Anti-interference circuit, circuit board and detection system

Abstract

Provided in the present disclosure is an anti-interference circuit, the circuit comprising a low-pass filter unit. The low-pass filter unit comprises a first capacitor, a first ferrite bead and a first inductor, a first end thereof is coupled to a signal processing module, a second end thereof is coupled to a target capacitor, and a third end thereof is coupled to the ground. A low-pass filter circuit directly or indirectly receives a signal of the target capacitor or a signal representing the target capacitor; the low-pass filter circuit processes the signal of the target capacitor or the signal representing the target capacitor, and transmits the processed signal to the signal processing module. Using the circuit can reduce parasitic capacitance as much as possible, and weaken ground plane noises coupled into a detection circuit via the parasitic capacitance, thereby weakening the impact of removing a shielding layer, and improving a signal-to-noise ratio of the signal acquired by the signal processing module. In addition, further provided in the present disclosure are a circuit board, a detection system and a steering wheel or seat comprising the detection system.

Description

Anti-interference circuits, circuit boards, and detection systems Technical Field

[0001] The present disclosure relates to the field of intelligent driving, and in particular, 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 intelligent vehicle technology, vehicles will monitor driver behavior while driving, especially when using assisted driving features. If the vehicle determines that the driver is engaging in dangerous driving behavior, the system will issue a takeover reminder. One of the most common driving monitoring mechanisms currently is hands-off detection.

[0003] HOD stands for Hands-off Detection. Simply put, if the driver's hands are off the steering wheel for an extended period while driving, especially when using assisted driving features, the system will prompt them to take over. If the driver subsequently fails to take back control, the assisted driving feature will be discontinued. There are currently several solutions for hands-off detection, one of which is capacitive detection.

[0004] If a vehicle uses a capacitive detection solution, the steering wheel will have a metal frame or other conductive layer structure and a sensor layer. The metal frame or other conductive layer structure and the sensor layer form a capacitor, which is the main component of the system's parasitic capacitance. When a person touches the steering wheel, a capacitor is formed between the hand and the steering wheel sensor layer, and then connected to the ground through the human body model, causing the capacitance of the detection channel to increase. Accordingly, the signal detected by the sensor will also change accordingly. The detection system detects a sufficient signal change to determine that the hand is on the steering wheel.

[0005] Typically, a shielding layer is placed between the sensor layer and the metal frame or other conductive structure to block interference noise and improve the accuracy of the capacitance detection scheme. Removing the shielding layer from the steering wheel will result in a reduced signal-to-noise ratio and inaccurate detection results. For example, in certain capacitance-compatible interference environments, noise can be conducted through the ground plane or radiated through space, causing a certain offset in the detected signal.

[0006] In addition, a heating layer is placed between the sensor layer and the metal frame. This layer heats the steering wheel. Temperature changes in the heating layer can cause a certain offset in the detected signal, affecting detection results and reducing system reliability. For example, the detection system could sound an alarm while the hand is still on the steering wheel, or fail to detect the change in time after the hand has left the steering wheel, thus affecting user experience. Summary of the Invention

[0007] To address the problems encountered in HOD detection after removing the shielding layer of the steering wheel, the present disclosure proposes an anti-interference circuit that can improve the signal-to-noise ratio of the detection signal, thereby making HOD detection more accurate.

[0008] According to a first aspect of the present disclosure, an anti-interference circuit is provided, comprising: a low-pass filter unit comprising a first capacitor, a first ferrite bead, and a first inductor, wherein a first end of the low-pass filter unit is coupled to a signal processing module, a second end of the low-pass filter unit is coupled to a target capacitor, and a third end of the low-pass filter unit is coupled to ground. The low-pass filter circuit directly or indirectly receives a signal from the target capacitor or a signal representative of the target capacitor, processes the signal from the target capacitor or the signal representative of the target capacitor, and transmits the processed signal to the signal processing module.

