Luminaire with hollow optical systems

[0001] This application is a continuation of U.S. application Ser. No. 17/866,449 filed Jul. 15, 2022, which is a continuation application of and claims the benefit of priority to U.S. application Ser. No. 17/282,366, filed on Apr. 1, 2021 (now U.S. Pat. No. 11,391,438 issued on Jul. 19, 2022), which is a U.S. national stage application of U.S. International Application PCT/US2019/053675, filed on Sep. 27, 2019, which claims the benefit of priority to U.S. Provisional Application Ser. No. 62/749,044, filed on Oct. 22, 2018, and U.S. Provisional Application Ser. No. 62/741,498, filed on Oct. 4, 2018 the contents of which are hereby incorporated by reference.

[0002] The present technology relates to luminaires with optical systems based on specular reflective surfaces.

[0003] Luminaires with optical systems based on solid transparent materials offer great design opportunities for miniaturization and to shape light provided by point-like light sources. Perfect lossless reflection via TIR, however, imposes constraints on incidence angles and can affect overall system design which is irrelevant to conventional reflective systems provided certain performance penalties are acceptable and transparent optics are not required. As such there has been a long-felt need to mitigate this situation.

[0017] Like symbols in different figures indicate like elements.

[0018] The details of one or more implementations of the technologies described herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the disclosed technologies will become apparent from the description, the drawings, and the claims.

[0019] This disclosure includes technologies directed to luminaires with optical systems based on reflective walls. The optical systems can include light guides, couplers, extractors, diffusers and so forth. Reflection at the reflective surfaces can be specular or partially diffuse. Luminaires with such optical systems are useful where opaque optics are admissible. Components of the optical system can be vacuum formed from suitable sheet material, milled from bulk stock or otherwise formed. Depending on the implementation, highly reflective surfaces may be provided by flat sheet material before forming or applied post forming such by sputtering or other processes. Compared to the requirements for processing solid optics, such manufacture can be easier and more cost effective. These technologies are described in detail below.

[0020] In a first innovative aspect (see, e.g., FIG. 1A-1B, 2 or 7A-7B, 8), a hollow luminaire (100, 200 or 700, 800) includes multiple light-emitting elements (LEEs) (110 or 710); a base (102 or 702) supporting the LEEs (110 or 710); a first wall (150-i or 750-i) and a second wall (150-o or 750-o) each extending along a first direction (e.g., along axis 101 or 701) from a respective first end facing the LEEs (110 or 710) to a respective second end. The first and second walls (150-i, 150-o or 750-i, 750-o) have light-reflective surfaces facing each other. The light-reflective surfaces are spaced apart and form a hollow channel (152 or 752). In one or more cross-sectional planes parallel to the first direction (e.g., along axis 101 or 701), the light-reflective surfaces of the first and second walls (150-i, 150-o or 750-i, 750-o) have first portions (120 or 720) that curve in opposite directions, second portions (130 or 730) that are parallel, and third portions (140 or 740) that curve in like directions. The first portions (120 or 720) are arranged facing the LEEs (110 or 710) to provide an input aperture (122 or 722) that receives light from the LEEs (110 or 710). The third portions (140 or 740) are arranged to provide an exit aperture (142 or 742) that outputs output light into an ambient environment. Additionally, the first and second walls (150-i, 150-o or 750-i, 750-o) are configured to propagate light from the input aperture (122 or 722) to the exit aperture (142 or 742).

[0021] The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In some implementations, the first ends of the first and second walls (150-i, 150-o or 750-i, 750-o) are arranged proximate the LEEs (110 or 710).

[0022] In some implementations, a width (T) of the hollow channel (152 or 752) between the second portions (130 or 730) of the first and second walls (150-i, 150-o or 750-i, 750-o) is uniform.

