Eye Tracker Device

• US 20110109880A1
• Filed: 01/26/2006
• Published: 05/12/2011
• Est. Priority Date: 01/26/2006
• Status: Active Grant

• Current Assignee: Magic Leap, Inc.
• Original Assignee: Nokia Corporation
• Inventors: Nummela, Ville
• Granted Patent: US 8,360,578 B2
• Time in Patent Office: Days
• US Class Current: 351/210
• CPC Class Codes: A61B 3/113 for determining or recording eye movement
• CPC Class Codes: G02B 27/0081 with means for altering, e.g. enlarging, the entrance or exit pupil
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence

Abstract

Two collimated light beams are directed towards an eye to provide two reflection spots. The collimated light beams are advantageously provided by a diffractive beam expander. The reflection spots and the pupil of the eye are monitored by an imaging unit. The collimated beams are at different angles with respect to the imaging unit. The gaze direction is determined based on the angles, the positions of the reflections spots, and the position of the pupil. Thanks to the use of the two collimated beams, the detected gaze direction is substantially independent of the size of the eye, independent of the lateral position of the eye, and independent of the distance between the imaging unit and the eye. The detected gaze angle may be used for selecting between options displayed by a virtual display.

Claims

1. A device for detecting gaze direction of an eye, said device comprising:

a first imaging unit to acquire an image of said eye,

at least one illuminating unit to provide a first substantially collimated light beam and a second substantially collimated light beam, said collimated light beams having different directions with respect to said device such that said first collimated light beam provides a first reflection spot when light is reflected from the surface of the eye and that said second collimated light beam provides a second reflection spot when light is reflected from the surface of the eye, said reflection spots appearing in said image, and

a data processing unit to determine the gaze direction of the eye with respect to said device based on the position of said first reflection spot in said image, on the position of said second reflection spot in said image, on the position of the pupil and/or iris of the eye in said image, and on the directions of the collimated light beams.

2. The device according to claim 1 further comprising one beam expander to expand the width of the collimated light beams.

3. The device according to claim 2 wherein said beam expander is a diffractive beam expander.

4. The device according to claim 2 wherein said first imaging unit is configured to view the eye through said beam expander, which is at least partially transparent to the wavelengths of the collimated light beams.

5. The device according to claim 1 wherein the width of the first collimated light beam is greater than or equal to 20 millimeters.

6. The device according to claim 1 wherein said illuminating unit comprises one semiconductor device to emit invisible infrared light.

7. The device according to claim 1 further comprising a virtual display unit to display virtual images.

8. The device according to claim 1 configured to associate an object or a location with a gaze direction.

9. The device according to claim 8 further comprising a half-mirror configured to reflect or transmit said collimated light beams towards the eye, wherein it is possible for the eye (100) to view said object and/or said location via said half-mirror.

10. The device according to claim 8 comprising a further imaging unit to monitor the angular position of said object or location with respect to said device.

11. The device according to claim 1 further comprising a command interface to send commands to the data processing unit in order to confirm a selection of an option associated with the determined gaze direction.

12. The device according to claim 1 further comprising a distance monitor to determine the distance between said eye and said first imaging unit.

13. The device according to claim 1 further comprising means to change the direction of said first collimated light beam and/or the direction of said second collimated light beam with respect to said device.

14. A method for detecting gaze direction of an eye, said method comprising:

directing a first substantially collimated light beam towards the eye in order to provide a first reflection spot when light is reflected from the surface of the eye,

directing a second substantially collimated light beam towards the eye in order to provide a second reflection spot when light is reflected from the surface of the eye, said second collimated light beam having a direction different from the direction of said first collimated light beam,

acquiring an image of the eye by a first imaging unit,

determining the gaze direction of said eye with respect to said first imaging unit based on the position of said first reflection spot in said image, on the position of said second reflection spot in said image, on the position of the pupil and/or iris of the eye in said image, and on the directions of the collimated light beams.

15. The method according to claim 14 wherein at least one of said collimated light beams is provided using one or more diffractive beam expanders.

