DE4410705A1 - Temperature measuring error compensation method for electrical sensor e.g. strain gauge - Google Patents

Abstract

Errors in the electrical signals from passive or active sensors, due to their temperature dependency, are compensated by measuring the temperature level in which the sensor is situated. The electrical sensor signals are then processed to compensate for measurement errors due to temperature conditions at the sensor. The signal processor (13) and sensors (8,9) are maintained at the same temperature level by linking them with a supporting thermoconductive foil (4). The sensors, processor and signal transmission paths are screened and protected from any electrical interference. The thermometer (7) includes a resistor in a Wheatstone bridge circuit and the signal processor includes amplifiers, a programmed digital processor and storage device.

Description

The invention is concerned with the electronically exact measurement of measured variables different types, which are recorded with sensors, the properties of which are not are negligibly influenced by the temperature level of the sensors.

When using singular functional system components for measuring sections, the Locations of signal generation, the frequently required signal amplification and the Signal processing and the evaluation and calculation of several signals with each other necessarily spatially separated. A measuring section can be as a result of its functional units represent:

The sensors are technical components that consist of a physical non-electrical measurement signal generate a unique electrical signal. The task of the sensors is to provide information to deliver measured quantities and these in a suitable form for the electronic To provide further processing and evaluation.

The mostly weak electrical signals have to be shielded by longer cables Distances (from often several meters up to the order of 100 meters) to the location of the Signal processing (linearization, amplification) are transmitted.

As a rule, this takes place in standardized, universally applicable electrical modules the global name "measuring amplifier". These modules with performance features of a higher quality class are not small in size, weight and volume, and not small Price off. As a rule, these devices are designed for use under laboratory conditions are therefore without additional protective measures under "harsh conditions" or under "Special conditions" (extreme cold or heat, fluid environment etc.) cannot be used.

The processed signals are possibly a combinatorial circuit or a computer fed for further evaluation (display, calculation, storage).

Due to the mostly different temperature levels of the components and the different temperature characteristics result overall in the construction of the measuring circuit inevitably an influence of the disturbance variable "temperature", which the signal of this measuring circuit in no longer falsified in a negligible way.

The error of a signal caused by the influence of a temperature (change) is therefore not constant, but depending on the current temperature levels.

The different temperature characteristics of the system components result in same starting temperature T₀ of the components each different Response behavior of the measurement signal to small temperature changes ΔT of an individual Component.

Since the system components are usually in a three-dimensional temperature field are usually with inhomogeneous heat distribution, which is z. B. by the Heat emission from built-in power supplies or the influence of drafts in the room changes uncontrollably, with such an arrangement no accurate measurement in done reliably.

When designing a measuring system, however, the goal must be accurate, reliable measured values over a wide temperature range and not only at singular temperatures to obtain.  

Many of the signals S _i resulting from the use of a measuring sensor can generally be described by an ideally already sufficiently simplified linearized term of the form:

A _i = F _{(E0) *} [1 + α _{20i *} (T _2i -20 ° C) + β _{i *} (y _2i -y _1i ) + Σx _{i *} (n _2i -n _1i )] - _* E _i

Are in here

A _i output signal of the i-th sensor,
E _i input variable = measured variable i,
F _(E0) function of the measured variable; ideally a constant or a Taylor function (Taylor line) that can be linearized sufficiently at least around an operating point Espunkt,
α _{20i influence} number, temperature coefficient f. Standard temperature,
(T₂-20 ° C) deviation of the actual temperature from the reference value (standard temperature),
β _i mechanical influence number,
(y _2i -y _1i ) deviation of the mechanical influencing variable from its reference value,
x _i other influence number,
(n _2i -n _1i ) Deviation of the associated influencing variable from the respective reference value.

In almost all cases, the temperature level T _{i of} the sensor influences its relevant properties (e.g. specific electrical resistance, electrical or magnetic permeability) in a manner that can no longer be neglected. The generation of a desired or at least constant temperature level at the measuring point is impossible or uneconomical in most cases.

Some sensors are also influenced by mechanical parameters (pressure, strain), this particular size may well be the goal of the measurement. Especially in these cases, in to whom the temperature is not the actual measured variable, it is important to influence to eliminate the resulting measurement signal.

