Light and Color Methods of Achieving High CRI with LEDs

Transcription

1 Light and Color Methods of Achieving High CRI with LEDs

2 Agenda Light and Color: Understanding the Basics Color Rendering Index for White Light Sources Methods for Creating White Light with LEDs New Techniques For Achieving High CRI OS SSL MK Page 2

3 High Color Rendering from LEDs play an important role in satisfying the light quality needs of end users and to accent the rich color which abounds in nature, interior design, clothing and fabric, jewelry, etc., while giving product and lighting designers the new lighting resources to continue to evoke emotional responses to lit environments. OS SSL MK Page 3

4 LIGHT COLOR AND QUALITY Understanding the Basics OS SSL MK Page 4

5 Nature of Light: Illumination and Sensing OS SSL MK Page 5

6 Spectral Power Distribution (SPD) IESNA Definition: A pictorial representation of the radiant power emitted by a light source at each wavelength or band of wavelengths in the visible region of the electromagnetic spectrum (360 to 770 nanometers). SPD plots for several common light sources showing relative radiate power as a function of wavelength. Gold: High Pressure Sodium Blue: CIE D65, model of average daylight at 6504K Red: Incandescent (3000K) Green: LED (6000K) OS SSL MK Page 6

7 Correlated Color Temperature (CCT) IESNA Definition: the absolute temperature of a blackbody whose chromaticity most nearly resembles that of the light source. The correlated color temperature (CCT) designation for a light source gives a good indication of the lamp's general appearance, but does not give information on its specific spectral power distribution. Therefore, two lamps may appear to be the same color, but their effects on object colors can be quite different. OS SSL MK Page 7

8 COLOR RENDERING INDEX For White Light Sources OS SSL MK Page 8

9 Color Rendering Index A measure of the degree of color shift objects undergo when illuminated by the light source as compared with the color of those same objects when illuminated by a reference source. Color Rendering Index R a The color rendering index describes how naturally a light source displays a set of different test colors. Reference and test light sources are calculated at the same CCT, measuring shift in chromaticity. Lamps that render color samples similarly will have a high CRI. The lower the CRI, the higher the luminous efficacy (lm/w) of an LED. # 8 # 1 # 2 # 3 # 4 # 5 # 6 # 7 OS SSL MK Page 9

10 Reference Illuminants (Light Sources) CRI measures the degree of color shift objects undergo when illuminated by the light source as compared with the color of those same objects when illuminated by a reference source of the same Correlated Color Temperature. Black Body Radiator: Color Temperatures in the range of 2300K < 5000K Daylight Spectrum: Color Temperatures in the range of 5000K 25000K OS SSL MK Page 10

11 Color Rendering Index Color Rendering Index R a Additional six special test color samples # 8 # 1 # 2 # 3 # 4 # 5 # 6 # 7 # 14 # 13 # 9 # 10 # 11 # 12 OS SSL MK Page 11

12 Color Rendering Index (CRI) Example CRI K CRI K CRI K OS SSL MK Page 12

13 Color Quality Rating of Color Rendering Index Definition of Color Rendering Classes for Color Quality OS SSL MK Page 13

14 Color Quality Industry Ratings Energy Star SSL Indoor Luminaires: CCT: 2700, 3000, 3500, 4000/4100K and 5000K for commercial CRI: Ra 80 SSL Indoor Lamps: CCT: 2700, 3000, 3500, 4000/4100K and 5000K CRI: Ra 80, R9>0 Designlights Consortium (DLC) Based on lighting application Application Minimum Light Output Minimum Luminaire Efficacy Allowable CCTs (ANSI C ) Minimum CRI Outdoor Pole/Arm-Mounted Area and Roadway Luminaires 1,000 lm 60 lm/w <5700K 50 Linear Panels (2x2 Troffers) 3,000 lm 60 lm/w <5000K 80 Four-foot Linear Replacement Lamps 2,200 lm 96 lm/w <5000K 80, R9>0 OS SSL MK Page 14

15 Limitations of CRI Small number of color samples, which are unsaturated. Test color samples 9-12 are for saturated colors, but they do not contribute to the computation of general CRI. CRI does not reasonably characterize highly structured, narrowband spectral emissions like those from SSL sources (red, green, and blue components) which may increase or decrease saturation of certain colors. One number cannot tell you everything. Cannot fully characterize the multidimensional experience of color such as color appearance, color fidelity, chromatic discrimination, vividness and observer preferences. Mock-ups remain the recommended method of assessing lamp color rendering properties, particularly in color critical applications. OS SSL MK Page 15

16 Limitations of CRI Example Same Chromaticity Same CCT Different CRI Different illumination lumens = 31.2 CCT = 3223 x = y = D(uv) = CRI=94 lumens = 217 CCT = 3231 x = y = D(uv) = CRI=1 OS SSL MK Page 16

17 New Metrics Color Quality Scale (CQS) (CIE TC1-69) Developed at the National Institute of Standards and Technology (NIST) to define and better qualify LED lighting. CQS involves several facets of color quality, including: color rendering, chromatic discrimination, and observer preferences. Main differences from CRI: Takes into account subjective color saturation perception - Gives weight to an increase of saturation addressing perception Measures color fidelity with regard to color saturation preferences Moderate increase of saturation is often correlated with desired color perception. Identifies color fidelity but is only one number! OS SSL MK Page 17

