WO2008122306A1

WO2008122306A1 - Transportable weighing system comprising a weighing device, and method for the production thereof

Info

Publication number: WO2008122306A1
Application number: PCT/EP2007/003312
Authority: WO
Inventors: Ralf Bandorf; Holger Lüthje; Saskia Biehl
Original assignee: Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V.
Priority date: 2007-04-05
Filing date: 2007-04-05
Publication date: 2008-10-16

Abstract

The invention relates to a weighing system comprising at least one weighing device (W) with a sensor array (2) for converting a mechanical load into an electrical signal as well as a measuring instrument (4) for measuring the electrical signal. The sensor array is arranged on a plate-shaped support (1) which is provided with a coating (2) having a piezoresistive material (21) that changes the electric resistance thereof when subjected to a mechanical load. The weighing system further comprises a data evaluation unit (7) in which the measured data is advantageously stored and the weight of an object that is to be measured is calculated.

Description

Transportable weighing system with weighing device and method for its production

The subject matter of the invention is a transportable, modular weighing system which consists of at least one weighing device and a data evaluation unit which can be connected to it. The weighing device has a sensor arrangement for converting a mechanical load into an electrical signal and a measuring device for measuring the electrical signal, wherein the sensor arrangement is arranged on a plate-shaped carrier.

Mobile weighing systems for vehicles, such as lorries or passenger cars, often require large transport capacities for their transport. This is partly due to the size, on the other hand due to the high weight of the weighing systems. In the prior art weighing systems are known, which are modular, the modules but only with heavy equipment, such as forklifts, can be transported. Due to the high weight, such truck scales are by no means flexible.

An advantageous further development of weighing systems for vehicles is that the weighing system consists of individual weighing plates, wherein the weighing plates are equipped with a sensor arrangement. The sensor arrangements have strain gauges. In this case, the sensor arrangement is located within a plate-shaped carrier which is covered by a cover plate. The sensor arrangement has both mechanical and electrical components, and is based on a complicated structure.

Another approach is followed by weighing devices which have a piezoelectric sensor. In the state of

In this case, devices are known in which the piezosensor consists of a piezocable which is inserted into a metal rail. The sensor is designed as a strip sensor, in which it is not possible to capture the entire tire contact surface on the sensor. The signal must be integrated when rolling the tire via the sensor.

Such piezo sensors are installed directly in the road and are either just with the road surface or a little lower. Due to the complicated arrangement of the piezoelectric sensor and the fixed installation in the street, the maintenance of such piezoelectric sensors is very difficult. Furthermore, the size of the sensor structure is already relatively large without its sheathing in the centimeter range. The object of the present invention is to provide a weighing device and a weighing system, which can be designed to be transportable on the one hand and on the other hand have a straightforward and robust construction.

The object is solved by the subject matter of claim 1, the weighing system of claim 13 and the method of weighing objects of claim 15.

A weighing device according to the invention has a sensor arrangement for converting a mechanical load into an electrical signal and a measuring device for measuring the electrical signal, wherein the sensor arrangement is arranged on a plate-shaped carrier. In this case, the plate-shaped carrier has a coating of a piezoresistive material, which changes its electrical resistance under mechanical stress.

The advantage of such a weighing device is that the sensor arrangement arranged in the coating can be made extremely flat. The thickness of the coating can range from a few micrometers to less than one centimeter.

The coating in this case has a piezoresistive material. In particular piezoresistive hard material layers are suitable for this purpose. Such hard material layers can be applied to the plate-shaped carrier by conventional methods. In this case, physical as well as chemical, as well as plasma-based deposition methods are suitable. With the help of these methods, an extremely hard and abrasion-resistant Layering be applied to the plate-shaped carrier.

The piezoresistive layers of hard material are deformed at a molecular level under mechanical stress, which results in a change in the specific resistance of the hard material layers. This change in resistivity can be translated into a mechanical load by means of a force-resistance characteristic.

