Stitched Sensors

Abstract

The present invention relates to a sensor (15) manufactured by stitching it onto a carrier (16) using threads (17, 19, 33). The stitching forms a first electrode (18), a second electrode (20), and a covering layer (32). The covering layer (32) can be used to create a conductive connection between the first electrode (18) and the second electrode (20) when at least a force (F) acts on the covering layer (32) to press at least a portion of the covering layer (32) against portions of the first electrode (18) and the second electrode (20). This force (F) can be caused by pressure acting locally on the covering layer (32) and / or by bending the covering layer (32) or the carrier (16). The entire sensor (15), particularly the first electrode (18), the second electrode (20), and the covering layer (32), is manufactured by simply stitching it onto a common carrier (16). The sensor can be manufactured in a particularly simple and cost-effective manner and is robust.

Description

[Technical field]

[0001] The present invention relates to a sensor configured to detect and / or measure forces acting on it. The sensor preferably operates piezo-resistively. The sensor can observe or measure effective pressure or bending forces. It is arranged on a flexible carrier, which can in particular be made of, for example, a textile material. For example, woven and / or knitted and / or warp-knitted and / or fleece materials can be used as textile materials. [Background technology]

[0002] US 2016 / 0328043 describes a sensor in which a conductive pattern is stitched onto a flexible carrier. The sensor is configured as a capacitive sensor. In one embodiment, the conductive pattern includes conductive node points. The cover layer includes conductive counter contacts. Between the cover layer and the carrier, adjacent to the conductive nodes and counter contacts, there is an intermediate layer that separates the nodes from the opposite counter contacts unless a force is applied to the cover layer. During compression of the cover layer, the counter contacts can contact the nodes and provide an electrical connection. With such a configuration, for example, a keyboard can be formed.

[0003] US 9816799 discloses a deformation sensor with a conductive element applied on or integrated into a textile carrier. The deformation of the textile carrier can be recognized because the distance between the sections of the conductive element changes. The conductive elements can be arranged, for example, in a meandering shape. Alternatively, two conductive elements can be provided in an interdigital arrangement.

[0004] US 2017 / 0261388 A1 describes a pressure sensor with interdigitated electrodes printed on a carrier. Printing of the electrodes is not easily possible on all types of carriers. Depending on the carrier configuration and material, for example in the case of textile carriers, defects may occur during printing of the electrodes due to capillary action.

[0005] US Patent No. 8,701,578 describes clothing in which knitting patterns are applied to establish conductive communication paths to which sensors can be connected.

[0006] US 2016 / 0048235 describes an interactive textile, a woven fabric with conductive yarns, which is proposed to be constructed in multiple layers to form a capacitive pressure sensor.

[0007] US Patent No. 7,770,473 discloses a pressure sensor made from a multi-layer yarn having conductive fibers and a pressure-sensitive layer. Such a multi-layer yarn can be introduced into a knitted fabric as a filler yarn, whereby the pressure sensor is formed by the multi-layer yarn itself.

[0008] A method for producing conductive threads is known from US Patent No. 8,505,474, whereby metal fibers are coated with non-conductive filaments.

[0009] Another known principle for manufacturing sensors is to form a sandwich structure of a number of separate layers, such sensors are known for example from US 7,145,432 or US 8,661,915 or US 8,904,876.

[0010] Furthermore, US 2004 / 0173028 A1 and DE 102013001772 A1 disclose the possibility of integrating pressure sensors into surfaces within the vehicle.

[0011] Interlink Electronics offers a touch sensor with variable resistance called FFR®. The sensor consists of several polymer layers connected by a laminate. One polymer layer is coated with interdigitated electrodes, the other polymer layer is coated with a special semiconducting material. By applying pressure, the electrodes can be connected in parallel through the semiconducting material.

[0012] Further background information on fibre-based sensors can be obtained from the following specialist literature: - BOSOWSKI, P., et al., "Design and manufacture of textile-based sensors", Electronic Textiles, Elsevier, 2015, p.75-107. - MEYER, Jan; LUKOWICZ, Paul; TROSTER, Gerhard, "Textile pressure sensor for muscle activity and motion detection", Wearable Computers, 10th IEEE International Symposium, p.69-72, 2006. - MEYER, Jan, et al., "Design and modeling of a textile pressure sensor for sitting posture classification", IEEE Sensors Journal 10 (8), p.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, p.29-34. - MECNIKA, V., et al., "Joining technologies for electronic Textiles", Electronic Textiles, Elsevier, 2015, p.133-153. - HASANI, M., et al., "Implementation of a dual-interrogation-mode embroidered RFID-enabled strain sensor", IEEE Antennas and Wireless Propagation Letters 12, p.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, p.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, p.1-9, 2015. - GRIES, Thomas; KLOPP, Kai (Hg.), "Joining and Surface Technologies for Textiles: Methods and Applications", original title:["Fugeund Oberflachentechnologien fur Textilien: Verfahren und Anwendungen"], Springer-Verlag, 2007. Summary of the Invention [Problem to be solved by the invention]

[0013] Starting from the known prior art, the object of the present invention is to provide a sensor for detecting pressure and / or bending forces which can be realized by simple means and in a cost-effective manner.

