Flat pressure sensor unit

Abstract

The invention relates to a flat pressure sensor unit, in particular a pressure sensor sheet (3), comprising first conductor paths (310) and second conductor paths (32) and a central layer (33) arranged between the first and the second conductor paths (310, 320). The first and second conductor paths (310, 320) cross one another, spaced apart by the central layer (33), whereby cross-over points (30) are formed in order to detect, as sensors, a spacing change between the first and second conductor paths (310, 320) generated by an external application of pressure. The conductor paths (310, 320) are sewn onto at least one material layer (31, 32). First and second connecting paths (390, 391) are provided, leading away from the first and second conductor paths (310, 320), extending towards at least one electronics unit (380, 381) and ending at the at least one electronics unit (380, 381). The first and second conductor paths (390, 391) are sewn on the at least one material layer (31, 32). The flat pressure sensor unit can be easily and economically produced and allows for flexible design both in the selection of the material layers (31, 32) and in the arrangement of the conducting and connecting paths (310, 320, 390, 391).

Description

[0001] TITLE

[0002] PLANAR PRESSURE SENSOR UNIT

[0003] TECHNICAL FIELD

[0004] The present invention relates to a flat pressure sensor unit, in particular a pressure sensor sheet, in particular a textile pressure sensor sheet, and a method for producing such a pressure sensor unit.

[0005] STATE OF THE ART

[0006] Optimal patient monitoring is a growing problem, particularly due to understaffing in the nursing field. Technical solutions can help address this issue and ensure greater safety and less burden on patient care.

[0007] Furthermore, solutions are being sought in the private sector to improve sleeping comfort.

[0008] US 5,144,284 discloses a mat with pressure sensors that can be placed on a bed to monitor a patient's movement. WO 2012 / 153263 A1 relates to a sensor pad with pressure sensors for sleep monitoring.

[0009] WO 01 / 75924 A1 describes pressure sensors in the form of an electrically conductive fabric. It is mentioned that such a sensor fabric can be used in combination with a mattress. EP 1 269 502 B1 discloses a sensor mat with an electrically conductive layer.

[0010] EP 3 736 364 A1 shows a textile sensor mat for a bed, wherein the sensor mat is used to determine the pressure distribution in bedridden persons. EP 3 447 463 B1 from Sefar AG discloses a textile pressure sensor. In one embodiment according to Figures 7 and 8, a first fabric layer has electrically conductive threads that extend in a first direction. A second fabric layer with electrically conductive threads extends in a second direction that is perpendicular to the first direction. A piezoresistive third fabric layer is arranged between the two fabric layers. This third fabric layer changes its resistance and thus its electrical conductivity depending on the pressure force. If a measuring current is applied to the electrically conductive threads and the mat is subjected to pressure, the electrical resistance changes at the intersection areas.This change serves as a measure of the applied pressure and can be recorded by a control unit.

[0011] J. Cheng, et al., Smart-surface: Large scale textile pressure sensors arrays for activity recognition, Pervasive and Mobile Computing (2016), http: / / dx.doi.Org / 10.1016 / i.pmcj.2016.01.007, discloses a sensor mat from Sefar AG with a third fabric layer made of a pressure-sensitive material with the brand name CARBOTEX® from Sefar AG. The electrically conductive threads form a grid or matrix nxm with crossing regions. Each crossing region acts as a pressure sensor and corresponds to a pixel of the pressure distribution matrix. An FPGA (Field Programmable Gate Array) controls ultrafast switch units (switch arrays) and analog-to-digital converters (ADCs) and collects data from the matrix. Each matrix column i of n is switched on individually, while the others are deactivated. The voltages in the m rows then correspond to those at the intersection areas of the m rows of the i-th column.These voltages from the m rows are passed to multiplexers and fed into the ADCs. In the next step, the next column i+1 is switched on, and the corresponding voltages in the m rows are passed on. How the individual multiplexers are controlled is not described. The column-by-column query results in a data series that corresponds to the pressure distribution. n ADCs and n corresponding multiplexers are required. It is stated that 128x128 sensor points can be passed to a computer at 40 frames per second. Image analysis is then performed.

[0012] The applicant's not yet published patent application, EP 21 200 161.4, filed on September 30, 2021, describes a cost-effective and rapid method and a corresponding pressure sensor unit for querying sensor values ​​from a pressure sensor sheet. However, the production of the sensor sheets described above, especially the textile sensor sheets, is also relatively time-consuming and costly.

[0013] WO 2022 / 146612 A1 discloses a textile material with capacitive, inductive, and NFC sensors. The sensor lines are sewn on. The material can be used as a trouser pocket.

