WO2014152655A1

WO2014152655A1 - Illumination systems based on indirect illumination devices

Info

Publication number: WO2014152655A1
Application number: PCT/US2014/027583
Authority: WO
Inventors: Ingo Speier; Hans Peter Stormberg
Original assignee: Quarkstar LLC
Current assignee: Quarkstar LLC
Priority date: 2013-03-14
Filing date: 2014-03-14
Publication date: 2014-09-25
Anticipated expiration: 2015-09-14

Abstract

An illumination device includes first light emitting elements (LEEs) optically coupled with first redirecting optics, and one or more second LEEs optically coupled with second redirecting optics; and a support to hold the illumination device spaced apart from and between a target surface and a diffusive surface. The first redirecting optics redirect light emitted by the first LEEs in a first angular range as first redirected light in a second angular range. The second redirecting optics redirect light emitted by the second LEEs in a third angular range as second redirected light in a fourth angular range. Additionally, prevalent directions of the first output light in the second angular range and the second output light in the fourth angular range are towards the diffusive surface and are different from each other, such that light that diffusely reflects from the diffusive surface illuminates two adjacent portions of the target surface.

Description

ILLUMINATION SYSTEMS BASED ON INDIRECT ILLUMINATION DEVICES

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims benefit under 35 U.S.C. § 119(e)(1) of U.S. Provisional Application No. 61/784,031, filed on March 14, 2013, which is incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates to illumination systems that use solid-state based illumination devices providing indirect illumination onto target surfaces that are located in a given environment, such that the solid-state based illumination devices are arranged and configured to illuminate one or more diffusive surfaces from the given environment that are different from the target surfaces.

BACKGROUND

Light sources are used in a variety of applications, such as providing general illumination and providing light for electronic displays (e.g., LCDs). Historically, incandescent light sources have been widely used for general illumination purposes. Incandescent light sources produce light by heating a filament wire to a high temperature until it glows. The hot filament is protected from oxidation in the air with a glass enclosure that is filled with inert gas or evacuated. Incandescent light sources are gradually being replaced in many applications by other types of electric lights, such as fluorescent lamps, compact fluorescent lamps (CFL), cold cathode fluorescent lamps (CCFL), high-intensity discharge lamps, and solid state light sources, such as light-emitting diodes (LEDs).

SUMMARY

The present disclosure relates to illumination systems that use solid-state based illumination devices providing indirect illumination onto target surfaces that are located in a given environment. In accordance with the disclosed technologies, the solid-state based illumination devices are arranged and configured to illuminate one or more diffusive surfaces from the given environment that are different from the target surfaces. A surface is referred to as a diffusive surface because light that impinges on the diffusive surface, in accordance with an arbitrary intensity distribution, is reflected by the diffusive surface in all directions which lie in the half-space adjacent to the surface (and obeys a Lambertian intensity distribution). For example, a solid-state based illumination device can be supported from a ceiling of a room and configured to illuminate the ceiling and/or one or more walls of the room, and in this manner, indirectly illuminate a target surface of the room, e.g., the floor, a desk in the room, a side-panel of an object in the room or a side-panel on a wall of the room. Moreover, illumination of the target surface provided in accordance with the disclosed technologies conforms to glare standards. In general, the disclosed illumination systems can be configured to provide light for particular lighting applications, including office lighting, garage lighting, or cabinet lighting, for instance.

A variety of illumination devices are disclosed that are configured to manipulate light provided by multiple light-emitting elements (LEEs). The LEEs can include LEDs, for example solid-state LEDs. In general, implementations of the illumination devices feature optical couplers (e.g., parabolic, elliptical, conical reflectors) that redirect light emitted by the LEEs in a variety of ways so a variety of intensity distributions can be provided by the illumination devices to one or more diffusive surfaces from a given environment that are different from a target surface.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1A shows a diagrammatic representation an illumination device used to provide indirect illumination.

Figure IB shows an example of an intensity profile of the illumination device of Figure

1A.

Figure 1C shows an example of an illumination system to provide indirect illumination using the illumination device of Figure 1A.

Figures 2A-2B show aspects of an illumination device used to provide indirect intensity distributions.

Figures 3A-3G show aspects of another illumination device used to provide indirect intensity distributions. Figures 4A-4B show aspects of yet another illumination device used to provide indirect intensity distributions.

Reference numbers and designations in the various drawings indicate exemplary aspects, implementations of particular features of the present disclosure.

DETAILED DESCRIPTION

The present disclosure relates to illumination systems configured to indirectly illuminate a target surface in a given environment, e.g., a floor of a room, a garage, etc., using an illumination device arranged and configured to illuminate one or more diffusive surfaces from the given environment that are different from the target surfaces, e.g., a ceiling of the room, the garage, etc. The illumination devices include light emitting elements (LEEs, such as, e.g., light emitting diodes, LEDs) and redirecting optics that are configured to provide indirect illumination on a diffusive area different from the target area. In some implementations, the diffusive area is positioned away from and facing the target area, such as, e.g., the diffusive area is the ceiling of a room when the target area is the floor of (or a desk surface in) the room. In some implementations, the illumination device is configured to provide indirect illumination on two different portions of the target area. Here, two sets of LEEs are controlled, by a user or by preprogrammed internal or external control circuitry, to provide interdependent as well as independent control of illuminations of the two different portions of the target area.

(i) Illumination device used to provide indirect illumination

Figure 1A illustrates a block diagram of an illumination device 150 in which a Cartesian coordinate system is shown for schematic reference. In this example, the coordinate system is oriented relative to the illumination device 150 such that light output by the illumination device 150 in each of first and second output angular ranges 125, 125' has a prevalent direction with a non-zero component that is antiparallel to the z-axis. Providing light in an "angular range" refers to providing light that propagates in a prevalent direction and has a divergence with respect to the propagation direction. In this context, the term "prevalent direction of propagation" refers to a direction along which a portion of an intensity distribution of the propagating light has a maximum. For example, the prevalent direction of propagation associated with the angular range can be an orientation of a lobe of the intensity distribution. Also in this context, the term "divergence" refers to a solid angle outside of which the intensity distribution of the propagating light drops below a predefined fraction of a maximum of the intensity distribution. For example, the divergence associated with the angular range can be the width of the lobe of the intensity distribution. The predefined fraction can be 10%, 5%, 1%, or other values, depending on the lighting application. An angular range includes (i) a divergence of the angular range and (ii) a prevalent direction of propagation of light in the angular range, where the prevalent direction of propagation corresponds to a direction along which a portion of an emitted light intensity distribution has a maximum, and the divergence corresponds to a solid angle outside of which the intensity distribution drops below a predefined fraction of the maximum of the intensity distribution. E.g., the predefined fraction is 5%.

