Linear reflector

Abstract

The present invention relates to an elongated linear lighting device (1) having a light mixing chamber (2) that is delimited by first and second opposite longitudinal sides (3, 3') and by first and second opposite transverse sides (4, 4'). The elongated linear lighting device (1) also has a light source (5) arranged on the first longitudinal side (3) of the light mixing chamber (2) and configured to emit light towards the second longitudinal side (3') of 5 the light mixing chamber (2), where a direct light exit window (6) is arranged. The elongated linear lighting device (1) further has a linear reflector (7) with a longitudinal extension (X) in a direction parallel to an axis of elongation of the light mixing chamber (2), and a transversal extension (Y) in a direction perpendicular to the axis of elongation. The linear reflector (7) has two branches (8, 8'), each having a first reflector portion (7') with a first reflector surface 0 (13, 13') and a second reflector portion (7'') with a second reflector surface (14, 14'), which are connected at a vertex (9, 9'). The branches (8, 8') of the linear reflector (7) are arranged along the transverse sides (4, 4') of the light mixing chamber (2) such that the vertices (9, 9') are arranged in the light mixing chamber. The first and second reflector portions (7', 7'') of the linear reflector (7) are arranged at an angle relative to each other, the angle being larger 5 than 0 degrees and smaller than 180 degrees. The first reflector surface (13, 13') faces towards the first longitudinal side (3) of the light mixing chamber, and the second reflector surface (14, 14') faces towards the second longitudinal side (3') of the light mixing chamber.

Description

[0001] Linear reflector

[0002] FIELD OF THE INVENTION

[0003] The present invention generally relates to an elongated linear lighting device having an improved homogeneity of light emitted through the direct light exit window.

[0004] BACKGROUND OF THE INVENTION

[0005] The use of elongated linear lighting devices is continuing to attract attention. In particular, such lighting devices are advantageous in non-residential environments, such as offices, hospitals, schools, libraries or the like, due to its high efficacy and pleasant appearance.

[0006] Elongated linear lighting devices comprise a direct light exit window, z.e., a light exit window facing the user. Elongated linear lighting devices may additionally be provided with at least one indirect light exit window, z.e., a light exit window facing away from the user. In such a device, indirect light emitted through the indirect light exit window may be directed towards a surface to which the elongated linear lighting device is attached, such as a ceiling or a wall, thus improving the aesthetic appearance of the elongated linear lighting device.

[0007] However, a problem often perceived in relation with elongated lighting devices is inhomogeneous light distribution through the direct light exit window. In particular, the user may observe dark shades along the longitudinal edges of the direct light exit window.

[0008] One way of remedying such a problem is to add additional light sources in the light mixing chamber, such that the light sources are arranged close to the longitudinal edges of the direct light exit window. Such a solution suffers from a disadvantage of additional costs, given the fact that the light sources are expensive elements of a lighting device.

[0009] When the linear lighting device has an indirect light exit window, another problem arises, wherein the amount of light exiting through the indirect light exit window is rather low due to absorption and scattering of the light emitted by the light source.

[0010] Such a problem may also be addressed by addition of at least one light source emitting light in the direction of the indirect light exit window, thus depriving the elongated light emitting device of cost efficiency. Considering the above, there is a need to provide an elongated linear lighting device providing an improved homogeneity of the light emitted by the elongated linear lighting device, in particular through the direct light exit window, while being cost efficient.

[0011] SUMMARY OF THE INVENTION

[0012] It is an object of the present invention to at least partly overcome one or more of the aforementioned disadvantages.

[0013] To this end, the invention provides an elongated linear lighting device comprising a light mixing chamber having an axis of elongation, wherein the light mixing chamber is delimited by a first longitudinal side and a second longitudinal side being arranged opposite to each other.

[0014] The first longitudinal side and the second longitudinal side may be arranged substantially parallel to each other, or may deviate from such an arrangement, depending on the intended design of the elongated linear lighting device. The first longitudinal side may have a width being perpendicular to the axis of elongation, wherein such a width may be same as or different from the width of the second longitudinal side.

[0015] The light mixing chamber is further delimited by a first transverse side and a second transverse side being arranged opposite to each other. In other words, each of the first and the second transverse sides is connected to the first and the second longitudinal sides.

