Abstract: An object is to provide a power feeding system and a power feeding method which are more convenient for a power feeding user at the power receiving end. An object is to provide a power feeding system and a power feeding method which also allow a power feeding provider (a company) which feeds power (at the power transmitting end) to supply power without waste. A power feeding device which wirelessly supplies power to a power receiver detects the position and the resonant frequency of the power receiver to be supplied with power, and controls the frequency of a power signal to be transmitted to the power receiver on the basis of the information. An efficient power feeding service can be offered by transmitting a power signal to the power receiver at an optimum frequency for high power transmission efficiency.

Abstract: An object is to provide a power feeding system and a power feeding method which are more convenient for a power feeding user at the power receiving end, without causing increases in complexity and size of devices. An object is to provide a power feeding system and a power feeding method which also allow a power feeding provider (a company) which feeds power (at the power transmitting end) to supply power without waste. A power feeding device which wirelessly supplies power to a power receiver detects the position and the resonant frequency of the power receiver by receiving a position and resonant frequency detection signal using a plurality of sub-carriers having different frequencies from the power receiver, and controls the frequency of a power signal to be transmitted to the power receiver on the basis of the information. An efficient power feeding service can be offered by transmitting a power signal to the power receiver at an optimum frequency for high power transmission efficiency.

Abstract: An object of this invention is to provide a semiconductor device (an RFID) with reduced loss of voltage/current corresponding to a threshold value of a transistor, and having a voltage/current rectification property. Another object of this invention is to simplify a fabrication process and a circuit configuration. A rectifier circuit is provided in an element included in a semiconductor device (RFID) capable of communicating data wirelessly. As compared to the case where only a diode is provided, coils are provided between gate terminals and drain terminals of transistors constituting the diode in a rectifier circuit, so that the coils overlap an antenna which receives a radio wave, whereby a voltage output by the rectifier circuit is increased using electromagnetic coupling between the antenna which receives a radio wave and the coils, so that the rectification efficiency is improved.

Abstract: A resonant power feeding system that can provide high power transmission efficiency between a power feeding device and a power reception device without dynamically controlling the oscillation frequency in accordance with the distance between the power feeding device and the power reception device. High power transmission efficiency between the power feeding device and the power reception device is obtained by addition of a structure for adjusting the matching condition to both the power reception device and the power feeding device. Specifically, a transmission-reception circuit and a matching circuit are provided in both the power reception device and the power feeding device, and wireless signals for adjusting the matching circuit are transmitted and received through a resonant coil. Thus, the power feeding device can efficiently supply power to the power reception device without adjusting the oscillation frequency.

Abstract: A wireless power feed system with high transfer efficiency of electric power is disclosed. The wireless power feed system includes a power feeding device and a power receiving device, wherein the power feeding device includes a first electromagnetic coupling coil that is connected to an AC power source via a directional coupler; a first resonant coil; a switch connected to the opposite ends of the first resonant coil; a control circuit which conducts switching on/off of the switch based on a parameter of an amplitude of a reflective wave detected by the directional coupler; and an analog-digital converter provided between the first electromagnetic coupling coil and the control circuit; and the power receiving device includes a second resonant coil; and a second electromagnetic coupling coil, and wherein the first electromagnetic coupling coil is provided between the first resonant coil and the second resonant.

Abstract: An object is to provide a power feeding device, a power feeding system, and a power feeding method which are more convenient for a power feeding user at the power receiving end. The power feeding device includes a means of controlling a frequency of a power signal transmitted to a power receiver, based on a proportion of signals, among power signals output to an antenna circuit, that return from the power receiver to the antenna circuit without feeding power to the power receiver.

Abstract: An object is to provide a power feeding system and a power feeding method which are more convenient for a power feeding user at the power receiving end. An object is to provide a power feeding system and a power feeding method which also allow a power feeding provider (a company) which feeds power (at the power transmitting end) to supply power without waste. A power feeding device which wirelessly supplies power to a power receiver detects the position and the resonant frequency of the power receiver to be supplied with power, and controls the frequency of a power signal to be transmitted to the power receiver on the basis of the information. An efficient power feeding service can be offered by transmitting a power signal to the power receiver at an optimum frequency for high power transmission efficiency.

Abstract: A power feeding device which wirelessly supplies power to a power receiver receives a position and resonant frequency detection signal from the power receiver, detects the position and the resonant frequency of the power receiver, and controls the frequency of a power signal to be transmitted to the power receiver on the basis of the information. As the power signal for power transmission, two signals having different frequencies, which are generated using a mixer by mixing a base carrier (a first signal) with a conversion carrier (a second signal) generated on the basis of the resonant frequency, are used.

Abstract: An object of this invention is to provide a semiconductor device (an RFID) with reduced loss of voltage/current corresponding to a threshold value of a transistor, and having a voltage/current rectification property. Another object of this invention is to simplify a fabrication process and a circuit configuration. A rectifier circuit is provided in an element included in a semiconductor device (RFID) capable of communicating data wirelessly. As compared to the case where only a diode is provided, coils are provided between gate terminals and drain terminals of transistors constituting the diode in a rectifier circuit, so that the coils overlap an antenna which receives a radio wave, whereby a voltage output by the rectifier circuit is increased using electromagnetic coupling between the antenna which receives a radio wave and the coils, so that the rectification efficiency is improved.

Abstract: An object is to provide a power feeding system and a power feeding method which are more convenient for a power feeding user at the power receiving end, without causing increases in complexity and size of devices. An object is to provide a power feeding system and a power feeding method which also allow a power feeding provider (a company) which feeds power (at the power transmitting end) to supply power without waste. A power feeding device which wirelessly supplies power to a power receiver detects the position and the resonant frequency of the power receiver by receiving a position and resonant frequency detection signal using a plurality of sub-carriers having different frequencies from the power receiver, and controls the frequency of a power signal to be transmitted to the power receiver on the basis of the information. An efficient power feeding service can be offered by transmitting a power signal to the power receiver at an optimum frequency for high power transmission efficiency.

Abstract: According to one embodiment, a display apparatus including a display screen, a first view-angle-controlled filter which is effective on a first direction of the display screen, a second view-angle-controlled filter which is effective on a second direction of the display screen, the second direction being orthogonal to the first direction, and a switching unit configured to allow the first view-angle-controlled filter and second view-angle-controlled filter to function exclusively and selectively.