Transcript Parabolic/Elliptical Reflector based light engine

Design of new collection systems for
multi LED light engines
Photonics
Europe
Hüseyin Murat
05/04/2006
© imec 2006
LED’s in projectors
Advantages LED’s in comparison with UHP
Directly R,G,B
 No dichroic mirrors
 No UV and IR filters
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 price, volume and losses
Robust and very long life time
Low operating voltage
 Small size
 Absence of mercury and
explosion danger
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 compact, portable, inexpensive
projection systems
LED narrow spectrum, large color gamut
 increased quality
Large dimming ratio (increased contrast)
 Rapidly switchable pulsing (1-panel, 3-panel)
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LED’s in projectors
Bottleneck
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Small optical output (luminance)
Étendue limitation of projector (f#, LV)
 low projected flux
LED interesting for low power applications
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Using high luminance LED’s
Optimally collecting available flux
Combining multiple LED’s
Design of new collection systems
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© imec 2006
‘Gradually Tapered Light Pipes’ based
‘Elliptical and Parabolic Reflector’ based
LED’s in projectors
System description
green LED +
lens/reflector
0.9” LV with 4:3 aspect ratio
 f# 2.88
 10% overfill
Esys= 26.19 mm2sr
 LED: surface emitter, lambertian
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blue LED +
lens/reflector
µD
integrator
blue
µD
proj.
lens
LED’s
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integrator
red
X-cube
µD
Luxeon III and Luxeon V (LumiLEDs); OSTAR (OSRAM)
optical
power [lm]
étendue
[mm2sr]
luminance
[lm/mm2sr]
electrical
power [W]
radiation
pattern
Luxeon III
80
7.07
11.32
3.9
lambertian
Luxeon V
160
28.27
5.66
4.8
lambertian
OSTAR
160
13.85
11.55
6.6
lambertian
 Luxeon III and OSTAR
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integrator
green
red LED +
lens/reflector
Types of collectors
Gradually Tapered Light Pipes
θ
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Principle
light α
ray
Collection within the f#
Homogenization to uniform illumination
Reshaping to 4:3 aspect ratio
Propagation by TIR
Reflector with light pipe
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Collection within f#  reflector
Homogenization and reshaping: light pipe
Propagation by mirroring sides
(α-2*θ)
TLP
GTLP based light engine
Single GTLP collector
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© imec 2006
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4 massive blocks, decreasing θtap
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Simulated for Luxeon III and OSTAR (green)
output
luminance
[lm/mm2sr]
collection
efficiency
[%]
étendue
[mm2sr]
output
dimensions
[mm2]
length
[mm]
electrical
power [W]
electrical
efficiency
[lm/W]
Luxeon III
7.70
69.6
6.55
7.2*9.6
50
3.9
12.92
OSTAR
8.54
74
13.1
14.4*9.6
100
6.6
16.95
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Luxeon III: opt. coupled, 4:3 ratio, 9.6mm*7.2mm, 25% Esys
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OSTAR: opt. not coupled, 2:3 ratio, 9.6mm*14.4mm, 50% Esys
GTLP based light engine
GTLP based multi LED engine
Photonics
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© imec 2006
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Combine 4 LUXIII-GTLP
 Practically: problem of dome
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Combine 2 OSTAR-GTLP
• Perfect match to Esys : ALV, f#
• 4:3 ratio
• Homogenization: uniformly illuminated rectangle
#
LED/GTLP
output
luminance
[lm/mm2sr]
captured
flux [lm]
collection
efficiency
[%]
volume
[mm3]
electrical
input power
[W]
electrical
efficiency
[lm/W]
Luxeon III
4
7.7
201.5
69.6
15*20*50
15.6
12.92
OSTAR
2
8.54
223.7
74
15*20*100
13.2
16.95
GTLP based light engine
Uniformity (ANSI):
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4xLUXIII system
- Brightest location: 5.2% greater than average
- Dimmest location: 8.8% less than average
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2xOSTAR system
- Brightest location: 1.6% greater than average
- Dimmest location: 8.3% less than average
Parabolic/Elliptical Reflector based light engine
Parabolic Reflector and Luxeon III
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4 LUX III – PR: collection within f#
Combining by reflecting pipe (60mm)
Perfect match to Esys : ALV, f#
4:3 ratio
Uniformly illuminated rectangle
Elliptical Reflector and Luxeon III
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4 LUX III- ER: collection witihin f#
Combining by reflecting pipe (60mm)
Perfect match to Esys : ALV, f#
4:3 ratio
Uniformly illuminated rectangle
Parabolic/Elliptical Reflector based light engine
Elliptical Reflector and 2 OSTAR
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Photonics
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2 OSTAR - ER: collection within f#
Combining by reflecting pipe (80mm)
Perfect match to Esys : ALV, f#
4:3 ratio
Uniformly illuminated rectangle
Elliptical Reflector and 4 OSTAR
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4 OSTAR - ER: collection witihin f#
Combining by reflecting pipe (60mm)
Perfect match to Esys : ALV, f#
4:3 ratio
Uniformly illuminated rectangle
Waste of flux (less efficient) but higher luminance
Parabolic/Elliptical Reflector based light engine
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4x PR and LUXIII:+3.1%/-9.5%
4x ER and LUXIII:+4.1%/-5.9%
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2x ER and OSTAR:+5.1%/-2.7%
4x ER and OSTAR:+3.2%/-2.1%
Photonics
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© imec 2006
Parabolic/Elliptical Reflector based light engine
Results:
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output flux
[lm]
luminance
[lm/mm2sr]
collection
efficiency[%]
electrical
power [W]
electrical
efficiency [lm/W]
volume
[ mm3]
4 Luxeon III+PR
134.7
5.14
45.4
15.6
8.63
45*45 *75
4 Luxeon III +ER
162.7
6.21
54.9
15.6
10.43
120*120*75
2 OSTAR+ER
186.2
7.11
61.6
13.2
14.11
16*100*95
4 OSTAR+ER
232.8
8.89
77
26.4
8.82
85*90*75
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Luxeon III: ER better PR (21%), but less compact
OSTAR based engines more performant than Luxeon based
engines
4 OSTAR boost in projected flux, but low power efficiency and
more volimunous
Uniformity
• Luxeon:ER more uniform than PR
• OSTAR engines better than Luxeon engines
• 4 OSTAR best uniformity
GTLP vs Reflector based multi LED engine
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Photonics
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© imec 2006
GTLP most compact and efficient (collection,power)
Only useable for LED’s with flat surface (no dome)
+ OSTAR, - Luxeon
ER/PR lower optical efficiencies, larger volume
Suited for LED’s with dome e.g. Luxeon, but also for OSTAR
type LED’s
Higher uniformity
ER approach better than PR approach, but larger
GTLP approach for OSTAR and Reflector approach for Luxeon
type LED’s
Conclusion
LED’s very interesting: superior properties but low
optical power  low power applications
 Optimally collect available flux and combine multiple
LED’s witihin the Esys
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Photonics
Europe
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Design multi LED collection engines: two approaches
GTLP approach most efficient: 8.54 lm/mm2sr (225 lm),
but only for LED’s with flat surface
 ER based approach for LED’s with encapsulating dome
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Acknowledgments
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‘Fonds voor Wetenschappelijk Onderzoek – Vlaanderen’ (FWO)
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Photonics
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‘Instituut voor de aanmoediging van innovatie door Wetenschap
en Technologie in Vlaanderen’ (IWT) and ‘Barco N.V.’
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© imec 2006
“Novel optical architectures for LCOS projectors”
“Compact high-quality LED projection systems”