DE102023125595B3 - Light-emitting system with homogeneous and diffused light; vehicle comprising the same and manufacturing method therefor - Google Patents

Abstract

The present disclosure relates to a light-emitting system (1) for an automotive application, comprising: at least one light source; at least one mask (5); at least one lens (3); and at least one adhesive (7) for scattering light to provide substantially homogeneous illumination. It also relates to a vehicle comprising at least one such light-emitting system and a method for manufacturing at least one such light-emitting system.

Description

The present disclosure relates to a light-emitting system for an automotive application according to the preamble of claim 1. It also relates to a vehicle having at least one such light-emitting system and a method for manufacturing such a light-emitting system.

Vehicles, such as passenger cars, vans, and trucks, include various vehicle interior and exterior lighting components that can emit light for different purposes. Aesthetic features that have become desirable in automotive applications are intended to provide exterior and/or interior badges and/or emblems, or the like, on vehicles or specific parts of a vehicle. Such aesthetic features backlight important features of the badge or emblem in question or are illuminated for visual or safety aspects. In particular, manufacturers are looking for ways to make their vehicles more appealing to customers by creating a premium atmosphere. For example, the instrument panel, the entire door panel, or parts thereof may be illuminated in such a manner. It is desirable for these elements to be backlit with a uniform (uniform or homogeneous) brightness using, for example, light-emitting diodes (LEDs). An LED is a directional light source with a relative luminous intensity that decreases with increasing viewing angle. This may result in an external viewer of the badge perceiving bright spots or hotspots.

Light-emitting systems that provide uniform light intensity are known, such as systems that typically utilize complex lens and reflector arrangements. Highly diffuse lenses have the disadvantage of appearing milky or cloudy, having poor optical efficiency, and/or being expensive. Optical features can also be used on clear materials to diffuse light, but these have the disadvantage that the optical features are visible when unlit, which is undesirable. A desirable feature of a light-emitting system is that the input of the light source, such as an LED, is not directly visible to the external observer.

Consequently, it is convenient to conceal any illuminant of light-emitting systems, i.e., such that the illuminant is not visible from the outside but only after the illuminant has been illuminated. Such a system is known as a Hidden-Till-Lit (HTL) system. Reflective metal coatings that provide such features are known, for example, from WO 2011/075796 and WO 2013/110122 Such prior art HTL systems present several problems, such as light leakage along the lens and light guide walls and/or the appearance of double images. Furthermore, these systems may be less flexible. Furthermore, known HTL systems require a multitude of separate elements, adding design and assembly complexity and increasing costs.

The US 10 969 080 B2 discloses a multi-function lamp unit for a vehicle, comprising a housing, at least one light guide together with at least one light source disposed at least partially within the housing, and a clear lens substantially enclosing the housing, the at least one light guide and the at least one light source, the lens having an inner surface, an outer surface disposed opposite the inner surface, and a continuous transparent and/or transmissive coating on the outer surface.

The EP 4 105 678 A1 relates to an illuminated cover for an electromagnetic sensor, such as a radar sensor, wherein the cover comprises a multilayer plate that is substantially transparent to the electromagnetic radiation emitted and/or received by the electromagnetic sensor, and the plate comprises a first layer of optically transparent material and, on at least one surface of the first layer, a second layer having a lower refractive index than the first layer. Further, a graphics layer is provided on the second layer and at least one light source is arranged to couple light into the first layer, which acts as a light guide, wherein at least one surface of the first layer is further provided with at least one optical element for coupling light out of the first layer.

The DE 20 2019 005 311 U1 relates to a system with a lighting assembly for a design element, in particular configured for a vehicle element, comprising: at least one light guide; at least one light source arranged at least partially within an interior of the system, wherein the at least one light source is configured to emit light based at least on receiving electrical energy from an electrical energy source, wherein the at least one light source is arranged adjacent to and directed towards the at least one light guide; a lens which illuminates the interior, the at least one light guide and which substantially encloses at least one light source, the lens having an inner surface, an outer surface opposite the inner surface, and a continuous transparent and translucent coating on the outer surface.

The WO 2021/038082 A1 relates to a system comprising a lighting assembly for 360° illumination of a design element, in particular configured for a vehicle design element, comprising: one or more light guides, each light guide comprising a core, and two or more light guides and two end portions of a light guide at least partially overlapping, thereby providing at least one overlap region to substantially close a loop; one or more light sources at least partially disposed within an interior of the system, each light source configured to emit light based on receiving at least electrical power from an electrical power source, and each light source being adjacent to and directed toward at least one of the one or more light guides.