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

[0010] Optionally, the first magnetic bead and the first inductor are combined in series, the first end of the first combination of the first magnetic 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 also includes a second magnetic bead and / or a second inductor, and the second magnetic bead and / or the second inductor are combined in series with the first magnetic bead, and the first end of the first magnetic bead, the first inductor, and the second combination of the second magnetic 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 also includes: a voltage suppression unit, which includes a first voltage suppressor, a first end of the first voltage suppressor is connected to the target capacitor, a 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, a first end of the second voltage suppressor is connected to the signal processing module, a second end of the second voltage suppressor is coupled to ground, and the second voltage suppressor is used to prevent overvoltage on the signal processing module.

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

[0015] Optionally, the anti-interference circuit also includes: a current regulating unit, a first end of the current regulating unit is coupled to the signal processing module, a second end of the current regulating unit is coupled to the target capacitor, and the current regulating 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-mentioned anti-interference circuit.

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

[0018] Optionally, the circuit board includes: a signal layer, the signal layer includes a signal of the target capacitor or a trace representing the signal of the target capacitor and a ground copper foil, and the signal of the target capacitor or the trace representing the signal of the target capacitor maintains at least a first distance from the ground copper foil, wherein the first distance is not less than 1 mm.

[0019] According to the third aspect of the present disclosure, a detection system is proposed, which includes at least one sensor layer, wherein the detection system uses the above-mentioned 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, wherein the sensor layer and the heating layer have an overlapping portion in a projection direction.

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

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

[0023] Optionally, the detection system further comprises at least one metal skeleton, wherein the sensor layer and the metal skeleton have an overlapping portion in a 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, comprising a circuit board having a circuit, wherein the circuit comprises: a low-pass filter unit comprising a first capacitor, a first magnetic bead, and a first inductor, wherein a first end of the low-pass filter unit is coupled to a signal processing module, a second end of the low-pass filter unit is coupled to a target capacitor, and a third end of the low-pass filter unit is coupled to ground. The low-pass filter circuit directly or indirectly receives a signal from the target capacitor or a signal representing the target capacitor, processes the signal from the target capacitor or the signal representing the target capacitor, and transmits the processed signal to the signal processing module.

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

[0026] Optionally, the circuit board includes: a signal layer, the signal layer includes a signal of the target capacitor or a trace representing the signal of the target capacitor and a ground copper foil, and the signal of the target capacitor or the trace representing the signal of the target capacitor maintains at least a first distance from the ground copper foil, wherein the first distance is not less than 1 mm.

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

[0028] According to a fifth aspect of the present disclosure, a steering wheel is proposed, wherein the steering wheel includes the above-mentioned 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 frame, wherein no shielding layer is provided between the sensor layer and the metal frame.

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

[0031] FIG1 shows a perspective schematic diagram of a vehicle steering wheel.

[0032] FIG2 illustrates a cross-sectional view of a rim of a steering wheel according to one embodiment of the present disclosure.

[0033] FIG3 shows a circuit diagram for HOD detection according to one embodiment of the present disclosure.

[0034] FIG4 shows a circuit diagram for HOD detection according to another embodiment of the present disclosure.

[0035] FIG5 shows a schematic diagram of a circuit board according to an embodiment of the present disclosure.

[0036] FIG6 shows a partial schematic diagram of a signal layer of a circuit board according to an embodiment of the present disclosure.

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

[0038] FIG8 is a schematic diagram showing a detection area of ​​a sensor layer in front of a steering wheel according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described in detail below through examples and 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 overall inventive concept of the present invention and should not be construed as limiting the present invention.

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

[0041] As used herein, the term "coupled" can refer to a direct electrical connection between one component and another, or an indirect electrical connection between one component and another via another component. In a circuit diagram, when a component is "connected" to another component, it should be considered a direct connection, not a coupling.

