Active stylus downlink signal transmission timing control relative to sensor controller
A method in which a sensor controller is connected to a sensor having an electrode group provided together with a display panel configured to operate in during a variable refresh cycle among a plurality of refresh cycles, and an active stylus performs bidirectional communication with the sensor controller. According to the method, the sensor controller acquires a present refresh cycle among the plurality of refresh cycles of the display panel, generates an uplink signal, which serves as a reference for synchronization corresponding to the acquired present refresh cycle, and transmits the uplink signal to the active stylus, which is not detected as yet or is detected already, at the present refresh cycle.
1 . A sensor controller for use with a stylus, the sensor controller comprising:
transmission circuitry, which, in operation,
repeatedly transmits, to the stylus, auxiliary uplink signals (USsubs) each having a time length corresponding to one bit and indicating a downlink transmission timing for the stylus; and
changes a transmission rate of uplink signals (US) based on a refresh cycle of a display coupled to the sensor controller, and transmits the uplink signals to the stylus at the changed transmission rate; and
reception circuitry, which, in operation, receives downlink signals (DS) from the stylus;
wherein each of the uplink signals (US) includes:
two of the auxiliary uplink signals (USsubs);
a command identifying content of data to be transmitted from the stylus to the sensor controller in the downlink signals (DS), the content selected from a position of the stylus, operation state data (OD) of the stylus including dynamic data, or configuration data (CD) of the stylus including static data; and
a cyclic redundancy code (CRC); and
wherein the transmission circuitry,
in response to the refresh cycle being a first refresh cycle, transmits the uplink signals to the stylus at a first transmission rate, and
in response to the refresh cycle being a second refresh cycle different from the first refresh cycle, transmits the uplink signals to the stylus at a second transmission rate different from the first transmission rate.
2 . The sensor controller of claim 1 , wherein the transmission rate is a reciprocal of the refresh cycle.
3 . The sensor controller of claim 1 , wherein the transmission circuitry transmits the uplink signals in vertical blanking periods.
4 . The sensor controller of claim 1 , wherein the sensor controller is an in cell type display sensor controller.
5 . The sensor controller of claim 1 , wherein the sensor controller is an on cell type display sensor controller.
6 . The sensor controller of claim 1 , wherein the reception circuitry receives the downlink signals, which are transmitted from the stylus in response to the uplink signals, at a reception rate which is a reciprocal of the refresh cycle.
7 . The sensor controller of claim 6 , wherein the reception circuitry receives the downlink signals in horizontal blanking periods.
8 . The sensor controller of claim 7 , wherein the uplink signals include information which defines the horizontal blanking periods.
9 . The sensor controller of claim 8 , wherein the transmission circuitry, in response to the refresh cycle being changed from the first refresh cycle to the second refresh cycle, transmits the uplink signals including information which defines second horizontal blanking periods different from first horizontal blanking periods defined prior to the refresh cycle being changed from the first refresh cycle to the second refresh cycle.
10 . A method performed by a sensor controller, the method comprising:
repeatedly transmitting, to a stylus, auxiliary uplink signals (USsubs) each having a time length corresponding to one bit and indicating a downlink transmission timing for the stylus;
changing a transmission rate of uplink signals (US) based on a refresh cycle of a display coupled to the sensor controller;
transmitting the uplink signals at the changed transmission rate to a stylus;
and
receiving the downlink signals (DS) from the stylus;
wherein each of the uplink signals (US) includes:
two of the auxiliary uplink signals (USsubs);
a command identifying content of data to be transmitted from the stylus to the sensor controller in the downlink signals (DS), the content selected from a position of the stylus, operation state data (OD) of the stylus including dynamic data, or configuration data (CD) of the stylus including static data; and
a cyclic redundancy code (CRC); and
wherein the transmitting the uplink signals includes:
transmitting the uplink signals to the stylus at a first transmission rate when the refresh cycle is a first refresh cycle, and
transmitting the uplink signals to the stylus at a second transmission rate different from the first transmission rate when the refresh cycle is a second refresh cycle different from the first refresh cycle.
11 . The method of claim 10 , wherein the transmission rate is a reciprocal of the refresh cycle.
12 . The method of claim 10 , comprising:
transmitting the uplink signals in vertical blanking periods.
13 . The method of claim 10 , comprising:
receiving the downlink signals, which are transmitted from the stylus in response to the uplink signals, at a reception rate which is a reciprocal of the refresh cycle.
14 . The method of claim 13 , comprising:
receiving the downlink signals in horizontal blanking periods.
15 . The method of claim 14 , wherein the uplink signals include information which defines the horizontal blanking periods.
16 . A system comprising:
a stylus; and
a sensor controller including:
transmission circuitry, which, in operation,
repeatedly transmits, to the stylus, auxiliary uplink signals (USsubs) to indicate a plurality of downlink transmission timings for the stylus; and
changes a transmission rate of uplink signals (US) based on a refresh cycle of a display coupled to the sensor controller, and transmits the uplink signals to the stylus at the changed transmission rate; and
reception circuitry, which, in operation, receives downlink signals (DS) from the stylus;
wherein each of the uplink signals (US) includes:
two of the auxiliary uplink signals (USsubs);
a command identifying content of data to be transmitted from the stylus to the sensor controller in the downlink signals (DS), the content selected from a position of the stylus, operation state data (OD) of the stylus including dynamic data, or configuration data (CD) of the stylus including static data; and
a cyclic redundancy code (CRC); and
wherein the transmission circuitry,
in response to the refresh cycle being a first refresh cycle, transmits the uplink signals to the stylus at a first transmission rate, and
in response to the refresh cycle being a second refresh cycle different from the first refresh cycle, transmits the uplink signals to the stylus at a second transmission rate different from the first transmission rate.
17 . The system of claim 16 , wherein the transmission rate is a reciprocal of the refresh cycle.
18 . The system of claim 16 , wherein the transmission circuitry transmits the uplink signals in vertical blanking periods.
19 . The system of claim 16 , wherein the sensor controller is an in cell type display sensor controller or an on cell type display sensor controller.
20 . The sensor controller of claim 1 , wherein the auxiliary uplink signal (USsub) indicates a time point of a blank period (BP) as the downlink transmission timing for the stylus.