SENSOR STRIP AND DEVICE FOR MEASURING GEOMETRIC SHAPES

Abstract

The present invention relates to a flexible sensor strip for measuring geometric shapes, in particular bending radii or the like, and to an associated device which can process and evaluate sensor signals of the sensor strip. The sensor strip comprises a substrate, on which a plurality of resistor pairs is arranged. Each of these resistor pairs has a resistor on the substrate front side and a further resistor on the substrate rear side. Both of these resistors are connected in series and between the poles of a supply voltage so that they form a voltage divider. The special feature of the present invention is that an electrical via and/or a pair of electrically interconnected contact elements is provided for the series circuit, that is, for the connection between the two resistors. When the substrate or the sensitive region of the sensor strip is moved into itself, in particular in the event of bending and/or twisting (torsion), the mid voltages in the affected voltage dividers change. This is sensed and evaluated by the measuring device according to the invention.

Claims

1. A sensor strip for measuring geometric shapes, wherein a substrate at least one first pair of two electrical resistors are provided, the first of which being arranged on the front side of the substrate and the other resistor being arranged on the rear side of the substrate in such a way that it lies essentially opposite to the first resistor the first terminal of the first resistor is electrically connected via a first supply voltage conductor to the first pole of a supply voltage and the first terminal of the second resistor is electrically connected via a second supply voltage conductor to the second pole (ground) of the supply voltage the second terminals of the two resistors are electrically interconnected, so that they form a voltage divider, is hereby characterized in that, for the electrical connection between the second terminals of the two resistors, at least one via is provided, which electrically connects a strip conductor to the second terminal of the first resistor on the front side to a strip conductor to the second terminal of the second resistor on the rear side, and/or in that the two strip conductors lead to respective contact sites, which are designed and arranged in such a way that they can be electrically interconnected via contact elements.

2. The sensor strip according to claim 1, further characterized in that at least one second pair of two electrical resistors is provided, the first of which being arranged on the front side of the substrate and the other resistor being arranged on the rear side of the substrate in such a way that it lies essentially opposite to the first resistor 1. the first terminal of the first resistor is electrically connected via the first supply voltage conductor to the first pole of the supply voltage and the first terminal of the second resistor is electrically connected via the second supply voltage conductor to the second pole of the supply voltage 2. the second terminals of the two resistors are electrically interconnected, so that they form a voltage divider 3. at least one of the first resistor pairs and at least one of the second resistor pairs are arranged adjacent to each other.

3. The sensor strip according to claim 1, further characterized in that the first resistor pairs and/or the second resistor pairs have an angle of inclination with respect to normals, the value of which lies between zero and 90 degrees.

4. The sensor strip according to claim 1, further characterized in that the number of first resistor pairs is equal to the number of second resistor pairs and they are arranged in mirror symmetry with respect to each other in relation to the normals.

5. The sensor strip according to claim 1, further characterized in that the first supply voltage conductor is arranged on the front side of the substrate and extends between the first resistor pairs and the second resistor pairs, preferably along the normals.

6. The sensor strip according to claim 1, further characterized in that the second supply voltage conductor is arranged on the rear side of the substrate and extends between the first resistor pairs (28l, 128l) and the second resistor pairs (28r, 128r), preferably along the normals.

7. The sensor strip according to claim 1, further characterized in that at least individual ones of the resistors are applied to the substrate by a printing method, such as, for example, screen printing, and preferably a high-ohmic paste is used for this purpose.

8. The sensor strip according to claim 1, further characterized in that at least individual ones of the connecting conductors required for the terminals of the resistors and/or at least one of the vias are applied to the substrate by a printing method, such as, for example, screen printing, and preferably a low-ohmic paste is used for this purpose.

9. The sensor strip according to claim 1, further characterized in that it has a first region, which, in normal operation, is deformable and in which the mentioned resistors are arranged, and it has a second region, which, in comparison with first region, is less deformable in normal operation and in which at least individual ones of the vias are arranged.

10. A device for measuring geometric shapes, characterized in that a sensor strip according to one of the above claims is used, and in that the resistors are connected via suitable electrical connections to an evaluation unit, which delivers the supply voltage and wich receives voltages produced by the voltage dividers as sensor signals and generates an output signal, which is a measure for changes in resistance within the individual resistor pairs.

11. The device according to claim 10, further characterized in that the evaluation unit generates a reference voltage, the value of which essentially corresponds to the value that the sensor signals have in a resting state of the sensor strip, and forms a difference between the value of this reference voltage and the value of the measured sensor signals.

