Sense Electrode Design

Abstract

A touch sensitive device includes a plurality of sense electrodes arranged in a pattern to receive charge from drive electrodes. The pattern of sense electrodes has extreme portions having worst case charge transfer times, wherein the worst case charge transfer time at multiple extreme portions is substantially equal.

1 . (canceled) 
     
     
         2 . A touch sensitive device comprising:
 a layer of longitudinal adjacent drive electrodes separated from each other by a gap, the layer of longitudinal adjacent drive electrodes to be positioned above a display; and   a layer of sense electrodes, the sense electrodes formed in the shape of spines running transverse to the drive electrodes and having a plurality crossbars running in the same direction as the drive electrodes, each spine coupled to sense circuitry at at least one end,   wherein at least the spine or a subset of two or more bars of the plurality of crossbars of each sense electrode increases in width with distance from an end coupled to sense circuitry such that at least one spine of the subset exhibits a worst case charge transfer time and other spines of the subset exhibit a charge transfer time that is equal to or less than the worst case charge transfer time.   
     
     
         3 . The touch sensitive device of  claim 2  wherein the sense electrodes are formed of a transparent conductive material. 
     
     
         4 . The touch sensitive device of  claim 2  wherein each crossbar on a spine has at least one tip that is furthest from the spine, and wherein a worst case charge transfer time from the tips to one of the two ends of the spine to couple to sense circuitry does not exceed a predetermined threshold. 
     
     
         5 . The touch sensitive device of  claim 4  wherein the predetermined threshold is determined to ensure a desired charge transfer time is not exceeded. 
     
     
         6 . The touch sensitive device of  claim 4  wherein the worst case charge transfer time to each tip is substantially equal. 
     
     
         7 . The touch sensitive device of  claim 2  wherein the spines each have first and second ends, both of which are adapted to couple to the sense circuitry. 
     
     
         8 . A method comprising:
 forming a layer of longitudinal adjacent drive electrodes separated from each other by a gap, the layer of longitudinal adjacent drive electrodes to be positioned above a display; and   a layer of sense electrodes in the shape of spines running transverse to the drive electrodes and having a plurality crossbars running in the same direction as the drive electrodes, each spine coupled to sense circuitry at at least one end,   wherein at least the spine or a subset of two or more bars of the plurality of crossbars of each sense electrode increases in width with distance from an end coupled to sense circuitry such that at least one spine of the subset exhibits a worst case charge transfer time and other spines of the subset exhibit a charge transfer time that is equal to or less than the worst case charge transfer time.   
     
     
         9 . The method of  claim 8  wherein the sense electrodes are formed of a transparent conductive material. 
     
     
         10 . The method of  claim 8  wherein each crossbar on a spine has at least one tip that is furthest from the spine, and wherein a worst case charge transfer time from the tips to one of the two ends of the spine to couple to sense circuitry does not exceed a predetermined threshold. 
     
     
         11 . The method of  claim 10  wherein the predetermined threshold is determined to ensure a desired charge transfer time is not exceeded. 
     
     
         12 . The method of  claim 10  wherein the worst case charge transfer time to each tip is substantially equal. 
     
     
         13 . The method of  claim 8  wherein the spines each have first and second ends, both of which are adapted to couple to the sense circuitry.