Projection module for a motor vehicle headlamp and motor vehicle headlamp having such a projection module

Abstract

The invention relates to a projection module (2) for a motor vehicle headlamp. The light module (2) comprises a light source for emitting light, primary optics for bundling, shaping and / or deflecting the light emitted by the light source, and secondary optics (4) in the form of a projection lens which images an intermediate image in an intermediate image plane arranged in the light path between the primary optics and the secondary optics (4) as a composite light distribution of the projection module (2) in a front region in front of the motor vehicle along a light exit direction (6) of the projection module (2). The projection module (2) has a heating element (8) for heating the projection lens (4). It is proposed that the heating element (8) has a transparent film (10) made of an electrically insulating material and a conductor track (12) applied to it or embedded therein, which is connected to an electrical power source (16) via a switching element (14), wherein the heating element (8) is applied at least on a partial region of a light entry face and / or a light exit face of the projection lens (4) of the projection module (2) or is at least introduced into a part of the projection lens (4) itself, such that the heating element (8) heats the projection lens (4) when an electrical current through the conductor track (12) is switched on.

Description

Technical Field

[0001] This invention relates to a projection module for a motor vehicle headlight. The projection module includes: a light source for emitting light; primary optics for focusing, shaping, and / or deflecting the light emitted by the light source; and secondary optics, in the form of a projection lens, which images an intermediate image of an intermediate image plane in the front region of the vehicle along the light emission direction of the projection module, forming a composite light distribution of the projection module. The intermediate image plane is arranged in the optical path between the primary and secondary optics. The projection module has a heating element for heating the projection lens.

[0002] The present invention also relates to a method for manufacturing a projection lens for a projection module of a motor vehicle headlight, the projection lens being heated by means of a heating element.

[0003] The present invention also relates to a headlight for a motor vehicle. The headlight includes a housing having a light channel opening arranged in the light emission direction of the headlight. Background Technology

[0004] The type of projection module and motor vehicle headlight mentioned is known, for example, by JP 2007-242 291A. This proposes arranging a planar heating element for heating the headlight cover at any location within the headlight, except for the cover itself, the cover closing the light channel opening of the headlight housing. Figure 4 In this embodiment, the heating element is arranged on the outer surface of the projection lens, such that the heat generated by the heating element radiates towards the cover plate and heats the cover plate. Here, the planar heating element is applied to the outer surface of the projection lens by means of a coating process, such as vacuum phase deposition or sputtering deposition of ITO (indium tin oxide). Therefore, the planar heating element does not have discrete conductor circuits, but heats up uniformly across the entire surface when energized. The contact points of the planar heating element are applied, for example, by means of a conductive coating.

[0005] The disadvantage of the described projection module is that the application and contact of the heating element are very complex and expensive. Therefore, the described method has not been, and will not be, implemented in mass production in the future. Although the cited prior art is nearly 15 years old, in practice, conventional heating of the inside of the headlight cover by means of hot airflow is still used. Here, waste heat from electrical or electronic components or heat generated by a separate heating element within the headlight housing is used to heat the airflow.

[0006] However, these commonly used methods for defrosting headlights have limitations in headlights without cover plates. In these newer headlight designs, the projection module is arranged in the light channel opening of the headlight housing, and the projection lens forms the end of the headlight outward in the light emission direction. Because there is no cover plate, moisture (e.g., raindrops, fog, condensation, etc.) and ice (e.g., snow, ice, hail, frost, etc.) accumulate on the outer surface of the projection lens in such headlights. This effect is further amplified because the outer surface of the projection lens in such headlights is typically arranged in recesses where moisture and ice are particularly prone to deposit. Summary of the Invention

[0007] Based on the described prior art, the object of the present invention is to provide a simple, inexpensive, yet still effective method for defrosting the projection lens of the light module of a motor vehicle headlight, especially when the headlight does not have a cover plate for sealing the light channel opening of the headlight housing.

[0008] To achieve this objective, a projection module having the features of claim 1 is proposed. Specifically, a projection module of the type mentioned at the beginning is proposed in which the heating element has a transparent thin film made of an electrically insulating material and conductive circuits applied thereto or embedded therein, these conductive circuits being connected to a power source via a switching element, wherein the heating element is applied to or at least introduced into a portion of the projection lens itself, at least on a portion of the light incident surface and / or light exit surface of the projection lens of the projection module, such that when current is switched on through the conductive circuits, the heating element heats the projection lens.

[0009] This invention can be implemented in a particularly simple and inexpensive manner. Prefabrication and holding (Vorhalten) of a large number of heating elements is readily achievable. The manufactured heating elements then only need to be applied to the outer surface of the projection lens or introduced into the lens and electrically contacted during the production of the projection lens or projection module. The transparent film preferably has sufficient flexibility to accommodate the curvature or slight curvature of the outer surface of the projection lens. It is proposed herein that the projection lens is preferably designed as a cylindrical lens. This cylindrical lens has a light-emitting surface with a greater curvature about the cylindrical axis and a significantly smaller curvature about an axis extending transversely to the cylindrical axis. The curvature about the axis extending transversely to the cylindrical axis is preferably very small, particularly almost zero. Therefore, the light-emitting surface of the lens is flat or nearly flat in cross-section including the cylindrical axis. When the projection module is installed in a motor vehicle in operation, the cylindrical axis extends in a substantially vertical direction, that is, approximately transversely to the lane where the vehicle is parked or traveling. A cylindrical lens generally refers to a lens having two cylindrical surfaces. However, in the sense of this invention, a lens with a toroidal surface (i.e., a lens whose surface is annular) is also called a cylindrical lens.

