EMBROIDERED SENSOR

Description

[0001] The invention relates to a sensor configured to detect and / or measure a force acting on the sensor. The sensor preferably operates piezoresistively. The sensor can detect or measure an applied compressive or bending force. It is arranged, in particular, on a flexible carrier, which can be formed, for example, from a textile material. The textile material used can be, for example, a woven textile material and / or a knitted textile material and / or a warp-knitted textile material and / or a nonwoven material.

[0002] US 2003 / 0119391 A1 discloses a sensor for detecting an applied force. The sensor may comprise a textile material with a first electrode made of first conductors and a second electrode made of second conductors. In one embodiment, the conductors may be arranged in a matrix configuration by stitching.

[0003] GB 2 343 516 A discloses a textile pressure sensor with conductive layers or strips and a separating insulator. The layers can be manufactured by weaving or knitting.

[0004] The pressure sensor known from US 2008 / 0307899 A1 is designed for integration into textile products. The pressure sensor has a multilayered thread, one of which is a pressure-sensitive layer. The thread can be integrated into the textile product by weaving, knitting, warp-knitting, or sewing.

[0005] US 2016 / 0328043 A1 describes a sensor in which a conductive pattern is embroidered onto a flexible carrier. The sensor is designed as a capacitive sensor. In one embodiment, the conductive pattern has conductive nodes. A cover layer has conductive mating contacts. An intermediate layer is present between the cover layer and the carrier, adjacent to the conductive nodes and the mating contacts, to create a distance between a node and an opposite mating contact as long as no force acts on the cover layer. When the cover layer is pressed in, the mating contact comes into contact with the node and can establish an electrical connection. Such an arrangement can be used, for example, to form a keyboard.

[0006] US 9,816,799 B2 discloses a deformation sensor with an electrically conductive element applied to or incorporated into a textile carrier. Deformations of the textile carrier can be detected because they change the distance between sections of the electrically conductive element. The electrically conductive element can, for example, be arranged in a meandering pattern. Alternatively, two electrically conductive elements can be present in an interdigital arrangement.

[0007] US 2017 / 0261388 A1 describes a pressure sensor consisting of interdigital electrodes printed on a substrate. Printing electrodes is not readily possible on all types of substrates. Depending on the structure and material of the substrate, capillary effects can lead to printing errors, for example, with textile substrates.

[0008] US Patent No. 8,701,578 B2 describes a garment in which embroidered patterns are applied to create an electrically conductive communication path. Sensors can be connected to these embroidered communication paths.

[0009] Interactive textiles are described in US 2016 / 0048235 A1. This involves a fabric with conductive threads, with a multilayer structure proposed for forming a capacitive pressure sensor.

[0010] US Pat. No. 7,770,473 B2 discloses a pressure sensor made of a multilayer yarn with conductive fibers and a pressure-sensitive layer. Such a multilayer yarn can be incorporated into a knitted fabric as a standing thread. The pressure sensor is formed by the multilayer yarn itself.

[0011] US Pat. No. 8,505,474 B2 discloses a method for producing a conductive yarn. In this process, metallic fibers are coated with non-conductive filaments.

[0012] Another well-known principle for manufacturing a sensor is the formation of a sandwich structure from several separate layers. Such sensors are known, for example, from US Pat. Nos. 7,145,432 B2, 8,661,915 B2, and 8,904,876 B2.

[0013] In addition, US 2004 / 0173028 A1 and DE 10 2013 001 772 A1 disclose the possibility of integrating pressure sensors into surfaces in a vehicle.

[0014] Interlink Electronics offers a touch sensor with a variable resistor called FFR®. It consists of several polymer layers bonded together by lamination. One polymer layer is coated with interdigitating electrodes, while the other polymer layer is coated with a special semiconductor material. By applying pressure, the electrodes can be connected in parallel via the semiconductor material.

[0015] Further background information on textile-based sensors can be found in the specialist literature: BOSOWSKI, P., et al., "Design and manufacture of textile-based sensors",Electronic Textiles, Elsevier, 2015, S. 75-107. MEYER, Jan; LUKOWICZ, Paul; TROSTER, Gerhard, "Textile pressure sensor for muscle activity and motion detection", Wearable Computers, 10th IEEE International Symposium, S. 69-72, 2006. MEYER, Jan, et al., "Design and modeling of a textile pressure sensor for sitting posture classification", IEEE Sensors Journal 10 (8), S. 1391-1398, 2010. LINZ, Torsten; GOURMELON, Lena; LANGEREIS, Geert, "Contactless EMG sensors embroidered onto textile", 4th International Workshop on Wearable and Implantable Body Sensor Networks, Berlin, Heidelberg, Springer, 2007, S. 29-34. MECNIKA, V., et al., "Joining technologies for electronic textiles",Electronic Textiles, Elsevier, 2015, S. 133-153. HASANI, M., et al., "Implementation of a dual-interrogationmode embroidered RFID-enabled strain sensor", IEEE Antennas and Wireless Propagation Letters 12, S. 1272-1275, 2013. ZHANG, Lanlin, et al., "Embroidered textiles for RF electronics and medical sensors", Wireless Information Technology and Systems (ICWITS), 2012 IEEE International Conference, pp. 1-4, 2012. KOO, Hye Ran, et al., "The effect of textile-based inductive coil sensor positions for heart rate monitoring", Journal of medical systems 38 (2), p. 2, 2014. MECNIKA, Viktorija, et al., "Preliminary Study on Textile Humidity Sensors", Smart SysTech 2015; European Conference on Smart Objects, Systems and Technologies; Proceedings of. VDE9, pp. 1-9, 2015. GRIES, Thomas; KLOPP, Kai (eds.), "Joining and surface technologies for textiles: processes and applications", Springer-Verlag, 2007. .

