Anti-interference circuit, circuit board and detection system

Abstract

The invention provides an anti-interference circuit. The circuit comprises a low-pass filtering unit. The low-pass filtering unit comprises a first capacitor, a first magnetic bead and a first inductor, the first end of the low-pass filtering unit is coupled to the signal processing module, the second end of the low-pass filtering unit is coupled to the target capacitor, and the third end of the low-pass filtering unit is grounded. Wherein the low-pass filter circuit directly or indirectly receives a signal of a target capacitor or a signal representing the target capacitor, processes the signal of the target capacitor or the signal representing the target capacitor, and transmits the processed signal to the signal processing module. By using the circuit, the stray capacitance can be reduced as much as possible, and ground plane noise entering the detection circuit through the stray capacitance is weakened, so that the influence of removing a shielding layer is weakened, and the signal-to-noise ratio of a signal obtained by the signal processing module is improved. In addition, the invention further provides a circuit board, a detection system and a steering wheel or a seat comprising the detection system.

Description

Technical Field

[0001] The present disclosure relates to the field of intelligent driving, and more particularly, to an anti-interference circuit, a circuit board, a detection system, and a steering wheel or seat including the detection system. Background Art

[0002] With the continuous development of vehicle intelligent technologies, when a driver is driving, especially when using the assisted driving function, the vehicle will also detect the driver's behavior. Once the vehicle determines that the driver has dangerous driving behavior, the system will give a takeover reminder. One of the most common driving supervision mechanisms currently is HOD hand-off detection.

[0003] HOD, that is, Hands off detection. Simply put, during driving, especially when the driver is using the assisted driving function, if the driver's hand is away from the steering wheel for a long time, the system will give a takeover reminder. If the driver does not take over the steering wheel subsequently, the vehicle will exit the assisted driving function. For hand-off detection, there are currently various solutions, and one of the solutions is to detect through capacitance.

[0004] If the vehicle adopts a capacitance detection solution, the steering wheel will be provided with a metal skeleton or other conductive layer structures, and a sensor layer is also provided. Among them, the metal skeleton or other conductive layer structures and the sensor layer form a capacitor, which is the main component of the system parasitic capacitance. When a human hand touches the steering wheel, a capacitor will be formed between the human hand and the steering wheel sensor layer and lead to the ground through the human body model, thereby causing the capacitance value of the detection channel to increase. Correspondingly, the signal detected by the sensor will also change accordingly, and the detection system detects a sufficient amount of signal change to determine that the hand is on the steering wheel.

[0005] Generally, a shielding layer is also provided between the sensor layer and the metal skeleton or other conductive layer structures. This shielding layer can shield interference noise and improve the accuracy of the capacitance detection solution. If the shielding layer of the steering wheel is removed, it will lead to the adverse results of reduced signal-to-noise ratio and inaccurate detection results. For example, in some capacitance-compatible interference environments, noise will also be conducted through the ground plane or radiated through space, thereby causing a certain offset in the detected signal.

[0006] In addition, a heating layer is also provided between the sensor layer and the metal skeleton. The heating layer can be used for steering wheel heating. When the temperature of the heating layer changes, it will cause a certain offset in the detected signal, affecting the detection result and reducing the system reliability. For example, the detection system issues an alarm when the hand is still on the steering wheel, or fails to detect this change in time when the hand has left the steering wheel, thus affecting the user experience. Summary of the Invention

[0007] In view of the problems existing in HOD detection after removing the shielding layer from the steering wheel, the present disclosure proposes an anti-interference circuit. This anti-interference circuit can improve the signal-to-noise ratio of the detection signal, making the HOD detection accurate.

[0008] According to a first aspect of the present disclosure, an anti-interference circuit is proposed, including: a low-pass filtering unit, which includes a first capacitor, a first bead, and a first inductor. The first end of the low-pass filtering unit is coupled to a signal processing module, the second end of the low-pass filtering unit is coupled to a target capacitor, and the third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filtering circuit directly or indirectly receives the signal of the target capacitor or a signal characterizing the target capacitor, processes the signal of the target capacitor or a signal characterizing the target capacitor, and transmits the processed signal to the signal processing module.

[0009] By adopting the above anti-interference circuit, the parasitic capacitance can be minimized as much as possible, and the ground plane noise is weakened from being coupled into the detection circuit through the parasitic capacitance, thereby weakening the influence of removing the shielding layer and improving the signal-to-noise ratio of the signal obtained by the signal processing module. Using the above anti-interference circuit or circuit board, even if a steering wheel without a shielding layer is used, the signal-to-noise ratio requirement of the detection circuit can still be met, and the immunity test in EMC can be passed. At the same time, the steering wheel without a shielding layer can save costs for the manufacturer and make the covering layer of the steering wheel thinner and lighter.

