CN115503473A

CN115503473A - Function display and associated operating element for selectively displaying at least one symbol representing a switch function and/or a plurality of switch states

Info

Publication number: CN115503473A
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: 2022-12-23
Also published as: DE102021114524B3

Abstract

The invention relates to a functional display, comprising: a photoconductor stack forming a display surface facing a viewer; the optical waveguide stack is formed by at least two transparent or semitransparent planar optical waveguides which are arranged in an overlapping manner in the stacking direction, the optical waveguides are arranged in transparent or semitransparent layers, and the layers are formed by optically thinner materials compared with adjacent optical waveguides; at least one light source per light conductor, arranged to cause light to be incident into the respective light conductor via an end face of the associated light conductor; wherein each light guide is further provided with at least one microstructured symbol region arranged in or on the light guide, comprising a plurality of microstructures and being formed so as to be visible to an observer by means of illumination of light incident into the light guide in the event of activation of the light source; a mirror arranged on the side of the light conductor stack facing away from the observer, in order to reflect light incident into the at least one light conductor and subsequently emerging from the light conductor towards the observer.

Description

Function display and associated operating element for selectively displaying at least one symbol representing a switch function and/or a plurality of switch states

Technical Field

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

These function displays are necessary, for example, for a multi-function operating element in order to visualize the switching function and/or the switching state associated with the operating element. Electronic pixel matrix displays are commonly used for this purpose. However, they are relatively expensive, limiting their design and placement due to their mostly rectangular shape. Furthermore, electronic pixel matrix displays generally tend to "burn-in" when displaying static display content, that is, display content remains undesirably visible for a duration even when the display is off, due to visually perceptible impairment of the imaging layer of the display. Furthermore, the power consumption of such electronic pixel matrix displays is relatively high. In addition, in certain applications, the use of conventional electronic pixel matrix displays is prohibited due to the danger of injury, for example in the event of a head collision. As an alternative to pixel matrix displays, it is known to emit light of a light source incident into an end face of a light guide in a targeted manner by means of a surface structure at a main face serving as a display surface, wherein only regions provided with surface structures are provided locally and symbols or the like are reproduced. It is disadvantageous here that the symbol is in most cases visually unobtrusive and can therefore easily be overlooked by an observer. This leads to the observer, in particular the driver of the vehicle, for example erroneously estimating the actual switching state.

Disclosure of Invention

Against this background, it is an object of the present invention to provide a functional display which creates the possibility of increasing the display richness and thus the attention of the observer, in particular can produce a depth effect by means of an additional display plane and can furthermore be produced cost-effectively, is energy-saving and reliable and/or reduces the risk of injury, in particular in the event of a head impact. This object is achieved by a functional display as claimed in claim 1. Correspondingly advantageous operating elements, steering wheels containing the function display and assemblies formed from a plurality of function displays are the subject matter of the respective juxtaposed main claims. Advantageous embodiments are the subject matter of the dependent claims. 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 represent further embodiments of the invention. The specification additionally characterizes and describes the invention in detail, especially in connection with the accompanying drawings.

The invention relates to a function 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. Selective display is understood not only to mean the selective display of different symbols from a plurality of predetermined symbols, which is achieved in the solution of the invention by selectively selecting one or more light sources from a plurality of light sources and energizing them, but also to switch the light sources on and off to selectively visualize the symbols visually for the observer by activated backlighting or to make the symbols as close to disappear as possible for the observer by switching off backlighting.

The functional display according to the invention has a light conductor stack which, when the functional display is installed as intended, forms a display surface facing the viewer. The light conductor stack is formed from at least two transparent or translucent planar light conductors arranged one above the other in the stacking direction, which are arranged to be separated by transparent or translucent layers, preferably via air gaps, which are formed from an optically thinner material than the adjacent light conductors. The light guide body has a main surface facing the observer and a main surface facing away from the observer. At least one light conductor has a main surface facing away from the observer and facing the next adjacent light conductor in the stacking direction.

The functional display according to the invention can optionally have an outer transparent or translucent cover layer arranged between the light conductor stack and the viewer, by means of which cover layer the display surface defined by the light conductor stack is visible to the viewer when the functional display is arranged as intended. The material of the cover layer and the light guide body 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.

