Gradient Refractive Index Protective Layer for Head-Mounted Display
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Solution Overview
Problem
Head-mounted displays using virtual and augmented reality technologies face issues with color shift and low optical efficiency due to light emitted at large exit angles, affecting image quality and field of view.
Innovation Solution
A head-mounted display optical module featuring a gradient refractive index protective layer that adjusts the exit angle of light emitted by the display panel, matching different refractive indexes along the radial direction to optimize light projection and reduce color shift, thereby improving optical efficiency and image quality at various viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If light is emitted at a large exit angle to expand the field of view, then the field of view is improved, but color shift occurs and optical efficiency decreases
Solution Approach 1:
The protective layer is designed with a gradient refractive index distribution where the refractive index varies continuously from the center to the edge of the layer. This local variation in optical properties allows different regions of the layer to handle light at different angles appropriately, correcting color shift at large exit angles while maintaining optical efficiency
Solution Approach 2:
The refractive index parameter of the protective layer is changed continuously across its thickness and radial position. By controlling the refractive index distribution (e.g., decreasing from center to edge), the optical path of light at different angles is adjusted, thereby correcting color shift and improving optical efficiency without limiting the field of view
2Adaptability or versatility
If light is emitted at a large exit angle to expand the field of view, then the field of view is improved, but optical efficiency decreases
Solution Approach 1:
The gradient refractive index structure creates local optical corrections that reduce total internal reflection and light loss at large exit angles. By adjusting the refractive index distribution, the optical path is optimized for different viewing angles, improving energy utilization efficiency while maintaining a wide field of view
Solution Approach 2:
By continuously varying the refractive index parameter across the protective layer, the optical efficiency is improved for light at large exit angles. The gradient distribution reduces optical losses and improves energy utilization without compromising the expanded field of view
3Device complexity
If a conventional protective layer with uniform refractive index is used, then the structure is simple, but it cannot correct color shift at large viewing angles
Solution Approach 1:
Instead of a uniform structure, the protective layer employs a gradient refractive index design where optical properties vary locally across the layer. This allows the single protective layer to perform multiple functions: protection, color shift correction, and optical efficiency improvement, without significantly increasing structural complexity
Solution Approach 2:
The protective layer uses composite material design with gradient composition to achieve varying refractive indices. This can be implemented through layered composite structures or compositional gradients, enabling color shift correction while maintaining a relatively simple overall structure
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 reduces the design requirements for the display panel, minimizes large viewing angle color shift, and enhances optical efficiency, allowing users to observe images without color distortion at a large field of view while improving energy utilization.
Implementation Method 1
the refractive index of an interior of the first protective layer continuously changes at least along a radial direction... different positions of the first protective layer have different refractive indexes... the first protective layer can amplify the exit angle of the light emitted by the display panel
Data Source
AI summary
A head-mounted display optical module includes an optical lens group located at a light-emitting display side of the display panel and a protective layer located on an optical path between the display panel and the optical lens group. The protective layer includes at least one first protective layer. A refractive index of the first protective layer continuously changes therein at least along a radial direction that is located in a plane of the first protective layer and points from a center of the first protective layer to an edge of the first protective layer.