[0014] PRESENTATION OF THE INVENTION

[0015] It is therefore an object of the invention to provide a planar pressure sensor unit, in particular a sensor sheet, and a method for producing a planar pressure sensor unit, which simplify the production.

[0016] This object is achieved by a flat pressure sensor unit having the features of claim 1 and a method having the features according to claim 14.

[0017] The pressure sensor unit according to the invention has first conductor tracks and second conductor tracks and a middle layer arranged between the first and second conductor tracks. The first and second conductor tracks intersect at a distance through the middle layer, forming intersection points to act as sensors for detecting a change in distance between the first and second conductor tracks caused by external pressure. The first and second conductor tracks are sewn onto at least one material layer. First and second connecting tracks are provided, which extend from the first and second conductor tracks to at least one electronic unit and which terminate at the at least one electronic unit. The first and second connecting tracks are sewn onto the at least one material layer.

[0018] In some embodiments, the middle layer extends as a flat material along a plurality of first and second conductor tracks. In other forms, the middle layer is formed by individual sections that are spaced apart from one another. The sections are located at least in the intersection regions of the first and second conductor tracks. Their shape is, for example, oval, round, or rectangular. Preferably, the total area of ​​all distances between the sections is many times larger than the total area of ​​all sections. The formation in sections has the advantage that the pressure sensor unit, in particular the sensor sheet, can be made more flexible. It is therefore more comfortable to use. In addition, it is easier to fold and requires less storage space.

[0019] The pressure sensor unit according to the invention is suitable for use as a pressure sensor sheet. However, it can also be connected to or integrated into other bodies. The pressure sensor unit is particularly suitable for use in, on, or on bodies that serve the human body for lying or sitting on. For example, it can be part of a mattress, a bed base, a lounger, an armchair, a chair, a sofa, or a car seat. The terms "pressure sensor sheet" and "sensor sheet" are used below. However, they also encompass the aforementioned embodiments integrated into other bodies, placed on other bodies, or connected to other bodies.

[0020] The term "crossing point" in this text also includes the term "crossing area." According to this text, "sewing," "stitching," and "stitching on" mean the attachment of elements, such as cables or wires, to a layer of material using stitches. "Embroidery" in this text refers to the creation of patterns on the layer of material by attaching elements to the layer of material using stitches. The "middle layer" is also called the sensor layer because it does not necessarily have to be arranged between two layers but can itself form an upper layer. "Middle" refers to the arrangement between the first and second conductor tracks, which cross at a distance from each other. The term "bed base" encompasses all supports on which a mattress or sleeping surface rests.

[0021] The sensor formed at the intersection points is preferably a capacitive sensor, as described in the publications and patent applications mentioned above, in particular in the not yet published EP 21 200 161.4 of September 30, 2021. The intersection points and intersection regions act like capacitors and electrical resistors, respectively. The capacitance of a capacitor changes indirectly proportionally to the distance between its two capacitor plates. Thus, the capacitance at an intersection region changes when a person lies on this intersection region and thus compresses the middle layer. If an electrical voltage is applied to the first and / or second conductor tracks, the change in capacitance results in a change in resistance. This change in resistance can be detected using a voltage divider.Since the first and second conductor tracks are sewn onto the at least one material layer, manufacturing is significantly simplified. Another advantage is that the first and second conductor tracks can be arranged in any pattern. They form an embroidery pattern. They are thus embroidered.

[0022] Preferably, each conductive track is stitched separately from the other conductive tracks. However, the connecting track is also preferably stitched separately from the other connecting tracks. "Separate" in this text means with separate stitches.

[0023] Since the first and second connecting tracks are also sewn or embroidered onto the at least one material layer, the connection to the at least one electronic unit is simplified. In particular, it is no longer necessary to arrange flexprints over the entire length or width of the sheet in order to enable the shortest possible cable connections between the first and second conductor tracks and the electronic unit. Furthermore, it is no longer necessary to solder cables to the multitude of conductor tracks. The electronic unit can now be made relatively small. In particular, it can be arranged in a relatively small area of ​​the sheet. For example, in a corner area or a partial area of ​​an edge of the sheet. The flexprints no longer have to extend over almost the entire length and width of the sheet.

[0024] A further advantage is that the pressure sensor sheet can be folded more easily because the at least one electronic unit arranged on or at the sheet is relatively small.

[0025] Another advantage is that there is greater flexibility in the choice of material for the material layer, since the first and second conductor tracks no longer have to be incorporated into the fabric.

