Mobile terminals such as a mobile phone, a Personal Digital Assistant (PDA) and the like are generally powered by rechargeable batteries. The battery of the mobile terminal is charged using a separate charging device that supplies electric energy. Typically, the charging device and the battery have separate contact terminals that are physically connected, by for example a wire, during the charging operations.
However, in these types of charging schemes, the contact terminals are exposed and thus may be easily contaminated by foreign substances. As a result, battery charging may not be correctly performed. Further, the battery charging may also not be correctly performed when the contact terminal is exposed to moisture.
Recently, wireless charging or non-contact charging technologies have been developed and used for electronic devices to solve the above-mentioned problem.
Such wireless charging technology employs wireless electric power transmission/reception, and corresponds to, for example, a system in which a battery can be automatically charged when a portable phone is not physically connected to a separate charging apparatus by wire, but by merely placing the phone on a charging pad. This wireless charging technology can improve waterproof functionality of the electronic device because expose contact terminals may be removed from the devices. In the near further, wireless charging may be deployed not only in portable devices such as mobile phones and electric toothbrushes but also in, for example, electric cars.
Wireless charging technology may be based on electromagnetic induction using a coil, electric resonance, and/or RF/microwave radiation that converts electrical energy to a microwave and then transmitting the microwave.