Computer device and method for testing a capacitive sensor

Abstract

The present invention relates to a computer device (10) and to a method for testing a capacitive sensor by measuring, at least once, a measurement curve of a change in a measurement variable (x) over time, which measurement curve reflects a position of a sensor mass (16) which is adjustably connected to and / or in a mount (12) by means of at least one spring component (18a, 18b), and by determining at least one damping (D) of a spring-mass system formed by the sensor mass (16) and the at least one spring component (18a, 18b), taking into account the at least one measured measurement curve, wherein, in addition, a natural frequency (f0) of the spring-mass system is determined taking into account the at least one measured measurement curve, and, if the determined damping (D) falls below a first limit value (g1(f0)) which is dependent on the determined natural frequency (f0) according to a specified first function (g1(f0)), and exceeds a second limit value (g2(f0)) which is dependent on the determined natural frequency (f0) according to a specified second function (g2(f0)), it is determined that the capacitive sensor satisfies at least a specified minimum suitability.

Description

[0001] Description

[0002] title

[0003] Computing device and method for testing a capacitive sensor

[0004] The present invention relates to a computing device for a capacitive sensor. The invention also relates to a capacitive sensor and a measuring cabinet for a production facility. Furthermore, the invention relates to a method for testing a capacitive sensor.

[0005] State of the art

[0006] The applicant is aware of a conventional procedure for testing a capacitive sensor after its manufacture as internal prior art. The capacitive sensor has a spring-mass system comprising a sensor mass and at least one spring component by means of which the sensor mass is adjustably connected to a holder of the capacitive sensor. To determine whether the capacitive sensor has at least a minimum suitability for its later desired operation, the damping of the spring-mass system is determined in the conventional procedure. According to the conventional procedure for testing the capacitive sensor, its minimum suitability is only confirmed if the determined damping of its spring-mass system is below a predetermined damping limit.

[0007] Disclosure of the invention

[0008] The present invention provides a computing device for a capacitive sensor having the features of claim 1, a capacitive sensor having the features of claim 6, a measuring cabinet for a production facility having the features of claim 8 and a method for testing a capacitive sensor having the features of claim 9.

[0009] Advantages of the invention

[0010] The present invention provides possibilities for more reliably testing a capacitive sensor after its manufacture and / or during its operation. In particular, by using the present invention, it can be more reliably detected whether the respective capacitive sensor fulfills at least a predetermined minimum suitability that enables its desired operation. In particular, the presence of damage to the respective capacitive sensor, which is attributable to at least one defect in its manufacture, or leaky packaging of the respective capacitive sensor can be more reliably detected or ruled out by means of the present invention. In particular, the present invention contributes to avoiding the erroneous interpretation of an increased number of capacitive sensors as defective during mass production of the respective capacitive sensor.The present invention thus contributes to increasing the yield in the mass production of capacitive sensors. Accordingly, capacitive sensors can be manufactured more cost-effectively using the present invention.

[0011] It is also pointed out that the use / utilization of the present invention merely requires a corresponding design and / or programming of an electronic device of a computer device used for this purpose, or of the electronics used to carry out the method according to the invention. As will become clear from the following description, however, a corresponding design and / or programming is comparatively simple and can be carried out with relatively little effort. Furthermore, an embodiment of the present invention does not require any additional hardware on the respective capacitive sensor or on a measuring cabinet used for this purpose in a production facility. The implementation / utilization of the present invention is therefore relatively cost-effective. The use / utilization of the present invention is also accessible to the end customer via a software API. This allows the end customer to test the suitability of the respective sensor during its lifetime and, if necessary, to improve it.readjust. In an advantageous embodiment of the computing device, the electronic device is additionally designed and / or programmed such that, if the determined attenuation is greater than the first limit value or less than the second limit value, the electronic device determines that the capacitive sensor itself lacks the specified minimum suitability. As will become clear from the following description, the embodiment of the computing device described here can be used to clearly identify when a particular capacitive sensor is unsuitable for subsequent or continued operation, without the risk of erroneously interpreting a capacitive sensor that meets the minimum suitability as unsuitable.

