WO2012080950A2

WO2012080950A2 - Flexible radiation guide system

Info

Publication number: WO2012080950A2
Application number: PCT/IB2011/055639
Authority: WO
Inventors: Elvira Johanna Maria Paulussen; Liesbeth Van Pieterson; Guofu Zhuo; Marjolein Yvonne JANSEN; Tim Dekker; Lucas Johannes Anna Maria Beckers; Hugo Johan Cornelissen; Jorgen Meeusen; Frank Anton Van Abeelen
Original assignee: Koninklijke Philips Electronics N.V.
Priority date: 2010-12-17
Filing date: 2011-12-13
Publication date: 2012-06-21
Also published as: WO2012080950A3

Abstract

A radiation guide system is described for guiding radiation. The radiation guide system(10) comprises a plurality of distinct radiation guide segments (13). These are arranged for receiving radiation and for coupling out at least part of the radiation through a surface of the radiation guide segments. The radiation guide segments (13) are connected to each other so as to be moveable with respect to each other and so as to construct a single radiation guide system.

Description

Flexible radiation guide system

FIELD OF THE INVENTION

The invention relates generally to flexible illumination systems. More particularly, the present invention relates to a flexible radiation guide system, e.g. a wearable radiation guide providing flexibility and breathability.

BACKGROUND OF THE INVENTION

In many applications, flexible radiation emitting or radiation guiding devices are of great interest. They can be used as wearable or flexible communication displays (e.g. in bags, jackets, curtains, carpets), as phototherapy devices for medical applications (e.g. heat therapy patch, acne treatment, wound healing plaster), or for wellness purposes (massage device). For communication displays, typically visible light is used for making a message visible. In radiation therapy devices, applications for cosmetic, wellness or medical purpose may be envisaged. Particular examples of applications are treatment of skin rejuvenation, acne control, psoriasis, use of infrared products, massage devices or wellness lamps, use of light and heat for pain relief. Nowadays heat therapy is a well established and numerous products such as heat cabins and flood lamps are on the market. Many devices are based on infrared (IR) light, e.g. Philips InfraCare. The benefits of infrared as heat therapy are based on a vasodilatory response in the skin which locally enhances the blood circulation. This results in an increased metabolic rate and transport of metabolites and other essential biochemical compounds. Benefits are also gained by deeper penetration of heat, providing a gentle and pleasant warming effect.

One way to arrive at a flexible radiation emitting or radiation spreading device is to use textile materials, well-known for their comfort, flexibility and breathability.

Photonic textiles can be made which consist of arrays of inorganic LEDs that are integrated into fabrics without compromising the soft look and feel of the textile. Although this technology has many advantages, there are also disadvantages such as the immaturity of the technology and the requirement to the use multiple (low or medium power) LEDs, which could possibly affect the bill of materials. Another alternative to obtaining a flexible light emitting patch is by weaving optical fibers into a fabric-like structure. Radiation can be coupled in on one end of the optical fibers, and is coupled out as a function of bending of the fibers or abrasion of the surface of the fibers. Although this technology combines the good optical properties of fibers with the flexibility and breathability of textiles, the usability is limited because of the low efficiency: the incoupling efficiency in the small diameter fibers is low and so is the outcoupling efficiency in a desired direction, with the majority of the light coupled out at the end of the fiber.

For general illumination systems, the use of one or more radiation guides produced on a uniform sheet is known. Radiation is received in the radiation guide from a radiation source and is guided through the radiation guide towards desired locations where it is coupled out. However, radiation guide materials with superior optical properties, such as polycarbonate or PMMA, show a limited flexibility and bending properties.

Hence, there is a need in the art for flexible radiation-emitting and/or radiation guiding systems which combine the good optical properties of superior radiation guide materials with the flexibility of textile materials or flexible materials such as silicone or thermoplastic elastomers.

SUMMARY OF THE INVENTION

It is an object of the embodiments of the present invention to provide a radiation guide system which combines good optical properties with high flexibility. It is an advantage of at least some embodiments according to the present invention that good optical properties of superior radiation guide materials can be obtained while maintaining a flexibility comparable to textile materials or to flexible materials such as silicone or thermoplastic elastomers. It is an advantage of embodiments of the present invention that radiation guide systems are provided that are at the same time efficient and flexible. It is an advantage of at least some embodiments according to the present invention that radiation guide systems are provided that are at the same time flexible while also providing breathability. It is an advantage of at least some embodiments of the present invention that an efficient incoupling and/or outcoupling of the radiation can be obtained in the radiation guide systems. It is an advantage of embodiments according to the present invention that well established manufacturing techniques may be used for obtaining devices according to embodiments of the present invention. It is an advantage of embodiments according to the present invention that flexible radiation guide systems are provided, wherein the radiation pattern provided by the radiation guide system does not substantially suffer from stretch.

