Occupancy detection device and method for detecting the occupancy status of a vehicle component, as well as steering wheel and vehicle seat with a measuring module of such an occupancy detection device.

Abstract

Occupancy detection device (10) for detecting the occupancy status of a vehicle component, characterized in that - the occupancy recording device (10) has an evaluation device (200) and at least one measuring module (100) connected to the evaluation device (200), - that at least one measuring module (100) has a first electrode (110) which is connected to a first connection point (101) of the measuring module (100), is electrically insulated from a reference potential (BP) and forms a first electrical capacitance with it, - that at least one measuring module (100) has a second electrode (120) which is connected to a second connection point (102) of the measuring module (100), is electrically insulated from the reference potential and forms a second electrical capacitance with it, - the first and second electrodes are capacitively coupled by a coupling capacitance and - the evaluation unit (200) is designed to determine the first and second capacity by forming a first and second capacity value (C1, C2) using at least three measurement steps (MS1-MS3), to calculate the quotient (C1 / C2) between the capacity values ​​and to generate an occupancy signal (SB) if the quotient deviates from a specified target quotient (Qtarget) beyond a specified measure.

Description

[0001] The invention relates to occupancy detection devices suitable for detecting the occupancy status of a vehicle component.

[0002] Such occupancy detection devices are provided in motor vehicles, for example for steering wheels, in order to check whether the driver of the motor vehicle is touching the steering wheel and is therefore able to react to the traffic situation by steering movements.

[0003] Occupancy detection systems are also used in motor vehicles to detect the occupancy status of vehicle seats, in order to determine whether the seats are occupied by a passenger or not; the occupancy information can be used, for example, to generate a warning signal if a vehicle seat is detected as occupied but the corresponding seat belt is not fastened. Other applications are also known, such as deactivating airbags when vehicle seats are unoccupied.

[0004] Occupancy recording devices are known, for example, from the publications WO 2022 / 023 369 A1 and DE 10 2019 106 959 A1.

[0005] The invention is based on the objective of providing an occupancy detection device that is particularly durable and can deliver reliable measurement results over a particularly long period of time.

[0006] This problem is solved according to the invention by an occupancy detection device with the features according to claim 1. Advantageous embodiments of the occupancy detection device according to the invention are specified in the dependent claims.

[0007] According to the invention, the occupancy detection device comprises an evaluation unit and at least one measuring module connected to the evaluation unit, the measuring module having a first electrode which is connected to a first terminal of the measuring module, is electrically isolated from a reference potential and forms a first electrical capacitance with it, the measuring module having a second electrode which is connected to a second terminal of the measuring module, is electrically isolated from the reference potential and forms a second electrical capacitance with it, the first and second electrodes being capacitively coupled by a coupling capacitance, and the evaluation unit being configured to determine the first and second capacitances by means of at least three measurement steps, thereby forming a first and second capacitance value.to calculate the quotient between the capacity values ​​and generate an occupancy signal if the quotient deviates from a predetermined target quotient beyond a specified limit.

[0008] A significant advantage of the occupancy detection device according to the invention is its exceptionally long lifespan and reliable occupancy detection. This is because the quotient between the first and second capacitance values—a relative value rather than an absolute value—is used as the measurement criterion for detecting the occupancy status. The invention is based on the premise that aging of the dielectric material located between the electrodes and the reference potential will alter the two capacitance values ​​used to calculate the quotient in a comparable manner; however, this alteration has no effect on the quotient itself, since the dielectric constants cancel out during the calculation, and the quotient thus remains unaffected by the aging of the dielectric material and the corresponding change in the dielectric constant.In contrast, the quotient changes when a person approaches or occupies the vehicle component, since the occupancy will practically never, or only negligibly rarely, be so symmetrical that the approach to the two electrodes occurs in an identical manner and both capacitance values ​​change equally; rather, there will always be an asymmetrical approach and thus a change in the quotient, which can be easily detected by comparing the measured quotient with the target quotient according to the invention. The same applies to the aging of an insulating material covering the electrodes on the outside.

