Abstract:
A method and tail light for controlling optical modules of the tail light, comprising the steps of 
     activating one or more optical modules to generate a first signaling function, 
     if the vehicle has reverse gear engaged, activating, according to a first mode of operation, one or more other optical modules to generate a second signaling function, 
     if the vehicle does not have reverse gear engaged, activating the or at least one of the other optical modules to generate a complementary beam of light distinct from the beam of light that it emits in the first mode of operation and that supplements the first signaling function. 
     The invention also relates to a tail light, notably for implementing this method.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to the French application 1550305 filed Jan. 15, 2015, which application is incorporated herein by reference and made a part hereof. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the field of motor vehicle tail lights, notably to tail lights with several optical modules generating beams of light and to methods for managing these optical modules. 
         [0004]    2. Description of the Related Art 
         [0005]    U.S. Patent Publication 2014/0160779 discloses a vehicle tail light in which a part of the light performs a stop light function, or indicates that the vehicle is braking, whatever the mode of operation of the tail light, and, underneath, a part which, according to two modes of operation, acts as a position light or as a turn indicator. 
         [0006]    However, such a tail light occupies a certain amount of space. This is because the various parts thereof comprise at least as many different optical modules, such as light guides associated with light-emitting diodes, as there are signaling functions to be performed. Also, the part that generates the stop light needs to be powerful enough and have enough of an illuminating surface area that it can be seen, this also adding an additional constraint on space. 
       SUMMARY OF THE INVENTION 
       [0007]    The technical problem that the invention seeks to solve is therefore that of reducing the size of a vehicle tail light while at the same time allowing it to perform its various signaling functions in accordance with the regulations. 
         [0008]    To this end, a first subject of the invention is a method for controlling optical modules of a tail light of a vehicle, the method comprising the following steps: 
         [0009]    activating a first set of one or more optical modules, the first set generating a first signaling function, 
         [0010]    if the vehicle has reverse gear engaged, activating, according to a first mode of operation, a second set of one or more optical modules, so that the second set generates a second signaling function distinct from the first signaling function, 
         [0011]    if the vehicle does not have reverse gear engaged, activating, according to a second mode of operation, the or at least one of the optical modules of the second set, so that this optical module, referred to as a dual-function optical module, generates a complementary beam of light distinct from the beam of light it emits in the first mode of operation, this distinct complementary beam of light supplementing the first signaling function. 
         [0012]    This method follows the opposite course of action to the solutions conventionally employed. Specifically, in tail lights of the prior art, certain signaling functions, notably the rear position light function or the stop light function, are always implemented with their power constantly maximized, in the case of the stop light, with the power maximized for a given braking intensity. 
         [0013]    Now, the applicant company has noticed that in the case of these signaling functions, notably the tail position light function or the stop light function, it was possible to have a lower intensity of light when the vehicle was reversing than when the vehicle was moving forward. This is because a vehicle reverses under maneuvering situations or at least in places where the speed is not as high. By contrast, when the vehicle is traveling forward, it is far more likely to be driving in an area in which automotive traffic is traveling at high speed, particularly on an expressway. Thus, when the vehicle is moving forward, its signaling functions need to be visible from further away than when it is reversing. 
         [0014]    As a result, the applicant company has selected a method using an optical module able to generate two different beams of light, hereinafter referred to as a dual-function optical module. According to this method, when the vehicle is reversing, or has engaged reverse gear, this dual-function optical module by itself performs or participates in a second signaling function, the first signaling function always being active or able to be activated by the first set of optical modules. When the vehicle is moving forward, or is in a forward gear, this dual-function optical module generates another beam referred to as the complementary beam of light, which supplements the first function, notably by enhancing it and/or increasing the aperture angle thereof, thus allowing the first signaling function to be seen from a greater distance. 
         [0015]    The method according to the invention therefore makes it possible to gain compactness because one and the same module is used in two different functions, while at the same time maintaining satisfactory performance. 
         [0016]    It should be noted that the first mode is implemented if the vehicle is reversing or if the vehicle has reverse gear engaged. The expression “the vehicle has reverse gear engaged” or “the vehicle is in reverse gear” means a configuration or a state of the vehicle that renders it able to reverse, for example when the gearshift lever is in a reverse gear position. The vehicle may actually be stationary, even though reverse gear is engaged, with the vehicle ready to reverse. This vehicle is therefore in a situation in which traffic speeds are as limited as they would be in a situation in which it were reversing. 
