Light guiding device

Abstract

The invention relates to a light guiding device (1) for the homogeneous light distribution of light to an illumination surface, wherein the light can be coupled in from an illuminating means (2) at a coupling-in surface, said light guiding device having two side walls (20) which define a receiving space therebetween which terminates a light guiding element (10) in a width direction (B) orthogonal to a longitudinal direction (L), wherein a respective reflector surface (21) which terminates the side walls (20) with respect to the light guiding element (10) in the longitudinal direction follows a respective predetermined longitudinal profile along which the receiving space widens in the width direction (B) from the coupling-in surface (11) in the longitudinal direction towards a coupling-out surface (12), 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), along which height profile the receiving space widens in the width direction (B) from a rear-side base surface (13) of the light guiding element (10) in the height direction (H) towards a visible-side top surface (14) of the light guiding element (10), such that coupled-in light is homogenised by reflection at the side wall from the coupling-in surface to the coupling-out surface.

Description

[0001] Light guide device

[0002] Description:

[0003] The invention relates to a light guiding device for homogeneous light distribution or for homogenizing light that can be coupled from a light source onto a luminous surface.

[0004] In principle, light guiding devices and light guiding devices usable for homogenizing light are known in the prior art. However, it is advantageous to achieve light homogenization in the smallest possible space and to homogenize as much of the coupled light as possible, so that the illuminating surface is illuminated as completely, uniformly, and well as possible with as little coupled light as possible, and in particular, no individual light points corresponding to the light source are visible on the illuminating surface. This is described, for example, in DE 10 2023 127 543.7, the teaching of which is hereby fully incorporated into the disclosure of the present application, a fairing element for vehicles is known in which rear-coupled light is guided along a predetermined light path via a light guide element having tilted reflective surfaces from a rear-side light source to a front-side light surface and is simultaneously homogenized along the light path.

[0005] However, this homogenization can be further optimized to achieve a smaller required installation space for homogenization and a greater light yield or greater efficiency in homogenization.

[0006] The invention is therefore based on the objective of overcoming the aforementioned disadvantages and providing a light guiding device by which light coupled in from a light source can be homogenized efficiently and in a small installation space to illuminate a luminous surface.

[0007] This problem is solved by the combination of features according to claim 1.

[0008] 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 coupling surface corresponding to the light source and a front coupling surface corresponding to the luminous surface, which is spaced longitudinally along a longitudinal axis from the coupling surface. The light-guiding element is preferably designed identically to the light-guiding element according to DE 10 2023 127 543.7, wherein the light-guiding device proposed here can be integrated into a cladding element proposed by DE 10 2023 127 543.7.The light guiding element proposed here is designed, according to the invention, to guide light coupled into the light guiding element along a coupling axis at the coupling surface in a longitudinal direction and to couple it out at the coupling surface along a coupling axis offset longitudinally from the coupling axis towards the illuminating surface, so that the light from the coupling surface to the coupling surface follows a predetermined light path along which the light is homogenized, i.e., the illuminating surface is evenly illuminated. However, stray light can occur during the incident or coupling of the light, so that the stray light does not follow the light path directly and contributes little or nothing to the illumination of the illuminating surface. To minimize stray light, or rather,Scattered light deflection onto the light path is provided in the present design by the fact that the light guiding device further comprises two side walls which are axially symmetrical to each other with respect to a plane of symmetry dividing the coupling surface and the coupling surface, and which define a receiving space between them that limits or encloses the light guiding element in a lateral direction orthogonal to the longitudinal direction along a transverse axis. The light guiding element is thus limited in the lateral direction orthogonal to the longitudinal direction by the side walls and rests directly against them. For this purpose, a reflector or reflective surface is provided on each of the side walls facing the plane of symmetry or the light guiding element, which is specifically designed to reflect light or scattered light incident on the light guiding element. The side walls follow the respective inner surface facing the light guiding element on their respective inner sides.The reflector surfaces terminating the side walls of the light-guiding element are defined by a predetermined longitudinal profile and a predetermined vertical profile along a vertical axis, orthogonal to both the longitudinal and lateral directions. According to the invention, the receiving space defined by the reflector surfaces widens symmetrically in the lateral direction from the coupling surface or an end face of the light-guiding device associated with the coupling surface along the longitudinal direction to the coupling surface or to an opposite end face of the light-guiding device associated with the coupling surface. Furthermore, the receiving space defined by the reflector surfaces widens vertically from a rear base surface of the light-guiding element along the vertical direction to a front surface.The top surface of the light-guiding element, facing the viewing side, widens particularly symmetrically in the width direction. This results in the recording space having an essentially U-shaped basic form in both a cross-section orthogonal to the longitudinal direction and a longitudinal section orthogonal to the vertical direction.