Techniques for compensating for the influence of temperature have been developed. For example, the use of measuring bridge circuits, which is often necessary for other technical reasons (e.g. minimum magnitude of the signal emitted by the sensor while simultaneously eliminating the offset), creates the prerequisite for compensation in that several sensors of the same type are connected to form a measuring circuit which all are exposed to the influence of the respective local temperature level T _i . Appropriate interconnection of the signals S _i attempts to achieve compensation in that the signal component which tends to be the same or at least of the same kind and which arises from the influence of a general temperature rise at all locations O _i is emphasized.

If mechanical quantities are to be measured, then measuring bridges are used to ensure that passive supplementary sensors are not mechanically stressed when they are Purpose of compensating for the temperature error caused by different temperature levels the active and passive sensors are created, brought close to the active sensors.

Basically, when using measuring circuits between active components, the in addition to the disturbance variables are subject to the actual measured variable and the passive ones Supplementary components are distinguished.  

For the construction of measuring circuits u. a. following global demands regarding the Summarize the load on the sensors:

• - The active components should be influenced most by the size to be measured Experienced. Anything other than the quantity to be measured is a disturbance variable; their influence should be as small as possible.
• - The passive additional components should not be influenced by the one to be measured Experience greatness. They should be exposed to the disturbance variables in as identical a manner as possible like the active components.
• - The influence of disturbance variables on the components of the measuring circuit must be possible as a whole be kept low.

In general, each individual component of a real measuring section is dependent on the temperature; this dependency, which can be described by a temperature characteristic curve, must be taken into account for correct measurements. A temperature characteristic or a temperature function F _i (t _i ) can thus be assigned to each individual component of a measuring section. The block diagram of conventional measuring sections always has several functional blocks, each of which has such a temperature characteristic F _i (T _i ); when calculating the transmission behavior of the overall system (characteristic curve), all individual temperature characteristic curves F _i (T _i ) must be taken into account. If n system components are present, n different temperature levels at which the system components are located must therefore be taken into account in accordance with their respective characteristic curve. This leads to a function of n + 1 variables.

S = F (measured variable X, T₁ ... T _n )

According to the prior art, in practice the k system components can be subjected to a so-called thermal stabilization, which keeps them at a common temperature level. At best, it is possible in this way to bring k = (n-1) system components, namely, all the components except for the sensor, to a uniform temperature level T _{stabilized n-1} = T, so that the signal of the electrode with

S = F (measured variable X, T _sensor , T _stabilized )

is described; in addition to the actual measured variable, it depends on two different temperature levels from.

The signal is due to the associated transition into the three-dimensional display space no longer able to compensate for the effects of temperature, especially below Appreciation of the fact that in most cases the temperature characteristics of the individual System components are not known or have to be obtained with great effort.

These measures already mean an increased technical effort. Use of Energy and matter and usually increased volume and weight.

In all experiments, the construction of measuring sections with regard to the effects of thermal and mechanical influences, other known influences that affect the Affect the quality of the signal, also be taken into account. These are:

• - Protection against electromagnetic interference at the point of signal generation and on the Transmission link,
• - ensuring good electrical insulation and contacting,
• - Compliance with the criteria for wired signal routing
  same cable type, same cable length, same cable routing.

Usually one tries by application-specific use of various shields along the signal transmission paths and at the locations of the signal generation, the influence of these To minimize interference.

Disadvantages with the usually spatially dispersed positioning of the components:

• - The electromagnetic field is generally a function of the location. From this it can be deduced that spatially dispersed components are influenced differently.
• - There is a separate shield for each sensor and each transmission path required for this required.  
• - The longer a transmission link with the same signal strength, the higher The shielding must meet requirements. That means additional effort Weight, volume and costs and limits manageability.

The requirement for minimal influence of measurement results by the whole the disturbances, particularly the temperature, can be used using conventional ones Components are not complied with. At least high demands can be placed on the Quality of measurements in this way is not without special measures, which additional effort in weight, volume and material mean and the Reduce manageability and thus usability of the measuring sections, satisfied become.

In practice, one has come up to the requirement regarding the maximum influence of the active sensors by the measurand with the choice of a type and design for the Measurement of suitable sensor. Ideally, the same components, against the influence isolated from the actual measured variable, also used as passive additional components.

The requirement for minimal influence by all the disturbance variables, the temperature in particular, on the other hand, cannot be easily met.

Due to the usually different temperature levels of the components in current practice As shown, there is an overall influence of the disturbance variable in the construction of the measuring circuit "Temperature", the signal of this measuring circuit in a way that is no longer negligible adulterated. The compensation of this influence is often not or only with a lot of effort realizable.

