DE102018127320A1 - Flat sensor arrangement for temporally and / or spatially resolved force or pressure measurement - Google Patents

Abstract

A flat sensor arrangement (1) for temporally and / or spatially resolved force or pressure measurement is disclosed. This sensor arrangement (1), distributed over a detection area, contains individual sensors. It also contains a controller with which the sensors are connected. The sensors are each formed with a first sensor part (5) and a second sensor part (8). The first sensor part comprises a printed circuit board (4) on which, in the area of a detection area, a printed conductor structure is applied, which is exposed to a contact surface. The conductor track structure has an electrical resistance and can be connected to two electrical poles of a measuring current source. The second sensor part (8) contains a contact element formed from a flexibly deformable material. The contact element has a contact surface with which it lies opposite the detection surface of the first sensor part and which tapers in a cross-sectional extent starting from a base in the direction of the detection surface. The contact element is also at least electrically conductive along the contact surface. Such a sensor arrangement (1) is particularly reliable and allows the possibility of accurate measurements while remaining stable over a long period of use. It is also inexpensive to manufacture, requires little maintenance and is easy to use for the user. A special application of the sensor arrangement (1) is to integrate it in an insole or insole for a shoe.

Description

The present invention relates to a flat sensor arrangement for the temporally and / or spatially resolved force or pressure measurement. Such a sensor arrangement has an arrangement of individual sensors distributed over a detection area and a control with which the sensors are connected.

In various fields of application, tasks are known in which loads on a surface or a pressure applied there should not only be recorded as a blanket, but also measured spatially and / or temporally in order to obtain further information therefrom. An example of such an application is the detection of forces which are dynamic on a person's foot when walking or running, in particular also resolved according to different sections of the foot anatomy. The detection of such forces or such pressure loads allows, for example, information about malpositions of the musculoskeletal system, can also be helpful in training an athlete, e.g. for improving his running style.

Correspondingly, flat sensor arrangements with force or pressure sensors have already been proposed, which enable temporally and / or spatially resolved detection of forces or pressures applied to the surface.

In the DE 3704870 describes a flat arrangement with capacitive sensors for measuring pressure forces in a shoe. The limits of this system, which is currently still available on the market, are the high technical effort, the power consumption and the disruptive influence of moisture and temperature. Sensors according to the DE 3704870 have to be calibrated by experts at short intervals, and the complicated electronics lead to short battery life and high retail prices. These products are aimed specifically at professional athletes or therapists and can be used by them after special training. For amateur athletes or other leisure users, however, they are unaffordable and too complicated. The system after DE 3704870 is especially not suitable for unsupervised mobile use with patients or amateur athletes, for example.

Furthermore, on the basis of sensors, so-called force-sensing resistors, which are formed in the form of foils and are dependent on force or pressure, so-called force-sensing resistors are built-up flat sensor arrangements, which have also been proposed for use, for example, for measuring loads in shoes (integrated in insoles) . The basic function of the sensors named above is described, for example, in the US 4,314,227 .

Examples of shoe insoles (or shoe insoles) equipped with such or a comparable sensor technology are described in US Pat US 2010/0063779 A1 , US 5,033,291 and DE 11 2012 000 006 T5 .

The sensors formed in foil form according to the principle of force sensing resistors have a decisive weakness, which up to now has prevented mass use especially for private users: The sensor cells formed according to this principle are inconsistent and change their electrical resistance partly temporarily, partly permanently after strong mechanical loads . This means that measurements cannot be reproduced. If a sensor arrangement, e.g. in an insole, for example containing fifteen individual sensors operating according to the principle of force sensing resistors, it is normal for four or five of these sensor cells to have a permanently changed characteristic curve after loading, while the less loaded sensors remain undamaged. The measurements distorted in this way are not trustworthy and the values of several of the individual sensors cannot be compared with each other. Users help themselves by replacing the sensor films of the sensor arrangement after a few hours of use, which alleviates the problem but does not solve it.

All of the systems currently on offer have three decisive weaknesses: They are expensive, can only be used in a stationary manner and require intensive maintenance. This means that these systems are far from being a consumer-oriented product for the mass market. Because they do not reach large quantities, the cost reductions that would otherwise be expected for electronic products are impossible. The high price results not only from the complicated technology and the relatively high power consumption, but also from the constantly necessary calibrations and the replacement of worn sensor soles in the technique described last with sensors based on Force Sensing Resistors. Specially trained specialists are required for the calibration, which further hinders mass use. For example, As a result, you can hardly find or use insoles in a department store, sports club or medical practice worldwide with a flat sensor arrangement for space and / or time-resolved force or pressure measurement, but rather for the purpose of recording loads and strains that occur during walking or running instead, treadmills with video cameras and Kistler force plates are used, which are expensive, but at least require little maintenance.

Furthermore, the DE 10 2015 007 106 A1 with the force or pressure measurement by a sensor arrangement formed in a shoe sole or a shoe insole. As the title "shoe sole and shoe insole for measuring body weight" makes clear, this invention pursues another goal, namely the measurement of body weight, but not the measurement of dynamic forces during movement.