[0023] In implementations shown in FIGS. 1A-1B and/or 7A-7B, the first and second walls (150-i, 150-o or 750-i, 750-o) extend along a curvilinear path perpendicular to the first direction (i.e., axis 101 or 701). In implementations shown in FIGS. 2 and/or 8, the first and second walls (150-i, 150-o or 750-i, 750-o) extend along a line perpendicular to the first direction (i.e., axis 101 or 701). In some cases of the implementations shown in FIGS. 1A-1B and/or 7A-7B, when the first and second walls (150-i, 150-o or 750-i, 750-o) have closed tubular shapes, the first wall (150-i or 750-i) is nested within the second wall (150-o or 750-o) and arranged to provide a hollow channel (152 or 752) of uniform width (T).

[0024] The first and second walls (150-i, 150-o or 750-i, 750-o) are configured to rotate an angular distribution of light propagating from the input aperture (122 or 722) to the exit aperture (142 or 742). With reference to FIGS. 2 and 3, the angular distribution 145 of output light has a prevalent propagation direction that includes an acute angle with the propagation direction (here, parallel to the z-axis), as shown by the orientation of corresponding lobe 145a in polar plot 191. Optionally, a portion of the light propagating from the input aperture (122) to the exit aperture (142) leaks to the ambient environment through the curved third portion (140) of the first wall (150-i). The angular distribution 145′ of leaked light has a prevalent propagation direction along the propagation direction, as shown by the orientation of corresponding lobe 145b in polar plot 191.

[0025] As another example, with reference to FIGS. 10 and 11, the angular distribution 1045 of output light has a prevalent propagation direction that includes an acute angle with the propagation direction (here, antiparallel to the z-axis), as shown by the orientation of corresponding lobe 1045a in polar plot 1091.

[0026] With reference to FIGS. 8 and 9, the angular distribution 745 of output light has a prevalent propagation direction that includes an obtuse angle with the propagation direction (here, antiparallel to the z-axis), as shown by the orientation of corresponding lobe 745a in polar plot 791. Optionally, a portion of the light propagating from the input aperture (722) to the exit aperture (742) leaks to the ambient environment through the curved third portion (740) of the first wall (750-i). The angular distribution 745′ of leaked light has a prevalent propagation direction along the propagation direction, as shown by the orientation of corresponding lobe 745b in polar plot 791.

[0027] As another example, with reference to FIGS. 4 and 5, the angular distribution 445 of output light has a prevalent propagation direction that includes an obtuse angle with the propagation direction (here, parallel to the z-axis), as shown by the orientation of corresponding lobe 445a in polar plot 491.

[0028] In implementations shown in FIG. 12, the hollow luminaire 1200 includes an endcap diffuser 1270 arranged to extend across the exit aperture 142. The endcap diffuser 1270 is configured to diffuse propagating light into diffused output light. The angular distribution 145* of the diffused output light has a divergence that is smaller than a divergence of the angular distribution 145 of output light by a predetermined value. This is shown with reference to FIGS. 3 and 13, in which the lobe 145a* of the polar plot 191* corresponding to the diffused light output by the hollow luminaire 1200 is wider than the lobe 145a of the polar plot 191 corresponding to the light output by the hollow luminaire 200.

[0029] Generally, depending on the implementation, one or more optical elements may be arranged at or near the exit aperture including one or more diffusers, Fresnel optics or other optical elements. Depending on shape, configuration, arrangement and/or other factors, such optical elements can be used in transmission, reflection or by combination in both transmission and reflection. Diffusers can be traditional, holographic or otherwise. Fresnel optics can include Fresnel lenses, various forms of collapsed refractive structures or other optics. Such optical elements may be configured to extend across a portion or all of the exit aperture and alone or in combination with other elements may help enclose the inside of the luminaire. Enclosing the inside of the luminaire may require additional elements such as endcaps or other elements arranged at the exit aperture or elsewhere in the luminaire. Suitably enclosing the inside of a luminaire can help mitigate contamination of optical surfaces, reduce cleaning requirements and prolong useful service life of the luminaire, for example.

[0030] In some implementations, the third portion (140 or 740) of the first wall (150-i or 750-i) intersects a notional linear extension of the second portion (130 or 730) of the second wall (150-o or 750-o) within the one or more cross-sectional planes. In this manner, it is ensured that there is no line of sight from the exit aperture (142 or 742) to the LEEs (110 or 710).

