Thermoformed device with OLED display and method of manufacture

Abstract

A curved human-machine interface device is manufactured by thermoforming a stack. The stack includes a front substrate formed of a transparent, first thermoplastic material; an OLED display configured to display images through the front substrate; and a thermo-mechanical buffer layer formed of a transparent, second thermoplastic material disposed between the front substrate and the OLED display. Heat is applied to the stack to raise the temperature of the front substrate and the buffer layer to respective processing temperatures at which the first and second thermoplastic materials become pliable. The stack is thermoformed while the thermoplastic materials are pliable to form the curved human-machine interface device. The second thermoplastic material has a lower stiffness than the first thermoplastic material at the respective processing temperatures.

Description

Technical Field

[0001] This disclosure relates to a curved OLED device and a method for manufacturing such a device. Background Technology

[0002] Human-machine interface devices, such as touch panels, can include various components, such as display devices and optional sensors for human-machine interaction with the device. While fabricating displays on flat substrates is relatively common, increasing curvature can be challenging. Curved (3D) substrates can be fabricated, for example, using processes such as thermoforming. Thermoforming typically involves the deformation of a material (stack) at elevated temperatures. For example, the substrate can be deformed according to a mold shape. Electronic circuitry can be included in the stack to create curved devices with functionality dependent on the electronic components in the circuitry. For example, if an OLED display could be included in a thermoformed stack, various new applications could be realized when fabricating curved (human-machine) interfaces. However, embedding certain functionalities (such as OLEDs) in thermoformed / in-mold electronics has remained challenging to date, for example, due to the high temperatures and strain involved in such processes. For example, reducing the temperature can be difficult due to material processing requirements, such as curing limitations. For example, strain can be reduced by using a smaller curvature or a smaller OLED, but this limits applications. For the single-foil method, especially in in-mold electronic devices, another potential problem is the appearance of visual defects at the user end (front substrate) of the device. These defects can occur, for example, due to localized deformation originating from circuit lines, and particularly from larger devices such as SMD chips and OLEDs, as well as the adhesives necessary to hold these SMD components in place during fabrication.

[0003] There is a need for human-machine interface devices that are easy to manufacture and flexible, especially those that can incorporate OLED displays in thermoforming processes. Summary of the Invention

[0004] This disclosure relates to a method of manufacturing a curved device by thermoforming a stack including an OLED display. A front substrate is formed of a transparent, first thermoplastic material, and a thermomechanical buffer layer is formed of a transparent, second thermoplastic material. The buffer layer is disposed between the front substrate and the OLED display. The stack is thermoformed into a three-dimensional (non-planar) shape to form the curved device. During or prior to thermoforming, heat is applied to the stack to raise the temperature of the front substrate and the buffer layer to a processing temperature. The materials of the front substrate and the buffer layer are selected such that the second thermoplastic material has a lower stiffness (stress / strain) than the first thermoplastic material at the processing temperature.

[0005] The inventors have surprisingly discovered that the insertion of this buffer layer allows for the inclusion of an OLED display within the stack during thermoforming processes, where the OLED retains its necessary functionality, which would otherwise (without the buffer layer) cause fatal damage to the OLED. Without being bound by theory, the reduction in damage can be explained in part by the lower stiffness of the buffer layer, which allows it to deform more than the front substrate and thus allows for lower mechanical stress on the OLED, which would otherwise transfer directly from the front substrate and could, for example, crack its moisture barrier. However, even considering the reduced mechanical stress, the OLED is expected to be susceptible to thermal stress damage. However, the inventors have actually found that the OLED can remain relatively cool when heat is applied to the stack. Even with careful control of the applied heat, at least the front substrate and the buffer layer need to be heated to become flexible when approaching or even contacting the OLED. It is still not necessary to heat the OLED to the same temperature. This can be explained, at least in part, by the additional heat capacity of the buffer layer. It is understood that materials undergoing phase transitions can have relatively high heat capacities when heat is used to change the state of the material rather than to raise its temperature. This is especially true when the thermoplastic material forming the buffer layer has lower stiffness than the front substrate at various processing temperatures. For example, the buffer layer may undergo a phase transition at a lower processing temperature than the front substrate. Therefore, through a synergistic combination of properties, the buffer layer can help mitigate thermal and mechanical stresses on the OLED during the thermoforming process. Attached Figure Description

