Lens assembly for a light module of a motor vehicle headlamp

Description

[0001] The present invention relates to a lens assembly for a light module of a motor vehicle headlight according to the preamble of claim 1. A lens assembly is known from DE 10 2014 216 127 A1. The known lens assembly comprises a first lens, a first half-shell, and a second half-shell. The two half-shells each have a first section and a second section. The first sections are configured to encompass an edge of the first lens. The first lens has a first optical axis that runs inside the half-shells between the first section and the second section.

[0002] The known lens assembly has a single projection lens as the objective. The sections of the known lens assembly represent ends of the lens assembly in a direction parallel to the optical axis. A light source is arranged at the second end of the known lens assembly.

[0003] US 2006 / 023175 A1, US 6 172 822 B1 and US 4 187 534 A each disclose a lens assembly having the features of the generic term.

[0004] The object of the present invention is to provide a lens assembly for a high-resolution light module of a motor vehicle headlight, comprising a plurality of lenses that are precisely positioned and fixed relative to one another with high temperature stability. The lens assembly should be characterized by a small number of components, a tight tolerance chain, and simple assembly. Furthermore, no additional parts should be required to prevent sun load and stray light. The term "sun load" refers to the effect of solar radiation, which, under unfavorable conditions, can lead to locally undesirable or even component-endangering high temperatures in the light module due to the focusing effect of the optical components of the light module.There are various causes within a lens that lead to stray light, which then affects the light distribution. For example, with partial high beam, stray light enters areas of the light distribution that should be dark. One possible source of stray light is the lens edges, where the actual surfaces often deviate more from the desired surface than in the center of a lens.

[0005] This object is achieved by the sum of the features of claim 1. The invention differs from the prior art mentioned at the outset in that the objective assembly has a second lens having an optical axis coinciding with the first optical axis, in that the second sections are configured to engage around an edge of the second lens, in that the first half-shell has two first contact surfaces and the second half-shell has two second contact surfaces, wherein the contact surfaces each extend continuously from the first section to the second section, so that one of the first contact surfaces in each case bears continuously against one of the second contact surfaces from the first section to the second section, and in that the two half-shells, when joined together, form a tube which is closed at its first section by a lens and which surrounds a part of the optical axis running between the two lenses.

[0006] The use of the second lens in the lens assembly improves the sharpness with which the inner light distribution, which is projected by the lens assembly as an outer light distribution of the vehicle headlight, can be reproduced. This allows high-resolution inner light distributions, such as those generated with micro-LEDs or micro-mirror chips (DMD, digital mirror device), to be projected as the outer light distribution of the light emitted by the light module or the vehicle headlight, while maintaining their resolution.

[0007] Because the second sections are configured to engage around an edge of the second lens, the second lens can be precisely located and held firmly in the light module. Because the first half-shell has two first contact surfaces and the second half-shell has two second contact surfaces, each of which extends continuously from the first section to the second section, so that one of the first contact surfaces rests continuously against one of the second contact surfaces from the first section to the second section, the two lenses are precisely held relative to one another.Because the two half-shells, when joined together, form a tube which is closed at its first section by a lens and which surrounds a part of the optical axis running between the two lenses, the beam path of the useful light propagating inside the lens assembly is not affected by external influences from sunlight or by internal stray light.

[0008] Furthermore, the two half-shells have radially outward-projecting projections and retaining springs arranged in the circumferential direction, which engage behind the projections in an elastically deformed state and generate clamping forces acting in the circumferential directions of the half-shells perpendicular to the optical axis, pressing the abutting surfaces against each other. This enables simple pre-assembly of the lens assembly. The lens assembly with the inserted lenses can then be easily handled as a whole during further assembly of the light module. During later operation, the elastic bracing ensures good vibration resistance. On the one hand, the bracing allows slight relative movement of the two half-shells against each other and, on the other hand, through play-compensating restoring forces, ensures a stable connection between the half-shells and lenses, even under the influence of vibrations.

[0009] A preferred embodiment is characterized in that the first sections are configured to engage the edge of the first lens in such a way that the position of the first lens is positively fixed in both directions of its optical axis. This allows the first lens to be held in the lens assembly with minimal assembly effort, a small number of components, and tight tolerances.

[0010] It is also preferred that the second sections are configured to engage the edge of the second lens in such a way that the position of the second lens is positively fixed in both directions of its optical axis. This allows the second lens to be held in the lens assembly with minimal assembly effort, a low number of components, and tight tolerances.

[0011] It is further preferred that the contact surfaces with which the two half-shells abut each other lie in a plane in which the optical axis also runs. The optical axis generally runs in a plane in which a diameter of the first lens and the second lens also lies. This allows the lenses to be inserted into one of the two half-shells without stress during assembly of the lens assembly.

