Optical elements for illumination systems that enhance brightness uniformity

Abstract

The present invention relates to an elongated optical element (1) for an illumination system (100), having a longitudinal extension and a lateral extension that is substantially perpendicular to the longitudinal extension. The optical element (1) has a central portion (2) having a first edge (2') and a second edge (2'') that are arranged substantially parallel to each other and to the longitudinal extension of the optical element (1). The optical element (1) further includes at least a first light guide (3) that is arranged on the first edge (2') of the central portion (2), and the optical element (1) has a first surface (4) that faces at least one light source (112) of the illumination system (100) and a second surface (4') opposite the first surface (4). The first surface (4) of the first light guide (3) includes at least one longitudinal jug (5) that is substantially parallel to the longitudinal extension of the optical element (1).

Description

[Technical Field]

[0001] The present invention relates to an optical element for an illumination system, to an illumination system including such an optical element, and to an illumination device including such an illumination system. [Background technology]

[0002] Office lighting fixtures have strongly conflicting requirements. In particular, office compliance lighting fixtures must have a limited luminous intensity distribution of UGR≦19.0 and low diffusion at angles of 65 degrees or more (L65≦3000 cd / m 2 On the other hand, customers prefer office lighting fixtures with maximum luminance uniformity, which means that the cover should be as diffusive as possible.

[0003] All these above-mentioned requirements can be met by currently available optical systems consisting of an MLO cover and a diffusing foil (e.g., FlexBlend MLO) or a diffusing reflector (e.g., SmartBalance). However, such solutions are costly (expensive MLOs cut from sheets have to be fixed using additional elements) and have low efficiency (e.g., FlexBlend MLO - LOR=65%), especially in luminaires with small exit windows.

[0004] There are more cost-effective luminaires, such as KeyLine PCS or FlexBlend PCS, in which a PCS cover, a hexagonal structure with a sphere radius of 2.3 mm, is used together with a lens inside the luminaire. Both the cover and the lens are molded, thus making them cost-effective and easy to assemble. Such optical systems are efficient (80-86%) and meet office compliance requirements, but have very uneven brightness at the exit window.

[0005] In view of the above, there is a need to provide an improved track lighting system that is cost effective, easy to assemble, yet exhibits uniform brightness.

[0006] DE202016002197U1 discloses a direct-light LED lamp with anti-glare effect. Summary of the Invention [Problem to be solved by the invention]

[0007] It is an object of the present invention to overcome or at least mitigate the aforementioned problems and to provide an improved lighting system. [Means for solving the problem]

[0008] To this end, the present invention provides an elongated optical element for an illumination system, having a longitudinal extension and a width as a transverse extension that is substantially perpendicular to the longitudinal extension. The longitudinal extension of the optical element depends on the intended application and may be between 1 cm and 100 m. The transverse extension of the optical element may be between 5 mm and 30 cm. The optical element according to the present invention may be a diffuser. The term "substantially" as used in the context of the present description is intended to mean "coinciding or slightly deviating".

[0009] The optical element of the present invention further includes a central portion having a first edge and a second edge arranged substantially parallel to each other and to a longitudinal extension of the optical element. The lateral extension of the central portion of the optical element may be 10% to 90% of the lateral extension of the optical element. The central portion of the optical element is arranged to be positioned to cover a light source of a track lighting system.

[0010] The optical element according to the present invention further includes at least a first light guide disposed on a first edge of the central portion. The first light guide may be laterally aligned with a light source of the track lighting system. The first light guide may be attached to the first edge of the central portion by a fastening element, such as an adhesive, a clamp, or a screw. Alternatively, the first light guide may be an integral part of the optical element, i.e., the first light guide and the central portion may be manufactured as one single piece. In particular, the first light guide and the central portion may be molded together in one process step from one tool. In such an embodiment, the first light guide and the central portion are manufactured from the same material.

[0011] The optical element according to the present invention has a first surface facing at least one light source of a track lighting system and a second surface opposite the first surface, the first surface of the first light guide including at least one longitudinal jag substantially parallel to a longitudinal extension of the optical element, and the optical element further includes a plurality of first light guides spaced apart along the first edge of the central portion.

[0012] Thus, the essence of the invention is to improve brightness uniformity by causing the light beam emitted from the light source to be reflected by the longitudinal jugs, thereby providing an additional apparent light source and thus enlightening dark areas of the light pattern that might otherwise be formed.

