METHOD FOR MANUFACTURING A LENS SYSTEM

Description

[0001] The invention is a method for manufacturing a lens system according to claim 1.

[0002] The invention further relates to a lens system comprising a first lens made of a first material having a first refractive index, and a second lens made of a second material having a second refractive index, wherein the first and second materials and the first and second refractive indices are different. According to the invention, the lens system is manufactured by a method according to claim 1.

[0003] The invention further relates to a motor vehicle headlight.

[0004] Methods for manufacturing lens systems of this type are known in the prior art. Since lens systems are typically composed of several lenses that interact optically, the manufacturing tolerances of the individual lenses must be minimized during their production. Tolerance is defined as the deviation of a quantity (for example, the ideal shape of a lens) from the standard state, which does not yet negatively impair the function of a system. In lens systems, aligning the manufactured lenses relative to one another is disadvantageously complex and costly. Furthermore, for cost reasons, it is important to design the manufacturing process not only as precisely as possible, i.e., with minimal tolerances, but also quickly and efficiently. Documents DE 10 2020 119043 A1, EP 0 746 460 A1, and JP H08 190004 A each disclose methods for manufacturing lenses according to the prior art.

[0005] The object of the present invention is to alleviate or eliminate the disadvantages of the prior art. The invention therefore aims in particular to provide a method for manufacturing a lens system which improves the manufacturing process.

[0006] This problem is solved by a method having the features of claim 1. Preferred embodiments are specified in the dependent claims. According to the invention, the method comprises the following steps: Introducing injection molding material into the recess to form a second lens in the cavity, wherein the second lens has a first optically active surface and a second optically active surface, wherein the second lens is formed on the first lens such that the first optically active surface of the second lens contacts the first optically active surface of the first lens, wherein the injection molding material from which the second lens is formed is a second material having a second refractive index, wherein the first material is different from the second material, wherein the first refractive index and the second refractive index are different such that the first and second lenses form an achromatic lens system, wherein the second material is a UV-curable material, wherein the second mold half has a UV-transparent area which is designed and configured tothat UV light can be shone onto the second lens from outside the injection molding device, providing a UV light source, curing the second lens by irradiation with UV light from the UV light source, wherein the UV light is shone onto the second lens through the UV-transparent area of ​​the second mold half in order to cure it.

[0007] This offers the advantage that the second lens is applied directly to a first optically active surface of the first lens, ensuring that the first and second lenses are precisely aligned with respect to their relative positions. Subsequent adjustment of the two lenses relative to each other is advantageously unnecessary. Furthermore, curing the second lens with UV light reduces the curing time and thus the duration of the manufacturing process. The second material can be an epoxy resin or acrylate. The first material can be glass or polymethyl methacrylate. The first and second lenses form, in particular, an achromatic lens system, which can also comprise more than two lenses. The first optically active surface of the first lens and the first optically active surface of the second lens are preferably complementary in shape.In other words, the first optically active surface of the first lens is the negative of the first optically active surface of the second lens. In this context, the optically active surfaces of a lens are the two surfaces that light strikes and from which light escapes when the lens is illuminated. For example, in a biconvex lens, the two curved surfaces at which the light is refracted are the optically active surfaces.

[0008] It can be provided that the first lens is a convex, preferably a biconvex, lens.

[0009] It may be provided that the second lens is a concave, preferably a bi-concave, lens.

[0010] The first recess may be made of silicone, preferably polydimethylsiloxane. The second recess is preferably made of a UV-transmitting material. Preferably, the entire second half of the injection mold is made of a UV-transmitting material, for example, silicone.

[0011] According to the invention, the recess shape has a step such that the second lens formed from injection-molded material has a reduced volume compared to a lens produced in a non-stepped recess shape. Filling a non-stepped recess shape with injection-molded material can, for example, form a biconvex lens, wherein the stepped recess shape has a reduced volume compared to the biconvex lens.

