Thermochromic fiber, micro-interactive system comprising such thermochromic fiber and method for manufacturing such thermochromic fiber

Abstract

The invention relates to a thermochromic fiber (1) comprising at least one heating layer (3), at least one thermochromic layer (5), changing its color according to the reached temperature, and at least one sensing layer (7) suitable for detecting a certain physical quantity resulting from the interaction between a user and the thermochromic fiber (1). By virtue of the introduction of said sensing layer (7), the thermochromic fiber (1) makes it possible to obtain a functional interface (13), between a user and the electronics of a machine, which does not require any external sensing devices. Said thermochromic fiber (1) is also flexible and adaptable – as a single fiber, a bundle of fibers, a braiding, or an interactive fabric – to complex, irregular profiles and shapes, allowing using said functional interface (13) in the vehicle cockpit. The invention also relates to a method for manufacturing such functional thermochromic fiber (1).

Description

Thermochromic fiber, micro-interactive system comprising such thermochromic fiber and method for manufacturing such thermochromic fiber

[0001] The present invention relates to a thermochromic fiber.

[0002] In particular, the present invention relates to a thermochromic sensing fiber.

[0003] The present invention further relates to a micro-interactive system comprising such thermochromic fiber.

[0004] By way of non-limiting example, the micro-interactive system of the present invention can find application in the automotive field, especially within the cockpit of a vehicle.

[0005] The present invention also relates to a method for manufacturing such thermochromic fiber.

[0006] As is known, the cockpit of a vehicle is the space within which the driver can monitor and control operation of the vehicle by means of several components, including steering wheel, gear stick, display, indicator panels, (speed, fuel, etc.), controls and switches.

[0007] Therefore, proper cockpit design is crucial to provide the driver with an environment containing all the functionalities they need.

[0008] To enable interaction between driver and vehicle, conventional vehicle cockpits are often equipped with single-function mechanical push-buttons, located in specific areas of the cockpit.

[0009] Therefore, in order to be able to operate such push-buttons, the driver is forced to look away from the road to focus their attention somewhere else, for example, on certain points of the dashboard or central console or door, thereby inevitably increasing the risk of road accidents.

[0010] It should also be considered that the cockpit, being the environment within which the user experiences driving, must be not only functional, but also comfortable.

[0011] For this reason, vehicle cockpits are often enriched with decorative elements, in order to improve the aesthetics of the cockpit, and with lighting systems, which can make the shapes and constituent elements of the cockpit stand out.

[0012] However, conventional decorative elements, being purely aesthetic components, do not allow for a limitation in the number of conventional push-buttons, which, on the other hand, can be unaesthetic.

[0013] Furthermore, conventional lighting systems, typically based on LEDs, may have certain drawbacks in terms of heat management, integration, color accuracy and standards to be met.

[0014] In an attempt to overcome the limitations described above, interface systems between the driver and the vehicle electronics have recently been introduced at functional areas of the cockpit, which interface systems have a more attractive appearance than traditional push-buttons and can also function as interior lighting systems in the cockpit.

[0015] Said interface systems, referred to as 'micro-interactive systems' are based on a simple, intuitive operation principle and can be used by the driver without unduly reducing their attention to the road.

[0016] Particularly, each micro-interactive system is controlled by an electronic control unit and comprises at least one sensing device.

[0017] Said sensing device is suitable for sensing a stimulus, i.e., a command given by the driver or any other user.

[0018] This stimulus usually takes the form of a force or pressure applied by the user onto the sensing device.

[0019] On the basis of such command, said sensing device sends a signal to said electronic control unit, which, in response to this signal, not only activates the function with which the micro-interactive system is associated, such as, for example, the controlling of the heating inside the cockpit, but it also controls generation of a noticeable feedback, thereby informing the user that the function has been or is being performed.

[0020] In particular, said micro-interactive systems, in response to the given command, can change their appearance by changing their color so as to provide visual feedback.

[0021] This color change, usually reversible, is often based on the introduction, into the micro-interactive system, of thermochromic materials, i.e., materials that are capable of changing their color according to the temperature to which said materials are exposed.

[0022] In addition or as an alternative to the color change, the visual feedback could be given as a luminescence change.

[0023] This luminescence change, usually reversible, is often based on the introduction, into the micro-interactive system, of luminescent materials, i.e., materials that are capable of changing their luminescence according to the stimuli such as light to which said materials are exposed.

[0024] However, presently known and currently used micro-interactive systems are not free from limitations.

[0025] For example, document WO 2021 / 236805 describes a micro-interactive system that can be used inside a vehicle and is made by associating the sensing device with an interactive fabric. Said interactive fabric comprises thermochromic fibers, i.e., fibers consisting of a central heating core surrounded by a thermochromic coating layer.

[0026] Said central heating core comprises a conductive material with a certain electric resistance, whereas said thermochromic layer comprises a thermochromic material.

[0027] When the user acts onto the sensing device, the micro-interactive system responds by giving a command for an electric current to flow through the conductive material. In this way, the electric resistance of said material causes heating of the central heating core, this also causing an increase in the temperature of the thermochromic layer.

[0028] When the temperature of said thermochromic layer reaches a threshold temperature, the thermochromic material becomes activated and changes its color.

[0029] Although the introduction of such micro-active system makes it possible to improve driving comfort, it provides for the sensing device to be still configured as a push-button located in a specific area of the cockpit. Therefore, the user is still forced to divert their attention from driving to be able to locate and actuate the push-button.

[0030] Document WO 2022 / 228330, instead, describes a micro-interactive system made in the form of an interactive fabric inside which pressure-sensitive sensing fibers are woven on a first layer and thermochromic fibers are woven on a second layer.

[0031] Such micro-interactive system, having pressure-sensitive fibers distributed inside an interactive fabric, makes it possible to obtain a sensing region onto which the user can act, said sensing region being larger than the one of a push-button.