[0016] The first transversal side may have a width being perpendicular to the axis of elongation of the light mixing chamber, and also to the width of the first and the second longitudinal sides, wherein such a width may be same as or different from the width of the second transverse side. The widths of the first and the second transverse sides correspond to the distance between the first and the second longitudinal sides.

[0017] The length of the light mixing chamber along the axis of elongation may be in the range from 30 cm to 3 m.

[0018] The elongated linear lighting device according to the present invention further comprises a light source arranged on the first longitudinal side of the light mixing chamber and configured to, in operation, emit light in a direction towards the second longitudinal side of the light mixing chamber. The light source may be in the form of at least one row of light emitting diodes (LEDs). The light source according to the present invention may emit light having wavelength in the range from 250 nm to 800 nm. The light source may be an elongated LED filament. Such an elongated LED filament may have a plurality of LEDs arranged on an elongated carrier. In particular, the LEDs may be arranged in a single row along the elongated LED filament.

[0019] The elongated linear lighting device according to the present invention further comprises a direct light exit window arranged on the second longitudinal side of the light mixing chamber. The width of the direct light exit window may be substantially the same as the width of the second longitudinal side.

[0020] The elongated linear lighting device further comprises a linear reflector having a longitudinal extension in a direction parallel to the axis of elongation, and a transversal extension in a direction perpendicular to the axis of elongation. The longitudinal extension of the linear reflector is preferably the same as the extension of the light mixing chamber along the axis of elongation. The direction of the transversal extension of the linear reflector is parallel to the widths of the first and the second longitudinal sides. In other words, the transversal extension of the linear reflector is extension of the linear reflector into the light mixing chamber. The longer the transversal extension of the linear reflector, the farther the linear reflector extends into the light mixing chamber.

[0021] The linear reflector according to the present invention comprises two branches, each branch having a first reflector portion comprising a first reflector surface and a second reflector portion comprising a second reflector surface that are connected at a vertex. The branches of the linear reflector are arranged substantially along the transverse sides of the light mixing chamber such that the vertices are arranged in the light mixing chamber.

[0022] The first and second reflector surfaces are reflective in order to maximize the amount of light exiting through the direct light exit window, and also through the indirect light exit window, if such a window is present. In particular, the first and second reflector surfaces of the linear reflector may comprise white paint. The first and second reflector surfaces of the linear reflector will generate Lambertian scattering.

[0023] The vertices are arranged at a first distance M from the first longitudinal side and at a second distance M’ from the second longitudinal side. The first distance M may be the same as the second distance M’, but they may also be different. For example, the first distance M may be larger than the second distance M’. Changing the position of the vertices in relation to the first and the second longitudinal sides can impact the light output ratio and efficacy of the elongated linear lighting device. The first reflector portion and the second reflector portion of the linear reflector are arranged at an angle a relative each other, wherein the angle a is larger than 0 degrees and smaller than 180 degrees. For example, the angle a may be in a range from 30 degrees to 120 degrees.

[0024] The first reflector surface faces towards the first longitudinal side of the light mixing chamber, and the second reflector surface faces towards the second longitudinal side of the light mixing chamber.

[0025] The branches of the linear reflector may be mirror images of each other, i.e., the branches may be identical in shape and size. Alternatively, the branches may be different in size. The vertices of the branches of the linear reflector may be arranged at a distance from each other in the direction of the transversal extension of the linear reflector.

[0026] The linear reflector according to the present invention may have a hyperbolic cross-section in the transverse direction. The hyperbolic cross-section has two branches, each branch having a vertex. The branches may be mirror images of each other, i. e. , the branches may be identical in shape and size. Alternatively, the branches may be different in size. The vertices of the branches of the linear reflector may be arranged at a distance from each other in the direction of the transversal extension of the linear reflector. The linear reflector having a hyperbolic cross-section further comprises two intersecting asymptotes delimiting the branches. The asymptotes cross each other in a point of intersection arranged between the vertices of the branches. The angle between the asymptotes in the direction perpendicular to the axis of elongation of the light mixing chamber may be in a range from 10 degrees to 170 degrees.

