(12) United States Patent
`Sawa et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 9.443,648 B2
`Sep. 13, 2016
`
`USOO9443648B2
`
`(54) MAGNETIC SHEET FOR NON-CONTACT
`POWER RECEIVING DEVICE,
`NON-CONTACT POWER RECEIVING
`DEVICE, ELECTRONIC APPARATUS, AND
`NON-CONTACT CHARGER
`
`(56)
`
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`4,368,496 A *
`
`1/1983 Kato ...................... G11B 5,105
`360/110
`5,821,731 A * 10/1998 Kuki ................... B6OL 11, 1805
`320, 108
`
`8, 193,767 B2
`8,232,764 B2
`2009/00583.58 A1
`2009/O121677 A1
`2009/02O6791 A1*
`
`6/2012 Inoue et al.
`7/2012 Inoue et al.
`3/2009 Inoue et al.
`5/2009 Inoue et al.
`8/2009 Jung ....................... HO2J 7,025
`320, 108
`
`2009,0284341 A1
`2010.0156344 A1
`2010, 0181842 A1
`2013,02931.91 A1
`
`11/2009 Okada et al.
`6/2010 Inoue et al.
`7/2010 Suzuki et al.
`11/2013 Hidaka et al.
`
`FOREIGN PATENT DOCUMENTS
`
`7/1997
`O9-190938 A
`JP
`9, 1999
`11-265814 A
`JP
`1, 2000
`2000-023393 A
`JP
`1, 2009
`2009-005475 A
`JP
`2009-277820. A 11/2009
`JP
`2010-283263. A 12/2010
`JP
`2012-156280 A
`8, 2012
`JP
`WO WO 2007/080820 A1
`7/2007
`WO WO 2007/111019 A1 10/2007
`WO WO 2007/122788 A1 11, 2007
`
`OTHER PUBLICATIONS
`
`System Description Wireless Power Transfer, Volume I: Low
`Power, Part 1: Interface Definition, Version 1.0.1. Oct. 2010, pp.
`1-76.
`
`* cited by examiner
`
`Primary Examiner — Arun Williams
`(74) Attorney, Agent, or Firm — Foley & Lardner LLP
`
`(57)
`
`ABSTRACT
`
`A magnetic sheet of an embodiment includes a laminate of
`a plurality of magnetic thin plates. The laminate constituting
`the magnetic sheet includes a first magnetic thin plate and a
`second magnetic thin plate different in kind from the first
`magnetic thin plate. The first magnetic thin plate has a
`magnetostriction constant exceeding 5 ppm in an absolute
`value, and the second magnetic thin plate has a magneto
`striction constant of 5 ppm or less in an absolute value.
`Alternatively, the first magnetic thin plate has a thickness of
`from 50 to 300 um, and the second magnetic thin plate has
`a thickness of from 10 to 30 um.
`
`13 Claims, 9 Drawing Sheets
`
`(71) Applicants: KABUSHIKI KAISHA TOSHIBA,
`Tokyo (JP); TOSHIBA MATERLALS
`CO., LTD., Yokohama-shi, Kanagawa
`(JP)
`(72) Inventors: Takao Sawa, Yokohama (JP);
`Katsuhiko Yamada, Yokohama (JP);
`Tadao Saito, Yokohama (JP); Kiyoshi
`Nagasaki, Yokohama (JP)
`(73) Assignees: KABUSHIKI KAISHA TOSHIBA,
`Minato-Ku (JP); TOSHIBA
`MATERIALS CO., LTD.,
`Yokohama-Shi (JP)
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 198 days.
`(21) Appl. No.: 14/271,780
`(22) Filed:
`May 7, 2014
`(65)
`Prior Publication Data
`US 2014/023.9892 A1
`Aug. 28, 2014
`Related U.S. Application Data
`(63) Continuation
`of
`application
`PCT/JP2012/007133, filed on Nov. 7, 2012.
`Foreign Application Priority Data
`
`(*) Notice:
`
`(30)
`
`No.
`
`Nov. 8, 2011
`
`(JP) ................................. 2011-24.4955
`
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2006.01)
`(2016.01)
`(2006.01)
`(2006.01)
`(2006.01)
`
`(51) Int. Cl.