According to the invention, each light conductor is provided with at least one light source which is arranged such that light is incident into the respective light conductor via an end face of the associated light conductor. The light guide has, for example, two main surfaces which are opposite one another and which preferably extend parallel to one another, are connected via end surfaces, for example at the narrow sides and at the long sides of the light guide, which end surfaces together with the main surfaces of the light guide form a common edge. The end face is, for example, orthogonal to at least one main surface or both main surfaces of the optical waveguide.

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 characteristic of the light source to the end face defined for the entry of light into the light guide, a lens and/or a baffle and/or a light channel is preferably arranged between the light guide and the light source, respectively. The baffle or light channel is also formed, for example, to suppress light escaping to the observer, to other layers or light conductors than the assigned light conductor.

According to the invention, each light guide is also provided with a microstructured symbol region arranged in or on the light guide, which symbol region comprises a plurality of light-refracting and/or light-scattering microstructures. The microstructured symbol regions form symbols, individually or together with other microstructured symbol regions of the same or a further light conductor, which become luminescently visible to an observer by means of light incident into the respective light conductor when the light source is activated, as a result of light refraction and/or light scattering by the plurality of microstructures at the respective microstructure surface. The microstructure, for example, makes it possible to achieve an angle of incidence of the light onto the relevant main surface which does not satisfy the conditions for total reflection of the main surface of the light guide body as an interface, so that the light incident into the light guide body leaves the light guide body 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 subsequently emerges 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 by providing the mirror with a further display plane which is offset to the viewer to the rear relative to the light conductors of the light conductor stack, for example in a virtual image plane of the mirror. This depth effect is not achieved by using the lightguide stack alone and provides additional optical appeal at the viewer.

The microstructure of at least one microstructured light guide body is preferably formed such that light incident into the respective light guide body emerges in the direction of the observer, that is to say bypassing the mirror. Thus, 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 achieved, for example, by simultaneous display with a symbol area display of the mirror and a same symbol area display of the same or another photoconductor of the stack of photoconductors bypassing the mirror, wherein a parallax shift of the symbol areas implies to a binocular viewer the three-dimensional nature of the displayed symbol. In a further embodiment, for example, switching between the display of symbols with a mirror and the display of symbols by-passing the mirror of a further light conductor of the light conductor stack takes place in a time sequence, the attention of the observer can also be drawn to the functional display 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 inexpensively and provides the designer with a large amount of design space, which also relates to the manner in which the functional display is placed. Functional displays exhibit aging phenomena which are hardly affected by light radiation and are relatively energy-efficient. The microstructuring renders the symbol, for example, in a positive manner as an image, as a representation of its inverse or as its contour. The previously mentioned depth effect can be set, for example, by the distance between the optical conductors, for example the air gap thickness. Said distance is for example in the range of 1 to 3 mm.

The microstructured symbol region can be introduced into the light guide body by laser ablation, for example by three-dimensional glass drawing (Vitrographie, also known 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 surfaces of each light guide, as a result of which a cost-effective functional display can be realized.

The microstructured symbol region is preferably formed by a plurality of microstructures formed in the same shape, which microstructures together define a continuous microstructured symbol region of each light guide body. A microstructure is preferably understood to mean a single projection on a main surface or a single depression in a main surface. In order to substantially exclude the visibility to the naked eye, the maximum dimension of each microstructure is in the range from 1 to 50 μm, preferably from 1 to 25 μm, for example. The microstructures are preferably arranged so as to be distributed uniformly spaced apart over the entire microstructured symbol region of the main surface. The microstructures are for example shaped as pyramids or prisms. The microstructures are preferably not only identical in shape, that is to say uniformly shaped, but also have a uniform orientation within the respective microstructured symbol region. For example, a uniform orientation can only be produced on a flat main surface if each microstructure can be mapped onto an adjacent microstructure of the same microstructured symbol region by means of a fictitious, only translatory displacement. The microstructures are more preferably formed such that they generate a collimated light beam formed by light exiting from the light guide, which light beam originates from the light source and has previously entered the light guide via the end face.

