Abstract:
A headlight system is provided for a motor vehicle and includes, but is not limited to at least one light source and beam-forming apparatus for generating the main light beam with an essentially horizontal cut-off line and a marker light beam within a limited azimuth angle range above the cut-off line of the main light beam. The beam-forming apparatus are switchable between at least two stationary states that differ from each other in the progression of an upper cut-off line of the marker light beam.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to German Patent Application No. 10 2012 013 730.3, filed Jul. 11, 2012, which is incorporated herein by reference in its entirety. 
     TECHNICAL FIELD 
     The technical field relates to a headlight system for a motor vehicle with which a so-called marker light can be generated. 
     BACKGROUND 
     Headlight systems for motor vehicles which support two operating states suitable for use on the moving vehicle, i.e., full beam and dipped beam, have been known for decades. In the full-beam mode a more widely fanned light beam is emitted, in which not only the carriageway in front of the vehicle but also objects above the carriageway or on the edge of the carriageway are clearly recognizable, which however has the disadvantage that oncoming traffic users are blinded. The dipped beam is essentially aimed only at the carriageway, thereby avoiding blinding the oncoming traffic but restricting recognition of objects that are directly on the carriageway surface. 
     In order to improve perceptibility of such objects headlight systems have been proposed in later years that additionally support a marker light, i.e., a normally narrowly limited light beam with which objects recorded in the vicinity of the vehicle can be specifically illuminated so as to alert the driver to their presence, or so as to enable him to quickly and reliably identify these objects. The DE 10 2009 035 743 A1 in particular has, for example, revealed a headlight system with a light source and beam-forming apparatus in the form of movable apertures, which permits generation of the main light beam with an essentially horizontal cut-off line and at the same time permits the generation of a marker light beam within a limited azimuth angle range above the cut-off line of the main light beam. One of these apertures comprises a horizontal edge with a notch formed therein, where light incident through the notch forms the marker light. The broader the notch and the marker light beam defined by it, in particular in a vertical direction, the quicker and more reliably the driver can recognize the marked object. It is undesirable for the person misinterprets the marker light beam as a sign of the driver that he/she has been seen and can cross the carriageway. 
     It is at least one object to indicate a motor vehicle that on the one hand is able to generate a vertically extended marker light beam that enables the driver of the motor vehicle to quickly and reliably perceive an object illuminated by the marker light beam, but which on the other hand limits undesirable effects caused the marker light beam. In addition, other objects, desirable features, and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background. 
     SUMMARY 
     A headlight system is provided for a motor vehicle with at least one light source and beam-forming apparatus for generating a main light beam with an essentially horizontal cut-off line and a marker light beam in a limited azimuth angle range above the cut-off line of the main light beam, the beam-forming apparatus can be switched between at least two stationary states that differ from each other in the progression of an upper cut-off line of the marker light beam. Due to the fact that the cut-off line of the marker light beam passes below head height of an illuminated person, undesirable effects of the marker light beam can be avoided. Even if the respective person perceives that part of his/her body is hit by the light, the source of this light cannot be determined by him/her as long as the marker light beam does not hit the eyes. Therefore the light, by which such a person is hit, cannot be associated by this person with a particular motor vehicle, and this person can therefore not erroneously deduce that the light represents a signal for him/her. 
     According to a first design of the invention the headlight systems can comprise a plurality of light sources switchable by the beam-forming apparatus, of which at least two contribute to the marker light beam. Due to the fact that, in the first stationary state, these at least two light sources are switched on, an object can be extensively marked; in that if, provided the object to be marked is a person, at least one light source of the at least two light sources is switched off, the head of that person can be kept un-illuminated so that the marker light beam is not noticed by the marked person or at least its origin is not recognizable by the person. With this design the beam-forming apparatus are of an essentially electric or electronic nature. 
     According to a second design the beam-forming apparatus comprise at least one first movable aperture which is held in respectively different positions in the first and second stationary states. Further the beam-forming apparatus may comprise a second aperture that defines an elongated edge that in at least the first and second stationary states defines the cut-off line of the main light beam, and also comprise an opening cut out adjacent to the edge and limiting the marker light beam. Preferably this opening is a notch open towards the edge in the second aperture. 