`H02. 700
`HOIF 7/02
`HOIF 38/4
`HOIF 3/02
`HOIF 27/245
`H02. 702
`HOIF 3/10
`HOIF 27/36
`HOIF I 7/00
`(52) U.S. Cl.
`CPC .............. H0IF 7/0247 (2013.01); H01F3/02
`(2013.01); H0IF 3/10 (2013.01); HOIF
`27/245 (2013.01); H01F 27/365 (2013.01);
`H0IF 38/14 (2013.01); H02J 7/0042
`(2013.01); H02J 7/025 (2013.01); HOIF
`2017/0066 (2013.01); Y10T 428/24314
`(2015.01); Y10T 428/24942 (2015.01); Y10T
`428/24967 (2015.01); Y10T 428/31678
`(2015.04)
`
`(58) Field of Classification Search
`CPC ...... H02J 7/025; H01F 38/14: YO2T 90/122;
`B60L 11/182; Y02E 60/12
`USPC .......................................................... 32Of 108
`See application file for complete search history.
`
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`U.S. Patent
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`Sep. 13, 2016
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`Sheet 1 of 9
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`US 9,443,648 B2
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`F.G. 1
`
`1
`
`Y
`
`Z24227.72222227 N
`
`FIG 2
`
`N YZ212227.2777
`2A
`N ZZZY ZO2 a YZZYZZYYYYYYYYaa
`
`
`
`2B
`
`Yi Ya Ya YaYamam ZZYYYYZZaaaaaa
`
`FIG 3
`
`2.
`
`N
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`SSSSSSSSSSSS-2A
`NSNNNNNNN
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`
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`
`
`
`
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`FIG. 4
`
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`
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`U.S. Patent
`U.S. Patent
`
`Sep. 13, 2016
`
`Sheet 3 of 9
`
`US 9,443,648 B2
`US 9,443,648 B2
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`F.G. 5
`FIG. 5
`
`
`
`3
`
`2(4)
`
`B1
`
`B2
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`B3
`
`B4
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`
`
`
`
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`
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`Ex.1008
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`U.S. Patent
`U.S. Patent
`
`Sep. 13, 2016
`Sep. 13, 2016
`
`Sheet 4 of 9
`Sheet 4 of 9
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`US 9.443,648 B2
`US 9,443,648 B2
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`F.G. 6
`FIG. 6
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`U.S. Patent
`
`Sep. 13, 2016
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`Sheet 5 Of 9
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`US 9,443,648 B2
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`FIG. 7
`
`6
`
`2(4)
`
`FIG. 8
`
`N-1
`-N
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`U.S. Patent
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`Sep. 13, 2016
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`Sheet 6 of 9
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`US 9,443,648 B2
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`FIG. 9
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`U.S. Patent
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`Sep. 13, 2016
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`Sheet 7 Of 9
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`US 9,443,648 B2
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`FIG 10
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`
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`12
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`U.S. Patent
`U.S. Patent
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`Sep. 13, 2016
`Sep. 13, 2016
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`Sheet 8 of 9
`Sheet 8 of 9
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`US 9,443,648 B2
`US 9,443,648 B2
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`FIG.
`
`11
`
`
`
`14
`
`10
`vo
`
`13
`
`.
`
`42
`
`J
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`aana
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`18
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`16
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`17a
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`- 11
`Lay
`
`a
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`Ex.1008
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`U.S. Patent
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`Sep. 13, 2016
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`Sheet 9 of 9
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`US 9,443,648 B2
`
`FIG. 12
`
`&S N D-3 n1n D.C.
`
`1 O
`
`aZZZZZZZZZZZYZZZZZYZZZZYZ
`
`
`
`
`
`
`
`
`
`
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`Ex.1008
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`US 9,443,648 B2
`
`1.
`MAGNETIC SHEET FOR NON-CONTACT
`POWER RECEIVING DEVICE,
`NON-CONTACT POWER RECEIVING
`DEVICE, ELECTRONIC APPARATUS, AND
`NON-CONTACT CHARGER
`
`CROSS-REFERENCE TO RELATED
`APPLICATIONS
`
`This application is a continuation of prior International
`Application No. PCT/JP2012/007133 filed on Nov. 7, 2012,
`which is based upon and claims the benefit of priority from
`Japanese Patent Application No. 2011-244955 filed on Nov.