[0027] The branches of the linear reflector of the present invention are arranged substantially along the transverse sides of the light mixing chamber such that the vertices are arranged in the light mixing chamber.

[0028] The elongated linear lighting device thus offers the advantage of a homogeneous light emitted through the direct light exit window, such that substantially no dark shades appear on the direct light exit window. Further, the elongated linear lighting device is cost efficient since no additional light sources are required in order to provide a homogeneous light.

[0029] The light mixing chamber may have a center line in a direction perpendicular to the axis of elongation. Each of the vertices of the branches of the linear reflector may be arranged offset from the center line. In other words, the vertices may be positioned closer to the second longitudinal side than to the first longitudinal side. The positions of the vertices relative to the center line of the mixing chamber determine the ratio between the light that is reflected towards the second longitudinal side (where the direct light exit window is arranged) and towards the first longitudinal side (where an indirect light exit window may be arranged).

[0030] The distance between the vertices of the branches of the linear reflector and the first longitudinal side of the light mixing chamber may be larger than the distance between the vertices of the branches of the linear reflector and the second longitudinal side of the light mixing chamber. In this case, the vertices are positioned closer to the second longitudinal side (where the direct light exit window is arranged) than to the first longitudinal side (where an indirect light exit window may be arranged).

[0031] The distance between the vertices of the branches of the linear reflector and the first longitudinal side of the light mixing chamber may also be smaller than the distance between the vertices of the branches of the linear reflector and the second longitudinal side of the light mixing chamber. In this case, the vertices are positioned closer to the first longitudinal side (where an indirect direct light exit window may be arranged) than to the second longitudinal side (where a direct light exit window is arranged).

[0032] The elongated linear lighting device may further comprise an indirect light exit window arranged on the first longitudinal side of the light mixing chamber adjacent to the light source. The indirect light exit window is thus facing in a direction being opposite to the direction of the direct light exit window. In particular, when the elongated linear lighting device is arranged on a surface, such as on a wall or a ceiling, the light emitted through the direct light exit window will be emitted away from the surface and towards the viewer, while the light emitted through the indirect light exit window will be emitted towards the surface and away from the viewer. The linear reflector may be configured to reflect at least a part of the light emitted from the light source through the indirect light exit window.

[0033] The distance between the vertices and the point of intersection of the asymptotes may be varied and depends on the desired effect. In other words, the distance the linear reflector extends into the light mixing chamber may be chosen such that the desired effect is achieved. For example, when an indirect light exit window is present, the width of such a window determines the distance between the vertices and the point of intersection. The wider the indirect light exit window, the further the branches of the linear reflector extend into the light mixing chamber. The light mixing chamber may further comprise an array of microlenses and / or a diffuser arranged on the second longitudinal side of the light mixing chamber.

[0034] The elongated linear lighting device may further comprise a controller configured to, in operation, control the light emitted from the light source.

[0035] The linear reflector may be removably attachable to the elongated linear lighting device. In particular, the linear reflector may be mounted to the transversal sides of the light mixing chamber by clicking the linear reflector into its intended position. This offers the advantage of simple mounting of the linear reflector since no tools are required.

[0036] The linear reflector may be an extruded profile, for example manufactured of plastic, in particular bio-based plastic, thus providing a sustainable element of the elongated linear lighting device. The linear lighting device may further be manufactured of metal and may be in the form of a bendable metal sheet. By the term “bendable” is understood as being able to amend the shape from straight to curved without breaking.

[0037] The elongated linear lighting device according to the present invention may have an efficacy that is at least 15 % larger as compared to the elongated linear lighting device of the prior art. The efficacy of the elongated linear lighting device according to the present invention may be at least 130 Im / W.

[0038] It is noted that the invention relates to all possible combinations of features recited in the claims. Further objectives of, features of, and advantages with, the present invention will become apparent when studying the following detailed disclosure, the drawings and the appended claims. Those skilled in the art will realize that different features of the present invention can be combined to create embodiments other than those described in the following. This and other aspects of the present invention will now be described in more detail, with reference to the appended drawings showing embodiment(s) of the invention.

[0039] BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Fig. 1 schematically shows a cross section of an elongated linear lighting device according to the present invention.

