Virtual-Image Display Device with Cholesteric Liquid Crystal Layers

Solution Overview

Problem

Existing see-through type virtual-image display devices face challenges with light shielding by the display, leading to low light utilization efficiency and potential image light leakage.

Innovation Solution

A virtual-image display device is designed with a display section outputting circularly polarized image light, a first reflection member with a flat surface and a transmissive reflection layer, and a second reflection member with a positive power and a cholesteric liquid crystal layer, optimizing the reflection and polarization of image light to enhance light utilization efficiency and prevent leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a display is disposed in front of eyes in a see-through type virtual-image display device, then a virtual image can be displayed, but light shielding by the display occurs leading to low light utilization efficiency and image light leakage

Engineering Contradiction:

Improvevirtual image display functionVSAvoidlight utilization efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The optical system is divided into multiple functional components: a first reflection member with a first optical function layer (transmissive reflection layer or cholesteric liquid crystal layer) and a second reflection member with a second optical function layer (the other type). This segmentation allows different parts of the optical path to handle different aspects of light control, improving overall light utilization efficiency while maintaining virtual image display functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different optical function layers are applied to different reflection members based on their specific functional requirements. The first reflection member uses one type of optical function layer while the second uses the other, creating local optimization of light control properties throughout the optical path to prevent leakage and improve efficiency.

Inventive Principle:

Principle #3Local quality

2Reliability

If a display is disposed in front of eyes in a see-through type virtual-image display device, then a virtual image can be displayed, but image light leakage occurs reducing privacy

Engineering Contradiction:

Improvevirtual image display functionVSAvoidimage light leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The optical system is divided into multiple functional components: a first reflection member with a first optical function layer (transmissive reflection layer or cholesteric liquid crystal layer) and a second reflection member with a second optical function layer (the other type). This segmentation allows different parts of the optical path to handle different aspects of light control, improving overall light utilization efficiency while maintaining virtual image display functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different optical function layers are applied to different reflection members based on their specific functional requirements. The first reflection member uses one type of optical function layer while the second uses the other, creating local optimization of light control properties throughout the optical path to prevent leakage and improve.

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

The solution effectively prevents image light leakage while maintaining a high light utilization efficiency, allowing for a clear virtual image to be overlapped with the outside-world image, ensuring privacy and improved display performance.

Implementation Method 1

a second reflection member having a positive power and configured to reflect, toward the first reflection member, the image light reflected at the first reflection member, in which the first reflection member includes a first optical function layer that is one of a cholesteric liquid crystal layer and a transmissive reflection layer, and the second reflection member includes a second optical function layer that is the other one of the cholesteric liquid crystal layer and the transmissive reflection layer

Methodology Applied

Scientific EffectCholesteric liquid crystal reflection: Cholesteric Liquid Crystal

Implementation Method 2

a first reflection member having a flat surface and configured to reflect the image light to a diagonal direction

Methodology Applied

Scientific EffectTransmissive reflection: Reflection

Implementation Method 3

the reflective polarizer is a reflective type CLC circular polarizer, for example. In this optical system, light from the display passes through the circular polarizer to turn into, for example, left-handed circularly polarized light

Methodology Applied

Scientific EffectCircular polarization conversion: Polarisation

Data Source

PatentUS20250138321A1Virtual-image display device and optical unit

Publication Date: 2025.05.01 SEIKO EPSON CORP

AI summary

A virtual-image display device or an optical unit includes a first display device configured to output image light of circularly polarized light; a first reflection member having a flat surface and configured to reflect the image light to a diagonal direction; and a second reflection member having a positive power and configured to reflect, toward the first reflection member, the image light reflected at the first reflection member. The first reflection member includes a first optical function layer that is one of a cholesteric liquid crystal layer and a transmissive reflection layer. The second reflection member includes a second optical function layer that is the other one of the cholesteric liquid crystal layer and the transmissive reflection layer.