     In order to avoid that the head of a person is illuminated, the first aperture may cover part of the opening of the second aperture in the second stationary state. In case the first aperture covers part of the opening also in the first stationary state, the coverage in the second stationary state is greater than in the first. According to a further embodiment the first aperture may comprise a point, which protrudes into the opening in the second stationary state. In this way in particular, a cross-section of the marker light beam can be generated which albeit leaves the head of a person in the dark, but still illuminates the environment to the right and left of the head. In a third stationary state of the headlight system, in particular if no marker light is to be emitted, the first aperture can completely cover the opening. 
     According to a convenient further development the second aperture is also movable. In the above mentioned three stationary states the position of the second aperture may always be the same. Preferably, due to the movement of the second aperture, the cut-off line of the main light beam is movable, in particular in order to switch between dipped beam and full beam. 
     In order to start a movement of the first aperture this may be coupled to a motion link that is driven by a cam which is moved in an oscillating manner. The same cam or a second cam which is moved because it is coupled thereto may interact with a motion link of the second aperture if this also is movable, as mentioned above. 
     In order to be able to align the marker light beam with an object in the environment of the vehicle, it is preferred that the beam-forming apparatus form an assembly which is pivotable at least in azimuthal direction. Preferably the at least one light source belongs to such an assembly. 
     Preferably the system further comprises an environmental sensor such as a camera and an evaluation and control unit connected with the environmental sensor for selecting between at least the first and second stationary state based on information of the environmental sensor. The evaluation and control unit may be a microprocessor, in particular, on which an image evaluation program is executed for identifying persons and other objects to the marked, if required. The evaluation and control unit may be adapted to control a pivotal movement of the assembly based on information of the environmental sensor, in particular in order to align the marker beam with an object identified based on the information of the environmental sensor. The evaluation and control unit may further be conveniently coupled to a vehicle steering system in order to pivot the assembly coupled to the steering at times when the evaluation and control unit does not record an object to be illuminated by the marker light beam. 
     In order to be able to make a meaningful decision whether the first or the second stationary state shall be set, the evaluation and control unit should be able to classify an object recorded by the environmental sensor. The classification may include differentiating between humans on the one hand and animals and lifeless objects on the other, but a classification is also feasible between live and lifeless objects so that animals on the edge of the road, if possible, are not irritated by the marker light beam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and: 
         FIG. 1  shows a schematic illustration of a headlight system according to a first embodiment with electronic beam-forming apparatus; 
         FIG. 2  shows a schematic illustration of a scenery illuminated by the headlight system; 
         FIG. 3  shows a first embodiment of a headlight system with mechanical beam-forming apparatus; 
         FIG. 4  shows a second embodiment of the headlight system with mechanical beam-forming apparatus; 
         FIG. 5   a - c  show variants of the headlight system of  FIG. 4 ; and 
         FIG. 6  shows a third embodiment of the headlight system with mechanical beam-forming apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description. 
     The schematically shown headlight system of  FIG. 1  comprises two front headlights  1  for a motor vehicle that are configured to be essentially identical or mirror-inverted relative to each other and of which, for reasons of simplicity only one is shown, an environmental sensor such as an electronic camera  2  or a radar system and a microprocessor  3 . The front headlights  1  and the camera  2  are mounted in a motor vehicle in the usual way such that they illuminate/record the environment in front of the vehicle. 
     The front headlight  1  is comprised of a plurality of light sources arranged in a two-dimensional matrix, in particular of white light LEDs  4 , as well as a lens  5  or lens array arranged in front of the LEDs  4  in order to map their matrix upon the environment in front of the vehicle. The microprocessor  3  controls the operation of the LEDs  4 . Its supports a full-beam operating mode, in which all LEDs  4  of the matrix spread their light widely across the carriageway and the environment, and a dipped-beam mode in which only LEDs  4  in an upper loosely hatched area  6  of the matrix are in operation, in order to illuminate the carriageway in front of the vehicle, but not to emit any upwardly directed light which could blind oncoming traffic. 
     The camera  2  continuously supplies pictures of the carriageway in front of the vehicle and the close environment to the microprocessor  3 .  FIG. 2  schematically shows such a picture with a carriageway  8  stretching in front of the vehicle and a person  9  standing by the side of the road. Due to the picture-reversing effect of the lens the LEDs of area  6  illuminate one half of the picture below the horizon, as symbolized by the hatched areas in  FIG. 1  and  FIG. 2  corresponding with each other, i.e., they generate a dipped-beam  10  with an upper cut-off line  11  which in the representation in  FIG. 2  extends just below the horizon. 