18 New Metrics CRI / Gaumut Area Index (GAI) Developed by ASSIST program to give subjective assessments of vividness, naturalness and acceptability. CRI and CRI-like metrics only evaluate a single aspect: fidelity. Good color rendering by a light source requires an optimum amount of color saturation. Gamut area index (GAI) is a good indicator of saturation. This two-metric recommendation using CRI and GAI together can ensure good color rendering. Results are representative of observers of different geographical origins and for sources of warm and cool CCTs, different spectral makeup, and light level. OS SSL MK Page 18

19 LED Spectrum is Critical for Interior Design Color Temperature (CCT) is not a perfect measure of lighting quality Color rendering index is another imperfect lighting quality metric, with its emotional impact dependent on the interaction of the illuminated surfaces Lighting spectrum, material textures and optical property interactions influence interior design results Managing the LED color spectrum can create varied emotions from sterile / clean to soft / warm OS SSL MK Page 19

20 METHODS OF CREATING White Light With LEDs OS SSL MK Page 20

21 How Do You Generate White Light? OS SSL MK Page 21 New Innovative Approaches

22 How Do LEDs Work? OS SSL MK Page 22

23 LED Phosphors OS SSL MK Page 23

24 LED Phosphors Entire white CCT-range ( K) LCW.CC CRI K LCW.EC CRI K LCW.PC CRI K LUW CRI K OS SSL MK Page 24

25 LED CCT Variations CRI 95 CRI 70 CRI 80 OS SSL MK Page 25

26 Traditional Light Sources Fluorescent CCT: 3000K CRI: 85 High Pressure Sodium CCT: K CRI: ~20 Tungsten Halogen 3000K CRI: ~ OS SSL MK Page 26

27 Lighting Technologies - The LED Advantage LEDs are an energy-saving alternative to conventional incandescent bulbs LEDs are point source emitters with precise optical control No radiated heat, only conducted. LEDs are available in all saturated and unsaturated colors LEDs are instant on-off and can be precisely controlled 9 Im/W 120 Im/W OS SSL MK Page 27

28 New Techniques For Achieving High CRI OS SSL MK Page 28

29 Phosphor-based High CRI Typical CRI of 95 R9 > 90 R13 > K Indoor Lighting Retail Lighting OS SSL MK Page 29

30 Phosphor-based High CRI Warm white (3000K) LED with a typical CRI R a = 95 and very good R 9 and R 13 values. OS SSL MK Page 30

31 The Efficiency and CRI Dilemma With standard white LEDs it is not possible to realize LED luminaires and lamps with both high efficiencies and high CRI. With the Brilliant Mix concept, high CRI and high efficiencies can be realized! Color Rendering and Luminaire Efficiency* Efficiency on luminaire level (lm/w) Brilliant Mix Solution *Luminaire efficiency considers thermal, optical and electrical losses OS SSL MK Page 31

32 Hybrid Approach - High CRI LEDs Brilliant Mix - Mixing of EQ White and Amber/Red LEDs results in warm white light...with a high CRI and a high luminous efficacy. Brilliant Mix Concept Mix of EQ White and Amber LEDs High efficacy and high CRI with R a > 90 Efficacies of >110 lm/w possible (2700K 4000K) at LED level OS SSL MK Page 32

33 Hybrid Approach - High CRI LEDs Brilliant Mix Concept Mixing of EQ White and amber LEDs enables warm white light sources. Combination of EQ White and Amber LEDs results in efficient light with a high CRI OS SSL MK Page 33

34 Hybrid Approach - High CRI LEDs Brilliant Mix Example Combination of Amber (617nm) and EQ White OS SSL MK Page 34

35 Hybrid Approach - High CRI LEDs Spectral Power Distribution OS SSL MK Page 35

36 Hybrid Approach - High CRI LEDs Brilliant Mix concept R values (2700K) CCT: 2700K OS SSL MK Page 36

37 OSLON SSL LED Compact and symmetrical with high luminosity Integrated silicone lens Excellent thermal management OS SSL MK Page 37

38 New LED Concepts Color tunable white Highly efficient, high CRI, white color tuning OS SSL MK Page 38

39 Summary FPO OS SSL MK Page 39

40 LED Source Measureables + + OS SSL MK Page 40

41 Summary CRI is the current way of describing a light s ability to render color. New metrics are being developed. New research and development is ongoing to improve LED color rendering and efficacy. LED sources can truly compete today for color critical applications. OSRAM Opto Semiconductors continues to lead the way in developing LEDs with superior high color rendering for every lighting application. OS SSL MK Page 41

42 Disclaimer All information contained in this document has been checked with the greatest care. OSRAM Opto Semiconductors GmbH can however, not be made liable for any damage that occurs in connection with the use of these contents. OSRAM Opto Semiconductor GmbH makes no representations and warranties as to a possible interference with third parties' intellectual property rights in view of products originating from one of OSRAM Opto Semiconductor GmbH's partners, or in view of products being a combination of an OSRAM Opto Semiconductor GmbH's product and a product of one of OSRAM Opto Semiconductor GmbH's partners. Furthermore, OSRAM Opto Semiconductors GmbH cannot be made liable for any damage that occurs in connection with the use of a product of one of OSRAM Opto Semiconductor GmbH's partners, or with the use of a combination of an OSRAM Opto Semiconductor GmbH's product and a product of one of OSRAM Opto Semiconductor GmbH's partners. OS SSL MK Page 42

43 OS SSL MK Page 43 Thank you for your attention.