The illumination device 150 can provide indirect illumination to a target surface in a given environment, when the target surface is spaced apart from the illumination device 150 in the positive direction of the z-axis. In this manner, the illumination device 150 is configured to illuminate a diffusive surface in the given environment, when the diffusive surface is spaced apart from the illumination device 150 in the negative direction of the z-axis. An example of such an illumination system is described below in connection with Figure 1C. Example implementations of the illumination device 150 are described below in connection with Figures 2A, 3A-3B and 4A.

The illumination device 150 includes one or more mounts 110, one or more LEEs 112, and redirecting optics 120. The one or more LEEs 112/112' are arranged on one or more surfaces of the mount 110. Figures 2A, 3A-3B and 4A illustrate various examples of illumination devices 200, 300 and 400 in which the LEEs are distributed along a length L (e.g., parallel to the y-axis) of the illumination devices 200, 300 and 400. In Figures 2A and 3A-3B, for example, two rows of LEEs 212/212' are arranged parallel to the y-axis on respective side surfaces of a mount 210. Here, these side surfaces are oriented obliquely to a ceiling 180 when the illumination device 200 or 300 is suspended from the ceiling 180. As another example, in Figure 4A two rows of LEEs 212/212' are arranged along the y-axis direction on respective surfaces of a mount 410 that are oriented substantially parallel to a ceiling 180 when the illumination device 400 is suspended from the ceiling 180. Here, the LEEs, also referred to as light emitters, are devices that emit radiation in one or more regions of the electromagnetic spectrum from among the visible region, the infrared region and/or the ultraviolet region, when activated. Activation of a LEE can be achieved by applying a potential difference across components of the LEE or passing a current through components of the LEE, for example. A light-emitting element can have monochromatic, quasi-monochromatic, polychromatic or broadband spectral emission characteristics. Examples of light-emitting elements include semiconductor, organic, polymer/polymeric light-emitting diodes (e.g., organic light-emitting diodes, OLEDs), other monochromatic, quasi-monochromatic or other light- emitting elements. Furthermore, the term light-emitting element is used to refer to the specific device that emits the radiation, for example a LED die, and can equally be used to refer to a combination of the specific device that emits the radiation (e.g., a LED die) together with a housing or package within which the specific device or devices are placed. Examples of light emitting elements include also lasers and more specifically semiconductor lasers, such as vertical cavity surface emitting lasers (VCSELs) and edge emitting lasers. Further examples include superluminescent diodes and other superluminescent devices.

Returning to Figure 1A, the LEEs 112/112' - arranged on a first/second surface (not shown in Figure 1A) of the mount 110 - emit light, during operation, in a first angular range 115/115' with respect to their optical axes, which can coincide with the normal to an associated surface of the mount 110 on which the LEEs 112 or 112' are arranged. For example, a divergence of the first (second) angular range 115 (or 115') of the light emitted by the LEEs 112 (or 112') can be 150°-180° around optical axes of the LEEs 112 (or 112'). The redirecting optics 120, also referred to as optical couplers, are arranged to receive light in the first (second) angular ranges 115 (115') from the LEEs 112 (112'). Each optical coupler 120 is configured to redirect the light received in the first (second) angular range 115 (115') into output light in first and second output angular ranges 125, 125'. For example, a divergence of each of the first and second output angular ranges 125, 125' of the light output by the optical couplers 120 can be 90°. As described below, the first and second output angular ranges 125, 125' at which light exits the illumination device 150 can depend on the properties of optical couplers 120 (e.g., geometry of the optical interfaces and optical properties of the materials forming the optical couplers). These and other properties of the illumination device 150 can be tailored to provide indirect illumination profiles (see, e.g., intensity distribution 122 shown in Figure IB) desirable for specific lighting applications. It is noted that the angular ranges may be defined relative to one or more directions or planes, for example the z-axis, a plane perpendicular to x or other direction whether parallel, perpendicular or oblique to axes of the Cartesian coordinate system.

In the examples illustrated in Figures 2A, 3A-3B and 4A, the redirecting optics 120 are elongated along the length L (e.g., parallel to the y-axis) of the illumination devices 200, 300 and 400.

For example, in Figure 2A the illumination device 200 includes two redirecting optics 220, 220', such that each of the redirecting optics includes a single reflector supported on an associated surface of mount 210 that is oriented substantially parallel to a ceiling 180 when the illumination device 200 is suspended from the ceiling 180.

As another example, in Figures 3A-3B the illumination device 300 includes two redirecting optics 320, 320'. Each of the redirecting optics 320 (320') includes a first refiector 326 (326') supported on an associated surface of mount 210, and a second reflector 324 (324') attached to an associated second surface of the mount 210, such that each of the surfaces of the mount 210 that support the first 326 (326') and second 324 (324') reflectors of the redirecting optics 320 (320') are oriented substantially parallel to a ceiling 180 when the illumination device 300 is suspended from the ceiling 180. In this manner, the first 326 (326') and second 324 (324') reflectors of each of the redirecting optics 320 (320') can be arranged to face each other and to form a respective optical coupler.

As yet another example, in Figure 4A the illumination device 400 includes two redirecting optics 420, 420'. Each of the redirecting optics 420, 420' includes a single refiector attached to an associated surface of a mount 410 that is oriented substantially parallel to a ceiling 180 when the illumination device 400 is suspended from the ceiling 180.

