Head-Mounted Display Optical Adjustment Element for Stray Light Reduction

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Solution Overview

Problem

Current VR head-mounted displays suffer from inefficient light usage and stray light due to uncontrolled light-emitting cone angles and directions, which degrade image quality, especially when using Fresnel lenses.

Innovation Solution

A head-mounted display apparatus comprising a light source module, an optical adjustment element, a display module, and a lens element, where the optical adjustment element, typically a Fresnel lens, is positioned between the light source and display modules to deflect the maximum light-emitting intensity towards a central point, improving light usage efficiency and reducing stray light without additional light shielding elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a Fresnel lens is used as the eyepiece to achieve lightness and slimness, then the device becomes lighter and thinner, but the image quality is sacrificed

Engineering Contradiction:
Improveweight of VR head-mounted displayVSAvoidimage quality
Core Design Contradiction:
Weight of moving objectVSManufacturing precision

Solution Approach 1:

An optical adjustment element is introduced as an intermediary component between the light source module and the display module. This element redirects the illumination beam to align with the display module's light-emitting direction, ensuring that light reaches the eyepiece efficiently without requiring additional shielding structures that would increase weight.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical adjustment element changes the transmission direction parameter of the illumination beam by deflecting it towards the central point of the display module. This parameter change ensures optimal light coupling with the display module's emission pattern, improving image quality while maintaining the lightweight Fresnel lens design.

Inventive Principle:
Principle #35Parameter changes

2Device complexity

If the light-emitting cone angle and light-emitting direction are not controlled, then the device structure is simpler, but a part of the light is wasted and stray light is produced which decreases the image quality

Engineering Contradiction:
Improvestructure complexityVSAvoidimage quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The optical adjustment element serves as a mediator that controls the illumination beam's direction without requiring complex light shielding structures. It efficiently redirects light to match the display module's emission pattern, preventing light waste and stray light while maintaining structural simplicity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

By changing the transmission direction parameter of the illumination beam through the optical adjustment element, the system achieves precise control over light propagation. This ensures that light is emitted in the correct direction with appropriate cone angle, eliminating stray light and improving image quality without adding structural complexity.

Inventive Principle:
Principle #35Parameter changes

3Manufacturing precision

If additional light shielding elements are added to reduce stray light, then stray light is reduced, but the device complexity increases

Engineering Contradiction:
Improveimage qualityVSAvoidstructure complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

Instead of adding light shielding elements, an optical adjustment element is used as an intermediary to actively control and redirect the illumination beam. This approach reduces stray light by directing light where it is needed, avoiding the need for additional shielding structures that would increase device complexity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The optical adjustment element converts the potentially harmful effect of uncontrolled light emission into a beneficial directed beam. By deflecting the illumination beam towards the central point of the display module, it transforms what would be stray light into useful directed light, eliminating the need for shielding elements.

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

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 light usage efficiency and reduces stray light, improving image quality and ANSI contrast without the need for additional light shielding, achieving better optical performance with a smaller light-emitting angle and deflection angle.

Implementation Method 1

The optical adjustment element is located between the light source module and the display module. The transmission direction of the maximum light-emitting intensity of the illumination beam transmitted from the light source module to the optical adjustment element is different to the transmission direction of the maximum light-emitting intensity of the illumination beam transmitted from the optical adjustment element to the display module.

Methodology Applied
Scientific EffectLight deflection: Refraction

Implementation Method 2

The lens element is disposed on a transmission path of the image beam

Methodology Applied
Scientific EffectLight focusing: Lens

Implementation Method 3

The display module is disposed on the transmission path of the illumination beam, and is configured to convert the illumination beam into an image beam

Methodology Applied
Scientific EffectLight modulation: Liquid Crystals

Data Source

PatentEP3674772B1Head-mounted display apparatus
Publication Date: 2023.04.26 CORETRONIC CORPORATION
  • EP3674772B1 patent drawingFigure 1~2
  • EP3674772B1 patent drawingFigure 3
  • EP3674772B1 patent drawingFigure 4~5

AI summary

A head-mounted display apparatus including a light source module, an optical adjustment element, a display module and a lens element is provided. The light source module provides an illumination beam. The optical adjustment element and the display module are disposed on a transmission path of the illumination beam, and the display module is configured to convert the illumination beam into an image beam. The optical adjustment element is located between the light source module and the display module. The lens element is disposed on a transmission path of the image beam, wherein a transmission direction of the maximum light-emitting intensity of the illumination beam transmitted from the light source module to the optical adjustment element is different to a transmission direction of the maximum light-emitting intensity of the illumination beam transmitted from the optical adjustment element to the display module.