WO2013105007A1

WO2013105007A1 - Light-emitting textile

Info

Publication number: WO2013105007A1
Application number: PCT/IB2013/050090
Authority: WO
Inventors: Gerrit Oversluizen; Jacobus Petrus Johannes VAN OS; Liesbeth Van Pieterson
Original assignee: Koninklijke Philips N.V.
Priority date: 2012-01-12
Filing date: 2013-01-04
Publication date: 2013-07-18

Abstract

A light emitting textile device (1, 1A, IB) is provided comprising a first textile sheet (3) comprising conductors (5) and at least one light source (7) connected to the conductors and being configured to emit first light (9) at a first wavelength. The device comprises a second textile sheet (11) arranged over at least a portion of the first sheet and being configured to be illuminated by the first light. The second sheet comprises a photoconversion material configured to convert incident first light at the first wavelength to emitted second light at a second wavelength, different from the first wavelength. The device is configured to illuminate an object with at least a portion of at least the second light.

Description

Light-emitting textile

FIELD OF THE INVENTION

The present disclosure relates to light emitting textiles and devices comprising the same, in particular human wearable textile devices, and phototherapy devices.

BACKGROUND OF THE INVENTION

Electronic textiles comprising light-emitting elements are known, as well as devices made thereof. Such textile and devices comprise a plurality of light sources, e.g. light emitting diodes, LEDs. According to WO 2011/135502 the light emitted from the light emitting diodes may be conducted through a light guide and it may be wavelength converted by fluorescent material provided on or in the light guide.

However, a demand for further improvements in user comfort and versatility of optically active human wearable devices is felt.

SUMMARY OF THE INVENTION

In an aspect, a light emitting textile device is provided comprising a first textile sheet comprising conductors and at least one light source connected to the conductors and being configured to emit first light at a first wavelength. The device comprises a second sheet arranged over at least a portion of the first sheet and being configured to be illuminated by the first light. The second sheet comprises a photoconversion material configured to convert incident first light at the first wavelength to emitted second light at a second wavelength, different from the first wavelength. The device is configured to illuminate an object with at least a portion of at least the second light. In at least said portion of the second sheet the second sheet is a textile sheet.

Textile materials combine strength in various directions with flexibility of the material, and they may effectively form substrates for plural objects attached to the textile, e.g. conductors, light sources and/or connectors. It has been found that devices that are often bent during use and that comprise layers of different materials may tend to show

delamination wear, whereas devices comprising materials with largely similar or even substantially identical properties as in the presently provided device are more robust against such wear. Further, textile materials may be processed with various techniques to form human body wear, e.g. clothing and/or patches, plasters etc. Textile materials are therefore very well suited for supporting electrical structures close to a human body.

One or more small, point-like light sources, e.g. Light Emitting Diodes ("LEDs") may be used as light source emitting light at the first wavelength. LEDs have several benefits, among others they may have a relatively small size/envelop, a high electrical-to-optical efficiency, provide a low thermal load, provide a desired light color and/or allow accurate operation control, e.g. with respect to switching on/off and/or output power.

The photoconversion material provides light at another wavelength (color) than the first light from the light source, so that an additional light source emitting at the second wavelength may be obviated. This is in particular beneficial when light sources at the second wavelength have drawbacks such as providing little power, being energy inefficient, delicate and/or expensive compared to light sources at the first wavelength.

Benefits of the present device further comprise that, compared to light emitting textiles wherein the light source itself comprises a photoconversion layer, a remote photoconversion solution is provided, which facilitates providing a relatively large surface area for emission of the photoconverted light. Also, manufacturing costs may be reduced. Textile is further a suitable carrier for photoconversion materials since it may provide a large surface area per volume (e.g. carriers with a sheet or plane like shape), which surface area may serve as emission surface and/or may be used for adhering or attaching photoconversion materials. Due to the three-dimensional structure of textile, textile is very efficient for redistribution of directed light, e.g. by scattering, diffusing etc., further the photoconversion materials may be arranged in various directions and assist in redistribution of the light. A large surface area for absorption of the first light and emission of the second light and/or scattering of the first and/or second light may therefore be provided, also when used with a small, point-like light source, e.g. an LED, and in particular when the second sheet is arranged in the optical path of the light source in between the light source and an emission surface of the device for illuminating another object, the second sheet possibly providing the emission surface.