[0014] This object is solved by a sensor having the features of claim 1. [Means for solving the problem]

[0015] The sensor according to the invention is configured to detect and / or measure the force acting on the sensor. In the simplest case, a digital detection of the applied force can be performed. In one embodiment of the sensor, a sensor value, in particular an electrical sensor value, depending on the amount of applied force can be generated by the sensor. Preferably, the sensor works piezo-resistively for this purpose. For example, the sensor can be used as a pressure sensor or a bending sensor.

[0016] The sensor comprises a carrier. The carrier is preferably made of a flexible material. The carrier is a planar element that is substantially two-dimensionally or two-and-a-half-dimensionally configured. This means that the carrier is a planar element that has a thickness that is at least an order of magnitude smaller than its length and width in the plane in which it extends. For example, a fibrous material such as a woven fabric, knitted fabric, warp-knitted fabric, fleece material, or any combination thereof can be used as the carrier. The carrier or carrier material is preferably of one-layer configuration.

[0017] The first electrode and the second electrode are formed on the carrier by stitching. The electrodes are not only attached to the carrier by stitching, but also formed by threads stitched onto the carrier. The first electrode is formed by stitching at least one first thread onto the carrier, and the second electrode is formed by stitching at least one second thread onto the carrier. The at least one first thread and the at least one second thread include or are composed of a conductive component. Such a component may be a fiber, and / or at least one filament, and / or a filler, and / or a coating. The at least one first thread and the at least one second thread may be configured as a thread or a twisted thread. For better stitchability, twisted threads are preferred.

[0018] The two electrodes are arranged at a distance from each other on the carrier such that at least one first thread and at least one second thread are not arranged on the carrier in direct contact with each other. The electrodes formed by stitching are preferably arranged on a common surface of the carrier, preferably directly on each surface of the carrier in a common layer. Depending on whether the carrier is oriented in a plane, curved or bent, the first electrode and / or the second electrode may extend planarly, curved or bent along the surface of the carrier.

[0019] The stitched sensor further comprises a covering layer formed by at least one third thread stitched onto the carrier. As in the case of the electrode, the covering layer is not constructed as a separate element attached by stitching onto the carrier, but is formed by stitching with at least one third thread. The at least one third thread comprises a conductive component. The at least one third thread can be formed by a thread or preferably a twisted thread. At a plurality of contact sites, the at least one third thread is in contact with at least one first thread of the first electrode and at least one second thread of the second electrode. Preferably, at least one first or second thread portion is arranged at each of the contact sites between the at least one third thread portion and the carrier.

[0020] Depending on the force acting on the coating layer, which may be caused by pressure or bending, the electrical conductivity between the first and second electrodes of the sensor changes, so that the applied force can be recognized and / or measured.

[0021] Thus, the entire sensor can be produced by stitching. Stitching is a method that can be carried out without costly production means, using sewing or stitching machines. By stitching threads onto the carrier, the two electrodes and the covering layer are formed and the sensor is produced. The electrodes and covering layer produced by stitching can be applied to various carrier materials, even those that are not suitable for printing due to their capillary action. The production of several sensor plies or layers and the subsequent connection of the sensor plies or layers is not necessary. The sensor can be produced in a continuous process in one sewing or stitching machine. It is only potentially advantageous to use different threads for stitching the electrodes and the covering layer. With a stitching machine with several heads, such a change of threads can be carried out very quickly and simply.

[0022] Preferably, at least not all the yarns, in particular at least one first yarn for forming the first electrode and at least one second yarn for forming the second electrode, have their own sensor properties: according to the invention, the sensor function is realized by cooperation of the electrode yarn and the covering layer, and not by one of the yarns.

[0023] Preferably, the at least one third thread has a conductivity different from that of the at least one first thread and / or the at least one second thread. In particular, the at least one third thread has a lower conductivity than that 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 may have equal conductivity, in particular may be identical.

[0024] At least one first thread and / or at least one second thread and / or at least one third thread can include conductive fibers and / or conductive fillers and / or at least one conductive filament and / or a conductive coating. The conductive material for the fibers, fillers or filaments or coating can be silver, stainless steel, carbon, carbon black, other known materials, or combinations thereof.

[0025] In one embodiment, the sensor comprises a total resistance between the first connection of the first electrode and the second connection of the second electrode, the amount of which depends on the force acting on the covering layer. This force can be caused by pressure or bending of the carrier or the sensor. The total resistance can thus depend on a first contact resistance between at least one first thread of the first electrode and at least one third thread of the covering layer, and a second contact resistance between at least one second thread of the second electrode and at least one third thread of the covering layer. Furthermore, the total resistance can also depend on the flow resistance of the at least one third thread, the amount of which can depend on the applied force and the resulting deformation of the at least one third thread. The total resistance can thus be defined by at least one series connection of the first contact resistance, the second contact resistance, and the potentially variable flow resistance. Also, multiple such series connections can be connected in parallel to define the total resistance between the first connection and the second connection. For example, this depends on how large the area where the force is applied is and how many contact locations are affected by the application of the force.

[0026] In a preferred embodiment, the first electrode has a first base zone and a number of first electrode fingers projecting from the first base zone, with a first gap being formed between each two directly adjacent first electrode fingers. Similarly, the second electrode can have a second base zone and a number of second electrode fingers projecting from the second base zone, with a second gap being formed between each two directly adjacent second electrode fingers.

[0027] In one embodiment, multiple first threads can be used to stitch the first electrode and multiple second threads can be used to stitch the second electrode. In doing so, different regions of the first electrode or the second electrode can be manufactured or stitched from different materials. For example, the base zone can be stitched from a different thread material than the electrode fingers of the first electrode and / or the second electrode. For example, this configuration can be particularly advantageous when the sensor is configured as a type of potentiometer.

