Abstract:
The present invention relates to a lighting device ( 100 ), which comprises a structure of interconnected sleeves ( 110 ) and a light emitting arrangement ( 140 ) arranged inside the sleeves. The structure forms a polygon mesh and light sources ( 116 ) on the light emitting arrangement ( 140 ) can be positioned by the structure so that the problem of glare can be reduced. The present invention also provides a sound-absorbing, flexible and collapsible structure which can be used in e.g. large scale architectural panels, horticulture and phototherapy devices. The lighting device ( 100 ) can be produced by connecting the sleeves ( 110 ) with thermoplastic material or by sewing.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to the technical field of lighting devices and specifically relates to a lighting device with embedded lighting sources, (such as LED&#39;s) arranged in a grid. 
         [0002]    The lighting device can be used in the design of architectural elements, large scale lighting devices or flexible textile garments (such as phototherapy devices). 
       BACKGROUND OF THE INVENTION 
       [0003]    Lighting devices are used in many applications, such as functional lighting devices, luminous architectural and decorative panels. 
         [0004]    An example of a light-emitting textile-based architectural element is disclosed in WO-2011/114263. The architectural element has a layered structure comprising a substrate textile, a diffusive sheet and a cover textile. A plurality of embedded light-sources is arranged in-between the layers such that the light is integrated into the structure. The diffusive layer distributes the light inside the structure and also reduces unwanted ‘glare’ effects. The layered structure in WO-2011/114263 is mounted on a rigid frame so that the layers are placed in the right distance from each other and so that a flat surface is achieved. 
         [0005]    However, there is a need to provide different shapes of luminous articles and provide lighting devices without the need for mechanical frames. Additionally, there is a need to provide large scale architectural panels with a reduced glare effect without the use of diffusive sheets. 
       SUMMARY OF THE INVENTION 
       [0006]    In view of the above, it is an object of the present invention to provide an alternative lighting device and a method for producing a lighting device. 
         [0007]    According to a first aspect of the present invention, it relates to a 
         [0008]    A lighting device, comprising a first and a second sleeve, a first set of at least two interconnecting seams connecting the sleeves to each other, wherein the interconnecting seams are arranged in-between the first and the second sleeves and extend in a transverse direction in relation to a longitudinal direction of the sleeves, and a light emitting arrangement having a plurality of light sources, which is located inside at least one of the sleeves. 
         [0009]    The present invention is based on the realization that by arranging light sources in a layered structure with a specific geometry, the glare effect from the light sources can be reduced. Consequently, the direction and angle of the light can be arranged such that the light is directed into the structure itself. Hence, the glare effect can be reduced without the use of diffusive layers. By excluding the diffusive layer, less amount of light is absorbed by the structure. Moreover, the structure of the lighting device does not need a frame to support the layers, and therefore provides a cost-efficient design of for large scale illumination articles and a garment articles. 
         [0010]    According to an exemplary embodiment, the lighting device further comprises a third sleeve and a second set of interconnecting seams arranged in-between the second and the third sleeves, wherein the first set of interconnecting seams is offset with a distance in relation to the second set of interconnecting seams along the longitudinal direction of the sleeves. In each set of interconnecting seams, the individual seams are arranged at a seam distance from each other. The set of interconnecting seams is offset such that a first seam in a second set is offset in relation to a first seam in a first set. The offset distance being in the range of 25% to 75% of the distance between the interconnecting seams in the same set. The offset seams make it easier to achieve a polygon mesh with sufficiently large openings. An advantage is that with more open meshes in the lighting device the air circulation around the light sources is improved. This can be especially beneficial for large area lighting devices when used in artificial lighting for horticulture applications, or in large area phototherapy textiles. Another advantage is that the acoustical absorption characteristics of the device are improved by the multi-layered structure with cavities. Acoustical properties are often important for large type architectural panels. 
         [0011]    According to an exemplary embodiment, the sleeves are flat with a closed circumference. The flat structure results in larger openings in the polygon mesh and enhances the circulation of light and air. It also creates a smaller structure when the lighting device is in a collapsed state. 
         [0012]    According to an exemplary embodiment, the sleeves are provided with apertures at the location of the light sources. An advantage is that more light can be emitted through the sleeves. 
