A combined circuit for hand release detection and heating, and its control method.

Abstract

This invention discloses a combined hands-free detection and heating circuit and its control method, relating to the field of autonomous driving. Both the first and second isolation modules include MOSFETs. When hands-free detection of the steering wheel is required, the control module not only outputs an excitation signal to the steering wheel through its second output terminal but also outputs a shielding signal through its first output terminal. At this time, the two ends of the first isolation module receive the excitation signal and the shielding signal respectively, and the two ends of the second isolation module also receive the excitation signal and the shielding signal respectively. By using identical excitation and shielding signals, the charging and discharging of the junction capacitance of the MOSFETs in the two isolation modules is avoided, thereby reducing the influence of the MOSFET junction capacitance on the hands-free detection signal. No additional hardware components are required, saving the hardware space and cost of the entire circuit. This facilitates the flexible application of the combined hands-free detection and heating circuit and expands its applicability.

Description

Technical Field

[0001] This invention relates to the field of autonomous driving, and in particular to a combined circuit for hands-free detection and heating, and its control method. Background Technology

[0002] Most existing automotive steering wheel hands-off detection systems on the market require a detection film and a shielding film. If a heating function is needed, an additional heating film is required, resulting in high costs. Current technology can reuse the heating film to achieve both heating and hands-off detection functions. However, to avoid interference between the heating control circuit and the hands-off detection circuit, an isolation circuit needs to be added to the heating control circuit. This isolation circuit is often implemented using diodes or MOSFETs (Metal-Oxide-Semiconductor Field-Effect Transistors). However, when diodes are used for isolation, they generate significant heat, leading to substantial circuit losses. Considering the excessive circuit losses caused by diode heat, current isolation circuits often use MOSFETs. However, in the design, multiple MOSFETs are usually connected in series to reduce the junction capacitance across the isolation circuit, thereby reducing the impact of the MOSFET junction capacitance on the hands-off detection signal. This approach requires multiple MOSFETs, necessitating significant hardware space. Summary of the Invention

[0003] The purpose of this invention is to provide a combined circuit for release detection and heating, and its control method. By using identical excitation and shielding signals, the charging and discharging of the junction capacitance of the MOS transistors in the two isolation modules is avoided, thereby reducing the influence of the junction capacitance of the MOS transistors on the release detection signal. No additional hardware components are required, saving the hardware space and cost required for the entire circuit. This facilitates the flexible application of the combined release detection and heating circuit and expands its applicability.

[0004] To solve the above-mentioned technical problems, the present invention provides a two-in-one circuit for hands-free detection and heating, which is applied to the steering wheel of a vehicle. The circuit includes a heating high-side drive module, a first isolation module, a second isolation module, a heating low-side switch module, and a control module.

[0005] The first end of the heating high-side drive module is connected to the power supply, and the second end is connected to the first end of the first isolation module and the first output end of the control module. The second end of the first isolation module is connected to the first end of the steering wheel. The first end of the heating low-side switch module is grounded, and the second end is connected to the first end of the second isolation module and the first output end of the control module. The second end of the second isolation module is connected to the second end of the steering wheel and the second output end of the control module. Both the first isolation module and the second isolation module include MOSFETs.

[0006] The control module is used to output an excitation signal to the steering wheel when a detection signal is received to detect whether the steering wheel is in a hands-free state, and at the same time output a shielding signal to the first end of the first isolation module and the first end of the second isolation module. The shielding signal is exactly the same as the excitation signal.

[0007] Optionally, the control module includes a hands-off detection module and a main processor; the input terminal of the hands-off detection module is connected to the output terminal of the main processor, the first output terminal is connected to the second terminal of the heated low-side switch module, the first terminal of the second isolation module, the second terminal of the heated high-side drive module and the first terminal of the first isolation module respectively, and the second output terminal is connected to the second terminal of the steering wheel and the second terminal of the second isolation module respectively;

[0008] The release detection module is used to output the excitation signal and the shielding signal based on the control of the main processor when a detection signal is received;

[0009] The main processor is used to determine whether the steering wheel is in a hands-free state based on the detection signal returned by the hands-free detection module.

[0010] Optionally, the heating high-side drive module includes a driver, a first current-limiting resistor, a second current-limiting resistor, and a diode. The power port of the driver is connected to a power supply, the input port is connected to the first end of the first current-limiting resistor, the second end of the first current-limiting resistor is connected to the main processor, the ground port of the driver is connected to the first end of the second current-limiting resistor and the positive terminal of the diode, the second end of the second current-limiting resistor is grounded and connected to the negative terminal of the diode, and the output terminal of the driver serves as the output terminal of the heating high-side drive module.

[0011] Optionally, the heating low-side switch module includes an NMOS transistor and a third current-limiting resistor; the drain of the NMOS transistor is connected to the first terminal of the second MOS transistor and the first output terminal of the release detection module, the source is grounded, the gate is connected to the first terminal of the third current-limiting resistor, and the second terminal of the third current-limiting resistor is connected to the main processor.

[0012] Optionally, it may also include a first capacitor, a second capacitor, and a third capacitor;

[0013] The first terminal of the first capacitor is connected to the first output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the high-side heating drive module and the first terminal of the first MOS transistor. The first terminal of the second capacitor is connected to the first output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the low-side heating switch module and the first terminal of the second MOS transistor. The first terminal of the third capacitor is connected to the second output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the second MOS transistor and the second terminal of the steering wheel.

[0014] Optionally, it also includes NTC resistors disposed at both ends of the heating coil of the steering wheel; the main processor is further configured to determine the current temperature based on the NTC resistors, and to perform temperature compensation on the detection results returned by the hands-off detection module based on the current temperature.

[0015] Optionally, it also includes a detection resistor and a detection capacitor, wherein the detection resistor and the detection capacitor are connected in series, and the first end of the series circuit is connected to the third output terminal of the release detection module, and the second end is grounded; the main processor is also used to obtain the environmental detection value corresponding to the release detection module itself by controlling the third output terminal of the release detection module to output an excitation signal, and to correct the detection result returned by the release detection module based on the environmental detection value.