[0009] A further significant advantage of the occupancy detection device according to the invention is that other external influencing factors – such as temperature changes, changes in humidity, moisture, electromagnetic radiation, especially sunlight – also have a symmetrical effect on the dielectric of the capacitors, so that these latter influencing factors affect the absolute values ​​of the capacitances, but not the ratio. Therefore, these latter influencing factors also do not affect the detection of the occupancy status.

[0010] It is advantageous if, in a first measurement step, the evaluation device measures the capacitance between the first terminal and the reference potential as the first auxiliary capacitance measurement when the second terminal is connected to the reference potential; in a second measurement step, the evaluation device measures the capacitance between the first terminal and the reference potential as the second auxiliary capacitance measurement when the second terminal is switched to a high-impedance tristate state; and in a third measurement step, the evaluation device measures the capacitance between the second terminal and the reference potential as the third auxiliary capacitance measurement when the first terminal is connected to the reference potential or switched to the high-impedance tristate state, whereby the order of the three measurement steps is arbitrary.

[0011] The evaluation unit preferably includes a measuring device for controlling the measurement steps, determining the quotient and generating the occupancy signal; such a measuring device is preferably formed by a microcontroller or preferably includes at least one.

[0012] It is considered particularly advantageous if the evaluation device measures the third auxiliary capacity measurement value in the third measurement step, after it has connected the first connection point to the reference potential.

[0013] In the latter configuration, the evaluation unit will preferably calculate the first capacity value according to C1=Cm1−Cm3⋅(Cm1−Cm2) and preferably calculate the second capacity value according to C2=Cm2−Cm3⋅(Cm1−Cm2) where C1 denotes the first capacity value, C2 the second capacity value, Cm1 the first auxiliary capacity measurement, Cm2 the second auxiliary capacity measurement, and Cm3 the third auxiliary capacity measurement.

[0014] Preferably, the evaluation unit calculates a coupling capacity value C3 indicating the coupling capacity according to: C3=Cm3⋅(Cm1−Cm2)

[0015] With regard to plausibility checks, it is considered advantageous if, in a fourth measurement step, the evaluation device switches the first terminal to the high-impedance tristate state and measures the capacitance between the second terminal and the reference potential as a fourth auxiliary capacitance measurement value after it has switched the first terminal to the high-impedance tristate state.

[0016] The evaluation unit then preferably subjects the fourth auxiliary capacity measurement, the first capacity value, the second capacity value and the coupling capacity value to a plausibility check.

[0017] In the latter design variant, it is considered advantageous if the evaluation unit checks, as part of the plausibility check, whether the fourth auxiliary capacity measurement value deviates from a target capacity measurement value beyond a predetermined capacity deviation measure.

[0018] The evaluation unit calculates the target capacity measurement value preferably according to Cs4=C1⋅C2+C1⋅C3+C2⋅C3C2+C3

[0019] In a preferred measurement design, the evaluation device applies a measurement pulse to the first connection point via a first series resistor in the first and / or second measurement step and determines the first and second auxiliary capacitance measurement value by evaluating the time course of the voltage applied to the first connection point.

[0020] In the third and / or fourth measurement step, the evaluation unit preferably applies a measurement pulse to the second connection point via a second series resistor and determines the third and / or fourth auxiliary capacitance measurement value by evaluating the time course of the voltage applied to the second connection point.

[0021] Alternatively or additionally, it can be advantageously provided that the evaluation device in the first and / or second measurement step feeds an alternating current into the first connection point or applies an alternating voltage to the first connection point and determines the first and / or second auxiliary capacitance measurement value by evaluating the alternating voltage or the alternating current flowing at the first connection point.

[0022] Alternatively or additionally, it can be advantageously provided that the evaluation device in the third and / or fourth measurement step feeds an alternating current into the second connection point or applies an alternating voltage to the second connection point and determines the third and / or fourth auxiliary capacitance measurement value by evaluating the alternating voltage or current flowing at the second connection point.

[0023] One or both electrodes can also be used for heating. Such heating operation can be combined with measurement operation for recording the occupancy status within a time-division multiplexing operation.

[0024] Accordingly, it is considered advantageous if the first electrode is connected with a first electrode end to the first connection point of the measuring module and with a second electrode end to a heating connection point of the measuring module, and if a heating operating switching device is provided that allows a vehicle-side on-board voltage to be applied between the first connection point and the heating connection point of the measuring module and the first electrode to be operated as a heating element.

