A capacitance value detection device, a steering wheel control device, a steering wheel, and a vehicle
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- BYD CO LTD
- Filing Date
- 2025-06-19
- Publication Date
- 2026-07-14
AI Technical Summary
The capacitance detection results of conductor wires have low accuracy and are easily affected by additional interference, leading to inaccurate detection.
The processor outputs a reference signal to both ends of the conductor wire, and the signal follower circuit outputs a follower signal that is the same as the reference signal to the induction path, so as to maintain the voltage balance of the parasitic capacitor plates, reduce the influence of interference, and achieve accurate capacitance value sampling.
This improves the accuracy of capacitance detection and ensures the accuracy and reliability of the detection signal.
Smart Images
Figure CN224500774U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of vehicle control technology, and in particular to a capacitance detection device, a steering wheel control device, a steering wheel, and a vehicle. Background Technology
[0002] The vehicle steering wheel off-hand detection system is an important means of ensuring driving safety. Its technology mainly relies on the detection of capacitance values. By setting conductor wires in the metal frame of the steering wheel or a special sensing layer, the capacitance changes formed when the driver's hands touch the steering wheel are collected, thereby determining whether the driver's hands have left the steering wheel.
[0003] However, during the capacitance detection of a conductor wire, the two ends of the conductor wire may be in a suspended state or connected to other electronic components, which can easily introduce additional interference from the two ends of the conductor wire, resulting in lower accuracy of the capacitance value detection result. Utility Model Content
[0004] This application provides a capacitance value detection device to improve the detection accuracy of capacitance value, thereby at least partially solving the above-mentioned technical problems.
[0005] To achieve the above objectives, according to a first aspect of this application, a capacitance value detection device is provided, comprising:
[0006] Conductor wire;
[0007] A processor, connected to the conductor wire, is used to output reference signals to both ends of the conductor wire respectively;
[0008] A signal follower circuit, connected to the conductor wire and the processor, is used to output a follower signal identical to the reference signal based on the reference signal, and to output the follower signal to an induction path connected in series with the conductor wire;
[0009] The processor is also used to receive capacitance detection signals obtained from both ends of the conductor wire based on the reference signal.
[0010] Optionally, the signal follower circuit includes an operational amplifier;
[0011] The operational amplifier includes a first input terminal connected to the processor, a second input terminal connected to the sensing path, and an output terminal.
[0012] Optionally, the signal follower circuit includes a first resistor, a second resistor, a first transistor, a second transistor, and a third transistor;
[0013] The first transistor includes a base connected to the processor, a collector connected to the second transistor and the first end of the first resistor, and an emitter connected to the third transistor and the first end of the second resistor;
[0014] The second transistor includes a base connected to the first transistor, a collector connected to the power supply and the second terminal of the first resistor, and an emitter connected to the sensing path and the third transistor;
[0015] The third transistor includes a base connected to the first transistor, an emitter connected to the second transistor, and a collector connected to the second terminal of the second resistor and ground.
[0016] Optionally, it is applied to a vehicle steering wheel; the conductor wire is disposed inside the steering wheel to heat the steering wheel;
[0017] The induction path connected in series with the conductor wire includes a switching circuit; the switching circuit is used to control the connection and disconnection between the conductor wire and the power supply.
[0018] The signal following circuit is connected to the switching circuit and outputs the following signal to the switching circuit so that the voltages on both sides of the parasitic capacitor in the switching circuit are consistent.
[0019] Optionally, the switching circuit includes a first switching sub-circuit and a second switching sub-circuit;
[0020] The first switch sub-circuit is connected in series between the power supply and the conductor wire to control the connection and disconnection between the power supply and the conductor wire;
[0021] The second switch sub-circuit is connected in series between the conductor wire and ground to control the connection and disconnection between the conductor wire and ground.
[0022] Optionally, the first switching sub-circuit includes a first switching transistor and a second switching transistor;
[0023] The first switching transistor includes a control electrode that receives a heating control signal, a first electrode that is connected to the power supply, and a second electrode that is connected to the second switching transistor and the signal follower circuit;
[0024] The second switching transistor includes a control electrode that receives the heating control signal, a first electrode connected to the first switching transistor, and a second electrode connected to the first end of the conductor wire.