[0032] Said pressure-sensitive fibers, however, being interwoven among other fibers, do not allow uniform sensing of pressure and therefore do not allow uniform interaction between the user and the system over the entire surface of the interactive fabric.

[0033] In addition, the need to provide a multi-layer fabric to allow introduction of fibers with different characteristics into different layers of fabric, results in a bulky interactive fabric difficult to be adapted to complex, irregular surfaces such as those present in a vehicle cockpit.

[0034] Consequently, the fabric of the micro-interactive system described in said document can hardly be employed inside a vehicle.

[0035] Document US 2020 / 240041 describes an interactive system provided with a fiber comprising an electrically conductive core, a thermochromic layer and discrete pressure sensors embedded in said fiber.

[0036] In this case, similarly to the document WO 2022 / 228330, the use of discrete sensors does not allow uniform sensing of pressure and therefore does not allow uniform interaction between the user and the system over the entire surface of the fiber.

[0037] Finally, document US 2022 / 145498 discloses a fiber comprising an electrically conductive core and a functional or aesthetic outer layer. However, said fiber does not comprise a sensitive element onto which the user can act.

[0038] The main object of the present invention is thus to overcome the limitations described above by providing a thermochromic fiber that makes it possible to obtain a micro-interactive system having a large, uniform sensing region with which the user can interact.

[0039] Another object of the present invention is to provide a thermochromic fiber having small overall dimensions and allowing obtaining a micro-interactive system that can also be easily adapted to complex, irregular surfaces, so as to be usable inside a vehicle cockpit.

[0040] Therefore, an object of the present invention is also to provide a micro-interactive system that has such thermochromic fiber, is capable of being used inside a vehicle cockpit and allows the driver to control operation of the vehicle while limiting the inattention factor to which the driver is exposed.

[0041] These and other objects are achieved by the thermochromic fiber and the micro-interactive system as claimed in the appended claims.

[0042] The thermochromic fiber according to the invention is a multi-layer element comprising, in a manner known per se, at least one heating layer and at least one thermochromic layer.

[0043] It shall be noted that in the present disclosure the term ‘thermochromic fiber’ is intended to include thermochromic hollow fiber, thermochromic bicomponent fiber, optical fiber, thermochromic flexible tube and similar flexible substrates with different diameters.

[0044] Preferably, said thermochromic layer acts as an outer coating of said thermochromic fiber.

[0045] According to the invention, the thermochromic fiber further comprises at least one sensing layer, i.e., a layer made of a material sensitive to a certain physical quantity resulting from the interaction with the thermochromic fiber itself.

[0046] Said at least one sensing layer is continuous along the thermochromic fiber.

[0047] Said at least one sensing layer is a layer (or surface) that incorporates sensing capabilities, embeddable into a system and able to interact with one or more materials or elements of said system.

[0048] Said sensing layer comprises sensing materials, coatings and / or embedded sensors, forming multiple sensing points or zones.

[0049] Therefore, said sensing layer is basically a distributed or area-based sensing, able to detect and measure stimuli substantially over the entire area of said layer.

[0050] According to a preferred embodiment of the invention, said sensing layer comprises sensing materials and / or coatings uniformly distributed over the area of said layer so that it extends substantially over the entire surface of the fiber.

[0051] According to another preferred embodiment of the invention said sensing layer comprises sensing materials and / or coatings distributed over the area of said layer according to a desired pattern.

[0052] In both the aforesaid embodiments, provision of a sensing layer continuously extending along the thermochromic fiber distinguishes the present invention from the prior solutions implementing layers provided with discrete sensors, in which uniform stimulus detection cannot be achieved.

[0053] Preferably, said at least one sensing layer comprises a material sensitive to a stimulus such as a pressure and / or a force and / or a tension resulting from a user touching said thermochromic fiber.

[0054] Even more preferably, said sensing layer comprises a flexible conductive material based on a piezoresistive sensing mechanism sensitive to the pressure applied by the user on the surface of said thermochromic fiber.

[0055] The piezoresistive sensing mechanism relies on the change in electrical resistance of a material when mechanical stress or strain is applied. When stress or strain is applied, the material’s geometry (length, cross-sectional area) or intrinsic properties (carrier mobility, band structure) change, altering its resistance. The change in resistance is proportional to the applied stimuli such as force or pressure.

[0056] The piezoresistive sensing mechanism requires an external power source to measure resistance changes via voltage or current changes in a circuit.

[0057] According to a possible embodiment of the invention, said at least one sensing layer is sandwiched between said at least one heating layer and said at least one thermochromic layer.

[0058] Preferably, said at least one heating layer forms the central core of said thermochromic fiber, and said at least one sensing layer surrounds said central core so that said core is received inside said at least one sensing layer.

[0059] Finally, said at least one sensing layer in turn is surrounded by said at least one thermochromic layer so that said at least one sensing layer is incorporated in said at least one thermochromic layer.

[0060] According to a second embodiment of the invention, said at least one heating layer is sandwiched between said at least one sensing layer and said at least one thermochromic layer.

[0061] It is evident that, in alternative embodiments of the invention, said at least one heating layer, said at least one sensing layer and said at least one thermochromic layer of the thermochromic fiber could be arranged in any order.

[0062] Irrespective of the embodiment, hollow fiber or tube that comprises at least a heating element can be used as heating layer. Preferably, said hollow fiber or tube is flexible.

[0063] Preferably, said heating element is inserted into the hollow fiber or tube or incorporated in the wall thereof.

[0064] The heating element can be any kind of heating element including metal wires, metal alloy wires, copper wires, carbon-based materials, polymer composites, thermally conductive polymer composites with various diameters ranging from 0.1 mm to couple of mms.

[0065] Irrespective of the embodiment, the thermochromic layer may further comprise at least one luminescent material sensitive to environmental stimulus.

