DE102024111319A1 - Light guide device - Google Patents

Abstract

The invention relates to a light-guiding device (1) for the homogeneous light distribution of a light which can be coupled in by a light source (2) at a coupling surface (11) onto a luminous surface (3), having two side walls (20) which define between them a receiving space which closes off a light-guiding element (10) in a width direction (B) orthogonal to the longitudinal direction (L), wherein a respective reflector surface (21) which closes off the side walls (20) to the light-guiding element (10) follows a respective predetermined longitudinal profile in the longitudinal direction (L), by which the receiving space widens from the coupling surface (11) along the longitudinal direction (L) to a coupling-out surface (12) in the width direction (B), and wherein the respective reflector surface (21) follows a respective predetermined height profile in a height direction (H) orthogonal to the longitudinal direction (L) and the width direction (B), by which the receiving space widens from a rear base surface (13) of the light-guiding element (10) widens along the height direction (H) towards a visible-side head surface (14) of the light-guiding element (10) in the width direction (B), so that a coupled-in light is homogenized by reflection at the side wall from the coupling-in surface to the coupling-out surface.

Description

The invention relates to a light-guiding device for homogeneous light distribution or for homogenizing a light that can be coupled from a light source onto a luminous surface.

In principle, light-guiding devices and light-guiding devices usable for the homogenization of light are known in the prior art. However, it is advantageous to realize the homogenization of the light in the smallest possible space and to homogenize as much of the coupled light as possible, so that the luminous surface is illuminated as completely, evenly, and well as possible with as little coupled light as possible, and in particular, no individual light points corresponding to the illuminant are discernible on the luminous surface.

For example, the DE 10 2023 127 543.7 , the teaching of which is hereby fully incorporated into the disclosure of the present application, a cladding element for vehicles is known in which light coupled in from the rear is guided along a predetermined light path via a light guide element having tilted reflection surfaces from a rear-side illuminating means to a visible-side luminous surface and is simultaneously homogenized along the light path.

However, this homogenization can be further optimized to achieve a smaller required installation space for homogenization and a higher light output or greater efficiency during homogenization.

The invention is therefore based on the object of overcoming the aforementioned disadvantages and providing a light-guiding device by means of which a light which can be coupled in from a light source can be homogenized in a small installation space and efficiently for illuminating a luminous surface.

This problem is solved by the combination of features according to patent claim 1.

According to the invention, a light-guiding device for the homogeneous distribution of light coupled from a light source onto a luminous surface is proposed. The light-guiding device comprises a light-guiding element with a rear-side coupling surface corresponding to the light source and a visible-side coupling-out surface corresponding to the luminous surface, which is spaced apart from the coupling surface in a longitudinal direction along a longitudinal axis. The light-guiding element is preferably identical to the light-guiding element according to DE 10 2023 127 543.7 formed, wherein the presently proposed light guide device is inserted into a DE 10 2023 127 543.7 proposed cladding element can be integrated. The light-guiding element proposed here is designed according to the invention to guide light coupled into the light-guiding element at the coupling-in surface along a coupling-in axis in the longitudinal direction and to couple it out at the coupling-out surface along a coupling-out axis offset in the longitudinal direction to the coupling-in axis towards the luminous surface, so that the light from the coupling-in surface to the coupling-out surface follows a predetermined light path, along which the light is homogenized, ie distributed so that the luminous surface is evenly illuminated. However, when the light is irradiated or coupled in, scattered light can occur, so that the scattered light does not directly follow the light path and contributes little or not to the illumination of the luminous surface. To minimize stray light or redirect stray light onto the light path, the light-guiding device is provided in the present case with two side walls which are axially symmetrical opposite one another with respect to a plane of symmetry dividing the input and output surfaces, and which define between them a receiving space which delimits or closes the light-guiding element in a width direction orthogonal to the longitudinal direction along a transverse axis. The light-guiding element is therefore delimited by the side walls in the width direction orthogonal to the longitudinal direction and lies directly against them. For this purpose, a reflector or reflection surface is provided on each of the side walls towards the plane of symmetry or towards the light-guiding element, which reflector or reflection surface is thus particularly designed to reflect light or stray light incident from the light-guiding element. In this case, the side walls on their respective inner side facing the light-guiding element or the reflector surfaces closing the side walls towards the light-guiding element follow a predetermined longitudinal profile in the longitudinal direction and a predetermined height profile in a height direction orthogonal to the longitudinal direction and the width direction along a vertical axis. In this case, the invention provides that the receiving space defined by the reflector surfaces widens, in particular symmetrically in the width direction, through the longitudinal profile from the input surface or an end face of the light-guiding device associated with the input surface, along the longitudinal direction, to the output surface or an opposite end face of the light-guiding device associated with the output surface. Furthermore, it is provided that the receiving space defined by the reflector surfaces widens, in particular symmetrically, through the height profile from a rear, i.e., a rear-facing base surface of the light-guiding element, along the height direction to a visible-side, i.e., a visible-side, head surface of the light-guiding element, widens, in particular symmetrically in the width direction. This results in the receiving space having a substantially U-shaped basic form both in a cross-section orthogonal to the longitudinal direction and in a longitudinal section orthogonal to the height direction.

