TECHNICAL FIELD AND BACKGROUND

The present disclosure relates to a lighting device, and the use of such device.

Various types of hghting devices exist which can be used to provide a respective type of illumination in accordance with a specific function. Some lighting devices such as ceiling lamps, wall lamps, and floor lamps are typically be used to provide general illumination in an office or other room. Other lighting devices can be used to provide relatively bright directional illumination, e.g. to illuminate a specific working surface. For example, a typical desk lamp consists of a hght source suspended from adjustable arm and configured to direct the light in an adjustable direction while preventing the user being bhnded by uncomfortable direct light. Other lighting devices, such as therapy lamps and wakeup lights can be used to regulate a circadian cycle by specifically directing light into the user’s eyes.

There is yet a need for a multifunctional lighting device providing desired illumination properties in a simple and economic design.

SUMMARY

These and other needs are provided by aspects of the present invention embodied as a lighting device, and use of such device as a multifunctional desk lamp, according to the independent claims. Further advantages can be achieved in accordance with features of the dependent claims.

A light source inside a housing is configured to emit light for illuminating a diffuse sidewall. By providing the sidewall as a vertically extending tube, light can spread around the device, which can be used e.g. for illuminating a desk or other surface. By shaping the spread of light using specific adapted diffusion layers and hght guiding structures, light from a simple light source can be guided in preferred directions while still providing at least some illumination in other direction.

Typically, a light diffusing layer does not have a specific orientation so light scatters isotropically along the layer surface. By providing the light diffusion layer with an asymmetric light transmission structure, e.g. microstructure film, the diffuse light can be steered predominantly in a specific direction. By orienting the asymmetric structure so that light is predominantly bent downwards (towards the bottom of the device), the hghting device can be used to direct a major portion of the diffuse illumination onto a working surface, e.g. table, on which the device is standing. At the same time the present solution allows more efficient and gradual illumination of the surroundings, e.g. compared to a standard desk lamp having an opaque cap to shield the user from viewing directly at the light source. In particular, at least some portion of the diffuse light can used directly to provide general ihumination of the surroundings. So the general illumination of a room is, e.g., less dependent on a reflectivity of the working surface. Furthermore, some of the diffuse light can directly reach a user’s eye. Since the user’s eye is normally located some distance above the table surface the amount of light can be hmited. Advantageously, the hghting device can thus provide a relatively bright ihumination onto the working surface (e.g. papers, keyboard, etc.), while some illumination can illuminate the surroundings, and in particular directly reach the user’s eye without blinding the user when looking at the hghting device.

By additionally or alternatively providing the light diffusing layer with a specific horizontally spreading light transmission structure, e.g. lenticular film, a brightness of the tubular sidewall can be made to appear more uniform. For example, if light is only directed radially outward, an axial center of the tube can appear relatively bright compared to the edges [since the center is directed with more surface towards the eye]. So the horizontal spreading can also alleviate blinding from an otherwise brighter center of the tube. Furthermore, the horizontal spreading can help smoothen a brightness gradient of lighting on surrounding surfaces around the device. For example, artefacts and sharp shadows of any internal structures in the housing, hght source, et cetera, can be alleviated. So user discomfort which may be caused by stark contrasts and/or blinding can be further alleviated.

Direct diffuse light reaching the user’s eye, enabled by the present solution, can provide advantages in regulating the user’s circadian cycle. This regulation can be further improved by controlling a color and/or brightness of the light source, e.g. depending on the time of day and/or sensor measurement. For example, by decreasing the hght intensity of the device when surrounding light is already sufficiently bright, energy for unnecessary illumination can be saved. For example, by alternatively or additionally measuring the presence or absence of a user, the device can be switched off when no one is present further saving energy. It can also be envisaged that the device is used to control the function of other hght sources in the room, or otherwise.

By omitting at least part of the light diffusing layer from part of the sidewall, a window can be formed to allow more directional light there through. For example, the vertical and/or horizontal light diffusion layers can be omitted so the diffusion of hght through the window can be less than through other parts of the sidewall which are covered by the (full) diffusion layer. Accordingly, a more directional light beam can be emitted from the device, e.g. used as a desk lamp, to provide a relatively bright focal area compared to surrounding areas which are illuminated via the (full) diffusion layer. For example, the bright focal area can be used for reading, illuminating a keyboard, or any other object that the user wants to interact with. BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the apparatus, systems and methods of the present disclosure will become better understood from the following description, appended claims, and accompanying drawing wherein:

FIG 1 illustrates a perspective view of a lighting device;

FIG 2A illustrates a top view of select components in the lighting device

FIG 2B illustrates a window formed by omitting part of the hght diffusing layer;

FIG 3 illustrates preferred features of a light diffusing layer;

FIG 4A illustrates a cross-section side view of a normal incidence beam impinging a vertically asymmetric light transmission structure;

FIG 4B illustrates resulting radiant intensity as function of polar coordinates;

FIG 5A illustrates a cross-section top view of a normal incidence beam impinging a horizontally spreading hght transmission structure;

FIG 5B illustrates resulting radiant intensity as function of polar coordinates;

FIG 6A illustrates a cross-section side view of an asymmetric lens;

FIG 6B illustrates resulting radiant intensity as function of polar coordinates;

FIGs 7 A -7D illustrate photographs of a lighting device, as described herein, shown from various angles.

FIGs 8A and 8B illustrate the lighting device in different orientations;

FIGs 9A and 9B illustrate use of the hghting device on a support surface, e.g. desk or table, adjacent a working area;

FIG 10 illustrates a photograph of a lighting device with an absence sensor; FIG 11 illustrates a lighting device comprising a central light guide inside the housing;

FIG 12 illustrates a lighting device comprising a LED strip inside the housing;

FIG 13 illustrates a lighting device comprising a perforated sidewall with micro-perforations to diffuse and/or guide the light;

FIG 14 illustrates a lighting device with an open structure and reflecting diffuser;

FIGs 15A and 15B illustrate a perspective and cross-section view, respectfully, of a hanging hghting device.

