Advanced Light Sources for Premium Worklamp Systems (eBook)

Master's Thesis from the year 2016 in the subject Electrotechnology, grade: 1,0, University of Linz (Technisch- Naturwissenschaftliche Fakultät), course: Optoelektronik, language: English, abstract: 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.