Input device for a motor vehicle with voltage-based error detection

Abstract

The invention relates to an input device (1) for safety-relevant functions of a motor vehicle, having a switch contact (3) with a first connection (4) and a mating contact (5) with a second connection (6). A first resistor (9) is connected between a voltage source connection (8) and one connection (4, 6) of a switching element (2), a second voltage source connection (7) being connected to the other connection (4, 6) of the switching element (2). A measuring node (10) is arranged between the first resistor (9) and the associated connection (4, 6), through which measuring node (10) an actuation-related voltage can be captured. The problem addressed by the invention is to develop input devices of the type mentioned, such that they can be used in motor vehicles for safety-relevant applications. This problem is solved by the switch contact (3) having a third connection (12), at which a second resistor (13) is arranged which is connected to the second connection (6) of the switching element (2).

Description

Technical Field

[0001] This invention relates to an input device for safety-related functions of a motor vehicle. The input device includes a switching element having a switch contact with a first connection portion and a mating contact with a second connection portion. When the input device is actuated, the switch contact contacts the mating contact. Furthermore, the input device includes a first resistor and a first voltage source connection portion and a second voltage source connection portion, through which an operating voltage for the input device can be provided. Here, the first voltage source connection portion is connected to one of the connection portions of the switching element, and the second voltage source connection portion is connected to the other connection portion of the switching element via the first resistor. Additionally, the input device has a measuring node disposed between the first resistor and the associated connection portion of the switching element, and connected to the measuring connection portion. Therefore, an actuation-related voltage dependent on the actuation of the input device can be detected via the measuring connection portion. Background Technology

[0002] Input devices with corresponding switching elements are known from the prior art. For example, US 6,423,918 B1 discloses an input device with a switching element having a circular or dome-shaped switch contact that, when actuated, contacts a mating contact on a printed circuit board. The circular or dome-shaped switch contact is held on the printed circuit board by a holding element.

[0003] US 7,825,345 B1 discloses an input device in the form of a miniature switch, which can be actuated from the rear. For this purpose, the miniature switch has a circular or dome-shaped switching element within its housing, which, when actuated, contacts mating contacts within the housing. The corresponding contacts are connected to a connection portion disposed outside the miniature switch housing.

[0004] US 2014 / 0144765 A1 discloses an input device having a switching element with a circular or dome-shaped switch contact that, when actuated, contacts a mating contact on a printed circuit board. The circular or dome-shaped switch contact is held on the printed circuit board by a holding element.

[0005] EP 2 001 034 A2 discloses an input device having a switching element with a switch contact that, when actuated, contacts a mating contact on a printed circuit board. The switch contact is connected to a first voltage source connection via electrodes, and the mating contact is connected to a second voltage source connection via a first resistor. The voltage drop across the resistor is measured, and this voltage drop is a measure of the actuation of the input device.

[0006] The drawback of the cited prior art is that faults in the switch contacts cannot be reliably detected because, for example, an open circuit in the switch contacts cannot be distinguished from a fault in the actuation input device. Therefore, such an input device cannot be used for safety-related applications, such as autonomous driving of motor vehicles.

[0007] Therefore, the object of the present invention is to further develop input devices of the aforementioned type so that they meet higher safety standards and are thus usable for safety-related applications in motor vehicles. Summary of the Invention

[0008] This objective is achieved through the solution of this application, which provides a third connection portion connected to a switch contact, wherein a second resistor is provided connected to the second and third connections of the switch element. This allows for the detection of an erroneous voltage via the measurement connection portion in the event of a fault at the measurement node of the switch contact, and enables the differentiation of this erroneous voltage from the actuation-related voltage. This has the advantage that the switching state (open and closed) of the switch element can be clearly distinguished from a fault or failure state of the switch contact, as each state provides a clearly identifiable voltage at the measurement node.

[0009] For the purposes of this invention, a fault in the switch contact is understood as: the opening of the switch contact causing a voltage at the measuring node that can be distinguished from the switch state and / or any change in the resistance of the switch contact. This is particularly applicable to cases where the aforementioned fault occurs in the region of the switch contact between the first and third connecting parts. In this case, the electrical connection between the first and third connecting parts is affected by the fault.

[0010] In an advantageous embodiment of the input device according to the invention, an evaluation circuit is provided that detects the voltage at a measuring node via a measuring connection, thereby identifying faults in the actuation and / or switching contacts of the input device. This has the advantage that the individual voltages at the measuring nodes can be identified and evaluated accordingly, thus definitively determining the state of the input device. Another advantage of the evaluation circuits is that they can further process information, for example, through a controller or control unit, which may be part of the evaluation circuit, to trigger corresponding functions in the vehicle or output corresponding warnings.

