Patent Publication Number: US-2020300434-A1

Title: Lighting unit for a light device of a motor vehicle and a light device with the lighting unit

Description:
RELATED APPLICATIONS 
     This application claims the priority benefit of Czech Patent Application Serial No. PV 2019-176 entitled “A lighting unit for a light device of a motor vehicle and a light device with the lighting unit,” filed Mar. 22, 2019, the entire disclosure of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The invention relates to a lighting unit for a light device of a motor vehicle and a light device with the lighting unit. 
     BACKGROUND INFORMATION 
     New vehicle lighting systems do not only focus on the optical output increasing the driving comfort and traffic safety, but it is also the appearance that is important for modern light devices of motor vehicles as headlights or signal lamps of a motor vehicle. Modern point and planar light sources, especially LED and OLED sources, have opened a new chapter for new stylistic options of car designers. 
     Using a planar light source, especially OLED—Organic Light Emitting Diodes—brings not only an extension of designer possibilities of the emitted light function, but it is also characterized by certain technical benefits including e.g. compact installation dimensions, low heat production, low energy consumption etc. Unfortunately, there are still some limitations of the OLED technology preventing widespread deployment of this technology in the serial production of car lighting. E.g. service life, penetration of moisture, low luminance for power functions, limitation to planar surfaces only and last, but not least, a high price. Another drawback of the OLED technology is the fact that a lamp of a motor vehicle must be adapted do detect an error status of the light source. With conventional LED&#39;s, this condition can be detected relatively well because in most cases, a short circuit or diode disconnection occurs, which results in a change of an electric quantity that can be relatively easily electronically detected. The situation of planar sources is more complicated because OLED&#39;s comprise organic layers that emit light after connection of electric voltage/current. 
     In the patent references U.S. Pat. Nos. 9,335,460, 7,651,241, 5,791,757, US20160356942, US20160349570, US20150331169, US20140268873, US20130033895, US20110249939, US20110170315, US20100309677, US20080186726, GB2537088, KR2008111786, there are many solutions that use a planarly shaped lighting unit equipped with an exit area for the output of light rays without using organic substances such as OLED. The disadvantage of the above-mentioned design solutions is that these lighting units are not intended to be used as external lighting equipment for motor vehicles, for which a variety of technical specifications and regulatory requirements must be followed and fulfilled. There is also a requirement for low manufacturing and assembly costs of such devices. For example, chemically cured cover glass that is used in the manufacturing process of screens is unsuitable for use as a cover glass of motor vehicle headlights as its manufacturing costs are too high. 
     To achieve the highest possible efficiency of light devices, efficient binding of light rays to light-guiding components must be ensured. Individual optical elements as a system of refractive and reflective surfaces and interfaces of optical environments must be arranged in such a way to prevent light losses to the highest possible extent, and at the same time to create an output light trace with the required light characteristic, i.e. the required light intensity and homogeneous appearance with constant luminance all over the exit surface. 
     Car lighting has certain specific features as it is not only the appearance and the total luminance of the lighting function that is concerned. Individual lighting functions must conform to locally valid legislative regulations (e.g. ECE, SAE, CCC etc.). Each function has different requirements for the minimal and maximal luminous intensity values at certain angles. This means that the purpose is not only to emit a certain amount of light from lighting elements. It is also necessary to emit light having certain luminous intensity at individual angles specified by the legislation. This luminous intensity is based on the minimum and maximum values in individual regulations for individual angles. A lighting function should be preferably designed in such a way to meet requirements of as many regulations as possible. So there is a certain overlap of the intervals of the specified minimum and maximum values for individual angles. In this case, a lamp or headlight can be used for more markets at the same time without changes. However, there are cases when the requirements of all regulations cannot be met with the use of a single design of a lighting function. In that case, the lighting function must be adapted to the requirements of individual markets, which results in a unique product for the particular market. 