[0012] A further preferred embodiment is characterized in that the arrangement of the two half-shells relative to one another is defined by interlocking form-fitting structures arranged in the contact surfaces and protruding from the contact surfaces and / or being recesses such as blind holes. This precisely defines the position of the half-shells relative to one another and thus also the position of the first lens and the second lens relative to one another, which is advantageous for the quality of the optical image provided by the lens assembly.

[0013] It is further preferred that at least the first lens has a circular cross-section in a surface perpendicular to its optical axis.

[0014] A further preferred embodiment is characterized in that the light module has a lens carrier which has a circular opening and which surrounds the first ends in an axial direction in a form-fitting and radially force-fitting manner.

[0015] It is also preferred that the half-shells be made of liquid crystal polymer. Liquid crystal polymer has the advantage of high dimensional stability, even under large temperature fluctuations (e.g., -20°C to 100°C). The low thermal expansion and high dimensional stability of the half-shells result in a stable position of the lenses within the lens assembly. This is particularly advantageous in conjunction with the generation of high-resolution internal light distributions. The more temperature-stable the lens positions are, the smaller the distortions of the external light distribution caused by temperature changes in the lens assembly, which result from the imaging of the internal light distribution by the lens assembly.

[0016] It is further preferred that the half-shells have inner walls which are provided with anti-scattered light structures.

[0017] A further preferred embodiment is characterized in that the anti-scattered light structures are formed into the inner wall.

[0018] Further advantages will become apparent from the following description, the drawings, and the dependent claims. It is understood that the features mentioned above and those to be explained below can be used not only in the respective combinations specified, but also in other combinations or on their own.

[0019] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description.

[0020] Showing, in schematic form: Figure 1 shows an embodiment of a motor vehicle headlight according to the invention; Figure 2 shows an embodiment of a first half-shell; Figure 3 shows an embodiment of a second half-shell; and Figure 4 shows the objects of the Figure 2 and 3in a state assembled into a lens assembly.

[0021] In detail, the Figure 1 a motor vehicle headlight 10 with a housing 12, the light exit opening of which is covered by a transparent cover plate 14. A light module 16 of the motor vehicle headlight 10 is arranged inside the housing 12. The light module 16 has a light source 18 and a lens assembly 20. The z-direction is a main radiation direction of the light module. The x-direction is vertical when the motor vehicle headlight is used as intended. The y-direction is horizontal when the motor vehicle headlight is used as intended.

[0022] The light source 18 is configured to generate an internal light distribution. The light source 18 consists, for example, of an array 22 of individually and / or group-controlled micro-LEDs 22'. The light distribution (which is high-resolution, corresponding to a large number of micro-LEDs) is then obtained, for example, on the light exit surface of the array 22, which in this case is simultaneously a light exit surface of the light source 18. The resolution is limited by the size of the light exit surface of an individual micro-LED 22'. Alternatively, the light source 18 can also be an arrangement consisting of a high-intensity semiconductor light source and a micromirror array (DMD: digital mirror device) with individually or group-adjustable micromirrors. The micromirrors are illuminated by the semiconductor light source, and these reflect the light into the lens assembly or in other directions depending on the mirror position.

[0023] The lens assembly 20 is configured to project the inner light distribution as the outer light distribution into the half-space located in front of the motor vehicle headlight 10 in the z-direction. The lens assembly has, for example, a cylindrical, in particular a circular-cylindrical, basic shape. The cylinder axis lies, for example, in the z-direction, and the guide curve of the cylindrical basic shape is a closed loop, which lies, for example, in the xz-plane.

[0024] The lens assembly 20 comprises a first lens 24, a first half-shell 26, and a second half-shell 28. When joined together, the two half-shells 26, 28 form a tube having the aforementioned basic shape. The first lens 24 is a light exit lens of the lens assembly 20.

[0025] Each of the two half-shells 26, 28 has a first section and a second section. The first half-shell 26 has a first section 26.1 and a second section 26.2. Similarly, the second half-shell 28 has a first section 28.1 and a second section 28.2.

[0026] The first sections 26.1, 28.1 are each configured to positively engage an edge 24.1 of the first lens 24 such that the position of the first lens is positively fixed in both directions of its optical axis. This allows the first lens to be held in the lens assembly with minimal assembly effort, a small number of components, and tight tolerances.

[0027] In one embodiment, the form fit extends over the entire circumference of the lens edge, which lies in a surface perpendicular to the optical axis. Alternatively, the form fit extends over individual sections of the lens edge. The lens edges are implemented, for example, as collars running around the optically relevant central parts of the lenses. The sections have a concave groove, which, in terms of shape and dimensions, forms a negative to the collar, which then represents a positive. This preferably applies to all lenses arranged in the lens assembly. The number of sections is preferably three to achieve automatic centering of the lens in the sections. The sections are preferably arranged equidistantly around the circumference.