[0006] These and other features, aspects, and advantages of the apparatus, systems, and methods disclosed herein will become more readily apparent from the following description, the appended claims, and the accompanying drawings, wherein:

[0007] Figure 1A The diagram shows a planar (flat) stack including an OLED display and a front substrate, with a thermomechanical buffer layer between the OLED display and the front substrate;

[0008] Figure 1B This illustrates a curved human-machine interface device formed by thermoforming lamination;

[0009] Figure 2A and Figure 2B This illustrates the use of mold shape heating and thermoforming of laminates;

[0010] Figure 2C This illustrates the application of a backing layer to a laminate using injection molding with a different mold shape;

[0011] Figure 3A A cross-sectional view of another stacked layout is shown;

[0012] Figure 3BThe corresponding front surface of a curved human-machine interface device is shown, which can be produced by thermoforming the stack.

[0013] Figure 4A and Figure 4B A photograph is shown of a curved human-machine interface device including an OLED display manufactured according to the method of the present invention;

[0014] Figures 5A to 5C A photograph shows another such device with an integrated OLED;

[0015] Figure 6A and Figure 6B The comparison between thermoformed stacks with and without OLEDs is shown separately. Detailed Implementation

[0016] The terminology used to describe particular embodiments is not intended to limit the invention. As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term “and / or” includes any and all combinations of one or more of the associated listed items. It will be understood that the terms “comprising” and / or “including” specify the presence of the stated feature but do not exclude the presence or addition of one or more other features. It will also be understood that when a particular step of a method is referred to as following another step, it may directly follow said other step or may have one or more intermediate steps performed before performing the particular step, unless otherwise stated. Similarly, it will be understood that when describing connections between structures or components, unless otherwise stated, the connection may be established directly or through intermediate structures or components.

[0017] The invention is described more fully below with reference to the accompanying drawings, in which embodiments of the invention are illustrated. In the drawings, for clarity, absolute and relative dimensions of systems, components, layers, and regions may be exaggerated. Embodiments may be described with reference to possibly idealized embodiments and schematic and / or cross-sectional views of intermediate structures of the invention. Throughout the specification and drawings, the same reference numerals denote the same elements. Relative terms and their derivatives should be interpreted as referring to the directions described in the discussion or shown in the drawings. These relative terms are for ease of description and, unless otherwise stated, do not require a specific orientation for construction or operation.

[0018] Figure 1A A planar (flat) stack 10 is shown, including an OLED display 13 and a front substrate 11, with a thermomechanical buffer layer 12 between the OLED display 13 and the front substrate 11. Figure 1B A curved human-machine interface device 100 formed by thermoforming lamination 10 is shown; Figure 2A and 2BThis illustrates the heating and thermoforming stack; Figure 2C The application of the optional backing layer 18 is shown.

[0019] Some aspects of the invention relate to the manufacture of the bending device 100. For example, (out-of-plane) curvature can be introduced by applying a deformation process to the planar stack 10. Preferably, the deformation process includes thermoforming. For example, the deformation process includes applying a predetermined macroscopic shape to the stack to thermoform the stack. Thermoforming is generally understood as a manufacturing process of heating a substrate of thermoplastic (thermally softening plastic) material to a flexible forming temperature. Typically, above its glass transition temperature (Tg) and below its melting point, the physical properties of thermoplastics change significantly without a associated phase transition. The heated substrate can be formed into a specific shape, for example, using a mold, and trimmed to produce a usable product. Typically, the stack is heated to a sufficiently high temperature that allows the stack to be stretched into or onto the mold 21, such as... Figure 2A As shown in the figure, it is cooled to its final shape.