[0012] As an advantageous further development, the electronic device can additionally be designed and / or programmed in such a way that the at least one measurement curve can be measured by means of the electronic device, in that a voltage can be applied between the at least one electrode and the sensor mass by means of the electronic device in such a way that the sensor mass can be deflected from its initial position, the voltage applied between the at least one electrode and the sensor mass can be switched off or interrupted by means of the electronic device at a triggering time, and the time course of the measurement curve can be detected by means of the electronic device during a total measurement time comprising the triggering time and covering an adjustment movement of the sensor mass into its initial position.The refinement of the computing device / its electronics described here eliminates the need to use an additional device for measuring the at least one measurement curve to be evaluated. This also contributes to further cost savings.

[0013] Preferably, the electronic device is additionally designed and / or programmed such that the respective triggering time can be stored together with the associated measurement curve in a memory of the computer device by means of the electronic device, and later, during an individual evaluation of the at least one stored measurement curve, a respective individual damping value of the damping of the spring-mass system and a respective individual natural frequency value of the natural frequency of the spring-mass system can be determined by means of the electronic device using the associated triggering time read from the memory. A significant advantage of the embodiment described here is the more precise determination of the natural frequency of the respective sensor, which is directly related to the calibration of the respective sensor. The natural frequency is a direct measure of the sensitivity of the sensor.The precision of the determination is significantly increased by using the stored trigger time. This makes it possible to replace calibration procedures using direct stimuli (tilting in a gravitational field or rotation in a centrifuge) during the initial production test with the transient measurements described here using substitute electrical stimuli without any loss of accuracy. Due to the ability to determine the natural frequency with high accuracy using the procedure described here, previously necessary, costly direct calibration procedures can be replaced. As explained in more detail below, by storing the respective trigger time and later using it to determine the respective damping, this can also be determined more precisely and reliably.

[0014] For example, the computing device can be an ASIC or PC. The computing device can thus be designed to be comparatively cost-effective and relatively space-saving. Implementing the computing device as an ASIC or PC on the autonomous module further enables use of the present invention throughout its life cycle, and thus also allows for repeated execution of the process, e.g., via a software API, or for restoring calibration at the end of production.

[0015] The advantages described above are also ensured in a capacitive sensor which is equipped with a corresponding computing device and the spring-mass system comprising the sensor mass of the capacitive sensor and the at least one spring component of the capacitive sensor, by means of which the sensor mass is adjustably connected to the holder of the capacitive sensor, the damping and the natural frequency of which can be determined by means of the electronic device of the computing device.

[0016] In particular, the capacitive sensor can be an acceleration sensor or a yaw rate sensor. The invention described here can therefore be used for commonly used sensor types. However, the design of the capacitive sensor is not limited to the sensor types listed here. The advantages explained above are also realized in a measuring cabinet for a production facility with such a computing device.

[0017] Furthermore, implementing a corresponding method for testing a capacitive sensor also provides the advantages explained above. It is expressly noted that the method for testing a capacitive sensor can be further developed according to the above-explained embodiments of the computing device and / or the capacitive sensor.

[0018] Short description of the drawings

[0019] Further features and advantages of the present invention are explained below with reference to the figures. They show:

[0020] Fig. 1A to 1F are schematic representations of an embodiment of the computing device and the cooperating capacitive sensor and coordinate systems for explaining their operation; and

[0021] Fig. 2a and 2b show a flow chart and a coordinate system for explaining an embodiment of the method for checking a capacitive sensor.

[0022] Embodiments of the invention

[0023] Fig. 1A to 1F show schematic representations of an embodiment of the computing device and the cooperating capacitive sensor and coordinate systems for explaining their operation.

[0024] The computing device 10, schematically shown in Fig. 1Aa and 1Ab, can interact with (almost) any capacitive sensor equipped with at least one holder 12, at least one electrode 14a and 14b, and a sensor mass 16. The at least one electrode 14a and 14b refers to a non-adjustable electrode 14a and 14b attached to and / or in the holder 12. In contrast, the sensor mass 16 refers to an adjustable mass or seismic mass that is adjustably connected to and / or in the holder 12 by means of at least one spring component 18a and 18b of the capacitive sensor.

