Function displays and associated operating elements with selectively displayed symbols

Abstract

The present invention relates to a functional display, comprising: a stack of optical waveguides forming a display surface facing an observer; the optical waveguide stack is formed by at least two transparent or translucent planar optical waveguides arranged overlapping in the stacking direction, the optical waveguides being arranged as transparent or translucent layers, the layers being formed by a material that is optically thinner than that of adjacent optical waveguides; at least one light source of each optical waveguide is arranged so that light is incident into the corresponding optical waveguide via the end face of the relevant optical waveguide; wherein each optical waveguide is also provided with at least one microstructured symbol area arranged in or on the optical waveguide, comprising a plurality of microstructures and being formed so as to be visible to an observer by illumination with the aid of light incident into the optical waveguide when the light source is activated; and a reflector arranged on the side of the optical waveguide stack facing away from the observer so as to reflect light incident into at least one optical waveguide and subsequently emitted from the optical waveguide toward the observer.

Description

Technical Field

[0001] The invention relates to a function display for selectively displaying at least one symbol representing a switch function and / or a plurality of switch states. Background Art

[0002] These functional displays are necessary, for example, in multifunctional operating elements, in order to visualize the switch functions and / or switch states associated with the operating elements. Electronic pixel matrix displays are usually used for this purpose. However, they are relatively expensive, and their configuration design and placement are limited due to their rectangular shape in most cases. In addition, electronic pixel matrix displays are usually prone to "screen burn-in" when displaying static display content, that is, due to the visually perceptible damage of the imaging layer of the display, the display content is undesirably kept visible even when the display is turned off. In addition, the power consumption of such electronic pixel matrix displays is relatively high. In addition, in certain applications, due to the risk of injury, for example, in the case of a head collision, the use of conventional electronic pixel matrix displays is prohibited. As an alternative to pixel matrix displays, it is known that the light of the light source incident on the end face of the light conductor is emitted in a targeted manner by means of a surface structure at the main surface used as a display surface, wherein only a region with a surface structure is locally provided and symbols, etc. are reproduced. The disadvantage here is that the symbols are visually unnoticeable in most cases and may therefore be easily overlooked by the observer. This leads to the observer, especially the vehicle driver, for example, misestimating the actual switch state. Summary of the invention

[0003] Against this background, the object of the present invention is to provide a functional display which creates the possibility of increasing the richness of the display and thus the attention of the observer, which can in particular generate a depth effect by means of an additional display plane and which can also be produced cost-effectively, which is energy-saving and reliable and / or reduces the risk of injury in particular in the case of head impacts. It should be noted that the features specified individually in the claims can be combined with one another in any technically meaningful manner and represent further embodiments of the invention. The description additionally characterizes and explains the invention in detail, in particular in conjunction with the drawings.

[0004] The invention relates to a function display, in particular for a motor vehicle, for selectively displaying at least one symbol representing a switch function and / or a plurality of switch states. Selective display is understood not only to mean the selective display of different symbols from a plurality of predefined symbols, which is achieved in the solution according to the invention by selectively selecting one or more light sources from a plurality of light sources and energizing them, but also to mean switching the light sources on and off in order to selectively visually make the symbol visible to an observer by means of activated backlighting or to make the symbol as nearly invisible as possible to the observer by means of switched-off backlighting.

[0005] The functional display according to the invention has a stack of optical conductors, which, when the functional display is installed as intended, forms a display surface facing an observer. The optical conductor stack is formed by at least two transparent or translucent planar optical conductors arranged one above the other in the stacking direction, the optical conductors being arranged to be separated by a transparent or translucent layer, preferably via an air gap, which is formed by a material that is optically thinner than that of adjacent optical conductors. In this case, the optical conductors each have a main surface facing the observer and a main surface facing away from the observer. At least one optical conductor has a main surface facing away from the observer facing the next adjacent optical conductor in the stacking direction.

[0006] The functional display according to the invention can optionally have an outer transparent or translucent cover layer arranged between the light conductor stack and an observer, through which the display surface defined by the light conductor stack is visible to the observer when the functional display is arranged as intended. The material of the cover layer and the light conductor is, for example, a plastic, preferably a thermoplastic, such as polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), acrylonitrile-butadiene-styrene (ABS) or polymethyl methacrylate (PMMA), or a glass material.

[0007] According to the present invention, each optical waveguide is provided with at least one light source, which is arranged to allow light to enter the corresponding optical waveguide via the end face of the relevant optical waveguide. The optical waveguide has, for example, two main faces that are opposite to each other and preferably extend parallel to each other, which are connected via end faces, for example at the narrow side and at the long side of the optical waveguide, and the end faces form a common edge together with the main faces of the optical waveguide. The end faces are, for example, orthogonal to at least one main face or both main faces of the optical waveguide.