It is an advantage of at least some embodiments according to the present invention that at least one of a front interface and a back interface of a radiation guide segment has a surface structure that guarantees efficient outcoupling of the radiation to at least one of the front side and the back side of the radiation guide system.

In a first aspect, the present invention relates to a radiation guide system for guiding radiation. The radiation guide system comprises a plurality of distinct radiation guide segments, wherein the radiation guide segments are arranged for receiving radiation.

According to embodiments of the present invention, the radiation guide system is

furthermore arranged for coupling out at least part of the incoupled radiation through a surface of the radiation guide segments. According to embodiments of the present invention, the radiation guide segments are connected to each other so as to be moveable with respect to each other and so as to construct a single radiation guide system.

The radiation guide system may furthermore comprise a substrate layer being fabricated from a flexible material, wherein the distinct radiation guide segments are bonded to the flexible substrate layer. It is an advantage of embodiments according to the present invention that flexibility as well as high optical efficiency can be obtained, by combining a flexible substrate layer with optical high grade radiation guide segments.

The radiation guide segments may have a ribbon-like shape. It is an advantage of embodiments according to the present invention that the use of ribbon-like shaped segments allows good propagation of the radiation. The radiation guide segments may be bonded to the flexible substrate layer using any suitable fixation technique for example by means of gluing or lamination techniques, by stitching, weaving, braiding or knitting the radiation guide segments to the substrate, or by self-adherence of the radiation guide segments to the substrate layer due to penetration of the radiation guide material through the substrate fabric.

The radiation guide segments may be made of a rigid, optical grade, material. It is an advantage of embodiments according to the present invention that optical grade material can be used such that good radiation guiding can be obtained.

The flexible substrate may have a refractive index substantially lower than the refractive index of the radiation guide segments. It is an advantage of embodiments according to the present invention that, when the invention is used in a radiation device for applying radiation to the skin, by proper selecting the refractive index of the substrate layer with respect to the refractive index of the radiation guide segments, efficient outcoupling of the radiation from the radiation guide segments can be achieved via the flexible substrate as radiation will be more easily extracted via the side of the radiation guide segments facing the substrate layer, because matching between the refractive index of the flexible substrate and the skin to which radiation is to be coupled out is easier and/or better than matching between the refractive index of the radiation guide segments and the skin. In these embodiments, the flexible substrate is preferably positioned adjacent the radiation guide outcoupling surface.

The flexible substrate layer may comprise a reflective material. It is an advantage of embodiments according to the present invention that by using a reflective substrate layer, efficient outcoupling of the radiation at the outcoupling surface is achieved by reflecting back radiation that was initially directed away from the outcoupling surface. The radiation guide segments may be spaced from the flexible substrate layer using any of spacers on the flexible substrate layer, spacers on the radiation guide segments, a transparent textile material or a silica layer nearly matching the refractive index of air (i.e. open structure silica/non- woven) . It is an advantage of embodiments according to the present invention that a good radiation outcoupling is obtained, by optimizing total internal reflection. In these embodiments, the flexible substrate is preferably positioned opposite the radiation guide outcoupling surface.

The flexible substrate layer may furthermore comprise channels for transporting moisture through the flexible radiation guide system, so as to form a breathable system. It is an advantage of embodiments according to the present invention that by using breathing channels, good optical properties and good flexibility of the radiation guide system can be combined with good breathability.

The radiation guide segments may at least partially be attached to a common radiation guide portion, e.g. at one end of the radiation guide segments, while the radiation guide segments are arranged separate from each other for the other, preferably larger, part, e.g. along an elongated direction of the radiation guide segments. It is an advantage of embodiments according to the present invention that radiation can be coupled in to the radiation guide segments via the common radiation guide portion, resulting in less radiation sources for incoupling radiation to each of the radiation guide segments.