     The requirements for the luminous intensity at individual angles are based on traffic safety requirements. This is because the primary task of signal lights is to make sure that a vehicle that emits a signal can be seen from angles that are critical for the particular function. All the signal functions (except the lateral ones) must emit light with the highest possible luminous intensity in the vehicle axis direction. The requirements for individual luminous intensity values at individual angles then decrease with the increasing angle of deflection from this axis. This decrease is gradual and does not approximate Lambert&#39;s distribution (cosine emitter). Thus, it is not desirable to strive to achieve this (Lambertian) distribution, which is close to the distribution that OLED lights or some displays work with. Concerning displays and TV screens, the aim is to ensure as constant luminance as possible from the widest possible viewing angles, which is a principal difference from the requirements for angular luminous intensities that light devices of motor vehicles, i.e. also the light device of a motor vehicle according to the present invention, are subject to. 
     As indicated above, fading at large viewing angles is rather considered as a defect in the case of displays and TV screens. On the other hand, signal lights of motor vehicles are subject to specifications what luminous intensities must be achieved at what angles to ensure safe visibility of a vehicle emitting a signal. In most cases, a light cone must be produced having the highest luminous intensity within the angle of +/−10° horizontally and +/−5° vertically from the longitudinal axis of the vehicle. Lower luminous intensities are then required up to the angles of +/−20° horizontally and +/−10° vertically from the vehicle axis. These angles are required for the main beam, the luminous intensity of the main beam being several times higher than the required luminous intensity at the other angles. At the other angles, visibility is the relevant parameter. I.e. a requirement for the signal to be visible from a large range of angles. E.g. for the stop function, visibility is required in the angular range of +/−45° horizontally and +/−15° vertically. However, for the tail light and the turn indicator function the visibility angle out of the vehicle has been extended up to 80°. With regard to the production tolerances it is then important to design the light function in such a way as to always meet the required luminous intensity value at the particular angle. Therefore, the minimal and maximal values are designed with a certain angular and value margin. This e.g. means that if a minimal luminous intensity is required up to a certain angle, the function is mostly designed in such a way for this minimal value to exceed the given angular direction by at least 1.5°. 
     The above-mentioned description implies that to efficiently meet the legislative regulations, the light must be directed specifically at individual angles. 
     Unlike displays and TV screens, in the automotive industry, the required shape of the output surface must further be considered. This is because in most cases, the use of a simple square or rectangular surface is not acceptable from a designer point of view. Today, the style of a car is a very important parameter and at the same time a limit for meeting technical and legislative requirements. Therefore, style must be combined with technological features to achieve the desired result. For this reason, within the design of the light-conductive core, the distribution and size of unbinding elements must be optimized. 
     The references CZ2017480 and CZ20180107 describe light devices for motor vehicles that comprise a panel-shaped shaped lighting unit with an exit area of light rays. The lighting unit is powered by spot light sources, in particular by LED, and it is equipped with optical elements to create signal light functions while the panel-shaped shaped lighting unit offers stylistic advantages comparable to the OLED technology. It is ensured that all technical specifications and legal requirements for use of lighting equipment in the automotive industry are fulfilled. The light device comprises a light-conductive core from an optically transparent material with an associated light unit situated against the entry area of the light-conductive core. The lighting unit further comprises a functional layer arranged between the light-conductive core and the translucent cover and configured to focus the beams of light rays that exit its surface averted from the light-conductive core in a predetermined direction, and a technological layer (situated in contact with the top surface of the light-conductive core and configured for total reflection of light rays). The lighting unit further comprises separators situated on the top surface of the light conductive core to delimit the required thickness of the technological layer. A disadvantage of these designs is the fact that the light rays are diffused with a relatively large lateral dispersion. This assembly achieves a lateral dispersion for the required luminous intensity of approx. 60°. Within the dispersion region of 60°, an almost homogeneous distribution of light is achieved on the display area whereas in the field of automotive lighting equipment it is desirable to emit a large amount of light especially in the vehicle axis direction and to diffuse a certain amount of light. Another drawback of the above-mentioned designs is the entire structural arrangement of the optical parts, which does not enable their variable configuration based on designer requirements, e.g. if it is necessary to direct the light beam in a certain manner, or if a spatial shape of an optical element is to be achieved. 
