 We have redesigned it from the ground up to provide visitors with streamlined navigation, more detailed information and rich educational material. Here are some of the new features:
| ||
| And it will not stop there. We are dedicated to constantly improving ourselves, our products and our services. Stay tuned for continuously updated content, educational materials, videos and more. Visit us now at http://fusionoptix.com ! | ||
Monday, September 24, 2012
Have you checked out the Fusion Optix's redesigned website yet?
Monday, August 13, 2012
Top 5 Advantages of using LED Color Mixing to Create White Light (Part 3 of 3)
 |
| Additive Color Mixing |
Beyond wavelength conversion technologies such as chip
level, volumetric, or remote conversion technologies, the third way to create
white light using LEDs is by color mixing.
Like an RGB pixel of any standard video monitor, color mixing uses the
principles of additive color to combine two or more colored LEDs to create
white light. By far it is the most
electronically complex method of creating white light, as it depends on some
type of control of the LED RMS current through either Pulse Width Modulation
(PWM) or Amplitude Modulation which dims LEDs of different color combinations
(such as red, green, blue, mint green, amber, even yellow or cool white) at
appropriate intensity levels to achieve white light of a desired color temperature. As with any lighting system, there will
always be advantages and challenges.
Top 5 advantages
of using LED Color Mixing to Create White Light:
1. Color uniformity
Capitalized upon by Cree through their TrueWhite™
technology, LEDs of different color are actively controlled via dimming through
either some type of optical, thermal, or electrical feedback system. This helps increase color uniformity from
fixture to fixture.
2. Easily customizable color temperature
Where chip level or remote conversion techniques require
different chemistries to achieve different CCTs such as 2700K, 3000K or 4100K, LED
color mixing often requires nothing more than a simple firmware change to set
the CCT of the system. This introduces a
higher level of simplicity on the manufacturing side, which helps lower the
overall cost of the system.
3. Advanced controllability during dimming
The PWM controls used in an LED color mixing system enable
the system to be inherently more controllable during dimming in application-
which opens the door for better color performance in a dimmed down state. A common complaint observed with dimmed LED
systems is the even further absence of a red component, which gives dimmed LED
lighting a faint, ghostly appearance, far from the warmer dimmed tone of an
incandescent bulb which is more generally preferred. By designing for increasing levels of red
and/or amber LED light while dimming, the system can more accurately
approximate the performance of an incandescent bulb.
4. Lower LED cost
Since issues such as color uniformity and dimming can be
effectively solved using the control techniques described above, LED binning becomes
less of a concern, which enables the usage of less expensive and larger
bins. This lower LED cost, however, may
be offset by higher costs in electronics and firmware.
5. High system efficacy and CRI
Luminous efficacy and CRI can be significantly increased
using LED color mixing with the use of red and green LEDs. Since the value of a “lumen” is based off the
human eye sensitivity curve and CRI is dependent on the blackbody spectrum of
Tungsten, adding strong green and red components can give a significant boost
to lumen and CRI performance.
As can be seen, LED color mixing in general does enable improved
color controllability and potentially superior CRI and efficacy performance as
well compared to the other two methods we have discussed. Of course, the types of systems mentioned
above do present some challenges. A
color mixing system will invariably require an array of LEDs which can limit
beam control options, and will most certainly require an efficient diffuser to
reduce shadowing on the application surface.
The inclusion of some mixing chamber or mixing distance into any system
using this technology is often desirable as well. Additionally, care must be taken during the
design to account for varying lumen maintenance of different color LEDs. Since Red LEDs often have a much longer lifetime
and shallower lumen maintenance curve than their cooler counterparts, care must
be taken to balance system color performance from a programming perspective as
well as heat sinking to make sure this higher lumen maintenance is accounted
for so the system does not experience a red shift over the course of its life.
Since all three conversion methods
to create white light discussed in this series- chip level (either volumetric
or true chip level), remote, or color mixing- all offer their advantages and
disadvantages, each may lend itself more pertinently to one application over
another. It is ultimately up to the
designer to determine which method to choose whether it is choosing the
appropriate light engine for a given fixture, or choosing the appropriate
fixture for a given application.