[0012] It may be provided that, due to the stepping, a section of the second lens facing away from the first lens has a reduced volume compared to a non-stepped lens. In particular, the stepped second lens may be an asymmetric lens, wherein the first and second optically active surfaces of the second lens may have different shapes.

[0013] It can be provided that the contact between the first optically active surface of the second lens and the first optically active surface of the first lens is full-surface, and in particular gap-free. The absence of an air gap between the lenses offers the advantage of preventing unwanted light scattering. A layer or film containing an adhesive, such as silicone oil, can be applied between the lenses to improve adhesion between the first and second lenses. Preferably, the adhesive layer or film is applied to the first optically active surface of the first lens before the injection molding device is closed. The adhesive is preferably transparent.

[0014] It may be provided that the first and second lenses are oriented coaxially to each other in the manufactured state of the lens system.

[0015] Furthermore, according to the invention, the recess shape is designed such that the second optically active surface of the second lens has a Fresnel lens-like surface. This has the advantage that less material is required for the second lens, which in turn reduces manufacturing costs.

[0016] According to the invention, a lens system is provided comprising a first lens which is formed from a first material having a first refractive index, a second lens which is formed from a second material having a second refractive index, wherein the first and second materials and the first and second refractive indices are different, wherein the lens system is an achromatic lens system which is produced by the method according to the invention.

[0017] It can be provided that the lens system comprises a plurality of lenses, wherein at least two lenses are designed as an achromatic lens system which is produced by the method according to the invention.

[0018] According to the invention, a motor vehicle headlight is provided, comprising a lighting device for generating and emitting a light distribution, wherein the lighting device has a lens system which is produced by the method according to the invention.

[0019] Within the context of this description, the terms "top", "bottom", "horizontal", "vertical" are to be understood as indications of orientation when the injection molding device is arranged in its normal operating position during the manufacturing process.

[0020] The invention is further explained below with reference to a preferred embodiment, to which it is not, however, limited. The drawings show: Fig. 1 a schematic illustration of an injection molding device in a first process step of a process according to the invention; Fig. 2 a schematic representation of the injection molding device during a second process step; Fig. 3 a schematic representation of the injection molding device during a third process step; Fig. 4 a schematic illustration of the injection molding device during a fourth process step; Fig. 5 a first embodiment of a lens system which was produced using the method according to the invention; and Fig. 6 a second embodiment of a lens system which was produced using the method according to the invention.

[0021] The illustrations are schematic and greatly simplified for clarity, omitting non-essential elements of the injection molding device.

[0022] Fig. 1 shows a first process step of a process for manufacturing a lens system.

[0023] The first step involves providing an injection molding device 1. The injection molding device 1 comprises a first mold half 1a and a second mold half 1b. The injection molding device 1 is set up to produce optical lenses using an injection molding process.

[0024] The first tool half 1a has a holding section 2, which is arranged on the side of the first tool half 1a facing the second tool half 1b. The holding section 2 is designed to fix a lens in a predetermined position relative to the second tool half 1b. The positioning and fixing of the first lens is carried out according to specific requirements defined by the lens system to be manufactured.

[0025] The method comprises the further step of providing a first lens 3. The first lens 3 is made of a first material having a first refractive index and has a first external shape. The first lens 3 can, for example, be made of glass. Preferably, the first lens is a convex, preferably a biconvex, lens.

[0026] Fig. 2 Figure 1 shows a further process step, which includes inserting and fixing the first lens 3 to the holding section 2. In this step, the first lens 3 is positioned and fixed to the holding section 2 of the first tool half 1a. The first lens 3 is fixed to the holding section 2 such that a first optically active surface 3a of the first lens 3 faces the second tool half 1b and a second optically active surface 3b of the first lens 3 faces away from the second tool half 1b (see Figure 2). Fig. 3 ).

[0027] Fig. 3 Figure 1 shows a further process step, which includes closing the injection molding device. The injection molding device is closed by joining the first mold half (1a) and the second mold half (1b).