DESCRIPTION OF EMBODIMENTS

Terminology used for describing particular embodiments is not intended to be limiting of the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. The term "and/or" includes any and all combinations of one or more of the associated listed items. It will be understood that the terms "comprises" and/or "comprising" specify the presence of stated features but do not preclude the presence or addition of one or more other features. It will be further understood that when a particular step of a method is referred to as subsequent to another step, it can directly fohow said other step or one or more intermediate steps may be carried out before carrying out the particular step, unless specified otherwise. Likewise it wih be understood that when a connection between structures or components is described, this connection may be estabhshed directly or through intermediate structures or components unless specified otherwise.

The invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. In the drawings, the absolute and relative sizes of systems, components, layers, and regions may be exaggerated for clarity. Embodiments may be described with reference to schematic and/or cross- section illustrations of possibly idealized embodiments and intermediate structures of the invention. In the description and drawings, like numbers refer to like elements throughout. Relative terms as well as derivatives thereof should be construed to refer to the orientation as then described or as shown in the drawing under discussion. These relative terms are for convenience of description and do not require that the system be constructed or operated in a particular orientation unless stated otherwise.

FIG 1 illustrates a perspective view of a lighting device 100. In some embodiments, e.g. as shown, the device comprises a tubular housing 10. For example, the tubular housing comprises a circumferential sidewall 11 axially extending in a vertical direction +Z between a bottom 10b and a top lOt of the device. Preferably, the tubular housing 10 has a rounded or essentially circular cross-section extending in the axial direction (Z). For example, this may help in isotropically spreading light around the device and/or prevent bright spots. Alternatively, also other shaped cross-sections can be used (not shown), e.g. a polygon shape such as triangular or square, with optional rounded edges. Alternative to a tubular housing, the device can also have other shapes (not shown), e.g. spherical or conical, although some of the functionality described herein may be diminished or more difficult to maintain. In some embodiments, a light source 12 is configured to emit light for illuminating the sidewah 11, preferably from inside Si the housing 10. In one embodiment, e.g. as shown, the sidewall 11 comprises a light diffusing layer lid. For example, the hght diffusing layer lid is configured to receive a first portion LI of the light from inside Si the housing 10 and transmit the first portion LI as diffuse hght Ls outside So the housing 10. Preferably, the sidewah 11 (together with the bottom and top) enclose an interior space, e.g. housing the light source 12 inside. In some embodiments, the light diffusing layer lid comprises a vertically asymmetric light transmission structure 1 lv configured to bend light transmitted there through predominantly downwards (-Z), e.g. with respect to a (horizontal) surface normal of the layer. In other or further embodiments, the light diffusing layer lid, alternatively or additionally, comprises a horizontally spreading light transmission structure 1 lh configured to (symmetrically) spread hght transmitted there through in a horizontal plane transverse to the vertical direction +Z. In one embodiment, the sidewall 11 is covered by the light diffusing layer lid, except for a window llw, formed by a contiguous area of the sidewall where at least part of the light diffusing layer lid is omitted. In another or further embodiment, the window llw is configured to receive a second portion L2 of the light and emit the second portion as a beam of light “Ld”. For example, the beam of light “Ld” is used for ihuminating a surrounding surface outside So the housing 10 with a relatively bright spot of light compared to the diffuse light Ls through the rest of the sidewall 11.

In some embodiments, the sidewall 11 comprises a clear, e.g. transparent and/or essentially non-scattering, outer shell 11c. For example, the light diffusing layer lid is arranged to cover an inside surface of the outer shell 1 lc. Advantageously, a smooth outer shell or tube can be relatively easy to fabricate and covered by a flexible film inserted inside the housing. The shell may also help protect the light diffusing layer lid, e.g. microstructure film. Alternatively, or additionally, (part of) the light diffusing layer lid can be laminated on an outside of the sidewall 11. The light diffusing layer lid can also form an integral part of the sidewall. For example, the sidewall can be entirely formed by one or more light diffusing layers lid.

In some embodiments, the light source 12 is exclusively arranged on one (axial) side of the housing, e.g. bottom or top. In a preferred embodiment, e.g. as shown, the light source 12 is arranged at the top lOt of the housing. Advantageously, this may help to cast the light in a predominantly downwards direction and/or cast a directed beam of light through the window. In one embodiment, the light source 12 is provided with an asymmetric lens 14 configured to redirect a relatively large portion of emitted light in towards one direction +X, most preferably in the direction of the window llw. Alternatively, or additionally, the light source 12 itself can be tilted, e.g. towards the window llw.

In some embodiments, a reflector 13 disposed at the bottom 10b inside the housing 10 to reflect light L2 coming down from the light source 12 back up. Advantageously, this may help to further optimize light distribution. Most preferably, the light source 12 comprises a (white) diffuse reflecting surface, e.g. Teflon (Polytetrafluoroethylene). This may help to radially distribute light all around the inside Si of the housing 10. Alternatively, also other reflecting surfaces can be used, e.g. a (specular) reflecting mirror surface. Alternatively, or additionally to a hght source at the top, a light source can also be disposed at the bottom, e.g. with a reflector on top, although this may provide less ideal light distribution. In principle also multiple light sources can be used although this may add to the expense of the device. It can also be envisaged to include a hght guiding structure inside the device, e.g. as illustrated in FIG 11.