[0025] Due to its adjustable connection, the sensor mass 16 is / is adjustable by means of a voltage U(t) (non-zero) applied between the at least one electrode 14a and 14b and the sensor mass 16. In addition, the sensor mass 16 is / is also adjustable by means of a physical force external to the sensor. The physical force external to the sensor can be understood, for example, as an inertial force or a Coriolis force. As a rule, the sensor mass 16 is in a so-called initial position when neither a voltage U(t) non-zero is applied between the at least one electrode 14a and 14b and the sensor mass 16, nor is a physical force external to the sensor acting on it. The initial position can be an initial position of the sensor mass 16 in relation to the at least one electrode 14a and 14b.However, the initial position can also be understood as an initial oscillation of the sensor mass 16 along an oscillation axis, which runs (essentially) equidistant from at least one first electrode 14a on a first side of the oscillation axis and at least one second electrode 14a on a second side of the oscillation axis.

[0026] The sensor mass 16 and the at least one spring component 18a and 18b form a so-called spring-mass system of the capacitive sensor. For example only, the capacitive sensor of Figs. 1Aa and 1Ab has, as its at least one spring component 18a and 18b, a first tension or compression spring 18a and a second tension or compression spring 18b, wherein the sensor mass 16 is suspended in a gimbal manner between the first tension or compression spring 18a and the second tension or compression spring 18b. However, the design of the capacitive sensor interacting with the computing device 10 is not limited to any specific spring type of its at least one spring component 18a and 18b.

[0027] The capacitive sensor can, in particular, be an acceleration sensor or a yaw rate sensor. However, it is expressly pointed out that the usability of the computing device 10 described below is not limited to any specific type of capacitive sensor. The computing device 10 can optionally be a subunit of the capacitive sensor or interact externally with the capacitive sensor. For example, the computing device 10 can also be a subunit of a measuring cabinet in a production facility where the at least one capacitive sensor is manufactured. The computing device 10 described below is thus versatile. Furthermore, the computing device 10 described below can be an ASIC. The computing device 10 can therefore be manufactured relatively inexpensively. The installation space requirement is also minimized with such a computing device 10.

[0028] The computing device 10 has an electronic device 10a, which is designed and / or programmed such that, by means of the electronic device 10a, a damping D of the spring-mass system formed by the sensor mass 16 and the at least one spring component 18a and 18b, and a natural frequency f0 of the spring-mass system can be determined / are determined, taking into account at least one measurement curve. The at least one measurement curve evaluated to determine the damping D and the natural frequency f0 of the spring-mass system can be understood as a measurement curve provided to the computing device 10 or a measurement curve measured by the computing device 10.

[0029] An example of such a measurement curve is shown in the coordinate system of Fig. 1B. To determine the damping D and the natural frequency f0 of the spring-mass system, at least one measurement curve is evaluated, each of which indicates a time course of a measured variable x that represents a position of the sensor mass 16 in relation to its initial position. In the coordinate system of Fig. 1B, the abscissa is a time axis t (in milliseconds), while the ordinate indicates a (normalized) deflection x of the sensor mass 16 from its initial position. The (normalized) deflection x of the sensor mass 16 from its initial position can be understood, for example, as a (normalized) deflection / a (normalized) distance x of the sensor mass 16 in relation to its initial position or the oscillation axis of its initial oscillation.

[0030] In the example of Fig. 1A to 1F, the electronic device 10a is additionally designed and / or programmed such that the at least one measurement curve can be measured / is measured by means of the electronic device 10a. A respective measurement of the at least one measurement curve is carried out by first applying a voltage U(t) not equal to zero between the at least one electrode 14a and 14b and the sensor mass 16 by means of the electronic device 10a in such a way that the sensor mass 16 can be deflected / is deflected from its initial position. In the example of the coordinate system of Fig. 1B, the sensor mass 16 is adjusted from its initial position by means of the applied voltage U(t) not equal to zero until a so-called triggering time / switch-off time toir.Subsequently, the voltage U(t) applied between the at least one electrode 14a and 14b and the sensor ground 16 can be switched off or interrupted by the electronic device 10a at (precisely) the triggering time toir. A voltage drop caused by switching off or interrupting the voltage U(t) applied between the at least one electrode 14a and 14b and the sensor ground 16, or a force drop triggered thereby, preferably occurs within a time interval which is in the range of RC charging times (or in the range of a few nanoseconds) and is thus significantly shorter than a so-called sampling time. Switching off or interrupting the voltage U(t) applied between the at least one electrode 14a and 14b and the sensor ground 16 preferably causes a voltage drop at the triggering time toir with a (substantially) infinitely negative gradient.In addition, the time profile of the measured variable x is detectable by the electronic device 10a during a total measurement time AT encompassing the triggering time toir and a (re)adjustment movement of the sensor mass 16 to its initial position. By means of the design / programming of the computer device 10 / its electronic device 10a described in this paragraph, a further "measuring device" for measuring the at least one measurement curve evaluated to determine the damping D and the natural frequency f0 of the spring-mass system can be eliminated.