[0020] A particularly preferred form of thermoforming is also known as high-pressure forming. Another form of thermoforming is known as vacuum forming; however, vacuum forming may require higher temperatures. For example, a machine can be used to heat the stack and stretch it over a mold using high pressure and / or vacuum. This method is commonly used for sample and prototype parts. In other or further applications, production machines can be used to heat and form substrates and optionally trim the formed parts from the stack in a continuous, high-speed process. Optionally or in addition to thermoforming, other deformation processes can also be used for the applications of this teaching, such as injection molding, blow molding, rotational molding, and other forms of processing of plastics at elevated temperatures. Therefore, when thermoforming processes or temperatures are mentioned herein, this can also apply to other similar processes. In some embodiments, for example, Figure 2C As shown, the backing layer 18 is applied to the rear side of the stack by injection molding (e.g., using mold 22). For example, thermosetting material is melted and injected between mold 22 and the stack.

[0021] In one implementation, for example, Figure 1A As shown, the stack 10 includes a front substrate 11. For example, the front substrate comprises or is substantially composed of a first thermoplastic material 11m, which is preferably transparent or at least translucent (to visible light). In a preferred embodiment, the stack includes an OLED display 13 configured to display an image through the front substrate 11. Most preferably, a thermomechanical buffer layer 12 is disposed between the front substrate 11 and the OLED display 13. For example, the buffer layer 12 comprises or is substantially composed of a second thermoplastic material 12m, which is preferably transparent or at least translucent.

[0022] In one implementation, for example, Figure 2A As shown, heat H is applied to the stack 10. This may cause the temperature of at least the front substrate 11 and the buffer layer 12 to rise. Preferably, the heat is applied such that the front substrate and the buffer layer reach the respective processing temperatures T1 and T2. At each processing temperature, the first thermoplastic material 11m and the second thermoplastic material 12m can become flexible (at least substantially more flexible than at room temperature 20°C).

[0023] In one implementation, for example, Figure 2B As shown, the thermoplastic materials 11m and 12m are preferably thermoformed while the laminate 10 is flexible to form a curved human-machine interface device 100. Although the figures show the heat H applied before thermoforming, heat may be applied alternatively or additionally during thermoforming.

[0024] As described herein, the second thermoplastic material 12m preferably has a lower stiffness than the first thermoplastic material 11m at each processing temperature T1, T2. In other words, at least during the thermoforming process, the second thermoplastic material 12m is more flexible or more resilient than the first thermoplastic material 11m, i.e., more easily deformable. For example, at the same or similar processing temperatures T1, T2, the second thermoplastic material 12m may have a lower elastic modulus and / or plastic modulus than the first thermoplastic material 11m (e.g., at least 10 percent lower, preferably at least 20 percent lower, or at least 50 percent lower).

[0025] According to some aspects, the methods described herein can be used to manufacture curved human-machine interface devices 100, for example, Figure 1B As shown in the figure. In one embodiment, the device includes a stack 10 having: a front substrate 11 formed of a transparent first thermoplastic material 11m; an OLED display 13 configured to display images through the front substrate 11; and a thermomechanical buffer layer 12 formed of a transparent second thermoplastic material 12m disposed between the front substrate 11 and the OLED display 13. Preferably, the flexible human-machine interface device 100 is formed by a thermoformed stack. For example, the front substrate 11 and the buffer layer 12 can be thermoformed simultaneously at processing temperatures T1 and T2 at which the first thermoplastic material 11m and the second thermoplastic material 12m become flexible. Most preferably, the second thermoplastic material 12m has a lower stiffness than the first thermoplastic material 11m at processing temperatures T1 and T2.

[0026] In some embodiments, during thermoforming, the corresponding temperature T2 of the buffer layer 12 can be maintained below the temperature T1 of the front substrate 11. For example, the second thermoplastic material 12m has a lower glass transition temperature and / or melting temperature than the first thermoplastic material 11m, for example, at least 5 or 10 degrees Celsius lower, preferably higher. In this way, when heat is applied, energy can first be used to induce a significant phase transition in the buffer layer 12 at a relatively lower temperature T2, while the front substrate 11 can reach a higher temperature T1 before the significant phase transition occurs.