[0028] The first electrode fingers are preferably oriented parallel to one another. The second electrode fingers are preferably oriented parallel to one another. It is further advantageous if the first electrode finger and the second electrode finger extend parallel to one another. Thereby, at least one second electrode finger can extend into the first gap and at least one first electrode finger can extend into the second gap. In a manner of speaking, a comb-shaped arrangement of the two electrodes is realized. Preferably, the distance between the first electrode finger and the respective adjacent second electrode finger is equal. It is advantageous if the electrode fingers are arranged at a uniform distance.

[0029] Instead of an interdigitated arrangement of electrodes, the electrodes can have other shapes. For example, the electrode fingers and / or the base zone can include at least one curved section and / or at least one bent section. The base zone can be linear (the width is less than the length, e.g., at least about 1 / 5 to 1 / 10) or can surround or fill an area (e.g., a circular or polygonal area).

[0030] In one embodiment, the first electrode and the second electrode can extend substantially parallel to each other, at least in the region where the covering layer covers the two electrodes. In this region, the two electrodes can be arranged adjacent to each other at a substantially constant distance. The electrodes can include one or more curves and / or bends and / or corners in this region. For example, the two electrodes can extend in a meandering manner, at least in this region. There can also be a plurality of such regions arranged spatially separated from each other on the carrier. In this one or more regions, each electrode can extend without branching. Between each two of such regions, there can be branching regions. One or more of such regions can form, for example, shapes, symbols, letters, etc.

[0031] In such a configuration, portions of the first and / or second electrodes may be immediately adjacent and extend parallel to one another, whereas in an interdigitated arrangement, the electrode fingers of different electrodes are preferably arranged immediately adjacent to each other.

[0032] At least some of the first and second gaps are preferably dimensioned such that sufficient space remains for puncture sites of at least one third thread of the covering layer. The puncture sites of the stitched covering layer, where at least one third thread penetrates the carrier, are preferably located in the first or second gaps adjacent to the electrode fingers. The puncture sites of the at least one third thread do not penetrate at least one first thread of the first electrode and at least one second thread of the second electrode.

[0033] At least one third yarn of the cover layer includes a plurality of stitches each having at least one contact area that may be referred to as bridging stitches, each bridging stitch preferably having at least one contact area to the first yarn and at least one contact area to the second yarn.

[0034] In one embodiment, each of the bridging stitches can extend across one of the first electrode fingers and one of the second electrode fingers, respectively. Preferably, a bridging stitch extends across exactly one first electrode finger and exactly one second electrode finger. A bridging stitch extends between two perforation sites located on opposite sides of an underlying electrode finger.

[0035] In one embodiment, the bridging stitches extending over one particular or considered first electrode finger only extend over one of the second electrode fingers arranged directly adjacent to each other. In this way, a group of bridging stitches can be formed, the perforations of which are arranged on two lines extending parallel to each other, these lines being oriented parallel to the associated first electrode finger and the associated second electrode finger. In an alternative embodiment, contact with two directly adjacent second electrode fingers is established via bridging stitches extending over one particular or considered first electrode finger. For this, a part of these bridging stitches extends over the first electrode finger and one of the second electrode fingers, and a part of the other bridging stitch extends over the first electrode finger and the other second electrode finger. The bridging stitches are arranged offset from each other in a direction perpendicular to the extension direction of the electrode fingers and overlap in the area where the first electrode fingers extend.

[0036] The bridging stitch arrangement which has been described in relation to one first electrode finger under consideration may also be provided accordingly for the second electrode finger under consideration.

[0037] Furthermore, it is preferred that the at least one third thread of the cover layer extends over the at least one third thread and the at least one second thread only in the electrode fingers, and thus the third thread does not extend over the first and second electrodes in the region of the first base zone or the second base zone.

[0038] In an embodiment, the sensor can be configured as a variable resistor. It is thereby particularly advantageous if the first base zone of the first electrode or the second base zone of the second electrode form the resistive zone. The resistance along the resistive zone can increase in the direction of extension of the resistive zone away from the respective connection of the electrodes. The resistance between the electrode fingers and the connection can be higher the further the electrode fingers are from the respective connection, since the resistance of the resistive zone increases. In this way, 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 position at which a conductive or better conductive connection is established between the two electrodes by the application of a force.

[0039] In all embodiments, in addition to the first and second electrodes, at least one distance element can be provided on the carrier, which is arranged between the carrier and the covering layer. The distance element is arranged on the carrier adjacent to the first and second electrodes (e.g. between the two electrodes). By the at least one distance element, the distance between the covering layer and the carrier or between the covering layer and the first and second electrodes can be defined relative to an initial state in which no external forces act on the covering layer. By the at least one distance element, for example, a content between the covering layer and the first and / or second electrode in the initial state can be prevented or reduced.

[0040] In a preferred embodiment, the at least one distance element can be formed by at least one distance thread, which can be sewn or stitched onto the carrier.

[0041] The distance thread is arranged at least in the area between or adjacent to the electrodes where the covering layer is present. The distance thread is arranged between the covering layer and the carrier. The distance thread can be arranged, for example, in the at least one first gap and / or in the at least one second gap. The distance thread is preferably electrically non-conductive. The thickness or strength of the distance thread is preferably greater than the thickness or strength of the at least one first thread and the at least one second thread. By the distance thread, the contact between the at least one third thread and the at least one second thread or the contact between the at least one third thread and the at least one first thread can be reduced in the initial state without applying a force to the sensor.