In some embodiments, the light source 12 is configured to emit a controllable color spectrum. For example, the light source comprised a tunable LED and/or a combination of different color LEDs which can be used to emit a combined variable spectrum. Preferably, the light source is configured to allow selecting an emission spectrum from a set of different spectra (e.g. different color temperatures). Also an intensity of the hght source can be controlled. In one embodiment, a controller (not shown) is configured to control a color and/or intensity of the light source, e.g. to regulate a user’s circadian cycle. In another or further embodiment, the lighting device 100 comprises or couples to a clock (not shown), wherein the light source 12 is controlled depending on a time and/or date determined by the clock. For example, the light source is controlled to emit relatively bright and/or blue hght in the morning while emitting relatively dim and/or red light in the late afternoon or evening. This cycle may also depend on the date and/or geographical location of the device. For example, the lighting is graduahy adjusted, e.g. throughout the day.

In some embodiments, the lighting device 100 comprises or couples to a light sensor 15. In one embodiment, an intensity and/or color of the light source 12 is controlled depending on a measurement of the hght sensor 15 (alternatively, or additionally to the clock). For example, an intensity of the hght source 12 is adjusted based on a measured intensity of (other) light coming from the environment. Advantageously, when the environment is already sufficiently bright, an intensity of the light source can be tuned down. Alternatively, or additionally to the intensity, also a color of the light can be adjusted, e.g. based on environmental brightness which can be hnked to a time-of-day. Preferably, the hght sensor 15 is disposed on top and/or front of the device, or at least in a position where light sensor 15 picks up a minimum amount of light from the light source 12. The light sensor 15 can also be calibrated to prevent self-interference, e.g. substantiahy subtract a portion of measured light originating from the light source and simultaneously act as a presence and/or absence detector (where the presence and/or absence detector could be also a separate detector).

In a preferred embodiment, at least one of the layers forming the light diffusing layer lid and/or sidewall 11 comprises, or is essentially formed of, a translucent material. Most preferably, the translucent material has an essentially white appearance. Typically, a white translucent material has an essentially wavelength independent transmission and/or reflection coefficient, e.g. less than twenty, ten, or five percent variation of the coefficient at least in a visible wavelength range (380 - 700 nm). In some embodiments, an appearance of the translucent material may depend on a color of the light source. Preferably, the spectrum (relative distribution of wavelengths) emitted by the lighting device via the diffusion layer is similar or essentially the same as that of the light source. For example, this may obviate adjusting the hght source color to the transmission spectrum of the diffusion layer.

Preferably, the light diffusing layer lid has at least some (diffuse) reflective properties to help spread light along the length of the tubular housing. For example, the (full) light diffusing layer lid may reflect between 10 - 90% of the light source back inside the housing, preferably between 20 - 80%. On the other hand, a transmissivity of the window llw can be higher. For example, a unit area of the window llw is configured to pass at least 10% more light of the light source 12 than a unit area of the surrounding (full) light diffusing layer lid, preferably at least 20%.

In a preferred embodiment, a height Hs of the lighting device 100 or at least the sidewall 11 is between 30 - 50 cm, most preferably between 35 - 45 cm. If the sidewall is too high, this can make it difficult to fully illuminate along the full height of the sidewall, especially when the light source is disposed only on one side of the housing (e.g. bottom or top). If the sidewall is too low/short, this may lower the actively illuminated surface. Most preferably, the height of the transparent/translucent sidewall 11 is at least eighty or ninety percent of the height of the device. The larger percentage of the device capable of emitting light, the more efficient the device can function. Typicahy, the hghting device 100, e.g. the tubular housing 10, has an (outer) diameter Ds less than its height Hs, e.g. by at least a factor two, three, four, or more. Preferably, the diameter Ds is between 5 - 20 cm, most preferably between 8 - 15 cm. This may provide on the one hand a device that can stably stand on the table while not taking too much space. In some embodiments, the diameter Ds is constant along the vertical direction +Z of the device. Alternatively, the diameter may vary, e.g. having a frustoconical and/or wavy housing, which may be larger at the bottom than at the top, or vice versa.

In a preferred embodiment, a maximum height of the window 11 w extends between 10 - 50% of the height Hs of the sidewall 11, preferably between 15 - 30%. More preferably, the window llw is disposed in a top half of the sidewall 11. This may allow the hght source to cast a light beam through the window to project a hght spot at some distance from the device. Most preferably, a top of the window llw is disposed at least some distance Ht below the light source 12, e.g. with the distance Ht between 1 - 15 cm, preferably between 3 - 10 cm. By providing a minimum height edge between light source and the window llw, the amount of light projected upwards can be diminished. Alternatively, to the preferred window size and position, as shown and described, in principle the window may also have other sizes, even extending up to a full height on one side of the device.

Preferably, the lighting device 100 is embodied as a table top or desk lamp. In some embodiments, the lighting device 100 is configured to stand with its bottom side on a working surface, e.g. table or desk. In one embodiment, the bottom 10b of the lighting device 100 is provided with anti slip provisions and/or cushioning means. For example, rubber and/or felt coverings on the bottom may prevent inadvertent displacement and/or scratching of a working surface, e.g. table or desk. The device may also be provided with legs to stand on a surface. In other or further embodiments, the lighting device 100 is provided a control interface. Preferably, the control interface is provided on top lOt of the device. For example, one or more buttons, sliders, et cetera, can be provided to control a brightness and/or color of the device. Also an on/off button can be provided. Of course, one or more controls can also be provided elsewhere, e.g. on a side of the bottom. Typically, the desk lamp is provided with an electricity cord lOe that preferably extends from the bottom side of the device. Alternatively, the electricity cord lOe may extend elsewhere, and/or the device can be provided with a battery.

Alternative to a desk lamp, the device can also be envisaged as a floor lamp, or standing lamp. For example, the device as described herein can be placed on a pole extending from the floor, e.g. next to a table, although this may be more cumbersome and provide less functionality, e.g. in illuminating the table all around the device. Alternatively, the floor lamp may also comprise a sidewall that extends over a relatively large height from the ground to above a table, although it may be more difficult to provide even lighting throughout the length of the device. This may be solved e.g. using a light guiding structure or LED strip as shown in FIGs 10 and 11, respectively. Alternatively still, the device can be envisaged as a wall lamp, e.g. connected near a desk, although this may provide less functionality in illuminating a surroundings behind the lamp. Alternatively still, the device can be envisaged as a hanging lamp, e.g. suspended above a table although this may provide less control over the light spot.

