Linear luminaire

Abstract

A linear luminaire (100), comprising: a housing (110) having a first light exit window (111) and a second light exit window (112) separate to the first light exit window, each light exit window extending along a length of the linear luminaire, and both light exit windows are positioned at a first surface (114) of the housing; a plurality of LEDs (120) contained in the housing and arranged linearly along the length of the linear luminaire between the first and second light exit windows; and a reflector arrangement (130) contained in the housing, wherein the reflector arrangement comprises: a first reflective portion (131) configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the first reflective portion is directed towards the first light exit window and converges as the reflected light from the first reflective portion travels towards the first light exit window; and a second reflective portion (132) configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the second reflective portion is directed towards the second light exit window and converges as the reflected light from the second reflective portion travels towards the second light exit window; wherein the first light exit window (111) and the second light exit window (112) are slits extending along the length of the linear luminaire.

Description

[0001] 2024PF80368 1

[0002] LINEAR LUMINAIRE

[0003] FIELD OF THE INVENTION

[0004] The invention relates to the field of linear luminaires.

[0005] BACKGROUND OF THE INVENTION

[0006] Glare from lighting installations can cause visual discomfort and can result in eye fatigue and / or headaches. Glare control is therefore an important factor in designing lighting installations.

[0007] Glare is commonly measured using the Unified Glare Rating (UGR), which takes into account all glare sources in a visual field. It is important that an environment does not have a higher UGR than is recommended for an activity being carried out in the environment, in order for the activity to be performed in comfort.

[0008] One way to reduce the glare in an environment is to use lighting having a lower UGR value. Reflective portions and collimators are often used to condense light in luminaires, but controlling glare while maintaining high optical efficiency is difficult with these components, as it is not generally possible to achieve a clear cut-off angle.

[0009] There is therefore a need for improved low-UGR luminaire designs.

[0010] SUMMARY OF THE INVENTION

[0011] The invention is defined by the claims.

[0012] According to examples in accordance with an aspect of the invention, there is provided a linear luminaire, comprising: a housing having a first light exit window and a second light exit window separate to the first light exit window, each light exit window extending along a length of the linear luminaire, and both light exit windows are positioned at a first surface of the housing; a plurality of LEDs contained in the housing and arranged linearly along the length of the linear luminaire between the first and second light exit windows; and a reflector arrangement contained in the housing, wherein the reflector arrangement comprises: a first reflective portion configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the first reflective portion is directed towards the first light exit window and converges as the reflected light from the first reflective portion travels towards 2024PF80368 2 the first light exit window; and a second reflective portion (132) configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the second reflective portion is directed towards the second light exit window and converges as the reflected light from the second reflective portion travels towards the second light exit window. The first light exit window and the second light exit window are slits extending along the length of the linear luminaire, preferably, a width of each slit is not more than 20% of a width of the housing.

[0013] This structure provides a simple way to reduce an angle of light output from the linear luminaire, thus reducing glare from the linear luminaire, while maintaining a high optical efficiency. By focusing light emitted by each LED towards each window via the reflector arrangement, the majority of light emitted by the LED is output from the luminaire, but within a particular angle range.

[0014] By providing a light exit window in the housing on both sides of the plurality of LEDs and configuring the reflector arrangement to reflect light towards both light exit windows, a greater proportion of light emitted by the LEDs may be output by the linear luminaire, further improving the optical efficiency of the linear luminaire. Furthermore, two light exit windows allow the two beams from the reflector arrangement to be overlapped (but not coincided) on the surface to be illuminated. Thus, the uniformity of the light output is improved.

[0015] The LEDs may be in a symmetrical package, e.g., model 5050 of the size 5 mm times 5mm, or in an asymmetrical package, e.g., model 2835 which is 2.8 mm x 3.5 mm. In the context of present disclosure, the length of LED is measured in the length direction of the linear luminaire and the width of LED is measured in a lateral direction of the linear luminaire which is perpendicular to the length direction.

[0016] Light being converged by the reflective portions and then output from the light exit window divergently may have Color over Angle issue at edges of the spot. This issue may be more severe along the spot edges parallel to the length of the linear luminaire.

