Capacitance-based eye tracker

Abstract

An eye-tracking system, including at least one vertical capacitance sensor, configured to measure the vertical position of a cornea of a user’s eye by sensing a position of an eyelid of the user; and at least one horizontal capacitance sensor, configured to measure the horizontal position of the cornea of the user’s eye by sensing a position of the user’s eyeball.

1 . An eye-tracking system, comprising:
 a first vertically measuring capacitance sensor, configured to measure the vertical position of a cornea of a user’s eye by sensing a position of an eyeball and an eyelid of the user;   a first horizontally measuring capacitance sensor, configured to measure the horizontal position of the cornea of the user’s eye by sensing a position of the user’s eyeball, wherein at least one of the first horizontally measuring capacitance sensor and the second vertically measuring capacitance sensor is a composite substrate including carbon nanotubes.   
     
     
         2 . The eye-tracking system of  claim 1 , further comprising a second horizontally measuring capacitance sensor configured to measure the horizontal position of the cornea of the user’s eye by sensing a position of the user’s eyeball. 
     
     
         3 . The eye-tracking system of  claim 2 , wherein the first horizontally measuring capacitance sensor and the second horizontally measuring capacitance sensor operate using differential measurement to measure the horizontal position of the cornea of the user’s eye. 
     
     
         4 . The eye-tracking system of  claim 1 , further comprising a second vertically measuring capacitance sensor configured to measure the vertical position of the cornea of the user’s eye by sensing a position of the user’s eyeball. 
     
     
         5 . The eye-tracking system of  claim 4 , wherein the first vertically measuring capacitance sensor and the second vertically measuring capacitance sensor operate using differential measurement to measure the vertical position of the cornea of the user’s eye. 
     
     
         6 . The eye-tracking system of  claim 1 , wherein the first vertically measuring capacitance sensor is configured to be within 30 mm of the user’s eyelid covering the cornea and the first vertically measuring capacitance sensor is positioned within +/- 45 mm from a center of the cornea. 
     
     
         7 . The eye-tracking system of  claim 1 , wherein the first horizontally measuring capacitance sensor is positioned within the range of -30 mm towards a nose of the user to 40 mm away as measured from the center of the cornea. 
     
     
         8 . The eye-tracking system of  claim 1 , wherein the total number of horizontally measuring capacitance sensors is 2 or fewer. 
     
     
         9 . The eye-tracking system of  claim 1 , wherein the total number of vertically measuring capacitance sensors is 2 or fewer. 
     
     
         10 . The eye-tracking system of  claim 1 , wherein the first vertically measuring capacitance sensor and the first horizontally measuring capacitance sensor are mounted on an article configured to be positioned close to the user’s eye. 
     
     
         11 . The eye-tracking system of  claim 10 , wherein the article is selected from monocular or binocular lenses, eyeglass frames, an eye mask, goggles, and a mechanical support or adjustable ring configured to suspend the first vertically measuring and horizontally measuring capacitance sensors in space above the eye. 
     
     
         12 . The eye-tracking system of  claim 1 , wherein the composite substrate including carbon nanotubes includes a plurality of fibers and a plurality of carbon nanotubes bonded to the insulating fibers forming a nanotube coating on the insulating fibers. 
     
     
         13 . The eye-tracking system of  claim 1 , wherein the first vertically measuring capacitance sensor is comprised of a single electrode. 
     
     
         14 . The eye-tracking system of  claim 1 , wherein the first vertically measuring capacitance sensor is comprised of a first electrode and a second electrode. 
     
     
         15 . The eye tracking system of  claim 14 , wherein the first electrode is a carbon-nanotube composite electrode, and the second electrode is a metal electrode. 
     
     
         16 . The eye tracking system of  claim 14 , wherein the first electrode is a first carbon nanotube composite electrode, and the second electrode is a second carbon nanotube composite electrode. 
     
     
         17 . The eye tracking system of  claim 14 , wherein the first electrode and the second electrode are coated with an electrically conductive ink. 
     
     
         18 . The eye tracking system of any of  claim 14 , wherein there is a gap between the first electrode and the second electrode. 
     
     
         19 . The eye tracking system of  claim 18 , wherein the gap between the first electrode and the second electrode is in a range from 300 µm to 1 mm. 
     
     
         20 . The eye tracking system of  claim 1 , wherein the first horizontally measuring capacitance sensor is comprised of a single electrode. 
     
     
         21 . The eye-tracking system of  claim 1 , wherein the first horizontally measuring capacitance sensor is comprised of a first electrode and a second electrode. 
     
     
         22 . The eye tracking system of  claim 21 , wherein the first electrode is a carbon-nanotube composite electrode, and the second electrode is a metal electrode. 
     
     
         23 . The eye tracking system of  claim 21 , wherein the first electrode is a first carbon nanotube composite electrode, and the second electrode is a second carbon nanotube composite electrode. 
     
     
         24 . The eye tracking system of  claim 21 , wherein the first electrode and the second electrode are coated with an electrically conductive ink. 
     
     
         25 . The eye tracking system of  claim 21 , wherein there is a gap between the first electrode and the second electrode. 
     
     
         26 . The eye tracking system of  claim 25 , wherein the gap between the first electrode and the second electrode is in a range from 300 µm to 5 mm. 
     
     
         27 . The eye-tracking system of  claim 1 , further comprising an electronic control unit configured to control and receive measurement signals from the first horizontally measuring capacitance sensor and the first vertically measuring capacitance sensor. 
     
     
         28 . The eye-tracking system of  claim 27  further comprising instructions executable on the processor configured to apply machine learning and/or artificial intelligence to provide the output indicative of the position of the user’s eye. 
     
     
         29 . An eye-tracking system, comprising:
 an article comprising a left side and a right side;   a first vertically measuring sensor attached to the right side of the article;   a second vertically measuring sensor attached to left side of the article;   a first horizontally measuring sensor attached to the right side of the article; and   a second horizontally measuring sensor attached to the left side of the article;   wherein the first vertically measuring sensor and the first horizontally measuring sensor are configured to measure a vertical position and a horizontal position, respectively, of a cornea of a user’s right eye by sensing a position of a right eyelid of the user and the user’s right eyeball,   wherein the second vertically measuring sensor and the second horizontally measuring sensor are configured to measure a vertical position and a horizontal position, respectively, of a cornea of a user’s left eye by sensing a position of a left eyelid of the user and the user’s left eyeball, so that both a user’s right eye movements and left eye movements are sensed simultaneously, and wherein at least one of the first or second vertically measuring capacitance sensors and the first or second horizontally measuring capacitance sensor is a composite substrate including carbon nanotubes.   
     
     
         30 . A method of tracking a position of at least one eye of a user, the method comprising:
 mounting an eye-tracking system to the user, the eye-tracking system including a first vertically measuring capacitance sensor, configured to measure the vertical position of a cornea of a user’s eye by sensing a position of an eyeball and an eyelid of the user, and a first horizontally measuring capacitance sensor, configured to measure the horizontal position of the cornea of the user’s eye by sensing a position of the user’s eyeball, wherein at least one of the first vertically measuring capacitance sensor and the second horizontally measuring capacitance sensor is a composite substrate including carbon nanotubes; and   measuring capacitance from the first vertically measuring sensor and the first horizontally measuring sensor.