The radiation guide segments may furthermore be arranged relative to each other by weaving, braiding or knitting the radiation guide segments. It is an advantage of embodiments according to the present invention that by using textile-like techniques, a flexible radiation guide system can be easily obtained. The radiation guide segments may be made at least partially of a flexible material and may furthermore comprise strengthening elements to limit the stretching properties of the radiation guide system. It is an advantage of embodiments according to the present invention that the stretching properties of the radiation guide segments can be limited, resulting in only little or no distortion of the radiation pattern obtained with the radiation guide system.

Part of the radiation guide segments may be flexible radiation guide segments and part of the radiation guide segments may be somewhat more rigid or stiff.

A radiation guide system according to embodiments of the present invention may furthermore comprise at least one radiation source for coupling in radiation in the radiation guide segments. The at least one radiation source may be a plurality of radiation sources provided at different sides of the radiation guide segments. It is an advantage of embodiments according to the present invention that by positioning radiation sources at different sides of the radiation guide segments, an improved homogeneity for the irradiation can be achieved.

In a second aspect, the present invention provides the use of a radiation guide system according to embodiments of the present invention for any of dynamic lighting systems, wearable communication displays or photonic therapy.

Particular and preferred aspects of the invention are set out in the accompanying independent and dependent claims. Features from the dependent claims may be combined with features of the independent claims and with features of other dependent claims as appropriate and not merely as explicitly set out in the claims.

For purposes of summarizing the invention and the advantages achieved over the prior art, certain objects and advantages of the invention have been described herein above. Of course, it is to be understood that not necessarily all such objects or advantages may be achieved in accordance with any particular embodiment of the invention. Thus, for example, those skilled in the art will recognize that the invention may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a schematic top view of a flexible radiation guide system according to a first embodiment of the present invention. Fig. 2 is a cross-sectional view of the flexible radiation guide system illustrated in Fig. 1 (cross-section along the dashed line of Fig. 1).

Fig. 3 illustrates different examples of an embodiment of the present invention in which the radiation guide layer is composed of several ribbon-like radiation guide segments.

Fig. 4 is a schematic top view of an embodiment of the present invention, in which each radiation guide ribbon has its own light source.

Fig. 5 is a schematic top view of an embodiment of the present invention, where the radiation sources are placed in turn on opposite sides of the flexible radiation guide system.

Fig. 6 is a schematic top view of an embodiment of the present invention, where the radiation is coupled in from a common side of the radiation guide ribbons.

Fig. 7 is a schematic top view of an embodiment of the present invention, in which the flexible radiation guide system comprises a flexible substrate with a low refractive index.

Fig. 8 is a cross-sectional view of the flexible radiation guide system illustrated in Fig. 7 (cross-section along the dashed line of Fig. 7).

Fig. 9 is a cross-sectional view of an alternative embodiment of the present invention, where the flexible radiation guide system comprises a reflecting flexible substrate layer.

Fig. 10 is a cross-sectional view of an embodiment of the present invention, where an air gap is provided between the radiation guide segments and a reflecting substrate layer.

Fig. 11 illustrates different examples for realizing the functionality of an air gap between the radiation guide segments and a substrate layer.

Fig. 12(a) and Fig. 12(b) illustrate embodiments of the present invention, wherein moisture evacuation channels are provided in the substrate layer.

Fig. 13 to Fig. 15 illustrate embodiment of the present invention wherein radiation guide segments are interconnected or are combined so as to form a single radiation guide system, without a flexible substrate being present.

The drawings are only schematic and are non-limiting. In the drawings, the size of some of the elements may be exaggerated and not drawn on scale for illustrative purposes. Any reference signs in the claims shall not be construed as limiting the scope. In the different drawings, the same reference signs refer to the same or analogous elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Where in embodiments of the present invention reference is made to a radiation guide segment or radiation guide portion, reference is made to an optical structure for guiding electromagnetic waves. According to embodiments of the present invention, the radiation guide portions or radiation guide segments may have a cross-section having a width to height ratio of at least 2. For a radiation guide portion or radiation guide segment having a varying cross-section width to height ratio, the ratio may be at least 2 across at least 50% of its length, more advantageously at least 75%, still more advantageously 90%> of its length. The width may be defined as the dimension corresponding with the largest distance in a cross-section of the radiation guide perpendicular to the average propagation direction of radiation. The height may be defined as the dimension within the same cross-section being perpendicular to the width. For example in a rectangular cross-section the width may correspond with the dimension along the largest side of the rectangular and the height may correspond with the dimension perpendicular thereto (the shortest side). In a radiation guide with an ellipsoid shaped cross-section, the width may correspond with the largest axis of the ellipsoid while the height may correspond with the dimension perpendicular thereto (the shortest axis of the ellipsoid). In the context of this detailed description, waveguide segments or radiation guide portions do not refer to optical fibers.

