CN115503473B

CN115503473B - Function displays and associated operating elements with selectively displayed symbols

Info

Publication number: CN115503473B
Application number: CN202210550286.5A
Authority: CN
Inventors: A·克劳姆利希; M·卢斯特
Original assignee: Preh GmbH
Current assignee: Preh GmbH
Priority date: 2021-06-07
Filing date: 2022-05-20
Publication date: 2025-02-21
Anticipated expiration: 2042-05-20
Also published as: CN115503473A; DE102021114524B3

Abstract

The invention relates to a functional display having a light conductor stack forming a display surface facing a viewer, the light conductor stack being formed by at least two transparent or translucent planar light conductors arranged one above the other in the stack direction, the light conductors being arranged as transparent or translucent layers, the layers being formed of a material which is optically thinner than adjacent light conductors, at least one light source of each light conductor being arranged such that light is incident into the respective light conductor via an end face of the associated light conductor, wherein each light conductor is further provided with at least one microstructured symbol region arranged in or on the light conductor, comprising a plurality of microstructures and being formed such that, upon activation of the light source, illumination of the light incident into the light conductor is visible to the viewer, and a mirror arranged on a side of the light conductor stack facing away from the viewer in order to reflect the light incident into the at least one light conductor and subsequently emitted from the light conductor towards the viewer.

Description

Functional display for selectively displaying symbols and associated operating element

Technical Field

The invention relates to a functional display for selectively displaying at least one symbol representing a switching function and/or a plurality of switching states.

Background

These functional displays are necessary, for example, for multifunctional operating elements in order to visualize the switching functions and/or the switching states associated with the operating elements. For this purpose, electronic pixel matrix displays are generally used. However, they are relatively expensive, limiting their design and placement due to the rectangular shape in most cases. Furthermore, electronic pixel matrix displays often tend to "burn in" when displaying static display content, that is, the display content undesirably remains continuously visible even with the display turned off due to visually perceived damage to the imaging layer of the display. In addition, the power consumption of such electronic pixel matrix displays is relatively high. In addition, in some applications, the use of conventional electronic pixel matrix displays is prohibited due to the risk of injury, for example in the event of a head collision. As an alternative to pixel matrix displays, it is known for light from a light source that is incident on an end face of a light guide to be emitted in a targeted manner by means of a surface structure at a main face serving as a display face, wherein only the areas provided with the surface structure are provided locally and symbols or the like are reproduced. Disadvantageously, the symbols are in most cases visually unobtrusive and thus may be easily ignored by the observer. This results in the observer, in particular the driver of the vehicle, for example, erroneously estimating the actual switching state.

Disclosure of Invention

Against this background, the object of the present invention is to provide a functional display which creates the possibility of increasing the display richness and thus the attention of the observer, in particular by means of an additional display plane, a depth effect and furthermore can be produced cost-effectively, which is energy-efficient and reliable and/or reduces the risk of injury in particular in the event of a head impact. It is to be noted that the features specified individually in the claims can be combined with one another in any technically meaningful way and exhibit further embodiments of the invention. The description additionally characterizes and specifies the invention in particular in connection with the accompanying drawings.

The invention relates to a functional display, in particular for a motor vehicle, for selectively displaying at least one symbol representing a switching function and/or a plurality of switching states. The selective display is understood not only to mean that different symbols are selectively displayed 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 switching them on, but also to mean that the light sources are switched to visually present the symbol to the observer by means of activated backlighting or to make the symbol disappear as close as possible to the observer by switching off the backlighting.

The functional display according to the invention has a light conductor stack which forms a display surface facing the viewer when the functional display is mounted as intended. The light conductor stack is formed by at least two transparent or translucent planar light conductors arranged one above the other in the stack direction, which light conductors are arranged as transparent or translucent layers, preferably separated by an air gap, which layers are formed of a material which is optically thinner than the adjacent light conductors. The light conductors here each have a principal face facing the observer and a principal face facing away from the observer. At least one light conductor, the main face facing away from the observer faces the next adjacent light conductor in the stacking direction.

The functional display according to the invention may optionally have an external transparent or translucent cover layer arranged between the light conductor stack and the observer, by means of which cover layer the display surface defined by the light conductor stack is visible to the observer in the case of the intended arrangement of the functional display. The material of the cover layer and the light conductor is, for example, plastic, preferably thermoplastic, such as Polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinylchloride (PVC), polyamide (PA), acrylonitrile Butadiene Styrene (ABS) or polymethyl methacrylate (PMMA), or a glass material.

