Apple Wins an HMD Eye Tracking System Patent that details the use of Near Infrared Cameras and Hot Mirrors
On the last granted patent day of 2020, the U.S. Patent and Trademark Office officially granted Apple a patent for an eye tracking system for a VR/AR Head-Mounted Display System as illustrated in patent FIG. 1 above in our cover graphic. The system could be used in both a full VR headset and future smart glasses. The patent focuses on the details of the system more than end-user experiences.
Apple's future HMD may include an eye tracking system (which may also be referred to as a gaze tracking system) for detecting position and movements of the user's eyes, or for detecting other information about the eyes such as pupil dilation.
The point of gaze on the display estimated from the information captured by the eye tracking system may, for example, allow gaze-based interaction with the content shown on the near-eye display.
Other applications may include, but are not limited to, creation of eye image animations used in future avatars in a VR/AR environment.
Apple's granted patent details their eye tracking system may include at least one eye tracking camera (e.g., near-IR (NIR) cameras) positioned at each side of the user's face and pointed towards the eye-facing surfaces of the respective eyepieces, an illumination source (e.g., an NIR light source) that emits light (e.g., NIR light) towards the user's eyes, and hot mirrors located between the eye-facing surfaces of the eyepieces and the user's eyes.
Positioning the hot mirror surfaces at or near the eye-facing surfaces of the eyepieces allows the eye tracking cameras to be placed at the sides of the user's face (e.g., at or near the user's cheek bones) without having to image through the eyepieces as presented in Apple's patent FIG. 3 below.
In some embodiments, the light sources of the HMD emit NIR light to illuminate the user's eyes. A portion of the NIR light is reflected off the user's eyes to the hot mirrors located at or near the eye-facing surfaces of the eyepieces of the HMD. The hot mirrors reflect at least a portion of the NIR light, while allowing visible light to pass. The NIR cameras, for example located at or near the user's cheek bones capture images of the user's eyes reflected by the hot mirrors.
Images captured by the eye tracking system may be analyzed to detect position and movements of the user's eyes, or to detect other information about the eyes such as pupil dilation. For example, the point of gaze on the display estimated from the eye tracking images may enable gaze-based interaction with content shown on the near-eye display of the HMD. Other applications may include, but are not limited to, creation of eye image animations used for avatars in a VR/AR environment.
For more details, you could review our original patent application report or Apple's granted patent 10,877,556.