[0066] Irrespective of the embodiment, the thermochromic fiber according to the invention may further comprise at least one background layer, arranged between said at least one thermochromic layer and the central core of said thermochromic fiber, preferably adjacently to the thermochromic layer.

[0067] Said at least one background layer may be white or have any color or pattern and its function is to provide an aesthetical layer visible as a result of a change in color of the thermochromic layer.

[0068] Furthermore, said at least one thermochromic layer may in turn be surrounded by at least one transparent or translucent layer.

[0069] Furthermore, the thermochromic fiber according to the invention may further comprise a luminescent material, for example a material sensitive to light.

[0070] Said luminescent material may constitute a layer or the central core of the thermochromic fiber and / or may be incorporated into one or more layers of said thermochromic fiber.

[0071] Preferably, said luminescent material is embedded in the background layer.

[0072] Preferably, said luminescent material is embedded in the transparent or translucent layer that surrounds the thermochromic layer.

[0073] According to a specific embodiment, said luminescent material - for example made in the form of optical fibers - is used as the central core of the thermochromic fiber and is surrounded by the sensing layer. The sensing layer covers the entire surface of the luminescent material or is masked to create specific patterns.

[0074] Preferably, said sensing layer is surrounded by the background layer.

[0075] Even more preferably, the luminescent material comprises LED (Light emitting diode) or other light sources combined with said optical fibers.

[0076] The thermochromic fiber according to the invention can be connected to the electronic control unit of a micro-interactive system.

[0077] This is made possible by the fact that, advantageously, the sensing layer can be integrated into a complex system and combined with various functionalized materials or elements as described below.

[0078] As said thermochromic fiber comprises at least one sensing layer, said fiber integrates in itself not only the functions of heating and related color changing, but also the sensing function performed by known sensing devices present in micro-interactive systems. Accordingly, the thermochromic fiber according to the present invention makes it possible to obtain a micro-interactive system that does not require any additional sensing devices and therefore has a much more compact structure than known micro-interactive systems.

[0079] Therefore, the present invention also relates to a micro-interactive system provided with such thermochromic fiber, wherein the at least one heating layer and the at least one sensing layer of said fiber are electrically connected to said electronic control unit.

[0080] When the user interacts with said micro-interactive system, i.e., when the user acts onto said thermochromic fiber, the sensing layer detects said interaction and sends a signal to the electronic control unit.

[0081] More specifically, when said sensing layer comprises the flexible conductive material based on the piezoresistive sensing mechanism, the user can interact with said micro-interactive system by applying a slight pressure onto said thermochromic fiber. Said pressure causes a change in the resistance of the flexible conductive material, thereby generating a signal that is detected by the electronic control unit.

[0082] Once this signal has been received, the electronic control unit activates the heating layer (by controlling flow of an electric current in said layer), thus increasing the temperature of the thermochromic fiber and bringing about the color change in the thermochromic layer.

[0083] According to an alternative embodiment of the present invention, the micro-interactive system might also comprise two or more of said thermochromic fibers, so as to create a colored pattern when the thermochromic material is activated.

[0084] In this case, the micro-interactive system would comprise bundles of thermochromic fibers, for example, twisted, forming a cord, or arranged in parallel close to one another or interwoven or braided with one another, forming interactive textile structures, cords, braidings, threads, yarns, fabrics.

[0085] In addition, each of said thermochromic fibers can be made with thermochromic layers with different colors and / or activatable at different threshold temperatures so as to create colored patterns.

[0086] Advantageously, the heating layer, the sensing layer and the thermochromic layer of each thermochromic fiber are made of flexible materials.

[0087] Therefore, each of said thermochromic fibers can be bent, twisted and applied to curved surfaces, thereby making said micro-interactive system adaptable to complex, irregular profiles and shapes.

[0088] In particular, the flexibility of said thermochromic fibers makes it possible to use the micro-interactive system according to the invention in a vehicle cockpit, to allow interaction between a user – especially the driver – and the electronics of the cockpit.

[0089] By way of non-limiting examples, said thermochromic fibers, in the form of single fibers or bundles of fibers, can easily be positioned along the profile of vehicle doors, of the central console, of the steering wheel or of an armrest control; in the form of an interactive fabric / textile, they can be used over or in place of the coating material of the cockpit.

[0090] In addition, as the heating layer, the sensing layer and the thermochromic layer of each thermochromic fiber are continuous along the fiber, the corresponding functions of heating, sensing and color changing can be performed homogeneously over the entire surface of said fiber.

[0091] In particular, the sensing layer is capable of detecting the command given by the user regardless of the point of the thermochromic fiber on which said command is being carried out. Therefore, the user can act indiscriminately on any point of the thermochromic fiber, of the bundle of fibers or of the interactive fabric to activate the function with which the micro-interactive system is associated.

[0092] In this regard, the use of a sensing layer made of flexible materials that can detect and measure stimuli over a distributed area allows it to be applied to various substrates and to cover a larger area.

[0093] This is particularly advantageous when such micro-interactive system is used in the cockpit of a vehicle.

[0094] The provision of said one or more thermochromic fibers, indeed, makes it possible to create, inside the cockpit, sensing regions and wide-area monitoring, i.e., regions that are sensitive to the command given by the user and are homogeneous and particularly long, in the case of a single fiber or bundle of fibers, or particularly large, in the case of an interactive fabric (such as touch screens, touch surfaces and so on).

[0095] This allows the user – especially the driver – to activate one or more functions of the vehicle without having to focus their attention on a specific point in the cockpit, thereby reducing the inattention factor involved in such action during driving.

[0096] In addition, the provision of a homogeneous sensing region reduces the risk that the electronic control unit of the micro-interactive system may misinterpret a command given by the user.

[0097] Furthermore, the provision of a homogeneous sensing region makes it possible to detect different commands, such as, for example, single touch, double touch, finger sliding, etc.