`8, 2011; the entire contents of all of which are incorporated
`herein by reference.
`
`10
`
`15
`
`FIELD
`
`Embodiments described herein relate generally to a mag
`netic sheet for non-contact power receiving device, and a
`non-contact power receiving device, an electronic device,
`and a non-contact charger.
`
`BACKGROUND
`
`2
`amorphous powder is mixed, and so on. However, ferrite,
`becoming fragile if processed to be thin, has a problem of
`being weak in impact resistance and being apt to cause a
`defect in a power receiving device by dropping or the like of
`the apparatus.
`In order to make a power receiving portion thinner to cope
`with decrease in thickness of an apparatus, it is studied to
`adopt a flat coil formed by printing a metal powder paste
`spirally on a Substrate. However, a magnetic flux passing
`through the flat coil interlinks a substrate or the like inside
`the apparatus, there is a problem that an eddy current
`generated by electromagnetic induction causes heat genera
`tion in the apparatus. Thus, a large power cannot be trans
`mitted and a charging time becomes long. Concretely, while
`it takes about 90 minutes for a contact charger to charge a
`cellular phone, it takes about 120 minutes for a non-contact
`charger to charge.
`In a power receiving device to which a conventional
`non-contact charging method is applied, a measure against
`an eddy current generated by electromagnetic induction is
`not sufficient. Since the power receiving device has a
`secondary battery, it is required to Suppress generation of
`heat to the utmost. Since the power receiving device is
`mounted on an electronic apparatus main body, generation
`of heat has a negative effect to a circuit component. Due to
`the above, a large power cannot be transmitted at a time of
`charging and a charging time becomes long. Further, gen
`eration of an eddy current leads to generation of a noise,
`which causes reduction of a charging efficiency. It is Sug
`gested, as a measure against the above, to provide a mag
`netic thin plate in a predetermined position of the power
`receiving device. By controlling a magnetic permeability
`and a plate thickness of the magnetic thin plate, or a
`saturation magnetic flux density and a plate thickness of the
`magnetic thin plate, heat generation by the eddy current,
`generation of the noise, reduction of the power receiving
`efficiency, and so on are Suppressed.
`A non-contact charging method is suggested in which a
`magnet is disposed in a power feeding side of a non-contact
`charger and positioning of an apparatus of a power receiving
`side is carried out. For example, in WPC (Wireless Power
`Consortium) being an international standard, a non-contact
`charger in which positioning is carried out by a magnet is
`described in "System Description Wireless Power Transfer,
`volume 1: Low Power Part 1: interface Definition version
`1.0, July, 2010”.
`When positioning is carried out by a magnet, magnetic
`saturation occurs in a conventional magnetic thin plate and
`a magnetic shield effect is substantially reduced. Thus, there
`is an apprehension that temperature rise of a secondary
`battery is brought about at a time of charging and that a cycle
`life time of the secondary battery is reduced. A conventional
`magnetic shield has a magnetic thin plate with a saturation
`magnetic flux density of 0.55 to 2 T (5.5 to 20 kG), for
`example, and Such (a) magnetic thin plate (s), in a range of
`one to three or less, is (are) laminated. Even if a laminate of
`the magnetic thin plates is used as magnetic shield, there is
`a possibility that a magnetic field generated from a magnet
`disposed in a power feeding device easily causes magnetic
`saturation of the magnetic shied, a function as the magnetic
`shield not being exhibited.
`In a present international standard of the non-contact
`charging method, there are a method of using a magnet and
`a method of not using a magnet in positioning of an
`apparatus in a power receiving side. Since a magnetic thin
`plate used in the conventional magnetic shield is excellent in
`Soft magnetic characteristic, use of a laminate in a range of
`
`25
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`30
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`35
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`40
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`45
`
`50
`
`A portable communication device has developed remark
`ably in recent years, and especially a cellular phone is being
`rapidly reduced in size, weight, and thickness. Other than the
`cellular phone, an electronic apparatus Such as a video
`camera (handy camera or the like), a codeless telephone, or
`a lap-top personal computer (note type personal computer),
`is being reduced in size, weight, and thickness. The above
`can be used without being connected to a plug as a result that
`a secondary battery is mounted on an electronic apparatus
`main body, which increases portability and convenience. At
`present, the secondary battery is limited in capacity and it is
`necessary for the secondary battery to be charged once in
`several days to several weeks.