[0026] Preferably, the first and second conductor tracks and the first and second connecting tracks are sewn together using a thread, for example a textile or plastic thread. The thread is preferably not electrically conductive. Depending on the embodiment, the stitches are separate from one another, so that the thread is linked to itself after each stitch. In preferred embodiments, however, a thread extending over several stitches, preferably over the entire length of a conductor track or connecting track, is used. This enables the use of a sewing or embroidery machine. Depending on the embodiment, the stitches penetrate the material layers or the thread runs only in an outer part of the layer.

[0027] The use of an embroidery machine has the advantage that the desired patterns of the conductor tracks and connecting tracks can be easily programmed into the control module of the embroidery machine and the pattern can be generated fully automatically.

[0028] Preferably, the first and second conductor tracks and the first and second connecting tracks are attached to the at least one material layer exclusively by sewing. This simplifies production.

[0029] In a simple embodiment, the first and second connecting tracks and the first and second conductive tracks, respectively, are separate components that are connected to one another. For example, they are soldered together or connected by crimping.

[0030] In preferred embodiments, however, extensions of the first and / or second conductor tracks form the first and / or second connecting tracks, respectively, whereby the first and / or second connecting tracks are formed integrally with the first and / or second conductor tracks, respectively. Thus, no additional tracks are present; instead, the first and / or second conductor tracks extend to the at least one electronic unit. This simplifies manufacturing and reduces interference signals.

[0031] In preferred embodiments, the first conductor tracks form rows of a grid, wherein the rows have ends defining two mutually opposite first sides of the grid. The second conductor tracks form columns of this grid, wherein the columns have ends that define two mutually opposite second sides of the grid. The first connecting tracks leading away from the first conductor tracks lead along at least one of the two first sides of the grid to at least one of the two second sides of the grid. The first and second connecting tracks are connected to the at least one electronic unit on the at least one second side of the grid. Since the first and second connecting tracks are led to the electronic unit outside the shape formed by the grid, they do not influence the crossing points and therefore the individual sensors. In addition, this pattern is quick and easy to sew orto embroider, which in turn simplifies production.

[0032] In preferred embodiments, the first and second conductor tracks and / or the first and second connecting tracks are electrically conductive threads, wires, or cables. They are preferably flat or round in cross-section. They are preferably silver-coated copper wires or other wires that possess optimal conductivity.

[0033] Preferably, the first and second conductor tracks do not have any electrical insulation. Depending on the embodiment, the first and second connecting tracks are either electrically insulated or they also have no electrical insulation.

[0034] If the first and second conductor tracks form the first and second connecting tracks, respectively, they are preferably electrically insulated in the region in which they form the first and second connecting tracks, and they have no electrical insulation in the remaining region. In other embodiments, they have no electrical insulation over their entire length. This is particularly true if the region forming the connecting tracks extends outside the pattern formed by the intersection points.

[0035] The pressure sensor sheet preferably has at least one flexprint that forms the electronics unit. Flexprints are thin, flexible circuit boards. They are typically etched, copper-coated foils, preferably made of plastic. The flexprints can be easily arranged on the sensor sheet or incorporated into the sensor sheet. They increase the thickness of the sheet only minimally or not at all.

[0036] The first and second connecting tracks are connected to the at least one electronic unit by crimping. This allows for a simple, fast, and secure connection of electronic components.

[0037] The material or fabric between the conductor tracks of the individual columns is preferably electrically non-conductive, so that these conductor tracks are galvanically isolated from one another. The same applies to the material or fabric between the conductor tracks of the individual rows. The middle layer is therefore preferably a dielectric or electrically insulating. The middle layer is preferably homogeneous. It is preferably made of a material that changes its thickness proportionally within the range of the expected external pressure and thus changes its electrical conductivity proportionally to the applied pressure. The middle layer is preferably made of Carbotex®, a material distributed by Sefar AG, or of SEFAR® PresSense, a material manufactured by the same company. Other materials that serve as sensor elements can also be used.

[0038] Depending on the embodiment, the pressure sensor sheet has different layers. In some embodiments, the first conductive traces and the first connecting traces are sewn onto a first material layer, and the second conductive traces and the second connecting traces are sewn onto a second material layer, with the middle layer being arranged between the first and second material layers. In some variants, the first material layer, the second material layer, and the middle layer are jointly formed from a composite material, with the first and second conductive traces and the first and second connecting traces being sewn onto the composite material. In other variants, the first material layer, the second material layer, and the middle layer are self-supporting material sheets that are joined together after the first and second conductive traces and the first and second connecting traces have been sewn on.