[0025] It is advantageous to have a disconnect switch between the measuring device of the occupancy detection unit and the first connection point. In the open position, the disconnect switch isolates the first connection point from the measuring device, and in the closed position, it connects the first connection point to the measuring device. The disconnect switch is preferably only closed when the heating control unit has electrically disconnected the on-board voltage from the measuring module.

[0026] In a preferred embodiment, the occupancy detection device is a steering wheel touch detection device and the measuring module is designed for integration into a vehicle steering wheel.

[0027] In another preferred embodiment, the occupancy detection device is a seat occupancy detection device and the measuring module is designed for integration into a vehicle seat.

[0028] The invention also relates to a steering wheel for a vehicle. According to the invention, the steering wheel is equipped with a measuring module of an occupancy detection device as described above.

[0029] The invention also relates to a vehicle seat for a vehicle. According to the invention, the vehicle seat is equipped with a measuring module of an occupancy detection device as described above.

[0030] The invention further relates to a method for detecting the occupancy state of a vehicle component. According to the invention, the method is provided that the occupancy state is detected using at least one measuring module, which has a first electrode connected to a first terminal of the measuring module, is electrically isolated from a reference potential and forms a first electrical capacitance with respect to it; the measuring module has a second electrode connected to a second terminal of the measuring module, is electrically isolated from the reference potential and forms a second electrical capacitance with respect to it; the first and second electrodes are capacitively coupled by a coupling capacitance; and the first and second capacitances are determined by means of at least three measurement steps, thus generating a first and second capacitance value.The quotient between the capacity values ​​is calculated, and an occupancy signal is generated if the quotient deviates from a predetermined target quotient by a specified amount.

[0031] Regarding the advantages of the method according to the invention and its advantageous embodiments, reference is made to the above statements in connection with the occupancy detection device according to the invention and its advantageous embodiments.

[0032] The invention is explained in more detail below with reference to exemplary embodiments; the following are shown as examples: Fig. 1 An embodiment of an occupancy detection device according to the invention, wherein a preferred embodiment of a measuring module of the occupancy detection device is shown in more detail, Fig. 2. In more detail, a preferred design of an evaluation device, which, for example, is used for the occupancy recording device according to Fig. 1 is suitable, Fig. 3 an embodiment of a preferred operating mode of the evaluation device according to Fig. 2 in the form of a flowchart, Fig. 4 a further embodiment of a preferred mode of operation of the evaluation device according to Fig. 2 in the form of a flowchart, Fig. 5 an embodiment of an occupancy detection device according to the invention, which is equipped with a heating function, Fig. 6 a preferred embodiment of a in the Fig. The 5 shown disconnect switch in more detail, Fig. 7. a measurement profile when a voltage pulse is applied to the measurement module, Fig. 8 an embodiment of an arrangement with a steering wheel in which a measuring module of an embodiment of an occupancy detection device according to the invention is integrated, Fig. 9 an embodiment of an arrangement with a vehicle seat in which a measuring module of an embodiment of an occupancy detection device according to the invention is integrated, and Fig. 10-13 the switching states during the different measurement steps.

[0033] For the sake of clarity, the same reference symbols are always used in the figures for identical or comparable components.

[0034] The Fig. Figure 1 shows an embodiment of an occupancy detection device 10 according to the invention, which is used to detect the occupancy status of a [unit of measurement] in the Fig. 1. Vehicle component not shown is suitable. The occupancy detection device 10 according to Fig. 1 comprises a measuring module 100 and an evaluation unit 200 connected to it.

[0035] A first electrode end 111 of a first electrode 110 of the measuring module 100 is connected to a first connection point 101 of the measuring module 100. The first electrode 110 is electrically insulated from a reference potential BP, which can be, for example, the ground potential of a vehicle or the earth potential, and forms a first electrical capacitance with it, which has a first capacitance value C1.

[0036] The second electrode end 112 of the first electrode 110 is not connected to any terminal of the measuring module 100 or is electrically unconnected; for better understanding, it should be mentioned now that this is the case in the version according to Fig. 5 is different because the second electrode end 112 is connected to a heating connection point 103 of the measuring module 100, as will be explained in detail below.