`As a charging method, there are a contact charging
`method and a non-contact charging method. The contact
`charging method is a method in which an electrode of a
`power receiving device and an electrode of a power feeding
`device are made to contact directly and charging is per
`formed. The contact charging method is generally used since
`its device structure is simple. However, as the electronic
`apparatus is reduced in size, weight, and thickness in recent
`years, the weight of the electronic apparatus becomes
`smaller, so that a contact pressure between the electrode of
`the power receiving device and the electrode of the power
`feeding device becomes insufficient, causing a problem that
`a charging defect occurs. Further, since the secondary bat
`tery is weak against heat, it is necessary to design a circuit
`so that excessive discharging or excessive charging does not
`occur, to prevent temperature rise of the battery. In view of
`the above, application of the non-contact charging method is
`55
`being studied.
`The non-contact charging method is a method in which
`both a power receiving device and a power feeding device
`are provided with coils and charging is performed by using
`electromagnetic induction. In the non-contact charging
`method, since it is not necessary to consider a contact
`pressure between electrodes, a charging Voltage can be
`supplied stably without being influenced by a state of
`contact between the electrodes. As the coil for the non
`contact charger, there are known a structure in which a coil
`is wound around a ferrite core, a structure in which a coil is
`mounted on a resin substrate where a ferrite powder or an
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`US 9,443,648 B2
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`3
`one or three or less magnetic thin plate(s) with a Saturation
`magnetic flux density of 0.55 to 2 T causes magnetic
`saturation easily, if a magnet exists in the neighborhood.
`Under the circumstances, a magnetic sheet for non-contact
`power receiving device is desired which enables a sufficient
`magnetic shield effect and a high charging efficiency inde
`pendently of existence/absence of a magnet in a power
`feeding device side.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`10
`
`4
`as long as two or more kinds are used, but it is preferable that
`four kinds or less, further, three kinds or less are used when
`a manufacturability including procurement of the compos
`ing materials (raw materials) is considered.
`FIG. 1 shows a magnetic sheet for non-contact power
`receiving device of a first embodiment. FIG. 2 shows a
`magnetic sheet for non-contact power receiving device of a
`second embodiment. FIG. 3 shows a magnetic sheet for
`non-contact power receiving device of a third embodiment.
`In those drawings, a reference numeral 1 indicates a mag
`netic sheet for non-contact power receiving device, a refer
`ence numeral 2 indicates a first magnetic thin plate, a
`reference numeral 3 indicates an adhesive layer portion, and
`a reference numeral 4 indicates a second magnetic thin plate
`different in kind from the first magnetic thin plate 2. It is
`preferable that the first magnetic thin plate 2 is a magnetic
`thin plate which is hard to be magnetic-saturated even if a
`magnet exists in a power feeding device side. It is preferable
`that the second magnetic thin plate 4 is a magnetic thin plate
`capable of obtaining a high magnetic permeability at a used
`frequency of a power receiving device. As a result of
`disposing in an electronic apparatus the magnetic sheet 1
`made by laminating the first magnetic thin plate 2 which is
`hard to be magnetic-saturated and the second magnetic thin
`plate 4 having the high magnetic permeability, heat genera
`tion, generation of a noise, reduction of a power receiving
`efficiency or the like can be suppressed regardless of exis
`tence/absence of positioning by a magnet in the power
`feeding device side in a non-contact charger.
`The adhesive layer portion 3 is provided between the first
`magnetic thin plate 2 and the second magnetic thin plate 4.
