Laminated Optical Device Shock Resistance
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Solution Overview
Problem
Glass light guide plates in head-mounted displays are prone to damage when dropped due to their brittle nature, making them unsuitable for applications requiring durability.
Innovation Solution
A laminated optical device structure comprising a first and second glass plate with a shock-absorbing layer in between, where deflection means such as hologram diffraction gratings are aligned and laminated to enhance shock resistance and maintain image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a glass light guide plate is used to achieve severe optical characteristics, then optical performance is improved, but shock resistance deteriorates
Solution Approach 1:
The light guide plate is divided into multiple glass plates (first glass plate and second glass plate) with a shock-absorbing layer in between. This segmentation allows each component to fulfill specific functions: the glass plates maintain optical characteristics while the intermediate layer provides shock absorption, resolving the contradiction between optical performance and durability.
Solution Approach 2:
The invention creates a composite structure combining glass plates with a shock-absorbing layer (made of resin or elastomer). This composite material approach integrates the optical transparency and surface quality of glass with the shock-absorbing properties of polymers, achieving both severe optical characteristics and improved shock resistance.
2Manufacturing precision
If a single glass plate is used, then optical characteristics are maintained, but durability upon dropping deteriorates
Solution Approach 1:
The single glass plate is segmented into multiple glass plates separated by a shock-absorbing layer. This segmentation transforms the monolithic fragile structure into a multi-layered system where the shock-absorbing layer acts as a buffer, preventing crack propagation and maintaining reliability while preserving optical characteristics through the transparent glass layers.
Solution Approach 2:
The shock-absorbing layer is positioned between the glass plates to provide beforehand cushioning against impact forces. This pre-positioned cushioning layer absorbs shock energy before it can damage the glass plates, ensuring durability upon dropping while maintaining the optical functionality of the glass components.
3Strength
If multiple glass plates are laminated with a shock-absorbing layer, then shock resistance is improved, but device complexity increases
Solution Approach 1:
The invention merges the light guide plate and protective cover into a single laminated structure where multiple glass plates and a shock-absorbing layer are bonded together. This merging integrates multiple functions (light guidance, protection, shock absorption) into one unified component, improving shock resistance while managing complexity through functional integration rather than separate components.
Solution Approach 2:
The laminated structure uses composite materials (glass plates combined with shock-absorbing resin or elastomer layer) to achieve enhanced shock resistance. The composite approach allows the structure to withstand impacts while maintaining a relatively simple overall form factor, as the different materials work together synergistically within a single integrated assembly.
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 laminated structure significantly enhances the shock resistance of the optical device while maintaining high parallelism and reducing light scattering, thus preventing damage from drops and ensuring image quality.
Implementation Method 1
a shock absorbing layer sandwiched between the first glass plate and the second glass plate
Implementation Method 2
a first diffraction grating member 930 and a second diffraction grating member 940 which are disposed on the light guide plate 921. Light emitted from each pixel 915 of the image forming device 911 enters the collimating optical system 912 through a convex lens 916, is converted into parallel light by the collimating optical system 912, and enters the light guide plate 921
Implementation Method 3
The parallel light thus diffracted or reflected travels while undergoing total reflection between the first surface 921A and the second surface 921B of the light guide plate 921
Data Source
AI summary
A display device is provided with (A) a frame that is worn on a head of a viewer, and (B) an image display device 100 mounted to the frame. The image display device is provided with (B-1) an image forming device 111, and (B-2) an optical device 120 that forms a virtual image on the basis of light emitted from the image forming device 111. The light from the image forming device 111 enters a pupil 21 of the viewer 20 through the optical device 120. The optical device 120 is provided at least with a first glass plate 121, a second glass plate 122 that faces the first glass plate 121, and a shock absorbing layer 123 sandwiched between the first glass plate 121 and the second glass plate 122.