Liquid Crystal Optical Compensator for Head-Mounted Display Image Alignment
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Solution Overview
Problem
Conventional binocular head-mounted displays suffer from dipvergence and convergence issues due to manufacturing tolerances, leading to user discomfort such as amblyopia, headache, and nausea, which are addressed by increasing manufacturing precision or adding mechanical adjusting mechanisms, but these solutions complicate and cost the product.
Innovation Solution
The use of an optical compensator with a liquid crystal layer and control circuit to modulate the wavefront of image beams, altering their optical paths by changing the refractive index with applied voltage, thereby adjusting the positions of virtual images without adding mechanical complexity or weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If manufacturing precision is increased to eliminate dipvergence and convergence, then virtual image alignment is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies parameter changes by using liquid crystal materials whose refractive index can be dynamically adjusted through voltage application. This allows the optical compensator to correct virtual image misalignment by changing the refractive index parameter, eliminating the need for high-precision mechanical manufacturing while maintaining effective image alignment.
2Manufacturing precision
If mechanical adjusting mechanisms are added to correct virtual image positions, then dipvergence and convergence are reduced, but device complexity and weight increase
Solution Approach 1:
The patent replaces mechanical adjusting mechanisms with an optical compensator based on liquid crystal technology. Instead of using mechanical components to physically adjust image positions, the system uses voltage-controlled refractive index changes in liquid crystals to optically correct misalignment, thereby reducing mechanical complexity and weight while achieving the same functional goal.
Solution Approach 2:
The optical compensator dynamically changes the refractive index parameter of the liquid crystal material in response to applied voltage, enabling real-time adjustment of light paths to correct virtual image positions without mechanical movement.
3Manufacturing precision
If mechanical adjusting mechanisms are added to align virtual images, then convergence and dipvergence are corrected, but weight increases
Solution Approach 1:
The patent substitutes heavy mechanical adjusting mechanisms with a lightweight optical compensator using liquid crystal materials. The liquid crystal-based system achieves image alignment through optical property changes rather than mechanical movement, significantly reducing the weight of the head-mounted display while maintaining alignment functionality.
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
This approach reduces the complexity and manufacturing cost of the head-mounted display while effectively aligning virtual images to prevent user discomfort by precisely adjusting their positions, thus eliminating dipvergence and convergence problems.
Implementation Method 1
The wavefront of the image beams of the virtual images are modulated by changing the optical path difference of the image beams based on the characteristics that the refractive index of liquid crystals is changed with the voltage field applied thereto
Data Source
AI summary
A head mounted display includes two imaging apparatuses and at least one optical compensator. The imaging apparatuses can form two virtual images respectively in front of two eyes of a user. The optical compensator can modulate wavefront of the image beams of the virtual images so as to adjust the positions of the virtual images. In this manner, the positions of the two virtual images can be adjusted to substantially coincide with each other. The present invention also provides an image adjustment method for a head-mounted display.