According to the invention, each light conductor is provided with at least one light source arranged to cause light to be incident into the respective light conductor via the end face of the associated light conductor. The light guide has, for example, two main faces which face one another and preferably extend parallel to one another, which are connected via end faces, for example, at the narrow sides and at the long sides of the light guide, which end faces form a common edge with the main faces of the light guide. The end face is, for example, orthogonal to at least one main face or both main faces of the photoconductor.

The light source is, for example, a light-emitting diode, in particular in the form of an SMD design. In order to improve the light incidence and/or to adapt the light radiation characteristics of the light source to the end face determined for the light to enter the light guide, lenses and/or baffles and/or light channels are preferably arranged between the light guide and the light source, respectively. The baffles or light channels are also formed, for example, to inhibit light from escaping to the viewer, other layers or light conductors than the assigned light conductor.

According to the invention, each light conductor is further provided with a microstructured symbol area provided in or on the light conductor, the symbol area comprising a plurality of light-refracting and/or light-scattering microstructures. The microstructured symbol areas form, alone or together with other microstructured symbol areas of the same or a further light conductor, symbols which become visible to an observer upon activation of the light source by means of light incident into the respective light conductor due to refraction and/or scattering of light generated by the plurality of microstructures at the respective microstructured surface. An angle of incidence of the light onto the relevant main face, which does not fulfil the condition of total reflection of the main face of the light guide as an interface, is achieved, for example, by a microstructure, such that the light incident into the light guide leaves the light guide again.

According to the invention, a preferably partially transmissive (that is to say partially transparent) mirror is provided, which is arranged on the side of the light conductor stack facing away from the observer and is formed to reflect light, which is incident into at least one of the light conductors and is subsequently emitted from the light conductor by means of the associated microstructure, in the direction of the observer. The mirror 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.

The depth effect of the display device can thus be achieved relatively simply and cost-effectively in that the mirror is provided with a further display plane which is offset back for the observer relative to the light conductors of the light conductor stack, which display plane is located, for example, in the virtual image plane of the mirror. This depth effect cannot be achieved by using the light guide stack alone and provides additional optical attraction at the viewer.

The microstructure of the at least one microstructured light conductor is preferably formed such that light incident into the respective light conductor emerges in the direction of the observer, that is to say with bypassing the mirror. Thereby, at the observer, depending on the activation of the light source, a depth effect or even a stereoscopic impression of the displayed symbol can be achieved by different display planes. This is for example achieved by simultaneous display of a symbol area display with a mirror and of the same symbol area display of the same or another photoconductor by-passing the mirror, wherein a parallax offset of the symbol areas implies to a binocular observer the three-dimensional nature of the displayed symbol. In a further embodiment, the viewer's attention can also be drawn to the functional display by switching, for example in time sequence, between the display of the symbol using the mirror and the display of the symbol of the other light conductor of the light conductor stack, which bypasses the mirror, by changing the display plane of the functional display. By selectively activating the light sources, different on-states or switching functions can be visualized relatively simply. The functional display can be realized simply and cost-effectively and gives the designer a great design space, which also relates to the way the functional display is placed. Functional displays exhibit aging phenomena that are hardly affected by light radiation and are relatively energy efficient. The microstructured is for example to reproduce the symbol in a positive manner as an image, as an inverse representation thereof or as a contour thereof. The previously mentioned depth effect may be set, for example, by the distance between the light conductors, for example the air gap thickness. Said distance is for example in the range of 1 to 3 mm.

The microstructured symbol regions can be introduced into the light guide by laser ablation, for example by means of a three-dimensional drawing of glass (Vitrographie, also referred to as laser internal engraving) applied in three dimensions or on one of its main faces. The microstructured symbol regions are preferably formed by embossing one of the main faces of each light conductor, so that a functional display can be realized at low cost.

The microstructured symbol region is preferably formed by a plurality of identically shaped microstructures, which together define a continuous microstructured symbol region of each light guide. The microstructure is preferably understood as a single protrusion on the main surface or a single depression in the main surface. In order to exclude substantially naked eye visibility, the maximum dimension of each microstructure is here, for example, in the range of 1 to 50 μm, preferably in the range of 1 to 25 μm. The microstructures are preferably arranged in a uniformly spaced apart manner over the entire microstructured symbol region of the main surface. The microstructure is formed, for example, in a pyramid shape or a prism shape. The microstructures are preferably not only identically shaped, i.e. uniformly shaped, but also have a uniform orientation within the corresponding microstructured symbol regions. For example, a uniform orientation on a planar main surface can only be produced if each microstructure can be mapped by an imaginary, translational-only offset onto an adjacent microstructure of the same microstructured symbol region. The microstructure is more preferably formed such that it produces a collimated light beam formed by light exiting from the light guide, the light beam originating from the light source and having previously entered the light guide via the end face.