[0039] In a preferred embodiment, the first conductor tracks are sewn onto a self-supporting material layer. The second conductor tracks are sewn onto the middle layer. Preferably, the self-supporting material layer and the middle layer are connected to one another by sewing on the second conductor tracks. During the manufacturing process, care is preferably taken to ensure that stitches that would damage the first conductor tracks are skipped, i.e., not carried out. In this example, the first connecting lines and the second connecting lines are preferably sewn onto the self-supporting material layer. Preferably, the electronic units, in particular the flexprints, are also sewn onto the self-supporting material layer. Additionally or alternatively, the electronic units can also be glued or attached in another way.

[0040] In this example, the middle layer is preferably smaller than the self-supporting material layer. The self-supporting material layer in this example is preferably a nonwoven, felt, milled fabric, or knitted fabric.

[0041] The first and second material layers are preferably each one or a common textile material layer, preferably a woven fabric, knitted fabric, a milled fabric, knitted fabric, braided fabric, stitch-bonded fabric, nonwoven fabric or felt.

[0042] In the method according to the invention for producing a pressure sensor sheet according to the invention, the first and second conductor tracks are sewn in a first predetermined pattern onto at least one material layer and the first and second connecting tracks are sewn in a second predetermined pattern onto the at least one material layer, wherein they lead from the first and second conductor tracks to the at least one electronic unit and wherein the first and second connecting tracks are connected to the at least one electronic unit.

[0043] The pressure sensor sheet according to the invention is preferably, but not necessarily, arranged in a protective cover that surrounds the at least one material layer. The pressure sensor sheet can be arranged on a mattress, forming the top layer of the bed, or it can be arranged between the sheet and the mattress. It can have means for securing it to a mattress, such as loops that are placed around the corners of the mattress, or it can be stretched over the mattress like a so-called fitted sheet. In these and other embodiments, it is placed on the mattress and secured by a sheet placed over it.

[0044] The pressure sensor sheet can also be placed between the mattress and the bed base. Depending on the design, it can preferably be attached to the mattress and / or the bed base. It can also be placed inside the mattress or be permanently attached to the mattress by the manufacturer. It can also be permanently attached to the bed base by the manufacturer.

[0045] The inventive sewing on of the conductor tracks and connecting tracks or the embroidering of the patterns is particularly advantageous when the sensor sheet is to form a unit with the mattress or bed base. The pattern can be easily adapted during production to the corresponding load pattern of the mattress or bed base. This means that areas that require special attention for a specific mattress or bed base in order to enable the most pain-free and comfortable lying experience possible can be provided with corresponding sensor patterns in the sensor sheet. Sensor sheets can be easily produced whose crossing points, i.e. their pressure patterns, are adapted to the arrangement of the springs of a spring core mattress, the arrangement of the slats of a slatted frame, the arrangement of a mattress base of a slatted frame and the distribution of the air chambers of a foam mattress.The number of intersection points a sensor sheet should have can also be flexibly selected. If the pressure sensor unit is intended for use in one of the other application areas mentioned above, the intersection points can be arranged during production of the pressure sensor unit according to the requirements of this application area.

[0046] Further embodiments are specified in the dependent claims.

[0047] BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Preferred embodiments of the invention are described below with reference to the drawings, which are for illustrative purposes only and are not to be construed as limiting. In the drawings:

[0049] Figure 1 is a schematic representation of a patient bed with a pressure sensor sheet according to the invention of a pressure sensor system according to the invention;

[0050] Figure 2 is a schematic representation of the pressure sensor sheet according to the invention in a first embodiment;

[0051] Figure 3 is a schematic representation of the pressure sensor sheet according to the invention in a second embodiment;

[0052] Figure 4 is a schematic representation of the pressure sensor sheet according to the invention with connecting tracks and flexprints;

[0053] Figure 5 is a photograph of part of the sheet according to the invention in a third embodiment;

[0054] Figure 6 is a photograph of part of the sheet according to Figure 5;

[0055] Figure ? a schematic representation of a bed structure with a pressure sensor sheet according to the invention in a first variant of use;

[0056] Figure 8 is a schematic representation of a bed structure with a pressure sensor sheet according to the invention in a second variant of use;

[0057] Figure 9 is a schematic representation of a bed structure with a pressure sensor sheet according to the invention in a third variant of the

[0058] Use;

[0059] Figure 10 is a schematic representation of a bed structure with a pressure sensor sheet according to the invention in a fourth variant of the

[0060] Use;

[0061] Figure 11 is a schematic representation of a bed structure with a pressure sensor sheet according to the invention in a fifth variant of the

[0062] Use;

[0063] Figure 12 is a schematic representation of a bed base according to the state of the

[0064] Technology and

[0065] Figure 13 is a schematic representation of a use of an inventive

[0066] Pressure sensor sheet on the bed frame as shown in Figure 11.

