Hologram Light Guide Plate Intermediate Layer Optical Confinement

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Solution Overview

Problem

Hologram light guide plates used in head mount displays are susceptible to deterioration from water vapor and ultraviolet rays, leading to image blurring when protection layers are applied externally, as they can intercept image light intended for the user's eyes.

Innovation Solution

A hologram light guide plate design featuring an intermediate layer between the glass and protection layers, where the intermediate layer's refractive index is lower than the glass layers, ensuring image light is confined within the transfer layer and preventing it from leaking into the protection layers, thus maintaining image clarity and protecting the hologram layer from environmental degradation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a protection layer is provided to protect the hologram material from water vapor and ultraviolet ray, then the durability of the hologram light guide plate is improved, but the image light may transfer to the protection layer causing image blurring

Engineering Contradiction:

Improvedurability of hologram light guide plateVSAvoidimage clarity

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

An intermediate layer with lower refractive index than both the glass layer and protection layer is introduced between the glass layer and protection layer. This intermediate layer acts as an optical mediator that reflects image light back into the transfer layer while allowing the protection layer to remain in place for environmental protection. The refractive index difference creates total internal reflection at the interfaces, preventing image light from entering the protection layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If the hologram light guide plate is made highly transparent for clear image transfer, then the image quality is improved, but the hologram layer becomes vulnerable to deterioration from water vapor and ultraviolet ray

Engineering Contradiction:

Improveimage qualityVSAvoidvulnerability to water vapor and ultraviolet ray

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The light guide plate is segmented into distinct functional layers: a transfer layer (glass layer + hologram layer) for image light transmission and a protection layer for environmental protection, separated by an intermediate layer. This segmentation allows each layer to be optimized for its specific function - the transfer layer for optical performance and the protection layer for durability - without compromising the other.

Inventive Principle:

Principle #1Segmentation

3Object-affected harmful factors

If a protection layer is added to shield the hologram layer, then the resistance to environmental factors is improved, but the device structure becomes more complex

Engineering Contradiction:

Improveresistance to environmental factorsVSAvoidstructure complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The intermediate layer is strategically positioned only where needed - between the glass layer and protection layer at the boundaries of the transfer layer - rather than throughout the entire structure. This localized application provides the necessary optical confinement exactly where image light might escape, while minimizing overall structural complexity and material usage.

Inventive Principle:

Principle #3Local quality

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 configuration allows for a highly transparent hologram light guide plate that can be used in outdoor environments for extended periods without image degradation, as it prevents water vapor and ultraviolet ray exposure from affecting the hologram layer, ensuring clear image transmission to the user.

Implementation Method 1

the intermediate layer's refractive index is lower than the glass layers, ensuring image light is confined within the transfer layer

Methodology Applied

Scientific EffectRefraction: Refraction

Implementation Method 2

a hologram light guide plate using diffraction by means of refractive index modulation

Methodology Applied

Scientific EffectDiffraction: Diffraction

Data Source

PatentUS11493759B2Hologram light guide plate with plurality of layers and head mount display using hologram light guide plate

Publication Date: 2022.11.08 HITACHI LG DATA STORAGE INC

AI summary

It is an objective of this disclosure to protect a highly transparent hologram light guide plate from water vapor and ultraviolet ray, thereby suppressing deterioration of the hologram light guide plate even when employed in a head mount display used in outdoor environments. A hologram light guide plate according to this disclosure comprises a protection layer that protects a hologram layer and an intermediate layer that is placed between a glass layer and the protection layer, wherein the glass layer and the hologram layer form a transfer layer that transfers image light. The intermediate layer causes the image light to transfer only in the transfer layer in a section from an input area of the image light to an output area of the image light.