The average number density of the microstructures of each microstructured symbol region of the light conductor stack is preferably in the range of between 500 and 7000 per mm ², more preferably in the range of between 1000 and 4000 per mm ². In this way, on the one hand, the non-visibility is ensured in the case of the light source being switched off, while in the case of the light source being activated, the impression of a uniformly illuminated symbol area can be simulated for the "bare" eye. The average number density of each photoconductor is preferably chosen to be substantially the same, wherein "substantially the same" is understood to be a maximum deviation of less than 100 per mm ² between the number densities of the photoconductor.

Preferably, at least two directly adjacent light conductors are provided, the microstructures of which are arranged only on the main faces facing away from each other.

All light conductors outside the microstructured region are transparent and the mirror is partially transmissive, so that a large part of the functional display remains at least partially transparent and for example a perspective through the functional display is ensured, in order to give the observer the possibility to track the course of other displays, meters or roads through the functional display. Thus, for example, the functional display can be arranged at the steering wheel, for example in the region between the steering wheel hub and the steering wheel rim, without affecting the view of the dashboard. The area proportion of all the surface-structured symbol regions on the display surface is preferably less than half.

The respective optical conductor need not necessarily be formed in one piece, and can be composed of a plurality of components. In one embodiment, the light conductors each have at least one foil, for example a multi-layered foil structure. The photoconductor is produced, for example, by back-molding a transparent foil, such as a PC foil or a PE foil, with a first material, in particular a thermoplastic.

According to a preferred embodiment, it is provided that the microstructured symbol regions of at least two light conductors of the light conductor stack are arranged to the observer in a non-overlapping, preferably spaced apart, manner when the display surface is viewed perpendicularly, in particular from a position above the geometric center point of the display surface.

According to a preferred embodiment, it is provided that the microstructured symbol regions of the at least two light conductors of the light conductor stack are arranged adjacent to one another, preferably overlapping, more preferably completely overlapping, for the observer, when the display surface is viewed perpendicularly, in particular from a position above the geometric center point of the display surface.

In order to provide an additional color effect, according to a preferred embodiment, at least two light sources differ from each other in terms of the color of the light.

It is preferably provided that the light conductors each have at least one curved interface in the respective light path from the light source to the associated symbol region, in order to form at least one focusing lens element. The light guide body forms, for example, a curved light incident surface provided for the light of the light source at an end surface thereof. In a further embodiment, the light guide has one or more interruptions, each having an interface that acts as a light exit surface and a light entrance surface, wherein at least one interruption is curved in an optically focusing manner, preferably both interruptions are curved in an optically focusing manner.

In order to avoid undesired light propagation in the respective light conductor, in particular when extraneous light is acting, according to a preferred embodiment the respective light conductor has an antireflection coating, which is often also referred to as an antireflection coating or compensation layer, at least one of the end faces, preferably at the end face opposite to the end face facing the light source. The task of the anti-reflection coating is to reduce the amount of light reflected into the optical conductor at the coated end face relative to the uncoated end face, for example by absorbing light in the coating. For example, the antireflection coating may be applied circumferentially, 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 guide or shielding layer.

The invention also relates to an assembly formed by a plurality of functional displays, each of which is formed in one of the previously described embodiments. The assembly is unique in that a plurality of display surfaces are arranged side by side with respect to each other from the perspective of a viewer. In the assembly, at least the cover layer and/or at least one light conductor are integrally formed, for example, to form a common cover layer or a common light conductor. In order to still suppress crosstalk of light from the light conductor of one functional display into the light conductors of the other functional displays of the assembly in the case of integration, for example, interruptions are provided which are filled with a material (for example air) which is optically thinner with respect to the material of the light conductor.

The invention also relates to an operating element having a functional display formed in one of the embodiments described above. The actuating element has, for example, a leg for fastening the actuating element to a vehicle component, such as a dashboard, a lining of a passenger compartment or, in particular, to a steering wheel of a motor vehicle. The actuating element according to the invention also has, for example, an actuating element defining an actuating surface, which is formed as at least one self-supporting lever arm. The self-supporting lever arm is supported on one side on the leg, for example, by means of a solid hinge, in order to be able to pivot the operating element relative to the leg about an imaginary pivot axis against a restoring force under the action of an operating force acting perpendicular to the operating face. Means are also provided, for example, to detect the degree of pivoting between the operating member and the leg. The area of the member that allows pivoting between two rigid body areas by bending is generally referred to as a solid hinge. By means of the solid hinge, a play-free and thus rattling-free support of the operating element at the leg is achieved. The legs and the operating member are formed, for example, from a thermoplastic such as Polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinylchloride (PVC), polyamide (PA), acrylonitrile Butadiene Styrene (ABS) or polymethyl methacrylate (PMMA). The actuating element according to the invention is particularly suitable for a design in which the maximum pivoting degree about the imaginary pivot axis from the unactuated rest position to the actuated maximum pivot position is less than 10 °, preferably less than 5 °.