[0017] In some examples, the plurality of LEDs may be mounted on an elongate PCB, wherein neighboring LEDs have a staggered offset from each other in a direction laterally to the length direction of the PCB. An offset distance between the neighboring LEDs is in a range of 1 / 4 to 1 / 3 of width of one of the LEDs. The offset configuration of LEDs improves the Color over Angle issue, providing a spot projected from the linear luminaire with uniform color especially at the edge portions of the spot. 2024PF80368 3

[0018] The light output from the linear luminaire may be tunable white with Color Rendering Index (CRI) > 90, preferably CRI > 95.

[0019] To achieve tunable white light output, the linear luminaire may use cold white (CW) and warm white (WW) LEDs. In some examples, one CW and one WW LEDs chips are combined in a single LED package, and a row of LED packages are mounted on the elongate PCB. It’s preferable to interlacing the orientation of each LED package in the row to provide homogeneous light output from the linear luminaire. In other examples, individual CW or WW LED chips are used, and these individual LED chips are arranged in a row on the PCB. The LEDs with different color temperature, CCT, may be mounted on the PCB in an even configuration so as to provide homogeneous light output. In the case of neighboring LEDs having a staggered offset from each other in the width direction, CW and WW chips may also be mounted on the PCB in an even distribution in the width direction. One pair of chips with same CCT is configured as a group. Two groups of same CCT are interval with a group of the other CCT.

[0020] In some examples, an inner surface of the housing, surrounding the plurality of LEDs and the reflector arrangement, is configured to absorb light.

[0021] In this way, stray light (i.e. light that is not focused towards either light exit window) is prevented from exiting the housing. Thus a sharp cut-off of the output beam is achieved (i.e. providing a spot with clear edge on the surface to be illuminated).

[0022] In some examples, the first reflective portion and second reflective portion are partial cylindrical reflectors. At cross-sectional view, the reflector may be in the form of a segment of a circle, an ellipse, a parabolic or a higher order polynomial curve, such as Bessel’s curve.

[0023] Preferably, the reflector arrangement comprises a substrate and a specular reflective foil laminated on the substrate. The substrate may be made of plastic.

[0024] In some examples, the first reflective portion and second reflective portion together provide a continuous reflective surface.

[0025] This prevents loss of light between the first and second reflective portion, increasing the amount of light reflected by the reflector arrangement towards the first and second light exit windows, and thus increasing the amount of light output by the luminaire.

[0026] The reflector arrangement is preferably positioned at a second surface inside the housing that is opposite to the first surface of the housing comprising the first and second light exit window. 2024PF80368 4

[0027] In some examples, the first reflective portion is configured to cause the reflected light from the first reflective portion to converge to a first focal line between the first reflective portion and the first light exit window, and the second reflective portion is configured to cause the reflected light from the second reflective portion to converge to a second focal line between the second reflective portion and the second light exit window.

[0028] Positioning the first and second focal lines within the housing improves the safety of the luminaire, as a focal line / point outside the housing of a luminaire would present a risk of blinding.

[0029] In some examples, the first reflective portion is configured to cause the reflected light from the first reflective portion to converge to a first focal line at the first light exit window; and the second reflective portion is configured to cause the reflected light from the second reflective portion to converge to a second focal line at the second light exit window.

[0030] Positioning the first and second focal lines at (or close to) the first and second light exit windows respectively allows the first and second light exit windows to be thinner without reducing an optical efficiency of the linear luminaire. This further reduces a likelihood that stray light will escape the linear luminaire at angles that would cause glare.

[0031] In some examples, the first reflective portion is symmetrical to the second reflective portion with respect to the plurality of LEDs.

[0032] A symmetric arrangement of the first and second reflective portions results in an inherently symmetrical light distribution. This enables a better uniformity of output light to be achieved more easily, compared with off-axis optical designs in which the light output is inherently not symmetrical (which increases the difficulty in optical design and reduces a feasibility of uniformity).

[0033] Further, the symmetric arrangement of the first and second reflective portions provides an improved color distribution. In conventional narrow-beam luminaires, light emitted from the LED(s) at large angles have a greater proportion of yellow light than light at the center of the emitted light. This issue is known as the color over angle effect, and is typically resolved using a fly-eye microstructure on a lens.