The coating is in the weighing device according to the invention in connection with a measuring device. This can be integrated both in the plate-shaped carrier and formed as an external module. The measuring device thereby provides a current or a voltage source and builds the piezoresisitive coating as a variable resistor in a circuit. By means of a current or voltage measuring device, the varying resistivity of the piezoresistive coating can be measured and the weight force acting on the layer can be determined by a separate calibration of the device from the change in the specific resistance.

Because the coating and the associated measuring device can be made very light, extremely flat and very resistant to mechanical stress, a high-load weighing device can be produced with a plate-shaped carrier, which has only a small structural height of a few millimeters up to a few centimeters , which due to their small size and low weight easily, for example, in the trunk of a car, can be accommodated. Due to the Fixed connection between the plate-shaped carrier and the coating, in particular with a piezoresistive hard material layer, can also achieve long lifetimes of the weighing device.

Advantageous developments of the weighing device according to the invention are described in the subordinate claims.

An advantageous development of the weighing device according to the invention is when the piezoresistive material is an amorphous carbon compound. Amorphous carbon compounds have the advantage that they have both sp ² and sp ³ compounds. They thus form an intermediate state between graphite and diamond and often combine the hardness of a diamond and electrical properties of a graphite with each other. In this case, amorphous carbon layers can have a specific resistance between a few kΩcm to several MΩcm. Due to the high hardness and corrosion resistance and the proven piezoresistive properties of the amorphous carbon layers, these materials are very well suited to form the piezoresistive part of the coating of the plate-shaped carrier.

An advantageous form of the amorphous carbons as part of the coating of the weighing device are the diamond-like carbon (DLC) materials. DLC is characterized by a high resistivity in the

MΩcm range. On the one hand, DLC has a high hardness and a high corrosion resistance, on the other hand, the coating can already take place at a substrate temperature (for example on the support directly) of less than 150 ^° C. Furthermore, DLC has the advantage that with a targeted doping with different elements positive effects with respect to the temperature dependence of the resistivity can be achieved. This is particularly advantageous when the weighing device is to be used in a wide temperature range. Furthermore, DLC is advantageous because it can be applied using common deposition techniques. There are no special requirements for the coating systems.

A further advantageous development of the weighing device is that the electrical measuring device is connected to an information technology interface. The information technology interface represents an interface between the measuring device and a data evaluation unit that can be connected to the weighing device. With the aid of the information technology interface, the data determined by the measuring device can be stored in a standardized protocol so that the data evaluation units do not have any must have further modifications. It does not matter whether the data evaluation unit is designed as part of the weighing device itself or whether the data evaluation unit forms an external independent unit.

Advantageously, the information technology interface can be connected or connected to the data evaluation unit by radio and / or by cable. In the case of an external data evaluation unit, this only has to be plugged into the weighing device, or be connected to it by radio in order to retrieve the measurement results held in the measuring device via the information technology interface. Advantageously, the coating on the plate-shaped carrier consists of a layer composite. In this case, at least one layer of the layer composite on the piezoresistive material. Depending on the choice of piezoresistive material, as well as the material of the plate-shaped carrier, further layers may be present in the layer composite. Adhesion enhancement layers may advantageously be mentioned here or insulation layers in order to produce an electrical insulation between the plate-shaped carrier and the piezoresistive layer. Although the piezoresistive materials which are preferably used are often very hard and corrosion-resistant, it is advantageous to form an additional protective layer as part of the layered composite.

Advantageously, the coating also has thin-film electrodes. With the help of thin-film electrodes, surprising effects can be achieved. In the case that amorphous carbon layers are used as piezoresistive material, the thin-film electrodes can form a clearly defined contact surface between the piezoresistive material and the thin-film electrodes. As a result, the measurements of the change in resistivity as a function of the mechanical load can be made in a region of the force-resistance characteristic of the piezoresistive layer, in which the characteristic of the material runs almost linearly. This also provides the advantage that when loading and unloading the weighing device, a virtually hysteresis-free sensor can be created, i. The force-resistance characteristic is almost the same with increasing and decreasing load.