The EP 3 026 471 A1 relates to an optical device comprising a light source and an optical object. The optical object comprises a light guide and a viscoelastic layer disposed on the light guide. Light emitted by the light source enters the light guide and is transported within the light guide by total internal reflection. The viscoelastic layer controls the light.

The US 2010/0157615 A1 relates to architectural lighting comprising a light source and a waveguide having a front and a rear surface. The waveguide is arranged relative to the light source such that light from the light source is input into and guided within the waveguide. The waveguide may include a plurality of deflection devices for deflecting the light guided in the waveguide out of the front surface, as well as one or more mounting devices for attaching the luminaire to an architectural structure.

Given the disadvantages of the prior art, it is desirable to have an effective solution for providing homogeneous light emission along parts of a vehicle, especially those with complex geometries and/or narrow cross-sections, such as logos and/or decorative stripes. Consequently, it is an object of the present disclosure to further develop the known light-emitting system to overcome the disadvantages of the prior art.

This object is achieved by the characterizing features of claim 1. Preferred systems of the present disclosure are described in claims 2 to 14.

Consequently, the light-emitting system comprises at least one adhesive for scattering light to provide substantially homogeneous illumination of the light-emitting system.

According to one aspect, the light source may be adapted to emit light into at least one light guide, which is preferably included in the light-emitting system and at least partially arranged in an interior of the light-emitting system; the lens may have at least one inner surface substantially aligned with the light guide and at least one outer surface substantially opposite the inner surface, wherein preferably the outer surface emits light directly or indirectly from the light-emitting system, and the lens and the mask form a lens-mask system, wherein parts of the lens-mask system are translucent and parts of the lens-mask system are non-translucent; and/or the lens-mask-adhesive system may be a three-layer system, wherein preferably the inner surface of the lens is substantially covered by the mask and the adhesive.

In one aspect, the adhesive may scatter light from the light guide; light from the light guide may pass through the adhesive and then through the lens; the lens may substantially enclose the light guide and the light source; and/or the lens, mask, and adhesive may form a lens-mask-adhesive system in which the mask, adhesive, and lens are permanently attached to one another and are not interchangeable.

According to a further aspect, the mask may be opaque and/or the mask has a continuous transparent and/or translucent coating on the outer surface, wherein the continuous transparent and/or translucent coating is at least partially transparent to at least some light emitted by the light source and passing through the lens.

Embodiments of the present disclosure may be provided with the adhesive comprising insoluble particles that substantially provide the light scattering effect of the adhesive.

Embodiments of the present disclosure may require that the insoluble particles comprise PMSQ beads, PMMA beads, and/or glass beads.

According to a further aspect, the adhesive is formed in at least one droplet-like or substantially square or substantially round or substantially triangular-like shape and/or the adhesive may be substantially pinstripe-like or bead-like or spherical along at least a portion of the length of the lens.

It is also possible that the adhesive is a single-component or multi-component adhesive; and/or the adhesive is a pressure-sensitive adhesive, a temperature-sensitive adhesive, an anaerobic adhesive and/or a combination thereof; and/or the adhesive comprises fillers, such as ethylene glycol dimethacrylate and/or multifunctional monomers.

In further embodiments of the present disclosure, the adhesive may be a one-component adhesive and may cure through the use of UV light, heat, an anaerobic environment, moisture, and/or contact with oxygen.

In a further embodiment, the adhesive may comprise acrylic, polyester, silicone, styrene copolymer and/or vinyl, preferably methacrylate and most preferably thixotropic methacrylate.

According to a further aspect, the adhesive may affect a color shift of the transmitted light, wherein the color shift is preferably corrected by pigmenting the lens and/or selecting a colored lens and/or tuning and/or calibrating the light source to the shifted color.

It is also possible that the light source comprises at least one LED and the color shift is preferably corrected by LED bin selection, wherein, preferably in the case of essentially white light, LED binning is selected up to several color bins cooler or warmer than the desired emitted light color.

In further embodiments of the present disclosure, the light source may be arranged adjacent to and aligned with the at least one light guide.

In a further embodiment, the lens-mask system can be formed as one part by 2K injection molding.

