Optical touch screens

• US 9,678,601 B2
• Filed: 05/31/2015
• Issued: 06/13/2017
• Est. Priority Date: 02/15/2009
• Status: Active Grant

• Current Assignee: Neonode, Inc.
• Original Assignee: Neonode, Inc.
• Inventors: Pettersson, Robert, Rosengren, Per, Rosengren, Erik, Berglind, Richard, Nordstrm, Karl Erik Patrik, Frjdh, Gunnar Martin, Wang, Xiatao, Behdasht, Remo, Holmgren, Stefan, Sparf, Lars, Eriksson, Thomas
• Primary Examiner(s): Giesy, Adam R
• Application Number:
  US14/726,533
• Publication Number:
  US 20150261339A1
• Time in Patent Office: 744 Days
• CPC Class Codes: G06F 2203/04102 Flexible digitiser, i.e. constructional details for allowing the whole digitising part of a device to be flexed or rolled like a sheet of paper
• 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 2203/04109 FTIR in optical digitiser, i.e. touch detection by frustrating the total internal reflection within an optical waveguide due to changes of optical properties or deformation at the touch location
• CPC Class Codes: G06F 3/03547 Touch pads, in which fingers can move on a surface
• 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 3/042 by opto-electronic means
• CPC Class Codes: G06F 3/0421 by interrupting or reflecting a light beam, e.g. optical touch-screen
• CPC Class Codes: G06F 3/0425 using a single imaging device like a video camera for tracking the absolute position of a single or a plurality of objects with respect to an imaged reference surface, e.g. video camera imaging a display or a projection screen, a table or a wall surface, on which a computer generated image is displayed or projected tracking a projected light spot to determine a position on a display surface G06F3/0386
• CPC Class Codes: G06F 3/0428 by sensing at the edges of the touch surface the interruption of optical paths, e.g. an illumination plane, parallel to the touch surface which may be virtual sensing beam interruptions in a planar beam grid of an optical touch-screen G06F3/0421

Abstract

Activating a plurality of light emitters and light detectors around a screen, each emitter-detector pair corresponding to a light path crossing the screen, wherein some of the light paths are blocked when one or more objects touch the screen, providing a look-up table, listing, for each cell from a plurality of cells, those light paths that traverse that cell when no object is touching the screen, wherein the cells partition the screen, for each cell: accessing the look-up table to identify those light paths that traverse that cell, determining whether the thus-identified light paths are blocked during the activating and, if affirmative, recognizing that cell as being a touched cell, and combining adjacent touched cells into a common touch location, thereby calculating one or more touch locations wherein each touch location is a combination of one or more constituent touched cells.

Claims

1. A method for calculating multiple touch locations on a screen comprising:

activating a plurality of light emitters and light detectors around the perimeter of a screen, each emitter-detector pair corresponding to a light path crossing the screen, wherein some of the light paths are blocked when one or more objects touch the screen;

providing a look-up table, listing, for each cell from a plurality of cells, those light paths that traverse that cell when no object is touching the screen, wherein the cells partition the screen;

for each cell;

accessing the look-up table to identify those light paths that traverse that cell; and

determining whether the thus-identified light paths are blocked during said activating and, if affirmative, recognizing that cell as being a touched cell; and

combining adjacent touched cells into a common touch location, thereby calculating one or more touch locations wherein each touch location is a combination of one or more constituent touched cells.

2. The method of claim 1, wherein the cells are of different sizes.

3. The method of claim 1, wherein each cell surrounds a point of intersection between two light paths.

4. The method of claim 1, further comprising calculating an area for each touch location according to the sum of the areas of that touch location'"'"'s constituent cells.

5. The method of claim 4, further comprising:

providing a range of values for the area of a touch location; and

validating those touch locations whose calculated area is within the range.

6. The method of claim 5, further comprising associating each touch location whose calculated area exceeds the range, with a plurality of objects touching the screen at that location.

7. A method for calculating multiple touch locations on a screen comprising:

activating a plurality of light emitters and light detectors around the perimeter of a screen, each emitter-detector pair corresponding to a light path crossing the screen, wherein some of the light paths are blocked when one or more objects touch the screen;

providing a look-up table, listing, for each light path, those cells from a plurality of cells, that are traversed by that light path when no object is touching the screen, wherein the cells partition the screen;

for each light path that is not blocked during said activating, accessing the look-up table to identify those cells that the identified light path traverses, and recognizing the thus-identified cells as being untouched cells;

classifying those cells that are not recognized as being untouched cells, as being touched cells; and

combining adjacent touched cells into a common touch location, thereby calculating one or more touch locations wherein each touch location is a combination of one or more constituent cells.

8. The method of claim 7, wherein the cells are of different sizes.

9. The method of claim 7, wherein each cell surrounds a point of intersection between two light paths.

10. The method of claim 7, further comprising calculating an area of each touch location according to the sum of the areas of that touch location'"'"'s constituent cells.

11. The method of claim 10, further comprising:

providing a range of values for the area of a touch location; and

validating those touch locations whose calculated area is within the range.

12. The method of claim 11, further comprising associating each touch location whose calculated area exceeds the range with a plurality of objects touching the screen at that location.