News Column

"Headlight for a Motor Vehicle Having an Interchangeable Complex Light Source" in Patent Application Approval Process

September 3, 2014

By a News Reporter-Staff News Editor at Electronics Newsweekly -- A patent application by the inventors Brendle, Matthias (Tuebingen, DE); Hamm, Michael (Eningen u.A., DE); Fadel, Kamislav (Stuttgart, DE), filed on August 17, 2012, was made available online on August 21, 2014, according to news reporting originating from Washington, D.C., by VerticalNews correspondents.

This patent application has not been assigned to a company or institution.

The following quote was obtained by the news editors from the background information supplied by the inventors: "The invention relates generally to a headlight for a motor vehicle and, more specifically, to a headlight for a motor vehicle having an interchangeable complex light source.

"The present invention relates to a headlight for a motor vehicle with a housing, at least one semiconductor light source generating light for a main function of the headlight, a cooling body touching the semiconductor light source in thermal coupling, an optical system collecting and directing light of the semiconductor source, a securing frame mechanically connected to the housing which holds the semiconductor light source with the cooling body and the optical system in the housing, and having an interface between a first part forming a complex light source and includes at least the semiconductor light source and the cooling body, and a second part, including at least the holder, wherein the first part is connected to the second part at the interface so that it can be separated without destruction. Such a headlight is known from published U.S. Pat. No. 7,712,948.

"In the art of illuminating devices for motor vehicles a distinction is made between 'lights' and 'headlights.' Lights serve the purpose of signaling the presence and/or behavior of a motor vehicle and/or the intentions of its driver to other traffic participants. For example, brake lights, flashing lights, and navigation lights (without this being an exhaustive list).

"Headlights serve the purpose of actively lighting the roadway in front of a motor vehicle such that the driver can quickly recognize obstacles in the roadway. The light distributions generated by headlights needs to be compliant with government regulations (for example, to prevent the blinding of other traffic participants). Examples of light distributions generated by headlights include passing light and high beam light distributions (without this being an exhaustive list).

"The task or capacity of a component to generate light distributions, be it light distributions or headlight distributions, is also referred to in the art as a light function. With respect to an illuminating device acting mainly as a headlight, headlight functions are also referred to as the 'main function: so as to distinguish from other light functions provided by the same illuminating device (for example, when an illuminating device also performs signal light functions).

"As known in the art of mass-produced road vehicles, semiconductor light sources have only been used for main headlight functions since around the year 2008, and were introduced earlier for signal light functions. One reason for the delay was the need for higher electric power for main functions in comparison to signal functions.

"Because of the relatively lower light fluxes produced by semiconductor light sources used in the automotive industry, several semiconductor light sources are typically combined into complex light sources for main headlight functions, so as to obtain the desired overall high light fluxes. Because of the long service life of light emitting semiconductors, little emphasis has been placed on repair options for headlights with semiconductor light sources until recently. Further, at the beginning of the development of high-performance semiconductor light sources, little data was available about the service life and the probability of failure of the light sources. Initially, it was assumed that the service life of the semiconductor light sources would be more than sufficient for the service life of a motor vehicle. However, there is now great deal more experience available about the durability and the probability of failure of semiconductor light sources used for main headlight functions. There is a desire in the art for interchangeable semiconductor light sources. Particularly in the case of motor vehicles from the mid-range or lower-range price segment, high repair costs for used motor vehicles are undesirable, even where there is a high probability that few motor vehicles are affected by light source failures. Without interchangeable semiconductor light sources, the entire headlight assembly would have to be replaced, which could require a disproportionately high cost compared to the value of the vehicle.

"However, difficulties arise in the case of such a replacement. Unlike halogen lamps, semiconductor light sources (such as LEDs) have a thermal interface in addition to the usual electrical and mechanical interfaces (for a power supply and positioning the light source). The thermal interface conducts away the heat generated in the operation of the semiconductor light source. Typically, the LED is firmly thermally coupled to a cooling body with thermal adhesives or heat sink paste. Thus, unlike the mechanical and electrical interfaces, it is difficult to provide the LED with a separable connection.

"Further, in the event of a change of the light source there is the danger of the optical system going out of adjustment and causing the oncoming traffic to be blinded. Moreover, light modules for main headlight functions typically require a horizontal and a vertical default setting. Because of this, mounting light modules is expensive and typically prevents disassembly and replacement of the light modules for repair purposes. For this reason, light modules known in the art involve fixed units, where the light module can not be changed without destroying the unit after installation of the headlight during production.

"To change LED light sources in the headlight in spite of these obstacles, Published U.S. Pat. No. 7,712,948 provides a light source module that has at least one light emitting element (in particular, LEDs), fiber optics, and collimating elements or lens elements. In addition, a retainer for such a system is provided, in particular in the form of a motor vehicle headlight. The headlight also has an optical system. The light source module is equipped to be positioned on a reference plane of the optical system, wherein it is also equipped to be replaced in a simple way, in particular without requiring soldered or welded connections.