Where in embodiments of the present invention reference is made to radiation, reference is made to electromagnetic radiation, such as for example visible light, infrared, ultra violet radiation, etc. As used herein, the term radiation source refers to any type of radiation emitting element, and includes for example light emitting diodes (LEDs) such as inorganic LEDs and organic LEDs. Light emitting elements emitting light of any color, from UV to IR, are contemplated in the present invention.

Where in embodiments of the present invention reference is made to portions being connected so as to be moveable with respect to each other and so as to act as a single radiation guide system, it implies that the portions can undergo relative movements with respect to each other, but cannot be disconnected from each other without significantly reducing the functionality of the radiation guide system or physically destroying the radiation guide system. The system therefore acts as a single radiation guide system. In a first aspect, the present invention relates to a fiexible radiation guide system. Such a fiexible radiation guide system may be used for any suitable application, such as for example, for dynamic interior lighting systems like furniture upholsteries, curtains, carpets, for wearable communication displays such as in backpacks or cloths, for photonic therapy devices, such as for example baby jaundice sleeping bags, acne treating t-shirts, wound healing plasters, heat or radiation treatment plasters, etc. According to some embodiments of the present invention, the radiation guide system comprises a plurality of distinct radiation guide segments having a rectangular cross-section. The radiation guide segments are distinct, meaning that propagation of electromagnetic radiation in these segments can be confined to these segments. The radiation guide segments of the radiation guide system are arranged for receiving radiation from a radiation source and for coupling out at least part of that radiation through a surface of the radiation guide segments. The radiation guide segments are connected to each other so as to be moveable with respect to each other and so as to act as a single radiation guide system. An advantage of such embodiments is that a fiexible system is obtained, while also good optical properties of the system can be achieved. According to one set of embodiments of the present invention, the obtained system comprises a fiexible substrate supporting the radiation guide segments, whereas according to another set of embodiments, the radiation guide segments can be arranged and connected so as to be moveable with respect to each other without the presence of a fiexible substrate. By way of illustration, different possible embodiments are discussed below.

According to one set of embodiments, the system comprises a plurality of radiation guide segments and a substrate layer being made of a fiexible material. The radiation guide segments are configured such that at least part of the radiation emitted by a radiation source is coupled in into at least one of the radiation guide segments. The radiation guide segments advantageously are arranged such that at least part of the radiation coupled into the radiation guide segments is efficiently coupled out through at least one of a front interface and a back interface of the radiation guide segments. Fig. 1 (top view) and Fig. 2 (cross-section) illustrate a first embodiment of a flexible radiation guide system 10 according to the present invention, comprising a flexible substrate layer 11 and a radiation guide layer 12 composed of several radiation guide segments 13. The radiation guide segments 13 have a front side 14 facing the flexible substrate 11 and a back side 15 facing away the fiexible substrate 11. The fiexible substrate layer 11 can be made of any suitable material, for example flexible silicon or thermoplastic elastomers such as polyurethane. Alternatively, the flexible substrate 11 may be for example a woven textile, a non- woven textile, a knitted textile, or a foam. The flexible substrate layer material may be selected for being suitable for contacting human or animal skin. It is an advantage of an embodiment of the radiation guide system 10 according to the present invention that increased flexibility of the radiation guide system 10 is achieved at low cost, since the flexible substrate layer 11 does not need to be necessarily manufactured from a high transparent optical grade material used for radiation guiding and transport across the radiation guide system 10. In the embodiment illustrated in Fig. 1, the radiation guide layer is composed of several pie/wedge shaped radiation guide segments 13. The number and the shape of the radiation guide segments may be adapted to the shape of a desired illumination/radiation area. For example, also rectangular or trapezoidal radiation guide segments 13 may be arranged on the circular substrate layer 11. In another embodiment of the present invention, the radiation guide layer 12 of the flexible radiation guide system 10 may be composed of several ribbon- like radiation guide