Returning to Figure 1A, the illumination device 150 is configured to output indirect light originating from the LEEs 112 (112'). The LEEs 112 (112') may be organic or inorganic light- emitting diodes or a combination thereof. In general, the illumination device 150 is configured to generate light of a desired chromaticity. In many applications, illumination device 150 is configured to provide broadband light. Broadband light can be generated using nominally white or off-white LEEs or colored LEEs whose emissions are mixed to provide white light. Alternatively, or additionally, white light can be generated using an LEE configured to emit pump light (e.g., blue, violet or ultra-violet light) in conjunction with a wavelength conversion material. For example, in certain implementations, LEEs 112 (112') include GaN-based pump LEDs with an overlying phosphor layer (e.g., YAG) that creates yellow, red and/or green components to produce white light. In some implementations, the illumination device 150 may be configured to provide colored light (e.g., yellow, red, green, blue light). Different LEEs 112 (112') in the illumination device 150 can be configured to emit nominally different light under operating conditions, for example yellow, red, green, blue, white or other color light.

In general, relatively energy efficient LEEs 112 (112') can be used. For example, LEEs 112 (112') can have an output efficiency of about 50 lm/W or more (e.g., about 75 lm/W or more, about 100 lm/W, about 125 lm/W or more, about 150 lm/W or more). In certain implementations, LEEs 112 conduct current greater than about 350 mA (e.g., 400 niA or more, 450 mA or more, 500 mA or more). LEEs may be surface mount devices.

The number of LEEs 112 (112') in an illumination device 150 can vary. In some implementations, the illumination device 150 can include relatively few LEEs (e.g., 10 or fewer). In some implementations, the illumination device 150 can include a large number of LEEs (e.g., 100 or more). In many applications, however, the illumination device 150 includes between 4 and 100 LEEs.

Each of the optical couplers 120 is configured to receive light from one or more of the LEEs 112 (112') through an entrance aperture of the optical coupler. In implementations that feature multiple optical couplers, they may be integrally formed. Each optical coupler can be configured to provide a predetermined amount of light at an exit aperture of the optical coupler. For this purpose, each optical coupler is optically coupled with the corresponding LEEs and the light guide. Adjacent optical couplers may be optically isolated or optically coupled to control cross talk and/or collimation of light or other functions in one or more planes parallel to the optical axes of the optical couplers or in other directions.

The optical couplers are configured to allow coupling of a predetermined amount of light from one or more of the LEEs into the optical couplers and a predetermined amount of that light is provided at the exit apertures of the optical couplers. Each optical coupler is configured to transform light as it interacts with the optical coupler between the entrance aperture and the exit aperture. Such transformations, also referred to as conditioning, may be regarded as transformations of the phase space of light including collimation of light (e.g. causing a reduction of the divergence of the coupled light) or other transformations, and/or preservation of etendue, light flux and/or other parameters, for example.

Optical couplers can include one or more optical elements including non-imaging dielectric TIR concentrators, such as CPC (compound parabolic concentrators), CECs (compound elliptical concentrators), CHC (compound hyperbolic concentrators), tapered or untapered portions, light pipes, segmented concentrators, other geometry concentrators, one or more lenses or other optical elements, for example. In some implementations, optical couplers 120 and LEEs 112 (and/or 112') are integrally formed as a single component.

The illumination device 150 may include a number of optical couplers with the same or different configuration. Optical couplers may have equal or different profiles or cross sections in different directions. In some implementations, optical couplers may have varying configurations depending on their location within a cluster or group of optical couplers. For example, optical couplers proximate the ends of an elongate illumination device may be configured with properties different from those of optical couplers near the center of the illumination device. Like considerations may apply in implementations in which the optical couplers are disposed in clusters proximate an optical axis. For example, optical couplers proximate the periphery of a cluster may be configured with properties different from those proximate the optical axis. An optical coupler may have rotationally symmetric and/or asymmetric cross sections, for example it may have parabolic, elliptical, circular, hyperbolic, triangular, square, rectangular, hexagonal or other regular or irregular polygonal or other cross sections.

In some implementations, one or more portions or all of the optical coupler 120 may be made of a solid transparent body (not illustrated) configured to propagate light internally and solely, partially or not at all, depending on whether a specular reflective coating is employed on the outside of the solid transparent body, rely on TIR, or may be configured to provide a through hole that is partially or fully reflectively coated on one or more optical surfaces. Depending on the implementation, one or more optical couplers 120 may be configured as hollow, reflectively coated non-imaging optical couplers. One or more of the optical couplers 120 may include a dielectric collimating optic configured to provide a predetermined collimation angle. The collimation angle may be determined by the length and/or shape of respective surfaces of the optical coupler 120, for example. An optical coupler 120 may be configured to provide substantially equal collimation about an optical axis in rotationally symmetrical configurations or may provide different collimation in different directions with respect to an optical plane of the optical coupler 120 and/or other component of the illumination device, for example.

The light output by an illumination device 150 in first and second output angular ranges 125/125' represents an intensity distribution, which may be customized (e.g., based on a user specification), at least, by choice of redirecting optics 120, and a spatial position of the LEEs 112/112' with respect to the redirecting optics 120. Moreover, the illumination device 150 can be configured to enable separate power control of the LEEs 112 (which emit the light output by illumination device 150 in the first output angular range 125) and the LEEs 112' (which emit light output by illumination device 150 in the second output angular range 125'). In this manner, the illumination device 150 can provide separately laterally-controllable light intensity distributions 125 (e.g., rightward), 125' (e.g., leftward).

(ii) Illumination provided by the illumination devices of Figure 1A Figure IB shows a section of an example light intensity profile 122 of the illumination device 150. Here, the illumination device 150 can be elongated along the y-axis (perpendicular to the sectional plane of Figure 1A). Lobes 125a, 125b of the light intensity profile 122 correspond to light output by the illumination device 150 in the x-z cross-section of the first and second output angular ranges 125, 125'.

As described in detail below, composition and geometry of components of the illumination device 150 can affect the light intensity profile 122. For the example illustrated in Figure IB, the illumination device 150 is configured to direct substantially all of the indirect (background) light 125 a, 125b into a range of polar angles between +95° and +105°, and between -95° and -105° in a cross-sectional plane (x-z) of the illumination device 150. In this case, the forward direction (0 degrees) is the direction of the z-axis and can be toward the floor 190 for illumination system 100 illustrated in Figure 1C.