The first and second textile sheets may be attached together by any suitable method, e.g. sowing, gluing and/or welding, in particular, the first and second sheets may be laminated together, such as by being glued or otherwise adhered together over substantially their full overlapping surface areas. In the context of this disclosure, "textile material" or "textile sheet" should be understood as a material or sheet that is wholly or partly made of fibers which may be provided in the form of single fibers or filaments or be bundled together in a multi- fiber configuration, e.g. a yarn. The textile material may be manufactured in any suitable manner, e.g. weaving, braiding, knitting, crocheting, quilting, felting etc. The textile material may be woven or non-woven. The material may be further treated, e.g. dyed and/or coated. The first and second sheets may be of any material that can be suitably processed in textile form, e.g. wool, cotton, linen and/or synthetic materials such as nylon, polyamide, acrylic, etc.

Synthetic fibers facilitate incorporation of the photoconversion material within the fibers, preventing their loss and therewith increasing robustness.

Photoconversion materials should be understood as materials that absorb light at one wavelength and emit light at another wavelength, such as by fluorescence or phosphorescence. The emitted light may generally have a longer wavelength than the incident light but wavelength upconversion is also possible.

In an advantageous embodiment, the device is a piece of human body wear. In particular, the first and second wavelengths may be selected for phototherapeutic use. Also, or alternatively, the device may be used for ornamental and/or utilitarian purposes, wherein the first and/or second wavelengths have an ornamental and/or signaling function.

At least the second sheet, advantageously also the first textile sheet may be gas and humidity permeable to allow the skin of the wearer to breathe when the device is arranged (e.g. worn) close to the body of a subject, facilitating prolonged wear of the device and/or wear in close contact to the skin.

It is preferred that at least a portion of the device, in particular at least one of the first and second sheets, more in particular the first sheet or an outer sheet is liquid repellent, e.g. water droplet repellent to prevent ingress of liquid into the device which might damage the device. This facilitates wear of the device on a body in daily use and/or outdoor use. Textiles providing on the one hand breathing pores and on the other hand being substantially waterproof, either by the nature of the fabric or due to a particular coating are commercially available from various suppliers.

The photoconversion material may be arranged in and/or on apertures in the textile sheet, so as to facilitate optical access by the first light to the photoconversion material. The apertures may be inherent in the fabric of the textile material, e.g. as in a wide- mesh woven fabric, a loosely knitted fabric, or a grid-shaped non- woven fabric, or they may be provided in the material afterwards by separating and/or cutting fibers and/or yarns of the material or local chemical, mechanical or heat processing of the material. The photoconversion material may close the aperture wholly or partly.

The photoconversion material may comprise a photoconverting agent embedded in a silicone comprising host material. Such material has excellent

biocompatibility so that the material may be worn close to the human skin for prolonged times.

The photoconversion material may also or alternatively be provided in or on fibers or yarns for manufacturing the second sheet, this facilitates providing a substantially homogeneous distribution of the photoconversion material in the second sheet and/or facilitates retention of the photoconversion material in the textile material, increasing its robustness and resistance to wear.

The photoconversion material may be patterned on the textile material and/or fibers or yarns for manufacturing the textile material, or be provided uniformly on or in at least a portion of the textile material, possibly by local chemical, mechanical or heat processing of the textile material itself.

The device may be configured to illuminate an object with both the first and second wavelengths or with substantially only the second wavelength, e.g. wherein substantially all light from the first wavelength is absorbed and converted by the

photoconversion material.