[0010] Another advantage of the present invention is that it requires fewer parts to manufacture and contact the heating element, and that the heating element is easy to install on or in the projection lens.

[0011] The transparent carrier film is preferably made of plastic, such as transparent polycarbonate (PC). The plastic used should be UV-resistant and / or heat-resistant, and—at least when the heating element is applied to the outer surface of the projection lens—weather-resistant and / or acid-resistant. The durability of the plastic ensures that it will not become brittle or hardened, crack, or discolor due to UV radiation and weathering during its service life. For example, the use of Covestro AG from Leverkusen, Germany, is conceivable. UV 244 is used as a material for a carrier film. The thickness of the film is in the range of 100-600 μm, preferably in the range of 200-500 μm, and very particularly preferably in the range of about 350 μm.

[0012] The conductor circuit can be a conductor circuit printed on a transparent carrier film, for example, made of copper. However, preferably, the conductor circuit is formed by a heating wire that heats up when an electric current is present and releases heat to the projection lens, thus defrosting it. The heating wire is preferably made of a metal (e.g., copper). It preferably has a circular cross-section. However, other cross-sections (e.g., elliptical or rectangular cross-sections) are also conceivable. Without electrical insulation, the diameter of the heating wire is in the range of 10-100 μm, preferably in the range of 30-70 μm, and very particularly preferably in the range of 40-55 μm. An insulating material can be applied at least partially to the wire, for example, in the form of insulating varnish or plastic insulating material. With this insulating material, the diameter of the heating wire increases by about 20-30% or about 10-20 μm. Very particularly preferably, the diameter of the heating wire is 44 μm without insulating material, and 56 μm with insulating material. When the heating wires are uniformly distributed on or within the projection lens, the small diameter of the heating wires results in negligible light loss. In particular, the light loss is in the range of <1%. There is also no need to worry about uncontrolled scattering, refraction, or diffraction of light passing through the lens due to the heating wires.

[0013] It is conceivable to apply several individual conductor circuits onto or introduce them into the carrier film. The conductor circuits can, for example, be parallel or concentric. The ends of the individual conductor circuits can be led to a common switching element or power source. However, it is preferable to apply or introduce individual conductor circuits onto or into the carrier film in a meandering manner. The loops of the conductor circuits can, for example, be parallel or concentric. The ends of the conductor circuits can be led to a contact element, which can be part of a heating element. The contact element can be connected to a switching element or power source.

[0014] The heating element is applied to and fixed to the outer surface of the projection lens, for example, by means of bonding or adhesive. The adhesive is preferably transparent and heat-resistant in its cured state. UV resistance, weather resistance, and acid resistance of the adhesive are also advantageous. The carrier film of the heating element preferably has an adhesive layer on one side, through which the heating element can be fixed to the outer surface of the projection lens.

[0015] However, it is particularly preferred that, in the production of projection lenses, the heating element is placed in an injection molding tool using an injection molding process (i.e., injection molding), and then the lens material (e.g., glass or transparent plastic, such as PC, PMMA, etc.) is sprayed onto the heating element in the tool. The sprayed hot lens material preferably bonds with the material of the carrier film, ensuring an inseparable bond between the heating element and the projection lens after hardening. Preferably, a material-fit bond is formed between the transparent film and the projection lens, particularly a molten bond.

[0016] Alternatively, the heating element can be introduced into the projection lens between its two parts using a so-called co-molding process within the production scope of the projection lens. Introducing the heating element into the projection lens can be achieved, for example, in multiple steps within the production scope of the projection lens (steps known, for example, from DE 10 2010 033 902 A1). The contents of that publication are hereby incorporated into this application. Specifically, the first part of the projection lens can be manufactured in a first process cycle using an injection molding tool. The heating element is then placed on the first part in the injection molding tool, and in order to produce the other part of the projection lens, it is sprayed again with the lens material in a further process cycle. The two parts of the lens and the transparent film are also interconnected and form an inseparable bond after curing. In the finished projection lens, the various parts of the introduced heating element or the transparent film are no longer visible to the naked eye.

[0017] This objective is also achieved by a motor vehicle headlight having the features of claim 18. In particular, based on the headlight of the above type, a headlight is proposed to have a projection module according to the invention within the housing.

[0018] Particularly preferred is that the light channel opening of the headlamp housing is not closed by a cover plate, and the projection module (especially the projection lens) is sealed and isolated from the housing around the light emission direction of the headlamp. The advantages of the heatable projection lens of the light module according to the invention are particularly effective in headlamps without a cover plate, wherein the outer surface of the projection lens forms the end of the projection module or headlamp outward in the light emission direction of the headlamp. Direct and immediate heating of the projection lens ensures particularly effective defrosting and particularly rapid response behavior.

[0019] To seal the projection module or projection lens relative to the headlight housing, a waterproof, elastic material, such as plastic or rubber, is preferably used. Sufficient flexibility of the sealing material allows the projection module or projection lens to move relative to the headlight housing, for example, to achieve a vertical basic setting, headlight range adjustment, and / or dynamic turn signals. Alternatively, headlight range adjustment and / or dynamic turn signals can also be implemented electrically, wherein a semiconductor light source array, for example in the form of an LED array, is used as the light source for the light module, and the semiconductor light source is controlled in a targeted manner to turn it on, off, or dim it.

[0020] An advantageous variation of the invention proposes that the light source comprises at least one semiconductor light source, particularly at least one LED, preferably a multi-chip LED. Multiple LED semiconductor light sources can be arranged side-by-side and overlapped in a matrix to form an LED array. Light emitted by semiconductor light sources typically does not contain sufficient thermal energy (IR radiation component) to ensure heating of the projection lens or cover plate and defrosting of the light module or headlight without additional heating. Using the invention, particularly effective and simple defrosting of the projection lens of a motor vehicle headlight projection module can now be achieved, even if the light module has a semiconductor light source whose radiation has only a very small IR component.