In some implementations, multiple correlated color temperature (CCT) or other chromaticity light sources can be included in the illumination device 150. These multiple CCT light sources can be controlled (e.g., certain LEEs may be selectively powered on/off, dimmed, etc.) to interpolate between the CCTs and intensity levels in lobe 125a, or in lobe 125b, or both lobes. In this manner, the CCT corresponding to the lobes 125a and 125b can be modified from a bluish to a reddish CCT throughout the day to accomplish certain bioluminous effects, for instance.

Moreover, as the first set of LEEs 112 can be powered independently from the second set of LEEs 1 12' of the illumination device 150, multiple configurations of the light intensity profile 122 shown in Figure IB are possible for the illumination device 150, as indicated in Table 1 below. For instance, the first set of LEEs 112 is powered (or is ON) if a first switch of a power source is closed, and the first set of LEEs 112 is not powered (or is OFF) if the first switch is open. Further, the second set of LEEs 112' is powered (or is ON) if a second switch of the power source is closed, and the second set of LEEs 112' is not powered (or is OFF) if the second switch is open.

Table 1

In accordance with the various manners of powering the first set of LEEs 112 and the second set of LEEs 112' shown in Table 1, indirect lobes 125a, 125b of the illumination pattern 122 in the x-z cross-section are independently controlled with respect to each other.

(iii) Illumination system including the illumination devices of Figure 1A

Figure 1C illustrates a block diagram of an illumination system 100 in which a Cartesian coordinate system is shown for schematic reference. The illumination system 100 is configured to illuminate a target surface 190 in a given environment, e.g., the floor of a room, and includes the illumination device 150 described above in connection with Figure 1A. As noted above, the illumination device 150 includes LEEs configured to emit light, and redirecting optics coupled with the LEEs and configured to redirect the emitted light as output light in first and second angular ranges 125, 125'. Moreover, the illumination device 150 provides indirect illumination to the target surface 190 by illuminating a diffusive surface 180 of the environment (e.g., the ceiling of the room) different from the target area 190, in accordance with the first and second angular distributions 125, 125'. Here, the first and second angular distributions 125, 125' are referred to as the first and second indirect angular distributions 125, 125'. In this manner, the diffusive surface 180 redirects the light received from the illumination device 150 in the first and second indirect angular distributions 125, 125', such that the target surface 190 is illuminated with redirected light, in accordance with diffuse angular distributions 152, 152'. In some implementations, the diffuse angular distributions 152, 152' of light redirected by the diffusive surface 180 are substantially Lambertian distributions.

In some implementations, the illumination device 150 is elongated along the y-axis, perpendicular to the page. In other implementations, the illumination device 150 is non- elongated, e.g. the illumination device 150 can have rotational symmetry around an axis parallel to the z-axis. In some implementations, the illumination device 150 is configured to allow interdependent as well as independent control of the indirect illuminations 125, 125 ' by a user or by pre-programmed internal or external control circuitry. For example, two rows of multiple LEEs (distributed along the y-axis) coupled with corresponding redirecting optics can be powered to emit light in the respective first and second indirect angular distributions 125, 125' independently from each other. For instance, only the "right-side" ("left-side") row of multiple LEEs can be powered to provide the first (second) indirect lobe 125 a (125b) of the illumination distribution 122 to illuminate only the right-side (left-side) of the floor 190, with respect to the position of the illumination device 150. Alternatively, both right-side and left- side rows of multiple LEEs can be powered concurrently to provide both indirect lobes 125 a, 125b of the illumination distribution 122 to illuminate both right and left-side of the floor 190. The foregoing independent power control of the light sources responsible for the first and second lobes 125 a, 125b of the indirect illumination distribution 122 can be accomplished by independently turning on or off some or all of the multiple LEEs of the two rows (as shown above in Table 1), or independently dimming some or all of the multiple LEEs of the two rows. In the example illustrated in FigurelC, the illumination device 150 is supported by the ceiling 180 through a support 108. In some implementations, the support 108 can be wires, rods, or combinations thereof. Here, the illumination system 100 can be configured to provide a particular light intensity distribution on the target surface 190, subject to given constraints. For example, the illumination system 100 can be configured to uniformly illuminate the floor 190 (e.g., to obtain 10%, 20%, etc., overlap between diffuse angular ranges 152 and 152' at the floor level). Configurations of the illumination system 100 can be implemented by selecting appropriate combinations of system parameters such as (i) first and second indirect angular ranges 125, 125' of indirect light output by the illumination device 150; and (ii) distance "H" from the ceiling 180 to an effective center of the illumination device 150, e.g., H = 1ft, 3ft, etc. Configurations of the illumination system 100 may further be based on reflectivity, color, uniformity, geometry and/or other properties of the ceiling 180.

(iv) First illumination device used to provide indirect illumination

Figure 2A shows an example of an illumination device 200 to be used for providing indirect illumination of the target surface 190 in the illumination system 100 of Figure 1C. The illumination device 200 includes a mount 210, first LEEs 212, second LEEs 212', and corresponding redirecting optics 220 and 220'. Further in this example, the illumination device 200 is supported by a ceiling 180 through a support 108. In this example, the coordinate system is oriented relative to the illumination device 200 such that light output by the illumination device 200 in each of first and second indirect angular ranges 125, 125' has a prevalent direction with a non-zero component that is antiparallel to the z-axis. When used as part of the illumination system 100 of Figure 1C, the illumination device 200 provides indirect illumination to the target surface 190, which is spaced apart from the illumination device 200 in the positive direction of the z-axis. In some implementations, the components of the illumination device 200 are elongated along the y-axis (perpendicular to the page.)