[0027] In some embodiments, the second thermoplastic material 12m may be softened or even (partially) melted, while the first thermoplastic material 11m is softened less or at least not melted. Therefore, when the stack deforms, the flow of the second thermoplastic material 12m can adequately buffer the mechanical stress between the front substrate 11 and the OLED display 13, while melting or other phase changes can also account for a considerable portion of the heat energy.

[0028] In some embodiments, the OLED display 13 has a lower temperature T3 during thermoforming than the front substrate 11, and most preferably also lower than the buffer layer 12. Optionally or additionally, the substrate temperature in the covered (covered by the second thermoplastic material and / or the OLED) portion of the device may be lower than the substrate temperature in the uncovered portion. In one embodiment, during thermoforming in a region of the OLED display 13, the stack has a lower temperature T3 than the temperature of the surrounding region (not overlapping with the OLED). For example, the temperature may be lower due to the effect of the buffer layer 12 and / or the inherent properties of the OLED display. In some embodiments, the OLED itself may have a relatively high heat capacity, for example higher than that of the front substrate 11 and / or the buffer layer 12. In other or further embodiments, wherein, at least during the application of heat H, the stack 10 is provided with a heat sink and / or a thermal shield 17 attached to the OLED display 13. For example, a heat sink may be attached to the OLED to absorb heat from the OLED, keeping the OLED relatively cool. For example, a thermal shield may be arranged to cover the OLED display 13 to shield the OLED from heat applied, for example by radiation or other means. Understandably, the functions of heat sink and thermal shield can be combined in a single structure, which is attached to cover the OLED, for example, with a material such as a metal with relatively high heat capacity and reflectivity.

[0029] In some embodiments, heat H is applied via radiation, preferably in the infrared wavelength range. For example, the stack 10 is heated by one or more IR lamps. In a preferred embodiment, heat is applied via (at least) from the side of the front substrate 11 (i.e., from...). Figure 2AHeat H is applied by radiation from the top side of the stack. For example, radiation can be specifically applied to the front side so that this side is heated first, while the opposite side (where the OLED is disposed) can remain relatively cool. In other or further embodiments, as shown in the figure, heat H is applied by radiation from the sides of the stack. For example, heating of the OLED can be mitigated by using a thermal shield to block or reflect radiation. This can also be achieved using a shield to radiate the stack outside the location of the OLED. In some embodiments, heat is applied by radiation from the sides of the OLED display 13, wherein the thermal shield 17 or shield is arranged to block or reflect radiation reaching the OLED display 13. While radiation is preferred, other ways of applying heat to one or both sides of the stack are also conceivable, such as by contact or convection from one or both sides. This can also be done selectively, for example, to avoid direct heating of the OLED.

[0030] In some embodiments, during thermoforming, preferably high-pressure forming, the respective processing temperatures T1 and T2 of the front substrate 11 and buffer layer 12 are between 100°C and 200°C, preferably less than 160°C, most preferably less than 140°C or even less than 130°C, for example, between 130°C and 160°C (130°C to 160°C). During thermoforming, the temperature of the OLED is preferably lower than the temperature of the front substrate 11 and / or buffer layer 12, for example, at least 10°C, 20°C, or even 30°C lower. Preferably, the temperature of the OLED is maintained below 110°C, most preferably below 105°C or cooler, at least below the temperature at which the OLED would be severely damaged (lose its necessary function).

[0031] In a preferred embodiment, the glass transition temperature of the first thermoplastic material 11m is below 160°C, preferably below 150°C, most preferably below 140°C, for example, in the range of 100°C to 130°C. In some embodiments, the glass transition temperature of the second thermoplastic material 12m is lower than that of the first thermoplastic material 11m, for example, at least 5 or 10 degrees lower. Various combinations of thermoplastic materials can be used to form the front substrate 11 and / or the buffer layer 12. In one embodiment, the front substrate 11 is made of polycarbonate (PC) having a glass transition temperature of about 150°C (423K), thus gradually softening around that point and becoming deformable above about 155°C (428K). For example, when deforming PC, the ideal processing temperature is between 155°C and 160°C. In another embodiment, the front substrate 11 is made of poly(methyl methacrylate) (PMMA). Typically, the glass transition temperature of PMMA is in the range of 85°C to 165°C (depending on the composition). PMMA is preferably used at a processing temperature of approximately 130°C (and with a Tg below this temperature). Other materials can also be used as the front substrate 11, such as ABS (acrylonitrile-butadiene-styrene), PETG (polyethylene terephthalate in a thermoformable form), PVC (polyvinyl chloride), etc. Of course, the processing temperature may differ for other materials, although it is preferred not to be too high.