[0025] Optionally, the second switching sub-circuit includes a third switching transistor and a fourth switching transistor;
[0026] The third switching transistor includes a control electrode that is connected to the heating control signal, a first electrode that is connected to the second end of the conductor wire, and a second electrode that is connected to the fourth switching transistor and the signal follower circuit.
[0027] The fourth switching transistor includes a control electrode that is connected to the heating control signal, a first electrode that is connected to the third switching transistor, and a grounded second electrode.
[0028] Optionally, it also includes a controller and a load driver;
[0029] The controller is used to output a first control signal to the load driver, so that the load driver outputs the heating control signal to the switching circuit to control the switching circuit to turn on.
[0030] Optionally, a current detection circuit connected in series with the conductor wire is also included, which is used to collect the heating current of the conductor wire when the switching circuit is on, and output the heating current to the load driver so that the load driver controls the switching circuit to be turned off according to the heating current.
[0031] Optionally, the controller is further configured to output a second control signal to the processor to cause the processor to output the reference signal, and receive a capacitance detection signal from the processor, and generate a steering wheel off-hand detection result based on the capacitance detection signal;
[0032] The controller outputs the first control signal and the second control signal at different time periods.
[0033] According to a second aspect of this application, a steering wheel control device is provided, including the aforementioned capacitance value detection device.
[0034] According to a third aspect of this application, a steering wheel is provided, including the steering wheel control device described above.
[0035] According to a fourth aspect of this application, a vehicle is provided, including the steering wheel described above.
[0036] In summary, in the capacitance detection device of this application embodiment, firstly, the processor outputs a reference signal to both ends of the conductor wire to excite the conductor wire to interact with the surrounding environment, so that the change in capacitance on the conductor wire can be reflected by the change in the reference signal. During this process, the signal follower circuit outputs a follower signal identical to the reference signal to the sensing path, so that the voltage of the two plates of the parasitic capacitor in the sensing path remains balanced and cannot conduct, thereby reducing the interference of the sensing path to the reference signal. At this time, the processor receives the capacitance detection signal obtained by the change in the reference signal caused by the change in capacitance characteristics on the conductor wire. This capacitance detection signal can accurately reflect the change in capacitance on the conductor wire, thereby realizing accurate sampling of the capacitance value.
[0037] Other features and advantages of this application will be described in detail in the following detailed description section. Attached Figure Description
[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0039] To gain a more complete understanding of this application and its beneficial effects, the following description will be provided in conjunction with the accompanying drawings, wherein the same reference numerals in the following description denote the same parts.
[0040] Figure 1 This is a schematic diagram of the capacitance detection device provided in an exemplary embodiment of this disclosure;
[0041] Figure 2 This is a circuit connection diagram of a signal follower circuit provided in an exemplary embodiment of this disclosure;
[0042] Figure 3 This is a circuit connection diagram of another signal follower circuit provided in an exemplary embodiment of this disclosure;
[0043] Figure 4 This is a schematic diagram of a switching circuit provided in an exemplary embodiment of this disclosure;
[0044] Figure 5 This is a circuit connection diagram of the capacitance detection device provided in an exemplary embodiment of this disclosure;
[0045] Figure 6 This is a timing diagram of time-division multiplexing provided in an exemplary embodiment of this disclosure.
[0046] Explanation of reference numerals in the attached diagram: 1. Conductor wire; 2. Processor; 3. Signal follower circuit; 4. Switching circuit; 41. First switch sub-circuit; 42. Second switch sub-circuit; 5. Controller; 6. Load driver; 7. Current detection circuit. Detailed Implementation
[0047] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the protection scope of this application.
[0048] According to the first aspect of this application, referring to Figure 1 This disclosure provides a capacitance detection device, including a conductor wire 1, a processor 2, and a signal follower circuit 3. The processor 2 is connected to the conductor wire 1 and outputs a reference signal Vh to both ends of the conductor wire 1. The signal follower circuit 3 is connected to the conductor wire 1 and the processor 2, and outputs a follower signal Vf identical to the reference signal Vh, and outputs the follower signal Vf to an induction path connected in series with the conductor wire 1. The processor 2 is also used to receive capacitance detection signals obtained at both ends of the conductor wire 1 based on the reference signal Vh.