At least a portion of the second sheet may comprise fibers or yarns that are at least translucent, possibly transparent, for at least one of the first and second wavelengths, so as to reduce obstruction to light at the respective wavelength(s). Also, or alternatively, at least part of at least one of the first and second sheets may be high-reflective for at least one of the first and second wavelengths, so as to reduce absorption of to light at the respective wavelength(s) and improve scattering thereof. Either or both options facilitate achieving an increased homogeneity and/or effectiveness of illumination from or through the second sheet of the device. Adjacent portions of a fiber or yarn may have different properties, e.g. a translucent portion being arranged adjacent a silvered or otherwise high-reflective portion. A mixture of fibers and/or yarns with different optical properties for the first and/or second wavelength may also be provided. Where it is desired that only light of the second

wavelength is emitted from the device, fibers and/or yarns of at least the second textile may be provided as strongly absorbent of the first wave light, whereas being translucent and/or reflective for the second wavelength. Optical properties of the fibers or yarns may be inherent to the used material and/or be due to treatment such as a dye and/or an applied coating. In an advantageous embodiment, the light source is configured to emit light in the wavelength range of about 400-600 nm, preferably blue or ultraviolet light in the wavelength range of about 400-500 nm. Such wavelengths have proven very effective in exciting photoconversion materials. Further, light at these wavelengths, in particular around 450 nm, are thought to have bio stimulating effects when incident on human skin, such as pain relief, stimulating blood perfusion and/or inducing formation of nitric oxide.

Although the photoconversion material may be configured to emit any desired visible or invisible light, in a preferred embodiment the second wavelength may be in the range of about 550-2500 nm, in particular in the range of about 550-1500 nm e.g. in the range 550-700 nm and/or in the range 700-900 nm, which wavelengths are considered particularly beneficial for treating pain relief and/or for providing an agreeable warmth sensation.

Suitable photoconversion materials for operation with the above-mentioned wavelength ranges comprise a fluorescent material based on quantum dots and/or materials comprising Tellurium-doped Yttrium Aluminium Garnet (YAG:Tm), Copper- CadmiumSulphide (Cu-CdS), Sodium-Barium Sulphate (Na-BaS0₄), Europium (Eu(2)) and/or transition metals. Such substances have a relatively high absorption efficiency in the blue wavelength range and high emissivity in the red to near infrared wavelength ranges. Such substances may also be embedded and retained in silicone host materials without substantial degradation.

One or more further photoconversion materials may be provided that are configured to convert incident first and/or second light at the first and/or second wavelengths to emitted third light at a further wavelength, different from the first and second wavelengths. In an embodiment at least two of the first, second, and further wavelengths are suitable for phototherapy. In a particular embodiment the second wavelength and the further wavelength from the photoconversion material respectively further photoconversion material are suitable for phototherapy whereas the first wavelength from the light source is especially suitable for exciting the photoconversion materials. In the latter case, the light source need not be selected to meet a specific phototherapeutic use but may be selected for its power efficiency, light output, preferable phosphor excitation wavelengths etc. The first lights source may for example be a UV light emitting light source and the photoconversion material and further photoconversion material may be excited to emit blue respectively red/IR light. It is noted that operation of a photoconversion material may be controlled by controlling operation of the first light source, e.g. by adjustment of the intensity, colour and/or colour temperature of the respective light source, and that the intensity and distribution of the photoconverted light may be controlled by the concentration and/or distribution of the photoconversion materials across the second textile sheet.

In a particularly advantageous embodiment, the device is formed as a patch for conforming to at least part of a body part and illuminating the body part with light at the second wavelength, e.g. as a plaster, a bandage, or another form of wrap for a body part such as a wrist band, sleeve or leg warmer. In particular in case of a device emitting in the above- mentioned wavelength range of about 550-2500 nm, in particular in the range of about 550- 1500 nm e.g. in the range 550-700 nm and/or in the range 700-900 nm, such patch may be very efficient for treating pain and/or provide a general feeing of well-being. In an embodiment, wavelengths for biostimulation of skin processes, e.g. amber light for skin rejuvenation, may be provided. The combination of photoconversion material with textile facilitates prolonged wear of the patch. Providing a functional device on a textile basis also allows applying the device inconspicuous, in particular in combination with "regular" clothing.