The cause of this interference is, as also shown, mostly due to the Boundary conditions of the application forced spatial distance of the sensors in Connection with a non-zero temperature gradient.

The well-known compensation method for the application of passive additional components or sensors on the same material as the active sensors ("application of all sensors on same material ") to compensate for the influence of temperature is particularly useful for measurements mechanical sizes are only effective in practice with considerable technical effort realizable.

When measuring mechanical quantities, one turns out to be "somehow" realized assumed solution to the problem just described "cancellation of the spatial Separation of active and passive components "another:

The spatial distance of the passive to the active sensors is measured mechanical parameters to the constraint, otherwise the passive sensors subject to the same mechanical influence as the active, which z. B. with a measuring bridge an incorrect measurement or even the compensation of the measured variable itself.

The presented invention, as characterized in the claims, solves the described technical problems by combining the following approaches:

The method according to the invention assigns the true value to the measured signal of one (or more) freely selectable, but implementation-dependent measured variable, which is associated with a measurement error due to the influence of the temperature. The true value is free from temperature errors and takes the place of the measured signal when the measured value is output.
Using one of the principles described below ensures that all components have a uniform temperature level, namely the level T _{AO of} the surface to which the unit was applied. Thus, in addition to their actual measured variable, the signals of all implemented measuring circuits are only influenced by precisely this one temperature T _AO (reference to application P 43 25 782.8-52).
The measuring circuit for measuring the temperature thus supplies a signal F (T _AO ) which is not dependent on any other parameter. The absolute and precise measurement of the temperature of all the components obtained in this way enables the temperature error of an entire measuring chain to be compensated for without additional measures. The signal can thus be written to

S = G (measured variable X, T)

When measuring mechanical quantities, the invention solves the problem of complete thermal coupling with simultaneous complete mechanical decoupling of the active At least sensors from the passive supplementary sensors in a measuring circuit largely.

A satisfactory elimination of the temperature influence from the measurement result by mutual compensation of the influences on the individual signals S _i that arise at the locations O _i is best achieved by eliminating the causes.

The influence of the existing temperature gradients and the spatial distances between the Sensors on the signal of the circuit can be described globally with:

K _* δT / δx _* dx = K _* ΔT = Δs

Are in here

K sensor-specific temperature coefficient,
δT / δx temperature gradient,
dx spatial distance of the sensors,
ΔT temperature difference,
Δs temperature-related error in the output signal.

The requirement ΔT = min is met by the invention

• - Minimization of the spatial distance dx of the sensors by application (almost) on the same place,
• - Minimization of the temperature gradient δT / δx by optimizing the thermal Contact between all elements of the circuit.

The principles of the mentioned minimizations are already in the application P 43 25 782.8-52 described. The effect of the invention is independent of the type of sensors and selected thus regardless of their specific temperature coefficient K. Even sensors that despite otherwise excellent metrological properties due to their increased thermal Sensitivity rarely applied can be done very easily with the help of the invention be used. The semiconductor strain gauges are a concrete example of this.

• - The removal of the spatial separation of the components of the measuring circuit except for the absolutely necessary measure fulfills the condition ΔT = min.
• - Establishing the availability of the integration of several common components into a single, closed unit, subject to miniaturization, Encapsulation and shielding.

The invention is also a very compact, according to industrial requirements in everyone Regarding robustness and usable in wide temperature ranges without influence on accuracy Measuring system with integrated power supply and signal processing, which together with The integrated but freely selectable sensors depending on the implementation as closed Unit is applied at the desired location of the signal generation.

Due to the principles described, all technical effort for the usual is eliminated thermal stabilization.  

In summary, the invention uses two approaches:

• - Basic problem solving through preventive measures / avoidance of Problem development.
• - Integration of the functions of several common components / Manufacturing units into a single, closed manufacturing unit under the Requirement for miniaturization and encapsulation.

This combination enables

• - a closed production and setting / calibration at the factory,
• - one in terms of operational safety, intended use, cost, weight and Volume-optimized measurement facial expressions.

Common systems can at best meet these criteria individually, but not in total correspond.

An autonomous, extremely compact measuring unit for measuring one is obtained Any combination of measured variables and the measured variable depending on the implementation "Temperature" with optimal compensation of the temperature influence even in rough conditions Industrial environment and large temperature ranges. The unit is great even at large Temperature fluctuations can be used in a short time for highly accurate measurements. Through the integrated power supply, it can be operated without being connected to the environment.