[0031] In another innovative aspect (see, e.g., FIG. 6), a hollow luminaire (600), includes multiple light-emitting elements (LEEs) (110), and a first and second walls (650-i, 650-o) extending along a first direction (e.g., along the axis 101) from first ends proximate the LEEs (110) to second ends. The first and second walls (650-i, 650-o) have light-reflective surfaces facing each other. The light-reflective surfaces are spaced apart by a hollow channel (652). In a cross-sectional plane parallel to the first direction (e.g., along the axis 101), the light-reflective surfaces of the first and second walls (650-i, 650-o) have first portions (120) that curve in opposite directions and third portions (140) that curve in like directions. The first portions (120) are arranged proximate the LEEs (110) to provide an input aperture (122) for receiving light from the LEEs (110). The third portions (140) are arranged to provide an exit aperture (142) for outputting light into an ambient environment. Additionally, the first and second walls (650-i, 650-o) are configured to propagate light from the input aperture (122) to the exit aperture (142).

[0032] Note that the first and second walls (650-i, 650-o) have openings along the first direction, such that the first portions and the second portions are discontiguous, and therefore spaced apart from each other by a distance D. Thus, the hollow channel (652) of this hollow luminaire (600) also is discontiguous. In this manner, light provided by the LEEs (110) through the input aperture (122) propagates from the first portions (120) to the third portions (140) over the distance D through free space. Note that a combination of (I) the curvatures of the first and second walls (650-i, 650-o) within the first portions (120), (II) the width (T) of the hollow channel (652), and (III) the distance (D) between the first portions (120) and the third portions (140) is configured to ensure that all light provided by the LEEs (110) through the input aperture (122) reaches the third portions (140) through free space.

[0033] The light output by hollow luminaire (600) has a far-field light intensity distribution 191 shown in FIG. 3.

[0034] The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In the implementations shown in FIG. 6, the hollow luminaire (600) includes support structure (660) that affixes the third portions (140) to the first portions (120) at a desired relative separation and orientation. In some implementations, the hollow luminaire (600) can include an endcap diffuser arranged to extend across the exit aperture 142. Here, the endcap diffuser can be implemented as the endcap diffuser 1270 described in connection with FIG. 12.

[0035] In another innovative aspect (see, e.g., FIG. 1A-1B, 2 or 7A-7B, 8), a hollow luminaire (100, 200 or 700, 800) includes multiple light-emitting elements (110 or 710); and a hollow light guide including a pair of walls (150 or 750) each extending along an axis (101 or 701) of the hollow luminaire (100, 200 or 700, 800) from the light emitting elements (110 or 710) to an exit aperture (142 or 742). A first surface of a first (150-i or 750-i) of the pair of walls (150 or 750) is separated from the first surface of a second (150-o or 750-o) of the pair of walls (150 or 750) in a direction orthogonal to the axis (101 or 701) by a channel (152 or 752) along which the hollow light guide directs light from the light emitting elements (110 or 710) to the exit aperture (142 or 742). In cross-section, the walls (150 or 750) define (i) a first portion (120 or 720) extending along the axis (101 or 701) in which the first surfaces of the pair of walls (150 or 750) curve in opposite directions; (ii) a second portion (130 or 730) extending along the axis (101 or 701) following the first portion (120 or 720) in which the first surfaces of the pair of walls (150 or 750) are parallel; and (iii) a third portion (140 or 740) extending along the axis (101 or 701) following the second portion in which the first surfaces of the pair of walls (150 or 750) curve in the same direction. Additionally, the hollow luminaire (100, 200 or 700, 800) includes a base (102 or 702) supporting the plurality of light emitting elements (110 or 710).

[0036] The foregoing and other embodiments can each optionally include one or more of the following features, alone or in combination. In some implementations shown in FIGS. 2, 4, 8, 10, 12, the hollow luminaire (200, 400, 800, 1000 or 1200) has a linear form factor. In other implementations shown in FIGS. 1A-1B, 7A-7B, the hollow luminaire (100 or 700) has a curvilinear form factor. In yet other implementations, the disclosed hollow luminaire can have a serpentine form factor.

