Optical Film Stack for VR Display Phase Retardation Compensation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing opto-mechanical modules in VR and MR devices face challenges with phase retardation compensation, particularly due to limitations in quarter-phase retardation films, leading to stray light and ghosting issues from high refractive indices and brittle liquid crystal polymers, which affect imaging quality.
Innovation Solution
An optical structure incorporating a compensation film with protruding structures and specific refractive index relationships to compensate for phase retardation, allowing flexible adjustment of phase retardation values and reducing reflections, thereby improving imaging quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a quarter-phase retardation film with high refractive index is used to compensate phase retardation, then the phase retardation compensation effect is improved, but stray light and ghosting occur due to high reflections
Solution Approach 1:
The compensation film is divided into multiple sub-compensation films stacked together, each with different refractive indices. This segmentation allows the system to achieve the required phase retardation compensation while distributing the refractive index values to reduce reflection and stray light, rather than using a single high refractive index material
Solution Approach 2:
The patent uses composite material structure by stacking multiple sub-compensation films with different refractive indices (e.g., 1.50, 1.55, 1.60) to create an effective medium that provides the needed phase retardation compensation while maintaining lower overall reflectivity compared to a single high refractive index film
2Manufacturing precision
If liquid crystal polymers are used for phase retardation compensation, then the compensation effect is improved, but the material becomes brittle and mechanical properties deteriorate
Solution Approach 1:
The patent replaces the expensive and brittle liquid crystal polymer material with alternative materials (such as cyclic olefin copolymer or other transparent polymers) that can be easily manufactured and have superior mechanical properties, achieving the same optical function without the brittleness and handling issues
Solution Approach 2:
The patent changes the material parameters by selecting polymers with appropriate refractive indices and optical properties that differ from liquid crystal polymers, achieving phase retardation compensation through material composition adjustment rather than relying on liquid crystal molecular orientation, thereby improving mechanical flexibility and durability
3Device complexity
If traditional compensation films are used, then the structure is simple, but imaging quality deteriorates due to insufficient phase retardation stabilization
Solution Approach 1:
The compensation function is segmented into multiple sub-compensation films with different refractive indices, where each layer contributes to the overall phase retardation compensation. This multi-layer structure provides better stabilization of phase retardation across different wavelengths and incident angles compared to a single-layer film
Solution Approach 2:
The patent optimizes optical parameters by carefully selecting and stacking materials with specific refractive indices to achieve precise phase retardation compensation, improving imaging quality through parameter optimization rather than relying on a single thick film with approximate properties
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 compensation film enhances imaging quality by stabilizing phase retardation and reducing stray light, offering superior mechanical properties and flexible production, addressing the limitations of traditional liquid crystal polymers.
Implementation Method 1
a refractive index of the compensation film in a thickness direction is nz, the compensation film has a maximum in-plane refractive index and a minimum in-plane refractive index in a plane parallel to a surface of the compensation film, the maximum in-plane refractive index and the minimum in-plane refractive index are nx and ny, respectively
Implementation Method 2
the compensation film has a maximum in-plane refractive index and a minimum in-plane refractive index in a plane parallel to a surface of the compensation film
Implementation Method 3
the opto-mechanical module regulates polarized light through a special polarized optical assembly to achieve an effect of lightness and thinness
Implementation Method 4
a combination of a display screen and a lens is known as an opto-mechanical module, and the existing opto-mechanical module includes a combination of a liquid crystal display (LCD) screen or a silicon-based organic light-emitting diode (OLED) screen with a folded optical-path lens
Data Source
AI summary
An optical structure and a display apparatus. The optical structure includes a lens structure, a beam splitting film, a reflective polarizing film, a phase retardation film and a compensation film. The lens structure includes a first surface and a second surface, the phase retardation film and the compensation film are arranged between the beam splitting film and the reflective polarizing film, the compensation film includes at least one sub-compensation film, the sub-compensation film includes a plurality of protruding structures spaced apart, a refractive index in a thickness direction of the compensation film is nz, the maximum in-plane refractive index and the minimum in-plane refractive index of the compensation film are nx and ny, respectively, and a thickness of the compensation film is d, nz, nx, ny, and d satisfy a following relational equation: nz>nx, nz>ny, (nx−ny)*d≤20 nm.