Virtual Image Display Device Polarizer Glittering Suppression

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Solution Overview

Problem

Existing virtual image display devices with transmissive mirrors suffer from outside light patterns being projected and seen in a glittered manner due to reflection, causing discomfort and impaired eye contact when worn.

Innovation Solution

A virtual image display device incorporating a partially transmissive mirror with a reflective polarizer and a transmissive polarizer disposed outside, where the polarizers' axes are aligned to allow p-polarized outside light to pass through while absorbing s-polarized light, preventing unwanted reflections and projections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a transmissive mirror is used to allow simultaneous observation of image light and outside light, then visibility of virtual images and real-world scenes is improved, but outside light patterns are reflected on the mirror surface causing glittering and discomfort

Engineering Contradiction:

Improvevisibility of virtual images and real-world scenesVSAvoidglittering from outside light reflection

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by introducing polarizing filters that selectively transmit or reflect light based on polarization state. The first polarizing filter transmits p-polarized outside light while the second polarizing filter reflects s-polarized image light, creating different transmission/reflection characteristics for different light components to eliminate glittering while maintaining visibility

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses composite optical structures combining transmissive mirror, polarizing filters, and optical members. The combination of these components creates a system where the transmissive mirror provides see-through functionality while the polarizing filters control reflection characteristics to prevent glittering

Inventive Principle:

Principle #40Composite materials

2Loss of information

If an absorber layer is added to suppress image light leakage from the concave transmissive mirror, then image privacy is improved, but the glittering effect from outside light reflection remains

Engineering Contradiction:

Improveimage light leakage suppressionVSAvoidglittering from outside light reflection

Core Design Contradiction:

Loss of informationVSObject-affected harmful factors

Solution Approach 1:

The patent changes the optical parameters by introducing polarizing filters with specific transmission and reflection axes. The first polarizing filter transmits p-polarized outside light, while the second polarizing filter reflects s-polarized image light, creating selective optical control that addresses both image privacy and glittering suppression

Inventive Principle:

Principle #35Parameter changes

3Ease of operation

If the transmissive mirror has high transparency to allow outside light passage, then eye contact and natural appearance are improved, but more outside light is reflected causing glittering

Engineering Contradiction:

Improveeye contact capabilityVSAvoidreflected outside light patterns

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by using polarizing filters to control the polarization state of transmitted and reflected light. The first polarizing filter transmits p-polarized outside light to maintain natural appearance, while the second polarizing filter reflects s-polarized image light, reducing glittering effects

Inventive Principle:

Principle #35Parameter changes

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 effectively suppresses the glittering of outside light patterns on the mirror surface, enhancing eye contact and user comfort by minimizing reflections and maintaining a clear view of virtual images superimposed on real-world scenes.

Implementation Method 1

a transmissive polarizer is disposed outside the partially transmissive mirror

Methodology Applied

Scientific EffectPolarisation: Polarisation

Implementation Method 2

the polarizers' axes are aligned to allow p-polarized outside light to pass through while absorbing s-polarized light

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Implementation Method 3

a partially transmissive mirror configured to partially reflect the image light from the projection optical system toward a pupil position

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS20240004200A1Virtual image display device

Publication Date: 2024.01.04 SEIKO EPSON CORP

AI summary

A virtual image display device includes a display element that is an image light generation device, a projection optical system on which image light from the display element is incident, and a partially transmissive mirror configured to partially reflect the image light from the projection optical system toward a pupil position, and a transmissive polarizer is disposed outside the partially transmissive mirror.