Fast multi-touch noise reduction

Abstract

A low-latency touch sensitive device provides a method for determining a location of a touch event thereon. The touch sensitive device row conductors and column conductors, the path of each of the row conductors crossing the path of each of the column conductors. Each of a set of orthogonal row signals are simultaneously transmitted on a respective one of at least some of the row conductors and an amount of each of the plurality of orthogonal row signals present on each of the plurality of column conductors is detected. A set of orthogonal column signals are simultaneously transmitted on a respective one of at least some of the column conductors. An amount of each of the orthogonal column signals present on each of the plurality of row conductors is detected. The detected amount of each of the plurality of orthogonal row signals and the detected amount of each of the plurality of orthogonal column signals is used to determine the location of a touch event on the device.

1 . A device comprising:
 signal generator adapted to generate a plurality of unique orthogonal signals, each unique orthogonal signal being orthogonal to each of the other unique orthogonal signals;   signal processor being adapted to decode the signals present during each of a plurality of successive measurement periods, and for each of the signals present for each of the plurality of successive measurement periods, to determine a measurement corresponding to each of the unique orthogonal signals, the signal processor outputting an event stream comprising usable touch events, the event stream based on the measurements made for each of the plurality of successive measurement periods; and   decimator operatively connected to the event stream, the decimator adapted to decimate the event stream and produce at least one output stream comprising usable events, the output stream being for use by the device.   
     
     
         2 . The device of  claim 1 , wherein the decimator is configured to receive GUI element boundary information from software running on the device and use the GUI element boundary information to change a decimation scheme. 
     
     
         3 . The device of  claim 2 , wherein the decimation scheme comprises a scheme by which the decimator determines whether to generate events and add the generated events to the stream. 
     
     
         4 . The device of  claim 2 , wherein the decimator is configured to use the GUI element boundary information to include in the modified stream a first event that is outside a GUI element. 
     
     
         5 . The device of  claim 1 , wherein the decimator is configured to select a decimation scheme based on a determination of a type of input device being used. 
     
     
         6 . The device of  claim 1 , wherein the decimator is configured to select a decimation scheme based on an identification of a user associated with an event in the event stream. 
     
     
         7 . The device of  claim 1 , wherein the decimator is configured to sample the event stream at every N input events such that at least one of the at least one output stream includes every Nth usable event from the event stream. 
     
     
         8 . The device of  claim 7 , configured such that N is a tunable parameter. 
     
     
         9 . The device of  claim 1 , wherein the decimator is configured to sample the event stream at every X microseconds such that at least one of the at least one output stream includes usable events from the event stream that occurred every X microseconds. 
     
     
         10 . The device of  claim 9 , configured such that X is a tunable parameter. 
     
     
         11 . The device of  claim 1 , wherein the decimator is configured to sample the event stream such that at least one of the at least one output stream includes events that represent meaningful changes in curvature of motion represented by the event stream. 
     
     
         12 . The device of  claim 1 , wherein the decimator is configured to sample the event stream such that at least one of the at least one output stream includes events that represent meaningful changes in velocity of motion represented by the event stream. 
     
     
         13 . The device of  claim 1 , wherein the decimator is configured to sample the event stream such that at least one of the at least one output stream includes events that represent meaningful changes in pressure represented by the event stream. 
     
     
         14 . The device of  claim 1 , wherein the decimator is configured to sample the event stream such that at least one of the at least one output stream includes events that represent meaningful changes in number of usable events represented by the event stream. 
     
     
         15 . The device of  claim 1 , wherein the decimator is configured to use a different decimation scheme when a specified input mode is active. 
     
     
         16 . A touch sensitive device having a touch interface comprising, signal generator for generating a plurality of signals and transmitting the plurality of signals, touch processor for identifying touch by processing touch signals present and outputting an event stream of usable touch events, the touch sensitive device comprising:
 decimator that receives the stream of usable touch events, generates one or more estimated touch events based at least in part upon the event stream, and outputs a modified stream of usable touch events for use by the touch sensitive device, wherein the modified stream of useable touch events includes the one or more estimated touch events.   
     
     
         17 . The touch sensitive device of  claim 16 , wherein the decimator additionally outputs an additional stream of usable touch events. 
     
     
         18 . The touch sensitive device of  claim 17 , wherein the additional stream of usable touch events comprises at least some of the usable touch events in the stream of usable touch events. 
     
     
         19 . A device having a signal generator for generating a plurality of signals and transmitting one of the plurality of signals, and a processor for identifying events by processing signals and outputting an event stream of usable events, the device comprising:
 decimator that receives the stream of usable events, generates one or more predicted events based at least in part upon the event stream, and outputs a modified stream of usable events for use by the device, wherein the modified stream of useable events includes the one or more predicted events.   
     
     
         20 . The device of  claim 19 , wherein the prediction is an estimate of a future event.