[0034] The symmetric reflector arrangement results in yellow wavelengths at large angles of the light emitted by the LED being reflected towards the center, and the central portion of emitted light (which has more blue light) being reflected towards the sides. In this way, color uniformity in the light output by the linear luminaire may be achieved without the need for a correcting lens microstructure. 2024PF80368 5

[0035] In some examples, the linear luminaire further comprises a condensing lens provided between each of the plurality of LEDs and the reflector arrangement.

[0036] This condenses light emitted by each LED onto the reflector arrangement, reducing the amount of light emitted by the plurality of LEDs that is not reflected by the reflector arrangement.

[0037] In some examples, the condensing lens is a meniscus lens. A meniscus lens allows a greater proportion of the light emitted by each LED to be collimated by the lens, as the LED can be mounted in the cavity of the concave side of the meniscus lens. Alternatively, the lens can be a column lens covering the linear arranged LED string.

[0038] Preferably, an array of linear micro-structures is provided on the surface of the cavity of the meniscus lens. The array of linear micro-structures comprises a group of linear protrusions or grooves, with each one of the linear protrusions or grooves extending along the length of the linear luminaire and the protrusions or grooves juxtaposing laterally to the linear luminaire. The width of each linear protrusion or groove is less than 1 / 10 of the width of the respective LED, and the length of each linear protrusion or groove is longer than the length of the respective LED. The array of linear micro-structures further improves the Color over Angle issue by mixing the yellow wavelengths at large angles of the light emitted by the LED with the main beam which has more blue light.

[0039] In some examples, the linear luminaire further comprises a first correcting lens provided between the first reflective portion and the first light exit window, and a second correcting lens provided between the second reflective portion and the second light exit window.

[0040] The first and second correcting lenses can modify the light distribution for different applications. For example, it would be for a wall washing. A typical application for wall washing is to illuminate the black board in the classroom or the paints in the museum. In this case, the light distribution is not symmetrical, otherwise the upper part will be much brighter than the lower part.

[0041] In some examples, the linear luminaire further comprises a first opaque shield positioned between each LED and the first light exit window.

[0042] This blocks light emitted by the LEDs from directly exiting through the first light exit window in the housing (i.e. without having first been focused by the reflector arrangement), further reducing glare.

[0043] In some examples, the linear luminaire further comprises a second opaque shield positioned between each LED and the second light exit window. 2024PF80368 6

[0044] This blocks light emitted by the LEDs from directly exiting through the second light exit window, further reducing glare.

[0045] The opaque shield(s) may extend in a direction perpendicular to the PCB.

[0046] The distance (pitch) between LED along the length direction is about 15 to 50 (preferably 20-30) times of the length of LED.

[0047] In some examples, the linear luminaire further comprises barrier shields between the neighboring LEDs, to prevent light interruption between the neighboring LEDs along the length direction of the linear luminaire. Such barrier shields may also reduce the beam angle of the linear luminaire in the length direction. Preferably, the height of the barrier shields is about 0.5 to 1.5 times of the pitch of the LEDs on the PCB.

[0048] These and other aspects of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

[0049] BRIEF DESCRIPTION OF THE DRAWINGS

[0050] For a better understanding of the invention, and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which:

[0051] Figure 1 illustrates a perspective view of a linear luminaire, according to an embodiment of the invention;

[0052] Figure 2 illustrates a cross-sectional view of the linear luminaire;

[0053] Figure 3 illustrates a ray diagram for the linear luminaire;

[0054] Figure 4 illustrates a view of a use case of the linear luminaire;

[0055] Figure 5 illustrates another view of the use case in Figure 4;

[0056] Figure 6 illustrates another cross-sectional view of the linear luminaire;

[0057] Figure 7 illustrates a side view of the reflector;

[0058] Figure 8 illustrates an explosive view of the light source assembly of the linear luminaire;

[0059] Figure 9 illustrates a sectional view of the light source assembly;

[0060] Figure 10 illustrates a planar view of the light source assembly;

[0061] Figure 11 illustrates a planar view of the plurality of LEDs on the PCB; and Figures 12 and 13 illustrate difference views of the condensing lens.