[0031] Preferably, the computer device 10 also has a memory 10b, and the electronic device 10a is designed and / or programmed such that, during the processes described in the preceding paragraph, the respective triggering time toir can be / are stored in the memory 10b together with the associated measurement curve. The memory 10b can also be understood as a register. Accordingly, during an individual evaluation of the at least one measurement curve stored in the memory 10b, a respective individual damping value of the damping D of the spring-mass system and a respective individual natural frequency value of the natural frequency f0 of the spring-mass system can be / are determined by the electronic device 10a using the associated triggering time toff read from the memory 10b.

[0032] Traditionally, it was assumed that the exact knowledge of the trigger time t off would not be relevant for the precise determination of the damping D of the spring-mass system or the natural frequency f0 of the spring-mass system because the relevant information would be sufficiently encoded in the remaining curve of the respective measurement curve. Until now, it was assumed that the accuracy-limiting time constant for determining the damping D of the spring-mass system or the natural frequency f0 of the spring-mass system would be the sampling time. However, this only applies to low-damped sensors with oscillatory response and, possibly, only in the limiting case of perfect signal-to-noise conditions. Storing / storing the respective trigger time toff together with the associated measurement curve in memory 10b, however, utilizes the knowledge that, in particular, the natural frequency f0 of the spring-mass system closely correlates with the measurement data at the trigger time toff and therefore requires precise knowledge of the trigger time t o ff is advantageous.

[0033] If, as is common in the state of the art, only the sampling time can be used as a reference in the computational evaluation, an error corresponding to the inverse of the sampling time results. By storing / storing the respective trigger time t O ff together with the associated measurement curve in memory 10b, however, can ensure a significant reduction in the determination error. This can be exploited by the fact that in digital ASIC circuits, the control of switching processes in higher digital clock domains is implemented deterministically. This makes it possible to determine the triggering time t o ff with an accuracy equal to a quotient of the sampling time divided by M with M=2 AN, whereby with N=2, 3, 4,..., significant increases in the accuracy of the time base, or the determination accuracy with M=4, 8, 16..., are possible. A particularly advantageous feature is the fact that these time domains are available at no additional cost.

[0034] Storing / storing and using the respective trigger time toff is very efficient, as it allows the time phase around the respective trigger time toir, which is particularly important for the dynamics of the process, to be precisely captured. This increases the evaluation accuracy many times over. A corresponding improvement in evaluation accuracy would theoretically also be possible by improving the signal-to-noise ratio or by significantly shortening the sampling time. However, based on current knowledge, the conditions required for this are currently unattainable.

[0035] The advantage of storing / storing the respective triggering time toff together with the associated measurement curve in memory 10b is also apparent from a comparison of the coordinate systems of Figs. ICa to ICd with the coordinate systems of Figs. IDa to IDd. The abscissas of the coordinate systems of Figs. ICa and IDa each represent specific individual natural frequency values ​​of the natural frequency f0 of the spring-mass system (in Hertz). The abscissas of the coordinate systems of Figs. ICb and IDb display individual damping values ​​of the damping D of the spring-mass system. The abscissas of the coordinate systems of Figs. ICc and IDc serve to display the respective triggering time t Off (in milliseconds). The ordinates of the coordinate systems in Figs. ICa to ICc and IDa to IDc represent a frequency I(fo), I(D), and I(toff). In contrast, in the coordinate systems of Figs. ICd and IDd, the abscissas represent the individual values ​​of the natural frequency f0 of the spring-mass system (in Hertz), and the ordinates represent the associated individual damping values ​​of the damping D of the spring-mass system.