[0011] Alternatively or additionally, the input device according to the invention may be provided with a circular or dome-shaped switch contact, and preferably, the first and third connecting portions are disposed in opposite regions of the circular or dome-shaped switch contact. On the one hand, this has the advantage that when the circular or dome-shaped switch contact is actuated, passive tactile feedback to the actuator can be generated through the circular or dome-shaped switch contact.

[0012] In the sense of a dome switch or actuator, due to its circular or dome-shaped form, the metal switch contact exhibits non-linear deformation characteristics, with its actuating force continuously increasing. As a result, the switch contact suddenly yields only when actuated at a certain pressure point, leading to corresponding tactile feedback at the actuator. After releasing the switch contact, it returns to its initial state.

[0013] On the other hand, arranging the first and third connecting portions in the opposing areas of the circular or dome-shaped switch contacts has the advantage of improving error detection of the input device according to the invention. This is because this measure maximizes or at least increases the switch contact area between the connecting portions, thereby allowing any faults within that area to be detected accordingly.

[0014] In another advantageous embodiment of the input device according to the invention, the switch contact has a flat design. Preferably, the first and third connecting portions are located near the edge of the flat switch contact or in opposite regions. The flat contact may be resilient and / or may be embossed to provide tactile feedback to the actuator. Embossing can also be used here in the sense of a chuck or ratchet to provide nonlinear deformation characteristics with increasing driving force.

[0015] On the other hand, the arrangement of the first and third connecting portions in the opposite area of ​​the flat switch contacts has the advantage of improving fault detection of the input device according to the invention. This is because this measure maximizes or at least increases the switch contact area between the connecting portions, thereby allowing any faults within that area to be detected accordingly.

[0016] Alternatively or additionally, in the input device according to the invention, a third resistor may be provided between the first voltage source connection and the corresponding connection of the switching element, such that the specific connection of the switching element is connected to the first voltage source connection via the third resistor. By means of this additional resistor, actuation of the switching contacts can be detected by an actuation-related voltage, which differs from either the operating voltage or the operating voltage potential. This further improves the reliability of the input device according to the invention, because actuation can now be distinguished from the closure of a measuring connection for one of the operating voltage potentials in the event of a fault.

[0017] In another advantageous embodiment of the input device according to the invention, the second voltage source connection is connected to a positive operating voltage, and the first voltage source connection is connected to a reference potential of the input device, preferably grounded. This measure allows the operating voltage to be provided in a simple manner. Alternatively, the first voltage source connection may be connected to a positive operating voltage, and the second voltage source connection may be connected to a reference potential of the input device, preferably grounded.

[0018] Alternatively or additionally, in the input device according to the invention, an actuation-related voltage can be detected at the measurement node in the unactuated state of the input device. This actuation-related voltage is generated by the voltage division ratio between a first resistor, a second resistor, and preferably a third resistor. The actuation-related voltage in the unactuated state is calculated as follows, where U1 is the actuation-related voltage, U... B For the positive operating voltage, R1 is the first resistor, R2 is the second resistor, and R3 is the third resistor.

[0019] (If R1 exists in U) B And there is no R3)

[0020] or

[0021] (If R1 is present at ground and R3 is not present)

[0022] or

[0023] (If R1 exists in U) B And has R3)

[0024] or

[0025] (If R1 is present at ground and R3 is present)

[0026] This has the advantage that the actuation-related voltage is significantly different from the actuation state or error state, thus increasing the safety of the input device according to the invention.

[0027] In another advantageous embodiment of the input device according to the invention, in the actuated state of the input device, an actuation-related voltage can be detected at the measurement node. This voltage corresponds to the voltage or potential at the first voltage source connection, or is generated by the voltage division ratio between the first resistor and the third resistor. The actuation-related voltage in the actuated state is calculated as follows, where U1 is the actuation-related voltage, U... B For the positive operating voltage, R1 is the first resistor, R2 is the second resistor, and R3 is the third resistor.

[0028] (If R1 exists in U) B And there is no R3)

[0029] or

[0030] (If R1 is present at ground and R3 is not present)

[0031] or

[0032] (If R1 exists in U)B And has R3)

[0033] or

[0034] (If R1 is present at ground and R3 is present)

[0035] This has the advantage that the actuation-related voltage is significantly different from the non-actuated or erroneous state, thereby increasing the safety of the input device according to the invention.