         [0013]    According to an exemplary embodiment at least two interconnecting seams are arranged in perpendicular to the longitudinal direction of the sleeves. By arranging the interconnecting seams in perpendicular, the openings in the structure have straight walls so that a spectator can see through the architectural panel. Additionally, the circulation of light and sound through the panel is increased. 
         [0014]    According to an exemplary embodiment the interconnecting seams are arranged at an angle different from 90 degrees in relation to the longitudinal direction of the sleeves. By arranging the interconnecting seams at an angle, the openings in the structure are skewed such that a spectator cannot see through the architectural panel. 
         [0015]    According to an exemplary embodiment, the sleeves are flexible. An advantage is that the structure can folded together and easily transported if needed. 
         [0016]    According to an exemplary embodiment, the sleeves are rigid. An advantage is that the structure can be at least partially self-supporting. 
         [0017]    According to an exemplary embodiment, the interconnecting seams comprise a thermoplastic material. Thermoplastic material provides a fast way of joining a sleeve. 
         [0018]    According to an exemplary embodiment, the interconnecting seams comprise a thermoplastic yarn with a heat-resistant core. An advantage of using thermoplastic yarns, is the fact that the connection will be straight, small and strong, based on a selected thermoplastic and heat resistant material combination. Another advantage is that by adjusting the amount and type of thermoplastic material in the thermoplastic, it is possible to create a robust interconnect. This can especially be an advantage in water-tight constructions to be used in horticulture environments. 
         [0019]    According to an exemplary embodiment, the interconnecting seams comprise a thread which is connecting the sleeves to each other in stitched seams. A stitched seam may provide an additional advantage such as an increased tensile strength. 
         [0020]    According to an exemplary embodiment, the sleeves are formed by sheets, which are joined together in longitudinal seams, and wherein the longitudinal seams are chosen from the group of stitched seams, glued seams and thermoplastic seams. The sheet structure provides a flat cross section of the sleeves so that large openings in the polygon mesh can be achieved. 
         [0021]    According to an exemplary embodiment the sleeves comprise a textile material. A textile material is flexible and can easily be provided in different textures, patterns and colors which can cooperate with the light sources in order to achieve a desired type of light in terms of e.g. light intensity, colors, or patterns. 
         [0022]    According to an exemplary embodiment the light emitting arrangement is a flexible carrier on which a plurality of light sources is arranged. An advantage is that the flexible carrier takes the shape of the sleeves and follows the angles in the structure. 
         [0023]    According to an exemplary embodiment, the light sources are low energy light sources, such as LEDs or variable LEDs. An advantage is that less heat is generated inside the sleeves. 
         [0024]    According to a second aspect of the present invention in accordance with the first aspect thereof, it relates to a method of producing a lighting device, the method comprises the steps of:
   A) arranging a first and a second flexible sheet on top of each other, such that they form a first pair of sheets,   B) arranging a third and a fourth sheet on top of each other, such that they form a second pair of sheets,   C) placing the first pair of sheets onto the second pair of sheets and connecting the first pair of sheets to the second pair of sheets,   D) joining longitudinal edges in each pairs of sheets, such that each pair of sheets form a sleeve, and   E) inserting a light-emitting arrangement into at least one of the sleeves.   
 
         [0030]    Production of this lighting device can take place in flat format, finally in use the band is bend so that it corresponds with the shape of the lighting device. 
         [0031]    According to an exemplary embodiment the step of connecting the first and the second pair of sheets, can be performed by: 
         [0032]    placing lines of thermoplastic material between the first and the second pair of sheets, and applying heat to the thermoplastic material. The fusible yarns will enable an easy, automated and flexible production of lighting device. 