In yet another embodiment, the lens-mask system is formed as one part by 3K injection molding.

Furthermore, a vehicle is provided with at least one light-emitting system as shown above.

Furthermore, a method for producing the light-emitting system as presented above is provided, comprising the steps of: providing at least one adhesive, preferably by mixing light-scattering particles, such as PMSQ and methacrylate, particularly preferably thixotropically modified methacrylate, using at least one mixer, preferably in the form of a centrifugal-planetary mixer, in particular for removing and preventing the admixture of air bubbles; providing the mask and the lens, preferably by 2K injection molding; applying the adhesive to the mask and the lens using a robot with an attached dispensing gun, wherein the dispensing gun is directly fed with the adhesive under high pressure, preferably between 2 and 10 bar, particularly preferably between 4 and 6 bar, most particularly preferably between 2 and 3 bar; and adjusting the robot speed and application rate to control the thickness of the adhesive, wherein the thickness of the adhesive is preferably between 1 mm and 2 mm and the robot speed is preferably between 38 mm/s and 85 mm/s and/or a dispensing gun supply voltage is preferably between 4 V and 10 V.

In a further embodiment of the method, feeding of the dispensing gun may be enabled via a recirculating feeding system to keep the light-scattering particles within the adhesive, and/or the robot speed and deposition rate may be varied at different points along the length of the lens, wherein the thickness of the adhesive may preferably be adjusted by varying the robot speed and/or the gun supply voltage.

Furthermore, an additional method for manufacturing the light-emitting system as set forth above is provided, comprising the step of providing the lens, the mask and the adhesive by 3K injection molding.

Adhesives are typically used to bond two separate surfaces together. However, in some applications, due to limitations of the injection molding process, such as filling narrow cross-sections, it is not possible to mold the diffuse layer together with the clear lens and the opaque mask. In this case, the present disclosure proposes the use and production of an adhesive for scattering light in an automotive application. This includes a Dispersion of insoluble particles for the production of a curable, light-scattering adhesive.

To initiate the bonding of an adhesive, an internal chemical reaction is required; this reaction varies depending on the type of adhesive. Common types in the industry include multi-component adhesives, single-component adhesives, pressure-sensitive adhesives, temperature-sensitive adhesives, and anaerobic adhesives. A person skilled in the art will be able to select the right adhesive based on the application and manufacturing requirements.

Limitations inherent in the injection molding process, such as filling narrow cross-sections for lighting applications, are overcome by the present disclosure. Single-component adhesives, particularly UV-curable adhesives, offer manufacturing advantages because they require only a single dispensing nozzle and cure quickly, making them preferable for processing applications.

These adhesives may also contain fillers, such as multifunctional monomers, to provide various characteristics such as chemical resistance, viscosity changes, curing speed, and bond strength. For example, copolymerization of ethylene glycol dimethylacrylate results in optical and viscosity changes in methyl methacrylate-based adhesives. Various additives can be used to tailor the chemical composition according to the application. Methyl methacrylate may be preferred with additives to provide a refractive index similar to the lens substrate and 30,000 to 60,000 cP at 2.5 rpm.

However, in an application with complex geometry, a methacrylate-based adhesive may be preferable due to its controllable viscosity with additives and its chemical compatibility with polycarbonate, which is often used as a substrate for a lens.

Different materials have unique optical properties that can affect light transmission, transmitted color, and light scattering. Using transmission and thickness proportionality, brightness can be varied by regulating the applied thickness of the adhesive. To provide a tapered light guide, the adhesive can be applied at a gradually changing thickness (e.g., from thick to thin) to change the brightness through the lens, preferably with a pinstripe shape. This is intended to achieve homogenized delivery for a light guide that has hotspots and decreasing brightness along its length; furthermore, it can also be used to minimize/remove hotspots from direct light sources such as LEDs.

The disclosure also relates to a vehicle having at least one such light-emitting system and a method for producing at least one such light-emitting system according to claims 16 to 18.

• 1 eine schematische Darstellung eines lichtemittierenden Systems gemäß einer beispielhaften Ausführungsform der vorliegenden Offenbarung veranschaulicht; und
• 2 eine schematische Darstellung der Teilquerschnittsansicht eines lichtemittierenden Systems gemäß einer beispielhaften Ausführungsform der vorliegenden Offenbarung veranschaulicht.