[0036] In another advantageous embodiment of the input device according to the invention, in the event of a switch contact failure, preferably in the event of a switch contact opening, particularly between the first and third connecting portions of the switch contact, and preferably if the switch contact is not actuated, an error voltage corresponding to the voltage or potential of the second voltage source connection portion can be detected at the measuring node. The error voltage is calculated as follows: U2 is the error voltage, U... B For the positive operating voltage, R1 is the first resistor, R2 is the second resistor, and R3 is the third resistor.

[0037] (If R1 exists in U) B And there is no R3)

[0038] or

[0039] (If R1 is present at ground and R3 is not present)

[0040] or

[0041] (If R1 exists in U) B And has R3)

[0042] or

[0043] (If R1 is present at ground and R3 is present)

[0044] This has the advantage that the error voltage is significantly different from the unactuated or actuated state, thus increasing the safety of the input device according to the invention.

[0045] In another advantageous embodiment of the input device according to the invention, the evaluation unit includes an analog-to-digital converter, such that the detected actuation-related voltage can be converted into a digital value and processed digitally. The digital value of the measured voltage is particularly insensitive to interference, thus improving the security of the input device according to the invention. Furthermore, the digital value can be processed particularly effectively, for example, for authenticity checks, which further enhances the security of the input device according to the invention.

[0046] Alternatively or additionally, when the input device according to the invention is actuated, the input device can provide a current- or conductive contact between the switching contact and the mating contact. This means that the switching contact and the mating contact are positioned relative to each other in a manner that establishes a conductive connection between them. In particular, this means a direct electrical contact between the switching contact and the mating contact. This type of contact produces reliable contact in a particularly advantageous manner, providing a clearly discernible voltage value at the measuring node.

[0047] In a particularly advantageous embodiment of the input device according to the invention, when the input device is actuated, the contact between the switch contact and the mating contact is resistive or capacitive. According to a first alternative, this means that the contact between the switch contact and the mating contact is achieved via a resistive element, such as a resistive material or a corresponding coating. This has the advantage of introducing an additional resistive element during actuation, which interacts with a second resistor, thereby providing a particularly reliable and distinguishable voltage value at the measurement node.

[0048] According to the second alternative, the contact can also be implemented via a capacitive element, such as a capacitor, so that when the AC voltage is used as the operating voltage and the corresponding actuation occurs, the transition between the switching contact and the mating contact becomes low impedance. This also advantageously provides a reliable and distinguishable voltage value at the measuring node.

[0049] Alternatively or additionally, in the input device according to the invention, the switching elements and resistors are arranged on a printed circuit board, and preferably, at least the first and third connections are implemented as solder joints on the printed circuit board. With this measure, the input device according to the invention can be configured in a particularly compact design.

[0050] In another advantageous embodiment of the input device according to the invention, a circular or dome-shaped switch contact is soldered to solder joints for the first and third connections, and a mating contact is disposed between these two solder joints on a printed circuit board. This allows the circular or dome-shaped switch contact to be advantageously supported on the printed circuit board to provide tactile feedback to the actuator in the sense of a dome switch. The mating contact arranged between the solder joints ensures reliable contact between the switch contact and the mating contact during actuation, as well as a compact design of the input device according to the invention.

[0051] In another advantageous embodiment of the input device according to the invention, additional support points are provided for the circular or dome-shaped switch contacts, and are preferably implemented as solder joints. As a result, the circular or dome-shaped switch contacts are held particularly securely on the printed circuit board, thereby improving the overall security of the input device according to the invention. Attached Figure Description

[0052] The invention will now be described in more detail based on preferred exemplary embodiments, and in particular with reference to the accompanying drawings. In the drawings:

[0053] Figure 1a A circuit diagram of a first advantageous exemplary embodiment of the input device according to the invention is shown schematically.

[0054] Figure 1b The circuit diagram schematically illustrates a first advantageous exemplary embodiment of the input device according to the invention in the unactuated state of the switching element.

[0055] Figure 1c The circuit diagram schematically illustrates a first advantageous exemplary embodiment of the input device according to the invention in the event of a failure of the switching element.

[0056] Figure 2a A circuit diagram of a second advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0057] Figure 2b A circuit diagram of a second advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0058] Figure 2c A circuit diagram of a second advantageous exemplary embodiment of the input device according to the invention is schematically shown in the event of a failure of the switching element.