The display surface is preferably a translucent or transparent region of the operating surface of the operating element which is defined as the operating element for contact or actuation.

The invention also relates to a steering wheel, for example having a steering wheel hub, at least one steering wheel spoke and a steering wheel ring carried by the steering wheel spoke. The steering wheel according to the invention also has a functional display formed in one of the previously described embodiments. The functional display is preferably an integral part of an operating element fastened to the steering wheel. The leg of the operating element is fixed, for example, in a rotationally fixed manner to the steering wheel rim. The display surface of the functional 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.

Drawings

The invention and its technical environment are explained in detail below with the aid of the figures. It is noted that the figures show particularly preferred implementation variants of the invention, to which, however, the invention is not limited. The drawings schematically show:

fig. 1 is a schematic cross-sectional view of a first embodiment of the invention of a functional display 1;

fig. 2 is a schematic cross-sectional view of an embodiment of the invention of an operating element 10 with a functional display;

fig. 3 shows a top view of a steering wheel according to the invention with an operating element 10 comprising a functional display 1;

Fig. 4 is a horizontal cross-section of the assembly of the invention formed by two functional displays 1, 1';

fig. 5 is a horizontal sectional view of another inventive assembly formed by two functional displays 1, 1'.

Detailed Description

Fig. 1 schematically shows a first embodiment of a functional display 1 according to the invention. The functional display 1 comprises an external transparent or translucent, but at the same time not mandatory and only optionally provided, cover layer 23 which defines a surface facing the viewer B in the intended arrangement of the functional display 1. The cover layer is, for example, a layer formed from plastic, preferably thermoplastic, such as Polyethylene (PE), polycarbonate (PC), polystyrene (PS), polyvinylchloride (PVC), polyamide (PA), acrylonitrile Butadiene Styrene (ABS) or polymethyl methacrylate (PMMA), or from a glass material. The cover layer 23 may also be part of a layer construction formed of a plurality of layers.

According to the invention, the functional display 1 also comprises, in a mandatory manner, a light conductor stack formed by at least two transparent or translucent planar light conductors 13, 14 arranged one above the other and formed by thermoplastic layers or thermoplastic foils, respectively. 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 of a material (here air) having a refractive index lower than the refractive index of the adjacent light conductors 13, 14. This air layer 24 is likewise arranged between the cover layer 23 and the nearest neighboring light conductor 13. The light conductors 13, 14 form at least a main face H facing the observer B and a main face H 'facing away from the observer B, respectively, whereas the upper light conductor 13 closer to the observer B has a main face H' facing away from the observer, facing the next adjacent light conductor 14 in the stacking direction.

The light conductors 13, 14 are each assigned a light source 12, i.e. a light-emitting diode in the form of an SMD design, which is arranged such that light generated by the light source is incident into the assigned light conductor 13, 14 via an end face S that is lateral to the stacking direction. In order to avoid unwanted light scattering or light radiation into the adjacent light conductors 13, 14, respectively, a baffle 17 is provided. At the end faces opposite to each other, an anti-reflection coating 33 is applied on the end faces of the light conductors 13, 14 in order to minimize back reflections in the respective light conductors 13, 14, while the light conductors 13, 14 are positively fixed in the frame 25. In at least one main face of the light guide 13, a plurality of individual microstructures 16 are introduced in the main face H' facing away from the observer by embossing or shaping, which are responsible for emitting the light L incident into the light guide 13 from the respective light guide 13 in the direction of the observer B by light refraction and/or light scattering, and define microstructured symbol regions comprising the microstructures 16. This symbol region, alone or in optical cooperation with other symbol regions, again generates the shape of a symbol that is visible to the observer B in the form of luminescence in the event that the associated light source 12 is correspondingly activated.

The microstructures 16 are formed to be identical in shape to each other and have a maximum diameter in the range of 1 to 25 μm. The light conductors 14 facing away from the observer B likewise have microstructures 26 in their main face H facing the observer B, which are likewise unitary and are formed identically to one another. These microstructures are also introduced into the relevant main face of the light guide 14, here the main face H facing the viewer B, by embossing or shaping. These light L' incident into the light guide 14 are coupled in the direction of a mirror 27, which is arranged on the side of the light guide stack formed by the light guides 13, 14 facing away from the observer B, in this case 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 light guide 14 by means of an air gap 24, but an arrangement adjoining the light guide 14 is also conceivable instead.