FIG 2A illustrates a top view of select components in the lighting device 100. Preferably, the hght source 12 is disposed at a radial center of the sidewall 11, most preferable at the top of the interior space Si.

In some embodiments, an asymmetric lens 14 is arranged to receive light emitted by the light source 12 and asymmetrically spread the received light in an interior space inside Si the sidewall 11 predominantly towards one direction +X, preferably in the direction of the window 1 lw (at least, if the window is present). Preferably, between 55 - 95% of total light emitted from the device is emitted in one half circumference of the device containing the window llw, most preferably between 60 - 80%. By projecting more the light towards one side, this may allow more efficiently illuminating a relevant part of the user’s working surface. Also the relatively high transparency of the window llw compared to other parts of the diffusion layer may help with this. On the other hand, at least some of the light projected on the other side of the device (negative X) may allow more evenly illuminating the environment. Alternatively, or additionally to the asymmetric lens 14, the light source 12 itself can be tilted towards one side +X, e.g. the window llw.

In some embodiments, the window llw is disposed (exclusively) on one side +X of the sidewall 11 to pass a beam or relatively unscattered light (compared to light passing the full diffusion layer) directly from the light source 12 through the window llw for casting a relatively bright spot of illumination onto a surface adjacent on said one side of the lighting device 100 (relatively bright compared to surrounding light on the surface passing other parts of the full diffusion layer). For example, the window llw is positioned on the housing axially below and radially adjacent the light source 12 on said one side. Preferably, there is only a single (contiguous) window. Alternatively, there can be multiple windows and/or the window can be subdivided in non-continuous adjacent parts. In one embodiment, a (maximum) width of the window 11 w extends circumferentially along the sidewall 11 (from the center) with an opening angle “F” between 30 - 180° (plane angle), preferably between 60 - 150°. This may allow casting a sufficiently large (adjustable) beam that is still relatively directional to one side.

In some embodiments, an opaque strip 16 is arranged vertically along a height of the sidewall 11, preferably opposite a side +X of the window llw. For example, the opaque strip 16 can be used to form a heat sink and/or used for housing electrical cabhng between the bottom and the top of the device (e.g. in combination with an electrical cable on the bottom). Preferably, the opaque strip 16 is relatively thin (along the circumference), e.g. between 1 - 5 cm, so it minimally hinders light emission around the device. In one embodiment, the heat sink is configured to conduct excess heat from inside to outside the housing 10. For example, the heat sink is configured to conduct heat away from a top of the fixture (keeping top touch surface below 50 deg C) and/or LED (keeping the LED’s Ct point within a temperature specification). For example, the heat sink is formed of a metal which can have relatively good heat conduction. The heat sink may also comprise surface enlarging features inside and/or outside the housing, e.g. fins to increase heat transport. In one embodiment, the opaque strip is provided with a (diffuse) reflective surface on the inside Si (at least in a visible spectrum) of the housing so the amount of direct absorbed light is minimized. In another or further embodiment, the opaque strip is provided with an infrared absorbing layer, so at least heat energy (infrared waves) can be efficiently absorbed for conduction to outside the enclosed interior. It can also be envisaged to provide ventilation openings, e.g. at a top or bottom of the housing. In some embodiments (not shown here), the opaque strip is used for attaching one or more light sources.

FIG 2B illustrates a window llw, e.g. formed by omitting part of the light diffusing layer lid. In a preferred embodiment, the window llw has a generally rounded (though not circular) shape. Preferably, the shape of the window llw is horizontally mirror symmetric (i.e. mirrored across a vertical center line Cv), Most preferably the shape of the window llw is vertically asymmetric (i.e. not symmetric when mirrored across a horizontal center line Ch). For example, the rounded shape is horizontally stretched above a horizontal center line Ch compared to below the horizontal center line. In one embodiment, the window llw can be described as a (heavily) rounded triangular shape with an apex of the (isosceles) triangle pointing downwards.

In a preferred embodiment, the shape and/or position of the window is adapted in relation to the position and/or light distribution of the light sources. Most preferably, the shape and/or position window is configured to pass a beam of light from the hght source that is projected as a circular or elliptical round spot on an adjacent (horizontal) support surface for the lighting device, e.g. table. For example, the shape of the window may correspond to an intersection of the sidewall 11 with hght cone between the light source and a circular or elliptical projected light spot on the support surface. Of course also other shaped windows can be used depending on a desired light spot.

FIG 3 illustrates preferred features of a light diffusing layer lid. In some embodiments, e.g. as shown, the light diffusing layer lid is formed by a stack of multiple layers 1 lv, 1 lh, 1 lc. Advantageously, each layer can provide respective functionalities, e.g. hght spreading function and/or rigidity. For example, different films of material can be used to provide the respective vertically asymmetric light transmission structure llv and/or horizontally spreading light transmission structure 1 lh, as described herein. The films can be easily cut in any desired direction and/or to provide a selective window. Advantageously, the tubular shape of the housing, e.g. determined by the rigid outer shell 1 lc, can allow easily inserting one or more rolled up pieces of film inside (or laminated outside). Alternatively to the shown arrangement, also other sequences of films and/or layers can be used and/or the functionality of one or more light transmission structures llv,llh can be combined, e.g. in a single hght diffusing layer lid that also forms the outer shell 1 lc.

