided in a
one-by-one corresponding relationship to each other.
[0010] Referring to FIG. 9, the power transmitting apparatus 10
includes a resonance element 11, an excitation element 12 and a
frequency signal generation section 13.
[0011] The resonance element 11 is formed, for example, from an
air-core coil in the form of a loop coil. The excitation element 12
is formed, for example, from an air-core coil, which is connected
at the opposite ends thereof to two output terminals of the
frequency signal generation section 13. The resonance element 11
and the excitation element 12 are placed in a relationship wherein
they are coupled strongly with each other by electromagnetic
induction.
[0012] The air-core coil which forms the resonance element 11 has
not only inductance but also coil internal capacitance and has a
self resonance frequency which depends upon the inductance and the
capacitance.
[0013] The frequency signal generation section 13 generates a
frequency signal of a frequency equal to the self resonance
frequency of the resonance element 11. The frequency signal
generation section 13 may be formed from a Colpitts type
oscillation circuit, a Hartley type oscillation circuit or the
like.
[0014] Though not shown, the power transmitting apparatus 10
receives supply of power from an ac power supply so that a
frequency signal is generated from the frequency signal generation
section 13.
[0015] Meanwhile, the power receiving apparatus 20 include a
resonance element 21, an excitation element 22, a rectification
circuit 23 and a load 24.
[0016] The resonance element 21 is formed, for example, from an
air-core coil in the form of a loop coil similarly to the resonance
element 11. The excitation element 22 is formed, for example, from
an air-core coil, which is connected at the opposite ends thereof
to two input terminals of the rectification circuit 23. The
resonance element 21 and the excitation element 22 are configured
so as to have a relationship wherein they are coupled strongly to
each other by electromagnetic induction.
[0017] The air-core coil which forms the resonance element 21 has
not only inductance but also coil internal capacitance and has a
self resonance frequency which depends upon the inductance and the
capacitance similarly as in the resonance element 11.
[0018] The self resonance frequencies of the resonance element 11
and the resonance element 21 are equal to each other and a
frequency fo.
[0019] In such a system configuration as described above, the
frequency signal generation section 13 in the power transmitting
apparatus 10 supplies a frequency signal equal to the self
resonance frequency fo of the resonance elements 11 and 21 to the
excitation element 12.
[0020] Accordingly, ac current of the frequency fo flows to the
air-core coil of the excitation element 12, and induction current
of the same frequency fo is induced in the resonance element 11
formed similarly from an air-core coil by electromagnetic
induction.
[0021] In the circuit configuration of FIG. 9, the self resonance
frequency of the air-core coil which forms the resonance element 21
of the power receiving apparatus 20 is the frequency fo and
coincides with the self resonance frequency of the resonance
element 11 of the power transmitting apparatus 10. Accordingly, the
resonance element 11 of the power transmitting apparatus 10 and the
resonance element 21 of the power receiving apparatus 20 have a
magnetic field resonance relationship and exhibit a maximum
coupling amount and minimum loss at the frequency fo.
[0022] Since the resonance element 11 of the power transmitting
apparatus 10 and the resonance element 21 of the power receiving
apparatus 20 in the present circuit configuration have a magnetic
field resonance relationship as described above, ac current is
supplied in a contactless fashion from the resonance element 11 to
the resonance element 21 at the resonance frequency fo.
[0023] In the power receiving apparatus 20, induction current is
induced in the excitation element 22 by electromagnetic induction
by ac current appearing in the resonance element 21. The induction
current induced in the excitation element 22 is rectified into dc
current by the rectification circuit 23 and supplied as power
supply current to the load 24.
[0024] In this manner, a magnetic field resonance phenomenon is
utilized to transmit power by radio from the power transmitting
apparatus 10 to the power receiving apparatus 20.
[0025] A relationship between the frequency of the frequency signal
from the frequency signal generation section 13 in the power
transmission system of the configuration shown in FIG. 9 and the
coupling amount in magnetic field resonance is illustrated in FIG.
10. As can be seen apparently from FIG. 10, the power transmission
system of the configuration of FIG. 9 indicates frequency
selectivity wherein a maximum coupling amount is obtained at the
resonance frequency fo.
[0026] FIG. 11 illustrates a relationship between the distance D
between the resonance element 11 of the power transmitting
apparatus 10 and the resonance element 21 of the power receiving
apparatus 20 and the coupling amount in magnetic field resonance.
From FIG. 11, it can be recognized that, although the coupling
amount increases as the distance decreases, where the distance is
very short, the coupling amount is rather low. Thus, it can be
recognized that a certain distance exists at which the coupling
amount is maximum at a certain resonance frequency.
[0027] FIG. 12 illustrates a relationship between the resonance
frequency and the distance between resonance elements at which a
maximum coupling amount is obtained. From FIG. 12, it can be seen
that a maximum coupling amount is obtained if, where the resonance
frequency is low, the distance between the resonance elements is
increased, but where the resonance frequency is high, the distance
between the resonance elements is decreased.
SUMMARY OF THE INVENTION
[0028] As described above, in the power transmission system of the
resonance type, even if the distance between the power transmitting
apparatus and the power receiving apparatus is comparatively great
or even if the coupling axes are somewhat out of alignment with
each other, power transmission can be carried out.