Core idea of the in the DE 10 2015 007 106 A1 disclosed approach is an arrangement of pressure sensors crossover to combine their measuring ranges. However, film sensors arranged in layers have a mutual influence.

However, the use of sensor arrangements as mentioned at the outset is not limited to an arrangement in an insole or insole of a shoe and the detection of dynamic measured values there. Corresponding sensor arrangements can also be presented for use in other applications, for example in the area of a seat of a piece of seating furniture, in order to dynamically record and monitor the seating behavior of a user. In such an application, warnings could be issued, for example, if a user of such a technology sits in a workplace for too long, too long in a certain posture or in an unhealthy posture to motivate the user to leave or close his or her sitting position change, for example to prevent back injuries caused by sitting for too long and incorrectly.

It is an object of the present invention to provide a sensor arrangement as described at the outset which, in comparison with the solutions known from the prior art, in particular provides a more reliable and stable measurement option which is stable over a long service life, which is at the same time inexpensive to manufacture and easy to use for the user and is low maintenance. In a special aspect of the invention, an improved insole or insole for a shoe is then to be specified, which is equipped with a possibility for temporally and / or spatially resolved force or pressure measurement.

This object is achieved according to the invention first of all by a sensor arrangement for the temporally and / or spatially resolved force or pressure measurement with the features of claim 1. Advantageous further developments of such a sensor arrangement are specified in the dependent claims 2 to 13 and also result from the following general Description of the solution according to the invention. With regard to the further aspect of the task, namely the specification of an improved insole or insole for a shoe, a solution according to the invention is defined in claim 14. Claim 15 specifies an advantageous development. Further advantageous developments result from the following general description of the invention also with regard to this aspect.

A sensor arrangement according to the invention for the temporally and / or spatially resolved force or pressure measurement has, as is also known in the prior art for comparable arrangements, an arrangement of individual sensors distributed over a detection area. This arrangement can in principle be arbitrary, but can advantageously also be matrix-like or in the manner of a partial matrix in rows and columns which are arranged at right angles to one another. The arrangement of the sensors can in particular lie in a flat surface, but it can also be aligned along a continuously running, at least sectionally curved surface. The surface of the individual sensors is separated. They can be arranged directly adjacent to one another, but also under the load of a distance between the individual sensors. Such a distance can differ individually; However, the same distances can also be maintained in a grid-like manner, at least for a partial section of the sensor arrangement.

The sensor arrangement also has a controller with which the sensors are connected. This control can be placed in comparatively close proximity to the sensors of the sensor arrangement, but it can also be at a significant distance from the sensors. The controller can be connected to the sensors of the sensor arrangement, in particular for the transmission of measured value signals from the sensors to the controller. It can also provide an energy supply for the sensors of the sensor arrangement and supply them to the respective sensors. The controller can in particular be set up to address the sensors in the sensor arrangement in a predetermined time pattern and to query them for a measured value signal output. This can be done simultaneously for several or even all sensors of the sensor arrangement, but also sequentially for the individual sensors of the sensor arrangement or for individual groups of sensors of the sensor arrangement. The controller can be set up to query the sensors of the sensor arrangement only when it receives a corresponding trigger signal, for example via a corresponding interface on the controller. It can also be set up for at least a predetermined period of time to carry out a continuous or a clocked or clocked continuous query of measured value signals of the sensors of the sensor arrangement, for example with a predetermined sampling frequency. An evaluation, at least a first partial evaluation of the measurement signals of the sensors of the sensor arrangement can be carried out in the controller, for example an interpretation of the sensor signals and transmission of the corresponding values for an applied force or an exerting pressure and / or a conversion of analog signal data into digital data. The control may, in particular an interface, particularly a wireless interface such as an interface to the WLAN or Bluetooth ^® standard, comprise and be capable of communication with an external data management apparatus, for example a smartphone or a tablet PC, set up on this.

The sensor arrangement can in particular also include an energy source, for example an electric battery or an accumulator, in order to supply the sensors of the sensor arrangement and / or the control with the energy required for operation.

The sensors of the sensor arrangement are each formed with a first sensor part and a second sensor part. The first sensor part of each sensor comprises a printed circuit board on which a conductor track structure having an electrical resistance is applied in the region of a detection surface. This conductor track structure is in any case partially exposed to a contact surface, i. H. Electrical conductors of the conductor track structure are exposed there with the electrically conductive material and can be contacted directly there. The conductor track structure can be connected to two electrical poles of a measuring current source. The measuring current source can in particular be controlled by the control. In particular, it can be designed to be integrated in the control. The conductor track structure can, in particular, also have an infinitely high electrical resistance, idealized, ie H. in an initial state it can be insulating for a measuring current at a given measuring voltage. It is crucial that this will be discussed in more detail below that the conductor track structure can conduct a measuring current by contacting electrical conductors on the exposed surface with a variable electrical resistance when a measuring voltage is applied.