[0021] According to a preferred embodiment of the invention, the conductor circuit of the heating element is led outward on the contact side of the transparent carrier film. The heating element can therefore be quickly and reliably connected to a switching element or power supply in a particularly simple manner. Contact surfaces can be formed at the ends of the conductor circuit on the contact side, which further simplifies the contact process.

[0022] According to another advantageous variation of the invention, a printed circuit board is fixed to a transparent film on the contact side, and the contact area of ​​the printed circuit board contacts the conductive circuit of the heating element. The printed circuit board can be designed to be flexible or rigid. Thus, the ends of the conductive circuit on the contact side of the carrier film are electrically contacted with the contact area of ​​the printed circuit board. This electrical contact can be achieved, for example, via conductive circuits formed on the printed circuit board in a manner known per se.

[0023] Printed circuit boards can be fixed to a transparent carrier film on the contact side in any way, especially by gluing, lamination, soldering (especially laser soldering), etc. Electrical contact between the conductor circuits of the heating element and the conductor circuits of the printed circuit board can also be achieved in any way, such as by fusion soldering (especially ultrasonic fusion soldering), welding, gluing, etc.

[0024] The contact area can, for example, have a contact surface applied to the printed circuit board, which further simplifies the contact process. The contact surface can be bonded to the printed circuit board, for example, using self-adhesive contact pads made of copper, and contacts the conductor circuit ends of the carrier film. The contact pads can be adhered around the printed circuit board, such that the rolled-edge contact pads adhere to both the top and bottom sides of the printed circuit board. This allows the heating element to contact simultaneously from both the top and bottom sides of the printed circuit board, achieving a particularly reliable and safe contact.

[0025] Furthermore, it is conceivable that the contact surface be applied directly to the carrier film, for example, which simplifies the contact process. The contact surface can be bonded to the carrier film, for example, using self-adhesive contact pads made of copper, and make contact with the conductive circuitry. The contact pads can be adhered around the carrier film, such that the rolled-edge contact pads adhere to both the top and bottom sides of the carrier film. This allows the heating element to contact simultaneously from both the top and bottom sides of the carrier film, achieving a particularly reliable and safe contact.

[0026] According to another preferred embodiment of the invention, a heating element is provided having a contact element that contacts a conductive circuit of the heating element, and the conductive circuit is connected via the contact element to a switching element or a power source. The contact element can be designed as a plug element. The plug element can be directly attached to a transparent carrier film on the contact side or attached to a printed circuit board (PCB) attached to the transparent carrier film on the contact side. The plug element can be designed as a plug or a socket. It can mechanically engage mating plug elements (sockets or plugs), wherein an electrical connection is automatically established between the plug elements. The plug element can be directly attached to the carrier film or the PCB. However, alternatively, the plug element can also be indirectly attached to the carrier film or the PCB via a wire. In the latter case, the plug element is movable relative to the carrier film and / or the PCB and can be positioned and aligned as needed to contact the switching element or the power source.

[0027] Alternatively, the contact element can have a contact surface that contacts the conductive circuitry of the heating element. This contact surface is applied to the contact side of a transparent carrier film, or to a circuit board fixed to the carrier film on the contact side. The contact surface can be bonded to the carrier film, for example, via self-adhesive contact pads made of copper, and contacts the ends of the conductive circuitry. The contact pads can be adhered around the carrier film, such that the rolled-edge contact pads adhere to both the top and bottom sides of the carrier film. Thus, the heating element can contact both the top and bottom sides of the carrier film simultaneously, achieving a particularly reliable and safe contact.

[0028] Electrical contact between the contact surface and the switching element or power supply can be made, for example, via a spring-loaded contact pin. The pin is compressed to its mounting size by applying force to its contact head. A spring installed inside the pin ensures that electrical contact is maintained between the pin head and the contact surface. The spring-loaded contact pin can be installed or placed in a lens holder (e.g., a suitable recess) that positions and holds the projection lens within the optical module. An annular stiftbund can be provided as a stop at the end position; the diameter of the stiftbund is slightly larger than the pin body. This stop ensures reverse support when the pins are pressed together, preventing the pins from retracting backward. When a projection lens with a heating element is mounted in the lens holder of the projection module according to the invention, the heating element can automatically engage via the spring-loaded contact pin.

[0029] Finally, it is proposed to arrange an opaque light-shielding element on the outside of the projection lens, covering the area of ​​the heating element outside the conductor circuit, particularly the contact area, through which the conductor circuit is connected to the switching element or to the power supply. The light-shielding element has, for example, a reflective or dark appearance when viewed from the outside. The light-shielding element can be a separate component, which is externally fixed to the light-emitting surface of the projection lens, for example by means of gluing, welding, clamping, latching, clipping, etc. It is also conceivable that the light-shielding element is designed as an opaque layer applied externally to the light-emitting surface of the projection lens. It is also conceivable that a separate light-shielding element is incorporated into the projection lens itself. This can be accomplished, for example, in multiple steps within the scope of the projection lens manufacturing process (steps known, for example, by DE 102010 033 902A1). The entire contents of this publication are hereby incorporated into this application. In particular, a first portion of the projection lens can be sprayed in a first process step. The light-shielding element is applied to this first portion, and in at least one additional process step, material for at least one additional portion of the projection lens is sprayed. In addition to the light-shielding element, the heating element can also be incorporated into the projection lens or applied to the light-incident surface of the lens. Crucially, the light-shielding element is positioned outside the heating element to protect the covered portion of the heating element from external visibility. Instead of an opaque element, the light-shielding element can be envisioned as translucent (e.g., in the manner of frosted glass). Attached Figure Description