[0036] To create the coordinate systems of Figs. ICa to ICd, the same total number of measurement curves was evaluated as for the creation of the coordinate systems of Figs. IDa to IDd. When evaluating the measurement curves underlying the coordinate systems of Figs. ICa to ICd, the trigger time t o ff was determined using a corresponding plotting algorithm together with the individual natural frequency values ​​and the individual damping values. This was necessary because the respective triggering time t off was not stored on a storage device when measuring the associated measurement curve. In contrast, when measuring the measurement curves underlying the coordinate systems of Fig. IDa to IDd, the respective trigger time t o ff together with the associated measurement curve in the memory 10b. This eliminated the need for subsequent estimation / plotting of the respective trigger time t o ff in the individual evaluation of the assigned measurement curve.

[0037] For the sake of clarity, the same trigger time toff was maintained when measuring all of the measurement curves underlying the coordinate systems of Figs. IC and ID. However, as is apparent from the coordinate system of Fig. ICc, the respective trigger time Uff can only be estimated / plotted with a relatively large degree of inaccuracy when evaluating the associated measurement curve individually. As is also apparent from a comparison of the coordinate system of Fig. ICa with the coordinate system of Fig. IDa and a comparison of the coordinate system of Fig. ICb with the coordinate system of Fig. IDb, the inaccuracy in estimating / plotting the trigger time toff contributes significantly to an increase in the scatter of the individual natural frequency values ​​of the natural frequency f0 and the individual damping values ​​of the damping D.

[0038] It is therefore advantageous if, by storing / storing the triggering time Uff in the memory 10b, the need for a subsequent estimation of the triggering time Uff is eliminated. In particular, by storing / storing the triggering time Uff in the memory 10b, significantly more precise and significantly more error-free individual natural frequency values ​​of the natural frequency f0 and individual damping values ​​of the damping D are obtained. Equipping the computer device 10 with the memory 10b and designing / programming the electronic device 10a to store the respective triggering time Uff together with the associated measurement curve in the memory 10b is therefore very advantageous.

[0039] After determining the damping D of the spring-mass system and the natural frequency fo of the spring-mass system, the electronic device 10a is designed and / or programmed to determine, taking into account the determined damping D and the determined natural frequency fo, whether the capacitive sensor meets at least a predetermined minimum suitability. To this end, the design and / or programming of the electronic device 10a enables the electronic device 10a to determine whether the determined damping is less than a first limit value gi(fo) and greater than a second limit value g2(fo). The first limit value gi(fo) depends on the determined natural frequency fo according to a predetermined first function gi(fo). Accordingly, the second limit value g2(fo) depends on the determined natural frequency fo according to a predetermined second function g2(fo).In particular, the first function gi(fo) and / or the second function g2(fo) can each be a linear function. For example, the first function gi(fo) and the second function g2(fo) can be defined according to equations (Eq. 1) and (Eq. 2): (Eq. 1) gi(fo) = Cl + mi * fo and.

[0040] (Eq. 2) g2(fo) = C2 + m2 * fo, where mi, m2, Ci, and C2 are each real numbers and C2< Ci and m2< mi. In particular, C2< Ci and m2= mi.

[0041] The use of the first function gi(fo) and the second function g2(fo) allows for a subsequent improvement in determination accuracy even when precise knowledge of the trigger time toir is not available. With this instrumental expansion of the measurement control and the recording and use of the trigger time toir, the error effect is reduced accordingly. In addition, the fundamental effect of mapping the fo / D correlation is still effective. This leads to a further reduction of the residual uncertainty in the parameter determination.

[0042] If the electronic device 10a determines that the determined attenuation D is less than the first limit value gi(fo) and greater than the second limit value g2(fo), the design and / or programming of the electronic device 10a ensures that the electronic device 10a also determines that the capacitive sensor meets at least the specified minimum suitability. Subsequently, the electronic device 10a can display / output corresponding information regarding the fulfillment or non-fulfillment of at least the specified minimum suitability by the capacitive sensor.Preferably, the electronic device 10a is additionally designed and / or programmed such that, if the determined attenuation D is greater than the first limit value gi(fö) or less than the second limit value g2(fö), it is / is determined by means of the electronic device 10a that the capacitive sensor itself lacks the predetermined minimum suitability.

[0043] Fulfillment of at least the specified minimum suitability can be understood, for example, as meaning that the respective capacitive sensor is packaged / sealed in a gas-tight manner. Where appropriate, the respective capacitive sensor has a "hole-free" or "gas-tight" packaging. Packaging can also be understood as packaging or encapsulation of the capacitive sensor. Accordingly, failure to fulfill at least the specified minimum suitability can be understood as meaning that undesirable "holes" appear in the packaging of the respective capacitive sensor.