[0067] DESCRIPTION OF PREFERRED EMBODIMENTS

[0068] Figure 1 schematically shows a bed, in particular a patient bed, with a pressure sensor sheet according to the invention.

[0069] A mattress 1 is covered, as usual, with a bed sheet 2 on which a patient P lies. A pressure sensor sheet 3 according to the invention is placed between mattress 1 and bed sheet 2. The pressure sensor sheet 3 can be designed, for example, as a fitted sheet or, as shown here, as a flat, flexible and preferably soft mat. Depending on the embodiment, it extends over the entire surface of the mattress 1 or, as shown here, ends at a distance from the edge of the mattress. In other embodiments, the pressure sensor sheet 3 extends only in a partial area of ​​the mattress 1, for example, only in the upper, middle, or lower area of ​​the mattress surface. In further embodiments, the pressure sensor sheet 3 is part of the mattress 1 or the bed sheet 2, or it is part of a bed base or rests on it.The arrangement of the sensor sheet beneath the mattress, for example, on a mattress pad or on a bed base, is advantageous because changing the bedding, in particular the bed sheet 2, does not affect the lying properties of the mattress or the patient's lying comfort. The same applies when using the pressure sensor unit according to the invention in other bodies and objects; for example, with such an arrangement, the sitting comfort and seating properties in an armchair or on a chair are not affected.

[0070] In this example, the pressure sensor sheet 3 is connected to a control device 4 via a connector 36 and a cable 37, preferably a 6-pin cable. A control unit of the control device is connected to a DC voltage source. Furthermore, it is connected to a data storage unit and / or a data evaluation unit. These can be located in an on-site unit and / or be cloud-based. A cloud is designated by reference numeral 5 in Figure 1. The control device 4 is preferably implemented as an SPI master, preferably on a Raspberry PI.

[0071] As can be clearly seen in Figure 1, the pressure sensor sheet 3 has a first material layer 31, in particular a fabric layer, a second material layer 32, preferably also a fabric layer, and a middle layer 33 arranged therebetween. The two material layers 31, 32 and the middle layer 33 are preferably connected to one another at specific points, preferably glued. They are preferably jointly surrounded by a protective cover, wherein the cover preferably has a lower layer 34 and an upper layer 35, which, depending on the embodiment, consist of the same material or of different materials. They are preferably soft and flexible, in particular they are a textile fabric or another suitable material layer. Depending on the area of ​​application, at least the upper of the two layers 34, 35 is preferably provided with an incontinence protector so that the three intermediate layers 31, 32, 33 are protected from moisture.In other embodiments, no protective cover is present, for example when the pressure sensor sheet is installed in a mattress.

[0072] The first and second material layers 31, 32 are preferably made of the same material. They are preferably made of an electrically non-conductive material. They are preferably a woven fabric, a knitted fabric, a fulled fabric, a knitted fabric, a braid, a stitch-bonded fabric, a nonwoven fabric, or a felt. The middle layer 33 is made of a pressure-sensitive, preferably dielectric material. The middle layer is preferably homogeneous. It is preferably made of a material that changes its thickness proportionally in the range of the expected externally applied pressure and thus changes its electrical conductivity proportionally to the applied pressure.

[0073] Electrically conductive first conductor tracks 310 are arranged on the first material layer 31, and electrically conductive second conductor tracks 320 are arranged on the second material layer 32. They are sewn onto or onto the respective material layer 31, 32. The individual first conductor tracks 310 preferably run parallel to one another, and the individual second conductor tracks 320 also preferably run parallel to one another. However, the first conductor tracks 310 preferably run perpendicular to the second conductor tracks 320. They thus form a grid or matrix. This is clearly visible in Figure 4.

[0074] In Figure 1, the first and second conductive paths 310, 320 are straight. In Figure 4, they run in a waveform. Both variants and other paths are possible.