The microstructured symbol areas of each of the photoconductor stacksThe average number density of the microstructures is preferably 500 to 7000 per mm ² In the range between 1000 and 4000, more preferably between 1000 and 4000, per mm ² Within the range of (a). On the one hand, this ensures that the light source is not visible when it is switched off, whereas the impression of a uniformly illuminated symbol area can be simulated for the "naked" eye when the light source is activated. The average number density of each light conductor is preferably selected to be substantially the same, wherein "substantially the same" means that less than 100 per mm are present between the number densities of the light conductors ² The maximum deviation of (c).

Preferably, at least two directly adjacent light conductors are provided, the microstructuring of which is provided only on the main surfaces 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, ensures transparency through the functional display, in order to give the observer the possibility of following other displays, meters or road directions through the functional display. Thus, for example, the function display can be placed at the steering wheel, for example in the region between the steering wheel hub and the steering wheel ring, without affecting the view of the dashboard. The proportion of the surface of all the surface-structured symbol regions on the display surface is preferably less than half.

The respective light conductors need not necessarily be formed in one piece, but they 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 layer structure. The light guide is produced, for example, by back-injection molding a transparent foil (e.g., a PC foil or a PE foil) with a first material, in particular a thermoplastic.

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

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

In order to provide additional color effects, according to a preferred embodiment, the at least two light sources differ from one another in terms of the light color.

It is preferably provided that the light guide has at least one curved interface in each case in the respective light path from the light source to the relevant symbol region, in order to form at least one focusing lens element. The light guide body forms, for example, at its end faces, a curved light entry face provided for the light of the light source. In a further embodiment, the light guide has one or more interruptions, each of which has an interface that acts as a light exit surface and a light entry 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 guide, in particular in the event of the action of extraneous light, according to a preferred embodiment the respective light guide has an antireflection coating, which is often also referred to as an antireflection coating or a compensation coating, at least one of the end faces, preferably at the end face opposite the end face facing the light source. The task of an antireflection 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. For example, the antireflection coating can be applied in a circumferential manner, in addition to the light entry region provided for the light of the light source. The antireflection coating has, for example, an optical refractive index which is between the value of air and the material of the light guide or of the screening layer.

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

The invention also relates to an operating element having a functional display formed in one of the previously described embodiments. The actuating element has, for example, a leg for fastening the actuating element to a vehicle component, such as an instrument panel, a lining panel of a passenger compartment or, in particular, a steering wheel of a motor vehicle. The operating element according to the invention also has, for example, an operating part which defines an operating surface and which is formed as at least one self-supporting lever arm. The self-supporting lever arm is supported on one side, for example, by means of a solid hinge at the leg in order to be able to pivot the actuating part relative to the leg about an imaginary pivot axis against a restoring force under an actuating force acting perpendicularly to the actuating surface. Means are also provided, for example, for detecting the degree of pivoting between the operating member and the leg. The following regions of the component are generally referred to as solid hinges: the regions allow pivoting between the two rigid body regions through bending. The solid hinge allows a play-free and thus rattling-noise-free mounting of the actuating element on the leg. The legs and the operating parts are formed, for example, from a thermoplastic, 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 about an imaginary pivot axis from the unactuated rest position to the actuated maximum pivoting 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 an operating part for contacting or actuating.

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 rim 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 function display is preferably a component of an operating element fastened to the steering wheel. The legs of the actuating element are secured, for example, in a rotationally fixed manner to the steering wheel rim. The display surface of the function display is preferably arranged between the steering wheel rim and the steering wheel hub or a bumper of the steering wheel covering the steering wheel hub.

Drawings

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

fig. 1 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 with an operating element 10 of a functional display;

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

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

fig. 5 is a horizontal cross-section 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 outer transparent or translucent, but at the same time not mandatory and only optionally provided cover layer 23, which, in the intended arrangement of the functional display 1, defines the surface facing the viewer B. 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 made of a glass material. The cover layer 23 may also be part of a layer construction formed by a plurality of layers.