[0044] The advantageous design and / or programming of the electronic device 10a is based on the realization that the occurrence of unwanted "holes" in the packaging of the respective capacitive sensor is generally associated with a significant increase in its damping D despite its (essentially) unchanged natural frequency f0, while a joint increase in damping D and natural frequency f0 of the respective capacitive sensor is not / hardly attributable to "holes" in the packaging of the respective capacitive sensor. The advantageous design and / or programming of the electronic device 10a is thus based on the realization that the conventional assumption that a significant increase in damping D of the respective capacitive sensor is (almost) always attributable to "holes" in its packaging is incorrect.In contrast to the conventional assumption, in the case of a capacitive sensor with a comparatively high damping D and a relatively large natural frequency f0, its packaging is generally free of holes.

[0045] A comparison of the coordinate systems in Figs. 1E and 1F clearly illustrates the advantages of the design / programming of the computing device 10 / its electronic device 10a. In the coordinate systems in Figs. 1E and 1F, the abscissa represents the determined natural frequency f0 (in Hertz), while the ordinate represents the determined corresponding damping D.

[0046] In the coordinate system of Fig. IE, the values ​​for the damping D of the respective capacitive sensor are compared with the first limit value gi(fo) and the second limit value g2(fo). It can be seen from the coordinate system of Fig. IE that the design / programming of the electronic device 10a ensures that for each capacitive sensor whose determined damping D is less than the first limit value gi(fo) dependent on its natural frequency f0 and greater than the second limit value g2(fo) dependent on its natural frequency f0, it is determined that the respective capacitive sensor at least meets the specified minimum suitability (hatching A).In addition, the design / programming of the electronic device 10a ensures that for each capacitive sensor whose specific damping D is greater than the first limit value gi(fo) dependent on its natural frequency f0 or less than the second limit value g2(fo) dependent on its natural frequency f0, it is determined that the respective capacitive sensor itself lacks the specified minimum suitability (hatching B).

[0047] In contrast, in the coordinate system of Fig. 1F, the values ​​for the damping D of the respective capacitive sensor are compared with a specified damping threshold Dthreshoid only according to the conventional procedure for testing a capacitive sensor explained above. According to the conventional procedure for testing the capacitive sensor, its minimum suitability is only affirmed if the damping D of the respective capacitive sensor is below the specified damping threshold Dthreshoid (hatching A). If the damping D of the respective capacitive sensor is above the specified damping threshold Dthreshoid, its minimum suitability is denied (hatching B).

[0048] A marking 20 in the coordinate system of Fig. 1F shows that, in contrast to the conventional approach, the design / programming of the electronic device 10a ensures that for each capacitive sensor whose damping D is greater than the specified damping threshold Dthreshoid, but smaller than the first threshold gi(fo) dependent on its natural frequency f0, and larger than the second threshold g2(fo) dependent on its natural frequency f0, the respective capacitive sensor at least meets the specified minimum suitability. The advantageous design / programming of the computer device 10 / its electronic device 10a thus contributes to increasing yield in the mass production of capacitive sensors. By utilizing the computer device 10 / its electronic device 10a, manufacturing costs for capacitive sensors can therefore be significantly reduced.

[0049] Fig. 2a and 2b show a flowchart and a coordinate system for explaining an embodiment of the method for testing a capacitive sensor.

[0050] The method explained below can be implemented for (almost) any capacitive sensor equipped with at least one mount, at least one electrode, and a sensor mass adjustably connected to and / or within the mount by means of at least one spring component of the capacitive sensor. For possible embodiments of the capacitive sensor and its components, please refer to the explanations above.