[0008] The light source is, for example, a light emitting diode, in particular a light emitting diode in SMD design. In order to improve the light input and / or to adapt the light emission characteristics of the light source to the end face defined for the entry of light into the optical waveguide, a lens and / or a baffle and / or a light channel is preferably arranged between the optical waveguide and the light source, respectively. The baffle or the light channel is also formed, for example, to suppress the escape of light to an observer, other layers or optical waveguides other than the assigned optical waveguide.

[0009] According to the invention, each optical waveguide is also provided with a microstructured symbol area arranged in or on the optical waveguide, the symbol area comprising a plurality of light-refracting and / or light-scattering microstructures. The microstructured symbol area alone or together with other microstructured symbol areas of the same optical waveguide or another optical waveguide forms a symbol which, due to the light refraction and / or light scattering produced by the plurality of microstructures at the surface of the respective microstructure, becomes luminous and visible to an observer with the aid of light incident into the respective optical waveguide when the light source is activated. For example, the microstructures realize an angle of incidence of the light onto the relevant main surface which does not satisfy the total reflection condition of the main surface of the optical waveguide as an interface, so that the light incident into the optical waveguide leaves the optical waveguide again.

[0010] According to the invention, a preferably partially transmissive (that is to say partially transparent) reflector is arranged on the side of the optical waveguide stack facing away from the observer, the reflector being designed to reflect light incident into at least one of the optical waveguides and subsequently emerging from the optical waveguide by means of associated microstructures in the direction of the observer. The reflector is produced, for example, by metal vapor deposition on a substrate, in particular a transparent substrate such as a foil, a thermoplastic layer or a layer formed from a glass material.

[0011] This makes it possible to achieve a depth effect of the display device relatively simply and cost-effectively by having the reflector provide a further display plane offset to the back relative to the optical waveguide of the optical waveguide stack for the observer, the display plane being located, for example, in a virtual image plane of the reflector. This depth effect cannot be achieved by using the optical waveguide stack alone and provides an additional optical attraction for the observer.

[0012] The microstructure of at least one microstructured optical waveguide is preferably formed so that the light incident into the corresponding optical waveguide is emitted in the direction of the observer, that is, bypassing the reflector. Thus, at the observer, a depth effect or even a three-dimensional impression of the displayed symbol can be achieved through different display planes depending on the activation of the light source. This is achieved, for example, by displaying the symbol area using a reflector and displaying the same symbol area of ​​the same or another optical waveguide of the optical waveguide stack bypassing the reflector, wherein the parallax offset of the symbol area suggests the three-dimensional nature of the displayed symbol to the binocular observer. By switching between the symbol display using a reflector and the symbol display of another optical waveguide of the optical waveguide stack bypassing the reflector in a time sequence in another design scheme, the observer's attention can also be attracted to the functional display, which is achieved by changing the display plane of the functional display. By selectively activating the light source, different light-on states or switch functions can be visualized relatively simply. The functional display can be realized simply and inexpensively and provides a large design space for the designer, which also involves the placement of the functional display. The functional display shows aging phenomena that are almost unaffected by light radiation and is relatively energy-saving. Microstructuring reproduces the symbol in positive relief as an image, as its inverse representation or as its outline. The depth effect mentioned above can be set, for example, by the distance between the light conductors, for example the air gap thickness. The distance is, for example, in the range of 1 to 3 mm.

[0013] The microstructured symbol area can be introduced into the light guide by laser ablation, for example by glass three-dimensional painting (Vitrographie, also known as laser internal engraving) in three dimensions or applied to one of its main surfaces. The microstructured symbol area is preferably formed by embossing one of the main surfaces of each light guide, thereby making it possible to realize a functional display cost-effectively.

[0014] The microstructured symbol area is preferably formed by a plurality of microstructures formed in the same shape, which together define a continuous microstructured symbol area of ​​each optical conductor. The microstructure is preferably understood as a single protrusion on the main surface or a single depression in the main surface. In order to basically exclude naked eye visibility, the maximum size of each microstructure is, for example, in the range of 1 to 50 μm, preferably in the range of 1 μm to 25 μm. The microstructures are preferably arranged to be evenly spaced and distributed on the entire microstructured symbol area of ​​the main surface. The microstructures are, for example, shaped in the shape of a pyramid or a prism. The microstructures are preferably not only of the same shape, that is, uniformly shaped, but also have a consistent orientation within the corresponding microstructured symbol area. For example, only when each microstructure can be mapped to the adjacent microstructure of the same microstructured symbol area by an imaginary, only translational offset, can a consistent orientation be produced on a flat main surface. The microstructure is preferably formed in such a way that it generates a collimated light beam, which is formed from light exiting from the light guide body, which light beam originates from the light source and has previously entered the light guide body via the end face.