It should be understood that each of the features of the disclosure may be used separately or in combination with other features. The present disclosure itself, together with other features and related advantages, will become apparent from consideration of the following detailed description taken in conjunction with the accompanying drawings. One or more embodiments of the present disclosure are described below by way of example only, wherein like reference numerals represent like elements, and wherein:

• 1 illustrates a schematic representation of a light-emitting system according to an exemplary embodiment of the present disclosure; and
• 2 illustrates a schematic representation of the partial cross-sectional view of a light-emitting system according to an exemplary embodiment of the present disclosure.

Furthermore, the drawings referred to in this description are not to be understood as being to scale unless expressly stated, and these drawings are by their nature only illustrative.

Before embodiments of the present disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangements of components set forth in the following description or illustrated in the drawings. Other embodiments of the disclosure are conceivable, and it may be practiced and implemented in various ways. Those skilled in the art will appreciate that, in the interest of clarity and understandability, not all features of an industrial embodiment are shown. Furthermore, those skilled in the art will appreciate that the development of an actual industrial embodiment incorporating aspects of the present disclosures requires many implementation-specific decisions to achieve the designer's ultimate goal for the industrial embodiment. While these efforts may be complex and time-consuming, they would nevertheless be routine for one skilled in the art having the benefit of this disclosure.

Furthermore, it should be understood that the phraseology and terminology used herein is for descriptive purposes and should not be considered limiting. For example, the use of a singular word, such as "a," is not intended to limit the number of positions. Furthermore, the use of relational terms, such as, but not limited to, "top," "bottom," "left," "right," "upper," "lower," "downward," "upward," and "side," which are used in the description for clarity with specific reference to the figures, is not intended to limit the scope of the disclosure or the appended claims. Further, it should be understood that each of the features of the disclosure may be used separately or in combination with other features. Other systems, methods, features, and advantages of the disclosure are and will become apparent to those skilled in the art upon examination of the figures and the detailed description. All such additional systems, methods, features, materials, chemicals, and advantages are intended to be included in this description, to be part of the scope of the present disclosure, and to be protected by the appended claims.

One skilled in the art will recognize that changes could be made to the above-described embodiments without departing from the broad concept of the present disclosure. Accordingly, it is to be understood that the disclosure disclosed herein is not limited to the specific embodiments disclosed, but is intended to cover modifications that fall within the scope and spirit of the present disclosure as defined by the appended claims.

According to the embodiment of 1 The light-emitting system 1 is formed from a three-layer system, wherein one layer is a clear lens 3 to allow the transmission of light, one layer is an opaque mask 5 to create the desired hidden-till-lit designs (together with the lens 3 and a possible coating of the lens 3), and one layer is the scattering layer in the form of an adhesive 7 to achieve homogeneous light emission along the lens 3, eliminate hotspots near the light entrance into one or more light guides, and locally control the brightness of complex designs, such as logos or decorative stripes. Consequently, the adhesive 7 scatters the light from a light guide to provide substantially homogeneous illumination of the light-emitting system 1. Furthermore, the lens 3, the mask 5, and the adhesive 7 form a lens-mask-adhesive system in which the mask 5, the adhesive 7, and the lens 3 are permanently attached to each other and are not interchangeable. The light from the light guide passes through the adhesive 7 and then through the lens 3.

A lens 3 according to this disclosure may be provided in various shapes. Accordingly, the subject matter of the present disclosure includes round, lenticular, or pinstripe-shaped configurations. Furthermore, the lens 3 has at least one inner surface 2 substantially aligned with the light guide and at least one outer surface 4 substantially opposite the inner surface 2. The outer surface 4 emits light directly or indirectly from the light-emitting system 1.

The lens of this disclosure may be formed from any suitable plastic material. For example, the lens may be formed from a material selected from the group consisting of, but not limited to, acrylonitrile-ethylene-styrene (AES), acrylonitrile-butadiene-styrene (ABS), acrylonitrile-styrene-acrylate (ASA), polyamide (PA), polybutylene terephthalate (PBT), polycarbonate (PC), polyethylene (PE), polyethylene terephthalate (PET), poly(methyl methacrylate) (PMMA), polyoxymethylene (POM), polypropylene (PP), polyurethane (PU), polyvinyl chloride (PVC), fast-flowing AES, acrylonitrile-(ethylene-propylene-diene)-styrene (AEPDS), blends of thermoplastics, or PC-ABS thermoplastic blend. In a preferred embodiment, the lens is made from polycarbonate.