[0051] The method begins with a method step S1, which is carried out at least once. In method step S1, a measurement curve of a time profile of a measurand is measured in each case, which represents a position of the sensor mass in relation to an initial position of the sensor mass, from which initial position the sensor mass is adjustable by means of a voltage applied between the at least one electrode and the sensor mass. For example, in method step S1, which is carried out at least once, the respective measurement curve can be measured by carrying out sub-steps S1a to S1c. If necessary, in the (optional) sub-step S1a, the sensor mass is deflected from its initial position by applying a voltage between the at least one electrode and the sensor mass.In the (optional) sub-step S1 b, the voltage applied between the at least one electrode and the sensor mass is switched off or interrupted at a triggering time. In addition, as an (optional) sub-step S1 c, the time profile of the measured variable is detected during a total measurement time, which includes the triggering time and a (re)adjustment movement of the sensor mass to its initial position. Preferably, the method step S1 also includes an (optional) sub-step S1 d, in which the respective triggering time is stored in a memory together with the associated measurement curve.

[0052] After method step S1 has been carried out at least once, in method step S2 a damping D of a spring-mass system formed from the sensor mass and the at least one spring component is determined taking into account the at least one measured measurement curve. Before, after or simultaneously with method step S2, in method step S3 a natural frequency f0 of the spring-mass system is additionally determined taking into account the at least one measured measurement curve. If sub-step S1 d has been carried out, a respective individual damping value of the damping D of the spring-mass system (as method step S2) and a respective individual natural frequency value of the natural frequency f0 of the spring-mass system (as method step S3) can be determined later during an individual evaluation of the at least one stored measurement curve using the assigned triggering time read from the memory.

[0053] In a method step S4, it is determined whether the capacitive sensor meets at least a predetermined minimum suitability. For this purpose, in method step S4 it is determined whether the determined damping D is less than a first limit value, which is dependent on the determined natural frequency f0 according to a predetermined first function, and greater than a second limit value, which is dependent on the determined natural frequency f0 according to a predetermined second function. If the determined damping D is less than the first limit value and greater than the second limit value, it is determined that the capacitive sensor meets at least the predetermined minimum suitability. Preferably, however, if the determined damping D is greater than the first limit value or less than the second limit value, it is determined that the capacitive sensor itself lacks the predetermined minimum suitability.

[0054] In the coordinate system of Fig. 2b, the abscissa represents the determined natural frequency f0 (in Hertz), while the ordinate indicates the corresponding damping D. It can be seen that for different types of capacitive sensors, each of which has a "hole-free" or "gas-tight" packaging, different linear graphs Li to L4 can be plotted.

Claims

Claims 1 . A computer device (10) for a capacitive sensor, comprising: an electronic device (10a) designed and / or programmed such that, by means of the electronic device (10a), taking into account at least one measurement curve of a time profile of a measured variable (x) provided or measured by the computer device (10), which represents a position of a sensor mass (16) of the capacitive sensor, which is adjustably connected to and / or in a holder (12) of the capacitive sensor by means of at least one spring component (18a, 18b) of the capacitive sensor, in relation to an initial position of the sensor mass (16), from which the sensor mass (16) is adjustable by means of a voltage (U(t)) applied between at least one electrode (14a, 14b) of the capacitive sensor and the sensor mass (16), - at least one damping (D) of a spring-mass system formed from the sensor mass (16) and the at least one spring component (18a, 18b) can be determined; and - it is possible to determine, at least taking into account the specific damping (D) of the spring-mass system, whether the capacitive sensor fulfils at least a predetermined minimum suitability; characterized in that the electronic device (10a) is additionally designed and / or programmed such that by means of the electronic device (10a): - in addition, a natural frequency (f0) of the spring-mass system can be determined taking into account at least one measured curve, and, - if the determined damping (D) is smaller than a first limit value (gi(fo)), which is dependent on the determined natural frequency (fo) according to a predetermined first function (gi(fo)), and is greater than a second limit value (g2(fo)), which is dependent on the determined natural frequency (f0) according to a predetermined second function (g2(fo)), it is specified that the capacitive sensor meets at least the predetermined minimum suitability.

2. Computer device (10) according to claim 1, wherein the electronic device (10a) is additionally designed and / or programmed such that, if the determined attenuation (D) is greater than the first limit value (gi(fo)) or less than the second limit value (g2(fo)), it is determined by means of the electronic device (10a) that the capacitive sensor itself lacks the predetermined minimum suitability.

