light, color and improved color quality possibilities with led

Presenter: Eric Haugaard, Cree LED Lighting

Credit(s) earned on completion of this course will be

reported to AIA CES for AIA members. Certificates of

Completion for both AIA members and non-AIA

members are available upon request.

This course is registered with AIA CES for

continuing professional education. As such, it does

not include content that may be deemed or

construed to be an approval or endorsement by the

AIA of any material of construction or any method or

manner of

handling, using, distributing, or dealing in any

material or product.

___________________________________________

Questions related to specific materials, methods, and services will

be addressed at the conclusion of this presentation.

Through the ongoing advancements of LED technology, the

possibility to provide improved color quality performance and

value to the application space has never been greater. This

presentation will address the aspects of color science and the

various light source technologies used for general illumination,

with a strong focus on Light Emitting Diodes (LEDs). Included

will be a review of the most widely adopted methods and

metrics for describing all aspects of color quality and

performance for general illumination solutions. Examples

illustrating the current and future possibilities for accurately

predicting color quality performance and value in the general

illumination space will be discussed.

1. Exploring Light in Nature vs Man Made Light.

2. Light Source Science – LED and Traditional Technologies, A look

into the Future With LED

3. Understanding Object Color and the Importance of Broad Spectrum

Sources.

4. Challenges in Quantifying Color Quality

5. Meeting Color Quality Expectations in the Application Space

Light – What is it made of?

Light is made of waves (technically: electromagnetic waves of radiant energy)

very small waves…

Lights wavelength is measured in

billionths of a meter, nanometer (nm)

UV, Infrared (IR) heat, cell phone radio

waves, X-rays are the same waves…

just longer or shorter

Visible Light is wavelengths between

380nm and 780nm

• Different Wavelengths = Different Colors Light comes in different colors, spread across the rainbow of hues we

call the visible spectrum.

Red waves are the longest, purple the shortest

8

Blue Green Red

Visible Light

How Do Humans “See” Color?

• The eye contains cones and rods - cones are color sensitive and used for high light level vision (photopic) , rods are for night vision (scotopic)

• Three types of cones – long, medium and short .. Sensitive to red, green and blue areas of the visual spectrum

• Cones are concentrated in high density in fovea, Rods are spread across a much larger area inside the eye

Sunlight

Twilight

Starlight

Color Intensity Perception

White light consists of many colors

mixed together

Natural White Light (such as

sunlight) consists of a continuous

spectrum of all colors

Wavelength

Power

Relative Human Eye Sensitivity

The Human Eye Response Curve

555 nm Peak

13 1931 CIE Chromaticity Diagram

1976 CIE Chromaticity Diagram

How It Works

• Monochromatic (“high Saturation”) colors are on the outside edge of the diagram

“The Spectral Locus”

• All combinations of colors are on the inside, with white colors in the middle

14 1931 CIE Chromaticity Diagram

Red

Green

Blue

Steel @ 1500K Warm White

B type star >11,000K Cool White

Noon time sun @ ~ 6000K Cool White

Blackbody Radiation

Tungsten @ 2700K Warm White

1931 CIE Chromaticity Diagram

Color Gamut

19

Blue + Yellow Phosphor

Blue Peak

Yellow Phosphor

CIE 1931 Color Space

White Light for General Illumination

Creating White Light

WHITE LIGHT

LIGHT EMITTING DIODE

Epitaxial Layer

Substrate

LIGHT EMITTING DIODE

LED Package

Blue + Phosphor Generating White Light with LEDs

Phosphor

Blue LED

Spectral Power Distribution

Daylight Incandescent

Phosphor Converted LEDs

Spectral Power Distribution Phosphor Converted LEDs

Metal Halide Fluorescent

Phosphor Converted LEDs

Precise Color Tuning

31 Precise Color Tuning

32

• Even with the two source method choices abound

• Here is a system that starts and ends on the BBC

6500K

2700K

2700 Tc(K)

6500

Two Source White Color Tuning

Credit: Finelite, Inc.

33

• Here is a system that starts above the Black Body Curve and ends

below it

6500K

2700K

2700 Tc(K)

6500



34

• Customer acceptance will determine which two source White Color

Systems provides the best value

6500K

2700K

2700 Tc(K)

6500



Comparing Spectral Power Distribution

Incan-descent

Daylight

3000 K 3000 K

Color Rendering

Color Rendering Index (CRI) – A quantitative measure of the ability of a light source to reproduce

the colors of various objects faithfully in comparison with an ideal or natural light source

– Ranges from 0 (poor) to 100 (excellent)

Object Color

Spectrum

Object Color

Vision

Object Color

Color Rendering Index

Daylight In general terms, CRI (Ra) is a measure of a light source's ability to show object colors "realistically" or "naturally" compared to a familiar reference source, either incandescent light or daylight.

None of the 8 test colors used to calculate CRI are saturated. So, CRI is a poor measure for indicating how well a light source illuminates saturated colors. Even with a high CRI (Ra), color rendering of saturated colors can be poor.

CRI With Expanded Ra

Example

Color Rendering Index – R9

U.S. Department of Energy (DOE) Comments:

0 100 75 50

Poor Good Very good Excellent

Color Like Nature Meant it to Be!

This produce may appear

reasonable under a broader

color spectrum source.

Why is full spectrum color important?

What would you expect to happen

under a Low Pressure Sodium lamp?

Color Contrast

LPS LED

Color Contrast

What’s the Value of

Exceptional Color Quality?

52 Good CRI and Red Color Rendition is Important

For Illustrative Purposes Only

Images: Courtesy GE Lighting

53

For Illustrative Purposes Only

Good CRI and Red Color Rendition is Important

Different Colors…

Should Look Different

Help People

Look Their Best

Tunable Fitting Room Lighting

Photo Credit; Lux Magazine

Published in March 2015 Collaborative paper between CLTC, University of British Columbia and the National Research Council of Canada.

High Color Rendering Can Enable Better Vision

without Requiring More Power

Dim-to-Warm Solutions

EXAMPLE:

• Follows above curve from 2700K to 1800K

• At 1800K, similar color to candle light,

sunset, and sunrise

• High CRI throughout dimming

• Color changes naturally just as an incandescent lamp

Seeing is Believing…

LED Metal Halide

830W 3,070W

Daylight at Night?

Metal Halide 4000K ~65 CRI

R9 <0

LED 5000K 90+ CRI

R9 50+

64 400W Metal Halide

65 LED Solution

67 “Lighting Class” LED Devices

68 Color Stability

Blue Shift

Green Shift Yellow Shift

69 Long Term Color Point Stability

This is poor color consistency…

Typical Fluorescent and Metal Halide Challenges

Greater Possibilities With LED Solutions

71

New Color Rendering Metrics are Being Explored (IESNA TM-30-15)

72

Credit: Royer, US DOE

73


74


75


Presenter: Eric Haugaard, Cree LED Lighting

This concludes The American Institute of Architects

Continuing Education Systems Course

light, color and improved color quality possibilities with led

Technology