[0016] Based on the known prior art, it is an object of the present invention to provide a sensor for detecting a compressive force and / or a bending force, which can be manufactured cost-effectively using simple means.

[0017] This problem is solved by a sensor having the features of patent claim 1.

[0018] The sensor according to the invention is designed to detect and / or measure a force acting on the sensor. In the simplest case, the acting force can be digitally recorded. In one embodiment of the sensor, a sensor variable dependent on the magnitude of the acting force, in particular an electrical sensor variable, can be generated by the sensor. For this purpose, the sensor preferably operates piezoresistively. The sensor can be used, for example, as a pressure sensor or bending sensor.

[0019] The sensor has a carrier. The carrier is preferably made of a flexible material. The carrier is a planar element that is essentially 2-dimensional or 2.5-dimensional. This is understood to mean a planar element that has a thickness that is at least one order of magnitude smaller than the length and width in a plane in which the carrier extends. A textile material, such as a woven fabric, a knitted fabric, a warp-knitted fabric, or a nonwoven material, or any combination thereof, can be used as the carrier. The carrier or textile material is preferably designed as a single-layer.

[0020] A first electrode and a second electrode are formed on the carrier by embroidery. The electrodes are not only attached to the carrier by the embroidery, but are formed by the embroidered thread on the carrier. A first electrode is formed by embroidering at least one first thread on the carrier, and a second electrode is formed by embroidering at least one second thread on the carrier. The at least one first thread and the at least one second thread have electrically conductive components or are formed by such electrically conductive components. Such components can be formed by fibers and / or at least one filament and / or a filler and / or a coating. The at least one first thread and / or the at least one second thread can be formed as a yarn or twisted thread, with twisted thread being preferred due to its better embroiderability.

[0021] The two electrodes are arranged at a distance from one another on the carrier, so that the at least one first thread and the at least one second thread are not arranged in direct contact with one another on the carrier. The electrodes formed by the stitching are preferably arranged on a common side of the carrier and are preferably located in a common position directly on the relevant side of the carrier. Depending on whether the carrier is aligned in a plane or is curved or bent, the first and / or second electrodes can also run flat, curved, or bent along the surface of the carrier.

[0022] The embroidered sensor also has a cover layer formed by at least one third thread embroidered on the carrier. As with the electrodes, the cover layer is not designed as a separate element that is attached to the carrier by embroidery, but is formed by embroidery with at least one third thread. The at least one third thread has electrically conductive components. The at least one third thread can be formed by a yarn or, preferably, a twisted yarn. It rests at several contact points on the at least one first thread of the first electrode and on the at least one second thread of the second electrode. Preferably, a section of the at least one first or second thread is arranged at each contact point between the section of the at least one third thread and the carrier.

[0023] Depending on the force acting on the cover layer, which can be generated by pressure or bending, the electrical conductivity between the first and second electrodes of the sensor changes. This allows the applied force to be detected and / or measured.

[0024] The entire sensor can therefore be manufactured by embroidery. Embroidery is a process that can be carried out without complex production equipment using a sewing or embroidery machine. By stitching the threads onto the carrier, the two electrodes and the cover layer are created, producing a sensor. The electrodes and the cover layer created by embroidery can be applied to many different carrier materials, even to carrier materials that are unsuitable for printing due to their capillary action. Creating multiple sensor layers or sensor plies and then bonding these sensor layers or sensor plies is not necessary. The sensor can be manufactured in a continuous process on a single sewing or embroidery machine. It may simply be expedient to use different threads for embroidering the electrodes and the cover layer.On embroidery machines with multiple heads, such a thread change can be carried out very quickly and easily.

[0025] Preferably, at least not all of the threads, and in particular not the at least one first thread forming the first electrode, nor the at least one second thread forming the second electrode, have their own sensor properties. According to the invention, the sensor function is not achieved by one of the threads, but rather by the interaction of the threads of the electrodes and the cover layer.

[0026] Preferably, the at least one third thread has an electrical conductivity that is different from the electrical conductivity of the at least one first thread and / or the at least one second thread. In particular, the at least one third thread has an electrical conductivity that is lower than the electrical conductivity of the at least one first thread and / or the at least one second thread. The at least one first thread and the at least one second thread can have the same electrical conductivity and can, in particular, be identical.

[0027] The at least one first thread and / or the at least one second thread and / or the at least one third thread may comprise electrically conductive fibers and / or fillers and / or at least one electrically conductive filament and / or an electrically conductive coating. Silver, stainless steel, carbon, carbon black, or other known materials or combinations thereof may be used as the electrically conductive material for the fibers, fillers, filaments, or coating.

[0028] In one embodiment, the sensor has a total resistance between a first terminal of the first electrode and a second terminal on the second electrode, the magnitude of which depends on a force acting on the cover layer. This force can be caused by pressure or bending of the carrier or sensor. The total resistance can depend on a first contact resistance between the at least one first thread of the first electrode and the at least one third thread of the cover layer and on a second contact resistance between the at least one second thread of the second electrode and the at least one third thread of the cover layer. In addition, the total resistance can also depend on a contact resistance of the at least one third thread, the magnitude of which can depend on the acting force and the resulting deformation of the at least one third thread.Thus, the total resistance can be formed by at least one series circuit consisting of a first contact resistance, a second contact resistance, and an optionally variable contact resistance. Several such series circuits can also be connected in parallel, which then determine the total resistance between the first terminal and the second terminal. This depends, for example, on the size of the point where the force is applied and how many contact points are affected by the force.