12. The device according to claim 10, further characterized in that the sensor signals of at least individual ones of the resistor pairs are evaluated in succession, so that, taking into consideration their position inside of the sensor strip, an output signal is generated, the value of which is a measure for the geometric shape of the sensor strip.

13. The device according to claim 10, further characterized in that, successively in time, sensor signals of at least individual ones of the resistor pairs are evaluated, so that, taking into consideration their position inside of the sensor strip, an output signal is generated, the value of which is a measure for the course of movement of the resistor pairs in question.

14. The device according to claim 10, further characterized in that it has a transmission unit, which emits a transmission signal as a function of the output signal.

15. The device according to claim 10, further characterized in that it has at least one pair of contact elements, with one of these contact elements being designed and arranged in such a way that, in normal operation, it is in electrical contact with one of the front-side strip conductors and the other one of these contact elements being designed and arranged in such a way that, in normal operation, it is in electrical contact with one of the rear-side strip conductors, with the two contact elements being electrically interconnected.

Description

[0045] Further details and advantages of the present invention are explained below on the basis of exemplary embodiments with associated figures. Hereby shown are:

[0046] FIG. 1 a first sensor strip

[0047] FIG. 2 front-side strip conductors of the first sensor strip [Vorderseite32 Front side]'

[0048] FIG. 3 front-side sensor resistors of the first sensor strip

[0049] FIG. 4 rear-side strip conductors of the first sensor strip [Rckseite=Rear side]*

[0050] FIG. 5 rear-side sensor resistors of the first sensor strip

[0051] FIG. 6 symbolic plan view of a via between a front-side strip conductor and a rear-side strip conductor

[0052] FIG. 7 symbolic cross-sectional illustration of the via between a front-side strip conductor and a rear-side strip conductor

[0053] FIG. 8 circuit diagram

[0054] FIG. 9 a second sensor strip

[0055] FIG. 10 the upper section B of the second sensor strip

[0056] FIG. 11 the lower section C of the second sensor strip

[0057] FIG. 12 symbolic cross-sectional illustration of the connection between a front-side strip conductor and a rear-side strip conductor through contact elements that are interconnected

[0058] FIG. 1 shows a Cartesian coordinate system (top left), a plan view of a first sensor strip 9 and, on the right side, a symbolic marking for distinguishing a sensor region S as well as a contact region K of the sensor strip 9. The latter is situated here within the x-y plane and accordingly in the plane of the drawing. It contains a substrate 10, which consists of a material that is bendable, twistable, and/or stretchable as well as, in the exemplary embodiment shown here, transparent. A PET film (PET=polyethylene terephthalate), the thickness of which, in a preferred embodiment, lies in the range of 100 to 180 m, has proven to be especially expedient. The substrate 10 has a front side 12 (see FIGS. 1 and 7) as well as a rear side 14 (see FIG. 7). The front side 12 could also be referred to as the top side. However, this term is avoided here, because the positional specifications top, bottom, right, and left (and the like) serve for the description of position within the plane of the drawing. Arranged both on the front side 12 and on the rear side 14 are a plurality of sensor resistors and also a plurality of electrical strip conductors. They are described in detail below on the basis of FIGS. 1 to 5.

[0059] FIG. 2 shows those strip conductors that are arranged on the front side 12 of the substrate 10 and FIG. 3 shows the sensor resistors of the front side 12. Situated in the lower region are a plurality of electrical contact sites 16, which form a connector power strip and are designed and arranged in such a way that they can be contacted with membrane connectors (not depicted here). Two of these contact sites 16 are connected via a strip conductor 18 to a front-side supply voltage conductor strip 20, which extends here essentially along the longitudinal axis LA.

[0060] Via associated connections, contact points 22r to the right of the supply voltage conductor strip 20 and contact points 22l to the left thereof are electrically connected to the supply voltage conductor strip 20.

[0061] Belonging to each of the contact points 22r is an associated contact point 24r, which is electrically connected via an associated strip conductor 26r to a respective one of the contact sites 16. Depicted in FIGS. 1 and 2 are five of the contact point pairs 22r, 24r, only two of which are provided with reference signs (see FIG. 2). Extending between each of these contact point pairs 22r, 24r is one of five sensor resistors 28r, which here have an oblong rectangular shape.