The integration of all components in the very compact unit eliminates long transmission distances between the functional blocks of the electrode together with their principle-related Disadvantages.

The principle of the invention, despite utilizing all the advantages, does not place the user at all Restrictions in the selection of the measuring circuit.

The economic advantages are as follows:

• - cost reduction:
  In the case of series production, a considerable reduction in costs can be expected in comparison to a conventionally constructed circuit.
• - Extended areas of application:
  It can also be measured in cases in which a measurement has so far not been necessary for cost reasons; in particular area measurements with a large number of measuring points are affordable.

Technically, there are the following advantages:

• - A constant compensation of the thermal influence.
• - The construction was chosen so that all components of the measuring unit are always on are at the same temperature level. This requirement was realized by the Minimization of the temperature gradient by means of good thermal contact between the locations of application of the sensors on the one hand and by minimizing the spatial distance on the other hand. As a result, the thermal stresses of everyone Components the same.
• - Tolerances and measuring accuracy:
  Manufacturing from a single source enables the final inspection of the entire measuring system by the manufacturer. That is why it is possible to maintain tighter tolerances than usual. It is possible to create the technical prerequisites for several high-precision measurements in an extremely small space and light weight.
• - Constant, automatic compensation of thermal influences:
  Due to the spatially compact arrangement of all modules, common problems in signal transmission are largely eliminated from the start. With additional use of the effect of thermal coupling, a uniform temperature level is generated between all assemblies. Only in this way can the described, in principle known method for compensating the measurement errors resulting from the influence of the temperature be used effectively.
• - The temperature measurement described in principle is always available as a measurement signal to disposal.
• - Minimizing the length of the transmission paths:
  The transmission paths for singular units, which are usually several meters in length, are shortened to a few millimeters to centimeters without competition.
• - Minimize the number of transmission paths.
  The number of transmission links required is reduced by eliminating the spatial separation between primary and secondary signal processing or signal processing.
• - Largest identity of the transmission channels:
  The requirement for wired signal routing for the same cable type, the same cable length and the same cable routing is fully met by using the conductor tracks integrated on the carrier film.
• - Optimization of the contact points:
  The occurrence of transition voltages cannot be avoided even with the measuring unit. However, since it is a complete circuit from a single source, the usual requirements for symmetrical circuit design with regard to the number of contact points and for "same" conductor material can be at least optimally met.
• - Minimize the weight and volume of the transmission paths and optimize their handling:
  Obviously, very light, small-volume transmission paths result from the use of the carrier foils. The problem of their handling is eliminated since they run inside the closed unit.
• - Shielding against electromagnetic radiation (environmental influence):
  A largely closed metal housing, which can be made very thick if required, takes on the task of electromagnetically shielding the entire measuring arrangement and preparation (Faraday cage). Additional grounding of the housing is possible.
• - Protection against large mechanical loads through massive, uninterrupted Housing is possible.
• - Protection against moisture, dirt and chemical influences (environmental influence):
  Said housing can be sealed against the application surface in a fluid-tight manner (liquids and gases), for example, by using any adhesive or seal. Measurements in a fluid environment (e.g. under water), even at higher ambient pressures, are possible; the high ambient pressure strengthens the seal.
• - Easy handling of the measuring unit:
  Even the measuring unit that has not yet been applied is completely watertight and very insensitive to handling.
• - By creating two clearly separate areas that are mechanically decoupled are, it is possible to use all components of a measuring circuit (sensors and passive Components) to apply and interconnect on a common film.
• - Optimized measuring electronics without external energy supply:
  The measuring electronics are built in hybrid technology in miniature form in a circuit adapted to the respective measuring sensor. This ensures minimum values in size, weight and energy consumption.
  This makes it possible to supply the measuring unit with energy for a reasonable time by means of built-in rechargeable batteries.

Many of the described, usually using conventional, singular Components mostly caused by different manufacturers can be solved this way by integrating the functionally required units into a compact unit (one Avoid in the approach or at least significantly reduce it.

The interaction of the various functional blocks can already take place during manufacture be optimized. This allows good and reproducible parameters when used in the Practice can be guaranteed.

For the user, the implementation of the measurements becomes a result of the elimination of handling problems easier.

By dispensing with an external energy supply, an energetically autonomous measuring system became created as it does not yet exist with the attainable accuracy.

By using the invention in the form described, the following results in particular Possibility:

• - Inexpensive composite measuring system:
  According to the idea of the modular principle, a variety of problem-oriented measuring systems can be put together by connecting several units (taken from a relatively small selection of implemented internal measuring sections).

