Object detection in touch systems

Patent metadata

Field	Value
Publication number	US-9626018-B2
Application number	US-201314398235-A
Country	US
Kind code	B2
Filing date	Apr 29, 2013
Priority date	May 2, 2012
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A signal processor implements a technique for detecting objects on a panel which transmits signals inside the panel such that the objects are allowed to interact with (e.g. attenuate) the signals by contact with a touch surface of the panel. The signal processor operates to define cells that have a given location on the touch surface and are associated with a respective set of intersecting paths for the signals across the touch surface. The signal processor operates to obtain ( 70 ) an output signal from a signal detection arrangement that measures a signal property for each path; process ( 71 ) the output signal to obtain an interaction value for each path; and determine ( 73 - 75 ) a touch status of a selected cell among the cells by analyzing the distribution of interaction values for at least part of the intersecting paths. The touch status indicates presence or absence of one of the objects in the selected cell.

First claim

The invention claimed is:

1. A method for detecting objects on a panel having a touch surface, said method comprising:
defining a plurality of reconstruction cells with respect to the touch surface, each of the plurality of reconstruction cells corresponding to a region on the touch surface, the region being intersected by a respective set of signal transmission paths, the signal transmission paths defined by signals transmitted across the touch surface from a plurality of emitters to a plurality of detectors, and the signal transmission paths extending across the touch surface of the panel between pairs of the plurality of emitters and the plurality of detectors;
obtaining an output signal based on a signal property measurement for each signal transmission path;
processing the output signal to obtain an interaction value for each signal transmission path; and
determining a touch status of a selected reconstruction cell among the plurality of reconstruction cells by analyzing a distribution of interaction values for signal transmission paths intersecting the region on the touch surface corresponding to the selected reconstruction cell, the touch status indicating presence or absence of at least one of the objects in the region corresponding to the selected reconstruction cell;
wherein the determining a touch status includes
identifying, based on the interaction values, at least one of interacting and non-interacting signal transmission paths among the signal transmission paths intersecting the region corresponding to the selected reconstruction cell; and
determining the touch status based on a ratio given by a count of said at least one of interacting and non-interacting signal transmission paths.

2. The method of claim 1 , wherein the analyzing a distribution of interaction values comprises:
analyzing the distribution of interaction values in relation to an interaction value representing either absence or presence of interaction with an object along the respective transmission path.

3. The method of claim 2 , wherein the touch status is determined by a degree of clustering of interaction values at the interaction value.

4. The method of claim 1 , wherein the interacting and non-interacting signal transmission paths are deemed to intersect and not intersect, respectively, one or more of the objects on the touch surface.

5. The method of claim 1 , wherein the ratio relates the count to a number of signal transmission paths intersecting the region corresponding to the selected reconstruction cell.

6. The method of claim 1 , wherein the identifying at least one of interacting and non-interacting signal transmission paths comprises:
mapping the interaction values for the signal transmission paths intersecting the region corresponding to the selected reconstruction cell to a specific range of interaction values.

7. The method of claim 6 , wherein the specific range includes an interaction value representing either presence or absence of interaction with an object along the respective signal transmission path.

8. The method of claim 1 , wherein the identifying at least one of interacting and non-interacting signal transmission paths comprises:
processing the interaction values for detection of one or more clusters of interaction values of corresponding magnitude; and
determining said count based on said one or more clusters.

9. The method of claim 8 , wherein said count is given by a count of interaction values in a cluster including an interaction value representing either presence or absence of interaction with an object along the respective signal transmission path.

10. The method of claim 1 , further comprising:
normalizing, before the determining a touch status, the interaction values for the set of signal transmission paths intersecting the region corresponding to the selected reconstruction cell, by a respective intersection value corresponding to a relative overlap between the respective signal transmission path and the region corresponding to the selected reconstruction cell.

11. The method of claim 1 , wherein the determining a touch status is performed for a plurality of selected reconstruction cells corresponding to a region of interest on the touch surface.

12. The method of claim 11 , further comprising:
generating a two-dimensional distribution of reconstruction values representative of interaction on the touch surface by operating an image reconstruction algorithm on the interaction values for at least part of the signal transmission paths; and
processing the two-dimensional distribution to identify said region of interest.

13. The method of claim 12 , wherein said region of interest is identified in the two-dimensional distribution to contain the at least one of the objects.

14. The method of claim 12 , wherein the region of interest is a coherent region of reconstruction values indicating presence of the at least one of the objects.

15. The method of claim 12 , further comprising:
determining a peak reconstruction value within the region of interest in the two-dimensional distribution; and
setting specific range of interaction values in relation to the peak reconstruction value.

16. A method for detecting objects on a panel having a touch surface, said method comprising:
defining a plurality of reconstruction cells with respect to the touch surface, each of the plurality of reconstruction cells corresponding to a region on the touch surface, the region being intersected by a respective set of signal transmission paths, the signal transmission paths defined by signals transmitted across the touch surface from a plurality of emitters to a plurality of detectors, and the signal transmission paths extending across the touch surface of the panel between pairs of the plurality of emitters and the plurality of detectors;
obtaining an output signal based on a signal property measurement for each signal transmission path;
processing the output signal to obtain an interaction value for each signal transmission path;
determining a touch status of a selected reconstruction cell among the plurality of reconstruction cells by analyzing a distribution of interaction values for signal transmission paths intersecting the region on the touch surface corresponding to the selected reconstruction cell, the touch status indicating presence or absence of at least one of the objects in the region corresponding to the selected reconstruction cell, wherein the determining a touch status is performed for a plurality of selected reconstruction cells corresponding to a region of interest on the touch surface;
generating a two-dimensional distribution of reconstruction values representative of interaction on the touch surface by operating an image reconstruction algorithm on the interaction values for at least part of the signal transmission paths;
processing the two-dimensional distribution to identify said region of interest;
estimating a location of the objects on the touch surface; and
selecting, based on the estimated location of the objects and for the selected reconstruction cell, a subset of the set of signal transmission paths intersecting the region corresponding to the selected reconstruction cell, the subset being selected to exclude the signal transmission paths that geometrically intersect the estimated location of at least one of the objects; wherein
the touch status is determined by analyzing the distribution of interaction values for the subset of signal transmission paths.

17. A device for detecting objects on a panel having a touch surface, said d

Assignees

• Flatfrog Lab Ab

Inventors

• Christiansson Tomas
• Ohlsson Nicklas
• Björklund Andreas
• Wallander Mats Petter

Classifications

• G06F2203/04104

  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 title

• G06F3/0416

  Control or interface arrangements specially adapted for digitisers · CPC title

• G06F3/041 Primary

  Digitisers, e.g. for touch screens or touch pads, characterised by the transducing means · CPC title

• G06F3/0421 Primary

  by interrupting or reflecting a light beam, e.g. optical touch-screen · CPC title

• G06F2203/04109

  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 title