[0010] Optionally, the first bead and the first inductor are combined in series. The first end of the first combination of the first bead and the first inductor is coupled to the signal processing module, the second end of the first combination is coupled to the target capacitor, the first end of the first capacitor is coupled to the signal processing module, and the second end of the first capacitor is coupled to ground.

[0011] Optionally, the low-pass filtering unit further includes a second bead and / or a second inductor. The second bead and / or the second inductor are combined with the first bead in series. The first end of the second combination of the first bead, the first inductor, and the second bead and / or the second inductor is coupled to the signal processing module, and the second end of the second combination is coupled to the target capacitor.

[0012] Optionally, the anti-interference circuit further includes: a voltage suppression unit, which includes a first voltage suppressor. The first end of the first voltage suppressor is connected to the target capacitor, the second end of the first voltage suppressor is coupled to ground, and the first voltage suppressor is used to suppress overvoltage from the target capacitor.

[0013] Optionally, the voltage suppression unit further includes a second voltage suppressor. The first end of the second voltage suppressor is connected to the signal processing module, and the second end of the second voltage suppressor is coupled to ground. The second voltage suppressor is used to prevent overvoltage to the signal processing module.

[0014] Optionally, at least one of the first voltage suppressor and the second voltage suppressor is a transient voltage suppression diode.

[0015] Optionally, the anti-interference circuit further includes a current regulation unit. The first end of the current regulation unit is coupled to the signal processing module, and the second end of the current regulation unit is coupled to the target capacitor. The current regulation unit is used to regulate the current provided by the signal processing module to the target capacitor.

[0016] According to a second aspect of the present disclosure, a circuit board is provided, characterized in that the circuit board has the above anti-interference circuit.

[0017] Optionally, the circuit board includes a ground layer, and the ground layer does not include traces of other signals except the ground signal.

[0018] Optionally, the circuit board includes a signal layer. The signal layer includes traces of the signal of the target capacitor or the signal characterizing the target capacitor and a ground copper foil. There is at least a first distance between the traces of the signal of the target capacitor or the signal characterizing the target capacitor and the ground copper foil, where the first distance is not less than 1 mm.

[0019] According to a third aspect of the present disclosure, a detection system is provided. The detection system includes at least one sensor layer. Among them, the detection system uses the above anti-interference circuit or circuit board to receive and process signals from the sensor layer and transmit the processed signals to the signal processing module of the detection system.

[0020] Optionally, the detection system further includes at least one heating layer. Among them, the sensor layer and the heating layer have an overlapping part in the projection direction.

[0021] Optionally, no shielding layer is provided between the sensor layer and the heating layer.

[0022] Optionally, the sensor layer includes one or more detection regions.

[0023] Optionally, the detection system further includes at least one metal skeleton. Among them, the sensor layer and the metal skeleton have an overlapping part in the projection direction, and no shielding layer is provided between the sensor layer and the metal skeleton.

[0024] According to a fourth aspect of the present disclosure, a detection system is further proposed. The detection system includes a circuit board having a circuit, and the circuit includes: a low-pass filtering unit including a first capacitor, a first bead, and a first inductor. A first end of the low-pass filtering unit is coupled to a signal processing module, a second end of the low-pass filtering unit is coupled to a target capacitor, and a third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filtering circuit directly or indirectly receives a signal of the target capacitor or a signal characterizing the target capacitor, processes the signal of the target capacitor or the signal characterizing the target capacitor, and transmits the processed signal to the signal processing module.

[0025] Optionally, the circuit board includes: a ground layer that does not include traces of other signals except the ground signal.

[0026] Optionally, the circuit board includes: a signal layer that includes traces of a signal of the target capacitor or a signal characterizing the target capacitor and a ground copper foil. At least a first distance is maintained between the trace of the signal of the target capacitor or the signal characterizing the target capacitor and the ground copper foil, where the first distance is not less than 1 mm.

[0027] Optionally, the detection system determines whether a human body part touches a detection area of the detection system based on detection data of the signal processing module.

[0028] According to a fifth aspect of the present disclosure, a steering wheel is proposed. The steering wheel includes the above detection system, and the detection system is used to determine whether a human hand touches the steering wheel.

[0029] Optionally, the steering wheel further includes a sensor layer and a metal skeleton, and no shielding layer is provided between the sensor layer and the metal skeleton.

[0030] According to a sixth aspect of the present disclosure, a seat is proposed. The seat includes the above detection system, and the detection system is used to determine whether a human body part touches the seat. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 A three-dimensional schematic diagram of a vehicle steering wheel is shown.