[0062] In the exemplary embodiment shown, the uppermost of these sensor resistors 28r hereby extends in such a way that it and accordingly also its longitudinal axis form a right angle with the supply voltage conductor strip 20 and therefore also with the longitudinal axis LA. The lowermost of these sensor resistors 28r extends essentially parallel to the supply voltage conductor strip 20 and accordingly also to the longitudinal axis LA. Drawn in the case of the middle one of the sensor resistors 28r in FIG. 1 is its longitudinal axis lar and also an angle of inclination , which is defined by the two longitudinal axes LA and lar and is approximately 45 degrees.

[0063] Situated to the left of the upper supply voltage conductor strip 20 and accordingly of the longitudinal axis LA is, besides the already mentioned contact points 22l, also associated contact points 24l, each of which is connected to a strip conductor piece 25l. Each of these strip conductor pieces 25l is connected by way of a special via to a strip conductor 126l, which is situated on the substrate rear side 14 and to the left of the longitudinal axis LA. Details regarding this are described further below.

[0064] Similarly to the right side, there are here also five contact point pairs 22l 24l, between which associated sensor resistors 28l are arranged. In this exemplary embodiment, the left sensor resistors 28l are arranged in mirror symmetry with respect to the right sensor resistors, so that the above-mentioned explanations apply analogously also to the left side.

[0065] FIG. 4 shows the strip conductors that are arranged on the rear side of the substrate 10 and FIG. 5 shows the associated sensor resistors. The direction of view on the elements shown in FIGS. 4 and 5 is from the top, that is, from the front side 12 passing through the substrate 10, with the elements that are on the substrate front side 12 not being present. Therefore, one could also say that here one sees the rear sides of those elements that are placed on the substrate rear side 14. Most of these rear-side elements cannot be seen in FIG. 1, because they are covered up by elements of the front side. Exceptions are the already mentioned strip conductors 1261.

[0066] As can be seen in FIG. 4, the substrate rear side 14 has a lower voltage supply conductor strip 120. It is connected via a strip conductor 50 (see FIGS. 1 and 2), which extends on the substrate front side 12, as well as by way of a via in the region 52, which is not depicted here, to two of the contact sites 16, which, in this exemplary embodiment, are all situated on the front side 12. The design and arrangement of the rear-side supply conductor strip 120 above the region 52 is essentially identical to the design and arrangement of the front-side supply voltage conductor strip 20. This also means, in particular, that, on the rear side 14, a plurality of contact points 122r, 1221 are present, which correspond to the contact points 22r, 221 apart from the fact that they are connected to different supply voltage conductor strips. Furthermore, five contact points 1241 are present to the left of the rear-side supply voltage conductor strip 120 and are each connected via a respective one of the left strip conductors 1261 and, in addition, by way of a via, which is not shown here, between the front side 12 and the rear side 14, to one of the front-side contact sites 16 (see FIG. 1). Situated to the right of the supply voltage conductor strip 120 are a five further contact points 124r, which are each connected to a strip conductor piece 125r.

[0067] Each of these strip conductor pieces 125r is connected by way of a special via to one of the strip conductors 26r, which are situated on the substrate front side 12 and to the right of the longitudinal axis LA. Details regarding this are described further below.

[0068] In a further exemplary embodiment, it is provided that contact sites are also provided on the rear side 14. These rear-side contact sites can be equal in size to the front-side contact sites 16 and also can be made virtually to coincide in position with them. In the case of the presence of contact sites on both sides 12, 14, an associated membrane connector should be used. Diverse contacting and circuitry variants are hereby possible.

[0069] The sensor resistors 128l, 128r shown in FIG. 5 have a design and arrangement that is identicalor at least essentially identicalto the design and arrangement of the sensor resistors 28l and 28r present on the substrate front side 12. Therefore, they cannot be seen in FIG. 1. It is hereby noted once again that, in FIG. 5, the illustration corresponds to a plan view of the substrate front side 12 with the view passing through the substrate 10 and the elements that are on the substrate front side 12 not being present.

[0070] FIG. 6 shows a symbolic enlargement of the region A marked in FIG. 1. What is hereby essentially involved is the illustration of a via between one of the front-side strip conductor pieces 25l and the associated strip conductor 126l, that is, the strip conductor 126l situated oppositely on the substrate rear side 14. FIG. 7 shows a symbolic cross-sectional illustration of this via.

