Skin for interior vehicle parts equipped with a light source

Abstract

The skin (1) comprises at least a translucent elastomeric layer (5) made of a pigmented plastic material and including at least one first portion (8) adapted to be placed in front of a light source 9. The light of this light source (9) generates an image on this first portion (8) of the translucent layer (5) due to the presence of surface reliefs (17, 18) on the surface of the translucent layer (5). The pigmented plastic material is 1.0 mm thick. -1 ~25mm -1 The average spectral attenuation coefficient (α av ), a clearly visible image can be obtained by introducing a slight difference in the thickness of the semi-transparent layer (5). av ) is the difference between the formula: α av The distance d2-d1 must be large enough to satisfy the equation (d2-d1)>-ln a, where a is equal to 0.50. The surface reliefs (17, 18) can be automatically generated when the semi-transparent layer (5) is molded onto the mold surface, so that the image can be easily positioned on the skin (1).

Description

Technical Field

[0001] The present invention relates to a skin for vehicle interior parts.

Background Art

[0002] The skin usually includes at least a translucent elastomer layer made of a plastic material substantially uniformly colored, and the translucent layer has an outer surface and an inner surface opposite to the outer surface. The outer surface forms the visible surface of the skin, i.e., the so-called A surface. The translucent layer includes at least one first portion configured to be disposed in front of a light source and transmit visible light generated by the light source from the inner surface to the outer surface. The light source is preferably adhered to the inner surface of the translucent layer.

[0003] Automobiles such as cars or trucks are equipped with many electrical or electronic components that can be controlled by a driver or a passenger. Operating elements such as buttons, switches, and sliders used to control the operation of these components are usually mechanically attached individually or as an assembly to an opening in the interior part itself. Between the regions having the operating elements, the interior part usually includes a region formed by an elastomeric skin optionally having other functional or aesthetic parts integrated into the skin. On its outer surface, the elastomeric skin has a surface texture. This texture may be intended to mimic leather, but may also be intended to reduce the gloss of the skin material. This can be important, for example, at the upper part of the dashboard, to avoid overly strong light reflection.

[0004] The operating elements may be adhered to the back of the elastomeric skin. They can be provided with a light source so as to be visible through the skin. In the method disclosed in Patent Document 1, the operating elements are adhered to the back of the skin by manufacturing the skin according to a powder slush process on the mold surface and applying the operating elements to the back of the powder slush skin when the skin material has not yet fully cured. In this way, the operating elements adhere to the skin by the adhesive properties of the curable skin material. In a similar method disclosed in Patent Document 2, the operating elements are applied to the back of the first polyurethane skin layer before the reactive material used to manufacture this skin layer is fully cured. Subsequently, a further polyurethane skin layer is sprayed onto the back of the first skin layer and the back of the operating elements to embed the operating elements in the elastomeric polyurethane skin.

[0005] In recent years, there has been an increasing interest in integrating the operating elements into the skin so as to be hardly visible. For example, reference can be made to Patent Documents 3 and 4. In Patent Document 3, the operating element is a pressure-sensitive element covered by a flexible skin material. Since it is thus not visible to the user, an assignment field is provided on the outer surface of the skin to indicate the presence of the operating element.

[0006] In Patent Document 4, a proximity sensor and a light source are arranged on the back of the skin. An icon layer between the light source and the skin can project an indication of the function of an electrical or electronic component controlled by a switch assembly onto the skin. The switch assembly is hidden unless it is actuated to emit light by the light source. The drawback of the required icon layer is that it makes the operating elements more complex and bulkier.

[0007] A similar system is disclosed in Patent Document 5. Patent Document 5 discloses an automotive interior component comprising an elastomeric skin, a light source, and an optical pattern layer between the skin and the light source. The optical pattern layer enables an image to be generated on the skin layer.

[0008] In the skin disclosed in Patent Document 6, characters or shapes are displayed on the outer surface of the skin not by an icon or optical pattern layer under the skin, but by several translucent skin color coating layers and a mask layer under these coating layers. The characters or shapes are generated by cutting a part of the coating layer and the mask layer with a laser so that light from a light source can pass through the skin at these positions. The drawback of such a system is that a post-processing laser process must be performed to accurately cut the characters or shapes at the correct position on the skin. Such post-processing is not only complex but also may lead to an additional amount of scrap.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a new skin having a translucent elastomer layer that can generate an image by a light source applied behind the translucent layer without requiring the presence of an icon or optical pattern layer under the skin and without requiring an additional post-processing step, such as a laser cutting step.

Means for Solving the Problem

[0011] The skin includes at least a translucent elastomer layer made of a colored plastic material. The translucent layer has an outer surface and an inner surface opposite to the outer surface. The translucent layer is disposed in front of a light source and is configured to transmit visible light generated by the light source from the inner surface to the outer surface, and includes at least one first portion.