[0059] Figure 3a A circuit diagram of a third advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0060] Figure 3b A circuit diagram of a third advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0061] Figure 3c A circuit diagram of a third advantageous exemplary embodiment of the input device according to the invention is schematically shown in the event of a failure of the switching element.

[0062] Figure 4a A circuit diagram of a fourth advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0063] Figure 4b A circuit diagram of a fourth advantageous exemplary embodiment of the input device according to the invention is schematically shown.

[0064] Figure 4c A circuit diagram of a fourth advantageous exemplary embodiment of the input device according to the invention is schematically shown in the event of a failure of the switching element.

[0065] Figure 5a A fifth advantageous exemplary embodiment of an input device with a printed circuit board according to the present invention is illustrated schematically.

[0066] Figure 5b A cross-sectional view of the printed circuit board of the input device according to a fifth exemplary embodiment of the present invention is shown.

[0067] Figure 6a A sixth advantageous exemplary embodiment of an input device with a printed circuit board according to the present invention is schematically illustrated, and

[0068] Figure 6b A cross-sectional view of the printed circuit board of the input device according to a sixth exemplary embodiment of the present invention is shown. Detailed Implementation

[0069] Figure 1a A circuit diagram of a first advantageous exemplary embodiment of the input device 1 according to the invention in an unactivated state is schematically shown. The input device 1 has a switching element 2 having a circular or dome-shaped switch contact 3, which, when actuated, can contact a mating contact 5. The switching element 2 has a first connection portion 4 on the circular or dome-shaped switch contact 3, and a first resistor 9 connected to a second voltage supply connection portion 8 is connected to this first connection portion 4. In this example, the applied operating voltage U... B It is positive. There is a measuring node 10 between the first resistor 9 and the first connection 4 of the switching element 2, at which a measuring connection 11 is provided for tapping the actuation-related voltage U1.

[0070] A second connection portion 6 of the switching element 2 is disposed on the mating contact 5. This second connection portion 6 connects the mating contact 5 to the first voltage source connection portion 7. In this example, the first voltage source connection portion 7 is connected to a reference potential of the input device 1 according to the invention; in this case, the reference potential is ground or ground potential. Furthermore, the switching element 2 has a third connection portion 12 disposed on the switching contact 3, located on the opposite side of the first connection portion 4. A second resistor 13 is connected between the second and third connection portions 6 and 12.

[0071] In the unactivated state of the input device 1 according to the present invention, or when the switching element 2 is not activated, an actuation-related voltage U1 generated by the voltage division ratio between the first resistor 9 and the second resistor 13 can be applied at the measuring connection 11. The following relationship applies: U1 is the actuation-related voltage, U... B The voltage is the positive operating voltage. R1 is the first resistor, and R2 is the second resistor.

[0072]

[0073] As will be shown, this voltage U1 is clearly distinguishable from the voltage of other states of the input device 1 according to the invention, thereby making it clear that the input device 1 according to the invention is not activated.

[0074] For example, Figure 1b It shows that according to Figure 1a An exemplary embodiment of the input device 1 according to the invention is shown, wherein the input device according to the invention is now in an actuated state. The switching element 2 has been actuated by a force F acting on the switching contact 3. Due to the action of the force F and the design of the switching element 2 having a circular or dome-shaped switching contact 3, the switching contact 3 deforms and becomes electrically connected or in contact with the mating contact 5. The corresponding deformation of the switching contact 3 also generates tactile feedback for the actuator.

[0075] As a result of actuation, the second resistor 13 between the second connection portion 6 and the third connection portion 12 of the switching element 2 is bridged or short-circuited, and the measuring node 10 is directly connected to the mating contact 5 of the switching element 2 or the second connection portion 6. In this exemplary embodiment, the second connection portion 6 is connected to the first voltage source connection portion 7, which is at the reference potential of the input device 1 according to the invention, which in this case is ground or ground potential. Therefore, the measuring node 10 is also grounded, so that the following actuation-related voltage U1 can be measured at the measuring connection portion 11:

[0076]

[0077] This voltage U1 is also significantly different from the voltage of other states of the input device 1 according to the invention. This means that the actuation of the input device 1 according to the invention can be clearly identified.

[0078] Figure 1c It shows that according to Figure 1a The input device 1 of the exemplary embodiment is shown in the example, wherein the fault has now occurred at the switch contact 3 of the switch element 2. Therefore, the input device 1 according to the invention is in an erroneous state. The erroneous state includes the disconnection 19 of the switch contact 3 of the switch element 2 between the first connection portion 4 and the third connection portion 12.