[0015] The average number density of the microstructures of each microstructured symbol region of the optical waveguide stack is preferably between 500 and 7000 per mm 2 In the range between 1000 and 4000 per mm 2 . This ensures that the light source is invisible when it is switched off, while the light source is activated and the impression of a uniformly illuminated symbol area can be simulated for the "naked" eye. The average number density of each light conductor is preferably selected to be substantially the same, wherein "substantially the same" is understood to mean that the number density of the light conductors is less than 100 per mm. 2 The maximum deviation.

[0016] Preferably, at least two directly adjacent light guides are provided, the microstructuring of which is provided only on main surfaces facing away from one another.

[0017] All light guides outside the microstructured area are transparent and the reflectors are partially transmissive, so that a large part of the functional display remains at least partially see-through and, for example, a see-through through the functional display is ensured, in order to give the viewer the possibility of following other displays, instruments or the course of the road through the functional display. This makes it possible, for example, to place the functional display on the steering wheel, for example in the area between the steering wheel hub and the steering wheel rim, without affecting the view of the instrument panel. The area proportion of all surface-structured symbol areas on the display surface preferably accounts for less than half.

[0018] The corresponding light guide does not necessarily need to be formed in one piece, and the light guide can be composed of multiple parts. In one design, the light guides each have at least one foil, such as a multi-layer foil layer structure. For example, the light guide is produced by back injection molding a transparent foil (such as a PC foil or a PE foil) with a first material, especially a thermoplastic.

[0019] According to a preferred embodiment, when viewing the display area vertically, in particular starting from a position above the geometric center of the display area, the microstructured symbol areas of at least two light guides of the light guide stack are non-overlapping for the observer and are preferably arranged spaced apart from one another.

[0020] According to a preferred embodiment, when viewing the display surface vertically, in particular starting from a position above the geometric center point of the display surface, the microstructured symbol areas of at least two light guides of the light guide stack are arranged adjacent to each other, preferably overlapping, more preferably completely overlapping for the observer.

[0021] In order to provide an additional color effect, according to a preferred configuration, at least two light sources are different from each other in terms of light color.

[0022] It is preferably proposed that the light conductor has at least one curved interface in the respective light path from the light source to the relevant symbol area in order to form at least one focusing lens element. The light conductor forms, at its end face, for example, a curved light incident surface provided for the light of the light source. In another design, the light conductor has one or more interruptions, each of which has an interface that functions as a light exit surface and a light incident surface, wherein at least one interruption is curved in a manner that optically focuses, and preferably both interruptions are curved in a manner that optically focuses.

[0023] In order to avoid unwanted light propagation in the corresponding light conductor, in particular when external light acts, according to a preferred embodiment, the corresponding light conductor has an anti-reflection coating at at least one of the end faces, preferably at the end face opposite the end face facing the light source, which is usually also referred to as an anti-reflection coating or compensation layer. The task of the anti-reflection coating is to reduce the amount of light reflected into the light conductor at the coated end face, for example by absorbing light in the coating, compared to an uncoated end face. For example, the anti-reflection coating can be applied all around, except for the light entrance area provided for the light of the light source. The anti-reflection coating has, for example, an optical refractive index that is numerically between air and the material of the light conductor or the shielding layer.

[0024] The invention also relates to an assembly, which is formed by a plurality of functional displays, each of which is formed in one of the previously described embodiments. The assembly is characterized by a plurality of display surfaces which are arranged side by side from the perspective of an observer. In the assembly, at least the cover layer and / or at least one optical waveguide are formed in one piece, so as to form, for example, a common cover layer or a common optical waveguide. In order to suppress crosstalk of light from an optical waveguide of a functional display into an optical waveguide of another functional display of the assembly even in the case of integration, for example, an interruption is provided, which is filled with a material that is optically thinner than the material of the optical waveguide, for example air.

[0025] The invention also relates to an operating element having a functional display formed in one of the previously described embodiments. The operating element has, for example, a leg for fixing the operating element to a vehicle component such as an instrument panel, a lining of a passenger compartment or, in particular, a steering wheel of a motor vehicle. The operating element of the invention also has, for example, an operating part defining an operating surface, which is formed as at least one self-supporting lever arm. The self-supporting lever arm is supported on one side at the leg by means of a solid joint, for example, so that under the action of an operating force acting perpendicularly to the operating surface, the operating part can be pivoted relative to the leg against a reset force about an imaginary pivot axis. For example, a device is also provided in order to detect the degree of pivoting between the operating part and the leg. Generally, the following area of ​​the component is referred to as a solid joint: the area allows pivoting between two rigid body areas by bending. The solid joint enables the operating part to be supported at the leg without play and thus without rattling noise. The legs and the operating element are formed, for example, from thermoplastics such as polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), acrylonitrile butadiene styrene (ABS) or polymethyl methacrylate (PMMA). The operating element of the invention is particularly suitable for designs in which the maximum pivoting degree from the unactuated rest position about the imaginary pivot axis to the actuated maximum pivot position is less than 10°, preferably less than 5°.

