Lighting device for a motor vehicle

Abstract

A lighting device for a motor vehicle, comprising: at least one light source; a flat light guide having an entry surface and at least one exit surface, the entry surface being in particular designed as an end face of the light guide; and at least one optical member configured as an optical lens or an optical film, the lighting device being arranged such that the light generated by the at least one light source is at least partially incident into the light guide through the incident surface, the light incident through the incident surface is at least partially emitted from the at least one exit surface, and the light emitted from the at least one light source is at least partially emitted from the light guide through the at least one exit surface. Light emitted from the at least one exit surface of the light guide at least partially passes through the at least one optical member and / or is reflected by the at least one optical member; the housing, the flat light guide and the at least one optical component are arranged on or in the housing, the flat light guide and / or the at least one optical component being made of silicone, or the flat light guide and / or the at least one optical component comprising silicone.

Description

Technical Field

[0001] The invention relates to a lighting device for a motor vehicle according to the preamble of claim 1 and to a method for producing such a lighting device. Background Art

[0002] For signal functions in motor vehicles, such as taillights, brake lights, turn indicators or daytime running lights, the design has long been a decisive factor in taillights or headlights. Since the introduction of LED technology, the design of these lighting devices has become even more important, because the small light-emitting diodes, which are usually used in larger numbers, can be used more flexibly as light sources for signal functions than large bulbs, thus offering a wide range of different design possibilities in combination with the selected optics.

[0003] A variant of LED technology is the form of OLED technology, in which the light-emitting device is not constructed as a small point like a light-emitting diode, but is constructed larger and flat to form a desired luminous surface, which can be illuminated very evenly. The disadvantage of OLED technology has been proven to be the significantly higher cost of OLED technology compared to LED technology. The reasons for these high costs are complex manufacturing processes, different shapes preset by the design, and smaller batches. In addition, there are special high requirements in the automotive field, such as durability under UV load and forces such as vibration, impact and shaking, and temperature resistance in the range of -40°C to +85°C or +100°C. These requirements are significantly more difficult to meet for organic light-emitting diodes than for standard light-emitting diodes.

[0004] This has led to a search for alternative possibilities to achieve a similar construction to that achieved with organic light-emitting diodes (OLEDs), namely in particular a homogeneously illuminated surface. This is achieved by using light-emitting diodes (LEDs) with a flat light guide and front optics in the form of microstructured foils or thin optical lenses for scattering the light emerging from the light guide. Overall, this provides a flat light module that offers high performance with homogeneous illumination of the entire surface.

[0005] Thus, just as in the case of organic light-emitting diodes, a plurality of flat light modules can be positioned offset next to one another and one behind the other when integrated into a taillight in order to produce a desired individual appearance of a signaling function, such as a taillight or a rear brake light.

[0006] An exemplary flat light module consists of a front housing part and a rear housing part connected to each other by a locking device. The front housing part can alternatively be implemented as a double component with a transparent lens. A plate-shaped light guide with micro-optics, a white diffuse reflection film behind the light guide and two or three micro-optics films in front of the light guide are introduced between the housing parts, which are responsible for the light distribution and efficiency of the system as a whole by coordinating the individual micro-optics components with each other. Typical light guides and / or optical components in known flat light modules are usually made of PMMA or PC.

[0007] A lighting device of the above type is known from DE 10 2021 122 264 A1. The lighting device described here comprises a lighting module configured as a flat light module, which has at least one light source, a light guide, a diffuser lens, and a lighting surface configured as an outer lens, from which light is emitted when the lighting device is in operation. The flat light module also has a housing with a reflective surface.

[0008] The current embodiments of flat light modules are designed to be flat and relatively small. In the initial automotive series applications, of course, a plurality of flat flat light modules arranged side by side can be arranged. However, for further automotive applications, it is desirable to be able to have curved and / or larger flat light modules, which, for example, have an elongated rectangular shape and are also curved in this case. Summary of the invention

[0009] Therefore, the problem underlying the present invention is to provide a lighting device of the above type, which can be configured to be curved. In addition, a method for efficiently and / or cost-effectively manufacturing such a lighting device should be provided.

