The present work is concerned with the study and feasibility analysis of various options for generating white light for semiconductor based work light systems. Analyzed were phosphor converted (PC) systems (state of the art) and a system for RGB color mixing (generation of white light via red, green and blue light sources). Specific parameters for the evaluation are the color temperature and color rendering index (CRI). An LED and a laser diode concept for the RGB white light generation were developed. As a reference, existing systems based on phosphor conversion were evaluated. In the literature, options for optimizing white light generation via laser diodes by 4, 5 or 6 laser diodes for color rendering indices of > 80 are described. The present investigation uses only three laser diodes, which as a result produces a CRI of up to 45. Compared to phosphor- converted modules with blue laser diodes with a CRI of 71, this is an improvement worthy value. Furthermore, the problems and obstacles which can prevent a possible industrialization are analyzed in detail. For a laser-based system, these are the strong temperature dependence and the difficulty of bringing homogeneous white light onto the road. Furthermore I introduce a new method (TM30) for calculating new color reproduction criteria and I compare it with the CRI method. This new method, known from the solid state lighting, shows an appreciation of RGB white light sources. The presented RGB LED prototype achieved with the TM30 measurement method better parameters by an average of 2% than a comparable PC system.
In summary, the present work is a comparison of both technologies (PC and RGB). Generation of white light with RGB LEDs shows great potential, particularly in special applications (applications requiring variable spectra). RGB LD systems can be realized at the current state of the art well with satisfactory values. For further development there is a need of optimized LD type and number, optimized thermal management and an optimized optical system. At present, the quality parameters of RGB LD Systems are on average 20% lower than for comparable PC systems.
Inhaltsverzeichnis (Table of Contents)
- 1 Motivation, Objectives.
- 2 Introduction to Photometric Terms and Units.
- 2.1 Colorimetry.....
- 2.1.1 Normalized Colors X, Y, Z.
- 2.1.2 CIE Chromaticity Diagram.
- 2.1.3 Correlated Color Temperature (CCT).
- 2.1.4 Color Rendering Index (CRI)
- 2.1.5 Spectral Structure of Light Sources
- 2.2 Generation of White Light...\n.
- 2.2.1 Phosphor Conversion
- 2.2.2 Color Mixing.
- 2.3 Physiological Aspects.
- 3 Light Amplification by Stimulated Emission of Radiation – LASER
- 3.1 Possible Concepts for Worklamps...\n
- 3.1.1 Phosphor Conversion
- 3.1.2 RGB Color Mixing....
- 4 State of the Art Systems.
- 4.1 LED Worklamps...\n
- 4.2 Currently available colored worklamps for special applications......
- 4.3 State of the Art LASER Applications in Lighting.
- 4.3.1 BMW i8 High Beam Laser Light.
- 4.3.2 RGB Laser Scanning Module
- 5 Simulations........
- 5.1 Visualization of different Color Temperatures within DIALUXevo\n.
- 5.2 Calculation of CRI and CCT.
- 5.3 Influence of Colored Light on CAL simulations within HELIOS.\n.
- 6 Development of RGB LED/LD Worklamp Concept
- 6.1 Optics Development within CAD...\n
- 7 Prototypes..\n
- 7.1 Investigation Goal..\n
- 7.2 Color Tuning with Multichip LEDs
- 7.3 Color Tuning with Laser Diodes
- 8 Characterization
- 8.1 Measurement RGB LED Prototype - Quality..\n
- 8.2 Measurement RGB LED Prototype – Light Distribution.
- 8.3 Measurement RGB LD Prototype - Quality.
- 8.4 Measurement RGB LD Prototype – Light Distribution
- 8.5 Measurement Temperature Dependency of Red LD.
- 8.6 Measurement phosphor converted LED – Quality.\n-
- 8.7 Measurement phosphor converted LD - Quality\n.
- 8.8 New calculation methods...\n
- 9 Summary and Outlook (Innovations in Worklamp Light Quality).\n
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This Master's Thesis explores various methods of white light generation for worklamp systems utilizing semiconductor technologies. The study delves into the technical aspects of phosphor conversion (PC) systems, currently considered the state-of-the-art, as well as RGB color mixing systems. By focusing on color temperature and color rendering index as crucial parameters, the research proposes a Light Emitting Diode (LED) and a Laser Diode (LD) concept for RGB white light generation. The thesis also examines a reference system based on color conversion using phosphors.
- Assessment and comparison of phosphor conversion and RGB color mixing techniques for white light generation in worklamps.
- Analysis of the limitations and advantages of RGB laser diode systems in relation to conventional phosphor conversion technologies.
- Evaluation of color rendering properties, color temperature, and other relevant parameters for different white light generation approaches.
- Investigation of the potential for optimizing RGB white light generation using laser diodes.
- Exploration of the feasibility and practical considerations for implementing RGB-based worklamp systems.
Zusammenfassung der Kapitel (Chapter Summaries)
- Chapter 2 introduces fundamental photometric terms and units, with an emphasis on colorimetry. It discusses the concept of normalized colors X, Y, Z, the CIE Chromaticity Diagram, correlated color temperature (CCT), and color rendering index (CRI), along with the spectral structure of light sources. The chapter explores different methods for generating white light, including phosphor conversion and color mixing.
- Chapter 3 delves into the concept of Light Amplification by Stimulated Emission of Radiation (LASER) and its potential applications in worklamp systems. It examines both phosphor conversion and RGB color mixing techniques for generating white light in worklamps.
- Chapter 4 reviews the state-of-the-art systems, focusing on LED worklamps, currently available colored worklamps for special applications, and existing LASER applications in lighting. This chapter discusses examples like the BMW i8 high beam laser light and RGB laser scanning modules.
- Chapter 5 explores simulation methodologies for assessing the performance of different light sources. It outlines the visualization of various color temperatures using DIALUXevo, the calculation of CRI and CCT, and the analysis of the influence of colored light on simulations within HELIOS.
- Chapter 6 outlines the development of an RGB LED/LD worklamp concept. The chapter delves into the detailed process of optics development within a Computer-Aided Design (CAD) environment.
- Chapter 7 explores the prototyping phase, focusing on the investigation goal, color tuning with multichip LEDs, and color tuning with laser diodes.
- Chapter 8 presents the characterization results for both RGB LED and RGB LD prototypes. It analyzes the light quality and distribution of each prototype, examining the temperature dependency of the red laser diode. Additionally, the chapter compares the performance of phosphor-converted LED and LD systems.
Schlüsselwörter (Keywords)
This research focuses on semiconductor-based light generation methods for worklamp systems, particularly exploring phosphor conversion (PC) and RGB color mixing techniques. Key themes include color temperature, color rendering index (CRI), light distribution, and spectral characteristics. The study analyzes the potential of RGB laser diodes (LD) for white light generation and compares them to conventional PC systems, highlighting the challenges and opportunities associated with this technology.
- Quote paper
- Ing; M.Sc; MBA Albert Krammer (Author), 2016, Advanced Light Sources for Premium Worklamp Systems, Munich, GRIN Verlag, https://www.grin.com/document/1165411