According to the invention, the functional display 1 also comprises a light conductor stack which is formed by at least two transparent or translucent planar

light conductors

13, 14 which are arranged one above the other and are 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 refractive index which is lower than the refractive index of the

adjacent light conductor

13, 14. This air layer 24 is likewise arranged between the cover layer 23 and the nearest adjacent light conductor 13. The

light conductors

13, 14 each form at least a main face H facing the observer B and a main face H 'facing away from the observer B, while the upper light conductor 13 closer to the observer B has a main face H' facing away from the observer and 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 in such a way that the light generated by it is incident into the assigned

light conductor

13, 14 via an end surface S which is lateral to the stacking direction. In order to prevent undesired light scattering or light radiation from entering the adjacent

light conductors

13, 14, respectively, a baffle 17 is provided. At the end faces opposite one another, an antireflection coating 33 is applied to 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 surface of the light guide body 13, a plurality of individual microstructures 16 are introduced by embossing or forming in a main surface H' facing away from the observer, said microstructures taking care of the light L incident into the light guide body 13 exiting from the respective light guide body 13 in the direction of the observer B by light refraction and/or light scattering and defining microstructured symbol regions comprising the microstructures 16. This symbol region, alone or in optical cooperation with other symbol regions, again produces the shape of a symbol which is visible to the observer B as a glow when 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 guide bodies 14 facing away from the observer B likewise have microstructures 26 in their main surface H facing the observer B, which are likewise single and are formed identically to one another. These microstructures are also introduced into the relevant main surface of the light guide 14, here the main surface H facing the viewer B, by embossing or shaping. These light beams L' which are 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, said mirror here being in the form of a partially transmissive metal vapor coating on a transparent plastic layer 28, said mirror here being arranged at a distance from the light guide 14 by an air gap 24, alternatively an arrangement adjoining the light guide 14 is also conceivable.

Only by reflection by the mirror 27 is the light L' originally incident into the light guide 14 reflected into the direction of the observer B. Thus, at the viewer 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 a symbol region display by means of a mirror of the lower light guide body 14 of the light guide stack and a display of the same symbol region by-passing the mirror of the upper light guide body, wherein the parallax offset of the symbol region produces an illusion of the three-dimensional nature of the displayed symbol for a binocular observer.

By switching between the display of symbols with mirrors for the lower light conductors 14 of the light conductor stack and the display of symbols bypassing the mirrors for the upper light conductors 13 in a further embodiment, for example, in a chronological sequence, the attention of the observer can also be drawn to the functional display 1 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 implemented simply and cost-effectively and offers the designer a large amount of design space, which also relates to the manner in which the functional display 1 is arranged. Functional displays exhibit aging phenomena which are hardly affected by light radiation and are relatively energy-efficient. The microstructured symbol regions reproduce the symbol, for example, alone or together with other symbol regions, in a positive manner as an image, as an inverse illustration thereof or as an outline thereof. The previously mentioned depth effect can be set, for example, by the distance between the

light conductors

13, 14, for example the thickness of an air gap. The distance is for example in the range of 1 to 3 mm.

All

light conductors

13, 14 are transparent outside the microstructured region. Since the mirror 17 is also provided with partial light transmission, a large part of the display surface 8 is optically transparent, so that, for example, a perspective through the functional display is ensured in order to give the observer B the possibility of following other displays or road courses through the functional display. Thus, for example, the function display 1 can be placed on 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 perpendicularly to the microstructured regions of all

light conductors

13, 14, the projected microstructured symbol regions of the individual

light conductors

13, 14 do not overlap, so that the display quality of the symbol is not impaired.