     The microprocessor  3  applies to the pictures supplied by the camera  2  a picture analysis process that is known as such and will therefore not be described in any detail, in order to identify potentially safety-relevant objects on or near the carriageway, in particular objects without their own light source which can easily be overlooked by the driver of the vehicle. When such an object is identified, the microprocessor  3  also decides whether the identified object is a person  9  or not. If it is decided that the object is not a person, the microprocessor  3  selects a small group of LEDs, marked  4 ′ and  4 ″, from the area  7  of the matrix normally switched-off in dipped-beam mode, which are positioned in the matrix in such a way that they are mapped by the lens  5  onto the identified object. If these LEDs  4 ′ and  4 ″ are switched on, they generate a marker light beam  12 , with which the identified object, depending upon size, is fully or at least for a large part, illuminated. When the identified object suddenly lights up, the driver&#39;s attention is drawn to it enabling him/her to identify and, if necessary, maneuver it in such a way as to avoid a danger created by the object. 
     If the microprocessor  3  decides that the identified object is a person  9 , the LEDs furthest away from the area  6 , i.e., those  4 ″ LEDs of the LEDs  4 ′ and  4 ″ which, if they were switched on, would hit the head of the person, remain switched off. Thus a marker light beam  13  of reduced cross-section is obtained the upper cut-off line  14  of which passes over the body of the identified person so that the legs and possibly the abdomen is illuminated, but the head of the person  9  remains in the dark. 
       FIG. 3  is a schematic illustration of a front headlight  15  according to a second embodiment. This front headlight comprises a single light source such as a halogen lamp  16 , a reflector  17  that bundles the light of the halogen lamp  16  to form a forward facing beam, a lens  5  and a plurality of apertures  18 ,  19 ,  20  movably arranged between the lamp  16  and the lens  5 . Motors driving the movement of the apertures  18 ,  19 ,  20  are not shown in the figure. They are subject to the control by a microprocessor  3  not shown in the figure, which as described with reference to  FIG. 1 , receives pictures of the environment of the camera  2 , in order to identify, as required, safety-relevant objects in these pictures and to decide whether the objects are persons or not. 
     The lamp  16 , the reflector  17 , the lens  5  and the motors of the apertures  18 ,  19 ,  20  are mounted in a frame not shown in  FIG. 2  for reasons of clarity and thus form an assembly  21  that with respect to the built-in frame fixed to the vehicle, schematically shown here as ring  22 , is azimuthally pivotable about an axis  23 . A further motor that drives the pivotal movement of the assembly  21  about axis  23  is also controlled by the microprocessor  3 . 
     In the position shown in  FIG. 2  the aperture  18  covers the lower half of the reflector  17 . Light which passes above the aperture  18  is deflected by the lens  5  obliquely downwards in direction of the carriageway, thus, as shown in the illustration in  FIG. 2 , forming the dipped-beam  10 , the cut-off line  11  of which is defined here by an upper edge  24  of the aperture  18 . A notch  25  at the edge  24  is covered in the configuration of  FIG. 2  by an aperture  20  rotatable about an axis  26 . The aperture  20  comprises three circle segments  27 ,  28 ,  29  with different radii. The circle segment  27  facing upwards in the configuration of  FIG. 2  is the segment with the largest radius. If the circle segment  28  with the smallest radius is rotated upwards, the aperture  20  exposes the notch  25 ; if the circle segment  29  with the medium radius is rotated upwards, the notch  25  is partially covered. The aperture  19  is a circular disc also rotatable about axis  26 , into which notches  30  are cut over a part of its circumference. 
     When the microprocessor  3  identifies an object to be marked that is potentially safety-relevant, it initially controls the motor of assembly  21  in order to align the optical axis  31  with the object. Depending on whether the object has been identified as a person or not, the microprocessor controls a motor of the aperture  20  in order to position the segment  29  or  28  in front of the notch  25 . If subsequently the aperture  19  is rotated once about axis  26 , the identified object is hit by the marker light beam as often as corresponds to the number of notches  30  of aperture  19 . As with the construction shown in  FIG. 1 , the marker light beam can be emitted in a spatial angle not illuminated by the dipped beam. The circle segment, which is positioned in front of the notch  25 , i.e., circle segment  28  or circle segment  29 , determines whether it is the marker light beam  12  or the marker light beam  13  that is generated with a cut-off line  14  below head height of the marked person. 