[0029] Therefore, it is possible to transmit power from a single
power transmitting apparatus 10 of a power supplying source to a
plurality of power supplying destinations as seen in FIG. 13, which
illustrates that power is transmitted to two power receiving
apparatus 20A and 20B as power supplying designations. It is to be
noted that the power receiving apparatus 20A and 20B have a
configuration quite same as that of the power receiving apparatus
20 described hereinabove and include like components which are
indicated by like reference symbols with suffixes A and B added
thereto, respectively.
[0030] It is assumed here that the self resonance frequency of the
resonance element 11 of the power transmitting apparatus 10 and the
self resonance frequency of resonance elements 21A and 21B of the
two power receiving apparatus 20A and 20B are equal to each
other.
[0031] Since the coupling amount between a power supplying source
and a power supplying destination increases as the distance between
the resonance elements decreases, in the example shown in FIG. 13,
the power receiving apparatus 20B has a coupling amount greater
than that of the power receiving apparatus 20A to the power
transmitting apparatus 10.
[0032] Since power to be supplied from the power supplying source
to the power supplying destination increases as the distance
between the resonance elements increases, the power supplied from
the power transmitting apparatus 10 is relatively higher to the
power receiving apparatus 20B than to the power receiving apparatus
20A.
[0033] Incidentally, apart from a case wherein it is necessary to
render operative both of the power receiving apparatus 20A and the
power receiving apparatus 20B and supply of dc current to loads is
demanded, a case wherein there is no necessity to render one of the
two apparatus operative matters.
[0034] In particular, each of the power receiving apparatus
described above is configured such that it normally receives power
transmitted thereto by radio. Therefore, even where any of the
power receiving apparatus does not demand reception of power, if
the power receiving apparatus is positioned such that it can
receive supply of power from the power transmitting apparatus 10,
then power is supplied to the power receiving apparatus uselessly
and rectified by the rectification circuit 23 and then
consumed.
[0035] Thus, if a plurality of power receiving apparatus have a
magnetic field resonance relationship with the power transmitting
apparatus 10 as seen in FIG. 13, then electric energy from the
power transmitting apparatus 10 is distributed and transmitted to
the plural power receiving apparatus. Therefore, the power received
by each of the power receiving apparatus decreases in response to
the number of such power receiving apparatus, resulting in a
problem that the power receiving apparatus which demands reception
of power cannot receive sufficient power from the power
transmitting apparatus.
[0036] Particularly if the power receiving apparatus 20B positioned
nearer to the power transmitting apparatus 10 in FIG. 13 need not
operate and does not demand reception of power, the power to be
supplied to the power receiving apparatus 20A which demands
reception of power decreases in a distribution relationship, which
is not efficient.
[0037] Therefore, it is desirable to provide an apparatus and a
method which can eliminate such a problem as described above.
[0038] According to the present embodiment, there is provided a
power receiving apparatus including a resonance element having a
specific resonance frequency and adapted to couple in a
non-contacting relationship to a different resonance element
through a resonance relationship, rectification means for
rectifying ac current of the resonance frequency in response to
energy received by the resonance element, and switching means for
cutting off a supplying path of the ac current from the resonance
element to the rectification means, the resonance element
maintaining the coupling state through the resonance relationship
to the different resonance element also when the supplying path of
the ac current to the rectification means is blocked by the
switching means.
[0039] It is assumed that the power receiving apparatus is
positioned such that it couples to the power transmitting apparatus
through a resonance relationship and couples also to a different
power receiving apparatus through a resonance relationship. In this
instance, the resonance element of the power receiving apparatus
couples to both of the resonance element provided in the power
transmitting apparatus and the resonance element of the different
power receiving apparatus through a resonance relationship.
[0040] When the power receiving apparatus having the configuration
described above need not receive supply of power, the supplying
path of ac current from the resonance element to the rectification
means is cut off by the switching means.
[0041] However, at this time, the resonance element of the power
receiving apparatus is kept in the state wherein it couples to the
different resonance element through a resonance relationship.
Accordingly, in the power receiving apparatus, the power which the
resonance element receives from the power transmitting apparatus is
transferred to the resonance element of the difference power
receiving apparatus which is kept coupled to the resonance element
through a resonance relationship while supply of current to the
rectification means is cut off by the switching means.
[0042] Thus, the resonance element of the power receiving apparatus
in which the supplying path of ac current from the resonance
element to the rectification means is cut off plays a role of
repeating means for repeating power from the power transmitting
apparatus to the different power receiving apparatus.
[0043] In this instance, the different power receiving apparatus
receives supply of power transmitted through the coupling through a
direct resonance relationship with the power transmitting apparatus
and besides receives reception of power through the coupling
through a resonance relationship with the power receiving
apparatus. Consequently, the power supply amount to the different
power receiving apparatus increases.
