VISUAL DISPLAY WITH ILLUMINATORS FOR GAZE TRACKING

• US 20110069277A1
• Filed: 03/31/2010
• Published: 03/24/2011
• Est. Priority Date: 04/01/2009
• Status: Active Grant

• Current Assignee: Tobii Technology AB
• Original Assignee: Tobii Technology AB
• Inventors: Hoglund, Anders, Rehnstrom, Bengt, Elvesjö, John, BLIXT, Peter
• Granted Patent: US 8,220,926 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: G01S 17/46 Indirect determination of position data
• CPC Class Codes: G01S 17/66 Tracking systems using electromagnetic waves other than radio waves
• CPC Class Codes: G06F 3/01 Input arrangements or combined input and output arrangements for interaction between user and computer G06F3/16 takes precedence
• CPC Class Codes: G06F 3/013 Eye tracking input arrangements G06F3/015 takes precedence
• CPC Class Codes: G06V 40/19 Sensors therefor

Abstract

A visual display characterized by hidden reference illuminators is adapted to emit invisible light for generating corneo-scleral reflections on an eye watching a screen surface of the display. The tracking of such reflections and the pupil center provides input for gaze tracking. A method for equipping and an LCD with a reference illuminator are also provided. A system and method for determining a gaze point of an eye watching a visual display comprising reference illuminators are further provided. The determination of the gaze point may be based on an ellipsoidal cornea model.

Claims

1. A visual display comprising:

a plurality of reference illuminators adapted to emit invisible light; and

a screen surface adapted to display graphical information based on said plurality of reference illuminators arranged beneath said screen surface.

2. The visual display according to claim 1, wherein said plurality of reference illuminators are adapted to emit infrared or near-infrared light.

3. The visual display according to claim 1, wherein a light cone of each reference illuminator is essentially normal to said screen surface and subtends a solid angle of at most π

steradians.

4. The visual display according to claim 1, wherein said plurality of reference illuminators is arranged in a two-dimensional array, with the array being parallel to said screen surface.

5. The visual display according to claim 1, further comprising a plurality of layers provided beneath said screen surface and essentially parallel therewith, wherein any layer being arranged between said plurality of reference illuminators and said screen surface is operable to be translucent.

6. The visual display according to claim 1, wherein said visual display comprises a liquid crystal display comprising a light guide, which is optically coupled to an edge-mounted backlight illuminator, and a rear reflector layer, between which layers said plurality of reference illuminators is arranged.

7. The visual display according to claim 1, said visual display comprises a liquid crystal display comprising a plurality of direct backlight illuminators, and wherein a subset of said plurality of backlight illuminators is at least one reference illuminator.

8. The visual display according to claim 6, further comprising a liquid crystal panel with variable transmittance, said visual display being alternately operable in:

a display mode, wherein at least one backlight illuminator is active; and

a reference mode, wherein said plurality of reference illuminators are active, all backlight illuminators for emitting visible light are inactive, and said liquid crystal panel has maxium transmittance.

9. The visual display according to claim 1, wherein said visual display comprises an organic light-emitting diode display comprising a translucent anode layer, a conductive layer, an emissive layer and a translucent cathode layer, beneath which layers said plurality of reference illuminators are arranged.

10. The visual display according to claim 1, wherein said plurality of reference illuminators is adapted to illuminate an eye watching the visual display, with the eye being subject to gaze tracking.

11. A system for determining a gaze point of an eye watching a visual display, the visual display comprising a plurality of reference illuminators adapted to emit invisible light, and a screen surface adapted to display graphical information based on the plurality of reference illuminators arranged beneath the screen surface, the system comprising:

a camera for acquiring an image of the eye including corneo-scleral reflections of the reference illuminators; and

a processor adapted to

define, based on the locations of the corneo-scleral reflections in the image plane, a mapping between a coordinate system in the object plane and a coordinate system in the image plane; and

determine, based on the mapping, the eye'"'"'s gaze point in the object plane coordinate system, with the mapping comprising an ellipsoidal reflection mapping and a perspective projection.

12. The system according to claim 11, wherein said is arranged near a lower edge of a screen surface of the visual display.

13. A method for equipping a liquid crystal display with a reference illuminator adapted to emit a beam of invisible light, the liquid crystal display comprising a screen surface adapted to display graphical information;

a plurality of layers, which are operable to be translucent, arranged beneath the screen surface and essentially parallel therewith; and

at least one opaque layer arranged beneath the plurality of layers, the method comprising the steps of;

a) providing a hole in the at least one opaque layer, the hole being commensurate with the beam of light; and

b) fixing, using a fastener, the reference illuminator in such a manner that the beam of light is essentially perpendicular to the screen surface and concentric with the hole.

14. A method for determining a gaze point of an eye watching a visual display comprising the steps of:

a) illuminating the eye by invisible light from a plurality of reference illuminators provided in an object plane;

b) acquiring an image of the eye including corneo-scleral reflections of the reference illuminators;

c) defining, based on the locations of the corneo-scleral reflections in the image plane, a mapping between a coordinate system in the object plane and a coordinate system in the image plane; and

d) determining, based on the mapping, the eye'"'"'s gaze point in the object coordinate system, with the mapping comprising an ellipsoidal reflection mapping and a perspective projection.

15. The method of claim 14, wherein the ellipsoidal reflection mapping comprises a prolate spherical reflection mapping.

16. The method according to claim 14, wherein the reference illuminators are arranged beneath a screen surface, adapted to display graphical information, of the visual display.