Advantageously, on the with a coating tion provided plate-shaped support a cover plate are applied, which covers the coating of the at least one plate-shaped carrier at least in parts. As a result, additional protective effects for the coating can be achieved, in particular in harsh everyday industrial life.

An advantageous development of the weighing device according to the invention is that the at least one plate-shaped carrier has a structuring on at least one side. The structuring is chosen such that elevations are applied to the surface of the carrier provided with the coating, wherein at least the elevations are provided with the coating. The loading of the weighing device primarily stresses the surface of the protruding structurings, which results in improved measurability of the mechanical stress through the coating. In particular, in conjunction with an additional cover layer can be applied in this way a weight applied to a large area of the top of the cover plate, one on a relatively small area, the elevations of the plate-shaped support. The fact that the applied weight is transferred to the small area of the elevations increases the pressure and the accuracy of the measurement.

It is advantageous if the coating with the piezoresistive material is applied only on the surface of the elevations of the plate-shaped carrier. In the case of multiple structuring, the coatings on the individual structuring by a connecting coating, for. Eg in the form of a strip, connect with each other. Advantageously, the weighing device is designed so that the surface of the plate-shaped carrier having the coating has a size between 200 and 20,000 square centimeters, preferably from 600 to 10,000 square centimeters.

Furthermore, it is advantageous if the weight of a weighing device does not exceed 100 kilos, preferably 50 kilos. The advantage of such a weighing device is that it can be easily transported and accommodated in small containers.

In a weighing system according to the invention, at least one weighing device and a data evaluation unit are used. The weighing device serves as a weighing module and the data evaluation unit as a collection point for the measurement data of all weighing modules used. The advantage of such a weighing system is that it can be transported, for example, in the trunk of a car due to the small dimensions and can be quickly assembled and disassembled.

In the inventive method for weighing

Objects at least one weighing device according to the invention is used. In this case, an object to be weighed is applied to the at least one weighing device, so that all bearing points of the object rest on at least one weighing device. After the object rests on the weighing device, the changes in the electrical properties of the piezoresistive material of the loaded weighing devices are measured and the measurements are combined and evaluated to determine the weight of the object. The advantage of such a method is that that only a few minutes can pass between a possible construction of the system and a possible dismantling of the system including the measurement in between. It thus offers advantages over previous systems, which are either permanently mounted or only partially transportable.

Further advantageous developments of the invention are described in the further independent claims.

The weighing device according to the invention, as well as the weighing system and the associated weighing method will be explained in greater detail on the basis of exemplary embodiments.

Show it:

Figure Ia, b, c: Inventive weighing device;

Figure 2a, b, c,: Different embodiments, in particular the coating of a weighing device according to the invention;

Figure 3a, b: alternative embodiments of a weighing device according to the invention;

Figure 4: Schematic structure of a weighing device according to the invention with measuring device and information-technical interface;

Figure 5: Inventive weighing system with multiple weighing devices and Data evaluation unit.

FIG. 1a shows a weighing device according to the invention which consists of a flat, flat, plate-shaped support 1 and a layer composite 2 applied thereon, wherein the individual layers of the layer composite 2 are applied to the planar support 1 by sputtering, vapor deposition or printing processes become .

As materials for the plate-shaped carrier 1 are preferably hard materials to choose, since they are compressible only to a small extent. For example, steel or composite materials can be used. However, in a suitable structure, the plate-shaped support can also be made of softer materials, set the case that the weighing device is placed on a hard, level surface.

The size of the weighing device W is dependent on the object to be weighed. In this case, a single weighing device W may have the size of a DIN A4 sheet or the size of up to 2 square meters. Even smaller weighing devices W are useful if used appropriately.