The conductor track structure can be formed, for example, and in particular by printed conductors or conductor track sections which are insulated from one another and on the printed circuit board, of which a first conductor track or a first conductor track section can be connected to a first pole of a measurement current source and a second conductor track or a second conductor track section can be connected to a second one of the first pole different pole of the measuring current source is connectable. In such an embodiment, as already explained above as a possibility, the electrical resistance in an initial state of the conductor track structure is ideally infinitely high, i. H. this structure is electrically insulating under normal conditions. By contacting the first conductor track (the first conductor track section) and at the same time the second conductor track (the second conductor track section) with an electrically conductive element, the resistance is reduced, and a measuring current can flow when the measuring voltage is present. In such an embodiment it can in particular be provided that the first and the second conductor track are each in the form of finger structures with fingers arranged parallel to one another and a connecting line connecting the fingers, the two finger structures being arranged with their fingers offset from one another so that the Fingers of the two conductor tracks lie adjacent to one another without touching one another. In such a structure, depending on a type of contacting of individual fingers on their exposed surface by an electrically conductive element and a bridging of the fingers obtained thereby, a different line resistance can be obtained.

A mask made of an insulating material can also be applied to the interconnects or interconnect sections which are not connected to one another in a starting state on their exposed surfaces, the mask adapting the shape of a geometry of the exposed surface of the interconnects or interconnect sections.

According to the invention, the second sensor part of the respective sensors of the sensor arrangement has a contact element formed from a flexibly deformable material. This contact element has a contact surface with which it is arranged opposite the first detection surface with the conductor track structure of the respective sensor. The contact surface tapers from a base in the direction of the detection surface. The contact element is at least electrically conductive along the contact surface.

In an unloaded state, the respective sensor can in particular be formed such that the contact element lies opposite the detection surface without touching it, in particular without touching the conductor track structure exposed there with the contact surface. In order to ensure this, elastic spacers can be provided which, in an unloaded state, force the contact element back into such a position in which it does not touch the detection area. Such spacers can in particular be connected to the contact element, in one piece with particular advantage. The spacers can be designed, for example, as a bead surrounding the contact element. However, individual, column-like supports or the like are also conceivable. Advantageously, the spacers cannot completely surround the contact element, but instead have interruptions in order to ensure ventilation and to prevent a vacuum, for example an annular space, from being formed in a space formed between the spacers and the contact element trains, which prevents resetting of the contact element.

If a force is applied to the sensor transversely to the orientation of the detection surface or if there is an appropriately directed pressure there, the contact element is forced in the direction of the detection surface and thereby touches the exposed conductor track structure. This creates an electrical contact between individual points of the conductor track structure due to the electrically conductive contact surface, which, with a corresponding configuration of the conductor track structure, leads to a change, in particular a reduction in the electrical resistance and thus a change, in particular an increase, in the measurement current flowing at a predetermined measurement voltage leads. If the load-bearing force or the load-bearing pressure increases, a higher pressure of the contact element on the detection surface leads to an elastic deformation of the contact element, in particular the contact surface, so that a contact area with which the contact surface rests on the detection surface becomes larger. With a corresponding design of the conductor track structure, this leads to a further change, in particular a reduction in the electrical resistance of this arrangement, so that a different, in particular a higher, measuring current flows at the same measuring voltage that is applied to the conductor track structure. In a corresponding geometric configuration of the contact element and on the basis of a characteristic curve recorded for the sensor, a specific resistance of the sensor can thus be assigned to a load-bearing force or an applied pressure. The value of the applied force or the applied pressure can be determined.

The contact element can advantageously be formed from an elastomer material, for example from a silicone rubber. In principle, the contact element can be formed entirely from an electrically conductive material by appropriate measures, for example by introducing corresponding electrically conductive particles or the like into an elastomer material. However, it is preferred, since this is also more economical to implement in terms of costs, that only the contact surface has an electrically conductive coating. This can be, for example, a printed or sprayed-on electrically conductive ink, for example a material with a high graphite content or with metal powder particles. However, other types of implementation are also possible, it being important to ensure that the electrically conductive coating, like the contact element, must have an elastic deformability, so that the electrically conductive coating does not risk tearing or breaking when the contact element is deformed, and thus the functionality of the sensor is lost.

The contact surface of the contact element can, in particular, be conically tapered in one section, starting in particular from the base in the direction of the detection surface. The contact element can in particular be formed in the shape of a truncated cone, for example with a spherically shaped tip. However, it can also have a conical shape overall. Other shapes are also conceivable, for example partially spherical or in the form of a truncated pyramid or a pyramid with a differently shaped base, for example a square base.

