Illumination device

Abstract

The invention relates to an illumination device, in particular contour lighting for a motor vehicle, having an optical waveguide (1), which is made of glass fiber and is surrounded by an at least partly transparent hollow profile (2), and a compensation component (5), the compensation component (5) being formed by a cylindrical spiral (51), which is integrated into the hollow profile (2), and the optical waveguide (1) completely passing through the compensation component (5).

Description

[0001] Lighting equipment

[0002] The invention relates to a lighting device, in particular contour lighting for a motor vehicle, comprising an optical fiber made of glass fiber, surrounded by a transparent hollow profile, and a compensation component.

[0003] It is well known that lighting can be used to create a special ambiance in both the vehicle interior and exterior. This aims to increase comfort and well-being within the vehicle. At the same time, such lighting can be used to highlight features and improve orientation. In this context, contour lighting is also well-known; it can be used to emphasize the outlines or lines of components and groups of components. Such contour lighting can also be referred to as linear lighting.

[0004] This type of lighting is often achieved using light sources, usually LEDs (light-emitting diodes), whose light is coupled into an optical fiber made of diffuse material at one end. The optical fiber then distributes the light homogeneously. The light exits laterally along the optical fiber, creating a visible linear strip of light. Transparent or clear plastics, such as polymethyl methacrylate (PMMA) or polycarbonate (PC), are frequently used as materials for these optical fibers. The optical fiber is typically surrounded by a protective plastic layer.

[0005] Alternatively, optical fibers are also used as the material for the optical waveguide. Optical fibers typically consist of quartz glass surrounded by a protective plastic sheath. This sheath is made of a transparent plastic. Compared to optical waveguides made of plastic, optical fibers have the problem that, due to the physical effect of thermal expansion, they are subject to significantly different linear expansion caused by temperature fluctuations. This problem is particularly relevant in vehicle exteriors, where, according to automotive industry specifications, temperature fluctuations between -40°C and +90°C must be taken into account.In addition, the lighting devices considered here are installed on components or groups of components that are also made of plastic and are therefore subject to a linear expansion that differs from that of the optical fibers.

[0006] The significantly different coefficients of thermal expansion of glass and plastic are responsible for the linear expansion caused by temperature fluctuations. The coefficient of thermal expansion is a characteristic value that describes how a material behaves with regard to changes in its dimensions when the temperature changes. The change in length of a material is characterized by the coefficient of linear thermal expansion, also known as the coefficient of thermal expansion.

[0007] The differing coefficients of thermal expansion result in mechanical stresses during high temperature fluctuations. Due to the greater expansion variations in the plastic compared to the glass fibers, these stresses can lead to the destruction of the glass fibers if the plastic sheath is rigidly bonded to them. To reduce this risk, the inner diameter of the plastic sheath is chosen to be larger than the outer diameter of the glass fibers, so that they are arranged "floating" within the sheath.

[0008] At the same time, known lighting devices employ an additional compensation component, which is tubular in shape to compensate for the difference in thermal expansion. This additional compensation component is installed in an arc at one end of the casing. In this way, the different thermal expansion can be compensated to a limited extent.

[0009] However, the use of the compensation component described above has the disadvantage that length compensation is only possible to a very limited extent. This is because the compensation component cannot be bent arbitrarily, as a radius that is too small can lead to breakage of the glass fibers. Furthermore, the bend requires additional installation space, which is not available in many applications.

[0010] The invention aims to remedy this problem. The invention is based on the objective of creating a lighting device that allows for a large length compensation between the fiber optic cable and the plastic sheathing while requiring only a small installation space. According to the invention, this objective is achieved with the features of claim 1.

[0011] The invention provides a lighting device that enables a large length compensation between the fiber optic cable and the plastic cladding while requiring only a small installation space. Its cylindrical spiral design allows for greater length compensation than known arc-shaped compensation components. Furthermore, the compensation component according to the invention is very compact, thus requiring less installation space than known arc-shaped compensation components.

[0012] In this embodiment of the invention, the compensation component is integrated into the hollow profile and sealed against environmental influences. This design makes the lighting device according to the invention also suitable for use in the exterior of vehicles.