segments 13. Several examples of a radiation guide systems 10 according to this embodiment are illustrated in Fig. 3 A to Fig. 3C. Fig. 3 A shows a rectangular radiation guide system 10 comprising multiple ribbon- like radiation guide segments 13 which are arranged on a flexible substrate 11 in one direction. Alternatively, the radiation guide segments 13, e.g. radiation guide ribbons, may be used in two or more directions. The radiation guide segments 13 may be arranged on the substrate layer 11 without any contact region between the different ribbons, or they may be connected via one or more common sides. Such common sides may be used for coupling in the radiation from one or more common radiation sources. Fig. 3B shows an example of a comb-like radiation guide system 10, wherein four parallel radiation guide segments 13 are attached to a single common orthogonal radiation guide portion 16. In another embodiment of the present invention, the radiation guide layer may be divided into a plurality of radiation guide segments 13 by making holes or grooves in a uniform sheet or foil of radiation guide material. This can for example be done by means of laser cutting or injection moulding. Fig 3C shows a radiation guide system 10 comprising several radiation guide segments 13, in the present example being radiation guide ribbons, which are fabricated from a single sheet of radiation guide material by making channels 17 in the length direction of the segments 13, thereby separating the segments. The radiation guide segments 13 may be bonded to the flexible substrate 11 for example by using gluing or lamination techniques, by stitching, weaving, braiding or knitting the radiation guide segments 13 to the substrate, or by self-adherence of the radiation guide segments 13 to the substrate due to penetration of the radiation guide material through the substrate fabric. It is an advantage of creating radiation guide segments instead of using the full radiation guide sheets that an improved flexibility of the radiation guide system can be achieved. Uniform radiation guide layers which are fabricated as sheets or foils have a limited bending properties; they can only bend easily along one axis. Bending in two directions

simultaneously is only limited possible with more stretchable low elasticity modulus materials, which often have poor optical properties. By using multiple radiation guide segments 13 attached to a flexible substrate layer 11, the lack of flexibility associated with a full sheet of radiation guide material can be partially removed and replaced by flexibility offered by the flexible substrate layer.

It is an advantage of a radiation guide system 10 according to the present invention that the optical material of the radiation guide segments 13 can be selected as a function of the wavelength of the radiation emitted by the radiation source. According to the embodiments of the present invention, the radiation guide segments 13 may be made of a rigid material with superior radiation guiding properties such as polycarbonate or PMMA. In an alternative embodiment, if optical properties such as a higher absorption are allowed, the radiation guide segments 13 may be replaced with a more flexible material, for example PDMS. PDMS ribbons are easily bendable and stretchable, and are preferred in radiation guide systems 10 where the radiation guide segments 13 are bonded to the flexible substrate 11 using textile-like techniques. Extensive stretching of the radiation guide system 10 however might distort the optical performance of the system. In various applications a good bending behavior, but limited stretching of the radiation guide system 10 might be required. Parallel use of flexible PDMS radiation guide ribbons and strengthening elements like stiff PMMA or POF fibers and ribbons may limit the stretching of the radiation guide system 10. Alternatively, a stiff fiber may be incorporated in the flexible PDMS radiation guide. In yet another alternative embodiment, the stretching of the radiation guide system 10 may be limited by arranging the radiation guide segments 13 on a substrate layer 11 from which the stretchability is fully or locally limited by using a non-stretching or limited-stretching material, for example a woven, knitted, embroidered or non-woven fabric.

Apart from the improved flexibility, the use of multiple radiation guide segments 13 allows coupling in of radiation from different sides of the radiation guide system 10. In the case of the disk-shaped radiation guide system of Fig. 1, a radiation source may be placed in the centre of the radiation guide system 10, allowing for a simultaneous illumination of the multiple radiation guide segments 13. Alternatively, several radiation sources may be located in center of the radiation guide system 10. In the case of ribbon- like radiation guide segments 13, each ribbon may have its own radiation source. This is illustrated in Fig. 4, where the radiation guide system 10 comprises several radiation guide segments 13 which each receive radiation from their own radiation source 20. In the embodiment of Fig. 4, the radiation sources 20 are arranged on one side of the radiation guide system 10. Alternatively, as illustrated in Fig. 5, the radiation sources 20 may be placed in turn on opposite sides of the radiation guide system 10, to improve the homogeneity of the out-coupled radiation. When the radiation guide ribbons are in contact with one another through a common radiation radiation guide portion, one or more common radiation sources 20 may be used to couple in radiation from the common side of the radiation guide segments 13. This is illustrated in Fig. 6 for a comb-like radiation guide system 10.

