2.45-GHz Intermittent Wireless Power Transmission System for Batteryless LED Cosmetic Accessories

An intermittent wireless power transmission system that enables the supply of power to ultra-small wearable devices from a long distance while maintaining a constant average power has been developed. Intermittent power transmission, in which the transmission peak power becomes large in proportion to the reciprocal of the duty cycle, makes it possible to increase the distance between the transmitter and the receiver. A rhythm detection circuit generates a rhythm signal from the electrical musical signal, and that signal is used as a power-switch control signal for intermittent operation. We fabricated a 2.45-GHz wireless power transmission system that consists of a transmitter and LED false eyelashes; in this arrangement an LED with an ultra-small rectenna is embedded in a false eyelash. The transmitter has an intermittent power control circuit and a patch array antenna with a director antenna whose antenna gain is 13.83 dBi. When the transmitter radiated the power intermittently with a duty cycle of 10% and an average power of 1 W, the LEDs of the false eyelashes flashed in time to the music of a CD at a distance of 1.3 m.