         [0033]    According to an exemplary embodiment, the steps included in the method are performed in the listed order from step A to step E. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]    The invention will now be described with reference to the appended drawings, which by way of example illustrate embodiments of the present invention and in which: 
           [0035]      FIG. 1  is a schematic view of a lighting device according to an embodiment of the present invention, 
           [0036]      FIG. 2   a  is a schematic perspective view, partly cut-away, showing the structure of the lighting device in  FIG. 1 , 
           [0037]      FIG. 2   b  is a schematic perspective view of an elongated sleeve according to the present invention, 
           [0038]      FIGS. 3   a  and  3   b  are different embodiments of the position of the interconnecting seams according to the present invention, 
           [0039]      FIG. 3   c  illustrates the position of the light sources in relation to the interconnecting seams according to an embodiment of the present invention, and 
           [0040]      FIG. 4  is a schematic view of manufacturing step in a hot press, and 
           [0041]      FIG. 5  is a flow chart illustrating the steps of an exemplary manufacturing method. 
       
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       [0042]    In the following description, a lighting device according to at least one exemplary embodiment of the present invention is described in the context of a large scale architectural panel. It should be noted that this by no means limits the scope of the present invention, which is equally applicable to other types of industrial applications, such as lighting devices for horticulture, combined shading and lighting devices and phototherapy blankets. 
         [0043]    As schematically illustrated in  FIG. 1 , a lighting device  100  according to the present invention can be produced in the shape of an architectural panel. Now referring to  FIG. 2   a , which shows that a large scale lighting device  100  can be produced in an efficient and flexible way by replicating a polygon structure of elongated sleeves  110  connected by interconnecting seams  120 . In use, the light sources  116  (e.g. LEDs) will emit light through the sleeves  110  and light up openings  150  defined in the polygon structure of the interconnected sleeves  110 . 
         [0044]    The lighting device  100  can be provided with a flexible and collapsible structure by using a flexible material in the sleeves  110 . For instance, the sleeves  110  can comprise a textile material in the shape of woven or non-woven sheets  11 . The textile material may comprise natural or synthetic fibers, metal or plastic. However, the sheet material is not limited to textiles; foils and plastic sheets can also be used, as long as they are at least partially light transparent. 
         [0045]    The lighting device  100  can be placed in various positions and locations, for instance, it can be used as a room/space divider in a vertical position. A vertical position of the lighting device  100  is defined as a position in which the openings  150  of the lighting device are arranged in a horizontal direction. It may also be placed in a horizontal position, by e.g. suspending the device in a ceiling. Consequently, a horizontal position of the lighting device  100  is defined as a position in which the openings  150  of the lighting device are arranged in a vertical direction. If the structure is flexible, cords may be used for suspending the lighting device  100  in a mounted and extended position. 
         [0046]    Alternatively, some or all the sleeves  110  can be provided with rigid sections, such that the structure is partly or completely self-sufficient. The rigidity can be achieved by the material in the flexible sheets  11 . Additionally the lighting device  100  may be post-treated with material in e.g. liquid form that after curing is rigidified. 
         [0047]    The embodiment in  FIG. 2   a , schematically illustrates the structure of the lighting device  100  in an embodiment which comprises four interconnected sleeves  110 . The walls of a first sleeve  110   a  consist of a first  11   a  and a second elongated and flexible sheet  11   b,  arranged together as a first pair and with the edges  12  joined by two longitudinal seams  130 , such that they form a first sleeve  110   a.  Alternatively, a sleeve  110  can be produced from a single sheet  11  that has been folded and closed in one longitudinal seam  130 . 
         [0048]    As illustrated in  FIG. 2   b , by joining the sheets  11  in longitudinal seams  130 , the sleeve  110  has a closed circumference along its longitudinal extension  160 . Additionally, the when two elongated sheets  11  are joined in two longitudinal seams  130 , the hollow cross section of the sleeves  110  can be arranged such that the sleeves  110  are flat. 
         [0049]    A plurality of sleeves  110  can be formed in the same way as the first sleeve  110 . In order to create a meshed structure, the sleeves  110  are stacked, one on top of the other, and connected to the adjacent sleeves  110  in interconnecting seams  120  arranged in-between the sleeves  110 . In the illustrated example, the interconnecting seams  120  consist of a thermoplastic yarn and connect a sheet  11   b  of the first sleeve  110   a  to a sheet  11   a  of the second sleeve  110   b.  Only two sheets  11  are connected by the interconnecting seams  120  at each connection, whereby the sleeves  110  are hollow inside with a free space for introducing a light emitting arrangement  140 . All sleeves  110  can be connected one to the adjacent other in a similar way. The thermoplastic yarn comprises a heat resistant core  112  surrounded by a thermoplastic layer  113 . The heat resistant core  113  can for instance comprise polyester (PES material) with a thermoplastic covering such as thermoplastic polyurethane (TPU), but can also be selected from any types of materials which are commonly known to provide heat resistant characteristics and thermoplastic characteristics. The interconnecting seams  120  between each sleeve  110  are offset in relation to each other with a distance  125 . The offset interconnecting seams  120  creates a polygon meshed structure with the interconnected sleeves  110 . 