[0049] The reference signal Vh serves as the excitation source for capacitance detection. Its transmission and change within conductor wire 1 reflect the change in capacitance value on conductor wire 1. The reference signal Vh can be a cosine signal, expressed as Vh = V × sin(ωt); where V is the amplitude of the reference signal Vh, ω is the phase of the reference signal Vh, and t is time. The follower signal Vf has the same phase and amplitude as the reference signal Vh, and can be expressed as Vf = V × sin(ωt).
[0050] As an example, the processor 2 outputs the reference signal Vh and receives the capacitance detection signal at different time periods. For example, the processor 2 can continuously output the reference signal Vh to both ends of the conductor wire 1 during the first time period, and stop outputting the reference signal Vh during the second time period after the first time period. When a human body approaches or touches other objects with metal wires, the capacitance environment around the conductor wire 1 will change, thereby changing the capacitance characteristics of the conductor wire 1, which will cause the reference signal Vh on the conductor wire 1 to change. At this time, the processor 2 receives the capacitance detection signal obtained at both ends of the conductor wire 1 according to the change of the reference signal Vh. The capacitance detection signal can reflect the change of capacitance value on the conductor wire 1.
[0051] The sensing path can be equipped with electronic components to realize other circuit functions. These electronic components can be switching transistors, diodes, triodes, etc., resulting in a certain amount of parasitic capacitance in the sensing path. Since the sensing path is connected in series with the conductor wire 1, the first plate of the parasitic capacitance is connected to the conductor wire 1, and the following signal Vf is output to the second plate of the parasitic capacitance in the sensing path. Since the following signal Vf is consistent with the reference signal Vh transmitted to the conductor wire 1, the potentials of the first and second plates of the parasitic capacitance are always in a balanced state, and there is no potential difference. The parasitic capacitance cannot conduct, so the reference signal Vh transmitted by the processor 2 to the conductor wire 1 will not continue to be transmitted to the parasitic capacitance. This ensures that the parasitic capacitance in the sensing path does not affect the reference signal Vh, so that the conductor wire 1 can provide a more accurate capacitance detection signal.
[0052] In the above embodiment, firstly, the processor 2 outputs a reference signal Vh to both ends of the conductor wire 1 to excite the conductor wire 1 to interact with the surrounding environment, so that the change in the capacitance value on the conductor wire 1 can be reflected by the change in the reference signal Vh. During this process, the signal follower circuit 3 outputs a follower signal Vf, which is the same as the reference signal Vh, to the sensing path, so that the voltage of the two plates of the parasitic capacitor in the sensing path remains balanced and cannot conduct, thereby reducing the interference of the sensing path on the reference signal Vh. At this time, the processor 2 receives the capacitance detection signal obtained by the change in the reference signal Vh caused by the change in capacitance characteristics on the conductor wire 1. This capacitance detection signal can accurately reflect the change in the capacitance value on the conductor wire 1, thereby realizing accurate sampling of the capacitance value.
[0053] Reference Figure 2 In the first embodiment, the signal follower circuit 3 includes an operational amplifier U1. The operational amplifier U1 includes a first input terminal connected to the processor 2, a second input terminal connected to the sensing path, and an output terminal.
[0054] As an example, the first input terminal can be the non-inverting input terminal and the second input terminal can be the inverting input terminal. When the operational amplifier U1 is operating in the linear region, the potentials of its non-inverting and inverting input terminals are approximately equal, and the current flowing into the non-inverting and inverting input terminals of the operational amplifier U1 is approximately zero.
[0055] Thus, when the reference signal Vh is input to the first input terminal, the potential of the second input terminal will also approach the potential of the first input terminal. Since no current flows into the second input terminal, the voltage at the output terminal of the operational amplifier U1 will, through feedback, make the potential of the second input terminal equal to the potential of the reference signal Vh at the first input terminal. At this time, the follower signal Vf output from the output terminal is identical to the reference signal Vh input to the first input terminal in amplitude, frequency, and phase, thereby realizing the generation of the follower signal Vf.