[0042] Figure 1 shows a perspective schematic diagram of a vehicle steering wheel. Figure 2 shows a cross-sectional view of a wheel rim according to one embodiment of the present disclosure, taken along plane AA shown in Figure 1. The steering wheel 10 comprises a sandwich structure comprising a frame 101, a foam layer 102, a heating layer 103, a sensor layer 104, and a leather layer 105. The frame 101 is made of a metal material (e.g., steel, magnesium, or aluminum) and defines the rim of the steering wheel 10. The foam layer 102 is disposed between the frame 101 and the heating layer 103. In other examples, an additional foam layer may be disposed between the heating layer 103 and the sensor layer 104. The foam layer 102 may be made of polyurethane foam or thermoplastic elastomer foam. The heating layer 103 includes a heater that defines the heating area of ​​the steering wheel 10. In this embodiment, the sensor layer 104 comprises a capacitive sensor, and the area covered by the sensor layer 104 defines a detection area for HOD detection. The leather layer 105 is arranged on the outside of the rim as the outer surface of the steering wheel 10 .

[0043] As mentioned earlier, the Hands-Off Detection (HOD) system monitors whether the user is holding the steering wheel and provides real-time feedback to the vehicle, such as the Advanced Driver Assistance System (ADAS). The ADAS then determines whether to enable assisted autonomous driving based on the user's current control of the steering wheel.

[0044] Figure 3 shows a circuit diagram for HOD detection according to an embodiment of the present disclosure. Based on this circuit diagram, this disclosure briefly explains the circuit principles of HOD detection. The circuit 20 shown in Figure 3 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. Under control signals from the communication link, the SBC module 201 controls and manages the voltage provided by the main power supply, thereby providing the MCU module 202 and the signal processing module 203 with required voltages (e.g., VCC, Volt Current Condenser) and currents. 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 a 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 is mainly composed of the sensor layer and the 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 body conductor introduced by the hand. This causes the target capacitor 205 to increase the capacitance ΔC on the original basis. The capacitance increment not only includes the capacitance between the hand and the sensor layer, but also includes the capacitance formed between the human body and the ground environment of the vehicle. Therefore, when the hand touches the steering wheel or does not touch the steering wheel, the detection signal of the target capacitor 205 obtained by the signal processing module 203 is different. 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 the current signal into a voltage signal, and uses a demodulator to perform demodulation, separation and other processing, and finally captures the capacitance change of the target capacitor 205. Based on the change in target capacitance 205, signal processing module 203 can detect whether a human hand is touching the steering wheel and send the detection result to MCU module 202 so that MCU module 202 can subsequently control the vehicle. In this embodiment, MCU module 202 and signal processing module 203 are independent components. In other examples, MCU module 202 and signal processing module 203 can be integrated into one.

[0045] In existing HOD detection, a shielding layer is provided between the metal frame 101 and the sensor layer 104, as shown in FIG2 . This shielding layer is made of a material with an electronic shielding effect (e.g., metal). The shielding layer prevents ground plane noise from the metal frame from entering the sensor layer, thereby preventing measurement errors and drift 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 reduces the initial target capacitance value C0. In this way, when the same capacitance increment ΔC is introduced after a human hand touches the steering wheel, the capacitance change of the target capacitance will be easier to capture because the capacitance increment is more obvious relative to the initial target capacitance value, which is more conducive to the accuracy of the HOD detection results. Conversely, if the shielding layer is removed from the steering wheel, that is, if the steering wheel shown in FIG2 is used, not only will ground plane noise enter the sensor layer and detection channel, but the parasitic capacitance between the sensor layer and the metal frame will also increase. Because 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, making it difficult to determine whether a human hand has touched the steering wheel. However, removing the shielding layer inside the steering wheel will inevitably bring some benefits, such as a simpler steering wheel structure, a lighter and thinner steering wheel covering, and reduced steering wheel manufacturing costs.

[0046] Based on this, the present disclosure proposes an anti-interference circuit for a steering wheel with a shielding layer removed. The circuit can reduce or eliminate interference signals from the target capacitor, improve the signal-to-noise ratio, and make HOD detection more accurate. Referring to Figure 3, the anti-interference circuit 204 includes a low-pass filter 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 filter unit 206 is coupled to the signal processing module 203, the second end of the low-pass filter unit 206 is coupled to the target capacitor 205, and the third end of the low-pass filter unit 206 is coupled to the ground. The low-pass filter circuit 206 directly or indirectly receives a signal from the target capacitor 205 or a signal representing the target capacitor 205, processes the signal from the target capacitor 205 or a signal representing the target capacitor 205, and transmits the processed signal to the signal processing module 203. The low-pass filter unit 206 can allow the low-frequency signal and DC signal provided by the signal processing module 203 to the target capacitor 205 to pass through, while filtering out high-frequency noise from the target capacitor 205.