[0032] In some embodiments, the second thermoplastic material 12m comprises a thermoplastic elastomer. A thermoplastic elastomer (TPE), sometimes referred to as a thermoplastic rubber, is a class of copolymers or polymers (typically plastics and rubbers) that consist of materials possessing both thermoplastic and elastic properties. For example, the second thermoplastic material 12m softens substantially when heated to temperatures substantially above room temperature, such as in the range of 80°C to 140°C. In a preferred embodiment, the second thermoplastic material 12m comprises thermoplastic polyurethane (TPU) or polyvinyl butyral (PVB). Thus, a combination of, for example, PMMA and TPU can be thermoformed at a processing temperature of about 130°C, while a combination of PC and TPU can be thermoformed at a processing temperature of about 160°C.

[0033] In some implementations, for example, Figure 1AAs shown, the stack 10 includes a circuit 14 with circuit lines 141. Preferably, the circuit lines are printed on a thermomechanical buffer layer 12. For example, the circuit lines 141 are printed using a conductive ink containing, for example, silver (Ag). The circuit lines are preferably printed on the buffer layer 12 after the buffer layer 12 is laminated to the front substrate 11 but before thermoforming. Other components are also preferably applied between the lamination and thermoforming steps, although these processes can in principle be applied to the buffer layer 12 before lamination. Typically, the circuit lines 141 are electrically connected to electronic components, including the OLED display 13, disposed on the buffer layer 12. In addition to mitigating damage to sensitive components such as OLEDs, the buffer layer has been found useful in reducing visible defects that may occur due to thermoforming. For example, when relatively large and / or rigid components (such as OLEDs or other devices, such as SMDs, chips, etc.) are included in the stack, defects can be seen on the front substrate. Alternatively, in addition to the printed circuit components on the buffer layer 12, it is conceivable that they be printed directly on the front substrate 11, although this may result in visible artifacts depending on the size and composition of the printed components (e.g., regarding the thickness of the front substrate 11). If desired, these can be alternatively positioned at the edges of the device.

[0034] In some embodiments, the stack 10 includes a sensor 15 disposed between the front substrate 11 and the buffer layer 12. For example, the stack can be thermoformed into a curved touchscreen device or touch button. Preferably, the sensor 15 is configured as a proximity sensor, such as a capacitive sensor device capable of detecting user interactions such as touching the front substrate 11. Most preferably, the proximity sensor 15 is substantially transparent to allow viewing of the OLED display 13 through the sensor. In some embodiments, the components between the front substrate 11 and the buffer layer 12, such as… Figure 1A The sensor 15 shown is electrically connected using a via connector 14V through the buffer layer 12.

[0035] While the proximity sensor 15 is preferably placed as close as possible to the front substrate 11, for example, to better detect touch events, in principle, the proximity sensor 15 can also be placed elsewhere, such as between the buffer layer 12 and the OLED display 13, or behind the OLED display 13, and / or integrated as a component of the OLED display 13. Alternatively, or in addition to the proximity sensor, other types of sensors, such as light sensors or motion sensors, are also conceivable. For example, it is also conceivable to detect movement of the entire device or its components, such as pressing a (circular) button with an OLED display formed by this method.