[0056] Reference Figure 3 In the second embodiment, the signal follower circuit 3 includes a first resistor R1, a second resistor R2, a first transistor Q1, a second transistor Q2, and a third transistor Q3. The first transistor Q1 includes a base connected to the processor 2, a collector connected to the second transistor Q2 and a first terminal of the first resistor R1, and an emitter connected to the third transistor Q3 and the first terminal of the second resistor R2. The second transistor Q2 includes a base connected to the first transistor Q1, a collector connected to the power supply and a second terminal of the first resistor R1, and an emitter connected to the sensing path and the third transistor Q3. The third transistor Q3 includes a base connected to the first transistor Q1, an emitter connected to the second transistor Q2, and a collector connected to the second terminal of the second resistor R2 and ground.
[0057] As an example, transistors Q1 and Q2 can be NPN transistors, and transistor Q3 can be a PNP transistor. Since the reference signal Vh is a cosine signal, it has a positive half-cycle and a negative half-cycle. When Vh is in the positive half-cycle, transistor Q1 is turned on, making the bases of transistors Q2 and Q3 high. At this time, transistor Q2 is turned on and transistor Q3 is turned off, with transistor Q2 outputting a following signal Vf for the positive half-cycle. When Vh is in the negative half-cycle, transistor Q1 is turned off, transistor Q2 is turned off, and transistor Q3 is turned on, causing transistor Q3 to output a following signal Vf for the negative half-cycle, thus ensuring that the following signal Vf maintains phase with the reference signal Vh. By adjusting the values of the first resistor R1 and the second resistor R2, the conduction levels of the second transistor Q2 and the third transistor Q3 can be changed, thereby making the amplitude of the follower signal Vf consistent with that of the reference signal Vh. In this way, a follower signal Vf that is consistent with the reference signal Vh can be generated.
[0058] In some embodiments, the capacitance detection device is applied to a vehicle steering wheel. A conductor wire 1 is disposed inside the steering wheel to heat it. The induction path connected in series with the conductor wire 1 includes a switching circuit 4. The switching circuit 4 is used to control the on / off connection between the conductor wire 1 and the power supply, thereby controlling the start and stop of heating of the conductor wire 1. A signal following circuit 3 is connected to the switching circuit 4 and outputs the following signal Vf to the switching circuit 4 to make the voltages on both sides of the parasitic capacitor in the switching circuit 4 consistent.
[0059] As an example, conductor wire 1 can be wound around the circular spokes of the steering wheel. To simultaneously achieve the steering wheel heating function and the hands-off detection function, conductor wire 1 can be reused. When the steering wheel needs to be heated, the control switch circuit 4 is connected to the power supply, and the voltage generates heat through conductor wire 1 to heat the steering wheel. When the steering wheel needs to be detected for hands-off, the switch circuit 4 is disconnected from the power supply. At this time, the following signal Vf is output to the switch circuit 4 so that the voltages on the two plates of the parasitic capacitor in the switch circuit 4 are consistent and cannot conduct, thus not affecting the detection of the capacitance value on conductor wire 1.
[0060] Reference Figure 4 In some embodiments, the switching circuit 4 includes a first switching sub-circuit 41 and a second switching sub-circuit 42. The first switching sub-circuit 41 is connected in series between the power supply and the conductor wire 1, and is used to control the connection and disconnection between the power supply and the conductor wire 1. The second switching sub-circuit 42 is connected in series between the conductor wire 1 and ground, and is used to control the connection and disconnection between the conductor wire 1 and ground.
[0061] As an example, when the steering wheel needs to be heated, the first switch sub-circuit 41 and the second switch sub-circuit 42 are turned on to form a loop from the power supply through the conductor wire 1 to ground, causing the conductor wire 1 to start heating. When the steering wheel needs to be removed from the hands, the first switch sub-circuit 41 and the second switch sub-circuit 42 are turned off to prevent the power supply and ground from affecting the capacitance value on the conductor wire 1.
