With development of wireless communication technology, there has been increased interest in wireless power transmitting and receiving technology for wirelessly supplying power to an electronic device. The wireless power transmitting and receiving technology can be applied for various purposes including power supply to electronic products for home use and power supply to electric vehicles or subways as well as battery charging of a portable terminal.
General wireless power transmitting and receiving technology uses a principle of magnetic induction or magnetic resonance. For example, when electrical energy is applied to a transmitting antenna of a wireless power transmitting apparatus, the transmitting antenna may convert the electrical energy into electromagnetic energy and radiate the electromagnetic energy to surroundings. Also, a receiving antenna of a wireless power receiving apparatus may receive the electromagnetic energy radiated from the transmitting antenna and convert the electromagnetic energy into electrical energy.
Here, to improve power transmitting and receiving efficiency, there is a need to minimize energy loss between the wireless power transmitting apparatus and the wireless power receiving apparatus. For this, the transmitting antenna and the receiving antenna may be aligned with each other within an effective distance. Also, a soft magnetic material may be arranged near the transmitting antenna and the receiving antenna, and the electromagnetic energy radiated by the transmitting antenna may be focused in a direction of the receiving antenna.
For this, a receiving coil is formed on a soft magnetic layer. Here, a problem in that a magnetic field guiding effect of the soft magnetic layer is decreased may occur due to a void formed between the soft magnetic layer and the receiving coil.