In preferred forms, the lens may have a maximum physical thickness in the range of 0.1 mm to 20 mm, more preferably in the range of 1 mm to 5 mm, and most preferably in the range of 2 mm to 3 mm, but is not limited thereto.

According to the embodiment of 1 the lens 3 is made of polycarbonate and may be coated with a decorative and/or functional coating, preferably on the outer surface 4, such as to color at least one surface of the lens 3 and/or to support the HTL function and/or to modify the light emission of the lens 3. Preferably, the outer surface 4 has at least one of a continuous transparent or translucent coating, wherein the continuous transparent or translucent coating is transparent to at least some light emitted by the light source and passes through the lens 3, is at least partially permeable.

For the embodiment of 1 The mask 5 is an opaque mask and creates an opening to create the designed illumination pattern (e.g., a decorative stripe or a logo). Furthermore, the adhesive 7 can be a dispersion comprising insoluble particles that essentially provide the light-scattering effect of the adhesive 7.

According to the embodiment of 1 The lens 3 and the mask 5 are formed as one component, with the adhesive 7 being applied in a separate manufacturing step. In this embodiment, a one-component adhesive 7 cured by UV light is used. One-component adhesives 7, particularly UV-curable adhesives, have the manufacturing advantages of requiring only a single dispensing nozzle and curing quickly, making them advantageous for processing applications.

UV-curable adhesives typically consist of various monomers and photoinitiator molecules that are activated and decompose when they absorb energy emitted by UV light. The activated molecules produce free radicals that initiate and accelerate the linking reaction that produces a cured polymer. These monomers or chemicals are typically based on acrylic, polyester, silicone, styrene copolymer, or vinyl. Each chemical base has different uses, but acrylic-based adhesives are typically used due to their chemical compatibility and bond strength. All suitable chemicals known to those skilled in the art are included in this disclosure.

According to further embodiments, one-component adhesives cure through the use of heat (known as hot melt adhesives), moisture, and contact with oxygen.

Adhesives 7 may also contain fillers, e.g., in the form of multifunctional monomers, to provide various characteristics such as chemical resistance, viscosity control, curing speed, and bond strength. According to the embodiment of 1 Methacrylate was chosen as the adhesive 7 due to its controllable viscosity with additives, for example, ethylene glycol dimethacrylate (may be required for complex geometry) and chemical compatibility with polycarbonate, which is the substrate of the lens 3. The selected adhesive 7 is strongly influenced by, for example, the intended manufacturing process and the part geometry. Consequently, other chemicals may be used in other cases and are thus similarly included in this disclosure.

Materials exhibit unique optical properties that can affect light transmission, transmitted color, and light scattering. Light scattering can be achieved by scattering light rays at different angles, typically increasing the amount of transmitted light as these angles decrease. This proportionality between scattering and transmission can be used to determine a required size, e.g., bead thickness, and/or amount of light-scattering particles of the adhesive 7. Due to the liquid state of the adhesives 7 during manufacturing, the amount of scattering can be regulated by incorporating light-scattering particles.

For the embodiment of 1 Adhesive 7 essentially exhibits high transmission and minimal color shift, while providing homogeneous illumination.

By incorporating light-scattering particles into an adhesive 7, the optical properties of the materials are altered. The additive particles utilize their material type and shape to alter the transmitted light and color. In general, any material that does not dissolve in the adhesive but is present in solid form or as liquid droplets can be used. Polymeric materials such as PMSQ beads, PMMA beads, or glass beads can be advantageously used. PMSQ, PMMA, and glass beads have been found to be chemically stable within various epoxies, e.g., methyl methacrylate (MMA), urethane acrylate, and other two-part epoxies, such as 650 Series Two-Part Epoxy.

By regulating the amount of additive(s), preferably between 0.1 wt% to 10 wt%, more preferably between 0.5 wt% to 2 wt%, most preferably at substantially 1 wt%, mixed into a material, the overall optical properties can be tuned. For example, by mixing 1 wt% of PMSQ beads into methyl methacrylate, the optical transmission is reduced by 11.5% and the haze is increased by 23.4%, evaluated at a thickness of 2 mm. According to the embodiment of 1 PMSQ beads were selected for their UV stability and resistance to yellowing at temperature.