[0032] Figure 2 A cross-sectional view of the rim of a steering wheel according to an embodiment of the present disclosure is shown.

[0033] Figure 3 A circuit diagram for HOD detection according to an embodiment of the present disclosure is shown.

[0034] Figure 4Shows a circuit diagram for HOD detection according to another embodiment of the present disclosure.

[0035] Figure 5 Shows a schematic diagram of a circuit board according to an embodiment of the present disclosure.

[0036] Figure 6 Shows a partial schematic diagram of a signal layer of a circuit board according to an embodiment of the present disclosure.

[0037] Figure 7 Shows a schematic diagram of a detection area of a sensor layer according to an embodiment of the present disclosure.

[0038] Figure 8 Shows a schematic diagram of a detection area of a sensor layer on the front side of a vehicle steering wheel according to an embodiment of the present disclosure. Detailed Description

[0039] The technical solutions of the present invention will be further specifically described below through embodiments in conjunction with the accompanying drawings. In the specification, the same or similar reference numerals indicate the same or similar components. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the general inventive concept of the present invention and should not be construed as a limitation of the present invention.

[0040] As used herein, the terms "comprising", "including" and similar terms should be understood as open terms, i.e., "including / including but not limited to", indicating that other contents may also be included. The term "based on" means "at least partially based on". The term "an embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment", and so on.

[0041] As used herein, the term "coupled" may refer to a component forming a direct electrical connection with another component, or may refer to a component forming an indirect electrical connection with another component via other devices. In a circuit diagram, a component "connected" to another component should refer to a direct connection rather than a coupling.

[0042] Figure 1 Shows a three-dimensional schematic diagram of a vehicle steering wheel. Figure 2 Shows a cross-sectional view of a wheel rim according to an embodiment of the present disclosure, the cross-section being along Figure 1Obtained by cutting along the AA plane as shown. The steering wheel 10 includes a sandwich structure, which includes a skeleton 101, a foam layer 102, a heating layer 103, a sensor layer 104, and a leather layer 105. The skeleton 101 is made of a metallic material (such as steel, magnesium, or aluminum, etc.), and it defines the rim of the steering wheel 10. The foam layer 102 is disposed between the skeleton 101 and the heating layer 103. In another example, an additional foam layer may also be disposed between the heating layer 103 and the sensor layer 104. The foam layer 102 can be made of polyurethane foam or thermoplastic elastomer foam. The heating layer 103 includes a heater, which defines the heating area of the steering wheel 10. In this embodiment, the sensor layer 104 includes a capacitive sensor, and the position covered by the sensor layer 104 defines a detection area for HOD detection. The leather layer 105 is disposed on the outside of the rim as the outer surface of the steering wheel 10.

[0043] As described above, the hands-off detection (HOD) system of the steering wheel needs to monitor whether the user is holding the steering wheel and feed the monitoring result back to the whole vehicle, such as ADAS, in real time. Subsequently, ADAS decides whether to activate the assisted autonomous driving function according to the user's control of the steering wheel at this time.

[0044] Figure 3 Shows a circuit diagram for HOD detection according to an embodiment of the present disclosure. The present disclosure briefly describes the circuit principle of HOD detection based on this circuit diagram. Figure 3The circuit 20 shown includes an SBC (power management chip) module 201, an MCU (microcontroller) module 202, a signal processing module 203, an anti-interference circuit 204, and a target capacitor 205. One end of the SBC module 201 is coupled to the main power supply, and the other end is coupled to the MCU module 202 and the signal processing module 203. The SBC module 201 controls and manages the voltage provided by the main power supply under the control signal of the communication link, and then provides the required voltage and current to the MCU module 202, the signal processing module 203, etc. One end of the signal processing module 203 is coupled to the MCU module 202, and the other end is coupled to one end of the anti-interference circuit 204. The other end of the anti-interference circuit 204 is coupled to the target capacitor 205. The signal processing module 203 obtains the detection signal related to the target capacitor 205 via the anti-interference circuit 204. When the driver's hand does not touch the steering wheel, the target capacitor 205 mainly consists of a sensor layer and a metal skeleton, and the initial target capacitance value is C0. When the driver's hand touches the steering wheel, the target capacitor 205 also includes the human conductor introduced by the hand. This causes the target capacitor 205 to increase the capacitance by ΔC on the original basis. This capacitance increment includes not only the capacitance between the hand and the sensor layer, but also the capacitance formed between the human body and the grounding environment of the whole vehicle. Therefore, the detection signal related to the target capacitor 205 obtained by the signal processing module 203 is different when the hand touches the steering wheel or does not touch the steering wheel. In one example, the signal processing module 203 sends a sine wave to the target capacitor 205, and the signal processing module 203 receives the mirror current fed back by the target capacitor 205. The signal processing module 203 converts this current signal into a voltage signal, and uses a demodulator for demodulation, separation and other processing, and finally captures the capacitance change of the target capacitor 205. Based on the change of the target capacitor 205, the signal processing module 203 can detect whether the hand touches the steering wheel, and send the detection result to the MCU module 202, so that the MCU module 202 can perform subsequent control on the vehicle. In this embodiment, the MCU module 202 and the signal processing module 203 are independent components respectively. In other examples, the MCU module 202 and the signal processing module 203 can be integrated into one body.