       FIG. 4  shows a variation of the design of  FIG. 3  in which the rotatable aperture  20  is replaced by a platelet-shaped aperture  32  that is essentially vertically movable by pivoting it about a laterally offset axis  33 .  FIG. 4   a  shows the apertures  18 ,  19 ,  32  of this variation in a frontal view along optical axis  31 . The aperture  32  is movable between the positions shown in  FIG. 4   a , in which it covers a lower area of the notch  25 , and a lowered position, in which it completely exposes the notch  25 . In the lowered position of the aperture  32  the light passing through the notch  25  results, in the open space in front of the front headlight, in the marker light beam  12  the vertical extension of which would suffice to illuminate a person from head to toe on the edge of the carriageway. If, however, the microprocessor  3  records such a person  9  it positions the aperture  32  in the indicated position, in which it omits the head of the person and in which the height-reduced marker light beam  13  which is generated. 
     In the design of  FIG. 4  and  FIG. 5   a  the aperture  32  is wider than the notch  25  so that it completely covers the latter in its lower area. As can be seen in  FIG. 5   b  or  FIG. 5   c , the aperture  32  may also be tapered or be narrower than the notch  25 , so that light is still allowed to pass laterally of the aperture  32 , but the head of a person which is aligned with the optical axis  31  of the headlight, remains in shadow. As long the microprocessor  3  does not recognize an object to be marked in the environment of the vehicle, the aperture  19  is turned such that a portion of its circumference which is free of notches  30  covers the notch  25  so that no marker light beam is generated. 
       FIG. 6  shows a front headlight  15  according to a further embodiment in a schematic frontal view along the optical axis  31 . The halogen lamp  16  and the reflector  17  are the same as in  FIG. 2  and  FIG. 3 , and also the picture-inverting lens  5  are present and are connected with the lamp  16  via a pivotably suspended frame and the front headlight  1 , forming the assembly. Two apertures  34 ,  35  are pivotably mounted between the lamp  16  and the lens  5  about an axis  36  fixed to the frame. In both apertures  34 ,  35  a slot-shaped motion link  37 ,  38  is cut out, through which a cam  39  extends. The cam  39  is supported by an arm  40  which in turn can be driven by the motor about a further axis  41  fixed to the frame in order to perform pivotal movements. 
     One of the two apertures, here the aperture  34  facing the observer comprises a notch  25  on its upper edge. The other aperture  35  comprises an essentially straight upper edge and in the configuration shown in  FIG. 5 , covers a part of the notch  25  so that the light that passes through the part of the notch  25  that has remained open forms the marker light beam  13  that is suitable for marking persons. 
     The motion link  37  of the front aperture  34  comprises a concentric portion  42  with regard to axis  41  and a portion  43  extending away from axis  41 . In the configuration of  FIG. 2  the cam  39  is in a central position of the concentric portion  42  so that when the arm  40  performs a pivotal movement in which the cam  39  does not leave the portion  42 , the aperture  34  remains immovable. 
     The motion link  38  of the rear aperture  35  comprises two concentric portions  44 ,  45  for different radii and a portion  46  connecting the concentric portions. In  FIG. 2  the cam  39  is in this portion  46 . When the arm  40  pivots anti-clockwise from the shown position, the aperture  35  is moved upwards until it completely covers the notch  25 . In this position no marker light beam is generated. Hence the normal position, in which the cam  39  remains so long as no object to be marked is recorded, is the left end of the motion links  37 ,  38 . When the microprocessor records a person to be marked, the arm  40  pivots once or twice for a short time from the normal position into the position shown in  FIG. 2 , as indicated by arrow  47 . As long as it stays in the position of  FIG. 6 , the marker light beam  13  generated is the beam which is suitable for marking the person  9  and which omits the head of that person. 
     If, however, the object to be marked is not a person, the pivot arm  40  is driven out of the normal position to perform a more extensive pivotal movement, beyond the configuration shown in  FIG. 6  and across the entire extension of the concentric portion  42 , as symbolized by arrow  48 . In this scenario, when the cam  39  reaches the concentric portion  45  of the motion link  38 , the aperture  35  has been folded down to such an extent that it fully exposes the notch  25 . If, however, the arm  40  is pivoted further in clockwise direction so that its cam  39  arrives at portion  43 , then the aperture  34  too pivots downwards that corresponds to the headlight being switched over to a full-beam characteristic. 
     While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.