[0036] In some embodiments, the stack 10 includes a pattern 16 formed of one or more layers of opaque material 16m. Preferably, the pattern 16 includes at least one window 16w for transmitting light L from an image displayed on the OLED display 13, or light emitted from or received by other components on the substrate (e.g., LEDs or light sensors (not shown)). For example, the opaque material 16m can be used to conceal circuitry and other components disposed on or between the buffer layer 12 and the pattern 16. In some embodiments, the front substrate and / or buffer layer 12 is configured to function as a light guide structure, for example, in cooperation with the pattern, which may also be white on the side facing the buffer layer to reflect more light along the light guide. Although this figure shows a pattern 16 between the front substrate 11 and the buffer layer 12, which is preferred, it is also conceivable to apply a pattern or another pattern on the front substrate 11 (e.g., including a scratch-resistant layer) or between the buffer layer 12 and the circuitry, for example, to apply the pattern 16 to the buffer layer 12 before or after the circuitry is applied.

[0037] In some embodiments, the front substrate 11 has a thickness of 1 mm or 2 mm, preferably less, for example, between 250 μm and 700 μm. It is understood that the method of the present invention allows for a relatively thin front substrate 11 because visible artifacts from components behind the substrate can be mitigated by the buffer layer 12 between them. Advantageously, it has been found that the buffer layer 12 can be effective at relatively low thicknesses, for example at least 5 μm or 10 μm, or greater. In one embodiment, the buffer layer 12 is applied as a sheet, for example, by lamination onto the front substrate 11 and / or the OLED display 13. In another or further embodiment, the buffer layer 12 is printed onto, for example, the front substrate 11 and / or the OLED display 13. The inventors have particularly found that relatively thin buffer layers (e.g., less than 20 μm, less than 10 μm, as low as 5 μm, or even thinner) can be applied most reliably by printing. The effectiveness of the buffer layer typically increases with increasing thickness; therefore, the thickness of the buffer layer 12 is preferably between 20 μm and 1000 μm, more preferably between 50 μm and 500 μm, or between 100 μm and 250 μm. It will be understood that even with the buffer layer included, the total thickness of the front substrate 11 and the buffer layer 12 can be less than that of a conventional front substrate 11 without the buffer layer 12, for example, where the total thickness is less than 2 mm, less than 1 mm, or even less than half a millimeter. The thinner the total thickness, the closer the OLED display 13 appears to the front surface of the device. The OLED is preferably as thin as possible. The surface area of ​​the OLED can vary, for example, from one square centimeter or larger (e.g., up to tens of centimeters). 2 The variation between )

[0038] Figure 3A A cross-sectional view of another stacked layout is shown; Figure 3B The corresponding front surface of a curved human-machine interface device 100 is shown. The curved human-machine interface device 100 can be produced by a thermoformed stack 10. In some embodiments, the stack 10 includes optoelectronic components, such as an OLED display 13a and / or an LED 13b. It will be understood that while this teaching is particularly useful for the unexpected ability to integrate OLED displays in a thermoforming process, this teaching can also be beneficial for integrating other types of devices (displays or not displays). Optionally, or in addition to OLED displays, other types of displays, such as electronic ink (E-ink) devices / paper, can also be integrated into the stack.

[0039] In some embodiments, stack 10 includes sensor components, such as a capacitive sensor 15a and / or other types of sensors 15b, such as light sensors, proximity sensors, time-of-flight sensors, motion sensors, etc. For some components, these components may preferably be printed. Other components may be placed using other methods. In some embodiments, stack 10 includes a circuit board 19 (e.g., a PCB), surface mount components, integrated chips, FSRs, etc. These and other components, including OLEDs, may be connected to circuitry including circuitry 141 (e.g., printed) on the buffer layer 12 and on the front substrate 11 and / or through vias 14v in the buffer layer 12 and / or other layers (such as an optional backing layer 18).

[0040] In some embodiments, the stack includes light-guiding structures. For example, light-blocking walls 12w can be arranged to guide light from LED 13b to patterned light outlets, such as forming an indicator light as shown in the figure. In some embodiments, backing layer 18 includes a reflective material, such as a white material, which can help guide light to the corresponding pattern 16p and / or window 16w. This can be achieved, for example, by vacuum or injection molding.