[0010] This is achieved according to the invention by a lighting device of the type mentioned above having the features of claim 1. The dependent claims relate to preferred configurations of the invention.

[0011] According to claim 1, the flat light guide and / or the at least one optical component are made of silicone or the flat light guide and / or the at least one optical component include silicone. The production of the light guide and / or the at least one optical component from silicone enables the production of curved lighting devices. The production of the light guide and / or the at least one optical component from silicone can also bring further advantages, which in particular relate to more efficient or more cost-effective production of the lighting device.

[0012] It can be provided that the flat light guide and / or the at least one optical component is bendable. In particular, the flat light guide and / or the at least one optical component can have at least one bend in the assembled state of the lighting device.

[0013] It can be provided that the radius of the curvature of the flat light guide is greater than three times the thickness of the light guide, in particular greater than four times the thickness of the light guide. With a radius of this magnitude, undesired outcoupling of light from the light guide is avoided, which would lead to a disruption in the homogeneity of the illuminated exit surface of the lighting device. For example, the radius of the curvature of the flat light guide can be between three and twelve times the thickness of the light guide.

[0014] It can be provided that the radius of the curvature of the flat light guide is greater than 8 mm, in particular greater than 12 mm. This ensures that, with wall thicknesses or thicknesses between 2 mm and 3 mm, which are usually used for flat light modules, no undesired outcoupling of light from the light guide occurs. For example, the radius of the curvature of the flat light guide can have dimensions between 8 mm and 25 mm.

[0015] It is possible that the light guide has structures, wherein the light guide is arranged such that light propagating through the light guide is at least partially deflected by the structures so that the light emerges from the light guide through at least one exit face.

[0016] It may be provided that at least one optical component has a structural portion, wherein the optical component is arranged such that light emitted from the light guide passes through the optical component. The structural portion may contribute to the diffusion and uniformity of the light emitted from the lighting device.

[0017] It is possible that at least one optical component is configured to be reflective, wherein the optical component is arranged such that light emitted from the light guide is reflected by the optical component. In particular, the optical component configured to be reflective can have a white surface that can diffusely reflect light back.

[0018] It can be provided that the light guide has a first emitting surface and a second emitting surface opposite to each other. Thus, the light can be emitted not only forward toward at least one optical component provided with the structure, but also backward from the light guide toward the optical component configured as a reflective structure.

[0019] Here, the lighting device can be configured so that light emitted from the second exit surface of the light guide is incident on an optical component constructed as a reflective structure, is reflected from the optical component constructed as a reflective structure back to the second exit surface, and at least partially enters the light guide again through the second exit surface, and then the light is emitted from the first exit surface, wherein the light in particular passes through another optical component.

[0020] It is possible that at least one optical component, in particular a reflective optical component, is connected to the light guide, in particular to one of its end sides. This simplifies the production of the lighting device, on the one hand because the light guide and the optical component can be produced together, and on the other hand because the positioning of the two parts relative to each other during assembly of the lighting device is simpler due to the connection.

[0021] The method according to claim 12 is characterized by the following method steps:

[0022] - producing the light guide and / or at least one optical component designed as an optical lens or optical film by means of an injection molding process,

[0023] - Introducing the light guide and the at least one optical component into the housing of the lighting device.

[0024] The injection molding process for producing the light guide and / or the at least one optical component can be used for mass production of corresponding lighting devices.

[0025] It may be provided that structures of the light guide and / or of the at least one optical component are produced during an injection molding process, in particular wherein the injection molding tool is structured accordingly by means of a photolithographic process or laser processing.

[0026] It is possible to bend the light guide and / or the at least one optical component during assembly of the lighting device. The light guide and / or the at least one optical component can thus be produced as a planar unfolded part, which simplifies the injection molding process. In particular, when the structural parts of the light guide and / or the optical component are produced during injection molding, the introduction of the corresponding microstructure elements into the mold surface of the injection mold in a planar injection molded part can be realized significantly easier. This is because, for example, no restrictions in terms of the demoulding direction have to be taken into account, so that the microstructure elements can be introduced uniformly into the mold surface of the injection mold.