[0012] To achieve the object of the present invention, the skin is such that when the first portion of the translucent layer transmits the visible light, the first portion includes a surface relief on the outer surface and / or the inner surface to generate an image on the first portion. The surface relief forms at least one first region. The translucent layer has a thickness of not more than a first thickness (d1), and at least half of the region has a thickness of not less than a second thickness (d2) greater than the first thickness (d1). The difference (d2 - d1) between the first thickness (d1) and the second thickness (d2) is greater than 0.08 mm and less than 3.0 mm. The colored plastic material has an average spectral attenuation coefficient (α av ), and this average spectral attenuation coefficient is the average of spectral attenuation coefficients (α(λ)) determined at regular intervals, particularly at intervals of 5 nm, for wavelengths (λ) over a range of visible wavelengths according to the following formula (I). (I) TIFF0007702405000001.tif3077Wherein, d1 = the first thickness, T1(λ) = the spectral transmittance at the wavelength (λ) of a film of the colored plastic material having a uniform thickness equal to the first thickness (d1) measured according to EN ISO13468 - 2:2006 Part 2.

[0013] According to the present invention, the average spectral attenuation coefficient (α av ) is further 1.0 mm -1and 25 mm -1 should be included between and should be related to the difference (d2 - d1) between the first thickness (d1) and the second thickness (d2) according to the following formula (II). α av (d2 - d1) > -In a(II) In the formula a = 0.50

[0014] The surface relief of the inner surface and / or the outer surface of the translucent layer can be easily obtained by manufacturing the translucent layer by a molding process. The surface relief can be generated with respect to the surface of the mold or with respect to an insert, in particular with respect to the surface of a light source pre - arranged in the mold. In this way, the image generated by the surface relief is always in the correct position on the skin. Furthermore, the image is automatically obtained without the need for an icon or an optical pattern layer under the translucent layer or without the need for a post - processing step.

[0015] The surface relief on the inner or outer surface of the translucent layer is preferably a shaped surface relief, i.e., a surface relief obtained by shaping the translucent elastomeric layer against a solid surface. Thus, in the case of the inner surface, the surface relief can be produced by shaping the translucent layer against an insert layer already arranged in the mold. Thus, the translucent layer can be produced, for example, by a reaction overmoulding process (ROM process), in particular by a liquid polyurethane reactive mixture. However, the surface relief is preferably provided on the outer surface of the translucent layer. The surface relief can be produced on the outer surface by shaping the translucent layer against a textured mold surface, the texture showing the negative characteristics of this surface relief. The translucent elastomeric layer may be made of a thermoplastic material that is shaped in a molten state against the mold surface, such as in a slush molding process. Alternatively, a layer (foil) of such a thermoplastic material may be shaped against the mold surface in a solid state. The solid layer of the thermoplastic material is shaped by urging or sucking it against the textured mold surface with sufficient pressure so that the negative surface relief of the mold surface is transferred to the skin layer. The skin layer and / or the mold surface are preferably heated to assist the molding process. The elastomeric layer may also be produced from a reactive mixture, such as a polyurethane reactive mixture, which can be applied in a liquid state against the textured mold surface, for example by a spraying process, and cured against this mold surface. Despite the fact that the colored elastomeric layer is translucent, according to the invention, when the colored plastic material has an average spectral attenuation coefficient selected between 1.0 mm -1 ~25 mm -1 it has been found that a clearly visible image can be obtained by providing a relatively small difference in the thickness of the above layer.

[0016] The higher this average spectral attenuation coefficient and the greater the difference in thickness between the first and second regions of the translucent layer, the greater the contrast between the portions of the image generated by the light transmitted through the thinner first region and the thicker second region of the translucent layer. 1.0 mm -1 A higher average spectral attenuation coefficient makes the translucent layer sufficiently opaque to generate a visible texture thereon without illumination from the back of the translucent layer as usual, especially in areas of the skin where the light source is not provided on the back. On the other hand, 25 mm -1 A lower average spectral attenuation coefficient is essential in order to be able to manufacture a translucent layer having a sufficiently high transmittance for a sufficiently large thickness. The transmittance (T) is actually determined by the following formula. T = e -α.d , wherein, T is the light transmittance through the translucent layer, α is the attenuation coefficient of the material of the translucent layer, d is the thickness of the translucent layer.

[0017] According to the present invention, it has been found that when the formula of formula (II) in which a is equal to 0.50 is satisfied, the first thinner region and the second thicker region can be visually distinguished. In other words, the light transmittance through the second region must be less than about 50% of the light transmittance through the first region.

[0018] According to the invention, the thickness difference between the first region and the second region to achieve the claimed difference in transmittance between the first region and the second region is automatically obtained by the manufacturing process and must be greater than 0.08 mm in order to avoid visible small thickness variations that cannot be (easily) avoided. Furthermore, the thickness difference between the first region and the second region to achieve the claimed difference in transmittance between the first region and the second region must be less than 3.0 mm. In this way, an overly large thickness difference is not required to achieve a predetermined difference in transmittance between the first skin region and the second skin region. In other words, the desired image can be obtained with a relatively low surface relief that has a particularly minimal impact on the appearance of the skin when not illuminated by the light source behind the translucent layer.

[0019] In one embodiment of the skin according to the invention, the value a in formula (II) is equal to 0.45, preferably equal to 0.40, more preferably equal to 0.35, and most preferably equal to 0.30.

[0020] This means that the light transmittance through the thicker second region includes at most about 45% or less of the light transmittance through the thinner first region of the skin, and the contrast between the portion of the image generated by the light passing through the first region of the skin and the portion of the image generated by the light passing through the second region of the skin becomes greater.

[0021] In one embodiment of the skin according to the invention, the difference (d2 - d1) between the first thickness (d1) and the second thickness (d2) is greater than 0.10 mm.

