Antenna device and communication device

Abstract

An antenna device that is built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter includes an antenna coil formed on a printed circuit board and inductively coupled to the transmitter, and a magnetic sheet that attracts the magnetic field transmitted from the transmitter to the antenna coil. The antenna coil and the magnetic sheet are superposed on each other.

What is claimed is: 
     
         1 . An antenna device that is built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, comprising:
 an antenna coil formed on a printed circuit board and inductively coupled to the transmitter; and   a magnetic sheet that attracts the magnetic field transmitted from the transmitter to the antenna coil,   wherein the antenna coil and the magnetic sheet are superposed on each other.   
     
     
         2 . The antenna device according to  claim 1 , wherein an end portion of the magnetic sheet is arranged so as to superpose on an opening of a center portion of the antenna coil formed on the printed circuit board. 
     
     
         3 . The antenna device according to  claim 1 , wherein
 step portions are formed at a position where the magnetic sheet is inserted into a center portion of the antenna coil formed on the printed circuit board, and   the antenna coil and the magnetic sheet are superposed on each other to form a uniform surface across the step portions in the inserted state.   
     
     
         4 . The antenna device according to  claim 1 , further comprising a conductor plate superposed to cover at least an entire surface of the antenna coil while being insulated from the antenna coil. 
     
     
         5 . The antenna device according to  claim 4 , wherein the conductor plate includes an opening to expose a terminal unit of the antenna coil. 
     
     
         6 . A communication device built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, wherein the antenna device according to  claim 1  is arranged along an inner surface of an outer plate forming a housing of the electronic device. 
     
     
         7 . The communication device according to  claim 6 , wherein the antenna device is arranged along the inner surface of the outer plate on an outer periphery side of the electronic device. 
     
     
         8 . A communication device built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, wherein the antenna device according to  claim 2  is arranged along an inner surface of an outer plate forming a housing of the electronic device. 
     
     
         9 . A communication device built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, wherein the antenna device according to  claim 3  is arranged along an inner surface of an outer plate forming a housing of the electronic device. 
     
     
         10 . A communication device built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, wherein the antenna device according to  claim 4  is arranged along an inner surface of an outer plate forming a housing of the electronic device. 
     
     
         11 . A communication device built in an electronic device and that can perform communication by receiving a magnetic field transmitted from a transmitter, wherein the antenna device according to  claim 5  is arranged along an inner surface of an outer plate forming a housing of the electronic device. 
     
     
         12 . The communication device according to  claim 8 , wherein the antenna device is arranged along the inner surface of the outer plate on an outer periphery side of the electronic device. 
     
     
         13 . The communication device according to  claim 9 , wherein the antenna device is arranged along the inner surface of the outer plate on an outer periphery side of the electronic device. 
     
     
         14 . The communication device according to  claim 10 , wherein the antenna device is arranged along the inner surface of the outer plate on an outer periphery side of the electronic device. 
     
     
         15 . The communication device according to  claim 11 , wherein the antenna device is arranged along the inner surface of the outer plate on an outer periphery side of the electronic device.