In Figure Ib, the weighing device W is shown as a rectangular shape, the shape does not affect the success of the measurement. It can clearly be seen that the weighing device W has the layer composite 2 over the entire surface. Because of the planar coating of the plate-shaped support lying below the layer composite 2, an exact positioning of the object to be weighed does not have to be carried out since the sensor arrangement consisting of the layer composite 2 covers large parts of the plate-shaped support covered.

In the figure Ic an easy to be realized embodiment of the weighing device W according to the invention is shown. The weighing device W has a

Base plate 1, on which surface (as shown in Figure Ib), a layer composite 2 is applied with an integrated DLC layer. The composite layer 2 is completely covered by a cover plate 3. Due to the sandwich construction, an improved protective effect for the layer composite 2 is achieved.

A load acting on the surface of the cover plate 3 facing away from the layer composite 2 is transferred via the cover plate 3 to the layer composite 2 and measured as a change in resistance. The pressure transfer to the layer composite 2 is most easily realized with the help of rigid cover plates and / or base plates.

A particularly simple embodiment of the weighing device W of Figure Ic is achieved when both the cover plate and the base plate, both of which are approximately the same size, each coated with a layer composite 2 with a DLC layer and the two DLC layers directly be placed on top of each other. In addition, a measuring device for measuring the change in resistance is connected to the laminations.

FIGS. 2 a to c show various exemplary embodiments of a layer composite 2 according to the invention.

In FIG. 2 a, the layer composite consists of a DLC layer 21 which is disposed on the plate-shaped carrier 1 is applied directly. The DLC layer 21 increasing surface of the plate-shaped support 1 is made of highly polished steel and has no contamination after treatment such. For example, oxidized surfaces. On this surface is the

DLC layer 21 grown by plasma enhanced chemical vapor deposition or physical vapor deposition techniques. On the DLC layer 21, a thin-film electrode 22 is applied. Thus, the DLC layer 21 can be electrically contacted by the metallic carrier 1 and the thin-film electrode 22.

Suitable materials for the plate-shaped support here are in particular carbide-forming metals, such as Al, Ti, Cr, Fe, W, Zr and Mo, since a particularly good adhesion of amorphous carbon layers can be achieved on these metals.

The thin-film electrode 22 applied to the DLC layer 21 in this case consists of Cr / Au and likewise forms a good adhesive bond with the DLC layer.

DLC is a material that is particularly suitable for weighing objects. On the one hand, the vapor-deposited layer 21 is very hard, on the other hand inert to chemicals, ie in particular corrosion-resistant. The use of other amorphous carbon layers is also possible. Thus, carbon layers are also possible which have no hydrogen compounds or which are doped with additional metals in addition to the carbon-hydrogen compounds. Thus doped DLC layers have z. For example, improved properties with respect to the temperature dependence of the electrical resistance coefficient of the DLC layer. An alternative embodiment of the laminar composite 2 is shown in FIG. 2b. Here, the plate-shaped carrier 1 also consists of a conductive material. An insulating layer 23 is applied directly on this. With the aid of the insulating layer 23, the electrically conductive carrier can be electrically decoupled from a change in resistance of the DLC layer 21 to be measured. In this case, a thin-film electrode 22 is applied to the insulation layer 23, for example in the form of Cr / Au, onto which in turn the DLC layer 21 is applied, which is likewise contacted with a thin-film electrode 22 '.

The arrangement shown in FIG. 2b is, in particular, a good layer composite arrangement when the support occupies a much larger area than the layer composite on the support. In this way, electrical losses occurring due to the carrier (for example due to long conduction paths) can be avoided, and a voltage to be measured or a current to be measured can be tapped directly at the thin-film electrodes 22 and 22 '. Furthermore, with the aid of the thin-film electrodes depicted in FIGS. 2 a and 2 b, a linearization of the force-resistance characteristic of the DLC layer 21 can be achieved.