[0022] In this embodiment, in order to achieve a predetermined difference in transmittance between the first skin region and the second skin region, a larger minimum thickness difference is required, so that the tolerance of the skin thickness can be increased without generating visible defects in the image generated by the light passing through the skin.

[0023] In one embodiment of the skin according to the present invention, the difference (d2 - d1) between the first thickness (d1) and the second thickness (d2) is less than 2.0 mm, preferably less than 1.5 mm, more preferably less than 1.0 mm.

[0024] In this embodiment, a smaller thickness difference is required to achieve a predetermined difference in transmittance between the first skin region and the second skin region. In other words, the desired image can be obtained with a lower surface relief, and in particular, it has a minimal impact on the appearance of the skin when not illuminated by a light source on the back side of the translucent layer.

[0025] In one embodiment of the skin according to the present invention, the average spectral attenuation coefficient (α av ) is greater than 2.0 mm -1 , preferably greater than 3.0 mm -1 , more preferably greater than 4.0 mm -1 , most preferably greater than 5.0 mm -1 .

[0026] In this embodiment, a smaller thickness difference is required to achieve a predetermined difference in transmittance between the first skin region and the second skin region. In other words, the desired image can be obtained with a lower surface relief, and in particular, it has a smaller impact on the appearance of the skin when not illuminated by a light source on the back side of the translucent layer.

[0027] In one embodiment of the skin according to the present invention, the average spectral attenuation coefficient (α av ) is less than 20.0 mm -1 , preferably less than 15.0 mm -1 , more preferably less than 10.0 mm -1 .

[0028] The smaller the attenuation coefficient, the greater the light transmittance of the skin obtained for the same skin thickness. At the same time, in order to achieve a predetermined light and dark contrast in the image generated by the light source, a greater difference in skin thickness is required. A specific selection of the attenuation coefficient makes it possible to achieve a clear image with a greater thickness of the translucent layer while maintaining the necessary difference in thickness between the thin skin region and the thick skin region that generates the image small enough.

[0029] In one embodiment of the skin according to the present invention, the first portion of the translucent layer has an average thickness of less than 2.0 mm, preferably less than 1.5 mm, more preferably less than 1.2 mm, and most preferably less than 1.0 mm. In a further embodiment of the skin according to the present invention, the first portion of the translucent layer has an average thickness greater than 0.2 mm, preferably greater than 0.3 mm, more preferably greater than 0.4 mm, and most preferably greater than 0.5 mm.

[0030] The average thickness is a surface weighted average. The average thickness of a portion of the translucent layer is determined by dividing its volume by the surface area of its inner surface.

[0031] The thickness of the translucent layer as claimed in these embodiments is particularly suitable for use as a structural layer of the elastomeric skin, i.e. as a layer contributing to the necessary mechanical properties of the elastomeric skin.

[0032] In one embodiment of the skin according to the present invention, the visible light wavelength range has a width of at least 50 nm, preferably at least 75 nm, or preferably at least 150 nm, or preferably at least 300 nm.

[0033] The light source may be a light source that emits only light within a specific wavelength range, for example, an LED. When the above conditions are satisfied for the wavelength range emitted by the light source (for example, when the translucent layer contains a coloring pigment having the same color as the light emitted by the light source in particular), a desired image can be generated as described above. On the other hand, when the light source emits light over a wider range, for example, the entire range of visible light wavelengths, and the translucent layer contains a coloring pigment such that mainly light of a specific range of wavelengths / colors passes through the translucent layer and other light is mainly absorbed, the effects of the present invention can be achieved with an average spectral attenuation coefficient determined over the range of transmitted wavelengths.

[0034] In one embodiment of the skin according to the present invention, the above range of visible light wavelengths is in the range of 380 to 780 nm.

[0035] This range encompasses all visible light wavelengths. Therefore, images can be generated not only with white light but also with light of other colors. Therefore, two or more light sources can be arranged behind the translucent layer to generate images in different colors depending on which light source is activated. The different light sources can alternatively be used or can be used together to generate different color portions of the image. The colored light source may include an LED that emits light within a specific wavelength range, or may include a light source that emits, for example, white light covered by a colored transparent mask such that the colored light passes through the mask and is transmitted to the translucent skin layer.

[0036] In one embodiment of the skin according to the present invention, the skin is adhered to the inner surface of the above first portion of the translucent layer and includes at least one light source configured to emit visible light having a predetermined wavelength range, and the above range of visible light wavelengths corresponds to this predetermined wavelength range.

[0037] Therefore, in this embodiment, the average spectral attenuation coefficient is determined over the wavelength range emitted by the light source such that the above effects are achieved using this light source.

[0038] Preferably, the skin includes an inner elastomer layer adhered to the inner surface of the semi-transparent elastomer layer, and the light source is embedded between the semi-transparent elastomer layer and the inner elastomer layer.

[0039] The advantage of this embodiment is that the light source is completely shielded from dust or moisture. Further, the light source can be easily and completely integrated when the two skin layers are molded against the mold surface, and thus can be accurately positioned at the required position on the back surface of the semi-transparent layer. Therefore, the light source is protected from damage when transferring the skin to the next mold, especially a back-foaming mold, and the substrate is adhered to the back surface of the skin through the foaming layer.

[0040] The light source may include at least one LED, particularly a bare LED, embedded between the semi-transparent elastomer layer and the inner elastomer layer. Such bare LEDs are less expensive than embedded LEDs and are also low-profile so that they can be easily integrated between the two skin layers.