`The adhesive layer portion 3 is preferable to be provided at
`least between the first magnetic thin plate 2 and the second
`magnetic thin plate 4. As the adhesive layer portion 3, there
`can be cited a resin film having adherence or an adhesive
`agent or the like. The adhesive layer portion 3 is not limited
`in particular as long as the adhesive layer portion 3 can fix
`the magnetic thin plates 2, 4. As concrete examples of the
`resin film, there can be cited a polyethylene terephthalate
`(PET) film, a polyester film, a polyimide (PI) film, a
`polyphenylene sulfide (PPS) film, a polypropylene (PP)
`film, a polytetrafluoroethylene (PTFE) film, and so on. As
`concrete examples of the adhesive agent, there can be cited
`an epoxy system adhesive agent, a silicone system adhesive
`agent, an acryl System adhesive agent, and so on.
`As will be described later, when incision portions are
`provided in the magnetic thin plates 2, 4, it is preferable to
`provide the adhesive layer portion 3 between the respective
`magnetic thin plates since there is a possibility that a
`positional displacement of the incision portion occurs. A
`thickness of the adhesive layer portion 3 is preferable to be
`100 um or less, and further, is more preferable to be 50 um
`or less. By making the adhesive layer portion 3 thin, an
`entire thickness of the magnetic sheet 1 can be made Small.
`A lower limit value of the thickness of the adhesive layer
`portion 3 is not limited in particular, but is preferable to be
`5um or more in order to make the adherence uniform. In a
`case of an electronic apparatus required to be made thinner
`Such as a cellular phone, a thickness of the magnetic sheet
`1, including a resin film covering an external appearance, is
`preferable to be 1 mm or less, is more preferable to be 0.8
`mm or less, and further, is desirable to be 0.6 mm or less.
`Alaminate constituting the magnetic sheet 1 can have, as
`shown in FIG. 2, a plurality of first magnetic thin plates 2A,
`2B and a plurality of second magnetic thin plates 4A, 4B.
`Further, as shown FIG. 3, a laminate can have a plurality of
`first magnetic thin plates 2A, 2B and one second magnetic
`
`Fig. is a cross-sectional view showing a magnetic sheet of
`a first embodiment.
`FIG. 2 is a cross-sectional view showing a magnetic sheet
`of a second embodiment.
`FIG. 3 is a cross-sectional view showing a magnetic sheet
`of a third embodiment.
`FIG. 4 is a plan view showing a first example of an
`incision portion of a magnetic thin plate in the magnetic
`sheet of the embodiment and a measurement example of an
`outer periphery length A of the magnetic thin plate.
`FIG. 5 is a plan view showing a measurement example of
`a total length B of the incision portion of the magnetic thin
`plate in the magnetic sheet of the embodiment.
`FIG. 6 is a plan view showing a second example of the
`incision portion of the magnetic thin plate in the magnetic
`sheet of the embodiment.
`FIG. 7 is a plan view showing a third example of the
`incision portion of the magnetic thin plate in the magnetic
`sheet of the embodiment.
`FIG. 8 is a plan view showing a fourth example of the
`incision portion of the magnetic thin plate in the magnetic
`sheet of the embodiment.
`FIG. 9 is a plan view showing a fifth example of the
`incision portion of the magnetic thin plate in the magnetic
`sheet of the embodiment.
`FIG. 10 is a view showing a schematic configuration of an
`electronic apparatus according to the first embodiment.
`FIG. 11 is a view showing a schematic configuration of an
`electronic apparatus according to the second embodiment.
`FIG. 12 is a view showing a schematic configuration of a
`non-contact charger according to the embodiment.
`
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`DETAILED DESCRIPTION
`
`50
`
`45
`According to one embodiment, there is provided a mag
`netic sheet for non-contact power receiving device. The
`magnetic sheet includes a laminate of a plurality of magnetic
`thin plates. The laminate in the magnetic sheet has two or
`more kinds of the magnetic thin plates.
`Hereinafter, a magnetic sheet for non-contact power
`receiving device according to an embodiment and a non
`contact power receiving device, an electronic apparatus, and
`a non-contact charger which use the same will be described.