[0016] Optionally, it further includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first terminal of the first resistor is grounded, and the second terminal is connected to the first terminal of the second resistor, the second terminal of the heating high-side drive module, the first terminal of the first isolation module, and the first output terminal of the control module, respectively; the second terminal of the second resistor is connected to the second terminal of the first isolation module and the first terminal of the steering wheel, respectively; the first terminal of the third resistor is grounded, and the second terminal is connected to the first terminal of the fourth resistor, the second terminal of the heating low-side switch module, the first terminal of the second isolation module, and the first output terminal of the control module, respectively; the second terminal of the fourth resistor is connected to the second terminal of the second isolation module, the second terminal of the steering wheel, and the second output terminal of the control module, respectively.

[0017] To address the aforementioned technical problems, this invention also provides a control method for a combined hand-release detection and heating circuit, applied to the aforementioned combined hand-release detection and heating circuit. The method includes:

[0018] When a detection signal is received, an excitation signal is output to the steering wheel to detect whether the steering wheel is in a hands-free state;

[0019] Simultaneously with outputting the excitation signal, a shielding signal is output to the first end of the first isolation module and the first end of the second isolation module. The shielding signal is exactly the same as the excitation signal.

[0020] Optionally, before the output excitation signal, the following further includes:

[0021] When a detection signal is received, the heating high-side drive module is disconnected, while the first isolation module, the second isolation module, and the heating low-side switch module remain on.

[0022] After a preset time, the first isolation module, the second isolation module, and the heating low-side switch module are turned off.

[0023] This invention provides a combined hand-free detection and heating circuit, comprising a heating high-side drive module, a first isolation module, a second isolation module, a heating low-side switch module, and a control module. Both the first and second isolation modules include MOSFETs. When hand-free detection of the steering wheel is required, the control module outputs an excitation signal to the steering wheel through its second output terminal and a shielding signal through its first output terminal. At this time, the two ends of the first isolation module receive the excitation signal and the shielding signal respectively, and the two ends of the second isolation module also receive the excitation signal and the shielding signal respectively. By using identical excitation and shielding signals, the charging and discharging of the junction capacitance of the MOSFETs in the two isolation modules is avoided, thereby reducing the influence of the MOSFET junction capacitance on the hand-free detection signal. No additional hardware components are required, saving hardware space and cost for the entire circuit. This facilitates the flexible application of the combined hand-free detection and heating circuit and expands its applicability.

[0024] The present invention also provides a control method for a combined hand-release detection and heating circuit, which has the same beneficial effects as the above-mentioned combined hand-release detection and heating circuit. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the prior art and embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a combined hand-release detection and heating circuit provided by the present invention;

[0027] Figure 2This is a schematic diagram of another combined hand-release detection and heating circuit provided by the present invention;

[0028] Figure 3 This is a schematic diagram of the structure of a hand-removal detection module provided by the present invention;

[0029] Figure 4 This is a schematic diagram of the structure of a heating high-side drive module provided by the present invention;

[0030] Figure 5 This is a schematic diagram of the structure of a heating low-side switch module provided by the present invention;

[0031] Figure 6 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under the first circuit structure;

[0032] Figure 7 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under a second circuit structure;

[0033] Figure 8 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under a third circuit structure;

[0034] Figure 9 A schematic diagram of the structure of a first isolation module provided by the present invention;

[0035] Figure 10 A schematic diagram of another first isolation module provided by the present invention;

[0036] Figure 11 A schematic diagram of the signal waveform of a first isolation module under a first circuit structure provided by the present invention;

[0037] Figure 12 This invention provides a schematic diagram of the signal waveform of a first isolation module under a second circuit structure.

[0038] Figure 13 This is a schematic diagram of the structure of a second isolation module provided by the present invention;

[0039] Figure 14 This is a flowchart illustrating a control method for a combined hand-release detection and heating circuit provided by the present invention. Detailed Implementation

[0040] The core of this invention is to provide a combined circuit for release detection and heating, and its control method. By using identical excitation and shielding signals, the charging and discharging of the junction capacitance of the MOS transistors in the two isolation modules is avoided, thereby reducing the influence of the junction capacitance of the MOS transistors on the release detection signal. No additional hardware components are required, saving the hardware space and cost required for the entire circuit. This facilitates the flexible application of the combined release detection and heating circuit and expands its applicability.

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0042] The dual-function circuit for hands-off detection and heating provided by this invention mainly relates to the fields of automotive steering wheel heating and HOD (Hands-off Detection) for automotive steering wheels. It is applied when the steering wheel uses only a single layer of heating film, providing a hardware solution that integrates both heating and hands-off detection functions, as well as a control method based on this circuit scheme. This invention offers an isolated circuit and control method with fewer components, eliminates component overheating issues, removes the influence of the heating signal on the detection signal, and provides a control method based on this circuit scheme. Detailed implementation methods are described below.

[0043] Please refer to Figure 1 , Figure 1 This invention provides a schematic diagram of a combined hand-off detection and heating circuit. To solve the above-mentioned technical problems, this invention provides a combined hand-off detection and heating circuit, applied to a vehicle steering wheel 6. The circuit includes a heating high-side drive module 1, a first isolation module 2, a second isolation module 3, a heating low-side switch module 4, and a control module 5.

[0044] The first end of the heating high-side drive module 1 is connected to the power supply, and the second end is connected to the first end of the first isolation module 2 and the first output end of the control module 5 respectively. The second end of the first isolation module 2 is connected to the first end of the steering wheel 6. The first end of the heating low-side switch module 4 is grounded, and the second end is connected to the first end of the second isolation module 3 and the first output end of the control module 5 respectively. The second end of the second isolation module 3 is connected to the second end of the steering wheel 6 and the second output end of the control module 5 respectively. Both the first isolation module 2 and the second isolation module 3 include MOSFETs.