[0041] In one embodiment according to the present invention, the skin includes a flat screen display, particularly an LED screen, more particularly an OLED screen, adhered to the inner surface of the second part of the semi-transparent layer, and the second part is configured to transmit visible light generated by the flat screen display from the inner surface to the outer surface.

[0042] Using the above-described attenuation coefficient, particularly the smaller attenuation coefficient defined in the preferred embodiment, the image of the display can be seen on the outer surface of the second part of the semi-transparent layer.

[0043] Preferably, the inner and outer surfaces of the second part of the semi-transparent layer have a surface texture that is completely smooth or has a Pt value measured according to DIN EN ISO 4287:1998, and the Pt value in mm satisfies the following formula (III). (III) In TIFF0007702405000002.tif3077, b is greater than 0.50, preferably greater than 0.60, and more preferably greater than 0.70.

[0044] In this embodiment, the image of the display is not distorted or minimally distorted by the presence of any surface texture on the outer or inner surface of the translucent layer. Similar to the first portion of the translucent layer, a surface relief can also be provided on the second portion of the translucent layer, and when this second portion is illuminated by the display, an additional image can be generated. This additional image can be arranged so as not to affect or minimally affect the image generated by the flat screen display itself.

[0045] Also preferably, the skin comprises an inner elastomeric layer adhered to the inner surface of the translucent elastomeric layer, and the flat screen display is embedded between the translucent elastomeric layer and the inner elastomeric layer.

[0046] The advantage of this embodiment is that the display is completely shielded from dust or moisture. Furthermore, the display can be easily and completely integrated when the two skin layers are molded onto the mold surface, and thus can be accurately positioned at the required position on the back surface of the translucent layer. Therefore, the display is protected from damage when transferring the skin to the next mold, especially the back foam mold, and the substrate is adhered to the back surface of the skin via the foam layer. Other advantages and particularities of the present invention will become apparent from the following description of some specific embodiments of the skin according to the present invention. This description is given by way of example only and is not intended to limit the scope of the present invention. The reference numbers used herein relate to the accompanying drawings.

Brief Description of the Drawings

[0047]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0048] The present invention generally relates to a skin 1 for vehicle interior components 2 such as dashboards, door panels, consoles, glove compartment lids, etc. As can be seen in FIGS. 3 and 5, the interior component comprises a skin 1 adhered to a rigid substrate layer 3. The skin 1 can be adhered directly to the substrate layer 3 by an adhesive or by an overmolding process in which the skin 1 is molded onto the substrate layer 3 in a mold. Preferably, the skin 1 is adhered to the substrate layer 3 via a foam layer 4. This foam layer 4 can be manufactured by a molding process between the skin 1 and the substrate layer 3.

[0049] The skin 1 according to the invention preferably is flexible and comprises at least a translucent elastomeric layer 5 having an inner face 6 and an outer face 7 forming the visible surface of the skin 1, i.e. face A. The translucent layer 5 preferably is made of a substantially homogeneously colored plastic material. The term plastic encompasses all synthetic materials including thermosetting and thermoplastic materials. The translucent layer 5 may be a thermoplastic layer or foil, in particular a TPE (thermoplastic elastomer) layer such as a TPO or PVC skin. Such a thermoplastic skin layer can be shaped by a thermoforming process or, for example, by a slush molding process. The elastomeric translucent skin layer 5 also can be produced starting from a curable composition, in particular a curable polyurethane composition. This curable composition is a flowable material which is applied onto a mold surface and cured thereon to produce the translucent skin layer 5.

[0050] The curable composition can be applied by a spraying process onto the surface of an open mold or can be applied to a closed mold, more specifically poured, but preferably injected according to a reaction injection moulding (RIM) process. A light-stable colored PU reaction mixture can be used. Reference can be made to EP 0 303 305, EP 0 379 246, WO 98 / 14492, EP 0 929 586 and WO 04 / 000905, which are hereby incorporated by reference.

[0051] The translucent skin layer 5 is elastomeric, which generally means having an elongation of at least 30%, preferably at least 50%, measured according to DIN / EN / ISO 527-3. Its flexural modulus measured according to ASTM D790-03 preferably is less than 100 MPa, more preferably less than 75 MPa, most preferably less than 55 MPa or even less than 40 MPa. Generally, its overall density is greater than 300 kg / m 3 and preferably greater than 500 kg / m3 Larger, more preferably 600 kg / m 3 Is larger.

[0052] In contrast to the translucent skin layer 5, the substrate layer 3 is relatively rigid and has a flexural modulus of more than 500 MPa, preferably more than 700 MPa, particularly as measured according to ASTM D790. The substrate layer can be made from a thermosetting material, but the substrate is preferably made from a thermoplastic material. This thermoplastic material is preferably selected from the group consisting of PC (polycarbonate), ABS (acrylonitrile butadiene styrene) and ABS blends, particularly PC / ABS, SMA (styrene maleic anhydride), PPO (polyphenylene oxide), TPO (thermoplastic olefin), particularly PP (polypropylene), polyacetal, particularly POM (polyoxymethylenes), nylon, polyester, acrylic and polysulfone.