Due to the predetermined longitudinal profile and the predetermined height profile of the inner surface of the side walls or the reflection surfaces, a scattered light radiated onto them in the width direction can be directed in a predetermined manner back onto the light path or to the output axis and onto the luminous surface, so that the scattered light also contributes to the homogeneous illumination of the luminous surface.

However, it is also advantageous that the side walls simultaneously fulfill a housing function, so that the side walls can form a section of a housing surrounding the light-guiding element, by means of which the light-guiding device and a product possibly comprising the light-guiding device can be stabilized.

For the sake of clarity, it should be mentioned that the longitudinal, transverse and vertical axes or the corresponding longitudinal, width and height directions are orthogonal to each other and form a spatial Cartesian coordinate system.

An advantageous variant of the light-guiding device provides that the plane of symmetry is spanned by the vertical and longitudinal directions and is orthogonal to the width direction. The input and output surfaces can be axially or mirror-symmetrical to the plane of symmetry. Furthermore, the light-guiding element can also be axially or mirror-symmetrical to the plane of symmetry.

The coupling surface is preferably offset in the vertical direction relative to the base surface in the direction of the head surface, so that the light-guiding element has a preferably frontal recess relative to the base surface, on which the coupling surface is provided. Furthermore, the coupling-out surface can be offset in the vertical direction relative to the head surface in a direction facing away from the base surface, so that the light-guiding element has a projection on the head surface, on which the coupling-out surface is provided.

The side walls extend in the vertical direction from the base surface towards the head surface, but do not necessarily reach it.

A variant is particularly advantageous in this case in which a height of the side walls and/or the reflector surfaces of the side walls, starting from the base surface, corresponds to between 60% and 90%, in particular between 70% and 80% and further in particular 75% of a height of the light-guiding element from the base surface to the head surface, so that between a visible end face of the side walls or a front edge of the reflector surfaces facing the visible side and the head surface, a gap which is translucent in the width direction remains, through which scattered light can pass and/or be coupled out, so that this scattered light does not lead to disadvantageous illumination on the luminous surface.

Preferably, the light-guiding element extends in the width direction through the gap beyond the side walls or ends in the width direction with the side walls or an outer side of the side walls.

Preferably, the height profile of the reflector surfaces, starting from the base surface of the light-guiding element to the head surface of the light-guiding element, follows a (first) radius in a first region that widens the receiving space in the width direction. This radius transitions smoothly into a (first) straight line, which, in a directly adjacent second region, runs while maintaining the width of the receiving space. The (first) straight line thus preferably runs parallel to the plane of symmetry and transitions into the (first) radius as a tangent of a circle determining the (first) radius.