[0075] Furthermore, electrically conductive first connecting tracks 390 are present on the first material layer 31 and electrically conductive second connecting tracks 391 are present on the second material layer 32, which are also sewn onto or attached to the respective material layer 31, 32. These first and second connecting tracks 390, 391 are not shown in Figure 1. However, they can be seen in Figure 4. Preferably, the first and second connecting tracks 390, 391 are one-piece extensions of the first and second conductor tracks 310, 320, respectively. The first connecting tracks 390 preferably run along one, or as in this example on two opposite first sides of the grid formed by the first and second conductor tracks 310, 320 to a second side of the grid. The second connecting tracks 291 are located on this side. The first and second connecting tracks 290, 291 are connected to at least one electronic unit on this side.This is preferably a flexprint. In this example, two first flexprints 380 are provided for connecting to the first connecting tracks 390, and a second flexprint 381 is provided for connecting to the second connecting tracks 391. The flexprints 380, 381 are arranged either on the corresponding material layer 31, 32 or between the two material layers 31, 32.

[0076] Figure 5 shows how the first and second connecting strips 390, 391 are sewn onto the first material layer 31. Each first and second connecting strip 390, 391 is fixed, i.e., sewn, onto the material layer 31 with its own thread 392 using several stitches. The first and second conductive strips 310, 320 can be sewn on in the same way. Preferably, one thread 392 is used over the entire length of the corresponding strip. The sewing is preferably done mechanically. A sewing machine of known type can be used for this purpose. However, an embroidery machine is preferably used.

[0077] As can be seen in Figure 4, the first and second conductor tracks 310, 320 have different orientations. The first conductor tracks 310 run perpendicular to the second conductor tracks 320. This creates crossing areas or crossing points 30. In Figure 4, two points are circled to make them easier to see. At the crossing points 30, the conductor tracks 310, 320 do not contact each other because they are separated from each other by the middle layer 33. The crossing points 30 thus act like capacitors or resistors, as explained above. The capacitance of a capacitor changes indirectly proportional to the distance between its two capacitor plates. Thus, the capacitance at a crossing point 30 changes when a person lies on this crossing point 30 and thus compresses the middle layer 33.

[0078] The change in capacitance results in a change in resistance, which in this example is detected using a voltage divider. For this purpose, a constant DC voltage is preferably applied to the first or second conductor tracks 310, 320. The voltage is preferably 3.3 V and thus does not affect the patient's well-being. Other voltages can also be used.

[0079] To determine the patient's lying position, each intersection area 30, i.e., each sensor, is queried individually. For this purpose, the electrical voltage is applied to only one row at a time, i.e., to a first conductor track 310. The values ​​of all columns, i.e., the second conductor tracks 320, are read out sequentially, and only then is the next row "energized," i.e., the electrical voltage applied. The remaining rows, or first conductor tracks 310, are set to 0V. Accordingly, all rows are clocked through sequentially. However, other types of sensor readout are possible.

[0080] In some embodiments, additional sensors are present. In Figure 4, a temperature sensor 8 is present in the sensor sheet 3. The sensor lines from the temperature sensor 8 to the electronics unit, here to the second flexprint 381, are provided with the reference numeral 80.

[0081] In the described example, the first material layer 31, the second material layer 32, and the middle layer 33 are each separate elements that are individually self-supporting. This is illustrated in Figure 2. The conductor tracks 310, 320 and connecting tracks 390, 391, or the combined and one-piece conductor / connecting tracks 310 / 390, 320 / 391, are preferably first sewn onto the material layers 31, 32, and then the material layers 31, 32 and the middle layer 33 are joined together.

[0082] In the variant according to Figure 3, the first material layer 31, the second material layer 32 and the middle layer 33 are jointly formed from a composite material, wherein the first and second conductor tracks 310, 320 and the first and second connecting tracks 390, 391 are sewn onto the composite material.

[0083] In the embodiment according to Figures 5 and 6, the middle layer 33 and the first material layer 31 are present, but no separate second material layer 32 is present. The first material layer 31 is preferably a nonwoven fabric. The middle layer 33 is preferably Carbotex® or another resistance material.

[0084] The first material layer 31 projects beyond the middle layer 33 at least in one edge region, preferably on at least two or all edge regions. The second conductor tracks 320 are embroidered or sewn onto the middle layer 33. The first conductor tracks 310 are embroidered or sewn onto the first material layer 31. The first and second connecting tracks 390, 391 are attached to the first material layer 31, being sewn or embroidered thereon. The electronic units, here the flexprints 380, 381, are also attached to the first material layer 31. Cables 37 or lines leading from the flexprints 380, 381 to the external control device 4 can also be attached to the first material layer 31. The flexprints 380, 381 and the cables 37 or lines can be adhered, for example, using adhesive strips 6.