[0028] The second mold half 1b has a recess 4 on one side facing the first mold half 1a, wherein, in the closed state of the injection molding device 1, a cavity 5, fillable with injection molding material, is formed between the first lens 3 and the recess 4. The recess 4 can also be referred to as a filling mold or injection mold. The recess 4 is essentially a recess in the second mold half 1b which can be filled with injection molding material. The recess 4 and / or the second mold half 1b is, for example, made of silicone, preferably polydimethylsiloxane.

[0029] The cavity 5 is configured as a negative mold of a second outer shape of a second lens 6, wherein the outer shape of the first lens 3 and the outer shape of the second lens 6 are different. The cavity 5 is essentially formed between the recess shape 4 of the second tool half 1b and the first optically active surface 3b of the first lens 3. The injection molding device includes a (not shown) feeding device for injection molding material, wherein the feeding device is configured to convey injection molding material into the cavity 5.

[0030] Fig. 4 Figure 1 shows a further process step, which includes introducing injection molding material into the recess 4. By introducing injection molding material into the recess 4, or into the cavity 5, a second lens 6 is formed from injection molding material in the cavity 5. The second lens 6 has a first optically active surface 6a and a second optically active surface 6b. The second lens 6 is formed on the first lens 3 such that the first optically active surface 6a of the second lens 6 contacts the first optically active surface 3a of the first lens 3. The second lens 6 is preferably a concave, and in particular a bi-concave, lens. In the manufactured state of the lens system, the first lens 3 and the second lens 6 are oriented coaxially to each other.

[0031] The contact between the first optically active surface 6a of the second lens 6 and the first optically active surface 3a of the first lens 3 is particularly full-surface, preferably gap-free. The first optically active surface 3a of the first lens 3 and the first optically active surface 6a of the second lens 6 are particularly complementary to each other.

[0032] The injection-molded material from which the second lens 6 is formed comprises a second material having a second refractive index. The first material of the first lens differs from the second material of the second lens, with the first and second refractive indices differing such that the first lens 3 and the second lens 6 form an achromatic lens system. The second material is a UV-curable material.

[0033] The second tool half 1b has a UV-transparent area, which is designed and configured to allow UV light from outside the injection molding device to be directed onto the second lens 6. The second tool half can, for example, be made entirely of a UV-transparent material.

[0034] In a further process step, a (not shown) UV light source is provided.

[0035] A further process step includes curing the second lens 6 by irradiation with UV light from the UV light source, wherein the UV light is emitted through the UV light transparent area of ​​the second tool half 1b onto the second lens 6 in order to cure it.

[0036] Fig. 5 Figure 1 shows a lens system produced according to the inventive method, comprising a first lens 3 made of a first material and having a first refractive index. The lens system further comprises a second lens 6 made of a second material and having a second refractive index.

[0037] The first and second materials and their refractive indices are different and chosen such that the lens system is an achromatic lens system. In other words, the first lens (3) and the second lens (6) form an achromatic lens.

[0038] Fig. 6 A second embodiment of a lens system produced according to the inventive method is shown. The recess shape 4 has a step such that the second lens 6, formed from injection-molded material, is stepped down compared to a lens in a non-stepped recess shape (cf. Figure 1). Fig. 3 und 4 ) manufactured lens has a reduced volume.

[0039] The step-off of the second lens 6 is located on a section of the second lens 6 facing away from the first lens 3. The stepped section has a reduced volume compared to a non-stepped lens.

[0040] The recess shape 4 is used to form the second embodiment according to Fig. 6 The second optically active surface 6b of the second lens 6 is designed such that it has a Fresnel lens-like surface. The first optically active surface 6a is concave and is defined by the convex shape of the first lens 3.