Adjusting the volume of scattering particles within the adhesive 7 can improve the homogeneity nity and brightness of hotspots generated by the light guide and hotspots caused by the ambient light guides at the ends of the light guide, directly produced by the nearby light source.

Using the transmission and thickness proportionality, the brightness can be varied by adjusting the thickness of the adhesive 7. Changing the adhesive thickness from 1 mm to 2 mm can result in a transmission reduction of approximately 8.35% and a haze increase of approximately 9.3%. Due to this relationship, different geometries of the adhesive layer result in increased/decreased brightness.

For example, a square adhesive profile in a thin decorative strip will result in a homogeneous light output because the optical area of the adhesive is constant. For larger and/or thicker adhesive profiles, a triangular profile can be used to accommodate intensity at larger angles from the light source.

According to the embodiment of 1 and 2 , which aims at reducing the size of the light guide, the adhesive 7 is applied with a gradually changing thickness (e.g., from thick to thin) in order to change the brightness through a decorative strip. The arrangement of the substrate of the lens 3 in a complex geometry and applied with a gradually changing thickness of the adhesive 7 is shown in the 1 2 respectively. This thickness of the adhesive can be determined based on the optical properties of adhesives with/without optical additives, such as PMMA, PMSQ, or glass beads.

This ability to adjust the thickness of the adhesive 7 can also be used for more complex geometries, such as logos with varying gap cross-sections. For example, a logo with thin and wide gaps will transmit different amounts of light at different points due to the design of the mask 5.

The adhesive 7 may be applied with a cross-section having a substantially droplet-like or triangular shape, wherein the adhesive 7 may preferably be substantially drop-shaped, pinstripe-shaped, bead-shaped, or spherical along at least part of the length of the lens. By applying a thicker cross-section of the scattering adhesive 7, or in the case of injection molding, an adhesive with a gradually varying thickness, the amount of light produced through the gap is regulated. In summary, varying the thickness of the scattering adhesive layer 7 across different locations can produce a homogenized and scattered light output.

The adhesive 7 acts as a filter and ultimately influences the color of the transmitted light. For lighting design and to meet the requirements of different applications, it may be necessary to correct the color shift of the adhesive 7. In the case of an LED light source, this can be achieved by LED bin selection. In the case of white, the LED binning can be selected to be up to several color bins cooler or warmer than the desired color of the emitted light due to the shift in color temperature caused by the scattering adhesive; for colors other than white, similar compensation may also be necessary. For example, a yellow/warmer white binned LED will induce a cooler/more blue color shift of the material. Furthermore, pigmenting and/or selecting a colored substrate of a lens 3 and/or adjusting and/or calibrating an LED to the shifted color may be appropriate. According to embodiments with a light source in the form of RGB LEDs, calibrating and/or adjusting the RGB LED may be a suitable method.

According to various embodiments, the lens 3, the mask 5, and the adhesive 7 are formed as a single component. This can be achieved by 3K injection molding. In this embodiment, the three layers are permanently bonded to one another. This solution eliminates the need for additional processing steps and their process control, in particular mixing a scattering additive in an adhesive, applying the adhesive, and curing the adhesive. The resulting 3K molding process enables intensive process control and throughput best suited for high-volume manufacturing.

In some applications, due to limitations of the molding process, such as filling narrow cross-sections, it is not possible to mold the diffuse layer of adhesive 7 together with the clear lens 3 and the opaque mask 5. In this case, the adhesive 7 is applied separately to the mask 5 and/or lens 3.

In a preferred embodiment, the adhesive 7 is provided by mixing the adhesive. Preferably, PMSQ particles can be mixed into the methacrylate. For mixing an adhesive, a mixer in the form of a centrifugal-planetary mixer can be used. Furthermore, it may be preferred that a thixotropic modified methacrylate is used. The lower mixing viscosity supports the production of a homogenized, air-free mixture of Adhesive 7. After mixing, the material returns to a high viscosity without collapse, thereby retaining Adhesive 7 beads, particularly PMSQ beads, in suspension.

To achieve a controlled thickness of the adhesive 7 along the length of the lens 3 and/or mask 5, a robot with an attached dispensing gun can be used. The dispensing gun can be directly fed with adhesive under high pressure, preferably between 2 and 10 bar, more preferably between 4 and 6 bar, the pressure preferably depending on the pressure supply, the chemical composition of the adhesive and/or the temperature of the adhesive. These values are important to prevent outgassing or deformation of the adhesive. A temperature range of 5° to 25° may be appropriate for the adhesive. Depending on the desired adhesive, this temperature can vary and typically ranges from -5° to 30°.