[0041] Fig. 2a schematically shows a perspective view of a linear reflector for use in an elongated linear lighting device according to the present invention.

[0042] Fig. 2b shows a cross-section of the linear reflector depicted in Figure la.

[0043] Figs 3a and 3b show an elongated linear lighting device according to the present invention. Figs 4a and 4b illustrate polar intensity diagrams for elongated linear lighting devices without and with the linear reflector, respectively.

[0044] Fig. 5 illustrates a polar intensity diagram for an elongated linear lighting device having a linear reflector with vertices that are positioned at 70 % of the distance from the first longitudinal side to the second longitudinal side.

[0045] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0046] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which currently preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness, and fully convey the scope of the invention to the skilled person.

[0047] Figure 1 shows a cross-section of the elongated linear lighting device 1 comprising a light mixing chamber 2 having an axis of elongation perpendicular to the plane of the cross-section.

[0048] The light mixing chamber 2 is delimited by a first longitudinal side 3 and a second longitudinal side 3’ being arranged opposite to each other. The first longitudinal side 3 and the second longitudinal side 3’ are arranged substantially parallel to each other. The first longitudinal side 3 has a width being perpendicular to the axis of elongation, wherein such a width is same as the width of the second longitudinal side 3’.

[0049] The light mixing chamber 2 is further delimited by a first transverse side 4 and a second transverse side 4’ being arranged opposite to each other. In other words, each of the first and the second transverse sides 4, 4’ is connected to the first and the second longitudinal sides 3, 3’.

[0050] The first transversal side 4 has a width being perpendicular to the axis of elongation of the light mixing chamber 2, and also to the width of the first and the second longitudinal sides 3, 3’, wherein such a width is same as the width of the second transverse side 4’. The widths of the first and the second transverse sides 4, 4’ correspond to the distance between the first and the second longitudinal sides 3, 3’.

[0051] The length of the light mixing chamber 2 along the axis of elongation may be in a range from 30 cm to 3 m. The elongated linear lighting device 1 further comprises a light source 5 arranged on the first longitudinal side 3 of the light mixing chamber 2 and configured to, in operation, emit light in a direction towards the second longitudinal side 3’ of the light mixing chamber 2. The light source 5 is in the form of one or more rows of light emitting diodes (LEDs). The light source 5 according to the present invention may emit light having a wavelength in a range from 250 nm to 800 nm.

[0052] The light source 5 may be an elongated LED filament. Such an elongated LED filament may have a plurality of LEDs arranged on an elongated carrier. In particular, the LEDs may be arranged in a single row along the elongated LED filament.

[0053] The elongated linear lighting device 1 further comprises a direct light exit window 6 arranged on the second longitudinal side 3’ of the light mixing chamber 2. The width of the direct light exit window 6 is substantially the same as the width of the second longitudinal side 3’.

[0054] The elongated linear lighting device 1 further comprises a linear reflector 7 having a longitudinal extension X in a direction parallel to the axis of elongation, and a transversal extension Y in a direction perpendicular to the axis of elongation.

[0055] The longitudinal extension X of the linear reflector 7 is preferably the same as the extension of the light mixing chamber 2 along the axis of elongation.

[0056] The direction of the transversal extension Y of the linear reflector 7 is parallel to the widths of the first and the second longitudinal sides 3, 3’. In other words, the transversal extension Y of the hyperbolic linear reflector 7 is an extension of the linear reflector 7 into the light mixing chamber 2. The longer the transversal extension Y of the linear reflector 7, the farther the linear reflector 7 extends into the light mixing chamber 2.

[0057] The linear reflector 7 is shown in greater detail in Figures 2a and 2b. The linear reflector 7 shown here has a hyperbolic cross-section in the transverse direction Y. The hyperbolic cross-section has two branches 8 and 8’, each having a vertex 9, 9’.

[0058] The branches 8, 8’ are mirror images of each other, i.e., the branches 8, 8’ are identical in shape and size.

[0059] The vertices 9, 9’ of the branches 8, 8’ of the linear reflector 7 are arranged at a distance L from each other in the direction of the transversal extension Y of the linear reflector 7.

