Multi-touch input discrimination

• US 8,130,203 B2
• Filed: 05/31/2007
• Issued: 03/06/2012
• Est. Priority Date: 01/03/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: Westerman, Wayne Carl
• Primary Examiner(s): Eisen, Alexander
• Assistant Examiner(s): Marinelli, Patrick
• Application Number:
  US11/756,211
• Publication Number:
  US 20080158185A1
• Time in Patent Office: 1,741 Days
• Field of Search: 345156-173, 178 1801- 2004, 382/172, 382/312, 382/191, 382/181, 382/203, 382/210
• US Class Current: 345/173
• 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 3/041 Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• 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 3/04182 Filtering of noise external to the device and not generated by digitiser components
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0488 using a touch-screen or digitiser, e.g. input of commands through traced gestures
• CPC Class Codes: G06T 7/11 Region-based segmentation
• CPC Class Codes: G06V 40/107 Static hand or arm
• CPC Class Codes: G09G 2320/0606 Manual adjustment
• CPC Class Codes: G09G 2320/0626 for control of overall brightness
• CPC Class Codes: G09G 2320/0633 by amplitude modulation of the brightness of the illumination source
• CPC Class Codes: G09G 2320/0653 Controlling or limiting the speed of brightness adjustment of the illumination source
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 2360/144 the light being ambient light
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2003 Display of colours specific for liquid crystal displays G09G3/3607
• CPC Class Codes: G09G 5/10 Intensity circuits

Abstract

Techniques for identifying and discriminating between different types of contacts to a multi-touch touch-screen device are described. Illustrative contact types include fingertips, thumbs, palms and cheeks. By way of example, thumb contacts may be distinguished from fingertip contacts using a patch eccentricity parameter. In addition, by non-linearly deemphasizing pixels in a touch-surface image, a reliable means of distinguishing between large objects (e.g., palms) from smaller objects (e.g., fingertips, thumbs and a stylus) is described.

Claims

1. A method to discriminate input sources to a touch-surface device, comprising:

obtaining a proximity image;

segmenting the proximity image to identify a plurality of patches;

determining a eccentricity value for each of the plurality of patches;

identifying a first patch as a thumb contact if the eccentricity value of the first patch is greater than a first threshold;

determining a minor radius value for each of the plurality of patches;

ignoring each patch having a minor radius value greater than a second threshold; and

using the identified patch to control an operation of a touch-surface device.

2. The method of claim 1, further comprising identifying a second patch as a fingertip contact if the eccentricity value of the second patch is less than the first threshold.

3. The method of claim 2, further comprising identifying the first and second patches as contacts from a right hand if the second patch is detected to the right of the first patch;

and

using the identified patch to control an operation of a touch-surface device comprises using the identified first and second patches to control an operation of the touch surface-device.

4. The method of claim 2, further comprising identifying the first and second patches as contacts from a left hand if the second patch is detected to the left of the first patch;

and

using the identified patch to control an operation of a touch-surface device comprises using the identified first and second patches to control an operation of the touch surface-device.

5. The method of claim 1, wherein the eccentricity value of a patch is determined by taking a ratio of a major radius value of the patch and a minor radius value of the patch.

6. The method of claim 1, wherein the first threshold comprises a constant value.

7. The method of claim 1, wherein the first threshold comprises a linear function.

8. The method of claim 1, wherein the act of ignoring is performed before the acts of identifying.

9. The method of claim 8, wherein the second threshold comprises a constant value.

10. The method of claim 8, wherein the second threshold comprises a linear function.

11. The method of claim 1, wherein the act of using comprises changing an operational mode of the touch-surface device.

29. A program storage device, readable by a programmable control device, comprising instructions stored thereon for causing the programmable control device to implement one or more of the methods of claims 1, 12 and 18.

30. A touch-surface device, comprising:

a touch-surface adapted to receive touch input;

a processor coupled to the touch-surface; and

memory storing instructions to perform one or more of the methods of claims 1, 12 and 18.

31. The touch-surface device of claim 30, wherein the touch-surface device comprises a mobile telephone.

32. The touch-surface device of claim 30, wherein the touch-surface device comprises a music device.

33. The touch-surface device of claim 30, wherein the touch-surface device comprises a video display device.

34. The touch-surface device of claim 30, wherein the touch-surface device comprises a personal computer.

12. A method to discriminate input sources to a touch-surface device, comprising:

obtaining a proximity image;

segmenting the proximity image to identify a plurality of patches, each patch having one or more pixels, each pixel having a value;

reducing the value of each pixel in a non-linear fashion;

determining a minor radius value for each of the plurality of patches;

identifying a first patch as a palm contact if the minor radius of the first patch is greater than a specified threshold; and

using the identified patch to control an operation of a touch-surface device.

13. The method of claim 12, wherein the specified threshold comprises a constant value.

14. The method of claim 12, wherein the specified threshold comprises a linear function.

15. The method of claim 12, wherein the act of reducing comprises reducing the value of a pixel to the square-root of the value of the pixel.

16. The method of claim 12, further comprising determining a centroid value for each of the plurality of patches, wherein the act of determining the centroid value uses pixel values that have not been reduced in a non-linear fashion.

17. The method of claim 12, wherein the act of using comprises changing an operational mode of the touch-surface device.

18. A method to discriminate input sources to a touch-surface device, comprising:

obtaining a proximity image;

segmenting the proximity image to identify one or more patches, each patch having a plurality of pixels, each pixel have a value;

reducing the value of each pixel in a non-linear fashion;

determining an eccentricity value for each of the plurality of patches;

determining a minor radius value for each of the plurality of patches;

identifying each patch having a minor radius value greater than a first threshold as a palm contact, said patches associated with a first group of patches;

identifying each patch having a minor radius value less than the first threshold and an eccentricity value greater than a second threshold as a thumb contact, said patches associated with a second group of patches;

identifying each patch having a minor radius value less than the first threshold and an eccentricity value less than the second threshold as a fingertip contact, said patches associated with a third group of patches; and

using the identified patches to control an operation of a touch-surface device.

19. The method of claim 18, further comprising identifying the first, second and third groups of patches as contacts from a right hand if the third group of patches is to the right of the second group of patches.

20. The method of claim 18, further comprising identifying the first, second and third groups of patches as contacts from a left hand if the third group of patches is to the left of the second group of patches.

21. The method of claim 18, wherein the first threshold comprises a constant value.

22. The method of claim 18, wherein the second threshold comprises a constant value.

23. The method of claim 18, wherein the first threshold comprises a linear function.

24. The method of claim 18, wherein the first threshold comprises a constant value.

25. The method of claim 18, wherein the second threshold comprises a linear function.

26. The method of claim 18, wherein the second threshold comprises a constant value.

27. The method of claim 18, wherein the act of reducing comprises reducing the value of a pixel to the square-root of the value of the pixel.

28. The method of claim 18, wherein the act of using comprises changing an operational mode of the touch-surface device.