Touch and hover sensing

Abstract

A capacitive sensing apparatus is disclosed. In some examples, the capacitive sensing apparatus includes a sensor control system configured to: during a first scan of the sensor array: transmit a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array, transmit the first AC signal to the first electrode of the sensor array, measure a self capacitance at the first input location, and transmit the second AC signal to the second electrode of the sensor array without measuring a self capacitance at the second input location, and during a second scan of the sensor array: transmit the first AC signal concurrently with the second AC signal to the sensor array, transmit the first AC signal to the first electrode of the sensor array without measuring the self capacitance at the first input location, and measure the self capacitance at the second input location.

What is claimed is: 
     
         1 . A capacitive sensing apparatus comprising:
 a sensor array comprising:   a first electrode at a first input location; and   a second electrode at a second input location adjacent to the first input location; and   a sensor control system configured to:
 during a first scan of the sensor array: 
 transmit the first AC signal to the first electrode of the sensor array; 
 measure a self capacitance at the first input location; and 
 transmit the second AC signal to the second electrode of the sensor array without measuring a self capacitance at the second input location; and 
   during a second scan of the sensor array:
 transmit the first AC signal to the first electrode of the sensor array without measuring the self capacitance at the first input location; and 
 measure the self capacitance at the second input location. 
   
     
     
         2 . The capacitive sensing apparatus of  claim 1 , wherein the sensor control system is further configured to:
 during a third scan of the sensor array:
 transmit the first alternating current (AC) signal concurrently with the second alternating current (AC) signal to the sensor array; 
 transmit the first AC signal to the first electrode of the sensor array; 
 measure the self capacitance at the first input location; 
 transmit the second AC signal to the second electrode of the sensor array; and 
 measure the self capacitance at the first input location. 
   
     
     
         3 . The capacitive sensing apparatus of  claim 1 , wherein the first and second signals have a same voltage. 
     
     
         4 . The capacitive sensing apparatus of  claim 1 , further comprising an AC shield electrode, different from the first electrode and the second electrode. 
     
     
         5 . The capacitive sensing apparatus of  claim 4 , wherein the AC shield is electrically isolated from the sensor array. 
     
     
         6 . The capacitive sensing apparatus of  claim 1 , wherein the first AC signal and the second AC signal are transmitted concurrently. 
     
     
         7 . The capacitive sensing apparatus of  claim 1 , wherein the sensor control system is further configured to:
 during a mutual capacitance scan of the sensor array:
 transmit the first AC signal to the first electrode of the sensor array; 
 measure a mutual capacitance at the first input location; 
 transmit the second AC to the second electrode of the sensor array; and 
 measure the mutual capacitance at the second input location. 
   
     
     
         8 . The capacitive sensing apparatus of  claim 1 , wherein the first AC signal has a waveform and the second AC signal is generated from a buffered copy of the waveform. 
     
     
         9 . A method comprising:
 during a first scan of a sensor array:
 transmitting a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array; 
 transmitting the first AC signal to a first electrode of the sensor array at a first input location; 
 measuring a self capacitance at the first input location; and 
 transmitting the second AC signal to a second electrode of the sensor array at a second input location without measuring a self capacitance at the second input location, the second input location different from the first input location; and 
   during a second scan of the sensor array:
 transmitting the first AC signal concurrently with the second AC signal to the sensor array; 
 transmitting the first AC signal to the first electrode of the sensor array without measuring the self capacitance at the first input location; and 
 measuring the self capacitance at the second input location. 
   
     
     
         10 . The method of  claim 9 , further comprising:
 during a third scan of the sensor array:
 transmitting a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array; 
 transmitting the first AC signal to the first electrode of the sensor array; 
 measuring the self capacitance at the first input location; 
 transmitting the second AC signal to the second electrode of the sensor array; and 
 measuring the self capacitance at the first input location. 
   
     
     
         11 . The method of  claim 9 , wherein the first and second signals have a same voltage. 
     
     
         12 . The method of  claim 9 , wherein the sensor array comprises an AC shield electrode, different from the first electrode and the second electrode. 
     
     
         13 . The method of  claim 12 , wherein the AC shield is electrically isolated from the sensor array. 
     
     
         14 . The method of  claim 12 , wherein the first AC signal and the second AC signal are transmitted concurrently. 
     
     
         15 . The method of  claim 9 , further comprising:
 during a mutual capacitance scan of the sensor array:
 transmitting the first AC signal to the first electrode of the sensor array; 
 measuring a mutual capacitance at the first input location; 
 transmitting the second AC to the second electrode of the sensor array; and 
 measuring the mutual capacitance at the second input location. 
   
     
     
         16 . The method of  claim 9 , wherein the first AC signal has a waveform and the second AC signal is generated from a buffered copy of the waveform. 
     
     
         17 . A non-transitory computer-readable storage medium having stored therein instructions, which when executed by a processor cause the processor to perform a method comprising:
 during a first scan of a sensor array:
 transmitting a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array; 
 transmitting the first AC signal to a first electrode of the sensor array at a first input location; 
 measuring a self capacitance at the first input location; and 
 transmitting the second AC signal to a second electrode of the sensor array at a second input location without measuring a self capacitance at the second input location, the second input location different from the first input location; and 
   during a second scan of the sensor array:
 transmitting the first AC signal concurrently with the second AC signal to the sensor array; 
 transmitting the first AC signal to the first electrode of the sensor array without measuring the self capacitance at the first input location; and 
 measuring the self capacitance at the second input location. 
   
     
     
         18 . The non-transitory computer readable medium of  claim 17 , the method further comprising:
 during a third scan of the sensor array:
 transmitting a first alternating current (AC) signal concurrently with a second alternating current (AC) signal to the sensor array; 
 transmitting the first AC signal to the first electrode of the sensor array; 
 measuring the self capacitance at the first input location; 
 transmitting the second AC signal to the second electrode of the sensor array; and 
 measuring the self capacitance at the first input location. 
   
     
     
         19 . The non-transitory computer readable medium of  claim 17 , wherein the sensor array comprises an AC shield electrode, different from the first electrode and the second electrode. 
     
     
         20 . The non-transitory computer readable medium of  claim 17 , wherein the first AC signal has a waveform and the second AC signal is generated from a buffered copy of the waveform.