Only the light L' originally incident into the light guide 14 is reflected in the direction of the observer B by reflection of the mirror 27. Thus, at the observer B, depending on the activation of the light source 12, a depth effect or even a stereoscopic impression of the displayed symbol can be achieved by different display planes. In one embodiment, this is achieved, for example, by simultaneous display of the symbol region display of the lower light conductor 14 of the light conductor stack using a mirror and the same symbol region display of the upper light conductor bypassing the mirror, wherein the parallax offset of the symbol regions creates an illusion of the three-dimensional nature of the displayed symbol for a binocular observer.

In a further embodiment, the viewer's attention can also be drawn to the functional display 1 by switching, for example in time sequence, between the display of the symbol of the lower light conductor 14 of the light conductor stack using the mirror and the display of the symbol of the upper light conductor 13 bypassing the mirror, by changing the display plane of the functional display 1. By selectively activating the light sources, different on-states or switching functions can be visualized relatively simply. The functional display 1 can be realized simply and cost-effectively and gives the designer a great deal of design space, which also relates to the way the functional display 1 is placed. Functional displays exhibit aging phenomena that are hardly affected by light radiation and are relatively energy efficient. The microstructured symbol regions reproduce the symbols, for example, alone or together with other symbol regions, in a yankee manner as images, as their inverse representations or as their contours. The previously mentioned depth effect may be set by, for example, the distance between the light conductors 13, 14, for example the air gap thickness. Said distance is for example in the range of 1 to 3 mm.

All the light conductors 13, 14 are transparent outside the microstructured region. Since the mirror 17 is also provided with a partial light transmission, a large part of the display surface 8 is optically transmissive, so that, for example, a perspective through the functional display is ensured, in order to give the observer B the possibility of tracking other displays or the course of the road through the functional display. Thereby, the functional display 1 can be placed, for example, at the steering wheel, for example in the region between the steering wheel hub and the steering wheel rim, without affecting the view of the dashboard. When viewing the display surface 8 perpendicular to the microstructured areas of all light conductors 13, 14, the projected microstructured symbol areas of the respective light conductors 13, 14 do not overlap, so as not to affect the display quality of the symbol.

Fig. 2 shows an embodiment of the operating element 1 according to the invention. This operating element has a leg 3 for fastening the operating element 1 to a vehicle component, such as a dashboard, a lining of a passenger compartment or, in particular, to a steering wheel rim 11 of a steering wheel of a motor vehicle. The operating element 10 according to the invention also has an operating part 2 defining an operating surface 9, which is formed as at least one self-supporting lever arm. The self-supporting lever arms are each supported on one side by means of a solid hinge 4 on the leg 3 in order to be able to pivot the operating part 2 relative to the leg 3 about an imaginary pivot axis a against a restoring force under the action of an actuating force acting perpendicular to the operating face 9. The restoring force is generated, for example, by deformation of the solid hinge 4.

Means 6 are also provided according to the invention in order to detect the degree of pivoting between the operating member 2 and the leg 3. The solid hinge 4 is formed only by an integral connection between the leg 3 and the operating part 2. The actuating element 1 according to the invention is particularly suitable for a design in which, starting from the unactuated rest position shown in fig. 2, the maximum pivot angle about the imaginary pivot axis a to the maximum possible actuated pivot position is less than 10 °, preferably less than 5 °.

According to the invention, an actuator 5 is also provided which can be acted upon by a steering electronic device, not shown, with a steering electrical signal in order to produce active haptic feedback (also referred to as a haptic perceptible output), wherein the actuator 5 is preferably fastened only to the operating element 2. The Actuator 5 is preferably an inertial-based, motor-based Actuator, such as a motor or a magnet Coil Actuator or a piezoelectric Actuator or a linear broadband Actuator such as a plunger Coil Actuator or a linear resonant Actuator, to the drive shaft of which the rotation is fixed a mass body eccentrically mounted with respect to its center of gravity. The actuator 5 is preferably fixed to the operating part 2 by a force-fit or material-fit connection, for example by screwing or gluing. Since it is only fixed at the operating part 2, the structural noise is prevented from being input into the steering wheel rim 11 and thus into the vehicle part, or at least minimized.

The means 6 for detecting the degree of pivoting are formed to detect the degree of pivoting between the leg 3 and the operating member 2 capacitively, optically and/or inductively. Thanks to the cooperation of the play-free support of the operating element 2 by the solid hinge 4 with the means 6 for preferably contactless detection of the degree of pivoting, a low to no hysteresis detection of an actuation force is obtained, which is provided, for example, as an output for triggering a switching function or a control function or at least an optically, acoustically or tactilely perceptible output.