[0013] In a further development of the invention, the cylindrical spiral has at least one thread. By providing a plurality of threads, the space available for length compensation in the compensation component is increased.

[0014] Advantageously, the cylindrical spiral forms a circular geometry at its center. This circular geometry allows the compensation component to be attached to the vehicle.

[0015] Other embodiments and configurations of the invention are specified in the remaining dependent claims. An exemplary embodiment of the invention is illustrated in the drawings and is described in detail below. The drawings show:

[0016] Figure 1 shows the basic half-view of a lighting device with a compensation component according to the invention at maximum extension;

[0017] Figure 2 shows the lighting device depicted in Figure 1 in its minimum dimensions.

[0018] The lighting device chosen as an example is particularly suitable for contour lighting in motor vehicles. It can, for example, be installed on the exterior of a vehicle, such as on the radiator grille.

[0019] The lighting device comprises an optical fiber 1 made of glass fibers, which is surrounded by a hollow profile 2. In the exemplary embodiment, the hollow profile 2 is an extruded hollow profile made of polyamide (PA). In a variation of the exemplary embodiment, the hollow profile 2 can, for example, also be manufactured as an injection-molded part. The hollow profile 2 is provided with fastening elements (not shown) that serve to attach it to a vehicle component or a vehicle component group.

[0020] The inner diameter of the hollow profile 2 is larger than the outer diameter of the optical fiber 1. The optical fiber 1 therefore floats within the hollow profile 2. This allows for relative movement between the optical fiber 1 and the hollow profile 2, which can be caused, for example, by differing thermal expansion during temperature fluctuations.

[0021] In the exemplary embodiment, the hollow profile 2 consists of two sections 21 and 22. The first section 21 is made of transparent polyamide. Section 21 is located in the visible area of ​​the vehicle component or vehicle component group. The second section 22, on the other hand, is located in the non-visible area of ​​the vehicle component or vehicle component group. For this reason, the second section 22 can also be made of a non-transparent plastic.

[0022] A light source 3 in the form of an LED is arranged at one end of the optical waveguide 1. Light is coupled into the optical waveguide 1 via the light source 3 in a known manner.

[0023] The light source 3 is attached to the vehicle component or vehicle component group in the longitudinal direction of the lighting device. For this purpose, in the exemplary embodiment, a keder (not shown) is formed on the hollow profile 2, which corresponds to a guide on the vehicle component or vehicle component group.

[0024] The lighting device incorporates a compensation component 5 to compensate for the different linear expansion due to temperature fluctuations between the optical fiber 1 and the hollow profile 2.

[0025] In the exemplary embodiment, the compensation component 5 is made of a glass fiber reinforced plastic (GFRP). The use of other materials, e.g., thermoplastic materials, which would allow the compensation component to be manufactured as an injection-molded part, is possible.

[0026] The compensation component 5 is formed by a cylindrical spiral 51 – also called a helix – which is integrated into the hollow profile 2. Consequently, the compensation component 5 is completely permeated by the optical fiber 1. In the exemplary embodiment, the cylindrical spiral 51 has only one turn or one winding. In a variation of the exemplary embodiment, it is also possible to design the cylindrical spiral 51 with multiple turns.

[0027] Connections 52 are formed at both ends of the spiral 51, which connect the compensation component 5 to the hollow profile 2. The compensation component 5 is integrated into the hollow profile 2 and sealed against environmental influences. The cylindrical spiral 51 forms a circular geometry in its center, creating a circular opening 53. The opening 53 can be used to attach the lighting device to the vehicle component or vehicle component group.

[0028] The cross-section inside the cylindrical spiral 51 is larger than the inner diameter of the hollow profile 2. This increases the volume in the spiral 51, providing more space to compensate for the different thermal expansion. Furthermore, the cylindrical spiral design 51 of the compensation component 5, as chosen according to the invention, ensures that the optical fiber 1 does not rub against itself despite a 360° rotation.

[0029] The diameter of the cylindrical spiral 51 is determined, firstly, by the smallest possible radius of curvature of the optical waveguide 1, in order to avoid damage or even breakage and at the same time to prevent excessive optical losses. Secondly, the diameter of the cylindrical spiral 51 is determined by the maximum volume required to accommodate the optical waveguide 1 with minimal expansion of the hollow profile 2.