[0029] The first electrode has a first base zone and a plurality of first electrode fingers extending from the first base zone. A first gap is formed between each two immediately adjacent first electrode fingers. Similarly, the second electrode has a second base zone and a plurality of second electrode fingers extending from the second base zone. A second gap is formed between each two immediately adjacent second electrode fingers.

[0030] In one embodiment, multiple first threads can be used to embroider the first electrode and / or multiple second threads can be used to embroider the second electrode. This allows different regions of the first electrode and / or the second electrode to be manufactured or embroidered from different materials. For example, the base zone can be embroidered from a different thread material than the electrode fingers of the first electrode and / or the second electrode. This configuration can be particularly advantageous, for example, if the sensor is designed in the form of a potentiometer.

[0031] The first electrode fingers are preferably aligned parallel to one another. The second electrode fingers are preferably aligned parallel to one another. It is further advantageous if the first electrode fingers and the second electrode fingers run parallel to one another. At least one second electrode finger can protrude into a first intermediate space, and at least one first electrode finger can protrude into a second intermediate space. This creates an interdigital arrangement of the two electrodes. The distance between the first electrode fingers and the adjacent second electrode fingers is preferably the same. It is advantageous if the electrode fingers are arranged at regular intervals.

[0032] Instead of the interdigital arrangement of the electrodes, the electrodes can also have a different shape. For example, the electrode fingers and / or the base zones can have at least one bend and / or at least one kink. The base zones can be linear (the width can, for example, be at least 5-10 times smaller than the length) or they can enclose or fill an area, for example, a circular or polygonal area.

[0033] In one embodiment, the first electrode and the second electrode can run essentially parallel to one another at least in a region in which the cover layer covers the two electrodes. In this region, the two electrodes can be arranged next to one another at an approximately constant distance. In this region, the electrodes can each have one or more curves and / or kinks and / or corners. For example, both electrodes can run in a meandering manner at least in this region. There can also be several such regions, which are arranged spatially separated from one another on the carrier. In this one or more regions, each electrode can extend without a branching point. Branching points can be present between every two such regions. One or more such regions can form, for example, shapes, symbols, letters or the like.

[0034] In such a configuration, sections of the first electrode and / or the second electrode can run directly adjacent and parallel to one another, while in an interdigital arrangement, electrode fingers of different electrodes are preferably arranged directly adjacent to one another.

[0035] At least some of the first spaces and the second spaces are preferably dimensioned such that sufficient space remains for puncture points of the at least one third thread of the cover layer. Several puncture points of the embroidered cover layer, at which the at least one third thread pierces the carrier, are preferably arranged in the first and second spaces, respectively, adjacent to the electrode fingers. The puncture points of the at least one third thread penetrate neither the at least one first thread of the first electrode nor the at least one second thread of the second electrode.

[0036] The at least one third thread of the cover layer has a plurality of stitches, each with at least one contact point, referred to as bridging stitches. Each bridging stitch preferably has a contact point with the at least one first thread and a contact point with the at least one second thread.

[0037] In one embodiment, each bridging stitch can overlap one of the first electrode fingers and one of the second electrode fingers. Preferably, a bridging stitch overlaps exactly one first electrode finger and exactly one second electrode finger. The bridging stitch extends between two puncture points located on opposite sides of the electrode fingers arranged below.

[0038] In one embodiment, the bridging stitches that span a specific or considered first electrode finger each span only one of the immediately adjacent second electrode fingers. This makes it possible to form a bridging stitch group from bridging stitches whose puncture points are arranged on two parallel lines, wherein these lines are aligned parallel to the associated first electrode finger and the associated second electrode finger. In an alternative embodiment, contact is established with two immediately adjacent second electrode fingers via the bridging stitches that span a specific or considered first electrode finger. For this purpose, some of these bridging stitches span the first electrode finger and one second electrode finger, and some other bridging stitches span the first electrode finger and the other second electrode finger.The bridging stitches are offset from one another in a direction perpendicular to the direction of extension of the electrode finger and overlap in the area in which the first electrode finger extends.

[0039] The arrangement of the bridging stitches described above in connection with a considered first electrode finger can be present accordingly for a considered second electrode finger.

[0040] It is also preferred if the at least one third thread of the cover layer overlaps the at least one first thread and the at least one second thread exclusively at the electrode fingers. The third thread therefore does not overlap the first electrode or the second electrode in the region of the first base zone or the second base zone, respectively.

[0041] In one embodiment, the sensor can be designed as a potentiometer. It is particularly advantageous if the first base zone of the first electrode or the second base zone of the second electrode forms a resistance zone. The resistance along the resistance zone can increase in a direction of extension of the resistance zone, starting from the respective connection of the electrode. The resistance between an electrode finger and the connection can be greater due to the increasing resistance of the resistance zone, the further the electrode finger is away from the respective connection. As a result, the total resistance of the sensor between the first connection of the first electrode and the second connection of the second electrode can vary depending on the point at which an electrically conductive or better conductive connection is established between the two electrodes due to the application of force.