[0062] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0063] The invention will be described with reference to the Figures. 2024PF80368 7

[0064] It should be understood that the detailed description and specific examples, while indicating exemplary embodiments of the apparatus, systems and methods, are intended for purposes of illustration only and are not intended to limit the scope of the invention. These and other features, aspects, and advantages of the apparatus, systems and methods of the present invention will become better understood from the following description, appended claims, and accompanying drawings. It should be understood that the Figures are merely schematic and are not drawn to scale. It should also be understood that the same reference numerals are used throughout the Figures to indicate the same or similar parts.

[0065] There is proposed a linear luminaire comprising a housing, a plurality of linearly-arranged LEDs and a reflector arrangement. The housing comprises a linear light exit window either side of the line of LEDs. The reflector arrangement comprises first and second reflective portions, each configured to reflect light emitted by each LED and direct the reflected light towards a respective light exit window in the housing. The first and second reflective portions are configured such that the reflected light converges as the reflected light travels towards the respective light exit window in the housing.

[0066] Embodiments are at least partly based on the realization that the angle range of light output by a linear luminaire may be reduced by the use of a reflector arrangement to focus the light.

[0067] Illustrative embodiments may, for example, be employed in lighting installations that have low UGR requirements.

[0068] Figure 1 illustrates a perspective view of a linear luminaire 100, according to an embodiment of the invention. The linear luminaire comprises a housing 110, a plurality of LEDs 120 and a reflector arrangement 130 contained in the housing.

[0069] The housing 110 comprises a first light exit window 111 and a separate second light exit window 112 to allow light to exit the housing. Each light exit window (or “aperture” or “slit”) extends linearly along the length of the linear luminaire (i.e. parallel or substantially parallel to the largest dimension, along Y axis, of the linear luminaire). The first and second light exit windows may each extend along the majority of the length of the linear luminaire (e.g. along at least 90% of the length of the linear luminaire). The first and second light exit windows may, in some examples, be covered by a transparent material, such as glass.

[0070] The first 111 and second 112 light exit windows may be positioned in a same side of the housing 110. For instance, the first 111 and second 112 light exit windows may lie in a same plane (surface 114 in X-Y plane, as illustrated), but this is not essential. 2024PF80368 8

[0071] The remainder of the housing 110 is opaque to visible light, such that light emitted by the plurality of LEDs 120 is only able to exit the linear luminaire 100 through the first and second light exit windows 111, 112. Preferably, the inner surface 113 of the housing (except at the first and second light exit windows) is configured to absorb light. Suitable lightabsorbing materials for the inner surface of the housing will be apparent to the skilled person. Alternatively, the inner surface 113 of the housing may be reflective, e.g., perform specular reflection of received light.

[0072] The plurality of LEDs 120 are arranged linearly along the length (Y direction) of the linear luminaire 100 between the first light exit window 111 and the second light exit window 112. Preferably, the LEDs are arranged to face away from the first and second light exit windows 111, 112 and emit light towards the reflector arrangement 130.

[0073] The reflector arrangement 130 is provided on a different (e.g., opposite) side of the housing 110 to the first light exit window 111 and second light exit window 112, and is configured to reflect light emitted by the plurality of LEDs towards the first and second light exit windows, such that at least the majority of light emitted by each LED is output through the first and second light exit windows. For instance, the reflector arrangement 130 is mounted on an internal surface 115 as illustrated.

[0074] As the skilled person will readily appreciate, the linear luminaire may further comprise other common components of a luminaire, such as a heat sink, power / driving circuitry, control circuitry, communication circuitry and so on.

[0075] The structure of the reflector arrangement 130 is shown more clearly in Figure 2, which illustrates a cross-sectional view of the linear luminaire 100. As can be seen in Figure 2, the reflector arrangement comprises a first reflective portion 131 and a second reflective portion 132.

[0076] Preferably, the first reflective portion and second reflective portion are symmetrical with respect to the plurality of LEDs 120, in order to provide a uniform light output from the linear luminaire. Optical simulations have shown that a symmetrical arrangement of the first and second reflective portions can provide a uniformity higher than 0.6 (lumen min / lumen average), thus meeting the requirements for a unified glare rating of UGR19.

[0077] The light distribution provided by the linear luminaire may be adjusted by varying the angles of the first and second reflective portions with respect to the plurality of LEDs 120, the first and second light exit windows 111, 112, and / or each other. In some 2024PF80368 9 examples, the first and second reflective portions may be arranged to provide an asymmetrical light distribution.