[0071] It can be seen from FIGS. 6 and 7, in particular, that, on the front side 12 of the substrate 10, one of the left sensor resistors 28l and below it (in accordance with FIG. 7), on the substrate rear side 14, an associated sensor resistor 128l are arranged. Moreover, the front-side sensor resistor 28l is connected to the front-side contact point 24l and, in turn, the latter is connected to the front-side strip conductor piece 25l. To this end, it is noted that the contact point 24l and the strip conductor piece 25l represent a common electrical connecting element and are drawn separate here only for a simple description of the figures. The rear-side sensor resistor 128l is connected to the rear-side contact point 124l and, in turn, the latter is connected to the rear-side strip conductor 126l, which leads by way of a further via to the associated contact site 16 (see FIG. 1). Arranged between the front side 12 and the rear side 14 through a corresponding opening within the substrate 10 is a via conductor 200, which here consists of the same material as the front-side strip conductor piece 25l and the rear-side strip conductor 126l and electrically interconnects these two elements 25l, 126l. Accordingly, the two sensor resistors 28l and 128l are connected in series. Moreover, even though not illustrated for reasons of clarity, it ensues from the preceding explanations as well as from FIGS. 1 to 5 that [0072] the apparently free end 29l of the sensor resistor 28l is electrically connected via the contact point 22l to the supply voltage conductor strip 20 and [0073] the apparently free end 1291 of the sensor resistor 128l is electrically connected via the contact point 122l to the supply voltage conductor strip 120.

[0074] The other ones of the front-side left sensor resistors 28l are also connected in such a way to their associated rear-side sensor resistors 128l. The same also applies to the right sensor resistors 28r and 128r.

[0075] The sensor resistors 28, 128 are preferably produced by a screen printing method, in which, in this case, a carbon-based paste, structured with a thickness of approximately 5 to 20 m, is applied to the two sides 12, 14 of the substrate 10. In the exemplary embodiment described, the sensor resistors 28, 128 hereby have a length of approximately 7 mm. Their width can be quite different depending on the application and lies in the range of approximately 100 m to 800 m in order to realize resistance values in the range of between 10 k and 80 k. The other elements present on the substrate sides 12, 14, such as, in particular, the strip conductors and the contact points, are preferably likewise produced by a screen printing method, in which silver paste with a thickness of approximately 5 to 15 m is applied.

[0076] FIG. 8 shows a circuit diagram, in which a pair of left sensor resistors 28l, 128l and a pair of right sensor resistors 28r, 128r are taken into account The circuit diagram is divided into the following three blocks: [0077] S: sensor region [0078] K: contact region [0079] A: evaluation unit

[0080] The sensor region S essentially corresponds to the part of the sensor strip 9 in which the sensor resistors 28l, 28r, 128l, 128r are arranged. It is designed in such a way that it is flexible and, in particular, can be bent, twisted, and/or stretched. The contact region K essentially corresponds to the part of the sensor strip 9 in which the supply voltage conductor strips 20, 120 as well as the strip conductors 26r, 126l are connected to the contact sites 16. In a preferred embodiment, the contact region K (see also FIG. 1), at least in the operating mode (normal operation), is substantially less flexible or deformable than the sensor region S. This can be achieved, for example, by way of the terminal of a membrane connector at the contact sites 16, by way of a lesser bonding of the region K to the object that is to be examined. and/or way of a corresponding design of the substrate 10 (such as, its thickness, material, etc.).

[0081] The evaluation unit A, which here is connected via the contact 300 of a membrane connector to the contact sites 16, contains a supply voltage source as well as conventional electronic elements, such as, for example, amplifiers, A/D converters, memory storage components, transmitting devices, display elements, and/or the like. This will be addressed in detail further below.

[0082] As ensues from the circuit diagram of FIG. 8, a supply voltage +u is applied to the front-side supply voltage conductor 20, the value +U of which can be, for example, 3 volts. The rear-side supply voltage conductor 120 is at ground. The sensor resistors 28r and 128r are connected in series between the supply voltage +u and ground, so that they form a voltage divider, with the strip conductor 26r making possible the center tap. The sensor resistors 28l and 128l also form a voltage divider of this kind, with the strip conductor 126l making possible the center tap. The two strip conductors 26r, 126l each lead to one of the contact sites 16. Via an associated membrane connector contact 300, the divided voltages, which are also referred to below as sensor signals sr and sl, are conveyed to amplifier stages 302a and 302b, respectively. The output signals thereof are fed to an evaluation stage 304, which, on account of the amplified sensor signals, generates output signals, which are conveyed via a signal conductor 308 to a display stage 306.

