This document summarizes a presentation on modern methods for tuning CCT and LED wavelengths for lighting applications. It discusses how LED technology is enabling a paradigm shift towards human-centric lighting that can promote well-being by mimicking natural light. Modern multi-color LED systems provide more degrees of freedom to precisely tune color qualities like CCT, CRI and spectral power distribution. Key challenges remain in developing integrated solutions that provide high color quality, dynamic control, low cost and simplicity for the user. Continued advances in LED technology are helping to realize the vision of human-centric lighting.

1. The Degrees of Freedom Provided by Modern
Methods to Tune CCT and LED Wavelengths
Wojtek Cieplik
LED Engin
5th International LED professional Symposium +Expo
LpS 2015 | Sept 22-24, 2015 | Bregenz

2. Paradigm shift in the lighting industry
Human Centric Lighting
Smart Lighting
A smart light engine for human centric lighting design
Future challenges
Outline

3. Was L&B 2014 a turning point?
it appears that way

4. Was L&B 2014 a turning point?
it appears that way

5. Was L&B 2014 a turning point?
it appears that way

6. Was L&B 2014 a turning point?
it appears that way

7. Fundamentals of life
as long as we are on earth, some things remain unchanged
MONEY SEXPOWER
AND…

8. NATURAL LIGHT
Fundamentals of life
as long as we are on earth, some things remain unchanged

9. to mimic natural light and (or)…
The challenge for the artificial light

10. Colour sensitive cones = 64% are
Red-sensitive, 32% Green and 2% Blue
Human eyes capture radiation through rods
and cones and dissect it into 3 components
The challenge for the artificial light
…to make our eye respond to it that way

11. HCL
Promoting
people’s
well-being
People’s
concentration,
efficiency,
safety
Healing
processes
Still not in
focus
Challenge
for LED
technology
To become
multibillion
business
Human Centric Lighting = focus on user

12. 0
1
2
3
4
5
6
7
8
9
10
Dynamic CCT
Colour rendering
Colour
consistency
# of colours
Beam angle
Frequency
DriverLumen output
Control protocol
Smart (sensorics)
Form factor
System costs
Simplicity
HCL (general) Museum Retail
Focus on user  Focus on quality
quality depends on the application

13. 0
1
2
3
4
5
6
7
8
9
10
Dynamic CCT
Colour rendering
Colour
consistency
# of colours
Beam angle
Frequency
DriverLumen output
Control protocol
Smart (sensorics)
Form factor
System costs
Simplicity
HCL (general) Museum Retail
Focus on user  Focus on quality
quality depends on the application

14. Smart lighting demands system approach
all the elements needed maximize user experience
Hardware & software Human factor
Tunable white
User interface
Sensors for touch
behaviour & activity
recognition
Light management system

15. Impact experienced by the users

16. light source & components
Integrated solutions

17. Light source Beam quality colour quality
Stability
Shadow
quality
Directional/
non-directional
Array of emitters
(low cost, mid
power)
Poor colour
mixing & tuning
CRI, R9
Not so stable
Worst >60⁰,
non-directional
more glare
COB Poor colour
mixing & tuning,
limited colour
positions
CRI, R9,
2-channels
Stable
Good 25~60⁰ reflectors/TIR lens,
less glare
Single multi-die
emitter
Superior in-
source colour
mixing, tuning, &
optimized colour
positions
CRI, R9,
multi-
wavelength
spectrum
Very stable
Best 10⁰~55⁰ TIR lens
less glare
Choosing optimal light source
according to quality of the beam, colour and shadow

18. Choosing the optimal light source
according to shadow quality

19. Choosing optimal white light
following the sun

20. Choosing optimal white light
following the sun

22. colour characteristics of artificial sources vary
• White light of equal appearance
can be created with different
Spectral Power Distributions
(SPDs)
• This chart shows the SPDs for
four different light sources, all
producing 2700K white light with
a CRI > 80
Mimic sun: mission impossible?

23. PHOSPHOR-CONVERTED (Pc) LED
Phosphors convert blue or near-UV light from
the LED into white light
COLOUR-MIXED LED
Mixing the proper amount of
light from red, green and blue
LEDs yields white light
HYBRID METHOD LED
A hybrid approach uses both
phosphor-converted and
discrete monochromatic LEDs
Pc vs. RGB vs. hybrid

24. demands measures
• Colour space map with black body curve
– Plank’s Law
• Colour space map with MacAdam’s
Ellipses
Benchmarking artificial to natural light

25. • Fixed White: Blue-Yellow
• Fixed/Dynamic White: RGB
• Linear Dynamic White: CW-WW
• Hybrid Dynamic White: R-mG-CW
can there be only one?
Choosing optimal multi-colour set-up

26. tunable white light engine, here with 2 features
Hybrid R-mG-CW enables

27. CRI throughout the CCT range
R in hybrid R-mG-CW enhances

28. Beware!
limitations of existing colour metrics may be confusing
Source: www.ssl.energy.gov

29. Beware!
limitations of existing colour metrics may be confusing
Source: Smithsonian American Art Museum

30. Market needs colour quality!
limitations of existing colour metrics may be confusing
Source: Xicato

31. Calibration
is the key to colour consistency overtime and temperature
Colour consistency for 40 units <2 SDCM in
Warm Dim mode
Colour consistency for 40 units <2 SDCM in
CCT Tune mode

32. Warm dimming
brings the emotion and sense of nature
Software solution helps to overcome driver
limitations
 Noise- and flicker-free
 Increased no of steps per channel
 Deep dimming (<1%)
 Variable frequency
 Increase refresh period as level decrease.
 Effectively decrease relative min turn off time
 Refresh interval randomization
 Provides better colour mixing