[0037] The first electrode end 121 of a second electrode 120 of the measuring module 100 is connected to a second terminal 102 of the measuring module 100. The second electrode 120 is also electrically insulated from the reference potential BP and forms a second electrical capacitance with it, which has a second capacitance value C2. The second electrode end 112 of the second electrode 120 is also not connected to any terminal of the measuring module 100 or is also electrically unconnected.

[0038] The first and second electrodes 110 and 120 are arranged close together, so that they are electrically capacitively coupled to each other and together form a coupling capacitance which has a coupling capacitance value C3.

[0039] The first and second electrodes 110 and 120 are preferably insulated from the reference potential BP using the same dielectric, so that changes in the dielectric constant caused by environmental influences (temperature changes, moisture, humidity changes, electromagnetic radiation, etc.) or aging will affect both capacitance values ​​C1 and C2 in at least approximately the same way; this means specifically that environmental influences or aging will not cause any change, or at least not a relevant change, in the ratio C1 / C2 between the first capacitance value C1 and the second capacitance value C2.

[0040] The evaluation unit 200 is designed to determine the first and second capacities by means of at least three measurement steps, forming the first and second capacity values ​​C1 and C2, to calculate the quotient C1 / C2 between the capacity values ​​and to generate an occupancy signal SB if the quotient C1 / C2 deviates from a predetermined target quotient Qsoll beyond a predetermined limit, preferably, however, only under the condition that the measurement results are plausible.

[0041] The Fig. Figure 2 shows a preferred configuration of the evaluation unit 200 of the occupancy recording unit 10 according to Fig. 1. In more detail. The evaluation unit 200 comprises, among other things, a computing unit 211 and a memory 212 in which a computer program product CPP and the aforementioned target quotient Qsoll are stored non-volatilely. When the computing unit 211 executes the computer program product CPP, the computer program product determines the operation of the evaluation unit 200 or at least partially determines its operation.

[0042] The evaluation unit 200 also includes a large number of transistors, of which in the Fig. The eight transistors shown are labelled T1 to T8. Each transistor, T1 to T8, can be controlled by the computing unit 211 via control lines not shown.

[0043] The evaluation unit 200 also includes two AD converters AD1 and AD2, which can be read by the computing unit 211 via readout lines (also not shown).

[0044] The computing unit 211, the memory 212, the transistors T1 to T8 and the two A / C converters AD1 and AD2 are in the embodiment according to Fig. 2 components of a measuring device, preferably designed as a microcontroller 210.

[0045] A first connection port P1 of the microcontroller 210 is directly connected to the first connection point 101 of the measuring module 100. A second connection port P2 of the microcontroller 210 is indirectly connected to the first connection point 101 of the measuring module 100 via a first series resistor R1.

[0046] A third connection port P3 of the microcontroller 210 is directly connected to the second connection point 102 of the measuring module 100. A fourth connection port P4 of the microcontroller 210 is indirectly connected to the second connection point 102 of the measuring module 100 via a second series resistor R2.

[0047] The microcontroller 210 or its computing unit 211 can selectively connect terminals 101 and 102 to the reference potential BP, put them into a high-impedance tristate state, or apply a measurement signal by switching transistors T1 to T8 on and off; transistors T1 to T8 thus enable the microcontroller 210 or its computing unit 211 to perform a large number of different measurement steps in succession.

[0048] The Fig. Figure 3 shows, in the form of a flowchart, a preferred embodiment of the operation of the microcontroller 210 and thus implicitly also a preferred embodiment of the computer program product CPP according to Fig. 2, specifically in the case that the microcontroller 210 is to check whether a vehicle component is occupied or not.

[0049] In a first measurement step MS1, the microcontroller 210 measures the capacitance between the first terminal 101 and the reference potential BP as the first auxiliary capacitance measurement Cm1, after it has connected the second terminal 102 to the reference potential BP. Fig. 10 indicates the corresponding switching state.

[0050] In a second measurement step MS2, the microcontroller 210 measures the capacitance between the first terminal 101 and the reference potential BP as a second auxiliary capacitance measurement Cm2, after switching the second terminal 102 into a high-impedance tristate state. Fig. 11 indicates the corresponding switching state.