[0053] The translucent layer 5 of the skin 1 according to the present invention includes at least one first portion 8 disposed in front of the light source 9 and configured to transmit visible light generated by the light source from its inner surface 6 to its outer surface 7. The light source 9 is preferably adhered to the inner surface 6 of the translucent layer 5. This is shown in FIG. 3. In this embodiment, a light-transmissive operating element 10 is further provided between the light source 9 and the translucent layer 5.

[0054] To adhere the light source 9 to the translucent layer 5 or, when the light source 9 combined with the operating element 10 forms part thereof, the light source 9 can be adhered to the translucent layer 5 by an adhesive, or, when the material of the translucent layer 5 has not yet fully cured, the light source 9 can be applied during the manufacture of the translucent layer 5. It is also possible to apply the light source 9 onto the base layer 3 and overmold the light source 9 together with the base layer 3 with the liquid material used to manufacture the translucent layer 5.

[0055] In the embodiment shown in FIG. 3, the light source 9 is adhered to the translucent layer 5 by an inner elastomeric layer 11 formed against the inner surface of the translucent layer 5. The inner elastomeric layer 11 may have the same composition and may be manufactured in the same manner as described above for the translucent layer 5. In particular, both layers 5 and 11 can be manufactured as disclosed in WO 2007 / 137623. The translucent layer 5 is preferably manufactured by applying a first curable polyurethane composition to the mold surface and the inner elastomeric layer 11 by applying a second curable polyurethane composition to the back surface of the translucent layer 5.

[0056] The interior component 2 shown in FIG. 1 is a dashboard. The dashboard 2 comprises an elastomeric skin 1 with an opening for integrating functional elements such as an instrument panel into the skin 1. The skin 1 also includes a region where components including a combination of the operating element 10 and the light source 9 are integrated on the back side of the skin and are hidden from view when the light source 9 is not energized. The operating element 10 and the light source 9 may be provided on an electronic printed foil 12 having a tail protruding from the interior component 2 such that the operating element 10 and the light source 9 can be connected to a controller.

[0057] To avoid deformation of the integrated region when the product is exposed to different ambient temperatures, the integrated printed foil preferably has a shrinkage rate similar to that of the elastomeric skin and / or the E modulus (Young's modulus) must be the same as or less than the E modulus of the elastomeric layer. Printed foils of TPU material are very suitable for use in combination with elastomeric materials.

[0058] The electronic printing foil can already be foreseen in electronic surface mount devices such as LEDs, tactile actuators, electric coils for non-contact charging, RFID readers, antennas, etc. The printed foil may also be an OLED display. The first operating element 10 may be intended to energize different light sources 9 so that the position of the operating element 10 is clearly visible. This comprises an on / off switch formed by a translucent pressure sensor 13 having an operating surface 14. The light source 9 behind the translucent pressure sensor 13 comprises two opposing LEDs 15A and 15B. The space between the LEDs is filled with a light guiding material 16 that diffuses the light of the LEDs in different directions to create uniform illumination of the first portion 8 of the translucent skin layer 5. Further, the operating element 10 can be completely or partially covered by an optical filter that filters a specific wavelength, for example, to show a colored image. Such an optical filter also forms part of the light source 9 to determine the wavelength of the light supplied to the inner surface 6 of the translucent layer 5 by the light source 9. The LEDs 15A and 15B are energized upon initial actuation of the pressure sensor 13 to have a visual indication of the actuation of the operating element 10 and to make the position of the first operating element 10 more clearly visible. Also, the light sources 9 of other hidden operating elements 10 may be energized upon actuation of the first operating element 10 so that they are visible or more clearly visible to the user.

[0059] To indicate the position of the first operating element 10 when its light source 9 is not energized, the first portion 8 of the translucent skin layer 5 preferably has a second surface texture, i.e., a first surface texture different from the surface texture around the first portion.

[0060] Typically, the second surface texture is present over a major portion of the surface of the epidermis. This second surface texture may be, for example, a leather texture, or any other texture used for interior components. Such a leather texture is shown at a larger microscope scale in FIG. 4. It has very deep valleys and very high mountains, and the surface forming the mountains and valleys is also very rough. The surface with such a texture applied is extremely matte.

[0061] As shown in FIG. 4, the first surface texture, i.e., the surface texture of the first portion 8 of the translucent epidermis layer 5, is preferably smoother than the second surface texture. Thus, the surface of this first portion 8 has a higher gloss than the surface of the surrounding epidermis region, and can thus be clearly distinguished from the surrounding portion of the epidermis layer 5.

[0062] The first surface texture can be produced against a completely smooth mold surface, i.e., a non-textured mold surface that can even be polished. The second texture is produced against the textured region of the mold surface.

[0063] To more clearly indicate the position of the first operating element 10 without illumination, a surface relief is provided on the outer surface 7 of the first portion 8 of the translucent layer 5. This surface relief is formed by a surface relief element that includes a central icon 17 indicating an on / off switching function, surrounded by a circle of dots 18 that form not only a clear visual display but also a clear tactile display of the position of the first operating element 10. The dots 18 actually resemble raised Braille dots but are made larger so that they can also be easily felt by less experienced users. Inside the circular icon 17, since the surface of the epidermis is completely smooth, the recessed region within the circular icon 17 can be clearly felt by the user to indicate the location where the user must press to activate the first operating element 10.