[0044] Consequently, with the power receiving apparatus, power
transmitted thereto through the coupling through a resonance
relationship from the power transmitting apparatus can be repeated
so as to be transmitted to the different power receiving apparatus
without consuming the power wastefully.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a diagrammatic view showing an example of a
configuration of a power receiving apparatus according to an
embodiment of the present invention;
[0046] FIG. 2 is a diagrammatic view showing an example of a power
transmission system which includes the power receiving apparatus of
FIG. 1;
[0047] FIG. 3 is a diagrammatic view showing an example of a
configuration of a power receiving apparatus according to another
embodiment of the present invention;
[0048] FIG. 4 is a flow chart illustrating processing operation of
the power receiving apparatus of FIG. 3;
[0049] FIGS. 5A and 5B are a diagrammatic view and a cross
sectional view, respectively, showing an example of a charging
system as a power transmission system according to a further
embodiment of the present invention;
[0050] FIG. 6 is a diagrammatic view showing an example of a
configuration of a charging system as a power transmission system
according to a still further embodiment of the present
invention;
[0051] FIG. 7 is a flow chart illustrating an example of processing
operation of a power transmitting apparatus in the charging system
of FIG. 6;
[0052] FIG. 8 is a flow chart illustrating an example of processing
operation of a power receiving apparatus in the charging system of
FIG. 6;
[0053] FIG. 9 is a diagrammatic view showing an example of a
configuration of a power transmission system of the magnetic field
resonance type;
[0054] FIGS. 10, 11 and 12 are diagrams illustrating
characteristics of the power transmission system of the magnetic
field resonance type shown in FIG. 9; and
[0055] FIG. 13 is a diagrammatic view illustrating a problem of an
existing power transmission system of the magnetic field resonance
type shown in FIG. 9.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0056] In the following, power receiving apparatus and power
transmission systems including the power receiving apparatus
according to preferred embodiments of the present invention are
described with reference to the accompanying drawings.
Power Receiving Apparatus According to the First Embodiment
[0057] FIG. 1 shows an example of a configuration of a power
receiving apparatus according to a first embodiment of the present
invention. Those parts shown in FIG. 1 which are identical to those
parts of the power receiving apparatus in the power transmission
system shown in FIG. 9 are denoted by identical reference
symbols.
[0058] Referring to FIG. 1, the power receiving apparatus 200
according to the first embodiment includes a resonance element 21,
an excitation element 22, a rectification circuit 23, a load 24,
and a power supply controlling switch 25 provided on a current path
between the excitation element 22 and the rectification circuit
23.
[0059] The resonance element 21 is formed, for example, from an
air-core coil in the form of a loop coil similarly to the resonance
element 11.
[0060] The excitation element 22 is formed, for example, from an
air-core coil, which is connected at a terminal thereof to one of
input terminals of the rectification circuit 23. The excitation
element 22 is connected at the other terminal of the air-core coil
thereof to the other one of the input terminals of the
rectification circuit 23 through the power supply controlling
switch 25.
[0061] The resonance element 21 and the excitation element 22 are
configured so as to have a relationship in which they are coupled
strongly to each other by electromagnetic induction.
[0062] The air-core coil of the resonance element 21 has not only
inductance but also coil internal capacitance and has a frequency
fo which depends upon the inductance and the capacitance. As
described hereinabove, the frequency fo of the resonance element 11
is equal to the self resonance frequency of the resonance element
11 of the power transmitting apparatus 10.
[0063] The power supply controlling switch 25 may be formed from a
mechanical switch which is manually operated by a user or a relay
switch or a semiconductor switch which switches on and off in
response to a predetermined operation by a user.
[0064] When the power supply controlling switch 25 is in an on or
closed state, the resonance element 21 in the power receiving
apparatus 200 is coupled to the resonance element 11 of the power
transmitting apparatus 10 through a magnetic field resonance
relationship therebetween, and similar operation to that described
above is carried out. In particular, induction current is induced
in the excitation element 22 by electromagnetic induction by ac
current appearing in the resonance element 21. The induction
current induced in the excitation element 22 is rectified into dc
current by the rectification circuit 23 and then supplied as power
supply current to the load 24.
[0065] On the other hand, when the power supply controlling switch
25 is in an off or open state, no current flows through the
excitation element 22. Accordingly, even if the resonance element
11 of the power transmitting apparatus 10 and the resonance element
21 of the power receiving apparatus 200 are coupled to each other
through the magnetic field resonance relationship therebetween and
ac current flows through the resonance element 21, no induction
current flows through the excitation element 22.
[0066] In other words, when the power supply controlling switch 25
is off, supply of ac current from the resonance element 21 to the
rectification circuit 23 is blocked.
[0067] Accordingly, when the power supply controlling switch 25 is
off, no dc current is supplied to the load 24 in the power
receiving apparatus 200, and no power is consumed in the power
receiving apparatus 200.
[0068] However, the resonance element 21 of the power receiving
apparatus 200 in which the power supply controlling switch 25 is
off in this manner can be coupled to the resonance element of a
different power receiving apparatus through a magnetic field
resonance relationship. Then, if such a different power receiving
apparatus as just mentioned exists, then ac magnetic field energy
transmitted to the resonance element 21 of the power receiving
apparatus 200 in which the power supply controlling switch 25 is
off is sent to the resonance element of the different power
receiving apparatus.
[0069] In other words, the resonance element 21 of the power
receiving apparatus 200 in which the power supply controlling
switch 25 is off acts as a repeater which transmits ac magnetic
field energy supplied thereto from the power transmitting apparatus
10 to the resonance element of the different power receiving
apparatus.
[0070] The state wherein the resonance element 21 acts as a
repeater is described more particularly with reference to FIG. 2
which shows a power transmission system according to an embodiment
of the present invention.