[0013] The optical element may further include a second light guide disposed on a second edge of the central portion. Such an embodiment provides the advantage of a symmetrical light pattern. The second light guide may be laterally aligned with the light source and / or the first light guide of the illumination system. The second light guide may be attached to the second edge of the central portion by adhesive or any other suitable means. Alternatively, the second light guide may be an integral part of the optical element, i.e., the second light guide and the central portion may be manufactured as a single unit.

[0014] In unclaimed embodiments, the first light guide and / or the second light guide may be continuous and may have a longitudinal extension substantially equal to the longitudinal extension of the optical element, in other words, the first light guide and / or the second light guide may run along the entire first edge and / or second edge of the central portion, respectively.

[0015] Although the invention will primarily be described only with respect to track lighting systems, it is also suitable for use in other types of (linear) lighting systems that include elongated optical elements, for example TLEDs.

[0016] As described above, the optical element may include a plurality of first light guides spaced apart along a first edge of the central portion. This minimizes the amount of light guided longitudinally through the optical element, thereby increasing the likelihood of meeting higher requirements for office compliance parameters (e.g., UGR, L65) in the longitudinal direction. When multiple first light guides are present, each first light guide may be laterally aligned with a light source of the illumination system. Similarly, the optical element may include a plurality of second light guides spaced apart along a second edge of the central portion. When multiple second light guides are present, each second light guide may be laterally aligned with a light source of the illumination system. Furthermore, each second light guide may be aligned with the first light guide.

[0017] The second light guide may include a longitudinal jug disposed on a first surface of the second light guide, the longitudinal extension of the jug being substantially equal to the longitudinal extension of the first light guide and / or the second light guide.

[0018] The longitudinal jags provided on the first surface of the first light guide and / or the second light guide may be in the form of grooves, the depth of which may be adapted to the intended application but should be sufficient to allow reflection of the light emitted by the light source.

[0019] Alternatively, the longitudinal jug may be formed between the riser portion of the step and the tread portion, in such an embodiment, the light beam is reflected by the riser portion.

[0020] The elongated optical element according to the present invention may include at least one lens plate arranged along a central portion of the optical element, the lens plate being arranged to cover the light sources of the illumination system, and preferably the number of lens plates is equal to the number of light sources.

[0021] The optical element may include at least one collimator disposed adjacent to the at least one lens plate on a first surface of the optical element in a central portion. Such an embodiment offers the advantage of providing a parallel light beam through the light guide, thus improving control of the beam once it reaches the edges and / or longitudinal jugs of the light guide.

[0022] The angle between the first light guide and / or the second light guide and the central portion of the optical element may be between 90° and 180°.

[0023] The present invention relates to a lighting system, e.g., a track lighting system, including a (track) substrate having a longitudinal extension, with first and second edges running substantially parallel to the longitudinal extension and spaced apart in a transverse direction substantially perpendicular to the longitudinal extension. The substrate has a first width W1 between the first and second edges. In other words, the substrate may be in the form of an elongated strip of material. The substrate may be flexible or rigid. The substrate may be made of any suitable material, such as polymethyl methacrylate (PMMA) or polycarbonate (PC). The length and width W1 of the substrate may be adapted to the desired application of the lighting system. Typically, the length of the substrate is significantly greater than the width W1 of the substrate. For example, the length of the substrate may be between 5 cm and 5 m. The width W1 of the substrate may be between 1 cm and 10 cm.

[0024] The lighting system further includes at least one printed circuit board (PCB) arranged on the base and including at least one light source. The at least one PCB has a second width (W2) in a direction substantially perpendicular to the longitudinal extension (L) of the base. The term "arranged on" is understood as meaning that the base and the PCB are arranged in direct or indirect contact with each other. In other words, the PCB may be directly adjacent to the base. Alternatively, there may be an additional layer between the base and the PCB, for example in the form of a thin plastic sheet with high reflectivity. The first width W1 may be greater than the second width W2. In other words, there may be portions of the base that are free of a PCB. In particular, W2 may be less than 100 mm, preferably less than 60 mm, and more preferably less than 40 mm.

