Method and system for detecting multiple touches on a touch-sensitive screen

• US 20050017959A1
• Filed: 08/24/2004
• Published: 01/27/2005
• Est. Priority Date: 06/28/2002
• Status: Active Grant

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kraus, Mark Gerard, Nguyen, Vu Xuan
• Granted Patent: US 7,295,191 B2
• Time in Patent Office: Days
• US Class Current: 345/173
• 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 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0436 in which generating transducers and detecting transducers are attached to a single acoustic waves transmission substrate
• CPC Class Codes: G06F 3/04883 for inputting data by handwriting, e.g. gesture or text

Abstract

Disclosed are a method and a system for detecting multiple, simultaneous touches on a touch-sensitive screen of a computing device. The hardware that controls the touch screen performs two measurements to locate a touch location on the screen. If there is a single touch, then the two measurements are equal. A non-zero difference indicates multiple touches and is correlated with the spread of locations simultaneously touched on the screen. If the difference is greater than a set threshold, then an indication is given of multiple touches. The user is warned against multiple touches, and input from the screen is ignored as long as multiple touches are detected. For some embodiments, when multiple touches are detected, the invention also tries to indicate the boundary of the set of locations simultaneously touched. The boundary is used to interpolate the intended single touch from the locations of all the touches.

Claims

1-48. -48. (Cancelled)

49. In a computing system comprising a touch-sensitive screen, a method for responding to an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points, the method comprising:

setting a multiple contact point discrimination threshold;

receiving an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points; and

discarding input from the touch-sensitive screen until receiving an indication that a set of simultaneous contact points on the touch-sensitive screen contains a single contact point.

50. The method of claim 49 wherein the multiple contact point discrimination threshold is set based upon a characteristic selected from the group consisting of:

a type of program configured to receive input from the touch-sensitive screen and a type of physical stylus.

51. The method of claim 49 wherein receiving an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points comprises receiving an indication of a boundary of the set of simultaneous contact points.

52. The method of claim 51 wherein receiving an indication of a boundary comprises receiving a value selected from the group consisting of:

a leftmost contact point location, a rightmost contact point location, a topmost contact point location, and a bottommost contact point location.

53. The method of claim 51 further comprising:

after receiving an indication of a boundary and before discarding input from the touch-sensitive screen, interpolating a contact point on the touch-sensitive screen from a former single contact point and from the indicated boundary; and

treating the interpolated contact point as a single contact point on the touch-sensitive screen.

54. The method of claim 53 wherein interpolating a contact point comprises selecting a top-left corner of the indicated boundary as the single contact point.

55. The method of claim 49 further comprising posting a warning against touching the touch-sensitive screen, the warning selected from the group consisting of:

a visual warning displayed on the touch-sensitive screen and an audible warning.

56. A computer-readable medium containing computer-executable instructions for performing, in a computing system comprising a touch-sensitive screen, a method for responding to an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points, the method comprising:

setting a multiple contact point discrimination threshold;

receiving an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points; and

discarding input from the touch-sensitive screen until receiving an indication that a set of simultaneous contact points on the touch-sensitive screen contains a single contact point.