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
Adisa Paulsson M.Sc., Product Development Engineer
-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
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
• Approaching 2010: Luminous efficiency 160 lm/ W phosphor white power LEDs
•Expect ~ 200 lm/W power LED performance within the next 3-5 years
The LEDs are not so cold ! !
Increasing the power requires more heat to evacuate !!
Wavelength shift as a function of the temperature
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
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
Performance of the white LEDs
Source: Mills E. and A. Jacobson, 2007, Light and Engineering
-Color mixing of usually three colors
-trade off between luminous efficiency and
color rendering capability
-requires electro-optical devices to control mixing of
-Individual colored LEDs respond differently to drive current,
temperature- impact on white light quality
1. Color-mixing LEDs (RGB method)
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
U.S. DOE Forecasted LED Efficacy Improvements, 2009
-Difference between cool
and warm white origin from
Life cycle assessment of Ultra Efficient lamps
Source: DEFRA-Department for Environment(UK), 2009
What is the main difference between UV LED and traditional UV light source?
UV LED spectra
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
The visible light (380nm-780) in UV sources-bad for many applications!
White Light Block Filter!
How to solve this technology insufficiency?
- 6000 hours life test data
-The data exceeds the absolute
1.Spectral sensitivity curve of the detector
2. Fluorescence of the detector
High transmittance in visible area!
+light weighted and small
+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
Technologies are complementing
At Last LEDs….
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.
Stockholm | Sweden