Curved Lightguide Eyewear for Concealed, Wide-Field AR Displays

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Solution Overview

Problem

Conventional electronically-enhanced eyewear devices suffer from limitations such as low field of view, light leakage, and bulkiness due to the positioning of components, which restricts their practical applications and user experience.

Innovation Solution

The eyewear device is designed with a display oriented towards the eye-side, incorporating a curved lightguide and reflector to enhance the field of view, while maintaining a thin and lightweight form factor by using a curved lens surface and a head mountable frame that supports the display, lightguide, and reflector, with components sealed to prevent light leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the display is positioned at the temple location with a tilted lightguide to facilitate total internal reflection, then the optics can be concealed within the temple region, but the field of view is restricted to approximately ten degrees diagonal or less

Engineering Contradiction:

Improveconcealment of opticsVSAvoidfield of view

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The lightguide is repositioned from the temple region to the front of the eyewear frame, and the display is rotated 90 degrees to face upward toward the lightguide. This dimensional reconfiguration allows the light path to be folded within the frame structure, achieving both concealment and a significantly enlarged field of view exceeding ten degrees diagonal.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Ease of manufacture

If conventional components are used to implement see-through eyewear, then the device can display computer-generated images, but the CGI width and height are limited to only a few degrees, resulting in poor user experience

Engineering Contradiction:

Improveuse of conventional componentsVSAvoidfield of view

Core Design Contradiction:

Ease of manufactureVSAdaptability or versatility

Solution Approach 1:

A curved lightguide with a convex outer surface and concave inner surface is employed instead of conventional flat lightguides. The curvature enables a wider angular acceptance of light from the display and provides a larger effective viewing area, expanding the field of view while maintaining compatibility with standard optical components.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Reliability

If a lightguide is tilted at a relatively high angle to facilitate total internal reflection, then the display light can be effectively guided, but the device becomes bulkier and the field of view is reduced

Engineering Contradiction:

Improvetotal internal reflection efficiencyVSAvoiddevice size

Core Design Contradiction:

ReliabilityVSVolume of moving object

Solution Approach 1:

Instead of tilting the lightguide at a high angle relative to the display, the display is inverted to face upward and positioned perpendicular to the lightguide surface. This inversion allows the light path to be folded within a compact volume while maintaining effective total internal reflection at the lightguide interfaces.

Inventive Principle:

Principle #13The other way round (Inversion)

4Ease of operation

If the display emits light toward the world-side of the device, then the display is visible from the outside, but light leakage occurs that inadvertently announces the use of an electronic device

Engineering Contradiction:

Improvedisplay visibilityVSAvoidlight leakage

Core Design Contradiction:

Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The display is extracted from its conventional orientation and repositioned to face upward toward the lightguide, with its light output directed into the lightguide structure. This extraction of the display from the front-facing position eliminates direct light leakage to the world-side while maintaining display functionality through the optical system.

Inventive Principle:

Principle #2Taking out (Extraction)

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 provides a compact, lightweight, and aesthetically pleasing augmented reality eyewear with an improved field of view and vision correction, making it suitable for various environments without revealing the electronic nature of the device.

Implementation Method 1

the lightguide is often required to be tilted at a relatively high angle (e.g. 18 degrees or more) so as to facilitate total internal reflection (TIR) of the display light within the lightguide

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

use of curved lens surfaces in the lightguide creates a thin, lightweight eyewear device

Methodology Applied

Scientific EffectRefraction: Refraction

Data Source

PatentUS12352972B2Compact rim-mounted curved optical see-through lightguide based eyewear as mobile augmented reality display

Publication Date: 2025.07.08 GOOGLE LLC

AI summary

An optical device includes a lightguide and a display at a top of a head mountable frame. The display is oriented toward an eye-side of the optical device. A reflector is positioned at an eye-side of the optical device and directs light into the lightguide. This orientation and arrangement of components reduces light leaking out of the optical device. The lightguide includes curved first and second surfaces. The device reflects light through the curved first surface to a user eye for augmented reality vision. A head mountable frame supports the display, the reflector, and the lightguide.