Asymmetric Multi-Row Touch Panel Scanning

Abstract

Asymmetric scanning logic implements asymmetric panel scanning by scanning some rows on a touch panel more frequently than other rows. Note that although an entire row at a time may be driven, if only particular pixels in the row are of interest (e.g., included in any region of interest for focused asymmetric scanning), then circuitry may power down the receivers for the columns in which the pixels exist to save power. The asymmetric scanning logic facilitates focused attention to specific areas of interest on the touch panel, to compensate, for example, for high noise or low signal strength in those areas of interest.

1 .- 20 . (canceled) 
     
     
         21 . A device comprising:
 a touch panel interface configured to communicate with a touch panel;   memory configured to store a scan map, the scan map configured to:
 define a first scan frequency for a first region of the touch panel; and 
 define a second scan frequency for a second region of the touch panel, the second scan frequency different from the first scan frequency; and 
   scan control circuitry in communication with the touch panel interface and the memory, the scan control circuitry configured to:
 access the scan map to determine the first and second scan frequencies; and 
 responsive to the scan map:
 scan the first region of the touch panel at the first frequency; and 
 scan the second region of the touch panel at the second frequency. 
 
   
     
     
         22 . The device of  claim 21 , where:
 the first region comprises a first set of rows of the touch panel; and   the second region comprises a second set of rows of the touch panel.   
     
     
         23 . The device of  claim 22 , where:
 the first set of rows is larger than the second set of rows; and   the first frequency is greater than the second frequency.   
     
     
         24 . The device of  claim 21 , where:
 the scan map comprises step scans, the step scans are configured to form a repeating scan order for the touch panel;   the scan map is configured to define the first and second scan frequencies by:   defining a first number the step scans for the first region; and   defining a second number the step scans for the second region.   
     
     
         25 . The device of  claim 21 , where the scan control circuitry is further configured to:
 receive noise information for the touch panel; and   responsive to the noise information, determine to adjust the first scan frequency, the second scan frequency, or both.   
     
     
         26 . The device of  claim 25 , where the noise information comprises a captured signal-to-noise ratio (SNR) for the first region. 
     
     
         27 . The device of  claim 26 , where the scan control circuitry is configured determine to adjust the first scan frequency by comparing the captured SNR to a target SNR stored in the memory. 
     
     
         28 . A method comprising:
 responsive to a scan map stored in memory, determining a first scan frequency for a first region of a touch panel;   responsive to the scan map, determining a second scan frequency for a second region of the touch panel;   scanning the first region of the touch panel at the first scan frequency; and   scanning the second region of the touch panel at the second scan frequency.   
     
     
         29 . The method of  claim 28 , where:
 determining the first scan frequency comprises determining a first number of step scans for the first region; and   determining the second scan frequency comprises determining a second number of step scans for the second region.   
     
     
         30 . The method of  claim 28 , further comprising receiving noise information for the touch panel. 
     
     
         31 . The method of  claim 30 , further comprising:
 responsive to the noise information, determining to adjust the first scan frequency, the second scan frequency, or both.   
     
     
         32 . The method of  claim 31 , where the noise information comprises a captured signal-to-noise ratio (SNR) for the first region. 
     
     
         33 . The method of  claim 32 , further comprising adjusting the first scan frequency responsive to a comparison of the captured SNR to a stored target SNR. 
     
     
         34 . The method of  claim 31 , further comprising adjusting the first scan frequency;
 where:   the noise information comprises a noise estimate for the second region;   the first region comprises an active region of the touch panel, the active region of the touch panel comprising a region where a touch is currently sensed; and   the second region comprises a non-active region of the touch panel.   
     
     
         35 . A device comprising:
 a touch panel interface configured to communicate with a touch panel;   memory configured to store a scan map, the scan map configured to define scan frequencies for panel regions of the touch panel; and   scan control circuitry in communication with the touch panel interface and the memory,   the scan control circuitry configured to:
 scan the touch panel in accord with the scan map; 
 responsive to the scan, receive noise information for touch panel; and 
 determine to adjust a first scan frequency for a first region of the touch panel among the panel regions, responsive to the noise information. 
   
     
     
         36 . The device of  claim 35 , where the noise information comprises a determined signal-to-noise ratio (SNR) for the first region. 
     
     
         37 . The device of  claim 36 , where the scan control circuitry is configured to determine to adjust the first scan frequency by comparing the determined SNR to a target SNR. 
     
     
         38 . The device of  claim 37 , where:
 the determined SNR is greater than the target SNR; and   the scan control circuitry is further configured to adjust the first scan frequency by reducing the first scan frequency.   
     
     
         39 . The device of  claim 37 , where the scan control circuitry is further configured to adjust the first scan frequency by increasing a number of step scans in the scan map for the first region. 
     
     
         40 . The device of  claim 35 , where:
 the first region comprises an active region of the touch panel, the active region of the touch panel comprising a region where a touch is currently sensed; and   the noise information comprises a noise estimate for a non-active region of the touch panel.