Active stylus, electronic device, and wireless power supply system
Disclosed herein is an active stylus that transmits and receives signals to and from an electronic device, the active stylus including a receiver which, in operation, receives an uplink signal transmitted from the electronic device, a transmitter which, in operation, transmits a downlink signal to the electronic device, a power receiver which, in operation, receives power wirelessly supplied from the electronic device, and an integrated circuit. When the power is not being supplied to the power receiver, the integrated circuit causes the transmitter to transmit the downlink signal in response to the receiver receiving the uplink signal. The integrated circuit stops transmission of the downlink signal by the transmitter in response to detecting that supply of the power supply to the power receiver has started.
1 . An active stylus that transmits and receives signals to and from an electronic device, the active stylus comprising:
a receiver which, in operation, receives an uplink signal transmitted from the electronic device;
a transmitter which, in operation, transmits a downlink signal to the electronic device;
a power receiver which, in operation, receives power wirelessly supplied from the electronic device; and
an integrated circuit which, in operation, when the power is not being supplied to the power receiver, causes the transmitter to transmit the downlink signal in response to the receiver receiving the uplink signal, and stops transmission of the downlink signal by the transmitter in response to detecting that supply of the power to the power receiver has started,
wherein, after the integrated circuit stops transmission of the downlink signal by the transmitter in response to detecting that supply of the power to the power receiver has started, the integrated circuit causes the receiver to receive the uplink signal in response to detecting that supply of the power to the power receiver has ended.
2 . The active stylus according to claim 1 , wherein, when the integrated circuit detects that the active stylus and the electronic device have magnetically bonded, the integrated circuit detects that supply of the power to the power receiver has started.
3 . The active stylus according to claim 1 , wherein the integrated circuit detects that supply of the power to the power receiver has started by detecting an increase in voltage inside the power receiver.
4 . The active stylus according to claim 1 , wherein, when a signal indicating that supply of the power to the power receiver has started is received from the electronic device, the integrated circuit detects that supply of the power to the power receiver has started.
5 . The active stylus according to claim 1 , wherein the integrated circuit stops the transmission of the downlink signal by the transmitter by stopping reception of the uplink signal by the receiver.
6 . The active stylus according to claim 1 , wherein the integrated circuit stops the transmission of the downlink signal by entering a sleep mode in which the uplink signal is not received and the downlink signal is not transmitted.