Fig. 2 shows an embodiment of the operating element 1 according to the invention. This actuating element has a leg 3 for fastening the actuating element 1 to a vehicle component, such as an instrument panel, a lining of a passenger compartment or a steering wheel rim 11, in particular of a motor vehicle steering wheel. The operating element 10 of the invention also has an operating part 2 which defines an operating surface 9 and 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 at the leg 3 in order to be able to pivot the actuating 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 perpendicularly to the actuating surface 9. The restoring force is generated, for example, by a 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 part 2 and the leg 3. The solid hinge 4 is formed only by the integral connection between the leg 3 and the operating part 2. The operating element 1 of the invention is particularly suitable for designs in which the maximum degree of pivoting about the imaginary pivot axis a from the unactuated rest position shown in fig. 2 to the maximally 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 control electronics, not shown, with a control electrical signal in order to generate an active haptic feedback (also referred to as a haptically perceptible output), wherein the actuator 5 is preferably fastened only at the operating element 2. The Actuator 5 is preferably an inertia-based, motor-based Actuator, such as a motor with a mass mounted eccentrically with respect to its center of gravity fixed to its rotating drive shaft, 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. The actuator 5 is preferably fixed to the operating element 2 by means of a force-fit or material-fit connection, for example by screwing or gluing. Since only the operating element 2 is fastened, the input of structural noise into the steering wheel rim 11 and thus into the vehicle components is prevented 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 part 2 capacitively, optically and/or inductively. Due to the play-free mounting of the operating element 2 by means of the solid-state hinge 4 in cooperation with the means 6 for preferably contactless detection of the degree of pivoting, a low to no hysteresis detection of the actuating force is achieved, which is provided, for example, as an output for triggering a switch function or a control function or at least an optically, acoustically or tactilely perceptible output.

The operating face 9 is provided by a transparent cover layer 23 of the functional display 1, which cover layer covers the display face 8 of the functional display 1. The function display 1 is formed to be partially transparent in order to ensure that an observer or operator can see through the function display 1 unimpeded into the operating region located therebelow, for example the meter of a meter panel. 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 each separated by an air layer 24 arranged between the

light conductors

13, 14, 15, which thus forms an air gap between two adjacent light conductors of the

light conductors

13, 14, 15. This air layer 24 is likewise arranged between the cover layer 23 and the nearest adjacent light conductor 13.

The

light conductors

13, 14, 15 each form at least a main surface H facing the observer B, while the two upper

light conductors

13, 14 closer to the observer B each have a main surface H' facing away from the observer and 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 in such a way that the light generated by it is incident into the assigned

light conductor

13, 14, 15 via an end face which is lateral to the stacking direction. In order to prevent unwanted light scattering or light radiation from entering the associated

light conductors

13, 14, 15, respectively, in this case, a baffle 17 is provided. At the end faces 25 which face one another, an antireflection coating 25 is applied to the end faces of the

light conductors

13, 14, 15 in order to minimize back reflections in the respective

light conductors

13, 14, 15. The microstructured symbol regions formed by the plurality of microstructures 16 are introduced into at least one main surface of the main surfaces of the light conductors (in this case, light conductors 13, 14) 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 the same in shape and have a diameter in the range of 1 to 25 μm, respectively. The light conductor 14 as well as the light conductor 15 also has a plurality of microstructures 26.

The lower light guide body 15 and the middle light guide body 14 facing away from the observer B likewise have microstructures 26 in their main faces H facing the observer B, which microstructures are likewise unitary and are formed to be identical in shape to one another. These microstructures are also introduced into the relevant main surface of the respective

light guide

14, 15, here the main surface H facing the observer B, by embossing or shaping. This main surface couples light incident in the respective

light conductors

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, here in the form of an opposite, partially transmissive metal vapor coating on a transparent plastic layer 28, which here adjoins the lower light conductor 15, alternatively an arrangement spaced apart from the light conductor 15 is also conceivable. Only by reflection by the mirror 27, light originally incident into the light guide body 14 is reflected in the direction of the observer B. Thus, at the viewer B, depending on the activation of the light source 12, a depth effect or even a stereoscopic impression of the displayed symbol may be achieved by different display planes. In one embodiment, this is achieved, for example, by simultaneous display of the symbol region display with the mirror of the lower light conductors 14 of the light conductor stack and of the same symbol region display of the upper light conductors 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. By switching between the mirror-implemented representation of the symbols of the

light conductors

14, 15 of the light conductor stack and the mirror-bypassed representation of the symbols of the