     The object of the invention is to disclose a new design of a light device of a motor vehicle that comprises a panel-shaped lighting unit with an exit area of light rays that will offer designer advantages comparable to the OLED technology and at the same time ensure that all technical specifications and legal requirements for use of lighting equipment in the automotive industry are fulfilled at acceptable manufacturing costs. 
     SUMMARY OF THE INVENTION 
     The above-mentioned object of the invention is fulfilled by a lighting unit according to the invention, intended for a light device of a motor vehicle, comprising a light guide to lead light rays from at least one light source. The light guide comprises a front surface and an apposite rear surface. The front surface comprises exit areas for the output of light rays from the light guide and intermediate areas situated between the exit areas and configured for total reflection of light rays passing along the light guide. The lighting unit further includes a light assembly situated against the front surface of the light guide and comprising optical elements containing a bearing area through which the optical elements are connected with the opposite exit areas directly or indirectly in such a way that between the exit areas and bearing areas transitional layers are arranged. The optical elements are configured to bind light rays falling onto the exit areas and to emit them from the exit surface of the optical elements, averted from the light guide, in a predetermined direction or directions. 
     In one of preferred embodiments, the rear surface of the light guide is smooth and without unbinding elements so that the light guide is virtually configured for the exit of light rays out of the light guide through the exit areas only. 
     In another one of preferred embodiments, the rear surface of the light guide is fitted with unbinding elements configured to direct light rays towards the exit areas and/or intermediate areas and to ensure their exit through the exit areas and/or intermediate areas out of the light guide. 
     The light assembly may preferably comprise a carrier carrying optical elements. 
     In another one of preferred embodiments, the optical element comprises a functional element and an emitting element, which are directly or indirectly connected to each other, the functional element comprising a bearing area and at least one reflective area to reflect light rays that have left the light guide through the exit area and entered the functional element through the bearing area, and to direct them to the emitting element comprising an exit surface for the exit of light rays out of the functional element. 
     In another one of preferred embodiments, the functional elements protrude from the rear surface of the carrier facing the front surface of the light guide and the emitting elements protrude from the front surface of the carrier averted from the front surface of the light guide. 
     The optical elements may preferably be integral bodies embedded in the carrier. 
     In another one of preferred embodiment, the functional elements and the emitting elements are separated from each other by the carrier. 
     The said transitional layers may preferably be part of a monolithic layer. 
     In one of preferred embodiments, the light guide is longitudinally shaped or panel-shaped. The carrier may be advantageously panel-shaped or longitudinally shaped as well. 
     In another one of preferred embodiments, the emitting elements have the form of ball-shaped lenses with a convex shape of the exit area and the functional element has the shape of a truncated cone whose base is the bearing area. 
     In another one of preferred embodiments, the emitting elements have an elongated shape, especially the shape of cylindrical lenses. 
     In another one of preferred embodiments, at least two of the emitting elements differ from each other with their shape and/or size. 
     In another one of preferred embodiments, the lighting unit includes a filter located behind the light guide to influence the color background when the lighting unit is viewed in its inactive state. 
     In another one of preferred embodiments, the lighting unit comprises a filter, especially homogenizer adapted for homogenization—diffusion of light rays, the filter being situated at a distance in front of the optical assembly and comprising a superficial or internal volume structure to influence the flow direction of the light rays, or the filter being colored or metal-plated in a semi-permeable way. 
     The thickness of the lighting unit is preferably from 0.1 mm to 14 mm. 
     The invention also relates to a light device comprising the lighting unit described above, situated to emit light rays from the exit areas of the optical elements out of the light device. 
     The light device may advantageously comprise multiple lighting units to serve one or more light functions of the light device. 