Claims

1. Method for manufacturing a lens system, the method comprising the following steps: - Providing an injection molding apparatus (1) comprising a first (1a) and a second (1b) mold half, wherein the injection molding apparatus (1) is adapted to manufacture optical lenses by means of an injection molding process, wherein the first mold half (1a) has, on a side facing the second mold half (1b), a holding portion (2) which is adapted to fix a lens in a predetermined position relative to the second mold half (1b), - providing a first lens (3), wherein the first lens (3) is made of a first material having a first refractive index and has a first outer shape, - inserting and fixing the first lens (3) to the holding section (2), wherein the first lens (3) is fixed to the holding portion (2) such that a first optically active surface (3a) of the first lens (3) faces the second mold half (1b) and a second optically active surface (3b) of the first lens (3) is turned away from the second mold half (1b), - closing the injection molding device by bringing the first (1a) and second (1b) mold halves together, wherein the second mold half (1b) has a recessed mold cavity (4) on a side facing the first mold half (1a), and wherein, when the injection molding device (1) is closed, a cavity (5) capable of being filled with injection molding material is formed between the first lens (3) and the recess (4), wherein the cavity (5) is configured as a negative mold of a second outer shape of a second lens (6), wherein the first outer shape of the first lens (3) and the second outer shape of the second lens (6) are different, - injecting injection molding material into the mold cavity (4) to form a second lens (6) in the cavity (5), wherein the second lens (6) has a first optically active surface (6a) and a second optically active surface (6b), wherein the second lens (6) is formed on the first lens (3) such that the first optically active surface (6a) of the second lens (6) contacts the first optically active surface (3a) of the first lens (3), wherein the injection-molded material from which the second lens (6) is formed is a second material having a second refractive index, wherein the first material is different from the second material, wherein the first refractive index and the second refractive index differ such that the first (3) and second lens (6) form an achromatic lens system, wherein the mold cavity (4) has a step such that the second lens (6) formed from injection molding material has a reduced volume compared to a lens produced in a non-stepped mold cavity, characterized in that the second material is a UV-light-curable material, wherein the second mold half (1b) has a region permeable to UV light, which is configured and arranged such that UV light can be irradiated onto the second lens (6) from outside the injection molding apparatus, - providing a UV light source, - curing the second lens (6) by irradiating it with UV light from the UV light source, wherein the UV light is emitted through the UV-transmissive region of the second mold half (1b) onto the second lens (6) to cure it, and wherein the recess shape (4) is designed such that the second optically active surface (6b) of the second lens (6) has a Fresnel-lens-like surface.

2. Method according to claim 1, wherein the first lens (3) is a convex, preferably a biconvex, lens.

3. Method according to any of the preceding claims, wherein the second lens (6) is a concave, preferably a biconvex, lens.

4. Method according to any of the preceding claims, wherein the mold (4) is formed from silicone, preferably from polydimethylsiloxane.

5. Method according to any of the preceding claims, wherein, due to the step, a portion of the second lens (6) facing away from the first lens (3) has a reduced volume compared to a non-stepped lens.

6. Method according to any of the preceding claims, wherein the contact between the first optically active surface (6a) of the second lens (6) and the first optically active surface (3a) of the first lens (3) is over the entire surface, in particular without a gap.

7. Method according to any of the preceding claims, wherein the first (3) and second (6) lenses are oriented coaxially with respect to one another in the manufactured state of the lens system.

8. Lens system comprising a first lens (3) formed from a first material having a first refractive index, a second lens (6), formed from a second material having a second refractive index, wherein the first and second materials and the first and second refractive indices are different, characterized in that the lens system is an achromatic lens system manufactured by a method according to any one of claims 1 to 7.

9. Lens system comprising a plurality of lenses, characterized in that at least two lenses are configured as an achromatic lens system produced by a method according to any one of claims 1 to 7.

10. Motor vehicle headlight comprising a lighting device for generating and emitting a light distribution, wherein the lighting device comprises a lens system according to claim 8, claim 9, or a lens system manufactured by a method according to any one of claims 1 to 7.