[0009] Due to the predetermined longitudinal and vertical profile of the inner surface of the side walls or reflective surfaces, scattered light projected onto them in a lateral direction can be directed back onto the light path or to the output coupling axis and onto the illuminating surface in a predetermined manner, so that the scattered light also contributes to the homogeneous illumination of the illuminating surface.

[0010] 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 guide element, through which the light guide device and a product possibly encompassing the light guide device can be stabilized.

[0011] For clarification, it should be noted that the longitudinal, transverse, and vertical axes, and their corresponding longitudinal, latitude, and height directions, are each orthogonal to one another and define a spatial Cartesian coordinate system. An advantageous variant of the light guide device provides that the plane of symmetry is defined by the height and longitudinal directions and is orthogonal to the latitude direction. The input and output surfaces can be axially or mirror-symmetrical with respect to the plane of symmetry. Furthermore, the light guide element itself can also be axially or mirror-symmetrical with respect to the plane of symmetry.

[0012] The coupling surface is preferably offset vertically relative to the base surface in the direction of the top surface, so that the light guide element has a recess, preferably at its end face, relative to the base surface, where the coupling surface is located. Furthermore, the coupling surface can be offset vertically relative to the top surface in a direction away from the base surface, so that the light guide element has a projection on the top surface where the coupling surface is located.

[0013] The side walls extend vertically from the base towards the top surface, but do not necessarily reach it.

[0014] A particularly advantageous variant is one in which the height of the side walls and / or the reflector surfaces of the side walls, measured from the base surface, corresponds to between 60% and 90%, in particular between 70% and 80%, and further, in particular 75%, of the height of the light-guiding element from the base surface to the top surface, so that a translucent gap remains between a viewing-side end face of the side walls or an end face of the reflector surfaces facing the viewing side and the top surface, through which stray light can pass and / or be coupled out, so that this stray light does not lead to an adverse illumination of the illuminated surface.

[0015] Preferably, the light guiding element extends in the width direction through the gap beyond the side walls or terminates in the width direction with the side walls or an outer surface of the side walls.

[0016] Preferably, the height profile of the reflector surfaces, starting from the base surface of the light guide element and extending to the top surface, follows a (first) radius that widens the recording space in the width direction in a first region. This radius transitions smoothly into a (first) straight line, which maintains the width of the recording space in an immediately adjoining second region. The (first) straight line thus preferably runs parallel to the plane of symmetry and transitions into the (first) radius as a tangent to a circle that defines the (first) radius.

[0017] The height profile determined by the (first) radius preferably corresponds to one-quarter to one-sixth, and in particular one-fifth, of a circle with a radius equal to the height of the side walls. The (first) straight line continues the height profile to the visible end face of the side wall, whereby a chamfer or transition can be provided at the end face of the (first) straight line, via which the reflective surface or the height profile transitions into the end face of the respective side wall.

[0018] The light-guiding element is preferably terminated longitudinally by two opposing and preferably parallel end faces, which are tilted relative to the coupling axis and can also be referred to as reflective surfaces or reflector surfaces. Of the two end faces, a first end face is designed to direct the light coupled in along the coupling axis onto a predetermined light path along the longitudinal axis. The second end face is further designed to direct the light from the predetermined light path onto the output coupling axis.

[0019] Furthermore, and preferably, the longitudinal profile of the reflector surfaces, starting from one end face of the light guide element at the coupling surface and extending to the second end face of the light guide element at the coupling surface, follows a (second) radius in a first region that widens the receiving space in the width direction. This radius transitions smoothly into a (second) straight line, which maintains the width of the receiving space in an immediately adjoining second region. This (second) straight line also preferably runs parallel to the plane of symmetry and transitions into the (second) radius as a tangent to a circle that defines the (second) radius.