[0030] Other features and advantages of the invention will now be explained in more detail with reference to the accompanying drawings. It should be noted that various features of the embodiments shown in the drawings may be essential to the invention even if not explicitly mentioned in the following description. Furthermore, any combination of features of the various embodiments may be essential to the invention, even if such combinations are not explicitly mentioned in the following description. The drawings show:

[0031] Figure 1 The light module of a motor vehicle headlight according to the present invention is shown;

[0032] Figure 2 A heating element is shown in a light module used in a motor vehicle headlight;

[0033] Figure 3 Top view, cross section AA, and detailed view Figure X It shows Figure 2 Heating element;

[0034] Figure 4 A printed circuit board is shown as part of a heating element;

[0035] Figure 5 Shown in a view from below Figure 2 and 3 The heating element, on which are fixed a Figure 4 Printed circuit boards in;

[0036] Figure 6 The heating element is shown in a view taken from above, on which are fixed... Figure 5 Printed circuit boards in;

[0037] Figure 7 The cross-sectional view shows that it is fixed with Figure 5 The heating element of the printed circuit board is applied to the inner surface of the projection lens of the light module of the motor vehicle headlight;

[0038] Figure 8 A view taken from the inside shows a heating element with a printed circuit board being applied onto a projection lens;

[0039] Figure 9 A heating element is shown in a light module used in a motor vehicle headlight.

[0040] Figure 10 Detailed illustration Figure 9 The heating element in the middle has a contact surface for the conductor circuit for electrical contact with the heating element;

[0041] Figure 11 A heating element is shown in a light module for a motor vehicle headlight, which has a plug element in the contact area;

[0042] Figure 12 Detailed illustration Figure 11 The heating element in the device has a plug element for electrical contact with the heating element's conductor circuit;

[0043] Figure 13 It shows Figure 9 The heating element in the middle has a printed circuit board fixed on it;

[0044] Figure 14 It shows Figure 13 Details of the heating element;

[0045] Figure 15 It shows Figure 13 The heating element has a plug element fixed to a printed circuit board;

[0046] Figure 16 Top view, section view AA and detailed view Figure X The heating element is shown;

[0047] Figure 17 It shows Figure 16The heating element has a printed circuit board with a plug element in the contact area fixed on it;

[0048] Figure 18 It shows Figure 16 The heating element has a plug element in the contact area that is directly fixed to the carrier film;

[0049] Figure 19 The projection lens of the projection module of a motor vehicle headlight is shown in a horizontal cross-sectional view. The projection lens has a heating element integrated into the lens.

[0050] Figure 20 Shown in vertical cross-section Figure 19 Projection lens;

[0051] Figure 21 The first process step is shown for producing according to Figure 19 Injection molds for projection lenses;

[0052] Figure 22 This illustrates the process used in subsequent steps to produce according to... Figure 19 Injection molds for projection lenses;

[0053] Figure 23 The projection lens is shown in a transparent view as observed from the outside;

[0054] Figure 24 The projection lens, which has a light-shielding element applied to its outer surface, is shown in an external view.

[0055] Figure 25 Another example of a heating element is shown in a light module for a motor vehicle headlight;

[0056] Figure 26 Shown in top view Figure 25 Details of the heating element with contact area;

[0057] Figure 27 A stereoscopic view viewed from an oblique angle is shown. Figure 26 Details;

[0058] Figure 28 A stereoscopic view shown from a downward angle is presented. Figure 26 Details;

[0059] Figure 29 It shows Figure 11 and 12 as well as Figures 25 to 28 A comparison of the contact areas of the heating elements;

[0060] Figure 30 A diagram showing the contact Figures 25 to 28 An example of a spring contact pin in the contact area of ​​a heating element, at its unforced length;

[0061] Figure 31 The length under compression is shown. Figure 30 Spring contact pin;

[0062] Figure 32 The diagram shows the contact between two spring contact pins and a plug element. Figures 25 to 28 Examples of heating elements;

[0063] Figure 33 The view shown from the outside is based on Figure 32 A lens holder with integrated spring contact pins and plug elements;

[0064] Figure 34 Shown in detail from the inside Figure 33 Lens support;

[0065] Figure 35 Shown from an external view Figure 33 A lens holder in which a projection lens is to be placed;

[0066] Figure 36 Shown in detail from the inside Figure 33 A lens holder in which a projection lens is to be placed;

[0067] Figure 37 Shown in detail from the inside Figure 33 The lens holder, in which the projection lens has already been placed; and

[0068] Figure 38 Shown in sectional view Figure 37 The lens holder already contains the projection lens. Detailed Implementation

[0069] An example of a projection module for a motor vehicle headlight according to the present invention is shown in... Figure 1 As shown in the figure, the projection module is generally indicated by reference numeral 2. The projection module 2 includes a light source for emitting light, which... Figure 1 The light source is located inside the projection module 2 and is therefore invisible. The light source preferably includes at least one semiconductor light source, such as an LED or laser diode, and particularly preferably an array of semiconductor light sources. The projection optics 2 also includes primary optics for focusing, shaping, and / or deflecting the light emitted by the light source. Figure 1The primary optics are not yet visible. They may include one or more reflectors or lenses. However, they may also include one or more additional optics that focus the light emitted by the light source by means of refraction at the light incident and / or light exit surfaces and / or by means of total internal reflection at the interfaces of the additional optics. Furthermore, the projection module 2 includes a secondary optics 4 in the form of a projection lens, which images an intermediate image of the intermediate image plane as the composite light distribution of the projection module 2 in the forward region in front of the vehicle along the light exit direction 6 of the projection module 2. The intermediate image plane is arranged in the optical path between the primary optics and the secondary optics 4. The projection lens is preferably designed as a cylindrical lens, wherein the light exit surface of the lens 4 has a large curvature about the cylindrical axis 60 and a small curvature about an axis extending transversely to the cylindrical axis 60. When the projection module 2 is installed in the vehicle in its operating state, the cylindrical axis 60 extends in a substantially vertical direction.