It is fundamentally possible to form a sensor arrangement according to the invention with individually designed sensors that are positioned relative to one another to form the sensor arrangement, for example on a base. However, a solution is preferred in which the sensor arrangement, at least in one section, is already produced or can be produced as a coherent arrangement. Correspondingly, at least the contact surfaces of a plurality of sensors of the sensor arrangement provided with the conductor track structures can be arranged on a common printed circuit board. Furthermore, in particular at least the contact elements of a plurality of sensors of the sensor arrangement can also be connected to one another in a contact element support. Such a connection can be realized, for example, by webs or the like connecting the contact element to one another. However, the formation of an overall coherent flat structure in the manner of a mat is particularly preferred here. In this case, contact elements are then implemented at the respectively provided positions and can also be designed as spacers mentioned at the beginning. Such a design enables a simple manufacture of several of the second sensor parts in one work step, for example an injection molding process, possibly with a subsequent printing or coating of the contact surfaces Contact elements with an electrically conductive layer. If the first sensor parts of a plurality of sensors of the sensor arrangement are also implemented jointly on a circuit board, then to form the entire sensor arrangement, the coherent planar structure (the mat) with the contact elements formed therein can be placed in the correct position on the circuit board with the detection areas formed thereon and with the conductor area be connected, for example glued to predetermined connection points.

The circuit board, in particular if it carries the detection surface for several sensors of the sensor arrangement, can also have conductor tracks for the contacting of the conductor track structures in the detection surface and for the interconnection thereof with the controller.

The circuit board, which is used for one sensor of the sensor arrangement or for a group of such sensors or even for all sensors of the sensor arrangement, is particularly advantageous as a flexible circuit board. Here, for example, a PET or PEN film can be used, but also a flexible circuit board film made of polyimide. The use of such a flexible printed circuit board or flexible printed circuit boards has the advantage that a sensor arrangement formed with it can be adapted to surface shapes on which it is to be used. Furthermore, such a sensor arrangement can also deform itself, at least slightly, during use, which is advantageous, for example, when using such a sensor arrangement in an area in which sensitive objects or sensitive body parts stressing the sensor arrangement are advantageous, since sensitive objects are not damaged a user with his sensitive body parts feels no pressure marks or the like. For example, when using a sensor arrangement according to the invention with a flexible printed circuit board in an insole or an insole for a shoe, the wearing comfort of the shoe is maintained if the printed circuit board (as well as the arrangement of the contact elements) has flexibility that does not give the user of the shoe a strong resistance and thus does not trigger a feeling of pressure.

As already mentioned above, a preferred application of a sensor arrangement according to the invention, which is in the particular focus of the inventors, is to arrange it in an insole or insole for a shoe. The arrangement is in particular such that a contact surface of a foot of the user of the shoe provided with the insole or insole rests on the sensor arrangement and in any case covers a plurality of sensors of the sensor arrangement. Advantageously, sensors of the sensor arrangement can be provided in at least one area of the inner or insole for receiving the ball of the foot and in one area of the inner or insole for receiving the heel of the foot.

In such an application, which is however not the only possible and conceivable application - sensor arrangements according to the invention can also be used in other applications, for example in applications as mentioned at the beginning for the detection of forces or pressures which bear on a seat of a piece of seating furniture - With the sensor arrangement, the forces or pressures exerted by the user of the shoe can then be recorded in a temporally and spatially resolved manner and fed to a further evaluation.

A further evaluation can consist, for example, in that the sensor values are compared with an image of corresponding measured values which have resulted for an optimal movement sequence, in order to optimize and train movement sequences for professional athletes or recreational athletes. However, use is also conceivable for or as part of a therapeutic treatment, for example for learning to walk gently in people with hip or knee problems or also after operations, for example for placing hip implants or knee implants or the like.

A corresponding evaluation of data recorded with the sensor arrangement can take place, for example, in software operated on a separate data processing device, typically an app. In the case of a continuous measurement with the sensor arrangement, correspondingly prepared data and results can also be displayed in real time, for example a leisure jogger who uses a running shoe equipped with such an insole or an insole and the corresponding results, for example, on a smartphone or one he has carried other terminal are displayed. In the context of such an evaluation, for example, speech outputs can also be provided, which, for example, can give instructions to an athlete during the use of such a device for improving his movement sequence, for example a running style, as feedback on the measured values and data recorded.

The insole or insole according to the invention can in particular be formed in such a way that the control and also an energy supply are integrated into it. This can be done, for example, by means of a compactly designed part which can be connected to the further sensor arrangement via a plug-in connection and which, in particular, consists of the insole or the insole of the shoe can be removed for connection to an external device, for example for charging accumulators arranged in the compact part and / or for data exchange, for example for loading software or software updates or upgrades onto the controller or for reading out of data from a data memory connected to the controller.

• 1 eine Aufsicht auf eine erfindungsgemäß gestaltete Sensoranordnung (ohne die Steuerung)
• 2 eine Explosionsdarstellung der Sensoranordnung aus 1;
• 3 in zwei Ansichten, einer Aufsicht (3a), und einer isometrischen Ansicht (3b) ein erstes Sensorteil eines Sensors der Sensoranordnung;
• 4 in drei Ansichten, einer Aufsicht (4a), einer isometrischen und explodierenden Ansicht (4b) und einem Längsschnitt (4c) ein zweites Sensorteil eines Sensors der Sensoranordnung;
• 5 in drei Ansichten, einer Aufsicht von der Rückseite her (5a), einer Aufsicht von der Vorderseite her (5b) und einer Seitenansicht ( 5c) zwei über Leitungsabschnitte zusammenhängende Leiterplatten mit darauf ausgebildeten ersten Sensorteilen der Sensoranordnung nach 1;
• 6 in drei Ansichten, einer Aufsicht von der Rückseite her (6a), einer Aufsicht von der Vorderseite her (6b) und einer Seitenansicht ( 6c) zwei mattenartig zusammenhängend gebildete Anordnungen mit zweiten Sensorteilen der Sensoranordnung nach 1;
• 7 eine Kennlinie eines Sensors der Sensoranordnung nach 1.