[0027] It can be provided that the light guide and the optical component, in particular the reflective optical component, are manufactured as a one-piece injection-molded component, in which the light guide and the optical component are connected to one another in the longitudinal or transverse direction, and the optical component is folded during the introduction into the housing so that it rests on at least one exit face of the light guide. By manufacturing the light guide and the optical component as a one-piece injection-molded component, the two parts are more cost-effective to manufacture. In addition, the installation of the lighting device is simplified, because by folding the optical component onto at least one exit face of the light guide, the positioning of the two parts relative to one another becomes easier during the assembly of the lighting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention will be described in detail below with reference to the accompanying drawings.

[0029] Figure 1 An exploded view showing a first embodiment of the lighting device according to the present invention;

[0030] Figure 2 A top view showing a light guide and an optical component connected thereto according to a second embodiment of an illumination device of the present invention;

[0031] Figure 3 Show according to Figure 2A side view of a light guide and optical components of a lighting device;

[0032] Figure 4 Show according to Figure 2 Light guide and optical components of lighting device Figure 3 a corresponding view showing the parts folded together;

[0033] Figure 5 A perspective view showing a plurality of light modules arranged next to each other having a third embodiment of an illumination device according to the present invention;

[0034] Figure 6 Show Figure 5 shows details of a third embodiment of the lighting device according to the present invention;

[0035] Figure 7 Show according to Figure 6 An exploded view of the lighting device;

[0036] Figure 8 Show according to Figure 6 Schematic diagram of the bending of the light guide of the lighting device;

[0037] Fig. 9 Show according to Figure 6 A side view of a light guide of a lighting device in a bent state;

[0038] Fig.10 Show Fig. 9 Details;

[0039] Fig.11 Show according to Figure 6 A side view of a light guide of an illumination device in a bent state, wherein the structure is shown with exaggerated size for greater clarity. DETAILED DESCRIPTION

[0040] In the figures, identical or functionally identical parts are provided with the same reference symbols.

[0041] The lighting device shown in the figure includes a light source configured as a light emitting diode (LED) or a plurality of light sources configured as light emitting diodes (LED). Figure 1 , a circuit board 1 is shown on which light sources in the form of light-emitting diodes are arranged. The plurality of light-emitting diodes can also have different colors in order to realize, for example, a double or triple function. These functions can be, for example, position lights, daytime running lights and turn indicators, or position lights, daytime running lights and an automated driving function, wherein the automated driving function requires the color cyan.

[0042] The lighting device also includes a flat light guide 2 having an incident surface 3 and a first and a second exit surface 4 and 5 (see Figure 1 , Figure 3 and Figure 7 ). In this case, the entrance surface 3 is configured as an end side of the light guide 2 , while the exit surfaces 4 , 5 are configured as the front side and the rear side of the light guide 2 .

[0043] The lighting device further comprises a first optical component 6 configured as an optical lens arranged in front of the first exit surface 4 of the light guide 2 and a second optical component 7 configured as an optical lens arranged in front of the first optical component 6 (see Figure 1 and Figure 7 ). Here, the second optical component 7 is optional and can also be omitted. The optical components 6 and 7 can also be configured as optical films instead. At least one optical component 6 and 7 can have a structure that is not shown, which can help diffuse and homogenize the light emitted from the lighting device.

[0044] The lighting device further comprises a housing 8 in which at least one light source 1, a light guide 2 and optical components 6, 7 can be at least partially received (see Figure 1 , Figure 6 and Figure 7 In order to simplify the installation of the optical components, the housing 8 can be implemented in two parts and has a rear housing part 8a and a front housing part 8b (see Figure 1 and Figure 7 ). The light guide 2 and the optical components 6, 7 can then be positioned between these housing parts 8a, 8b and held and fixed when the two housing parts 8a, 8b have been joined together. The housing parts 8a, 8b can be locked to each other, screwed or welded from the rear side.

[0045] The rear housing portion 8a may have a rear wall that is configured to be at least partially reflective (see Figure 7 Alternatively, a reflective optical component 9 may be provided (see Figure 1 ), which is, for example, a reflective optical film with a white surface, so as to diffusely reflect the light back. The reflective optical member 9 is bent at the edge. Therefore, the second exit surface 5 of the light guide 2 and the side edge of the light guide 2 are covered to ideally reflect the exiting light back into the light guide 2 again.