The height profile determined by the (first) radius preferably corresponds to a quarter to a sixth, in particular a fifth, of a circle with a radius equal to the height of the side walls. The (first) straight line continues the height profile up to the visible end face of the side wall, whereby a chamfer or bevel can be provided on the end face of the (first) straight line, via which the reflective surface or the height profile merges into the end face of the respective side wall.

The light-guiding element is preferably terminated in the longitudinal direction by two opposing, preferably parallel, end faces tilted relative to the coupling axis, which can also be referred to as reflection surfaces or reflector surfaces. Of the two end faces, a first end face is designed to direct the light coupled along the coupling axis onto a predetermined light path along the longitudinal axis. The second end face of the two end faces is also designed to direct the light from the predetermined light path onto the coupling axis.

Furthermore, and likewise preferably, the longitudinal profile of the reflector surfaces, starting from one or the first end face of the light-guiding element on the input surface to one or the second end face of the light-guiding element on the output surface, follows, in a first region, a (second) radius that widens the receiving space in the width direction, which radius transitions smoothly into a (second) straight line that runs in an immediately adjacent second region while maintaining the width of the receiving space. The (second) straight line also preferably runs parallel to the plane of symmetry and transitions into the (second) radius as a tangent of a circle determining the (second) radius.

The longitudinal profile determined by the (second) radius preferably corresponds to a quarter to a sixth, in particular a fifth, of a circle with a radius equal to the length of the side walls. The (second) straight line continues the longitudinal profile up to the second end face of the light-guiding element.

Preferably, a length of the side walls and/or the reflector surfaces of the side walls, starting from the first end face, corresponds to between 60% and 90%, in particular between 70% and 80% and further in particular 75% of a total length of the light-guiding element from a terminal edge of the first end face to a terminal edge of the second end face.

Furthermore, according to an advantageous development, the light-guiding device further comprises end walls which, together with the side walls, completely enclose the light-guiding element, leaving the coupling-in surface and the coupling-out surface free, and correspondingly form a housing surrounding the light-guiding element with the side walls, wherein the coupling-in surface and the coupling-out surface remain free of this, so that light can be coupled in at the coupling-in surface and light can be coupled out at the coupling-out surface.

In addition, the light-guiding device preferably has a diffuser which is arranged directly on the output surface, covering the light-guiding element from a visible side, and which preferably forms the luminous surface on its visible side, so that the light-guiding element is not visible through the diffuser.

Additionally or alternatively, the light-guiding device can further comprise the illuminant, which is arranged on the coupling surface to form an air gap, so that light can be coupled into the coupling surface by the illuminant via the air gap.

The features disclosed above can be combined as desired, as long as this is technically possible and they do not contradict each other.

• 1 eine perspektivische Ansicht eines Zierteils mit einer integrierten Lichtleitvorrichtung;
• 2 perspektivischer Längsschnitt entlang der Symmetrieebene durch die Lichtleitvorrichtung;
• 3 Längsschnitt entlang der Symmetrieebene durch die Lichtleitvorrichtung;
• 4 zu der Längsachse orthogonaler Querschnitt durch die Lichtleitvorrichtung;
• 5 zu der Hochachse orthogonaler Längsschnitt durch die Lichtleitvorrichtung.

Other advantageous developments of the invention are characterized in the subclaims or are presented in more detail below, together with the description of the preferred embodiment of the invention, with reference to the figures. They show:

• 1 a perspective view of a trim part with an integrated light-guiding device;
• 2 perspective longitudinal section along the plane of symmetry through the light-guiding device;
• 3 Longitudinal section along the plane of symmetry through the light-guiding device;
• 4 cross-section through the light-guiding device orthogonal to the longitudinal axis;
• 5 Longitudinal section through the light guide device orthogonal to the vertical axis.

The figures are exemplary schematics and show different views of an embodiment variant, so that identical reference numerals in the figures indicate identical functional and/or structural features. However, the various figures may also show views of different embodiment variants, so that they can also be viewed in isolation from one another.

