VR Display Optical Stack Using Zero Anisotropy Solid

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Solution Overview

Problem

Current head mount display technologies for virtual reality struggle with maintaining high display quality, particularly in terms of minimizing unwanted reflections and ensuring efficient light usage, which can lead to issues like ghosting and color inaccuracies due to refractive anisotropy and wavelength dependency in the optical system.

Innovation Solution

The implementation of a display device with a specific optical system configuration that includes a display panel emitting linearly polarized light, quarter-wave retardation plates, a transflective layer with a concave surface, a transparent solid with almost zero refractive anisotropy, and a reflective polarizer, which collectively maintain polarization states and reduce unwanted reflections, focusing light efficiently onto the user's eyes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional optical systems are used in head mount displays, then the structure is simpler, but ghosting and color inaccuracies occur due to refractive anisotropy and wavelength dependency

Engineering Contradiction:

Improvedisplay qualityVSAvoidoptical system configuration

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The optical system is segmented into multiple functional layers: a display panel, a first retardation plate, a transflective layer, a second retardation plate, and a reflective polarizer. Each layer performs a specific function in managing light polarization and reflection, thereby eliminating ghosting and color inaccuracies while maintaining manageable system complexity through modular design

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent employs composite optical structures including retardation plates with specific refractive indices and a transflective layer with asymmetric reflectivity for different polarizations. These composite materials work together to control light properties precisely, achieving high display quality by compensating for refractive anisotropy and wavelength dependency effects

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If light is reflected multiple times in the optical system, then more light can reach the user's eyes, but unwanted reflections and ghosting increase

Engineering Contradiction:

Improvelight efficiencyVSAvoidunwanted reflections

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The reflective polarizer and transflective layer are configured to convert potentially harmful unwanted reflections into beneficial effects. By carefully designing the reflectivity characteristics for different polarizations, the system uses reflected light constructively to enhance illumination intensity while the polarization control eliminates ghosting and color inaccuracies

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The transflective layer is designed with asymmetric reflectivity that varies by location and polarization state. It reflects light with a first polarization state while transmitting light with a second polarization state, creating local quality differences that manage light paths precisely. This allows multiple light reflections to contribute to brightness without generating unwanted ghost images

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 enhances display quality by minimizing ghosting and light loss, while simplifying the optical system and ensuring accurate color representation, thereby providing an improved virtual reality experience.

Implementation Method 1

a display panel configured to emit display light of linear polarization

Methodology Applied

Scientific EffectLinear polarization: Polarisation

Implementation Method 2

the first retardation plate and the second retardation plate are a quarter-wave plate

Methodology Applied

Scientific EffectRetardation: Birefringence

Implementation Method 3

a reflective polarizer configured to pass first linear polarized light, and to reflect second linear polarized light which is orthogonal to the first linear polarized light

Methodology Applied

Scientific EffectPolarization reflection: Polarisation

Implementation Method 4

a transparent solid disposed between the transflective layer and the reflective polarizer, with almost zero refractive anisotropy

Methodology Applied

Scientific EffectRefractive anisotropy: Anisotropy

Implementation Method 5

a transflective layer disposed between the first retardation plate and the second retardation plate to be apart from the second retardation plate, and including a concave surface opposed to the second retardation plate

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS11500211B2Display device

Publication Date: 2022.11.15 MAGNOLIA WHITE CORP

AI summary

According to one embodiment, a display device including a display panel configured to emit display light of linear polarization, a first retardation plate, a second retardation plate, a reflective polarizer configured to pass first linear polarized light, and to reflect second linear polarized light, a transflective layer including a concave surface opposed to the second retardation plate, and a transparent solid with almost zero refractive anisotropy, wherein the first retardation plate and the second retardation plate are a quarter-wave plate, and the transparent solid includes a first surface shaped convex to be opposed to the concave surface, and a second surface opposed to the reflective polarizer.