[0020] The longitudinal profile determined by the (second) radius preferably corresponds to one quarter to one sixth, and in particular one fifth, of a circle with a radius equal to the length of the side walls. The (second) straight line extends the longitudinal profile to the second end face of the light-guiding element.

[0021] Preferably, the 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 the total length of the light guiding element from a termination edge of the first end face to a termination edge of the second end face.

[0022] Furthermore, according to an advantageous embodiment, the light guiding device also has end walls which, together with the side walls, completely enclose the light guiding element, leaving the coupling surface and the coupling surface free, and accordingly form a housing surrounding the light guiding element with the side walls, whereby the coupling surface and the coupling surface remain free of this, so that light can be coupled in at the coupling surface and light can be coupled out at the coupling surface.

[0023] In addition, the light guiding device preferably has a diffuser which is arranged directly on the output surface, covering the light guiding element from one side and preferably forming the luminous surface on its side, so that the light guiding element is not visible through the diffuser.

[0024] Additionally or alternatively, the light guide device can also include the light source, which is arranged at the coupling surface forming an air gap, so that light can be coupled into the coupling surface via the air gap through the light source.

[0025] The features disclosed above can be combined in any way, provided that this is technically possible and they do not contradict each other.

[0026] Other advantageous embodiments of the invention are characterized in the dependent claims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. The figures show:

[0027] Fig. 1 shows a perspective view of a decorative part with an integrated light guide device;

[0028] Fig. 2 perspective longitudinal section along the plane of symmetry through the light guiding device;

[0029] Fig. 3 Longitudinal section along the plane of symmetry through the light guiding device;

[0030] Fig. 4 shows a cross-section through the light guide device orthogonal to the longitudinal axis;

[0031] Fig. 5 shows a longitudinal section through the light guide device orthogonal to the vertical axis.

[0032] The figures are schematic examples and show different views of a single design variant, so that identical reference symbols in the figures indicate the same functional and / or structural features. However, the different figures can also show views of different design variants, allowing them to be considered in isolation.

[0033] Figure 1 shows a trim element or functional assembly with an integrated light guide 1, which is intended to illuminate a spatially limited illuminated area 3 on the visible side facing upwards in the illustration. For this purpose, the light guide 10 and side walls 20 are incorporated into the decorative part or functional element, the latter being covered on the visible side by the diffuser 4.

[0034] Although only one light guide device 1 is shown in the cladding element, a multitude of such light guide devices 1 can be arranged adjacent to one another in the lateral direction B or along the associated transverse axis and can also be connected to one another by their light guide elements 10. Immediately adjacent side walls 20 of immediately adjacent light guide devices 1 can also be integrally formed with one another. This also applies to the diffusers and end walls of such light guide devices 1.

[0035] A basic structure of the light guide device 1 is shown in Figure 2, which depicts a section through the light guide device 1 along the plane of symmetry S, which will be explained later. Light from a light source 2, for example an LED, can be coupled into the light guide element 10 at an input surface 11 along an input axis E. The light is deflected at a first tilted reflective or end surface 15 of the light guide element 10 onto the predetermined light path P, along which the light is selectively scattered within the light guide element 10 for homogenization and directed onto a second reflective or end surface 16 opposite in the longitudinal direction L. At this second reflective or end surface 16, the light is directed along the output coupling axis A to the output coupling surface 12, so that the light is coupled into the diffuser 4 at the output coupling surface 12 and homogeneously illuminates the illuminating area 3, which is spatially limited, for example, to 20 mm x 3 mm.

[0036] The light guide element 10 and the light source 2 are further 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 chosen such that the light emitted by the light source 2 is distributed essentially over the entire surface of the coupling surface 11.

[0037] Furthermore, the coupling surface 11 is offset vertically relative to a base surface 13 facing the rear of the light guide element 10, in the direction of a head surface 14 facing the front, so that a recess is formed on the first end surface 15. The coupling surface 12 is provided on a projection opposite the head surface 14 and is also offset vertically relative to the head surface 14. Both the recess and the projection, or the respective vertical 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 blocked or filtered at the coupling surface 12.