[0062] Reference Figure 5 In some embodiments, the first switching sub-circuit 41 includes a first switching transistor T1 and a second switching transistor T2. The first switching transistor T1 includes a control electrode that receives the heating control signal, a first electrode that is connected to the power supply, and a second electrode that is connected to the second switching transistor T2 and the signal follower circuit 3. The second switching transistor T2 includes a control electrode that receives the heating control signal, a first electrode that is connected to the first switching transistor T1, and a second electrode that is connected to the first end of the conductor wire 1.
[0063] As an example, the first switch T1 and the second switch T2 can form a dual MOS transistor. The signal follower circuit 3 outputs the follower signal Vf between the first switch T1 and the second switch T2. When the steering wheel is off-hand, the power supply is disconnected from the signal follower circuit 3 through the first switch T1 to avoid the power supply output voltage providing an additional DC component to the follower signal Vf, so that the follower signal Vf is consistent with the reference signal Vh.
[0064] Reference Figure 5In some embodiments, the second switching sub-circuit 42 includes a third switching transistor T3 and a fourth switching transistor T4. The third switching transistor T3 includes a control electrode connected to the heating control signal, a first electrode connected to the second end of the conductor wire 1, and a second electrode connected to the fourth switching transistor T4 and the signal follower circuit 3. The fourth switching transistor T4 includes a control electrode connected to the heating control signal, a first electrode connected to the third switching transistor T3, and a grounded second electrode.
[0065] Among them, the first switch T1, the second switch T2, the third switch T3 and the fourth switch T4 can all be N-type transistors.
[0066] As an example, the third switch T3 and the fourth switch T4 can form a dual MOSFET. The signal follower circuit 3 outputs the follower signal Vf between the third switch T3 and the fourth switch T4. When the steering wheel is off-hand, the fourth switch T4 disconnects the ground from the signal follower circuit 3 to avoid the follower signal Vf output by the signal follower circuit 3 flowing directly to the ground, which would cause the follower signal Vf to be inconsistent with the reference signal Vh.
[0067] In some embodiments, the capacitance detection device further includes a controller 5 and a load driver 6. The controller 5 is used to output a first control signal to the load driver 6, so that the load driver 6 outputs a heating control signal to the switching circuit 4 to control the switching circuit 4 to turn on.
[0068] As an example, the power supply voltage of controller 5 is generally 5V or 3.3V, and the signal output of each pin of controller 5 cannot exceed its power supply voltage. That is, the maximum heating control signal is 5V or 3.3V. However, the conduction threshold voltage of the first switch T1, the second switch T2, the third switch T3, and the fourth switch T4 is usually greater than 10V. The first controller 5 can output a high-level heating control signal to the load driver 6. After receiving the high-level heating control signal, the load driver 6 boosts it to input a signal greater than the conduction threshold voltage to the first switch T1, the second switch T2, the third switch T3, and the fourth switch T4, thereby controlling the first switch T1, the second switch T2, the third switch T3, and the fourth switch T4 to be saturated and turned on.
[0069] Reference Figure 5 In some embodiments, the capacitance detection device further includes a current detection circuit 7 connected in series with the conductor wire 1, which is used to collect the heating current of the conductor wire 1 when the switching circuit 4 is on, and output the heating current to the load driver 6 so that the load driver 6 controls the switching circuit 4 to be turned off according to the heating current.
[0070] As an example, when the circuit detects that the heating current is greater than the current threshold, the load driver 6 can stop outputting signals to the first switch T1, the second switch T2, the third switch T3 and the fourth switch T4, so that the first switch T1, the second switch T2, the third switch T3 and the fourth switch T4 are disconnected. At this time, no current flows through the conductor wire 1, and the heating of the steering wheel stops.
[0071] In some embodiments, the controller 5 is further configured to output a second control signal to the processor 2 to cause the processor 2 to output a reference signal Vh, and to receive a capacitance detection signal from the processor 2, and to generate a steering wheel off-hand detection result based on the capacitance detection signal.
