APIC Laser Backlight for AR Waveguide Illumination Uniformity

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Solution Overview

Problem

Current augmented reality (AR) and virtual reality (VR) display technologies face challenges in achieving uniform illumination, high pixel density, and efficient power usage due to nonuniformity in AR waveguides and limitations in photonic IC-based delivery systems.

Innovation Solution

An active photonics integrated circuit (APIC) based laser backlight unit is proposed, which includes a dynamic light distribution module, outcoupling modules, beam spot generation modules, and color-conversion modules. This configuration allows for local dimming, energy redistribution, and high out-coupling efficiency per zone, enabling improved light efficiency and color gamut.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If AR waveguide-based light delivery is used, then display functionality is achieved, but illumination uniformity deteriorates

Engineering Contradiction:

Improveillumination uniformityVSAvoidlight delivery performance

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The waveguide is divided into multiple independently controllable zones with individual light delivery channels. Each zone can be adjusted separately to compensate for nonuniformities, allowing different regions to be optimized for their specific illumination requirements while maintaining overall system reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different zones of the waveguide are equipped with localized control mechanisms including zone-specific microlens arrays and outcoupling structures. This enables each region to have tailored optical properties that address local illumination nonuniformities while preserving the overall waveguide functionality.

Inventive Principle:

Principle #3Local quality

2Device complexity

If photonic IC-based delivery system is used, then integration is improved, but pixel density and power efficiency are limited

Engineering Contradiction:

Improvesystem integrationVSAvoidpixel density

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The system transitions from planar photonic IC circuits to three-dimensional waveguide structures with vertical light delivery. This dimensional change enables higher pixel density by utilizing the third dimension for light routing, while the waveguide integration maintains system compactness and reduces power consumption compared to conventional LCD backlights.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Device complexity

If conventional backlight units are used, then simple structure is achieved, but light efficiency and color gamut are insufficient

Engineering Contradiction:

Improvestructure simplicityVSAvoidlight efficiency

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The conventional mechanical LCD backlight system is replaced with a waveguide-based optical system that uses total internal reflection and controlled outcoupling. This substitution eliminates the need for bulky diffusers and reflectors, improving light efficiency while the integrated microlens arrays provide precise optical control for enhanced color gamut.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Productivity

If high pixel density is achieved, then display resolution is improved, but illumination uniformity deteriorates

Engineering Contradiction:

Improvepixel densityVSAvoidillumination uniformity

Core Design Contradiction:

ProductivityVSIllumination intensity

Solution Approach 1:

The waveguide system incorporates dynamically adjustable outcoupling mechanisms including electro-optic or thermo-optic control elements that can reallocate light distribution in real-time. This dynamic adaptation allows the system to maintain illumination uniformity even when pixel density varies across different display regions.

Inventive Principle:

Principle #15Dynamics

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 APIC-based laser backlight unit achieves efficient and uniform illumination with local dimming capabilities, enhancing display performance and reducing power consumption while supporting high pixel density and large color gamut.

Implementation Method 1

a waveguide to convey the blue light to a display portion of the liquid crystal display

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

A color conversion module proximate the display portion converts parts of the blue light into red light and green light

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentUS12216357B2Display backplanes with integrated electronics, photonics and color conversion components

Publication Date: 2025.02.04 META PLATFORMS TECHNOLOGIES LLC

AI summary

In some examples, an apparatus may include a backlight unit (BLU) including an electronic integrated circuit layer, a photonic integrated circuit layer, a color conversion module, and a display interface layer. In some examples, a BLU may include at least one laser or may be configured to receive laser light from at least one external laser source. Laser light may be transmitted towards a portion of the display interface layer using the photonic integrated circuit. Color conversion modules may be used to convert the laser light into one or more desired colors. Example apparatus may be used in head-mounted devices such as augmented reality and/or virtual reality devices. Other devices, methods, systems, and computer-readable media are also disclosed.