Active Stylus with Filter

Abstract

In one embodiment, a method includes receiving at a stylus a receive signal from a device. The stylus includes one or more computer-readable media embodying logic, and the device includes a touch sensor. The receive signal is received at the stylus through the touch sensor of the device and one or more electrodes of the stylus. The method includes filtering the receive signal for processing by the logic and processing, by the logic, the receive signal as filtered.

What is claimed is: 
     
         1 . A method comprising:
 receiving at a stylus a receive signal from a device, the stylus comprising one or more computer-readable media embodying logic, the device comprising a touch sensor, the receive signal being received at the stylus through the touch sensor of the device and one or more electrodes of the stylus;   filtering the receive signal for processing by the logic; and   processing by the logic the receive signal as filtered.   
     
     
         2 . The method of  claim 1 , wherein the filtering comprises applying a non-linear function to the receive signal. 
     
     
         3 . The method of  claim 2 , wherein the non-linear function disproportionately amplifies low-amplitude signals. 
     
     
         4 . The method of  claim 1 , wherein the filtering comprises applying a proportional gain function to the receive signal. 
     
     
         5 . The method of  claim 1 , wherein one or more of the electrodes of the stylus are disposed on or in a tip of the stylus. 
     
     
         6 . The method of claim of  1 , further comprising:
 if the receive signal has an amplitude between a first pre-determined threshold and a second pre-determined threshold, then transmitting from the stylus to the device a transmit signal that is a first function of the receive signal as filtered; and   if the receive signal has an amplitude exceeding a first pre-determined threshold and exceeding a second pre-determined threshold, then transmitting from the stylus to the device a transmit signal that is a second function of the receive signal as filtered.   
     
     
         7 . The method of  claim 6 , wherein at least one of the functions is non-linear. 
     
     
         8 . The method of  claim 6 , wherein at least one of the functions comprises:
 changing a phase of the receive signal as filtered; or   multiplying by a factor the receive signal as filtered.   
     
     
         9 . The method of  claim 6 , further comprising, if the stylus touches the device, then transmitting from the stylus to the device a transmit signal that is a third function of the receive signal as filtered. 
     
     
         10 . The method of  claim 1 , further comprising dynamically adjusting the filtering based at least in part on the receive signal. 
     
     
         11 . One or more computer-readable non-transitory storage media embodying logic that is operable when executed to:
 receive at a stylus a receive signal from a device, the stylus comprising the media, the device comprising a touch sensor, the receive signal being received at the stylus through the touch sensor of the device and one or more electrodes of the stylus;   filter the receive signal for processing by the logic; and   process the receive signal as filtered.   
     
     
         12 . The media of  claim 11 , wherein the filtering comprises applying a non-linear function to the receive signal. 
     
     
         13 . The media of  claim 12 , wherein the non-linear function disproportionately amplifies low-amplitude signals. 
     
     
         14 . The media of  claim 11 , wherein the filtering comprises applying a proportional gain function to the receive signal. 
     
     
         15 . The media of  claim 11 , wherein one or more of the electrodes of the stylus are disposed on or in a tip of the stylus. 
     
     
         16 . The media of claim of  11 , wherein the logic is further operable when executed to:
 if the receive signal has an amplitude between a first pre-determined threshold and a second pre-determined threshold, then transmit from the stylus to the device a transmit signal that is a first function of the receive signal as filtered; and   if the receive signal has an amplitude exceeding a first pre-determined threshold and exceeding a second pre-determined threshold, then transmit from the stylus to the device a transmit signal that is a second function of the receive signal as filtered.   
     
     
         17 . The media of  claim 16 , wherein at least one of the functions is non-linear. 
     
     
         18 . The media of  claim 16 , wherein at least one of the functions comprises:
 changing a phase of the receive signal as filtered; or   multiplying by a factor the receive signal as filtered.   
     
     
         19 . The media of  claim 16 , wherein the logic is further operable when executed to, if the stylus touches the device, then transmit from the stylus to the device a transmit signal that is a third function of the receive signal as filtered. 
     
     
         20 . The media of  claim 11 , wherein the logic is further operable when executed to dynamically adjust the filtering based at least in part on the receive signal.