Convertible Waveguide Optical Engine for HMD Eye Relief
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Solution Overview
Problem
Conventional head-mounted displays (HMDs) suffer from limitations such as small eye relief, eye box, and field of view due to the use of microdisplays with refractive optics.
Innovation Solution
The use of a waveguide optical engine assembly that includes a microprojector paired with a waveguide, enclosed within an opaque housing, which allows for improved eye relief, eye box, and field of view, while reducing energy requirements and footprint.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional microdisplays with refractive optics are used, then the HMD structure is simple, but the eye relief, eye box, and field of view are limited
Solution Approach 1:
The patent introduces a waveguide as an intermediary optical element between the microdisplay and the user's eye. The waveguide receives light from the microdisplay through a coupling optics system and guides it to the user's eye, enabling extended eye relief and larger eye box while maintaining system compactness. This intermediary structure resolves the contradiction by decoupling the physical distance constraints from the optical path requirements.
2Use of energy by moving object
If the waveguide is enclosed in an opaque housing, then energy efficiency improves and environmental light interference is reduced, but the device volume increases
Solution Approach 1:
The patent applies local quality by making only the necessary portions of the housing opaque - specifically the regions where environmental light would interfere with the waveguide optical engine. The housing is transparent or open in other regions to minimize volume. This selective application of opacity achieves energy efficiency and light interference reduction without unnecessarily increasing overall device volume.
3Manufacturing precision
If the waveguide optical engine is enclosed to prevent environmental light interference, then image quality improves, but the device footprint increases
Solution Approach 1:
The patent employs nesting by placing the waveguide optical engine assembly within a compact housing structure that integrates with the overall HMD design. The opaque enclosure is nested within the existing device form factor, and the optical components are arranged in a nested configuration where the microdisplay, coupling optics, and waveguide are closely integrated. This nesting approach protects the optical engine from environmental light interference while minimizing the increase in device footprint.
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
The waveguide optical engine assembly provides enhanced eye relief, eye box, and field of view, while reducing power consumption and maintaining image quality by preventing environmental light interference.
Implementation Method 1
waveguide optical engine assembly that includes a microprojector paired with a waveguide
Implementation Method 2
prism for projecting a source image projected by the microprojector to the waveguide
Data Source
AI summary
A head-mounted computing device having a convertible waveguide optical engine assembly is disclosed. The waveguide in accordance with aspects herein can be utilized in its transparent configuration, or may be provided with means for blocking light from passing through it either by using mechanical means, or by using different types of treatments that can switch the waveguide between opaque and transparent states based on an external stimulus, such as, for example, electricity, temperature, light, and the like. Further, the waveguide optical engine assembly comprises a compact footprint, which is advantageous for head-mounted computing devices. In addition to the compact footprint of the waveguide optical assembly, the configuration of the waveguide optical assembly, as disclosed, allows for maximization of advantages provided by the waveguide as related to eye box and eye relief.