[0045] In the existing HOD detection, such as Figure 2A shielding layer is also provided between the shown metal skeleton 101 and the sensor layer 104. The shielding layer is made of a material (such as metal) with an electronic shielding effect. The setting of the shielding layer can prevent the ground plane noise from the metal skeleton from being coupled into the sensor layer, thereby avoiding measurement errors and drifts caused during the detection process. If a shielding layer is added to the steering wheel, the target capacitance will also include the shielding layer, which makes the initial target capacitance value C0 smaller. In this way, when the same capacitance increment ΔC is introduced after a human hand touches the steering wheel, since the capacitance increment is more obvious relative to the initial target capacitance value, the capacitance change of the target capacitance will be easier to capture, which is more conducive to the accuracy of the HOD detection result. On the contrary, if the shielding layer in the steering wheel is removed, that is, a steering wheel as shown in Figure 2 is used, not only will the ground plane noise enter the sensor layer and the detection channel, but also the parasitic capacitance between the sensor layer and the metal skeleton will become larger. Since the capacitance increment is somewhat insignificant relative to the initial target capacitance value, the capacitance change of the target capacitance will become difficult to detect, so it is very difficult to determine whether a human hand has touched the steering wheel. However, removing the shielding layer in the steering wheel will inevitably bring some benefits, such as a simpler structure of the steering wheel, a thinner wrapping layer of the steering wheel, and a reduced manufacturing cost of the steering wheel.

[0046] Based on this, the present disclosure proposes an anti-interference circuit for a steering wheel without a shielding layer. This circuit can reduce or eliminate the interference signals from the target capacitance, improve the signal-to-noise ratio, and make the HOD detection more accurate. Referring to Figure 3 , the anti-interference circuit 204 includes a low-pass filtering unit 206, which includes a first capacitor C1, a first magnetic bead FB1, and a first inductor L1. The first end of the low-pass filtering unit 206 is coupled to the signal processing module 203, the second end of the low-pass filtering unit 206 is coupled to the target capacitance 205, and the third end of the low-pass filtering unit 206 is coupled to the ground. Among them, the low-pass filtering circuit 206 directly or indirectly receives the signal of the target capacitance 205 or the signal representing the target capacitance 205, processes the signal of the target capacitance 205 or the signal representing the target capacitance 205, and transmits the processed signal to the signal processing module 203. The low-pass filtering unit 206 can allow the low-frequency signals and DC signals provided by the signal processing module 203 to pass through the target capacitance 205, and at the same time filter out the high-frequency noise from the target capacitance 205.

[0047] In this embodiment, the first magnetic bead FB1 and the first inductor L1 are combined in series. The first end of the first combination of the first magnetic bead FB1 and the first inductor L1 is coupled to the signal processing module 203, and the second end of the first combination is coupled to the target capacitor 205. The first end of the first capacitor C1 is coupled to the signal processing module 203, and the second end of the first capacitor C1 is coupled to ground. The positions of the first magnetic bead FB1 and the first inductor L1 can be interchanged, as Figure 4 shown in the circuit diagram. The magnetic bead can be used to absorb the energy of high-frequency noise. It can be understood that the anti-interference circuit 204 and the target capacitor 205 are in series. If the capacitance value introduced by the anti-interference circuit itself is too large, it will inevitably affect the capture of the capacitance increment ΔC. Therefore, optionally, the first capacitor C1 can be less than or equal to 100 pF to ensure the signal-to-noise ratio of the signal received by the signal processing module 203. Optionally, the first capacitor C1 can also be greater than or equal to 68 pF. If the first capacitor C1 is too small, considering the cut-off frequency of the low-pass filtering unit 206, a first magnetic bead FB1 with a higher inductance value is required, which will increase the manufacturing cost of the circuit. Optionally, the impedance of the first magnetic bead FB1 is greater than 1 kΩ at 100 MHz. Preferably, the impedance of the first magnetic bead FB1 is 1.8 kΩ at 100 MHz.