[0070] The projection module 2 is preferably arranged in a headlight housing, which has a light channel opening in the light emission direction 6. Light passing through the projection lens 4 is projected onto the lane in front of the vehicle through this light channel opening. The headlight housing preferably does not have a transparent cover that closes the light channel opening. Instead, the projection lens 4 forms the end of the headlight outward in the light emission direction 6. The projection lens 4 has a heating element for heating itself. The design of the heating element in the projection module 2 according to the invention and the manufacture of the projection lens 4 having such a heating element will be explained in more detail below.

[0071] To provide a simple, inexpensive, yet still effective method for defrosting the projection lens 4 of a projection module 2 for a motor vehicle headlight, particularly when the headlight does not have a cover for closing the light channel opening, it is proposed that the heating element 8 has a transparent carrier film 10 made of an electrically insulating material and a conductive circuit 12 applied to or embedded therein, which is connected to a power source 16 via a switching element 14. The power source 16 may be, for example, the vehicle's onboard battery. The current flowing through the conductive circuit 12 can be enabled or disabled via the switching element 14. The switching element 14 can be manually controlled, for example, by the driver of the motor vehicle, or automatically controlled, for example, based on the external temperature or the temperature of the light module 2 or the projection lens 4.

[0072] The heating element 8 is applied to at least a portion of the light incident surface and / or light exit surface of the projection lens 4 of the projection module 2, or is introduced into at least a portion of the projection lens 4 itself. When current flows through the conductor circuit 12, the heating element 8 heats the projection lens 4 and ensures effective defrosting.

[0073] Without a cover plate, the headlight and its light module 2 are at risk that the projection lens 4 will be at least partially covered by snow and ice in cold weather, resulting in complete or partial obstruction of light or incomplete or even complete failure of lane illumination. In some headlights, a washer is known that sprays antifreeze onto the cover plate or lens 4 of the light module 2, thus preventing it from being completely or partially blocked by snow and / or ice. However, washer equipment is complex and expensive to use, and its efficiency is not always guaranteed, especially in very low external temperatures.

[0074] To ensure that the light projected onto the lane by the uncovered headlights without significant light loss, even in cold weather, it is necessary to keep the exposed projection lens 4 free of snow and ice. This can be achieved by heating the lens 4 and maintaining it at a sufficiently high temperature, causing ice and snow to melt and / or not adhere.

[0075] For a light module 2 with a semiconductor light source emitting light with low infrared components, in the case of a headlight without a cover, the temperature on the external lens 4 is usually not high enough to prevent ice and snow from adhering to the lens 4. However, by using a targeted mechanism arranged directly on or within the projection lens 4, the temperature on the lens 4 can be increased to a level that prevents snow and ice from adhering. Preheating the lens 4 results in little or no precipitation (such as snow and ice) adhering to the outer surface of the lens and prevents too little light from being projected onto the lane.

[0076] The heatable projection lens 4 can be obtained by placing a carrier film 10 with integrated or applied heating wires 12 into an injection molding tool and spraying it with a transparent material (e.g., plastic, especially PC), the lens 4 being made of said transparent material. Figure 3 Heating element 8 is shown, wherein heating wire 12 is applied to carrier film 10. However, since the thickness of carrier film 10 is greater than the diameter of heating wire 12, heating wire 12 can also be integrated into film 10 without problems. In particular, heating wire 12 can be welded to carrier film 10 by means of ultrasonic welding. Heating wire 12 is heated by applying voltage to the exposed end 18 of heating wire 12. The generated heat 20 radiates to all sides and also heats the material around lens 4, ultimately causing the outer surface of lens to heat up. Sufficient heating prevents ice and snow from adhering to the heated surface.

[0077] The carrier film 10 is preferably composed of a transparent plastic (e.g., PC) in which fine heating wires 12, on the order of 50 μm, are introduced. These wires 12 have a plastic coating or some other type of electrical insulation material. If possible, the individual tracks or loops of the soldered wires 12 should cover a sufficiently large area on the film 10 to enable as uniform a heating of the optically effective surface of the lens 4 as possible, and to heat over the largest possible surface area. With uniform distribution of the paths or loops of the wires 12 on or within the projection lens 4, and with the wires 12 having a small diameter, light loss is very small (<1%), which is negligible in lighting technology.

[0078] Several possibilities can be envisioned for contacting the heating element 8 with the switching element 14 and / or the power supply 16. Figure 5 In the example, the film 10 is fixed to the printed circuit board 22, for example, by adhesive bonding. The adhesive bonding is... Figure 5 The figure is indicated by reference numeral 26. The printed circuit board 22 can be designed to be flexible or rigid. The printed circuit board 22 may be provided with a plug element 24, through which contact with the switching element 14 and / or the power supply 16 is facilitated. Uninsulated wire ends 18 are crimped / soldered to the printed circuit board 22. Conductor circuitry 28 is applied to the printed circuit board 22 and forms an electrical connection from the wire ends 18 to the contacts 30 of the plug element 24. This structure, consisting of the carrier film 10, heating wires 12, the fixed printed circuit board 22, and the plug element 24, forms the heating element 8 (see Figure 10). Figure 6 ).