light conductors

13, 14 in a further embodiment, for example in a chronological sequence, the attention of the observer can also be drawn to the functional display 1 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 inexpensively and offers the designer a large amount of design space, which also relates to the way in which the functional display 1 is placed. The functional display exhibits an aging phenomenon which is hardly affected by light radiation and is relatively energy-saving. The microstructured symbol regions reproduce the symbol, for example, alone or together with other symbol regions, in a positive manner as an image, as an inverse illustration thereof or as an outline thereof. The previously mentioned depth effect can be set, for example, by 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 the display surface 8 remains transparent and, for example, ensures a perspective through the functional display 1, in order to give the observer B the possibility of following other displays or road courses through the functional display. Thus, for example, the function display 1 can be placed on 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 perpendicularly, the microstructured symbol regions of the light-conducting

bodies

13, 14, 15 overlap at least partially, so that, by using light sources 12 with light radiation of different colors, a multi-color symbol is produced which can be made visible by simultaneously illuminating a plurality of light-conducting

bodies

13, 14, 15 completely. In order to avoid undesired light propagation in the respective

light guide

13, 14, 15, in particular in the event of the action of extraneous light, each

light guide

13, 14, 15 has an antireflection coating 33, which is also often referred to as an antireflection coating or a compensation coating, at least one of the end faces, preferably at the end face not facing the light source 12. The task of the antireflection coating is to reduce the amount of light reflected into the light guide body 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 close to circumferentially. This antireflection coating 33 has, for example, an optical refractive index which is between the value of air and the material of the

light conductors

13, 14, 15. The ends of the

light conductors

13, 14, 15 facing away from the light source 12 are each secured in a material-fit 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 a 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 of the invention also 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 mounted in a pivotably movable manner on a leg of the operating element 10. The leg of the actuating element 10 is fixed in this case to the steering wheel 11 in a rotationally fixed manner. The 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 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, depending on this selection, the different symbols 18 in the region of the display surface 8 become visible to the observer (that is to say the driver), while the dashboard or the instrument thereof 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 assembly according to the invention formed by a plurality of functional displays 1,1', which for example each have the sectional configuration as shown in fig. 1, 4 or 5 and are arranged alongside one another from the viewpoint of the observer, in order thereby to form display surfaces 8,8' arranged alongside one another. This arrangement is distinguished in that the at least one light guide 13 of one functional display 1 is formed in one piece with the light guide 13 'of another functional display 1' in order to form a common light guide. The other light conductors not shown here and located thereunder are formed with correspondingly identical dimensions. However, embodiments are also to be included according to the invention in which the light guides of each functional display 1,1' are formed to differ in their outer dimensions. In order to minimize the mutual light incidence from one functional display 1 into the other functional display 1' and vice versa, conical interruptions 29 are formed in the common light guide 13, 13', which interruptions are filled with a material having a lower refractive index than the material of the common light guide 13, 13 '. In this case, some of the end faces of the light conductors 13, 13' are provided with an antireflection coating 33.

Fig. 5 shows a sectional view through a further assembly according to the invention formed by a plurality of functional displays 1,1', which for example each have the sectional configuration as shown in fig. 1, 4 or 5 and are arranged alongside one another from the viewpoint of the observer, in order thereby to form display surfaces 8,8' arranged alongside one another. This arrangement is also distinguished in that the at least one light guide 13 of one functional display 1 is formed integrally with the light guide 13 'of the other functional display 1' in order to form a common light guide. The other light conductors not shown here and located thereunder are formed with correspondingly identical dimensions. However, embodiments are also to be included according to the invention in which the light guides of each functional display 1,1' are formed differently in their outer dimensions. In order to minimize the mutual light incidence from one functional display 1 into the other functional display 1' and vice versa, it can be seen from fig. 4 that tapered interruptions are formed in the shared light conductors 13, 13', which interruptions are filled with a material having a refractive index that is lower than the refractive index of the material of the shared light conductors 13, 13 '. This conical interruption is omitted in the embodiment shown in fig. 5. In the embodiment shown here, the respective light guide 13, 13' forms a curved boundary surface 30, 32 in the respective light path from the light source 12, 12' to the associated symbol 18, 18', in order to form an optically effective, preferably focusing, lens element. For example, in the case of the light guide 13, a concave entry surface 30 is provided in the outer end face of the light guide 13, whereas the light guide 13 'has a plurality of interruptions 31 which are filled with a material having a lower refractive index than the material of the shared light guide 13, 13'. The lens element formed by the interruption 31 likewise acts in a focusing manner on the light path from the light source 12 'to the relevant symbol 18'. In this case, some of the end faces of the light conductors 13, 13' are provided with an antireflection coating 33.