         [0017]    Likewise, the fact that the vehicle is in reverse gear can be used in a substep of the method that makes it possible to detect whether the vehicle is reversing or ready to reverse. 
         [0018]    Likewise, the second mode is implemented if the vehicle is moving forward or if the vehicle is in a forward gear. The expression “reverse gear is not engaged” or “the vehicle is in a forward gear” means a configuration or a state of the vehicle rendering it able to move forward, for example when the gearshift lever is in neutral or in a forward gear position. The fact that the vehicle is in a forward gear can be used in a substep of the method making it possible to detect whether the vehicle is moving forward or capable of moving forward. 
         [0019]    Within the context of this invention, the reversing light function will be classified as part of the signaling functions. 
         [0020]    The method according to the invention may optionally exhibit one or more of the following features: 
         [0021]    the first signaling function is a tail position light or a stop light; that makes it possible to enhance safety by making such functions visible from far away when the vehicle is likely to move forward; 
         [0022]    the first signaling function is a stop light, the step of activating the first set being implemented if the vehicle is braking; the method of the invention is all the more advantageous in terms of safety in the context of this stop light function; 
         [0023]    the second signaling function is a reversing light; since the reversing light is used only during or for the reversing of the vehicle, this reversing light is particularly suited to forming the second signaling function of the method according to the invention; 
         [0024]    the complementary beam of light is designed to enhance the light intensity of the first signaling function; this is a simple way of allowing the first signaling function, particularly a stop light, to be seen from far away; 
         [0025]    the complementary beam of light has a photometric distribution, the pattern of which is identical to that of the photometric distribution of the first function; the complementary beam of light thus has intensity ratios at various points of its photometric distribution that are identical to those of the first signaling function, thereby allowing the distribution of the light intensity of the beam of light generated by the first set of optical modules to be enhanced while at the same time maintaining the light intensity ratios at various points in the photometric distribution thereof. 
         [0026]    Another subject of the invention is a vehicle tail light comprising: 
         [0027]    a first set of one or more optical modules, the optical module or modules being able to generate one or more beams of light, in such a way that the first set generates a first signaling function, 
         [0028]    a second set of one or more optical modules, the optical module or modules being able to generate one or more beams of light in such a way that the second set generates a second signaling function distinct from the first signaling function, 
         [0029]    the or at least one of the optical modules of the second set, referred to as dual-function optical module, is arranged in such a way as to be able to emit two distinct beams of light alternatively, the first beam of light creating or participating in the creation of the second signaling function, and the second complementary beam supplementing the first signaling function. 
         [0030]    This tail light is suited to implementing the method according to the invention. It therefore makes it possible to obtain the advantages of this method. 
         [0031]    The tail light according to the invention may optionally exhibit one or more of the following features: 
         [0032]    at least one of the optical modules comprises a light guide comprising at least one input diopter and at least one illuminating surface, the light guide being arranged in such a way as to be able to receive the rays of light emitted by a light source through this input diopter and guide these rays as far as this illuminating surface, whence these rays exit to generate alone or participate in the generation of the first signaling function or the second signaling function; this makes it possible to achieve different arrangements of other systems for directing the rays of light, such as, for example reflectors; the light guides can be coupled to light-emitting diodes, commonly referred to as LEDs; LEDs are particularly suited to being controlled by a method; 
         [0033]    the dual-function optical module comprises a light guide comprising two input diopters distant from one another and an illuminating surface, notably a single illuminating surface, this light guide, referred to as a dual-input light guide, being arranged in such a way that:
       one of the input diopters, referred to as the first input diopter, can receive the light from a light source through this input diopter,   the other of the input diopters, referred to as the second input diopter, can receive the light from another light source through this second input diopter,   it guides the light coming from its input diopters as far as the illuminating surface, whence this light will exit to generate or participate in the generation of the second signaling function or to supplement the first signaling function;       
 
         [0037]    this is a simple way of embodying a dual-function optical module with a light guide; control of the dual-function optical module is also simplified because all that is required is action or nonaction on the power supply to the light source corresponding to the mode of operation to be implemented in the method according to the invention; 