[0079] The heating element 8 can be placed in a plastic injection molding tool and coated or injection molded with the material used to manufacture the projection lens 4. The lens 4, on which the heating element 8 is fixed, is... Figure 7 and 8 As shown in the diagram. The projection lens 4 and the carrier film 10 are preferably composed of the same material (e.g., PC). After curing, an inseparable material fit is created between the heating element 8 and the lens 4 by spraying or injection molding. This results in an optical lens 4 with an integrated heating element 8, which can be mounted onto the optical module 2. Here, the manufacture of the heatable projection lens 4, as well as the mounting and electrical contact of the lens 4 and the heating element 8 in the optical module 2, can be performed particularly quickly and easily. Active heating allows the lens surface oriented in the direction of travel to be heated, preventing ice and snow from blocking the light-emitting surface.

[0080] The material of the heating wire 12, the geometry of the wire 12 (e.g., diameter and length), the resistivity of the wire 12, as well as the applied voltage and the current flowing through it, affect the achievable heating power of the heating element 8. These parameters of the heating wire 12 can be selected individually depending on the specific circumstances.

[0081] Heating element 8 can be heated by means of voltage or current control or regulation to avoid overheating, which could damage the optical properties of lens 4 or the lens material. Electrical and / or electronic components required for control and / or regulation can be mounted on printed circuit board 22. These components include, for example, temperature sensors and / or microprocessors.

[0082] Alternatively, the plug element 24 can also be directly mounted onto the carrier film 10 (see [link]). Figure 11 and 12 In this case, a copper pad 32 can be provided at the end 18 of the heating wire 12. This copper pad 32 can be, for example, self-adhesively attached to the film 10 and connected to the uninsulated wire end 18, for example, by means of a low-temperature soldering process. The contacts 30 of the plug element 24 are connected to the copper pad 32, for example, by soldering (see...). Figure 12 Then, the heating element 8 is sprayed or injection molded within the production scope of the projection lens 4 using an injection molding process (molding or co-molding), as described above. The advantage of this implementation is that less installation space is required since there is no separate printed circuit board 22.

[0083] This can be achieved using a flexible printed circuit board 22 (see...) Figures 13 to 15 To achieve an alternative for the wires 12 used to apply voltage to the heating element 8, a flexible printed circuit board 22 is attached, for example, by lamination or adhesive bonding 26, to the contact side of the transparent film 10 with the integrated heating wires 12. The uninsulated wire ends 18 are then soldered to contact surfaces 32 provided for this purpose on the printed circuit board 22. The printed circuit board 22 has conductor circuitry 28 connecting the contact surfaces 32 to the contacts 30 of the plug element 24. Instead... Figure 15 The plug element 24 shown, along with multiple plug elements, can also be attached to the printed circuit board 22 and contact the wire end 18. An advantage of this implementation is that the flexible printed circuit board 22 can be folded, thus requiring only a reduced length for the heating element 8. This makes the structure of the lens 4, which has an integrated heating element 8 and is coated or injection molded, compact.

[0084] In the preceding embodiments, the current-carrying conductor circuit 12 of the heating element 8 is designed as a heating wire applied to or introduced into the carrier film 10. However, instead of these heating wires 12, printed strands 12a can also be used as current-carrying tracks (see [link to documentation]). Figures 16 to 18 This can be printed onto the transparent film 10, for example, by screen printing or by means of pad printing or inkjet printing. If conductive printing ink or paste is used, the printed strands 12a can be used as current-carrying tracks and, similar to heating wires 12, can be used to heat the projection lens 4 when a voltage is applied.

[0085] In this embodiment, the dimensional design of the printed conductor strands 12a is particularly important. On the one hand, it must provide a correspondingly low resistance (depending on the material used and the cross-sectional area of ​​the strands 12a) so that it can be easily and inexpensively applied to the film 10 while also providing the required heat output. To maintain the lowest possible light loss, the conductor strands 12a should be designed to be as narrow as possible. A width of approximately 0.5 mm for the strands 12a is still acceptable. The light loss would then be in the range of approximately 5%. This light loss can be compensated for by a higher current from the light source of the optical module 2. To apply a thickness (or height) of ink / paste to obtain a cross-section sufficient for the calculated resistance, this thickness should be greater than the typical thickness of screen printing, i.e., it should reach a thickness greater than 50 μm.

[0086] The electrical contact capability of the carrier film 10 having printed strands 12a as conductor circuits essentially corresponds to the embodiment described at the beginning having the carrier film 10 and heating wires 12 (see...). Figure 17 and 18 ).

[0087] The planar heating element 8 described above has been installed on one side (inner or outer side) of the projection lens 4 during the injection molding process (see...). Figure 7 Another possible implementation is to introduce the heating element 8 into the projection lens 4 itself by injection molding the material of the lens 4 onto both the inner and outer sides (see [link]). Figures 19 to 22 ).

[0088] This can be achieved using a multi-stage injection molding process. In a simpler case, the method is designed as a two-stage process. In the first stage, as described above, the carrier film 10 with integrated conductor circuitry 12 is coated with a material (e.g., plastic, particularly PC) layer 4.1, from which the projection lens 4 is composed (see...). Figure 21 Then, in the second stage, lens material 4.2 is sprayed onto the still free side of the carrier film 10 (see...). Figure 22 The use of lens material to injection mold the heating element 8 occurs in the injection molding tool, such as... Figure 21 and Figure 22 As shown. The first tool side is represented by W1, and the second tool side is represented by W2.