In some embodiments, one or more layers forming the light diffusing layer lid comprise a scattering material, e.g. embedded scattering particles, and/or surface roughness features to promote light diffusion or scattering. For example, the scattering material and/or surface roughness features results in relatively random scattering so the resulting light can be relatively isotropic, e.g. without introducing a specific directional preference along the surface. In one embodiment, the embedded scattering particles comprise small particles with different material than the surrounding matrix, e.g. having different refractive index and/or transparency. For example, the embedded scattering particles have a mean diameter more than 0.1 pm, more than 1 pm, or even more than 10 pm, e.g. up to 100 pm, or more. Also other types of scattering media can be used. In another or further embodiment, the surface roughness features comprise (random) irregularities at the layer surface. For example, the surface roughness features can be quantified using a roughness value “Ra” (e.g. arithmetical mean deviation according to ISO 4287:1997 standard) of more than 0.1 pm, more than 1 pm, or even more than 10 pm, e.g. up to 100 pm, or more.

In other or further embodiments, one or more layers forming the light diffusing layer lid comprise (directional) microstructures at a respective interface and/or embedded inside a respective layer to shape a direction of the hght. For example, directional microstructures can be used to introduce a preferential directionality depending on an orientation or cut of the layer. In this way the transmitted light can be relatively anisotropic with respect to a surface normal.

In one embodiment, the microstructures are asymmetrically formed along an in plane direction (T and/or Z) of the diffusion layer so light interacting with the microstructures is predominantly transmitted and/or scattered towards a specific direction which correlated with a directionality of the microstructures. For example, the microstructures form an asymmetric configuration along a surface of a light diffusing layer. In this way light can be transmitted and/or scattered towards a specific direction which correlates with the direction of the asymmetric configuration. For example, a set of (microscopic) scales, ridges and/or prism-hke structures distributed and oriented along the surface can be used to vertically spread light in a preferential direction, e.g. downwards.

In another or further embodiment, the microstructures have an at least partially symmetric structure (e.g. horizontally and/or vertically mirror-symmetric), to symmetrically spread light at least along a specific plane. For example, a lenticular film can be used to horizontally spread transmitted light. Alternatively, or in addition to internal or external microstructures, light can also be redirected in other ways, e.g. using a gradient index material wherein a refractive index varies along a surface of the film (similar to a gradient index lens). Internal microstructures can also be provided by variations in refractive index inside the film.

In some embodiments, diffusion and/or hght directing properties are combined in a respective light diffusing layer. For example, the respective light diffusing layer can be provided both with superficial or embedded directional microstructures as well as respective surface roughness and/or embedded (random) scattering particles. By minimizing the number of different layers, visible artefacts such as Newton’s rings can be alleviated. Such artefacts can also be aheviated by choosing a specific sequence of layers. Alternatively, diffusion and hght directing functions can be provided by separate layers, e.g. a first layer to direct the light vertically downward, a second layer to spread hght horizontally, and a third layer to randomly diffuse at least some of the light in one or more directions.

In some embodiments, the vertically asymmetric light transmission structure llv is formed by a first flexible sheet, e.g. of a translucent material with micro scales. In other or further embodiments, the horizontally spreading hght transmission structure 1 lh is formed by a second flexible sheet, e.g. of the same or different translucent material with a lenticular structure, e.g. vertically extending surface corrugations. In one embodiment, the flexible sheets are inserted inside a rigid transparent, e.g. essentially non-scattering, outer shell 11c to form the sidewall 11. Preferably, the second flexible sheet is disposed between the first flexible sheet and the outer shell 1 lc. This arrangement and sequence is found to provide less visible artefacts and/or smoother appearance than e.g. reversing the films. Also other or further flexible films or arrangements of flexible films in a rigid shell can be used, in principle. In some embodiments, the sidewall 11 is partially covered by a first sheet forming a vertically asymmetric light transmission structure 1 lv as part of the light diffusing layer lid. In one embodiment, the first sheet is omitted at a contiguous area of the sidewah 11 forming a (cut out) window 1 lw. In another or further embodiment, the sidewall 11 including the window 1 lw is fully covered by a second sheet forming a horizontally spreading light transmission structure llh. By only covering the window with the horizontally spreading light transmission structure, the beam of light can stih be relatively well directed some distance from the device while a direct view of the interior can be prevented. In principle, also alternative arrangements of layers can be envisaged, e.g. omitting the light diffusing layer lid entirely, providing only a simple hght diffusion layer (without specific directional structures), or omitting only the horizontally spreading light transmission structure.

FIG 4A illustrates a cross-section side view of a normal incidence beam impinging a verticahy asymmetric light transmission structure 1 lv.

In some embodiments, light transmitted through the verticahy asymmetric light transmission structure 1 lv has an angle of transmission that is on average closer to the downwards vertical direction (-Z) than an angle of incidence at which the light is received (zero for normal incidence). In one embodiment, more than fifty percent of the diffuse light is emitted in an angle below a normal to the sidewah surface (e.g. between the normal and the bottom 10b of the housing 10), preferably between sixty and ninety percent.

FIG 4B illustrates resulting radiant intensity as function of polar coordinates. It will be noted that these and other polar plots are intended to illustrate quahtative behavior of the respective layer. Of course the actual measured radiant intensity may differ. Also it will be noted the spread of radiant energy typically depends at least in part on the direction of the incoming beam, while the present plot is simplified for ease of understanding in that it shows transmitted directions resulting from an incoming collimated beam at normal incidence.

In some embodiments, e.g. as shown, the film has both light directing and scattering/diffusing properties. Preferably, the hght transmission structure 1 lv has bias or tendency to skew the light predominantly towards one direction (here towards the downwards direction (-Z)). For example, this behavior can be provided by one or more films comprising asymmetric microstructures to direct the light, and light diffusing structures to introduce a spread in the light. In some embodiments, preferred skewing and/or diffusion of the light through the vertically asymmetric light transmission structure 1 lv as described herein can be quantified by impinging the film with a normal incidence collimated beam of light and observing an average vertical direction qn and/or spread av of resulting transmitted light. It will be noted that in practice, hght inside the device as described herein can already have a generally downward direction with relatively high spread (etendue), e.g. due to preferred placement of the light source emitting downwards from the top of the device. Nevertheless, it may be easier to quantify behavior of the film using a normal incidence collimated light beam.

