Microlens Array for Head-Mounted Display Screen Door Effect
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Solution Overview
Problem
Head-mounted display devices suffer from a screen door effect due to the enlargement of both pixels and light blocking areas by the eyepiece lens, leading to a lattice pattern and increased weight and size.
Innovation Solution
A microlens array with varying focal distances and thicknesses is used to correspond with each pixel, preventing the screen door effect and reducing device weight and size, while a correction layer with varying thickness can be added to improve image quality by adjusting focal distances based on location.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If an eyepiece lens is used to display images, then the image can be enlarged as a virtual image, but the light blocking area between pixels is also enlarged causing a screen door effect
Solution Approach 1:
The patent divides the single eyepiece lens into multiple microlenses, each corresponding to a specific pixel or pixel group. This segmentation allows each microlens to independently control light from its corresponding pixel, preventing the light blocking areas between pixels from being collectively enlarged, thus eliminating the screen door effect while maintaining image display functionality
Solution Approach 2:
The patent applies different focal distances to different microlenses based on their position in the array. Microlenses closer to the pupil have shorter focal distances, while those farther away have longer focal distances. This local differentiation optimizes light control for each region, preventing the screen door effect in different viewing zones while maintaining overall image quality
2Illumination intensity
If an eyepiece lens is used to display images, then the image can be enlarged as a virtual image, but the device weight and size increase
Solution Approach 1:
The patent replaces the traditional eyepiece lens with a microlens array that replicates the light control function across multiple small lenses. Each microlens is a simplified version that handles light from a specific pixel, collectively achieving the same virtual image display function as a single large eyepiece lens but with reduced weight and size
Solution Approach 2:
The patent changes the optical parameters by using multiple microlenses with varying focal distances instead of a single eyepiece lens. This parameter change allows the system to maintain the virtual image display function while significantly reducing the overall weight and size of the head-mounted display device
3Object-affected harmful factors
If microlenses with varying focal distances are used, then the screen door effect is prevented and image quality is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent implements local quality by assigning different focal distances to microlenses at different positions in the array. This localized differentiation prevents the screen door effect in various viewing zones while maintaining a systematic manufacturing approach where the complexity is managed through positional variation rather than complete individual customization of each microlens
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 microlens array effectively prevents the screen door effect and reduces the weight and size of the head-mounted display, while the correction layer enhances image quality by minimizing Petzval field curvature, resulting in improved luminance and reduced image distortion.
Implementation Method 1
A microlens array that includes a plurality of lenses that respectively overlap the plurality of pixels
Implementation Method 2
The plurality of lenses may have different focal distances
Data Source
AI summary
The present disclosure relates to a head mounted display device, and a head mounted display device according to an exemplary embodiment includes: a display panel including a plurality of pixels; and a microlens array that includes a plurality of lenses that respectively overlap the plurality of pixels wherein the plurality of pixels and the plurality of lenses have one-to one correspondence.