`The magnetic sheet for non-contact power receiving
`device of the embodiment includes a laminate of a plurality
`of magnetic thin plates. The laminate constituting the mag
`netic sheet includes two or more kinds of magnetic thin
`plates. In other words, the laminate includes at least a first
`magnetic thin plate and a second magnetic thin plate differ
`ent in kind from the first magnetic thin plate. The different
`in kind means that magnetic characteristic Such as a mag
`netostriction constant, thickness, composing material, or the
`like of the magnetic thin plate are different. The laminate can
`include a third or more magnetic thin plate(s) different in
`kind from the first and the second magnetic thin plates. The
`kinds of the magnetic thin plates are not limited in particular
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`thin plate 4. Alaminate can have one first magnetic thin plate
`2 and a plurality of second magnetic thin plates 4 in contrast
`to FIG. 3. The number of each of the magnetic thin plates 2.
`4 is preferable to be in a range of one to four. The magnetic
`sheets 1 shown in FIG. 2 and FIG.3 have structures in which
`the adhesive layer portions 3 are provided between the
`respective magnetic thin plates 2, 4.
`The magnetic sheet 1 shown in FIG. 3 has a structure in
`which the laminate of two first magnetic thin plates 2A, 2B
`and one second magnetic thin plate 4 is covered by a resin
`film 5. If the magnetic thin plates 2, 4 are affected by
`corrosion Such as rust, covering the entire laminate of the
`magnetic thin plates 2, 4 by the resin film 5 is effective. If
`it is necessary for the magnetic thin plates 2, 4 to be
`electrically insulated, the resin film 5 covering the entire
`laminate is effective. If the entire laminate is covered by the
`resin film 5 as in the magnetic sheet 1 shown in FIG. 3, it is
`not necessary to provide an adhesive layer portion 3 between
`the magnetic thin plates of the same kind, for example,
`between the magnetic thin plate 2A and the magnetic thin
`plate 2B. As concrete examples of the resin film 5, there can
`be cited a PET film, a PI film, a PPS film, a PP film, a PTFE
`film, and so on.
`As a first concrete example of the magnetic sheet 1, there
`can be cited a laminate of a first magnetic thin plate 2 having
`a magnetostriction constant exceeding 5 ppm in an absolute
`value and a second magnetic thin plate 4 having a magne
`tostriction constant of 5 ppm or less in an absolute value.
`The magnetostriction constant can be measured by a strain
`gauge method. A range of the magnetostriction constant of
`5 ppm or less in the absolute value indicates a range
`(including Zero) from -5 ppm to +5 ppm. A range of the
`magnetostriction constant exceeding 5 ppm indicates a range
`of less than -5 ppm or exceeding +5 ppm. A magnetostric
`tion indicates a rate of expansion or contraction of a mag
`35
`netic Substance in a magnetic field direction at a time that the
`magnetic Substance is magnetized by an external magnetic
`field. When the magnetostriction of the magnetic Substance
`is large, magnetic anisotropy is induced by an interaction
`between the magnetostriction and a stress, so that magnetic
`saturation is hard to occur.
`The first magnetic thin plate 2 whose magnetostriction
`constant exceeds 5 ppm in the absolute value is hard to be
`magnetically influenced even in a case of being disposed in
`a power feeding device side. In other words, the first
`magnetic thin plate 2 whose magnetostriction constant
`exceeds 5 ppm in the absolute value is hard to be magnetic
`saturated in a magnetic field brought by a magnet disposed
`in a power feeding device side, because of an interaction
`between a stress having been generated at a time of rolling
`in advance and the magnetostriction. Therefore, an L value
`(inductance value) necessary as the magnetic sheet 1 can be
`obtained. The second magnetic thin plate 4 whose magne
`tostriction constant is 5 ppm or less in the absolute value
`exhibits a high magnetic permeability when a magnet is not
`disposed in a power feeding device side. Therefore, accord
`ing to the magnetic sheet 1 having the laminate of the first
`magnetic thin plate 2 and the second magnetic thin plate 4.
`a good magnetic shield effect can be obtained in either a
`non-contact charging method in which a magnet is disposed
`in a power feeding device side or a non-contact charging
`method in which a magnet is not disposed in a power feeding
`device side.
`The difficulty of being magnetic-saturated based on the
`interaction between the magnetostriction and the stress can
`be obtained effectively when the absolute value of the
`magnetostriction constant exceeds 5 ppm. Therefore, the
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`first magnetic thin plate 2 is preferable to have a magneto
`striction constant exceeding 5 ppm in an absolute value.