    
    
     
       CLARIFICATION OF DRAWINGS 
       The present invention will be further clarified in more detail with the use of its embodiment examples referring to the enclosed drawings wherein: 
         FIG. 1  shows a side view of the first embodiment example of the lighting unit according to the invention with a schematic representation of the route of light rays, 
         FIG. 2  shows a detail of an embodiment of an optical element, 
         FIGS. 3A, 3B, 3C, 3D, 3E, and 4A  show embodiment examples of the optical elements carried by the carrier in a front view, 
         FIG. 4B  shows cross-section A-A′ of the optical element shown in  FIG. 4   a,    
         FIG. 5  shows a side view of another embodiment example of the lighting unit, 
         FIG. 6  shows a side view of another embodiment example of the lighting unit, 
         FIG. 7A  shows a side view of another embodiment example of the lighting unit, 
         FIG. 7B  shows a side view of another embodiment example of the lighting unit, 
         FIG. 8  shows a side view of another embodiment example of the lighting unit, 
         FIG. 9  shows a top view of another embodiment example of a light device of a motor vehicle according to the invention, 
         FIG. 10  shows a side view of another embodiment example of the lighting unit, 
         FIG. 11  shows a side view of another embodiment example of the lighting unit, 
         FIG. 12  shows a side view of another embodiment example of the lighting unit, 
         FIG. 13A  shows a side view of another embodiment example of the lighting unit, 
         FIG. 13B  shows a side view of another embodiment example of the lighting unit, 
         FIGS. 14A and 14B  show a cross-section of an optical element carried by the carrier of a motor vehicle with the lighting unit according to the invention, 
         FIG. 15A  shows a side view of another embodiment example of the lighting unit, 
         FIG. 15B  shows a side view of another embodiment example of the lighting unit, 
         FIG. 16  shows a front view of an embodiment example of a light device of a motor vehicle with the lighting unit according to the invention, and 
         FIG. 17  shows a front view of another example of the light device. 
     
    
    
     EXAMPLES OF EMBODIMENTS OF THE INVENTION 
       FIGS. 1 to 15   b  show embodiment examples of the lighting unit  3  according to the invention. 
     The lighting unit  3  comprises a light guide  15  made of an optically transparent material, with an associated light unit  7  comprising light sources  11  situated on a carrier  12 . The light guide  15  can e.g. be of a plate-like shape (a panel-shaped light guide) and have a constant or variable thickness, or be of an elongated shape (rod light guide), it may be straight, bent, undulated or spatially shaped. The light sources  11  are situated at the entry area  9  of the light guide  15  and are designed to emit light rays  10  into the light guide  15 . These light rays  10  pass along the light guide  15  using the total reflection principle, which occurs on the rear surface  18  and front surface  17  of the light guide  15  which form interfaces between the light guide  15  and the surroundings of the light guide  15  with a low refractive index with respect to the refractive index of the light guide  15  material, except the exit areas  30  designed specifically for the exit of light rays  10  out of the light guide  15  as described in detail below. The front surface  17  of the light guide  15  comprises exit areas  30  and intermediate areas  19  that separate the exit areas  30  from each other. 
     The rear surface  18  of the light guide  15  can be (see the embodiments of  FIGS. 13 a , 13 b , 15 b   ) fitted with unbinding elements  28  configured to direct light rays  10  in predetermined directions towards the front surface  17  of the light guide  15  to make the light rays  10  exit from the light guide  15 . In such a case, the light rays  10  can, by the effect of the unbinding elements  28 , also exit from the front surface  17  through the intermediate areas  19  (see  FIGS. 13 b  and 15 b   ), which are situated between the exit areas  30 . The unbinding elements  28  can be e.g. designed as a tooth-like structure. However, in the other presented embodiments, the rear surface of the light guide  15  does not comprise any unbinding elements and is smoother, and therefore light rays  10  virtually only exit from the front surface  17  of the light guide  15  through the exit areas  30 . 