[0042] In all embodiments, in addition to the first electrode and the second electrode, at least one spacer element can be present on the carrier, which is arranged between the carrier and the cover layer. The spacer element is located on the carrier next to the first electrode and the second electrode, for example in a space between the two electrodes. By means of the at least one spacer element, the distance between the cover layer and the carrier or between the cover layer on the one hand and the first electrode and the second electrode on the other hand can be predetermined for an initial state in which no external force acts on the cover layer. By means of the at least one spacer element, for example, the contact between the cover layer and the first electrode and / or the second electrode in the initial state can be prevented or reduced.

[0043] In a preferred embodiment, the at least one spacer element can be formed by at least one spacer thread. The at least one spacer thread can be sewn or embroidered onto the carrier.

[0044] The spacer thread is arranged at least in the region between or next to the electrodes in which the cover layer is located. The spacer thread is located there between the cover layer and the carrier. The spacer thread can be arranged, for example, in at least one first intermediate space and / or at least one second intermediate space. The spacer thread is preferably electrically non-conductive. The thickness of the spacer thread is preferably greater than the thickness of the at least one first thread and the at least one second thread. The spacer thread can reduce the contact between the at least one third thread and the at least one second thread or between the at least one third thread and the at least one first thread in the idle state, without any force acting on the sensor.

[0045] By using one or more of the above embodiments of the invention, a very flat sensor is achieved. The material used to manufacture the sensor is minimal, and only minimal waste is generated during production. The measuring range and / or sensitivity can be determined by one or more of the following properties: the choice of thread or yarn or twine for the first thread and / or the second thread and / or the third thread; the arrangement of the electrodes and / or the bridging stitches of the cover layer; the arrangement of the bridging stitches of the cover layer; integration of the additional spacer thread.

[0046] The sensor according to the invention can also be produced with one or more other embroidered sensors in a common process on a sewing or embroidery machine, for example, with another sensor according to the invention or a humidity sensor. The sensor according to the invention can also be combined with other embroidered electrical functional areas, such as supply lines and / or heaters, during embroidery.

[0047] Advantageous embodiments of the invention will become apparent from the dependent claims, the description, and the drawings. Preferred embodiments of the invention are explained in detail below with reference to the drawings. They show: Figure 1 a schematic view of a carrier, a first electrode formed by a first thread and a second electrode formed by a second thread, Figure 2 a schematic representation of a sensor with the carrier and the electrodes from Figure 1 and a covering layer of a third thread which is in contact with the first electrode and the second electrode, Figures 3 and 4 each a schematic view of further embodiments of the sensor according to Figure 2 , whereby the stitches of the cover layer are arranged differently than in the embodiment according to Figure 2 , Figure 5 a schematic representation of a bridging stitch of the third thread of the cover layer, which overlaps a first thread of the first electrode and a second thread of the second electrode, Figure 6 the representation from Figure 5 during pressure on the third thread, Figure 7 an electrical equivalent circuit diagram of a total resistance of a bridging stitch of the at least one third thread, which changes depending on the action of a force, Figure 8a schematic representation of a carrier on which a first electrode and a second electrode are embroidered, wherein a spacer thread is embroidered or sewn onto the carrier between the two electrodes, Figure 9 a schematic diagram of a bridging stitch of the third thread such as a first thread, a second thread and a spacer thread in the embodiment according to Figure 8 , Figure 10 a schematic diagram of a potentiometer formed by the sensor, Figure 11 an equivalent circuit diagram of the Figure 10 illustrated potentiometer, Figure 12 a schematic view of a carrier, a first electrode formed by a first thread and a second electrode formed by a second thread and Figure 13 a schematic representation of another embodiment of the sensor with the carrier and the electrodes from Figure 12and a covering layer of a third thread which is in contact with the first electrode and the second electrode.

[0048] The invention relates to a sensor 15 which can be produced by embroidery. In the Figures 2 to 4 , 8 and 10 Different embodiments of a sensor 15 are shown schematically. The sensor 15 is designed to measure a force F ( Figure 6 ). This can either detect or determine only the presence of an external force, or optionally, a sensor value can be generated that depends on the magnitude of the applied force and / or the location at which the force F acts.

[0049] The sensor 15 can be referred to as an embroidered sensor 15. It has a carrier 16, which is preferably designed as a textile carrier 16. The carrier 16 is generally a flat structure and thus has a length and a width in a plane of extension that are one or more orders of magnitude greater than a thickness of the carrier 16 perpendicular to its plane of extension. The carrier 16 can be made of plastic material and / or natural material. The carrier 16 is preferably designed as a textile carrier, e.g. as a knitted and / or warp-knitted fabric and / or woven and / or nonwoven material. The carrier 16 can be part of a garment or another textile surface.

[0050] A first electrode 18 is created on the carrier 16 by embroidery using at least one first thread 17. The figures schematically illustrate the individual stitches, viewed from one side of the carrier 16, which are created on the carrier 16 by the at least one first thread 17. The at least one first thread 17 comprises electrically conductive components, such as electrically conductive fibers, filaments, or fillers. Silver, stainless steel, or carbon, or a combination thereof, can be used as the electrically conductive material. The at least one first thread 17 can also have an electrically conductive coating.

[0051] Using at least one second thread 19, a second electrode 20 is created by stitching onto the carrier 16 and, for example, on the same side of the carrier 16. The at least one second thread 19 has electrically conductive components and can be constructed as explained above for the first thread 17. The at least one first thread 17 and the at least one second thread 19 preferably have the same electrical conductivity and can be identical.