         [0050]    The sleeves  110  form a closed structure adapted to house the light emitting arrangement  140  with the plurality of light sources  116 . Alternatively, the sleeves  110  may be provided with apertures in the locations of the light sources  116 , such that more light is emitted through the structure. 
         [0051]    The light emitting arrangement  140  may be a flat flexible band on which LEDs are arranged. The flexible shape can be bent to follow the shapes defined by the interior of the sleeves  110 . 
         [0052]    The light sources  116  may be of LED type. For instance, the LEDs can be of a RGB type (red, green, and blue), which can produce both white light as well as color changing capabilities if they are pixel controlled. The light emitting arrangement  140  can be made from conventional electronics like flexible printed circuit boards. If the light emitting arrangement  140  is a flat flexible band is populated with RGB LEDs including data control, the band can be introduced in a flat format and thereafter bent to correspond with the desired structure of the lighting device  100 . The light sources  116  are positioned inside the sleeves, between the interconnecting seams  120 . 
         [0053]    The structure of the lighting device  100  can be modified by changing the position and angle of the interconnecting seams  120 . As illustrated in  FIG. 3   a , the interconnecting seams  120  may be arranged in perpendicular in relation to the longitudinal direction on the sleeves  160 . As illustrated in  FIGS. 3   b  and  3   c , the interconnecting seams  120  may be arranged at an angle α in relation to the longitudinal direction  150  on the sleeves  110 . By arranging the interconnecting seams  120  at an angle α in relation to the longitudinal direction  160  on the sleeves  110 , the openings  150  in the structure are skewed such that a spectator cannot see through the lighting device  100 . The skewed openings  150  result in a polygon structure in which the light effects from the light sources  116  (e.g. RGB LEDs) can be enhanced. The direct sight  170  into the light sources  116  is limited by the skewed openings  150 , and the outgoing light  180  is diffused over larger area. This can be an advantage in the application of the lighting device  100  as an architectural panel for separating spaces in e.g. a room. 
         [0054]    Additionally, by providing sleeves  110  with a reflective material, the direction of the light from the light sources  116  can be reflected inside the sleeves  110  to create a lighting effect. Moreover, this kind of construction with skewed openings  150  make it interesting for architectural design where it can block transparency under specific angles and allow transparency for other angles. For example this can be achieved by selecting a light transparent material in one sheet  11  and a reflective material in the other sheet  11 . 
         [0055]    As schematically illustrated in  FIG. 4 , the structure of the lighting device  100  can be produced by stacking and joining sheets  11 . After the structure is produced, the light emitting arrangement  140  can be inserted into the structure. A method for producing a lighting device may include the steps of: 
         [0056]    In a first step S 1 , grouping a first  11   a  and a second flexible sheet  11   b  on top of each other, such that they form a first pair of sheets. 
         [0057]    In a second step S 2 , placing lines of thermoplastic yarn  120  on top of the upper sheet  11   a  in the first pair. This thermoplastic yarn  120  can be placed by a wire laying automat. Alternatively, the thermoplastic yarn  120  can be placed in a manual operation. In a third step S 3 , grouping a first  11   a  and a second flexible sheet  11   b  on top of each other, such that they form a second pair of sheets, 
         [0058]    In a fourth step S 4 , placing the second pair on top of the first pair, In a following step, the first and second steps can be repeated, such that a desired size of a stack  200  is created. 
         [0059]    In a fifth step S 5 , applying heat to the stack  200  such that the pair of sheets  11  are connected to each other. 