[0042] One or more of the above embodiments of the invention result in a sensor with a very flat configuration. The sensor is manufactured using a low amount of material and generates very little waste during manufacture. The measurement range and / or measurement sensitivity can be defined by one or more of the following characteristics:

[0043] - selection of the yarns or strands to be used for the first and / or second and / or third yarns; - Arrangement of bridge stitches for electrodes and / or covering layers -Placement of bridge stitches on the covering layer -Integration of additional distance threads

[0044] The sensor according to the invention can also be manufactured together with one or more additional stitched sensors (e.g. together with further sensors according to the invention or with a humidity sensor) in a common process on a sewing or stitching machine. The sensor according to the invention can also be combined during stitching with other stitched electrical functional areas, such as supply lines and / or heating devices.

[0045] Advantageous embodiments of the invention emerge from the dependent claims, the description and the drawing. Preferred embodiments of the invention are explained in detail below on the basis of the drawings, in which: [Brief description of the drawings]

[0046] [Figure 1] FIG. 1 is a schematic diagram showing a carrier, a first electrode formed by a first yarn, and a second electrode formed by a second yarn. [Diagram 2] FIG. 2 is a schematic illustration of a sensor having the carrier and electrodes of FIG. 1 and a third yarn covering layer in contact with the first and second electrodes. [Diagram 3] FIG. 3 is a schematic diagram of a further embodiment of the sensor according to FIG. 2, in which the stitches of the cover layer are arranged differently than in the embodiment according to FIG. [Figure 4] FIG. 4 is a schematic diagram of a further embodiment of the sensor according to FIG. 2, in which the stitches of the cover layer are arranged differently than in the embodiment according to FIG. [Diagram 5] FIG. 5 is a schematic basic illustration of a bridging stitch of a first thread of a first electrode and a third thread of a cover layer extending over a second thread of a second electrode. [Figure 6] FIG. 6 is an illustration of FIG. 5 during application of pressure to the third yarn. [Figure 7] FIG. 7 shows an electrical equivalent circuit of the total resistance of the bridging stitches of at least one third yarn as a function of applied force. [Figure 8] FIG. 8 is a schematic illustration of a carrier having a first electrode and a second electrode stitched thereto, with a distance thread stitched or sewn onto the carrier between the two electrodes. [Figure 9] FIG. 9 is a schematic basic illustration of a bridging stitch of a third thread, a first thread, a second thread and a distance thread in the embodiment according to FIG. [Figure 10] FIG. 10 is a basic schematic diagram of a variable resistor formed by a sensor. [Figure 11] FIG. 11 is an equivalent circuit of the variable resistor shown in FIG. [Figure 12] FIG. 12 is a schematic diagram showing a carrier of a first electrode formed by a first yarn and a second electrode formed by a second yarn. [Figure 13] FIG. 13 is a schematic illustration of a further embodiment of a sensor having the carrier and electrodes of FIG. 12 and a third yarn covering layer in contact with the first electrode and the second electrode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0047] The present invention relates to a sensor 15 that can be manufactured by stitching. In Figures 2-4, 8 and 10, various embodiments of the sensor 15 are shown, respectively, in schematic form. The sensor 15 is configured to detect or measure a force F (Figure 6) acting on the sensor 15. This can detect or determine only the presence or absence of an applied external force, or, optionally, generate a sensor value that depends on the amount of force applied and / or the location at which the force F is applied.

[0048] The sensor 15 can be described as a stitched sensor 15. It comprises a carrier 16, which is preferably configured as a textile carrier 16. The carrier 16 is generally a two-dimensional structure, so that in its extension plane, the carrier 16 has a length and a width which are about one or several orders of magnitude greater than the thickness of the carrier 16 perpendicular to its extension plane. The carrier 16 can be made of plastic and / or natural materials. Preferably, the carrier 16 is configured as a textile carrier, for example as a knitted fabric and / or a warp knitted fabric and / or a woven fabric and / or a fleece material. The carrier 16 can also be part of a garment or other textile surface.

[0049] By using at least one first thread 17, a first electrode 18 is produced by stitching on the carrier 16. In the figure, the individual stitches made by the first thread 17 on the carrier 16 are shown diagrammatically as viewed from one side of the carrier 16. The at least one first thread 17 includes a conductive component, such as a conductive fiber, filament or filler. The conductive material can be silver, stainless steel, carbon, or a combination thereof. The at least one first thread 17 can also include a conductive coating.

[0050] By using at least one second thread 19, a second electrode 20 is produced by stitching on the carrier 16, according to an embodiment, on the same side of the carrier 16. The at least one second thread 19 includes a conductive component and can be configured as described above with respect to the first thread 17. The at least one first thread 17 and the at least one second thread 19 preferably have equal electrical conductivity and can be identical.

[0051] As shown in particular in FIG. 1, the first electrode 18 and the second electrode 20 are arranged in an interdigital manner in some embodiments (FIGS. 1 to 4, 8, 10). For this, the first electrode 18 comprises a first base zone 21, which extends away from the first connection 22, for example in a linear manner. A plurality of first electrode fingers 23 project in a cross direction, preferably perpendicular to the first base zone 21. The first electrode fingers 23 are arranged parallel to one another and equally spaced apart. Between two directly adjacent first electrode fingers 23, a first gap 24 is formed. The number of first electrode fingers 23 and thus the number of first gaps 24 can be varied depending on the realised dimensions of the sensor. Also the length of the base zone 21 or the length of the first electrode fingers 23 can be varied. In the present embodiment, all first electrode fingers 23 have the same length.