[0026] The display surface is preferably a translucent or transparent region of an operating surface of the operating element which is intended as an operating part for contact or actuation.

[0027] The invention also relates to a steering wheel, which has, for example, a steering wheel hub, at least one steering wheel spoke and a steering wheel rim carried by the steering wheel spokes. The steering wheel according to the invention also has a function display formed in one of the previously described embodiments. The function display is preferably a component of an operating element fastened to the steering wheel. The legs of the operating element are, for example, fixedly secured to the steering wheel rim in a rotationally fixed manner. The display surface of the function display is preferably arranged between the steering wheel rim and the steering wheel hub or a buffer of the steering wheel covering the steering wheel hub. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention and the technical environment are explained in detail below with the aid of the accompanying drawings. It should be noted that the accompanying drawings show particularly preferred implementation variants of the present invention, but the present invention is not limited to these implementation variants. The accompanying drawings schematically show:

[0029] Figure 1 A schematic cross-sectional view of a first embodiment of the invention of a functional display 1;

[0030] Figure 2 Schematic sectional view of an embodiment of the invention of an operating element 10 with a functional display;

[0031] Figure 3 A top view of a steering wheel according to the invention with an operating element 10 including a functional display 1;

[0032] Figure 4 Horizontal cross-section of an assembly according to the invention formed by two functional displays 1 , 1 ′;

[0033] Figure 5 Horizontal section through another assembly according to the invention formed by two functional displays 1 , 1 ′. DETAILED DESCRIPTION

[0034] Figure 1 A first embodiment of a functional display 1 according to the invention is schematically shown. The functional display 1 comprises an outer transparent or translucent, but at the same time not mandatory and only optionally provided, cover layer 23, which defines the surface facing the observer B in the intended arrangement of the functional display 1. The cover layer is, for example, a layer made of plastic, preferably thermoplastic, such as polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinyl chloride (PVC), polyamide (PA), acrylonitrile-butadiene-styrene (ABS) or polymethyl methacrylate (PMMA), or of a glass material. The cover layer 23 can also be part of a layer structure formed by a plurality of layers.

[0035] According to the invention, the functional display 1 also necessarily comprises a light conductor stack, which is formed by at least two transparent or translucent planar light conductors 13, 14 arranged one above the other and each formed by a thermoplastic layer or a thermoplastic foil. The light conductors 13, 14 are separated by a layer 24 arranged between the light conductors 13, 14, which layer (here an air gap) is formed by a material (here air) having a lower refractive index than the refractive index of the adjacent light conductors 13, 14. This air layer 24 is also arranged between the cover layer 23 and the nearest adjacent light conductor 13. The light conductors 13, 14 each form at least a main surface H facing the observer B and a main surface H' facing away from the observer, while the upper light conductor 13 closer to the observer B has a main surface H' facing away from the observer and facing the next adjacent light conductor 14 in the stacking direction.

[0036] The light conductors 13, 14 are each assigned a light source 12, namely a light emitting diode in the form of an SMD design, which is arranged so that the light generated by it is incident on the assigned light conductor 13, 14 via an end face S lateral to the stacking direction. In order to avoid undesired light scattering or light radiation entering adjacent light conductors 13, 14, a baffle 17 is provided. At the end faces opposite each other, an anti-reflection coating 33 is applied to the end faces of the light conductors 13, 14 in order to minimize the back reflection in the respective light conductor 13, 14, while the light conductors 13, 14 are fixed in a form-fitting manner in a frame 25. In at least one main surface of the light conductor 13, here in the main surface H' facing away from the observer, a plurality of individual microstructures 16 are introduced by embossing or shaping, which ensure that the light L incident on the light conductor 13 is emitted from the respective light conductor 13 in the direction of the observer B by light refraction and / or light scattering and define a microstructured symbol area including the microstructures 16. This symbol area alone or in optical cooperation with other symbol areas again produces the shape of a symbol which is visible in light for an observer B when the associated light source 12 is activated accordingly.

[0037] The microstructures 16 are formed to be identical to one another and have a maximum diameter in the range of 1 to 25 μm. The optical waveguide 14 facing away from the observer B also has microstructures 26 in its main surface H facing the observer B, which are also single and are formed to be identical to one another. These microstructures are also introduced into the relevant main surface of the optical waveguide 14, here the main surface H facing the observer B, by embossing or shaping. These couple the light L' incident into the optical waveguide 14 in the direction of a reflector 27, which is arranged on the side of the optical waveguide stack formed by the optical waveguides 13, 14 facing away from the observer B, and in this case the reflector is in the form of a partially transmissive metal vapor coating on a transparent plastic layer 28, which is arranged here at a distance from the optical waveguide 14 by an air gap 24, alternatively an arrangement adjacent to the optical waveguide 14 is also conceivable.