[0045] The control module 5 is used to output an excitation signal to the steering wheel 6 when a detection signal is received to detect whether the steering wheel 6 is in a hands-free state. At the same time, it outputs a shielding signal to the first end of the first isolation module 2 and the first end of the second isolation module 3. The shielding signal is exactly the same as the excitation signal.

[0046] Specifically, such as Figure 1 As shown, BAT is the power supply and GND is the reference ground. Figure 1 This is a basic circuit diagram of the present invention, applicable to heating based on a single heating wire in the steering wheel 6 and the process of detecting when the steering wheel 6 is removed from the hands. The output terminal of the high-side drive module of the heating circuit is connected to the input terminal of the first isolation module 2, and the output terminal of the first isolation module 2 is connected to the positive electrode of the heating film of the steering wheel 6. The input terminal of the low-side switch module of the heating circuit is connected to the output terminal of the second isolation module 3, and the input terminal of the second isolation module 3 is connected to the negative electrode of the heating film of the steering wheel 6. The steering wheel 6 is an externally heated steering wheel 6, requiring heating components such as heating wires or heating coils to achieve the heating process. When the steering wheel 6 needs to be heated, the control module 5 controls the heating high-side drive module 1, the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 to conduct, forming a conducting heating circuit to heat the steering wheel 6. When a hands-off detection of the steering wheel 6 is required, the control module 5 outputs an excitation signal to the steering wheel 6 through its second output terminal, thereby realizing the hands-off detection of the steering wheel 6. During this detection process, the control module 5 outputs an excitation signal to the first terminal of the first isolation module 2 and the second terminal of the first isolation module 3. An identical shielding signal, which is the same as the excitation signal used as the detection signal, is applied to the first end of the isolation module 3. At this time, the first end of the first isolation module 2 receives the shielding signal, and the second end receives the excitation signal through the connected steering wheel 6. The first end of the second isolation module 3 receives the shielding signal, and the second end receives the excitation signal through the connected steering wheel 6. Therefore, the two ends of the first isolation module 2 and the second isolation module 3 can receive two identical signals, avoiding the charging and discharging of the junction capacitance of the MOS transistors in the two isolation modules, thereby eliminating the influence of the junction capacitance of the MOS transistors used in the two isolation modules on the detection signal.

[0047] It should be noted that this application does not impose any special limitations on the specific implementation methods of the excitation signal and shielding signal output by the control module 5. Generally, a high-frequency sine wave can be used to implement the excitation signal. This application also does not impose any special limitations on the specific circuit structure and implementation methods of the heating high-side drive module 1, the first isolation module 2, the second isolation module 3, the heating low-side switch module 4, and the control module 5. The heating high-side drive module 1 is connected to the power supply and realizes the heating process of the heating component in the steering wheel 6 through the driver and other driving devices and the power supply. Switching devices such as MOSFETs can also be set inside so that the heating high-side drive module 1 can realize heating or stopping heating based on the control of the internal switching devices by the control module 5. The first isolation module 2 mainly plays an isolation role to prevent the connection between the heating high-side drive module 1 and the steering wheel 6 from affecting the hands-off detection signal of the steering wheel 6. The heating low-side switch module 4 is grounded and mainly plays a switching role to control the conduction and shutdown of the heating circuit. The second isolation module 3 mainly plays an isolation role to prevent the connection between the heating low-side switch module 4 and the steering wheel 6 from affecting the hands-off detection signal of the steering wheel 6.

[0048] It should be noted that the steering wheel 6 with an external heating coil is equipped with a heating film, around which a heating wire is wound. The two ends of the heating wire are connected to the first isolation module 2 and the second isolation module 3 via wires. This allows the heating circuit formed by the high-side drive module 1, the first isolation module 2, the second isolation module 3, and the low-side switch module 4 when they are turned on, thus heating the steering wheel 6. Simultaneously, the connection and excitation signal between the second output terminal of the control module 5 and the steering wheel 6 enable hands-free detection. Therefore, the hands-free detection and heating dual-function circuit provided by this invention can be applied to a steering wheel 6 with a single heating film, and can simultaneously achieve both heating and hands-free detection functions. This application does not impose any specific limitations on the specific type of steering wheel 6 and vehicle used, or the implementation method.

[0049] This invention provides a combined hand-drop detection and heating circuit, comprising a heating high-side drive module 1, a first isolation module 2, a second isolation module 3, a heating low-side switch module 4, and a control module 5. Both the first isolation module 2 and the second isolation module 3 include MOSFETs. When hand-drop detection of the steering wheel 6 is required, the control module 5 outputs an excitation signal to the steering wheel 6 through its second output terminal and a shielding signal through its first output terminal. At this time, the two ends of the first isolation module 2 receive the excitation signal and the shielding signal respectively, and the two ends of the second isolation module 3 also receive the excitation signal and the shielding signal respectively. By using identical excitation and shielding signals, the charging and discharging of the junction capacitance of the MOSFETs in the two isolation modules is avoided, thereby reducing the influence of the MOSFET junction capacitance on the hand-drop detection signal. No additional hardware components are required, saving the hardware space and cost of the entire circuit. This facilitates the flexible application of the combined hand-drop detection and heating circuit and expands its applicability.

[0050] Please refer to Figure 2 , Figure 2 This is a schematic diagram of another combined hand-release detection and heating circuit provided by the present invention; based on the above embodiments:

[0051] As an optional embodiment, the control module 5 includes a hands-off detection module 11 and a main processor; the input terminal of the hands-off detection module 11 is connected to the output terminal of the main processor, the first output terminal is connected to the second terminal of the heating low-side switch module 4, the first terminal of the second isolation module 3, the second terminal of the heating high-side drive module 1 and the first terminal of the first isolation module 2 respectively, and the second output terminal is connected to the second terminal of the steering wheel 6 and the second terminal of the second isolation module 3 respectively.

[0052] The release detection module 11 is used to output an excitation signal and a shielding signal based on the control of the main processor when a detection signal is received;

[0053] The main processor is used to determine whether the steering wheel 6 is in a hands-free state based on the detection signal returned by the hands-free detection module 11.

