EDGE LIGHTING TECHNOLOGYEfficiency, Control & Uniformity

Paul Crisp(Managing Director – Fern-Howard Ltd)

Agenda

• Why Use Edge Lighting Technology?• Principles of Edge Lighting Technology• Different Approaches to Edge Lighting• Optical Control & Application Efficiency• Optical Efficiency• Uniformity• Fern-Howard & Rambus Reference Lightguides• In Conclusion

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Why Use Edge Lighting Technology?

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LED Edge Lighting has rapidly emerged as the solution of choice for backlighting in the displays and TV market

Do the benefits transfer to the Lighting Market?

Why Use Edge Lighting Technology?

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Luminaire designers have always had to manage issues of:• Efficiency• Light Distribution• Uniformity• Appearance

Why Use Edge Lighting Technology?

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LED is no different …

• Directional Output

• High Glare

• Visual Appearance

• Efficiency

Why Use Edge Lighting Technology?

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To resolve issues of Glare and Uniformity diffusing materials are often used, but …..

The compromise is

Efficiency Often with as much as 40% reduction in output

Why Use Edge Lighting Technology?

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Edge Lighting offers an opportunity to produce new and exciting luminaires:

But ……..Not all Edge-lit technology is the same

• Great uniformity• Thin• No hotspots• Optical Control• Retains LED Efficiency

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Principles Of Edge Lighting TechnologyEdge Lighting uses the principle of Total Internal Reflection (TIR)

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Principles Of Edge Lighting Technology

Light travels and bounces along the lightguide until it hits a disruption feature

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LED Backlit Module Compared to Edge Lit Module

LED’s Lightguide

Optical & Diffusing Films (optional)

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Different Approaches to Edge Lighting Technology

There are a range of different ways to create the optical disruption features

• Printed Dot• Chemical Etch• Laser Etch• Vee Grooves• Embedded Optics

Patterning Technology

Printed Dot Chemical Etch Laser Etch V-grooves Embedded Optics

Method

Optics • Diffuse • Diffuse • Diffuse • Diffuse (1D only) • Specular (ray • angle control)

Optical Efficiency • Good • Good • Better • Good • Best

Uniformity • Good • Good • Better • Good • Best

Manufacture-ability • Fast • Fast • Slow • Slow • Fast

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Comparison of Edge Lighting Approaches

Optical features can be varied by depth, shape, density and location and enable output

distributions to be optimised to support any application

area

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At Fern-Howard we work with Rambus Inc and use their Embedded MicroLens® Optics

Optical Control

Most Edge lighting systems have limited optical control and produce a diffuse output

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Optimized LED-to-light guide interface

Highest Application

Efficiency

High Optical Efficiency

+ Precise Ray Angle Control

=

Maximum light extracted

from light guide

Custom controlled light

output

Optical Control And High Application Efficiency

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Optical Efficiency – Why is it Important?

Optical Efficiency 90% 85% 80% 75% 70%

LED Efficacy 120 L/W 120 L/W 120 L/W 120 L/W 120 L/W

Drive Current 83mA 83mA 83mA 83mA 83mA

System Efficacy 108 L/W 102 L/W 96 L/W 90 L/W 84 L/W

Data based on Samsung LM231A excluding thermal losses

It is clear that higher optical efficiency can be used to create higher system efficacy

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Optical Efficiency – Why is it Important?

Optical Efficiency 90% 85% 80% 75% 70%

Min LED Efficacy 100 L/W 106 L/W 113 L/W 120 L/W 129 L/W

Drive Current 150mA 140mA 112mA 83mA 57mA

LED output 50 L 47 L 39 L 30 L 21 L

Qty of LED’s Required 60 64 77 100 143

% increase in LED’s / cost - + 7% + 28% + 67% + 138%

Table shows LED’s required to achieve 3000 lumens @ 90 L/WData based on Samsung LM231A excluding thermal losses

However, high optical efficiency can also be used to reduce LED count and luminaire cost

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Patterning Technology Performance Comparison:Printed Dot vs. Laser Etched vs. MicroLens

Test SetupFixture Configuration

18” Hanging Pendant, LEDs on 1 edge

LEDs Nichia NS2X123, qty 28Light Guide Thickness

4mm

Pattern Size 92.6mm x 406.4mmBack Reflector NoneDiffuser NoneEdge Reflector NoneCCT 3500KCRI 85

Optical Efficiency

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Light-guide with embedded MicroLens optics measured 10% higher efficiency than other light-guides

Extraction Technology

Light Guide Thickness

TotalFlux

% Output*

MicroLens 4mm 609.3 100%

Laser 4mm 551.1 90.4%

Printed 4mm 541.1 88.8%

* Flux from fixture with MicroLens light guide used as the baseline

Optical Efficiency

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Optical Uniformity

High Uniformity is achieved by statistical mapping of lens density across the surface of the lightguide

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Fern-Howard and Rambus

Fern-Howard have been working with Rambus to develop edge-lit lighting products based on their extensive portfolio of Edge lighting patents and technology

All our products use the Rambus Embedded MicroLens® Optics and Lens Replication technology, and are injection moulded in our facility in the UK

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Fern-Howard, Rambus Reference LightguidesA recent collaboration with Rambus has seen us launch a range of Reference Lightguide designs

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Fern-Howard, Rambus Reference Lightguides

• Based on Rambus patented embedded optics technology

• No upfront development or tooling costs

• Common forms with optimised distributions

• Compatible with wide range of LED manufacturers

• Design flexibility to create the LED / optical configuration you require

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• Edge lighting Technology offers Luminaire Designers the opportunity to achieve uniformity and application efficiency whilst retaining much of the inherant efficiency that LED offers

• Not all Edge Lighting is the same with embedded optics offering the most effective performance from the range of optical disruption techniques commonly used

• Our Reference Design range of Edgelit lightguides enables access to Rambus patented embedded optics technology without upfront development and tooling costs

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Thank you for the opportunity to present to you todayAre there any questions?