[0085] In this example, the first and second conductor tracks 310, 320 are integrally connected to the respective first and second connecting tracks 390, 391. This means that they are formed by the same tracks, in particular wires. They are preferably silver-coated copper wires. Depending on the embodiment, this material composite can be used as such, for example, in a mattress or on a bed base. In other embodiments, it is further surrounded by a protective sheath or it covers at least the middle-layer-side surface of the material composite. The sheath preferably consists of the upper layer 35 and / or the lower layer 34.

[0086] The embodiment according to Figures 5 and 6 is preferably produced as follows: First, the first material webs 310 and the first connecting webs 390 are sewn or embroidered onto the first material layer 31, here the fleece.

[0087] Subsequently, the middle layer 33 is placed on the first material layer 31. The second conductor tracks 320 are now sewn or embroidered onto the middle layer 33. Care is taken to ensure that no stitches are placed that could damage the underlying first conductor tracks 310. This is achieved thanks to programmed embroidery machines, which exclude those stitches in the embroidery pattern program that would cause such damage. The area of ​​the second conductor tracks 320 that protrudes above the middle layer 33, i.e., the second connecting tracks 391, is sewn or embroidered onto the first material layer 31 in the same work step, up to the flexprints 380, 381.

[0088] The middle layer 33 is thereby also attached to the first material layer 31. In other embodiments, it is additionally connected, in particular sewn, to the first material layer 31 before or after the first conductor tracks are sewn on.

[0089] In a next process step, the flexprints 380, 381 are attached to the first material layer 31. This step can also be performed before the first and second conductor tracks 310, 320 are sewn on, or after the first conductor tracks 310 are sewn on, but only after the second conductor tracks 320 are sewn on. Subsequently, or before the flexprints 380, 381 are attached, the first and second connecting tracks 390, 391 are crimped to the flexprints 380, 381. The cables 37 are connected to the flexprints 380, 381 and routed to the outside, if not already done beforehand.

[0090] This design allows industrial production at a minimized cost.

[0091] In the described example, the pressure sensor sheet 3 according to the invention is arranged between the bed sheet 2 and the mattress 1. This is shown schematically again in Figure 7.

[0092] However, the pressure sensor sheet 3 can also be arranged underneath the mattress 1, whereby it is positioned between the mattress 1 and a bed base 9. This is shown in Figure 8.

[0093] Furthermore, it can be integrated into the underside of the mattress 1, as can be seen in Figure 9.

[0094] In the variant according to Figure 10, the pressure sensor sheet 3 is formed together with the bed base 9. It can, for example, be fixed to the bed base 9 by the manufacturer.

[0095] In the embodiment shown in Figure 11, the pressure sensor sheet 3 is arranged inside the mattress 1. It can be located centrally, in the upper, or lower region of the mattress 1's thickness. In the example shown, it is arranged approximately centrally.

[0096] Bed bases 9 according to the prior art are designed in very different ways. For example, spring bases, wire bases, spring spring frames, slatted bases, and wooden sprung frames are known. Since the first and second conductor tracks 310, 320 and the first and second connecting tracks 390, 391 are sewn onto the pressure sensor sheet 3 according to the invention, they can be combined into any desired pattern, as long as sufficient crossing points 30 are available as sensors. In particular, the crossing points 30 can be arranged at specific locations.

[0097] Figure 12 shows a bed base 9 with an outer frame 90 and transverse slats 91. Several plates 92 are arranged on the individual slats 91, which resiliently adapt to the loads during use of the bed. Figure 13 shows a pressure sensor sheet 3 according to the invention, manufactured to fit this bed base 9, with only the first and second conductor tracks 310, 320 shown. As can be clearly seen, the spacing of the conductor tracks 310, 320 is selected such that the intersection points 30 each fall on a plate 92.

[0098] The pressure sensor sheet 3 according to the invention can be manufactured easily and inexpensively and allows a flexible design both in the choice of material layers 31, 32 and in the arrangement of the conductor and connecting tracks 310, 320, 390, 391. LIST OF REFERENCE SYMBOLS

[0099] Mattress 390 first connecting track

[0100] 391 second connecting track

[0101] Bed sheet 392 thread

[0102] Pressure sensor sheet 4 Control device Intersection area first material layer 5 Cloud first conductor track

[0103] 6 Adhesive strips second material layer second conductor track 8 Temperature sensor

[0104] 80 sensor cable

[0105] Middle layer lower layer 9 Beds grate upper layer 90 Frame connection 91 Slat cable 92 Plate first Flexprint second Flexprint P Patient

Claims

PATENT CLAIMS 1. A flat pressure sensor unit with first conductor tracks (310) and second conductor tracks (32) and with a middle layer (33) arranged between the first and second conductor tracks (310, 320), wherein the first and second conductor tracks (310, 320) cross at a distance through the middle layer (33), whereby crossing points (30) are formed in order to detect, as sensors, a change in distance between the first and second conductor tracks (310, 320) caused by external pressure, wherein the conductor tracks (310, 320) are sewn onto at least one material layer (31, 32) and wherein first and second connecting tracks (390, 391) are provided, which, leading away from the first and second conductor tracks (310, 320), extend to at least one electronic unit (380, 381) and are connected to the at least one electronic unit (380, 381), and wherein the first and second connecting webs (390, 391) are sewn onto the at least one material layer (31, 32).