[0038] Only by reflection by the reflector 27 is the light L′ originally incident on the optical waveguide 14 reflected in the direction of the observer B. As a result, at the observer B, a depth effect or even a three-dimensional impression of the displayed symbol can be achieved through different display planes depending on the activation of the light source 12. In one embodiment, this is achieved, for example, by a simultaneous display of a symbol area of ​​the lower optical waveguide 14 of the optical waveguide stack using a reflector and of the same symbol area of ​​the upper optical waveguide bypassing the reflector, wherein a parallax shift of the symbol area creates an illusion of the three-dimensional nature of the displayed symbol for a binocular observer.

[0039] By switching between the symbol display of the lower optical waveguide 14 of the optical waveguide stack using a reflector and the symbol display of the upper optical waveguide 13 bypassing the reflector in a time sequence in another design scheme, the observer's attention can also be attracted to the functional display 1, which is achieved by changing the display plane of the functional display 1. By selectively activating the light source, different light-on states or switch functions can be visualized relatively simply. The functional display 1 can be realized simply and cost-effectively and provides the designer with a lot of design space, which also involves the placement of the functional display 1. The functional display shows aging phenomena that are almost unaffected by light radiation and is relatively energy-saving. The microstructured symbol area, for example, reproduces the symbol in positive text as an image, as its opposite illustration or as its outline alone or together with other symbol areas. The depth effect mentioned above can be set, for example, by the distance between the optical waveguides 13 and 14, such as the air gap thickness. The distance is, for example, in the range of 1 to 3 mm.

[0040] All optical waveguides 13, 14 are transparent outside the microstructured area. Since the reflector 17 is also partially transparent, a large part of the display surface 8 is optically transparent, so that, for example, a perspective through the functional display is guaranteed, so as to give the observer B the possibility to follow other displays or the direction of the road through the functional display. As a result, for example, the functional display 1 can be placed at the steering wheel, for example in the area between the steering wheel hub and the steering wheel ring, without affecting the view of the instrument panel. When the display surface 8 is observed perpendicularly to the microstructured areas of all optical waveguides 13, 14, the projected microstructured symbol areas of the individual optical waveguides 13, 14 do not overlap, so as not to affect the display quality of the symbol.

[0041] Figure 2 An embodiment of an operating element 1 according to the invention is shown. This operating element has a leg 3 for fastening the operating element 1 to a vehicle component such as an instrument panel, a lining of a passenger compartment or in particular a steering wheel rim 11 of a motor vehicle steering wheel. The operating element 10 according to the invention also has an operating part 2 which defines an operating surface 9 and is formed as at least one self-supporting lever arm. The self-supporting lever arm is supported on one side at the leg 3 by means of a solid joint 4 in each case so that under the action of an actuating force acting perpendicularly to the operating surface 9, the operating part 2 can be pivoted relative to the leg 3 against a restoring force about an imaginary pivot axis A. The restoring force is generated, for example, by a deformation of the solid joint 4.

[0042] According to the invention, a device 6 is also provided for detecting the degree of pivoting between the operating part 2 and the leg 3. The solid joint 4 is formed only by the integral connection between the leg 3 and the operating part 2. The operating element 1 according to the invention is particularly suitable for the following design, in which Figure 2 The maximum pivoting degree from the unactuated rest position shown in FIG. 1 about the imaginary pivot axis A to the maximum possible actuated pivot position is less than 10°, preferably less than 5°.

[0043] According to the invention, an actuator 5 is also provided which can be acted upon by an electronic control device (not shown) with an electrical control signal in order to generate an active haptic feedback (also referred to as a tactilely perceptible output), wherein the actuator 5 is preferably fixed only to the operating part 2. The actuator 5 is preferably an inertial, motor-based actuator, such as an electric motor or a magnet coil actuator or a piezoelectric actuator or a linear broadband actuator such as a plunger coil actuator (English name: Voice-Coil-Actuator) or a linear resonant actuator, which has a mass body mounted eccentrically relative to its center of gravity fixed to its rotating drive shaft. The actuator 5 is preferably fixed to the operating part 2 by a force-fitting or material-fitting connection, for example by screwing or bonding. Due to the fact that it is fixed only to the operating part 2, the input of structure-borne noise into the steering wheel rim 11 and thus into the vehicle components is prevented or at least minimized.

[0044] The means 6 for detecting the degree of pivoting are formed to detect the degree of pivoting capacitively, optically and / or inductively between the leg 3 and the operating part 2. Due to the cooperation of the play-free support of the operating part 2 by the solid joint 4 and the means 6 for detecting the degree of pivoting, preferably contactlessly, a low-hysteresis to hysteresis-free detection of the actuating force is obtained, which is provided, for example, for triggering an output of a switching function or a control function or at least an output perceptible optically, acoustically or tactilely.

