Power receiving device, and electronic apparatus and non-contact charger using the same

1. A power receiving device, comprising:

a power receiving coil having a spiral coil;

a rectifier rectifying an alternating voltage generated in the power receiving coil;

a secondary battery to which a direct-current voltage rectified in the rectifier is charged; and

a magnetic foil arranged in at least one of a position between the spiral coil and the secondary battery, and a position between the spiral coil and the rectifier,

wherein the magnetic foil comprises an amorphous alloy thin ribbon or an iron-based Microcrystalline alloy thin ribbon having an average thickness in a range of 5 to 50 μm,

wherein the magnetic foil has a Ms·t value of 15 or more and 103.68 or less, where Ms [T] is a saturation flux density of the magnetic foil, t [μm] is a plate thickness of the the magnetic foil, and the Ms·t value [T·μm] is a product of the saturation flux density Ms and the plate thickness t,

wherein the power receiving coil has a power receiving rate of 0.25 W/h or more.

2. The power receiving device according to claim 1 , wherein the magnetic foil has a μr′·t value of 40000 or more, where μr′ is a real component of relative permeability of the magnetic foil and the μr′·t value [μm] is a product of the real component μr′ of the relative permeability and the plate thickness t.

3. The power receiving device according to claim 1 , wherein the magnetic foil has a R·μr′ value of 1.01×10 −3 or more, where R [Ω·m] is an electric resistivity of the magnetic foil, μr′ is a real component of relative permeability of the magnetic foil, and the R·μr′ value [Ω·m] is a product of the electric resistivity R and the real component μr′ of the relative permeability.

4. The power receiving device according to claim 1 , wherein an outer peripheral edge of the magnetic foil extends outward farther than an outer peripheral portion of the spiral coil.

5. The power receiving device according to claim 1 , wherein the magnetic foil has a slit.

6. The power receiving device according to claim 1 , wherein the secondary battery is an lithium ion secondary battery.

7. An electronic apparatus, comprising:

a power receiving device which is provided with a power receiving coil having a spiral coil, a rectifier rectifying an alternating voltage generated in the power receiving coil, and a secondary battery to which a direct-current voltage rectified in the rectifier is charged;

an electronic apparatus body which is provided with an electronic device which is operated by the direct-current voltage supplied from the secondary battery, and a circuit board on which the electronic device is mounted; and

a magnetic foil arranged in at least one of a position between the spiral coil and the secondary battery, a position between the spiral coil and the rectifier, a position between the spiral coil and the electronic device, and a position between the spiral coil and the circuit board,

wherein the magnetic foil comprises an amorphous alloy thin ribbon or an iron-based Microcrystalline alloy thin ribbon having an average thickness in a range of 5 to 50 μm,

wherein the magnetic foil has a Ms·t value of 15 or more and 103.68 or less, where Ms [T] is a saturation flux density of the magnetic foil, t [μm] is a plate thickness of the the magnetic foil, and the Ms·t value [T·μm] is a product of the saturation flux density Ms and the plate thickness t,

wherein the power receiving coil has a power receiving rate of 0.25 W/h or more.

8. The electronic apparatus according to claim 7 , wherein the magnetic foil has a μr′·t value of 40000 or more, where μr′ is a real component of relative permeability of the magnetic foil and the μr′·t value is a product of the real component μr′ of the relative permeability and the plate thickness t.

9. The electronic apparatus according to claim 7 , wherein the magnetic foil has a R·μr′ value of 1.01×10 −3 or more, where R [Ω·m] is an electric resistivity of the magnetic foil, μr′ is a real component of relative permeability of the magnetic foil, and the R·μr′ value [Ω·m] is a product of the electric resistivity R and the real component μr′ of the relative permeability.

10. The electronic apparatus according to claim 7 , wherein the spiral coil is arranged around the secondary battery, and the magnetic foil is arranged between the spiral coil and the circuit board.

11. The electronic apparatus according to claim 7 , wherein the magnetic foil has a bent portion which is formed by bending an outer peripheral edge of the magnetic foil in a direction opposite to the circuit board.

12. The electronic apparatus according to claim 7 , wherein an outer peripheral edge of the magnetic foil extends outward farther than an outer peripheral portion of the spiral coil.

13. The electronic apparatus according to claim 7 , wherein the magnetic foil has a slit.

14. The electronic apparatus according to claim 7 , wherein the secondary battery is an lithium ion secondary battery.

15. A non-contact charger, comprising:

the electronic apparatus according to claim 7 ; and

a power feeding device which is provided with a power feeding coil arranged in a non-contact manner with the power receiving coil of the electronic apparatus and a power supply supplying an alternating voltage to the power feeding coil,

wherein magnetic flux generated in the power feeding coil is transmitted to the power receiving coil to transmit electric power in a non-contact manner.

16. The power receiving device according to claim 1 ,

wherein the magnetic foil comprises a plurality of the amorphous alloy thin ribbons or a plurality of the iron-based microcrystalline alloy thin ribbons, and the plate thickness t of the magnetic foil is a total thickness of the plurality of amorphous alloy thin ribbons or of the plurality of iron-based microcrystalline alloy thin ribbons.

17. The power receiving device according to claim 7 ,

wherein the magnetic foil comprises a plurality of the amorphous alloy thin ribbons or a plurality of the iron-based microcrystalline alloy thin ribbons, and the plate thickness t of the magnetic foil is a total thickness of the plurality of amorphous alloy thin ribbons or of the plurality of the iron-based microcrystalline alloy thin ribbons.