[0079] As a result, the connection between the first connection 4 and the other connections 6 and 12 of the switching element 2 is interrupted, causing the measuring node 10 to always be at the potential of the second voltage source connection 8, in which case, this potential is the operating voltage U. B Therefore, the following error voltage U2 can be measured at the measuring connection 11:

[0080]

[0081] This voltage U2 is also significantly different from the voltages of other states of the input device 1 according to the invention. This also clearly identifies the erroneous state of the input device 1 according to the invention.

[0082] Figure 2a Another exemplary embodiment of the input device 1 according to the present invention is shown. This example is essentially based on... Figure 1a In an exemplary embodiment, the first resistor 9 is now arranged between the first voltage source connection 7 and the second connection 6 of the switching element 2, instead of between the second voltage source connection 8 and the first connection 4 of the switching element 2. Therefore, the measuring node 10 with the measuring connection 11 is provided between the second connection 6 and the first resistor 9 of the switching element 2. Furthermore, the first connection 4 of the switching element 2 is now directly connected to the second voltage source connection 8. In this example, the first voltage source connection 7 is connected to the reference potential of the input device 1 according to the invention, which in this case is grounded. The second voltage source connection 8 is connected to the positive operating voltage U. B .

[0083] In the unactivated state of the input device 1 according to the second embodiment of the present invention, or when the switching element 2 is not activated, an actuation-related voltage U1 generated by the voltage division ratio between the first resistor 9 and the second resistor 13 can be applied at the measuring connection 11. The following relationship applies: U1 is the actuation-related voltage, U... B The voltage is the positive operating voltage. R1 is the first resistor, and R2 is the second resistor.

[0084]

[0085] This voltage U1 is significantly different from the voltage of the input device 1 in other states according to the second embodiment of the present invention. Therefore, the inactivity of the input device 1 according to the present invention can be clearly identified.

[0086] Figure 2b An input device 1 according to the invention is shown according to a second exemplary embodiment, wherein it is now in an actuated state. The switching element 2 has been actuated by a force F acting on the switching contact 3. Due to the action of the force F and the design of the switching element 2 having a circular or dome-shaped switching contact 3, the switching contact 3 deforms and becomes electrically connected or in contact with the mating contact 5.

[0087] As a result, the second resistor 13 between the second connection portion 6 and the third connection portion 12 of the switching element 2 is bridged or short-circuited, and the measuring node 10 is directly connected to the first connection portion 4 of the switching element 2. Since the first connection portion 4 is connected to the second voltage source connection portion 8 which is at a positive operating voltage potential, the measuring node 10 is also at a positive operating voltage potential, so the following actuation-related voltage U1 can be measured at the measuring connection portion 11:

[0088]

[0089] According to this second embodiment, the voltage U1 is also significantly different from the voltage of other states of the input device 1 according to the invention. This also clearly indicates the actuation of the input device 1 according to the invention.

[0090] Figure 2c It shows that according to Figure 2a The second exemplary embodiment of the input device 1 according to the invention, wherein a fault has now occurred at the switch contact 3 of the switching element 2. Therefore, the input device 1 according to the invention is in an erroneous state. The erroneous state includes a break 19 in the switch contact 3 of the switching element 2 between the first connection portion 4 and the third connection portion 12.

[0091] As a result, the connection between the first connection 4 and the other connections 6 and 12 of the switching element 2 is interrupted, causing the measuring node 10 to now be at the potential of the first voltage source connection 7, which corresponds to the reference potential here. Therefore, the following error voltage U2 can be measured at the measuring connection 11:

[0092]

[0093] This voltage U2 can also be significantly different from the voltage of other states of the input device 1 according to the second embodiment of the invention. Therefore, errors in the input device 1 according to the invention can also be clearly identified.

[0094] Figure 3a A third exemplary embodiment of the input device 1 according to the present invention is shown. This example is essentially based on... Figure 1a An exemplary embodiment is provided, wherein a third resistor 15 is now provided. The third resistor 15 is connected or arranged between the second connection portion 6 of the switching element 2 and the first voltage source connection portion 7. In this example, the first voltage source connection portion 7 is also connected to a reference potential of the input device 1 according to the invention, which is grounded, and the second voltage source connection portion 8 is connected to the positive operating voltage U. B .