2. Planar pressure sensor unit according to claim 1, wherein the first and second conductor tracks (310, 320) and the first and second connecting tracks (390, 391) are attached to the at least one material layer (31, 32) exclusively by sewing on the at least one material layer (31, 32).

3. A planar pressure sensor unit according to one of claims 1 or 2, wherein extensions of the first and second conductive tracks (310, 320) form the first and second connecting tracks (390, 391), whereby the first and second connecting tracks (390, 391) are formed integrally with the first and second conductive tracks (310, 320).

4. Planar pressure sensor unit according to one of claims 1 to 3, wherein the first conductor tracks (310) form rows of a grid, wherein the rows have ends defining two mutually opposite first sides of the grid, wherein the second conductor tracks (320) form columns of the grid, wherein the columns have ends defining two mutually opposite second sides of the grid, wherein the first connecting tracks (390) leading away from the first conductor tracks (310) are arranged along at least one of the two first sides of the grid to at least one of the two second sides of the grid and wherein the first and second connecting tracks (310, 320) are connected to the at least one electronic unit (380, 381) on the at least one second side of the grid.

5. A planar pressure sensor unit according to any one of claims 1 to 4, wherein the first and second connecting tracks (390, 391) are electrically conductive threads, wires or cables.

6. A planar pressure sensor unit according to claim 5, wherein the surfaces of the first and second conductor tracks (310, 320) and the first and second connecting tracks (390, 391) have no electrical insulation.

7. Planar pressure sensor unit according to one of claims 1 to 6, wherein the planar pressure sensor unit has at least one flexprint (380, 381) which forms the electronic unit.

8. A planar pressure sensor unit according to one of claims 1 to 7, wherein the first and second connecting tracks (390, 391) are connected to the at least one electronic unit (380, 381) by crimping.

9. A planar pressure sensor unit according to one of claims 1 to 8, wherein the middle layer (33) is a dielectric or electrically insulating.

10. A planar pressure sensor unit according to one of claims 1 to 9, wherein the first conductor tracks (310), the first connecting tracks (390) and the second connecting tracks (391) are sewn on a first material layer (31) and the second conductor tracks (320) are sewn onto the middle layer (33).

11. A planar pressure sensor unit according to one of claims 1 to 9, wherein the first conductor tracks (310) and the first connecting tracks (390) are sewn on a first material layer (31) and the second conductor tracks (320) and the second connecting tracks (391) are sewn on a second material layer (32), and wherein the middle layer (33) is arranged between the first and the second material layer (31, 32).

12. A planar pressure sensor unit according to claim 11, wherein the first Material layer (31), the second material layer (32) and the middle layer (33) are self-supporting material webs which are joined together after the first and second conductor tracks (310, 320) and the first and second connecting tracks (390, 391) have been sewn on.

13. Planar pressure sensor unit according to one of claims 1 to 13, wherein the first and, if present, the second material layer (31, 32) are each one or a common textile material layer, preferably a woven fabric, knitted fabric, a milled fabric, knitted fabric, braided fabric, stitch-bonded fabric, nonwoven fabric or felt.

14. A method for producing a planar pressure sensor unit according to one of claims 1 to 13, wherein the first and second conductor tracks (310, 320) are sewn in a first predetermined pattern onto at least one material layer (31, 32) and wherein the first and second connecting tracks (390, 391) are sewn in a second predetermined pattern onto the at least one material layer (31, 32), wherein they lead from the first and second conductor tracks (310, 320) to the at least one electronic unit (380, 381) and wherein the first and second connecting tracks (390, 391) are connected to the at least one electronic unit (380, 381).

15. The method according to claim 14, wherein the first conductor tracks (310) and the first connecting tracks (390) are sewn onto a material layer (31), wherein the second conductor tracks (320) are subsequently sewn onto the middle layer (33) and wherein subsequently or simultaneously the second connecting tracks (391) are sewn onto the material layer (31).

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