[0083] In FIG. 8, for reasons of clarity, the processing of a sensor signal sl, which originates from a pair of left resistors 28, 128l, as well as the processing of a sensor signal sr, which originates from a pair of right resistors 28r, 128r, are illustrated. It is obvious that the evaluation unit A can also receive and process the sensor signals of the other resistor pairs 28l, 128l and 28r, 128r. There exist various possibilities for this, such as, for example, the use here of a switching stage, which is not depicted, inside of or outside of the evaluation unit A. Such a switching stage could receive a plurality of or all of the sensor signals sl, sr and convey them further in accordance with the principle of a time multiplexer under time control via the amplification stages 302a, 302b to the evaluation stage 304. It is also conceivable that, for each of the sensor signals sl, sr, a separate amplifier stage 302a and 302b, respectively, is provided and the amplified sensor signals are conveyed to the evaluation stage 304 by means of an associated switching stage. It is also conceivable that each of the sensor signals sl, sr (that is, in this exemplary embodiment, 5sl+5sr) is fed to a separate amplifier stage 302a, b and the evaluation stage 304 has a total of 10 inputs for the amplified sensor signals. Further possible are also mixed forms of the mentioned alternatives.

[0084] As already mentioned, the individual ones of the resistor pairs 28l, 128l and 28r, 128r form series circuits and accordingly voltage dividers. Accordingly, the following holds for the value of the sensor signals sl, sr:

SL=+U*R128l/(R28l+R128l)

SR=+U*R128r/(R28r+R128r)

with [0085] SL: voltage value of the sensor signals sl with respect to ground [0086] SR: voltage value of the sensor signals sr with respect to ground [0087] +U: value of the voltage +u with respect to ground [0088] R128l: value of the sensor resistor 128l [0089] R28l: value of the sensor resistor 28l [0090] R128r: value of the resistor 128r [0091] R28r: value of the resistor 28r.

[0092] Ideallythat is, in particular, without taking into consideration manufacturing tolerancesthe sensor resistors 28l, 28r, 128l, 128r are designed in such a way that their values are then equal in size when the sensor strip 9 is situated without mechanical strains in a plane (such as, for example, in the x-y plane of FIG. 1). Such a state is also referred to here as the resting state. The following then holds:

R28l=R128l=R28r=R128r.

[0093] In such a case, the following then holds as well:

SL=*+U and

SR=*+U.

[0094] When the sensor region S arches backward out of the x-y plane (in the z direction), the front-side resistors 28l, 28r are stretched and the rear-side resistors 128l, 128r are compressed. The effect on the individual resistors is hereby dependent on their angle of inclination as well as on the location and direction of the arching. This is explained briefly with the help of FIG. 1, with it being assumed that the sensor strip 9 is arched uniformly downward perpendicular to the longitudinal axis LA (that is, it does not have any kink, but rather has the shape of a semicircular arch) and the angles of inclination have a value of between zero and 90 degrees. The effect on the individual resistors is then all the stronger, the smaller is the angle of inclination . When, in contrast, there is a uniform arching parallel to the longitudinal axis LA, the effect on the individual resistors is all the stronger, the larger is the angle of inclination .

[0095] In the case of a nonuniform arching of the sensor region S (the extreme case is a kink), the effect on an individual one of the resistors 28, 128in addition to the effect on its angle of inclination is also very dependent on whether and how it is situated in the region of the arching.

[0096] When the sensor region S arches forward out of the x-y plane (in the z direction), the front-side sensor resistors 28l, 28r are compressed and the rear-side sensor resistors 128l, 128r are stretched. When the sensor region S is brought into a wave shape, it is possible for individual ones of the front-side sensor resistors 28l, 28r to be compressed and for others to be stretched.

[0097] When a twisting (torsion) of the sensor strip 9 or of its sensor region S occurs, changes in resistance also arise, which are dependent on the position of the individual sensor resistor 28, 128 as well as on its angle of inclination . When, for example, the lower part of the sensor strip 9that is, the region in the direction of the contact sites 16remains in the plane of the drawing and its upper part is twisted in the clockwise direction corresponding to the torsion arrow TP (FIG. 1), the left front-side resistors 28l are stretched and the left rear-side resistors 128l are compressed. On the right side, in contrast, the front-side resistors 28r are compressed and the rear-side resistors 128r are stretched. The extent of such a stretching or compression is hereby dependent on the angle of inclination as well as also on the characteristics of the substrate. It has hereby been found that, in the case of a relatively thin substrate, corresponding essentially to a film, the resistance values change the most when the angle of inclination has a value of approximately 45 degrees. Of course, such a change is further dependent on how strong the torsion is at the location of the respective resistor. Accordingly, the following can be stated in general: It is possible by way of the angle of inclination to adjust the ratio of the sensitivity of the resistor pairs with respect to the torsion to the sensitivity of the resistor pairs with respect to the bending transverse to the longitudinal axis LA. By way of the combination of at least two differently angled resistor pairs, it is accordingly possible to measure a bending direction that does not extend transverse to the longitudinal axis LA or an overlapping torsion that extends transverse to the bending extending transverse to the longitudinal axis LA.