In 1 A trim element or functional assembly with an integrated light-guiding device 1 is depicted, which is intended to illuminate a spatially limited luminous surface 3 on the visible side facing upwards in the illustration. For this purpose, the trim part or functional element accommodates the light-guiding element 10 and side walls 20, which are covered by the diffuser 4 on the visible side.

Although only one light-guiding device 1 is shown in the cladding element in the present case, a plurality of such light-guiding devices 1 can be arranged adjacent to one another in the width direction B or along the associated transverse axis and can also be connected to one another by their light-guiding elements 10. Directly adjacent side walls 20 of directly adjacent light-guiding devices 1 can also be formed integrally with one another. This also applies to the diffusers and end walls of such light-guiding devices 1.

A basic structure of the light guide device 1 is shown in 2 visible, which shows a section through the light-guiding device 1 along the symmetry plane S explained below. Light can be coupled into the light-guiding element 10 by a light-emitting means 2, for example an LED, at a coupling surface 11 along a coupling axis E. The light is deflected at a first tilted reflection or end surface 15 of the light-guiding element 10 onto the predetermined light path P, along which the light is specifically scattered in the light-guiding element 10 for homogenization and guided onto a second reflection or end surface 16 opposite in the longitudinal direction L, at which the light is directed along the coupling-out axis A to the coupling-out surface 12, so that the light is coupled into the diffuser 4 at the coupling-out surface 12 and homogeneously illuminates the luminous surface 3 which is spatially limited, for example, to 20 mm x 3 mm.

For this purpose, the light-guiding element 10 and the illuminant 2 are also spaced apart by an air gap 5 with a height H7 and a width W5, wherein the height H7 and the width W5 are preferably selected such that the light emitted by the illuminant 2 is distributed substantially over the entire surface of the coupling surface 11.

In the present case, it is also provided that the coupling surface 11 is offset in the height direction relative to a base surface 13 on the light-guiding element 10 facing the rear side in the direction of a head surface 14 facing the visible side, so that a recess is formed on the first end face 15. The coupling surface 12 is provided on a projection opposite the head surface 14 and is correspondingly also offset in the height direction H relative to the head surface 14. Both the recess and the projection or the respective height offset serve to minimize stray light and increase efficiency, since more light can be coupled in at the coupling surface 11 and control light components are shielded or filtered at the coupling surface 12.

In 2 It is also advantageously visible that the light-guiding element 10 is housed not only by the side walls 20, but also on the rear side by an end wall 6 designed as a base plate with a thickness or height H4, on the visible side by an end wall 43 extending in the gap determined by the projection, and on the end sides by respective end walls 41, 42, wherein the side walls 20 are in particular designed integrally with the end walls 41, 42, 43 and can be manufactured together, for example, by injection molding.

Reflecting surfaces towards the light-guiding element 10 can be formed or provided through the end walls 6, 41, 42, 43 as well as through the side walls 20, said reflecting surfaces being formed on the side walls 20 as the reflector surfaces 21.

As can be seen in the figures, it is provided that the side walls 20 and the reflector surfaces 21 provided or formed on them and facing the light-guiding element 10 are axially or mirror-symmetrically opposite one another with respect to the plane of symmetry S and define between them a receiving space which closes the light-guiding element 10 in a width direction B orthogonal to the longitudinal direction L.

The reflector surfaces 21 follow in the longitudinal direction L a respective predetermined longitudinal profile which is axially or mirror-symmetrical to one another with respect to the plane of symmetry S, and in a height direction H orthogonal to the longitudinal direction L and the width direction B a respective predetermined height profile which is axially or mirror-symmetrical to one another with respect to the plane of symmetry S.

Due to the longitudinal course, the receiving space widens from the coupling surface 11 or the associated first end face 15 along the longitudinal direction L to the coupling surface 12 or the associated second end face 16 in the width direction B, as is particularly shown in 5 is visible.