[0098] Therefore, by means of a single micro-interactive system of the present invention, it is possible to manage different functions, each associated with a specific command, and to correspondingly provide different visible feedbacks.

[0099] Moreover, said thermochromic fibers may incorporate and / or be associated with lighting systems so that the micro-interactive system can provide visual feedback not only by means of a color change, but also by means of a luminosity change.

[0100] For example, if the thermochromic fiber comprises luminescent materials (for example the central core of the thermochromic fiber is made in the form of optical fiber), when said thermochromic fiber is touched, the touch is detected by the sensing layer and the optical fiber is illuminated by a lighting system that is controlled by the electronic control unit.

[0101] Therefore, the micro-interactive system of the present invention, by integrating the functions of sensing, color changing and luminosity management, can be used to create environments having clean, elegant lines and being optically spacious and comfortable.

[0102] Accordingly, the micro-interactive system according to the invention, when used within a vehicle, makes it possible not only to improve the interaction between the user and the vehicle electronics, making it simpler, more intuitive and efficient, but also to fulfil the aesthetic requirements within the cockpit, improving the overall driving experience.

[0103] The present invention also relates to a method for manufacturing the thermochromic fiber according to the present invention.

[0104] Said method is a solution-based process that comprises the following steps:

[0105] - providing a heating element, forming a heating layer;

[0106] - preparing a first solution and dispersing sensing materials, coatings and / or sensors in said first solution to make a sensing solution;

[0107] - preparing a second solution and dispersing thermochromic materials in said second solution to make a thermochromic solution;

[0108] - arranging one over the other, successively and in any order, said heating layer, a sensing layer obtained by applying said sensing solution and a thermochromic layer obtained by applying said thermochromic solution so as to obtain a multilayered fiber.

[0109] Preferably, the method further includes the step of preparing a third solution and dispersing a background pigment in said third solution to make a background solution.

[0110] In this case, said heating layer, said sensing layer, said thermochromic layer and a background layer obtained by applying said background solution are applied one over the other, successively and in any order, so as to obtain the multilayered fiber.

[0111] Preferably, said first, said second and / or said third solution (if provided) is / are polymer-based solution(s).

[0112] Preferably, said heating element is incorporated into a hollow fiber or tube.

[0113] The heating element can be any type of heating material such as metal wires, metal alloy wires, carbon fibers, carbon-based wires, bicomponent fibers with a heating element, polymer composite filaments, and combinations of these with various diameters ranging from 0.1 mm to couple of mms.

[0114] The sensing solution is uniformly applied or a masking layer is used to create specific patterns.

[0115] In the case of masking, the method according to the present invention comprises the further steps:

[0116] - applying a masking layer, said masking layer having different patterns such as lines, circles, squares, flowers, etc;

[0117] - coating the sensing solution on the masking layer;

[0118] - removing the masking layer in order to obtain different patterns.

[0119] According to a first embodiment of the invention, said method is a solution-based process that comprises the following steps:

[0120] - providing a heating element as central core, said heating element being preferably flexible;

[0121] - preparing a first solution and dispersing sensing materials, coatings and / or sensors in said first solution to make a sensing solution;

[0122] - preparing a second solution and dispersing thermochromic materials in said second solution to make a thermochromic solution

[0123] - coating the sensing solution on the central core, thus obtaining the sensing layer;

[0124] - coating the thermochromic solution on the sensing layer, thus obtaining the thermochromic layer.

[0125] According to a second embodiment of the invention, said method is a solution-based process that comprises the following steps:

[0126] - providing a heating element as central core, said heating element being preferably flexible;

[0127] - preparing a first solution and dispersing sensing materials, coatings and / or sensors in said first solution to make a sensing solution;

[0128] - preparing a second solution and dispersing thermochromic materials in said second solution to make a thermochromic solution;

[0129] - preparing a third solution and dispersing a background layer pigment in said third solution to make background solution;

[0130] - coating the sensing solution on said central core, thus obtaining a sensing layer;

[0131] - coating the background solution on the sensing layer, thus obtaining a background layer;

[0132] - coating the thermochromic solution on the background layer, thus obtaining a thermochromic layer.

[0133] In both embodiments, the heating element can be directly used as central core or can be incorporated into a flexible tube or hollow fiber forming a central core.

[0134] Preferably, after one of said sensing, background and thermochromic solutions is applied, said solution is left to dry or dried before being coated by the next solution.

[0135] Preferably, between the application of said solutions one over the other, the method according to the present invention comprises the following steps:

[0136] - preparing a fourth solution with or without additives in said fourth solution to make a shielding solution;

[0137] - coating the shielding solution on the thermochromic fiber as outermost layer, thus obtaining a shielding layer.

[0138] Preferably, after the application of the thermochromic solution, the method according to the present invention comprises the following steps:

[0139] - preparing a transparent or translucent solution;

[0140] - coating the transparent or translucent solution on the last applied layer, obtaining a transparent or translucent layer.

[0141] Even more preferably, said fourth and / or said transparent or translucent solution is / are polymer-based solution(s).

[0142] Preferably, the method according to the present invention may further comprise the introduction of a luminescent material, used as or central core of the thermochromic fiber or incorporated therein, applied between the solutions previously mentioned and / or incorporated into the solutions previously mentioned.

[0143] Further features and advantages of the present invention will become more evident from the ensuing detailed description of some preferred embodiments of the invention, given as a non-limiting examples with reference to the annexed drawings, in which:Fig.1

[0144] shows the thermochromic fiber according to the invention in a first embodiment;Fig.2

[0145] shows the thermochromic fiber according to the invention in a second embodiment;Fig.3

[0146] is a schematic diagram of the micro-interactive system comprising the thermochromic fiber according to the invention;Fig.4

[0147] is a schematic diagram of the electronic control unit of the micro-interactive system of;Fig.5a

[0148] shows a first possible configuration of a bundle of thermochromic fibers according to the invention;Fig.5b

[0149] shows a second possible configuration of a bundle of thermochromic fibers according to the invention;Fig.5c

[0150] shows a possible configuration of a bundle of thermochromic fibers according to the invention and luminescent fibers.

