Murata Manufacturing Co., Ltd.

Satoshi Shinoda

Takahiro Baba

Koichi Sakamoto

Keiichi Ichikawa

Hiroshi Nishida

Hironori Sakai

Akihiko Shibata

Masanori Fujidai

Takahide Sano

A power receiving apparatus to which power is transmitted from a power transmission apparatus through electric field coupling includes a parallel resonance circuit in which an active electrode and a passive electrode are connected, a capacitor and a first switch that change a resonance condition of the parallel resonance circuit, and a second switch that supplies or cuts off an AC voltage, outputted from the parallel resonance circuit, to or from a load. The power receiving apparatus also includes a communication unit that notifies of the start of communication with the power transmission apparatus and receives a response to the notification, a first switching unit that generates a signal to be sent to the power transmission apparatus, and a second switching unit that connects or disconnects the second switch based on the response received by the communication unit.

Power receiving apparatus and power transmission system

A wireless power transmission system transmits power from a power transmitting apparatus to a relay power receiving apparatus by applying voltage to an active electrode in the power transmitting apparatus, which is opposed to an active electrode in the relay power receiving apparatus, and a passive electrode in the power transmitting apparatus, which is opposed to a passive electrode in the relay power receiving apparatus.

Electronic apparatus and wireless power transmission system

A mobile terminal device performs short range communication with an R/W device and receives power from a power transmission device. The mobile terminal device includes a coil antenna, an RFID IC circuit that performs short range communication with the outside via the coil antenna, a charging circuit that receives power received by the coil antenna which is capacitively coupled with a passive electrode and switches that switch to a short range communication state in which short range communication is performed via the coil antenna or a power reception state in which power is received via the coil antenna. Accordingly, a power reception device, a power transmission device and a wireless power transmission system are provided with which wireless power transmission can be realized without obstructing size reduction by giving a single member two functions.

Power reception device, power transmission device and wireless power transmission system

This disclosure provides a contactless power reception circuit that includes a power reception part, a voltage rectifying part, a voltage transforming part and a load modulation part. The voltage transforming part includes a smoothing capacitor, a DCDC converter and a backflow prevention device. The power reception part is couplable with an electromagnetic field adjacent to the contactless power reception circuit. The rectifying part rectifies a voltage output from the power reception part, the voltage transforming part transforms rectified voltage from the rectifying part, and the load modulation circuit conducts a load modulation while signals are transmitted. The smoothing capacitor smoothes a voltage input to the voltage transforming part, the DCDC converter transforms voltage smoothed by the smoothing capacitor, and the backflow prevention device prevents backflow of charge from the smoothing capacitor while the signals are transmitted to a contactless power transmission circuit.

Contactless power reception circuit and contactless power transmission system

This disclosure provides a wireless power transfer terminal that enables a power device to be used for both power transmission and power reception and allows space savings of circuits and a reduction in the cost of manufacturing. The wireless power transfer terminal includes first through fourth switching elements, a coil, and a control circuit. Each of two sets of switching elements forms a series circuit, and the two sets are connected in parallel to each other. The coil is connected between connection points of the switching elements of the series circuits. The control circuit performs switching control of the first to fourth switching elements in a power transmission mode and in a power reception mode.

Wireless power transfer terminal

A voltage controlled oscillator includes a resonant circuit which is connected with an active circuit. In the resonant circuit, a variable capacitance diode is connected with a resonator via a transmission line, and a capacitive circuit is connected in parallel with the variable capacitance diode. By setting the length of the transmission line to an appropriate value ranging from, for example, about one quarter to about one half of the wavelength of the resonant frequency, the frequency change width can increase, while maintaining the frequency linearity because of connection of the capacitive circuit.

Voltage-controlled oscillator having a transmission line between a resonator and a variable capacitance diode, high-frequency module including the same, and communication apparatus including the same

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Nagaokakyo, Japan

Satoshi Shinoda