"The light source module known in the art has light exit surfaces arranged in series. A longitudinal edge of this arrangement is considered an optical element and should be reproduced by a further optical element (referred to as secondary as a light/dark border of a light distribution of the headlight. To this end, an exact and stable positioning of the longitudinal edge is necessary with respect to the further optical element. First, second, and third reference points are provided for this exact positioning between optical faces of the module and the optical system of the headlight. For example, the reference points should be made of hard rubber, plastic or metal. Position correction should be made possible by altering the thickness of the reference points. A change in the position of the LEDs with their cooling body relative to the remaining light module is also mentioned as an alternate setting option."

In addition to the background information obtained for this patent application, VerticalNews journalists also obtained the inventors' summary information for this patent application: "The present invention differs from the prior art with a first part forming the complex light source having at least one optical system collecting and directing a light of the semiconductor light source in addition to the semiconductor light source and the cooling body. In this way, the interface lying between the light exit surfaces of the semiconductor light source known in the art is shifted between the first interchangeable first part and the second part remaining in the headlight. Thus, the shifted interface no longer lies between the light exit surfaces of the semiconductor light sources and the optical system.

"Between the light exit surfaces of the semiconductor sources and the entry into the subsequent optical system in the roadway, occurring inaccuracies in position have a strong effect on the quality of the resulting light distribution. This holds true in particular for projection systems whose primary optical systems are used with short focal distance and narrow tolerances in order to produce an intermediate image of the light entry surface of the semiconductor light sources, which is then projected by a subsequent projection lens in the roadway as light distribution into the front region of the headlight.

"Due to the inventive shifting of the interface, an advantage is achieved in that no inaccuracies in position occur in the interface between the light exit surfaces of the semiconductor light source and the optical system when the light source is changed. The interface is a part of the pre-installed complex light source as a whole. Thus, inaccuracies in position occurring in the interface do not have as strong an effect on the quality of the light distribution created by the headlight.

"Ultimately, using the present invention, a headlight equipped with semiconductor light sources for main functions is provided, in which the light source can be easily changed in case of repair. In particular, the headlight is not incorrectly adjusted when changing the light source. Neither the location of the light module in the headlight nor the optical system of the light module itself is changed in the replacement of the light source.

"In one embodiment, the headlight has a housing with a service opening which is open from the factory, or is equipped to be cut open in a predetermined service opening region in case of repair. In operation, the headlight housing has geometries for fastening a cover with which the service opening in the headlight can be closed again after replacement of the complex light source.

"In one embodiment, the first part and the second part together form a light module which is a projection module. Further, the light module has a cover equipped for amplification of a brightness gradient at a light/dark border of the light distribution. In another embodiment, the cover is a minor cover equipped to direct incident light of the semiconductor light sources on a secondary optical system of the projection module.

"In one embodiment, the optical system of the complex light source includes all optical components of the light module. Further, the light module is a projection module and the optical system of the complex light source includes a cover as well as a secondary optical system. In a further embodiment, the secondary optical system is a projection lens or a parabolic minor.

"In another embodiment, the individual parts of the complex light source are detachably connected to one another. Further, the complex light source has an electronic component in which parameters of the electrical interface are stored, wherein the parameters can be read via a control device. Further still, the complex light source is equipped with a temperature sensor (in particular, an NTC or PTC resistor) with which the temperature of the light source can be determined.

"In one embodiment, the complex light source can be mechanically connected to the light module with detachable fastening elements (for example, screws, latches, bolt or bayonet locks) such that the complex light source can be separated from the light module and replaced without destruction. The latches, bolt, or bayonet locks have at least one spring that presses a bolt or another latching geometry into a counterpiece, in which a bolt element is held (either non-positively or positively). Further, the spring and the bolt element may be designed to be in one piece. The bolt element may be part of the complex light source. Further still, the bolt element may be part of the second part. In another embodiment, several spring elements are equipped to clamp the first part and the second part to one another without play.

"Additional features and advantages arise from the dependent claims, the description and the attached figures.

"The foregoing features and features still to be explained can be used not only in the respective specified combination, but rather also in other combinations or by themselves without departing from the scope of the present invention.


"Exemplary embodiments of the invention are presented in the figures and are described in greater detail in the subsequent description. The figures show the following, in each case in schematic form:

"FIG. 1 shows an exemplary embodiment of an inventive headlight with a light module;

"FIG. 2 shows the light module from FIG. 1 with a first part detached from the second part of the light module, but not completely withdrawn from the first part;

"FIG. 3 shows an embodiment of a complex light source forming the first part of the light module from FIG. 2 completely withdrawn from the second part of the light module;

"FIG. 4 shows an exploded view of the complex light source of FIG. 3;

"FIG. 5 shows a front view of the headlight with the light module;

"FIG. 6 shows a lateral view of the subject matter of FIG. 5;

"FIG. 7 shows one embodiment of the light module as a projection module in sectional view;

"FIG. 8 shows sectional views of a complex light source together with an interface to the second part of the light module; and

"FIG. 9 shows reference geometries and springs at the complex light source and a securing frame."

URL and more information on this patent application, see: Brendle, Matthias; Hamm, Michael; Fadel, Kamislav. Headlight for a Motor Vehicle Having an Interchangeable Complex Light Source. Filed August 17, 2012 and posted August 21, 2014. Patent URL:

Keywords for this news article include: Patents, Electronics, Legal Issues, Semiconductor.

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Source: Electronics Newsweekly

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