CLOSED-LOOP SENSOR ON A SOLID-STATE OBJECT POSITION DETECTOR

• US 20080041642A1
• Filed: 10/26/2007
• Published: 02/21/2008
• Est. Priority Date: 04/11/2002
• Status: Active Grant

• Current Assignee: Wacom Co Limited (Wacom)
• Original Assignee: Synaptics Incorporated
• Inventors: Huie, Mark, GILLESPIE, David, SHAW, Scott, TRENT, Raymond, HEINY, Christopher
• Granted Patent: US 7,609,253 B2
• Time in Patent Office: Days
• US Class Current: 178/18.06
• CPC Class Codes: G06F 2203/0339 Touch strips, e.g. orthogonal touch strips to control cursor movement or scrolling; single touch strip to adjust parameter or to implement a row of soft keys
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• CPC Class Codes: G06F 3/0448 Details of the electrode shape, e.g. for enhancing the detection of touches, for generating specific electric field shapes, for enhancing display quality

Abstract

The present disclosure discloses an object position detector. The object position detector comprises a touch sensor formed as a closed loop and having a physical constraint formed on an upper surface of the touch sensor and coextensive with the closed loop. The touch sensor is configured to sense motion of an object proximate to the closed loop. The object position detector also comprises a processor coupled to the touch sensor and is programmed to generate an action in response to the motion on the touch sensor.

Claims

1. A method for processing signals from a plurality of sensor electrodes in a closed loop sensor device comprising:

receiving a set of signals, the set of signals comprising a signal from each of the plurality of sensor electrodes in the closed loop sensor device;

determining a set of capacitance values, the set of capacitance values comprising a capacitance value for each of the plurality of sensor electrodes from the set of signals;

determining positional information of an input object proximate to the closed loop sensor device using the set of capacitance values; and

generating an output based on the positional information.

2. The method of claim 1 wherein the determining positional information of an input object comprises:

determining a highest capacitance value sensor electrode of the plurality of sensor electrodes using the set of capacitance values;

determining a quadratic fitting from a capacitance value of the highest capacitance value sensor electrode, a capacitance value of a first one of the plurality of sensor electrodes on a first side of the highest capacitance value sensor electrode, and a capacitance value of a second one of the plurality of sensor electrodes on a second side of the highest capacitance value sensor electrode;

determining a center point of the quadratic fitting; and

determining positional information from the center point

3. The method of claim 2 wherein the determining positional information from the center point of the quadratic fitting comprises:

applying a non-linear function to the center point.

4. The method of claim 2 wherein the determining positional information from the center point of the quadratic fitting comprises:

determining a modified center point by subtracting a modulus of a number of the plurality of sensor electrodes from the center point of the quadratic fitting.

5. The method of claim 4 wherein the determining positional information from the center point further comprises:

applying a non-linear function to the modified center point.

6. The method of claim 1 wherein the determining positional information of an input object comprises:

determining a highest capacitance value sensor electrode of the plurality of sensor electrodes;

setting an orientation of the plurality of sensor electrodes such that the highest capacitance value sensor electrode is positioned as a center of the plurality of sensor electrodes in that orientation;

determining a position of the input object by calculating a centroid; and

applying a reverse rotation function to the position.

7. The method of claim 6 wherein the determining positional information of an input object further comprises:

determining the reverse rotation function for the plurality of sensor electrodes, wherein an application of the reverse rotation function sets the orientation of the plurality of sensor electrodes to an original orientation.

8. The method of claim 1 wherein the determining positional information of an input object comprises:

applying a first periodic weighting function to the set of capacitance values of the plurality of sensor electrodes to determine a numerator value;

applying a second periodic weighting function to the set of capacitance values of the plurality of sensor electrodes to determine a denominator value; and

applying a third function to the numerator value and the denominator value.

9. The method of claim 8 wherein the applying a first periodic weighting function to the set of capacitance values comprises:

applying the first periodic weighting function to the capacitance value of each of the plurality of sensor electrodes to determine a first set of weighted capacitance components, the first set of weighted capacitance components comprising a first weighted capacitance component for each of the plurality of sensor electrodes; and

determining the numerator value from the first set of weighted capacitance components; and

wherein

the applying a second periodic weighting function to the set of capacitance values comprises;

applying the second periodic weighting function to the capacitance value of each of the plurality of sensor electrodes to determine a second set of weighted capacitance components, the second set of weighted capacitance components comprising a second weighted capacitance component for each of the plurality of sensor electrodes; and

determining the denominator value from the second set of weighted capacitance components.

10. The method of claim 9 wherein the first periodic weighting function is based on a sine function, the second periodic weighting function is based on a cosine function, and an inverse of the third function is a four quadrant arctangent function.

11. A program product for processing signals from a plurality of sensor electrodes in a closed loop sensor device comprising:

instructions for directing a processing unit to;

receive a set of signals, the set of signals comprising a signal from each of the plurality of sensor electrodes in the closed loop sensor device;

determine a set of capacitance values, the set of capacitance values comprising a capacitance value for each of the plurality of sensor electrodes from the set of signals;

determine positional information of an input object proximate to the closed loop sensor device using the set of capacitance values; and

generating an output based on the positional information; and

a media readable by the processing unit that stores the instructions.