[0038] Figure 2 also advantageously shows that the light guiding element 10 is enclosed not only by the side walls 20, but also on the rear side by a closing wall 6 designed as a base plate with a thickness or height H4, on the visible side by a closing wall 43 extending in the gap defined by the projection, and on the end faces by respective closing walls 41, 42, wherein the side walls 20 are in particular formed integrally with the closing walls 41, 42, 43 and can, for example, be manufactured together by injection molding.

[0039] Reflective surfaces can be formed or provided through the end walls 6, 41, 42, 43 as well as through the side walls 20 towards the light guiding element 10, whereby these are formed as the reflector surfaces 21 on the side walls 20.

[0040] 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 directed towards the light guiding element 10 are axially or mirror-symmetrically opposite each other with respect to the plane of symmetry S and define a receiving space between them which closes off the light guiding element 10 in a width direction B orthogonal to the longitudinal direction L.

[0041] The reflector surfaces 21 follow a predetermined longitudinal profile in the longitudinal direction L, which is axially or mirror-symmetrically symmetrical to each other with respect to the plane of symmetry S, and a predetermined vertical profile in the vertical direction H, which is orthogonal to the longitudinal direction L and the horizontal direction B, which is axially or mirror-symmetrically symmetrical to each other with respect to the plane of symmetry S.

[0042] Due to the longitudinal direction, 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 can be seen in particular in Figure 5.

[0043] Due to the vertical profile, the recording space widens from the rear base surface 13 of the light guide element 10 along the vertical direction H to the front head surface 14 of the light guide element 10 in the horizontal direction B, as can be seen particularly in Figure 4. As also shown in Figures 4 and 5, it is particularly advantageous for both the longitudinal and vertical profiles that they each have two regions, wherein the respective profile in a first region is formed by a partial circle defined by a radius R1, R2, through which the recording space widens in the horizontal direction B and which transitions into a straight line 31, 32 tangential to the partial circle, which extends parallel to the plane of symmetry S while maintaining the same width.The tangential straight line 32 with respect to the longitudinal course has, as shown in Figure 5, an exemplary length L9 and a width W2, through which the light falling on the tilted front surface 16 can be homogenized onto the R light and directed evenly onto the luminous surface 3.

[0044] Figure 4 also shows another particularly advantageous feature. The illustrated variant provides that the side walls 20 extend from the base surface 13 towards the head surface 14, but have a height H6 of only 75% of the height H2 of the light guide element 10 between the base surface 13 and the head surface 14, so that a gap 23 is created between the end face 22 of the side walls 20 and the head surface 14, through which unusable stray light from the receiving space or the light guide element 10 can be coupled out and thus does not lead to faulty, i.e., inhomogeneous, illumination of the illuminating surface 3.

[0045] In particular, Figure 5 shows the maximum longitudinal extent L10 of the light guide element 10, wherein the light guide element 10 widens from an initial width W4 on the side facing the diffuser 4 to the width W2 over the radius R2 at the tilted end face 15.

[0046] Furthermore, Figures 3 to 5 illustrate additional advantageous height, width, and length ratios, which can be achieved through a single variant or various embodiments. For example, the following may preferably be provided:

[0047] • The height H6 of the side walls 20 shall be 75% of the height H2 of the light guiding element 10 between the base surface 13 and the head surface 14.

[0048] • The gap between the front face 22 of the side walls 20 and the head surface 14 resulting from the difference between the height H6 and the height H2 is chosen such that light can penetrate through the gap in the lateral direction.

[0049] • The first radius R1 should be 1 / 5 of a full circle, taking into account the midpoint of the height H2 of the side walls 20.

[0050] • The straight line 31 continues the first radius R1 to the end face 22 of the respective side wall 20.

[0051] • The light source 2 is positioned with one side facing the light guide element 10 between coupling surface 11 and base surface 13 and thus shifted, for example, by the height H3 into a housing formed at least partially by the side walls 20.

[0052] • 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.

[0053] • 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 adjacent end wall 43 in the vertical direction is preferably a maximum of 10 mm.

[0054] • The angles A1 and A2 are preferably equal and further preferably 135°.

[0055] • 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 coupling surface 12 to the head surface 14, is formed to allow the injection of a material for the production of the end wall 43.