16. The method according to claim 14 wherein the width of the collimated light beams is greater than equal to 20 mm.

17. The method according to claim 14 wherein the distance between the first imaging unit and the eye is smaller than or equal to 0.2 m.

18. The method according to claim 14 further comprising associating an object or a location with a gaze direction.

19. The method according to claim 18 further comprising determining the angular position of said object or said location with respect to said first imaging unit based on an image of said object or location acquired by a further imaging unit.

20. The method according to claim 14 further comprising:

displaying a virtual image, and

associating a location of said virtual image with a gaze direction.

21. The method according to claim 14 further comprising selecting an option or a target based on the detected gaze direction of said eye.

22. The method according to claim 14 further comprising varying the direction of said first collimated light beam and/or the direction of said second collimated light beam.

23. The method according to claim 14 wherein said first collimated beam and said second collimated beam are provided using pixels of a micro-display.

24. The method according to claim 14 wherein said first collimated beam and said second collimated beam are provided using light-emitting semiconductor devices.

25. The method according to claim 14 further comprising sending image data to a remote data processing unit, and performing said determination in the remote data processing unit.

26. A portable device comprising an eye tracking device for detecting gaze direction of an eye, said tracking device comprising:

a first imaging unit to acquire an image of said eye,

at least one illuminating unit to provide a first substantially collimated light beam and a second substantially collimated light beam, said collimated light beams having different directions with respect to said device such that said first collimated light beam provides a first reflection spot when light is reflected from the surface of the eye and that said second collimated light beam provides a second reflection spot when light is reflected from the surface of the eye, said reflection spots appearing in said image, and

a data processing unit to determine the gaze direction of the eye with respect to said tracking device based on the position of said first reflection spot in said image, on the position of said second reflection spot in said image, on the position of the pupil and/or iris of the eye in said image, and on the directions of the collimated light beams.

27. The portable device according to claim 26 further configured to provide wireless communication capabilities.

28. A computer readable medium stored with computer program code sections for determining the gaze direction of an eye, which when executed by a processor are for determining a gaze direction of an eye with respect to an imaging unit, said imaging unit to acquire an image of an eye, based on a position of a first reflection spot in said image, on a position of a second reflection spot in said image, on a position of the pupil and/or iris of the eye in said image, and on the directions of a first substantially collimated light beam and a second substantially collimated light beam, said collimated light beams having different directions with respect to said imaging unit such that said first collimated light beam provides a said first reflection spot when light is reflected from the surface of the eye and that said second collimated light beam provides said second reflection spot when light is reflected from the surface of the eye, said reflection spots appearing in said image.

29. The computer readable medium according to claim 28, wherein said computer program code sections are for:

determining the angular position of a first reflection point and the angular position of a second reflection point on the surface of the eye based on the coordinates of said two reflection spots,

determining the direction of a first surface normal at said first reflection point and a second surface normal at said second reflection point based on the directions of said collimated light beams and the directions of a first vector and a second vector, said first vector being designated by the principal point of said imaging unit and said first reflection point, and said second vector being designated by the principal point of said imaging unit and said second reflection point,

determining a third vector which is substantially perpendicular to said surface normals,

determining the lengths of said first, second and third vector,

approximating the position of the eye center by a point on the third vector, said point being preferably the mid-point of the third vector,

determining the direction of a fourth vector based on the coordinates of the pupil and/or iris in said image, said fourth vector being designated by the principal point of said imaging unit and the pupil center,

determining the position of the pupil center, and

providing the gaze direction based on the position of said approximated eye center and said pupil center.

30. A device for detecting gaze direction of an eye, said device comprising:

means for acquiring an image of said eye,

means for providing a first substantially collimated light beam and a second substantially collimated light beam, said collimated light beams having different directions with respect to said device such that said first collimated light beam provides a first reflection spot when light is reflected from the surface of the eye and that said second collimated light beam provides a second reflection spot when light is reflected from the surface of the eye, said reflection spots appearing in said image, and

means for determining the gaze direction of the eye with respect to said device based on the position of said first reflection spot in said image, on the position of said second reflection spot in said image, on the position of the pupil and/or iris of the eye in said image, and on the directions of the collimated light beams.