     The lighting unit  3  further comprises an optical assembly  23  situated against at least a part of the front surface  17  of the light guide  15  in such a way that the optical assembly  23  virtually follows the shape of the opposite front surface  17 . The optical assembly  23  always comprises optical elements  26 . Each optical element  26  contains an emitting element  26   a  and a functional element  26   b.  The optical assembly  23  can further comprise a carrier  15  (it is the case of the embodiments shown in  FIGS. 1 to 14   b  and  15   b ) carrying the optical elements  26  in such a way that the emitting elements  26   a  protrude from the front surface  25   a  of the carrier  25  and the functional elements  26   b  protrude from the rear surface  25   b  of the carrier  25 . The invention also envisages embodiments wherein the optical assembly  23  does not comprise a carrier  25  (see  FIG. 15 a   ), and in such a case, the optical elements  26  are carried by the light guide  15 . 
     The emitting elements  26   a  and functional elements  26   b  are preferably arranged in mutual alignment opposite each other as in the case of the presented preferred embodiments. Each pair of an emitting element  26   a  and functional element  26   b  is part of one optical element  26 . However, the invention also envisages embodiments wherein the emitting element  26   a  and functional element  26   b  from which light rays  10  proceed to the emitting element  26   a  assigned to this functional element  26   b  are situated at a distance from each other, to which, however, the geometry and shape of these elements must be adapted, to achieve the desired propagation of light rays  10  from the functional element  26   b  to the emitting element  26   a.  In this case, the functional element  26   b  and the emitting element  26   a  assigned to it are considered as parts of one optical element  26 . 
     The said carrier  25  may be e.g. foil. 
     The optical element  26  comprising a functional element  26   b  and an emitting element  26   a  assigned to it can be an integral optical element  26  that is embedded in the carrier  25  as shown in  FIG. 14 a   , displaying a cross-section of the optical element  26 . However, such an embodiment is also possible wherein the emitting element  26   a  and the functional element  26   b  are two mutually separated parts included in the optical element  26  and attached to the carrier  25  as shown in  FIG. 14 b   . The functional element  26   b  comprises a bearing area  14  situated opposite the respective exit area  30  of the light guide  15 . 
     The shape of the functional elements  26   b  is configured to direct light rays  10  in predetermined directions to push the light rays  10  to the emitting elements  26   a  from where they are emitted out of the lighting unit  3 . The functional elements  26   b  are further configured to bind light rays  10  from the exit areas  30  through the bearing area  14  into the functional elements  26   b.  The emitting element  26   a  is configured to emit a beam or beams of light rays  10  in a predetermined direction of directions and/or in a predetermined angular range. The functional elements  26   b  and emitting elements  26   a  usually have a size on the order of nanometers, micrometers to millimeters, e.g. in the range from 10 μm to 2000 μm. 
     The optical elements  26  are attached directly or indirectly to the exit areas  30  of the light guide  15  with their bearing areas  14 . As direct attachment (see e.g.  FIG. 5 ) such a case is understood when the bearing area  14  of the functional element  26   b  directly bears on the exit area  30  of the light guide  15  and the bearing areas  14  and the exit areas  30  are connected to each other with a suitable technology that does not require any connecting material as e.g. an adhesive to be added between the bearing areas  14  and exit areas  30  to establish this connection. Such a technology may be e.g. vibration or laser welding or mechanical joining by sealing the functional elements  26   b  into the exit surface  30  of the light guide  15 . In other preferred embodiments (e.g. see  FIGS. 1, 6, 7 and 8 ), some material is added between the bearing areas  14  and the opposite exit areas  30 , e.g. optically clear adhesive or a transparent adhesive layer, this material forming a transitional layer  24  that must ensure indirect mutual connection of the bearing area  14  of the functional element  26   b  with the exit surface  30  on the one hand, and on the other hand, the material of the transitional layer  24  must ensure transmission of light rays  10  through the transitional layer  24  into the functional element  26   b.  Therefore, the technological layer  24  is preferably implemented as a layer with a refractive index approximating the refractive index of the light guide  15  and functional elements  26   a.  However, for the material of the transitional layer  24 , material with a different refractive index from the refractive index of the light guide  15  or the material of the functional element  26   b  can also be used while in this case additional refraction of light on individual interfaces, which occurs due to different refractive indexes, can be technologically used. 
