FIELD: electricity.
SUBSTANCE: power transmission device comprises: the first power transmission unit made with the possibility to periodically perform wireless power transmission using the first antenna; the detection unit made with the possibility to detect a signal received from the power receiving device in response to the power transmission by the first power transmission unit; the second power transmission unit made with the possibility to perform wireless transmission of the power having a longer period than the period of power transmission by the first power transmission unit using the first antenna, in the case when the signal is detected by the detection unit; the third power transmission unit made with the possibility of performing wireless transmission of the power having a larger power amount than the amount of power in the power transmission by the first power transmission unit and the power in the power transmission by the second power transmission unit using the first antenna; and the communication unit made with the possibility to perform the communication with the power receiving device after the second power transmission unit performs the power transmission, in order to determine whether to excite the third power transmission unit to perform the power transmission using the second antenna different from the first antenna. The power transmission device operates in accordance with one of the first power transmission method, including detecting a signal modulated by a load using a power receiving device using the ID in response to the transmitted power during the periodic transmission and the second power transmission method including transmitting the power modulated in accordance with a predetermined ID so that the power receiving device detects a predetermined ID.
EFFECT: increasing the power transmission efficiency.
24 cl, 18 dwg