[0028] Similarly, the second sections 26.2, 28.2 are configured to positively engage an edge 30.1 of the second lens 30 such that the position of the second lens is positively fixed in both directions of its optical axis. This also allows the second lens to be held in the lens assembly with minimal assembly effort, a small number of components, and tight tolerances.

[0029] In one embodiment, the positive fit extends over the entire circumference of the lens edge, which lies in a surface perpendicular to the optical axis. Alternatively, the positive fit extends over individual sections of the lens edge. The number of sections is preferably three to achieve automatic centering of the lens in the sections. The sections are preferably arranged equidistantly around the circumference.

[0030] The edges 24.1 and 30.1 preferably extend in surfaces parallel to the xy plane. The first lens 24 has a first optical axis 24.2, which runs inside the half-shells 26, 28 between the first sections 26.1, 28.1 and the second sections 26.2, 28.2. The first optical axis 24.2 coincides, for example, with the z-direction. The second lens 30 preferably has an optical axis that coincides with the first optical axis 24.2.

[0031] Figure 2 shows an embodiment of a first half-shell 24 in an oblique view together with a first lens 24, a second lens 30, a third lens 32 and a fourth lens 34. The third lens 32 and the fourth lens 34 are only optionally present.

[0032] Figure 3shows a complementary second half-shell 28. The first half-shell 26 has two first contact surfaces 26.3, 26.4, and the second half-shell 28 has two second contact surfaces 28.3, 28.4. The second contact surface 28.4 is also shown in the Figure 1 visible as an edge.

[0033] The contact surfaces each extend continuously at least from the first section 26.1 to the second section 26.2, so that one of the first contact surfaces 26.3, 26.4 rests continuously on one of the second contact surfaces 28.3, 28.4 from the first section 26.1 to the second section 26.2.

[0034] For example, the contact surfaces 26.4 and 28.4 extend continuously at least from the first section 26.1 to the second section 26.2, so that the first contact surface 26.4 continuously bears against the second contact surface 28.4 from the first section 26.1 to the second section.

[0035] The arrangement of the two half-shells 26, 28 relative to each other is defined by interlocking form-fitting structures arranged in the contact surfaces 26.3, 26.4, 28.3, 28.4. The form-fitting structures are preferably elevations 29 (e.g., locating pins) in one half-shell, which are negatives of depressions 31 in the other half-shell.

[0036] The half-shells 26, 28 are made of liquid crystal polymer. Figure 3 As shown in Figure 2, the inner walls of the half-shells 26, 28 are provided with anti-scattering structures 33. In one embodiment, the anti-scattering structures 33 are grooves (corrugations) formed into the inner walls. Alternatively, the scattering structures can consist of a black coating or have such a coating.

[0037] In the present invention, the ribs that hold the lenses in the mount can be raised to cover the edge of a lens and thus reduce stray light (this could be implemented on the light entrance side of the lens). Likewise, additional ribs can be added, which then function as a diaphragm in the finished lens. Figure 3 The ribs are clearly visible. In a preferred design, the ribs are also of different heights.

[0038] Figure 4 shows the objects of Figure 2 and 3in a state when joined together to form an objective assembly. In this state, the two half-shells 26, 28 form a tube with a first section and a second section, which is closed at its first section 26.1 by the first lens 24 and which surrounds a part of the optical axis 24.2 running between the two lenses 24, 30. The second lens 30 closes the tube at its second section 26.2. The first section preferably forms a first tube end. The second section preferably forms a second tube end. The tube preferably has a circular-cylindrical basic shape with the optical axis as the cylinder axis. The contact surfaces lie in a longitudinal section through this basic shape, in which the cylinder axis also runs. The cylinder axis coincides with the optical axis 24.1.

[0039] When assembled, the tube preferably has only the openings designed to accommodate the first lens and the second lens. This ensures that the beam path of the useful light propagating inside the lens assembly is not affected by external influences such as stray light from the environment and / or sunlight.

[0040] The contact surfaces with which the two half-shells abut one another lie in a plane in which the optical axis 24.2 also runs. The optical axis 24.2 generally runs transverse to a plane in which a diameter of the first lens or the second lens lies. The lenses can therefore be inserted into one of the two half-shells without stress during assembly of the lens assembly. The two half-shells 26, 28 have projections projecting radially outwards and retaining springs 35 arranged in the circumferential direction, which engage behind the projections in an elastically deformed state and in the process generate clamping forces acting in the circumferences of the half-shells perpendicular to the optical axis 24.2 and pressing the abutting contact surfaces against one another.The retaining springs 35 are preferably leaf springs made of spring steel with inwardly bent ends 36, whose shape is adapted to the projections so that they can engage behind them in an elastically deformed state. The projections are in the . Figure 4 concealed by the mounted leaf springs 35.