         [0038]    the dual-function optical module comprises the two light sources of different intensities and/or different colors, one of the light sources being arranged so as to emit through the first input diopter of the dual-input light guide, the other of the light sources being arranged to emit through the second input diopter of the dual-input light guide; this is a simple way of embodying different beams of light for the first signaling function and for the second signaling function, notably when these functions require different intensities and/or different colors; 
         [0039]    the light sources from which the dual-input light guide receives the light are the photoemissive elements of distinct light-emitting diodes; LEDs are particularly well suited to being powered alternatively and therefore for being controlled by the method according to the invention; 
         [0040]    the dual-function optical module comprises:
       a light guide comprising an input diopter, notably an input diopter common to or separate from the two light sources, and an illuminating surface, notably a single illuminating surface,   two light sources arranged to emit through the input diopter, the light sources having different intensities and/or different colors,   the light guide being arranged to guide the light coming from its input diopter as far as this illuminating surface, whence this light will exit to generate or participate in the generation of the second signaling function or to supplement the first signaling function;       
 
         [0044]    that allows the light guide to be embodied in a simpler way by having an input diopter common to the two light sources; according to one exemplary embodiment the light sources of the dual-function module are the photoemissive elements of one and the same light-emitting diode or of distinct light-emitting diodes; that allows the common input diopter to be embodied in a simpler way; this type of LED is known as a two-chip LED or a multichip LED, the chips corresponding to the photoemissive elements; in this case, these chips may be controlled autonomously; 
         [0045]    one of the light sources of the dual-function optical module is able to emit red light and the other of the light sources of the dual-function optical module is able to emit white light; that allows a first function to be supplemented with red light, such as a stop function or a tail position light function, and a second function to be supplemented with white light, such as a reversing light; 
         [0046]    the optical module or modules of the first set comprise light sources able to emit red light, so that the light emitted by the first set is red; that allows a first function to be performed using red light, such as a stop function or a tail position light function; 
         [0047]    it comprises a control module controlling the light sources of the dual-function optical module, the control module being able to activate one of the light sources when the vehicle does not have reverse gear engaged and able to activate the other of the light sources when the vehicle is reversing and/or is in reverse gear; the device thus itself comprises elements for controlling the tail light in order to implement the method according to the invention; the control module may for example be integrated onto the electronic board that controls the light sources, notably the LEDs; information regarding the state of the vehicle may come from the vehicle itself, notably from sensors, the tail light comprising means for receiving signals containing this information. 
         [0048]    Thus, according to one embodiment, the method of the invention is implemented for controlling the optical modules of a tail light according to the invention. 
         [0049]    In the method according to the invention, or in the tail light according to the invention, the first function may be a stop light or a tail position light, more particularly a stop light, and the second function may be a reversing light. 
         [0050]    These and other objects and advantages of the invention will be apparent from the following description, the accompanying drawings and the appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS 
         [0051]    Further features and advantages of the invention will become apparent from reading the detailed description of the nonlimiting examples that follow, for the understanding of which reference will be made to the attached drawings, among which: 
           [0052]      FIG. 1  depicts a front view of a vehicle tail light according to the invention in a first mode of operation; 
           [0053]      FIG. 2  depicts a front view of the vehicle tail light of  FIG. 1  in a second mode of operation; 
           [0054]      FIG. 3  depicts optical modules of the tail light according to the invention, according to a first embodiment of the dual-function optical module; and 
           [0055]      FIG. 4  depicts a dual-function optical module of the tail light according to the invention, according to a second embodiment. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0056]      FIGS. 1 and 2  schematically illustrate a tail light  1  according to the invention in two modes of operation which are activated in accordance with the method according to the invention. 
         [0057]    This tail light  1  comprises a housing  4  closed by a transparent outer lens (not depicted) in front of optical modules  11 ,  12 ,  21 ,  22  of this tail light  1 .  FIGS. 1 and 2  are views from the front, which means that only the illuminating surfaces of these optical modules  11 ,  12 ,  21 ,  22  are depicted. 
