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

• US 7,295,191 B2
• Filed: 08/24/2004
• Issued: 11/13/2007
• Est. Priority Date: 06/28/2002
• Status: Expired due to Fees

• Current Assignee: Microsoft Technology Licensing LLC (Microsoft Corporation)
• Original Assignee: Microsoft Corporation
• Inventors: Kraus, Mark Gerard, Nguyen, Vu Xuan
• Primary Examiner(s): Lefkowitz; Sumati
• Assistant Examiner(s): Beck; Alexander S.
• Application Number:
  US10/924,508
• Publication Number:
  US 20050017959A1
• Time in Patent Office: 1,176 Days
• Field of Search: 345/173, 345/174, 178/18.01, 178/19.05
• 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. A computing system comprising a touch-sensitive screen, the computing system configured to, at least:

set a multiple contact point discrimination threshold specifying, at least, a threshold distance between a first contact point and a second contact point;

receive an indication that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points, the indication comprising a boundary of the set of simultaneous contact points;

interpolate an interpolated contact point on the touch-sensitive screen from a former single contact point and from the indicated boundary;

treat the interpolated contact point as a single contact point on the touch-sensitive screen; and

discard input from the touch-sensitive screen until an indication is received that the set of simultaneous contact points on the touch-sensitive screen contains the single contact point.

2. The system of claim 1 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.

3. The system of claim 1 wherein the indication of the boundary comprises at least one 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.

4. The system of claim 1 wherein interpolating the interpolated contact point comprises selecting a top-left corner of the indicated boundary as the single contact point.

5. The system of claim 1 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.

6. The system of claim 1, wherein receiving each indication comprises receiving a message of a message protocol.

7. At least one 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 specifying, at least, a threshold distance between a first contact point and a second contact point;

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

interpolating an interpolated contact point on the touch-sensitive screen from a former single contact point and from the indicated boundary;

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

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

8. Said at least one computer-readable medium of claim 7, 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.

9. Said at least one computer-readable medium of claim 7, wherein the indication of the boundary comprises at least one 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.

10. Said at least one computer-readable medium of claim 7, wherein interpolating the interpolated contact point comprises selecting a top-left corner of the indicated boundary as the single contact point.

11. Said at least one computer-readable medium of claim 7, wherein the method further comprises posting a warning against touching the touch-sensitive screen.

12. Said at least one computer-readable medium of claim 7, wherein receiving each indication comprises receiving a message of a message protocol.

13. A computer readable medium having a message protocol encoded thereon, the message protocol between a computing device comprising a touch-sensitive screen and a computing system, the message protocol comprising:

a message for setting a multiple contact point discrimination threshold specifying, at least, a threshold distance between a first contact point and a second contact point;

a message for indicating that a set of simultaneous contact points on the touch-sensitive screen contains a plurality of contact points, the indication comprising a boundary of the set of simultaneous contact points;

a message for indicating that a set of simultaneous contact points on the touch-sensitive screen contains a single contact point, the indication comprising the single contact point, the single contact point having been interpolated from a former single contact point and from the indicated boundary; and

wherein each message of the message protocol causes at least one modification to data stored in the computer-readable medium of at least one of;

the computing device and the computing system.

14. The message protocol of claim 13, wherein the computing system includes the computing device.

15. The message protocol of claim 13, wherein the threshold distance is set based upon a type of physical stylus and a type of program configured to receive input from the touch-sensitive screen.

16. The message protocol of claim 13, wherein the boundary comprises a rectangular boundary.

17. The message protocol of claim 16, wherein the rectangular boundary comprises at teast two of:

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

18. The message protocol of claim 16, wherein the former single contact point was indicated by a previous message.

19. The message protocol of claim 18, wherein interpolating the single contact point comprises selecting a top-left corner of the rectangular boundary.

20. The message protocol of claim 13, wherein, in response to at least one message of the message protocol, a warning against touching the touch-sensitive screen is posted.