Due to the fact that the thin-film electrodes 22, 22 'have a defined contact surface with the DLC layer, only a small extent results in a so-called contact surface effect. The contact surface effect occurs in particular when only parts of the DLC layer are loaded with a weight, ie the pressure only on a local area section of the DLC layer works. This is the normal case, since the amorphous DLC layer has a certain surface roughness. An electrode not following the contours of the DLC layer would therefore touch only the tips of the rough surface. As the load increases, this electrode would be pressed against the DLC layer until full-area contact between the electrode and the DLC layer is achieved. In this "pressure range" of the force-resistance characteristic of the DLC layer 21, the resistance of the DLC layer changes even with very small force changes. Only when the pressure on the DLC layer 21 has become so great that elastic deformations on the macroscopic and microscopic level of the DLC layer 21 occur (ie a full-area contact between the electrode and DLC layer is produced) does a linearization occur the force-resistance characteristic. Since the surface effect can almost be eliminated with the aid of thin-layer electrodes 22, 22 '(since they already adapt to the contours of the DLC layer during application), not only can a measurement be made in the region of the linear portion of the force-resistance characteristic curve, but also hysteresis-free loading and unloading of the sensor arrangement formed by the layer composite 2, which in turn greatly simplifies the measurement of the change in resistance.

FIG. 2 c shows a further embodiment of the laminar composite 2. In FIG. 2c, the plate-shaped carrier is made of a hard, insulating material. On the insulating material, a thin-film electrode 22 is applied. In this case, the thin-film electrode 22 is made of a material which can not be connected to the desired extent with the DLC layer 21. For this purpose, an adhesion-improving layer 24 is applied, which consists for example of transition metals such as chromium or titanium. With the aid of the adhesion-improving layer 24, the DLC layer 21 can be adhered to the laminate 2 and adhered to the thin-film electrodes 22, 22 '. This is a useful measure, in particular when improving the conductivity of contacts with silver or gold.

On the DLC layer 21, a further adhesion enhancement layer 24 'is applied, on which in turn a thin-film electrode 22' is applied. The layer composite is terminated by an insulating layer 23 ', which is intended to electrically insulate the underlying layer composite against external influences on the one hand, and on the other hand provides improved protection for the thin-film electrode 22'.

In FIGS. 1a and 2a to 2c, the various layers of the laminar composite 2 are not shown to scale. The DLC layer may have a thickness of 0.01 to 20 microns, preferably 3 to 6 microns. The adhesion enhancing layer 24, 24 'need not be thicker than several tens to hundreds of nanometers (depending on the thickness of the DLC layer) to achieve improved adhesion of the DLC layer and the thin-film electrode or support. In the field of thin-film electrodes, various thicknesses are conceivable which, depending on the material, can be between 0.02 and 20 micrometers.

FIGS. 3 a, b show an alternative embodiment of the weighing device according to the invention. In FIG. 3 a, a plate-shaped carrier 1 can be seen, which has a structuring formed as extensions 11, 11 '. It is in each case a layer composite, wherein different layer composites can be connected to each other via electrical contacts on the surface of the extensions 11, 11 'applied. The cover plate 3 in conjunction with the extensions 11, II ¹ , and the layered composites 2, 2 'lying thereon has the result that a pressure which on the side facing away from the layer composite Cover plate 3 is applied is transferred to the laminates 2, 2 '. In this way, the layer composite can be applied to the plate-shaped carrier in a very efficient and economical manner, without diminishing the measuring accuracy during weighing.

The layer composites 2, 2 ¹ represent defined contact surfaces on which a pressure applied to the cover plate 3 can be measured. Since most amorphous carbon layers and in particular DLC layers measure a pressure, it is advantageous if a weight applied over a large area on the side of the cover plate 3 remote from the DLC layer is applied only to a few extensions 11, II ¹ .