The operating surface 9 is provided by a transparent cover layer 23 of the functional display 1, which cover layer covers the display surface 8 of the functional display 1. The functional display 1 is formed to be partially transparent in order to ensure that an observer or operator is unhindered to view the instrument located in the operating area underneath, such as the instrument panel, through the functional display 1. According to the invention, the functional display 1 further comprises a light conductor stack formed by three transparent or translucent planar light conductors 13, 14, 15, each formed by a thermoplastic foil, arranged one above the other. The light conductors 13, 14, 15 are separated by an air layer 24 provided between the light conductors 13, 14, 15, respectively, which air layer thus forms an air gap between two adjacent ones of the light conductors 13, 14, 15, respectively. This air layer 24 is likewise arranged between the cover layer 23 and the nearest neighboring light conductor 13.

The light conductors 13, 14, 15 each form at least a main face H facing the observer B, while the two light conductors 13, 14 in the upper part, which are closer to the observer B, each have a main face H' facing away from the observer, facing the next adjacent light conductor 14 or 15 in the stacking direction. The light conductors 13, 14, 15 are each assigned a light source 12, i.e. a light-emitting diode in the form of an SMD design, which is arranged such that light generated by the light source is incident into the assigned light conductor 13, 14, 15 via an end face that is lateral to the stacking direction. In order to avoid unwanted light scattering or light radiation into the connected light conductors 13, 14, 15, respectively, a baffle 17 is provided. At the end faces 25 opposite each other, an anti-reflection coating 25 is applied on the end faces of the light conductors 13, 14, 15 in order to minimize back reflections in the respective light conductors 13, 14, 15. In at least one of the main faces of the light conductors (here, light conductors 13, 14), microstructured symbol regions formed by a plurality of microstructures 16 are introduced by embossing, which causes light to emerge from the respective light conductor 13, 14 in the direction of the observer B. The microstructures 16 are formed to be identical in shape and have a diameter in the range of 1 to 25 μm, respectively. The light conductor 14 and the light conductor 15 also have a plurality of microstructures 26.

The lower light conductor 15 and the middle light conductor 14 facing away from the observer B likewise have microstructures 26 in their main faces H facing the observer B, which are likewise unitary and are formed identically to one another. These microstructures are also introduced into the relevant main face, here the main face H facing the viewer B, of the respective light conductor 14, 15 by embossing or shaping. This primary face couples light incident into the respective light conductor 14, 15 in the direction of a mirror 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, which mirror here takes the form of a metal vapor coating which is transmitted in the reverse section on the transparent plastic layer 28, which mirror here adjoins the lower light conductor 15, but an arrangement spaced apart from the light conductor 15 is also conceivable instead. Only the light originally incident into the light guide 14 is reflected in the direction of the observer B by reflection by the reflecting mirror 27. Thus, at the observer B, depending on the activation of the light source 12, a depth effect or even a stereoscopic impression of the displayed symbol can be achieved by different display planes. In one embodiment, this is achieved, for example, by simultaneous display of the symbol region display of the lower light conductor 14 of the light conductor stack using a mirror and the same symbol region display of the upper light conductor bypassing the mirror, wherein the parallax offset of the symbol regions causes the binocular observer to believe the three-dimensional nature of the displayed symbol. In a further embodiment, the viewer's attention can also be drawn to the functional display 1 by switching, for example in time sequence, between the display of the light conductors 14, 15 of the light conductor stack with the mirror and the display of the light conductors 13, 14 bypassing the mirror, by changing the display plane of the functional display 1. By selectively activating the light sources, different on-states or switching functions can be visualized relatively simply. The functional display 1 can be realized simply and cost-effectively and gives the designer a great deal of design space, which also relates to the way the functional display 1 is placed. Functional displays exhibit aging phenomena that are hardly affected by light radiation and are relatively energy efficient. The microstructured symbol regions reproduce the symbols, for example, alone or together with other symbol regions, in a yankee manner as images, as their inverse representations or as their contours. The previously mentioned depth effect may be set by, for example, the distance between the light conductors 13, 14, 15, for example the air gap thickness. Said distance is for example in the range of 1 to 3 mm.