`However, if the absolute value of the magnetostriction
`constant exceeds 50 ppm, there is a possibility that a
`magnetic anisotropy obtained by the interaction with the
`stress becomes too large to obtain a Sufficient L value.
`Therefore, it is preferable that the absolute value of the
`magnetostriction constant of the first magnetic thin plate 2 is
`in a range exceeding 5 ppm to 50 ppm or less. The absolute
`value of the magnetostriction constant of the second mag
`netic thin plate 4 is preferable to be 5 ppm or less in order
`to obtain a high magnetic permeability, and further, is more
`preferable to be 2 ppm or less. The magnetostriction con
`stant of the second magnetic thin plate 4 can be Zero.
`In the first concrete example of the magnetic sheet 1, the
`first magnetic thin plate 2 is preferable to have a thickness
`in a range of 50 to 300 Lum. The second magnetic thin plate
`4 is preferable to have a thickness in a range of 10 to 30 um.
`Further, the first magnetic thin plate 2 is preferable to have
`an electric resistance value of 80 LG2 cm or more and a
`saturation magnetic flux density in a range of 1 T (10 kG) or
`more to 2.1 T (21 kG) or less. The second magnetic thin plate
`4 is also preferable to have an electric resistance value of 80
`LG2 cm or more. Constitutional conditions of the first and the
`second magnetic thin plates 2, 4 will be described in detail
`in a second concrete example.
`As the second concrete example of the magnetic sheet 1.
`there can be cited a laminate of a first magnetic thin plate 2
`having a thickness (plate thickness) in a range of 50 to 300
`um and a second magnetic thin plate 4 having a thickness
`(plate thickness) in a range of 10 to 30 Jum. A magnetostric
`tion constant of the first magnetic thin plate 2 is preferable
`to exceed 5 ppm in an absolute value. If the thickness of the
`first magnetic thin plate 2 is less than 50 um, a stress
`generated by rolling becomes too large as will be described
`later, and a magnetic anisotropy obtained by an interaction
`with a magnetostriction becomes too large. Thus, there is a
`possibility that a sufficient L value cannot be obtained. The
`magnetostriction constant of the first magnetic thin plate 2 is
`preferable to be 50 ppm or less in an absolute value. If the
`thickness of the first magnetic thin plate 2 exceeds 300 um,
`an L value and a Q value at 100 kHz or more are reduced.
`The thickness of the first magnetic thin plate 2 is preferable
`to be in a range of 80 to 250 um. The thickness of the first
`magnetic thin plate 2 can be obtained by a later-described
`weighing method, or can be measured by a micrometer.
`When the thickness of the magnetic thin plate 2 is measured
`by the micrometer, the thickness is indicated by an average
`value of measured values of arbitrary three points.
`The magnetic sheet 1 of the embodiment can be used as
`a magnetic shield for a non-contact power receiving device,
`regardless of existence/absence of a magnet in a power
`feeding device side. The magnetic sheet 1 has a structure in
`which the first magnetic thin plate 2 hard to be magnetic
`saturated when a magnet is disposed in a power feeding
`device side and a second magnetic thin plate 4 exhibiting a
`high magnetic permeability at a used frequency when a
`magnet is not disposed are laminated. However, there is a
`case where an inductance of the second magnetic thin plate
`4 is not materialized as it is despite the fact that a magnet is
`not disposed in a power feeding device side, so that only an
`inductance value reduced by about 15 to 30% is obtained as
`the magnetic sheet 1. The above is considered to be influ
`enced by an electric resistance value of the first magnetic
`thin plate 2 hard to be magnetic-saturated. A cause thereof
`is not obvious, but is assumed to be as below.