[0095] In the unactivated state of the input device 1 according to the third embodiment of the present invention, or when the switching element 2 is not activated, an actuation-related voltage U1 generated by the voltage division ratio between the first resistor 9, the second resistor 13, and the third resistor 15 can be tapped at the measuring connection 11. The following relationship applies, where U1 is the actuation-related voltage, U... B For the positive operating voltage, R1 is the first resistor, R2 is the second resistor, and R3 is the third resistor.

[0096]

[0097] This voltage U1 can be clearly distinguished from the voltage of other states of the input device 1 according to the invention according to the third exemplary embodiment, and thus the inactivity of the input device 1 according to the invention can be clearly identified.

[0098] Figure 3b An input device 1 according to the invention is shown according to a third exemplary embodiment, wherein it is now in an actuated state. The switching element 2 has been actuated by a force F acting on the switching contact 3. Due to the action of the force F and the design of the switching element 2 having a circular or dome-shaped switching contact 3, the switching contact 3 deforms and becomes electrically connected or in contact with the mating contact 5.

[0099] As a result, the second resistor 13 between the second connection portion 6 and the third connection portion 12 of the switching element 2 is bridged or short-circuited, and the measuring node 10 is directly connected to the second connection portion 4 of the switching element 2. Therefore, the measuring node 10 is now located between the first resistor 9 and the third resistor 15, so that the following actuation-related voltage U1 can be measured at the measuring connection portion 11:

[0100]

[0101] According to this exemplary embodiment, the voltage U1 can also be clearly distinguished from other states of the input device 1 according to the invention, and thus the actuation of the input device 1 according to the invention can be clearly identified.

[0102] Figure 3c It shows according to Figure 3a In a third exemplary embodiment of the input device 1 according to the invention, a fault has now occurred at the switch contact 3 of the switching element 2. Therefore, the input device 1 according to the invention is in an erroneous state. This erroneous state includes a break 19 in the switch contact 3 of the switching element 2 between the first connection portion 4 and the third connection portion 12.

[0103] As a result, the connection between the first connection 4 and the other connections 6 and 12 of the switching element 2 is interrupted, causing the measuring node 10 to always be at the potential of the second voltage source connection 8, which corresponds to the positive operating voltage here. Therefore, the following error voltage U2 can be measured at the measuring connection 11:

[0104]

[0105] This voltage U2 can also be significantly different from the voltage of other states of the input device 1 according to the third embodiment of the invention. Therefore, errors in the input device 1 according to the invention can also be clearly identified.

[0106] Figure 4aA fourth exemplary embodiment of the input device 1 according to the present invention is shown. This example is essentially based on... Figure 2a An exemplary embodiment is provided, wherein a third resistor 15 is now provided. The third resistor 15 is connected or arranged between the first connection portion 4 and the second voltage source connection portion 8 of the switching element 2. In this example, the first voltage source connection portion 7 is also connected to the reference potential of the input device 1 according to the invention, which is grounded, and the second voltage source connection portion 8 is connected to the positive operating voltage U. B .

[0107] In the unactivated state of the input device 1 according to the fourth embodiment of the present invention, or when the switching element 2 is not activated, an operation-dependent voltage U1 generated by the voltage division ratio between the first resistor 9, the second resistor 13, and the third resistor 15 can be applied at the measuring connection 11. The following relationship applies, where U1 is the activation-related voltage, U... B For the positive operating voltage, R1 is the first resistor, R2 is the second resistor, and R3 is the third resistor.

[0108]

[0109] According to this exemplary embodiment, the voltage U1 can be clearly distinguished from the voltage of other states of the input device 1 according to the invention, and thus the inactivity of the input device 1 according to the invention can be clearly identified.

[0110] Figure 4b An input device 1 according to the invention is shown according to a fourth exemplary embodiment, wherein it is now in an actuated state. The switching element 2 has been actuated by a force F acting on the switching contact 3. Due to the action of the force F and the design of the switching element 2 having a circular or dome-shaped switching contact 3, the switching contact 3 deforms and becomes electrically connected or in contact with the mating contact 5.

[0111] As a result, the second resistor 13 between the second connection portion 6 and the third connection portion 12 of the switching element 2 is bridged or short-circuited, and the measuring node 10 is directly connected to the first connection portion 4 of the switching element 2. Therefore, the measuring node 10 is now located between the first resistor 9 and the third resistor 15, so that the following actuation-related voltage U1 can be measured at the measuring connection portion 11:

[0112]

[0113] This voltage U1 can also be clearly distinguished from the voltage of other states of the input device 1 according to this embodiment, and therefore the actuation of the input device 1 according to this embodiment can be clearly identified.