[0045] The operating surface 9 is provided by a transparent cover layer 23 of the functional display 1, which covers the display surface 8 of the functional display 1. The functional display 1 is formed partially transparent in order to ensure that the observer or operator can see the operating area located below it, such as the instruments of the instrument panel, through the functional display 1 without hindrance. According to the invention, the functional display 1 also includes a light conductor stack, which is formed by three transparent or translucent planar light conductors 13, 14, 15 arranged in an overlapping manner and each formed of a thermoplastic plastic foil. The light conductors 13, 14, 15 are separated by an air layer 24 arranged between the light conductors 13, 14, 15, respectively, and the air layer thus forms an air gap between two adjacent light conductors of the light conductors 13, 14, 15. This air layer 24 is also arranged between the cover layer 23 and the nearest adjacent light conductor 13.

[0046] The optical waveguides 13, 14, 15 each form at least a main surface H facing the observer B, while the two upper optical waveguides 13, 14 closer to the observer B each have a main surface H' facing away from the observer and facing the next adjacent optical waveguide 14 or 15 in the stacking direction. Each optical waveguide 13, 14, 15 is assigned a light source 12, i.e. a light emitting diode in the form of an SMD design, which is arranged in such a way that the light generated by it enters the assigned optical waveguide 13, 14, 15 via an end surface lateral to the stacking direction. In order to avoid undesired light scattering or light radiation entering the connected optical waveguides 13, 14, 15, a baffle 17 is provided. At the end surfaces 25 lying opposite each other, an anti-reflection coating 25 is applied to the end surfaces of the optical waveguides 13, 14, 15 in order to minimize back reflections in the respective optical waveguide 13, 14, 15. In at least one of the main surfaces of the optical waveguide (here optical waveguides 13, 14), a microstructured symbol area formed by a plurality of microstructures 16 is introduced by embossing, which causes light to emerge from the respective optical waveguide 13, 14 in the direction of an observer B. The microstructures 16 are each formed to be identical in shape and have a diameter in the range of 1 to 25 μm. The optical waveguide 14 and the optical waveguide 15 also have a plurality of microstructures 26.

[0047] The lower light conductor 15 and the middle light conductor 14 facing away from the observer B also have microstructures 26 in their main surface H facing the observer B, which are also unitary and are formed in the same shape as one another. These microstructures are also introduced by embossing or shaping into the relevant main surface H of the respective light conductor 14, 15, here the main surface H facing the observer B. This main surface couples the light incident into the respective light conductor 14, 15 in the direction of a reflector 27, which is arranged on the side of the light conductor stack formed by the light conductors 13, 14, 15 facing away from the observer B, and here in the form of a reverse partially transmissive metal vapor coating on a transparent plastic layer 28, which adjoins the lower light conductor 15 here, but an arrangement spaced apart from the light conductor 15 is also conceivable as an alternative. Only by reflection by the reflector 27 is the light originally incident into the light conductor 14 reflected in the direction of the observer B. Thus, at the observer B, a depth effect or even a three-dimensional impression of the displayed symbol can be achieved by different display planes depending on the activation of the light source 12. In one embodiment, this is achieved, for example, by the simultaneous display of the symbol area display of the lower light conductor 14 of the light conductor stack using a reflector and the same symbol area display of the upper light conductor bypassing the reflector, wherein the parallax shift of the symbol area convinces the binocular observer of the three-dimensional nature of the displayed symbol. By switching between the symbol display of the light conductors 14, 15 of the light conductor stack using a reflector and the symbol display of the light conductors 13, 14 bypassing the reflector, for example in a time sequence in another embodiment, the observer's attention can also be drawn to the functional display 1, which is achieved by changing the display plane of the functional display 1. By selectively activating the light source, different switching states or switch functions can be visualized relatively easily. The functional display 1 can be realized simply and cost-effectively and provides the designer with a lot of design space, which also relates to the placement of the functional display 1. The functional display shows aging phenomena that are almost unaffected by light radiation and is relatively energy-saving. The microstructured symbol area alone or together with other symbol areas reproduces the symbol in positive text as an image, as its reverse representation or as its outline. The depth effect mentioned above can be set, for example, by the distance between the optical waveguides 13, 14, 15, for example the air gap thickness. The distance is, for example, in the range of 1 to 3 mm.