Further advantages and features of the invention result from the following description of an exemplary embodiment with reference to the attached figures. Show:

• 1 a supervision of a sensor arrangement designed according to the invention (without the control)
• 2nd an exploded view of the sensor arrangement 1 ;
• 3rd in two views, one supervision ( 3a ), and an isometric view ( 3b ) a first sensor part of a sensor of the sensor arrangement;
• 4th in three views, one supervision ( 4a ), an isometric and exploding view ( 4b ) and a longitudinal section ( 4c ) a second sensor part of a sensor of the sensor arrangement;
• 5 in three views, a top view from the back ( 5a ), a front view ( 5b ) and a side view ( 5c ) two circuit boards connected via line sections with first sensor parts formed thereon following the sensor arrangement 1 ;
• 6 in three views, a top view from the back ( 6a ), a front view ( 6b ) and a side view ( 6c ) two mat-like coherent arrangements with second sensor parts after the sensor arrangement 1 ;
• 7 a characteristic curve of a sensor according to the sensor arrangement 1 .

A possible exemplary embodiment or possible embodiments of a sensor arrangement according to the invention are shown in the figures. These merely represent an example of a possible implementation of the invention. The invention is not restricted to this exemplary embodiment, but, as will become clear to the person skilled in the art, can also be implemented in different design forms. Nevertheless, features essential to the invention are again shown and explained on the basis of the figures and the exemplary embodiment shown there, such features also being able to be implemented and incorporated in general in modified embodiments.

In 1 is a possible embodiment of a flat sensor arrangement according to the invention 1 to see. It contains a plurality, in this embodiment 15 , individual sensors 2nd that are designed for the detection of forces or pressures. The sensors are over in the sensor arrangement 1 in the manner described in more detail below with supply and signal lines connected to a connector 3rd to lead. The control can work with the rest of the sensor arrangement 1 alternatively, be firmly connected.

At the connector is in use the sensor arrangement 1 a controller connected, the measurement signals from the sensors 2nd receives and the sensors 2nd supplied with a supply voltage. This control is part of the sensor arrangement 1 . An evaluation of the sensor signals for recording data on the respective sensor can also be carried out in the control 2nd load force or the pressure exerted thereon. The controller can have an, in particular wireless, interface for transmitting data. It can furthermore contain an energy source, such as in particular a battery or an accumulator, for supplying itself and also the sensors 2nd with the required electrical energy.

In the exemplary embodiment shown is the sensor arrangement 1 formed to be integrated into an inner or an insole for a shoe, for example for a running shoe. In this exemplary embodiment, the outline of the sensor arrangement is adapted to the shape of a left foot, for example the size of the shoe 40 may have. Because the sensors 2nd can be largely freely arranged, adaptations to different shoe sizes are possible without any problems. Adaptations can also be made for other uses of the sensor arrangement 1 advantageous forms or those required by such applications are made simply by the number and / or the arrangement of the sensors 2nd adjusted and varied accordingly.

In the arrangement shown are in the sensor arrangement 1 three sensors 2nd in a section intended for arrangement in the area of the heel and twelve sensors 2nd for an arrangement in the area of the front of the shoe in which the ball of the foot is supported. This arrangement reflects the fact that for an application of the sensor arrangement 1 for absorbing dynamic forces that arise during locomotion (walking, running), can be measured on the heel with a lower resolution, while the rolling movements of the toes and forefoot should be measured more precisely.

In 2nd is an exploded view of the vertical structure of the sensor arrangement 1 recognizable. Each on a flexible circuit board 4th are the first sensor parts 5 educated. The flexible printed circuit boards 4th (or sections of a flexible printed circuit board) are over a web 6 connected with each other. Electrical signal and supply lines, which are the first sensor parts, also run along this web 5 to the connector 3rd connect to be able to connect it to the control. When assembled on the flexible circuit boards 4th lie mats 7 with second sensor parts formed therein 8th . The mats are preferably with the second sensor parts 8th formed from an elastomer, in particular from silicone rubber. The mats 7 lie with the second sensor parts to match the first sensor parts 5 on the flexible circuit boards 4th aligned and are with the circuit boards 4th firmly connected, for example with all-round adhesive layers 9 or by welding.