[0078] In Figure 2, each of the first reflective portion 131 and the second reflective portion 132 is a cylindrical reflector. The cylindrical reflectors may have any suitable shape for causing light to converge as it is reflected towards a light exit window; for instance, the cylindrical reflectors may be circular cylindrical reflectors, parabolic cylindrical reflectors or elliptical cylindrical reflectors.

[0079] Other suitable configurations of the first and second reflective portion will be apparent to the skilled person. For instance, each of the first and second reflective portions may comprise a row of spherical, parabolic or elliptical reflectors (e.g. with the number of reflectors in each row corresponding to the number of LEDs in the plurality of LEDs 120).

[0080] Preferably, the first and second reflective portions together provide a continuous reflective surface, in order that the majority of light, e.g., more than 90% of light, emitted by each LED towards the reflector arrangement is reflected by one or other of the first and second reflective portions.

[0081] The first reflective portion 131 is configured to reflect light emitted by each of the plurality of LEDs 120 such that the reflected light from the first reflective portion is directed towards the first light exit window 111 and converges as the reflected light from the first reflective portion travels towards the first light exit window.

[0082] Similarly, the second reflective portion 132 is configured to reflect light emitted by each of the plurality of LEDs 120 such that the reflected light from the second reflective portion is directed towards the second light exit window 112 and converges as the reflected light from the second reflective portion travels towards the second light exit window.

[0083] The behavior of light in the linear luminaire 100 is shown in Figure 3, which illustrates a ray diagram for the linear luminaire.

[0084] In the example illustrated by Figure 3, light reflected by each reflective portion 131, 132 converges to a focal line inside the housing 110. In other words, the first reflective portion 131 is configured to cause reflected light to converge to a first focal line between the first reflective portion and the first light exit window 111, and the second reflective portion 132 is configured to cause reflected light to converge to a second focal line between the second reflective portion and the second light exit window 112.

[0085] In other examples, the first and second focal lines may be located at or near the first and second light exit window respectively. A focal line may be considered to be “at” a light exit window if the focal line lies within the plane of the light exit window. Configuring 2024PF80368 10 the first and second reflective portions to focus light at the first and second light exit windows allows narrower windows to be used without reducing an amount of light output through the windows.

[0086] Preferably, the first and second focal lines are not located outside the housing 110, as this can present a hazard to the human eye.

[0087] Depending on the shape of the first and second reflective portions, light reflected by each reflective portion may not converge exactly to a single focal line. Rather, some aberration may be present, as shown in Figure 3. Therefore, the terms “first focal line” and “second focal line” as used herein should be understood as not necessarily denoting a line that extends only in one direction; each focal line may have a non-zero “thickness”, with the thickness depending on the extent of aberration.

[0088] The angle range of light output from the linear luminaire 100 will depend on the width of the first and second light exit windows in the housing 110, and on the focal length of the first and second reflective portions of the reflector arrangement 130. A longer focal length will result in light having a narrower angle range. Since a shorter focal length results in light having a wider angle range, a wider window would typically (depending on the position of the focal line with respect to the light exit window) be required for a shorter focal length, in order to output the full angle range of light.

[0089] As illustrated by Figure 3, the beams from the light exit windows overlap at far field, and because the distance between the light exit windows is relative much smaller than the spot to be illuminated, the beam angle of the luminaire in lateral direction (in X-Z plane) is approximately the same as the beam angle coming from one of the light exit window.