[0047] In this embodiment, a first magnetic bead FB1 and a 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 are interchangeable, as shown in the circuit diagram of Figure 4. Magnetic beads can be used to absorb energy from high-frequency noise. It is understood that if the anti-interference circuit 204 is connected in series with the target capacitor 205 and the capacitance introduced by the anti-interference circuit itself is too large, it will inevitably affect the capture of the capacitance increment ΔC. Therefore, the first capacitor C1 can optionally 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. Alternatively, the first capacitor C1 can be greater than or equal to 68 pF. If the first capacitor C1 is too small, considering the cutoff frequency of the low-pass filter 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 1k@100MHz. Preferably, the impedance of the first magnetic bead FB1 is 1.8k@100MHz.

[0048] In other embodiments, the low-pass filter unit 206 further includes a second magnetic bead and / or a second inductor, which are combined in series with the first magnetic bead FB1. A first end of a 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 a 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, with continued reference to FIG3 , the anti-interference circuit 204 further includes a voltage suppression unit, which includes a first voltage suppressor TVS1 (Transient Voltage Suppressor, for example, which may be a transient voltage suppressor). A first end of the first voltage suppressor TVS1 is connected to the target capacitor 205, and a second end of the first voltage suppressor TVS1 is coupled to ground (i.e., GND, Ground as shown in the figure). The first voltage suppressor TVS1 is used to suppress overvoltage from the target capacitor 205. For example, the first voltage suppressor TVS1 can clamp transient pulse interference such as ESD from the target capacitor 205, thereby preventing overvoltage from breaking down or burning components such as the anti-interference circuit 204 and the signal processing module 203.

[0050] Furthermore, the voltage suppression unit also includes a second voltage suppressor (TVS2). A first terminal of the second voltage suppressor (TVS2) is connected to the signal processing module 203, and a second terminal of the second voltage suppressor (TVS2) is coupled to ground. The second voltage suppressor (TVS2) is used to protect the signal processing module 203 from overvoltage, thereby preventing overvoltage from breaking down or damaging components within the signal processing module 203. In another example, the signal processing module 203 may have a built-in voltage suppressor. In this case, the second voltage suppressor (TVS2) is no longer required 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 introduced by the anti-interference circuit 204 is too large, it will inevitably affect the capture of the capacitance increment ΔC, thereby affecting 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 may also be other types of voltage suppressors, such as a spark gap, a thyristor, a varistor, or an avalanche diode.

[0052] In this embodiment, the anti-interference circuit 204 also includes a current regulating unit 207. The first end of the current regulating unit 207 is coupled to the signal processing module 203, and the second end of the current regulating unit 207 is coupled to the target capacitor 205. The current regulating unit 207 is used to regulate the current provided by the signal processing module 203 to the target capacitor 205. The current regulating 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, thereby affecting the signal-to-noise ratio of the signal received by the signal processing module 203. The current regulating unit 207 can limit the excessive DC current while suppressing AC noise. In other examples, the current regulating unit can also be other types of current regulating devices or circuits.

[0053] In addition, the present disclosure also proposes a circuit board having the above-mentioned anti-interference circuit. Figure 5 shows a schematic diagram of a circuit board (PCB, Printed Circuit Board) according to an embodiment of the present disclosure. The circuit board 30 includes a first signal layer 301 arranged on the first layer, a power 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 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 low impedance, which facilitates the noise backflow and reduces the impact of noise on the measurement.