The device may comprise one or more further electronic components, e.g. comprising a controller for operating the light source and possibly a memory which may be programmable.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

Fig. 1 illustrates a first embodiment of a textile illumination device;

Figs. 2A-2B illustrate a method of manufacturing a second embodiment of a textile illumination device;

Fig. 3 is a cross section view of another embodiment.

DETAILED DESCRIPTION OF EMBODIMENTS

It is noted that in the drawings, like features may be identified with like reference signs. It is further noted that the drawings are schematic, not necessarily to scale and that details that are not required for understanding the present invention may have been omitted. The terms "upward", "downward", "below", "above", and the like relate to the embodiments as oriented in the drawings. Further, elements that are at least substantially identical or that perform an at least substantially identical function are denoted by the same numeral, where useful individualized by an alphabetic suffix. Fig. 1 is an exploded view of a light emitting textile device 1 comprising a first textile sheet 3 comprising conductors 5 and a plurality of light sources 7 connected to the conductors 5 and being configured to emit first light 9 at a first wavelength. Here, the light sources 7 are formed as forward emitting surface mounted LEDs fixed to the first textile sheet 3. The device 1 further comprises a second sheet 11 arranged over a portion of the first sheet 3 and being configured to be illuminated by the first light 9. The second sheet 11 comprises a photoconversion material configured to convert incident first light at the first wavelength to second light at a second wavelength, different from the first wavelength. Here, the photoconversion material is provided in plural objects formed as lenses 13 patterned on the second textile sheet corresponding with the positions of the LEDs 7 on the first textile sheet 3.

Such patterning may be done by stamping, screen printing, ink jet printing, dispense processing (e.g. liquid silicone dispensing with possible subsequent curing) of a substantially flowable or deformable mass. A further method comprises gluing, possibly preformed, objects of the photoconversion material to the textile sheet, e.g. by a pick-and- place technique. This may be done prior to or after arranging the second sheet over the first sheet.

Figs. 2A-2B illustrate a method of manufacturing another embodiment of a light emitting textile device 1 A (Fig. 2B), which method comprises the step of manufacturing photoconversion material containing objects 13 on a substrate 15 (Fig. 2A). The substrate 15 here comprises the second textile sheet 11 and a glue layer 17.

Else, an intermediate carrier with the objects 13, e.g. the glue layer 17, may be attached to the second textile sheet 11 to provide a substrate 15. The second textile sheet 11 and the objects 13 are then attached to the first textile sheet 3 (arrows in Fig. 2B). Here, a lamination process is used wherein the glue layer 17 is deformed and cured, so that a compact laminated textile device is produced with two layers formed by the textile sheets.

Fig. 3 shows an embodiment of a device IB wherein the first and second textile sheets 3, 11 are separated from each other by a spacing layer 17, here a fiber-based padding layer having apertures 19 at the positions of the LEDs 7 so as not to obstruct the light from the LEDs 7 towards the second sheet 11, which here comprises a substantially continuous distribution of photoconversion material. The device IB further comprises a controller 21 and a power source 23 both connected with the LEDs 7. The power source may comprise a battery. The padding layer 17 masks the shapes of the LEDs 7, so that a subject wearing the device IB will not feel their presence. Further, the separation between the LEDs 7 and the second sheet 11 allows for widening of the light cone from the LEDs 7, resulting in a larger illuminated spot on the second sheet 11 so that the device IB provides a relatively large light-emitting surface area on the emitting surface 25. The material of the padding layer 17 may also be highly transparent to the first light to provide an even larger illuminated surface on the second sheet 11. The material of the padding layer 17 may also comprise a further photoconversion material. The device may be formed as a patch for wear close to a body portion to be treated by phototherapy, as in WO 2011/135502 referred to above, and/or be integrated in a piece of clothing. A tight piece of clothing may obviate separate fastening means like a strap or a belt, or hook-and-loop-type textile fasteners such as Velcro©.