[0090] A use case example is shown in Figure 4 at width direction of the linear luminaire, and in Figure 5 at length direction of the linear luminaire. It’s desired to match the angle range of light output from the linear luminaire 100 with the area to be lit-up, e.g., a dinner table or a billiards table. Preferably, the spot from the linear luminaire is a little larger than the area of the table. The table is a rectangle, and the linear luminaire is suspended above the table along the table’s lengthy direction. The length LL of the luminaire is similar to that Ltabie of the table, see Figure 5, preferably Li. is larger than 90% of Ltabie. Compared to the width Wtabie of the table, width WL of the luminaire is relatively much smaller. A ratio of the length LL and the width WL of the luminaire is in the range of 10: 1 to 100: 1. In lateral direction (in X-Z plane of Figure 4), the light output angle ai ranges about 45 to 55°. In longitudinal direction (in Y-Z plane of Figure 5), the light output angle 012 ranges about 10 to 30°. Figure 5 shows half beam angle (012 / 2) at each side of the table. With such illumination, the details on the table can be 2024PF80368 11 perfectly demonstrated, while a person sitting aside or standing aside won’t see direct light from the luminaire in the meantime. Referring to Figure 6, preferably, the width Ws of each light exit window is wide enough to output at least the majority, and preferably substantially all, of the light directed towards the light exit window by the reflector arrangement 130, but is not significantly wider than the width of the beam at the light exit window, in order to prevent light exiting the luminaire at angles that would cause glare. The width Ws of a light exit window may be a distance across said light exit window in a direction (in X axis) perpendicular to the linear length (in Y axis) along which the light exit window extends, i.e., a cross-sectional width. Ws is at least 3 times of a width WLED of the light emitting surface of a LED in the plurality of LEDs 120. In preferable embodiments, Ws is at most 20% of the width WL of the housing 110.

[0091] Thus, a desired output angle range of light output from the linear luminaire 100 may be achieved by configuring the focal length of the first and second reflective portions 131 / 132 to produce the desired angle range, and configuring the widths and positions of the first and second light exit windows such that all light reflected and focused by the first and second reflective portions is output through the light exit windows, while light outside the desired output angle range is not output through the light exit windows. Preferably, the first and second reflective portions each have the same focal length, and the first and second light exit windows each have the same width Ws, in order to achieve a uniform light output from the first and second light exit windows.

[0092] Further referring to Figure 7, the reflector arrangement 130 is preferably made by attached a specular reflective foil or film over a substrate 135 to provide the desired shape for shaping the beam output. 3M Enhanced Specular Reflective film (ESR) is a good candidate as it reflects more than 98% visible incident light. It is a plastic sheet. To overcome the elasticity at the ridge between the 2 wings of the first and second reflective portions 131 / 132, it is preferable to kiss-cut with a thin scratch mark on the connection line between the first and second reflective portions 131,132. Such scratch mark cuts the film to a certain depth while still keeps the film in one piece, so that the film can be bent with no rebounding. In alternative examples, the specular reflective film is cut deeply till to the substrate 135.

[0093] The focal length of the first and second reflective portions 131 / 132 may be defined by the radius R of the first and second reflective portions 131 / 132 and the distance H between the plurality of LEDs 120 and the first and second reflective portions 131 / 132. It shall be noted that the radius of the first and second reflective portions 131 / 132 in sectional view 2024PF80368 12 includes high order polynomial so as to reduce optical aberration, not just a simple arc. Width WR of the reflector arrangement 130 is less than width WL of the luminaire. Here:

[0094] H is about 1 to 1.2 times of R;

[0095] WR is in the range of 1.5 to 2 times of H.

[0096] Returning to Figure 2, the linear luminaire 100 may further comprise a condensing lens 140 provided or positioned between each of the plurality of LEDs 120 and the reflector arrangement 130, in order to condense light emitted by each LED onto the reflector arrangement. This improves the optical efficiency of the linear luminaire, as a greater proportion of light emitted by the LED is output through the first and second light exit windows.

[0097] In Figure 2, the condensing lens 140 is a meniscus lens; however, any suitable condensing lens (e.g. a bi-convex lens) may be used. A meniscus lens has the advantage that the cavity provided by the concave side of the lens allows the LED to be mounted within the lens, resulting in more of the light emitted by the LED being collimated by the lens.

[0098] As previously mentioned, in some cases, not all of the light reflected by each reflective portion 131, 132 converges to a precise focal line. In some examples, the linear luminaire 100 may further comprise a correcting lens for each reflective portion (not shown in the Figures) to correct the aberration of the reflective portion. In particular, a first correcting lens provided between the first reflective portion 131 and the first light exit window 111 may be used to more precisely focus light to the first focal line, and a second correcting lens provided between the second reflective portion 132 and the second light exit window 112 may be used to more precisely focus light to the second focus line. Suitable lenses for correcting an aberration of the first and second reflective portions will be apparent to the skilled person.