In the figure 3b, the arrangement of Figure 3a is seen in plan. In this case, the cover plate 3 is shown and by the hatched lines three stamp-like located on the underside of the cover plate 3 continu- sets 11, 11 ', II ^{1 1} . Between the extensions 11,

11 ', II ¹ ' and the cover plate 3 is in each case a layer composite 2, 2 ', 2 ^{1 1} . It is possible for the layer composites 2, 2 ', 2 ^{1 1} to be connected to one another directly, ie, by a narrow composite composite strip applied between the extensions 11, 11' and II ^{1 1} . The structuring with the help of the extensions 11, II ¹ and 11 '' can be adapted to the application of the weighing device. Thus, the extensions 11, 11 ', II' ^{1 may} also be rectangular or formed as a strip or as a cone, if offered by the object to be weighed. The layer composites are arranged at least on the extensions.

FIG. 4 shows a weighing device W, wherein the thin-film electrodes 22, 22 'of the laminar composite 2 are connected to a measuring arrangement 4 via the contacts 5. With the aid of the measuring arrangement 4, the change in resistance of the DLC layer 21 induced by an applied pressure F can be measured by means of a voltage source or a current source via a further connected measuring device, which is arranged within the measuring arrangement 4. Whether current or voltage is measured in the measuring unit depends on whether the amorphous carbon layer 21 has a very high or a very low specific resistance.

The measuring arrangement 4 can be accommodated inside the plate-shaped carrier 1. However, the measuring arrangement 4 can also be formed as an additional module, which is designed to be removable and thus allows for improved maintenance by the user. One way of evaluating the measurement result is that in the measuring arrangement 4, a measuring device visually displays the voltage or current change, so that the user can read this value and transmit it to a data evaluation unit. Of course, the data evaluation unit can also be designed in conjunction with the measuring arrangement 4, so that the measurement result of the measuring arrangement 4 is converted directly into a weight value, which can then be read on the individual weighing device.

In FIG. 4, the measuring arrangement 4 is connected to an information technology interface 6. In this case, the information technology interface 6 benefits from the task of preparing the data measured by the measuring arrangement 4 in such a way that it can be transmitted by conventional data transmission methods to a data evaluation unit which is executed in the weighing device W or externally on the weighing device W.

5 shows an exemplary weighing system according to the invention with four weighing devices W, W ¹ , W ^{1 1} , W "and a data evaluation unit 7. The weighing devices W, W ¹ , W ^{1 1} , W ' ^{1 1 are} connected via the respective information technology interface 5, 5 ', 5'',5'^'■ connected to the data evaluation unit. 7

The connections 8 can be made by cable or cable. Also, a manual readout of the measurement data of the weighing devices W, W ¹ , W ¹ , W ¹ "is possible with a corresponding device to the weighing devices.

In the weighing system according to the invention, for example, a truck with two axes so on the weighing devices W, W ¹ , W ¹ ', W "driven so that all tires directly on a weighing device for

Come stand up. By measuring the change in the electrical resistance of the individual piezoresizive layers of the weighing devices, the total weight of the truck is determined in a data evaluation unit 7. Both the raw measurement data of the measuring device 4 and also already evaluated data (with an internal Datenauswerteein- unit of the weighing devices W, W, W ', W'') are calculated and displayed in the data evaluation unit 7.

In the method according to the invention, the individual weighing devices W, W ¹ , W ¹ ', W "are positioned at suitable spatial distances from each other and aligned so that, for example, a motor vehicle or an aircraft can ride on the weighing device, that the entire weight through the plurality After the object has been positioned on the individual weighing devices, the electrical resistance changes of the individual weighing devices in the data evaluation unit 7 are combined and calculated.

With the weighing devices according to the invention and the weighing system according to the invention thus a modular, transportable high load weighing system is created. In this case, the particularly low overall height (in the centimeter range or smaller) of the individual weighing devices W, W ¹ , W ¹ , W "is advantageous, because of the materials used of the weighing device and the sizes used, a system is created which is light in the boot This makes it especially suitable for road traffic monitoring and the control of maximum permissible weights.