     The transitional layer  24  can be of the same size and positionally aligned with the exit surface  30  and bearing area  14  so that the bearing area  14 , transitional layer  24  and exit area  30  are arranged on each other in a precise alignment (see e.g.  FIGS. 1 and 6 ); in other embodiments (see  FIGS. 7 and 8 ), however, the technological layer  24  may be integral with a monolithic layer  4 , preferably made of a single material. 
     The transitional layer  24  in the sense of this invention is a layer configured to eliminate the air gap between the exit surfaces  30  of the light guide  15  and the opposite bearing surfaces  14  of the functional elements  26 , as the purpose is to prevent total reflection of light rays  10  on their incidence on the exit surfaces  30 , and conversely to enable transition of these rays  10  through the transitional layers  24  into the functional elements  26   b.    
     Note that the production process of the light unit  3  preferably comprises the step of using a light guide  15  whose entire front surface  17  is adapted for total reflection of light rays  10  passing along the light guide, i.e. the front surface is completely uniform in this sense. Thus, before connection to the optical assembly  23 , the front surface  17  does not comprise any exit areas  30  because they will only be produced by attachment of the optical assembly  23  to the light guide  15 . The exit areas  30  are created because in places where the bearing areas  14  are attached to the front surface of the light guide  15 , either directly or via a transitional layer  24 , the surface of the light guide will no longer form an interface between materials with a significantly different refractive index, and therefore light rays  10  will (with no or small refraction depending on whether the refractive indexes of the material of the light guide  15  and transitional layer  24  or light guide  15  and the functional element  26   a  are the same or slightly different) transit from the light guide  15  into the functional elements  26   a.    
     In embodiments that comprise a carrier  25  (embodiments of  FIGS. 1 to 14   b ), a separate light guide  15  and a separate optical assembly  23  are first produced during their production, and then the light guide  15  is connected to the optical assembly  23  in the places of the bearing areas  14  of the optical elements  26 . 
       FIG. 2  shows a side view of a detail of an exemplary carrier  25  of the emitting element  26   a  and functional element  26   b,  which are carried by the carrier  25 . The emitting element  26   a,  functional element  26   b  and carrier  25  are made of an optically transparent material. The carrier  25  has its front surface  25   a,  which the emitting elements  26   a  and the rear surface  25   b  with the functional elements  26   b  protrude over. The functional element  26   b  shown has at least one reflective area  27  to reflect light rays  10  towards the emitting element  26   a  whose exit area  29  light rays  10  are emitted from in predetermined directions. The refractive indexes of the material of the functional element  26   b,  carrier  25  and emitting element  26   a  can be approximately equal while in such a case there will be minimal refraction of light rays  10  on the interface formed by the rear side  25   b  and the front side  26   a,  or materials with different refractive indexes can be selected, which will cause refraction on the said interfaces, which must be taken into account in the design of the geometrical shape of the elements  26   a  and  26   b  to achieve the predetermined emission characteristics of light rays  10  from the exit area  29 . As mentioned above, the optical element  26  comprising the functional element  26   b  and emitting element  26   a  can be an integral element made of the same material, i.e. an element where no interfaces are made, and in such a case, after the entry of light rays  10  into the optical element  26 , no refraction of light rays occurs inside the optical element  26 . 
       FIGS. 3A to 3E  and  FIG. 4A  show a front view of the carrier  25 , more particularly of its front surface  25   a,  and the emitting elements  26   a  protruding over the front surface  25   a.    
     The emitting elements  26   a  shown in  FIG. 3A  e.g. have the form of ball-shaped lenses with a convex shape of the exit area  29  protruding over the front surface  25   a  of the carrier  25 . The functional element  26   b  preferably has the shape of a truncated cone and the emitting element  26   a  preferably has the shape of a spherical cap—of the above-mentioned ball-shaped lens. 
     The emitting elements  26   a  shown in  FIG. 3B  are designed as cylindrical lenses, only influencing the route of light rays  10  on the plane perpendicular to the axis of this cylinder whereas on the plane delimited by the axis of the cylinder and the normal to the front surface  25   a  of the carrier  25 , the route of the rays  10  is intentionally not influenced (refraction on the optical interface is applied only). 