[0052] The second electrode, which is produced from at least one second thread 19, is constructed similarly to the first electrode 18. The second electrode comprises a second base zone 25, which extends away from the second connection 26, for example in a linear fashion. The first base zone 21 and the second base zone 25 preferably extend parallel to each other and are arranged at a distance from each other. A plurality of second electrode fingers 27 protrude from the second base zone 25 in a cross direction, preferably in a perpendicular direction. The second electrode fingers 27 are parallel to each other and, in the present embodiment, are arranged at equal intervals from each other. The second electrode fingers 27 preferably have equal lengths. Between two directly adjacent second electrode fingers, a second gap 28 is respectively formed.

[0053] Threads of different materials may be used for the stitching of the base zones 21, 25 and for the stitching of the electrode fingers 23, 27. For example, the first electrode 18 may be stitched from two different (particularly of different conductivity) first threads and the second electrode 20 may be stitched from two different (particularly of different conductivity) second threads.

[0054] In this embodiment, the first electrode finger 23 and the second electrode finger 27 are arranged parallel to each other. In one, several or all of the first gaps 24, at least one, and according to this embodiment exactly one, second electrode finger 27 extends. In one, several or all of the second gaps 28, at least one, and according to this embodiment exactly one, first electrode finger 23 extends. Thus, the first electrode finger 23 and the second electrode finger 27 are always arranged alternately in a direction parallel to the extension line of the first base zone 21 and the second base zone 25.

[0055] Between the first electrode 18 and the second electrode 20, a distance is provided such that at least one first thread 17 and at least one second thread 19 are not in direct contact with each other. In this embodiment, a first distance a is provided between each first electrode finger 23 and the directly adjacent second electrode finger 27 in a direction parallel to the extension direction of the base zones 21, 25. A second distance b is provided between the free end of the first electrode finger 23 and the second base zone 25 in a direction parallel to the extension direction of the electrode fingers 23, 27. The same second distance b can thus be provided towards the free end of the second electrode finger 27. In an embodiment, the first distance a and the second distance b have equal amounts.

[0056] As already explained, there is no direct contact and no direct conductive connection between the first electrode 18 and the second electrode 20. The carrier 16, at least in the region on which the electrodes 18, 20 are disposed, is non-conductive or is not configured to establish an indirect electrical contact between the at least two electrodes.

[0057] An indirect contact and an indirect conductive connection between the first electrode 18 and the second electrode 20 can be established via a covering layer 32. The covering layer 32 is formed by stitching at least one third thread 33 onto the carrier 16. As with the at least one first thread and the at least one second thread, the at least one third thread can comprise a conductive component and have a configuration as initially described in relation to the first thread 17. The at least one third thread 33 is preferably 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. According to this embodiment, the electrical conductivity of the at least one third thread 33 is lower than the electrical conductivity of the first thread 17 and the second thread 19 in a state where no external force is applied to the at least one third thread 33. In one embodiment, the at least one third yarn 33 has conductive components such as fillers and / or fibers and / or filaments, and the distance between the components is changed by an external influence, thereby changing, preferably increasing, the electrical conductivity of the at least one third yarn 33.

[0058] The at least one third thread 33 extends over the first electrode 18 and the second electrode 20 at a plurality of locations, thus forming a plurality of first contact sites 34 with the at least one first thread 17 and a plurality of second contact sites 35 with the at least one second thread 19. Each of the first contact sites 34 has a first contact resistance R1 between the first thread 17 and the third thread 33. Each of the second contact sites 35 has a second contact resistance R2 between the second thread 19 and the third thread 33. The at least one third thread 33 may have a variable flow resistance R3.

[0059] As shown diagrammatically on the basis of Figs. 5-7, 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 such that the first contact resistance R1 and the second contact resistance R2 are lower when a force F is applied on the covering layer 32. Optionally, the flow resistance R3 of the third thread 33 can be further reduced by the application of the force. For example, the conductive components of the third thread 33 establish an improved electrical connection between each other along the extension direction of the third thread 33 by the applied force F, thereby increasing the electrical conductivity of the third thread 33 or reducing the flow resistance R of the third thread 33 between the first contact site 34 and the directly adjacent second contact site 35.

[0060] As shown diagrammatically in Figures 2 to 4, at least one third thread 33 of the covering layer 32 is stitched on the carrier 16 to form a plurality of stitches, which may be denoted as bridging stitches 36. The bridging stitches 36 comprise in each case a first contact site 34 and a second contact site 35 and in the embodiment extend respectively over a first electrode finger 23 and a directly adjacent second electrode finger 27. It is preferred if each of the bridging stitches 36 extends over exactly one first electrode finger 23 and exactly one second electrode finger 27. In that way, the bridging stitch 36 can be kept very short between its two perforation sites 37.