[0114] Figure 4c It shows that according to Figure 4aIn the fourth exemplary embodiment of the input device 1 according to the invention, a fault has now occurred at the switch contact 3 of the switching element 2. Therefore, the input device 1 according to the invention is in an erroneous state. The fault includes a break 19 between the switch contact 3 of the switching element 2 and the first connection portion 4 and the third connection portion 12.

[0115] As a result, the connection between the first connection 4 and the other connections 6 and 12 of the switching element 2 is interrupted, causing the measuring node 10 to now be at the potential of the first voltage source connection 7, which corresponds to the reference potential here. Therefore, the following error voltage U2 can be measured at the measuring connection 11:

[0116]

[0117] This voltage U2 is also significantly different from the voltage of other states of the input device 1 according to the fourth embodiment of the invention. Therefore, malfunctions of the input device 1 according to the invention can also be clearly identified.

[0118] Figure 5a A fifth exemplary embodiment of the input device 1 according to the invention is schematically illustrated, wherein circuitry of the input device 1 according to the invention is shown on a printed circuit board 16. The circuitry here substantially corresponds to that according to... Figure 3a An exemplary embodiment is provided, wherein the reference numerals for the various components are selected identically. The individual components are not repeated, as they are entirely similar to those described in the embodiment. Figure 3a An exemplary embodiment of the invention.

[0119] The switch contact 3 is circular or dome-shaped and is arranged on the printed circuit board 16. For this purpose, the switch element 2 has two connecting portions 4 and 12, which are implemented as solder points 17 on the printed circuit board 16. Furthermore, additional solder points 17 are provided on the printed circuit board 16 as support points 18 for the switch contact 3, used to fix the switch contact 2 to the printed circuit board 16. This allows the corresponding switch contact 3 to deform when actuated, generating tactile feedback to the actuator. This closes the contact between the switch contact 3 and the mating contact 5, which is arranged in the center below the switch contact 3.

[0120] The arrangement of the contacts is once again in Figure 5b As shown in the figure, Figure 5b Is it through Figure 5a The cross-sectional view along axis A-A' is shown here. The switch contact 3 is shown in a circular or dome shape, with the switch contact 3 fixed to solder joint 17, which also serves as the connecting portion 4, 12 of the switching element 2. A mating contact 5 is arranged at the center below the circular or dome-shaped switch contact 3. Figure 5bThe fifth exemplary embodiment of the invention, in an inactive state, shows the input device 1 according to the invention.

[0121] Figure 6a A sixth exemplary embodiment of the input device 1 according to the invention is schematically illustrated, wherein the circuitry of the input device 1 according to the invention is shown here on a printed circuit board 16. The circuitry here substantially corresponds to that according to... Figure 3a An exemplary embodiment is provided, wherein the reference numerals for the various components are selected identically. The individual components are not repeated, as they are entirely similar to those described in the embodiment. Figure 3a An exemplary embodiment of the invention.

[0122] The switch contact 2 has a flat design and is arranged on a printed circuit board 16. For this purpose, the switch element 2 has two connecting portions 4 and 12, which are implemented as solder points 17 on the printed circuit board 16. The switch contact 3 of the switch element 2 is designed to be resilient so as to close the contact between the switch contact 3 and the mating contact 5 in the sense of a button. The flat switch contact 3 also has a groove 20, so that the switch contact 3 has two separate connection areas, on which a first connecting portion 4 and a third connecting portion 12 are provided.

[0123] The arrangement of the contacts is once again in Figure 6b As shown in the figure, Figure 6b Through Figure 6a A cross-sectional view along axis B-B' is shown. Here, a flat form of the switch contact 3 is shown, wherein the switch contact 3 is fixed to solder joint 17, which here also serves as the connection part 4 of the switch element 2. A mating contact 5 is arranged on the printed circuit board 16 near the end region of the switch contact 3, such that the switch contact 3 moves in the direction of the mating contact 5 when actuated until the contact is closed. Figure 6b An input device 1 according to the invention in a sixth exemplary embodiment is shown in an inactive state.