[0041] At least the first lens 24 has a circular cross-section in a surface perpendicular to its optical axis.

[0042] The lens carrier 38 has a circular opening and engages the first ends in a form-fitting and / or force-fitting manner. The half-shells have radially projecting tabs 40 (transverse to the optical axis 24.2) with which they can be screwed together with the lens carrier 38. The Figure 4illustrated screws 42, the orientation of which represents their screwing direction. The assembly thus formed, consisting of lens carrier 38 and lens assembly 20, is adjusted in its position relative to the light source in the light module.

[0043] The shape of the lenses, and thus of the closed loop mentioned above, does not necessarily have to be circular. What is essential is that the shape of the half-shells partially corresponds to the shape of the lens edges, thus establishing a precisely defined position of the lenses within the lens assembly. The position is pre-fixed in the defined position by preferably two fixing elements such as retaining springs 35. The lens assembly thus formed is then assembled with the lens carrier 38. This permanently strengthens the resilient cohesion of the two half-shells and thus of the entire lens package arranged within the two half-shells.

Claims

1. Objective lens assembly (20) for a light module (12) of a motor vehicle headlight (10), the objective lens assembly (20) having a first lens (24), a first half-shell (26) and a second half-shell (28), the two half-shells (26, 28) each having a first portion (26.1, 28.1) and a second portion (26.2, 28.2), the first portions (26.1, 28.1) being designed to encompass an edge (24.1) of the first lens (24), and the first lens (24.1) having a first optical axis (24.2) which extends inside the half-shells (26, 28) between the first portion (26.1, 28.1) and the second portion (26.2, 28.2), the objective lens assembly (20) having a second lens (30) which has an optical axis coinciding with the first optical axis (24.1), that the second portions (26.2, 28.2) are designed to encompass an edge (30.1) of the second lens (30), that the first half-shell (26) has two first contact surfaces (26.3, 26.4) and the second half-shell (28) has two second contact surfaces (28.3, 28.4), the contact surfaces (26.3, 26.4, 28.3, 28.4) each extending continuously from the first portion (26.1, 28.1) to the second portion (26.2, 28.2), so that each of the first contact surfaces (26.3, 26.4) continuously abuts one of the second contact surfaces (28.3, 28.4) from the first portion (26.1, 28.1) to the second portion (26.2, 28.2), and that the two half-shells (26, 28) when joined together form a tube which is closed at its first portion (26.1, 28.1) by a lens (24) and which surrounds a part of the optical axis (24.1) that extends between the two lenses (24, 30), characterized in that the two half-shells (26, 28) have radially outwardly protruding projections and retaining springs (35) which engage behind the projections in a resiliently deformed state and thereby generate clamping forces which act in the circumferential directions of the half-shells (26, 28), which circumferential directions are perpendicular to the optical axis (24.1), and press the abutting contact surfaces against one another.

2. Objective lens assembly (20) according to claim 1, characterized in that the first portions (26.1, 28.1) are designed to encompass the edge of the first lens (24) such that the position of the first lens (24) is form-fittingly fixed in the two directions of its optical axis (24.1).

3. Objective lens assembly (20) according to claim 1 or claim 2, characterized in that the second portions (26.2, 28.2) are designed to encompass the edge of the second lens such that the position of the second lens (30) is form-fittingly fixed in the two directions of its optical axis.

4. Objective lens assembly (20) according to any of the preceding claims, characterized in that the contact surfaces (26.3, 26.4, 28.3, 28.4) with which the two half-shells (26, 28) abut one another lie in a plane in which the optical axis (24.1) also extends.

5. Objective lens assembly (20) according to any of the preceding claims, characterized in that the arrangement of the two half-shells (26, 28) relative to one another is defined by interlocking form-fitting structures (29, 31) which are arranged in the contact surfaces.

6. Objective lens assembly (20) according to any of the preceding claims, characterized in that at least the first lens (24) has a circular cross-section in a surface which is perpendicular to the optical axis (24.1) of said first lens.

7. Objective lens assembly (20) according to claim 6, characterized in that the objective lens assembly has a lens carrier (38) which has an opening and which form-fittingly and radially force-fittingly surrounds the first ends in an axial direction.

8. Objective lens assembly (20) according to any of the preceding claims, characterized in that the half-shells (26, 28) are made of liquid crystal polymer.

9. Objective lens assembly (20) according to any of the preceding claims, characterized in that the half-shells have inner walls which are provided with anti-scattering light structures (33).

10. Objective lens assembly (20) according to claim 7, characterized in that the anti-scattering light structures (33) are formed in an inner wall.