[0041] Typically, components or devices to be integrated into the stack are relatively rigid, at least compared to the front substrate 11 and / or buffer layer 12. Additionally, the manner in which components are attached can contribute to localized stiffness. For example, isotropic conductive adhesive (ICA) can be used to attach components to circuit lines. Therefore, the method of the present invention can alleviate thermal and mechanical stresses on OLEDs and / or other components.

[0042] Figure 4A and Figure 4B A photograph is shown of a curved human-machine interface device including an OLED display, manufactured according to the method of the present invention. As shown, different images can be displayed on the device, such as dynamic indicator lights and / or buttons.

[0043] Figures 5A to 5C Integrity testing of another such device with an integrated OLED is shown. Photographs of the functional device are shown here 11 days, 18 days, and 139 days after manufacturing. This demonstrates the reliability of the product manufactured according to this method. In one embodiment, a curved human-machine interface device as described herein is fabricated by applying a 0.7 mm thick TPU buffer layer onto a 2 mm thick PMMA front substrate. The OLED display is immediately applied onto the TPU buffer layer. The stack is laminated at 90 degrees and subsequently thermoformed at 130°C. The stack is formed using a positive semi-cylindrical mold as shown in the figure, in which case TPU is applied only locally, rather than over the entire area (the latter being preferred).

[0044] Figure 6A This shows a stack without OLED thermal forming. Figure 6B The same stack is shown, but thermoformed with an OLED display 13, which is peeled off from the stack after thermoforming, leaving imprint 13i. As previously shown, see reference, for example. Figures 2A to 2C The OLED display 13 is preferably a component of the stack, and a thermoforming process is applied. Therefore, during the attachment of the OLED display 13, the buffer layer and / or front substrate can be at least partially melted and / or deformed by heating and / or thermoforming processes. This can leave imprints 13i, such as indentations (at least on the surface) in the buffer layer according to the shape of the OLED display 13. For example, this can be considered as... Figure 6B The relatively glossy mark 13i in the middle, which is in Figure 6A It does not exist in ( Figure 6A The rectangular dark area in the diagram corresponds to the window 16w through the underlying opaque layer (not the imprint). In some embodiments, the imprint can be used to distinguish a curved human-machine interface device, as described herein, from a portion of the OLED display 13 that is not stacked during thermoforming, and can be applied in a separate subsequent step. For example, a device formed according to the methods described herein can be identified by the shape or roughness of the buffer layer and / or the front substrate. For example, due to the presence of the OLED display in the thermoforming process, the shape of the buffer layer includes the imprint 13i of the OLED display 13, such as a serrated shape or contour. For example, the imprint 13i may have a roughness different from the surrounding surface (e.g., smoother). For example, the OLED display 13 may be integrally attached to the buffer layer without any additional (adhesive) layer between them.

[0045] For the purposes of clarity and concise description, features are described herein as part of the same or separate embodiments; however, it will be understood that the scope of the invention may include embodiments having combinations of all or some of the features described. For example, although embodiments for embedding OLED display devices in thermoformed stacks are shown, those skilled in the art will envision alternative methods that have the benefits of this disclosure to achieve similar functionality and results. For example, components and layers may be combined or divided into one or more alternatives. The various elements of the embodiments discussed and illustrated provide certain advantages, such as protection against damage and mitigation of visible artifacts. Of course, it should be understood that any of the above embodiments or processes can be combined with one or more other embodiments or processes to provide even further improvements in discovering and matching designs and advantages. It should be understood that this disclosure provides particular advantages for manufacturing curved human-machine interface devices and can generally be applied to any application in which heat and / or strain-sensitive components are included in the thermoforming process. For example, the methods and systems of the present invention can also be fitted with other surface mount devices besides OLED display devices, or alternatives to OLED display devices.

[0046] In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or actions besides those listed in a given claim; the words "a" or "an" preceding an element do not exclude the presence of a plurality of such elements; any reference numerals in the claims do not limit their scope; several "means" may be represented by the same or different items or implementations of structure or function; unless otherwise specifically stated, any of the disclosed means or portions thereof may be combined together or divided into other parts.