[0054] Considering that the control module 5 not only needs to output excitation signals to realize the release detection, but also needs to control the heating high-side drive module 1, the first isolation module 2, the second isolation module 3 and the heating low-side switch module 4 to complete the heating process, the control module 5 is implemented by a release detection module 11 and a main processor. The release detection module 11 is used to output excitation signals and shielding signals to complete the release detection process. The main processor is used to control the release detection module 11 and the heating high-side drive module 1, the first isolation module 2, the second isolation module 3 and the heating low-side switch module 4 to complete the release detection process and the heating process. This application does not make any special restrictions on the specific type and implementation method of the main processor and the release detection module 11. The main processor can control the entire circuit to perform release detection or heating by receiving external signals, or it can implement the release detection or heating process according to the internal pre-set program. The release detection module 11 can be implemented by a driver chip or other means.

[0055] As a specific embodiment, please refer to Figure 3 , Figure 3 This is a schematic diagram of a hand release detection module provided by the present invention. The hand release detection module 11 can be implemented by the AS8579 chip and its related peripheral circuits. The first output terminal of the hand release detection module 11 can be the VAR_SEN pin of the AMS chip U3. The second output of the off-hand detection module 11 can use the Sens0 pin of the AMS chip AS8579. The AMS chip provides ten detection pins, Sens0-9. ECLK is used as the crystal oscillator pin, CS is the chip select pin, and it can be directly connected to the 5V power supply VCC through the current limiting resistor R5. VDD1 and VDD2 are used as power supply pins and can be directly connected to the 5V power supply VCC. At the same time, a grounding capacitor C4 can be added to further protect the circuit. GND1 and GND2 are used as grounding pins and can be directly grounded. VREG1 and VREG2 are used as voltage adjustment pins and can be directly grounded through capacitor C5. SCLK is used as the clock pin. MISO is connected to the main processor and can return the detection signal read back after the detection pin sends the excitation signal to the main processor. The resistor R5 can be a fixed resistor with a resistance of 4.7K. The capacitor C4 can be implemented with a 100nF / 50V capacitor, and the capacitor C5 can be implemented with a 1μF / 50V capacitor. During the detection process, the first output terminal of the release detection module 11 needs to apply a shielding signal that is exactly the same as the detection signal, i.e. the excitation signal, to one pin of the first isolation module 2 and the second isolation module 3. This can eliminate the influence of the MOS transistor junction capacitance and isolate the influence of the front-end circuit capacitance of one pin.

[0056] Specifically, the functions of the control module 5 can be effectively realized through the hand-removal detection module 11 and the main processor. The main processor controls the hand-removal detection process and the heating process, while the hand-removal detection module 11 is used to realize hand-removal detection. The main processor can distinguish and control the hand-removal detection process and the heating process, further avoiding mutual interference between the two functions and improving the accuracy and reliability of the entire circuit.

[0057] Please refer to Figure 4 , Figure 4 This is a schematic diagram of a heating high-side drive module provided by the present invention. As an optional embodiment, the heating high-side drive module 1 includes a driver, a first current-limiting resistor R6, a second current-limiting resistor R7, and a diode D1. The power port of the driver is connected to the power supply, the input port is connected to the first end of the first current-limiting resistor R6, the second end of the first current-limiting resistor R6 is connected to the main processor, the ground port of the driver is connected to the first end of the second current-limiting resistor R7 and the positive terminal of the diode D1, the second end of the second current-limiting resistor R7 is grounded and connected to the negative terminal of the diode D1, and the output terminal of the driver serves as the output terminal of the heating high-side drive module 1.

[0058] It is easy to understand that the heating high-side drive module 1 can be implemented by a circuit consisting of a driver, a first current-limiting resistor R6, a second current-limiting resistor R7, and a diode D1. The first current-limiting resistor R6 is connected between the main processor and the heating high-side drive module 1, which plays the role of current limiting and voltage division, further protecting the circuit. The second current-limiting resistor R7 and the diode D1 work together to ensure that the current in the circuit of the heating high-side drive module 1 does not exceed the threshold, while avoiding negative voltage. The driver uses the connected power supply to power the heating wire in the steering wheel 6, thereby heating the steering wheel 6 when the heating circuit is on. This application does not make any special restrictions on the specific types and implementation methods of the driver, the first current-limiting resistor R6, the second current-limiting resistor R7, and the diode D1.

[0059] As a specific embodiment, with Figure 4For example, the high-side drive module of the heating circuit can be implemented using the BTS5010 chip and its related peripheral circuits. EP is used as the power supply port and is connected to the power supply. The OUT terminal is used as the output terminal of the heating high-side drive module 1. The IN terminal is used as the input terminal and is connected to the main processor through the first current-limiting resistor R6 to obtain the control signal of the main processor. The GND terminal is grounded through the second current-limiting resistor R7 and the diode D1. The DEN terminal and the IS terminal are used as current feedback ports for diagnostic purposes. In application, it is usually necessary to add a resistor R8 as a current-limiting resistor. Resistors R9 and R10 and capacitor C6 can form a voltage divider circuit for easy diagnostics. Resistor R7 can be implemented using a fixed resistor with a resistance of 1K. Resistors R6, R8 and R9 can all be implemented using fixed resistors with a resistance of 10K. Resistor R10 can be implemented using a fixed resistor with a resistance of 1.3K. Capacitor C6 can be implemented using a 2.2nF / 50V capacitor.

[0060] Specifically, the circuit consisting of the driver, the first current-limiting resistor R6, the second current-limiting resistor R7, and the diode D1 effectively realizes the heating high-side driving module 1, while further protecting the circuit. The entire circuit structure is simple and easy to implement. The components used are low-cost, small in size, and easy to integrate, which is conducive to the simple implementation of the overall circuit.

[0061] Please refer to Figure 5 , Figure 5 This is a schematic diagram of the structure of a heating low-side switch module 4 provided by the present invention. As an optional embodiment, the heating low-side switch module 4 includes an NMOS transistor and a third current-limiting resistor R11. The drain of the NMOS transistor is connected to the first terminal of the second MOS transistor and the first output terminal of the hand-off detection module 11, respectively. The source is grounded, the gate is connected to the first terminal of the third current-limiting resistor R11, and the second terminal of the third current-limiting resistor R11 is connected to the main processor.