Due to the height progression, the receiving space widens from the rear base surface 13 of the light-guiding element 10 along the height direction H to the visible-side head surface 14 of the light-guiding element 10 in the width direction B, as is particularly evident in 4 is visible.

As also shown by the 4 and 5 It is particularly advantageous for both the longitudinal profile and the height profile that they each have two areas, wherein the respective profile is formed in a first area by a partial circle determined by a radius R1, R2, through which the receiving space widens in the width direction B and which merges into a straight line 31, 32 tangential to the partial circle, which extends parallel to the symmetry plane S while maintaining the width. The tangential straight line 32 with regard to the longitudinal profile has, as in 5 shown, by way of example, a length L9 and a width W2, through which the light falling on the tilted end face 16 can be homogenized onto the R light and uniformly directed onto the luminous surface 3.

In 4 Another particularly advantageous feature is also apparent. The variant shown provides that the side walls 20 extend from the base surface 13 towards the head surface 14, but only have a height H6 of 75% of the height H2 of the light-guiding element 10 between the base surface 13 and the head surface 14, so that a respective gap 23 is created between the end face 22 of the side walls 20 and the head surface 14, through which unusable scattered light can be coupled out of the receiving space or the light-guiding element 10 and accordingly does not lead to faulty, ie inhomogeneous, illumination of the luminous surface 3.

Especially in 5 In addition, the maximum longitudinal extent L10 of the light-guiding element 10 is shown, wherein the light-guiding element 10 widens on the side facing the diffuser 4 from an initial width W4 at the tilted end face 15 over the radius R2 to the width W2.

• • Die Höhe H6 der Seitenwände 20 soll 75% von der Höhe H2 des Lichtleitelements 10 zwischen der Basisfläche 13 und der Kopffläche 14 betragen.
• • Der sich aus der Differenz der Höhe H6 von der Höhe H2 ergebende Spalt zwischen der Stirnseite 22 der Seitenwände 20 und der Kopffläche 14 ist derart gewählt, dass Licht in Breitenrichtung durch den Spalt dringen kann.
• • Der erste Radius R1 sollte 1/5 eines Vollkreises betragen, wobei der Mittelpunkt der Höhe H2 der Seitenwände 20 berücksichtigt werden kann.
• • Die Gerade 31 setzt den ersten Radius R1 bis zu der Stirnseite 22 der jeweiligen Seitenwand 20 fort.
• • Das Leuchtmittel 2 ist mit einer zu dem Lichtleitelement 10 gewandten Seite zwischen Einkoppelfläche 11 und Basisfläche 13 und somit um beispielsweise die Höhe H3 in ein zumindest abschnittsweise durch die Seitenwände 20 gebildetes Gehäuse hinein verschoben.
• • Die Länge L6 der Seitenwände 20 sollte 75% der Länge L7 der Lichtleitvorrichtung 1 in Längsrichtung betragen.
• • Die Gesamthöhe entsprechend der Summe der Höhe H5 des Diffusors 4 und der Höhe H1 von der Basisfläche 13 zu einer sichtseitigen Fläche einer in Höhenrichtung angrenzenden Abschlusswandung 43 ist vorzugsweise maximal 10 mm.
• • Die Winkel A1 und A2 sind vorzugsweise gleich und weiter vorzugsweise 135°.
• • Die Abschlusswandung 43, welche die Kopffläche 14 sichtsseitig vorzugsweise vollständig überdeckt, ist ausgebildet die Lichtverteilun in dem Lichtleitelement 10 zu maximieren und besitzt eine Länge L5 vorzugsweise 60% der Gesamtlänge L7, wobei ein Spalt, welcher sich durch den Höhenversatz der Auskoppelfläche 12 gegenüber der Kopffläche 14 ergibt, ausgebildet ist, ein Einspritzen eines Materials zur Herstellung der Abschlusswandung 43 zu erlauben.
• • Der zweite Radius R2 berücksichtigt vorzugsweise die Länge L11 und die Breite W1, welche der Einkoppelfläche 11 zugeordnet sind, als Referenz.

