Coil unit and electronic instrument
A coil unit includes a planar coil that has a transmission side and a non-transmission side, a magnetic sheet provided over the non-transmission side of the planar coil, and a heat sink/magnetic shield plate stacked on a side of the magnetic sheet opposite to a side that faces the planar coil, the heat sink/magnetic shield plate dissipating heat generated by the planar coil and shielding magnetism by absorbing a magnetic flux that has not been absorbed by the magnetic sheet. The heat sink/magnetic shield plate has a thickness larger than that of the magnetic sheet.
1. A coil unit comprising:
a planar coil that has a transmission side and a non-transmission side;
a magnetic sheet provided over the non-transmission side of the planar coil; and
a heat sink/magnetic shield plate stacked on a side of the magnetic sheet opposite to a side that faces the planar coil, thus forming a stack direction, the heat sink/magnetic shield plate dissipating heat generated by the planar coil and shielding magnetism by absorbing a magnetic flux that has not been absorbed by the magnetic sheet,
the heat sink/magnetic shield plate being formed of a non-magnetic material, and
the heat sink/magnetic shield plate having a thickness larger than that of the magnetic sheet in the stack direction.
2. The coil unit as defined in claim 1 ,
the coil unit further including:
a substrate, the heat sink/magnetic shield plate being secured on the substrate; and
a temperature detection element provided on the substrate, the temperature detection element detecting the temperature of the planar coil due to heat generation that is transferred through solid heat conduction of the magnetic sheet and the heat sink/magnetic shield plate.
3. The coil unit as defined in claim 2 ,
heat transfer conductive patterns being formed on a front side and a back side of the substrate, the front side facing the heat sink/magnetic shield plate; and
the temperature detection element being provided on the back side of the substrate.
4. The coil unit as defined in claim 3 ,
the heat transfer conductive patterns formed on the front side and the back side of the substrate being connected via a through-hole formed through the substrate.
5. The coil unit as defined in claim 2 ,
a depression being formed in a side of the heat sink/magnetic shield plate that faces the substrate; and
the temperature detection element being provided on a front side of the substrate and disposed inside the depression formed in the heat sink/magnetic shield plate, the front side of the substrate facing the heat sink/magnetic shield plate.
6. The coil unit as defined in claim 5 ,
a heat transfer conductive pattern being formed on the front side of the substrate.
7. The coil unit as defined in claim 2 ,
the temperature detection element being an element that breaks or suppresses power supplied to the planar coil based on the temperature of the planar coil due to heat generation.
8. The coil unit as defined in claim 1 ,
the coil unit further including a covering member that covers an edge of the magnetic sheet.
9. The coil unit as defined in claim 2 ,
the coil unit further including a protective sheet having a hole that receives the planar coil, the protective sheet covering edges of the magnetic sheet and the heat sink/magnetic shield plate and securing the magnetic sheet and the heat sink/magnetic shield plate on a front side of the substrate.
10. The coil unit as defined in claim 1 ,
the coil unit including a plurality of the magnetic sheets,
the thickness of the heat sink/magnetic shield plate being larger than the total thickness of the plurality of magnetic sheets.
11. The coil unit as defined in claim 1 ,
the planar coil having an inner end lead line and an outer end lead line, the inner end lead line being provided over the non-transmission side of the planar coil; and
a spacer member being disposed between the planar coil and the magnetic sheet, the spacer member having a thickness substantially equal to the thickness of the inner end lead line, and a slit being formed in the spacer member at a position at which the inner end lead line is provided.
12. The coil unit as defined in claim 3 ,
the substrate having a mounting surface provided with a mounted component in an area that extends from an area that faces the heat sink/magnetic shield plate, the mounting surface being provided on the back side of the substrate.
13. An electronic instrument comprising the coil unit as defined in claim 1 .
14. A coil unit comprising:
a planar coil;
a magnetic sheet; and
a heat sink/magnetic shield plate that has a thickness larger than that of the magnetic sheet in a stack direction,
the magnetic sheet being provided between the planar coil and the heat sink/magnetic shield plate in the stack direction, and
the heat sink/magnetic shield plate dissipating heat generated by the planar coil and shielding magnetism by absorbing a magnetic flux that has not been absorbed by the magnetic sheet.