[0062] It is understood that the low-side switch module of the heating circuit can be implemented by NMOS and its related peripheral circuits. In order to further protect the circuit, a third current-limiting resistor R11 is set between the main processor and the heating low-side switch module 4 to play the role of current limiting and voltage division. This application does not make any special restrictions on the specific type and implementation method of the NMOS transistor and the third current-limiting resistor R11. The resistor R11 can be implemented by a fixed resistor with a resistance of 10K.

[0063] Specifically, the circuit consisting of an NMOS transistor and a third current-limiting resistor R11 effectively heats the low-side switch module 4, while further protecting the circuit. The entire circuit structure is simple and easy to implement. The components used are low-cost, small in size, and easy to integrate, which is conducive to the simple implementation of the overall circuit.

[0064] As an optional embodiment, it also includes a first capacitor C1, a second capacitor C2, and a third capacitor C3;

[0065] The first terminal of the first capacitor C1 is connected to the first output terminal of the hands-off detection module 11, and the second terminal is connected to the second terminal of the heating high-side drive module 1 and the first terminal of the first MOSFET. The first terminal of the second capacitor C2 is connected to the first output terminal of the hands-off detection module 11, and the second terminal is connected to the second terminal of the heating low-side switch module 4 and the first terminal of the second MOSFET. The first terminal of the third capacitor C3 is connected to the second output terminal of the hands-off detection module 11, and the second terminal is connected to the second terminal of the second MOSFET and the second terminal of the steering wheel 6.

[0066] It is easy to understand that, in order to further improve the accuracy of the hands-free detection signal, a first capacitor C1, a second capacitor C2, and a third capacitor C3 are added. These capacitors provide DC isolation between the hands-free detection module 11 and other circuits. One pin of the hands-free detection module 11 is connected to one pin of the first capacitor C1, and the second pin of the first capacitor C1 is connected to the positive terminal of the steering wheel 6 heating film. One pin of the hands-free detection module 11 is connected to one pin of the second capacitor C2, and the second pin of the second capacitor C2 is connected to the negative terminal of the steering wheel 6 heating film. The second pin of the hands-free detection module 11 is connected to one pin of the third capacitor C3, and the second pin of the third capacitor C3 is connected to either the positive or negative terminal of the steering wheel 6 heating film. The pin that outputs the shielded signal from the hands-free detection module 11 is connected to both C1 and C2. This application does not specifically limit the specific types and implementation methods of the first capacitor C1, the second capacitor C2, and the third capacitor C3.

[0067] Specifically, a first capacitor C1, a second capacitor C2, and a third capacitor C3 are added to provide DC isolation, further improving the accuracy of the release detection module 11 and ensuring the accuracy and reliability of the release detection signal received by the main processor. The structure is simple, easy to implement, has low component cost, small size, and is easy to integrate, which is conducive to the simple implementation of the overall circuit.

[0068] As an optional embodiment, it also includes NTC (Negative Temperature Coefficient) resistors disposed at both ends of the heating coil of the steering wheel 6; the main processor is also used to determine the current temperature based on the NTC resistors and to perform temperature compensation on the detection results returned by the hands-off detection module 11 based on the current temperature.

[0069] Considering that the frame of the steering wheel 6 is generally a metal frame and the frame is grounded, the resistance and capacitance between the heating wire, i.e. the heating coil, and the frame of the steering wheel 6 will also be detected by the hands-off detection module 11. The resistance and capacitance between the heating wire and the frame are inherent parameters of the steering wheel 6 and are related to the temperature of the steering wheel 6. Therefore, temperature compensation can be performed by adding an NTC resistor and detecting the NTC resistance value. The NTC resistor can also be directly integrated into the heating film. This application does not specifically limit the specific type and implementation method of the NTC resistor. The NTC resistor can be bonded to the heating wire to realize the temperature detection on the steering wheel. Usually, the NTC resistor needs to form a voltage divider circuit with the voltage divider resistor. The current temperature is determined by the different voltages across the NTC resistor. The temperature detection process on the steering wheel can also be realized through other settings. There are also multiple choices for how to perform temperature compensation. This application does not specifically limit it. Before application, the correspondence between temperature and inherent resistance and capacitance can be determined. For example, when the temperature rises to the preset temperature, the inherent resistance and capacitance will increase by Δ. In the process of hands-free detection, if the measured value of steering wheel 6 obtained in the first detection is A and the measured value of steering wheel 6 obtained in the second detection is B, and the temperature obtained through the NTC resistor indicates that the temperature of the second detection has risen to the preset temperature compared with the first detection, then the actual detected change of steering wheel 6 in the two detections is B-A+Δ. The change in these two detections is not only due to the steering wheel 6, but also due to the change of inherent resistance and capacitance. Therefore, in the process of hands-free detection of steering wheel 6, the actual detected change of B-A+Δ should be used as the basis for judgment.

[0070] Specifically, an NTC resistor is added to obtain the current temperature, avoiding the influence of temperature-induced changes in inherent resistance and capacitance on the hand-release detection process, further reducing the error in the hand-release detection process, and improving the accuracy and reliability of the entire hand-release detection process. The added circuit structure is simple, the components used are easy to implement, the cost is low, the size is small, and it is easy to integrate, which is conducive to the simple implementation of the entire circuit.

[0071] As an optional embodiment, it also includes a detection resistor and a detection capacitor, the detection resistor and the detection capacitor are connected in series, and the first end of the series circuit is connected to the third output terminal of the release detection module 11, and the second end is grounded; the main processor is also used to obtain the environmental detection value corresponding to the release detection module 11 itself by controlling the third output terminal of the release detection module 11 to output an excitation signal, and to correct the detection result returned by the release detection module 11 based on the environmental detection value.

