BurkardWördenweber·JörgWallaschek·PeterBoyce·DonaldHoffman AutomotiveLightingandHumanVision BurkardWördenweber·JörgWallaschek PeterBoyce·DonaldHoffman Automotive Lighting and Human Vision With270 Figuresand22Tables 123 Authors ProfessorDr.BurkardWördenweber Dr.PeterBoyce Globaladvanced 60RiversideClose,Bridge VisteonDeutschlandGmbH CanterburyCT45TN,Kent EuropeanCorporateOffice&InnovationCentre UnitedKingdom Visteonstr.4–10 50170Kerpen ProfessorDonaldD.Hoffman Germany [email protected] UniversityofCalifornia DepartmentofCognitiveSciences Irvine92697,California ProfessorDr.-Ing.JörgWallaschek USA HeinzNixdorfInstitut [email protected] UniversitätPaderborn Fürstenallee11 33102Paderborn Germany [email protected] LibraryofCongressControlNumber:2006939127 ISBN 978-3-540-36696-6 SpringerBerlinHeidelbergNewYork Thisworkissubjecttocopyright.Allrightsarereserved,whetherthewholeorpartofthematerial isconcerned,specificallytherightsoftranslation,reprinting,reuseofillustrations,recitation,broad- casting,reproductiononmicrofilmorinanyotherway,andstorageindatabanks.Duplicationof thispublicationorpartsthereofispermittedonlyundertheprovisionsoftheGermanCopyrightLaw ofSeptember9,1965,initscurrentversion,andpermissionforusemustalwaysbeobtainedfrom Springer.ViolationsareliableforprosecutionundertheGermanCopyrightLaw. SpringerisapartofSpringerScience+BusinessMedia springer.com ©Springer-VerlagBerlinHeidelberg2007 Theuseofgeneraldescriptivenames,registerednames,trademarks,etc.inthispublicationdoesnot imply, even in the absence of a specific statement, thatsuch names are exempt from the relevant protectivelawsandregulationsandthereforefreeforgeneraluse. Typesetting:bytheAuthors Production:LE-TEXJelonek,Schmidt&VöcklerGbR,Leipzig Cover:FridoSteinen-Broo,eStudioCalamar,Spain Printedonacid-freepaper 68/3100YL-543210 Preface It is possible to buy excellent books on human vision as well as about automotive lighting. Unfortunately, these books have little or no common content. But in fact these fields do overlap. Providing optimal conditions for human vision is what automotive lighting is all about. Our motivation for writing this book arises from interdisciplinary stud- ies of human vision and lighting. Initially we intended the book to provide background information on human vision to engineers working in automo- tive lighting. At the same time we planned to introduce basic concepts of automotive lighting to experts in human vision. However because of the intricate connections between human vision and automotive lighting, it turns out that the book provides new insights to anyone interested in either or both subjects. The subject matter is complex and spans a number of disciplines from psychology to mechatronics. Hence there are very few individuals who are experts in all fields. Looking at the nature of human vision, it is surprising to find out how much every one of us takes it for granted. Rarely are we aware of how we use vision predominantly to verify our internal model of our surroundings. Many accidents, particularly at night, stem from the fact that our internal model misrepresented a significant part of our surround- ings. Taking knowledge on human vision into account in the design of fu- ture automotive lighting systems reduces the risk of accidents at night. After several futile attempts to write this book in a “standard way”, we decided to create it in an innovation cell. This is an intense work and study session, where authors meet and write simultaneously. Three of the four authors were doubtful whether it could all be written in just one week, but were later surprised how much can be achieved in such a short and concen- trated period. In fact within the week much more was accomplished than in either the three preceding or following months. We would like to thank all those who contributed to the book. We are par- ticularly grateful to Sabine Raphael, Bianca Lehde, Marco Eggert, Janet Wördenweber and all the external authors of the Spotlights. December 2006 Burkard Wördenweber, Jörg Wallaschek, Donald Hoffman and Peter Boyce Contents 1 Introduction......................................................................................1 2 How Vision Constructs Reality.......................................................9 2.1 Visual construction......................................................................9 2.1.1 Constructing shape and depth............................................10 2.1.2 Constructing shading and colour.......................................16 2.1.3 Constructing objects and their parts...................................23 2.1.4 Limits of attention..............................................................29 2.1.5 General principles..............................................................29 2.2 Models of visual perception.......................................................33 2.2.1 Signal detection theory......................................................33 2.2.2 Vision as bayesian inference..............................................41 2.2.3 Vision, evolution, and user interface.................................43 2.3 Visual structure and capabilities................................................48 2.3.1 The physiology of vision...................................................48 2.3.2 Continuous adjustments of the visual system....................60 2.3.3 Visual capabilities..............................................................72 2.3.4 Conclusions........................................................................93 3 Automotive Lighting - State of the Art...................................95 3.1 Headlamps.................................................................................96 3.1.1 Installation and function....................................................97 3.1.2 Optical concepts...............................................................100 3.1.3 Design aspects of headlamps...........................................116 3.1.4 Quality in development and production...........................121 3.1.5 Day and night appearance................................................142 3.1.6 Advanced front lighting...................................................146 3.1.7 Night vision systems........................................................153 3.2 Rear and signal lights...............................................................159 3.2.1 Installation and functions.................................................160 3.2.2 Design concepts...............................................................162 3.2.3 Optical concepts...............................................................163 3.2.4 Styling freedom................................................................171 3.2.5 Adaptive signal lights......................................................184 3.3 Interior lighting........................................................................185 3.3.1 Installation and function..................................................185 3.3.2 Filling space with light and colour...................................196 3.3.3 Special light sources........................................................197 VIII Contents and Index of External Spotlights 3.3.4 Control systems................................................................199 3.4 Ever-changing technologies for luminaires.............................201 3.4.1 Man made light sources...................................................201 3.4.2 Electronics for lighting....................................................215 3.4.3 Materials for lighting.......................................................221 3.5 Updating standards..................................................................245 4 Fundamental Problems with Automotive Lighting...................263 4.1 Mesopic vision.........................................................................263 4.1.1 Mesopic vision – The problem........................................263 4.1.2 Performance in mesopic vision........................................265 4.1.3 Implications for practice..................................................270 4.1.4 Mesopic vision – Conclusion...........................................272 4.2 Glare........................................................................................273 4.2.1 The forms of glare............................................................273 4.2.2 The quantification of glare...............................................277 4.2.3 Performance in the presence of glare...............................280 4.2.4 Recovery from glare........................................................290 4.2.5 Behaviour in