[0051] In a third measurement step MS3, the microcontroller 210 measures the capacitance between the second terminal 102 and the reference potential BP as the third auxiliary capacitance measurement Cm3, after it has connected the first terminal 101 to the reference potential BP. Fig. 12 indicates the corresponding switching state.

[0052] The order of the three measurement steps MS1 to MS3 is arbitrary.

[0053] In a calculation step RS, the microcontroller 210 determines the first capacitance value C1 according to C1=Cm1−Cm3⋅(Cm1−Cm2) and the second capacity value C2 according to C2=Cm2−Cm3⋅(Cm1−Cm2) where C1 denotes the first capacity value, C2 the second capacity value, Cm1 the first auxiliary capacity measurement, Cm2 the second auxiliary capacity measurement, and Cm3 the third auxiliary capacity measurement.

[0054] In a capacity check step BPS, the microcontroller 210 checks whether the quotient C1 / C2 between the first capacity value C1 and the second capacity value C2 deviates from the specified target quotient Qsoll beyond a specified limit MAX and generates corresponding output signals, for example according to

[0055] |C1 / C2 - Qsoll| > MAX ⇒ Generation of the occupancy signal SB, which indicates an occupied state of the vehicle component, and

[0056] |C1 / C2) - Osoll| < MAX ⇒ Generation of a free signal FS, which can also be called an unoccupied signal and indicates an unoccupied state of the vehicle component.

[0057] The Fig. Figure 4 shows, in the form of a further flowchart, a preferred further development of the embodiment according to Fig. 3.

[0058] During further training according to Fig. In step 4, the microcontroller 210 also performs a fourth measurement step MS4, in which it measures the capacitance between the second terminal 102 and the reference potential BP as the fourth auxiliary capacitance measurement Cm4, after switching the first terminal 101 into the high-impedance tristate state. Fig. 13 indicates the corresponding switching state.

[0059] Furthermore, in the calculation step RS, the microcontroller 210 calculates the coupling capacitance value C3 according to C3=Cm3⋅(Cm1−Cm2) The microcontroller 210 then performs a plausibility check (PPS) to verify whether the fourth auxiliary capacitance measurement, Cm4, corresponds to the target capacitance measurement, Cs4, or deviates from it too significantly. The target capacitance measurement, Cs4, is preferably calculated as follows: Cs4=C1⋅C2+C1⋅C3+C2⋅C3C2+C3

[0060] If the difference between the fourth auxiliary capacity measurement Cm4 and the target capacity measurement Cs4 falls below a predefined deviation limit CMAX, the measurement result is plausible and a plausibility signal PS is output; otherwise, a warning signal WS is output, which warns of a lack of plausibility and preferably blocks the output of the occupancy signal SB, for example according to |Cm4−Cs4| <CMAX⇒Erzeugung eines Plausibilita¨tssignalsPS |Cm4−Cs4|>CMAX⇒Generation of a warning signal WS and blocking of an output of the occupancy signal SB.

[0061] The Fig. Figure 5 shows a further embodiment of an occupancy detection device 10 according to the invention, which is suitable for detecting the occupancy status of a vehicle component.

[0062] At the occupancy recording device 10 according to Fig. 5 is the first electrode 110 with the first electrode end 111 connected to the first connection point 101 and with the second electrode end 112 (see Fig. 1) connected to a heating connection point 103 of the measuring module 100.

[0063] A heating operation switching device 220 is connected between the microcontroller 210 and the electrode 110 of the measuring module 100. This device enables the application of a system voltage Ub between the first terminal 101 and the heating terminal 103 of the measuring module 100, allowing the first electrode 110 to operate as a heating element. For this purpose, the heating operation switching device 220 has a first switching device 221 between the system voltage Ub and the first terminal 101, and a second switching device 222 between the heating terminal 103 and the reference potential BP.

[0064] To protect the connection ports P1 and P2 of the microcontroller 210 from the on-board voltage Ub, a disconnect switch 223 is connected between connection ports P1 and P2 and the first switching device 221 of the heating operation switching device 220. In the open state, the disconnect switch 223 disconnects the first connection point 101 from the microcontroller 210, and in the closed state, it connects the first connection point 101 to the microcontroller 210. The disconnect switch 223 thus enables heating operation as an alternative to measurement operation or occupancy testing; the heating operation and the measurement operation are preferably carried out sequentially using a time-division multiplexing method.