[0089] Particularly preferred is that, for the production of a projection lens 4 that can be heated by means of a heating element 8, the heating element 8—which takes the form of a transparent thin film 10 made of an electrically insulating material and conductive circuits 12, 12a applied thereon or placed therein—is applied to at least a portion of the light incident surface and / or light emitting surface of the projection lens 4 of the projection module 2, or is introduced into at least a portion of the projection lens 4 itself. For the introduction of the heating element 8 into the lens 4, it is proposed that...

[0090] -First, the first part 4.1 of the projection lens 4 is manufactured using injection molding tool W.

[0091] - Place the heating element 8 in the injection molding tool W (on the first part 4.1 of the projection lens 4, if available) and

[0092] - Another part 4.2 of the projection lens 4 is manufactured on the heating element 8 using an injection molding tool W.

[0093] The first tool plugin WE1 is preferred in the first stage ( Figure 21 ) and the second phase ( Figure 22 Replace the first part 4 with the second tool plug WE2. The second tool plug WE2 provides a recess 34 for spraying the second part 4.2 of the lens 4. The completed projection lens 4 surrounds the heating element 8 and leaves only the plug element 24 free so as to provide voltage to the heating element 8 or the conductor circuits 12, 12a.

[0094] Figure 23 The diagram shows a view of a projection lens 4 with an integrated heating element 8 disposed therein, relative to the light emission direction 6 (i.e., viewed from the outside). The transparent first portion 4.1 of the lens 4 and the heating element 8 and all its components 10, 12, 18, 22 behind it can be seen very clearly.

[0095] The contact areas of the heating element 8 (with the printed circuit board 22, conductor circuit 28, contact surface 32, and plug element 24) and the edges related to the production of the projection lens 4 can be covered by means of the light-shielding element 36 (cover, frame, or design portion) (see Figure 24The light-shielding element 36 can be opaque or translucent. An opaque light-shielding element 36 may be, for example, silver or black. The light-shielding element 36 can be a separate component, which is fixed to the outer surface of the lens 4, for example, by gluing or welding. It is also conceivable that the light-shielding element 36 be applied as a coating to the outer surface of the lens 4, for example, by spraying or dipping. Finally, it is also conceivable that, within the scope of a multi-stage manufacturing process, the light-shielding element 36 is applied as one of several components of the lens 4 by injection molding. For this purpose, the light-shielding element 36 can first be placed in an injection molding tool and sprayed with a first layer 4.1 of the material of the lens 4. Then, the heating element 8 is placed on the first layer 4.1 and sprayed with a second layer 4.2.

[0096] The following is based on Figures 25 to 29 Another possibility for contacting the heating element 8 is described. In this embodiment, the plug element 24, which rests directly on the carrier film 10, is eliminated. Although in the previously described embodiment, the plug-in connection is achieved directly on the film 10 by means of the plug element 24 (receptacle housing and plug housing), in this embodiment, the electrical contact with the switching element 14 and / or the power supply 16 is provided by contact pads (see...). Figures 26 to 28 The coating is applied to the contact pins (see 30 to 32) on the film 10, and the contact pads are applied directly to the film 10. The advantages lie in the simple and inexpensive manufacture of the heating element 8 and the simple yet reliable integration (mechanical fastening and electrical contact) of the projection lens 4 into the projection module 2. Furthermore, this implementation requires particularly few components and less space in the optical module 2. This reduces weight and opens up new styling possibilities for the optical module 2.

[0097] Figure 25 The aforementioned carrier film 10, made of plastic, is shown, having an applied or integrated conductor circuit 12 (e.g., heating wire or printed strand). The ends 18 of the conductor circuit 12 are guided to the side edges on the contact side of the film 10. Figure 26 The contact pad 38 is shown, which may be composed, for example, of copper foil. The contact pad 38 may be self-adhesive, allowing it to be easily attached to the carrier film 10 and to contact the conductor circuit 12 or its end 18 in the contact area of ​​the film 10. The wire end 18 may be soldered to the contact pad 38. The lateral protrusion 38a of the contact pad 38 may be folded back and secured to the back side of the carrier film 10 (see [reference]). Figures 26 to 28 The folded contact pads 38 and their contact surfaces on the front and back sides of the thin film 10 provide suitable surfaces for electrical contact connections. This results in a significantly narrower contact area 40 compared to the embodiments described above, because the plug element 24 occupies relatively more space in the previous embodiments (see...). Figure 29Specifically, the contact area 40 is reduced to approximately 35% of the previous value (e.g., only 7 mm instead of the previous 20 mm).

[0098] The contact pad 38 can make electrical contact using a spring contact pin 42. By applying a force F (pressure) to the contact head 44 of the pin 42, it is compressed (length l1 minus length l2) to the mounting size. Figure 30 The length of pin 42 before force is applied (original) is shown. Figure 31 The compressed length (final assembly length) is shown. Establishing and maintaining contact between the pin head 44 and the contact pad 38 is ensured by a spring element mounted inside the pin 42. The diameter of the contact surface of the pin head 44 or the entire pin 42 and the pin length can be designed as needed or selected from existing standard sizes from a suitable supplier. The contact force or spring force F can also be specially designed or selected from standard versions. Here, for example, a pin 42 diameter D of 1.5 mm and a contact surface length of 1.767 mm are proposed. 2 (π*(d / 2) 2 ).