Claims

1. An input device (1) for safety-related functions of a motor vehicle, comprising a switching element (2) having a switch contact (3) with a first connection portion (4) and a mating contact (5) with a second connection portion (6), wherein when the input device (1) is actuated, the switch contact (3) is capable of contacting the mating contact (5); the input device (1) having a first resistor (9), a first voltage source connection portion (7) and a second voltage source connection portion (8), capable of providing an operating voltage to the input device (1) via the first voltage source connection portion (7) and the second voltage source connection portion (8), wherein the first voltage source connection portion (7) is connected to... The second voltage source connection (8) is connected to one of the first connection portion (4) and the second connection portion (6) of the switching element (2) via the first resistor (9); the input device (1) has a measurement node (10) disposed between the first resistor (9) and the associated first connection portion (4) and the second connection portion (6) of the switching element (2) and connected to the measurement connection portion (11), such that the actuation-related voltage (U1) dependent on the actuation state of the input device (1) can be detected via the measurement connection portion (11). Its features are, The switching element (2) has a third connection (12) connected to the switch contact (3), wherein a second resistor (13) is provided connected to the second connection (6) and the third connection (12) of the switching element (2), the second resistor (13) being connected between the second connection (6) and the third connection (12) such that in the event of a failure of the switch contact (3), the electrical connection between the first connection (4) and the third connection (12) is affected by the failure, and an error voltage (U2) can be detected at the measurement node (10) via the measurement connection (11), and the error voltage can be distinguished from the actuation-related voltage (U1), wherein an evaluation circuit is provided that detects the voltage at the measurement node (10) via the measurement connection (11), and thereby identifies the actuation of the input device (1) and / or the failure of the switch contact (3).

2. The input device (1) according to claim 1, wherein, The switch contact (3) is circular or dome-shaped, and the first connecting part (4) and the third connecting part (12) are disposed in opposite areas of the circular or dome-shaped switch contact (3).

3. The input device (1) according to claim 1, wherein, The switch contact (3) has a flat design, and the first connecting part (4) and the third connecting part (12) are located near the edge of the flat switch contact (3) or in the opposite area.

4. The input device (1) according to any one of claims 1 to 3, wherein, A third resistor (15) is disposed between the first voltage source connection (7) and the first connection (4) and the second connection (6) associated with the switching element (2), such that the first connection (4) or the second connection (6) of the switching element (2) is connected to the first voltage source connection via the third resistor (15).

5. The input device (1) according to any one of claims 1 to 3, wherein, The second voltage source connection (8) is connected to the positive operating voltage, and the first voltage source connection (7) is connected to the reference potential of the input device (1).

6. The input device (1) according to claim 4, wherein, In the unactivated state of the input device (1), an actuation-related voltage (U1) can be detected at the measurement node (10), which is generated by the voltage division ratio between the first resistor (9), the second resistor (13), and the third resistor (15).

7. The input device (1) according to claim 4, wherein, In the actuated state of the input device (1), an actuation-related voltage (U1) can be detected at the measurement node (10). The actuation-related voltage corresponds to the voltage or potential of the first voltage source connection (7), or is generated by the voltage division ratio between the first resistor (9) and the third resistor (15).

8. The input device (1) according to any one of claims 1 to 3, wherein, In the event of a fault in the switch contact (3), an error voltage (U2) corresponding to the voltage or potential of the second voltage source connection (8) can be detected at the measurement node (10).

9. The input device (1) according to any one of claims 1 to 3, wherein, The evaluation circuit includes an analog-to-digital converter, which enables the detected voltage to be converted into a digital value and processed digitally.

10. The input device (1) according to any one of claims 1 to 3, wherein, When the input device (1) is actuated, the contact between the switch contact (3) and the mating contact (5) is current- or conductive.

11. The input device (1) according to any one of claims 1 to 3, wherein, When the input device (1) is actuated, the contact between the switch contact (3) and the mating contact (5) is resistive or capacitive.

12. The input device (1) according to claim 4, wherein, The switching element (2), the first resistor (9), the second resistor (13), and the third resistor (15) are arranged on a printed circuit board (16), and at least the first connection (4) and the third connection (12) are implemented as solder joints (17) on the printed circuit board (16).

13. The input device (1) according to claim 12, wherein, A circular or dome-shaped switch contact (3) is soldered to a solder joint (17) for the first connection (4) and the third connection (12), and the mating contact (5) is disposed between the two solder joints (17) on the printed circuit board (16).

14. The input device (1) according to claim 13, wherein, Additional support points (18) for the circular or dome-shaped switch contacts (3) are provided on the printed circuit board (16) and implemented as solder joints (17).

15. The input device (1) according to claim 1, wherein, The fault of the switch contact (3) is that the switch contact (3) is disconnected (19).

16. The input device (1) according to claim 5, wherein, The first voltage source connection part (7) is grounded.

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