[0065] The first switching device 221, the second switching device 222 and the disconnect switch 223 are preferably controlled by the microcontroller 210 via connection ports and control lines not shown.

[0066] Of course, a heating connection point and a heating operation switching device can also be provided for the second electrode 120 if the second electrode 120 is to be used for heating.

[0067] The Fig. Figure 6 shows a preferred embodiment of the [unclear] in the Fig. 5 shown disconnect switch 223 in more detail.

[0068] Regarding the above in connection with the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5 to Fig. In the embodiments described in section 6, it can advantageously be provided that the microcontroller 210 performs the first measurement step MS1 and the second measurement step MS2 by applying a measurement pulse to the first terminal 101 via the first series resistor R1 and determining the first and second auxiliary capacitance measurement values ​​Cm1 and Cm2 by evaluating the time course of the voltage applied to the first terminal 101.

[0069] In the third measurement step MS3, the microcontroller 210 preferably applies a measurement pulse to the second terminal 102 via the second series resistor R2 and determines the third auxiliary capacitance measurement value Cm3 by evaluating the time course of the voltage applied to the second terminal 102.

[0070] The Fig. Figure 7 shows, by way of example, the increase in the voltage applied to the first connection point 101 and thus to the first connection port P1 in the case of an output of a rectangular voltage pulse at the second connection port P2.

[0071] Examples include: Fig. Figure 7 shows the curves for two different load capacities of 300pF and 350pF respectively, to visualize the difference in the measured value curve.

[0072] Preferably, a sampling time ta is chosen for evaluation within the "linear" range of the exponential rise of the voltage curve. The load capacitance is preferably determined from the measured voltage using the following basic formula: Uc(t)=U0(1−e−tR1C) where Uc is the voltage at the first connection port P1, U0 is the amplitude of the voltage pulse at the second connection port P2, and C is the load capacitance sought at the first connection point 101, which has the auxiliary capacitance measurement value Cm1 or Cm2 depending on the circuit configuration of the third and fourth connection ports P3 and P4.

[0073] The desired capacity C is obtained C=−taR1∗ln(1−Uc(ta)U0) If a single measurement pulse is set to approximately 500ps, it is possible to complete the four measurement steps MS1 to MS4 of a cycle explained above in 2ms.

[0074] Naturally, recording a large number of pulses is useful to average the result and minimize potential interference. A fast response time of less than 100 ms is therefore achievable in practice.

[0075] Alternatively or additionally, in the first and / or second measurement step MS1 and MS2, the microcontroller 210 can each inject an alternating current into the first terminal 101 or apply an alternating voltage to the first terminal 101 and determine the first and / or second auxiliary capacitance measurement value Cm1 and Cm2 by evaluating the alternating voltage or current applied to the first terminal 101, for example by evaluating the magnitude and phase or the in-phase and quadrature components.

[0076] Alternatively or additionally, in the third and / or fourth measurement step MS3 or MS4, the microcontroller 210 can inject an alternating current into the second terminal 102 or apply an alternating voltage to the second terminal 102 and determine the third and / or fourth auxiliary capacitance measurement value Cm3 or Cm4 by evaluating the alternating voltage or current applied to the second terminal 102, for example by evaluating the magnitude and phase or the in-phase and quadrature components.

[0077] The Fig. Figure 8 shows an occupancy detection device 10 in the form of a steering wheel touch detection device, in which the measuring module 100 is integrated into a vehicle steering wheel 500. The electrodes of the measuring module 100 are preferably separated from the steering wheel frame, which lies on the reference potential, by foam or the like. The evaluation device 200 is preferably spatially separated from the measuring module 100 and the steering wheel 500 and is located, for example, in a separate control unit of the vehicle.

[0078] The Fig. Figure 9 shows an occupancy detection device 10 in the form of a seat occupancy detection device, in which the measuring module 100 is integrated into a seat surface of a vehicle seat 600. The electrodes of the measuring module 100 are preferably separated from a seat frame at the reference potential by insulating material. The evaluation unit 200 is preferably spatially separated from the measuring module 100 and from the vehicle seat 600 and is located, for example, in a separate control unit of the vehicle.