[0071] Referring to FIG. 2, in the power transmission system shown,
while power is supplied from the power transmitting apparatus 10 of
a power supplying source to a certain power receiving apparatus
200A, there exists a different power receiving apparatus 200B which
can be coupled to the power transmitting apparatus 10 through a
magnetic field resonance relationship.
[0072] In the power transmission system of FIG. 2, the power
receiving apparatus 200A and 200B have a configuration quite
similar to that of the power receiving apparatus 200 described
hereinabove and includes like components to those of the power
receiving apparatus 200. Such like components are denoted by like
reference symbols with the suffixes A and B added thereto,
respectively.
[0073] In the power transmission system of FIG. 2, it is shown that
the power receiving apparatus 200B which need not receive supply of
power is positioned nearer to the power transmitting apparatus 10
which serves as a power supplying source than the power receiving
apparatus 200A to which power is to be supplied and therefore has a
coupling amount to the power transmitting apparatus 10 greater than
that of the power receiving apparatus 200A.
[0074] Further, in the power transmission system of FIG. 2, the
power receiving apparatus 200A and the power receiving apparatus
200B have such a positional relationship to each other that they
are coupled to each other through a magnetic field resonance
relationship.
[0075] Further, in the power transmission system shown in FIG. 2,
the power supply controlling switch 25A of the power receiving
apparatus 200A is in an on or closed state in order that the power
receiving apparatus 200A may receive supply of power from the power
transmitting apparatus 10 of a power supply source. Meanwhile,
since the power receiving apparatus 200B need not receive supply of
power from the power transmitting apparatus 10, the power supply
controlling switch 25 is in an off or open state.
[0076] Accordingly, between the power transmitting apparatus 10 and
the power receiving apparatus 200A, the resonance elements 11 and
21A are coupled to each other through a magnetic field resonance
relationship, and since the power supply controlling switch 25A is
on, induction current flows through the excitation element 22A. The
induction current induced in the excitation element 22A is
rectified into dc current by the rectification circuit 23A and
supplied as power supply current to the load 24 not shown in FIG.
2.
[0077] In the meantime, between the power transmitting apparatus 10
and the power receiving apparatus 200B, the resonance elements 11
and 21B are coupled to each other through a magnetic field
resonance relationship. Consequently, ac magnetic field energy from
the power transmitting apparatus 10 is transmitted to the resonance
element 21B of the power receiving apparatus 200B. However, in the
power receiving apparatus 200B, since the power supply controlling
switch is in an off or open state, no induction current flows to
the excitation element 22B, and no current is supplied to the
rectification circuit 23B and no power is consumed.
[0078] Here, the power receiving apparatus 200A and the power
receiving apparatus 200B have such a positional relationship that
they are coupled to each other through a magnetic field resonance
relationship. Accordingly, ac magnetic field energy transmitted
from the power transmitting apparatus 10 to the resonance element
21B of the power receiving apparatus 200B is sent to the resonance
element 21A of the power receiving apparatus 200A.
[0079] In other words, in the power transmission system of FIG. 2,
part of the ac magnetic field energy sent out from the power
transmitting apparatus 10 is sent to the resonance element 21A of
the power receiving apparatus 200A through the resonance element
21B of the power receiving apparatus 200B.
[0080] In the power transmission system of FIG. 13, ac magnetic
field energy sent from the power transmitting apparatus 10 to the
power receiving apparatus 20B is consumed in the power receiving
apparatus 20B. However, in the power transmission system of FIG. 2,
such ac magnetic field energy is not consumed but is sent to the
power receiving apparatus 200A through the power receiving
apparatus 200B.
[0081] In this manner, the power receiving apparatus 200A receives
supply of power from the power transmitting apparatus 10 through
coupling by a direct magnetic field resonance relationship and
further receives supply of power through the power receiving
apparatus 200B. Accordingly, in the power transmission system of
FIG. 2, the power receiving apparatus 200A can receive all of the
ac magnetic field energy sent out from the power transmitting
apparatus 10. Consequently, the power receiving apparatus 200A can
receive supply of power efficiently.
[0082] It is to be noted that, since the power supply controlling
switch 25A in the power receiving apparatus 200A which is to
receive supply of power from the power transmitting apparatus 10 is
in an on state as can be seen from FIG. 2, the power receiving
apparatus 200A may have the configuration of the power receiving
apparatus 20 shown in FIG. 9 which does not include the power
supply controlling switch 25. In particular, in the power
transmission system of FIG. 2, all of the power receiving apparatus
may not include the configuration of the power receiving apparatus
200 of the present embodiment.
[0083] It is to be noted that, while, in the first embodiment
described above, the power supply controlling switch 25 is a
mechanical switch or a relay switch, the power supply controlling
switch 25 may otherwise have a configuration of a semiconductor
switch. In this instance, a controlling section formed, for
example, from a microcomputer for receiving an operation input of a
user is provided such that it controls the power supply controlling
switch 25 to switch in response to an operation input of the user
indicative of whether or not the power receiving apparatus should
be rendered operative. In particular, if the user inputs an
instruction operation for rendering the power receiving apparatus
operative, then the control section controls the power supply
controlling switch to an on state, but if the user inputs another
instruction operation for rendering the power receiving apparatus
inoperative, then the control section controls power supply
controlling switch to an off state.