Preferably, a thickness of 2 mm can be achieved with a pressure of 3 bar using a supply voltage of 9 V at 38 mm/s, and a thickness of 1 mm can be achieved with a supply voltage of 5.4 V at 45 mm/s. Along the length of the lens, the robot speed and voltage can be adjusted between these two ranges to achieve a gradual reduction in thickness, maintaining uniform brightness along the length of the optic. Gradually changing thickness can be achieved by setting different supply voltages and robot speeds at multiple points along the lens length. For example, on the side closest to the LED, the supply voltage is 9 V and the robot speed is 38 mm/s, halfway through the part parameters are set to 8 V at 45 mm/s, and at 2/3 of the length the parameters are set to 5.4 V at 45 mm/s.

It is possible that the robot parameters are non-linear, so dispensing and measuring each part may be necessary. A relationship between the dispensing gun supply voltage and the robot speed can be used to adjust the adhesive thickness. These two values can be decreased to reduce the adhesive thickness and subsequently increased to increase it. By setting reduction values, i.e., 30% reduction from the starting point (at 1/3 the length of the lens) up to 60% reduction at the starting point (at 2/3 the length of the lens), a gradually changing thickness can be achieved. Alternatively, this can be achieved by reducing the output parameters by a ratio over time. By setting a starting point and an end point, the robot's internal system can change both values to achieve a gradual change in the adhesive thickness.

One or more dispensing guns can be fed directly with the adhesive 7 at high pressure to increase viscosity and reduce any cavitation that may be produced from the supply inlet. A target pressure of 4 to 8 bar has been shown to significantly improve bead quality, but due to air supply limitations, a pressure of 2 to 3 bar may also be used. A recirculating feeding system can be used in production to ensure the particles remain suspended in the adhesive 7 and minimize any cavitation.

In a preferred embodiment, the lens 3 substantially encloses the light guide and the light source so that it receives all of the light to be emitted. Consequently, the light guide does not protrude or extend beyond and/or out of the lens 3.

According to a further embodiment, the lens 3, the mask 5 and the adhesive 7 form a lens-mask-adhesive system in which the mask 5, the adhesive 7 and the lens 3 are permanently attached to one another after manufacture and are preferably not replaceable.

Although the subject matter has been described herein using language specific to structural features and/or acts, it should be understood that the subject matter described in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as examples of implementation of the claims, so that other equivalent features and acts are included within the scope of the claims.

REFERENCE SYMBOL

1

light-emitting system

2

inner surface of the lens

3

lens

4

outer surface of the lens

5

mask

7

adhesive

Claims (18)