[0079] In the exemplary embodiments according to the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig.9 shows that only one measurement module 100 is connected to the evaluation unit 200 or the microcontroller 210 as an example; of course, more than one measurement module 100 can be connected to the evaluation unit 200 or the microcontroller 210 if the evaluation unit 200 or the microcontroller 210 is equipped with correspondingly more connection ports.

[0080] Finally, it should be mentioned that the features of all the embodiments described above can be combined with each other in any way to form further embodiments of the invention.

[0081] Furthermore, all features of dependent claims can be combined individually with each of the subordinate claims, either individually or in any combination with one or more other dependent claims, to obtain further embodiments. Reference symbol list 10 Occupancy recording device 100 measuring modules 101 first junction 102 second exit 103 Heating connection point 110 first electrode 111 first electrode end 112 second electrode end 120 second electrode 121 first electrode end 122 second electrode end 200 evaluation unit 210 Microcontroller 211 Computing equipment 212 storage 220 Heating operating switch 221 first switching device 222 second switching device 223 Disconnect switch 500 vehicle steering wheels 600 vehicle seats AD1 AD converter AD2 AD converter BP reference potential BPS occupancy check step C1 first capacity value C1 / C2 ratio C2 second capacity value C3 coupling capacity value Cm1-Cm4 Auxiliary Capacity Measurements CPP Computer Program Product CS4 target capacity measurement FS free signal MS1-MS4 measuring steps P1-P4 connection ports PPS plausibility check step PS plausibility signal Qsoll Target quotient R1 first series resistor R2 second series resistor RS calculation step SB occupancy signal ta sampling time T1-T8 transistors USB on-board power WS warning signal