All light conductors 13, 14, 15 are transparent outside the microstructured region, so that a large part of display surface 8 remains transparent and for example a perspective through functional display 1 is ensured, in order to give observer B the possibility to track the course of other displays or roads through the functional display. Thereby, the functional display 1 can be placed, for example, at the steering wheel, for example in the region between the steering wheel hub and the steering wheel rim, without affecting the view of the dashboard. When the display surface 8 is viewed vertically, the microstructured symbol areas of the light conductors 13, 14, 15 overlap at least partially in order to produce symbols of a plurality of colors by using light sources 12 with different color light radiation, which symbols can be made visible by simultaneously illuminating a plurality of light conductors 13, 14, 15 completely. In order to avoid unwanted light propagation in the respective light conductors 13, 14, 15, in particular when extraneous light is acting, each light conductor 13, 14, 15 has an anti-reflection coating 33, which is often also referred to as an anti-reflection coating or compensation layer, 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 light in the coating 33. This coating 33 may be applied near circumferentially. This anti-reflection coating 33 has, for example, an optical refractive index which is numerically between that of air and the material of the light conductors 13, 14, 15. The ends of the light conductors 13, 14, 15, respectively, facing away from the light source 12, are each fixed in a material-fitting manner in a frame 25.

As shown in fig. 3, the present invention also relates to a steering wheel 20. The steering wheel 20 has a bumper 22 covering the steering wheel hub, at least one steering wheel spoke 21 and a steering wheel rim 11 carried by said steering wheel spoke 21. The steering wheel 20 according to the invention also has a functional display 1 which is part of an actuating element 10 fastened to the steering wheel 20 and is integrated into an actuating element 2 which is mounted in a pivotable manner on a leg of the actuating element 10. The leg of the actuating element 10 is fixed in a rotationally fixed manner to the steering wheel 11. The substantially transparent display surface 8 of the functional display 1 is arranged between the steering wheel rim 11 and a steering wheel hub or a bumper 22 of the steering wheel 20 covering the steering wheel hub. Upon selective activation of the light sources belonging to the functional display 1, the different symbols 18 in the region of the display surface 8 become visible to the observer (that is to say the driver) as a result of this selection, while the instrument panel or the instrument thereof located behind the steering wheel 20 is visible to the driver due to the transparency of the functional display 1 in the remaining region.

Fig. 4 shows a sectional view through an inventive assembly formed by a plurality of functional displays 1, 1', which have, for example, the sectional configuration as shown in fig. 1, 4 or 5, respectively, and are arranged next to one another from the perspective of the observer, in order to thereby form display surfaces 8, 8' arranged next to one another. This arrangement is distinguished in that at least one light conductor 13 of one functional display 1 is integrally formed with a light conductor 13 'of the other functional display 1' so as to form a common light conductor. Other light conductors not shown here and located thereunder are formed in correspondingly identical dimensions. But according to the invention it should also comprise embodiments in which the light guide formation of each functional display 1, 1' differs in its outer dimensions. In order to minimize mutual light incidence from one functional display 1 into the other functional display 1' and vice versa, a conical discontinuity 29 is formed in the common light conductors 13, 13', which discontinuity is filled with a material having a refractive index smaller than the refractive index of the material of the common light conductors 13, 13 '. Here, some of the end faces of the light conductors 13, 13' are provided with an anti-reflection coating 33.

Fig. 5 shows a sectional view through a further component of the invention formed by a plurality of functional displays 1, 1', which have, for example, the sectional configuration shown in fig. 1,4 or 5, respectively, and are arranged next to one another from the perspective of the observer, in order to thereby form display surfaces 8, 8' arranged next to one another. This arrangement is also distinguished in that at least one light conductor 13 of one functional display 1 is integrally formed with a light conductor 13 'of the other functional display 1' in order to form a common light conductor. Other light conductors not shown here and located thereunder are formed in correspondingly identical dimensions. But according to the invention it should also comprise embodiments in which the light guide formation of each functional display 1, 1' differs in its outer dimensions. In order to minimize mutual light incidence from one functional display 1 into the other functional display 1' and vice versa, it is known from fig. 4 that in the common light conductors 13, 13' a conical interruption is formed, which interruption is filled with a material having a refractive index smaller than the refractive index of the material of the common light conductors 13, 13 '. This conical interruption is omitted in the embodiment shown in fig. 5. In the embodiment shown therein, the respective light conductors 13, 13' form curved interfaces 30, 32 in the respective light path from the light sources 12, 12' to the respective symbol 18, 18', respectively, in order to form optically effective, preferably focusing, lens elements. For example, in the optical conductor 13, an incident surface 30 concave with respect to the optical conductor is provided in an outer end surface of the optical conductor 13, whereas the optical conductor 13 'has a plurality of interruption portions 31 filled with a material having a refractive index smaller than that of the materials of the common optical conductors 13, 13'. The lens element formed by the interruption 31 likewise acts in a focused manner on the light path from the light source 12 'to the associated symbol 18'. Here, some of the end faces of the light conductors 13, 13' are provided with an anti-reflection coating 33.