[0052] As is particularly the case in Figure 1 As illustrated, the first electrode 18 and the second electrode 20 are in some embodiments ( Figures 1-4 , 8 , 10) arranged interdigitally. For this purpose, the first electrode 18 has a first base zone 21 which extends away from a first connection 22, for example in a straight line. A plurality of first electrode fingers 23 protrude transversely and preferably at right angles from the first base zone 21. The first electrode fingers 23 are arranged parallel to one another at equal intervals. A first intermediate space 24 is formed between two immediately adjacent first electrode fingers 23. The number of first electrode fingers 23 and thus the number of first intermediate spaces 24 can vary depending on the realized size of the sensor. The length of the base zone 21 or the length of the first electrode fingers 23 can also vary. In the exemplary embodiment, all first electrode fingers 23 are the same length.

[0053] The second electrode, which is made from the at least one second thread 19, is constructed analogously to the first electrode 18. It has a second base zone 25 which extends from a second connection 26, for example in a straight line. The first base zone 21 and the second base zone 25 preferably run parallel to one another and are arranged at a distance from one another. A plurality of second electrode fingers 27 protrude transversely and preferably at right angles from the second base zone 25. In the exemplary embodiment, the second electrode fingers 27 are arranged parallel to one another and at equal distances from one another. They are preferably of equal length. A second intermediate space 28 is formed between each two immediately adjacent second electrode fingers 27.

[0054] Threads made of different materials can be used for embroidering the base zones 21, 25 and the electrode fingers 23, 27. For example, the first electrode 18 can be embroidered from two different (in particular, differently conductive) first threads, and the second electrode 20 can be embroidered from two different (in particular, differently conductive) second threads.

[0055] In the exemplary embodiment, the first electrode fingers 23 and the second electrode fingers 27 are arranged parallel to one another. At least one, and, for example, exactly one, second electrode finger 27 protrudes into one, several, or all of the first gaps 24. At least one, and, for example, exactly one, first electrode finger 23 protrudes into one, several, or all of the second gaps 28. Therefore, a first electrode finger 23 and a second electrode finger 27 are always arranged alternately in a direction parallel to the extension of the first base zone 21 and the second base zone 25.

[0056] A distance exists between the first electrode 18 and the second electrode 20 such that the at least one first thread 17 and the at least one second thread 19 do not directly touch one another. In the exemplary embodiment, a first distance a exists between each first electrode finger 23 and an immediately adjacent second electrode finger 27, viewed parallel to the direction of extension of the base zones 21, 25. Viewed parallel to the direction of extension of the electrode fingers 23, 27, a second distance b exists between the free end of the first electrode fingers 23 and the second base zone 25. Accordingly, the same second distance b can exist between the free end of the second electrode fingers 27. In one exemplary embodiment, the first distance a and the second distance b are of equal magnitude.

[0057] As already explained, there is no direct contact and no direct electrically conductive connection between the first electrode 18 and the second electrode 20. The carrier 16 is, at least in the region in which the electrodes 18, 20 are arranged thereon, electrically non-conductive or at least not designed in such a way that it establishes an indirect electrical contact between the two electrodes.

[0058] An indirect contact and an indirect electrically conductive connection between the first electrode 18 and the second electrode 20 can be established via a cover layer 32. The cover layer 32 is formed by stitching at least one third thread 33 onto the carrier 16. Analogous to the at least one first thread and the at least one second thread, the at least one third thread has electrically conductive components and can have a structure as described in the introduction in connection with the first thread 17. Preferably, the at least one third thread 33 is different from the at least one first thread 17 and the at least one second thread 19. In particular, the electrical conductivity of the at least one third thread 33 is different from the electrical conductivity of the threads 17, 19 of the electrodes 18, 20.For example, the electrical conductivity of the at least one third thread 33 - at least in a state in which no external force acts on the at least one third thread 33 - is smaller than the electrical conductivity of the first thread 17 and the second thread 19. In one embodiment, the at least one third thread 33 has electrically conductive components, such as fillers and / or fibers and / or filaments, the spacing of which changes upon external influence, whereby the conductivity of the at least one third thread 33 is changed and preferably increases.

[0059] The at least one third thread 33 overlaps the first electrode 18 and the second electrode 20 at several points and thereby forms several first contact points 34 with the at least one first thread 17 and several second contact points 35 with the at least one second thread 19. Each first contact point 34 has a first contact resistance R1 between the first thread 17 and the third thread 33 and each second contact point 35 has a second contact resistance R2 between the second thread 19 and the third thread 33. The at least one third thread 33 can have a variable contact resistance R3.

[0060] As can be seen from the Figures 5 to 7As is illustrated schematically, by acting on the cover layer 32, the contact between the at least one third thread 33 and the at least one first thread 17 or the at least one second thread 19 can be improved, so that the first contact resistance R1 and the second contact resistance R2 become smaller. Optionally, the contact resistance R3 of the third thread 33 can also be reduced by the action of the force, for example by electrically conductive components of the third thread 33 establishing a better electrical connection with one another along the extent of the third thread 33 due to the acting force F, whereby its conductivity is increased or its contact resistance R3 between a first contact point 34 and an immediately adjacent second contact point 35 is reduced.

[0061] As it is in the Figures 2 to 4As is schematically illustrated, the at least one third thread 33 of the cover layer 32 forms, by stitching onto the carrier 16, a plurality of stitches referred to as bridging stitches 36, each of which has a first contact point 34 and a second contact point 35, and which, in the exemplary embodiment, each overlap a first electrode finger 23 and an immediately adjacent second electrode finger 27. It is preferred if each bridging stitch 36 overlaps exactly one first electrode finger 23 and exactly one second electrode finger 27. As a result, a bridging stitch 36 can be kept very short between its two stitching points 37.

