Patent attributes
In an electric power transmission device in which a primary side power transmission coil (L1) and a secondary side power receiving coil (L2) are magnetically coupled, and electric power is transmitted from the primary side power transmission coil (L1) to the secondary side power receiving coil (L2) via a non-contact and out of touch, a capacitor (C1) is connected to the primary side power transmission coil (L1) in series, a voltage to be supplied to the primary side power transmission coil (L1) is converted into AC voltage and stepped up, and a series resonance circuit (7) including a mutual inductance (M) by the secondary side power receiving coil (L2) is formed; wherein a resonance point of the series resonance circuit (7) including the mutual inductance (M) by the secondary side power receiving coil (L2) is set to a frequency higher than a resonance point of a primary side series resonance circuit (6) which is composed of the primary side power transmission coil (L1) and the capacitor (C1), whereby a high electric power transmission efficiency of practical level can be obtained and thus reduction in size and weight and electric power saving can be easily realized with the high electric power transmission efficiency.