[0046] The lighting device further comprises an optical component 10 configured as an outer lens, which is illuminated as evenly as possible by the light emitted from the light guide 2 (see Figure 1 and Figure 7 The outer lens can be used as an illuminated exit surface of the lighting device. It is possible that the optical component 10 configured as an outer lens is configured as a two-component part in one piece with the front housing part 8b.

[0047] When the lighting device is in operation, light emitted from the light source is coupled into the incident surface 3 at the end of the light guide 2. A portion of the coupled light is directly emitted from the first exit surface 4. Figure 1 The light is emitted to the right in the light guide 2 and leaves the lighting device after passing through the optical components 6, 7 and the outer lens. In addition, a portion of the light propagating in the light guide 2 is emitted from the second exit surface 5 of the light guide 2 and hits the reflective optical component 9. The light is reflected from the reflective optical component back to the second exit surface 5, so that the light is at least partially re-incident into the light guide 2 again through the second exit surface 5, and then the light is emitted from the first exit surface 4 and leaves the lighting device through the optical components 6, 7 and the outer lens.

[0048] The light guide 2 and / or the optical components 6, 7, 9, 10 may be made of silicone or include silicone. The light guide 2 and / or the optical components 6, 7, 9, 10 may be manufactured in particular by an injection molding process. By configuring the light guide 2 and / or the optical components 6, 7, 9, 10 as silicone components, the lighting device may be configured to be curved (see Figure 7 ). Furthermore, the manufacturing can be simplified since the manufacturing of different parts can be combined.

[0049] Figures 2 to 4 An embodiment is shown in which the light guide 2 and the reflective optical component 9 are manufactured as a one-piece injection-molded component. In this case, in the unmounted state, the optical component 9 is connected to the light guide 2 (see Figure 3 ). The optical component 9 has a first section 9a, which in the installed state covers the second exit surface 5 of the light guide 2. The optical component 9 also has three second sections 9b, which in the installed state abut against the side surface 2a of the light guide 2 that is not used as the incident surface 3 and cover it.

[0050] The connecting region between the light guide 2 and the optical component 9 has two fold edges 11 which simplify the folding of the optical component 9 onto the light guide 2 . Figure 4 The optical component 9 folded over onto the light guide 2 is shown with dashed lines. In the folded state, the optical component 9 rests on the second exit face 5 and the side face 2a of the light guide 2 that does not serve as the entrance face 3 and effectively covers them.

[0051] The lighting device can be used as a single light module for a signal function or as part of a multiple arrangement of light modules for a signal function. A plurality of such light modules can also be combined with one another in a partially overlapping manner to jointly form a signal function. For example, this can be a daytime running light or a turn indicator light, or a combination of both functions, in particular when the light source comprises a first light-emitting diode with a "white" color and a second light-emitting diode with a "yellow" color.

[0052] Figure 5A corresponding embodiment with a multi-arranged light module is shown, wherein a third embodiment of the lighting device according to the invention is an intermediate light module 12 used as a curved corner element. Thus, the signal function implemented with a plurality of flat light modules can be implemented as a luminous surface that surrounds the corner of the lighting device, which is designed as a taillight, for example, and which continues in the side area of ​​the taillight. By configuring the light guide 2 and / or the optical components 6, 7, 9, 10 as silicone components, Figure 6 and Figure 7 The light module 12 used as a corner element, shown in the exploded view of FIG. 1 , can also be provided with an outer lens that emits relatively uniform light.

[0053] The light guide 2 and / or the optical components 6, 7, 9, 10 can be produced as a flat, developed part as an injection-molded part and only brought into a curved shape when the lighting device or light module 12 is assembled, such as Figure 8 Bend shapes shown for different bend radii.

[0054] A large bending radius is not critical here, whereas an excessively small bending radius risks causing undesired outcoupling of light from the light guide 2, which results in interference with the homogeneity of the illuminated outer lens 10 of the lighting device. It can be provided that the radius of the curvature of the light guide 2 is greater than three times the thickness of the light guide 2, preferably greater than four times the thickness of the light guide 2. At a radius of this magnitude, undesired outcoupling of light from the light guide is avoided.