[0060] The linear reflector 7 further comprises two intersecting asymptotes 10, 10’ delimiting the branches 8, 8’. The asymptotes 10, 10’ cross each other in a point of intersection 11 arranged between the vertices 9, 9’ of the branches 8, 8’. The angle between the asymptotes 10, 10’ in the direction perpendicular to the axis of elongation of the light mixing chamber 2 may be in a range from 10 degrees to 170 degrees.

[0061] The branches 8, 8’ of the linear reflector 7 are arranged substantially along the transverse sides 4, 4’ of the light mixing chamber 2 such that the vertices 9, 9’ are arranged in the light mixing chamber 2.

[0062] The elongated linear lighting device 1 offers the advantage of a homogeneous light emitted through the direct light exit window 6, such that substantially no dark shades appear on the direct light exit window 6. Further, the elongated linear lighting device 1 is cost efficient since no additional light sources are required in order to provide a homogeneous light.

[0063] As shown in Figure 1, the light mixing chamber 2 has a center line C in a direction perpendicular to the axis of elongation. In this case, each of the vertices 9, 9’ of the branches 8, 8’ of the linear reflector 7 are arranged offset from the center line C. In particular, the vertices 9, 9’ are positioned closer to the second longitudinal side 3’ than to the first longitudinal side 3.

[0064] In other examples, each of the vertices of the branches of the linear reflector may be positioned closer to the first longitudinal side than to the second longitudinal side, and they may also be arranged on the center line C.

[0065] The positions of the vertices 9, 9’ relative to the center line C of the mixing chamber 2 determine the ratio of light that is reflected towards the second longitudinal side 3’ and light that is directed towards the first longitudinal side 3.

[0066] In Figure 1, the first distance M between the vertices 9, 9’ of the branches 8, 8’ of the linear reflector 7 and the first longitudinal side 3 of the light mixing chamber 2 is larger than the second distance M’ between the vertices 9, 9’ of the branches 8, 8’ of the linear reflector 7 and the second longitudinal side 3’ of the light mixing chamber 2. In other words, the vertices 9, 9’ are arranged closer to the second longitudinal side 3’ than to the first longitudinal side 3.

[0067] The elongated linear lighting device 1 shown in Figure 1 further comprises an indirect light exit window 12 arranged on the first longitudinal side 3 of the light mixing chamber adjacent to the light source 5.

[0068] The indirect light exit window 12 is thus facing in a direction being opposite to the direction in which the direct light exit window 6 is facing. In particular, when the elongated liner lighting device 1 is arranged on a surface, such as on a wall or a ceiling, the light emitted through the direct light exit window 6 will be emitted away from the surface and towards the viewer, while the light emitted through the indirect light exit window 12 will be emitted towards the surface and away from the viewer. The linear reflector 7 may be configured to reflect at least a part of the light emitted from the light source 5 through the indirect light exit window 12.

[0069] The distance the linear reflector 7 extends into the light mixing chamber 2 may be varied and depends on the desired effect. When the linear reflector 7 is a hyperbolic linear reflector, the distance between the vertices 9, 9’ and the point of intersection 11 of the asymptotes 10, 10’ may be chosen such that a desired effect is achieved.

[0070] For example, when an indirect light exit window 12 is present, there may be a relation between the width of the indirect light exit window 12 and the distance the linear reflector 7 should extend into the light mixing chamber 2. For example, the wider the indirect light exit window 12, the further the branches 8, 8’ of the linear reflector 7 extend into the light mixing chamber 2.

[0071] The linear reflector 7 may be removably attachable to the elongated linear lighting device 1. In particular, the linear reflector 7 may be mounted to the transversal sides 4, 4’ of the light mixing chamber 2 by clicking the linear reflector 7 into its intended position. This offers the advantage of simple mounting of the linear reflector 7 since no tools are required.

[0072] Figures 3a and 3b illustrate perspective views of the elongated linear lighting device 1.

[0073] An elongated linear lighting device according to the present invention was compared to a conventional elongated linear lighting device having no linear reflector. The used equipment was a goniophotometer unit with a system photometer head, GO-V-1900. The two devices were compared under the same electrical conductions (input voltage of 230 V, power consumption of 41.9 W).