[0025] The PCB may be symmetrically positioned relative to the central longitudinal axis of the base such that the distance between the first edge portion and the PCB is equal to the distance between the second edge portion and the PCB. Alternatively, the PCB may be asymmetrically positioned relative to the central longitudinal axis of the base. The lighting system may include one PCB having a length substantially equal to the length of the base. Alternatively, the lighting system may have multiple PCBs positioned along the longitudinal extension of the base. In such an embodiment, the length of each PCB is shorter than the length of the base.

[0026] An illumination system according to the present invention may include multiple light sources. In such an embodiment, each light source of the multiple light sources may be covered by a common lens plate or by an individual lens plate. Typically, a lens plate has a length of 280 mm (1 foot) and covers 20 to 24 LEDs. Alternatively, the number of light sources in the multiple light sources is equal to the number of lens plates in the multiple lens plates.

[0027] The light sources and lens plates may be arranged in a linear array. The array may be a straight array. In another embodiment, the linear array is curved in a plane perpendicular to the optical axis of the lens plates.

[0028] The illumination system includes an optical element as described above. The optical element is arranged downstream from at least one light source. Finally, the illumination system further includes a cover arranged downstream from the optical element. The term "downstream" in the context of the present invention is intended to mean in a consecutive order in the direction of the light path. Finally, the illumination system includes a cover arranged downstream from at least one diffuser. The cover may be an optical cover that may be made of polycarbonate (PC). The cover may be clear or diffusive. Furthermore, the cover may include an optical structure or may be flat to provide an appropriate light distribution and improve the uniformity of the light exit window so that the light exit window is perceived as uniformly illuminated.

[0029] The optical element may have a width Wo in the lateral extension. In particular, the width Wo of the optical element may be greater than the second width W2 of the PCB. Such an embodiment provides the advantage of improving brightness uniformity.

[0030] Finally, the invention relates to a lighting device comprising a lighting system as described above. The lighting system may be a track lighting system. The lighting device may be a track lighting device, a (track) lighting fixture, in particular an office (track) lighting fixture, comprising the track lighting system.

[0031] The invention relates to all possible combinations of the features recited in the claims. [Brief explanation of the drawings]

[0032] These and other aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numerals refer to like elements throughout, and in which: [Figure 1a] 1 shows a perspective view of an optical element according to an unclaimed embodiment of the present invention. [Figure 1b]1 shows a perspective view of an optical element according to an unclaimed embodiment of the present invention. [Figure 2a] 1a, 1b and 4a-4c show cross-sectional views of the optical elements shown in FIG. [Figure 2b] 3 shows a cross section of an optical element according to another embodiment of the present invention. [Figure 3a] 3 shows the brightness pattern provided by the track lighting system according to the present invention. [Figure 3b] 3 shows the brightness pattern provided by the track lighting system according to the present invention. [Figure 4a] 1 shows a perspective view of an optical element according to yet another embodiment of the present invention; [Figure 4b] 1 shows a perspective view of an optical element according to yet another embodiment of the present invention; [Figure 4c] 1 shows a perspective view of an optical element according to yet another embodiment of the present invention; [Figure 5] 4a-4c show the brightness patterns provided by the optical elements shown in FIGS. [Figure 6a] 1 shows the brightness pattern provided by a track lighting system according to the prior art, i.e., without optical elements. [Figure 6b] 1A and 1B show the brightness patterns provided by a track lighting system having optical elements according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0033] The present invention will be described more fully below with reference to the accompanying drawings, in which presently preferred embodiments of the invention are shown. However, the present invention may 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, so as to fully convey the scope of the present disclosure to those skilled in the art. In the drawings, the present invention will be discussed primarily in terms of a track lighting device, but should be considered to apply generally to other (linear) lighting devices that include at least one elongated optical element.

[0034] 1a and 1b show a top view and a bottom view, respectively, of an elongated optical element 1. The elongated optical element 1 has a longitudinal extension L and a lateral extension T that is substantially perpendicular to the longitudinal extension L. The optical element 1 shown in FIGS. 1a and 1b further comprises a central portion 2 having a first edge 2′ and a second edge 2″ that are arranged substantially parallel to each other and to the longitudinal extension L of the optical element 1. The central portion 2 of the optical element 1 is arranged such that it is positioned to cover a light source of the illumination system 100, as can be seen in FIG. 2a.