Further use is possible in the field of load distribution measurement. Since the weight acting on each contact point of an object to be measured can be determined, an imbalance-generating

Load distribution (eg load of a truck) avoided and so the traffic safety can be increased.

Claims

claims

1. weighing device with a sensor arrangement for converting a mechanical load into an electrical signal and a measuring device for measuring the electrical signal, wherein the sensor arrangement is arranged on a plate-shaped carrier, characterized in that the plate-shaped carrier (1) has a coating (2) with a piezoresistive material (21) which changes its electrical resistance under mechanical stress.

2. Weighing device according to one of the preceding claims, characterized in that the piezoresistive material (21) is an amorphous carbon compound.

3. Weighing device according to claim 2, characterized in that the amorphous carbon compound has hydrogen-containing formations (DLC).

4. weighing device according to one of the preceding claims, characterized in that the plate-shaped support (1) has at least one information technology interface (6), wherein the information technology interface

(6) is connected to the electrical measuring device (4), and the information technology

Interface (6) with a data evaluation unit

(7) is connectable.

5. Weighing device according to claim 4, characterized in that the information technology interface (6) by radio and / or cable to the data evaluation unit (7) is connectable.

6. Weighing device according to claim 4, characterized in that the data evaluation unit (7) is arranged in the plate-shaped carrier.

7. Weighing device according to one of the preceding claims, characterized in that the coating (2) consists of a layer composite (2) and at least one layer (21, 22, 22 ', 23, 24, 24') of the layer composite, the piezore - Sistive material (21).

8. Weighing device according to one of the preceding claims, characterized in that the coating (2) has thin-film electrodes (22, 22 ').

9. weighing device according to one of the preceding claims, characterized in that on the plate-shaped support (1) facing away from the surface of the coating (2) a cover plate (3) is applied, which covers the coating (2) at least in parts.

10. Weighing device according to claim 9, characterized in that the cover plate has a coating with a piezoresistive material.

11. Weighing device according to one of the preceding claims, characterized in that the at least one plate-shaped carrier (1) consists of a flexible material.

12. weighing device according to one of the preceding claims, characterized in that the at least one plate-shaped carrier (1) and / or the coating (2) on at least one side structuring (11, 11 ', II ^{1 1} ).

13. Weighing device according to one of the preceding claims, characterized in that the at least one plate-shaped carrier (1) has a thickness of less than 10 cm and / or an areal extent of less than 2 m ² and / or a weight of less than 100 kg having.

14. Weighing system comprising a data evaluation unit (7) and at least one weighing device (W) as

Weighing module for weighing objects, wherein the object has at least one support point, characterized in that the weighing device (W) satisfies one of claims 1-12.

15. Weighing system according to claim 14, characterized in that the measurement data of the at least one weighing device (W) are stored in the data evaluation unit (7) and the data evaluation unit (7) calculates the weight of an object located on the at least one weighing device (W) ,

16. A method for weighing objects, comprising at least one weighing device according to one of claims 1 to 13 as a weighing module, comprising the following steps:

a) applying an object to be weighed on the at least one weighing device (W, W ¹ , W ¹¹ , W ¹ ''), so that all bearing points of the object rest on a weighing device; b) measuring the changes in the electrical properties of the piezoresistive material of the loaded weighing devices (W, W ¹ , W ¹ ', W ¹ "); c) determining the weight of the object from the individual electrical property measurements per weighing device.

17. The method according to claim 16, characterized in that prior to the application of an object to the at least one weighing device (W, W, W ¹¹ , W ¹ ' ¹ ), the at least one weighing device is designed.

18. The method according to any one of claims 16 or 17, characterized in that after measuring the electrical properties of the at least one weighing device (W, W ¹ , W ¹¹ , W ''), the measured values by cable and / or by radio to a Data evaluation unit (7) are transmitted.