[0064] In the case where there is no light source 9 or when the light source is not energized, the surface relief of the first portion 8 of the translucent layer 5 can only be seen when there is sufficient ambient light, for example daylight. According to the present invention, the surface relief should also be visible when there is insufficient ambient light. Therefore, the surface relief on the first portion 8 of the translucent layer 5 is configured to generate an image on the first portion 8 of the translucent layer 5 by visible light generated by the light source 9 and transmitted through the translucent layer 5 from its inner surface 6 to its outer surface 7. The images generated by the surface relief shown in FIGS. 2 to 4 can be seen in FIG. 6.

[0065] From the photograph shown in FIG. 6, it is clear that the light source 9 not only makes the image visible in the dark, but also enhances its visibility during the day.

[0066] According to the present invention, it has been found that the desired image can be obtained by a specific selection of the thickness difference caused by the surface relief and the average spectral attenuation coefficient α of the colored plastic material of the translucent layer 5 av of.

[0067] The inventors conducted tests to investigate the effect of the thickness of the translucent layer on the light transmittance of the translucent layer. This test demonstrated an exponential relationship between the layer thickness and the light transmittance through the layer. The light transmittance is the ratio of the illuminance, which is the luminous flux (lux) incident on one side of the translucent layer, to the luminous flux (lux) exiting from the other side of the translucent layer. The inventors found that the surface relief should preferably reduce the light transmittance of the second, thicker region to less than at least 50% of the light transmittance of the first, thicker region to create a clearly visible contrast between the different regions, and that the greater the difference in light transmittance, the better the surface relief elements are visible.

[0068] In the embodiments shown in FIGS. 2 to 4, where an image shown in FIG. 6 is generated when the light source 9 is energized, the first portion 8 of the translucent skin layer 5 includes at least one first region 19, and the translucent layer 5 has a thickness of not more than a first thickness d1. In this embodiment, the first region 19 has a smooth surface and has a thickness d1 of about 0.55 mm. However, the first region can exhibit some texture or roughness, in which case the surface of the valley where the translucent layer has a thinner thickness is also included in the first region. Due to the surface relief, the first portion 8 of the translucent skin layer 5 further includes at least a half region 20, and the translucent layer 5 has a thickness of not less than a second thickness d2. In the embodiments of FIGS. 2 to 4, the central icon 17 and the dot 18 have a height h of about 0.17 mm such that the translucent layer 5 has a thickness of about 0.72 mm at the position above these surface relief elements. Since the dot 18 is dome-shaped, only a small region of the first portion 8 of the light-transmitting skin layer 5 has such a large thickness. Therefore, the second region 20 is defined as a region where the translucent layer 5 has a thickness of not less than a second thickness d2 equal to, for example, 0.70 mm.

[0069] According to the present invention, the difference in thickness between the regions 19 and 20 that should be visually distinguishable on the first portion 8 of the translucent layer 5, that is, the difference between the first thickness d1 and the second thickness d2, must be greater than at least 0.08 mm and less than 3.0 mm. Therefore, the height h of the icon 17 and the dot 18 must be greater than at least 0.08 mm, or preferably greater than at least 0.10 mm.

[0070] The decrease in light transmittance by only the large thickness d2 compared to d1 depends not only on this difference d2 - d1 in thickness but also on the average spectral attenuation coefficient α av According to the present invention, this average attenuation coefficient is greater than 1 mm -1 or preferably greater than 2 mm -1 or even more preferably greater than 3 mm -1 or most preferably greater than 4 mm -1 or greater than 5 mm -1It must be larger. The larger the average attenuation coefficient, the smaller the difference in the thickness d2 - d1 of the translucent layer 5 can actually be made to obtain the same reduction in light transmission. On the other hand, the average spectral attenuation coefficient α av shall be less than 25 mm -1 or preferably further less than 20 mm -1 or more preferably less than 15 mm -1 or most preferably less than 10 mm -1 should be. In this way, the thickness d1 of the first thin region 19 can be large enough to provide the necessary mechanical properties for the translucent skin layer 5 without requiring an overly strong light source.

[0071] The average spectral attenuation coefficient α av should be determined based on the transmittance of a film (sheet) of the colored plastic material of the translucent layer 5 having a uniform thickness equal to the above-mentioned first thickness d1. EN ISO13468-2:2006 Part 2 discloses a method for measuring the spectral transmittance T1(λ), which is the total transmittance of monochromatic radiation of a given wavelength λ at 5 nm intervals over the entire range of visible wavelengths, i.e., 380 nm to 780 nm. According to the present invention, the spectral attenuation coefficient is then Equation (I): is determined for each wavelength λ using TIFF0007702405000003.tif3684. Then, the average spectral attenuation coefficient α av can be determined as the mathematical average of these different spectral attenuation coefficients α(λ).

[0072] Then, the average spectral attenuation coefficient α av can be calculated over the entire range of visible light wavelengths. This can be done especially when the light source 9 behind the first part 8 of the translucent layer 5 emits white light, i.e., light containing all wavelengths between 380 and 780 nm. However, when the light source 9 emits light containing a narrower wavelength range, the average spectral attenuation coefficient α avshould preferably be determined over this narrower wavelength range. When two or more light sources 9 emitting light including different wavelength ranges are provided behind the translucent layer 5, different average spectral attenuation coefficients α av should preferably be determined, i.e., should be determined as an average over different wavelength ranges, so that images of different colors are preferably all generated in accordance with the present invention.