[0035] The optical element according to the invention further comprises a first light guide 3 arranged at a first edge 2' of the central portion 2 and a second light guide 3' arranged at a second edge 2'' of the central portion 2. The first light guide 3 and the second light guide 3' may be aligned with a light source of the illumination system in the lateral direction T. The first light guide 3 and the second light guide 3' are integral parts of the optical element 1, i.e. the first light guide 3 and the second light guide 3' and the central portion 2 are manufactured as a single piece.

[0036] The optical element 1 shown in Figure 1a has a first surface 4 facing the at least one light source of the illumination system 100, and a second surface 4' opposite to the first surface 4. The first surface 4 of the first light guide 3 comprises longitudinal jugs 5 that are substantially parallel to the longitudinal extension L of the optical element 1. The second surface 4' of the second light guide 3' comprises longitudinal jugs 5' that are substantially parallel to the longitudinal extension L of the optical element 1. The longitudinal jugs 5, 5' depicted in Figures 1a, 1b and 2a are in the form of grooves.

[0037] The illumination system 100 includes a substrate 110 having a longitudinal extension, with a first edge 110′ and a second edge 110″ running substantially parallel to the longitudinal extension and spaced apart in a transverse direction that is substantially perpendicular to the longitudinal extension. The substrate 110 has a first width W1 between the first edge 110′ and the second edge 110″. In other words, the substrate 110 is in the form of an elongated strip of material.

[0038] The illumination system further includes at least one PCB 111 disposed on the base 110 and including at least one light source 112. The at least one PCB 111 has a second width W2 in a direction substantially perpendicular to the longitudinal extension (L) of the base 110. The first width W1 is greater than the second width W2.

[0039] The PCB 111 is positioned symmetrically about the central longitudinal axis 8 of the base 110 such that the distance between the first edge portion 110' and the PCB is equal to the distance between the second edge portion 110'' and the PCB.

[0040] The optical element 1 has a width Wo in lateral extension. As can be seen in Fig. 2a, the width Wo of the optical element 1 is greater than the second width W2 of the PCB 111. A cover 113 is arranged downstream from said optical element 1.

[0041] Thus, the essence of the invention is to cause the light beam emitted from the light source to be reflected by the longitudinal jags, providing an additional apparent light source, thus improving brightness uniformity by illuminating dark areas of the light pattern that might otherwise be formed.

[0042] The optical element 1 further comprises a second light guide 3' arranged at a second edge 2'' of the central portion 2. Such an embodiment offers the advantage of a symmetrical light pattern. The second light guide 3' may be laterally aligned with the light source and / or the first light guide 3 of the illumination system 100. The second light guide 3' may be attached to the second edge 2'' of the central portion 2. Like the first light guide 3, the second light guide 3' may be an integral part of the optical element 1, i.e. the second light guide 3' and the central portion 2 may be manufactured as a single piece.

[0043] 1a and 1b are unclaimed embodiments in which the first light guide 3 and the second light guide 3' are continuous and have a longitudinal extension substantially equal to the longitudinal extension of the optical element 1. In other words, the first light guide 3 and the second light guide 3' run along the entire first edge 2' and second edge 2'' of the central portion 2, respectively.

[0044] Figure 3a shows the luminance pattern of the track lighting system 100 obtained by the embodiment shown in Figure 2a at viewing angles of 0° on the left and 30° on the right, respectively. As can be seen, the luminance pattern is improved compared to the luminance pattern provided by the prior art track lighting system shown in Figure 6a.

[0045] Figure 2b shows a cross-sectional view of an optical element 101 according to another embodiment of the invention. The structure of the optical element 101 is similar to that of the optical element 1. Longitudinal jags 105, 105' are in the form of steps and are provided on the first face 104 (opposite the second face 104') of the first light guide 103 and the second light guide 103' connected to the central portion 102. Figure 3b shows the luminance pattern of a track lighting system 1001 including the optical element 101 obtained by the embodiment shown in Figure 2b at viewing angles of 0° on the left and 30° on the right, respectively.

[0046] As described above, the optical element 201 may include a plurality of first light guides 203 spaced apart along the first edge 202′ of the central portion 202. Such an embodiment minimizes the amount of light guided longitudinally of the optical element 201. If multiple first light guides 203 are present, each first light guide 203 may be laterally aligned with a light source of the track lighting system 2001. The optical element 201 further includes a plurality of second light guides 203′ spaced apart along the second edge 202″ of the central portion 202. If multiple second light guides 203′ are present, each second light guide 203′ is laterally aligned with a light source of the track lighting system 2001. Furthermore, each second light guide 203′ is aligned with a first light guide 203.