         [0060]    In a sixth step S 6 , joining longitudinal edges  12  of the sheets  11  in each pair of sheets, such that each pair of sheets forms a sleeve  110 . The edges  12  of each pair of sheets  11  can be joined by gluing the edges  12  together or by stitching. Alternatively, the longitudinal edges  12  may be closed by arranging lines of thermoplastic material in-between the sheets  11  included in each pair in a joint operation with the third step. By performing a joint operation, both the longitudinal  130  and the interconnecting seams  120  can be placed in the same production step. 
         [0061]    In a seventh step S 7 , inserting a light-emitting arrangement  140  into at least one of the sleeves  110 . 
         [0062]    Optionally, the method comprises a in an eight step S 8 , cutting the stack  200  before or after the step of applying heat to the stack  200 . 
         [0063]    Optionally, the method comprises a in a ninth step S 8 , controlling the interconnections between the sheets  11  before slicing it. This step provides a quality control of the structure. 
         [0064]    As schematically illustrated in  FIG. 5 , the production method may include the use of a hot press that activates the thermoplastic material.  FIG. 5  shows a stack of sheets  200  arranged in-between the plates  190  of a hot press machine. The temperature of the stack inside the press should preferably achieve 120 to 150 degrees C., for approximately 20 seconds under a pressure of 6 bar, such that the sheets  11  are bonded to each other. 
         [0065]    After the bonding process is finished, the stack  200  can be sliced in a direction essentially transverse with the interconnecting seams  120  such that the stack  200  is cut into several thinner stacks of interconnected elongated sleeves  110 . Depending on the desired illumination pattern, all or some of the sleeves  110  can be filled with light emitting strips  118 . The process of inserting the light emitting strips  118  can be done manually or with help of tools which can pull the flexible strips  118  through the sleeves  110 . 
         [0066]    The connection between the light emitting arrangement  140  and the sleeve structure is reversible. Bringing back the sleeves  110  to the original format of flat strips, makes it easy to retrieve the light emitting arrangement  140  (e.g. LED strips) out when product comes at end-of-life or at repairs and makes it a sustainable design as well. 
         [0067]    Additionally, the lighting device may also be adapted for more specific purposes, such as the use as a phototherapy blanket, for e.g. treating Jaundice. In particular, the present invention can give the light emitting surface a more comfortable surface. 
         [0068]    A still further example includes horticulture applications, where the plants need a homogeneous light and uniform light intensity. This requires a constant distance between the light source and the plant or vegetable, a water resistant structure. Additionally, the structure has to allow sufficient air/CO 2  concentration around the plant. A flexible lighting system according to the present invention would fulfil this requirement by designing the sleeves from water-tight structure of e.g. plastic sheets. Moreover, the size of the openings in the structure can be adapted, such that the plants can grow inside the openings and receive a well distributed light. 
         [0069]    The skilled person will realize that the present invention by no means is limited to the described exemplary embodiments. 
         [0070]    It is also possible to use alternative methods for producing a lighting device according to the present invention. For instance, the method can involve sewing and can comprise the following steps:
   A) arranging a first set of two sheets on top of each other, one sheet belonging to a first sleeve and the other belonging to a second sleeve,   B) sewing the first set of two sheets together along the extension of the interconnecting seams,   C) arranging a second set of two sheets on top of each other, one sheet belonging to a second sleeve and the other belonging to a third sleeve,   D) stacking the first and the second set of sheets in a direction essentially transverse in relation to the extension of the interconnecting seams, and such that the interconnecting seams are offset,   E) joining longitudinal edges in of the sheets, such that a sheet in a first set of sheets forms a sleeve with a sheet in a second set of sheets, and   F) inserting a light-emitting arrangement into at least one of the sleeves.   
 
         [0077]    Optionally, the method comprises a step of cutting the sheets or stack of sheets in a direction essentially transverse to the extension of the interconnecting seams. The step is performed before the longitudinal edges of the sheets are joined. 
         [0078]    The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Moreover, the expression “comprising” does not exclude other elements or steps. Other non-limiting expressions include that “a” or “an” does not exclude a plurality and that a single unit may fulfil the functions of several means. Any reference signs in the claims should not be construed as limiting the scope. Finally, while the invention has been illustrated in detail in the drawings and in the foregoing description, such illustration and description is considered to be illustrative or exemplary and not restrictive; the invention is not limited to the disclosed embodiments.