Photoluminescent Display Layer Surface Structure for Directional Light Control

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Solution Overview

Problem

Photoluminescent materials emit light in all directions, requiring optical elements like reflectors and lenses to direct light, which increases device size and complexity.

Innovation Solution

A light-emitting device with a photoluminescent layer and a light-transmissive layer, featuring a submicron structure with projections or recesses that enhance directional light emission by coupling light into a quasi-guided mode, allowing for localized directional light output without the need for additional optical elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If photoluminescent materials are used to emit light, then light emission is achieved, but light is emitted in all directions requiring additional optical elements

Engineering Contradiction:

Improvelight emissionVSAvoidoptical elements

Core Design Contradiction:

Illumination intensityVSDevice complexity

Solution Approach 1:

The patent combines the photoluminescent layer with a waveguide layer and surface structure into an integrated light-emitting device. The surface structure is formed directly on the waveguide layer, merging multiple functional components into a single unified structure that achieves both light emission and directional control without separate optical elements

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent introduces a surface structure with projections or recesses on the waveguide layer surface, adding a third-dimensional geometric feature to a previously planar structure. This surface relief structure modifies light emission directionality by interacting with light at the surface interface, enabling directional control without additional optical components

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Speed

If reflectors and lenses are added to direct light, then directional light output is achieved, but device size increases

Engineering Contradiction:

Improvelight directionalityVSAvoiddevice size

Core Design Contradiction:

SpeedVSVolume of moving object

Solution Approach 1:

The patent merges the light-emitting function and light-direction function into a single integrated layer structure. The waveguide layer with surface structure simultaneously serves as both the light source (via photoluminescent conversion) and the light-directing element, eliminating the need for separate reflectors and lenses that would increase device volume

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses a thin film waveguide layer with surface relief structure to control light direction. This thin-film approach replaces bulky traditional optical elements with a compact, planar structure that achieves the same light-direction function while minimizing device volume

Inventive Principle:

Principle #30Flexible shells and thin films

3Speed

If optical elements are used to direct light, then light directionality is improved, but manufacturing complexity increases

Engineering Contradiction:

Improvelight directionalityVSAvoidmanufacturing process

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent combines multiple manufacturing steps into a single integrated process. The surface structure is formed directly on the waveguide layer using standard semiconductor fabrication techniques, eliminating the need for separate assembly of optical elements and simplifying the overall manufacturing process

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent replaces mechanical optical elements (reflectors, lenses) with a surface relief structure that controls light through geometric optics and waveguide modes. This substitution enables manufacturing using standard thin-film deposition and lithography techniques rather than precision mechanical fabrication and assembly

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 enables directional light emission with improved luminous efficiency and polarization selectivity, reducing device size and complexity by eliminating the need for external optical elements.

Implementation Method 1

a light-emitting device including a photoluminescent layer that receives the excitation light and emits light

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

A surface structure is defined on at least one of the photoluminescent layer and the light-transmissive layer. The surface structure has projections or recesses or both and limits a directional angle of the first light

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS10031276B2Display apparatus including photoluminescent layer

Publication Date: 2018.07.24 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD

AI summary

A display apparatus includes an excitation light source that outputs excitation light; a light-emitting device including a photoluminescent layer that receives the excitation light and emits light including first light having a wavelength λa in air, and a light-transmissive layer located on or near the photoluminescent layer; and an optical shutter on an optical path of the light emitted from the photoluminescent layer. A surface structure is defined on at least one of the photoluminescent layer and the light-transmissive layer, and the surface structure has projections or recesses or both and limits a directional angle of the first light having the wavelength λa in air.