[0099] In some examples, the linear luminaire 100 may further comprise one or more opaque shields to block light emitted by the plurality of LEDs 120 from exiting the linear luminaire through the first and / or second light exit window without first being reflected and focused by the reflector arrangement 130.

[0100] For instance, in Figure 2, a first opaque shield 151 is positioned between each LED and the first light exit window 111, and a second opaque shield 152 is positioned between each LED and the second light exit window 112.

[0101] The surface(s) of each opaque shield 151, 152 facing the LEDs may be configured to absorb light emitted by the LEDs. Alternatively, some or all of the surface(s) facing the LEDs may be made from or coated with a reflective material, such that each opaque 2024PF80368 13 shield is configured to redirect light away from the first or second light exit window and towards the reflector arrangement 130.

[0102] When using middle power LED as light source, there may be Color over Angle (CoA) issue, the color at edge of the spot looks different (e.g., yellowish) than that of the main portion of the spot projected by the luminaire.

[0103] As shown in Figure 8, an embodiment of the light source assembly of the linear luminaire 100 may comprise the plurality of LEDs 120 mounted on a PCB 125, condensing lenses 140 over each LED and a frame 160 clamping the lenses over the LED. On the frame 160, there are apertures 161 allowing the light emitting through the lenses 140. The frame 160 further comprises barrier shields 165 between the neighboring LEDs, spacing each lens to prevent light interruption between the neighboring LEDs in Y-axis direction, and reduce the beam angle 012 from the linear luminaire in length direction (see Y-Z plane of Figure 5). The barrier shields 165 may be painted with light absorbing coating or made of black plastic together with the frame 160 as an integral element. The height of the barrier shields is about 0.5 to 1.5 times of the pitch P of the LEDs.

[0104] Figure 9 shows the sectional view of the light source assembly. Figure 10 shows the planar view of the light source assembly. The neighboring LEDs 120 and their respective lenses 140 may be arranged in an off-set configuration, which is shown more clearly in Figure 11. The plurality of LEDs 120 are arranged in a linear array along Y -axis and staggered offset from the center line of the PCB 125, which means when one LED is offset in +X direction, the next nearby LED is offset in -X direction. The offset distance D between the neighboring LED may be about one forth (1 / 4) to one third (1 / 3) of a width WLED of the LED 120. This offset approach is beneficial for solving the CoA issue, providing good light mixing effect at edge of the spot projected from the linear luminaire 100.

[0105] Figure 12 shows a perspective view of a lens 140, illustrating its inner cavity facing the LED 120. There is an array of linear micro-structure 145 on the surface of the inner cavity. The area of the array of linear micro-structure 145 is preferable to be larger than the light emitting surface of individual LED 120. Figure 12 is a sectional view of the lens 140. The array of linear micro-structure 145 comprises a group of linear protrusions (as shown in Figure 13) or grooves (not shown) wherein each one extends along the Y-axis direction, and the protrusions or grooves juxtapose along the X-axis direction. The width WM (in X-axis direction) of each linear protrusion or groove may be less than 1 / 10 of the width WLED of the LED 120, which means the array of linear micro-structure 145 may comprise more than ten linear protrusions or grooves. The length of each linear protrusion or groove may be longer 2024PF80368 14 than the length LLED of the LED 120, in Y-axis direction. The array of linear micro-structure 145 is further beneficial for solving the CoA issue, providing good light mixing effect in X- axis direction.

[0106] Returning to Figure 8, the neighboring LEDs 120 have a staggered offset from each other in the width direction on the PCB 125, and the LEDs 120 include cold white, CW, LEDs and warm white, WW, LEDs. The CW / WW LEDs are grouped as CW groups 121 and WW groups 123. Each group consists of 2 staggered offset LEDs of the same color temperature. To achieve homogeneous light output, the groups of different color temperatures are configured on the PCB 125 in interval.

[0107] Variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality.

[0108] 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.

[0109] If the term "adapted to" is used in the claims or description, it is noted the term "adapted to" is intended to be equivalent to the term "configured to". If the term "arrangement" is used in the claims or description, it is noted the term "arrangement" is intended to be equivalent to the term "system", and vice versa.

[0110] Any reference signs in the claims should not be construed as limiting the scope.