Power Receiving Apparatus of the Second Embodiment
[0084] In the power receiving apparatus 200 of the first
embodiment, the power supply controlling switch is controlled to
switch only in response to an operation of the user. In contrast,
in the power receiving apparatus of the second embodiment, the
power supply controlling switch is automatically controlled to
switch.
[0085] FIG. 3 shows an example of a configuration of the power
receiving apparatus 300 of the second embodiment. The power
receiving apparatus 300 includes several common components to those
of the power receiving apparatus 200 of the first embodiment, and
overlapping description of the common components of the power
receiving apparatus 200 is omitted herein to avoid redundancy.
[0086] Referring to FIG. 3, the power receiving apparatus 300 shown
includes a battery 301B of the rechargeable type and further
includes a charging circuit 301 for charging the rechargeable
battery 301B, a power supply switch 302, a control section 303 and
an operation section 304.
[0087] The power receiving apparatus 300 further includes a power
supply controlling switch circuit 250 in place of the power supply
controlling switch 25. The power supply controlling switch circuit
250 is formed, for example, from a semiconductor switching
element.
[0088] In the present second embodiment, the power receiving
apparatus 300 receives radio power transmitted from the power
transmitting apparatus 10 and uses the radio power to charge the
battery 301B and then supplies power supply current to a load.
[0089] The charging circuit 301 charges the battery 301B with dc
current from the rectification circuit 23 when the power supply
controlling switch circuit 250 is on. In the power receiving
apparatus 300, the charging circuit 301 has a function of detecting
that the battery 301B is charged up and notifying the control
section 303 of such charge up.
[0090] The power supply switch 302 is interposed between an output
terminal of the rectification circuit 23 and the load 24 and
controlled between on and off in accordance with a switching signal
from the control section 303. Also this power supply switch 302 is
formed, for example, from a semiconductor switching element.
[0091] When the power supply controlling switch circuit 250 is on
and the power supply switch 302 is on, the power receiving
apparatus 300 receives radio power transmitted from the power
transmitting apparatus 10, and while the battery 301B is charged by
the charging circuit 301, the power receiving apparatus 300
supplies power also to the load 24.
[0092] The control section 303 includes, for example, a
microcomputer, and power is normally supplied from the battery 301B
to the control section 303.
[0093] The operation section 304 includes a power supply key and is
connected to the control section 303. If the operation section 304
receives an operation input information of the power supply key,
then it decides whether the operation input information represents
an operation to switch on the power supply or another operation to
switch off the power supply. Then, the control section 303 controls
the power supply switch 302 to an on state or an off state in
response to a result of the decision.
[0094] On the other hand, if the control section 303 receives a
notification from the charging circuit 301 that the charging
circuit 301B is charged up, then it switches off the power supply
controlling switch circuit 250. Accordingly, at this time, the
power receiving apparatus 300 does not consume ac magnetic field
energy sent thereto from the power transmitting apparatus 10, and
the resonance element 21 acts as a repeater of the ac magnetic
field energy as described hereinabove.
[0095] If the battery 301B is not charged up, then the control
section 303 controls the power supply controlling switch circuit
250 to an on state, and the power receiving apparatus 300 converts
ac magnetic field energy sent thereto from the power transmitting
apparatus 10 into dc current by means of the rectification circuit
thereof and then consumes the dc current.
[0096] FIG. 4 illustrates processing operation by the control
section 303 for controlling the power supply controlling switch
circuit 250 between on and off.
[0097] The control section 303 first checks a notification of
charge up from the charging circuit 301 at step S101. Then at step
S102, the control section 303 decides whether or not the battery
301B is in a charged up state at step S102. If it is decided that
the battery 301B is not in a charged up state, then the control
section 303 controls the power supply controlling switch circuit
250 to be kept on at step S103. Thereafter, the processing returns
to step S101.
[0098] On the other hand, if it is decided at step S102 that the
battery 301B is in a charged up state, then the control section 303
controls the power supply controlling switch circuit 250 to change
over to an off state at step S104. Thereafter, the processing
returns to step S101.
[0099] In the power receiving apparatus 300 of the present second
embodiment, when the battery 301B is in a charged up state, it need
not receive supply of power from the power transmitting apparatus
10, and consequently, the power supply controlling switch circuit
250 is switched off automatically.
[0100] Accordingly, with the power receiving apparatus 300 of the
present second embodiment, different from the power receiving
apparatus 200 of the first embodiment, even if the user does not
manually carry out a switching operation of the power supply
controlling switch, it is possible to prevent unnecessary
consumption of ac magnetic field energy and achieve efficient radio
power transmission.
[0101] Further, where all of a plurality of power receiving
apparatus which receive ac magnetic field energy from the power
transmitting apparatus 10 have the configuration of the power
receiving apparatus 300 of the second embodiment, the time before
all of the plural power receiving apparatus are placed into a fully
charged stage can be reduced.
[0102] In particular, where all of the batteries of the plural
power receiving apparatus 300 are not in a charged up state, ac
magnetic field energy from the power transmitting apparatus 10 is
distributed to the plural power receiving apparatus 300 to carry
out charging. However, in a power reception state wherein the
batteries are in a charged up state, the power supply controlling
switch circuit 250 is off and acts as a repeater for the ac
magnetic field energy. Therefore, the ac magnetic field energy to
be transmitted to a power receiving apparatus which has a battery
which is not in a charged up state as yet increases.
