Patent ID: 9431989
Filing Date: 2016-08-30
CPC Classification: H01F,H02J,H03H

Claim Text:
1. A power transmission device for transmitting electric power in a wireless manner to an electronic device, the electronic device including a secondary power reception coil and a power reception circuit configured to receive electric power via the secondary power reception coil, the power transmission device comprising: a primary power transmission coil; and a power transmission circuit that supplies electric power to the primary power transmission coil, the electric power supplied to the primary power transmission coil being transmitted to the secondary power reception coil, wherein a first impedance which corresponds to an input impedance of a transmission circuit, including the primary power transmission coil and the secondary power reception coil coupled to the primary power transmission coil, and to an impedance of the transmission circuit seen by the power transmission circuit, is matched with a second impedance which corresponds to an output impedance of the transmission circuit and to an impedance of the power reception circuit of the electronic device, by using a coupling coefficient between the primary power transmission coil and the secondary power reception coil, wherein, when the power transmission circuit supplies AC electric power at angular frequency ω to the primary power transmission coil, where L 1 is a first inductance of the primary power transmission coil, L 2 is a second inductance of the secondary power reception coil, Z 1 is the first impedance, Z 2 is the second impedance, and K is the coupling coefficient.