A flexible radiation guide system 10 according to the embodiments of the present invention is arranged such that at least part of the radiation emitted by a radiation sources is coupled in into at least one of the radiation guide segments 13. Therefore, it is desired that the cross-section of the radiation guide segments 13 at the incoupling side is adapted in such way that the amount of radiation which is coupled in into the radiation guide layer 12 is as large as possible. Typically, a thickness and width of the radiation guide segment 13 at the incoupling side may be at least 1,5 times the diameter of the radiation source. In some embodiments the larger of thickness or width of the radiation guide segment at the incoupling side may be for example between 3 mm and 10 mm, e.g. between 4 mm and 6 mm. Furthermore, according to the embodiments of the present invention, the radiation guide system 10 is arranged such that at least part of the incoupled radiation is efficiently coupled out towards at least one of a front side and a back side of the radiation guide system 10. In one embodiment of the present invention, efficient outcoupling of the radiation may be obtained by gradually decreasing the thickness of the radiation guide segment 13 from the incoupling side of the radiation guide segment 13 towards the opposite (end) side of the radiation guide segment 13, until a thickness of for example 0 mm is achieved.

In another embodiment of the present invention, at least one of a front side and back side of the radiation guide segments 13 may have a surface structure or property that supports efficient outcoupling of the incoupled radiation. The surface structure may be obtained by any suitable method known in the art, for instance by means of moulding. As will be shown, in one example, such a surface structure may be a reflecting surface or may be a surface supporting total internal reflection.

In yet another embodiment of a radiation guide system 10 according to the present invention, efficient outcoupling of the radiation from the radiation guide layer 12 may be achieved by making use of a flexible substrate 11 material with a low refractive index. One example is illustrated in top view in Fig. 7 and in cross-sectional view in Fig. 8. The radiation guide system 10 comprises a flexible substrate 11 with a low refractive index and several trapezoidal radiation guide segments 13 with a high refractive index. Preferably, the flexible substrate 11 has a refractive index that is higher than 1 , but lower than the refractive index of the radiation guide material. For example, the radiation guide segments 13 may be made from polycarbonate (refractive index n = 1.58), whereas the flexible substrate layer 11 may be a silicone layer (refractive index n = 1.41). In the embodiment illustrated in Fig. 7 and Fig. 8, two radiation sources 20 emit radiation in the centre 80 of the radiation guide system 10. Radiation 81 which is coupled in into one of the radiation guide segments 13, will, depending on its angle of incidence at the incoupling surface, encounter one of the front interface surface 14 and the back interface surface 15 of the radiation guide segment 13. Since the vertical distance between the front interface surface 14 and the back interface surface 15 of the radiation guide segment 13 decreases with increasing distance from the incoupling surface 82, the angle of incidence of the incoupled radiation 81 at the interface surfaces will gradually decrease with the number of internal reflections, until it finally falls below the critical angle for total internal reflection. At this point, radiation 81 will be coupled out from the radiation guide segment 13, and irradiate one of the front side and the back side of the radiation guide system 10. By using a flexible substrate layer 11 with a low refractive index, the critical angle for total internal reflection is higher at the interface 14 between the radiation guide segment 13 and the substrate layer 11, than at the interface 15 between the radiation guide segment 13 and air. When the front side is in contact with the skin and a refractive index match between the skin and the substrate 11 at the front side 83 of the radiation guide system 10, radiation 81 will more easily be coupled out of the radiation guide segments 13 via the front side 83 than via the back side 84 of the radiation guide system 10.

In an example application, at the front side 83 of the flexible radiation guide system 10, the system may be in contact with the skin of a human being. Radiation that is coupled in into one or more radiation guide segments 13 will be directed to the front (skin) side 83 of the radiation guide system 10, and an efficient irradiation of the skin will be achieved.

In yet another embodiment of the present invention, efficient outcoupling of the radiation 81 from the radiation guide layer 12 is obtained by using a flexible substrate 11 composed of a reflecting material at the back side of the radiation guide system. An example is illustrated in Fig. 9. The flexible substrate layer 11 may be made of any suitable reflective material, for example white silicone or white TPE material. At least part of the radiation emitted by a radiation source 20 will be coupled in into one or more radiation guide segments 13. Due to the wedge shape of the radiation guide segments 13, part of the incoupled radiation 81 will be coupled out towards the front side 83 of the radiation guide system 10, whereas the other part will be coupled out towards the back side 84 of the radiation guide system 10. As the flexible substrate layer 11 in this embodiment is made of a reflective material, the part of the radiation that couples out towards the back side 84 of the radiation guide system 10, will be reflected back towards the front side 83 of the radiation guide system 10. In this embodiment where the substrate layer 11 includes a reflector, radiation outcoupling may be realized at the other side, opposite to the side where the substrate is arranged. Moreover, when used for the irradiation of skin, at least a part of the radiation 81 which is coupled out on the skin side 83 of the radiation guide layer 12 will be reflected back from the skin and enter again in the radiation guide segment 13. By using the flexible substrate layer 11 as a reflector, this reflected radiation will be guided to the reflecting substrate layer 11 and will be reflected back to the skin again. Hence, efficient out coupling of the radiation 81 from the radiation guide layer 12 towards the skin side 83 is obtained.

