Rotating HMD with Scanning LED Array for Compact AR

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Conventional head-mounted displays (HMDs) for augmented reality are bulky, expensive to manufacture, and have limited field of view due to complex optical arrangements and the use of rectangular displays, which result in obscured vision and reduced image clarity.

Innovation Solution

A mechanical-based HMD system featuring a substrate with light emitting elements oriented towards the world side, a non-planar reflective surface, and a motor for rotating the substrate and reflective surface, along with a display driver to selectively activate the light emitting elements, creating a polar-coordinate-based image with improved transparency and reduced complexity in optical design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If conventional rectangular displays with multiple LEDs are used, then image coverage is achieved, but device complexity and manufacturing cost increase

Engineering Contradiction:
Improveimage coverage areaVSAvoiddisplay complexity
Core Design Contradiction:
Area of stationary objectVSDevice complexity

Solution Approach 1:

The display is segmented into a single column of light emitting elements that are scanned sequentially across the field of view, replacing the conventional rectangular grid of multiple LEDs. This segmentation reduces the number of simultaneous light sources needed while maintaining complete image coverage through time-multiplexed scanning.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The display transitions from a static rectangular array to a dynamic scanning system where a single column of LEDs is rotated through different angular positions to sequentially illuminate different parts of the field of view. This dynamic approach reduces device complexity while maintaining full image coverage area.

Inventive Principle:
Principle #15Dynamics

2Illumination intensity

If conventional opaque displays are used, then image projection is achieved, but field of view is limited and external vision is obscured

Engineering Contradiction:
Improveimage brightnessVSAvoidfield of view
Core Design Contradiction:
Illumination intensityVSArea of stationary object

Solution Approach 1:

The display system employs a spherical or curved reflective surface instead of a planar opaque display. This curvature allows the light from the scanning LED column to be reflected across a wider field of view while maintaining image brightness, and the spherical geometry enables simultaneous visibility of both the displayed image and the external world through transparent portions.

Inventive Principle:
Principle #14Spheroidality (Curvature)

Solution Approach 2:

The display transitions from a two-dimensional opaque surface to a three-dimensional spherical scanning system. By adding the temporal dimension of scanning and the spatial dimension of spherical geometry, the system achieves wider field of view and maintains image brightness without requiring an opaque surface that would block external vision.

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

3Manufacturing precision

If complex optical arrangements are used, then image clarity is improved, but device complexity and bulk increase

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

Solution Approach 1:

The system extracts and eliminates complex optical arrangements (multiple lenses, mirrors, and optical components) by using a simpler mechanical scanning approach with a single column of LEDs and a spherical reflective surface. Image clarity is maintained through the scanning mechanism and optical geometry rather than through complex optical path management.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces complex optical systems with a mechanical scanning system where a single column of LEDs is physically rotated through different angular positions. This mechanical approach achieves image projection and clarity without requiring complex optical arrangements, reducing overall device complexity and bulk.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 more compact, cost-effective HMD with enhanced image clarity and a wider field of view, allowing both digital and real-world imagery to be visible simultaneously, while minimizing optical distortions and manufacturing costs.

Implementation Method 1

a substrate supporting a set of light emitting elements, wherein each light emitting element is oriented toward a world side of the HMD system

Methodology Applied
Scientific EffectLight emission: Light Emitting Diode

Implementation Method 2

a non-planar reflective surface oriented toward a user eye and positioned on the world side of the set of light emitting elements

Methodology Applied
Scientific EffectReflection: Reflection

Implementation Method 3

a motor coupled to the substrate and the reflective surface for motion of the substrate and reflective surface, wherein the motor is configured for rotating the substrate and the reflective surface

Methodology Applied
Scientific EffectMechanical rotation:

Data Source

PatentEP3698203B1Head mounted display with mechanical scanning
Publication Date: 2024.05.22 GOOGLE LLC
  • EP3698203B1 patent drawingFigure 1~2
  • EP3698203B1 patent drawingFigure 3~10
  • EP3698203B1 patent drawingFigure 4~5

AI summary

A head mounted display (HMD) system (300, 1000) includes a display for emitting light (106) toward an eye-ward side of the system and which allows both ambient light (105) and emitted light to reach an eye (107) of a user. The system provides augmented reality (AR) based viewing and includes a rotatable substrate (315) supporting a set of light emitting elements (301). Each light emitting element is oriented toward a world side of the HMD system. A rotatable reflective surface (316) is positioned on the world side of the set of the light emitting elements. The reflective surface reflects emitted light toward a user eye. A motor, coupled to the rotatable substrate and the rotatable reflective surface, rotates these elements about a common axis and a display driver (317) selectively activates the light emitting elements during this rotation in accordance with an illumination sequence so as to provide an image (310).