The invention will be presented using the example of a measuring system for measuring mechanical Stretches in two or more directions. Strain gauges are used as sensors (DMS) used.

Except for the sensors, the mechanical structure of the system and the hardware and hardware used remain Software largely unchanged even when measuring other sizes.

In the drawing, on the basis of which the exemplary embodiment is described, shows

Fig. 1 shows a cross section of the embodiment,

Fig. 2 is a block diagram of the embodiment.

The measuring unit shown has the following main mechanical components:

• - housing 1 ,
• Multilayer board 3 , equipped with electronic components 5 ,
• - flexible carrier film 4 with already integrated measuring sensors, including a measuring circuit for measuring the temperature (reference to registration P 43 25 782.8-52),
• - molded part 6 made of rubber or elastic plastic,
• - solid casting compound 2 .

The housing 1 is made of metal and serves as a closed shield for all components. In order to ensure maximum mechanical strength in the event of impacts and vibrations, the empty space between the upper side of the multilayer board 3 and the housing 1 is filled with the solid sealing compound 2 (for example EPOXY or a similar material). The result is great resilience and overall very good protection of the electronic components.

The all-round groove for sealants 11 guarantees a hermetic seal of the system against all external influences to be assumed.

The multi-layer circuit board 3 carries the electronic assemblies necessary for signal amplification, calculation, correction and programmable evaluation, as well as the power supply.

The carrier film 4 consists of flexible carrier material and is provided by the manufacturer with conductor tracks and with measuring sensors that are completely connected to form measuring bridges for the measuring tasks. The carrier film 4 grows out of the multilayer board 3 as a flexibly held lower layer. The contact between the layers (including the carrier film 4 ) and the application of the components on the carrier film 4 are realized using proven technologies. The following measuring circuits are implemented:

• - Circuit for measuring the temperature with resistance thermometer 7 :
  A Wheatstone bridge is used.
• - Circuits for measuring mechanical strains in two directions:
  For this purpose, a Wheatstone measuring bridge with two active 8 and two passive DMS 9 is used for each measuring channel.

The carrier film 4 has two functionally separate areas that are thermally coupled but mechanically decoupled. The upper ( Fig. 1) area 4 a remains mechanically unloaded and carries the measuring bridge of the resistance thermometer 7 and the passive supplementary half bridges 9 of the measuring bridges for measuring the mechanical strains.

The lower ( FIG. 1) area 4 b carries the active half bridges 8 of the measuring bridges for measuring the mechanical expansions of the application surface, which are applied to the spring body to be measured using a slightly modified conventional method.

The molded part 6 made of rubber or plastic simultaneously fulfills several tasks:

• - Transfer of the mechanical pressure required when the measuring unit is applied the application areas of the strain gauges,
• - spacers between the two parts of the carrier film,  
• - Hermetic sealing of all components from the environment (first stage of sealing).

The assembly of the entire measuring unit and the strain gauge application fall into one.

The application process of the active strain gauges 8 on the spring body takes place under mechanical contact pressure; the molded part 6 , due to its design, shape and material properties, deforms elastically during the application of the pressure in such a way that it distributes the applied pressure evenly to the active strain gauges 8 to be bonded. Thus, the measuring unit is applied by the user to the spring body or the carrier material using proven technologies.

When the load is released, the molded part 6 returns to its original shape and thus provides the passive supplementary strain gage 9 with the necessary space for its mechanical decoupling.

The cavity remaining between the components is filled with a viscous viscous mass 10 , which takes on two tasks:

• - Creation of a very good thermal contact between the active and the passive Sensors to minimize the described disturbances due to thermal influences,
• - Floating, damped mounting of the passive additional sensors for measuring the mechanical strains and the measuring bridge for temperature measurement; this part of the Carrier film remains completely unstressed mechanically.

The viscous viscous mass thus generates a uniform temperature level between all components including sensors 7 and 9 and 8 and mechanically decouples the two areas 4 a and 4 b of the carrier film with the respective sensors.

Due to the compact design, all components are spatially very close together thermally very well coupled due to the viscous viscous mass. Therefore, there is a uniform Temperature level in all modules; the described requirement:

S = F (X, T)

for the compensation of the temperature error by means of the method described in signal S this becomes possible.

The entire unit has exactly one temperature characteristic for each individual measured variable. These characteristic curves are determined exactly at the factory and stored in map memories 14 and 15 .