Claims

1. A method for manufacturing a curved human-machine interface device (100), the method comprising: A stack (10) is provided, the stack comprising: A front substrate (11) is formed of a transparent, first thermoplastic material (11m); OLED display (13), configured to display an image through the front substrate (11); and The thermomechanical buffer layer (12) is formed of a transparent, second thermoplastic material (12m) disposed between the front substrate (11) and the OLED display (13); Heat (H) is applied to the stack (10) to raise the temperature of the front substrate (11) and the buffer layer (12) to the respective processing temperatures (T1, T2) at which the first thermoplastic material (11m) and the second thermoplastic material (12m) become flexible; and The laminate (10) is thermoformed while the thermoplastic material (11m, 12m) is flexible to form the curved human-machine interface device (100). The second thermoplastic material (12m) has lower stiffness than the first thermoplastic material (11m) at each processing temperature (T1, T2).

2. The method according to claim 1, wherein, The stack (10) includes a printed sensor (15) disposed between the front substrate (11) and the buffer layer (12).

3. The method according to claim 1 or 2, wherein, The stack (10) includes a circuit (14) having circuit lines (141) printed on the thermomechanical buffer layer (12), wherein the circuit lines (141) are electrically connected to electronic components disposed on the buffer layer (12) including the OLED display (13).

4. The method according to claim 1 or 2, wherein, The stack (10) includes a graphic pattern (16) formed of one or more layers of opaque material (16m), the graphic pattern (21) including at least one window (16w) for transmitting light (L) from an image displayed on the OLED display (13) through the front substrate (11), wherein the opaque material (16m) is arranged to visually block other components and / or circuit components on the buffer layer (12) from passing through the front substrate (11).

5. The method according to claim 1 or 2, wherein, At least during the application of heat (H), the stack (10) is provided with a heat sink and / or thermal shield (17) attached to the OLED display (13).

6. The method according to claim 1 or 2, wherein, The heat (H) is applied by radiation from the side of the front substrate (11).

7. The method according to claim 1 or 2, wherein, Heat is applied by radiation from the side of the OLED display (13), wherein a heat shield (17) or shield is arranged to block or reflect radiation to the OLED display (13).

8. The method according to claim 1 or 2, wherein, The OLED display (13) has a lower temperature (T3) than the front substrate (11) and / or the buffer layer (12) during the thermoforming process.

9. The method according to claim 1 or 2, wherein, The various processing temperatures (T1, T2) are between 100 degrees Celsius and 160 degrees Celsius, wherein the temperature of the OLED display (13) is maintained below 110 degrees Celsius.

10. A curved human-machine interface device (100), comprising: The thermoformed stack (10) includes: A front substrate (11) is formed of a transparent, first thermoplastic material (11m); OLED display (13), configured to display an image through the front substrate (11); and The thermomechanical buffer layer (12) is formed of a transparent, second thermoplastic material (12m) disposed between the front substrate (11) and the OLED display (13). The front substrate (11) and the buffer layer (12) can be thermoformed simultaneously at processing temperatures (T1, T2) where the first thermoplastic material (11m) and the second thermoplastic material (12m) become flexible. The second thermoplastic material (12m) has a lower stiffness than the first thermoplastic material (11m) at the processing temperatures (T1, T2). The shape of the buffer layer (12) includes an imprint formed by the shape of the OLED display (13) present during thermoforming.

11. The curved human-machine interface device according to claim 10, wherein, The second thermoplastic material (12m) has a lower glass transition temperature or melting temperature than the first thermoplastic material (11m).

12. The curved human-machine interface device according to claim 10 or 11, wherein, The first thermoplastic material (11m) has a glass transition temperature in the range of 100°C to 130°C.

13. The curved human-machine interface device according to claim 10 or 11, wherein, The second thermoplastic material (12m) includes a thermoplastic elastomer.

14. The curved human-machine interface device according to claim 10 or 11, wherein, The front substrate (11) has a thickness between 250 μm and 700 μm, and the buffer layer (12) has a thickness between 100 μm and 250 μm.

15. The curved human-machine interface device according to claim 10 or 11, wherein, The front substrate (11) comprises PMMA, and the buffer layer (12) comprises TPU.

Images