[0056] • 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.

Claims

Patent claims 1. Light guiding device (1) for the homogeneous distribution of light coupled from a light source (2) onto a luminous surface (3), with a light guiding element (10) with a (2) corresponding rear coupling surface (11) and a front coupling surface (12) corresponding to the illuminating surface (3), which is spaced apart in a longitudinal direction (L) from the coupling surface (11), wherein the light guiding element (10) is configured to guide light coupled into the light guiding element (10) at the coupling surface (11) along a coupling axis (E) in a longitudinal direction (L) and to couple out at the coupling surface (12) along a coupling axis (A) offset in a longitudinal direction (L) to the illuminating surface (3), wherein the light guiding device (1) further comprises two side walls (20) which are axially symmetric to each other with respect to a plane of symmetry (S) dividing the coupling surface (11) and the coupling surface (12) and which separate the light guiding element (10) in a longitudinal direction (L) (L) determine the orthogonal width direction (B) define the final recording space,wherein a respective reflector surface (21) ) terminating the side walls (20) to the light guiding element (10) follows a predetermined longitudinal profile in the longitudinal direction (L), by which the receiving space widens from the input surface (11) along the longitudinal direction (L) to the output surface (12) in the lateral direction (B), and wherein the respective reflector surface (21) follows a predetermined vertical profile in a vertical direction (H) orthogonal to the longitudinal direction (L) and the lateral direction (B), by which the receiving space widens from a rear base surface (13) of the, The light guiding element (10) widens along the vertical direction (H) towards a view-side head surface (14) of the light guiding element (10) in the horizontal direction (B).

2. Light guiding device according to claim 1, wherein the plane of symmetry (S) is spanned by the vertical direction (H) and the longitudinal direction (L) and is orthogonal to the horizontal direction (B) and / or wherein the coupling surface (11) and the coupling surface (12) are axially symmetric to the plane of symmetry (S) and / or wherein the light guiding element (10) is axially symmetric to the plane of symmetry (S).

3. Light guiding device according to claim 1 or 2, wherein the coupling surface (11 ) is offset in the vertical 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 vertical direction (H) relative to the head surface (14) in a direction away from the base surface (13).

4. Light guiding device according to one of the preceding claims, wherein the side walls (20) extend in the vertical direction (H) from the base surface (13) towards the head surface (14).

5. 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 translucent in the width direction (B) remains between a visible end face (22) of the side walls (20) and the head surface (14).

6. 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).

7. Light guiding 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 guiding element (10) to the head surface (14) of the light guiding element (10) in a first area follows a radius (R1 ) widening the receiving space in the width direction (B), which transitions without kinks into a straight line (31 ) which maintains the width of the receiving space in an immediately adjoining second area.

8. Light guiding device according to the preceding claim, wherein the height profile determined by the radius (R1 ) corresponds to one quarter to one sixth, in particular one 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 to the viewable end face (22) of the side wall (20).

9. Light guiding device according to one of the preceding claims, wherein the light guiding element (10) is closed in the longitudinal direction (L) by two opposing end faces (15, 16) tilted relative to the coupling axis (E), of which a first end face (15) is formed which the- to direct 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 formed to direct the light from the predetermined light path (P) onto the coupling axis (A).

10. 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) at the coupling surface (11 ) to a second end face (16) of the light guiding element (20) at the coupling surface (11 ) follows in a first area a radius (R2) widening the receiving space in the width direction (B), which transitions without kinks into a straight line (32) which in an immediately adjoining second area maintains the width of the receiving space.

11. Light guiding device according to the preceding claim, wherein the longitudinal profile determined by the radius (R2) corresponds to one quarter to one sixth, in particular one 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 to the second end face (16) of the light guiding element (10).

12. 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 termination edge of the first end face (15) to a termination edge of the second end face (16).

13. 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 surface (11) and the coupling surface (12) free.

14. Light guiding device according to one of the preceding claims, further comprising a diffuser (4) which is arranged directly on the output surface (12) covering the light guiding element (10) from one side, and / or further comprising the light source (2) which is located under Formation of an air gap (5) at the coupling surface (11) is arranged so that light can be coupled into the coupling surface (11) via the air gap (5) through the light source (2).

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