LucidShape-Poly Curve Systems

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1.1. IntroductionThere are two types of headlamps in automotive lighting: free form reflectors and projector type headlamps(also called Poly Curve Sstems). Nowadays the latter ones are widely used, especially in the higher classcars. The advantage of these headlamps is to build systems with smaller spatial dimensions. Hence they caneasily be used in so called AFS lamps (advanced front lighting systems).

1.2. The concept of Poly Curve SystemsThe poly curve system is mainly build up by a reflector, a shield, a light source and an aspherical lens. Thefilament of the lamp is positioned in the first focus of the reflector and the shield in the second. The shieldserves as an absorber, i.e. only rays above the shield reaches the lens thus forming a cutoff line in the shapeof the shield. This way, different types of low beampatterns can be achieved according to ECE or SAE regula-tions, respectively. The lens can be created using the create projector lens dialog box. The reflector can becreatedwith different predefined configurations. It is also possible to create various LED reflector applicationsusing this tool. To design projection systems, it is sometimes necessary to use different lens types. Therefore"PCS Projector Lens" offers the possibility to create seven different lenses such as aspherical lens, free formFresnel lens, rotational lens, rectangular lens, elliptical and spherical shaped lens and finally TIR lens, whichuses total internal reflection. The reflector can be createdwith different applications: "Poly Ellipsoid Basics","Poly Ellipsoid Advanced", or "Poly Ellipsoid Complete".The samples can be found under "Application/PCS Application with Predefined Configuration", recall PCSis the abbreviation for Poly Curve System and PES means Poly Ellipsoid System.Furthermore it is possible to create reflectors in the form of compound parabolic concentrators (CPC) butwith the option to vary the light spread with free form curves.

1.3. ConfigurationsLucidStudio comeswith several predefined configurations for Automotive PCSHeadlamps to build the differentapplications. These are described in an extra document.The individual "Poly Ellipsoid" samples uses different kinds of base curves.

The Tutorial Poly Ellipsoid servesas a base model for the construction. Within this example, only elliptical base curves have been used. ThePCS Applicationswith predefined Configurations aremore advanced, they are based on any number of differentfree form curves which may have individual local axis systems. The base curves can have different spatialorientations. The PES bi-function D=65 and PES low beam for example, use this latter version in order tocreate special reflectors for a bifunctional and low beam application.

1.4. Poly Curve System (PCS)The Poly Curve System allows the use of any number of base curves. It is used in the applications with pre-defined configurations. Each curve has it??s own local axis system, therefore each curve can have any arbitraryspatial orientation. The reflector may also have steps between adjacent curves. The flexibility permits forexample the design of a bi-function module for low and high beam, where the upper and the lower parts ofthe reflector are separated by a step.The upper part of the reflector generates the major part of the low beam pattern below the horizontal line,while the lower part creates the high beamwith a light concentration above the horizon. The switch betweenthe low and high beam parts is realized by a dynamic removable shield.