33. Are we there yet?
no!
 Control protocol (0-10V, DMX, DALI, Zigbee, …)
 Driver (AC / DC, 24/48V, frequency, flicker)
 Firmware, software
 Heat management
 Complexity of the system but simplicity for the user (UX)
 Total system cost
variety of decisions to make when designing user-driven
lighting system is significant

34. HCL
More
continuous
SPD
(mimic sun)
Freedom of
wavelengths
(460-
480nm, UV)
>3
individually
addressable
channels
Increased
CCT tuning
range
(2700-
6500K)
More beam
angles
(narrower,
wider)
HCL is defining LED product roadmaps

35. LZ7 platform 7x1mm2 dies
on AlO (white) 7x7mm substrate
flat lens
7 individually addressable colours
emitter-only or emitter-on-board
LED Engin’s roadmap

36. LZ7 platform 7x1mm2 dies
on AlO (white) 7x7mm substrate
flat lens
7 individually addressable colours
emitter-only or emitter-on-board
LED Engin’s roadmap
Designed primarily for versatile wash
lights with zoom optics
(ENTERTAINMENT)
R-G-B-CW-A-C-UV
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
350 400 450 500 550 600 650 700 750 800
RelativeSpectralPower
Wavelength (nm)
Red Green Blue White Amber Cyan UV

37. LZ7 platform 7x1mm2 dies
on AlO (white) 7x7mm substrate
flat lens
7 individually addressable colours
emitter-only or emitter-on-board
LED Engin’s roadmap
Designed primarily for versatile wash
lights with zoom optics
(ENTERTAINMENT)
R-G-B-CW-A-C-UV
A possible die design for HCL could be:
R-mG-B(460-480nm)-CW-WW-UV-x
Will this be the next generation platform for
HCL?
0.00
0.10
0.20
0.30
0.40
0.50
0.60
0.70
0.80
0.90
1.00
350 400 450 500 550 600 650 700 750 800
RelativeSpectralPower
Wavelength (nm)
Red Green Blue White Amber Cyan UV

38. Human Centric Lighting will keep enabling
crossover of technology, science & art
thank you

39. Back-up

40. Paradigm shift in lighting
according to value metrics
` Energy colour quality
& stability
Glare
(UGR)
Useful light
& cost
UX
Energy efficiency
(low & mid
power emitters)
lm/W CRI, R9
Not stable CCT
Multiple shadows
Large LES
Glare
lux/W low
lux/$ low
Not good
Warm dim/CCT
tuning
(single multi-die
emitter)
lux/W CRI, R9, COA
Stable CCT
Natural shadows
Small LES
TIR/Reflector
Less glare
lux/W high
lux/$ high
Good
Human centric/
connectivity
Sensors,
controls,
VLC
Natural light like Not visible Very
good
D
e
v
e
l
o
p
m
e
n
t

41. of 3 channels is closer to natural light than CW-WW
Spectral power distribution (SPD)

42. Optics
soul of the dynamic white solution
TIR lenses enable many functions
 color mixing, also in direct beam
 define the beam (cut)
 define shadow quality
 prevent glare

43. Promoting
people’s
well-being
Design
Materials /
Haptics
Sound
Air quality
& temp
Ergonomics
Proximity to
nature
LIGHT
Well-being depends on…

44. Healing
processes
Patients
are
scared
Daylight
is
important
Doctors
are
people
Cost isn’t
everything
Circadian
rhythm
Use the
best tech
Designing lighting for healthcare*
* Healthcare Lighting Forum, LuxReview
2014 Vol 3, Issue 3

45. Calibration
is the key to colour consistency overtime

46. Calibration
is the key to colour consistency overtime

47. Δu’v’ = 0.007 EnergyStar limit
Calibration
is the key to colour consistency overtime

48. Δu’v’ = 0.007 EnergyStar limit
Calibration
is the key to colour consistency overtime

49.  Background
 Dimming level and min switching time limited by driver hardware
 100~ 200 steps are common per channel
 Limited per channel minimum to 0.5-1%
 Different color ratio will limit the lowest dimming level to ~5%
 Solution
 Enhance lowest dimming level via software
 Applying algorithms to achieve <1% deep dimming
 0.5% deep dimming
 e-flickering-free and noise-free
 20kHz refresh rate
 Lowest dimming level at timestamp 4:30
 Software solution (<1%)
 Dithering
 Turn on and off bit pattern to increase level of dimming
 Variable frequency
 Increase refresh period as level decease.
 Effectively decease relative min turn off time
 Refresh interval randomization
 Provide better color mixing
 Decease need of higher frequency
Dimming

50. Challenges for the industry
 Will CRI prevail?
 Other solutions like GAI or CQS are available but still lack industry agreement
 Warranty
 Industry finds it difficult to make a box of circuitry last five years (see cars, aircrafts)
 Dimming compatibility
 wall dimmer vs. transformer vs. fixture
 Blue light discussion
 It helps to stay alert but can damage retinas
 Control protocols on debate
 Which protocol will be the way for the industry?
 DALI, DMX (-RDM), Zigbee, EnOcean, KNX, 0-10V, Bluetooth, custom/bespoke?
 Low cost integrated solution
 In-package driver, no cables, connectors

51. THANK YOU
Wojtek Cieplik
Regional Sales Director
Lighting OEMs & Specifiers
LED Engin Inc.
wcieplilk@ledengin.com