Furthermore, in particular the 3 to 5 Further advantageous height, width, and length ratios are shown, which can be realized by a single variant or various embodiments. Thus, the following can preferably be provided:

• • The height H6 of the side walls 20 should be 75% of the height H2 of the light guide element 10 between the base surface 13 and the head surface 14.
• • The gap resulting from the difference between the height H6 and the height H2 between the end face 22 of the side walls 20 and the head surface 14 is selected such that light can penetrate through the gap in the width direction.
• • The first radius R1 should be 1/5 of a full circle, taking into account the center point of the height H2 of the side walls 20.
• • The straight line 31 continues the first radius R1 up to the end face 22 of the respective side wall 20.
• • The illuminant 2 is displaced with a side facing the light-guiding element 10 between the coupling surface 11 and the base surface 13 and thus by, for example, the height H3 into a housing formed at least in sections by the side walls 20.
• • The length L6 of the side walls 20 should be 75% of the length L7 of the light guide device 1 in the longitudinal direction.
• • The total height corresponding to the sum of the height H5 of the diffuser 4 and the height H1 from the base surface 13 to a visible surface of an end wall 43 adjacent in the height direction is preferably a maximum of 10 mm.
• • The angles A1 and A2 are preferably equal and more preferably 135°.
• • The end wall 43, which preferably completely covers the head surface 14 on the visible side, is designed to maximize the light distribution in the light-guiding element 10 and has a length L5 preferably 60% of the total length L7, wherein a gap, which results from the height offset of the output surface 12 relative to the head surface 14, is designed to allow injection of a material for producing the end wall 43.
• • The second radius R2 preferably takes into account the length L11 and the width W1, which are assigned to the coupling surface 11, as a reference.

QUOTES CONTAINED IN THE DESCRIPTION

This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10 2023 127 543.7 [0003, 0007]

Claims (14)

