Waveguide Mounting Using Peripheral Adhesive for AR Headsets
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Solution Overview
Problem
Mechanical and thermal stresses in head-mounted display (HMD) devices cause image distortion in waveguides used for augmented reality (AR) visualization, as conventional mounting methods fail to isolate these components from stress-induced deformations.
Innovation Solution
A waveguide assembly with a carrier that suspends output waveguides from a central location using soft, pressure-sensitive adhesive, maintaining waveguide flatness and isolating them from mechanical and thermal stresses, thereby reducing distortion and enhancing resistance to shocks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional mounting methods are used to attach waveguides in HMD devices, then the waveguides are securely fixed in place, but mechanical and thermal stresses cause image distortion in the waveguides
Solution Approach 1:
The mounting structure is divided into separate functional zones: a rigid carrier structure for positioning and a compliant adhesive layer for stress isolation. This segmentation allows the fixed carrier to provide secure mounting while the compliant adhesive layer absorbs mechanical and thermal stresses, preventing stress transmission to the waveguides and maintaining image quality.
Solution Approach 2:
A compliant adhesive layer is introduced as an intermediary between the rigid waveguide carrier and the waveguides. This intermediary layer decouples the rigid mounting structure from the sensitive optical components, allowing it to absorb differential expansion and mechanical stresses while maintaining secure attachment, thus preventing image distortion.
2Stability of the object's composition
If rigid mounting structures are used to hold waveguides, then structural stability is improved, but stress-induced deformations and image distortion occur
Solution Approach 1:
The adhesive layer's mechanical parameters (modulus, thickness) are optimized to create a compliant mounting interface. By changing the stiffness parameter of the mounting interface from rigid to compliant, the structure maintains stability through the rigid carrier while the compliant adhesive absorbs stress variations, preventing stress-induced deformations in the waveguides.
Solution Approach 2:
The mounting system uses a composite structure combining rigid carrier material (for structural stability) and compliant adhesive material (for stress absorption). This composite approach integrates both rigid and flexible properties in a single mounting system, achieving structural stability while eliminating stress-induced deformations.
3Ease of manufacture
If waveguides are mounted using traditional adhesive methods, then assembly is simplified, but thermal and mechanical stresses cause curvature and distortion
Solution Approach 1:
The adhesive layer thickness is increased beyond conventional mounting standards to create a compliant mounting interface. This parameter change transforms the adhesive from a thin rigid bond to a thick compliant layer that absorbs thermal and mechanical stresses, maintaining waveguide flatness while preserving assembly simplicity.
4Manufacturing precision
If waveguides are isolated from mounting structures to reduce stress, then image distortion is reduced, but secure fixation and alignment are compromised
Solution Approach 1:
The compliant adhesive layer serves as an intermediary that simultaneously achieves both secure fixation and stress isolation. It provides sufficient bonding strength to hold the waveguides firmly in alignment while its compliance prevents stress transmission, thus maintaining both secure fixation and image quality.
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 solution effectively maintains waveguide flatness and reduces image distortion, ensuring high-quality AR visualization and increased durability against mechanical stress and thermal variations.
Implementation Method 1
a first layer of adhesive that contacts only a periphery of a surface of the first left waveguide
Data Source
AI summary
Disclosed is a waveguide assembly for a head-mounted display device. The waveguide assembly can comprise a waveguide carrier, a first left waveguide, and a first right waveguide. The waveguide carrier can include a nose bridge portion, and flat left and right mounting surfaces extending from the nose bridge portion, to align with a left eye and a right eye, respectively, of a user of the head-mounted display device. The first left waveguide can be affixed to the left mounting surface of the waveguide carrier only by a first layer of adhesive disposed only around a periphery of a surface of the first left waveguide, while the first right waveguide can be affixed to the right mounting surface of the waveguide carrier only by a second layer of the adhesive disposed only around a periphery of a surface of the first right waveguide.