Communication method executed between active pen and sensor controller, and active pen
An active pen is provided that transmits, through coupling capacitance, a signal to a sensor electrode connected to a sensor controller. The active pen includes a pen tip electrode provided on a leading end in a pen axis direction of the active pen; a peripheral electrode provided behind in the pen axis direction as viewed from the pen tip electrode; and a signal processor that transmits a downlink signal from the pen tip electrode and that transmits a reverse-phase signal of the downlink signal from the peripheral electrode at the same time.
1. An active pen that transmits, through coupling capacitance, a signal to a sensor electrode connected to a sensor controller, the active pen comprising:
a first electrode provided on a first portion in a pen axis direction of the active pen;
a second electrode provided on a second portion different from the first portion in the pen axis direction; and
a signal processor that transmits a downlink signal from the first electrode and that transmits a reverse-phase signal of the downlink signal from the second electrode at the same time,
wherein the second electrode includes a plurality of segmented electrodes, and
wherein the signal processor is capable of individually switching each of the plurality of segmented electrodes to transmit the downlink signal or to transmit the reverse-phase signal.
2. The active pen according to claim 1 , wherein the signal processor stops transmitting the reverse-phase signal from the second electrode according to a predetermined trigger.
3. The active pen according to claim 2 , wherein the predetermined trigger is provided by a timer built in the active pen.
4. The active pen according to claim 2 , wherein the predetermined trigger is provided by a beacon signal transmitted from the sensor controller.
5. The active pen according to claim 1 , wherein the signal processor starts to transmit the downlink signal from the first electrode according to a predetermined trigger.
6. The active pen according to claim 1 , wherein the signal processor uses a predetermined communication method to notify the sensor controller that the second electrode includes the plurality of segmented electrodes.
7. The active pen according to claim 1 , wherein the signal processor includes:
a transformer including a first inductor and a second inductor, and
a transmission circuit that generates the downlink signal,
wherein the first inductor is connected to the transmission circuit.
8. The active pen according to claim 1 , wherein the first electrode and the second electrode are connected to a normal-phase signal output terminal and a reverse-phase signal output terminal, respectively, of a reverse-phase signal generation circuit of the signal processor.