       FIG. 3C  shows emitting elements  26   a  whose shape is determined by spatially arranged surfaces. 
       FIG. 3D  shows emitting elements  26   a  of a linear shape. 
       FIG. 3E  shows emitting elements  26   a  that are mutually interconnected in such a way that they create the shape of a net or grid. 
       FIGS. 4A and 4B  show an example of emitting elements  26   a  whose exit area  29  is composed of spatially arranged partial areas. 
       FIG. 5  shows another embodiment example of the lighting unit  3  according to the invention wherein two emitting elements  26   a  arranged next to each other, e.g. lenses, differ with their shape and size, and the adjacent functional elements  26   b  are also different from each other, e.g. with the shape of the reflective areas  27 . 
       FIG. 6  shows another embodiment example of the lighting unit  3  according to the invention wherein behind a transparent light guide  15 , a filter  21  is situated influencing the color appearance/background when the lighting unit  3  is viewed in the inactive state. In a preferred embodiment, the filter  21  has a dark color, e.g. black. 
       FIG. 7A  shows another embodiment example of the lighting unit  3  according to the invention wherein on the front surface  17  of the light guide  15 , a layer  4  is situated that comprises transitional layers  24 . In front of the optical assembly  23 , a filter  20  is preferably situated, having a superficial or internal volume structure influencing the flow direction of light rays  10 . The filter  20  is separated from the optical assembly  23  with free space. The filter  20  may be e.g. a homogenizer adapted to homogenize—diffuse light rays  10 . The material of the filter  20  can be e.g. a milk material or another material with a superficial or internal structure influencing the direction of light rays  10 . Light rays  10  passing through the filter  20  and exiting from its exit surface  22  can be diffused in an isotropic or anisotropic way. The filter  20  may be adapted in such a way that it changes the wavelength of transmitted light or a semi-permeable mirror to achieve a mirror-like appearance. At least along a part of the perimeter of the lighting unit  3 , a connecting element  8  is situated, e.g. a frame of any color, preferably of milk color or non-transparent. Inside the lighting unit, a spacing element  13  may be situated to ensure the required distance of individual components, especially the filter  20  and optical assembly  23 . 
     As shown in  FIG. 7B , the function of the spacing element  13  may also be fulfilled by the optical element  26  with a specific height as well as design, which then fulfills both the optical function and the spacing function. 
       FIG. 8  shows another embodiment example of the lighting unit  3  according to the invention wherein at least a part of the surface of the emitting elements  26   a  and/or the front surface  25   a  of the carrier  25  is fitted with coating  5 , e.g. metal plating, color spray etc., which serves the function of a filter/homogenizer. In an alternative embodiment, the function of the filter/homogenizer is ensured by a microtexture/nanostructure obtained by mechanical treatment of the mold (graining), or degradation of the surface of the emitting element  26   a  and/or front surface  25   a  of the carrier  25 . 
       FIG. 9  shows another embodiment example of the lighting unit  3  according to the invention. In this case, the light guide  15  is undulated and to achieve that the beams of light rays  10  are sent in the required identical direction by individual optical elements  26 , the optical elements  26  of the optical assembly  23  have different geometrical shapes. 
       FIGS. 10 and 11  show another embodiment example of the lighting unit  3  according to the invention wherein the rear face  16  of the light guide  15  is adapted to reflect light rays  10 . 
       FIG. 12  shows another embodiment example of the lighting unit  3  according to the invention wherein the rear face  16  of the light guide  15  is adapted to absorb light rays  10 . 
       FIG. 13A  shows another embodiment example of the lighting unit  3  according to the invention wherein the rear surface  18  of the light guide  15  is fitted with unbinding elements  28  configured to direct light rays  10  in predetermined directions. 
       FIG. 13B  shows another embodiment example of the lighting unit  3  according to the invention wherein the rear surface  18  of the light guide  15  is fitted with unbinding elements  28  configured to direct light rays  10  towards the front surface  17  of the light guide  15  in such a way that the light rays  10  can exit out of the light guide  15 . Thus, the light rays  10  also exit, by the effect of the unbinding elements  28 , from the front surface  17  through the intermediate areas  19 , which are situated between the exit areas  30 . 