[0055] For example, it can be provided that the radius of the curvature of the light guide 2 is greater than 8 mm, preferably greater than 12 mm. This ensures that, with a wall thickness or thickness of the light guide 2 of between 2 mm and 3 mm, which is usually provided in flat light modules, no undesired decoupling of light from the light guide 2 occurs. It is entirely possible to use a larger radius, for example a radius of between 15 mm and 25 mm, in order to produce a satisfactory geometric curve in the corner region and to avoid corners that are too sharp or too sharply formed.

[0056] The optical components 6, 7, 9, 10 and the housing parts 8a, 8b can have the same curvature or the same curvature as the light guide 2 (see Figure 7 ).

[0057] The light guide 2 has a structure 13 on its second exit surface 5, which serves as an outcoupling optical device. It can be provided that, alternatively or additionally, a structure (not shown) is also provided on the first exit surface 4. In order to produce a uniform illumination in the flat light module, it is advantageous if the optical device is implemented as a micro-optical device with a size of less than 200 microns, in particular less than 100 microns. The structure 13 can be designed as a depression or a concave optical structure in the light guide 2 or as a protrusion or a convex structure in the light guide 2.

[0058] As an example, Fig.11A structure 13 is shown which is designed as a concave optical structure with facets 14 between the individual optics. The distribution of the individual optics on the exit face 5 of the light guide 2 is different and is selected to be suitable for achieving the desired uniform illumination of the optical component 10 used as an outer lens.

[0059] It can be provided that structures of the light guide 2 and / or of at least one optical component 6, 7 are produced during the injection molding process. In this case, the corresponding structures of the injection mold can be realized by photolithographic processes or laser processing.

[0060] In a photolithography process, such as UV photolithography or laser interference photolithography, a planar primary optical component is produced, from which a thin nickel sheet is then electroplated. The nickel sheet is directly placed in a mold or, after its shaping, is further electroplated to form a thicker mold insert.

[0061] As a second possible method, direct laser processing of the mold to produce the structure has advantages in terms of time and cost. In addition, in the case of possible repairs, the mold can be re-laser processed, while in the photolithography process a completely new nickel sheet or a thicker electroformed layer must be produced. Therefore, laser processing of the mold is the preferred method.

[0062] By laser processing the mold, structures suitable for raised or convexly configured micro-optics as well as for recessed or concavely configured micro-optics can be created on the mold side on at least one exit face 4 , 5 of the light guide 2 .

[0063] A corresponding implementation or adjustment can also be carried out in structures (not shown) of the optical components 6 , 7 , which can be designed as micro-optics or diffuse optics.

[0064] Reference numerals list

[0065] 1 Circuit board for at least one LED used as a light source

[0066] 2 Light guide

[0067] 2a Side of the light guide not used as the incident surface

[0068] 3. Light guide incident surface

[0069] 4 First exit surface of the light guide

[0070] 5 Second exit surface of the light guide

[0071] 6. First optical component configured as an optical lens

[0072] 7. Second optical component configured as an optical lens

[0073] 8 Housing

[0074] 8a Rear housing part

[0075] 8b Front housing part

[0076] 9 Optical components constructed to be reflective

[0077] 9a First section of the reflective optical component

[0078] 9b Second section of the reflective optical component

[0079] 10 Optical component configured as outer lens

[0080] 11 Bending edge in the connection area between light guide and optical component

[0081] 12 Light module designed as corner element

[0082] 13. Structural part of the second emission surface of the light guide

[0083] 14 Plane of the structure

Claims

1. Lighting devices for motor vehicles, including - at least one light source; - a flat light guide (2) having an entrance face (3) and at least one exit face (4, 5), wherein: The incident surface (3) is in particular configured as an end side surface of the light guide (2); - at least one optical component (6, 7, 9, 10), the at least one optical component being configured as an optical lens or an optical film, wherein the lighting device is configured such that the light generated by the at least one light source (1) is at least partially incident on the light guide (2) through the incident surface (3), the light incident through the incident surface (3) is at least partially emitted from the at least one emission surface (4, 5), and the light emitted from the at least one emission surface (4, 5) of the light guide (4, 5) at least partially passes through the at least one optical component (6, 7, 10) and / or is reflected by the at least one optical component (9); a housing (8) on or in which the flat light guide (2) and the at least one optical component (6, 7, 9, 10) are arranged, It is characterized in that the flat light guide (2) and / or the at least one optical component (6, 7, 9, 10) are made of silicone, or the flat light guide (2) and / or the at least one optical component (6, 7, 9, 10) include silicone.