[0073] Apart from the above selection of the range of the thickness difference d2 - d1 and the range of the average spectral attenuation coefficient determined over the range of the wavelengths emitted by the light source (or light sources), a further requirement that must be met is that α av and / or d2 - d1 must be large enough such that α av (d2 - d1) > -ln a, where the value a is equal to 0.50 (ln a is the loge value or natural logarithm of a). If the transmittance T1 of a film (sheet) of a translucent plastic material having a thickness d1 is defined by the following equation, TIFF0007702405000004.tif3175 ; the transmittance T2 of a film (sheet) of a translucent plastic material having a greater thickness d2 corresponds at least substantially to the value obtained by the following equation. TIFF0007702405000005.tif34117 or TIFF0007702405000006.tif34117. Thus, when a is equal to 0.50, the transmittance of the second thicker region 20 is at least about 50% less than the transmittance of the first thinner region 19. This allows the second region 20 to be clearly visually distinguishable from the first region 19 when the light source 9 is energized. Preferably, a greater contrast between the first region 19 and the second region 20 is obtained by reducing the value of a to be equal to 0.45, preferably equal to 0.40, more preferably equal to 0.35, and most preferably equal to 0.30. For these values of a, the reduction in the transmittance of the thicker region 20 substantially corresponds to reductions of 55%, 60%, 65%, and 70% respectively.

[0074] As already described hereinabove, in the embodiments shown in FIGS. 2 - 4 for generating the image shown in FIG. 6, the thickness d1 of the first thinner region 19 is equal to about 0.55 mm and the thickness d2 of the second thicker region 20 is equal to 0.70 mm (or locally up to 0.72 mm maximum). This semi - transparent skin layer's colored semi - transparent polyurethane material has an average spectral attenuation coefficient α -1 of about 6.9 mm av measured over the entire range of visible light wavelengths. Thus, the transmittance T2 is at least about 64% less than the transmittance T1 (up to about 69% less for a thickness difference of 0.17 mm). This results in a clear visual distinction between the first thinner region 19 and the second thicker region 20 as seen in FIG. 6. Equation TIFF0007702405000007.tif2458 Based on this, the transmittance of the first thinner region 19 can be calculated to be about 0.022, i.e., about 2.2%. The image generated using a 1500 - lux light source as shown in FIG. 6 can be clearly seen in a dark room or a slightly illuminated room, but is not very visible in daylight. The average spectral attenuation coefficient of this material corresponds to a transmittance of about 0.033 for a thickness of 6.2 mm -1When the pigment contained in the colored plastic material is less so as to decrease, the image can be seen better in a well-lit room. Although it is not very sharp in full daylight, it can still be seen.

[0075] In the embodiments shown in FIGS. 2 to 4, the relief elements that generate the surface relief, i.e., the central icon 17 and the dots 18, provide a second thicker region 20 of the first part 8 of the translucent layer 5. Alternatively, the translucent layer 5 can be made thicker, and the surface relief elements 17 and 18 can be formed by depressions on the outer surface 7 of the translucent layer 5 that form a first thinner region 19 of the translucent skin layer 5. In this way, the surface relief elements 17 and 18 will appear as brighter regions within a darker background.

[0076] When the translucent layer 5 is formed on the surface of the rigid part including the light source 9 and any operating elements 10, a surface relief can also be formed on the inner surface 6 of the translucent layer 5. In this way, as a result of the difference in transmittance caused again by the surface relief, an image can also be obtained on the outer surface 7 of the translucent layer 5 when the light source 9 is energized. The negative characteristics of the surface relief can be provided on the surface of the light source directed towards the translucent layer, and the translucent layer can be manufactured, for example, by a partial reactive overmolding process with respect to the surface of the light source. It is also possible to provide surface reliefs on both the inner surface 6 and the outer surface 7 of the translucent layer 5.

[0077] Due to the fact that the translucent layer 5 is made of a colored material having the above average spectral attenuation coefficient, it is also possible to provide a flat screen display on the back surface of the translucent layer 5. Such a flat screen display 21 is schematically shown in FIGS. 1 and 5. The illustrated flat screen display comprises a flexible OLED screen 21 adhered to the inner surface 6 of the second part 22 of the translucent layer 5. Since the thickness of the translucent layer 5 is relatively small and the attenuation coefficient is relatively small, the image generated by the flat screen display 21 can be seen through the translucent layer 5.

[0078] The outer surface 7 of the second portion 22 of the translucent layer 5 is preferably completely smooth or has little gloss so as to be difficult to visually recognize when the display 21 is not energized, and can exhibit some surface texture or roughness so as to better match the surrounding surface area.

[0079] Preferably, the inner surface 6 and the outer surface 7 of the second portion 22 of the translucent layer 5 have a surface texture that is completely smooth or has a Pt value measured in accordance with DIN EN ISO 4287:1998, and the Pt value in mm satisfies the following formula (III): TIFF0007702405000008.tif3158 wherein b is greater than 0.50, preferably greater than 0.60, more preferably greater than 0.70, and the average spectral attenuation coefficient (α av ) is preferably determined for any range of visible light wavelengths emitted by a flat screen display.

[0080] Therefore, the difference in light transmittance between the peak and the valley of the texture is less than about 50%, or preferably less than 40% or less than 30%. Locally, a relief element can be provided in the second portion 22 of the translucent layer 5 to provide an additional image in front of the image generated by the flat screen display 21.

