AR Optical Structure With Embedded Reflectors for Focus Stability

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Solution Overview

Problem

Conventional augmented reality devices face issues with complex configurations leading to high weight, volume, and manufacturing costs, as well as a need for separate adjustments to maintain focus when changing focal lengths, resulting in reduced optical efficiency and increased manufacturing complexity.

Innovation Solution

An optical device for augmented reality with a straight arrangement structure of reflective units, allowing for improved optical efficiency and simplified manufacturing, featuring reflective units smaller than the human pupil to maintain focus and reduce manufacturing complexity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional optical systems using prisms and multiple optical elements are used, then augmented reality functionality is achieved, but device weight and volume increase making it inconvenient for users to wear

Engineering Contradiction:
Improveaugmented reality functionalityVSAvoiddevice weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent combines multiple optical elements (prism, lens, and reflective unit) into a single integrated optical element. The prism portion and lens portion are formed as one piece, and the reflective unit is embedded within the optical element, eliminating the need for separate components and reducing overall device weight and volume.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The reflective unit is nested inside the optical element, specifically embedded within the lens portion. This nested arrangement allows the reflective unit to be housed within the existing optical element structure without increasing external dimensions, thereby reducing device volume while maintaining functionality.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If conventional optical systems with multiple separate components are used, then augmented reality functionality is achieved, but manufacturing complexity and cost increase

Engineering Contradiction:
Improveaugmented reality functionalityVSAvoidmanufacturing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the prism, lens, and reflective unit into a single integrated optical element. This consolidation reduces the number of manufacturing steps by eliminating the need to separately produce and assemble multiple components, thereby simplifying the manufacturing process and reducing production costs.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The optical element serves multiple functions simultaneously: the prism portion performs total internal reflection to redirect light, the lens portion focuses light onto the retina, and the embedded reflective unit reflects augmented reality image light. This multi-functionality reduces the need for separate specialized components, simplifying manufacturing.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Reliability

If variable focal length mechanisms are added to maintain focus when changing focal lengths, then focus maintenance is improved, but device complexity and operational burden increase requiring separate adjustments

Engineering Contradiction:
Improvefocus maintenanceVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The optical element automatically maintains focus on the retina through its fixed optical design. The optical element's structure inherently ensures that light from different distances is focused onto the retina without requiring user adjustment or additional control mechanisms, making the system self-regulating.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent removes variable focal length adjustment mechanisms and control systems from the device. By using a fixed optical element with carefully designed curvature and reflective properties, the system achieves focus maintenance without the need for extractable or adjustable components, reducing device complexity.

Inventive Principle:
Principle #2Taking out (Extraction)

4Reliability

If conventional optical arrangements are used, then augmented reality image transfer is achieved, but optical efficiency is reduced due to light loss

Engineering Contradiction:
Improveaugmented reality image transferVSAvoidlight loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The optical element is designed with pre-calculated optical paths and reflective angles that ensure maximum light efficiency from the outset. The prism portion and lens portion are configured in advance to minimize light loss, and the reflective unit is positioned and angled optimally to reflect the maximum amount of augmented reality image light toward the user's eye.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The lens portion of the optical element has a curved surface that efficiently focuses light onto the retina. This curvature is optimized to maintain focus across different viewing conditions while minimizing light scattering and loss, thereby improving optical efficiency.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 device enhances optical efficiency by ensuring all augmented reality image light is transferred to the pupil, maintaining focus regardless of focal changes, while simplifying the manufacturing process through a more straightforward assembly method.

Implementation Method 1

a reflective unit configured to transfer augmented reality image light, which is image light output from an image output unit, to a pupil by reflecting the augmented reality image light toward the pupil

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 2

an optical means configured such that the reflective unit is buried and disposed inside the optical means, and also configured to transmit at least part of real object image light, which is image light output from a real object, therethrough toward the pupil of the user's eye

Methodology Applied
Scientific EffectRefraction: Refraction

Data Source

PatentEP4206785B1Optical device for augmented reality, having optical structure arranged in straight line, and method for manufacturing optical means
Publication Date: 2026.01.21 LETINAR CO LTD
  • EP4206785B1 patent drawingFigure 1~2
  • EP4206785B1 patent drawingFigure 3
  • EP4206785B1 patent drawingFigure 4

AI summary

The present invention provides an optical device for augmented reality having an optical structure arranged in a straight line, the optical device including: a reflective means configured to transfer augmented reality image light, output from an image output unit, to the pupil of a user's eye by reflecting the augmented reality image light toward the pupil, thereby providing an image for augmented reality to the user; and an optical means configured such that the reflective means is buried and disposed therein, and also configured to transmit at least part of real object image light, output from a real object, therethrough toward the pupil of the user's eye; wherein the optical unit has a first surface through which the augmented reality image light and the at least part of the real object image light are output and a second surface which the real object image light enters.