[0074] The results are summarized in Table 1 below. Table 1: Comparison of elongated linear lighting devices with and without a linear reflector.

[0075] In Table 1, FWHM denotes the full width at half maximum of the emitted light beam, expressed in degrees, and it is essentially a measure for the beam angle. The parameter UGR denotes the so-called unified glare rating, which is a measure of the glare in a given environment, adopted by the International Commission on Illumination (CIE).

[0076] From Table 1 it is clear that the devices with and without a linear reflector have a similar performance as to beam angle (FWHM) and glare (UGR), while the device with the linear reflector provides a significant improvement in efficacy. The efficacy of the elongated linear lighting device with a linear reflector is about 15 % higher than that of the comparative device without a linear reflector.

[0077] Finally, the polar intensity diagrams (Figures 4a and 4b) showed a difference in the direct and indirect light ratio. The comparative device had a ratio of 88 % vs. 12 %, while the inventive device had only 92 % vs. 8 %.

[0078] The results of a further comparison of elongated linear lighting devices with and without a linear reflector are shown below in Table 2.

[0079] Table 2: Comparison of elongated linear lighting devices with and without a linear reflector.

[0080] In Table 2, LOR denotes the light output ratio, being the percentage of light emitted from the light source that makes it out of the lighting device. The results show that the linear reflector increased the LOR by 6 % both for the case with an indirect light exit window and for the case without an indirect light exit window.

[0081] For a device that has both a direct light exit window and an indirect light exit window, Table 2 also contains the ratio of light emitted through the direct light exit window and light emitting through the indirect light exit window. When the device does not have a linear reflector, this ratio is 84 (direct) versus 16 (indirect). When the device has a linear reflector, the ratio changes to 80 (direct) versus 20 (indirect). In the latter situation, the linear reflector is arranged such that its vertices are positioned at 70 % of the distance from the first longitudinal side (where the indirect light exit window is arranged) to the second longitudinal side (where the direct light exit window is arranged).

[0082] Changing the position of the vertices in the elongated linear lighting device may impact the LOR and efficacy of the luminaire.

[0083] The dependence of optical parameters on the position of the vertices is presented below in Table 3.

[0084] For various positions of the vertices, Table 3 contains values for the LOR and for the ratio of light emitted towards the second longitudinal side (where the direct light exit window is arranged) and towards the first longitudinal side (where an indirect light exit window may be positioned). These values are obtained from optical simulations.

[0085] The position of the vertices is expressed as a ratio of the first distance M from the first longitudinal side and the full separation between the first and second longitudinal sides. In other words, when the position of the vertices is 0.5, the vertices are positioned at 50 % of the distance from the first longitudinal side to the second longitudinal side (or, halfway between the first and second longitudinal sides).

[0086] Table 3: Dependence of optical parameters on the position of the vertices.

[0087] From Table 3 it is clear that when the vertices are positioned halfway between the first and second longitudinal sides (position 0.5), the ratio of the amount of light that is emitted towards the second longitudinal side (where the direct light exit window is arranged) and the amount of light that is emitted towards the first longitudinal side (where an indirect light exit window may be positioned) is 5.25. In other words, the amount of light that is emitted towards the second longitudinal side (where the direct light exit window is arranged) is more than five times higher than the amount of light that is emitted towards the first longitudinal side (where an indirect light exit window may be positioned).

[0088] When instead the vertices would be positioned closer to the second longitudinal side (where the direct light exit window is arranged), this ratio decreases. For example, when the vertices are positioned at 70 % of the distance from the first longitudinal side to the second longitudinal side (position 0.7), the ratio of the amount of light that is emitted towards the second longitudinal side (where the direct light exit window is arranged) and the amount of light that is emitted towards the first longitudinal side (where an indirect light exit window may be positioned) is 4.

[0089] When the vertices would be positioned closer to the first longitudinal side (where an indirect light exit window may be arranged), the ratio increases. For example, when the vertices are positioned at 30 % of the distance from the first longitudinal side to the second longitudinal side (position 0.3), the ratio of the amount of light that is emitted towards the second longitudinal side (where the direct light exit window is arranged) and the amount of light that is emitted towards the first longitudinal side (where an indirect light exit window may be positioned) is 7.33.