[0072] Considering that the measured value received by the hands-off detection module 11 is affected by the temperature of the hands-off detection module 11 itself, in order to solve this temperature influence, during the heating control stage, that is, when the heating circuit is turned on and the heating high-side drive module 1, the first isolation module 2, the second isolation module 3 and the heating low-side switch module 4 are all turned on, any other detection channel of the hands-off detection module 11 can be turned on for detection. This channel can be left floating or connected to a fixed capacitor or resistor to ground. That is, the third output terminal of the hands-off detection module 11 is connected to the circuit after the detection resistor and the detection capacitor are connected in series. At this time, the measured value obtained by the hands-off detection module 11 is also affected by the temperature of the hands-off detection module 11 itself. The measured value at this time can be used as the environmental detection value. In the subsequent hands-off detection process, the measured value of the steering wheel 6 is subtracted from the environmental detection value to eliminate the influence of the temperature of the hands-off detection module 11 itself on the detection result. This application does not impose specific limitations on the specific types and implementation methods of the detection resistors and capacitors. The switching process of the detection pins of the release detection module 11 can be controlled by the main processor or by its own preset program. The specific implementation method for obtaining environmental detection values ​​is not specifically limited here. Using a series detection resistor and capacitor to determine the environmental detection value is only one specific embodiment. Alternatively, the third output terminal of the release detection module 11 can be directly left floating, or a fixed load can be connected to the third output terminal of the release detection module 11. This fixed load is detected through the third output terminal of the release detection module to characterize the environmental value. This fixed load can be a single 100pF capacitor, a single 10K resistor, or a combination of capacitors and resistors connected in series or in parallel.

[0073] Specifically, the process of adding a hand-drop detection module 11 to measure using the third output terminal is to obtain the environmental detection value under the influence of the temperature of the hand-drop detection module 11 itself. This reduces the influence of the temperature of the hand-drop detection module 11 itself on the detection results in the subsequent hand-drop detection process, and improves the accuracy and reliability of the hand-drop detection results. The added circuit structure is simple, the components used are easy to implement, the cost is low, the size is small, and it is easy to integrate, which is conducive to the simple implementation of the entire circuit.

[0074] As an optional embodiment, it further includes a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4; the first end of the first resistor R1 is grounded, and the second end is connected to the first end of the second resistor R2, the second end of the heating high-side drive module 1, the first end of the first isolation module 2, and the first output end of the control module 5, respectively; the second end of the second resistor R2 is connected to the second end of the first isolation module 2 and the first end of the steering wheel 6, respectively; the first end of the third resistor R3 is grounded, and the second end is connected to the first end of the fourth resistor R4, the second end of the heating low-side switch module 4, the first end of the second isolation module 3, and the first output end of the control module 5, respectively; the second end of the fourth resistor R4 is connected to the second end of the second isolation module 3, the second end of the steering wheel 6, and the second output end of the control module 5, respectively.

[0075] Considering that the heating signal in the circuit can affect the release detection signal, a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4 are added. The input terminal of the first isolation module 2 is connected to pin 1 of the first resistor R1, and pin 2 of the first resistor R1 is grounded. The input terminal of the first isolation module 2 is connected to pin 1 of the second resistor R2, and the output terminal of the first isolation module 2 is connected to pin 2 of the second resistor R2. The output terminal of the second isolation module 3 is connected to pin 1 of the third resistor R3, and pin 2 of the third resistor R3 is grounded. The input terminal of the second isolation module 3 is connected to pin 1 of the fourth resistor R4, and the output terminal of the second isolation circuit is connected to pin 2 of the fourth resistor R4. The first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4 are used for circuit discharge to eliminate the influence of the heating signal on the detection circuit. This application does not specifically limit the specific types and implementation methods of the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. Please refer to [reference needed]. Figure 6 , Figure 7 and Figure 8 , Figure 6 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under the first circuit structure; Figure 7 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under a second circuit structure; Figure 8 A schematic diagram of the signal waveform of a combined hand-release detection and heating circuit provided by the present invention under a third circuit structure; Figure 6 The diagram shows the signal waveform when the circuit lacks the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. Figure 7 The diagram shows the signal waveforms when only the first resistor R1 and the third resistor R3 are present in the circuit. Figure 8The diagram shows the signal waveforms when the circuit includes the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4. The original signal represents the measured value of the resistance-capacitance signal of the steering wheel 6 received by the hands-free detection module 11. The detected value represents the final detection result obtained by the main processor after further filtering the measured value returned by the hands-free detection module 11. The heating control signal is the control signal of the main processor for each device in the heating circuit. The detection signal is significantly improved after adding the first resistor R1, the second resistor R2, the third resistor R3, and the fourth resistor R4.

[0076] Specifically, by adding a first resistor R1, a second resistor R2, a third resistor R3, and a fourth resistor R4, the influence of the heating signal in the circuit on the detection signal is avoided, thereby further improving the accuracy and reliability of the release detection results. The added circuit structure is simple, the components used are easy to implement, the cost is low, the size is small, and it is easy to integrate, which is conducive to the simple implementation of the entire circuit.