In some implementations, the mount 210 can be formed of extruded aluminum. The first LEEs 212 are operatively disposed on a first side surface of the mount 210. The second LEEs 212' are operatively disposed on a second side surface of the mount 210, such that the first and second side surfaces are oriented obliquely with respect to each other and to the z-axis. The first LEEs 212 emit, during operation, light in a first angular range with respect to the z-axis. The second LEEs 212' emit, during operation, light in a second angular range with respect to the z- axis. At least prevalent directions of propagation of light in the first and second angular ranges are different from each other at least perpendicular to the y-axis. In some implementations, the first LEEs 112 and the second LEEs 112' are operatively arranged in two rows. Each of the two rows of LEEs 212, 212' includes multiple LEEs distributed along the y-axis direction on the respective first and second surfaces of the mount 210. Additionally, the two rows of multiple LEEs 212 and 212' can be powered to emit light independently from each other.

Each of the redirecting optics 220, 220' includes a single reflector attached to a corresponding surface of the mount 210 that is oriented substantially parallel to the ceiling 180 when the illumination device 200 is suspended from the ceiling. In some implementations, a side of the single reflector that faces the ceiling 180 is mostly concave, as illustrated in Figure 2A. In this manner, the redirecting optics 220, 220' are configured to cast light emitted by the first and second LEEs 212, 212' in first and second indirect angular ranges 125, 125' corresponding to the indirect intensity distribution of the illumination device 200. A divergence of each of the first and second indirect angular ranges 125, 125' is smaller than a divergence of the first and/or second angular range at least in a plane perpendicular to the y-axis. Additionally, a prevalent direction of propagation of light in each of the first and second indirect angular ranges 125, 125' has a non-zero component antiparallel with a normal to the z-axis. In this manner, the illumination device 200 can be used as part of the illumination system 100 shown in Figure 1C to illuminate (in the first and second indirect angular ranges 125, 125') the ceiling 180. In this example, the ceiling 180 can diffusely reflect the light output by the illumination device 200 to provide indirect illumination of a target surface 190 located in the positive direction of the z-axis (e.g., on the floor).

In general, the illumination device 200 can be configured in a variety of form factors. For example, the illumination device 200 can be designed to be installed in a ceiling 180 with ceiling panels. As another example, the illumination device 200 is configured as a suspended illumination device 200 (e.g., pendant luminaire or troffer luminaire) using one or more rods 108. In an aspect, the illumination device 200 may have a length L (along the y-axis). For example, the illumination device 200 can have a 2' x 2' or 2' x 4' footprint (e.g., in the x-y plane), corresponding to the size of conventional fixtures that support fluorescent luminaires. In some implementations, the redirecting optics 220, 220' may be closed off at two ends by walls in the x-z plane (not shown in Figure 2A). The end- walls that close off the redirecting optics can be configured to reflect components of incident light in the first and second indirect angular ranges 125, 125' along the y-axis. In some implementations, the illumination device 200 can be used alone or in multiples to form a suitably sized troffer, for example. In some implementations, the illumination device 200 includes a diffusor plate (not shown in Figure 2) positioned, for example, to cover the opening formed by the redirecting optics 220, 220' and the end-walls (on the ceiling-side of the illumination device 200) to protect the optical components of the illumination device 200 from dust or other environmental effects.

Figure 2B shows a section of light intensity profile 222 of suspended illumination device

200. Here, the illumination device 200 can be elongated along the y-axis (perpendicular to the sectional plane of Figure 2A). As such, lobes 225a, 225b of the light intensity profile 222 correspond to light output by the illumination device 200 in the x-z cross-section of the first and second indirect angular ranges 125, 125'.

Arrangement and shape of components of the redirecting optics 220, 220' determine the light intensity profile 222. For the example illustrated in Figure 2B, the reflector of each of the redirecting optics 220, 220' is arranged and configured to direct substantially all of the indirect (backward) light 225a, 225b into a range of polar angles between +90° and +130°, and between - 90° and -130° in a cross-sectional plane (x-z) of the illumination device 200. In this case, the forward direction (0 degrees) is the direction of the z-axis and can be toward the floor 190 for illumination system 100 illustrated in Figure 1C.

As the first LEEs 212 can be powered independently from the second LEEs 212', multiple configurations of the light intensity profiles shown in Figure 2B are possible for the illumination device 200, as indicated in Table 2 below. For instance, the first LEEs 212 are powered (or are ON) if a first switch of a power source is closed, and the first LEEs 212 are not powered (or are OFF) if the first switch is open. Further, the second LEEs 212' are powered (or are ON) if a second switch of the power source is closed, and the second LEEs 212' are not powered (or are OFF) if the second switch is open.

Table 2

LEE power combinations Lobe 225a Lobe 225b first LEEs 212 0N;

ON ON

second LEEs 212' ON

first LEEs 212 0N;

ON OFF

second LEEs 212' OFF

first LEEs 212 0FF;

OFF ON

second LEEs 212' ON

first LEEs 212 0FF;

OFF OFF

second LEEs 212' OFF

In accordance with the various manners of powering the first and second LEEs 212, 212' shown in Table 2, indirect lobes 225a, 225b of the illumination pattern 222 in the x-z cross- section are independently controlled with respect to each other.

(v) Second illumination device used to provide indirect illumination

Figure 3 A shows a sectional view of an illumination device 300 to be used for providing indirect illumination of the target surface 190 in the illumination system 100 of Figure 1C. The illumination device 300 includes a mount 210, first LEEs 212, second LEEs 212', and corresponding redirecting optics 320 and 320'. Further in this example, the illumination device 300 is supported by a ceiling 180 through supports 108/108'. Here, the coordinate system is oriented relative to the illumination device 300 such that light output by the illumination device 300 in each of first and second indirect angular ranges 125, 125' has a prevalent direction with a non-zero component that is antiparallel to the z-axis. When used as part of the illumination system 100 of Figure 1C, the illumination device 300 provides indirect illumination to a target surface 190, which is spaced apart from the illumination device 300 in the positive direction of the z-axis.

Figure 3B shows an exploded, perspective view of the illumination device 300 with components which are elongated along the y-axis. In this case, the first 212 and second 212' LEEs are operatively arranged in two rows. Each of the two rows of LEEs 212, 212' includes multiple LEEs distributed along the y-axis direction on respective first and second side surfaces of the mount 210. In this case, the first and second side surfaces are oriented obliquely to the ceiling 180 when the illumination device 300 is suspended from the ceiling 180. The two rows of multiple LEEs 212, 212' can be powered to emit light independently from each other.