[0103] Consequently, since ac magnetic field energy from the power
transmitting apparatus 10 can be transmitted efficiently until all
of a plurality of power receiving apparatus are placed into a
charged up state, the time before all of the plural power receiving
apparatus are placed into a charged up state can be reduced.
Third Embodiment
Power Transmission System (Charging System)
[0104] In the present third embodiment, the present invention is
embodied as a charging system or charging apparatus for charging
the power receiving apparatus 300 of the second embodiment. FIGS.
5A and 5B show appearance of the charging system as a power
transmission system of the present third embodiment.
[0105] In the charging system of the present embodiment, a power
transmitting apparatus 10 is provided in the inside of a box-shaped
charging cradle, and a plurality of power receiving apparatus 300
are placed on the charging cradle.
[0106] FIG. 5A shows a top plan of a charging cradle 400 which
forms the charging system of the present embodiment, and FIG. 5B
shows a cross section taken along line X-X.
[0107] The charging cradle 400 is formed in a flattened box shape
made of a non-magnetic material. In the inside of the charging
cradle 400, the power transmitting apparatus 10 serving as a power
supplying source is disposed at a central position of the charging
cradle 400. A broken line shown in FIG. 5A indicates an air-core
coil which forms the resonance element 11 of the power transmitting
apparatus 10.
[0108] On a receiving face 400A of the charging cradle 400 which
receives a plurality of power receiving apparatus 300, a plurality
of marks MK each indicative of a position at which a power
receiving apparatus 300 is to be placed, in the example of FIG. 5A,
a plurality of circular marks, are provided, for example, by
printing.
[0109] As seen in FIGS. 5A and 5B, the marks MK are provided such
that the centers thereof are positioned on a circle at an equal
distance from the position of the center of the charging cradle 400
at which the power transmitting apparatus 10 is disposed. This is
because it is intended to make all of the coupling amounts through
a magnetic field resonance relationship between the plural power
receiving apparatus 300 placed on the charging cradle 400 and the
power transmitting apparatus 10 equal to each other.
[0110] In particular, in the present charging cradle 400, if a
power receiving apparatus 300 is placed at one of the plural marks
MK, then on whichever one of the plural marks MK the power
receiving apparatus 300 is placed, the power receiving apparatus
300 can receive ac magnetic field energy of an equal magnitude from
the power transmitting apparatus 10.
[0111] Further, if a plurality of power receiving apparatus 300 are
placed on the charging cradle 400, then ac magnetic field energy is
first distributed and supplied equally to all of the power
receiving apparatus 300 from the power transmitting apparatus
10.
[0112] Then, if the battery 301B of any of the power receiving
apparatus 300 is placed into a charged up state, then the resonance
element of the power receiving apparatus 300 now acts as a repeater
of the ac magnetic field energy as described hereinabove.
Accordingly, to any other power receiving apparatus 300 whose
battery 301B is not in a charged up state, ac magnetic field energy
is additionally transmitted through the repeater in addition to the
ac magnetic field energy originally supplied thereto from the power
transmitting apparatus 10.
[0113] In particular, the power receiving apparatus 300 whose
battery 301B is fully charged does not consume the ac magnetic
field energy being received till then but repeats the ac magnetic
field energy to the other power receiving apparatus 300 whose
battery 301B is not in a charged up state. Accordingly, the ac
magnetic field energy to be applied to the other power receiving
apparatus 300 whose battery 301B is not in a fully charged state
increases from that till then.
[0114] Therefore, with the charging system of the present
embodiment, it can charge a plurality of power receiving apparatus
efficiently.
Fourth Embodiment
Power Transmission System or Charging System
[0115] Also in the present fourth embodiment, the present invention
is applied to a charging system as an example of a power
transmission system similarly to the third embodiment.
[0116] Although the charging system of the present fourth
embodiment has a basic configuration which includes a charging
cradle similar to that in the third embodiment, it is different
from the third configuration in that each of a power transmitting
apparatus of a supplying source of charging power and a power
receiving apparatus for receiving the charging power include a
communication section.
[0117] In the present fourth embodiment, each power receiving
apparatus sends a residual charging amount of a battery to the
power transmitting apparatus.
[0118] The power transmitting apparatus produces a charging
schedule plan in response to the received residual charging amounts
of the plural power receiving apparatus and sends a controlling
instruction for placing the power supply controlling switch circuit
into an on state or an off state to each of the plural power
receiving apparatus in accordance with the charging schedule
plan.
[0119] Each of the power receiving apparatus executes an operation
to place the power supply controlling switch circuit thereof into
an on or off state in response to the controlling instruction from
the power transmitting apparatus.
[0120] Consequently, in the charging system of the present fourth
embodiment, the plural power receiving apparatus can be charged up
rapidly in appropriate charging time.
[0121] FIG. 6 shows an example of a configuration of the power
transmitting apparatus 100 and the power receiving apparatus 500
which form the charging system of the present fourth embodiment.
Those parts shown in FIG. 6 which are identical to those shown in
abovementioned embodiments are denoted by identical reference
symbols.
