Normalizing capacitive sensor array signals

Abstract

An embodiment of the present invention is directed to a method for reporting position information. Position information received from a plurality of capacitive sensors in an array of capacitive sensors is adjusted based on predetermined adjustment values to generate adjusted position information. Each predetermined adjustment value is associated with at least one of the plurality of capacitive sensors. A signal representative of the adjusted position information is generated. In another embodiment, the sensitivity of at least one of the capacitive sensors is adjusted based on the position of the at least one capacitive sensor within the array.

What is claimed is: 
     
       1. A method for reporting position information, the method comprising:
 adjusting position information received from a plurality of capacitive sensors in an array of capacitive sensors based on predetermined adjustment values to generate adjusted position information, wherein each predetermined adjustment value is associated with at least one of the plurality of capacitive sensors, and wherein each predetermined adjustment value is derived from a distance between the at least one of the plurality of capacitive sensors and a connection of the array of capacitive sensors; and 
 generating a signal representative of the adjusted position information. 
 
     
     
       2. The method of  claim 1 , wherein each predetermined adjustment value is derived from a position of the at least one of the plurality of capacitive sensors within the array of capacitive sensors. 
     
     
       3. The method of  claim 1 , wherein each predetermined adjustment value is a scalar value, and the predetermined adjustment values are stored in a matrix corresponding to the array of capacitive sensors. 
     
     
       4. The method of  claim 3 , wherein the adjusting of the position information comprises multiplying the position information received from the plurality of capacitive sensors by the respective predetermined adjustment values. 
     
     
       5. The method of  claim 1 , further comprising performing a centroid computation based on the adjust position information. 
     
     
       6. The method of  claim 1 , wherein the array of capacitive sensors comprises a high impedance substrate. 
     
     
       7. A method for reporting position information comprising:
 adjusting the sensitivity of at least one capacitive sensor in a capacitive sensor array based on a distance between the at least one capacitive sensor and a connection of the capacitive sensor array; 
 receiving position information from the at least one capacitive sensor; and 
 generating a signal representative of the position information. 
 
     
     
       8. The method of  claim 7 , further comprising generating the position information with the at least one capacitive sensor, wherein the generating of the position information comprises charging the at least one capacitive sensor based on the operation of a switch. 
     
     
       9. The method of  claim 8 , wherein the operation of the switch is controlled by a pseudo random generator. 
     
     
       10. The method of  claim 7 , wherein the adjusting of the sensitivity of the at least one capacitive sensor comprises adjusting a scan time of the at least one capacitive sensor. 
     
     
       11. The method of  claim 10 , wherein the adjusting of the scan time of the at least one capacitive sensor comprises adjusting a current source coupled to the at least one capacitive sensor. 
     
     
       12. The method of  claim 10 , wherein the adjusting of the scan time of the at least one capacitive sensor comprises adjusting the pulse width modulation of a pulse width modulator. 
     
     
       13. The method of  claim 10 , wherein the at least one capacitive sensor is coupled to a capacitor, and the adjusting of the scan time of the at least one capacitive sensor comprises adjusting a reference voltage to which a voltage across the capacitor is compared. 
     
     
       14. The method of  claim 10 , wherein the at least one capacitive sensor is coupled to a capacitor, and the adjusting of the scan time of the at least one capacitor comprises adjusting the capacitance of the capacitor. 
     
     
       15. A method for reporting position information, the method comprising:
 storing a plurality of predetermined adjustment values, wherein each predetermined adjustment value is associated with at least one of a plurality of capacitive sensors in an array of capacitive sensors, and wherein each predetermined adjustment value is derived from a distance between at least one of the plurality of capacitive sensors and a connection of the array of capacitive sensors; and   generating a signal based on the predetermined adjustment values and received position information.    
     
     
       16. The method of claim 15, wherein generating the signal further comprises adjusting position information received from the plurality of capacitive sensors based on the stored predetermined adjustment values to generate adjusted position information.  
     
     
       17. The method of claim 15, wherein each predetermined adjustment value is a scalar value, and the predetermined adjustment values are stored in a matrix corresponding to the array of capacitive sensors.  
     
     
       18. The method of claim 17, further comprising adjusting the position information by multiplying the received position information by the respective predetermined adjustment values.  
     
     
       19. The method of claim 15, further comprising performing a centroid computation based on the adjusted position information.  
     
     
       20. The method of claim 15, wherein the array of capacitive sensors comprises a high impedance substrate.