[0077] As a specific embodiment, please refer to Figure 9 , Figure 9 This invention provides a schematic diagram of the structure of a first isolation module 2. The first isolation module 2 can be composed of a PMOS transistor and its related peripheral circuits. The peripheral circuits can include resistors R12 and R13, and capacitor C7. Additionally, Q1 can be added as a driver device. One end of the driver device is connected to the main processor, and the other end is connected to the gate of the PMOS transistor. By receiving control signals from the main processor, it drives the gate of the PMOS transistor, thereby controlling the on / off state of the first isolation module 2. Resistor R12 can be a fixed resistor with a resistance of 10KΩ, and resistor R13 can be a fixed resistor with a resistance of 3.3KΩ. Please refer to... Figure 10 , Figure 10 This is a schematic diagram of another first isolation module provided by the present invention; VCC is the power supply, which can be directly implemented using the power supply BAT. The first isolation module 2 can also be implemented using an NMOS transistor and peripheral circuitry. When the first isolation module 2 uses an NMOS transistor, a boost converter chip Q2 needs to be added to generate a control signal higher than the power supply voltage to drive the NMOS transistor to conduct. One end of the boost converter chip Q2 is connected to the main processor through a resistor R15, and the other end is connected to the gate of the NMOS transistor. By receiving the control signal from the main processor, the gate of the NMOS transistor is driven, thereby controlling the conduction and cutoff of the first isolation module 2. At the same time, a resistor R14 needs to be added between the boost converter chip Q2 and the NMOS transistor, and the resistance value of the resistor R14 needs to be a large value to eliminate the influence of power supply voltage fluctuations on the detection signal; please refer to Figure 11 and Figure 12 , Figure 11A schematic diagram of the signal waveform of a first isolation module under a first circuit structure provided by the present invention; Figure 12 This invention provides a schematic diagram of the signal waveform of a first isolation module under a second circuit structure. Figure 11 The diagram shows the power supply voltage signal when resistor R14 is not set or the resistance value of resistor R14 is small, and the waveform diagram of the original signal detected by the hand-off detection module 11. Figure 12 The diagram shows the power supply voltage signal when the resistance of resistor R14 is relatively large, approximately 100KΩ, and the waveform of the original signal detected by the hand-off detection module 11. Please refer to... Figure 13 , Figure 13 This invention provides a schematic diagram of the structure of a second isolation module 3. The second isolation module 3 can be composed of an NMOS transistor and its related peripheral circuits. The gate of the NMOS transistor can be connected to the main processor via a resistor R16, which can be a fixed resistor with a resistance of 10KΩ. The second resistor R2 and the fourth resistor R4 can be fixed resistors of 10kΩ, the first resistor R1 and the third resistor R3 can be fixed resistors of 2kΩ, the first capacitor C1 and the second capacitor C2 can be 4.7uF capacitors, the third capacitor C3 can be a 220nF capacitor, and BAT can be powered by a 12V power supply.

[0078] Please refer to Figure 14 , Figure 14 This is a flowchart illustrating a control method for a combined hand-release detection and heating circuit provided by the present invention. To solve the above-mentioned technical problems, the present invention also provides a control method for a combined hand-release detection and heating circuit, applied to the aforementioned combined hand-release detection and heating circuit, the method comprising:

[0079] S11: When a detection signal is received, an excitation signal is output to the steering wheel 6 to detect whether the steering wheel 6 is in a hands-free state;

[0080] S12: At the same time as outputting the excitation signal, output a shielding signal to the first end of the first isolation module 2 and the first end of the second isolation module 3. The shielding signal is exactly the same as the excitation signal.

[0081] As an optional embodiment, before outputting the excitation signal, the method further includes:

[0082] When a detection signal is received, the heating high-side drive module 1 is disconnected, while the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 remain on.

[0083] After a preset time, the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 are turned off.

[0084] Specifically, when the steering wheel 6 needs to be heated, the heating high-side drive module 1, the first isolation module 2, the second isolation module 3 and the heating low-side switch module 4 are turned on for a period of time, while the hands-off detection module 11 is stopped from detecting.

[0085] When a hand-drop test is required, firstly, the high-side heating drive module 1 is turned off, while the first isolation module 2, the second isolation module 3, and the low-side heating switch module 4 remain on for a period of time to provide discharge time for the capacitors in the circuit. Then, the high-side heating drive module 1, the first isolation module 2, the second isolation module 3, and the low-side heating switch module 4 are all turned off for a period of time, and the hand-drop detection module 11 is activated for the first test. During the test, the second output terminal of the hand-drop detection module 11 needs to output an excitation signal, and simultaneously, the first output terminal needs to output a shielding signal that is exactly the same as the excitation signal output by the second output terminal. Since the excitation signal of the first test charges the capacitors in the circuit after the circuit discharges, the detection value may be incorrect, and the measurement value of the first test can be discarded. Then, the heating high-side drive module 1, the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 are kept closed for a period of time. The hands-off detection module 11 is then activated for the second detection, and the process is the same as the first detection. The measured value of the second detection is the valid measured value. After eliminating the influence of the temperature of the hands-off detection module 11 itself and compensating for the temperature of the steering wheel 6, a reliable value can be obtained. That is, the process of correcting using the temperature detection value and compensating for temperature using the NTC resistor can then be performed. This allows for the subsequent hands-off detection logic. Usually, a threshold value is set. If the value is higher than the threshold value, it is determined that the steering wheel 6 has been touched by a hand. If the value is lower than the threshold value, it is determined that the steering wheel 6 has not been touched by a hand. It is not difficult to understand that the process of hands-off detection of the steering wheel 6 is to obtain the resistance and capacitance measurement value of the steering wheel 6 through the excitation signal, and determine whether the hand has been touched based on the resistance and capacitance of the steering wheel 6, thereby completing the hands-off detection.

[0086] In practical applications, the operation is typically performed periodically, with a 100ms cycle. For the first 90ms, the heating high-side drive module 1, the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 are turned on, while the hand-release detection module 11 is turned off. From 90ms to 91ms, the heating high-side drive module 1 is turned off, while the first isolation module 2, the second isolation module 3, and the heating low-side switch module 4 remain on, and the hand-release detection module 11 remains off. From 91ms to 95ms, these modules are turned off, and the hand-release detection module 11 initiates its first detection. Due to the charging process after circuit discharge, the measurement value from the first detection is discarded. From 95ms to 100ms, these modules are turned off again, and the hand-release detection module 11 initiates its second detection. The measurement value from the second detection is the valid measurement value and can be used for hand-release detection. This application does not make any special limitations on how the control module 5 controls the heating process and the removal detection process. The periodic detection process is only one embodiment provided by this application.

[0087] For a description of the control method of the combined hand-release detection and heating circuit provided by the present invention, please refer to the above embodiment of the combined hand-release detection and heating circuit. The present invention will not be described again here.

[0088] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0089] Those skilled in the art will further recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of both. To clearly illustrate the interchangeability of hardware and software, the components and steps of the various examples have been generally described in terms of functionality in the foregoing description. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementations should not be considered beyond the scope of this invention.

