Wide Field-of-View Virtual Image Projector Using Segmented Gratings

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Solution Overview

Problem

Conventional virtual image projectors small enough for eyeglasses typically project images with a narrow field-of-view, limiting the range of angles at which virtual images can be seen.

Innovation Solution

A wide field-of-view virtual image projector is implemented using a rod light guide embossed with multiple diffraction gratings that project light rays at various angles, combined with a slab light guide to diffract these rays and generate a virtual image with a broader field-of-view, allowing for a wider range of angles to be projected.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If a single diffraction grating is used in a compact virtual image projector, then the device size is reduced, but the field-of-view becomes narrow

Engineering Contradiction:
Improveprojector sizeVSAvoidfield-of-view
Core Design Contradiction:
Volume of moving objectVSAdaptability or versatility

Solution Approach 1:

The patent divides the diffraction grating into multiple segments (first diffraction grating and second diffraction grating) with different orientations. The first grating diffracts light in a first range of angles while the second grating diffracts light in a second range of angles, collectively providing a wide field-of-view without increasing the overall projector size

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent extends the diffraction capability from a single angular dimension to multiple angular dimensions by introducing gratings with different orientations. This multi-dimensional approach to light diffraction enables a wide field-of-view in both horizontal and vertical directions while maintaining compact form factor

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Adaptability or versatility

If multiple diffraction gratings with different orientations are used, then the field-of-view is widened, but the device complexity increases

Engineering Contradiction:
Improvefield-of-viewVSAvoidgrating structure
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent combines multiple diffraction gratings (first and second gratings with different orientations) into a single integrated light guide structure. This merging approach achieves wide field-of-view coverage while avoiding the complexity of separate projector components, as all gratings are embedded within one light guide

Inventive Principle:
Principle #5Merging (Combining)

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 solution enables the generation of virtual images with a significantly wider field-of-view, enhancing the viewing experience by allowing the viewer to see virtual images over a broader horizontal direction, such as 120 degrees, while still being able to see external objects.

Implementation Method 1

A wide field-of-view virtual image projector includes a rod light guide that is embossed with at least a first diffraction grating and a second diffraction grating that is substantially parallel to the first diffraction grating. The first diffraction grating is configured to receive first light rays, and to project first diffracted light rays from the rod light guide at a first range of angles.

Methodology Applied
Scientific EffectDiffraction: Diffraction

Implementation Method 2

A wide field-of-view virtual image projector includes a rod light guide that is embossed with at least a first diffraction grating

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 3

The virtual image projector further includes a slab light guide configured to receive the first diffracted light rays and the second diffracted light rays, and to diffract the first diffracted light rays and the second diffracted light rays out of the slab light guide to generate a virtual image with a wide field-of view.

Methodology Applied
Scientific EffectDiffraction: Diffraction

Data Source

PatentUS10107994B2Wide field-of-view virtual image projector
Publication Date: 2018.10.23 MICROSOFT TECHNOLOGY LICENSING LLC
  • US10107994B2 patent drawing
  • US10107994B2 patent drawing
  • US10107994B2 patent drawing

AI summary

A wide field-of-view virtual image projector includes a rod light guide that is embossed with at least a first diffraction grating and a second diffraction grating that is substantially parallel to the first diffraction grating. The first diffraction grating is configured to receive a first light ray, and to project first diffracted light rays from the rod light guide at a first range of angles. The second diffraction grating is configured to receive a second light ray, and to project second diffracted light rays from the rod light guide at a second range of angles. The virtual image projector further includes a slab light guide configured to receive the first diffracted light rays and the second diffracted light rays, and to diffract the first diffracted light rays and the second diffracted light rays out of the slab light guide to generate a virtual image with a wide field-of view.