Description

The present invention relates to a lighting assembly for a lighting device of a motor ve hicle, the lighting assembly comprising an objective module with at least one objective lens mounted in a lens holder and with at least two first pins extending from the back of the objective module, the lighting assembly further comprising a light source module with at least one light source mounted on a heat sink element and with at least two first cavities accessible from the front of the light source module, wherein the objective module and the light source module are joined by means of adhesive joints between the first pins and the first cavities. The invention further relates to a corresponding lighting device and a method of assembling and mounting the lighting assembly.

PRIOR ART

A key challenge in assembling and mounting lighting assemblies for lighting devices of motor vehicles is the precise adjustment of light sources and optical components, e.g. objective lenses, relative to each other and relative to a common support frame. Espe cially, the position of the light cut-off line projected onto the road represents a key per formance criterion of motor vehicle head lamps and is subject to strict regulations and customer specifications. In the prior art, active alignment of the various components in combination with adhesive joining is generally employed to meet the required stand ards. Active alignment means, that during assembling e.g. of an objective module with a light source module, the light source is operated and the resulting lighting effect is monitored. The target arrangement of the modules is then finally defined by the consti tution of a desired target lighting effect. The fixation of the modules in their target ar rangement is usually established by adhesive joints, especially by pin-cavity-type joints.

The document DE 102012213841 A1 discloses a lighting assembly comprising a light source module, a primary optic module and a segmented fastening unit, wherein the fastening unit is attached to the light source module and to the primary optic mod ule by means of screw joints. The fastening unit comprises fastening means in the form of pins extending from the light source module and related cavities attached to the primary optic module. During assembling the lighting assembly, the cavities are filled with an adhesive and the pins are inserted into the cavities to fasten the modules in target arrangement by pin-cavity-type joints.

A number of drawbacks is associated with the use of a fastening unit according to the teaching of the DE 102012213841 A1. There is an increased number of components to be produced and assembled, namely the fastening means and the screws and threaded holes for attachment to the respective modules. The number of necessary components contributes to the tolerance chain and determines weight and size of the modules as well as time and effort for the assembly process. Furthermore, the need for drilling threaded holes into the modules for the screw joints with the fastening unit was identified as a potential source of contamination with dust or debris.

DISCLOSURE OF THE INVENTION

It is an object of the present invention to provide an alternative embodiment of a light ing assembly for a lighting device of a motor vehicle, the lighting assembly comprising an objective module with at least one objective lens mounted in a lens holder and with at least two first pins, the lighting assembly further comprising a light source module with at least one light source mounted on a heat sink element and with at least two first, wherein the objective module and the light source module are joined by means of adhesive joints between the first pins and the first cavities.

This object is achieved by a lighting assembly according to claim 1 and by the related assembling method taught by claim 10. Advantageous embodiments of the invention are defined in the subclaims.

The invention discloses the technical teaching that the lens holder comprises the first pins and/or the heat sink element comprises the first cavities.

The core of the invention lies in the integration of the fastening means, i.e. the pins and the cavities, into primary components of the modules. Besides serving as means to carry the objective lens or to dissipate waste heat from the light source, the lens holder and the heat sink element according to the invention thus furthermore feature the additional function as fastening means. Owing to this function integration, the in ventive lighting assembly does not comprise the separate fastening unit known from the prior art. Therefore, a significant reduction in the number of components including several screws is achieved, which results in more efficient handling and logistics dur ing assembling as well as in improved properties of the lighting assembly in terms of weight, dimensional tolerance and vibration characteristics.

As a preferred embodiment of the invention the lens holder and the first pins form a one-piece component of uniform material. Likewise, the heat sink element and the first cavities preferably form a one-piece component of uniform material. This allows for an effective production of the components and thus a convenient function integration.

Advantageously, the first pins extend from the back of the objective module and the first cavities are accessible from the front of the light source module. The front of each module corresponds to the respective light exit side and the back of the objective module corresponds to its light entrance side. The back of the objective module thus faces the front of the light source module in the lighting assembly. With the aforemen tioned arrangement of pins and cavities, the modules can be assembled by pushing them together along the optical axis and a straightforward adjustment is feasible.

According to another preferred embodiment, the inventive lighting assembly com prises at least a section of a support frame with at least two second cavities, and the heat sink element comprises at least two second pins, wherein the light source mod ule and the support frame are joined by means of adhesive joints between the second pins and the second cavities. The support frame serves for mounting of the lighting as sembly into a lighting device, wherein several lighting assemblies can be attached to one support frame in an exemplary embodiment. The adhesive joint between the light source module and the support frame is also established by a pin-cavity-type joint and again the fastening means, i.e. the second pins and the second cavities, are integral parts of primary components of the joining partners. The heat sink element in this embodiment thus comprises the first cavities as fastening means for the joint between the light source module and the objective module as well as the second pins as fas tening means for the joint with the support frame. Especially, the heat sink element and the second pins form a one-piece component of uniform material.

