Antenna device and electronic device
An antenna device includes a power supply coil to which a near field communication circuit is connected, a near field communication coil that is coupled to an antenna coil of a communication target and the power supply coil via a magnetic field and that resonates at the frequency of a near field communication signal, and a non-contact charging coil that is connected to a non-contact charging control circuit and that is coupled to a target coil for non-contact charging. The power supply coil and the non-contact charging coil are provided on the same plane or on planes that are close to each other. The non-contact charging coil is superposed with the near field communication coil when viewed in plan view, and the shortest distance between the power supply coil and the NFC coil is smaller than the shortest distance between the power supply coil and the non-contact charging coil.
1. An antenna device comprising:
a power supply coil to which a first wireless transmission system circuit is connected;
a first wireless transmission system coil that is coupled to an antenna coil of a transmission target in a first wireless transmission system and to the power supply coil via a magnetic field and that resonates at a transmission frequency of the first wireless transmission system; and
a second wireless transmission system coil that is connected to a second wireless transmission system circuit and that is coupled to an antenna coil of a transmission target in a second wireless transmission system via a magnetic field; wherein
at least a portion of a coil opening of the second wireless transmission system coil and at least a portion of a coil opening of the first wireless transmission system coil are superposed with each other when viewed in plan view;
the first wireless transmission system coil includes a principal portion and a coupling portion that is coupled to the power supply coil via a magnetic field; and
a shortest distance between the coupling portion of the first wireless transmission system coil and the power supply coil is smaller than a shortest distance between the power supply coil and the second wireless transmission system coil.
2. The antenna device according to claim 1 , wherein the coupling portion is located at a position different from a position of a portion of the first wireless transmission system coil, the portion being closest to the second wireless transmission system coil.
3. The antenna device according to claim 1 , further comprising:
a magnetic sheet that is superposed with the second wireless transmission system coil when viewed in plan view.
4. The antenna device according to claim 3 , wherein
the magnetic sheet is positioned in a vicinity of the first wireless transmission system coil;
at least a portion of the first wireless transmission system coil is located out of a vicinity range of the magnetic sheet; and
the power supply coil is disposed at a position where the power supply coil is in a magnetic field coupling relationship with the coupling portion of the first wireless transmission system coil, the position being located out of the vicinity range of the magnetic sheet.
5. The antenna device according to claim 1 , wherein the power supply coil is disposed in an area outside the second wireless transmission system coil when viewed in plan view.
6. The antenna device according to claim 5 , wherein
the power supply coil includes a magnetic core and a coil conductor that is wound around the magnetic core; and
the power supply coil is disposed such that a coil winding axis of the coil conductor extends in the area outside the second wireless transmission system coil when viewed in plan view.
7. The antenna device according to claim 1 , wherein the power supply coil is disposed in an area inside the second wireless transmission system coil when viewed in plan.
8. The antenna device according to claim 1 , wherein the power supply coil is disposed at a position that is superposed with a coil winding axis of the second wireless transmission system coil when viewed in plan view.
9. The antenna device according to claim 3 , wherein the coupling portion of the first wireless transmission system coil is located on a rear side of the magnetic sheet as seen from the second wireless transmission system coil.
10. The antenna device according to claim 9 , wherein the principal portion of the first wireless transmission system coil is located on a surface of the magnetic sheet on which the second wireless transmission system coil is located.
11. The antenna device according to claim 10 , wherein the first wireless transmission system coil is provided on a base material sheet that is bent, and as a result of the base material sheet being bent, the coupling portion of the first wireless transmission system coil is positioned on a side opposite to a side on which the principal portion of the first wireless transmission system coil is positioned with respect to the magnetic sheet.
12. The antenna device according to claim 10 , wherein the first wireless transmission system coil is provided on a base material sheet that has an opening, and the magnetic sheet is inserted into the opening of the base material sheet such that the coupling portion of the first wireless transmission system coil is positioned on a side opposite to a side on which the principal portion of the first wireless transmission system coil is positioned with respect to the magnetic sheet.
13. The antenna device according to claim 1 , further comprising:
a magnetic sheet that is superposed with the second wireless transmission system coil and the first wireless transmission system coil when viewed in plan view; wherein
the power supply coil is disposed in an area outside the second wireless transmission system coil when viewed in plan view; and
in a region that is superposed with the second wireless transmission system coil when viewed in plan view, the magnetic sheet is positioned on a side opposite to a side on which a target coil for the second wireless transmission system is positioned with respect to the second wireless transmission system coil, and in the coupling portion of the first wireless transmission system coil, the magnetic sheet is positioned on a side opposite to a side on which the power supply coil is positioned with respect to the first wireless transmission system coil.
14. The antenna device according to claim 1 , wherein a conductive member or a magnetic member is disposed between the power supply coil and the coil for the second wireless transmission system.
15. The antenna device according to claim 1 , wherein the first wireless transmission system coil and the second wireless transmission system coil are provided on the same main surface of a substrate.
16. The antenna device according to claim 15 , wherein the substrate is bent in the area outside the second wireless transmission system coil, and as a result of the substrate being bent, the coupling portion of the first wireless transmission system coil is positioned on a side opposite to a side on which the surface, on which the second wireless transmission system coil is disposed, is positioned.
17. The antenna device according claim 1 , wherein a transmission frequency band of the first wireless transmission system and a transmission frequency band of the second wireless transmission system are different from each other.
18. The antenna device according claim 1 , wherein one of the first wireless transmission system and the second wireless transmission system is a near field communication system, and another one of the first wireless transmission system and the second wireless transmission system is a non-contact charging system.
19. The antenna device according to claim 18 , wherein the antenna device is included in an electronic device, the electronic device comprising:
a secondary battery that is a power supply for a circuit including a circuit of the near field communication system; and
a non-contact charging control circuit that charges the secondary battery by using electrical power induced by a coil for the non-contact charging system.