Claims

1. A functional display (1) for selectively displaying symbols (18) representing switch functions and/or switch states, in particular for a motor vehicle, having:

a light conductor stack which, when the functional display (1) is installed as intended, forms a display surface (8) facing a viewer (B); 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, which are arranged spaced apart by a transparent or translucent layer, preferably via an air gap (24), which layer is formed by an optically thinner material than the adjacent light conductors, such that the light conductors (13, 14, 15) each have a main face (H) facing the observer (B) and a main face (H ') facing away from the observer (B) and in at least one light conductor (13, 14, 15) the main face (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 ') of each light conductor (13, 14, 15), which is arranged such that light (L, L') is incident into the respective light conductor (13, 14, 15) via an end face (S) of the associated light conductor (13, 14, 15);

wherein each light guide (13, 14, 15) is further provided with at least one microstructured symbol region arranged in or on the light guide (13, 14, 15), which symbol region comprises a plurality of light-refracting and/or light-scattering microstructures (16, 26) and is formed so as to be luminescently visible to the observer (B) by means of the light incident into the light guide (13, 14, 15) in each case when the light source (12, 12') is activated, in order to display a symbol (18) composed of one or more microstructured symbol regions for the observer (B);

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

2. The functional display (1) according to claim 1, wherein the microstructures (16) of at least one microstructured light conductor (13, 14, 15) are formed such that light (L) incident into the respective light conductor (13, 14, 15) exits in the direction of the viewer (B).

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

4. The functional display (1) according to any of the preceding claims, wherein the average number density of the microstructures (16, 26) for all microstructured symbol areas of the light conductor (13, 14, 15) is between 1000 and 4000 per mm ² Within the range of (1).

5. The functional display (1) according to any of the preceding claims, wherein the microstructures (16, 26) of all microstructured symbol areas each have a maximum diameter in the range of 1 to 25 μ ι η.

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

7. The functional display (1) according to any of the preceding claims, wherein the proportion of the area of all microstructured symbol areas is less than half of the display surface (8).

8. The functional display (1) according to any one of the preceding claims, wherein the microstructured symbol areas of at least two light conductors (13, 14, 15) of the light conductor stack are arranged non-overlapping, preferably spaced apart, to the observer (B) when viewing the display surface (8) perpendicularly.

9. The functional display (1) according to any one of the preceding claims, wherein the microstructured symbol areas of at least two photoconductors (13, 14, 15) of the photoconductor stack are arranged adjacent to each other, preferably overlapping, more preferably completely coinciding, for the viewer (B), when viewing the display surface (8) perpendicularly.

10. The functional display (1) according to any of the preceding claims, wherein at least two light sources (12) differ in light color.

11. The functional display (1) according to any of the preceding claims, wherein the light conductors (13, 14, 15) each have a foil or are formed by a foil.

12. Functional display (1) according to any of the preceding claims, wherein a lens and/or a baffle (17) and/or a light channel, respectively, is arranged between the light conductor (13, 14, 15) and the light source (12).

13. The functional display (1) according to any one of the preceding claims, wherein at least one of the light conductors (13) of the light conductor stack has at least one curved interface (32, 30) in each case in the respective light course from the light source (12) to the associated microstructured symbol region, in order to form at least one focusing lens element.

14. An assembly formed by a plurality of functional displays (1, 1 ') which are each formed according to one of the preceding claims and, from the point of view of the viewer (B), form a plurality of display surfaces (8, 8 ') arranged next to one another, and wherein at least a cover layer (23) and/or at least one light conductor (13, 13 ') is formed in one piece.

15. Operating element (10) with a functional display (1) according to one of the preceding claims.

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

17. A steering wheel (20) for a motor vehicle with a functional display (1) according to one of the preceding claims 1 to 13.