Advantageously, the lens holder comprises a thermosetting polymer, and/or the heat sink element comprises an aluminium alloy. Thermosetting polymers, e.g. bulk mould ing compounds, exhibit appropriate thermo-mechanical properties for use in lighting devices of motor vehicles, i.e. high robustness and stiffness as well as a low thermal expansion coefficient.

Preferably, the lens holder is fabricated by means of injection moulding, and/or the heat sink element is fabricated by means of die casting. These are established pro cesses and offer suitable geometrical flexibility to form the parts with integrated pins and cavities.

The invention further concerns a lighting device for a motor vehicle comprising at least one lighting assembly according to one of the aforementioned embodiments.

Furthermore, the invention concerns a method of assembling a lighting assembly for a lighting device of a motor vehicle, the lighting assembly comprising an objective mod ule with at least one objective lens mounted in a lens holder, a light source module with at least one light source mounted on a heat sink element, and a support frame, and wherein the method comprises at least the following steps:

- providing the lens holder with at least two first pins,

- providing the heat sink element with at least two first cavities and with at least two second pins,

- providing the support frame with at least two second cavities,

- positioning the objective module relative to the light source module,

- joining the objective module to the light source module by generating an adhesive joint between the first pins and the first cavities,

- positioning the light source module relative to the support frame, and - joining the light source module to the support frame by generating an adhesive joint between the second pins and the second cavities.

Advantageously, during positioning the objective module and/or the light source mod ule, the light source is operated and a lighting effect thereby generated is monitored, wherein a target arrangement of the objective module and/or the light source module is defined by constitution of a target lighting effect. This procedure corresponds to the active alignment known from the prior art. The formation of the joint between objective module and light source module can be performed in a first workplace and afterwards this pre-assembly is transferred to a second workplace in order to attach it to the sup port frame, which typically carries a multitude of light source modules.

Preferably, during positioning the objective module and/or the light source module, the objective module and/or the light source module are displaced along three transla tional axes and/or rotated around three rotational axes. Such six-axis alignment allows for a most precise positioning and convenient setting of the target arrangement.

PREFERRED EMBODIMENT

Additional details, characteristics and advantages of the object of the invention are disclosed in the following description of the respective figures - which in an exemplary fashion - shows preferred embodiments of the joining method and the joint assembly according to the invention.

Fig. 1 a sketch of the inventive lighting device.

Fig. 1 shows a cross-sectional sketch of a preferred embodiment of the lighting as sembly 100 as part of the inventive lighting device 200. The lighting device 200 is de picted only schematically as an entity comprising the lighting assembly 100, while fur ther components of the lighting device 200 like a housing, a front panel or further light- technical components are not included in Fig. 1. The lighting assembly 100 is depicted in a partially exploded view with the objective module 1 , the light source module 2 and the support frame 3 separated from each other along the optical axis z.

The objective module 1 comprises three lenses 11 mounted in the lens holder 10, e.g. by means of laser beam welding or adhesive bonding. The lens holder 10 exhibits the shape of a cylindrical hull surrounding the lenses 11 . At the back of the lens holder 10, the first pins 12 extend towards the light source module 2. The first pins 12 and the re maining sections of the lens holder 10 form a one-piece component of uniform mate rial, preferably fabricated from a bulk moulding compound by means of bulk moulding.

The light source module 2 comprises the light source 21 , in this case a LED on a printed circuit board 24, mounted on the heat sink element 20. The heat sink element 20 comprises the first cavities 22 and the second pins 23, altogether forming a one- piece component of uniform material, preferably a die-cast part from an aluminium al loy. The first cavities 22 are accessible from the front of the light source module 2 and aligned for acceptance of the first pins 12 to establish adhesive joints of the pin-cavity- type between the objective module 1 and the light source module 2.

For assembling the lighting assembly 100, the first cavities get filled with an adhesive 4, e.g. an ultraviolet-light curable type, and during the positioning of the objective mod ule 1 , typically by means of an automated manipulator, the first pins 12 are received by the first cavities 22 and active alignment is deployed to find the target arrangement of the two modules 1 and 2 relative to each other. The dimensions of the first pins 12 and of the first cavities 22 are chosen to allow for a six-axis alignment of the modules 1 and 2, i.e. within a certain range the objective module 1 can be displaced along three translational axes and/or rotated around three rotational axes. After curing the adhesive 4, the objective module 1 and the light source module 2 are joint together in the target arrangement. Likewise, an adhesive joint is established between the light source module 2 and the support frame 3 with the second pins 23 and the second cavities 31 filled with adhe sive 4 serving as the fastening means.

In addition to the pins 12, 23 and cavities 22, 31 shown in the cross-sectional view of Fig. 1 , further such fastening means are preferably present in the lighting assembly 100, e.g. distributed every 90° around the optical axis z.

The present invention is not limited by the embodiment described above, which is rep resented as an example only and can be modified in various ways within the scope of protection defined by the appending patent claims.

List of Numerals

100 lighting assembly

200 lighting device

1 objective module

10 lens holder

11 lens

12 first pin

2 light source module

20 heat sink element

21 light source

22 first cavity

23 second pin

24 PCB

3 support frame

31 second cavity

4 adhesive z optical axis