LOCATING MULTIPLE OBJECTS ON A CAPACITIVE TOUCH PAD

• US 20090174675A1
• Filed: 05/30/2008
• Published: 07/09/2009
• Est. Priority Date: 01/09/2008
• Status: Abandoned Application

• Current Assignee: Synaptics Incorporated
• Original Assignee: Synaptics Incorporated
• Inventors: Gillespie, Dave, Dattalo, Tracy Scott
• Application Number:
  US12/130,904
• Publication Number:
  US 20090174675A1
• Time in Patent Office: Days
• US Class Current: 345/173
• CPC Class Codes: G06F 2203/04104 Multi-touch detection in digitiser, i.e. details about the simultaneous detection of a plurality of touching locations, e.g. multiple fingers or pen and finger
• 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
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

A system and method for locating multiple objects on a capacitive touch pad is described. The method for determining locations of a plurality of objects contemporaneously interacting with a capacitive touch pad having a sensing region includes generating a first capacitive profile associated with a first object and a second object contemporaneously in the sensing region and determining locations of the first and second objects with respect to the sensing region utilizing the first capacitive profile.

Claims

1. A method for determining locations of a plurality of objects contemporaneously interacting with a capacitive touch pad having a sensing region, the method comprising:

generating a first capacitive profile associated with a first object and a second object contemporaneously in said sensing region; and

determining locations of said first and second objects with respect to said sensing region utilizing said first capacitive profile.

2. The method of claim 1 wherein determining locations of said first and second objects with respect to said sensing region comprises:

determining capacitance values associated with said first and second objects with respect to a first axis of said sensing region; and

determining locations of said first and second objects in said first axis.

3. The method of claim 2, further comprising:

generating a second capacitive profile associated with said first and second objects, said second capacitive profile comprising capacitance values associated with said first and second objects with respect to a second axis of said sensing region; and

determining locations of said first and second objects in said second axis.

4. The method of claim 3, further comprising:

determining a relationship between said locations in said first axis and said locations in said second axis; and

utilizing said relationship to control a user interface.

5. The method of claim 2 wherein determining locations of said first and second objects comprises:

performing local interpolation on said first capacitive profile.

6. A computer-readable medium have computer-readable code stored thereon for causing a processor to perform a method for determining locations of a plurality of objects contemporaneously interacting with a capacitive touch pad having a sensing region, the method comprising:

generating a first capacitive profile associated with a first object and a second object contemporaneously in said sensing region with respect to a first axis of said sensing region, said first capacitive profile comprising capacitance values associated with said first axis;

determining locations of said first and second objects with respect to said first axis of said sensing region utilizing said first capacitive profile;

generating a second capacitive profile associated with said first object and said second object contemporaneously in said sensing region with respect to a second axis of said sensing region, said second capacitive profile comprising capacitance values associated with said second axis; and

determining locations of said first and second objects with respect to said second axis of said sensing region utilizing said second capacitive profile.

7. The computer readable medium of claim 6 wherein said method further comprises:

determining a relationship between said locations in said first axis and said locations in said second axis; and

utilizing said relationship to control a user interface.

8. The computer readable medium of claim 6 wherein determining locations of said first and second objects with respect to said first axis comprises:

performing local interpolation on said first capacitive profile.

9. The computer readable medium of claim 8 wherein said local interpolation uses a value of a peak electrode and a value of an adjacent electrode.

10. The computer readable medium of claim 6 wherein determining locations of said first and second objects with respect to said second axis comprises:

performing local interpolation on said second capacitive profile.

11. A method for determining locations of a plurality of objects interacting with a capacitive touch pad that generates capacitance profiles comprising:

generating a first capacitance profile associated with a first object proximate said touch pad;

determining a position of said first object with respect to said touch pad based on said first capacitance profile;

generating a second capacitance profile associated with said first object and a second object simultaneously proximate said touch pad;

determining an adjusted capacitance profile based on said first and second capacitance profiles; and

determining a position of said second conductive object with respect to said touch pad based on said adjusted capacitance profile.

12. The method of claim 11 wherein said first and second capacitance profiles are both generated with respect to a first axis of said touch pad.

13. The method of claim 11 further comprising:

using said positions of said first and second objects to emulate a text input device.

14. The method of claim 11 wherein said generating said first capacitance profile occurs prior to said generating said second capacitance profile.

15. The method of claim 11 wherein said determining said adjusted capacitance profile comprises:

scaling one of said first and second capacitance profiles.

16. A capacitance sensing touch pad for determining locations of a plurality of objects comprising:

a capacitance profile generator coupled with said touch pad for generating a first capacitance profile associated with a first object proximate said touch pad;

a position determiner coupled with said profile generator for determining a position of said first object with respect to said touch pad based on said first capacitance profile;

said capacitance profile generator for generating a second capacitance profile associated with said first object and a second object simultaneously proximate said touch pad;

a profile adjuster coupled with said profile generator for determining an adjusted capacitance profile based on said first and second capacitance profiles; and

said position determiner for determining a position of said second conductive object with respect to said touch pad based on said adjusted capacitance profile.

17. The capacitance sensing touch pad of claim 16 wherein said first and second capacitance profiles are both generated with respect to a first axis of said touch pad.

18. The capacitance sensing touch pad of claim 16 further comprising:

a text input emulator for using said positions of said first and second objects to emulate a text input device.

19. The capacitance sensing touch pad of claim 16 wherein said profile generator generates said first capacitance profile prior to generating said second capacitance profile.

20. The capacitance sensing touch pad of claim 16 further comprises:

a profile scaler for scaling one of said first and second capacitance profiles.

21. A module for identifying a plurality of objects interacting with a capacitive touch pad comprising:

a first input for accessing a signal corresponding to a first object proximate said capacitive touch pad;

a profile generator for generating a first capacitive profile associated with said first object;

a second input for accessing a signal indicating a second object proximate said capacitive touch pad, wherein said profile generator is also for generating a second capacitive profile associated with said second object; and

a location determiner for determining locations of said first and second objects with respect to said capacitive touch pad utilizing said first and second capacitive profiles.

22. The module of claim 21 further comprising:

a text input emulator for using said positions of said first and second objects to emulate a text input device.

23. The module of claim 21 further comprising:

a user interface controller for using said locations of said first and second objects to control a user interface.

24. The module of claim 21 wherein said profile generator generates said first capacitance profile prior to generating said second capacitance profile.

25. The module of claim 21 further comprising:

a profile scaler for scaling one of said first and second capacitance profiles.