MULTI-TOUCH CONTACT TRACKING ALGORITHM

• US 20070081726A1
• Filed: 11/14/2006
• Published: 04/12/2007
• Est. Priority Date: 01/26/1998
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: FingerWorks Limited (Apple Inc.)
• Inventors: Elias, John, WESTERMAN, WAYNE
• Granted Patent: US 8,334,846 B2
• Time in Patent Office: Days
• US Class Current: 382/185
• CPC Class Codes: G06F 18/24137 Distances to cluster centroïds
• CPC Class Codes: G06F 2203/04101 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup
• 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 2203/04106 Multi-sensing digitiser, i.e. digitiser using at least two different sensing technologies simultaneously or alternatively, e.g. for detecting pen and finger, for saving power or for improving position detection
• CPC Class Codes: G06F 2203/04808 Several contacts: gestures triggering a specific function, e.g. scrolling, zooming, right-click, when the user establishes several contacts with the surface simultaneously; e.g. using several fingers or a combination of fingers and pen
• CPC Class Codes: G06F 3/0235 using chord techniques G06F3/0234 takes precedence
• CPC Class Codes: G06F 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0412 Digitisers structurally integrated in a display
• 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 3/0446 using a grid-like structure of electrodes in at least two directions, e.g. using row and column electrodes
• CPC Class Codes: G06F 3/0447 Position sensing using the local deformation of sensor cells
• CPC Class Codes: G06F 3/04815 Interaction with a metaphor-based environment or interaction object displayed as three-dimensional, e.g. changing the user viewpoint with respect to the environment or object
• CPC Class Codes: G06F 3/04845 for image manipulation, e.g. dragging, rotation, expansion or change of colour
• CPC Class Codes: G06F 3/0485 Scrolling or panning
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text
• CPC Class Codes: G06F 3/04886 by partitioning the display area of the touch-screen or the surface of the digitising tablet into independently controllable areas, e.g. virtual keyboards or menus
• CPC Class Codes: G06V 30/19173 Classification techniques
• CPC Class Codes: G06V 30/1983 Syntactic or structural pattern recognition, e.g. symbolic string recognition
• CPC Class Codes: G06V 40/107 : Static hand or arm
• CPC Class Codes: H03K 17/9622 : using a plurality of detectors, e.g. keyboard
• CPC Class Codes: H03K 2217/960725 : Charge-transfer

Abstract

Apparatus and methods are disclosed for simultaneously tracking multiple finger and palm contacts as hands approach, touch, and slide across a proximity-sensing, multi-touch surface. Identification and classification of intuitive hand configurations and motions enables unprecedented integration of typing, resting, pointing, scrolling, 3D manipulation, and handwriting into a versatile, ergonomic computer input device.

Claims

1. A method for associating into paths one or more surface contacts from successive proximity images, the successive proximity images including a current proximity image and one or more prior proximity images, the method comprising:

generating one or more predicted paths by predicting from the one or more prior proximity images current positions of the one or more surface contacts;

finding for each surface contact in the current proximity image a closest predicted path;

finding for each predicted path a closest surface contact, the closest surface contact having a centroid closest to the predicted path; and

pairing each surface contact with its closest predicted path if the surface contact is also the closest surface contact to the predicted path.

3. The method of claim 1 or 2 further comprising:

starting new paths for unpaired surface contacts.

4. The method of claim 3 further comprising:

deactivating unpaired predicted paths.

5. The method of claim 1 or 2 further comprising:

deactivating unpaired predicted paths.

6. The method of claim 1 or 2 further comprising:

updating path parameters for each of the one or more predicted paths from one or more measured parameters of the surface contact paired with each predicted path.

7. The method of claim 6 further comprising:

starting new paths for unpaired surface contacts.

8. The method of claim 7 further comprising:

deactivating unpaired predicted paths.

9. The method of claim 6 further comprising:

deactivating unpaired predicted paths.

10. The method of claim 1 or 2 wherein generating one or more predicted paths by predicting from the one or more prior proximity images current positions of the one or more surface contacts comprises determining a velocity of the one or more surface contacts along one or more corresponding existing paths.

11. The method of claim 10 further comprising:

starting new paths for unpaired surface contacts.

12. The method of claim 11 further comprising:

deactivating unpaired predicted paths.

13. The method of claim 10 further comprising:

deactivating unpaired predicted paths.

14. The method of claim 10 further comprising:

updating path parameters for each of the one or more predicted paths from one or more measured parameters of the surface contact paired with each predicted path.

15. The method of claim 14 further comprising:

starting new paths for unpaired surface contacts.

16. The method of claim 15 further comprising:

deactivating unpaired predicted paths.

17. The method of claim 14 further comprising:

deactivating unpaired predicted paths.

2. A method for associating into paths one or more surface contacts from successive proximity images, the successive proximity images including a current proximity image and one or more prior proximity images, the method comprising:

generating one or more predicted paths by predicting from the one or more prior proximity images current positions of the one or more surface contacts;

finding for each surface contact in the current proximity image a closest predicted path;

finding for each predicted path a closest surface contact, the closest surface contact having a centroid closest to the predicted path and within a path-dependent tracking radius of the predicted path; and

pairing each surface contact with its closest predicted path if the surface contact is also the closest surface contact to the predicted path and if the centroid of the closest surface contact is within the path-dependent tracking radius of the predicted path.

18. A method for associating into paths one or more groups of pixels from successive proximity images, each group of pixels corresponding to a distinguishable hand part or other touch object on or near the surface of a multi-touch apparatus and each proximity image representing a scan of a plurality of proximity sensors of the multi-touch apparatus, the successive proximity images including a current proximity image and one or more prior proximity images, the method comprising:

predicting paths for each of the one or more groups of pixels from the one or more prior proximity images;

pairing each group of pixels with its predicted path;

whereby the paths may be used to generate user interface interactions in response to motion of the distinguishable hand parts or other touch objects through the successive proximity images.

20. The method of claim 18 further comprising:

starting new paths for unpaired groups of pixels.

21. The method of claim 20 further comprising:

deactivating unpaired predicted paths.

22. The method of claim 18 further comprising:

deactivating unpaired predicted paths.

23. The method of claim 18 wherein at least one of the groups of pixels corresponds to a hand part near but not on the multi-touch surface.

24. The method of claim 23 further comprising:

starting new paths for unpaired groups of pixels, wherein at least one unpaired group of pixels corresponds to a hand part near but not on the multi-touch surface.