[0048] All light conductors 13, 14, 15 are transparent outside the microstructured areas, so that a large part of the display surface 8 remains transparent and, for example, a see-through through the functional display 1 is ensured, in order to give the observer B the possibility of following other displays or the course of the road through the functional display. As a result, for example, the functional display 1 can be placed on the steering wheel, for example in the area between the steering wheel hub and the steering wheel ring, without affecting the view of the instrument panel. When the display surface 8 is viewed vertically, the microstructured symbol areas of the light conductors 13, 14, 15 overlap at least partially, so that by using light sources 12 with light radiation of different colors, a multi-color symbol can be generated, which can be made visible by completely illuminating a plurality of light conductors 13, 14, 15 at the same time. In order to avoid undesired light propagation in the respective light conductor 13, 14, 15, in particular when exposed to external light, each light conductor 13, 14, 15 has an antireflection coating 33, which is also generally referred to as an antireflection coating or compensation layer, at at least one of the end faces, preferably at the end face not facing the light source 12. The task of the anti-reflection coating is to reduce the amount of light reflected into the light conductor at the coated end face relative to the uncoated end face, for example by absorbing the light in the coating 33. This coating 33 can be applied almost circumferentially. This anti-reflection coating 33 has, for example, an optical refractive index that is numerically between air and the material of the light conductors 13, 14, 15. The ends of the light conductors 13, 14, 15 that are respectively facing away from the light source 12 are each fixed in a materially bonded manner in the frame 25.

[0049] like Figure 3 As shown in FIG. 1 , the invention further relates to a steering wheel 20. The steering wheel 20 has a buffer 22 covering the steering wheel hub, at least one steering wheel spoke 21 and a steering wheel rim 11 carried by the steering wheel spoke 21. The steering wheel 20 according to the invention further has a function display 1, which is a component of an operating element 10 fastened to the steering wheel 20 and is integrated into an operating part 2, which is pivotably supported on a leg of the operating element 10. The leg of the operating element 10 is fixed to the steering wheel rim 11 in a rotationally fixed manner. A substantially transparent display surface 8 of the function display 1 is arranged between the steering wheel rim 11 and the steering wheel hub or a buffer 22 covering the steering wheel hub of the steering wheel 20. When a light source belonging to the function display 1 is selectively activated, different symbols 18 in the area of ​​the display surface 8 become visible to the observer, that is to say the driver, depending on this selection, while due to the transparency of the function display 1 in the remaining area, the instrument panel or its instruments located behind the steering wheel 20 are visible to the driver.

[0050] Figure 4 A cross-section through an assembly according to the invention is shown which is formed by a plurality of functional displays 1, 1', each having, for example, a Figure 1 , 4 5 and are arranged side by side from the perspective of an observer, so as to form display surfaces 8, 8' arranged side by side. The uniqueness of this arrangement is that at least one optical waveguide 13 of a functional display 1 is formed integrally with the optical waveguide 13' of another functional display 1', so as to form a common optical waveguide. The other optical waveguides not shown here and located below are formed with correspondingly the same size. However, the present invention also includes the following embodiments, in which the optical waveguide of each functional display 1, 1' is formed to be different in its external dimensions. In order to minimize the mutual light incidence from one functional display 1 to another functional display 1' and in the reverse direction, a conical interruption 29 is formed in the common optical waveguide 13, 13', and the interruption is filled with a material having a refractive index smaller than the refractive index of the material of the common optical waveguide 13, 13'. Here, some of the end faces of the optical waveguide 13, 13' are provided with an anti-reflection coating 33.

[0051] Figure 5 A cross-section through another assembly according to the invention is shown, which is formed by a plurality of functional displays 1, 1', each of which has, for example, a Figure 1 , 4 or 5 and are arranged side by side with each other from the perspective of an observer so as to form display surfaces 8, 8' arranged side by side with each other. The uniqueness of this arrangement is also that at least one optical waveguide 13 of a functional display 1 is formed integrally with the optical waveguide 13' of another functional display 1' so as to form a common optical waveguide. The other optical waveguides not shown here and located below are formed with correspondingly identical dimensions. However, the present invention should also include the following embodiments, in which the optical waveguide of each functional display 1, 1' is formed to be different in its external dimensions. In order to minimize the mutual incidence of light from one functional display 1 into the other functional display 1' and vice versa, Figure 4 It can be seen that a conical interruption is formed in the common optical waveguide 13, 13', which interruption is filled with a material having a lower refractive index than the material of the common optical waveguide 13, 13'. Figure 5In the embodiment shown in FIG. 1 , this conical interruption is omitted. In the embodiment shown therein, the respective light conductors 13 , 13 ′ form curved interfaces 30 , 32 in the respective light path from the light source 12 , 12 ′ to the associated symbol 18 , 18 ′, respectively, in order to form an optically effective, preferably focusing lens element. For example, in the light conductor 13 , an incident surface 30 which is concave relative to the light conductor is provided in the outer end face of the light conductor 13 , whereas the light conductor 13 ′ has a plurality of interruptions 31 which are filled with a material having a lower refractive index than the material of the common light conductor 13 , 13 ′. The lens element formed by the interruptions 31 also acts in a focusing manner on the light path from the light source 12 ′ to the associated symbol 18 ′. In this case, some of the end faces of the light conductors 13 , 13 ′ are provided with an anti-reflection coating 33 .