[0090] An optical simulation of the elongated linear lighting device wherein the vertices are positioned at 70 % of the distance from the first longitudinal side to the second longitudinal side (position 0.7), corresponding to a ratio of direct vs. indirect light of 80 vs. 20, resulted in the polar intensity diagram shown in Figure 5.

[0091] Although the present invention has been described with reference to various embodiments, those skilled in the art will recognize that changes may be made without departing from the scope of the invention. It is intended that the detailed description be regarded as illustrative and that the appended claims including all the equivalents are intended to define the scope of the invention.

Claims

CLAIMS:

1. An elongated linear lighting device (1) comprising a light mixing chamber (2) having an axis of elongation, the light mixing chamber being delimited by a first longitudinal side (3) and a second longitudinal side (3’) being arranged opposite to each other, the light mixing chamber (2) further being delimited by a first transverse side (4) and a second transverse side (4’) being arranged opposite to each other, wherein the elongated linear lighting device (1) further comprises: a light source (5) comprising one or more rows of light emitting diodes, the light source (5) being arranged on the first longitudinal side (3) of the light mixing chamber (2) and configured to, in operation, emit light in a direction towards the second longitudinal side (3’) of the light mixing chamber (2), a direct light exit window (6) arranged on the second longitudinal side (3’) of the light mixing chamber (2), and a linear reflector (7) having a longitudinal extension in a direction parallel to the axis of elongation, and a transversal extension in a direction perpendicular to the axis of elongation, wherein the linear reflector (7) comprises two branches (8, 8’), each branch (8, 8’) having a first reflector portion (7’) comprising a first reflector surface (13, 13’) and a second reflector portion (7”) comprising a second reflector surface (14, 14’) that are connected at a vertex (9, 9’), and wherein the branches (8, 8’) of the linear reflector (7) are arranged substantially along the transverse sides (4, 4’) of the light mixing chamber (2) such that the vertices (9, 9’) are arranged in the light mixing chamber (2), and wherein the first reflector portion (7’) and the second reflector portion (7”) of the linear reflector (7) are arranged at an angle relative to each other, the angle being larger than 0 degrees and smaller than 180 degrees, and wherein the first reflector surface (13, 13’) faces towards the first longitudinal side (3) of the light mixing chamber, and the second reflector surface (14, 14’) faces towards the second longitudinal side (3’) of the light mixing chamber.

2. The elongated linear lighting device (1) according to claim 1, wherein in a direction perpendicular to the axis of elongation, the light mixing chamber has a center line, and wherein each of the vertices (9, 9’) of the branches (8, 8’) of the linear reflector (7) is arranged offset from the center line.

3. The elongated linear lighting device (1) according to claim 2, wherein the vertices (9, 9’) are arranged at a first distance from the first longitudinal side (3) and at a second distance from the second longitudinal side (3’), and wherein the first distance is larger than the second distance.

4. The elongated linear lighting device (1) according to any one of the preceding claims, further comprising an indirect light exit window (12) arranged on the first longitudinal side (3) of the light mixing chamber (2) adjacent to the light source (5).

5. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is configured to reflect at least a part of the light emitted from the light source (5) through the indirect light exit window (12).

6. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the first and second reflector surfaces (13, 13’, 14, 14’) of the linear reflector (7) comprise white paint.

7. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the light mixing chamber (2) further comprises an array of microlenses and / or a diffuser arranged on the second longitudinal side (3’) of the light mixing chamber (2).

8. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the elongated linear lighting device (1) further comprises a controller configured to, in operation, control the light emitted from the light source (5).

9. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is removably attachable to the elongated linear lighting device (1).

10. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is an extruded profile.

11. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is manufactured from one or more of a metal and a plastic.

12. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the light source (5) is an elongated LED filament.

13. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the length of the light mixing chamber (2) along the axis of elongation is in the range from 30 cm to 3 m.

14. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is a hyperbolic linear reflector having a hyperbolic cross-section in the transverse direction, and two intersecting asymptotes (10, 10’) delimiting the branches (8, 8’).

15. The elongated linear lighting device (1) according to any one of the preceding claims, wherein the linear reflector (7) is bendable.

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