Position-Sensing and Force Detection Panel

Abstract

Disclosed is a touch position sensor. Force detection circuitry can be included with the position sensor, for example, to determine an amount of force applied to a touch panel of the sensor.

1 .- 17 . (canceled) 
     
     
         18 . A sensor, comprising:
 a voltage driver operable to provide an alternating voltage;   an integrator circuit;   a first variable resistance element coupled to a first output of the voltage driver and an input of the integrator circuit, wherein the integrator circuit is operable to measure a parameter of the first variable resistance element over a period of time; and   circuitry operable to determine, based on the measured parameter, an amount of force applied to a touch sensing panel.   
     
     
         19 . The sensor of  claim 18 , wherein the parameter is current flowing through the variable resistance element. 
     
     
         20 . The sensor of  claim 18 , further comprising a bias resistance element connected in parallel with the first variable resistance element. 
     
     
         21 . The sensor of  claim 18 , further comprising a limiting resistance element connected in series with the first variable resistance element, 
     
     
         22 . The sensor of  claim 18 , further comprising a second variable resistance element coupled with a second output of the voltage driver and the input of the integrator circuit. 
     
     
         23 . The sensor of  claim 22 , further comprising a bias resistance element connected in parallel with the second variable resistance element. 
     
     
         24 . The sensor of  claim 22 , further comprising a limiting resistance element connected in series with the second variable resistance element. 
     
     
         25 . The sensor of  claim 18 , wherein the first input of the integrator circuit is at a voltage between a first voltage and a second voltage of the alternating voltage provided by the voltage driver. 
     
     
         26 . The sensor of  claim 18 , wherein the circuitry is operable to determine an amount of force applied to the sensor using a differential measurement. 
     
     
         27 . The sensor of  claim 18 , wherein the circuitry is further operable to determine a location in a sensing area of the touch sensing panel associated with the determined amount of force. 
     
     
         28 . A circuit, comprising:
 a voltage driver operable to provide an alternating voltage:   an integrator circuit;   a first resistive force sensitive element coupled to a first output of the voltage driver;   a first bias resistance element connected in parallel with the first resistive force sensitive element; and   a first limiting resistance element connected in series with the first resistive force sensitive element and the first bias resistance element, and coupled to an input of the integrator circuit.   
     
     
         29 . The circuit of claim  38 , further comprising:
 a second resistive force sensitive resistance element coupled to a second output of the voltage driver;   a second bias resistance element connected in parallel with the second resistive force sensitive element; and   a second limiting resistance element connected in series with the second resistive force sensitive element and the second bias resistance element, and coupled to the input of the integrator circuit.