3rd shows an isolated, in the embodiment shown in the flexible circuit board 4th integrally formed, first sensor part 5 . The first sensor part 5 is in the form of a conductor track structure, also known as an electrode 10th formed, especially on the flexible circuit board 4th upset. This trace structure 10th consists of conductor tracks or conductor track sections made of electrically highly conductive material such as copper, while the flexible circuit board 4th consists of an electrically insulating material such as polyimide. The conductor tracks of the conductor track structure 10th are in any case exposed in one section (or in sections) with their conductive material to a contact surface. Both the circuit board 4th as such, as well as the conductor tracks, must be flexibly deformable. In particular, the aim is a realizable bending radius of down to 3 cm. Circuit board 4th and also conductor tracks must also be mechanically robust so that they are used in the application outlined here than in the sensor arrangement 1 withstand the rolling movements of the foot in an insole or insole of a shoe.

The trace structure 10th consists of two separate conductor tracks, which are in an unloaded starting position of the sensor 2nd have no electrical connection.

To the trace structure 10th to the geometric shape of the second sensor part 8th to adapt (see also 4th ) is on the trace structure 4th a mask 15 applied from an insulating material, for example printed.

In 4th is the mechanical structure of a second sensor part 8th shown in more detail (as a section of one of the mats 7 the in 1 sensor arrangement shown). Here are all the second sensor parts 8th a mat 7 in particular and advantageously constructed identically.

The second sensor part 8th has a contact element as the central element 11 , starting from a base with which it is attached to the mat 7 is molded, in an assembled state of the sensor 2nd to the first sensor part 5 pointing direction reduced in cross section. In the exemplary embodiment shown, the contact element is 11 in a perpendicular to the base, hence to a plane of the mat 7 , guided cut in a largely conical shape, has a flattened, approximately spherical tip.

The contact element 11 is like the mat 7 , made of a soft elastomer such as silicone rubber, which is easy to deform on the one hand, but moves back to its original shape in the absence of forces. On a contact surface of the contact element 11 is a coating 12th applied, which is formed from an electrically conductive material which is also elastically deformable.

The contact element 11 Spacers made of the same material are surrounding 13 or support elements shaped. These spacers 13 are placed in a ring section around the contact element and have approximately the cross-sectional shape of an isosceles triangle.

When the sensor is installed 2nd is the second sensor part 7 so on the first sensor part 5 put on that the contact element 11 the trace structure 10th opposite, with a central portion of the contact element 11 to a center of the trace structure 10th points.

The conductor tracks of the conductor track structure 10th are designed so that a small contact surface of the contact element 11 (more precisely the electrically conductive coating 12th ) to a high electrical resistance between two conductor tracks of the conductor track structure 10th leads while a large contact surface of the contact element 11 with its electrically conductive coating 12th as they result from a deformation of the contact element obtained as a result of an exerting force or an exerting pressure 11 results in lower resistance. For example, a meandering structure as used in the exemplary embodiment can be suitable for this. Instead of such a meandering structure, other arrangements are also possible. The only decisive thing is that a deformation of the contact element 11 leads to a correlated change in resistance.

If the contact element 11 as in an unloaded state of the sensor 2nd the trace structure 10th The contact is not touched at all, so the resistance is theoretically infinite. With a light touch, the resistance can be 1 kOhm, with a medium contact, for example at 100 ohms and with a maximum contact area, for example at 10 ohms. The variable electrical resistance stems from the fact that with an increasing contact surface larger parts of the electrically conductive coating 12th of the contact element 11 from the trace structure 10th be contacted.

The spacers 13 are in an assembled state of the sensor 2nd on the circuit board 4th on and prevent the contact element 11 permanently on the track structure 10th lies on. At low across the plane of the circuit board 4th or the mat 7 acting forces are only the spacers 13 on while the contact element 11 with larger forces increasingly on the flexible circuit board 4th trained trace structure 10th rests, thereby being deformed further and further, so to speak, pressed flat, and thereby, as mentioned above, an ever-decreasing electrical resistance. Recesses 14 between the spacers formed as ring segments 13 serve as air channels to prevent air bubbles when compressed.

As mentioned, the mats are 7 at its edge, for example by means of an adhesive, a weld or an adhesive tape with the respective flexible printed circuit board 4th connected. The contact elements can be removed by mechanical pressure from above 11 individually or together, independently of each other across the plane of the mat 7 towards the flexible circuit board 4th be pressed.

In an application for the formation of a sensor array 1 provided inner or insole of a shoe should be the contact elements 11 With regard to the hardness of the material and the shape, it should be dimensioned and designed so that a slight vertical pressure (pressing force <10 N) only leads to minimal deformation, while the maximum deformation (depending on body weight and movement load up to approx. 500 N) ) per unit area for an almost complete support of the contact element 11 on the flexible circuit board 4th , or the conductor track structure 10th should lead. This is because no additional forces can be measured with a full run. The shape of the contact element 11 and the hardness of their material, especially the elastomer used, determine the measuring range.

Depending on the application, the sensor arrangement 1 with their integrated sensors 2nd So be designed for lighter or heavier loads. When used in an insole or insole of a shoe, however, the load per unit area is roughly the same for heavier and lighter people, because taller people generally also have larger feet. Therefore, the same construction of the contact elements 11 be suitable for very different shoe sizes.

