Head-Mounted Display Optics With Integrated Gaze Tracking LEDs
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Solution Overview
Problem
Incorporating gaze tracking circuitry into head-mounted devices is challenging due to its bulkiness when mounted far from the pupil, adding bulk to the device.
Innovation Solution
Integrating gaze tracking light-emitting diodes between a waveguide and a tint layer in a head-mounted display, with narrow traces in the transparent region to minimize visibility and bulkiness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gaze tracking circuitry is mounted far from the pupil, then gaze tracking function is achieved, but device bulkiness increases
Solution Approach 1:
The patent combines the gaze tracking light sources with the display optics by integrating them into the same optical path. The light sources are positioned within the display assembly, sharing the optical components and space with the display projector and waveguide, thereby eliminating the need for separate bulky mounting structures.
Solution Approach 2:
The patent transitions from a lateral mounting arrangement (where light sources are positioned far from the pupil in a different spatial dimension) to a integrated optical path arrangement where light sources are positioned within the optical path itself, utilizing the depth dimension of the display assembly to reduce lateral bulk.
2Volume of moving object
If light sources are integrated into the display, then device bulkiness is reduced, but visibility of light sources may increase
Solution Approach 1:
The patent applies different optical properties to different regions of the display assembly. The light sources are positioned in specific locations within the optical path where they do not interfere with the display output, and the waveguide and optical components are designed to direct light selectively, ensuring that the light sources remain invisible or imperceptible to the user while maintaining their gaze tracking function.
Solution Approach 2:
The patent uses the waveguide and optical components as intermediaries between the light sources and the user's eye. These intermediate optical elements guide and direct the light from the integrated sources along a specific path, allowing the sources to be hidden within the optical path while still performing their gaze tracking function without being directly visible to the user.
3Measurement precision
If light sources are mounted on the display perimeter, then gaze tracking is enabled, but user view is obstructed
Solution Approach 1:
The patent moves the light sources from the peripheral lateral positions to positions within the optical path depth dimension. By utilizing the depth dimension of the display assembly, the light sources are positioned along the optical path rather than at the periphery, allowing them to be integrated without obstructing the user's lateral view through the display.
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
Enhances gaze tracking accuracy while reducing the bulkiness of the device around the display perimeter, allowing seamless integration of gaze tracking circuitry without obstructing the user's view.
Implementation Method 1
One or more gaze tracking light-emitting diodes and/or other light sources may be interposed between the waveguide and the tint layer
Implementation Method 2
a waveguide that provides the display light and real-world light from the environment to the eye box
Implementation Method 3
An active tint layer or other light modulator layer may overlap the waveguide and may be used to adjust at least one of an intensity and color of real-world light that is transmitted through the active tint layer
Data Source
AI summary
A head-mounted display may include a transparent region through which a real-world environment is viewable from an eye box. The head-mounted display may include a projector that produces display light and a waveguide that provides the display light and real-world light from the environment to the eye box. A tint layer or other light modulator layer may overlap the waveguide and may be used to adjust at least one of intensity and color of real-world light that is transmitted through the tint layer. One or more gaze tracking light-emitting diodes and/or other light sources may be interposed between the waveguide and the tint layer and may be located within the transparent region of the head-mounted display. The light sources may be mounted to a transparent substrate that is laminated between the waveguide and the tint layer, or the light sources may be mounted to the tint layer.