[0098] When the sensor region S is stretched, this likewise has consequences for the individual sensor resistors. These consequences are dependent on the position and the orientation of the individual resistor as well as on the kind and direction of the stretching. Converse effects arise when the sensor region S is compressed. In the preferred exemplary embodiment, resistors that lie opposite one another, such as the resistor pairs 28l, 128l or 28r, 128r, are similar in design. This means that they have essentially the same geometry and the same material properties. The result hereof is that a stretching of the sensor region S has the same consequences for the oppositely lying resistors and therefore the corresponding values SL, SR ideally do not change. However, if the respectively oppositely lying resistors differ, then, in the case of a stretching, a change in the values SL, SR is possible.

[0099] On the basis of the described examples, it becomes clear that the individual resistance values R28l, R128l, R28r, R128r are dependent on the mechanical influencing of the sensor strip 9 or of its sensor region S. Conversely, it ensues that, in the event that these resistance values are changedand, accordingly, the associated sensor signal value SL, SR is changeda corresponding mechanical influencing of the sensor strip 9 exists. To this end, in the evaluation stage 304, the amplified sensor signals sl, sr are evaluated as a function of the position and orientation of the associated sensor resistors 28l, 128l, 28r, 128r on the basis of a suitable algorithm. To this end, the evaluation stage 304 has conventional elements known to the person skilled in the art, such as a microprocessor, an analog-digital (A/D) converter, memory storage components, etc.

[0100] As described above, the sensor signals sl, sr are each the result of the center tap in the case of a voltage divider having two resistors. It is also possible that, instead of absolute voltages, a differential voltage is measured and processed in each case. Such a differential voltage can be produced, for example, by means of a Wheatstone bridge, in which the reference voltage required for such a differential voltage is usually generated by a suitable second voltage divider. When the value of the first voltagegenerated by one of the voltage dividers 28, 128is now identical in the resting state to the value of the reference voltage, the difference is zero. When, in the subsequent measurement operation, the sensor region S experiences a mechanical movement in such a way that one of the two resistors 28, 128 changes, there is also a change in the value of the tapped voltage. However, this change in voltage can be relativethat is, in relation to the absolute voltage valuequite small. A change in voltage of this kind can be evaluated markedly better when not the tapped voltage as such of the evaluation stage 304 is processed, but rather the differential voltage produced by means of the reference voltage is processed, since the relative change thereof is substantially larger than that of the tapped voltage.

[0101] In an exemplary embodiment in accordance with the invention, the evaluation stage A is designed in such a way that a reference voltage is generated, the value of which corresponds exactly or at least essentially to the voltage value than results from the respective voltage divider 28, 128, such as preferably *+U (see above). Within the amplification stages 302a, 302bbut prior to the actual amplificationthe difference between the sensor signal sl and the reference voltage as well as the difference between the sensor signal sr and the reference voltage are generated. In order to avoid negative voltages, a voltage is added after the amplification in each case, the value of which is preferably *+U (1.5 V). The value of this voltage is again subtracted during the subsequent digitalization, so that also negative digital sensor values can result and can be used already through their sign to draw conclusions about the bending direction.

[0102] The result of the evaluation of the sensor signals sl, sr is output by using output signals sa. This result can be designed in various ways. Preferably, it contains the requisite information in order for the display stage 306, which is equipped with an associated display, to be able to reproduce the sensor strip 9 or, more precisely, the sensor region S graphically. It is hereby also possible for such a reproduction to assume a dynamic time course, which is dependent on the time point of the measurement. For this purpose, the evaluation stage 306 can have suitable memory storage components (not depicted separately) in order to be better able to record and later retrieve such a dynamic reproduction.

[0103] It is also conceivable that the output signal sa and/or the display stage 306 are or is designed in such a way that, in addition to or instead of a graphical display, acoustical and/or haptic (vibrations or the like) alert signals are output when the sensor region S is moved in such a wayfor example, arched, twisted, and/or stretchedthat predetermined threshold values are exceeded. The criteria for such threshold values can be very different. It can hereby also be taken into account when predetermined geometric values of the course of the speed thereof and/or the acceleration thereof are not attained or are exceeded for a certain time.