Each of the redirecting optics 320 (320') includes a first reflector 326 (326') supported on a corresponding first surface of mount 210, and a second reflector 324 (324') attached to a corresponding second surface of the mount 210. In this case, the first and second surfaces of the mount 210 that support the first 326 (326') and second 324 (324') reflectors of the redirecting optics 320 (320') are oriented substantially parallel to the ceiling 180 when the illumination device 300 is suspended from the ceiling 180. In this manner, the first 326 (326') and second 324 (324') reflectors of each of the redirecting optics 320 (320') can be arranged to face each other with respective mostly concave sides and to form an associated optical coupler, as illustrated in Figure 3 A. Further in this manner, the redirecting optics 320, 320' are arranged and configured to cast light emitted by the first and second LEEs 212, 212' in first and second indirect angular ranges 125, 125' corresponding to the indirect intensity distribution of the illumination device 300. In some implementations, a prevalent direction of propagation of light in each of the first and second indirect angular ranges 125, 125' has a non-zero component antiparallel with the z- axis.

In this manner, the illumination device 300 can be used as part of the illumination system 100 shown in Figure 1C to illuminate (in first and second indirect angular ranges 125, 125') the ceiling 180. In this example, the ceiling 180 can diffusely reflect the light output by the illumination device 300 to provide indirect illumination of a target surface 190 located in the positive direction of the z-axis (e.g., on the floor).

In the elongated implementation of the illumination device 300, the redirecting optics 320, 320' may be closed off at two ends by walls 370, 370' in the x-z plane (as shown in Figure 3B). The end-walls 370, 370' that close off the redirecting optics 320, 320' can be configured to reflect components of incident light in the first and second indirect angular ranges 125, 125' along the y-axis.

Figures 3C-3F show aspects of an example implementation of the second reflector 324'. As described above in connection with Figure 3B, the second reflector 324' forms, along with the first reflector 326', the redirecting optics 320'. The redirecting optics 320, 320' redirect light emitted by the first and second LEEs 212, 212' and output the redirected light in the first and second indirect angular ranges 125, 125'. The first and second indirect angular ranges 125, 125' into which the illumination device 300 outputs light are determined at least in part by the choice of curvatures Rl , R2 and R3 of a cross-section of the second reflector 324'. In this example, the curvatures are approximately Ri = 130 mm, R₂ = 90 mm, and R₃ = 35 mm. Figures 3C and 3E- 3F show that the second reflector 324' may either be semi-transparent or may have multiple apertures 328 separated by a pitch Δ as indicated in Figure 3E. In some implementations, each of the apertures 328 of the second reflector 324' may be aligned with a corresponding one of the second LEEs 212' distributed along the y-axis. In this case, the pitch Δ corresponds to a separation of the second LEEs 212' along the y-axis. In some implementations, the pitch Δ can be approximately 12 mm. Figure 3F shows that an aperture 328 fans out from a first aperture end, near an edge of the second reflector 324', corresponding to an approximate position 329 of a LEE from among the second LEEs 212' with respect to the aperture, to a second aperture end near an opposite edge of the second reflector 324'. In some implementations, the aperture width at the LEE location 329 can be 4 mm, for example, and at the second aperture end can be 8 mm, for example.

In this manner, part of the indirect intensity distribution generated by the illumination device 300 that results from light from the first and second LEEs 212, 212' is transmitted through apertures 328 and can illuminate a portion of the ceiling 180 of a room directly above the illumination device 300, while another part of the indirect intensity distribution results from light directed by the redirecting optics 320, 320' in first and second indirect angular ranges 125, 125 ' .

A suspended illumination device 300 may be fabricated in various lengths L, e.g., L = 4ft or 8ft, and installed in a linear arrangement for example in an office environment. Such illumination devices may emit about 12501m/linear foot and provide a peak intensity of above 1500cd in the indirect light distribution.

In some implementations, multiple illumination devices 300 can be installed in a space to provide desired illumination for a target surface and/or a ceiling area. In general, the number, density, and orientation of the illumination devices in the space can vary as desired to provide an overall intensity profile suitable of the target surface. In some implementations, arrays of illumination devices 300 can be arranged on a ceiling.

Figure 3G shows a section of light intensity profile 322 of suspended illumination device

300. Here, the illumination device 300 can be elongated along the y-axis (perpendicular to the sectional plane of Figure 3A). As such, lobes 325a, 325b of the light intensity profile 322 correspond to light output by the illumination device 300 in the x-z cross-section of the first and second indirect angular ranges 125, 125'.

Arrangement and shape of components of the redirecting optics 320, 320' determine the light intensity profile 322. For the example illustrated in Figure 3G, the first reflector 326 (326') and second reflector 324 (324') of the redirecting optics 220 (220') are configured to direct substantially all of the indirect (backward) light 325a, 325b into a range of polar angles between +90° and +110°, and between -90° and -110° in a cross-sectional plane (x-z) of the illumination device 300. In this case, the forward direction (0 degrees) is the direction of the z-axis and can be toward the floor 190 for illumination system 100 illustrated in Figure 1C.

As the first LEEs 212 can be powered independently from the second LEEs 212', multiple configurations of the light intensity profiles shown in Figure 3G are possible for the illumination device 300, as indicated in Table 3 below. For instance, the first LEEs 212 are powered (or are ON) if a first switch of a power source is closed, and the first LEEs 212 are not powered (or are OFF) if the first switch is open. Further, the second LEEs 212' are powered (or are ON) if a second switch of the power source is closed, and the second LEEs 212' are not powered (or are OFF) if the second switch is open.

