Interview zur Intelligent Transport Lighting Tagung 2010 (18.05.2010)

Good afternoon, Mr von Hoffmann,

 It’s an honour to have the opportunity to speak to you. You are the chairman of IQPC’s International Conference on Intelligent Transport Lighting, and furthermore you will contribute a presentation on Optical Simulation of LED Systems.

 1)        First of all, can you briefly explain to our listeners who you are and what your expertise is in?

 My name is Alexander von Hoffmann.  I studied Electrical Engineering at Technical University of Darmstadt , where I heard my first lighting lectures in the nineties.

In 1998 I started working at VOLKSWAGEN’s Lighting Development department. My first challenge was research and development of advanced front-lighting systems. Later I was working on mechanical design of SHARANs Lighting packages. In these days I received my PHD from University of Ilmenau.

In my last 3 years at VOLKSWAGEN I finally had the opportunity to introduce in function as a Team Leader a new development process in VOLKSWAGEN’s lighting department.

 In 2006 I became Professor for mechanical Design at Nuremberg University of applied sciences. My expertise is thermal, mechanical and optical Design of Lighting products with application of Simulation Software such as Light Simulation and Thermal Simulation.

 2)        Is it right to say that lighting has become an important innovation tool in the transport industry? And furthermore, what technological advances do you consider the reasons for this?

 I agree fully. Lighting Technology innovations provide benefits: LEDs have more design freedom and a better lifetime than conventional bulbs.

 But we should be honest: Lighting Innovations are not only chosen by clients due to technological benefits. They are regarded by clients as a “Must Have” – something like a gadget.

 Today a lot of car manufactures provide the same powertrain technology in basic and Top class cars such as skoda and AUDI or DACIA and Renault. Those companies had to find answers for the clients question, why they should pay more money for an AUDI than for a SKODA.

 

Lighting Technology is used by OEMs to create a clear difference between those basic and top class cars and is a good argument for customers to pay more for a certain car. A strategy, which can easily be adapted to other transportation branches.

 3) So what kind of new opportunities for the transport industry do you see brought about by LED technology? Are there similar topics that concern or excite the experts from aviation, railway as well as marine or automotive?

For interieur lighting – for all branches - I see as a clear benefit the simple feasibility of color mixture or color change. In Addition  a low energy consumption, low weight and low emitted temperature should mentioned as benefits.

 4)  Your presentation will be on optical simulation of LED Systems. Is this a challenging issue regarding LED technology?

Of course: Today no company can afford to built to many prototypes or trying guesswork on lighting design. Simulation for lighting is now well known for many years, and especially for LEDs a lot of very accurate Light Source information is provided by LED manufacturers helping the lighting engineer to perform his simulations. Still a challenging issue is performing color simulation, because more information about light sources and materials is needed than for a simple simulation of luminous intensities or iiluminances.  

 5) How do you model the LED light source?

There are many means to model the LED light source. In most cases it is the best way, to take near field photometry information from LED suppliers, which can be imported in all simulation programs. These Light source models consider the LED not as a point light source, but as an illuminated surface with a certain light distribution at each point of the surface.

 A critical point is, to determine the overall emitted luminous flux, which is dependent on surrounding conditions such as temperature or forward current of the LED.

 6)  So what are the special characteristics needed for an exact colour simulation of an LED arrangement?

 Temperature behavior of red, green and blue LEDs is different. So you need information, how a change of surrounding temperature is compensated by electronic drivers. For a perfect preparation of the optical simulation, a thermal simulation of the LED should be conducted. Finally, you need information about the color filter properties of applied materials and - in addition - information about the spectrum of the LEDs for the temperature surrounding. Finally, you should be able to display – and also understand - the result of your simulation in a CIE Diagram.

 7) That sounds very interesting indeed. As a last remark, is there something you would like to say regarding the conference to our prospect delegates?

I am convinced, that we have prepared an excellent program facing vital essential issues on LED Lighting. I  am looking very much forward to these interesting days in Hamburg, and hope to make a lot of interesting new contacts.

 Thank you very much, Mr. von Hoffmann, for your time and for providing a glimpse of the conference on Intelligent Transport Lighting.