A light-emitting system (1) for an automotive application, comprising: at least one light source; at least one mask (5); and at least one lens (3); characterized by at least one adhesive (7) for scattering light to provide substantially homogeneous illumination, the adhesive (7) being applied to the lens (3) with a gradually varying thickness. Light-emitting system (1) according to Claim 1 , wherein the light source is adapted to emit light into at least one light guide, which is preferably contained in the light-emitting system (1) and arranged at least partially in an interior of the light-emitting system (1). Light-emitting system (1) according to Claim 2 , wherein the lens (3) has at least one inner surface (2) which is substantially aligned with the light guide and at least one outer surface (4) which is arranged substantially opposite the inner surface (2), wherein preferably the outer surface (4) emits light directly or indirectly from the light-emitting system (1). Light-emitting system (1) according to Claim 2 or 3 , wherein the lens (3) and the mask (5) form a lens-mask system, wherein preferably • parts of the lens-mask system are translucent and parts of the lens-mask system are not translucent and/or • the lens-mask system is formed as one part by 2K injection molding. Light-emitting system (1) according to Claim 2 or 3 , wherein the lens (3), the mask (5) and the adhesive (7) form a lens-mask-adhesive system in the form of a three-layer system, wherein preferably the inner surface (2) of the lens (3) is substantially covered by the mask (5) and the adhesive (7) and/or the lens (3), the mask (5) and the adhesive (7) form a lens-mask-adhesive system in which the mask (5), the adhesive (7) and the lens (3) are permanently attached to one another and are not replaceable, and/or the lens-mask-adhesive system is formed as one part by 3K injection molding. Light-emitting system (1) according to one of the Claims 2 until 5 , wherein the adhesive (7) scatters light from the light guide; light from the light guide passes through the adhesive (7) and then the lens (3); and/or the lens (3) substantially encloses the light guide and the light source. Light-emitting system (1) according to one of the preceding claims, wherein the mask (5) is opaque; and/or the lens (3) has a continuous transparent and/or translucent coating on its outer surface (4), preferably wherein the continuous transparent and/or translucent coating is at least partially transparent to at least some of the light emitted by the light source and passing through the lens (3). The light-emitting system (1) according to any one of the preceding claims, wherein the adhesive (7) comprises insoluble particles that substantially provide the light-scattering effect of the adhesive (7), preferably wherein the insoluble particles comprise PMSQ beads, PMMA beads, and/or glass beads. The light-emitting system (1) according to any one of the preceding claims, wherein the adhesive (7) is formed in at least one droplet-like or substantially angular or substantially round or substantially triangular shape and/or the adhesive (7) is substantially pinstripe-like or bead-like or spherical along at least part of the length of the lens (3). The light-emitting system (1) according to any one of the preceding claims, wherein • the adhesive (7) is a one-component or multi-component adhesive, wherein the adhesive (7) is preferably a one-component adhesive and cures through the use of UV light, heat, an anaerobic environment, moisture, and/or contact with oxygen; and/or • the adhesive (7) is a pressure-sensitive adhesive, a temperature-sensitive adhesive, an anaerobic adhesive, and/or a combination thereof; and/or • the adhesive (7) comprises fillers such as ethylene glycol dimethacrylate and/or multifunctional monomers; and/or • the adhesive (7) comprises acrylic, polyester, silicone, styrene copolymer, and/or vinyl, preferably methacrylate, and more preferably thixotropic methacrylate. Light-emitting system (1) according to one of the preceding claims, wherein the adhesive (7) influencing a color shift of the transmitted light, wherein the color shift is preferably corrected by pigmenting the lens (3) and/or selecting a colored lens (3) and/or tuning and/or calibrating the light source to the shifted color. Light-emitting system (1) according to one of the preceding claims, wherein the light source comprises at least one LED, wherein preferably the color shift is corrected by LED bin selection. Light-emitting system (1) according to Claim 12 , where in the case of essentially white light, LED binning is selected up to several color bins cooler or warmer than the desired emitted light color. Light-emitting system (1) according to one of the Claims 2 until 12 , wherein the light source is arranged adjacent to and aligned with the at least one light guide. Vehicle comprising at least one light-emitting system (1) according to one of the preceding claims. Method for producing the light-emitting system (1) according to one of the Claims 1 until 14 , comprising the following steps: • Providing at least one adhesive (7), preferably by mixing light-scattering particles, such as PMSQ and methacrylate, particularly preferably thixotropically modified methacrylate, using at least one mixer, preferably in the form of a centrifugal-planetary mixer, in particular for removing and preventing the admixture of air bubbles; • Providing the mask (5) and the lens (3), preferably by 2K injection molding; • Applying the adhesive (7) to the mask (5) and the lens (3) using a robot with an attached dispensing gun, wherein the dispensing gun is directly fed with the adhesive (7) under high pressure, preferably between 2 and 10 bar or between 4 and 6 bar or between 2 and 3 bar and/or wherein the pressure preferably depends on the pressure supply, the chemical composition of the adhesive and/or the temperature of the adhesive; and • adjusting the robot speed and application rate to control the thickness of the adhesive (7), wherein the thickness of the adhesive is preferably between 1 mm and 2 mm and/or the robot speed is preferably between 38 mm/s and 85 mm/s and/or a dispensing gun supply voltage is preferably between 4 V and 10 V. Procedure according to Claim 16 , wherein the feeding of the dispensing gun is preferably carried out via a feeding system with recirculation, in particular in order to keep the light-scattering particles within the adhesive, and/or the robot speed and application rate are varied at different points along the length of the lens (3), wherein the thickness of the adhesive can preferably be adjusted by varying the robot speed and/or the gun supply voltage. Procedure according to Claim 16 or 17 , comprising the following step: Providing the lens (3), mask (5) and adhesive (7) by 3K injection molding.

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