At the output of the circuit for measuring the temperature, a signal T _RD (after digitization in FIG. 13 ) is assigned the true value T from the map memory 14, possibly with the aid of interpolations; This means that the current temperature operating point of the entire unit can be precisely determined at all times. At the same time, the signal is linearized.

With the precise temperature operating point as basic information, a further circuit is able to assign the true signal value S to a measured signal X _RD (after digitization in FIG. 12 ) by selecting the appropriate temperature characteristic curve and, if necessary, with the aid of interpolations using the map memory 15 .

This enables accurate measurements even with large temperature fluctuations without loss of accuracy will be realized.

Claims (23)

1. A method for eliminating measurement errors of at least one sensor that delivers electrical signals, measuring system having due to interference, characterized in that with a temperature dependence of the electrical signals supplied by each sensor, the temperature-related measurement error due to a measurement of the temperature level on which the sensor is located, is compensated. 2. The method according to claim 1, characterized in that the preparation of the existing of each Sensor supplied electrical signals including the compensation of the temperature-related measurement error in the immediate vicinity of the sensor. 3. The method according to claim 1 or 2, characterized in that the sensor and the preparation of the electrical signals supplied by him on the same components Temperature level are maintained. 4. The method according to claim 3, characterized in that in the presence of more than one sensor all sensors and the components processing their signals at the same temperature level being held. 5. The method according to any one of claims 1 to 4, characterized in that on the signal transmission paths interfering influences due to an at least largely identical design of the signal transmission paths be suppressed. 6. The method according to any one of claims 1 to 5, characterized in that all signal transmission paths and components, including the existing sensors, are shielded against electromagnetic interference become. 7. The method according to any one of claims 1 to 6, characterized in that all signal transmission paths and components, including the existing sensors, are protected against environmental influences become. 8. The method according to any one of claims 1 to 7, characterized in that for the compensation of the temperature-dependent measurement errors of the electrical signals from the sensors, digital map memories are used. 9. The method according to any one of claims 1 to 8, characterized in that for the compensation of the temperature-dependent Measurement error of the electrical signal of the temperature sensor a digital map memory is used. 10. The method according to claims 1 to 9, characterized in that when measuring mechanical quantities When using measuring bridges, passive comparison sensors of the respective measurand mechanically be decoupled. 11. The method according to any one of claims 1 to 10, characterized in that the processing of the measurement signals a time signal for the purpose of saving energy and improving the information content the measurements are made available. 12. Device for eliminating measurement errors due to disturbances of at least one electrical Measuring system emitting signals, characterized in that they are compact Measuring device is formed, in which a temperature measuring device measuring the temperature level of the sensor and a temperature-dependent measurement error due to the measured temperature of the sensor compensating signal conditioning circuit are integrated. 13. The apparatus according to claim 12, characterized in that an energy supply ( 5 ) is integrated in the measuring device. 14. The apparatus according to claim 12 or 13, characterized in that the measuring device is shielded by a metallic housing ( 1 ) against electromagnetic radiation. 15. The device according to one of claims 12 to 14, characterized in that the measuring device against the environment is completely sealed. 16. Device according to one of claims 12 to 15, characterized in that all components of the measuring device are arranged on a conductor tracks as signal and energy transmission paths having carriers ( 3 , 4 ). 17. The apparatus according to claim 16, characterized in that the carrier is at least partially formed by a film ( 4 ). 18. The apparatus according to claim 17, characterized in that an end portion of the film ( 4 ) forms a layer of a multilayer support plate ( 3 ). 19. Device according to one of claims 16 to 18, characterized in that the signal transmission paths have a length of at most a few centimeters, preferably a few millimeters. 20. The apparatus according to claim 19, characterized in that the signal transmission paths at least are largely identical. 21. Device according to one of claims 12 to 21, characterized in that all parts in a mechanical highly resilient unit with minimized dimensions, preferably a few millimeters or centimeters are integrated. 22. The device according to one of claims 12 to 21, characterized in that the mechanical load, for the application of active sensors for measuring mechanical quantities on a surface outside the device is required, can be applied during the application process without permanent change and without affecting the measurements. 23. Device according to one of claims 2 to 22, characterized in that by using a plurality of spatially distributed temperature measuring devices ( 7, 13, 14, 5 ) and a time generator ( 5 ) the inertia behavior of the measurements in the event of a sudden change in the temperature of the surface, to which the device is applied is improved by taking thermal conduction phenomena into account.