3. Computer device (10) according to claim 1 or 2, wherein the electronic device (10a) is additionally designed and / or programmed such that the at least one measurement curve can be measured by means of the electronic device (10a) in that by means of the electronic device (10a): - a voltage (U(t)) between the at least one Electrode (14a, 14b) and the sensor mass (16) can be applied in such a way is that the sensor mass (16) can be deflected from its initial position; - the voltage (U(t)) present between the at least one electrode (14a, 14b) and the sensor mass (16) is measured by means of the electronic device (10a) at a triggering time (t O ff) can be switched off or interrupted; and - the time course of the measured variable by means of the electronic device (10a) during a time period which determines the triggering time (t Off) and covering an adjustment movement of the sensor mass (16) to its initial position.

4. Computer device (10) according to claim 3, wherein the electronic device (10a9) is additionally designed and / or programmed such that the respective triggering time (t O ff) can be stored together with the associated measurement curve by means of the electronic device (10a) on a memory (10b) of the computer device (10), and later, during an individual evaluation of the at least one stored measurement curve, a respective individual damping value of the damping (D) of the spring-mass system and a respective individual natural frequency value of the natural frequency (f ) of the spring-mass system are determined using the associated triggering time (t O ff) can be determined by means of the electronic device (10a).

5. The computing device (10) according to any one of the preceding claims, wherein the computing device (10) is an ASIC.

6. Capacitive sensor with: a computer device (10) according to one of the preceding Claims; and the spring-mass system comprising the sensor mass (16) of the capacitive sensor and the at least one spring component (18a, 18b) of the capacitive sensor, by means of which the sensor mass (16) is adjustably connected to the holder (12) of the capacitive sensor, the damping (D) and the natural frequency (f0) of which can be determined by means of the electronic device (10a) of the computing device (10).

7. Capacitive sensor according to claim 6, wherein the capacitive sensor is an acceleration sensor or a yaw rate sensor.

8. Measuring cabinet for a production facility with a computer device (10) according to one of claims 1 to 5.

9. Procedure for testing a capacitive sensor with the steps: Measuring at least once a measurement curve of a time profile of a measured variable (x), which represents a position of a sensor mass (16) of the capacitive sensor, which is adjustably connected to and / or in a holder (12) of the capacitive sensor by means of at least one spring component (18a, 18b) of the capacitive sensor, in relation to an initial position of the sensor mass (16), from which the sensor mass (16) is adjustable by means of a voltage (U(t)) applied between at least one electrode (14a, 14b) of the capacitive sensor and the sensor mass (16) (S1); Determining at least one damping (D) of a spring-mass system formed from the sensor mass (16) and the at least one spring component (18a, 18b) taking into account the at least one measured measurement curve (S2); and Determining whether the capacitive sensor meets at least a predetermined minimum suitability, at least taking into account the determined damping (D) of the spring-mass system; characterized in that, in addition, a natural frequency (f0) of the spring-mass system is determined taking into account the at least one measured measurement curve (S3); and, if the determined damping (D) is smaller than a first limit value (gi(fo)), which is dependent on the determined natural frequency (fo) according to a predetermined first function (gi(fo)), and is greater than a second limit value (g2(fo)), which is dependent on the determined natural frequency (f0) according to a predetermined second function (g2(fo)), it is determined that the capacitive sensor meets at least the predetermined minimum suitability (S4).

10. The method according to claim 9, wherein, if the determined attenuation (D) is greater than the first limit value (gi(fo)) or less than the second limit value (g2(fo)), it is determined that the capacitive sensor itself lacks the predetermined minimum suitability.

11. Method according to claim 9 or 10, wherein the at least one measurement curve is measured by performing the following substeps: - deflecting the sensor mass (16) from its initial position by applying a voltage (U(t)) between the at least one electrode (14a, 14b) and the sensor mass (16)(S1a); - switching off or interrupting the voltage (U(t)) applied between the at least one electrode (14a, 14b) and the sensor mass (16) at a triggering time (t O ff) (S1 b) ; and - Detecting the time course of the measured variable (x) during a trigger time (t Off) comprising a total measuring time (AT)(S1c) and covering an adjustment movement of the sensor mass (16) to its initial position.

12. The method according to claim 11, wherein the respective triggering time (t O ff) is stored (S1 d) together with the associated measurement curve in a memory (10b), and later, during an individual evaluation of the at least one stored measurement curve, a respective individual damping value of the damping (D) of the spring-mass system and a respective individual natural frequency value of the natural frequency (f ) of the spring-mass system are determined using the associated triggering time (t O ff).

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