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

A power transmission device comprising:

• a single loop-shaped conductor;
• a communication circuit configured to wirelessly communicate data via the single loop-shaped conductor;
• a power transmission circuit configured to transmit power to an active electrode of a power reception device via the single loop-shaped conductor when the active electrode is capacitively coupled to the single loop-shaped conductor;
• a switching circuit configured to electrically couple the single loop-shaped conductor to the communication circuit in a data communication state and to electrically couple the single loop-shaped conductor to the power transmission circuit in a power transmission state;
• and
• a passive electrode of the power transmission device that is electrically insulated from the single loop-shaped conductor and that faces a passive electrode of the power reception device when the single loop-shaped conductor is capacitively coupled with the active electrode of the power reception device,
• wherein the single loop-shaped conductor has a first end and a second end,
• wherein the switching circuit includes a first switch that selectively connects the first end of the single loop-shaped conductor to the communication circuit or the power transmission circuit, and a second switch that selectively connects the second end of the single loop-shaped conductor to the communication circuit, and
• wherein, when the power transmission device is in the data communication state, the first switch connects the first end of the single loop-shaped conductor to the communication circuit and the second switch connects the second end of the single loop-shaped conductor to the communication circuit, and
• wherein, when the power transmission device is in the power transmission state, the second switch disconnects the second end of the single loop-shaped conductor from the communication circuit and the first switch connects the first end of the single loop-shaped conductor to the power transmission circuit.

A wireless power transmission system comprising:

• a power transmission device having:
• a power transmission side electrode,
• a passive electrode, and
• a voltage generating circuit configured to apply a voltage to the power transmission side electrode;
• and
• a power reception device having:
• a power reception side electrode that is a single loop-shaped conductor and capacitively coupled with the power transmission side electrode,
• a power reception circuit configured to receive power from the power transmission device through capacitive coupling of the power reception side electrode,
• a communication circuit configured to wireless communicate data via the power reception side electrode,
• a switching circuit configured to electrically couple the power reception side electrode to the communication circuit in a communication state and to electrically couple the power reception side electrode to the power reception circuit in a power reception state, and
• a coupling electrode that faces the passive electrode of the power transmission device when the power reception side electrode is capacitively coupled with the power transmission side electrode of the power transmission device, and
• wherein a voltage generated between the power reception side electrode and the coupling electrode is applied to the power reception circuit.

A wireless power transmission system comprising:

• a power reception device having a power reception side electrode and a passive electrode;
• and
• a power transmission device having:
• a power transmission side electrode that is a single loop-shaped conductor and capacitively coupled with the power reception side electrode,
• a voltage generating circuit configured to apply a voltage to the power transmission side electrode,
• a communication circuit to wirelessly communicate data via the power transmission side electrode,
• a switching circuit configured to electrically couple the power transmission side electrode to the communication circuit in a data communication state and to electrically couple the power transmission side electrode to the voltage generating circuit in a power transmission state, and
• a passive electrode of the power transmission device that faces the passive electrode of the power reception device when the power transmission side electrode is capacitively coupled with the power reception side electrode,
• wherein the single loop-shaped conductor has a first end and a second end,
• wherein the switching circuit includes a first switch that selectively connects the first end of the single loop-shaped conductor to the communication circuit or the voltage generating circuit, and a second switch that selectively connects the second end of the single loop-shaped conductor to the communication circuit, and
• wherein, when the power transmission device is in the data communication state, the first switch connects the first end of the single loop-shaped conductor to the communication circuit and the second switch connects the second end of the single loop-shaped conductor to the communication circuit, and
• wherein, when the power transmission device is in the power transmission state, the second switch disconnects the second end of the single loop-shaped conductor from the communication circuit and the first switch connects the first end of the single loop-shaped conductor to the voltage generating circuit.