Touch-sensitive system with motion filtering

1. A stylus, comprising:

a pen-tip;

a sensor; and

a processor operable to:

operate in a lower-power mode and a higher-power mode;

detect, with the sensor, a defined frequency or a defined range of frequencies indicating shaking of the stylus;

transition from the lower-power mode to the higher-power mode in response to the detection of the defined frequency or the defined range of frequencies;

be prevented from transitioning from the lower-power mode to the higher-power mode in response to detection of a frequency other than the defined frequency and of a range of frequencies other than the defined range of frequencies; and

in response to a relative motion between the stylus and a device in communication with the stylus, process both a device signal representative of the relative motion and a stylus signal representative of the detection of the defined frequency or the defined range of frequencies.

2. The stylus according to the claim 1 , wherein

the higher-power mode is a mode in which a component for transmitting a high-voltage signal from an electrode in the stylus is activated, and

the lower power mode is a mode in which the component is deactivated.

3. The stylus according to claim 1 , wherein

the defined frequency or the defined range of frequencies indicates unintentional shaking of the stylus as opposed to intentional shaking of the stylus.

4. The stylus according to claim 1 , wherein the processing of the device signal includes adding a previous device signal representative of a previous relative motion of the stylus with respect to the device as an offset to the current device signal representative of the current relative motion of the stylus with respect to the device.

5. The stylus according to claim 4 , wherein the previous relative motion of the stylus with respect to the device is a motion of the stylus in a first direction on a display of the device, and the previous device signal is added as the offset to the current device signal.

6. A stylus, comprising:

a sensor; and

a processor operable to:

operate in a lower-power mode and a higher-power mode;

detect, with the sensor, a defined frequency or a defined range of frequencies indicating shaking of the stylus;

transition from the lower-power mode to the higher-power mode in response to the detection of the defined frequency or the defined range of frequencies;

be prevented from transitioning from the lower-power mode to the higher-power mode in response to detection of a frequency other than the defined frequency and a range of frequencies other than the defined range of frequency; and

in response to a relative motion of the stylus with respect to a device in communication with the stylus, process both a device signal representative of the relative motion and a stylus signal representative of the detection of the defined frequency or the defined range of frequencies.

7. A stylus, comprising:

a sensor; and

a processor operable to:

operate in a first mode and a second mode, wherein the stylus consumes less power in the first mode than in the second mode;

detect a first frequency with the sensor;

transition from the first mode to the second mode in response to the detection of the first frequency;

be prevented from transitioning from the first mode to the second mode in response to detection of a second frequency different from the first frequency; and

in response to a relative motion of the stylus with respect to a device in communication with the stylus, process both a device signal representative of the relative motion and a stylus signal representative of the detection of the first frequency.