[0048] In other embodiments, the low-pass filtering unit 206 further includes a second magnetic bead and / or a second inductor. The second magnetic bead and / or the second inductor are combined with the first magnetic bead FB1 in series. The first end of the second combination of the first magnetic bead FB1, the first inductor L1, and the second magnetic bead and / or the second inductor is coupled to the signal processing module 203, and the second end of the second combination is coupled to the target capacitor 205. In the second combination, the positions of the first magnetic bead FB1, the first inductor L1, and the second magnetic bead and / or the second inductor can be interchanged.

[0049] In this embodiment, continuing to refer to Figure 3 , the anti-interference circuit 204 further includes a voltage suppression unit, which includes a first transient voltage suppressor TVS1. The first end of the first transient voltage suppressor TVS1 is connected to the target capacitor 205, and the second end of the first transient voltage suppressor TVS1 is coupled to ground. The first transient voltage suppressor TVS1 is used to suppress the overvoltage from the target capacitor 205. For example, the first transient voltage suppressor TVS1 can clamp instantaneous pulse interferences such as ESD from the target capacitor 205 to avoid overvoltage breakdown or burning of devices such as the anti-interference circuit 204 and the signal processing module 203.

[0050] Further, the voltage suppression unit further includes a second voltage suppressor TVS2. The first end of the second voltage suppressor TVS2 is connected to the signal processing module 203, and the second end of the second voltage suppressor TVS2 is coupled to ground. The second voltage suppressor TVS2 is used to prevent overvoltage to the signal processing module 203 to avoid overvoltage breakdown or burning of the components in the signal processing module 203. In another example, the signal processing module 203 has a built-in voltage suppressor, and in this case, the second voltage suppressor TVS2 is no longer needed to provide protection.

[0051] Optionally, at least one of the first voltage suppressor TVS1 and the second voltage suppressor TVS2 is a transient voltage suppressor. As described above, if the capacitance value introduced by the anti-interference circuit 204 itself is too large, it will inevitably affect the capture of the capacitance increment ΔC, and further affect the signal-to-noise ratio. Therefore, optionally, the junction capacitance of the transient voltage suppressor is less than or equal to 1 pF. In other examples, the first or second voltage suppressor can also use other types of voltage suppressors, such as discharge gaps, thyratrons, varistors, or avalanche diodes, etc.

[0052] In this embodiment, the anti-interference circuit 204 further includes a current regulation unit 207. The first end of the current regulation unit 207 is coupled to the signal processing module 203, and the second end of the current regulation unit 207 is coupled to the target capacitor 205. The current regulation unit 207 is used to regulate the current provided by the signal processing module 203 to the target capacitor 205. The current regulation unit 207 in this embodiment is a resistor R1. Optionally, the resistor R1 is less than 2.2 kΩ. If the resistance is too large, the current provided by the signal processing module 203 to the target capacitor 205 will be too small, which will further affect the signal-to-noise ratio of the signal received by the signal processing module 203. The current regulation unit 207 can limit the excessive DC current and suppress the AC noise at the same time. In other examples, the current regulation unit can also be other types of current regulation devices or circuits.

[0053] In addition, the present disclosure also proposes a circuit board having the above anti-interference circuit. Figure 5 A schematic diagram of a circuit board according to an embodiment of the present disclosure is shown. The circuit board 30 includes a first signal layer 301 arranged on the first layer, a power supply layer 302 arranged on the second layer, a ground layer 303 arranged on the third layer, and a second signal layer 304 arranged on the fourth layer. Among them, the ground layer 303 does not include the traces of other signals except the ground signal. The ground layer 303 is a complete ground plane. The vias of other signals may pass through the ground layer 303, but the traces of other signals are not arranged on the ground layer 303. By setting this ground layer 303, the noise passing through the anti-interference circuit can be connected to the ground via a low impedance, which is easy for the noise to return, and reduces the impact of the noise on the measurement.

[0054] Figure 6 FIG. 2 shows a partial schematic diagram of a signal layer of a circuit board according to an embodiment of the present disclosure. The signal layer of the circuit board includes a trace 41 for the signal of the target capacitor or a signal characterizing the target capacitor, and a ground plane 42. There is at least a first distance d maintained between the trace 41 for the signal of the target capacitor or a signal characterizing the target capacitor and the ground plane 42, where the first distance d is not less than 1 mm. If there are multiple signal traces with a relatively close distance on the signal layer, it is the outermost signal trace that is spaced from the ground plane by at least the first distance d. Maintaining at least the first distance d between the signal trace 41 and the ground plane 42 reduces the parasitic capacitance between the signal line and the ground signal. As described above, parasitic capacitance introduced into the circuit should be minimized as much as possible to ensure the signal-to-noise ratio.