[0104] As mentioned, the display stage 306 can be designed in very diverse ways. It is also conceivable for it to be arranged to be outside of the evaluation unit A and to be designed, for example, as a PC, a tablet computer, a smartphone, or the like. It is hereby also possible for the algorithm for evaluation of the sensor signals sl, sr to be run in part or in full on such a device.

[0105] The signal conductor 308 can be realized as a cable and/or in a cable-free manner. This means that the evaluation unit A has, as needed, a transmission stage. The latter can be designed in such a way that it can transmit high-frequency signals (for example, Bluetooth, WLAN, etc.), optical signals, acoustical signals, and/or the like. This is especially advantageous in the case when the display stage 306 is realized as a smartphone or a tablet computer.

[0106] The sensor strip according to the invention can be used in diverse ways, such as, for example, in [0107] the field of orthopedics [0108] medical diagnostics [0109] smartwatches and other wearables [0110] life science

[0111] A preferred application in the field of the orthopedics relates to the measurement of the spinal column of a human being. To this end, the sensor strip 9 is placed by suitable means, such as patches, adhesive, or the like, on the back of the human being in question. It is also conceivable that, for this purpose, a kind of clothing piece is used, such as a T-shirt, a body shirt, a vest, or the like, in which and/or on which the sensor strip 9 is arranged or integrated. By way of individual measurements or, better still, by way of ongoing measurements within a certain period of time, it is possible to determine how the back moves and, if need be, how it is subjected to loads. For this purpose, a special embodiment of the sensor strip according to the invention has proven to be especially expedient and will be described below as the sensor strip 900 on the basis of FIGS. 9 to 11. FIG. 9 hereby shows a plan view of the entire sensor strip 900 and FIGS. 10 and 11 show sections B and C thereof, which, in FIG. 9, are marked. The sensor strip 900 also consists of a substrate (not shown here) with a front side and a rear side. On account of the plan view, essentially the elements that are situated on the substrate front side are depicted and the elements that are situated on the substrate rear side and are covered up by the substrate front side elements are not visible here.

[0112] Elements that are identical or similar to those of the previously described sensor strip 9 are given the same reference signs and they will be addressed only insofar as they seem to be required in order to understand the present invention. In addition, reference is made to the above embodiments in regard to the sensor strip 9.

[0113] The sensor strip 900 shown in FIG. 9 has a sensor region S that is approximately 60 cm long. Hereby present on the substrate front side 12, along the longitudinal axis LA, is a front-side strip conductor 18, to the left 28 of which a piece of sensor resistor 28l and to the right of which 28 a piece of sensor resistor 28r are electrically connected. Here, they are also oblong in design and have a nearly rectangular shape and all here have the same angle of inclination , the value of which is approximately 30 degrees. The left sensor resistors 28l are each connected to one of the left strip conductors 26l and the right sensor resistors 28r are each connected to one of the right strip conductors 26r.

[0114] The sensor resistors 128l, 128r arranged on the substrate rear side 14 are situated precisely (or essentially) below the front-side sensor resistors 28l, 28r and are therefore not visible here. Analogously to the front-side sensor resistors 28l, 28r, they are connected, on the one hand, to the rear-side supply voltage conductor strip 120, only a small sectional cutout of which can be seen here above the region 52 (see FIG. 11), and, on the other hand, to the rear-side strip conductors 126l and 126r, which extend on the substrate rear side 14 opposite to or below the left strip conductors 26l or 26r.

[0115] This means that, in the case of the sensor strip 900, a separate strip conductor 26, 126 is provided for each of the sensor resistors 28, 128. Thus, this is different from the case for the sensor strip 9, in which, for each pair of resistors 28, 128, initially one of the vias 200 is provided and afterwards only one of the strip conductors 26r, 126l is provided. The required vias 200 for the realization of voltage dividers from two resistors 28, 128, lying one above the other, are all situated in the case of the sensor strip 900 in a region 902 (see FIG. 11), which is situated in the region of the contact sites 16 and thus inside of the contact region K and accordingly lies outside of the sensor region S (see FIG. 9). Through the arrangement of the vias 200 outside of the sensor region S, which, in normal measurement operation, is usually bent, twisted, and/or stretched, a very robust sensor strip 900 is achieved.

[0116] The sensor strip illustrated in FIGS. 9 to 11 can be shortened in that a desired length is cut off the upper part. In this way, although the number of resistor pairs decreases, the sensor strip length can be adapted to the object that is to be examined.

