LED Sidewall Light-Altering Materials for Cross-Talk Reduction

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Solution Overview

Problem

Conventional LED packaging limitations, such as increased footprints and spacing issues, hinder the development of high-quality light with desired emission characteristics in closely-spaced LED arrays, particularly in applications like automotive lighting and display systems.

Innovation Solution

The use of light-altering materials, such as light-reflective and light-absorbing materials, are applied directly to the peripheral sidewalls of LED chips without a submount or lead frame, allowing for reduced thickness and conformal coverage, which reduces cross-talk and enables closer spacing of LED devices while maintaining a footprint similar to the chip size.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of stationary object

If conventional LED packaging with submount or lead frame is used, then structural support is provided, but footprint increases and spacing between LEDs is limited

Engineering Contradiction:

ImprovefootprintVSAvoidstructural support

Core Design Contradiction:

Area of stationary objectVSEase of operation

Solution Approach 1:

The patent removes the conventional submount or lead frame from the LED packaging structure. The light-altering material is applied directly to the peripheral sidewalls of the LED chip without requiring a separate supporting substrate, thereby eliminating the additional footprint area while maintaining structural integrity through the conformal coating on the chip sidewalls.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The light-altering material is applied as a thin conformal coating on the peripheral sidewalls of the LED chip. This thin film approach provides the necessary structural definition and light management function without requiring a bulky submount, reducing the overall footprint while maintaining structural support.

Inventive Principle:

Principle #30Flexible shells and thin films

2Object-generated harmful factors

If light-altering material is applied with sufficient thickness to reduce cross-talk, then cross-talk between LEDs is reduced, but footprint increases

Engineering Contradiction:

Improvecross-talkVSAvoidfootprint

Core Design Contradiction:

Object-generated harmful factorsVSArea of stationary object

Solution Approach 1:

The light-altering material is applied selectively only to the peripheral sidewalls of the LED chip rather than uniformly across the entire device. This localized application provides cross-talk reduction at the critical interfaces between adjacent LEDs while minimizing the overall material volume and footprint. The conformal coating ensures adequate thickness at the sidewalls where cross-talk occurs without expanding the device area.

Inventive Principle:

Principle #3Local quality

3Area of stationary object

If LED emitters are arranged in close proximity, then footprint is reduced, but light quality and emission characteristics deteriorate due to cross-talk

Engineering Contradiction:

ImprovefootprintVSAvoidlight quality

Core Design Contradiction:

Area of stationary objectVSIllumination intensity

Solution Approach 1:

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent addresses the harmful effect of cross-talk between closely-spaced LEDs by applying light-altering material that converts the potentially harmful lateral light propagation into beneficial directional emission. The material reflects or absorbs stray light at the sidewalls, converting what would be cross-talk into controlled light paths that maintain emission quality even in closely-spaced arrays.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 configuration enhances light extraction efficiency, reduces cross-talk between closely-spaced LEDs, and allows for the creation of LED devices with tunable emission characteristics, suitable for applications requiring precise light control and reduced footprint.

Implementation Method 1

The light-altering material comprises a light-reflective material

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

the light-altering material comprises a light-absorbing material

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Implementation Method 3

photons reaching the surface (interface) between an LED surface and the surrounding environment are either refracted or internally reflected

Methodology Applied

Scientific EffectLight refraction: Refraction

Data Source

PatentUS11688832B2Light-altering material arrangements for light-emitting devices

Publication Date: 2023.06.27 CREELED INC

AI summary

Solid-state lighting devices and more particularly light-emitting devices including light-emitting diodes (LEDs) with light-altering material arrangements are disclosed. LED devices may include light-altering materials that are provided around peripheral sidewalls of LED chips without the need for a supporting submount or lead frame. The light-altering materials may be provided with reduced thicknesses along peripheral sidewalls of LED chips. An exemplary LED device as disclosed herein may be configured with a footprint that is close to a footprint of the LED chip within the LED device while also providing an amount of light-altering material around peripheral edges of the LED chip to reduce cross-talk. Accordingly, such LED devices may be well suited for use in applications where LED devices form closely-spaced LED arrays. Fabrication techniques are disclosed that include laminating a preformed sheet of light-altering material on one or more surfaces of the LED chip.