In an embodiment (not shown) a spacing layer as shown in Fig. 3 may be absent in significant portions of the device, while other means for maintaining the first and second sheets apart are provided, e.g. spacers and/or frame parts in which the sheets are pulled taut. In particular in devices with such separated and spaced apart first and second sheets, it may be beneficial to provide at least one or more portions of the first and/or second textile sheets that are high reflective for at least one of the first and second wavelengths, so as to direct the light towards an output surface 25 and prevent absorption losses where undesired.

The textile devices 1, 1A, IB may be formed in desired shape beforehand, e.g. the first and/or second textile sheet having a desired shape and possible attachment structures for supporting the finished device in a particular manner, such as a patch, a piece of clothing or a supported light-emitting object that my be a piece of furniture. However, the device may also be a half- fabricate and be further processed to form a desired product.

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 measured 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.

Claims

CLAIMS:

1. A light emitting textile device (1, 1A, IB) comprising a first textile sheet (3) with at least one light source (7) attached to the first textile sheet (3) and configured to emit first light (9) at a first wavelength,

wherein the device comprises a second textile sheet (11) arranged over at least a portion of the first sheet and being configured to be illuminated by the first light,

wherein the second sheet comprises a photoconversion material configured to convert incident first light at the first wavelength to emitted second light at a second wavelength, different from the first wavelength,

wherein the device is configured to illuminate an object with at least a portion of at least the second light.

2. The device (1, 1A, IB) of claim 1, wherein the first textile sheet (3) comprises conductors (5) and the at least one light source (7) is connected to the conductors of the first textile sheet (3).

3. The device (1, 1A, IB) of claim 1, wherein the at least one light source (7) comprises a light emitting diode.

4. The device (1, 1A, IB) of claim 1, wherein the first and second sheets (1, 11) are laminated together.

5. The device (1, 1A, IB) of claim 1, wherein the device is a piece of human body wear.

6. The device (1, 1A, IB) of claim 1, wherein a portion of at least the second sheet (11) is of a material that is permeable to gas and humidity.

7. The device (1, 1A, IB) of claim 1, wherein at least a portion of the device is liquid repellent.

8. The device (1, 1A) of claim 1, wherein the photoconversion material is arranged in and/or on apertures of the second textile sheet.

9. The device (1, 1A, IB) of claim 1, wherein the photo luminescent material comprises a photoconverting agent embedded in a silicone comprising host material.

10. The device (1, 1A, IB) of claim 1, wherein at least a portion of the second sheet (11) comprises fibers or yarns that are at least one of translucent and reflective for at least one of the first and second wavelengths.

11. The device (1, 1A, IB) of claim 1, wherein the at least one light source (7) is configured to emit light in the wavelength range of about 400-600 nm

12. The device (1, 1A, IB) of claim 1, wherein the second wavelength is in the range of about 550-2500 nm.

13. The device (1, 1A, IB) of claim 1, wherein the photo luminescent material comprises a phosphor based on Tellurium-doped Yttrium Aluminium Garnet (YAG:Tm), Copper-CadmiumSulphide (Cu-CdS), Sodium-Barium Sulphate (Na-BaS0₄), and/or phosphors based on quantum dots, Europium (Eu(2)) and/or transition metals.

14. Method of manufacturing a light emitting textile device (1, 1A, IB) comprising the steps of providing a first textile sheet (3) and at least one light source (7) attached to the first textile sheet (3) and configured to emit first light (9) at a first wavelength providing a second textile sheet (11) comprising a photoconversion material configured to convert incident first light at the first wavelength to emitted second light at a second wavelength, different from the first wavelength,

arranging the second sheet over at least a portion of the first sheet so as to be illuminated by the first light and so that the device is configured for illuminating an object with at least a portion of at least the second light.

15. Method of claim 14, wherein the step of providing a second textile sheet (11) comprising a photoconversion material configured to convert incident first light (9) at the first wavelength to emitted second light at a second wavelength, different from the first wavelength, comprises coating one or more fibers and/or yarns with the photoconversion material and forming the second with the coated fibers and/or yarns.