[0090] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.

[0091] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A circuit combining hand-release detection and heating, characterized in that, The circuit, used in vehicle steering wheels, includes a heated high-side drive module, a first isolation module, a second isolation module, a heated low-side switch module, and a control module. The first terminal of the high-side heating drive module is connected to the power supply, and the second terminal is connected to the first terminal of the first isolation module and the first output terminal of the control module. The second terminal of the first isolation module is connected to the first terminal of the steering wheel. The first terminal of the low-side heating switch module is grounded, and the second terminal is connected to the first terminal of the second isolation module and the first output terminal of the control module. The second terminal of the second isolation module is connected to the second terminal of the steering wheel and the second output terminal of the control module. Both the first isolation module and the second isolation module include MOSFETs; the MOSFET in the first isolation module is a first MOSFET, and the MOSFET in the second isolation module is a second MOSFET. The control module is used to output an excitation signal to the steering wheel when a detection signal is received to detect whether the steering wheel is in a hands-free state. At the same time, it outputs a shielding signal to the first terminal of the first isolation module and the first terminal of the second isolation module. The shielding signal is exactly the same as the excitation signal to avoid charging and discharging of the junction capacitance of the MOSFETs in the two isolation modules. Specifically, the control module obtains the resistance and capacitance measurement value of the steering wheel through the excitation signal, and determines whether there is hand contact based on the resistance and capacitance of the steering wheel to complete the hands-free detection. The hands-free detection and heating combined circuit also includes a first resistor, a second resistor, a third resistor, and a fourth resistor; the first end of the first resistor is grounded, and the second end is connected to the first end of the second resistor, the second end of the heating high-side drive module, the first end of the first isolation module, and the first output end of the control module, respectively; the second end of the second resistor is connected to the second end of the first isolation module and the first end of the steering wheel, respectively; the first end of the third resistor is grounded, and the second end is connected to the first end of the fourth resistor, the second end of the heating low-side switch module, the first end of the second isolation module, and the first output end of the control module, respectively; the second end of the fourth resistor is connected to the second end of the second isolation module, the second end of the steering wheel, and the second output end of the control module, respectively.

2. The combined hand-release detection and heating circuit as described in claim 1, characterized in that, The control module includes a hands-off detection module and a main processor; the input terminal of the hands-off detection module is connected to the output terminal of the main processor, the first output terminal is connected to the second terminal of the heated low-side switch module, the first terminal of the second isolation module, the second terminal of the heated high-side drive module and the first terminal of the first isolation module respectively, and the second output terminal is connected to the second terminal of the steering wheel and the second terminal of the second isolation module respectively. The release detection module is used to output the excitation signal and the shielding signal based on the control of the main processor when a detection signal is received; The main processor is used to determine whether the steering wheel is in a hands-free state based on the detection signal returned by the hands-free detection module.

3. The combined hand-release detection and heating circuit as described in claim 2, characterized in that, The heating high-side drive module includes a driver, a first current-limiting resistor, a second current-limiting resistor, and a diode. The power port of the driver is connected to the power supply, the input port is connected to the first end of the first current-limiting resistor, the second end of the first current-limiting resistor is connected to the main processor, the ground port of the driver is connected to the first end of the second current-limiting resistor and the positive terminal of the diode, the second end of the second current-limiting resistor is grounded and connected to the negative terminal of the diode, and the output terminal of the driver serves as the output terminal of the heating high-side drive module.

4. The combined hand-release detection and heating circuit as described in claim 2, characterized in that, The heating low-side switch module includes an NMOS transistor and a third current-limiting resistor; the drain of the NMOS transistor is connected to the first terminal of the second MOS transistor and the first output terminal of the release detection module, the source is grounded, the gate is connected to the first terminal of the third current-limiting resistor, and the second terminal of the third current-limiting resistor is connected to the main processor.

5. The combined hand-release detection and heating circuit as described in claim 2, characterized in that, It also includes a first capacitor, a second capacitor, and a third capacitor; The first terminal of the first capacitor is connected to the first output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the high-side heating drive module and the first terminal of the first MOS transistor. The first terminal of the second capacitor is connected to the first output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the low-side heating switch module and the first terminal of the second MOS transistor. The first terminal of the third capacitor is connected to the second output terminal of the hands-off detection module, and the second terminal is connected to the second terminal of the second MOS transistor and the second terminal of the steering wheel.

6. The combined hand-release detection and heating circuit as described in claim 2, characterized in that, It also includes NTC resistors disposed at both ends of the heating coil of the steering wheel; the main processor is also used to determine the current temperature based on the NTC resistors, and to perform temperature compensation on the detection results returned by the hands-off detection module based on the current temperature.

7. The combined hand-release detection and heating circuit as described in claim 2, characterized in that, It also includes a detection resistor and a detection capacitor, wherein the detection resistor and the detection capacitor are connected in series, and the first end of the series circuit is connected to the third output terminal of the release detection module, and the second end is grounded; the main processor is also used to obtain the environmental detection value corresponding to the release detection module itself by controlling the third output terminal of the release detection module to output an excitation signal, and to correct the detection result returned by the release detection module based on the environmental detection value.

8. A control method for a combined hand-release detection and heating circuit, characterized in that, The method, applied to the combined hand-release detection and heating circuit as described in any one of claims 1 to 7, comprises: When a detection signal is received, an excitation signal is output to the steering wheel to detect whether the steering wheel is in a hands-free state; Simultaneously with outputting the excitation signal, a shielding signal is output to the first end of the first isolation module and the first end of the second isolation module. The shielding signal is exactly the same as the excitation signal.

9. The control method for the combined hand-release detection and heating circuit as described in claim 8, characterized in that, Before the output excitation signal, it also includes: When a detection signal is received, the heating high-side drive module is disconnected, while the first isolation module, the second isolation module, and the heating low-side switch module remain on. After a preset time, the first isolation module, the second isolation module, and the heating low-side switch module are turned off.

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