         [0058]    The optical modules  11 ,  12 , at the top in this example, form a first set  10 . The optical modules  21 ,  22 , at the bottom in this example, form a second set  10 . 
         [0059]    This first set  10  and this second set  20  of optical modules  11 ,  12 ,  21 ,  22  may be separated for example by a mask or by other optical modules performing another function, such as the town beam function, here represented by three horizontal bars referenced  2 . 
         [0060]    The optical modules  11 ,  12  of the first set  10  are each able to generate a beam of light. The two beams of light obtained perform a first signaling function, such as a tail light position function or a stop light function. 
         [0061]    In the example described hereinafter the first function is a stop light, which will be activated when the vehicle brakes, whether this vehicle is moving forward or reversing and whether it is in a forward gear or in reverse gear. This stop light function is represented by the diagonal hatching in  FIGS. 1 and 2 . 
         [0062]    The optical modules  21 ,  22  of the second set  20 , hereinafter referred to as dual-function optical modules  21 ,  22 , are each able to generate two distinct beams of light, used according to the mode of operation of these dual-function optical modules  21 ,  22  and therefore according to the mode of the operation of the tail light  1 . 
         [0063]    In  FIG. 1 , the vehicle has reverse gear engaged. According to the method example illustrated, the dual-function optical modules  21 ,  22  are made to operate in a first mode of operation, during which the dual-function optical modules  21 ,  22  each generate a beam of light, the two beams formed performing a second signaling function, in this example a reversing light. This reversing light function is represented by the vertical hatching in  FIG. 1 . 
         [0064]    If, during the maneuver the vehicle brakes, the first set of optical modules  11 ,  12  will be able to emit a stop light function that is strong enough to be visible from a sufficient distance. In a parking lot, or in a side street, there is no need for this stop light to be seen from as far away as is required on a high-speed road. 
         [0065]    When a forward gear is engaged, for example when the vehicle is traveling on a high-speed road, this stop light needs to be visible from further away. 
         [0066]    Rather than adding additional modules devoted solely to providing additional power, the tail light  1  is produced in such a way that the optical modules  21 ,  22  of the second set  20  can generate beams of light different than those that they generate during the first mode of operation. 
         [0067]    Thus, when a forward gear is engaged, according to the method illustrated, the dual-function optical modules  21 ,  22  are operated in a second mode of operation in which they will be able to generate additional beams of light which supplement the stop light generated by the first set  10 , if the vehicle brakes. 
         [0068]    Note that in this example, all of the optical modules of the second set  20  are configured as dual-function optical modules  21 ,  22 . However, it would be possible to configure just one of them in this way. By creating the two optical modules as dual-function modules, the stop light function becomes visible from even further away. 
         [0069]    In this example, the additional beam of light of each of the dual-function optical modules  21 ,  22  has a photometric distribution, the pattern of which is identical to that of the photometric distribution of the first function. This then enhances the intensity while at the same time maintaining the pattern and distribution on the photometric grating of the stop light function before it is supplemented by the dual-function optical modules  21 ,  22 . 
         [0070]    However, according to some embodiments that have not been depicted, the two dual-function optical modules  21 ,  22  may be configured in such a way as to enlarge the illuminating surface or even the angle of opening of the overall beam of light that performs this stop light function. It is also possible to have a dual-function optical module configured to operate according to one of the modes that have not been depicted and another dual-function optical module configured to operate according to the mode illustrated, notably as described in the paragraph above. 
         [0071]      FIG. 3  illustrates an exemplary embodiment of the optical modules  11 ,  12 ,  21 ,  22  of the tail light of  FIGS. 1 and 2 . Only one optical module  11 ,  21  per set has been depicted. The description that follows can be read across to the other optical modules hereinabove referenced  12 ,  22 . Each of the optical modules  11 ,  12  comprises a light guide  19 ,  29 . Each of these light guides  19 ,  29  comprises an input diopter  14 ,  24 , facing which there is a light-emitting diode  17 ,  27  (hereinafter referred to as LED) so that it emits its rays of light toward the corresponding input diopter  14 ,  24 . These rays will then pass through the corresponding input diopter  14 ,  24  then be guided, notably by internal reflection, for example total internal reflection, inside the corresponding light guide  19 ,  29  off the faces of this light guide, as far as a terminal output diopter that forms the illuminating surface  15 ,  25  of this light guide  19 ,  29 . These illuminating surfaces  15  and  25  are the visible image of the optical modules  11  and  21  illustrated respectively in  FIGS. 1 and 2 . 
