Touch Identification for Multi-Touch Technology

• US 20120044150A1
• Filed: 04/26/2010
• Published: 02/23/2012
• Est. Priority Date: 04/24/2009
• Status: Active Grant

• Current Assignee: Parade Technologies, Ltd.
• Original Assignee: Cypress Semiconductor Corporation (Infineon Technologies AG)
• Inventors: Karpin, Oleksandr, Hutnyk, Volodymyr
• Granted Patent: US 8,633,904 B2
• 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 3/04166 Details of scanning methods, e.g. sampling time, grouping of sub areas or time sharing with display driving Synchronisation with the driving of the display or the backlighting unit to avoid interferences generated internally G06F3/04184
• CPC Class Codes: G06F 3/04186 Touch location disambiguation
• CPC Class Codes: G06F 3/044 by capacitive means
• 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 method of operating a touch-sensing surface may include determining a first plurality of contact locations including a first contact location, determining a second plurality of contact locations including a second contact location, performing a first correlation process for correlating the second contact location with the first contact location when the number of contacts is less than or equal to a first threshold number, and performing a second correlation process for correlating the second contact location with the first contact location when the number of contacts is greater than a second threshold number.

Claims

1. A method of operating a touch-sensing surface, the method comprising:

determining a first plurality of contact locations during a first time period, wherein the first plurality of contact locations includes a first contact location;

determining a second plurality of contact locations during a second time period, wherein the second plurality of contact locations includes a second contact location;

if a number of contacts is less than or equal to a first threshold number, performing a first correlation process for correlating the second contact location with the first contact location; and

if the number of contacts is greater than a second threshold number, performing a second correlation process for correlating the second contact location with the first contact location.

2. The method of claim 1, wherein the first time period includes a time period for performing a first scan of a touch-sensing surface, and wherein the second time period includes a time period for performing a second scan of the touch-sensing surface.

3. The method of claim 1, wherein the second threshold number is equal to the first threshold number.

4. The method of claim 1, further comprising:

detecting at least one unmoved contact; and

excluding the at least one unmoved contact from at least one of the first correlation process or the second correlation process.

5. The method of claim 1, wherein the first correlation process includes a least squares calculation.

6. The method of claim 5, wherein performing the least squares calculation comprises calculating a sum of squared distances for each of a plurality of combinations, wherein each of the plurality of combinations correlates each of the second plurality of contact locations with one of the first plurality of contact locations, and wherein the sum of squared distances includes a square of a distance between each of the second plurality of contact locations and a corresponding contact location from the first plurality of contact locations.

7. The method of claim 1, wherein the second correlation process includes a nearest neighbor calculation.

8. The method of claim 7, wherein performing the nearest neighbor calculation comprises:

comparing the second contact location with the first contact location; and

correlating the second contact location with the first contact location in response to determining that the first contact location is within a maximum distance of the first contact location.

9. The method of claim 7, wherein performing the nearest neighbor calculation comprises selecting from the first plurality of contact locations a contact location nearest the second contact location as the first contact location.

10. The method of claim 1, further comprising:

assigning one of a plurality of contact identifiers to each of the first plurality of contact locations; and

assigning one of the plurality of contact identifiers to each of the second plurality of contact locations.

11. The method of claim 1, wherein correlating the second contact location with the first contact location comprises assigning a contact identifier of the first contact location to the second contact location.

12. The method of claim 1, further comprising:

if the number of the first plurality of contacts is less than the first threshold number, performing the first correlation process for correlating each of the second plurality of contact locations with one of the first plurality of contact locations; and

if the number of the first plurality of contacts is greater than the second threshold number, performing the second correlation process for correlating each of the second plurality of contact locations with one of the first plurality of contact locations.

13. A touch controller, comprising:

an input configured to connect the touch controller with a touch-sensing surface;

a processor coupled with the input; and

a memory coupled with the processor, wherein the memory contains instructions which, when executed by the processor, cause the touch controller to perform operations comprising;

determining a first plurality of contact locations during a first time period, wherein the first plurality of contact locations includes a first contact location;

determining a second plurality of contact locations during a second time period, wherein the second plurality of contact locations includes a second contact location;

if a number of contacts is less than or equal to a first threshold number, performing a first correlation process for correlating the second contact location with the first contact location; and

if the number of contacts is greater than a second threshold number, performing a second correlation process for correlating the second contact location with the first contact location.

14. The touch controller of claim 13, wherein the touch sensing surface is a touchscreen.

15. The touch controller of claim 13, wherein the first time period includes a time period for performing a first scan of a touch-sensing surface, and wherein the second time period includes a time period for performing a second scan of the touch-sensing surface.

16. The touch controller of claim 13, wherein the second threshold number is equal to the first threshold number.

17. The touch controller of claim 13, wherein the memory further contains instructions which, when executed by the processor, cause the touch controller to perform operations comprising:

detecting at least one unmoved contact; and

excluding the at least one unmoved contact from at least one of the first correlation process or the second correlation process.

18. The touch controller of claim 13, wherein the first correlation process includes performing a least squares calculation.

19. The touch controller of claim 18, wherein performing the least squares calculation comprises calculating a sum of squared distances for each of a plurality of combinations, wherein each of the plurality of combinations correlates each of the second plurality of contact locations with one of the first plurality of contact locations, and wherein the sum of squared distances includes a square of a distance between each of the second plurality of contact locations and a corresponding contact location from the first plurality of contact locations.

20. The touch controller of claim 13, wherein the second correlation process includes performing a nearest neighbor calculation.

21. The touch controller of claim 20, wherein performing the nearest neighbor calculation comprises:

comparing the second contact location with the first contact location; and

correlating the second contact location with the first contact location in response to determining that the first contact location is within a maximum distance of the second contact location.

22. The touch controller of claim 20, wherein performing the nearest neighbor calculation comprises correlating the second contact location with the first contact location comprises selecting from the first plurality of contact locations a contact location nearest the second contact location as the first contact location.

23. The touch controller of claim 13, wherein the memory further contains instructions which, when executed by the processor, cause the touch controller to perform operations comprising:

assigning one of a plurality of contact identifiers to each of the first plurality of contact locations; and

assigning one of the plurality of contact identifiers to each of the second plurality of contact locations.

24. The touch controller of claim 13, wherein correlating the second contact location with the first contact location comprises assigning a contact identifier of the first contact location to the second contact location.

25. The touch controller of claim 13, wherein the memory further contains instructions which, when executed by the processor, cause the touch controller to perform operations comprising:

if the number of the first plurality of contacts is less than or equal to the first threshold number, performing the first correlation process for correlating each of the second plurality of contact locations with one of the first plurality of contact locations; and

if the number of the first plurality of contacts is greater than the second threshold number, performing the second correlation process for correlating each of the second plurality of contact locations with one of the first plurality of contact locations.