LED Safety Barrier with Segmented Openings for Thermal Expansion

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Solution Overview

Problem

LED lighting fixtures face challenges with heat-related thermal expansion, environmental protection, and stringent safety standards, particularly the 'finger test' during fire conditions, which increase costs and reduce optical efficiency.

Innovation Solution

The design includes a mounting board with LED packages, a safety barrier with a metal layer and insulating layer laminate, and a resilient gasket member to accommodate thermal expansion and prevent finger contact with electrical elements, ensuring compliance with safety standards while maintaining cost-effectiveness.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a safety barrier is added to prevent finger contact with electrical elements, then electrical safety is improved, but optical efficiency deteriorates

Engineering Contradiction:
Improveelectrical safetyVSAvoidoptical efficiency
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The safety barrier is segmented with openings positioned at lens locations, allowing light to pass through while maintaining safety coverage over electrical elements. This segmentation enables the barrier to simultaneously provide safety protection and optical transmission without requiring a complete solid barrier.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The safety barrier has different properties in different locations: solid coverage over electrical elements for safety, and openings at lens positions for light transmission. This local differentiation allows the single component to serve dual functions of safety protection and optical efficiency.

Inventive Principle:
Principle #3Local quality

2Reliability

If enclosure barriers are added to meet fire safety standards, then product safety is improved, but device complexity increases

Engineering Contradiction:
Improvefire safetyVSAvoidenclosure structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety barrier combines multiple functions into a single component: it provides fire safety barrier protection, maintains structural integrity, and incorporates openings for light transmission. This merging eliminates the need for separate safety enclosures and optical components.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The safety barrier serves multiple purposes simultaneously: it acts as a fire safety barrier, a structural support element, and a light transmission pathway. This multi-functionality reduces the number of separate components needed and simplifies the overall device structure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Illumination intensity

If lens-over-lens mounting is used to achieve optical design goals, then lighting performance is improved, but thermal stability deteriorates

Engineering Contradiction:
Improvelighting performanceVSAvoidthermal alignment stability
Core Design Contradiction:
Illumination intensityVSStability of the object's composition

Solution Approach 1:

The safety barrier acts as an intermediary thermal management component between the stacked lenses and the external environment. It provides a stable reference structure that accommodates thermal expansion of the lens assembly while maintaining alignment, preventing direct thermal contact that would cause misalignment.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The safety barrier is designed with material properties and dimensional parameters that compensate for thermal expansion of the lens assembly. By changing the barrier's thermal characteristics or dimensions, the system maintains alignment stability across temperature variations despite the lens-over-lens configuration.

Inventive Principle:
Principle #35Parameter changes

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 enhanced electrical safety and cost-effectiveness by preventing finger contact with electrical elements during thermal expansion and fire conditions, while maintaining optical efficiency and compliance with stringent safety standards.

Implementation Method 1

temperature changes may cause thermal expansion and related alignment problems

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

a resilient gasket member to accommodate thermal expansion

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2149008B1Safety accommodation arrangement in LED package/lens structure
Publication Date: 2013.03.06 WOLFSPEED INC
  • EP2149008B1 patent drawingFigure 1
  • EP2149008B1 patent drawingFigure 2~3
  • EP2149008B1 patent drawingFigure 4A~4B

AI summary

An LED apparatus (10) including (a) a mounting board (12), (b) a plurality of LED packages (14) thereon, (c) a lens member (50) over each LED package, and (d) a safety barrier positioned over the mounting board, the barrier having sufficient thickness for enclosure of electrical elements on the mounting board and including a plurality of openings each sized to permit light from an LED package to pass therethrough and through a light-transmission portion (36) of the lens member over such LED package to prevent finger-contact of electrical elements on the mounting board when the light-transmission portion is not present.