Compensation of signal values for a touch sensor

• US 8,482,536 B1
• Filed: 07/23/2009
• Issued: 07/09/2013
• Est. Priority Date: 07/23/2008
• Status: Expired due to Fees

• Current Assignee: Monterey Research, LLC (Vector Capital Corporation)
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Young, David
• Primary Examiner(s): SHENG, TOM V
• Application Number:
  US12/508,487
• Time in Patent Office: 1,447 Days
• Field of Search: 345/173, 345/174, 345/175, 178 1803- 1809, 715/863, 715/864
• US Class Current: 345/173
• CPC Class Codes: G06F 3/0418 for error correction or compensation, e.g. based on parallax, calibration or alignment
• CPC Class Codes: G06F 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes

Abstract

An apparatus includes a data conditioning module configured to translate each of a plurality of signal strength values to a compensated signal value, where the compensated signal value is a function of its corresponding signal strength value.

Claims

1. An apparatus, comprising:

an input configured to receive a plurality of signal strength values from a touch sensor including a plurality of sensor elements; and

a data conditioning module coupled with the input, wherein the data conditioning module is configured to generate a set of compensated signal values, wherein the set of compensated signal values has a reduced dynamic range relative to the dynamic range of the plurality of signal strength values, by using a multiplier function to translate each of the plurality of signal strength values to a compensated signal value, wherein the compensated signal value is a function of its corresponding signal strength value, and wherein a signal strength value measured from each sensor element of the plurality of sensor elements is used to generate one of the plurality of compensated signal values based on a position of an object relative to the sensor element.

2. The apparatus of claim 1, wherein the touch sensor includes the plurality of sensor elements configured to generate the plurality of signal strength values.

3. The apparatus of claim 1, wherein each of the plurality of signal strength values represents a capacitance of a sensor element generating the signal strength value.

4. The apparatus of claim 1, wherein the one of the plurality of compensated signal values is related to the position of the object according to an approximately Gaussian function.

5. The apparatus of claim 1, wherein a function relating the position of the object to the compensated signal value as compressed has a decreased maximum slope relative to a function relating the position of the object to the signal strength value.

6. The apparatus of claim 1, wherein the data conditioning module is further configured to calculate a centroid based on the plurality of compensated signal values, wherein the centroid represents a location of an input at the touch sensor.

7. The apparatus of claim 6, wherein the centroid identifies a location on a display according to a pixel coordinate system.

8. The apparatus of claim 6, wherein the centroid identifies a location in a linear coordinate system.

9. The apparatus of claim 1, further comprising a lookup table coupled with the data conditioning module, wherein the data conditioning module is further configured to translate each of the plurality of signal strength values to a compensated signal value by querying the lookup table.

10. A method, comprising:

receiving a plurality of signal strength values from a touch sensor including a plurality of sensor elements; and

using a multiplier function to generate a set of compensated signal values by translating each of the plurality of signal strength values to a compensated signal value, wherein the compensated signal value is a function of its corresponding signal strength value, wherein the dynamic range of the set of compensated signal values is reduced relative to the dynamic range of the plurality of signal strength values, and wherein a signal strength value measured from each sensor element of the plurality of sensor elements is used to generate one of the plurality of compensated signal values based on a position of an object relative to the sensor element.

11. The method of claim 10, wherein the touch sensor includes the plurality of sensor elements configured to generate the plurality of signal strength values.

12. The method of claim 10, wherein each of the plurality of signal strength values represents a capacitance of a sensor element generating the signal strength value.

13. The method of claim 10, wherein the compensated signal value is related to the position of the object according to an approximately Gaussian function.

14. The method of claim 10, wherein a function relating the position of the object to the compressed signal value has a decreased maximum slope relative to a function relating the position of the object to the signal strength value.

15. The method of claim 10, further comprising calculating a centroid based on the plurality of signal strength values, wherein the centroid represents a location of an input at the touch sensor.

16. The method of claim 15, wherein the centroid identifies a location on a display according to a pixel coordinate system.

17. The method of claim 15, wherein the centroid identifies a location in a linear coordinate system.

18. The method of claim 10, wherein the translating comprises querying a lookup table.