[0055] By adopting the above anti-interference circuit or circuit board, the parasitic capacitance can be minimized as much as possible, and the ground plane noise is weakened from being coupled into the detection circuit through the parasitic capacitance, thereby weakening the influence of removing the shielding layer and improving the signal-to-noise ratio of the signal acquired by the signal processing module. Using the above anti-interference circuit or circuit board, even if a steering wheel without a shielding layer is adopted, the requirements for the signal-to-noise ratio of the detection circuit can still be met, and it can pass the immunity tests in EMC, such as tests like R1 (radiated immunity), BCI (big current injection immunity), PTI (portable transmitter radio frequency immunity), etc. At the same time, the steering wheel without a shielding layer can save costs for the manufacturer and make the covering layer of the steering wheel thinner and lighter. Of course, for a steering wheel with a shielding layer, the above anti-interference circuit or circuit board can also be used to implement HOD detection, which is beneficial to improving the signal-to-noise ratio of the detection signal and the accuracy of the detection.

[0056] In addition, the present disclosure also proposes a detection system, which includes at least one sensor layer (such as Figure 2 the sensor layer 104). The detection system uses the above anti-interference circuit or circuit board to receive and process signals from the sensor layer and transmit the processed signals to the signal processing module of the detection system (such as Figure 3 or Figure 4 the signal processing module 203).

[0057] In one embodiment, the detection system further includes at least one heating layer (such as Figure 2 the heating layer 103), where the sensor layer and the heating layer have an overlapping part in the projection direction. As described above, when the temperature of the heating layer changes, it will cause a certain shift in the detected signal, affecting the accuracy of the HOD detection result. However, since the detection system adopts the anti-interference circuit or circuit board proposed by the present disclosure, the signal-to-noise ratio can be greatly improved, ensuring the accuracy of the HOD detection result.

[0058] In one embodiment, there is no shielding layer between the sensor layer and the heating layer. As described above, even if there is no shielding layer in the steering wheel, since the detection system adopts the anti-interference circuit or circuit board proposed in the present disclosure, the accuracy of the HOD detection result can still be ensured.

[0059] In one embodiment, the sensor layer includes one or more detection regions. Figure 7 The schematic diagram of the detection region of the sensor layer according to an embodiment of the present disclosure is shown. The sensor layer may include a monolithic metal wire mesh, wherein the area covered by the metal wire mesh is virtually divided into two detection regions, namely the detection region 50 located on the front side of the steering wheel and the detection region 60 located on the rear side of the steering wheel. Based on the internal circuit of the detection system, it can be detected whether a human hand touches the steering wheel. At the same time, pressure-sensitive materials are also provided at the positions where the detection region 50 and the detection region 60 are located. When a human hand touches any one of the detection region 50 or the detection region 60, the pressure-sensitive material can determine the position of the human hand, and further determine which detection region the human hand touches.

[0060] In another example, continue to refer to Figure 7 , the sensor layer of the steering wheel may include multiple pieces of metal wire mesh, which are structurally separated from each other, including the metal wire mesh located on the front side of the steering wheel and the metal wire mesh located on the rear side of the steering wheel, which respectively correspond to the detection region 50 and the detection region 60. Each detection region belongs to a separate HOD detection circuit. The detection region 50 belongs to the HOD detection circuit 50', and the detection region 60 belongs to the HOD detection circuit 60'. When a human hand touches any one of the detection region 50 or the detection region 60, according to the result obtained from the HOD detection circuit where the detection region is located, it can be determined which detection region the human hand touches.

[0061] The sensor layer provided with multiple detection regions can more finely distinguish the gestures of the human hand holding the steering wheel. Figure 8 The schematic diagram of the detection region on the front side of the steering wheel of the sensor layer according to an embodiment of the present disclosure is shown. Combining Figure 7 and Figure 8 , in other examples, the sensor layer includes the detection region 51 located on the left front side of the steering wheel, the detection region 52 located on the right front side of the steering wheel, and the detection region 60 located on the rear side of the steering wheel. Based on the above similar principle, it can be determined which region among the detection region 51, the detection region 52, or the detection region 60 the human hand touches.

[0062] In one embodiment, the detection system further includes at least one metal skeleton (such as Figure 2 the metal skeleton 101). Among them, the sensor layer (such as Figure 2The sensor layer 104) and the metal skeleton have an overlapping part in the projection direction, and no shielding layer is provided between the sensor layer and the metal skeleton.

