Active Reflective Surfaces for Wearable Displays

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Solution Overview

Problem

Conventional reflective displays and LCOS projection technologies suffer from significant light loss due to color filters and polarizers, resulting in only 8-17% of light being usable for display, which is inadequate for wearable devices requiring efficient light output.

Innovation Solution

Implementing an active color conversion material, such as quantum dots or phosphorus, directly on a reflective layer within the imaging structure to convert input light into emitted light, replacing conventional passive absorbing color filters and enhancing light output efficiency by a factor of two to four.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional color filters are used to convert white light to RGB sub-pixels, then color display is achieved, but light loss increases to 50-70%

Engineering Contradiction:

Improvelight output efficiencyVSAvoidlight loss

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent changes the fundamental mechanism of color conversion from passive absorption (color filters) to active conversion (quantum dots/phosphors). This parameter change in the conversion mechanism transforms how light interacts with the color conversion layer, enabling higher efficiency by converting rather than absorbing light wavelengths.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite material structures combining quantum dot layers with reflective layers and encapsulation layers. This composite approach integrates multiple functional materials to achieve both color conversion and light management, resulting in improved light output efficiency while maintaining color accuracy.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If polarizers are added to liquid crystal display devices, then display contrast is improved, but light loss increases further reducing overall efficiency to 8-17%

Engineering Contradiction:

Improveusable light percentageVSAvoidlight loss through polarizers

Core Design Contradiction:

Illumination intensityVSLoss of energy

Solution Approach 1:

The patent changes the light conversion mechanism from passive filtering to active wavelength conversion, fundamentally altering how light passes through the display stack. This enables maintaining display performance while reducing the number of light-blocking components needed.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies quantum dot layers with specific size distributions to different regions to convert specific wavelengths, allowing localized optimization of light conversion efficiency while maintaining overall display performance requirements.

Inventive Principle:

Principle #3Local quality

3Productivity

If conventional absorbing color filters are used, then color separation is achieved, but light output efficiency remains low

Engineering Contradiction:

Improvelight output efficiencyVSAvoidlight absorption by filters

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent fundamentally changes the light-matter interaction mechanism from absorption to conversion. Quantum dots and phosphors convert absorbed light to emitted light at different wavelengths, preserving more of the original light energy compared to conventional filters that simply absorb unwanted wavelengths.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical/optical filtering system with a quantum optical conversion system. Instead of using physical filters to block certain wavelengths, the system uses quantum mechanical properties of quantum dots to convert wavelengths efficiently.

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

This solution significantly improves light output efficiency and color gamut, allowing for more effective use of light in wearable display devices by converting input light into RGB light, thereby addressing the limitations of conventional technologies.

Implementation Method 1

An active color conversion material that is formed on the reflective layer converts the input light to the emitted light. The active color conversion material can be implemented as a phosphorus material or quantum dot material that converts the input light to the emitted light.

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

A reflective layer of the imaging structure reflects input light from an illumination source

Methodology Applied

Scientific EffectReflection: Reflection

Data Source

PatentUS9151984B2Active reflective surfaces

Publication Date: 2015.10.06 MICROSOFT TECHNOLOGY LICENSING LLC

AI summary

In embodiments of active reflective surfaces, an imaging structure includes a circuit control layer that controls pixel activation to emit light. A reflective layer of the imaging structure reflects input light from an illumination source. An active color conversion material that is formed on the reflective layer converts the input light to the emitted light. The active color conversion material can be implemented as a phosphorus material or quantum dot material that converts the input light to the emitted light, and in embodiments, the active color conversion material is laminated directly on the reflective layer.