[0151] illustrates a first embodiment of the thermochromic fiber according to the present invention.

[0152] The thermochromic fiber 1 shown incomprises a heating layer 3, forming the central core of said thermochromic fiber 1, and a thermochromic layer 5, which acts as an outer coating of said thermochromic fiber 1.

[0153] As is known, said thermochromic layer 5 comprises one or more thermochromic materials capable of changing their color according to the temperature of said layer.

[0154] Said one or more thermochromic materials can be selected from organic thermochromic materials, inorganic thermochromic materials, inorganic liquid crystals, hydrogel-based thermochromic materials, conjugated polymer-based thermochromic materials, or a combination of at least two of these materials.

[0155] Said one or more thermochromic materials are inserted in a flexible matrix, preferably an elastomer, a thermoplastic elastomer and / or a silicone.

[0156] Said heating layer 3 comprises a heating element, in the form of conductive thread, wire or yarn made by a conductive material having a certain electrical resistance.

[0157] Said conductive material can be selected from a metal (such as copper or silver), a metal alloy, a conductive inorganic material, a polymer-based material, a carbon-based material, a composite material, a hybrid material, or a combination of at least two of these materials.

[0158] When said conductive material is passed through by an electric current, the electric resistance of said material causes heating of the heating layer 3, this also causing a temperature increase in the thermochromic layer 5.

[0159] When the temperature of said thermochromic layer 5 reaches a certain threshold temperature, the thermochromic material becomes activated, changing its color.

[0160] The thermochromic fiber 1 according to the invention further comprises a sensing layer 7, i.e., a layer made of a material sensitive to a certain physical quantity resulting from the interaction with the thermochromic fiber itself.

[0161] Said sensing layer 7 comprises a flexible conductive material based on a piezoresistive sensing mechanism sensitive to the pressure applied by a user on the surface of said thermochromic fiber 1, thus forming a touch sensor.

[0162] Said flexible conductive material consists of a base material and a conductive filling material.

[0163] Said base material can be selected from: polymer materials, mixtures or compounds, composites, inorganic materials, metals, hybrid materials, or a combination of at least two of these materials.

[0164] Said conductive filling material can be formed by any conductive filler, such as carbon black, graphite, graphene, reduced graphene oxide, carbon fiber, carbon nanofiber, carbon nanotubes, MXene, silver nanoparticles, or derivatives, mixtures or hybrids of such conductive fillers.

[0165] Alternatively, said sensing layer 7 might comprise a material sensitive to another physical quantity, such as a force, a tension, a deformation, a compression, a flexion, a sliding, a torsion, a stretch or a blow resulting from the interaction between the user and the thermochromic fiber 1.

[0166] According to the embodiment shown in, said sensing layer 7 is sandwiched between said heating layer 3 and said thermochromic layer 5.

[0167] Therefore, the central core of said thermochromic fiber 1, formed by the heating layer 3, is surrounded by the sensing layer 7 so that said central core is incorporated in said sensing layer 7.

[0168] In addition, said one sensing layer 7 in turn is surrounded by said thermochromic layer 5 so that said sensing layer 7 is incorporated in said thermochromic layer 5.

[0169] Alternatively, said thermochromic fiber 1 might have the heating layer 3 sandwiched between the sensing layer 7 and the thermochromic layer 5.In particular, said thermochromic layer 1 might comprise a central core formed by the sensing layer 7, a heating layer 3 surrounding said sensing layer 7, and a thermochromic layer 5 surrounding said heating layer 3.

[0170] It is worth mentioning that, in alternative embodiments of the invention, said heating layer 3, said sensing layer 7 and said thermochromic layer 5 could be arranged in any order.

[0171] shows a second embodiment of the thermochromic fiber according to the present invention.

[0172] In this embodiment, the thermochromic fiber 1 further comprises a background layer 9, arranged between the thermochromic layer 5 and the central core of thermochromic fiber 1, preferably adjacently to the thermochromic layer 5.

[0173] Said background layer 9 may be white or have any color or pattern and its function is to provide an aesthetical layer visible as a result of a change in color of the thermochromic layer 5.

[0174] Said background layer 9 consists of a flexible material, such as, for example, an elastomer, a thermoplastic elastomer and / or a silicone, blends, mixtures or compounds, or a combination or at least two of these materials.

[0175] Obviously, the thermochromic fiber according to the present invention might also have multiple heating layers, thermochromic layers, sensing layers and background layers.

[0176] Regardless of the embodiment, the thermochromic fiber 1 according to the invention may be connected to the electronic control unit 11 of a micro-interactive system 13, whose operation is schematically shown in Figures 3 and 4.

[0177] In particular, in the embodiment described and illustrated in Figures 3 and 4, reference will be made to a micro-interactive system 13 used in a vehicle cockpit to allow interaction between a user – especially the driver – and the electronics of the vehicle.

[0178] However, the micro-interactive system according to the present invention could also be used to allow interaction between a user and the electronics provided in one or more devices of any machine.

[0179] As indicated in, to activate said micro-interactive system 13, the user touches the thermochromic fiber 1, applying a slight pressure onto it.

[0180] The sensing layer 7 recognizes this touch because the pressure exerted by the user causes a change in the resistance of the conductive material present in said layer and generates a signal that is detected by the electronic control unit 11.

[0181] Said electronic control unit 11 is an electronic structure that manages operation of the whole micro-interactive system 13, interprets and processes the signal received from the sensing layer 7 and, based on such signal:

[0182] - activates the functions of the one or more external devices 12 connected to the micro-interactive system 13, such as, for example, the heating system, the stereo system or the window lifters; and

[0183] - controls the flow of electric current in said heating layer 3 so as to increase the temperature of the thermochromic fiber 1 and activate the color change of the thermochromic layer 5, so as to generate a visual feedback that is immediately recognizable by the user to inform them that said functions have been or are being performed.