In a preferred embodiment, the verticahy asymmetric light transmission structure 1 lv comprises a film with vertically asymmetric microstructures configured to cause a normal incidence colhmated light beam to be transmitted through the film while bending the light beam downwards (-Z) with an average vertical skew angle qn between 10° - 60° with respect to the normal incidence most preferably between 15° - 45°, e.g. 20°. In another or further embodiment, the vertical spread of the light traversing the vertical skewing layer 1 lv and/or the full diffusion layer can be quantified by impinging the light with a normal incidence colhmated light beam, e.g. 532 nm laser, and measuring a (vertical) opening angle av of a resulting light cone (around the average direction qn) after transmission/diffusion where exactly half of the light is inside the cone and half outside the cone. To prevent too much hght scattering upwards (negating the vertical skew), preferably the vertical opening angle av is relatively small, e.g. less than 40°, less than 30°, or even less than 20°. It can also be envisaged that the vertically asymmetric light transmission structure 1 lv provides essentially no vertical diffusion where the vertical diffusion is optionally provided by other layers.

Alternatively, or additionally to quantifying the respective behavior of respective diffusion layers, the overall preferred light spreading properties of the lighting device can be quantified. In some embodiments, a peak work area illuminance of a bright spot projected on a horizontal working surface is preferably between 500 - 1500 Lux, most preferably between 800 -1200 Lux. For example, the bright spot is projected and measured adjacent the device on the table from a side of the window llw at a distance between 0.3 - 0.6 meter, e.g. 0.4 m. In other or further embodiments, the device is configured to provide direct vertical lighting, e.g. measured at a vertical plane one meter adjacent the device and half a meter above a bottom of the device (typical position of user’s eyes), preferably between 50 - 500 Lux, more preferably between 100 - 300 Lux, most preferably at least 200 Lux vertical illumination. The Lux values described herein can refer to Photopic Lux or Melanopic Lux (depending on color temperature by a Melanopic Ratio). For example, for the efficient activation of the circadian effect the device is preferably configured to provide a user with a target vertical illuminance directly on the eye of at least 150 Lux at 2700K and higher levels approaching 240 Lux at 6500K. For example, the light is provided over a duration of at least 4 hours electric light alone between the hours of 9 am and 1 pm. The lighting intensity and/or color can be changed for different times of the day interval, e.g. reducing intensity by at least a factor two, three in the late afternoon / evening (e.g. after 15 pm or 16 pm).

FIG 5A illustrates a cross-section top view of a normal incidence beam impinging a horizontally spreading light transmission structure llh. FIG 5B illustrates resulting radiant intensity as function of polar coordinates. Similar as described with reference to FIGs 4A and 4B, the shown film can have both light directing and scattering/diffusing properties. For example, a set of light guiding structures can be used to generally diverge the light in a horizontal plane while the film also comprises scattering features to horizontally and/or vertically diffuse the hght. Also similar as before, the film can be provided with only horizontal diverging structures while diffusing properties are provided in other of further layers. It will be noted that in practice, light inside the device as described herein can already have a horizontally divergent direction with relatively high spread (etendue), e.g. due to central placement of the light source emitting radially outwards. Nevertheless, it may be easier to quantify behavior of the film using a normal incidence colhmated light beam.

In one embodiment, e.g. as shown, the horizontal spread of light traversing the layer llh and/or the full diffusion layer can be quantified by impinging the hght with a normal incidence colhmated light beam, e.g. 532 nm laser, and measuring a (horizontal) opening angle ah of a resulting hght cone (around the average normal direction) after transmission/diffusion where exactly half of the light is inside the cone and half outside the cone. To provide a smooth horizontal spread of hght, preferably the horizontal opening angle ah is relatively large. In a preferred embodiment, the horizontally spreading light transmission structure 1 lh comprises a lenticular film configured to cause a normal incidence colhmated light beam to be transmitted through the film while horizontally spreading the light beam with a horizontal opening angle (ah) of more than 10°, more than 20°, or even more than 30°. The resulting (increase in) vertical opening angle can be relatively small, e.g. less than the horizontal opening angle by at least a factor two. For example, an effect of the horizontally spreading light transmission structure 1 lh on a vertical direction of the light can be negligible (possibly except any random diffusive properties of the layer).

While the present figures show the horizontally spreading light transmission structure 1 lh essential acting as a negative cylindrical lens for diverging the light, also a positive cylindrical lens structure can be used or a combination of such elements. For example, a focal point of the positive cylindrical lens structure can be relatively close to the device, after which point the beam starts diverging. So it will be understood that in principle any corrugated structure can be used such as a lenticular film having vertically extending stripes / corrugations to horizontally spread the light while minimally affecting the vertical direction.

FIG 6A illustrates a cross-section side view of an asymmetric lens 14. FIG 6B illustrates resulting radiant intensity as function of polar coordinates. In some embodiments, e.g. as shown, light emitted by the light source 12 is preferentially skewed in a specific direction +X, e.g. towards the window (not shown here), or any other preferred direction. For example, light can be skewed by an asymmetric lens 14 as shown or other light guiding structure (e.g. having microstructures such as the film described with reference to FIGs 4A and 4B). Preferably, the asymmetric lens 14 has relatively high transparency, e.g. transmitting more than 90% of light from the light source 12, preferably >95%, or even >99%. The skewing behavior of the lens or other structure can be quantified by recording an average directional angle qc with respect to a vertical downward axis -Z. In a preferred embodiment, light emitted by the light source itself and/or the asymmetric lens 14 arranged in front of the light source is skewed in a direction (+X) resulting in an average emission angle qc between 10° - 60°, with respect to a vertical downward axis -Z, most preferably between 15° - 30°. Similar as defined with reference to FIG 4B, also the directional spread can be quantified using the spread angle ax as indicated. Preferably, the spread angle ax is relatively large, e.g. >qc so at least some light is also used to illuminate the backside of the device (opposite the window). Overall preferred illumination around the device is also indicated in FIG 2A.