Claims

1. A function display (1) for a motor vehicle for selectively displaying symbols (18) representing switch functions and / or switch states, the function display comprising: A light conductor stack, which forms a display surface (8) facing an observer (B) when the functional display (1) is installed as intended; wherein the light conductor stack is formed by at least two transparent or translucent planar light conductors (13, 14, 15) arranged one above the other in the stacking direction, the light conductors being arranged to be separated by a transparent or translucent layer, the layer being formed of a material that is optically thinner than that of adjacent light conductors, so that the light conductors (13, 14, 15) each have a main surface (H) facing the observer (B) and a main surface (H') facing away from the observer (B), and in at least one light conductor (13, 14, 15), the main surface (H') facing away from the observer (B) faces the next adjacent light conductor (13, 14, 15) in the direction opposite to the stacking direction; At least one light source (12, 12') for each optical conductor (13, 14, 15), the light source being arranged so that light (L, L') is incident into the corresponding optical conductor (13, 14, 15) via an end face (S) of the associated optical conductor (13, 14, 15); Each optical waveguide (13, 14, 15) is further provided with at least one microstructured symbol area arranged in or on the optical waveguide (13, 14, 15), the symbol area comprising a plurality of light-refracting and / or light-scattering microstructures (16, 26) and being formed to be luminously visible to the observer (B) by means of light incident into the optical waveguide (13, 14, 15) when the light source (12, 12') is activated, so as to display a symbol (18) composed of one or more microstructured symbol areas to the observer (B); A reflector (27) is arranged on the side of the optical waveguide stack facing away from the observer (B) in order to reflect light (L') incident on at least one of the optical waveguides (13, 14, 15) and subsequently emerging from the optical waveguide (13, 14, 15) by means of an associated microstructure (26) in the direction of the observer (B).

2. The functional display (1) according to claim 1, wherein the microstructure (16) of at least one microstructured light guide (13, 14, 15) is formed in such a way that light (L) incident on the respective light guide (13, 14, 15) emerges in the direction of the observer (B).

3. The functional display (1) according to any one of the preceding claims, wherein the microstructured symbol regions each comprise a plurality of microstructures (16, 26) formed in the same shape as one another.

4. The functional display (1) according to claim 1, wherein: For all microstructured symbol areas of the optical waveguide (13, 14, 15), the average number density of the microstructures (16, 26) is between 1000 and 4000 per mm 2 within the range. 5 . The functional display ( 1 ) according to claim 1 , wherein the microstructures ( 16 , 26 ) of all microstructured symbol regions each have a maximum diameter in the range of 1 to 25 μm. 6 . The functional display ( 1 ) according to claim 1 , wherein the microstructure ( 16 , 26 ) is formed by embossing one of the main surfaces (H, H′) of each light guide body ( 13 , 14 , 15 ).

7. The functional display (1) according to claim 1, wherein the area ratio of all microstructured symbol areas occupies less than half of the display area (8). 8 . The functional display ( 1 ) according to claim 1 , wherein the microstructured symbol areas of at least two light conductors ( 13 , 14 , 15 ) of the light conductor stack are arranged non-overlappingly for the observer (B) when viewing the display area ( 8 ) vertically.

9. The functional display (1) according to claim 1, wherein the microstructured symbol regions of at least two light conductors (13, 14, 15) of the light conductor stack are arranged adjacent to or overlapping each other for the observer (B) when viewing the display area (8) perpendicularly.

10. The functional display (1) according to claim 1, wherein at least two light sources (12) differ in light color. 11 . The functional display ( 1 ) according to claim 1 , wherein the light guide bodies ( 13 , 14 , 15 ) each comprise a foil or are formed from a foil.

12. The functional display (1) according to claim 1, wherein a lens and / or a baffle (17) and / or a light channel is arranged between the light conductor (13, 14, 15) and the light source (12).

13. The functional display (1) according to claim 1, wherein at least one of the optical waveguides (13) of the optical waveguide stack has at least one curved interface (32, 30) in the corresponding light path from the light source (12) to the associated microstructured symbol area in order to form at least one focusing lens element.

14. The functional display (1) according to claim 1, wherein the transparent or semi-transparent layer is an air gap.

15. An assembly consisting of a plurality of functional displays (1, 1'), each of which is formed according to one of the preceding claims and forms a plurality of display surfaces (8, 8') arranged next to one another from the perspective of the observer (B), and wherein at least a cover layer (23) and / or at least one optical waveguide (13, 13') are formed in one piece.

16. An operating element (10) having a functional display (1) according to any one of claims 1 to 14.

17. An operating element (10) according to claim 16, wherein the display surface (8) is formed as a translucent and / or transparent part of an operating surface (9) of the operating element (10) intended for contacting or actuating an operating part (2) or the display surface is arranged below a translucent and / or transparent covering layer forming the operating surface (9).

18. A steering wheel (20) for a motor vehicle having a functional display (1) according to any of the preceding claims 1 to 14.

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