[0184] Therefore, the thermochromic fiber 1 according to the invention, being provided with the sensing layer 7, integrates within itself not only the functions of heating and related color changing, already present in known thermochromic fibers, but also the function of detecting the pressure applied by the user.

[0185] Accordingly, the thermochromic fiber 1 according to the present invention allows making a micro-interactive system 13 that does not require any devices external to the fiber.

[0186] The micro-interactive system 13 according to the invention therefore has a much more compact structure than known micro-interactive systems.

[0187] The electronic control unit 11 of the micro-interactive system 13 of the present invention could also control two or more of said thermochromic fibers 1.

[0188] In this case, the micro-interactive system would comprise bundles of thermochromic fibers, said thermochromic fibers 1 being, for example, arranged in parallel close to one another (see), or twisted, forming a cord (see), or braided, or interwoven with one another, forming interactive fabrics.

[0189] In addition, each of said thermochromic fibers could be made with thermochromic layers of different colors and / or activatable at different temperatures so as to create colored patterns.

[0190] According to an embodiment of the invention, luminescent fibers, filaments, optical fibers or ribbons can be associated with the thermochromic fiber(s).

[0191] For instance, one or more thermochromic fibers 1 can be twisted with one or more luminescent fibers 25, as shown in.

[0192] It will be evident to the person skilled in the art that the thermochromic fiber(s) and the luminescent fiber(s) could also be arranged in other way, such as for instance arranged in parallel close to one another or interwoven with one another, and so on.

[0193] According to this embodiment, it is possible to envisage that the micro-interactive system 13 has a day mood and a night mood, and in the night mood, luminescent fibers, filaments, optical fibers or ribbons are activated.

[0194] In alternative (or in addition), the thermochromic fiber(s) can comprise a luminescent material that constitutes a layer or the central core of the thermochromic fiber itself and / or may be incorporated into one or more of the layers already mentioned.

[0195] According to a specific embodiment, said luminescent material - for example made in the form of optical fibers - is used as the central core of the thermochromic fiber and is surrounded by the sensing layer.

[0196] Preferably, said sensing layer is surrounded by the background layer.

[0197] Even more preferably, the luminescent material comprises LED (Light emitting diode) or other light sources combined with said optical fibers.

[0198] When said thermochromic fiber is touched, the touch is detected by the sensing layer and the optical fiber is illuminated by a lighting system that is controlled by the electronic control unit. Irrespective of the embodiment, each of said thermochromic fibers 1 could be advantageously bent, twisted and applied to curved surfaces, because the heating layer 3, the sensing layer 7 and the thermochromic layer 5 are made of flexible materials.

[0199] Therefore, said thermochromic fibers 1 make the micro-interactive system 13 of the present invention adaptable to complex, irregular profiles and shapes.

[0200] In particular, said thermochromic fibers 1 can be reduced to a diameter preferably smaller than 10 mm, even more preferably smaller than 5 mm, so as to further increase the flexibility of the fiber.

[0201] In particular, said thermochromic fibers, in the form of single fibers or bundle of fibers, can easily be positioned along the profile of vehicle doors, of the central console or of the steering wheel and, in the form of an interactive fabric, they can be used over or in place of the coating material of the cockpit.

[0202] In addition, as the heating layer 3, the sensing layer 7 and the thermochromic layer 5 are continuous along each thermochromic fiber 1, the corresponding functions of heating, sensing and color changing can be performed homogeneously over the entire surface of said fiber.

[0203] In particular, the sensing layer 3 is capable of detecting the pressure applied by the user irrespective of the point of the thermochromic fiber 1 to which the user applies such pressure.

[0204] Therefore, the user, to activate the function of the external device associated with the micro-interactive system 13, can act indiscriminately on any point of the single thermochromic fiber 1, or on any point of the bundle of fibers or of the interactive fabric.

[0205] Accordingly, said thermochromic fibers make it possible to create, inside the cockpit, sensing regions, i.e., regions that are sensitive to the user’s touch, which regions are homogeneous and particularly long, in the case of a single fiber or bundle of fibers, or particularly large, in the case of an interactive fabric.

[0206] In particular, when said thermochromic fibers are configured as an interactive fabric, said fabric can constitute a micro-interactive tactile coating material that can be arranged in different areas of the cockpit.

[0207] This allows the user – especially the driver – to activate one or more vehicle functions without having the focus their attention on a specific point of the cockpit, thereby reducing the inattention factor involved in such action during driving.

[0208] In addition, the provision of a homogeneous sensing region reduces the risk that the electronic control unit 11 may misinterpret a command generated by the user’s action.

[0209] Furthermore, the provision of a homogeneous sensing region makes it possible to detect different commands, such as, for example, single touch, double touch, finger sliding, etc.

[0210] Therefore, the user, acting by moving their fingers on a single micro-interactive system 13 can manage different functions, each associated with a specific command, thereby allowing the user to control one or more vehicle functions, including those related to different external devices.

[0211] In more detail, as shown in the operation diagram of, the electronic control unit 11 comprises a processor 15, which controls the operation of the micro-interactive system 13 according to the command given by the user and according to predetermined scenarios defined during programming.

[0212] Said processor 15 interprets the signals from the sensing layer 7 and accordingly decides the level of temperature of the heating layer 3, as well as the activation state of the external devices 12 connected to the micro-interactive system 13.

[0213] Preferably, said process 15 supports the CANBus (Controller Area Network Bus) protocol or any other communication protocol capable of communicating with a vehicle.

[0214] The electronic control unit 11 further has a temperature control module 17, connected to the heating layer 3 of one or more of the thermochromic fibers 1 by means of an electric connection 17a.