[0122] Referring to FIG. 6, the power transmitting apparatus 100
includes a control section 111 and a communication section 112 in
addition to a resonance element 11, an excitation element 12 and a
frequency signal generation section 13.
[0123] The control section 111 is configured including, for
example, a microcomputer and analyzes information received from the
power receiving apparatus 500 through the communication section 112
or produces and transmits transmission information to the power
receiving apparatus 500 through the communication section 112.
[0124] The communication section 112 is formed, for example, from a
Bluetooth unit or a ZigBee unit.
[0125] Further, similarly to the power receiving apparatus 300 of
the second embodiment, the power receiving apparatus 500 includes a
power supply controlling switch circuit 250, a charging circuit 301
for charging a battery 301B, a power supply switch 302, a control
section 303 and an operation section 304 and additionally includes
a communication section 501.
[0126] The charging circuit 301 notifies the control section 303 of
a residual charging amount or battery remaining amount of the
battery 301B and of a charged up state, a little different from
that in the second embodiment.
[0127] In the present fourth embodiment, the control section 303
transmits the residual charging amount or battery remaining amount
of the battery 301B received from the charging circuit 301 to the
power transmitting apparatus 100 through the communication section
501 together with identification information of the power receiving
apparatus 500 itself.
[0128] In the present fourth embodiment, it is possible for a user
to input additional information such as whether or not charging is
demanded urgently or charging may be carried out slowly through the
operation section 304.
[0129] Upon such notification of the residual charging amount, the
control section 303 additionally transmits the additional
information to the power transmitting apparatus 100.
[0130] Further, when the control section 303 receives a
notification representing that the battery 301B is charged up from
the charging circuit 301, it switches off the power supply
controlling switch circuit 250 and transmits a notification that
the battery 301B is charged up to the power transmitting apparatus
100 through the communication section 501 together with the
identification information of the power receiving apparatus 500
itself.
[0131] When the control section 111 of the power transmitting
apparatus 100 receives a notification of a residual charging amount
or a notification of full charge from the power receiving apparatus
500, then it produces or modifies a charging schedule plan. Then,
the control section 111 produces on/off controlling instructions
for the power supply controlling switch circuit to each of the
plural power receiving apparatus in accordance with the charging
schedule plan and then transmits the controlling instructions
through the communication section 112.
Processing Operation of the Control Section 111 of the Power
Transmission Apparatus 100
[0132] FIG. 7 is a flow chart illustrating processing operation
executed by the control section 111 of the power transmitting
apparatus 100.
[0133] The processing operation in FIG. 7 is carried out when
plural power receiving apparatus 500 as power supplying
destinations are placed on the charging cradle and the power supply
for the charging system is switched on to supply power to the power
transmitting apparatus 100.
[0134] The control section 111 receives a residual charging amount
and additional information to the residual charging amount from the
plural power receiving apparatus 500 which are power supplying
destinations at step S111 at the communication section 112.
[0135] Then, the control section 111 produces a charging schedule
plan for the plural power receiving apparatus 500 from the received
residual charging amounts and additional information at step
S112.
[0136] In particular, the control section 111 recognizes
identification information of each power receiving apparatus from
the received information and then checks the residual charging
amount, emergency for charging and so forth of each power receiving
apparatus. Then, the control section 111 produces an optimum
charging schedule plan based on the received information and
determines, in accordance with the charging schedule plan, which
power supply controlling switching circuit 250 is to be switched on
or off in the power receiving apparatus.
[0137] Then, the control section 111 transmits the determined
on/off controlling information for the power supply controlling
switching circuits 250 of the power receiving apparatus 500 to the
respective power receiving apparatus 500 in a matched relationship
with the identification information through the communication
section 212 at step S113.
[0138] Then, the control section 111 monitors reception of charge
up information from any power receiving apparatus 500 at step S114
and decides, if it is decided that such charge up information is
received, whether or not all of the power receiving apparatus 500
are charged up at step S115.
[0139] If it is decided at step S115 that not all of the power
receiving apparatus 500 are charged up, then the control section
111 decides whether or not the charging schedule plan need be
revised for those power receiving apparatus 500 which are not
charged up at step S116. In particular, since there possibly is a
case wherein, for example, while the battery is not charged up, the
power supply controlling switching circuit 250 in an off state need
be changed to an on state, the necessity for the change and so
forth is decided.
[0140] If it is decided at step S116 that the charging schedule
plan need not be revised, then the processing of the control
section 111 returns to step S114.
[0141] On the other hand, if it is decided at step S116 that the
charging schedule need be revised, then the control section 111
re-produces a charging schedule plan for the power receiving
apparatus other than the power receiving apparatus which is or are
charged up. Then, the control section 111 produces, in accordance
with the re-produced charging schedule plan, an on/off controlling
instruction for each of the power supply controlling switching
circuit 250 of the power receiving apparatus 500 other than those
power receiving apparatus 500 which is or are charged up and
transmits the on/off controlling instruction to the pertaining
power receiving apparatus 500 at step S117. Then, the processing
returns to step S114 to repetitively carry out the processes at the
steps beginning with step S114.
[0142] If it is decided at step S115 that all of the power
receiving apparatus 500 are charged up, then the control section
111 switches off the main power supply to the power transmitting
apparatus 100 and then ends the processing routine.