2. The lighting device according to claim 1, characterized in that: The flat light guide (2) and / or the at least one optical component (6, 7, 9, 10) are bendable.

3. The lighting device according to any one of claims 1 or 2, characterized in that: The flat light guide (2) and / or the at least one optical component (6, 7, 9, 10) have at least one bend in the assembled state of the lighting device.

4. The lighting device according to claim 3, characterized in that: The radius of the curved portion of the flat light guide (2) is greater than three times the thickness of the light guide (2), in particular greater than four times the thickness of the light guide (2).

5. The lighting device according to any one of claims 3 or 4, characterized in that: The radius of the curved portion of the flat light guide (2) is greater than 8 mm, in particular greater than 12 mm.

6. The lighting device according to any one of claims 1 to 5, characterized in that: The light guide (2) has a structure (13), wherein the light guide (2) is arranged so that light propagating through the light guide (2) is at least partially deflected by the structure (13) so that the light emerges from the light guide (2) through the at least one exit surface (4, 5).

7. The lighting device according to any one of claims 1 to 6, characterized in that: The at least one optical component (6, 7) has a structural portion, wherein the optical component (6, 7) is arranged so that light emitted from the light guide (2) passes through the optical component (6, 7).

8. The lighting device according to any one of claims 1 to 7, characterized in that: The at least one optical component (9) is of reflective configuration, wherein the optical component (9) is arranged such that light emitted from the light guide (2) is reflected by the optical component (9).

9. The lighting device according to any one of claims 1 to 8, characterized in that: The light guide (2) has a first emitting surface (4) and a second emitting surface (5) which are opposite to each other.

10. The lighting device according to claim 9, characterized in that: The lighting device is arranged so that light emitted from a second exit surface (5) of a light guide (2) is incident on an optical component (9) configured as a reflective type, is reflected by the optical component configured as a reflective type back to the second exit surface (5), and is at least partially incident again into the light guide (2) through the second exit surface (5), and then the light is emitted from a first exit surface (4), wherein the light in particular passes through another optical component (6, 7, 10) of the optical components.

11. The lighting device according to any one of claims 1 to 10, characterized in that: The at least one optical component (6, 7, 9, 10), in particular a reflective optical component (9), is connected to the light guide (2), in particular at one of the end sides of the light guide (2).

12. A method for manufacturing a lighting device according to any one of claims 1 to 11, characterized in that: The method comprises the following method steps: - manufacturing the light guide (2) and / or at least one optical component (6, 7, 9, 10) by an injection molding process, wherein the at least one optical component is configured as an optical lens or an optical film; - Introducing the light guide (2) and the at least one optical component (6, 7, 9, 10) into a housing (8) of the lighting device.

13. The method according to claim 12, characterized in that The structures of the light guide (2) and / or the at least one optical component (6, 7) are produced during the injection molding process, in particular wherein the corresponding structures of the injection molding tool are realized by a lithographic process or laser machining.

14. The method according to claim 12 or 13, characterized in that: The light guide (2) and / or the at least one optical component (6, 7, 9, 10) are bent during assembly of the lighting device.

15. The method according to any one of claims 12 to 14, characterized in that The light guide (2) and the optical component (6, 7, 9, 10), in particular the reflective optical component (9), are manufactured as a one-piece injection-molded component, in which the light guide (2) and the optical component (6, 7, 9) are connected to each other in the longitudinal or transverse direction, wherein the optical component (6, 7, 9, 10) is folded during its introduction into the housing (8) so that it is placed on the at least one exit surface (4, 5) of the light guide (2).

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