[0215] Said temperature control module 17 has the function of adjusting the temperature of one or more of the thermochromic fibers 1 to which it is connected, allowing the heating layer 3 to reach different temperature levels according to the instructions given by the processor 15, modifying the color of said thermochromic fibers 1 accordingly.

[0216] The electronic control unit 11 further comprises a sensing module 19, connected to the sensing layer 7 of one or more of the thermochromic fibers 1 by means of an electric connection 19a.

[0217] Said sensing module 19 has the purpose of detecting the signal generated by the sensing layer 7 when the user touches the thermochromic fiber 1, of converting said signal into a format legible by the processor 15, and of transmitting it to said processor.

[0218] The electric connection of the temperature control module 17a and the electric connection of the sensing module 19a can be made by means of electrical connectors, electrical wires, conductive adhesives, conductive polymers, conductive polymer composites, conductive composites, a flexible printed circuit board or the like.

[0219] The electronic control unit 11 further has a power control module 21, connected to an outer power source, said module converting the electric signals necessary for the operation of the electronic control unit 11 to the levels necessary for the operation of the processor 15 and the modules 17 and 19, controlling the power consumption of the micro-interactive system 13.

[0220] Finally, the electronic control unit 11 comprises one or more output modules 23.

[0221] Said one or more output modules 23 are electronic structures to which said one or more external devices 12 associated with the micro-interactive system 13 are connected; the electronic components necessary for activating said one or more external devices 12 and providing them with the required power are housed within said one or more output modules 23.

[0222] According to a preferred embodiment of the present invention, said electronic control unit 11 is made as a printed circuit board having one or more layers so as to obtain a small-sized electronic control unit 11.

[0223] In particular, it is possible to use a flexible printed circuit board to allow positioning the electronic control unit 11 inside the vehicle.

[0224] In addition, the thermochromic fibers 1 according to the invention may incorporate and / or be associated with internal lighting systems of the cockpit.

[0225] In particular, the thermochromic fibers 1 may integrate within themselves, within either existing layers or dedicated layers, luminescent materials in organic, inorganic or hybrid structures, or in a combination of said structures.

[0226] In this way, the micro-interactive system 13 can provide visual feedback not only by means of a color change, but also by means of a luminosity change.

[0227] Therefore, the micro-interactive system 13 of the present invention, by integrating the functions of sensing, color changing and luminosity management, can be used for manufacturing cockpits having clean, elegant lines and being optically spacious and comfortable.

[0228] Accordingly, the micro-interactive system 13 according to the invention not only makes it possible to improve the interaction between the user and the electronics of the vehicle by making it simpler, intuitive and efficient, but also to meet the aesthetic requirements within the cockpit, thereby improving the overall driving experience.

[0229] It will be evident to the person skilled in the art that the embodiments described above in detail are in no way to be understood in a limiting sense, and that numerous variations and modifications are possible without departing from the scope of the invention as defined in the appended claims.

[0230] In particular, the thermochromic fiber according to the invention could incorporate within itself further chromatic materials such as photochromic, electrochromic, piezoceramic, electrophoretic materials, solvated chromic materials or electronic inks.

[0231] The present invention also relates to a method for manufacturing the thermochromic fiber.

[0232] According to a preferred embodiment of the invention, said method comprises the following steps:

[0233] - providing a heating element forming a central core, said heating element being flexible;

[0234] - preparing a first polymer-based solution and dispersing sensing materials, coatings and / or sensors in the first polymer-based solution to make a sensing solution;

[0235] - coating the sensing layer material on the central core, obtaining a sensing layer;

[0236] - drying the sensing layer;

[0237] - preparing a second polymer-based solution and dispersing thermochromic materials in said second polymer-based solution to make a thermochromic solution;

[0238] - preparing a third polymer-based solution and dispersing pigment materials in said third polymer-based solution to make a background solution;

[0239] - coating the background solution on the sensing layer, thus obtaining a background layer;

[0240] - coating the thermochromic solution on the background layer, thus obtaining the thermochromic layer.

[0241] It will be evident that the method according to the present invention can only include the preparation steps and the application steps of said heating layer and of said sensing and thermochromic solutions and that the heating layer and all the solutions previously mentioned can be applied in any order.

[0242] It will be also evident that the method for manufacturing the thermochromic fiber according to the present invention can use physical coating processes such as dip coating, spray coating, curtain coating, roller coating or brushing or any coating process known to the person skilled in the art or a combination of at least two of said processes.

