Pupil Illuminator Optical Element for Eye Tracking
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Solution Overview
Problem
Wearable devices with eye monitoring capabilities face design aesthetics limitations and reliability issues due to the need for illumination sources, typically infrared lights, which are often positioned in front of the eye, making the devices more visible and potentially stiffening the hinge where electrical connections are made.
Innovation Solution
An optical element for a head-mountable display that includes a lens with a concave surface, an embedded reflector, a reflective polarizer, and a retarder, which directs infrared light emitted from a light source toward the pupil, allowing for eye tracking without compromising the user's view of the world or digital images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If infrared illumination sources are positioned in front of the eye for eye monitoring, then eye tracking functionality is achieved, but device visibility increases and hinge reliability decreases
Solution Approach 1:
The illumination source is relocated from the traditional front-position (horizontal dimension near the eye) to the temporal dimension (side of the eyewear frame). This spatial repositioning in another dimension allows the illumination function to be achieved while removing the conflict with the hinge area, thus maintaining hinge reliability while enabling eye tracking.
2Adaptability or versatility
If infrared illumination sources are positioned in front of the eye, then eye monitoring is enabled, but design aesthetics are compromised
Solution Approach 1:
By moving the illumination source to the temporal position on the eyewear frame rather than the front position, the design achieves eye monitoring capability while maintaining a more aesthetically pleasing appearance. The illumination component is positioned in a less visually prominent area, preserving the overall design aesthetics.
Solution Approach 2:
The patent introduces a temporal positioning structure as an intermediary between the eye monitoring function and the eyewear design. This intermediary position allows the illumination source to be coupled to the eyewear frame in a way that achieves functional requirements while minimizing impact on design aesthetics.
3Adaptability or versatility
If electrical connections pass through the hinge for front-positioned illumination, then illumination function is achieved, but connection reliability decreases due to hinge stiffness
Solution Approach 1:
The illumination source and its electrical connections are extracted from the hinge area by repositioning them to the temporal position on the eyewear frame. This extraction removes the conflicting requirement of passing electrical connections through the hinge, thereby maintaining both the illumination function and the reliability of the hinge and its connections.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables effective eye tracking while maintaining the design aesthetics and reliability of the wearable device by positioning the illumination system elsewhere, ensuring that world view images and digital images are not compromised, and reducing the stiffness of the hinge.
Implementation Method 1
an optical element that transmits light, where light emitted from the light source is directed by the optical element toward the pupil of the eye
Implementation Method 2
The light source can emit infrared light that is not visible to the human eye
Implementation Method 3
an embedded reflector disposed therebetween
Implementation Method 4
a reflective polarizer aligned to a first polarization direction and disposed adjacent the concave first major surface; and a retarder between the reflective polarizer and the embedded reflector, the retarder having a fast axis aligned at a retarder angle to the first polarization direction
Data Source
AI summary
The present disclosure provides for an optical element useful in an optical device for illuminating the pupil of an eye, particularly for use with a head mountable display that can include eye-tracking. The optical device includes a light source and an optical element that transmits light, where light emitted from the light source is directed by the optical element toward the pupil of the eye, and attributes of the eye can then be detected by an optical sensor such as a camera. The light source can emit infrared light that is not visible to the human eye, so that world view images and/or combined digital images of the head-mountable display are not compromised.