[0061] A bridging stitch 36 between two perforation sites 37 is shown diagrammatically in Fig. 5 and Fig. 6. Figs. 2 to 4 show various stitch patterns that can be used to arrange the bridging stitches 36 of the cover layer 32. In the embodiment shown in Fig. 2, exactly one second electrode finger 27 is assigned to each first electrode finger 23 forming a common electrode finger pair. The electrode finger pairs 23, 27 are bridged by one bridging stitch group of bridging stitches 36. There are no bridging stitches 36 connecting the electrode fingers of different electrode finger pairs to each other. For example, the bridging stitches 36 assigned to the common electrode finger pair 23, 27 are arranged such that the perforation sites 37 are oriented along two parallel lines, which run parallel to the electrode fingers 23, 27 of the electrode finger pair. In this way, the bridging stitches 36 form one bridging stitch group for each electrode finger pair, and the bridging stitch groups do not overlap in a direction parallel to the extension direction of the base zones 21, 25, but are adjacent to each other in contact with each other or adjacent to each other at a distance.

[0062] An alternative embodiment is shown in figures 3 and 4. The bridging stitches 36 are arranged offset from one another parallel to the extension direction of the base zones 21, 25. With this offset arrangement, the first electrode finger 23 extending into the second gap 28 is connected to one directly adjacent second electrode finger 27 by a number of bridging stitches 36 and to each other directly adjacent second electrode finger 27 by a number of other bridging stitches 36. In this way, the electrical connection between the first electrode 18 and the second electrode 20 via the covering layer 32 can be improved, at least during the application of a force.

[0063] The stitch density of the bridging stitches 36 can vary.

[0064] The difference between the embodiment according to Figure 3 and the embodiment according to Figure 4 is that in the embodiment according to Figure 3 the bridging stitches 36 arranged in a row or line perpendicular to the extension direction of the base zones 21, 25 are adjacent to each other with substantially no distance between them, whereas in the embodiment according to Figure 4 the bridging stitches 36 are spaced apart from each other in a direction perpendicular to the extension direction of the base zones 21, 25.

[0065] Except for the placement of the bridging stitches 36, the embodiments according to FIGS. 2 and 4 are constructed identically.

[0066] In the preferred embodiment illustrated in the present disclosure, each of the bridging stitches 36 includes at least one perforation site 37 located in the first gap 24 and the second gap 28. All perforation sites 37 are disposed adjacent to a respective electrode finger 23, 27 and are not penetrated by either the at least one first thread 17 or the at least one second thread 19.

[0067] In some embodiments (FIGS. 1 to 4, 8 and 10), the covering layer 32 is limited to the region between the first base zone 21 and the second base zone 25 in the extension direction of the electrode fingers 23, 27. Preferably, the third thread 33 does not extend onto the first base zone 21 or onto the second base zone 25. The first contact site 34 and the second contact site 35 are only present in those electrode fingers 23 or 27 where at least one third thread 33 extends onto the electrode 18, 20.

[0068] In Fig. 7 the electrical equivalent circuit of the resistance between the first thread 17 and the second thread 19 is shown diagrammatically. They are connected to each other by exactly one first contact site 34 and exactly one second contact site 35 via one single bridging stitch 36. This resistance is formed by a series circuit of a first contact resistance R1, a flow resistance R3 and a second contact resistance R2. However, the amount of all the individual resistances R1, R3, R2 of this series connection, at least the amount of the two contact resistances R1, R2, is variable depending on the applied force F.

[0069] As shown diagrammatically in FIG. 6, the application of force F can be produced, for example, by pressing the covering layer 32 with the tip of a finger 38. In this way, the force F does not act on one single bridging stitch 36 of the covering layer 32, but on multiple bridging stitches 36. In this way, as shown diagrammatically in FIG. 7, multiple series connections of the first contact resistance R1, the flow resistance R3 and the second contact resistance R2 are connected in parallel by acting on multiple bridging stitches 36. A total resistance RG between the first connection 22 and the second connection 26 is then obtained by the parallel connection of multiple series connections, one of which is shown diagrammatically in FIG. 7.

[0070] Also, according to FIG. 7, when a conductive connection is already established between the two electrodes 18, 20 via the coating layer 32 without applying an external force F, the total resistance RG is formed by a plurality of series connections 39 connected in parallel, which can be modified, in particular reduced, by applying a force F.

[0071] If a conductive connection between the two connection parts 22, 26 has already been established without the application of an external force F, the interruption-free condition of the electrical connection can also be confirmed without the application of an external force F.

[0072] In figures 12 and 13 a further example of an embodiment of the sensor 15 is shown, in which in figure 12 the covering layer 32 has been omitted for improved clarity and only the electrodes 18, 20 are shown. The two electrodes 18, 20 extend at a distance substantially parallel to each other, in a meandering line or meandering manner, at least in the region where the covering layer 32 is applied on the carrier. According to this example, this meandering extension is arranged between two parallel extensions of the first electrode 18 to a substantially parallel extension of the second electrode 20. The exact extension and shape of the electrodes 18, 20 can be varied and can for example form letters, numbers or symbols. The bridging stitches 36 of the covering layer 32 extend along their extensions over the first electrode 18 and the second electrode 20, respectively. In figure 13 a covering layer 32 with a low density of bridging stitches 36 is shown diagrammatically to illustrate the principle of the sensor construction. The density of the bridging stitches 36 can also be higher.

[0073] The perforations of the bridging stitches 36 of the covering layer 32 are arranged adjacent to or between two parts of the same electrode 18 or 20 in the embodiment shown in Fig. 13. Depending on the shape of the extension of the electrodes 18, 20, sufficient space can be provided for a higher or lower stitch density of the bridging stitches 36. The distance between the perforations of the bridging stitches 36 is preferably as short as possible to make optimal use of the surface. However, the perforations of the bridging stitches 36 must not damage or unintentionally short-circuit the electrodes 18, 20 arranged underneath them.