[0081] As seen in FIGS. 3 and 5, the different light sources 9 and the flat screen display 21 are preferably embedded between the translucent layer 5 and the inner elastomeric layer 11. Thus, even when the light source 9 or the flat screen display 21 does not adhere to the translucent layer 5, the light source 9 or the flat screen display 21 is adhered to the translucent layer 5 by the inner elastomeric layer 11.

Claims

1. An outer skin (1) for a vehicle interior part (2), wherein the outer skin (1) comprises at least one translucent elastomer layer (5) made of a colored plastic material, the translucent layer (5) having an outer surface (7) and an inner surface (6) opposite to the outer surface (7), the translucent layer (5) being arranged in front of a light source (9) and being configured to transmit visible light generated by the light source (9) from the inner surface (6) to the outer surface (7), and comprising at least one first portion (8). The first portion (8) of the translucent layer (5) includes a surface relief on the outer surface (7) and / or the inner surface (6) in order to generate an image on the first portion (8) when the visible light passes through the first portion (8) of the translucent layer (5). The surface relief forms at least one first region (19) in which the translucent layer (5) has a thickness of at most a first thickness (d1) and at least one second region (20) in which the translucent layer (5) has a thickness of at least a second thickness (d2) greater than the first thickness (d1). The first thickness (d １ ), and the difference (d ２ ), between the first thickness (d ２ -d １ ) is greater than 0.08 mm but less than 3.0 mm, The colored plastic material has an average spectral attenuation coefficient (α ａｖ ) over the visible light wavelength range from 380 to 780 nm, and the average spectral attenuation coefficient is the average of the spectral attenuation coefficients (α(λ)) determined by the following formula (I) at regular intervals, particularly at intervals of 5 nm, over the visible wavelength range. (I) where T １ is the spectral transmittance at the wavelength (λ) of the film of the colored plastic material having a uniform thickness (d), measured in accordance with EN ISO 13468-2:2006 Part 2, d = the thickness of the film The average spectral attenuation coefficient (α ａｖ ) is included between 1.0 mm －１ and 25 mm －１ and is related to the difference (d １ −d ２ ) between the first thickness (d ２ ) and the second thickness (d １ ) according to the following formula (II). α ａｖ (d ２ - d １ ) > -In 0.05 (II) and characterized in that it is an outer skin (1).

2. The difference (d2 - d1) between the first thickness (d1) and the second thickness (d2) follows the following formula αav(d2 - d1) > -In0.45 characterized in that it is the outer skin according to claim 1.

3.

4. The difference (d １ - d ２ ), between the first thickness (d ２ ), and the second thickness (d １ ), is greater than 0.10 mm, the skin according to claim 1 or 2.

5. The difference between the first thickness (d １ ), and the second thickness (d ２ ), (d ２ -d １ ) is less than 2.0 mm, characterized in that the epidermis according to any one of claims 1 to 3.

6. The average spectral attenuation coefficient (α ａｖ ) is greater than 2.0 mm －１ , and the epidermis according to any one of claims 1 to 4, characterized in that.

7. The average spectral attenuation coefficient (α ａｖ ) is less than 20.0 mm －１ The epidermis according to any one of claims 1 to 5, characterized in that it is smaller than that.

8. The outer skin according to any one of claims 1 to 6, characterized in that the first portion (8) of the translucent layer (5) has an average thickness of less than 2.0 mm.

9.

10. The outer skin according to any one of claims 1 to 7, characterized in that the first portion (8) of the translucent layer (5) has an average thickness greater than 0.2 mm.

11.

12. The outer skin according to any one of claims 1 to 8, characterized in that the first portion (8) of the translucent layer (5) is provided with the surface relief on its outer surface (7).

13.

14. The outer skin (1) according to any one of claims 1 to 9, characterized in that it is adhered to the inner surface (6) of the first portion (8) of the translucent layer (5) and comprises at least one light source (9) configured to emit visible light having a predetermined wavelength range.

15. ​ The skin (1) comprises an inner elastomer layer (11) adhered to the inner surface (6) of the translucent elastomer layer (5), and the light source (9) is embedded between the translucent elastomer layer (5) and the inner elastomer layer (11). The skin according to claim 10, characterized in that.

12. The skin according to claim 11, characterized in that the light source (9) includes at least one LED (15A, 15B) embedded between the translucent elastomer layer (5) and the inner elastomer layer (11).

13. The skin according to any one of claims 1 to 12, characterized in that the skin (1) comprises a flat screen display (21) adhered to the inner surface (6) of the second part (22) of the translucent layer (5), and the second part (22) is configured to transmit visible light generated by the flat screen display (21) from the inner surface (6) to the outer surface (7).

14. The inner surface (6) and the outer surface (7) of the second part (22) of the translucent layer (5) have a surface texture having a Pt value measured in accordance with DIN EN ISO 4287: 1998, and the Pt value in mm satisfies the following formula (III). (III) where b is equal to 0.

50. The skin according to claim 13, characterized in that.

15. The skin according to claim 13 or 14, characterized in that the skin (1) includes an inner elastomer layer (11) adhered to the inner surface (6) of the translucent elastomer layer (5), and the flat screen display (21) is embedded between the translucent elastomer layer (5) and the inner elastomer layer (11).

Images