FIGs 7 A -7D illustrate photographs of a lighting device, as described herein, shown from various angles. FIG 7A illustrates a front view of the device where a preferred shape and position of the window is visible. FIG 7B illustrates a side view of the device, showing part of the window.

FIG 7C illustrates a backside view of the device, showing an opaque strip. FIG 7D illustrates a zoomed in view of a top of the device, showing the window.

FIGs 8A and 8B illustrate further photographs of the lighting device in different orientations. As illustrated in FIG 8A, the device can provide a relatively even distribution of hght on all sides. As illustrated in FIG 8B, the device can provide a relatively bright spot of illumination (here on the wall) depending on its orientation.

FIGs 9A and 9B illustrate use of the hghting device on a support surface, e.g. desk or table, adjacent a working area. Some aspects can be embodied as a method of using of the lighting device as described herein. In some embodiments, the use comprises positioning the device as desk lamp on a support surface adjacent a (generally horizontal) working area. Preferably, the lighting device is oriented with a window facing the working area to project a relatively bright spot of light onto the working area while overall illuminating a surrounding area of the table and/or room with relatively less bright light. In some embodiments, a color and/or intensity of light emitted by the lighting device is controlled by a controller depending on a time of day for regulating a user’s circadian cycle. Of course the device can also have other or further uses.

FIG 10 illustrates a photograph of a lighting device. In some embodiments, the lighting device comprises an absence sensor 15a (or presence detector), e.g. IR and/or motion detector, configured to detect the presence and/or absence of a user, e.g. in a room and/or seated at a table where the device is located. For example, the device can be configured to automatically switch on or off depending on a detected presence or absence of a user, respectively; or switch between alternate lighting levels (e.g. less bright is the user is not detected). In this way, power for unnecessary lighting can be saved. Preferably, the absence sensor 15a is disposed on a front side of the device, e.g. the side where the window as described herein is also located. For example, absence sensor 15a is disposed above the window, as shown. As will be appreciated the device is typically turned with the window towards a working area of the user. So by arranging the absence sensor at the same side, this sensor is typically directed to also detect the user. Alternatively, the absence sensor can also be placed elsewhere, e.g. on top of the device or on the bottom. By arranging the sensor near the top of the device, it can be easily connected to other circuitry, e.g. printed circuit board at the top of the device.

In some embodiments, the absence sensor is combined with a light sensor, e.g. the light sensor 15 as shown and described earher with reference to FIG 1. For example, the sensors are combined by positioning the sensors at the same position on the device, e.g. top front side. Most preferably, the sensors are integrated to form an integrated and/or combined light and absence sensor. For example, one sensor device can be configured to detect both IR light corresponding to the presence of a user and visible hght corresponding to environmental lighting conditions. In one embodiment, the light source of the lighting device is controlled based on one or more measurement of the combined light and absence sensor. For example, the light source of the hghting device is turned down when the sensor either detects more than a threshold amount of visible light (bright environment) and/or when the sensor detects less than a threshold amount of infrared light (absent user). In principle, the absence and light sensors can also be separate and/or there can be multiple sensors for detecting other or further environment variables.

FIG 10 illustrates a lighting device 100 comprising a light guide 17 inside an interior space of the housing 10. In one embodiment, the hght guide 17 is configured to receive light from the light source 12 into the light guide 17, and reflect at least a portion of this light inside the hght guide 17. For example, the light guide 17 can be formed by another tube or solid rod inside the housing 10. Preferably, the internal reflection in the light guide 17 is relatively high, e.g. >50%, so a major portion of the light may can be propagated internally inside and along the hght guide 17. Preferably, the internal reflection is not too high, e.g. <95%, so at a least some light can escape the guide along its length. For example, the light guide 17 is formed of a translucent material and/or scattering medium that reflects and/or scatters light inside and outside the guide. In one embodiment, the light guide 17 is disposed concentrically inside the tubular sidewall 11 with an open space there between surrounding the hght guide 17. In another or further embodiment, the light guide 17 extends axially between the bottom 10b and top lOt of the housing 10. In this way, light can be spread around the height of the device. This can make it easier to extend the height while still maintaining even illumination.

In some embodiments, the light source 12 is disposed at the bottom 10b of the housing 10, wherein light is guided upwards by the light guide 17. In one embodiment, the housing comprises a reflector 13 at the top lOt of the housing, e.g. at the end of the light guide 17. In another or further embodiment, reflector 13 is tilted to direct a portion of reflected light towards one side of the housing, preferably as a directional beam Ld through the window 1 lw. Other light escaping along a length of the light guide 17 can be emitted as diffuse light, e.g. through one or more a light diffusing layers, e.g. forming part of the sidewall 11 as described herein. For example, this may include the vertically asymmetric light transmission structure and/or horizontahy spreading light transmission structure.

FIG 12 illustrates a lighting device 100 comprising a directional light source 12d and string of light sources 12s inside the housing. For example, string of light sources 12s can be formed by a LED strip. In one embodiment, the directional hght source 12d is directed to project a beam of light from one side of the device, preferably through the window 1 lw as described herein. In another or further embodiment, string of hght sources 12s configured to ihuminate the sidewall 11, e.g. comprising a light diffusing layer as described with reference to the other embodiments. For example, the string of light sources 12s is distributed along a height of the housing. Optionally, different color light LEDs can be used which can be controlled to provide a combined light color / temperature, as described with reference to the other embodiments. In some embodiments (not shown), one or more light sources are connected to an opaque strip, e.g. at the back of the housing. For example, the opaque strip 16 described with reference to FIG 2A can be used for this alternative or additional purpose.