[0074] Due to the serpentine shape of the electrodes 18, 20, there is the possibility of providing a covering layer 32 over the entire area covered by the electrodes 18, 20 and using it as a pressure-sensitive surface. The number of bridges per unit area is less than in the comb-shaped arrangement described above, as shown, for example, in Figures 1 to 4.

[0075] Another possible configuration of the sensor 15 is shown diagrammatically in Fig. 8 and Fig. 9, which can be combined with all the embodiments of the sensor 15. In this embodiment, a distance thread 45 is stitched to the carrier 16. The distance thread 45 is arranged on the same side or in the same plane of the carrier 16 as the first electrode 18 and the second electrode 20. The strength or diameter of the distance thread 45 is greater than the strength or diameter of the at least one first thread 17 and the at least one second thread 19. The distance thread 45 is stitched on the carrier 16 at least in the position where the covering layer 32 is arranged. Preferably, each of the bridging stitches 36 of the covering layer 32 extends over a portion of the distance thread 45. Even without applying an external force, the maximum distance of the third thread 33 of the bridging stitch 36 to the carrier 16 is increased compared to the variation without the distance 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 thereby be increased in such a way that no measurable current occurs between the first connection portion 22 and the second connection portion 26 for the voltages and currents normally used in the sensor, and the first contact resistance R1 and / or the second contact resistance R2 can be made infinitely high, so to speak, provided that at the contact sites 34, 35 there is a distance between the third thread 33 and the first thread 17 or the second thread 19 in the absence of any external force.

[0076] It should be understood that when multiple threads are used in the stitches of the electrodes 18, 20 forming a thread bundle, at least one distance thread 45 or a distance thread bundle of multiple distance threads 45 is used, the total thickness of which is greater than the total thickness of the fiber bundle of the first thread 17 or the second thread 19.

[0077] By means of stitching techniques, the sensor 15 can also be manufactured forming a potentiometer 46 (FIG. 10). In the potentiometer 46, at least one base zone, according to this embodiment the first base zone 21, is configured as a resistive zone 47. The resistive zone 47 has a lower electrical conductivity than the remaining part of the first electrode 18. This can be achieved, for example, in that the resistive zone 47 is stitched from a thread having a lower electrical conductivity than the thread used to stitch the first electrode finger 23. Opposite the first connection 22, a third connection 48 is electrically connected with the resistive zone 47. Between the first connection 22 and the third connection 48, the maximum resistance of the potentiometer is therefore formed by the resistive zone 47.

[0078] As described in relation to the first base zone 21, the first electrode fingers 23 extend from the resistive zone 47 at different positions. The second electrode 20 is constructed similarly to the embodiments described above.

[0079] When a force F is applied on the covering layer 32 at the application position 49, an electrical coupling is generated between at least one first electrode finger 23 and at least one second electrode finger 27. Depending on where the application position 49 is located in the extension direction E of the resistive zone 47, a variable total resistance RG between the first connection portion 22 and the second connection portion 26 changes. In FIG. 11, an equivalent circuit of the variable resistor 46 of FIG. 10 is shown diagrammatically. The total resistance RG is substantially formed by the part of the resistive zone 47 extending between the application position 49 and the first connection portion 22.

[0080] If a first voltage U1 is applied between the first connection 22 and the third connection 48, a second voltage U2, which depends on the position of the application position 49 in the extension direction E, can be measured between the second connection 26 and the third connection 48. Thereby, the following formula applies:

[0081]

number

[0082] The invention relates to a sensor 15 which is produced by stitching with threads 17, 19, 33 on a carrier 16. By stitching, a first electrode 18, a second electrode 20 and a covering layer 32 are formed. A conductive connection can be established between the first electrode 18 and the second electrode 20 when at least a force F acts on the covering layer 32 via the covering layer 32, pressing at least a part of the covering layer 32 against parts of the first electrode 18 and the second electrode 20. This force F can be generated by a pressure applied locally on the covering layer 32 and / or by bending the covering layer 32 or the carrier 16. The entire sensor 15, in particular the first electrode 18, the second electrode 20 and the covering layer 32, are produced exclusively by stitching on a common carrier 16. This sensor can be produced in a particularly simple and inexpensive way and is robust.

[0083] The present invention also allows for a sensor 20 to be obtained that is very planar in construction. The amount of material used for the manufacture of the sensor 15 is low and only little waste is generated during manufacture. The measurement range and the measurement sensitivity of the sensor 15 can be selected by the choice of the threads or strands used as the first and / or second and / or third threads. The measurement range and the measurement sensitivity can be varied due to the arrangement of the electrodes 18, 20 and / or the bridging stitches 36 of the covering layer 32. Instead of the comb-shaped arrangement of the electrodes 18, 20 illustrated by this embodiment, any other shape for forming the electrodes 18, 20 is also possible. For example, the electrode fingers 23, 27 can also have at least one curved and / or bent portion. The base zones 21, 25 do not necessarily have to extend along a straight line but can also include at least one curved and / or at least one bent portion. The base zones 21, 25 can also surround or cover an area, for example a circular or polygonal area. The sensor of the present invention can also be manufactured together with one or more additional stitched sensors (e.g. together with another sensor according to the present invention or with a humidity sensor) in a common process on a sewing or stitching machine. The sensor of the present invention can also be combined with other stitched electrical functional areas, such as supply lines and / or heating devices, during stitching. [Explanation of symbols]