[0072] The controller 5 outputs the first control signal and the second control signal at different time periods.
[0073] As an example, the capacitance detection signal includes a first detection signal from the first end of conductor wire 1 and a second detection signal from the second end of conductor wire 1. After receiving the first and second detection signals, controller 5 first performs filtering and other processing, then subtracts the first and second detection signals to eliminate common-mode interference, thereby obtaining the capacitance value on conductor wire 1. Since the capacitance value on conductor wire 1 changes when a human body touches the steering wheel, the hand-off detection result, which characterizes whether the human body has left the steering wheel, can be obtained through the capacitance value on conductor wire 1. For example, when the capacitance value on conductor wire 1 is greater than a preset value, the hand-off detection result is determined to be that the human body is in contact with the steering wheel. When the capacitance value on conductor wire 1 is less than or equal to the preset value, the hand-off detection result is determined to be that the human body is not in contact with the steering wheel.
[0074] Reference Figure 6 As an example, this disclosure exemplarily describes the operation of a capacitance value detection device:
[0075] When only steering wheel heating is needed, the controller 5 first controls the processor 2 to enter standby mode. At this time, the processor 2 does not output the reference signal Vh, and the signal follower circuit 3 does not output the follower signal Vf. The controller 5 outputs the first control signal to the load driver 6, so that the load driver 6 outputs the heating control signal and simultaneously controls the first switch T1, the second switch T2, the third switch T3, and the fourth switch T4 to conduct. At this time, current flows through the conductor wire 1 and begins to heat up, thereby heating the steering wheel.
[0076] When only a hands-off detection of the steering wheel is required, controller 5 stops outputting the first control signal to load driver 6, causing load driver 6 to control the first switch T1, second switch T2, third switch T3, and fourth switch T4 to disconnect. Then, during the first time period t1, controller 5 outputs a second control signal to processor 2, causing processor 2 to output a reference signal Vh to conductor wire 1 and signal follower circuit 3, causing signal follower circuit 3 to output a follower signal Vf. The follower signal Vf is applied between the first switch T1 and the second switch T2, and between the third switch T3 and the fourth switch T4, so that there is no voltage difference between the first and second electrodes of the second switch T2 and the first and second electrodes of the third switch T3, thus preventing the parasitic capacitance in the second switch T2 and the third switch T3 from conducting. Finally, during the second time period t2, processor 2 stops outputting the reference signal Vh and collects the change of the reference signal Vh on conductor wire 1 to obtain a capacitance detection signal. The capacitance detection signal is transmitted to controller 5, which processes it to obtain the hands-off detection result.
[0077] When both steering wheel heating and hands-off detection are required, during the heating period T1, controller 5 controls processor 2 to enter standby mode, and controller 5 outputs a first control signal to load driver 6 to heat the steering wheel. During the hands-off detection period T2, which includes a first period t1 and a second period t2, the specific working principles of the first period t1 and the second period t2 are the same as when only hands-off detection is needed, and will not be repeated here. The durations of heating period T1 and hands-off detection period T2 are set; for example, heating period T1 can be set to 20 milliseconds, and hands-off detection period T2 can be set to 80 milliseconds. This cycle repeats continuously, achieving hands-off detection while heating the steering wheel through time-division multiplexing.
[0078] According to a second aspect of this application, a steering wheel control device is provided, including the aforementioned capacitance value detection device.
[0079] According to a third aspect of this application, a steering wheel is provided, including the steering wheel control device described above.
[0080] According to a fourth aspect of this application, a vehicle is provided, including the aforementioned steering wheel.
[0081] The vehicle may be a gasoline-powered vehicle, a plug-in hybrid electric vehicle, or a new energy vehicle, etc., and this disclosure does not make any specific restrictions.
[0082] In the description of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.
[0083] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.
[0084] The embodiments, implementation methods, and related technical features of this application can be combined and substituted for each other without conflict.
[0085] The above are merely preferred embodiments of this application and are not intended to limit this application in any way. Any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of this application without departing from the scope of the technical solution of this application shall still fall within the scope of the technical solution of this application.