Claims

2024PF80368 15CLAIMS:

1. A linear luminaire (100), comprising: a housing (110) having a first light exit window (111) and a second light exit window (112) separate to the first light exit window, each light exit window extending along a length of the linear luminaire, and both light exit windows are positioned at a first surface (114) of the housing; a plurality of LEDs (120) contained in the housing and arranged linearly along the length of the linear luminaire between the first and second light exit windows; and a reflector arrangement (130) contained in the housing, wherein the reflector arrangement comprises: a first reflective portion (131) configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the first reflective portion is directed towards the first light exit window and converges as the reflected light from the first reflective portion travels towards the first light exit window; and a second reflective portion (132) configured to reflect light emitted by each of the plurality of LEDs such that the reflected light from the second reflective portion is directed towards the second light exit window and converges as the reflected light from the second reflective portion travels towards the second light exit window; wherein the first light exit window (111) and the second light exit window (112) are slits extending along the length of the linear luminaire.

2. The linear luminaire of claim 1, wherein a width (Ws) of each slit is not more than 20% of a width (WL) of the housing (110).

3. The linear luminaire of claim 1, wherein the plurality of LEDs (120) are mounted on an elongate PCB (125), wherein neighboring LEDs have a staggered offset from each other in a direction laterally to the length direction of the PCB, wherein an offset distance (D) between the neighboring LEDs is in a range of one forth (1 / 4) to one third (1 / 3) of a width (WLED) of the LED (120).2024PF80368 164. The linear luminaire of any of claims 1 to 3, wherein an inner surface (113) of the housing, surrounding the plurality of LEDs and the reflector arrangement, is configured to absorb light.

5. The linear luminaire of any of claims 1 to 4, wherein the first reflective portion and second reflective portion are partial cylindrical reflectors, and the first reflective portion and second reflective portion together provide a continuous reflective surface.

6. The linear luminaire of any of claims 1 to 5, wherein the reflector arrangement (130) is positioned at a second surface (115) inside the housing that is opposite to the first surface (114) of the housing comprising the first and second light exit window.

7. The linear luminaire of any of claims 1 to 6, wherein: the first reflective portion is configured to cause the reflected light from the first reflective portion to converge to a first focal line between the first reflective portion and the first light exit window; and the second reflective portion is configured to cause the reflected light from the second reflective portion to converge to a second focal line between the second reflective portion and the second light exit window.

8. The linear luminaire of any of claims 1 to 6, wherein: the first reflective portion is configured to cause the reflected light from the first reflective portion to converge to a first focal line at the first light exit window; and the second reflective portion is configured to cause the reflected light from the second reflective portion to converge to a second focal line at the second light exit window.

9. The linear luminaire of any of claims 1 to 8, wherein the first reflective portion is symmetrical to the second reflective portion with respect to the plurality of LEDs.

10. The linear luminaire of any of claims 1 to 9, further comprising a condensing lens (140) provided between each of the plurality of LEDs and the reflector arrangement.

11. The linear luminaire of claim 10, wherein the condensing lens is a meniscus lens.2024PF80368 1712. The linear luminaire of claim 11, wherein the meniscus lens provides a cavity on its concave side, allowing a respective LED (120) to be mounted within the lens, wherein an array of linear micro-structures (145) is provided on a surface of the cavity, the array of linear micro-structures (145) comprising a group of linear protrusions or grooves, with each one of the linear protrusions or grooves extending along the length of the linear luminaire and the protrusions or grooves juxtaposing laterally to the linear luminaire; wherein a width (WM) of each linear protrusion or groove is less than 1 / 10 of the width (WLED) of the respective LED (120), and a length of each linear protrusion or groove is longer than a length (LtED)of the respective LED (120).

13. The linear luminaire of any of claims 3 to 12, further comprising a first opaque shield (151) positioned between each LED and the first light exit window, and / or, a second opaque shield (152) positioned between each LED and the second light exit window, wherein the first opaque shield and / or the second opaque shield extend in a direction perpendicular to the PCB.

14. The linear luminaire of any of claims 1 to 13, further comprising barrier shields (165) between the neighboring LEDs.

15. The linear luminaire of any of claims 1 to 14, wherein the reflector arrangement comprises a substrate and a specular reflective foil laminated on the substrate.

Images