Processing Operation of the Control Section 303 of the Power
Receiving Apparatus 500
[0143] FIG. 8 illustrates processing operation to be executed by
the control section 303 of the power receiving apparatus 500.
[0144] The control section 303 transmits identification information
(ID) of the power transmitting apparatus 100 itself, a residual
charging amount and additional information to the power
transmitting apparatus 100 which is a power supplying source
through the communication section 501 at step S201.
[0145] Then, the control section 303 decides whether or not a
switching on or off instruction for the power supply controlling
switching circuit 250 from the power transmitting apparatus 100 is
received through the communication section 501 at step S202.
[0146] If it is decided at step S202 that such a switching on or
off instruction for the power supply controlling switching circuit
250 is not received, then the control section 303 repetitively
carries out the process at step S202.
[0147] On the other hand, if it is decided at step S202 that a
switching on or off instruction for the power supply controlling
switching circuit 250 is received, then the control section 303
controls switching on or off of the power supply controlling
switching circuit 250 in accordance with the received instruction
at step S203.
[0148] Then, the control section 303 decides at step S204 whether
or not the power supply controlling switching circuit 250 is off.
If it is decided that the power supply controlling switching
circuit 250 is off, then the processing returns to step S202 to
repetitively carry out the processes at the steps beginning with
step S202.
[0149] On the other hand, if it is decided at step S204 that the
power supply controlling switching circuit 250 is not off, then the
control section 303 decides whether or not the battery 301B is
charged up at step S205.
[0150] If it is decided at step S205 that the battery 301B is not
charged up, then the processing of the control section 303 returns
to step S202 to repetitively carry out the processes at the steps
beginning with step S202.
[0151] On the other hand, if it is decided at step S205 that the
battery 301B is charged up, then the control section 303 transmits
charge up information together with the ID of the power receiving
apparatus 500 itself to the power transmitting apparatus 100 which
is a power supplying source through the communication section 501
at step S206.
[0152] Further, the control section 303 changes over the power
supply controlling switching circuit 250 to an off state at step
S207 and then ends the processing routine.
Other Embodiments and Modifications
[0153] It is to be noted that, in the description of the
embodiments given above, only a case is described wherein the power
receiving apparatus 200 in which the power supply controlling
switch is in an off state repeats ac magnetic field energy from the
power transmitting apparatus 10 to a different power receiving
apparatus. However, in a situation wherein the power supply
controlling switch is in an off state in a plurality of power
receiving apparatus 200, it sometimes occurs that a power receiving
apparatus transmits alternating current magnetic field energy
transmitted thereto from a different power receiving apparatus
which operates as a repeating apparatus to a further different
power receiving apparatus.
[0154] Further, although a case is described wherein the power
transmission system of the fourth embodiment described above is a
charging system, the present embodiment is not limited to this. For
example, each of the plural power receiving apparatus may not
include a rechargeable battery but may include a function for
issuing a notification regarding whether or not the power receiving
apparatus itself need operate to the power transmitting apparatus.
On the other hand, the power transmitting apparatus may include a
function for issuing an instruction for on/off control of the power
supply controlling switching circuit of the power receiving
apparatus based on the notification.
[0155] With such a power transmission system as just described, the
power transmitting apparatus monitors the information regarding
whether or not the power transmitting apparatus need operate from
the power receiving apparatus and issues an instruction for on/off
control of the power supply controlling switching circuit so that
suitable power supply can be usually carried out for any power
receiving apparatus for which power supply is demanded.
[0156] Further, while, in the embodiments described above, the
excitation element 22 is provided between the resonance element 21
and the rectification circuit 23 so that impedance conversion is
carried out to carry out effective ac power transmission, the
excitation element may be omitted.
[0157] In particular, while, in this instance, both terminals of
the resonance element 21 are connected to one and the other one of
the input terminal of the rectification circuit 23, in the present
embodiment, the power supply controlling switch is provided between
one of both terminals of the resonance element 21 and one of the
input terminals of the rectification circuit 23.
[0158] Further, the power supply controlling switch in this
instance is changed over to a state wherein ac current from the
resonance element 21 is supplied to the rectification circuit 23
when supply of the power from the power transmitting apparatus is
received by the power receiving apparatus. Further, when supply of
the ac current from the resonance element 21 to the rectification
circuit 23 is to be blocked, the power supply controlling switch
cuts off the connection between one of the terminals of the
resonance element 21 and one of the input terminals of the
rectification circuit 23 and changes over so that both terminals of
the resonance element 21 are connected to each other to form a loop
coil. Consequently, the resonance element 21 is placed into a state
wherein it can carry out magnetic field resonance coupling with a
different resonance element.
[0159] It is to be noted that, while a case wherein a resonance
relationship between resonance elements is magnetic field resonance
is described in the description of the embodiments, the present
invention can be applied also to electric field resonance.
[0160] The present application contains subject matter related to
that disclosed in Japanese Priority Patent Application JP
2009-170805 filed in the Japan Patent Office on Jul. 22, 2009, the
entire content of which is hereby incorporated by reference.
[0161] It should be understood by those skilled in the art that
various modifications, combinations, sub-combinations and
alterations may occur depending on design requirements and other
factors insofar as they are within the scope of the appended claims
or the equivalents thereof.
* * * * *