Method for stylus touch-down and lift-off noise mitigation

Patent metadata

Field	Value
Publication number	US-2016378208-A1
Application number	US-201514751057-A
Country	US
Kind code	A1
Filing date	Jun 25, 2015
Priority date	Jun 25, 2015
Publication date	Dec 29, 2016
Grant date	—

Abstract

Active styli, methods and non-transitory computer readable storage media can be used for mitigating noise coupling from an active stylus to a touch sensing system. An active stylus can include a force sensor that can be used to detect stylus touch-down and lift-off events. Based on a touch-down and lift-off events, the stylus can generate stimulation signals and ramp up or ramp down the amplitude of the stimulation signals. Additionally or alternatively, an active stylus can receive information to synchronize the active stylus with a touch-sensitive device. Based on the information, the stylus can synchronize generation of stimulation signals with the stylus scan performed by the touch-sensitive device. The stimulation signals can be ramped up during a guard band period before a stylus scan and can be ramped down during a guard band period after the stylus scan.

First claim

What is claimed is:

1 . A method of mitigating noise from a stylus, the method comprising:
detecting a first event, the first event associated with generation of one or more stimulation signals by the stylus; and in response to detecting the first event, ramping up an amplitude of the stimulation signals until a desired amplitude is reached.

2 . The method of claim 1 , further comprising:
detecting a second event, the second event associated with cessation of the generation of the stimulation signals by the stylus; and in response to detecting the second event, ramping down the amplitude of the stimulation signals.

3 . The method of claim 1 , wherein detecting the first event comprises detecting a contact between the stylus and a surface.

4 . The method of claim 3 , wherein the stylus comprises a force sensor and detecting the contact between the stylus and the surface comprises detecting a force measured by the force sensor meets a threshold amount of force.

5 . The method of claim 2 , wherein detecting the second event comprises detecting a break in contact between the stylus and a surface.

6 . The method of claim 5 , wherein the stylus comprises a force sensor and detecting the break in the contact between the stylus and the surface comprises detecting a force measured by the force sensor fails to meet a threshold amount of force.

7 . The method of claim 1 , wherein detecting the first event comprises predicting a start of a scan for an active stylus by a touch-sensing device based on at least one of clock signal synchronized with the touch-sensing device and a scan plan transmitted to the stylus from the touch-sensing device.

8 . The method of claim 7 , wherein ramping up the amplitude of the stimulation signals begins during a guard band period before the start of the scan for the active stylus.

9 . The method of claim 2 , wherein detecting the second event comprises predicting an end of a scan for an active stylus by a touch-sensing device based on at least one of a clock signal synchronized with the touch-sensing device and a scan plan transmitted to the stylus from the touch-sensing device.

10 . The method of claim 1 , wherein ramping up the amplitude of the stimulation signals is based one or more of an amplitude parameter and a timing parameter.

11 . The method of claim 1 , further comprising:
detecting a second event, the second event associated with cessation of generation of the stimulation signals by the stylus; and in response to detecting the second event, continuing generating the stimulation signals for a threshold period of time without ramping down the amplitude of the stimulation signals before stopping generating the stimulation signals.

12 . An active stylus comprising;
one or more electrodes; stimulation circuitry coupled to the one or more electrodes and configured to generate one or more stimulation signals; and a processor coupled to the stimulation circuitry and capable of causing the stimulation circuitry to generate the stimulation signals and to ramp up or ramp down an amplitude of the stimulation signals.

13 . The active stylus of claim 12 , further comprising:
a force sensor coupled to the processor; wherein the processor is further capable of causing the stimulation circuitry to generate the stimulation signals and to ramp up or ramp down the amplitude of the stimulation signals based on a force detected by the force sensor.

14 . The active stylus of claim 13 , wherein the processor is further capable of causing the stimulation circuitry to ramp up the amplitude of the stimulation signals when the force detected by the force sensor meets or exceeds a first threshold and causing the stimulation circuitry to ramp down the amplitude of the stimulation signals when the force detected by the force sensor falls below a second threshold.

15 . The active stylus of claim 13 , wherein the processor is further capable of causing the stimulation circuitry to ramp up the amplitude of the stimulation signals when the force detected by the force sensor meets or exceeds a first threshold and causing the stimulation circuitry to stop generating the stimulation signals a threshold period of time after the force detected by the force sensor falls below a second threshold.

16 . The active stylus of claim 12 , wherein the processor is further capable of causing the stimulation circuitry to generate the stimulation signals and to ramp up or ramp down the amplitude of the stimulation signals based on one or more of a synchronized clock and a scan plan.

17 . The active stylus of claim 16 , wherein ramping up or ramping down the amplitude of the stimulation signal begins during a guard band period before a start of or an end of a scan for the active stylus by a touch-sensitive device.

18 . The active stylus of claim 12 , wherein the processor is further capable of communicating one or more of an amplitude parameter and a timing parameter to the stimulation circuitry, and wherein the stimulation circuitry is configured to ramp up or ramp down the amplitude of the stimulation signals based on the one or more of the amplitude parameter and the timing parameter.

19 . The active stylus of claim 12 , wherein the processor is further capable of communicating a plurality of amplitude parameters to the stimulation circuitry, and wherein the stimulation circuitry is configured to ramp up or ramp down the amplitude based on the plurality of amplitude parameters.

20 . A non-transitory computer readable storage medium having stored thereon a set of instructions for generating one or more stimulation signals, that when executed by a processor causes the processor to:
detect a first event, the first event associated with generation of the stimulation signals by the stylus; in response to detecting the first event, ramp up an amplitude of the stimulation signals until a desired amplitude is reached; detect a second event, the second event associated with cessation of generation of the stimulation signals by the stylus; and in response to detecting the second event, ramp down the amplitude of the stimulation signals.

21 . The non-transitory computer readable storage medium of claim 20 , wherein detecting the first event comprises detecting a contact between the stylus and a surface, and wherein detecting the second event comprises detecting a break in contact between the stylus and the surface.

22 . The non-transitory computer readable storage medium of claim 21 , wherein the stylus comprises a force sensor, wherein detecting the contact between the stylus and the surface comprises detecting a force measured by the force sensor meets a first threshold amount of force, and detecting the break in the contact between the stylus and the surface comprises detecting the force measured by the force sensor falls below a second threshold amount of force.

23 . The non-transitory computer readable storage medium of claim 20 , wherein detecting the first event comprises predicting a start of a scan for an active stylus by a touch-sensing device based on one or more of a clock signal synchronized with the touch-sensing device and a scan plan transmitted to the stylus from the touch-sensing device, and wherein detecting the second event comprises predicting an end of the scan for the active stylus by the touch-sensing device based on the one or more of the clock signal synchronized with the touch-sensing device and the scan

Assignees

• Apple Inc

Inventors

• Shahparnia Shahrooz
• Pant Vivek

Classifications

• G06F3/03545 Primary

  Pens or stylus · CPC title

• G06F3/0383

  Signal control means within the pointing device · CPC title

• G06F3/0418

  for error correction or compensation, e.g. based on parallax, calibration or alignment · CPC title

• G06F3/0414

  using force sensing means to determine a position · CPC title

• G06F3/0412

  Digitisers structurally integrated in a display · CPC title