[0062] A bridging stitch 36 between two puncture points 37 is shown schematically in the Figures 5 and 6 illustrated. The Figures 2 to 4show different embroidery patterns that can be used to arrange the bridging stitches 36 of the cover layer 32. In the embodiment shown in Figure 2, each first electrode finger 23 is assigned exactly one second electrode finger 27, which form a common electrode finger pair. An electrode finger pair 23, 27 is overlapped by a bridging stitch group consisting of several bridging stitches 36. Bridging stitches 36 that connect electrode fingers of different electrode finger pairs to one another are not present. For example, the bridging stitches 36 assigned to a common electrode finger pair 23, 27 are arranged such that the puncture points 37 are aligned along two parallel lines, these lines extending parallel to the electrode fingers 23, 27 of the electrode finger pair.The bridging stitches 36 thus each form a bridging stitch group for a pair of electrode fingers, wherein the bridging stitch groups do not overlap in a direction parallel to the direction of extension of the base zones 21, 25 and are connected to one another either with contact or with a distance.

[0063] In the Figures 3 and 4An alternative embodiment is shown. The bridging stitches 36 are arranged offset from one another parallel to the direction of extension of the base zones 21, 25. As a result, a first electrode finger 23, which projects into a second intermediate space 28, is coupled by several bridging stitches 36 to the one immediately adjacent second electrode finger 27 and by several other bridging stitches 36 to the other immediately adjacent second electrode finger 27. As a result, the electrical connection between the first electrode 18 and the second electrode 20 can be improved by the cover layer 32, at least when an external force F is applied.

[0064] The embroidery density of the bridging stitches 36 can vary.

[0065] The difference between the design according to Figure 3 and the design according to Figure 4 is that in the embodiment according to Figure 3Bridging stitches 36, which are arranged in a row or line at right angles to the direction of extension of the base zones 21, 25, are connected to one another essentially without a gap, while the bridging stitches 36 in this direction in the embodiment according to Figure 4 have a distance from each other.

[0066] Apart from the arrangement of the bridging stitches 36, the embodiments according to the Figures 2 to 4 executed identically.

[0067] In the preferred embodiments illustrated here, each bridging stitch 36 has at least one puncture point 37 located in a first intermediate space 24 and a second intermediate space 28. All puncture points 37 are arranged adjacent to the respective electrode fingers 23, 27 and do not penetrate the at least one first thread 17 or the at least one second thread 19.

[0068] The cover layer 32 is viewed in the direction of extension of the electrode fingers 23, 27, in some embodiments ( Figures 1-4 , 8 and 10 ) is limited to the area between the first base zone 21 and the second base zone 25. The third thread 33 preferably overlaps neither the first base zone 21 nor the second base zone 25. The first contact points 34 and the second contact points 35 are present exclusively on the electrode fingers 23 and 27, respectively, at which the at least one third thread 33 overlaps the electrodes 18, 20.

[0069] In Figure 71 schematically illustrates an electrical equivalent circuit for a resistance between a first thread 17 and a second thread 19, which are connected to each other via exactly one first contact point 34 and exactly one second contact point 35 by a single bridging stitch 36. This resistance is formed by the series connection of the first contact resistance R1, the contact resistance R3, and the second contact resistance R2. The values ​​of all individual resistances R1, R3, R2 in this series connection, but at least the values ​​of the two contact resistances R1, R2, are variable depending on the acting force F.

[0070] As shown schematically in Figure 6As illustrated, the action of the force F can be generated, for example, by pressing with the tip of a finger 38 onto the cover layer 32. The force F generally acts not only on a single bridging stitch 36 of the cover layer 32, but on a plurality of bridging stitches 36. Thus, several series circuits of a first contact resistance R1, a contact resistance R3 and a second contact resistance R2, as shown in Figure 7 is schematically illustrated, connected in parallel by acting on the several bridging stubs 36. Then, a total resistance RG results between the first terminal 22 and the second terminal 26 by the parallel connection of several series circuits, one of which is schematically shown with Figure 7 is illustrated.

[0071] The total resistance RG is determined even without the action of an external force F by a plurality of parallel series circuits 39 according to Figure 7 formed when an electrically conductive connection between the two electrodes 18, 20 is already established by the cover layer 32 without the action of an external force F, the total resistance RG of which can be changed and in particular reduced by the action of the force F.

[0072] If an electrically conductive connection between the two terminals 22, 26 has already been established without the application of an external force F, the uninterrupted nature of the electrical connection can be tested even without the application of an external force F.

[0073] In the Figures 12 and 13 A further embodiment of the embodiment of a sensor 15 is illustrated, wherein for a better overview in Figure 12the cover layer 32 has been omitted and only the electrodes 18, 20 are illustrated. In this embodiment, the two electrodes 18, 20 extend approximately parallel to one another at a distance, at least in a section in which the cover layer 32 is applied to the carrier, in a serpentine or meandering manner in the exemplary embodiment. Due to this meandering course, for example, two approximately parallel sections of the second electrode 20 are arranged between two parallel sections of the first electrode 18. The exact course and shape of the electrodes 18, 20 can vary and form, for example, letters, numbers, or symbols. The bridging stitches 36 of the cover layer 32 each overlap the first electrode 18 and the second electrode 20 along their extent. In Figure 13A cover layer 32 with a low density of bridging stitches 36 is shown schematically to illustrate the principle of the sensor structure. The density of the bridging stitches 36 can also be higher.