Claims

Occupancy detection device (10) for detecting the occupancy status of a vehicle component, characterized in that: - the occupancy detection device (10) comprises an evaluation unit (200) and at least one measuring module (100) connected to the evaluation unit (200); - the at least one measuring module (100) has a first electrode (110) which is connected to a first terminal (101) of the measuring module (100), is electrically isolated from a reference potential (BP) and forms a first electrical capacitance with it; - the at least one measuring module (100) has a second electrode (120) which is connected to a second terminal (102) of the measuring module (100), is electrically isolated from the reference potential and forms a second electrical capacitance with it; - the first and second electrodes are capacitively coupled by a coupling capacitance; and - the evaluation unit (200) is configured toBy including at least three measurement steps (MS1-MS3), the first and second capacities are determined by forming a first and second capacity value (C1, C2), the quotient (C1 / C2) between the capacity values ​​is calculated, and an occupancy signal (SB) is generated if the quotient deviates from a predetermined target quotient (Qtarget) beyond a predetermined limit. Occupancy detection device (10) according to claim 1, characterized in that: - the evaluation device (200) measures the capacitance between the first terminal and the reference potential as the first auxiliary capacitance measurement (Cm1) in a first measurement step (MS1) when the second terminal is connected to the reference potential; - the evaluation device (200) measures the capacitance between the first terminal and the reference potential as the second auxiliary capacitance measurement (Cm2) in a second measurement step (SM2) when the second terminal is switched to a high-impedance tristate state; and - the evaluation device (200) measures the capacitance between the second terminal and the reference potential as the third auxiliary capacitance measurement (Cm3) in a third measurement step (MS3) when the first terminal is connected to the reference potential or switched to the high-impedance tristate state; - the order of the three measurement steps is arbitrary. Occupancy detection device (10) according to claim 2, characterized in that the evaluation device (200) - in the third measuring step connects the first connection point to the reference potential and measures the third auxiliary capacity measurement value after it has connected the first connection point to the reference potential, - calculates the first capacity value according to C 1 = C m 1 − C m 3 ⋅ ( C m 1 − C m 2 ) and - the second capacity value is calculated according to C 2 = C m 2 − C m 3 ⋅ ( C m 1 − C m 2 ) - where C1 denotes the first capacity value, C2 the second capacity value, Cm1 the first auxiliary capacity measurement, Cm2 the second auxiliary capacity measurement and Cm3 the third auxiliary capacity measurement. Occupancy detection device (10) according to claim 3, characterized in that the evaluation device (200) - in a fourth measuring step (MS4) switches the first terminal to the high-impedance tristate state and measures the capacitance between the second terminal and the reference potential as a fourth auxiliary capacitance measurement value (Cm4) after it has switched the first terminal to the high-impedance tristate state, - calculates a coupling capacitance value indicating the coupling capacitance according to C 3 = C m 3 ⋅ ( C m 1 − C m 2 ) where C3 denotes the coupling capacitance value, and - subjects the fourth auxiliary capacity measurement, the first capacity value, the second capacity value and the coupling capacity value to a plausibility check. Occupancy detection device (10) according to claim 4, characterized in that the evaluation device (200) checks, as part of the plausibility check, whether the fourth auxiliary capacity measurement value deviates from a target capacity measurement value (Cs4) beyond a predetermined capacity deviation measure, wherein the evaluation device (200) calculates the target capacity measurement value Cs4 according to Cs4 = C1 ⋅ C2 + C1 ⋅ C3 + C2 ⋅ C3 / C2 + C3 Occupancy detection device (10) according to one of the preceding claims, characterized in that - the evaluation device (200) applies a measurement pulse to the first connection point via a first series resistor (R1) in the first and second measurement step and determines the first and second auxiliary capacitance measurement value by evaluating the time course of the voltage applied to the first connection point and - the evaluation device (200) applies a measurement pulse to the second connection point via a second series resistor (R2) in the third measurement step and determines the third auxiliary capacitance measurement value by evaluating the time course of the voltage applied to the second connection point. Occupancy detection device (10) according to one of the preceding claims, characterized in that - the evaluation device (200) in the first and second measuring step feeds an alternating current into the first connection point or applies an alternating voltage to the first connection point and determines the first and second auxiliary capacity measurement value by evaluating the alternating voltage or the alternating current flowing at the first connection point and - the evaluation device (200) in the third measuring step feeds an alternating current into the second connection point or applies an alternating voltage to the second connection point and determines the third auxiliary capacity measurement value by evaluating the alternating voltage or the alternating current flowing at the second connection point. Occupancy detection device (10) according to one of the preceding claims, characterized in that - the first electrode is connected with a first electrode end (111) to the first connection point of the measuring module (100) and with a second electrode end (112) to a heating connection point (103) of the measuring module (100) and - a heating operation switching device (200) is provided which enables the application of a system voltage (Ub) between the first connection point and the heating connection point of the measuring module (100) and the operation of the first electrode as a heating element. Occupancy detection device (10) according to claim 8, characterized in that a disconnect switch (223) is connected between a measuring device (210) of the occupancy detection device (10) and a first switching device (221) of the heating operation switching device, and the disconnect switch, in the open state, disconnects the first connection point and the first switching device (221) of the heating operation switching device from the measuring device and, in the closed state, connects the first connection point and the first switching device (221) to the measuring device. Occupancy detection device (10) according to one of the preceding claims, characterized in that the occupancy detection device (10) is a steering wheel touch detection device and the measuring module (100) is designed for integration into a vehicle steering wheel (500). Occupancy detection device (10) according to one of the preceding claims 1 to 9, characterized in that the occupancy detection device (10) is a seat occupancy detection device and the measuring module (100) is designed for integration into a vehicle seat (600). Steering wheel for a vehicle, characterized in that the steering wheel (500) is equipped with a measuring module (100) of an occupancy detection device (10) according to claim 10. Vehicle seat, characterized in that the vehicle seat (600) is equipped with a measuring module (100) of an occupancy detection device (10) according to claim 11. A method for detecting the occupancy state of a vehicle component, characterized in that: - the occupancy state is detected using at least one measuring module (100); - the at least one measuring module (100) has a first electrode which is connected to a first terminal of the measuring module (100), is electrically insulated from a reference potential and forms a first electrical capacitance with respect to it; - the at least one measuring module (100) has a second electrode which is connected to a second terminal of the measuring module (100), is electrically insulated from the reference potential and forms a second electrical capacitance with respect to it; - the first and second electrodes are capacitively coupled by a coupling capacitance; and - the first and second capacitances are determined by means of at least three measurement steps, forming a first and second capacitance value.The quotient between the capacity values ​​is calculated, and an occupancy signal is generated if the quotient deviates from a predetermined target quotient by a specified amount.

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