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									             Adjustable Color Light LED Lamp Graduate Thesis Project

                Submitted to the Engineering Excellence Fund Committee
                           University of Colorado at Boulder

                                      March 2, 2007

                                    Primary Contact:
                                     Sergio Andermann P.
                          Building Systems Studies Graduate Student
                      Civil, Environmental and Architectural Engineering
                                        (720) 883-2114


                                    Michael J. Brandemuehl
                      Civil, Environmental and Architectural Engineering
                                       Office: ECCE 249
                                        (303) 492-8594

                                        Moncef Krarti
                      Civil, Environmental and Architectural Engineering
                                      Office: ECCE 247
                                       (303) 492-3389

The purpose of this project is to design and build an electronic LED lamp that would change the
color of the light in a range of yellow, white and blue. The user would be able to either choose
the desired color by entering the exact °K value of the light in a small keypad, or manually by
increasing or decreasing the °K value by pushing “up” and “down” buttons. Such a device, that
doesn’t exist commercially, would be useful for several lighting applications. In particular, the
user would be able to change the appearance of the light from incandescent to fluorescent within
the same luminaire.
The idea behind this Thesis, conducted by the Civil and Architectural Engineering Department,
is to explore the existing LED lighting technologies and find new applications for a growing
market like this, especially when focusing on finding energy efficient alternatives in the
construction field.

Brief Introduction:
In the Architectural Lighting Design field there are many aspects to consider when
selecting a technology; one of them is the color of the light (measured in °K).
Incandescent lamps provide warm white light which color is more close to yellow
(around 2,800°K) while fluorescent lamps provide colder white light, more close to blue
(4,000°K). And even when there are several devices to control other aspects of light,
such as intensity, yet there is nothing that would allow the user to select a desired color
within the same lamp.
The LED (light emitting diode) it’s a semiconductor component that emits light of a
certain wavelength when an electric current passes though it. This is a very low power
consumption device that can be found in hundreds of different applications. But it
wasn’t until a few years ago when it started to be used as an illumination alternative,
and although the price per watt emitted still being high, today there are several
illumination corporations that sell all kinds of luminaires that operate with LED’s.
There are dozens of different colors for LED’s that go from blues to reds and greens.
There are also several white ones, which manufactures sell, among other specifications,
by their color temperature (measured in °K).
LEDs have many advantages, one of them being the fact that they are dimmable over a
1000 times without compromising either the Color Acceptance Index (CAI) or the
Color Rendering Index (CRI) [1]. However, the combination of light of different colors
and intensities may create more colors. My hypothesis is that it is possible to achieve
every color temperature in a certain range by dimming sets of LED’s of different colors
without compromising the overall luminous intensity.

Project Description:
The idea is to design and build an electronic high intensity LED luminarie that would
allow the user to change the color of the light by either selecting the desired color
temperature with a numeric keyboard, or by increasing or decreasing the value by
pushing “up” and “down” buttons. The lamp would provide only white-yellow-blue
colors in a range between 1,800 and 7,000K. The desired colors would be achieved by
changing the luminous intensities of sets of different LEDs.
The lamp will consist of two separate components; the controller and the luminaire.
    - The luminaire: This would be the actual lamp. It will be made of steel, covered
        with glass and would allow heat dissipation on the back. It will contain LEDs of
        at least 4 different sets mounted in an electronic board, each one of them
        corresponding to a different color. The controller will turn on all these sets in
        different intensities according to the color of the light requested. All LEDs will
        be mixed among them in a certain order (as shown in the image bellow); this
        will ensure that the light produced by them would be well mixed and that the
        luminous intensity would be equal for all cases.

        Figure 1, example of LED array               Figure 2, Luxeon Emitter LED

       Due to its characteristics, I will use the 1W Luxeon emitting LED produced by
       Philips (shown in figure 2). However, the exact number of LEDs and their color,
       as well as the shape of the lamp are part of the project’s investigation and are
       unknown at this moment.
       The control module: It will be apart form the lamp, connected to it with a cable
       and will host the main electronic circuit. All functions will be controlled by an
       Ubicom SX48AC 40 pin microprocessor programmed in a Parallax Inc.
       development embedded system.
       This module will also include the liquid crystal display, the keyboard and the
       power supply.