[0074] The puncture holes of the bridging stitches 36 of the cover layer 32 are in the Figure 13 In the illustrated embodiment, they are arranged adjacent to or between two sections of the same electrode 18 or 20. Depending on the shape of the path of the electrodes 18, 20, sufficient space can be created for a higher or lower stitch density of the bridging stitches 36. It is preferred if the distances between the puncture points of the bridging stitches 36 are as small as possible in order to optimally utilize the area. However, the puncture points of the bridging stitches 36 must not damage or inadvertently short-circuit the underlying electrodes 18, 20.

[0075] Due to the meandering shape of the electrodes 18, 20, it is possible to provide the entire area occupied by the electrodes 18, 20 with a covering layer 32 and to use it as a pressure-sensitive surface. The number of bridging points per unit area is lower than in the previously described interdigital arrangement, as used, for example, in the Figures 1 to 4 is illustrated.

[0076] In the Figures 8 and 9A further possible design of the sensor 15 is schematically illustrated, which can be combined with all other embodiments of the sensor 15. In this embodiment, a spacer thread 45 is embroidered on the carrier 16. The spacer thread 45 is located on the carrier 16 on the same side or in the same plane as the first electrode 18 and the second electrode 20. The thickness or diameter of the spacer thread 45 is greater than the thickness or diameter of the at least one first thread 17 and the at least one second thread 19. The spacer thread 45 is embroidered on the carrier 16 at least where the cover layer 32 is located. Preferably, each bridging stitch 36 of the cover layer 32 overlaps a section of the spacer thread 45.Without the action of an external force, the maximum distance of the third thread 33 of a bridging stitch 36 from the carrier 16 is increased compared to a variant without a spacer thread 45, and the first contact resistance R1 and the second contact resistance R2 are increased. The first contact resistance R1 and / or the second contact resistance R2 can be increased such that no measurable current flow occurs between the first connection 22 and the second connection 26 at the voltage and current intensities typically used for sensors - the first contact resistance R1 and / or the second contact resistance R2 can be infinitely large, so to speak, as long as no external force acts, if at the contact points 34, 35 there is a distance between the third thread 33 and the first thread 17 or the second thread 19 without external force.

[0077] It is understood that in a case in which a plurality of threads forming a thread bundle are used for embroidering the electrodes 18, 20, at least one spacer thread 45 or a spacer thread bundle of a plurality of spacer threads 45 is used, the total thickness of which is greater than the total thickness of the fiber bundles of first threads 17 or second threads 19.

[0078] Using the embroidery technique, a sensor 15 can also be manufactured, which represents a potentiometer 46 (Figure 10). In the potentiometer 46, at least one base zone, and for example the first base zone 21, is designed as a resistance zone 47. The resistance zone 47 has a lower conductivity than the remaining parts of the first electrode 18. This can be achieved, for example, by stitching the resistance zone 47 from a thread that has a lower conductivity than the thread used to stitch the first electrode fingers 23. On the side opposite the first terminal 22, a third terminal 48 is electrically connected to the resistance zone 47. Between the first terminal 22 and the third terminal 48, a maximum potentiometer resistance provided by the resistance zone 47 is thus formed.

[0079] As described in connection with the first base zone 21, the first electrode fingers 23 extend at different locations in the resistance zone 47. The second electrode 20 is designed analogously to the embodiments described above.

[0080] When a force F acts on the cover layer 32 at an action point 49, an electrical coupling takes place between at least one first electrode finger 23 and at least one second electrode finger 27. Depending on where the action point 49 is located in the extension direction E of the resistance zone 47, the variable total resistance RG changes between the first terminal 22 and the second terminal 26. Figure 11 is a schematic equivalent circuit diagram for the potentiometer 46 from Figure 10The total resistance RG is essentially formed by the part of the resistance zone 47 that extends between the point of action 49 and the first terminal 22.

[0081] If a first voltage U1 is applied between the first terminal 22 and the third terminal 48, a second voltage U2 can be measured between the second terminal 26 and the third terminal 48, which second voltage U2 depends on the position of the point of action 49 in the direction of extension E. The following applies: U 1 R max = U 2 R max − RG

[0082] The invention relates to a sensor 15 produced by stitching threads 17, 19, 33 onto a carrier 16. The stitching forms a first electrode 18, a second electrode 20, and a cover layer 32. An electrically conductive connection between the first electrode 18 and the second electrode 20 can be established via the cover layer 32, at least when a force F acts on the cover layer 32 and presses at least a portion of the cover layer 32 against a portion of the first electrode 18 and the second electrode 20. This force F can be caused by pressure exerted locally on the cover layer 32 and / or by bending the cover layer 32 or the carrier 16. The entire sensor 15, and in particular the first electrode 18, the second electrode 20, and the cover layer 32, are produced exclusively by stitching onto a common carrier 16. The sensor is particularly simple and cost-effective to manufacture and is robust.