[0063] In addition, the present disclosure also proposes a detection system. The detection system includes a circuit board, and the circuit board has a circuit. The circuit includes a low-pass filtering unit, which includes a first capacitor, a first bead, and a first inductor. The first end of the low-pass filtering unit is coupled to the signal processing module, the second end of the low-pass filtering unit is coupled to the target capacitor, and the third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filtering circuit directly or indirectly receives the signal of the target capacitor or the signal characterizing the target capacitor, processes the signal of the target capacitor or the signal characterizing the target capacitor, and transmits the processed signal to the signal processing module.

[0064] In one embodiment, the circuit board includes a ground layer. The ground layer does not include traces of other signals except the ground signal.

[0065] In one embodiment, the circuit board includes a signal layer. The signal layer includes traces of the signal of the target capacitor or the signal characterizing the target capacitor and a ground copper foil, and at least a first distance is maintained between the traces of the signal of the target capacitor or the signal characterizing the target capacitor and the ground copper foil, wherein the first distance is not less than 1 mm.

[0066] In one embodiment, the detection system determines whether a human body part touches the detection area of the detection system based on the detection data of the signal processing module.

[0067] In addition, the present disclosure also proposes a steering wheel, which includes the above detection system, and the detection system is used to determine whether a human hand touches the steering wheel.

[0068] In one embodiment, the steering wheel further includes a sensor layer (such as Figure 2 the sensor layer 104) and a metal skeleton (such as Figure 2 the metal skeleton 101), wherein no shielding layer is provided between the sensor layer and the metal skeleton.

[0069] The present disclosure also proposes a seat, which includes the above detection system, and the detection system is used to determine whether a human body part touches the seat. The above-mentioned sensor layer and metal layer are arranged at some positions of the seat (for example, the seat surface or the backrest). The metal layer may be a metal skeleton or other metal structures. Based on the detection circuit provided by the detection system, when a human body part (such as the buttocks or the back) touches the seat, the detection circuit can capture the corresponding capacitance increment, and then send the detection result to the seat to realize the seat occupancy detection function.

[0070] It should be noted that the present invention (such as the inventive concept, etc.) has been described in the specification of this patent document and / or illustrated in the figures according to exemplary embodiments; the embodiments of the present invention are presented by way of example only and are not intended to limit the scope of the present invention. The structure and / or arrangement of the elements of the inventive concept embodied in the present invention as described in the specification and / or illustrated in the figures are merely illustrative. Although the exemplary embodiments of the present invention have been described in detail in this patent document, it is readily understood by those of ordinary skill in the art that equivalents, modifications, variations, etc. of the subject matter of the exemplary embodiments and alternative embodiments are possible and are considered to be within the scope of the present invention; all such subject matter (such as modifications, variations, embodiments, combinations, equivalents, etc.) is intended to be included within the scope of the present invention. It should also be noted that various / other modifications, variations, substitutions, equivalents, changes, omissions, etc. can be made in the configuration and / or arrangement of the exemplary embodiments (such as in terms of concept, design, structure, device, form, assembly, construction, means, function, system, process / method, steps, order of process / method steps, operation, operating conditions, performance, materials, composition, combination, etc.) without departing from the scope of the present invention; all such subject matter (such as modifications, variations, embodiments, combinations, equivalents, etc.) is intended to be included within the scope of the present invention. The scope of the present invention is not intended to be limited to the subject matter described in the specification and / or figures of this patent document (such as details, structure, function, materials, behavior, steps, order, system, results, etc.). Considering that the claims of this patent document will be properly construed to cover the full scope of the subject matter of the present invention (such as including any and all such modifications, variations, embodiments, combinations, equivalents, etc.); it should be understood that the terms used in this patent document are for the purpose of describing the subject matter of the exemplary embodiments and not as a limitation on the scope of the present invention.

[0071] It should also be noted that, according to the exemplary embodiments, the present invention may include conventional technologies (such as technologies implemented and / or integrated in the exemplary embodiments, modifications, variations, combinations, equivalents), or may include any other applicable technologies (present and / or future) with the ability to perform the functions and processes / operations described in the specification and / or illustrated in the figures. All such technologies (such as technologies implemented in the form of embodiments, modifications, variations, combinations, equivalents, etc.) are considered to be within the scope of the present invention in this patent document.

Claims

1. An anti-interference circuit, comprising: A low-pass filtering unit, which includes a first capacitor, a first bead, and a first inductor. The first end of the low-pass filtering unit is coupled to a signal processing module, the second end of the low-pass filtering unit is coupled to a target capacitor, and the third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filtering circuit directly or indirectly receives the signal of the target capacitor or a signal characterizing the target capacitor, processes the signal of the target capacitor or a signal characterizing the target capacitor, and transmits the processed signal to the signal processing module.