         [0072]    It will be noted that, in this example, these light guides  19 ,  29  are in the form of parallelepipedal sheets, the illuminating surfaces  15 ,  25  thereof visible from the front in  FIGS. 1 and 2  being rectangular. Nevertheless, other shapes are possible. 
         [0073]    Each LED  17  associated with a light guide  19  of one of the optical modules  11  or  12  of the first set  10  comprises a substrate  16  and a photoemitting element  31  mounted on this substrate facing the input diopter  14 . This photoemitting element  31  is designed and configured to emit red light when subjected to electrical current. The substrate  16  is itself mounted on an electronic control board  18  of the LED  17 . When the electronic control board  18  is supplying current to the photoemitting element  31 , the latter emits rays of light that are red in color. The configuration of the light guide  19  will guide and deflect these rays in such a way that when they emerge, the rays emitted from the illuminating surfaces  15  of the light guides  11  or  12  of the first set  10  form a stop light. 
         [0074]    Each LED  27  associated with a light guide  29  of one of the optical modules  21 ,  22  of the second set  20  comprises a substrate  26  and two photoemitting elements  32 ,  33  mounted on this substrate  26  and facing the input diopter  24  of this light guide  29 . A first,  32 , of these photoemitting elements is designed and configured to emit white light when subjected to an electrical current. A second,  33 , of these photoemitting elements is designed and configured to emit red light when subjected to an electrical current. These two photoemitting elements  32  and  33  are mounted on one and the same substrate  26  such that the LED can be qualified as a two-chip LED. Alternatively, there may be two LEDs, each one mounted on its own substrate and positioned side by side. In both instances, the light source will hereinafter be referred to as a dual-function LED. The substrate  26  is itself mounted on an electronic control board  28  of the dual-function LED  27 . 
         [0075]    The electronic control board  28  for this dual-function LED  27  is connected to a control module  30  which, according to information signals received by the vehicle, determines how to illuminate the optical modules  21 ,  22  according to whether the vehicle is in a forward gear or in reverse gear. 
         [0076]    If the vehicle is in reverse gear, the control module  30  transmits the instruction to activate the first photoemitting element  32  of the dual-function LED  27 . The electronic control board  28  for this dual-function LED  27  then supplies current to the first photoemitting element  32  which then emits rays of light that are white in color. The configuration of the light guide  29  will guide and deflect these rays in such a way that on emerging, the rays emitted from the illuminating surfaces  25  of the light guides  29  of the second set  20  form a regulation reversing light. 
         [0077]    The control module  30  is also connected to the electronic control board  18  for each LED  17  of the first set  10 . In the event of braking, this control module  30  will send the braking instruction to this electronic control board  18  of the first set  10 . This electronic control board  18  will then power the photoemitting element  31  and the first set  10  will generate a regulation stop function. The second set  20  will nevertheless continue to generate a reversing light function. 
         [0078]    If the vehicle is in a forward gear, the control module  30  places itself in the second mode of operation. If, during this second mode of operation, the vehicle brakes, in addition to transmitting the braking instruction to the electronic control board  18  for the first set  10 , the control module  30  transmits the instruction to activate the second photoemitting element  33  of the dual-function LED  27 . The electronic control board  28  for this dual-function LED  27  then supplies current to the second photoemitting element  33  which then emits rays of light that are red in color. The configuration of the light guide  29  will guide and deflect these red rays in such a way that on exiting the rays emitted from the illuminating surfaces  25  of the light guides  29  of the second set  20  combine with the rays of light emitted by the illuminating surfaces  15  of the first set  10  and therewith form what is referred to as an enhanced-intensity stop light. This stop light will thus be more powerful than when the tail light is in the first mode of operation, and will therefore be visible from further away, something which becomes advantageous when traveling at high speed, notably on an expressway. 