In a preferred embodiment, an air gap between the substrate layer 11 and the radiation guide layer 12 may be provided for a maximal radiation guiding effect. This is illustrated in Fig. 10. Due to the presence of the air gap, conditions are optimally fulfilled for total internal reflection and an increased breathability of the radiation guide system 10 is achieved. To maintain the air gap 100 between the radiation guide layer 12 and the flexible substrate 11, several methods can be applied, as illustrated in Fig. 11. In Fig. 11(a), the air gap 100 between the reflecting substrate layer 11 and the radiation guide segment 13 is maintained by making use of structures 110 with a certain height that are moulded on the radiation guide segment 13. Alternatively, the structures 110 may afterwards be printed onto the radiation guide segment 13 by means of screen-printing or hot embossing. The height and the distance of the structures 110 may be chosen in such a way, that the air gap 100 is maintained over the whole length of the radiation guide segment 13. The structures 110 may be made from a transparent or a white high reflective material. In Fig. 11(b), the air gap 100 between the reflector 11 and the radiation guide segment 13 is maintained by making use of structures 111 that are moulded on the reflector 11. Alternatively, the structures 111 may afterwards be printed onto the reflector 11 by means of screen-printing or hot embossing. The structures 111 may be of the same material as the flexible reflector 11. In yet another embodiment, as illustrated in Fig. 11(c), an intermediate layer 112 may be arranged between the radiation guide segment 13 and the reflecting substrate layer 11 to maintain the air gap 100. The intermediate layer 112 may made from any suitable material. For example, the intermediate layer may be a high transparent textile, a foam or a silica layer.

It is an advantage of a flexible radiation guide system 10 according to the present invention, that the substrate layer 11 may be furthermore adapted to form a breathable layer, such that moisture, coming from the skin side of the radiation guide material, can evaporate towards the environment. Breathability of the substrate layer 11 may be obtained by using a very thin flexible substrate layer, or by producing the substrate layer from a breathable material such as TPE. In an alternative embodiment, an enhanced breathability of the radiation guide system 10 may be achieved by providing perforations such as holes, grooves or channels in the flexible substrate 11. Examples of radiation guide systems 10 with a perforated flexible substrate layer 11 are illustrated in Fig. 12. Fig. 12(a) shows a radiation guide system 10 wherein the radiation guide layer 12 is composed of multiple trapezoidal radiation guide segments 13. The radiation guide segments 13 are arranged on a flexible substrate layer 11, which comprises several breathable grooves 120 which are radial symmetrically arranged in the substrate layer 11. The breathable

grooves 120 are located in between the radiation guide segments 13, and allow moisture, coming from the skin side of the radiation guide system, to escape to the environment.

Fig. 12(b) shows an alternative embodiment, wherein the grooves 120 are centrifugal arranged in the substrate layer 11.

According to some embodiments of the present invention, the radiation guide segments are not or only partially supported by a flexible substrate layer. Fig. 13 for example shows a radiation guide system 10 according to the present invention, wherein the radiation guide layer 12 comprises a plurality of parallel radiation guide ribbons 13 and a single orthogonal radiation guide portion 16, not supported by a substrate. A common side of the parallel ribbons 13 touches one side of the orthogonal portion 16, such that a comb-like radiation guide system 10 is formed. In an alternative embodiment, as illustrated in Fig. 14, a second orthogonal radiation guide portion 16 may be included, wherein opposite sides/ends of the parallel radiation guide ribbons 13 touch a respective orthogonal radiation guide portions 16.

Fig. 15 shows an example of a radiation guide system 10, wherein several radiation guide segments 13 are woven to form a textile-like structure. A checkerboard- like weaving pattern is thereby obtained, but any other suitable pattern which gives rise to a flexible radiation guide system 10 may be used. Apart from weaving, the radiation guide segments 13 may also be connected by using other textile-like techniques such as braiding and knitting. In case textile-like techniques are applied, the ratio of the width and height of a cross-section of the separate radiation guide segments 13 should be at least 2, preferable larger than 5.