2. The circuit according to claim 1, wherein, The first bead and the first inductor are combined in series. The first end of the first combination of the first bead and the first inductor is coupled to the signal processing module, the second end of the first combination is coupled to the target capacitor, the first end of the first capacitor is coupled to the signal processing module, and the second end of the first capacitor is coupled to ground.

3. The circuit according to claim 2, wherein, The low-pass filtering unit further includes a second bead and / or a second inductor. The second bead and / or the second inductor are combined with the first bead in series. The first end of the second combination of the first bead, the first inductor, and the second bead and / or the second inductor is coupled to the signal processing module, and the second end of the second combination is coupled to the target capacitor.

4. The circuit according to claim 1, further comprising: A voltage suppression unit, which includes a first voltage suppressor. The first end of the first voltage suppressor is connected to the target capacitor, the second end of the first voltage suppressor is coupled to ground, and the first voltage suppressor is used to suppress overvoltage from the target capacitor.

5. The circuit according to claim 4, wherein, The voltage suppression unit further includes a second voltage suppressor. The first end of the second voltage suppressor is connected to the signal processing module, the second end of the second voltage suppressor is coupled to ground, and the second voltage suppressor is used to prevent overvoltage to the signal processing module.

6. The circuit according to claim 5, wherein, At least one of the first voltage suppressor and the second voltage suppressor is a transient voltage suppression diode.

7. The circuit according to claim 1, further comprising: A current regulation unit. The first end of the current regulation unit is coupled to the signal processing module, the second end of the current regulation unit is coupled to the target capacitor, and the current regulation unit is used to regulate the current provided by the signal processing module to the target capacitor.

8. A circuit board, characterized in that, The circuit board has the anti-interference circuit according to any one of claims 1-7.

9. The circuit board according to claim 8, comprising: A ground layer, which does not include traces of other signals except the ground signal.

10. The circuit board according to claim 8, comprising: A signal layer, which includes traces of the signal of the target capacitor or a signal characterizing the target capacitor and ground copper clads. There is at least a first distance between the traces of the signal of the target capacitor or a signal characterizing the target capacitor and the ground copper clads, wherein the first distance is not less than 1 mm.

11. A detection system, the detection system comprising at least one sensor layer, wherein, The detection system uses the anti-interference circuit described in any one of claims 1-7 or the circuit board described in any one of claims 8-10 to receive and process signals from the sensor layer and transfer the processed signals to the signal processing module of the detection system.

12. The detection system according to claim 11 further includes at least one heating layer, wherein, The sensor layer and the heating layer have an overlapping portion in the projection direction.

13. The detection system according to claim 12, wherein, No shielding layer is provided between the sensor layer and the heating layer.

14. The detection system according to claim 11, wherein, The sensor layer includes one or more detection regions.

15. The detection system according to claim 11 further includes at least one metal skeleton, wherein, The sensor layer and the metal skeleton have an overlapping portion in the projection direction, and no shielding layer is provided between the sensor layer and the metal skeleton.

16. A detection system, wherein, The detection system includes a circuit board having a circuit, and the circuit includes: A low-pass filtering unit, which includes a first capacitor, a first bead, and a first inductor. The first end of the low-pass filtering unit is coupled to the signal processing module, the second end of the low-pass filtering unit is coupled to a target capacitor, and the third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filtering circuit directly or indirectly receives the signal of the target capacitor or a signal characterizing the target capacitor, processes the signal of the target capacitor or a signal characterizing the target capacitor, and transfers the processed signal to the signal processing module.

17. The detection system according to claim 16, wherein, The circuit board includes: A ground layer that does not include traces of other signals except the ground signal.

18. The detection system according to claim 16, wherein, The circuit board includes: A signal layer that includes traces of the signal of the target capacitor or a signal characterizing the target capacitor and ground copper cladding. At least a first distance is maintained between the trace of the signal of the target capacitor or a signal characterizing the target capacitor and the ground copper cladding, wherein the first distance is not less than 1 mm.

19. The detection system according to any one of claims 16 - 18, wherein, The detection system determines whether a human body part touches the detection region of the detection system based on the detection data of the signal processing module.

20. A steering wheel, wherein, The steering wheel includes the detection system described in claim 19, and the detection system is used to determine whether a human hand touches the steering wheel.

21. The steering wheel according to claim 20, wherein the steering wheel further comprises a sensor layer and a metal skeleton, where No shielding layer is provided between the sensor layer and the metal skeleton.

22. A seat, wherein, The seat includes the detection system described in claim 19, and the detection system is used to determine whether a human body part touches the seat.

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