         [0079]    This tail light and the method according to the invention have therefore made it possible, when in a forward gear, to make use of the optical modules used to signal that the vehicle is reversing when reverse gear is engaged. This tail light and this method therefore make it possible to increase the power of the stop light signal without further cluttering the tail light with additional modules. 
         [0080]    The control module  30  may determine whether the vehicle is in reverse gear or in a forward gear using sensors at the gearshift lever or using instructions it receives when reverse gear or forward gear is engaged. 
         [0081]    The optical modules of the second set  20  may also be produced according to an embodiment illustrated in  FIG. 4 . The optical modules  11 ,  12  of the first set  10  remain identical to those illustrated in  FIG. 3  and are therefore not depicted in  FIG. 4 . 
         [0082]    As illustrated in  FIG. 4 , the light guide  129  of each second optical module  121  comprises a first input diopter  124   a  and a second input diopter  124   b,  these respectively being borne by a first branch  129   a  and a second branch  129   b  of the light guide  129 . These two branches  129   a,    129   b  meet in a common trunk  129   c,  which bears the output diopter that forms the illuminating surface  125  of the light guide  129 . 
         [0083]    This first and this second input diopter  124   a  and  124   b  are therefore distant and distinct from one other. An LED is arranged facing each of them, namely a first LED  127   a  facing the first input diopter  124   a  and a second LED  127   b  facing the second input diopter  124   b.    
         [0084]    Each of these LEDs  127   a,    127   b  comprises a photoemitting element mounted on a corresponding substrate  116 ,  126 . 
         [0085]    The photoemitting element  132  of this first LED  127   a  is designed and configured to emit white light when subjected to an electrical current. The photoemitting element  133  of this second LED  127   b  is designed and configured to emit red light when subjected to an electrical current. 
         [0086]    The substrates  116 ,  126  of these two LEDs  127   a,    127   b  are mounted on one and the same electronic control board  128 . The latter is connected to a control module  130 , itself connected to the electronic control board or boards  18  for the optical modules  11 ,  12  of the first set  10 . 
         [0087]    In the event of braking, this control module  130  will send the braking instruction to this electronic control board  18  of the first set  10 , as described hereinabove in respect of  FIG. 3   
         [0088]    In the embodiment of  FIG. 4 , if the vehicle is in reverse gear, the control module  130  transmits the instruction to activate the first LED  127   a.  The electronic control board  128  therefore supplies current to the first LED  127   a.  The photoemitting element  132  of this first LED  127   a  therefore emits rays of light that are white in color, through the first input diopter  124   a.  The configuration of the light guide  129  will guide and deflect these rays along the first branch  129   a  thereof, then along the trunk  129   c  thereof, as far as the output diopter from which they will exit. The light guide  129  is configured in such a way that the white rays emerging from the illuminating surfaces  25  of the light guides  21 ,  22  of the second set  20  form a reversing light. 
         [0089]    As in the embodiment of  FIG. 3 , the control module  130  will be able to control the first set  10  in order to generate the stop light, while at the same time allowing the second set  20  in parallel to generate a reversing light function 
         [0090]    In the embodiment of  FIG. 4 , if the vehicle is in a forward gear, the control module  130  places itself in the second mode of operation. If, during this second mode of operation, the vehicle brakes, in addition to transmitting the braking instruction to the electronic control board  18  to power the LEDs  17 ,  27  of the optical modules  11 ,  12  of the first set  10 , the control module  130  transmits the instruction to activate the photoemitting element  133  of the second LED  127   b  of the optical modules  121  of the second set  20 . The electronic control board  128  of this second LED  127   b  therefore supplies current to its photoemitting element  133  and the latter therefore emits rays of light that are red in color. The configuration of the light guide  129  will guide and deflect these red rays along the second branch  129   b  thereof, then along the trunk  129   c  thereof, as far as the output diopter from which the rays will emerge. The light guide  129  is configured in such a way that the illuminating surfaces  25  of the light guides  21 ,  22  of the second set  20  therefore form a stop light with the rays of light emitted by the illuminating surfaces  15  of the first set  10 . 
         [0091]    While the system, apparatus, process and method herein described constitute preferred embodiments of this invention, it is to be understood that the invention is not limited to this precise system, apparatus, process and method, and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.