{"title":"High performance LED lamps for the automobile: needs and opportunities","authors":"W. Pohlmann, T. Vieregge, Martin Rode","doi":"10.1117/12.760978","DOIUrl":"https://doi.org/10.1117/12.760978","url":null,"abstract":"Light emitting diodes have been an option in automotive lighting for more than 15 years now. The capacities and colours of LEDs available in the recent past were sufficient to realize interior lighting and rear signalling functions. In the meantime, series applications, such as position or daytime running lights, using white LEDs for signal functions in headlamps, are no longer a rarity. The next step - realizing main lighting functions for series applications - is imminent. LED will offer a multitude of styling options in rear and front lighting, as well as a light colour which differs considerably from that of the previous halogen and xenon headlamp systems. The further advantages of the LED compared with conventional light sources with regard to service life, power efficiency and package space requirements can thus only be sensibly exploited by means of suitable structural and connection techniques. Increasing complexity and installation conditions in an often rough environment are demanding challenge to realize the hardware of LED lamps. In this paper at first the requirements on LEDs and LED modules in automotive exterior lighting will be discussed. Furthermore the status of industrialization and modular concepts for signal lamps and full LED headlamps will be presented. The paper will finish with a discussion of new headlamp active lighting functions like maker light or glare free high beam, implemented in hybrid or with pure LED technology. In the subsequent headlamp integration, from about 2012, freely-addressable LED-Arrays will possibly enable these new types of lighting functions.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131588355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
H. Winkler, H. Enderle, C. Kuehn, R. Petry, T. Vosgroene
{"title":"Advanced phosphors for LED applications","authors":"H. Winkler, H. Enderle, C. Kuehn, R. Petry, T. Vosgroene","doi":"10.1117/12.761291","DOIUrl":"https://doi.org/10.1117/12.761291","url":null,"abstract":"In this paper we give a summary of technologies that are essential for phosphor developing: Characterization of the pure phosphor powders with methods like powder X-ray diffraction (XRD), optical spectroscopy, scanning electron microscopy (SEM), etc. give strong hints for and how to improve the phosphor's performance. The final proof of the phosphor's quality is obtained by application testing in the LED. Latter is a very useful tool for materials researchers and developers to adopt the phosphor to the LED device. Last but not least we demonstrate advantages of a phosphor fabrication process by using wet chemical routes in comparison to the traditional and widely applied solid state diffusion methods (\"mix & fire\").","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"268 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116832434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"LEDs in automotive lighting and signaling: a customer point of view","authors":"S. Berlitz, Christiane Heider","doi":"10.1117/12.765539","DOIUrl":"https://doi.org/10.1117/12.765539","url":null,"abstract":"The development of brand specific front and tail lights in cooperation with the stylists is the assignment of automobile lighting. Highest car safety, attractive styling, differentiation in the traffic situation and environment friendliness are the project limits. LED technology has the potential to extend these limits. The LED technology will have to improve, but it is also enhanced by new sensor technologies that introduce new functionalities. The implementation of a possible roadmap depends on right technologies at the right time. For new styling ideas and functional innovations further steps in lighting technology are necessary. The document will show a car makers view on possible innovation ideas.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131782671","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Improvement of ultra-high-brightness white LEDs","authors":"Tanja Mesli","doi":"10.1117/12.768084","DOIUrl":"https://doi.org/10.1117/12.768084","url":null,"abstract":"As LEDs became the preferred light source for coloured light, the focus is now on improving the performance of white LEDs, to achieve the required levels for applications such as general lighting. One especially interesting automotive application of white LEDs are daytime running lights, which may become mandatory in the near future in Europe. In this application the specific advantages of LEDs like long lifetime, high efficiency, robustness and freedom for the designers can be fully employed. The most common way to realize a white LED is the approach of a luminescence conversion LED, where blue light of a GaN Chip is partly transformed into yellow light by a phosphor. The combination of the not converted blue and the yellow light results in white light. A strong increase of the luminous flux becomes possible by the use of High Power LED Chips, high efficient yellow phosphors and a packaging that offers an excellent thermal management. First of all, the application of a High Power LED Chip allows an increase of the electrical current up to 1 Ampere. While this increases the light output significantly, the thermal management of the LED package has to be improved in order to remove the heat created by the LED chip. Apart from chip efficiency and driving current the brightness of a white LED also strongly depends on the efficiency of the used phosphor. Today's typically used phosphors are for example YAG:CE, or with Europium 2+ doped compounds. The required quantum efficiency should be higher than 90% for good results in the luminous efficiency. Furthermore, for certain applications such as automotive front lighting the converter even has to be stable under temperature conditions up to 120°C, be resistant to humidity and guarantee a long lifetime. In this contribution we will present a comparison of several different types of phosphors with emphasis on their temperature dependent behaviour.