FIG 13 illustrates a lighting device comprising a sidewall 11 with a perforated sheet. In one embodiment, the sheet comprises a pattern of micro-perforations to diffuse and/or guide the light. Essentiahy, the perforated sheet can thus act similar to the light diffusing layer lid as described herein. In another or further embodiment, the opaque sheet is cut to form a window llw which can also function similarly as described herein. In some embodiments, the sidewall 11 comprises an essentially opaque material, e.g. metal sheet, wherein light can only pass the sidewall via the perforations, i.e. openings through the sheet. In one embodiment, the sheet is painted, e.g. white, which may result in diffuse reflection inside the housing. Alternatively, or additionally, also one or more translucent layers can be used which may or may not be perforated. The outside can be painted in any desired color.

Various patterns of micro-perforations can be envisaged, e.g. as illustrated on the bottom right side. Preferably, an open area formed by the openings is relatively high, e.g. >30%, >40%, or >50%, of the surface area.

For example, the micro-perforations are formed by openings through a respective layer having a respective cross-section diameter <lmm, <0.5mm, <0.2mm, or even <0.1mm, e.g. down to 0.01 mm, or less. In one embodiment, the micro-perforations are directional, e.g. sloped across a thickness of the sheet, to guide hght in a specific direction. For example, the cross-sections of the perforations are as illustrated on the bottom left side which can result in light being guided in a generally downwards direction similar to the vertically asymmetric light transmission structure as described herein. Also other or further sloped passages can be used to guide light in any direction, e.g. forming a horizontahy spreading light transmission structure.

FIG 14 illustrates a lighting device 100 with a diffuse reflecting layer 1 lr configured to directly reflect diffuse light outwards from the device (without further sidewah or housing). Similar to earlier embodiments, the lighting device comprises a hght source 12 disposed at a top of the device configured to project a relatively bright beam of light Ld while also causing the emission of indirect diffuse hght Ls. For example, the light source 12 is configured to project a portion of the light onto the diffuse reflecting layer Hr to cause a diffuse reflection emitted from the device. For example, the layer lid comprises a white reflecting layer, e.g. Teflon. Preferably, the diffuse reflecting layer Hr has a relatively steep slope, e.g. <45° or even <60° with respect to the vertical axis, so a major portion of light is still reflected downward.

FIG 15A illustrates a perspective view of a hghting device 100 configured as a hanging lamp. FIG 15 illustrates a corresponding cross- section view. As shown, it can be envisaged to provide a lighting device with a tubular housing comprising a circumferential sidewall axially extending in a horizontal direction between a two sides of the housing. One or more a light sources 12 can be configured, e.g. at the top on one side of the tubular housing shining downwards, to emit light for illuminating the sidewall from inside the housing. Also other lighting configurations can be envisaged, e.g. with (horizontal) light guide similar to FIG 11 and/or a LED strip similar to FIG 12. Preferably, the sidewall comprises a light diffusing layer lid configured to receive a first portion of the light from inside the housing and transmit the first portion as diffuse light Ls outside the housing. More preferably, the sidewall is covered by the light diffusing layer, except for a window llw as described herein. For example, the window is arranged on a bottom side of the tubular housing (e.g. opposite the one or more light sources 12). Accordingly, the window llw may be configured to receive a second portion of the light and emit the second portion as a beam of light, e.g. for illuminating a working surface below the device with a relatively bright spot of light compared to the diffuse hght through the rest of the sidewall.

Optionally, the light diffusing layer lid comprises a vertically asymmetric light transmission structure configured to bend light transmitted there through predominantly downwards. In this case the downwards direction is not aligned with the axial direction of the tubular housing, so the vertically asymmetric light transmission structure can be rotated accordingly. Optionally, the light diffusing layer lid comprises a horizontally spreading light transmission structure 1 lh, which may be similarly rotated 90 degrees. Advantageously, the hanging lamp can provide a combination of directional light on a working surface and diffuse hght illuminating the surroundings similar as described herein. For example, this can be used for regulating a circadian cycle. Also other or further features described with any of the other embodiments can be applied to the present lighting device.

In general, for the purpose of clarity and a concise description, features are described herein as part of the same or separate embodiments, however, it will be appreciated that the scope of the invention may include embodiments having combinations of all or some of the features described. While embodiments were shown for various arrangements of components in a lighting device, also alternative ways may be envisaged by those skilled in the art having the benefit of the present disclosure for achieving a similar function and result. For example, components, structures, and layers may be omitted or combined or split up into one or more alternative components. For example, any of the features, such as the light diffusing layer, hght source, reflector, asymmetric lens, light/absence sensor, et cetera, described with reference to the embodiments of FIGs 1-9 can be applied (mutatis mutandis) to any of the embodiments of FIGs 10-15, and vice versa. The various elements of the embodiments as discussed and shown offer certain advantages, such as a combination of directional and diffuse lighting, in particular with hght steered in preferred directions including a working surface and the user’s eyes without causing blinding. Of course, it is to be appreciated that any one of the above embodiments or processes may be combined with one or more other embodiments or processes to provide even further improvements in finding and matching designs and advantages. It is appreciated that this disclosure offers particular advantages to regulating a circadian cycle, and in general can be applied for any other lighting application.

In interpreting the appended claims, it should be understood that the word "comprising" does not exclude the presence of other elements or acts than those listed in a given claim; the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements; any reference signs in the claims do not limit their scope; several "means" may be represented by the same or different item(s) or implemented structure or function; any of the disclosed devices or portions thereof may be combined together or separated into further portions unless specifically stated otherwise.