[0099] For this application, contact pin 42 and fixing cable 46 already assembled in plug housing 24a can be used (see [link]). Figure 32 During further installation, pin 42 is inserted into the appropriate recess 48 in the lens holder 50 and secured therein (see...). Figure 33 Lens bracket 50 is used to secure the projection lens 4 to the projection module 2. A pin collar 52, with a diameter slightly larger than the pin body, serves as a stop at the end position. This stop 52 ensures that when the pins 42 are pressed together, there is reverse support and the pins 42 cannot retract backward. The plug 24a can be fixed to the lens bracket 50 in any area remote from the lens 4, for example, by means of a clip (see [link to plug 24a]). Figure 34 To keep the contact pin 42 in a lateral position within the recess 48, the cover 54 can be secured (see...). Figure 34 and 36 Other fastening possibilities, with or without additional fastening or fixing components, are also conceivable.

[0100] In a subsequent step, a projection lens 4 with an integrated heating element 8 can be applied to the lens holder 50 (see [link]). Figure 35The projection lens may have a sealing seat 56 that, when placed on the lens holder 50, enters a sealing channel 58 formed on the lens holder 50. The sealing channel 58 may be pre-filled with an adhesive or sealant (e.g., butyl). The sealing seat 56 may extend over the entire circumference of the lens 4. At least in this case, the sealing channel 58 extends over the entire circumference of the lens 4. By pressing the sealing seat 56 into the sealing channel 58 and after the adhesive or sealant has hardened, the projection lens 4 is almost inseparably fixed to the lens holder 50. Alternatively, the lens 4 may also be fixed to the lens holder 50 in other ways, such as by means of a retaining spring, laser welding, etc.

[0101] In this mounting position, the lens 4 compresses the spring contact pin 42 to a predetermined final size. This creates a permanent spring-loaded contact between the contact pad 38 located inside the lens 4 and the contact surface 44 of the pin head, enabling electrical contact for the heating element 8 integrated into the lens 4. Contact is automatically established when the lens 4 is mounted on the lens holder 50. This allows the contact point 38 to also be placed in hard-to-reach or inaccessible areas.

Claims

1. A headlight for a motor vehicle, comprising a housing having a light channel opening arranged along the light emission direction (6) of the headlight, wherein, The headlight has a projection module (2) in the housing, the projection module (2) comprising: a light source for emitting light; a primary optics for focusing, shaping and / or deflecting the light emitted by the light source; and a secondary optics (4) in the form of a projection lens, the secondary optics (4) imaging a composite light distribution of the projection module (2) in the front region in front of the vehicle along the light emission direction (6) of the projection module (2), the intermediate image plane being arranged in the optical path between the primary optics and the secondary optics (4), wherein the projection module... Block (2) has a heating element (8) for heating the projection lens, the heating element (8) being connected to a power source (16) via a switching element (14), wherein the heating element (8) has a transparent film (10) made of an electrically insulating material and a conductive circuit (12) applied thereto or embedded therein, the heating element (8) being applied to or introduced into at least a portion of the light incident surface and / or light exit surface of the projection lens of the projection module (2) such that when current is switched on through the conductive circuit (12), the heating element (8) heats the projection lens. Its features are, The light channel opening of the housing is not closed by the cover plate, and the projection module (2) is sealed and isolated from the housing around the light emission direction (6) of the headlight.

2. The headlight according to claim 1, characterized in that, The projection lens forms the end of the projection module (2) outward in the light emission direction (6).

3. The headlight according to claim 1, characterized in that, In the production of the projection lens, the heating element (8) is applied to the light incident surface and / or light exit surface of the projection lens or introduced into the projection lens itself by means of injection molding or co-injection molding.

4. The headlight according to any one of claims 1 to 3, characterized in that, The light source includes at least one semiconductor light source.

5. The headlight according to any one of claims 1 to 3, characterized in that, The transparent film (10) is made of plastic.

6. The headlight according to any one of claims 1 to 3, characterized in that, The projection lens has the form of a cylindrical lens, and the light emitting surface of the projection lens has a large curvature around the cylindrical axis (60) and a small curvature around an axis extending transversely to the cylindrical axis (60).

7. The headlight according to claim 6, characterized in that, When the projection module (2) is installed on a motor vehicle in operation, the cylindrical axis (60) extends in the vertical direction.

8. The headlight according to any one of claims 1 to 3, characterized in that, The conductor circuit (12) of the heating element (8) is led outward on the contact side of the transparent film (10).

9. The headlight according to claim 8, characterized in that, The printed circuit board (22) is fixed to the transparent film (10) on the contact side, and the contact area (28; 40) of the printed circuit board (22) is in contact with the conductor circuit (12) of the heating element (8).

10. The headlight according to any one of claims 1 to 3, characterized in that, The heating element (8) has a contact element that contacts the conductor circuit (12) of the heating element (8) and the conductor circuit (12) is connected to the switching element (14) or the power supply (16) via the contact element.

11. The headlight according to claim 9, characterized in that, The heating element (8) has a contact element that contacts the conductor circuit (12) of the heating element (8) and the conductor circuit (12) is connected to the switching element (14) or the power supply (16) via the contact element.

12. The headlight according to claim 11, characterized in that, The contact element is designed as a plug element (24) fixed on the printed circuit board (22).

13. The headlight according to claim 10, characterized in that, The contact element has a contact surface (38; 32) that contacts the conductor circuit (12) of the heating element (8), wherein the contact surface (38) is applied to the printed circuit board (22) on the contact side of the transparent film (10), or the contact surface (32) is applied to the printed circuit board (22) of the transparent film (10) on the contact side of the transparent film (10).

14. The headlight according to any one of claims 1 to 3, characterized in that, A light-shielding element (36) is arranged on the outside of the projection lens, and the light-shielding element (36) covers the area of ​​the heating element (8) outside the conductor circuit (12).

15. The headlight according to claim 14, characterized in that, The area is a contact area (40), through which the conductor circuit (12) is connected to the switching element (14) or the power supply (16).

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