Changing the detection range of a touch sensor

Abstract

A device includes a touch sensor and a touch-sensor controller. The touch-sensor may receive a signal associated with an operation of the device; in response to the signal, determine that a detection mode of the touch sensor associated with the device is to be changed, and in response to the determination, increase sensitivity of a first portion, but not all, of the touch sensor. A first portion of increased sensitivity may be an area of the touch sensor associated with a button. A first portion of increased sensitivity may be the top right portion of the touch sensor. In other examples, sensitivity may be decreased when an operation is a game played by a user on the device, a voicemail operation on the device, or an operation requiring an ear or face of a user to contact the touch sensor.

What is claimed is: 
     
         1 . A device comprising:
 a touch sensor;   a touch-sensor controller coupled to the touch sensor and configured to:
 receive a signal associated with an operation of the device; 
 in response to the signal, determine that a detection mode of the touch sensor associated with the device is to be changed; and 
 in response to the determination, increase sensitivity of a first portion, but not all, of the touch sensor. 
   
     
     
         2 . The device of  claim 1 , wherein the first portion of increased sensitivity is an area of the touch sensor associated with a button. 
     
     
         3 . The device of  claim 1 , wherein the touch sensor comprises an approximately rectangular area including a top right portion and the first portion of increased sensitivity is located in the top right portion of the touch sensor. 
     
     
         4 . The device of  claim 1 , wherein the touch sensor includes a first plurality of electrodes oriented in a first direction in the first portion of the touch sensor, a second plurality of electrodes oriented in the first direction in a second portion of the touch sensor outside the first portion, and a third plurality of electrodes intersecting the first and second plurality of electrodes. 
     
     
         5 . The device of  claim 4 , wherein the touch-sensor controller is further configured to drive the first and the third plurality of electrodes such that intersections between the first and third electrodes have a potential greater than ground to increase a detection range in the first portion of the touch sensor, wherein an increase in the detection range increases a projection of electrical field lines from the touch sensor. 
     
     
         6 . The device of  claim 5 , further comprising a ground connector, wherein the touch-sensor controller is further configured to couple at least some of the second electrodes to the ground connector such that respective intersections between the at least some of the second and third electrodes are connected to ground to decrease a detection range in the second portion of the touch sensor, wherein a decrease in the detection range decreases a projection of electrical field lines from the touch sensor. 
     
     
         7 . The device of  claim 7 , wherein the at least some of the second and the third plurality of electrodes comprises every odd or even electrode in the plurality of second electrodes. 
     
     
         8 . The device of  claim 7 , wherein the at least some of the second and the third plurality of electrodes comprises every third electrode in the plurality of second electrodes. 
     
     
         9 . The device of  claim 7 , wherein the operation comprises a game played by a user on the device and the touch-sensor controller is configured to in response to the determination couple at least some of the second electrodes to the ground connector. 
     
     
         10 . The device of  claim 7 , wherein the operation comprises a voicemail operation on the device and the touch-sensor controller is configured to in response to the determination couple at least some of the second electrodes to the ground connector. 
     
     
         11 . The device of  claim 7 , wherein the operation comprises an operation requiring an ear or face of a user to contact the touch sensor and the touch-sensor controller is configured to in response to the determination couple at least some of the second electrodes to the ground connector. 
     
     
         12 . A device comprising:
 a touch sensor;   a touch-sensor controller coupled to the touch sensor and configured to:
 receive a signal associated with an operation of the device; 
 in response to the signal, determine that a detection mode of the touch sensor associated with the device is to be changed; and 
 in response to the determination, decrease sensitivity of a portion, but not all, of the touch sensor. 
   
     
     
         13 . The device of  claim 12 , wherein the operation comprises a game played by a user on the device, and wherein the touch-sensor controller is configured to in response to the determination decrease the sensitivity of the portion of the touch sensor. 
     
     
         14 . The device of  claim 12 , wherein the operation comprises a voicemail operation on the device, and wherein the touch-sensor controller is configured to in response to the determination decrease the sensitivity of the portion of the touch sensor. 
     
     
         15 . The device of  claim 12 , wherein the operation comprises an operation requiring an ear or face of a user to contact the touch sensor, and wherein the touch-sensor controller is configured to in response to the determination decrease the sensitivity of the portion of the touch sensor. 
     
     
         16 . A device comprising:
 a touch sensor having a plurality of electrodes;   a storage unit; and   a processor unit coupled to the storage unit and configured to:
 receive a signal associated with an operation of the device; 
 in response to the signal, determine that a detection mode of the touch sensor associated with the device is to be changed; and 
 in response to the determination, increase sensitivity of a first portion, but not all, of the touch sensor. 
   
     
     
         17 . The device of  claim 16 , wherein the first portion of increased sensitivity is an area of the touch sensor associated with a button. 
     
     
         18 . The device of  claim 16 , wherein the touch sensor comprises an approximately rectangular area including a top right portion and the first portion of increased sensitivity is located in the top right portion of the touch sensor. 
     
     
         19 . The device of  claim 16 , further comprising a drive unit coupled to drive electrodes in the plurality of electrodes and wherein the processor unit is configured to control a supply of drive signals to the drive unit. 
     
     
         20 . The device of  claim 16 , wherein the touch sensor includes capacitive nodes and further comprising a sense unit configured to sense charge at the capacitive nodes of the touch sensor and output measurement signals to the processor unit.