12. The program product of claim 11 wherein the instructions for directing the processing unit to determine positional information of an input object comprise:

instructions for directing the processing unit to;

determine a highest capacitance value sensor electrode of the plurality of sensor electrodes using the set of capacitance values;

determine a quadratic fitting from the capacitance value of the highest capacitance value sensor electrode, the capacitance value of a first one of the plurality of sensor electrodes on a first side of the highest capacitance value sensor electrode and the capacitance value of a second one of the plurality of sensor electrodes on a second side of the highest capacitance value sensor electrode;

determine a center point of the quadratic fitting; and

determine positional information from the center point.

13. The program product of claim 12 wherein the instructions for directing the processing unit to determine positional information from the center point comprise:

instructions for directing the processing unit to;

apply a non-linear function to the center point to determine the positional information.

14. The program product of claim 12 wherein the instructions for directing the processing unit to determine positional information from the center point comprise:

instructions for directing the processing unit to;

determine a modified center point by subtracting a modulus of a number of the plurality of sensor electrodes from the center point of the quadratic fitting.

15. The program product of claim 14 wherein the instructions for directing the processing unit to determine positional information from the center point further comprise:

instructions for directing the processing unit to;

apply a non-linear function to the modified center point to determine the positional information.

16. The program product of claim 11 wherein the instructions for directing the processing unit to determine positional information of an input object comprise:

instructions for directing the processing unit to;

determine a highest capacitance value sensor electrode of the plurality of sensor electrodes;

set an orientation of the plurality of sensor electrodes such that the highest capacitance value sensor electrode is positioned as a center of the plurality of sensor electrodes in that orientation;

determine a position of the input object by calculating a centroid; and

apply a reverse rotation function to the position.

17. The program product of claim 16 wherein the instructions for directing the processing unit to determine positional information of an input object further comprise:

instructions for directing the processing unit to;

determine the reverse rotation function for the plurality of sensor electrodes,

wherein an application of the reverse rotation function sets the orientation of the plurality of sensor electrodes to an original orientation.

18. The program product of claim 11 wherein the instructions to determine positional information of an input object comprise:

instructions for directing the processing unit to;

apply a first periodic weighting function to the set of capacitance values of the plurality of sensor electrodes to determine a numerator,

apply a second periodic weighting function to the set of capacitance values of the plurality of sensor electrodes to determine a denominator, and

apply a third function to the numerator and the denominator.

19. The program product of claim 18 wherein

the instructions to apply an first periodic weighting function comprise instructions for directing the processing unit to:

apply the first periodic weighting function to the set of capacitance values to determine a first set of weighted capacitance components, the first set of weighted capacitance components comprising a first weighted capacitance component for each of the plurality of sensor electrodes; and

determine the numerator from the first set of weighted capacitance components; and

wherein

the instructions to apply the second periodic weighting function comprise instructions for directing the processing unit to;

apply the second periodic weighting function to the set of capacitance values to determine a second set of weighted capacitance components, the second set of weighted capacitance components comprising a second weighted capacitance value component for each of the plurality of sensor electrodes; and

determine the denominator from the second set of weighted capacitance components.

20. The program product of claim 19 wherein the first periodic weighting function is based on sine, the second periodic weighting function is based on cosine, and an inverse of the third function is a four quadrant arctangent.

21. An apparatus comprising:

a plurality of sensor electrodes arranged in a substantially closed loop; and

a processor configured to receive a signal from each of the plurality of sensor electrodes, the processor further adapted to determine a capacitance value of each of the plurality of sensor electrodes from the signal received from each of the plurality of sensor electrodes responsive to a receipt of the signal, determine positional information of an input object proximate to the closed loop sensor device responsive to a determination of the capacitance value of each of the plurality of sensor electrodes, and generate an output using the positional information responsive to a determination of the positional information.

22. The apparatus of claim 21 wherein the processor is configured to determine the positional information of the input object by being configured to:

determine a highest capacitance value sensor electrode from the plurality of sensor electrodes responsive to a determination of the capacitance value of each of the plurality of sensor electrodes;

determine a quadratic fitting from the capacitance value of the highest capacitance value sensor electrode, the capacitance value of a first one of the plurality of sensor electrodes on a first side of the highest capacitance value sensor electrode, and the capacitance value of a second one of the plurality of sensor electrodes on a second side of the highest capacitance value sensor electrode;

determine a center point of the quadratic fitting; and

determine the positional information from the center point responsive to a determination of the center point.

23. The apparatus of claim 22 wherein the processor is configured to determine the positional information of the input object by being configured to:

determine a modified center point by subtracting a modulus of a number of the plurality of sensor electrodes from the center point of the quadratic fitting responsive to a determination the center point; and

apply a non-linear function to the modified center point to determine the positional information responsive to a determination of the modified center point.

24. The apparatus of claim 21 wherein the processor is configured to determine the positional information of the input object by being configured to:

determine a highest capacitance value sensor electrode of the plurality of sensor electrodes;

set an orientation of the plurality of sensor electrodes to have the highest capacitance value sensor electrode as a center of the plurality of sensor electrodes,

determine a position of the input object by calculating a centroid responsive to the orientation of the plurality of sensor electrodes being set; and

apply the position to a reverse rotation function to generate the positional information.

25. The apparatus of claim 21 wherein the processor is configured to determine the positional information of the input object by being configured to:

calculate a numerator from the capacitance values of the plurality of sensor electrodes;

calculate a denominator from the capacitance values of the plurality of sensor electrodes; and

apply a periodic function to the numerator and the denominator to generate the positional information responsive to a calculation of the numerator and the denominator.