[0047] Each of the first light guides 203 and each of the second light guides 203' includes longitudinal jags 205, 205' disposed on the first surface 204. The longitudinal extension of the jags 205, 205' is substantially equal to the longitudinal extension of the first light guide 203 and the second light guide 203'. The longitudinal jags 205, 205' provided on the first surface 204 of the first light guide 203 and the second light guide 203' are in the form of grooves. The depth of the grooves 205, 205' should be sufficient to allow reflection of light emitted by the light source, as shown in FIG. 5.

[0048] 4a, the elongated optical element according to the present invention includes a plurality of lens plates 206 arranged along the central portion 202 of the optical element 201. The lens plates 206 are arranged to cover the light sources of the track lighting system 2001. Preferably, the number of lens plates 206 is equal to the number of light sources.

[0049] The optical element 201 includes a plurality of collimators 207 disposed adjacent to a lens plate 206 on a first surface 204 of the optical element 201 in a central portion 202, as shown in Figure 4b. Figure 4c shows a detailed view of Figure 4b. Figures 5 and 6b show the brightness pattern provided by the track lighting system shown in Figures 4a-4b. As is evident from these figures, the brightness pattern is improved compared to the brightness pattern shown in Figure 6a provided by a prior art track lighting system.

[0050] Those skilled in the art will recognize that the present invention is by no means limited to the preferred embodiments described above. Furthermore, variations to the disclosed embodiments can be understood by those skilled in the art, from a study of the drawings, the disclosure, and the appended claims, and can be implemented in practicing the claimed invention. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite articles "a" or "an" do not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage.

Claims

1. an elongated optical element for an illumination system, having a longitudinal extension and a width as a lateral extension substantially perpendicular to said longitudinal extension, the optical element having a central portion with a first edge and a second edge arranged substantially parallel to each other and to the longitudinal extension of the optical element, the optical element further comprising at least a first light guide arranged at the first edge of the central portion, the optical element having a first side facing at least one light source of the illumination system and a second side opposite to the first side, the first side of the first light guide comprising at least one longitudinal jug substantially parallel to the longitudinal extension of the optical element; The optical element is an elongated optical element including a plurality of first light guides spaced apart along the first edge of the central portion.

2. The elongated optical element of claim 1 , further comprising a second light guide disposed at the second edge of the central portion.

3. The elongated optical element of claim 2 , wherein the second light guide includes longitudinal jags disposed on the first surface of the second light guide.

4. An elongate optical element according to any one of claims 1 to 3, wherein the jags are in the form of grooves.

5. 4. An elongate optical element according to any one of claims 1 to 3, wherein the jug is formed between a riser portion and a tread portion of a step.

6. 6. An elongate optical element according to any one of the preceding claims, wherein the longitudinal extension of the jug is substantially equal to the longitudinal extension of the optical element.

7. 7. An elongate optical element according to any one of the preceding claims, wherein the optical element comprises at least one lens plate arranged along the central portion of the optical element.

8. 8. The elongated optical element of claim 7, wherein the optical element includes at least one collimator disposed adjacent the at least one lens plate on the first surface of the optical element in the central portion.

9. An elongate optical element according to any one of the preceding claims, wherein the optical element is a diffuser.

10. 10. An elongate optical element according to any one of the preceding claims, wherein the angle between the first light guide and / or the second light guide and the central part of the optical element is between 90° and 180°.

11. a substrate having a longitudinal extension, a first edge and a second edge running substantially parallel to said longitudinal extension and spaced apart in a transverse direction that is substantially perpendicular to said longitudinal extension, said substrate having a first width between said first edge and said second edge; at least one printed circuit board (PCB) disposed on the base and including at least one light source, the at least one PCB having a second width in a direction substantially perpendicular to the longitudinal extension of the base; An optical element according to any one of claims 1 to 10, arranged downstream from the at least one light source; a cover disposed downstream from the optical element; a lighting system, including:

12. 12. The lighting system of claim 11, wherein the lighting system is a track lighting system.

13. 13. A lighting device comprising a lighting system according to claim 11 or 12.

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