Claims
1. A capacitance value detection device, characterized in that, include: Conductor wire; A processor, connected to the conductor wire, is used to output reference signals to both ends of the conductor wire respectively; A signal follower circuit, connected to the conductor wire and the processor, is used to output a follower signal identical to the reference signal based on the reference signal, and to output the follower signal to an induction path connected in series with the conductor wire; The processor is also used to receive capacitance detection signals obtained from both ends of the conductor wire based on the reference signal.
2. The capacitance detection device according to claim 1, characterized in that, The signal follower circuit includes an operational amplifier; The operational amplifier includes a first input terminal connected to the processor, a second input terminal connected to the sensing path, and an output terminal.
3. The capacitance detection device according to claim 1, characterized in that, The signal follower circuit includes a first resistor, a second resistor, a first transistor, a second transistor, and a third transistor; The first transistor includes a base connected to the processor, a collector connected to the second transistor and the first end of the first resistor, and an emitter connected to the third transistor and the first end of the second resistor; The second transistor includes a base connected to the first transistor, a collector connected to the power supply and the second terminal of the first resistor, and an emitter connected to the sensing path and the third transistor; The third transistor includes a base connected to the first transistor, an emitter connected to the second transistor, and a collector connected to the second terminal of the second resistor and ground.
4. The capacitance detection device according to claim 1, characterized in that, Applied to vehicle steering wheels; the conductor wire is disposed inside the steering wheel to heat the steering wheel; The induction path connected in series with the conductor wire includes a switching circuit; the switching circuit is used to control the connection and disconnection between the conductor wire and the power supply. The signal following circuit is connected to the switching circuit and outputs the following signal to the switching circuit so that the voltages of the two plates of the parasitic capacitor in the switching circuit are consistent.
5. The capacitance detection device according to claim 4, characterized in that, The switching circuit includes a first switching sub-circuit and a second switching sub-circuit; The first switch sub-circuit is connected in series between the power supply and the conductor wire to control the connection and disconnection between the power supply and the conductor wire; The second switch sub-circuit is connected in series between the conductor wire and ground to control the connection and disconnection between the conductor wire and ground.
6. The capacitance detection device according to claim 5, characterized in that, The first switching sub-circuit includes a first switching transistor and a second switching transistor; The first switching transistor includes a control electrode that receives a heating control signal, a first electrode that is connected to the power supply, and a second electrode that is connected to the second switching transistor and the signal follower circuit; The second switching transistor includes a control electrode that receives the heating control signal, a first electrode connected to the first switching transistor, and a second electrode connected to the first end of the conductor wire.
7. The capacitance detection device according to claim 6, characterized in that, The second switching sub-circuit includes a third switching transistor and a fourth switching transistor; The third switching transistor includes a control electrode that is connected to the heating control signal, a first electrode that is connected to the second end of the conductor wire, and a second electrode that is connected to the fourth switching transistor and the signal follower circuit. The fourth switching transistor includes a control electrode that is connected to the heating control signal, a first electrode that is connected to the third switching transistor, and a grounded second electrode.
8. The capacitance detection device according to claim 7, characterized in that, It also includes the controller and load driver; The controller is used to output a first control signal to the load driver, so that the load driver outputs the heating control signal to the switching circuit to control the switching circuit to turn on.
9. The capacitance detection device according to claim 8, characterized in that: It also includes a current detection circuit connected in series with the conductor wire, used to collect the heating current of the conductor wire when the switching circuit is on, and output the heating current to the load driver so that the load driver controls the switching circuit to be turned off according to the heating current.
10. The capacitance detection device according to claim 8, characterized in that: The controller is also configured to output a second control signal to the processor to cause the processor to output the reference signal, and to receive the capacitance detection signal from the processor to generate a steering wheel off-hand detection result based on the capacitance detection signal; The controller outputs the first control signal and the second control signal at different time periods.
11. A steering wheel control device, characterized in that, Includes the capacitance detection device as described in any one of claims 1 to 10.
12. A steering wheel, characterized in that, Includes the steering wheel control device as described in claim 11.
13. A vehicle, characterized in that, Includes the steering wheel as described in claim 12.