Friday, July 20, 2012
Creating White Light Using LEDs
Part 2) Optical Effects of True Chip-Level Conversion vs. Volumetric Conversion
When designing a secondary optic
for use with LEDs, the method of chip-level phosphor conversion has more
influence on optical performance than many would think. There are basically 2 methods of chip level
conversion. In what I call true chip-level
conversion, the phosphor is deposited directly on the LED die, as in the case
of the OSRAM Golden Dragon Plus (Fig 1).
 |
Fig 1: OSRAM’s Golden Dragon Plus
exhibits true chip-level conversion, where the phosphor is deposited directly
on the die
|
The other most widely used method for phosphor application and conversion is known as volumetric conversion such as in the Nichia 183A (Fig 2). In volumetric conversion, the phosphor effectively floods the chip package and the blue die rests underneath a sort of pool or film of phosphor.
 |
Fig 2: Nichia’s 183A Series is an example
of an LED using volumetric phosphor conversion, where the blue die sits beneath
a die film
|
While either method can be argued to be equally efficient
and effective at converting blue light to white light as phosphors are intended
to do, each presents a different set of challenges for secondary optic design.
An LED
utilizing true chip-level conversion better approximates a point source of
light compared to an LED which uses the volumetric method. This has a major influence in optical design
applications where a point source is essential to light quality and efficiency. For example, most parabolic optics will
require a point light source to maintain efficient beam control. When using a volumetrically converted chip, shadowing
and dark/light rings are often observed due to its diffuse nature, where the
larger emitting area creates superfluous reflections within the optic. Another example of the importance of focal
point location occurs in refractory optics, such as batwing style lenses which
perform very extreme light bending and have a very low tolerance on focal point
location, such that much of the light escaping from a volumetrically converted
chip enters the optic at incorrect incident angles, resulting in color
separation and undesirable Fresnel scattering losses which can result in lower
optical efficiency.
There
are indeed times when a volumetrically converted LED is desirable,
however. In light guides, the larger
diffuse surface of the LED widens the area of injection, and effectively
narrows the spacing between LEDs which will promote a shallower mixing area
thus enabling larger emitting areas for the light guide. This can lead to thinner and more attractive
bezel design in, for example, LCD panels.
Also, volumetric conversion can be a reason to choose a particular LED
when the LEDs are placed very closely behind a diffuser lens which requires
higher backlighting uniformity. As can
be expected, the extra few millimeters of emitting surface area provided by a
volumetric conversion can help with uniformity at the surface, especially in
the case of very high clarity diffusers.
In the
case of reflective optics where flat and angled reflectors are used to direct
and control the light, chip-level phosphor conversion method perhaps matters a
little less. A key point to remember in
a situation such as this is that highly specular surfaces can be glary and
distracting to people in the space.
However, when flat reflector are used, the concept of a focal point
usually does not come into play and for the most part light exiting from an LED
or array of LEDs has already achieved a far-field characteristic by the time it
first reflects off a flat optic.
Designing
for high optical efficiency is one of the most cost effective ways of maximizing
the efficacy of an LED lighting system.
By paying attention to the type of optics needed for the application,
and selecting the right LEDs to be used with those optics based on knowledge of
the phosphor conversion method, designers can realize easy and significant gains
in system efficiency.
Fusion Optix has years of experience in selecting the right LEDs to meld with our innovative AirOptics(tm) secondary optics, LED modules, and light diffusers to help our OEM customers select the right LEDs for their applcaition. Visit our website at www.fusionoptix.com, call us at (781) 995 0805, or email us at info@fusionoptix to learn more!
Wednesday, July 11, 2012
What is the difference between luminance vs. illuminance?
What is the difference between luminance vs. illuminance?
When talking about light, one of
the most confusing terms will be luminance and illuminance. They are more or less used incorrectly by people,
sometimes even by the people in the industry.
Luminance
Luminance is the density of luminous intensity in a given direction and
falls within a given solid angle.
It is measured in cd/m2.