glare............................................................292 4.2.6 Glare in practice...............................................................294 4.2.7 Xenon and halogen headlights.........................................295 4.2.8 Conclusion.......................................................................298 5 Automotive Lighting and Mechatronics.....................................303 5.1 Introduction..............................................................................303 5.1.1 Limitations of passive lighting systems...........................303 5.1.2 Technology push..............................................................307 5.1.3 Solving conflicts with active systems..............................307 5.1.4 The promises of active lighting systems..........................308 5.2 Automotive lighting systems from the perspective of mechatronics............................................................................309 5.2.1 Systems, energy, mass and information flows.................309 5.2.2 System structure of classical headlamp systems..............311 5.2.3 Mechatronic systems........................................................314 5.2.4 Basic system structures for automotive lighting..............315 5.3 Simplify your life - Improving passive lighting by adding just a little touch of mechatronics............................................323 5.3.1 Switching the lights on and off automatically.................323 5.3.2 Headlamp levelling..........................................................324 5.3.3 Dynamic bending.............................................................329 5.3.4 Interior light control.........................................................334 5.3.5 Lighting bus and wiring...................................................340 Contents and Index of External Spotlights IX 5.4 Active lighting.........................................................................340 5.4.1 Sensors and sensor systems for active lighting................341 5.4.2 Actuators for active lighting............................................347 5.4.3 Functional structures and functions of active lighting systems.............................................................................356 5.4.4 Active signal lights..........................................................371 5.5 Adding additional channels of perception...............................379 5.6 Active lighting or additional displays? – The principle of immediacy................................................................................385 5.7 Lighting future.........................................................................386 5.7.1 Rating of lighting systems...............................................387 5.7.2 Recommendations............................................................390 6 References.....................................................................................395 Contents and Index of External Spotlights XI Index of Spotlights Index of Examples We have used spotlights to illustrate the validity of the points made in this book. Many of the spotlights have been contributed by authors with differ- ent areas of expertise in various industries or institutes. We are grateful to the authors and appreciate their cooperation and the diversity of views they represent. You will recognise spotlights in the text by their special format- ting. A list of the external authors of spotlights is provided at the end of the index. Structure from motion.............................................................................13 Colour from motion.................................................................................20 Why do I sometimes see flickering rear lights?.....................................27 Change blindness.....................................................................................31 Information take-rate..............................................................................46 The closed loop: Driver – Car.................................................................58 Glance and the perceived present...........................................................64 Glance behaviour during driving...........................................................66 Conspicuity: Visible and different..........................................................69 Road lighting and headlights..................................................................74 Contour lighting.......................................................................................79 Braking is hard to do...............................................................................87 Optical and kinaesthetic feedback..........................................................92 Automotive projector modules.............................................................103 The emergence of the LED headlamp..................................................110 XII Contents and Index of External Spotlights Are my headlamps any good?...............................................................121 CAE in exterior lighting........................................................................126 Fogging and de-fogging of headlamps and tail lamps?......................134 Nanotechnology anti-fog coatings in automotive lighting and sensor applications.................................................................................137 Design appearance of headlamps.........................................................143 Advanced front lighting – Concept overview......................................147 Automotive night vision systems..........................................................153 Light guides for automotive application..............................................165 Ultra-thin LED lamps offering new design freedom..........................176 Entropy strikes.......................................................................................203 The bulb can make a difference............................................................205 LED control............................................................................................216 Exterior lighting – Lenses and reflectors history................................222 Thermoset – The plastic that keeps its shape......................................227 Reflective coatings - Mirror surfaces in luminaires............................233 Projection lenses for headlamps...........................................................239 Advanced front lighting reaching approval........................................247 Impact behaviour of automotive headlamp.........................................249 Guidelines for visibility and mounting requirements (SAE).............253 The origins of glare................................................................................275 Luminance as criterion to evaluate disability and discomfort glare.....................................................................................281 Contents and Index of External Spotlights XIII Don’t kill the jogger...............................................................................285 Reducing the stress of driving...............................................................287 “Headlights aren’t nearly as good as they used to be…”...................292 20 ways of dealing with glare................................................................299 Local lighting habits..............................................................................305 Lighting without glare...........................................................................318 Compensating for a heavy load, sharp braking or accelerating, by headlamp-levelling systems..............................................................325 Dynamic lighting....................................................................................330 Interior lighting – Not just a bright car interior.................................335 Bi-Xenon: Actuators and mechanisms competing for their role in front-lighting......................................................................................349 Vehicle surroundings - Sensing technologies for active lighting........358 Quality of automotive headlamp beam patterns.................................365 Emergency vehicle lighting...................................................................372 Virtual reality tools for headlamp design............................................374 Humanocentric design of driver assistance systems...........................381 A day in the life…..................................................................................389