[0117] In a further exemplary embodiment, which is not illustrated here by figures, it is provided that [0118] the mentioned vias 200 are arranged near to the individual resistor pairs (voltage divider) 28, 128 (similarly to the case of the sensor strip 9), so that, per resistor pair, only one of the strip conductors 26, 126 is required and, furthermore, that [0119] a first number of these resistor pairs 28, 128 are connected via front-side strip conductors 26 and the remaining resistor pairs via rear-side strip conductors 126 to the contact sites 16.

[0120] This affords the advantage that such a sensor strip can be designed to be narrower than the sensor strip 900. However, it needs hereby to be taken into account that, in the case of one-sided contact sites 16 (membrane connectors), additional vias are required.

[0121] Shown in FIG. 12, which is similar in part to FIG. 7, is a further exemplary embodiment. The essential difference from the previously described embodiments consists in the fact that here the front-side strip conductor 251 is connected to the rear-side strip conductor 126l via a first contact element 252 and a second contact element 254 as well as a connecting conductor 256 between the contact elements 252 and 254. For a simple and operationally reliable contacting, the front-side strip conductor 251 extends all the way to a first contact site 251, which is situated in the edge region of the front side 12 of the substrate 10. Correspondingly, the rear-side strip conductor 1261 extends all the way to a second contact site 253, which is situated in the edge region of the rear side 14 of the substrate 10. Preferably, the two contact sites 251, 253 are arranged in such a way that they lie opposite to each other. In normal operation (as also shown here), the first contact element 252 is in electrical contact with the first contact site 251 and accordingly with the strip conductor 251 and the second contact element 254 is in electrical contact with the second contact site 253 and accordingly with the strip conductor 1261. Moreover, the connecting conductor 256 is connected to the evaluation unit A, at which a corresponding sensor signal sl (see also FIG. 8) is emitted.

[0122] It is obvious that the electrical connection shown here between the front-side strip conductor 251 and the rear-side strip conductor 126l by means of the electrical contact elements 252, 254 is only shown by way of example. By way of contacts of this kind and/or similar contacts, it is also possible to connect further ones or even all of the front-side strip conductors to the associated rear-side strip conductors, so that the number of vias 200 can be reduced correspondingly or they can be dispensed with entirely.

[0123] The described exemplary embodiments are only given by way of example and represent preferred realizations of the present invention. It is obvious that specific features, which were described above in connection with individual exemplary embodiments, can also be used in the case of other exemplary embodiments and insofar there are no obvious limitations imposed against them.

[0124] Moreover, diverse variations and alternatives of the described embodiments are possible such as, for example: [0125] The supply voltage +u can be a direct current voltage and/or an alternating current voltage. [0126] The elements that are here referred to as the resistors 28, 128 can also be used as capacitors. To this end, these elements are to be correspondingly connected to the evaluation unit and an appropriate alternating current voltage is to be applied.

LIST OF REFERENCE CHARACTERS

[0127] 9 first sensor strip [0128] 10 substrate [0129] 12 front side of 10 [0130] 14 rear side of 10 [0131] 16 contact sites [0132] 18 strip conductors on 12 [0133] 20 front-side supply voltage connector strip [0134] 22l, 22r left and right contact points on 12 [0135] 24l, 24r left and right contact points on 12 [0136] 25l strip conductor piece on 12 [0137] 26l, 26r left and right strip conductors on 12 [0138] 28l, 28r left and right sensor resistors on 12 [0139] 29l an end of 281 [0140] 50 strip conductor on 12 [0141] 52 region of a via from 50 to 120 [0142] 120 rear-side supply voltage strip conductor [0143] 122l, 122r left and right contact points on 14 [0144] 124l, 124r left and right contact points on 14 [0145] 125r strip conductor piece on 14 [0146] 126l left strip conductors on 14 [0147] 128l, 128r left and right sensor resistors on 14 [0148] 129l an end of 128l [0149] 200 via conductor between 251 and 126l [0150] 251 first contact site [0151] 252 electrical contact element to 251 [0152] 253 second contact site [0153] 254 electrical contact element to 253 [0154] 256 connecting conductor between 252 and 254 [0155] 300 circuit board connector contacts [0156] 302a, b amplification stages [0157] 304 evaluation stage [0158] 306 display stage [0159] 308 signal conductor [0160] 900 second sensor strip [0161] 902 via region [0162] LA longitudinal axis of 9 or 900 [0163] TP torsion arrow [0164] S sensor region [0165] K contact region [0166] A evaluation unit [0167] lal, lar longitudinal axis of a left and right sensor resistor [0168] sl, sr left and right sensor signal [0169] sa output signal [0170] angle of inclination