Luminance is often used to characterize the emission from a diffuse
surface. It indicates how much luminous power will be perceived by eye when
viewing the surface from a particular angle. Luminance remains the same
regardless of the distance from the light source.
 |
| Luminance is the light that is coming out of a surface. Photo Credit: Fusion Optix's Display |
Illuminance
Illuminance is the density of photons which fall within a given surface
area. It is measured in lux, or footcandle(fc).
Illuminance can be measured with a lux meter. For a given light source,
the closer to a light source the illuminated area is, the higher the
Illuminance value.
 |
| Illuminance is the light falling to a surface. |
Monday, July 9, 2012
Creating White Light using LEDs
By Mike Georgalis, LC
Different methods to create white light include chip-level conversion, color mixing, and remote conversion utilizing Fusion Optix ColorTune™ Technology
By Mike Georgalis, LC
Different methods to create white light include chip-level conversion, color mixing, and remote conversion utilizing Fusion Optix ColorTune™ Technology
When it comes to creating white
light using LEDs, there are many different methods, all of which have their
advantages and disadvantages. First, the
most common and traditional is chip level conversion, where the converting
material is integrated directly onto the blue LED die or fills up the LED
package volumetrically. Another method
is color mixing using red and white (or mint colored) LEDs, where the LEDs are
dimmed and mixed to create the desired color temperature. A third method is converting the blue light
of a diode far away from the chip, which utilizes a mixing chamber and remote
optic integrating a converting Phosphor, Fluorescent Dye, Quantum Dot, or
Fusion Optix’ proprietary ColorTune™ technology.
This series of Fusion Optix Blog
postings will focus on the characteristics of each of these methods to help
engineers and designers choose the right conversion method for their system.
Creating White Light Using LEDs Part 1:
Using Remote Wavelength Conversion Optics
How Remote Phosphors, Dyes, Quantum Dots, and Fusion Optix ColorTune™ Technology Impacts Lighting System Performance.
| without ColorTune™ | with ColorTune™ |
In a remote wavelength conversion
optic, discrete blue LEDs are mounted in an array, and directly illuminate the
inside surface of a lens which contains the conversion material. There are many different types of conversion
methods available on the market today including Phosphors, Fluorescent Dyes,
Quantum Dots, and Fusion Optix’ proprietary ColorTune™ technology. Typically, the lens is mounted as part of a
mixing chamber several centimeters away and from the LEDs to provide uniform
light at the surface. This method
results in a number of optical and thermal effects of which designers should be aware.
1)
Thermally, there will be heat generated on the
lens from the wavelength conversion.
Designers should be sure to select materials with high conversion
efficacies to minimize this heat which can cause rapid deterioration of the
lens substrate or the conversion material itself. This results in the need for creative heat
sinking of the lens- which is often a challenge since lenses are not often made
form highly thermal conductive material, and they do not frequently have a very
large or tight thermal interface with heat sinking materials.
2)
Remote conversion optics often result in large,
diffuse emitting areas, which can pose challenges in down lighting and spot
lighting for tight beam control. Just as
there will be losses from the conversion, a designer should be aware of high
losses from using a large diffuse source where a point source should be i.e. in
a parabolic lens.
3)
Remote conversion methods can offer advantages
in binning and color uniformity- which can reduce the overall cost of a
system. Especially when used to control
white light exiting from chip level LEDs, using wavelength conversion to more
finely tune output during production can allow OEMs to purchase larger, and
therefore cheaper, bins of white LEDs
4)
Aesthetically, many remote conversion
technologies have a yellow, green, or red tint when the light engine is off (as
opposed to the normal white diffuser or just fully visible CFL or incandescent
light source), an unfamiliar effect that some lighting designers have found
hard to swallow. This is a matter of
taste, but I am not sold on this is a sole reason to move away from remote
conversion technology.
Fusion Optix has developed industry leading wavelength
conversion technologies in our ColorTune™ family of optical components. To take advantage of our optical expertise
and highly efficient systems using ColorTune™ optic, visit http://www.fusionoptix.com/solutions/lighting/components/colortune.htm
or email us at sales@fusiopnoptix.com.
Thursday, January 26, 2012
Wednesday, January 18, 2012
Subscribe to:
Posts (Atom)