[0030] In the case of maximum expansion of the hollow profile 2, i.e., at the highest temperature acting on the lighting device, the optical fiber 1 rests against the inner side of the cavity formed in the cylindrical spiral 51, as can be seen in principle from Figure 1. This is the smallest radius acting on the optical fiber 1. This radius must be chosen such that the aforementioned damage to the optical fiber does not occur. Figure 2 schematically shows the lighting device at minimum expansion of the hollow profile 2, i.e., at the lowest temperature acting on the lighting device. In this state, the optical fiber 1 rests against the outer side of the cavity formed in the cylindrical spiral 51.

[0031] The different positions of the light source 3 and the fastening element 4, as shown in Figures 1 and 2, illustrate how length compensation can be achieved with the device according to the invention. If the lighting device heats up, for example due to high ambient temperatures, the hollow profile 2 expands. This expansion pulls the optical fiber 1. Since the glass fiber material of the optical fiber does not allow expansion, it rests against the inside of the cavity formed in the cylindrical spiral 51. Within the cylindrical spiral 51, the optical fiber 1 performs a movement similar to tightening a loop.

[0032] As it cools, the hollow profile 2 contracts again, causing the light source 3 and the mounting element 4 to move towards each other. The optical fiber 1 is thereby pushed towards the compensation component 5. Within the cylindrical spiral 51, the optical fiber 1 moves towards the outer wall of the spiral 51.

[0033] The lighting device according to the invention can be used in a variety of applications, for example on the radiator grille of a motor vehicle. The lighting device is mounted on a vehicle component or a vehicle component group in such a way that the compensation component 5 and the second section 22 of the hollow profile 2 are not visibly installed.

[0034] The first section 21 of the hollow profile 2 of the lighting device can be partially enclosed by a vehicle component or component group by installing this section, at least partially, in a joint. Light can emerge from the component or component group in a strip-like pattern through the gap of the joint in which the first section 21 of the hollow profile 2 is located, thus creating contour lighting. However, it is also possible to install the area of ​​the first section 21 of the hollow profile 2 of the lighting device so that it is visible from all sides. In this case, the visible section 21 itself follows the contour of the component or component group, thereby creating contour lighting as well.

[0035] Only one half of the complete lighting device is shown in the figures. The other half, not shown, is a mirror image of the half shown. Consequently, a compensating component 5 is also arranged at this end, to which a second section 22 is attached. At this end as well, the compensating component 5 and the second section 22 are arranged in the non-visible area of ​​the component or component group. This design is particularly suitable for large components or component groups where a long lighting device is required to achieve complete contour illumination. For shorter lighting devices, the provision of a second compensating component 5, as well as the second section 21, can be omitted.

[0036] The lighting device according to the invention compensates for the different thermal expansion between the optical fiber and the plastic sheathing due to temperature fluctuations. The compensation component according to the invention is very compact and therefore requires little space. At the same time, the invention ensures that the optical fiber does not suffer any mechanical damage at either maximum or minimum expansion. Furthermore, the compensation component prevents optical losses.

Claims

Patent claims 1. Lighting device, in particular contour lighting for a motor vehicle, comprising an optical fiber (1 ) made of glass fiber, which is surrounded by a hollow profile (2) which is at least partially transparent, and a compensation component (5), characterized in that the compensation component (5) is formed by a cylindrical spiral (51 ) which is integrated into the hollow profile (2), and that the compensation component (5) is completely penetrated by the optical fiber (1 ).

2. Lighting device according to claim 1, characterized in that the compensation component (5) is integrated into the hollow profile (2) in a sealed manner against environmental influences.

3. Lighting device according to claim 1 or 2, characterized in that the cylindrical spiral (51) has at least one thread.

4. Lighting device according to one of the preceding claims, characterized in that the cylindrical spiral (51) forms a circular geometry in its center.

5. Lighting device according to one of the preceding claims, characterized in that the hollow profile (2) consists of two sections (21 , 22).

6. Lighting device according to claim 5, characterized in that at least the first section (21 ) of the hollow profile (2) consists of a transparent plastic.

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