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`7
`If the electric resistance value of the first magnetic thin
`plate 2 is low, an eddy current loss becomes large, reducing
`a Q value. Concurrent therewith, the integrated second
`magnetic thin plate 4 made of a high magnetic permeability
`material is also influenced by the first magnetic thin plate 2,
`and it is considered that consequently an inductance value of
`the magnetic sheet 1 is reduced. Thus, the first magnetic thin
`plate 2 is preferable to have an electric resistance value of 80
`LG2 cm or more. If the electric resistance value of the first
`magnetic thin plate 2 is 80 LG2 cm or more, increase of the
`eddy current loss or reduction of the Q value thereby can be
`Suppressed. Therefore, it is possible to make the inductance
`of the second magnetic thin plate 4 exhibited effectively. The
`electric resistance value of the first magnetic thin plate 2 is
`preferable to be 100 LG2 cm or more. Further, the electric
`resistance value of the second magnetic thin plate 4 is also
`preferable to be 80 LC2 cm, and is more preferable to be 100
`LG2 cm or more.
`In order to Suppress magnetic Saturation of the first
`magnetic thin plate 2, it is preferable that the first magnetic
`thin plate 2 has a large magnetostriction constant and a
`saturation magnetic flux density of 1 T (10 kG) or more. By
`setting the Saturation magnetic flux density of the first
`magnetic thin plate 2 to be 1 T or more, magnetic Saturation
`of the first magnetic thin plate 2 can be suppressed more
`effectively when a magnet is disposed in a power feeding
`device side. In particular, when a magnet having a strong
`magnetic force, as a rare-earth magnet Such as later-de
`scribed Nd—Fe—B based magnet and Sm—Co based mag
`net, is used, the saturation magnetic flux density of the first
`30
`magnetic thin plate 2 is preferable to be 1 T or more, and is
`further preferable to be 1.2T or more. An upper limit of the
`saturation magnetic flux density of the first magnetic thin
`plate 2 is not limited in particular, but is preferable to be 2.1
`T (21 kG) or less. Also in a case where the aforementioned
`rare-earth magnet is used, it is sufficient that the Saturation
`magnetic flux density is about 2.1 T. Further, there is another
`reason that rust becomes easy to be generated during usage,
`if the Saturation magnetic flux density exceeds 2.1 T, since
`an additive element amount in an Fe alloy is limited sig
`nificantly and a measure to resist oxidation becomes insuf
`ficient.
`It is preferable that the laminate constituting the magnetic
`sheet 1 has one first magnetic thin plate 2 or first magnetic
`thin plates 2 laminated in a range of two to four plates. In
`order to make magnetic Saturation hard to occur in a case
`where a magnet is disposed in a power feeding device side,
`it is effective to make the number of the first magnetic thin
`plates 2 to be laminated large. However, when the number
`of the plates to be laminated is increased, an entire thickness
`of the magnetic sheet 1 becomes large. If the thickness of the
`entire magnetic sheet 1 becomes too large, it becomes
`difficult to mount the magnetic sheet 1 on an electronic
`apparatus which is demanded to be made thinner, such as a
`cellular phone. As a result that the first magnetic thin plate
`2 having a thickness of 50 to 300 um satisfies two or more
`conditions of the magnetostriction constant exceeding 5 ppm
`in the absolute value, the electric resistance value of 80 uS2
`cm or more, and the saturation magnetic flux density of 1 T
`or more, it becomes possible to decrease the number of the
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`first magnetic thin plates 2 to one to four, and further, to one
`to three.
`It is preferable that the second magnetic thin plate 4 has
`the thickness in the range of 10 to 30 um as described above.
`As a result of the thickness of the second magnetic thin plate
`4 being 30 um or less, the second magnetic thin plate 4 can
`have a higher magnetic permeability. However, if the thick
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`US 9,443,648 B2
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`ness of the second magnetic thin plate 4 is less than 10 um,
`manufacturing becomes difficult, and further, there is a
`possibility that the second magnetic thin plate 4 is broken at
`a time of formation of a later-described incision portion. The
`thickness of the second magnetic thin plate 4 is preferable to
`be in a range of 12 to 25um. The second magnetic thin plate
`4 is preferable to exhibit a high magnetic permeability at a
`used frequency of a power receiving device. The used
`frequency of the power receiving device means a frequency
`used in transmission for non-contact charging. The magnetic
`permeability of the second magnetic thin plate 4 is prefer
`able to be 1000 or more at a used frequency. The magne
`tostriction constant of the second magnetic thin plate