[0083] The invention also makes it possible to create very flat sensors 20. The material used to manufacture the sensor 15 is low, and only a small amount of waste is generated during production. The measuring range and measuring sensitivity of the sensor 15 can be selected by selecting the thread or yarn or twist for the first thread and / or the second thread and / or the third thread. The measuring range and measuring sensitivity can also be varied by the arrangement of the electrodes 18, 20 and / or the bridging stitches 36 of the cover layer 32. Instead of the interdigital arrangement of the electrodes 18, 20 illustrated in the example, any other shapes for forming the electrodes 18, 20 are also possible. For example, the electrode fingers 23, 27 can also have at least one curved point and / or at least one kink.The base zones 21, 25 do not necessarily have to run in a straight line, but can also have at least one curved point and / or at least one kink. The base zones 21, 25 can also enclose or occupy a surface, for example, a circular or polygonal surface. The sensor according to the invention can also be produced with one or more additional embroidered sensors in a common process on a sewing machine or embroidery machine, for example, with another sensor according to the invention or a humidity sensor. The sensor according to the invention can also be combined with other embroidered electrical functional areas, such as supply lines and / or heaters, during embroidery. List of reference symbols:

[0084] 15Sensor 16Carrier 17First thread 18First electrode 19Second thread 20Second electrode 21First base zone 22First connection 23First electrode finger 24First gap 25Second base zone 26Second connection 27Second electrode finger 28Second gap 32Cover layer 33Third thread 34First contact point 35Second contact point 36Bridging stitch 37Puncture point 38Finger 39Series connection 45Spacer thread 46Potentiometer 47Resistance zone 48Third connection afirst distance or further distance EExtension of the resistance zone FForce R1first contact resistance R2second contact resistance R3contact resistance RGtotal resistance R max maximum potentiometer resistance

Claims

1. Sensor (15) configured to detect and / or measure a force (F) applied on the sensor (15), wherein the sensor (15) comprises: - a carrier (16), - a first electrode (18) that is formed by at least one first thread (17) that is embroidered on the carrier (16) and that comprises electrically conductive components, - a second electrode (20) that is formed by at least one second thread (19) that is embroidered on the carrier (16) and that comprises electrically conductive components, wherein the two electrodes (18, 20) are arranged with distance to one another on the carrier (16), - a cover layer (32) that is formed by at least one third thread (33) that is embroidered on the carrier (16) and that comprises electrically conductive components, wherein the at least one third thread (33) of cover layer (32) is in abutment with the at least one first thread (17) of first electrode (18) and the at least one second thread (19) of second electrode (20) at multiple contact sites (34, 35), characterized in that the first electrode (18) has a first base zone (21) and multiple first electrode fingers (23) extending away from the first base zone (21), wherein a first interstice (24) is formed between two directly adjacent first electrode fingers (23) respectively, that the second electrode (20) comprises a second base zone (25) and multiple second electrode fingers (27) extending away from the second base zone (25), wherein a second interstice (28) is formed between two directly adjacent second electrode fingers (27) respectively.

2. Sensor according to claim 1, characterized in that at least one distance element is present on the carrier (16) and / or at the carrier (16) adjacent to the electrodes (18, 20) that defines the distance between the carrier (16) and the cover layer (32).

3. Sensor according to claim 2, characterized in that the at least one distance element is realized by a distance thread (45) that is sewn or embroidered on the carrier (16).

4. Sensor according to any of the preceding claims, characterized in that the sensor (15) comprises a total resistance (RG) between a first connection (22) of first electrode (18) and a second connection (26) of second electrode (20), the amount of which depends on a force (F) acting on the cover layer (32).

5. Sensor according to claim 4, characterized in that the total resistance (RG) depends on a first contact resistance (R1) between the at least one first thread (17) of first electrode (18) and the at least one third thread (33) of cover layer (32) and on a second contact resistance (R2) between the at least one second thread (19) of second electrode (20) and the at least one third thread (33) of cover layer (32).

6. Sensor according to claim 4 or 5, characterized in that the total resistance (RG) depends on a flow resistance (R3) of the at least one third thread (33), the amount of which depends on a force (F) acting on the at least one third thread of cover layer (32).

7. Sensor according to any of the preceding claims, characterized in that at least one second electrode finger (27) extends into a first interstice (24) and that at least one first electrode finger (23) extends into a second interstice (28).

8. Sensor according to any of the preceding claims, characterized in that multiple puncture sites (37) of the embroidered cover layer (32) where the at least one third thread (33) penetrates the carrier (16) are arranged in the first and / or second interstices (24, 28).

9. Sensor according to claim 8, characterized in that the at least one third thread (33) of cover layer (32) comprises multiple bridging stitches (36) that extend over a first electrode finger of the first electrode fingers (23) and a second electrode finger of the second electrode fingers (27) respectively.

10. Sensor according to claim 9, characterized in that some of the bridging stitches (36) that extend over one of the first electrode fingers (23) extend over one of two directly adjacent second electrode fingers (27) and other bridging stitches (36) that extend over this first electrode finger (23) extend over the other of the two directly adjacent second electrode fingers (27).

11. Sensor according to any of the preceding claims, characterized in that the at least one third thread (33) of cover layer (32) extends over the at least one first thread (17) and the at least one second thread (19) at least predominantly at the electrode fingers (23, 27).

12. Sensor according to any of the preceding claims, characterized in that the sensor (15) is configured as potentiometer (46).

13. Sensor according to claim 12, characterized in that the first base zone (21) of the first electrode (18) or the second base zone (25) of the second electrode (20) forms a resistance zone (47) and that the sensor (15) comprises a total resistance (RG) between a first connection (22) of first electrode (18) and a second connection (26) of second electrode (20), wherein the total resistance (RG) changes depending on the location where a force (F) acts on the cover layer (32).