Claims

A thermochromic fiber (1) comprising:- at least one heating layer (3) comprising a conductive material with a certain electric resistance; and- at least one thermochromic layer (5) suitable for forming an outer coating of said thermochromic fiber (1) and comprising a thermochromic material that changes its color when the temperature to which said thermochromic layer (5) is exposed exceeds a threshold temperature;characterized in that it comprises at least one sensing layer (7) suitable for detecting a physical quantity resulting from the interaction, in use, between a user and the thermochromic fiber (1), said at least one sensing layer (7) extending continuously along said thermochromic fiber.The thermochromic fiber (1) according to claim 1, wherein said at least one sensing layer (7) comprises sensing materials and / or coatings uniformly distributed over the area of said sensing layer.The thermochromic fiber (1) according to claim 1 or 2, wherein said at least one sensing layer (7) is sandwiched between said at least one heating layer (3) and said at least one thermochromic layer (5).The thermochromic fiber (1) according to claim 3, wherein said at least one heating layer (3) forms the central core of said thermochromic fiber (1), wherein said at least one sensing layer (7) surrounds said central core so that said central core is incorporated in said at least one sensing layer (7), and wherein said at least one sensing layer (7) in turn is surrounded by said at least one thermochromic layer (5) so that said at least one sensing layer (7) is incorporated in said at least one thermochromic layer (5).The thermochromic fiber (1) according to claim 1 or 2, wherein said at least one heating layer (3) is sandwiched between said at least one sensing layer (7) and said at least one thermochromic layer (5).The thermochromic fiber (1) according to claim 5, wherein said at least one sensing layer (7) forms the central core of said thermochromic layer (1), wherein said at least one heating layer (3) surrounds said central core so that said central core is incorporated in said at least one heating layer (3), and wherein said at least one heating layer (3) in turn is surrounded by said at least one thermochromic layer (5) so that said at least one heating layer (3) is incorporated in said at least one thermochromic layer (5).The thermochromic fiber (1) according to any one of the preceding claims, wherein said at least one sensing layer (7) comprises a material sensitive to the pressure applied, in use, by a user onto said thermochromic fiber (1).The thermochromic fiber (1) according to claim 7, wherein said at least one sensing layer (7) comprises a flexible conductive material based on a piezoresistive sensing mechanism.The thermochromic fiber (1) according to any one of the preceding claims, wherein said thermochromic fiber (1) comprises at least one background layer (9), arranged between said at least one thermochromic layer (5) and the central core of said thermochromic fiber (1).The thermochromic fiber (1) according to claim 9, wherein said background layer (9) comprises a luminescent material sensitive a predetermined stimulus.The thermochromic fiber (1) according to any one of the preceding claims, wherein said at least one thermochromic layer (5) comprises a luminescent material sensitive a predetermined stimulus.The thermochromic fiber (1) according to any one of the preceding claims, wherein said thermochromic fiber (1) comprises luminescent material, said luminescent material constituting a layer or the central core of said thermochromic fiber (1) and / or being incorporated into one or more layers of said thermochromic fiber (1).The thermochromic fiber (1) according to claim 12, wherein said thermochromic fiber (1) comprises a central core consisting of said luminescent material, preferably made in the form of optical fibers, said central core being surrounded by said at least one sensing layer (7).The thermochromic fiber (1) according to any one of the preceding claims, wherein said at least one heating layer (3), said at least one sensing layer (7) and said at least one thermochromic layer (5) are made of flexible materials.The thermochromic fiber (1) according to any one of the preceding claims, wherein said thermochromic fiber (1) may incorporate and / or be associated with lighting systems.A micro-interactive system (13), intended to allow interaction between a user and the electronics provided in one or more external devices (12), said system being controlled by an electronic control unit (11), characterized in that it comprises one or more thermochromic fibers (1) according to any one of claims 1 – 15, wherein said at least one heating layer (3) and said at least one sensing layer (7) of said one or more thermochromic fibers (1) are electrically connected to said electronic control unit (11), said electronic control unit (11) being suitable for receiving the signal generated by said at least one sensing layer (7) when said layer detects said physical property, processing said signal, and, based on said signal:- activating one or more functions of said one or more external devices (12); and- controlling the flow of electric current in said at least one heating layer (3) so as to cause an increase in the temperature of said at least one heating layer (3) and activate the color change of said at least one thermochromic layer (5).The micro-interactive system (13) according to claim 16, wherein said micro-interactive system (13) comprises bundles of thermochromic fibers (1), and wherein the thermochromic fibers (1) forming said bundles can be twisted with one another or arranged in parallel close to one another or braided or interwoven with one another.The micro-interactive system (13) according to claim 16 or 17, wherein each of said one or more thermochromic fibers (1) are made with thermochromic layers (5) having different colors and / or activatable at different temperatures.The micro-interactive system (13) according to claim 16 or 17 or 18, wherein luminescent fibers, filaments, optical fibers or ribbons (25) are associated, for instance twisted, braided with said one or more thermochromic fibers (1).Method for manufacturing a thermochromic fiber, said method being a solution-based process that comprises the following steps:- providing a heating element forming a heating layer;- preparing a first solution and dispersing sensing materials, coatings and / or sensors in said first solution to make a sensing solution;- preparing a second solution and dispersing thermochromic materials in said second solution to make a thermochromic solution;- applying one over the other, successively and in any order, said heating layer, a sensing layer obtained by applying said sensing solution and a thermochromic layer obtained by applying said thermochromic solution so as to obtain a multilayered fiber.Method according to claim 20, wherein said sensing solution is uniformly applied.Method according to claim 20, comprising the further steps:- applying a masking layer, said masking layer having different patterns;- coating said sensing solution on the masking layer;- removing the masking layer in order to obtain different patterns.Method according to claim 20 or 21 or 22, further comprising the steps of:- preparing a third solution and dispersing background pigment in said third solution to make a background solution;- applying one over the other, successively and in any order, said heating layer, said sensing layer, said thermochromic layer and a background layer obtained by applying said background solution so as to obtain a multilayered fiber.Method according to claim 20 or 21 or 22, comprising the following steps:- providing said heating element as a central core;- coating the sensing solution on the central core, thus obtaining said sensing layer;- coating the thermochromic solution on the sensing layer, thus obtaining said thermochromic layer.Method according to claim 23, comprising the following steps:- providing said heating element as a central core;- coating said sensing solution on said central core, thus obtaining said sensing layer;- coating the background solution on said sensing layer, thus obtaining said background layer;- coating said thermochromic solution on said background layer, obtaining said thermochromic layer.Method according to any one of the claims 20 – 25, wherein, after the application of the thermochromic solution, the method according to the present invention comprises the following steps:- preparing a transparent or translucent solution;- coating the transparent or translucent solution on the last applied layer, obtaining a transparent or translucent layer.Method according to any one of the claims 20 – 26, wherein the method according to the present invention comprises the following steps:- preparing a fourth solution with or without additives in said fourth solution to make a shielding solution;- coating the shielding solution on said thermochromic fiber as outermost layer, thus obtaining a shielding layer.Method according to any one of the claims 20 – 27, wherein said heating element is selected from metal wires, metal alloy wires, carbon fibers, carbon-based wires, bicomponent fibers with a heating element, polymer composite filaments or their combinations or is inserted into a flexible tube or hollow fiber.

Images