Claims

1. A functional display (1) for a motor vehicle for selectively displaying symbols (18) representing a switching function and/or a switching state, the functional display having:

A light conductor stack forming a display surface (8) facing the viewer (B) in the intended mounting of the functional display (1), wherein the light conductor stack is formed of at least two transparent or translucent planar light conductors (13, 14, 15) arranged one above the other in the stacking direction, which light conductors are arranged to be separated by a layer of a layer which is formed of a material which is optically thinner than an adjacent light conductor, such that the light conductors (13, 14, 15) each have a main surface (H) facing the viewer (B) and a main surface (H ') facing away from the viewer (B) and the main surface (H') facing away from the viewer (B) in at least one light conductor (13, 14, 15) faces the next adjacent light conductor (13, 14, 15) in the opposite direction to the stacking direction;

At least one light source (12, 12 ') of each light conductor (13, 14, 15), said light source being arranged to cause light (L, L') to be incident into the respective light conductor (13, 14, 15) via an end face (S) of the associated light conductor (13, 14, 15);

Wherein each photoconductor (13, 14, 15) is further provided with at least one microstructured symbol region provided in or on the photoconductor (13, 14, 15), the symbol region comprising a plurality of light-refracting and/or light-scattering microstructures (16, 26) and being formed so as to be visible to the observer (B) by means of light incident into the photoconductor (13, 14, 15), respectively, upon activation of a light source (12, 12'), so as to display for the observer (B) a symbol (18) composed of one or more microstructured symbol regions;

A mirror (27) is arranged on the side of the light conductor stack facing away from the observer (B) in order to reflect light (L') incident into at least one of the light conductors (13, 14, 15) and subsequently exiting the light conductors (13, 14, 15) by means of an associated microstructure (26) in the direction of the observer (B).

2. Functional display (1) according to claim 1, wherein the microstructures (16) of at least one microstructured light guide (13, 14, 15) are formed such that light (L) incident into the respective light guide (13, 14, 15) is emitted in the direction of the observer (B).

3. Functional display (1) according to any of the preceding claims, wherein the microstructured symbol areas each comprise a plurality of microstructures (16, 26) formed in the same shape as each other.

4. Functional display (1) according to claim 1, wherein the average number density of the microstructures (16, 26) is in the range of 1000 to 4000 per mm ² for all microstructured symbol areas of the light guide (13, 14, 15).

5. Functional display (1) according to claim 1, wherein the microstructures (16, 26) of all microstructured symbol areas each have a maximum diameter in the range of 1 to 25 μm.

6. Functional display (1) according to claim 1, wherein the microstructures (16, 26) are formed by embossing one of the main faces (H, H') of each photoconductor (13, 14, 15).

7. Functional display (1) according to claim 1, wherein the area proportion of all microstructured symbol areas is less than half of the display surface (8).

8. Functional display (1) according to claim 1, wherein microstructured symbol areas of at least two light conductors (13, 14, 15) of the light conductor stack are arranged non-overlapping for the viewer (B) when the display surface (8) is viewed vertically.

9. Functional display (1) according to claim 1, wherein microstructured symbol areas of at least two light conductors (13, 14, 15) of the light conductor stack are arranged adjacent to each other or overlapping each other for the observer (B) when the display surface (8) is viewed vertically.

10. Functional display (1) according to claim 1, wherein at least two light sources (12) differ in light color.

11. Functional display (1) according to claim 1, wherein the light conductors (13, 14, 15) have or are formed by a foil, respectively.

12. Functional display (1) according to claim 1, wherein lenses and/or baffles (17) and/or light channels are arranged between the light conductors (13, 14, 15) and the light sources (12), respectively.

13. Functional display (1) according to claim 1, wherein at least one light conductor (13) of the light conductors of the light conductor stack has at least one curved interface (32, 30) in the respective light path from the light source (12) to the relevant microstructured symbol area, respectively, in order to form at least one focusing lens element.

14. Functional display (1) according to claim 1, wherein the transparent or translucent layer is an air gap.

15. An assembly of a plurality of functional displays (1, 1 '), each formed according to any of the preceding claims and forming, from the perspective of the viewer (B), a plurality of display surfaces (8, 8 ') arranged alongside one another, and wherein at least the cover layer (23) and/or at least one light conductor (13, 13 ') are integrally formed.

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

17. 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) determined as an operating part (2) for contact or actuation or is arranged below a translucent and/or transparent cover layer forming the operating surface (9).

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