[0054] Figure 6 shows a partial schematic diagram of the 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 of the signal of the target capacitor or the signal representing the target capacitor and a ground copper foil 42. The trace 41 of the signal of the target capacitor or the signal representing the target capacitor is at least a first distance d from the ground copper foil 42, wherein the first distance d is not less than 1 mm. If there are multiple signal traces that are close to each other in the signal layer, the outermost signal trace is at least a first distance d away from the ground copper foil. Maintaining at least the first distance d between the signal trace 41 and the ground copper foil 42 reduces the parasitic capacitance between the signal line and the ground signal. As mentioned above, the introduction of parasitic capacitance in the circuit should be reduced as much as possible to ensure the signal-to-noise ratio.

[0055] By adopting the above-mentioned anti-interference circuit or circuit board, the parasitic capacitance can be reduced as much as possible, and the ground plane noise can be weakened from being injected into the detection circuit through the parasitic capacitance, thereby weakening the impact of removing the shielding layer and improving the signal-to-noise ratio of the signal obtained by the signal processing module. Using the above-mentioned anti-interference circuit or circuit board, even if a steering wheel without the shielding layer is used, the signal-to-noise ratio requirements of the detection circuit can still be met, and the anti-interference tests in EMC can be passed, such as R1 (spatial radiation immunity), BCI (large current injection immunity), PTI (portable transmitter radio frequency immunity) and other tests. At the same time, the steering wheel without the shielding layer can save costs for manufacturers and make the steering wheel coating thinner. Of course, for steering wheels with a shielding layer, the above-mentioned anti-interference circuit or circuit board can also be used to implement HOD detection, which is conducive to improving the signal-to-noise ratio of the detection signal and improving the accuracy of detection.

[0056] In addition, the present disclosure also provides a detection system comprising at least one sensor layer (e.g., sensor layer 104 in FIG. 2 ). The detection system utilizes the aforementioned anti-interference circuit or circuit board to receive and process signals from the sensor layer and transmit the processed signals to a signal processing module of the detection system (e.g., signal processing module 203 in FIG. 3 or FIG. 4 ).

[0057] In one embodiment, the detection system further includes at least one heating layer (e.g., heating layer 103 in FIG. 2 ), wherein the sensor layer and the heating layer overlap in the projection direction. As described above, changes in the temperature of the heating layer can cause a certain offset in the detected signal, affecting the accuracy of the HOD detection results. However, because the detection system utilizes the anti-interference circuit or circuit board proposed in this disclosure, the signal-to-noise ratio can be greatly improved, ensuring the accuracy of the HOD detection results.

[0058] In one embodiment, no shielding layer is provided between the sensor layer and the heating layer. As described above, even without a shielding layer in the steering wheel, the detection system can still ensure the accuracy of the HOD detection results because it uses the anti-interference circuit or circuit board proposed in this disclosure.

[0059] In one embodiment, the sensor layer includes one or more detection areas. Figure 7 shows a schematic diagram of the detection area of ​​the sensor layer according to an embodiment of the present disclosure. The sensor layer may include a whole piece of metal wire mesh, wherein the area covered by the metal wire mesh is virtually divided into two detection areas, namely a detection area 50 located in front of the steering wheel, and a detection area 60 located behind 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 locations of the detection areas 50 and 60. When a human hand touches any one of the detection areas 50 or 60, the pressure-sensitive material can determine the location of the human hand, and then determine which detection area the human hand is touching.

[0060] In another example, with continued reference to FIG7 , the steering wheel sensor layer may include multiple pieces of metal mesh, which are structurally separated from one another. These metal meshes include a metal mesh located on the front side of the steering wheel and a metal mesh located on the rear side of the steering wheel, which correspond to detection areas 50 and 60, respectively. Each detection area is subordinate to a separate HOD detection circuit. Detection area 50 is subordinate to HOD detection circuit 50', and detection area 60 is subordinate to HOD detection circuit 60'. When a human hand touches either detection area 50 or detection area 60, the result obtained by the HOD detection circuit in which the detection area is located can be used to determine which detection area the human hand touched.

