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Some Fact about LEDs and UV-radiation. Labino AB Adisa Paulsson M.Sc., Product Development Engineer August 2010. Labino. We develop and manufacture the UV and white light lamps for industry and public sector. The lamps are based on MPXL and LED technology. Founded 1994, Sweden.

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Some fact about leds and uv radiation

Some Fact about LEDs and UV-radiation

Labino AB

Adisa Paulsson M.Sc., Product Development Engineer

August 2010


  • We develop and manufacture the UV and white light lamps for industry and public sector.

  • The lamps are based on MPXL and LED technology.

  • Founded 1994, Sweden

Topics today
Topics today

  • Historical development of the power LEDs

  • How LEDs operate

  • Factors influencing the Lifetime and Reliability

  • How to produce the white light

  • UV LED technology

What are the leds
What are the LEDs?


-Electroluminescence was discovered in 1907

-first LED was reported in 1927, by Oleg Losev

-LEDs are semiconductor which emits the photons when current is passing trough the material

-Color = energy gap of the semiconductor

InGaN- near UV,blue,green

AlGaN- red, infrared, amber

Leds become more and more bright
LEDs become more and more bright!

First power LED was introduced by Philips Lumileds 1999.

XLamp XM LED delivers efficacy of 160 lm/W (at 350 mA)

At 2A, XM LED produce 750 lm at 7W = 60W incandescent light bulb

Luminous flux increased by factor of 2

every 18-24 months!

5 mm LEDs,1-2 lm

Luxeon I- 5 lm 2002

Luxeon III- 50 lm 2006

Luxeon Rebel-120 lm, 2010

Efficiency is increasing
Efficiency is increasing

• Approaching 2010: Luminous efficiency 160 lm/ W phosphor white power LEDs

•Expect ~ 200 lm/W power LED performance within the next 3-5 years

More facts about leds
More facts about LEDs

The LEDs are not so cold ! !

Increasing the power requires more heat to evacuate !!

Temperature effect on the leds
Temperature effect on the LEDs!


Useful Life

Temperature effect on the leds1
Temperature effect on the LEDs!

Wavelength shift as a function of the temperature

Lifetime of leds
Lifetime of LEDs

How to define the useful lifetime of the LEDs?

Lumen maintenance or Lumen depreciation!

LM-80 test criteria developed by U.S. Department of Energy and LRC

L70 -at least 70 % of the initial lumen output

B50-50% of population fails

B50/L80 or B10/L70

B10/L70 at 60 000 hours

Lifetime of leds1
Lifetime of LEDs

2. Temperature internal and ambient

1. Drive current

Source: LED Magazine, 51 news letter, November 2007

LED Luminaire Lifetime

● Complexity of LED luminaire.

● Luminaire reliability is the product of all

the critical components:

-in well designed luminaire - the failure should be caused by lumen depreciation

Quality is a major issue
Quality is a major issue!

Performance of the white LEDs

  • The quality of commercial white LEDs used in

  • lightning products varies widely (26 batches)

  • -A quality assurance is needed to protect

  • consumers and prevent “market spoiling”

Source: Mills E. and A. Jacobson, 2007, Light and Engineering

Producing the white light 1
Producing the White Light (1)

-Color mixing of usually three colors

-High efficacy

-trade off between luminous efficiency and

color rendering capability

-requires electro-optical devices to control mixing of

different colors

-Individual colored LEDs respond differently to drive current,

temperature- impact on white light quality

1. Color-mixing LEDs (RGB method)

Producing the white light 2
Producing the White Light (2)

1. Phosphor conversion approach (blue or UV-light +phosphor)

Broadening of the spectra with phosphor layers

GaN or InGaN LED

-the most common method blue LED + Phosphor

-UV phosphor coated LEDs –less efficient,

better color rendering

- low conversion efficiency

-A lot of research to improve phosphor coating quality and efficacy

-More simple and not so costly production compared to RGB system

What are the limits of the high power white light chip
What are the Limits of the high power White Light chip?

U.S. DOE Forecasted LED Efficacy Improvements, 2009

-Difference between cool

and warm white origin from

phosphor efficacy.

How green are leds
How green are LEDs?

Life cycle assessment of Ultra Efficient lamps

Source: DEFRA-Department for Environment(UK), 2009

Uv led technology
UV-LED Technology

What is the main difference between UV LED and traditional UV light source?


Xe spectra

UV LED spectra

Uv led technology1
UV LED Technology

The peak wavelength

is at 365 nm

UV LED also emits a small amount of the visible light mostly blue-violet in spectral range 380nm to 475nm.

blue LED, InGaN

Uv led and white light
UV-LED and White Light

The visible light (380nm-780) in UV sources-bad for many applications!

White Light Block Filter!

How to solve this technology insufficiency?

Life time presumption of uv led
Life time presumption of UV-LED

- 6000 hours life test data

-The data exceeds the absolute

maximum rating.

Measurement of the visible light in uv light sources
Measurement of the visible light in UV- light sources

1.Spectral sensitivity curve of the detector

2. Fluorescence of the detector

High transmittance in visible area!

Uv led versus mpxl
UV LED versus MPXL



+light weighted and small

+good efficiency


+long life

+Intensity: 0.3 W of UVA radiation

-High cost of lm/W compared to MPXL

+Cold (no IR)

-sensitive to high ambient temperature

-Lack of standard optical solutions

-Problem with white light leakage-requires filter

-require active or passive cooling solution

  • -Big and clumsy

  • +high efficiency

  • +keeps running after drop

  • +lifetime up to 4000 hours

  • + high intensity: 5 W of UVA radiation

  • +relatively low cost

  • the bulb gets very hot

  • + Relative insensitive to ambient temperature

Technologies are complementing

each other!


  • The LEDs have a great potential: light waited, high efficiency and low cost products(white).

  • Challenges:

    • Increase power per chip

    • Improve the efficacy of the LEDs specially UV and green

    • Increase the product quality and reliability

    • Increase the luminere system efficiency (electronic, optics, heat management)

    • Enhance production process/ Reduce binning

    • Reduce environmental impact

    • A new material for UV needed

At Last LEDs….

  • Who truly wants to unleash the potential of LED technology should not only seize the opportunities, but also bear some of the responsibilities.

    False or incomplete information → wrong expectations

    Wrong expectations→ Unhappy users

100 lm/W LEDs do not make a 100 lm/W light source

50 000 hours lifetime do not make a LED light source with 50 000 lifetime.

Thank you!

Labino AB

Stockholm | Sweden