[0084] 15 Sensors 16 Carriers 17 The First Thread 18 First electrode 19 The Second Thread 20 Second electrode 21 First base zone 22 First connection 23 First electrode finger 24 The First Gap 25 Second base zone 26 Second Connection 27 Second electrode finger 28 The Second Gap 32 Covering layer 33 The Third Thread 34 First Contact Site 35 Secondary Contact Site 36 Bridge stitch 37 Perforation site 38 fingers 39 Series Connection 45 Distance Thread 46 Variable resistor 47 Resistance Zone 48 Third Connection a First distance b Second distance E Extension direction of the resistance zone F force R1 First contact resistance R2 Second contact resistance R3 Flow resistance RG Total Resistance Rmax Maximum resistance of the variable resistor

Claims

1. A sensor (15) configured to detect and / or measure a force (F) applied to the sensor (15), The sensor (15) is a resistive sensor operated by a resistor, the entire sensor (15) being manufactured by stitching, A support (16); a first electrode (18) formed by at least one first thread (17) stitched onto said carrier (16) and including a conductive component; a second electrode (20) formed by at least one second thread (19) stitched onto said carrier (16) and including a conductive component, the two electrodes (18, 20) being arranged at a distance on said carrier (16); a covering layer (32) formed by at least one third thread (33) stitched onto the carrier (16) and including a conductive component, the at least one third thread (33) of the covering layer (32) being adjacent to the at least one first thread (17) of the first electrode (18) and the at least one second thread (19) of the second electrode (20) at a plurality of contact sites (34, 35); A sensor (15) comprising:

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

3. 3. The sensor according to claim 2, characterized in that the at least one distance element is realised by a distance thread (45) which is sewn or stitched onto the carrier (16).

4. 4. The sensor according to claim 1, wherein the sensor (15) comprises a total resistance (RG) between the first connection (22) of the first electrode (18) and the second connection (26) of the second electrode (20), the amount of the total resistance (RG) being dependent on a force (F) acting on the coating layer (32).

5. 5. The 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 a first electrode (18) and the at least one third thread (33) of a covering layer (32) and a second contact resistance (R2) between the at least one second thread (19) of a second electrode (20) and the at least one third thread (33) of a covering layer (32).

6. 6. The 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 the flow resistance (R3) depending on a force (F) acting on the at least one third thread of the covering layer (32).

7. 7. The sensor according to claim 1, wherein the first electrode (18) and the second electrode (20) extend parallel to each other at a predetermined distance adjacent to each other in at least one region.

8. The first electrode (18) has a first base zone (21) and a plurality of first electrode fingers (23) extending away from the first base zone (21), with a first gap (24) being formed between each two directly adjacent first electrode fingers (23); The second electrode (20) has a second base zone (25) and a plurality of second electrode fingers (27) extending away from the second base zone (25), and two directly adjacent second 7. The sensor according to claim 1, wherein second gaps (28) are formed between the electrode fingers (27).

9. 9. The sensor according to claim 8, characterized in that at least one second electrode finger (27) extends into the first gap (24) and at least one first electrode finger (23) extends into the second gap (28).

10. 10. The sensor according to claim 8 or claim 9, characterized in that a plurality of perforation sites (37) of the stitched covering layer (32), through which the at least one third thread (33) penetrates the carrier (16), are arranged in the first gap (24) and / or the second gap (28).

11. 11. The sensor according to claim 10, characterized in that the at least one third thread (33) of the covering layer (32) comprises a plurality of bridging stitches (36) each extending over a first electrode finger of the first electrode fingers (23) and a second electrode finger of the second electrode fingers (27).

12. a part of the bridging stitch (36) that extends over one of the first electrode fingers (23) also extends over one of the two immediately adjacent second electrode fingers (27); 12. The sensor according to claim 11, characterized in that the other bridging stitch (36) extending over the one first electrode finger (23) extends over the other of the two directly adjacent second electrode fingers (27).

13. 13. The sensor according to claim 8, wherein the at least one third thread (33) of the covering layer (32) extends over the at least one first thread (17) and the at least one second thread (19), at least mainly in the first and second electrode fingers (23, 27).

14. The sensor according to any one of the preceding claims, characterized in that the sensor (15) is configured as a variable resistor (46).

15. 15. The sensor according to claim 8, wherein the first base zone (21) of the first electrode (18) or the second base zone (25) of the second electrode (20) forms a resistive zone (47), and the sensor (15) comprises a total resistance (RG) between the first connection (22) of the first electrode (18) and the second connection (26) of the second electrode (20), the total resistance (RG) varying depending on the position at which a force (F) acts on the coating layer (32).

16. A sensor as described in claim 1, wherein the first electrode (18) and the second electrode (20) are arranged on a common surface of the carrier (16) and each are formed by stitching.

17. The sensor of claim 1, wherein the third thread (33) of the coating layer (32) includes a plurality of bridging stitches (36) having a contact portion (34) to the at least one first thread (17) and a contact portion (35) to the at least one second thread (19).

18. A sensor as described in claim 17, wherein the first thread (17) and the second thread (19) are arranged adjacent to each other between the carrier (16) and the third thread (33) of the bridging stitch (36).

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