In 5 is the entire flexible circuit board 4th to be seen with the first sensor parts formed on an insulating carrier material 5 in the form of the conductor track structures 10th . In the circuit board 4th are interconnects that form the interconnect structures 10th with the connector 3rd connect. These conductor tracks are not shown here. The course and the arrangement of these conductor tracks correspond to the technology customary for flexible conductor tracks. Every contact element 11 is exactly a conductive coating 12th and exactly one trace structure 10th assigned, together they each form a sensor 2nd .

Each sensor is in the exemplary embodiment 2nd also exactly one channel of an analog / digital converter assigned to the controller. A matrix arrangement for measurement is also conceivable and would reduce the number of conductor tracks and the channels to be provided in the analog / digital converter, but such an arrangement increases the risk of interference due to the mutual influence of sensors 2nd .

6 shows the mats 7 with a group of a contact element formed thereon 11 having second sensor parts 8th . The mats 7 are arranged here in a shape adapted to the foot. The second sensor parts are in the exemplary embodiment 9 with the contact elements 11 arranged in a regular grid. But this is not absolutely necessary, they can be arranged freely. The sensor parts 8th and their contact elements 11 can also be made larger or smaller than in the exemplary embodiment. With larger contact elements 11 however, the position information of the measurements would be less precise. With very small contact elements 11 (<6mm) there is a danger that saturation is reached faster with larger forces, ie the force measuring range would be restricted, but the position resolution would be higher.

In 7 is a characteristic of a sensor 2nd pictured. As long as the contact element with the electrically conductive coating 13 the trace structure 10th the contact is open and the resistance is extremely high (in the megaohm range). As can be seen from this characteristic curve, the resistance drops here with a load of around 5N to around 1 kOhm, then drops with a load from 10N to below 250 Ohm and then approaches when the sensor is saturated 2nd with around 80N a resistance of less than 10 ohms.

This characteristic is directly related to the mechanical design of the contact element 11 . Depending on the shape and material of the contact element 11 If the characteristic curve also changes, a flat shaped contact element would be used 11 lead to saturation faster (the measuring range would be smaller, the sensor 2nd more sensitive), while a contact element made of harder material 11 can also register higher forces.

The semi-linear characteristic in 7 In the exemplary embodiment, this is deliberately chosen because it enables precise measurement with lower forces of less than 10N, but can still differentiate forces of more than 50N.

• Sohlensensoren auf kapazitiver Basis liefern nur schwache elektrische Signale mit hohem Rauschanteil, die leicht durch Feuchtigkeit in der Messumgebung, z.B. in einem Schuh, oder durch andere Störeinflüsse, wie z.B. bei einer Integration in einer Sohle durch Fußbewegungen, gestört werden können. Im Unterschied dazu liefert die erfindungsgemäße Lösung bei einer Beschaltung der resistiven Sensoren, z.B. der Sensoren 2, mit einem üblichen Spannungsteiler vergleichsweise starke Signale im 100mV-Bereich. Dadurch ist es nicht eforderlich, die Zuleitungen abzuschirmen.

A sensor arrangement according to the invention, for example a sensor arrangement as shown in the figures and described above 1 , has the following advantages over the known solutions:

• Capacitive-based sole sensors only provide weak electrical signals with a high noise component, which can easily be disturbed by moisture in the measurement environment, e.g. in a shoe, or by other interfering influences, such as foot movements when integrated in a sole. In contrast to this, the solution according to the invention provides when the resistive sensors, for example the sensors, are connected 2nd , with a common voltage divider comparatively strong signals in the 100mV range. It is therefore not necessary to shield the supply lines.

Usual sensor arrangements The basis of foils with so-called force sensing resistors, when used as sole sensors, provide signals with jitter in the frequency range of over 20 Hz, which have to be filtered out separately. The cause is the strong vibrations when running, which lead to changeable contacts of the film. In particular, while running with a sports shoe, the inserted sensor film is considerably curved and deformed in accordance with the foot movements. The trigger path of a force sensor based on a force sensing resistor is around 0.01 to 0.05 mm, i.e. 10-50µm. Accordingly, a vibration or impact with a movement of 0.01 to 0.05 mm acting on the sensor leads to a full deflection of the sensor system. The short triggering path of the sensor in the manner of the known force sensing resistor results in a high resonance frequency of well over 100 Hz, which worsens the signal / noise ratio of the measurements.

In contrast to this, the spring travel, that is to say the trigger path in the solution according to the invention, is in the range of 0.5 mm, which is 10 to 50 times as much as in the case of the sensors of the type of a force sensing resistor which have been customary to date. Correspondingly, a deformation with a movement of 0.01 to 0.05 mm acting on the sensor according to the invention only leads to a deflection of 2-10%, and therefore does not confuse the measurement. The resonance frequency is clearly below 100 Hz and thus outside the frequency ranges important for the measurement.

The construction of the sensors according to the invention ensures that each electrically measurable signal is directly proportional to the deformation of the contact element, for example the contact element 11 , behaves. Accordingly, the precision of the system is a constantly conductive contact surface of the contact element, for example in the form of the coating 12th on the contact element 11 , and a constant conductor structure, for example the conductor structure 4th , provided that it is as reproducible as the mechanics of the contact element, eg the contact element 11 .