The project plan:

I started to work a few weeks ago, and I established myself a work plan that include, but
it’s not limited to the following tasks:
a) Assembler programs:
     - PWM routines: (Phase Wide Modulation) the basic digital procedure for LED
     - Liquid Crystal Display, keyboard module routines.
     - Keyboard routines
     - The main program (combination of all of the above)
     - The calibration
b) Electronic circuits:
     - Power supply
     - Interface circuit
     - The control module circuit board design
     - The luminaire circuit board design
c) Luminaire and control module design and construction

In a parallel process I will do research on the following topics:
    - Basic state-of-the art publications in LED lighting systems and control of LED
    - Colorimetry and color rendering index theory, including the X, Y and Z
    - LED lighting output and semiconductor theory.
    - Testing plan

The biggest challenge is to find a way to convert the X Y Z equation to an ensembler
program and relate the color to a digital signal.
The entire project it’s intended to be finished by December 2007.

Student Impact:
This is a research project that will provide a deeper knowledge in LED illumination
systems emphasizing on its applications and advantages. It could be used at CU’s
illumination courses to show students the benefits of this fast growing technology,
taking on account the fact that it’s a very clean and energy efficient illumination option.
It is also very innovative, since it suggests a non-existing alternative for lighting design
that could have countless applications.

Economic Feasibility:
The LED industry has been able to reduce its costs. The price per watt emitted by an
LED has been going down year by year, therefore, the costs on materials and electronic
components, including the LEDs themselves won’t be really high, especially when
considering that most of the acquiring and testing of the device will be done by
software. In fact, such a device could be produced for commercial purposes and sold for
a reasonable price (depending on its size). The only sensitive issue regarding this
project is the testing, and for that, certain equipment is needed. My request to the EEF is
to support me by purchasing the embedded system to program the microprocessor, as
well as some measuring instruments that CU presently does not have. In particular, I
require a color meter; an instrument the measures both the luminous intensity (in Foot
candels) and the color of the light [2] (in K). Without this device it will be impossible to
calibrate the luminaire. The rest of the expenses will be covered by me.

Team Qualifications:
My name is Sergio Andermann; I’m a graduate student of the Building Systems Studies
program as part of the Civil and Architectural Department expecting to receive my
degree by December 2007. I have undergraduate studies in Electrical Engineering at the
Universidad Iberoamericana, in Mexico City. Back then I received my degree after
presenting a Thesis project on “Intelligent Houses”, as I designed and build a model of a
house with several home-made sensors, interfaced with a microcontroller and connected
to a remote terminal.
Also in Mexico City I worked in the paper industry for 20 months until I decided to
open my own start up company in illumination related electronic circuits and LED
lamps. For almost two years I designed and manufactured illumination systems and
devices for different applications. The main purpose of this project is to continue
working with LED light and to achieve a deeper knowledge about this new technology
that promises to grow and maybe become the illumination alternative for the future.

1:Luxeon (Philips) web site:

Project Budget
Please provide the information listed below. Type NA where not applicable.


  Total Project Budget          $1,781.02

                EEF Request $1,372.95

Outside funding:
 Source                                                      Total Amount
                                      Confirmed? [Y/N]
  Department Contribution                     N              $
  College Contribution                        N              $
  Personal / family contribution              Y              $ 408.02
  Advising, lab time/equipment                Y              $ N/A


Salaries (benefits should be included in total salary):

  Student Name              Grad or         Hourly        %        Length    Total Amount
                            Undergrad       Rate          Time     Of
                            [G/U]                                  Time

                                                                   Total $

Equipment and Materials:
                                              Unit Price         Quantity    Total Amount
  Item Name / Description
  Basic Stamp 2p40 module                     $89.00                 1       $89.00
  Parallax Professional Development Board     $149.95                1       $149.95
  Grayhill 12 keyboard module                 $21.99                 1       $21.99
  General electronic components*                                    set      $100.00
  LXHL-BW03 Warm white Luxeon LED*            $2.99                 10*      $29.99
  LXHL-BW02 Cold white Luxeon LED *           $2.99                 10*      $29.99
  LXHL-BL01 Yellow Luxeon LED*                $1.30                 10*      $13.00
  LXHL-BR02 Blue Luxeon LED*                  $2.41                 10*      $24.10
  Materials to build the luminaire*                                 set      $100.00

  Gossen Colormaster 3F                       $1223.00               1       $1223.00

                                                                 Total $     $1781.02
 * This models and quantities may change


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