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"56 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122664242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Metal contacts to p-type GaN by electroless deposition","authors":"L. Lewis, D. Casey, J. Rohan, P. P. Maaskant","doi":"10.1117/12.758947","DOIUrl":"https://doi.org/10.1117/12.758947","url":null,"abstract":"Initial results are presented on the electroless deposition of metal contacts to p-type gallium nitride (GaN). Deposition procedures were developed for the deposition of both nickel and tungsten-cobalt (W-Co) contacts onto p-type GaN. Attempts to deposit platinum on p-type GaN failed, despite the fact that electroless platinum deposition was successfully achieved on other substrate types. Nickel contacts were overlaid with gold and annealed in oxygen ambient to form ohmic contacts with specific contact resistivity values down to 2x10-2 &OHgr;cm2. Measurements at elevated temperatures up to 140 degrees C showed that the specific contact resistivity was almost independent of temperature. The tungsten-cobalt contacts showed rectifying behaviour even after annealing at 650 degrees C. This makes this contact type a possible candidate for Schottky contacts in high temperature applications.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124747466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Phosphor-converted high power LEDs","authors":"R. Mueller-Mach, G. Mueller, M. Krames","doi":"10.1117/12.754744","DOIUrl":"https://doi.org/10.1117/12.754744","url":null,"abstract":"Phosphor converted Light Emitting Diodes (pcLED) have undergone many changes of design over the last 11 years. For advanced applications, however, besides other binning criteria a closely binned color point appears to be a major issue. Manufacturing yield is closely related to this point. Philips Lumileds Lighting (PLL) introduced very recently a new compact solid state color converter - Lumiramic - which allows much closer color control by selecting perfect matches between blue pump LEDs and previously characterized converter tiles in a pick-and-place process. Lumiramic phosphor technology utilizes a ceramic phosphor plate and PLL's new Thin Film Flip Chip (TFFC) technology. A first application in Automotive Forward Lighting and some of the design considerations are outlined in the paper","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"3 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114839642","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A. Knauer, V. Kueller, S. Einfeldt, V. Hoffmann, T. Kolbe, J.-R. van Look, J. Piprek, M. Weyers, M. Kneissl
{"title":"Influence of the barrier composition on the light output of InGaN multiple-quantum-well ultraviolet light emitting diodes","authors":"A. Knauer, V. Kueller, S. Einfeldt, V. Hoffmann, T. Kolbe, J.-R. van Look, J. Piprek, M. Weyers, M. Kneissl","doi":"10.1117/12.774648","DOIUrl":"https://doi.org/10.1117/12.774648","url":null,"abstract":"MOVPE grown InGaN multiple-quantum-well (MQW) light emitting diodes (LEDs) on c-plane (0001) sapphire emitting at 375 nm with GaN, Al0.16Ga0.84N and InxAl0.16GaN-barrier layers were investigated in order to study the influence of the barrier composition on the light output characteristics of near UV devices. By substituting the GaN barrier layers with Al0.16Ga0.84N the output power increased 30-fold due to the increased band-offset between the In0.03Ga0.97N QWs and the barriers. The addition of 3.3% indium to the AlGaN barriers resulted in a reduction of the FWHM, and a 50-fold increase in light output power compared to LEDs with GaN barriers. Even though the band-offset and hence the carrier confinement for the InAlGaN barriers is smaller than in the case of AlGaN barriers, strain compensated In0.03Al0.16Ga0.79N barrier layers seem to be greatly beneficial for the external quantum efficiency of the near UV LEDs. The effect of an n-type Al0.23Ga0.77N hole-blocking-layer, which was inserted below the MQW stack to prevent hole carrier leakage from UV LED active region, on the light output was also investigated. By incorporating strain compensated In0.03Al0.16Ga0.79N barriers and an Al0.23Ga0.77N hole blocking layer we were able to realize 375 nm LEDs with an output of 1 mW (measured on-wafer) at 100 mA. Finally, the wavelength dependence of the light output from UV LEDs with InGaN MQWs emitting between 375 nm and 381 nm with peak output power of 4 mW at 200 mA for the longer wavelength devices is shown.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"283 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2007-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116091681","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Converter film technology for homogeneous white light","authors":"R. Jordan, J. Bauer, H. Oppermann","doi":"10.1117/12.759437","DOIUrl":"https://doi.org/10.1117/12.759437","url":null,"abstract":"Rafael C. Jordan, Jorg Bauer, and Hermann Oppermann Fraunhofer Institut fur Zuverlassigkeit und Mikrointegration (IZM) Gustav-Meyer-Allee 25, D-13355 Berlin, Germany Email: jordan@izm.fhg.de, Phone: +49(30)46403-219, Fax: +49(30)46403-271 1. Introduction An important issue for white ultra high power LEDs is the generation of a homogeneous light with high efficiency and a good color rendering index. Different from hot light sources LEDs do not emit the whole range of visible wavelengths. Only a certain wavelength with a limite d full width at half maximum is emitted. Therefore a combination of wavelengths must be used to satisfy the human eye for white light. The CIE chromaticity diagram (Fig. 1) show s, that several combinations of wavelengths let the brain realize white light. Already the combination of two wavelengths (e.g. cyan and red or blue and yellow) let us think, that the source is white, if this wavelengths hit our receptors. This is completely different, if the light is illuminating an object. The reflection spectra of this object, which is crucial for our color f eeling about this object, can not be stimulated in the whole ra nge. For example a red stop sign, which is absorbing all wavelength excepting red, will absorb the blue and yellow light from our \"white\" light source and due to the missing red, the sign seems to be dark grey or black.","PeriodicalId":245823,"journal":{"name":"Manufacturing LEDs for Lighting and Display","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128500337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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