In an alternative embodiment, the radiation guide segments may be woven into a textile substrate. In the example of Fig. 3(a), the radiation guide segments 13 are woven in one direction, but several weaving directions may be used. Alternative patterns may be achieved by changing the number of radiation guide segments, or by changing the sequence by which the radiation guide segments are woven in the textile substrate 11.

While the invention has been illustrated and described in detail in the drawings and foregoing description, such illustration and description are to be considered illustrative or exemplary and not restrictive. The invention is not limited to the disclosed embodiments.

Other variations to the disclosed embodiments can be understood and effected by those skilled in the art in practicing the claimed invention, from a study of the drawings, the disclosure and the appended claims. In the claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. A single processor or other unit may fulfill the functions of several items recited in the claims. 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. A computer program may be stored/distributed on a suitable medium, such as an optical storage medium or a solid-state medium supplied together with or as part of other hardware, but may also be distributed in other forms, such as via the Internet or other wired or wireless telecommunication systems. Any reference signs in the claims should not be construed as limiting the scope.

The foregoing description details certain embodiments of the invention. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the invention may be practiced in many ways. It should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to include any specific characteristics of the features or aspects of the invention with which that terminology is associated.

Claims

CLAIMS:

1. A radiation guide system (10) for guiding radiation, the radiation guide system (10) comprising a plurality of distinct radiation guide segments (13), wherein the radiation guide segments are arranged for receiving radiation and for coupling out at least part of the radiation through a surface of the radiation guide segments, the radiation guide segments having a cross-section with a width to height ratio of at least 2, wherein the radiation guide segments (13) are connected to each other so as to construct a single radiation guide system wherein the radiation guide segments are moveable with respect to each other.

2. A radiation guide system (10) according to claim 1, wherein the radiation guide segments (13) have a ribbon- like shape.

3. A radiation guide system (10) according to any of the previous claims, wherein the radiation guide segments (13) are made of an optical grade material.

4. A radiation guide system (10) according to any one of the previous claims, wherein the radiation guide system (10) comprises furthermore a substrate layer (11) being produced from a flexible material, and wherein the distinct radiation guide segments (13) are attached to the flexible substrate layer (11).

5. A radiation guide system (10) according to claim 4, wherein the flexible substrate has a refractive index substantially lower than the refractive index of the radiation guide segments (13) so that matching between the refractive index of the flexible substrate and of skin is better than matching between the refractive index of the radiation guide segments and of skin.

6. A radiation guide system (10) according to claim 4, wherein the flexible substrate layer (11) comprises a reflective material.

7. A radiation guide system (10) according to claim 6, wherein the radiation guide segments (13) are spaced from the flexible substrate layer (11) using any of spacers on the flexible substrate layer (11), spacers on the radiation guide segments (13), a transparent textile material or a silica layer.

8. A radiation guide system (10) according to any of the claims 4 to 7, wherein the flexible substrate layer (11) comprises channels for transporting moisture through the flexible radiation guide system (10), so as to form a breathable system.

9. A radiation guide system (10) according to any of the previous claims, wherein the radiation guide segments are attached to a common radiation guide portion at at least one side, while being separated from each other over at least one other side along an elongated direction of the radiation guide segments.

10. A radiation guide system (10) according to any of the previous claims, wherein the radiation guide segments are connected to each other by weaving, braiding or knitting the radiation guide segments.

11. A radiation guide system (10) according to any of the previous claims, wherein the radiation guide segments (13) are made at least partially of a flexible material and furthermore comprises strengthening elements to limit stretching of one or more components of the radiation guide system (10).

12. A radiation guide system (10) according to any of the previous claims, wherein a first part of the radiation guide segments (13) are flexible radiation guide segments and a second part of the radiation guide segments (13) are more rigid.

13. A radiation guide system (10) according to any of the previous claims, the radiation guide system furthermore comprising at least one radiation source for coupling in radiation in the radiation guide segments.

14. A radiation guide system (10) according to claim 13, wherein the at least one radiation source is a plurality of radiation sources provided at different locations relative to the radiation guide segments (13).

15. Use of a radiation guide system according to any of claims 1 to 14 in any of dynamic lighting systems, wearable communication displays or photonic therapy devices.