Table 3

In accordance with the various manners of powering the first and second LEEs 212, 212' shown in Table 3, indirect lobes 325a, 325b of the illumination pattern 322 in the x-z cross- section are independently controlled with respect to each other. (vi) Third Illumination Device Used to Provide Indirect Illumination

Figure 4A illustrates another example of an illumination device 400 to be used for providing indirect illumination of the target surface 190 in the illumination system 100 of Figure 1C. The illumination device 400 includes a mount 410, first LEEs 212, second LEEs 212', and corresponding redirecting optics 420 and 420'. Here, the illumination device 400 is supported by a ceiling 180 through a support 108. In this example, the coordinate system is oriented relative to the illumination device 400 such that light output by the illumination device 400 in each of first and second indirect angular ranges 125, 125' has a prevalent direction with a non-zero component that is antiparallel to the z-axis. When used as part of the illumination system 100 of Figure 1C, the illumination device 400 provides indirect illumination to a target surface 190, which is spaced apart from the illumination device 400 in the positive direction of the z-axis. In some implementations, the components of the illumination device 400 are elongated along the y- axis (perpendicular to the page.)

In some implementations, the mount 410 can be formed of extruded aluminum. The first LEEs 212 are operatively disposed on a first side surface of the mount 210. The second LEEs 212' are operatively disposed on a second side surface of the mount 210, such that the first and second side surfaces are oriented parallel to the ceiling 180 when the illumination device 400 is suspended from the ceiling 180. The first LEEs 212 emit, during operation, light in a first angular range with respect to the z-axis. The second LEEs 212' emit, during operation, light in a second angular range with respect to the z-axis. In this case, prevalent directions of propagation of light in the first and second angular ranges are substantially equal. In some implementations, the first LEEs 112 and the second LEEs 112' are operatively arranged in two rows. Each of the two rows of LEEs 212, 212' includes multiple LEEs distributed along the y-axis direction on the respective first and second surfaces of the mount 210. Additionally, the two rows of multiple LEEs 212 and 212' can be powered to emit light independently from each other.

Each of the redirecting optics 420, 420' includes a single reflector attached to a corresponding surface of the mount 410 that is oriented substantially parallel to the ceiling 180 when the illumination device 400 is suspended from the ceiling. In some implementations, a side of the single reflector that faces away from the ceiling 180 is mostly concave, as illustrated in Figure 4A. In this manner, the redirecting optics 420, 420' are configured to cast light emitted by the first and second LEEs 212, 212' in first and second indirect angular ranges 125, 125' corresponding to the indirect intensity distribution of the illumination device 400. A divergence of each of the first and second indirect angular ranges 125, 125' is smaller than a divergence of the first and/or second angular range at least in a plane perpendicular to the y-axis. Additionally, a prevalent direction of propagation of light in each of the first and second indirect angular ranges 125, 125' has a non-zero component antiparallel with a normal to the z-axis. In this manner, the illumination device 400 can be used as part of the illumination system 100 shown in Figure 1C to illuminate (in the first and second indirect angular ranges 125, 125 ') the ceiling 180. In this example, the ceiling 180 can diffusely reflect the light output by the illumination device 400 to provide indirect illumination of a target surface 190 located in the positive direction of the z-axis (e.g., on the floor). Similar to the example illumination device 300 illustrated in Figures 3A to 3F, the redirecting optics 420, 420' can include apertures or other transparent portions to allow illumination of a portion of the ceiling 180 directly above the illumination device 400.

In general, the illumination device 400 can be configured in a variety of form factors. For example, the illumination device 400 can be designed to be installed in a ceiling 180 with ceiling panels. As another example, the illumination device 400 is configured as a suspended illumination device 400 (e.g., pendant luminaire or troffer luminaire) using one or more rods 108. In an aspect, the illumination device 400 may have a length L (along the y-axis). For example, the illumination device 400 can have a 2' x 2' or 2' x 4' footprint (e.g., in the x-y plane), corresponding to the size of conventional fixtures that support fluorescent luminaires.

In some implementations, the redirecting optics 420 and 420' may be closed off at two ends by walls in the x-z plane (not shown in Figure 4) in analogy with the end- walls 370 of illumination device 300. The end- walls that close off the redirecting optics 420 and 420' can be configured to reflect components of incident light 125, 125' along the y-axis.

Figure 4B shows a section of light intensity profile 422 of suspended illumination device 400. Here, the illumination device 400 can be elongated along the y-axis (perpendicular to the sectional plane of Figure 4A). As such, lobes 425a, 425b of the light intensity profile 422 correspond to light output by the illumination device 400 in the x-z cross-section of the first and second indirect angular ranges 125, 125'. Arrangement and shape of components of the redirecting optics 420, 420' determine the light intensity profile 422. For the example illustrated in Figure 4B, the reflector of each of the redirecting optics 420, 420' is arranged and configured to direct substantially all of the indirect (backward) light 425a, 425b into a range of polar angles between +90° and +110°, and between - 90° and -110° in a cross-sectional plane (x-z) of the illumination device 400. In this case, the forward direction (0 degrees) is the direction of the z-axis and can be toward the floor 190 for illumination system 100 illustrated in Figure 1C.

As the first LEEs 212 can be powered independently from the second LEEs 212', multiple configurations of the light intensity profiles shown in Figure 4B are possible for the illumination device 400, as indicated in Table 4 below. For instance, the first LEEs 212 are powered (or are ON) if a first switch of a power source is closed, and the first LEEs 212 are not powered (or are OFF) if the first switch is open. Further, the second LEEs 212' are powered (or are ON) if a second switch of the power source is closed, and the second LEEs 212' are not powered (or are OFF) if the second switch is open.

Table 4

In accordance with the various manners of powering the first and second LEEs 212, 212' shown in Table 4, indirect lobes 425a, 425b of the illumination pattern 422 in the x-z cross- section are independently controlled with respect to each other.

In general, the LEEs 212, 212' and the redirecting optics 220, 220', or 320, 320' or 420, 420' may be configured to provide spatial positions and/or optical properties (spatial shape of reflective surfaces, index of refraction of solid material, spectrum of emitted) to provide a predetermined indirect illumination distribution.