     The thickness of the lighting unit  3  is preferably from 0.1 mm to 14 mm. 
       FIG. 15A  shows the lighting unit  3  wherein the light guide  15  is configured as a carrier  25  carrying the optical elements  26  that comprise a bearing area  14  that the optical elements  26  indirectly bear on the exit areas  30  of the light guide  15  via a transitional layer  24  with. 
       FIGS. 16 and 17  show examples of using the lighting unit  3  according to the invention in a light device of a car. 
       FIG. 16  shows a front view of a light device comprising a housing  1  defining a chamber  2  wherein one lighting unit  3  is seated, positioned in such a way that the emitting elements  26   a  emit light rays  10  out of the light device. 
       FIG. 17  shows a light device comprising multiple lighting units  3 . The lighting units  3  can be arranged in the chamber  2  of a light device, especially a lamp, e.g. in such a way that some of the lighting units  3  will fulfill the requirements for the main beam and conversely, some of them will be designed to ensure visibility and/or to meet designer requirements. But at the same time, all the lighting units  3  of one lighting function must collectively meet the requirements of the legislative regulation for the particular function. Lighting units  3  can also be combined in such a way that one or more lighting units  3  are common for more lighting functions of the same color or more colors. E.g. a combination of the stop and tail function or the tail and turn indication function. Or a functional layer of one lighting unit can be designed in such a way to emit a part of the light to meet the requirement for visibility angles. 
     A relatively simplest configuration is such when the front surface  25   a  of the carrier  25  is situated approximately perpendicularly to the longitudinal axis of the vehicle and is approximately planar. However, this configuration is not always suitable for the style of the vehicle. Therefore, the optical assembly  23  or combination of optical assemblies  23  is adapted to redirect the main axis of the final light beam exiting from the optical assemblies  23 . If there is an additional requirement that the optical assemblies  23  should be shaped and curved on the basis of designer requirements, optical analyses should be carried out and their results used to optimize the optical assemblies  23  or individual optical elements  26  to meet the legislative requirements for the particular function. 
     At present, motor vehicles are equipped with signal lamps designed to emit various light beams. Such signal lamps can be integrated in the body as separate lighting elements or they can be an integral part of headlights and tail lights in the form of a partial lighting unit. 
     Such functions are considered as signal functions that do not directly illuminate the space in front of the vehicle, but enhance road traffic safety by helping to improve visibility of the respective vehicle for the other road traffic participants. This mainly relates to the following functions: 
     DRL—Daytime running light, of white color 
     Turn indicator, of amber or red color 
     Front position light, of white color 
     Front parking light, of white color 
     Tail light, of red color 
     Stop light, of red color 
     High mount stop light (HMSL), of red color 
     Side marker, of white, amber or red color 
     Besides the required color of the light beam, each of the signal functions is characterized by visibility, which is based on the required directions and propagation angles of the light beam both on the horizontal and vertical plane as well as photometric requirements where in various angular areas in front of/behind the vehicle there are various areas with various required luminous intensity values. 
     LIST OF REFERENCE MARKS 
       1 —housing 
       2 —chamber 
       3 —lighting unit 
       4 —layer 
       5 —coating 
       7 —light unit 
       8 —connecting element 
       9 —entry area 
       10 —light ray 
       11 —light source 
       12 —carrier 
       13 —spacing element 
       14 —bearing area 
       15 —light guide 
       16 —rear face 
       17 —front surface 
       18 —rear surface 
       19 —intermediate area 
       20 ,  21 —filter 
       22 —exit surface 
       23 —optical system 
       24 —transitional layer 
       25 —carrier 
       25   a —front surface 
       25   b —rear surface 
       26 —optical element 
       26   a —emitting element 
       26   b —functional element 
       27 —reflective surface 
       28 —unbinding element 
       29 —exit area 
       30 —exit area