[0061] A sensor layer with multiple detection areas can more precisely distinguish the gestures of a person holding the steering wheel. Figure 8 shows a schematic diagram of the detection areas of the sensor layer on the front side of the steering wheel according to one embodiment of the present disclosure. In conjunction with Figures 7 and 8, in other examples, the sensor layer includes a detection area 51 located on the left front side of the steering wheel, a detection area 52 located on the right front side of the steering wheel, and a detection area 60 located on the rear side of the steering wheel. Based on similar principles as described above, it can be determined which area of ​​detection area 51, detection area 52, or detection area 60 the person's hand is touching.

[0062] In one embodiment, the detection system further includes at least one metal skeleton (e.g., metal skeleton 101 in FIG. 2 ), wherein the sensor layer (e.g., sensor layer 104 in FIG. 2 ) and the metal skeleton have overlapping portions 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 having a circuit. The circuit includes a low-pass filter unit, which includes a first capacitor, a first magnetic bead, and a first inductor. The first end of the low-pass filter unit is coupled to the signal processing module, the second end of the low-pass filter unit is coupled to the target capacitor, and the third end of the low-pass filter unit is coupled to the ground. The low-pass filter circuit directly or indirectly receives a signal from the target capacitor or a signal representing the target capacitor, processes the signal from the target capacitor or the signal representing the target capacitor, and transmits the processed signal to the signal processing module.

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

[0065] In one embodiment, the circuit board includes a signal layer. The signal layer includes a trace for a target capacitor signal or a signal representing the target capacitor and a ground copper sheet. The trace for the target capacitor signal or a signal representing the target capacitor and the ground copper sheet maintain at least a first distance therebetween, wherein the first distance is not less than 1 mm.

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

[0067] In addition, the present disclosure also provides a steering wheel, which includes the above-mentioned 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 (eg, the sensor layer 104 in FIG. 2 ) and a metal frame (eg, the metal frame 101 in FIG. 2 ), wherein no shielding layer is provided between the sensor layer and the metal frame.

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

[0070] It should be noted that the present invention (e.g., the inventive concept, etc.) has been described in the specification of this patent document and / or illustrated in the drawings based on exemplary embodiments; the embodiments of the present invention are presented only by way of example and are not intended to limit the scope of the 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 drawings is merely illustrative. Although exemplary embodiments of the present invention have been described in detail in this patent document, it is readily understood by those skilled 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 matters (e.g., modifications, variations, embodiments, combinations, equivalents, etc.) are intended to be included within the scope of the present invention. It should also be noted that various / other modifications, changes, substitutions, equivalents, changes, omissions, etc. may be made in the configuration and / or arrangement of the exemplary embodiments (e.g., in terms of concept, design, structure, device, form, assembly, construction, means, function, system, process / method, step, order of process / method steps, operation, operating conditions, performance, materials, composition, combination, etc.) without departing from the scope of the present invention; all of these subjects (e.g., modifications, changes, embodiments, combinations, equivalents, etc.) are 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 description and / or drawings of this patent document (e.g., details, structures, functions, materials, behaviors, steps, orders, systems, results, etc.). Considering that the claims of this patent document will be appropriately interpreted to cover the full scope of the subject matter of the present invention (e.g., including any and all such modifications, changes, embodiments, combinations, equivalents, etc.); it should be understood that the terminology used in this patent document is intended to provide a description of 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, depending on the exemplary embodiments, the present invention may include conventional technologies (such as those implemented and / or integrated in the exemplary embodiments, modifications, variations, combinations, equivalents), or may include any other applicable technologies (present and / or future) that have the ability to perform the functions and processes / operations described in the specification and / or illustrated in the figures. All of these technologies (such as those implemented in embodiments, modifications, variations, combinations, equivalents, etc.) are considered to be within the scope of the present invention of 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 foil. There is at least a first distance between the trace of the signal of the target capacitor or a signal characterizing the target capacitor and the ground copper foil, 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, the circuit board has 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 the target capacitor, and the third end of the low-pass filtering unit is coupled to ground. Wherein, the low-pass filter 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, and the ground layer 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, the signal layer includes traces of the signal of the target capacitor or a signal characterizing the target capacitor and ground copper clads, and at least a first distance is maintained 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.

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.

Images