[0037] In implementations similar to the ones shown in FIGS. 1A-1B, 7A-7B, the hollow luminaire can have continuous rotational symmetry about the axis (101 or 701). In other implementations, the disclosed hollow luminaire can have discrete rotational symmetry about the axis (101 or 701).

[0038] In implementations shown in FIGS. 1A-1B, 2, 6, 12, the hollow luminaire (100, 200, 600, 1200) includes walls (150, 650) which have third portions (140) configured to enable operation of the hollow luminaire (100, 200, 600, 1200) as a standing lamp, pedestal, or pendant for indirect illumination via ceiling or wall. Examples of far-field light intensity distributions (191, 191*) of light output by this configuration of the disclosed hollow luminaire (100, 200, 600, 1200) are shown in FIGS. 3, 13.

[0039] In implementations shown in FIG. 4, the hollow luminaire (400) includes walls (similar to the walls 150) which have third portions (440) configured to enable operation of the hollow luminaire (400) as a stack light. An example of far-field light intensity distribution (491) of light output by this configuration of the disclosed hollow luminaire (400) is shown in FIG. 5.

[0040] In implementations shown in FIGS. 7A-7B, 8, 10, the hollow luminaire (700, 800) includes walls (750) which have third portions (740) configured to enable operation of the hollow luminaire (700, 800) as a pendant for direct/indirect illumination which can be ceiling mounted or partially recessed. An example of far-field light intensity distributions (791) of light output by this configuration of the disclosed hollow luminaire (700, 800) is shown in FIG. 9.

[0041] In implementations shown in FIG. 10, the hollow luminaire (1000) includes walls (similar to the walls 750) which have third portions (1040) configured to enable operation of the hollow luminaire (1000) as a wall wash. An example of far-field light intensity distribution (1091) of light output by this configuration of the disclosed hollow luminaire (1000) is shown in FIG. 11.

[0042] In each of the above implementations, part of the configuration of the third portion to enable a particular one of the foregoing operations is a configuration of the exit aperture (142, 442, 742, or 1042) to control divergence and direction of emission of the respective hollow luminaire.

[0043] In some implementations, the light guide guides light by reflection of light at the first surfaces of the pair of walls (150 or 750). Here, the reflection is one or more of specular reflection, diffuse reflection, or TIR.

[0044] In some implementations, the walls (150 or 750) include plastic. In some implementations, the first surfaces of the pair of walls (150 or 750) are metallized.

[0045] In some implementations, the disclosed hollow luminaires (100, 200, 400, 600, 700, 800, 1000, 1200) extend along the axis (101, 701) for a length D of 0.1, 0.2, 0.3, 0.5, 1 m. In some implementations, the disclosed hollow luminaires (100, 200, 400, 600, 700, 800, 1000, 1200) are elongated along a path in a plane perpendicular to the axis (101, 701) for an extension L of 0.5, 1, 2, 3, 10 m. In some implementations, the disclosed hollow luminaires (100, 200, 400, 600, 700, 800, 1000, 1200) have hollow channels (152, 752) with a thickness T of 0.005, 0.01, 0.02, 0.03, 0.05 m.

[0046] In the implementations described above, within the third portion (140, 740), the first surfaces of the pair of walls (150 or 750) curve in the same direction away from the axis (101, 701). In some implementations, within the third portion (140, 740), the first surfaces of the pair of walls (150 or 750) curve in the same direction such that a surface of inner wall (150-i or 750-i) is concave and a surface of outer wall (150-o or 750-o) is convex.

[0047] In some implementations, an extension of inner wall (150-i or 750-i) in third portion (140, 740) is configured to occlude direct light emission from LEEs (110 or 710).

[0048] In some implementations, the light emitting elements (110 or 710) include LEDs. Here, the LEDs can include white-light LEDs and/or phosphor coated LEDs.

[0049] A number of embodiments are described. Other embodiments are in the following claims.