In addition, it is ensured in the construction according to the invention that the measured electrical resistances are always relative to the total resistance of the conductive contact surface of a contact element, for example the conductive coating 12th of the contact element 11 , behavior. Without contact between the contact element and the conductor track structure, in an implementation as described in the exemplary embodiment or in a comparable implementation with conductor tracks separated in the normal state, no electrical connection can be made to the conductor track structure. With maximum contact of the contact surface of the contact element, ie maximum triggering of a sensor, for example a sensor 2nd , the electrical resistance of this sensor is always the same value that that of the resistance of the conductive contact surface of the contact element, for example the conductive coating 12th of the contact element 11 corresponds.

There may be deviations between the second sensor parts, for example the second sensor parts 8th on the mat 7 , and there may also be production tolerances or other deviations between several second sensor sub-arrangements of different sensor arrangements, for example between several mats 7 , but the measured values of a sensor are relative to the maximum resistance of the conductive contact surface, for example the conductive coating 12th a contact element 11 , always constant. This also compensates for fluctuations in changing temperatures.

Reference list

1

Sensor arrangement

2nd

sensor

3rd

Connector

4th

flexible circuit board

5

first sensor part

6

web

7

flexible mat

8th

second sensor part

9

Adhesive layer

10th

Trace structure

11

Contact element

12th

electrically conductive coating

13

Spacers

14

Recess

15

mask

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for better information for the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• DE 3704870 [0004]
• US 4314227 [0005]
• US 2010/0063779 A1 [0006]
• US 5033291 [0006]
• DE 112012000006 T5 [0006]
• DE 102015007106 A1 [0009, 0010]

Claims (15)

Flat sensor arrangement (1) for the temporally and / or spatially resolved force or pressure measurement with an arrangement of individual sensors (2) distributed over a detection area and with a control with which the sensors (2) are connected, characterized in that each of the Sensors (2) are formed with a first sensor part (5), which has an electrical resistance and has an electrical resistance on a printed circuit board (4), which is mounted thereon in the area of a detection surface and is at least partially exposed to a contact surface and can be connected to two electrical poles of a measuring current source Conductor structure (10), and a second sensor part (8) which has a contact element (11) formed from a flexibly deformable material, the contact element (11) having a contact surface with which it is opposite the detection surface with the conductor structure (10) is arranged, and which is in a cross-sectional scope starting from e seen tapered in the direction of the detection surface, and wherein the contact element (11) is formed at least along the contact surface in an electrically conductive manner. Sensor arrangement (1) after Claim 1 , characterized in that the contact element (11) is formed from an elastomer material. Sensor arrangement (1) according to one of the preceding claims, characterized in that the contact element (11) is provided on its contact surface with an electrically conductive coating (12). Sensor arrangement (1) according to one of the preceding claims, characterized in that the contact element (11) has a contact surface which tapers in one section in any case, starting from the base in the direction of the detection surface. Sensor arrangement (1) according to one of the preceding claims, characterized in that the contact element (11) does not touch the detection surface when the sensor (2) is not subjected to a force or a pressure. Sensor arrangement (1) according to one of the preceding claims, characterized in that the conductor track structure (10) having an electrical resistance is formed by conductor tracks or conductor track sections which are applied to the printed circuit board (4) and are insulated from one another, of which a first conductor track or a first conductor track section also has a first pole of a measuring current source can be connected and a second conductor track or a second conductor track section can be connected to a second pole of the measuring current source that is different from the first pole. Sensor arrangement (1) after Claim 6 , characterized by two interleaved, mutually electrical finger structures as first and second conductor tracks. Sensor arrangement (1) according to one of the Claims 6 or 7 , characterized by a mask made of an insulating material applied to the exposed surface of the conductor tracks or conductor track sections, the mask adapting the shape of a geometry of the exposed surface of the conductor tracks or conductor track sections to a cross-sectional geometry of the contact element. Sensor arrangement (1) according to one of the preceding claims, characterized in that the contact surfaces provided with conductor track structures (10) of a plurality of sensors (2) of the sensor arrangement (1) are arranged on a common printed circuit board (4). Sensor arrangement (1) according to one of the preceding claims, characterized in that the contact elements (11) of a plurality of sensors (2) of the sensor arrangement (1) are connected to one another in a contact element support (7). Sensor arrangement (1) according to one of the preceding claims, characterized in that the printed circuit board (4) is a flexible printed circuit board. Sensor arrangement (1) according to one of the preceding claims, characterized in that the controller is set up to repeatedly record sensor signals of the individual sensors (2) in a predetermined time interval and to provide an evaluation. Sensor arrangement (1) according to one of the preceding claims, characterized in that the controller has an interface for wireless transmission of data, in particular of measurement data obtained from the sensor signals. Insole or insole for a shoe, characterized in that it has a flat sensor arrangement (1) according to one of the preceding claims. Insole or insole after Claim 14 , characterized in that the flat sensor arrangement (1) sensors (2) at least in a region of the insole or insole for receiving the ball of the foot and in a region of the insole or insole for the heel.

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