The preceding figures and accompanying description illustrate example methods, systems and devices for illumination. It will be understood that these methods, systems, and devices are for illustration purposes only and that the described or similar techniques may be performed at any appropriate time, including concurrently, individually, or in combination. In addition, many of the steps in these processes may take place simultaneously, concurrently, and/or in different orders than as shown. Moreover, the described methods/devices may use additional steps/parts, fewer steps/parts, and/or different steps/parts, so long as the methods/devices remain appropriate.

In other words, although this disclosure has been described in terms of certain aspects or implementations and generally associated methods, alterations and permutations of these aspects or implementations will be apparent to those skilled in the art. Accordingly, the above description of example implementations does not define or constrain this disclosure. Further implementations are described in the following claims.

Claims

1. An illumination system comprising:

an illumination device comprising one or more first light emitting elements (LEEs) optically coupled with first redirecting optics, and one or more second LEEs optically coupled with second redirecting optics; and

a support to hold the illumination device spaced apart from and between a target surface and a diffusive surface,

wherein the first redirecting optics are arranged and configured to redirect light emitted by the one or more first LEEs in a first angular range as first redirected light in a second angular range,

wherein the second redirecting optics are arranged and configured to redirect light emitted by the one or more second LEEs in a third angular range as second redirected light in a fourth angular range, and

wherein prevalent directions of the first output light in the second angular range and the second output light in the fourth angular range are towards the diffusive surface and are different from each other, such that light that diffusely reflects from the diffusive surface illuminates two adjacent portions of the target surface.

2. The illumination system of claim 1, wherein a combination of the second and fourth angular ranges and a distance from the target surface at which the illumination device is held by the support is selected such that an overlap of the two adjacent portions of the target surface is less than a predetermined fraction of any one of the portions.

3. The illumination system of claim 1, wherein the first and second LEEs are powered independently.

4. The illumination system of claim 1, wherein the first and second LEEs comprise solid-state light-emitting diodes.

5. The illumination system of claim 4, wherein the first and second LEEs have multiple CCTs and are powered to interpolate between the multiple CCTs.

6. The illumination system of claim 4, wherein the first and second LEEs have multiple chromaticities and are powered to interpolate between the multiple chromaticities.

7. The illumination system of claim 4, wherein divergences of the first and third angular ranges are smaller than divergences of the second and fourth angular ranges, respectively.

8. The illumination system of claim 1 , wherein the target surface is a floor of a room, and the diffusive surface is a ceiling of the room.

9. The illumination system of claim 1, wherein

the illumination device further comprises a mount having a longitudinal dimension and a transverse dimension shorter than the longitudinal dimension;

the first LEEs are operatively disposed on a first surface of the mount, and the second LEEs are operatively disposed on a second surface of the mount, the first and second surfaces being elongated along the longitudinal direction, the first and second LEEs being distributed along the longitudinal dimension, such that the first and second surfaces are oriented obliquely with respect to each other and to the diffusive surface, and such that at least prevalent directions of propagation of light in the first and third angular ranges are different from each other at least perpendicular to the longitudinal dimension;

the first redirecting optics are coupled with the first LEEs and comprise a first reflector arranged on a third surface of the mount, the first reflector being elongated along the longitudinal dimension and facing the diffusive surface with a concave side; and

the second redirecting optics are coupled with the second LEEs and comprise a second reflector arranged on a fourth surface of the mount, the third and fourth surfaces being parallel to the diffusive surface, the second reflector being elongated along the longitudinal dimension and facing the diffusive surface with a concave side.

10. The illumination system of claim 1, wherein

the first redirecting optics are coupled with the first LEEs and comprise a first reflector arranged on a third surface of the mount, and a second reflector arranged on a fourth surface of the mount, the third and fourth surfaces being parallel with each other and the diffusive surface, the first and second reflectors being elongated along the longitudinal dimension and facing each other with respective concave sides; and

the second redirecting optics are coupled with the second LEEs and comprise a third reflector arranged on a fifth surface of the mount, and a fourth reflector arranged on a sixth surface of the mount, the fifth and sixth surfaces being parallel with each other and the diffusive surface, the third and fourth reflectors being elongated along the longitudinal dimension and facing each other with respective concave sides.

11. The illumination system of claim 10, wherein either of the first reflector of the first redirecting optic or the third reflector of the second redirecting optic comprises portions that transmit light received from the respective first LEEs in the first angular range or second LEEs in the third angular range.

12. The illumination system of claim 1, wherein

the first LEEs are operatively disposed on a first surface of the mount, and the second

LEEs are operatively disposed on a second surface of the mount, the first and second surfaces being elongated along the longitudinal direction, the first and second LEEs being distributed along the longitudinal dimension, such that the first and second surfaces are oriented parallel with respect to each other and to the diffusive surface, and such that the first and third angular ranges are substantially equal;

the first redirecting optics are coupled with the first LEEs and comprise a first reflector arranged on a third surface of the mount, the first reflector being elongated along the longitudinal dimension and facing the target surface with a concave side; and

the second redirecting optics are coupled with the second LEEs and comprise a second reflector arranged on a fourth surface of the mount, the second reflector being elongated along the longitudinal dimension and facing the target surface with a concave side.

13. The illumination system of claim 12, wherein either of the first reflector of the first redirecting optic or the second reflector of the second redirecting optic comprises portions that transmit light received from the respective first LEEs in the first angular range or second LEEs in the third angular range.

14. The illumination system of claim 11 or 13, wherein the light transmitting portions of the reflectors of the redirecting optics are apertures.

15. The illumination system of claim 11 or 13, wherein the light transmitting portions of the reflectors of the redirecting optics are elongated along a direction orthogonal to the longitudinal direction of the illumination device, and an end of each of the light transmitting portions is adjacent a corresponding one of the first or second LEEs.

16. The illumination system of claim 9, 10 or 12, wherein a length of the illumination device along the longitudinal dimension is in the range of about 0.3m to 2.5m.

17. The illumination system of claim 16, wherein a length of the illumination device along the longitudinal dimension is about 0.6m.

18. The illumination system of claim 16, wherein a length of the illumination device along the longitudinal dimension is about 1.2m.

19. The illumination system of claim 16, wherein a separation between the illumination device and the diffusive surface is in the range of 0.3m to lm.