Power management system for active stylus
In one embodiment, a stylus includes one or more electrodes and one or more computer-readable non-transitory storage media embodying first logic for transmitting signals wirelessly to a device through a touch-sensor of the device. The stylus has a first power mode in which components of the stylus for receiving signals from or transmitting signals to the device are powered off; a second power mode in which components of the stylus for receiving signals from the device are powered on at least periodically and components of the stylus for transmitting signals to the device are powered off; and a third power mode in which components of the stylus for transmitting signals to the device are powered on at least periodically. The media further embodies second logic for transitioning the stylus from one of the first, second, and third power modes to another one of the first, second, and third power modes.
1. A stylus comprising: one or more electrodes and one or more computer-readable non-transitory storage media embodying first logic for transmitting signals wirelessly to a device through a touch sensor of the device,
the stylus having:
a high-power mode in which one or more components of the stylus for transmitting signals to the device are periodically powered on when one or more touch-sensor drive lines in proximity of the stylus are scanned by the device; and
a low-power mode in which the one or more components of the stylus for transmitting signals to the device are periodically powered off when the touch-sensor drive lines are not scanned by the device; wherein: the stylus is operable to learn a timing of when the device scans the one or more touch-sensor drive lines; the one or more components of the stylus are periodically powered on based at least in part on the learned timing;
the one or more components of the stylus are periodically powered off based at least in part on the learned timing;
in the high-power mode the one or more components are, while the stylus learns the timing, further powered on for a predetermined amount of time before the touch-sensor drive lines are scanned;
the media further embodies second logic for dynamically adjusting the predetermined amount of time; and
dynamically adjusting the predetermined amount of time comprises decreasing the predetermined amount of time until the predetermined amount of time is within a predetermined range of when the one or more drive lines are scanned by the device.
2. The stylus of claim 1 , wherein the period at which the one or more components are periodically powered on is based at least in part on a frequency at which the device scans the touch-sensor drive lines.
3. The stylus of claim 1 , wherein the drive lines are in the proximity of the stylus based on a motion of the stylus relative to the device.
4. A method comprising:
by first logic embodied by one or more computer-readable non-transitory storage media of a stylus, transitioning the stylus from one power mode to another, both being selected from the group consisting of a high-power mode and a low-power mode, the stylus comprising one or more electrodes and the media further embodying second logic for transmitting signals wirelessly to a device through a touch-sensor of the device, wherein: in the high-power mode one or more components of the stylus for transmitting signals to the device are periodically powered on when one or more touch-sensor drive lines in proximity of the stylus are scanned by the device;
in the low-power mode the one or more components of the stylus for transmitting signals to the device are periodically powered off when the touch-sensor drive lines are not scanned by the device;
the stylus is operable to learn a timing of when the device scans the one or more touch-sensor drive lines;
the one or more components of the stylus are periodically powered on based at least in part on the learned timing;
the one or more components of the stylus are periodically powered off based at least in part on the learned timing;
in the high-power mode the one or more components are, while the stylus learns the timing, further powered on for a predetermined amount of time before the touch-sensor drive lines are scanned;
the second logic is operable to dynamically adjust the predetermined amount of time; and
dynamically adjusting the predetermined amount of time comprises decreasing the predetermined amount of time until the predetermined amount of time is within a predetermined range of when the one or more drive lines are scanned by the device.
5. The method of claim 4 , wherein the period at which the one or more components are periodically powered on is based at least in part on a frequency at which the device scans the touch-sensor drive lines.
6. The method of claim 4 , wherein the drive lines are in the proximity of the stylus based on a motion of the stylus relative to the device.
7. One or more computer-readable non-transitory storage media embodying first logic that is operable when executed to:
transition a stylus from one power mode to another, both being selected from the group consisting of a high-power mode and a low-power mode, the stylus comprising one or more electrodes and the media further embodying second logic for transmitting signals wirelessly to a device through a touch-sensor of the device, wherein:
in the high-power mode one or more components of the stylus for transmitting signals to the device are periodically powered on when one or more touch-sensor drive lines in proximity of the stylus are scanned by the device;
in the low-power mode the one or more components of the stylus for transmitting signals to the device are periodically powered off when the touch-sensor drive lines are not being scanned by the device;
the stylus is operable to learn a timing of when the device scans the one or more touch-sensor drive lines;
the one or more components of the stylus are periodically powered on based at least in part on the learned timing; and
the one or more components of the stylus are periodically powered off based at least in part on the learned timing;
in the high-power mode the one or more components are, while the stylus learns the timing, further powered on for a predetermined amount of time before the touch-sensor drive lines are scanned;
the second logic is operable to dynamically adjust the predetermined amount of time; and
dynamically adjusting the predetermined amount of time comprises decreasing the predetermined amount of time until the predetermined amount of time is within a predetermined range of when the one or more drive lines are scanned by the device.
8. The media of claim 7 , wherein the period at which the one or more components are periodically powered on is based at least in part on a frequency at which the device scans the touch-sensor drive lines.
9. The media of claim 7 , wherein the drive lines are in the proximity of the stylus based on a motion of the stylus relative to the device.
10. A stylus comprising: one or more electrodes and one or more computer-readable non-transitory storage media embodying first logic for transmitting signals wirelessly to a device through a touch sensor of the device,
the stylus having:
a high-power mode in which one or more components of the stylus for transmitting signals to the device are periodically powered on when one or more touch-sensor drive lines in proximity of the stylus are scanned by the device; and
a low-power mode in which the one or more components of the stylus for transmitting signals to the device are periodically powered off when the one or more touch-sensor drive lines in the proximity of the stylus are not being scanned by the device, one or more touch-sensor drive lines outside the proximity of the stylus being scanned by the device for at least a portion of a time that the one or more touch-sensor drive lines in the proximity of the stylus are not being scanned;
wherein:
the stylus is operable to learn a timing of when the device scans the one or more touch-sensor drive lines;
the one or more components of the stylus are periodically powered on based at least in part on the learned timing;
the one or more components of the stylus are periodically powered off based at least in part on the learned timing;
in the high-power mode the one or more components are, while the stylus learns the timing, further powered on for a predetermined amount of time before the touch-sensor drive lines are scanned;
the media further embodies second logic for dynamically adjusting the predetermined amount of time; and
dynamically adjusting the predetermined amount of time comprises decreasing the predetermined amount of time until the predetermined amount of time is within a predetermined range of when the one or more drive lines are scanned by the device.
11. The stylus of claim 10 , wherein the period at which the one or more components are periodically powered on is based at least in part on a frequency at which the device scans the touch-sensor drive lines.
12. The stylus of claim 10 , wherein the drive lines are in the proximity of the stylus based on a motion of the stylus relative to the device.