Light-guiding device (1) for the homogeneous light distribution of a light that can be coupled in from a light source (2) onto a luminous surface (3), with a light-guiding element (10) with a rear-side coupling surface (11) corresponding to the light source (2) and a visible-side coupling-out surface (12) corresponding to the luminous surface (3) and spaced apart from the coupling surface (11) in a longitudinal direction (L), wherein the light-guiding element (10) is designed to guide light coupled in at the coupling surface (11) into the light-guiding element (10) along a coupling axis (E) in the longitudinal direction (L) and to couple it out at the coupling-out surface (12) toward the luminous surface (3) along an output axis (A) offset in the longitudinal direction (L) from the coupling axis (E), wherein the light-guiding device (1) further comprises two side walls (20) that are mutually offset with respect to a coupling surface (11) and the output surface (12) are axially symmetrically opposite one another and define a receiving space between them, enclosing the light-guiding element (10) in a width direction (B) orthogonal to the longitudinal direction (L), wherein a respective reflector surface (21) enclosing the side walls (20) to the light-guiding element (10) follows a predetermined longitudinal profile in the longitudinal direction (L), through which the receiving space widens from the input surface (11) along the longitudinal direction (L) to the output surface (12) in the width direction (B), and wherein the respective reflector surface (21) follows a predetermined height profile in a height direction (H) orthogonal to the longitudinal direction (L) and the width direction (B), through which the receiving space widens from a rear base surface (13) of the light-guiding element (10) along the height direction (H) to a visible head surface (14) of the light-guiding element (10) widens in the width direction (B). Light guide device according to Claim 1 , wherein the plane of symmetry (S) is spanned by the height direction (H) and the longitudinal direction (L) and is orthogonal to the width direction (B) and/or wherein the coupling-in surface (11) and the coupling-out surface (12) are axially symmetrical to the plane of symmetry (S) and/or wherein the light-guiding element (10) is axially symmetrical to the plane of symmetry (S). Light guide device according to Claim 1 or 2 , wherein the coupling surface (11) is offset in the height direction (H) relative to the base surface (13) in the direction of the head surface (14) and/or wherein the coupling surface (12) is offset in the height direction (H) relative to the head surface (14) in a direction facing away from the base surface (13). Light guide device according to one of the preceding claims, wherein the side walls (20) extend in the height direction (H) starting from the base surface (13) in the direction of the head surface (14). Light-guiding device according to one of the preceding claims, wherein a height (H6) of the side walls (20) and/or the reflector surfaces (21) of the side walls (20) starting from the base surface (13) corresponds to between 60% and 90%, in particular between 70% and 80% and further in particular 75% of a height (H2) of the light-guiding element (10) from the base surface (13) to the head surface (14), so that a gap (23) which is transparent to light in the width direction (B) remains between a visible end face (22) of the side walls (20) and the head surface (14). Light-guiding device according to the preceding claim, wherein the light-guiding element (10) extends in the width direction (B) through the gap (23) beyond the side walls (20) or terminates in the width direction (B) with the side walls (20). Light guide device according to one of the preceding claims, wherein the height profile of the reflector surfaces (21), starting from the base surface (13) of the light guide element (10) to the head surface (14) of the light guide element (10), follows in a first region a radius (R1) which widens the receiving space in the width direction (B), which radius merges without kinks into a straight line (31) which runs in a directly adjoining second region while maintaining the width of the receiving space. Light-guiding device according to the preceding claim, wherein the height profile determined by the radius (R1) corresponds to a quarter to a sixth, in particular a fifth, of a circle with a radius equal to the height (H6) of the side walls (20) and wherein the straight line (31) continues the height profile up to the visible end face (22) of the side wall (20). Light guide device according to one of the preceding claims, wherein the light guide element (10) is closed in the longitudinal direction (L) by two end faces (15, 16) which are opposite one another and tilted relative to the coupling axis (E), of which a first end face (15) is designed to direct the light coupled along the coupling axis (E) onto a predetermined light path (P) along the longitudinal axis (L), and of which a second end face (16) is designed to direct the light from the predetermined light path (P) onto the coupling-out axis (A). Light-guiding device according to one of the preceding claims, wherein the longitudinal course of the reflector surfaces (21), starting from a first end face (15) of the light-guiding element (20) on the coupling-in surface (11) to a second end face (16) of the light-guiding element (20) on the coupling-out surface (11), follows in a first region a radius (R2) which widens the receiving space in the width direction (B), which merges without kinks into a straight line (32) which runs in a directly adjoining second region while maintaining the width of the receiving space. Light-guiding device according to the preceding claim, wherein the longitudinal profile determined by the radius (R2) corresponds to a quarter to a sixth, in particular a fifth, of a circle with a radius equal to the length (L6) of the side walls (20) and wherein the straight line (32) continues the longitudinal profile up to the second end face (16) of the light-guiding element (10). Light-guiding device according to one of the two preceding claims, wherein a length of the side walls (20) and/or the reflector surfaces (21) of the side walls (20), starting from the first end face, corresponds to between 60% and 90%, in particular between 70% and 80% and further in particular 75% of a total length (L10) of the light-guiding element (10) from a terminal edge of the first end face (15) to a terminal edge of the second end face (16). Light-guiding device according to one of the preceding claims, further comprising end walls (6, 41, 42, 43) which completely enclose the light-guiding element (10) together with the side walls (20), leaving the coupling-in surface (11) and the coupling-out surface (12) free. Light-guiding device according to one of the preceding claims, further comprising a diffuser (4) arranged directly on the output surface (12) covering the light-guiding element (10) from a visible side, and/or further comprising the illuminant (2) arranged on the input surface (11) to form an air gap (5) such that light can be coupled into the input surface (11) by the illuminant (2) via the air gap (5).