Heater with human body approaching detection function

Abstract

The utility model relates to a heater with a human body approaching detection function. The heater comprises a power supply, an electric heating module, a capacitance digital conversion circuit and a control module, the electric heating module is composed of a resistor which emits heat through electric energy, the resistor is connected with the power source through a switch, the resistor is installed in a steering wheel or a seat, the resistor is accompanied by at least one signal line installed in the steering wheel or the seat, the signal line is connected with a capacitance digital conversion circuit, and the capacitance digital conversion circuit is connected with the power source. The capacitance digital conversion circuit comprises a capacitance excitation signal circuit, the capacitance digital conversion circuit is connected with the control module, the control module outputs a logic signal for detecting that a human body is close to the steering wheel or the seat, and an active shielding layer used for forming equipotential with the signal line is arranged between the signal line and a framework of the steering wheel or the seat. The active shielding layer is respectively insulated from the framework and the signal line, and the capacitance digital conversion circuit is connected with the active shielding layer.

Description

Technical Field

[0001] This utility model relates to a heating device for automobiles, and more particularly to a heater with a human body proximity detection function. Background Technology

[0002] Currently, automotive steering wheel and seat heating technology is relatively mature. Our company applied for patent number 202020367398.3 in 2020, which cited several comparative documents, introducing the current state of this technology and our proposed solutions. In 2021, our company supplemented patents 202120130082.7 and 202120055136.8, introducing further improvement solutions based on problems discovered during practice, specifically:

[0003] Patent No. 202020367398.3 employs a resistive element multiplexing detection concept. However, the electronic switches controlling the resistive element are typically electronic devices made of various PN junctions, such as MOSFETs, which generate junction capacitance to ground. Due to the large heating current of the resistive element, the junction capacitance of the electronic switch becomes very large, leading to a short circuit in the measurement signal. To solve this problem, our company aimed to utilize the inductive effect of the resistive element itself to improve the inductive reactance and meet the sensitivity requirements. Patent No. 202020367398.3 proposes using high-frequency excitation to improve the inductive reactance. Patent No. 202120130082.7 presents another solution, which involves winding the resistive element around a magnetic material environment to improve the inductive reactance while simultaneously addressing the problems caused by high-frequency excitation. Patent No. 202120055136.8 presents yet another approach, abandoning the multiplexing concept and adding additional signal lines, which can also achieve the goal of reducing the excitation frequency requirement.

[0004] On the other hand, as technology advances, manufacturers are demanding more, requiring the differentiation of scenarios such as a little finger resting on the surface. Previous solutions could recognize a hand grasping the entire palm, but lacked sufficient sensitivity to distinguish a little finger from the palm due to its proximity to noise.

[0005] Therefore, it is necessary to study solutions that further improve detection sensitivity requirements, based on previous considerations of high frequency and cost, in order to meet the ever-growing market demands. Utility Model Content

[0006] To address the shortcomings of existing technologies, a heater with human proximity detection function is provided for use in a steering wheel or seat connected to a vehicle's power supply.

[0007] This utility model heater includes a power supply, an electric heating module, a capacitor-to-digital converter circuit, and a control module. The electric heating module consists of a resistive element that heats up through electrical energy. The resistive element is connected to the power supply via a switch and is installed in a steering wheel or seat. The resistive element is accompanied by at least one signal line installed in the steering wheel or seat. The signal line is connected to the capacitor-to-digital converter circuit, which includes a capacitor excitation signal circuit. The capacitor-to-digital converter circuit is connected to the control module. The control module outputs a logic signal that detects the proximity of a human body to the steering wheel or seat. An active shielding layer is provided between the signal line and the frame of the steering wheel or seat to form an equipotential with the signal line. The active shielding layer is insulated from both the frame and the signal line. The capacitor-to-digital converter circuit is connected to the active shielding layer.

[0008] The heater provided by this utility model also includes the following auxiliary solutions:

[0009] The signal line and the resistor are arranged in the same layer.

[0010] The signal lines and resistors are arranged in layers. The layer containing the resistors is located between the active shielding layer and the frame.

[0011] The resistor is heated based on PWM or DC.

[0012] The signal line is configured as a self-capacitance electrode accompanying the resistor; or, the signal line has at least two lines, and the at least two signal lines constitute mutual capacitance electrodes accompanying the resistor.

[0013] The active shielding layer is a conductive cloth.

[0014] The heater structure of this invention, while taking into account high-frequency issues and cost, further enhances sensitivity to meet the needs of distinguishing when a little finger is placed on it. Attached Figure Description

[0015] Figure 1 A front view of the steering wheel is given.

[0016] Figure 2 A diagram showing the steering wheel's partitions is provided.

[0017] Figure 3 A schematic diagram of the preferred layer structure of the steering wheel is given.

[0018] Figure 4 A schematic diagram of an active shielding layer structure is given between heating and detection.

[0019] Figure 5 A schematic diagram of the structure with the accompanying signal line as a self-capacitance electrode is given.

[0020] Figure 6 A schematic diagram of the structure with the accompanying signal line as the mutual capacitance electrode is given. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention.

[0022] Figures 1 to 2 A schematic diagram of the steering wheel 100 is shown. The upper surface of the steering wheel is divided into two areas, A and B, and the lower surface is divided into one area, C.

[0023] See Figures 3 to 6 The heater of this invention includes a power supply, an electric heating module, a capacitor-to-digital converter circuit, and a control module. The electric heating module, i.e., the heating layer 130, is mounted on the frame 110 of the steering wheel. The heating layer 130 is separated from the frame 110 by a primary foam layer 120, which serves as a buffer and heat insulation layer. The heating layer 130 is composed of a resistor 131 that heats up through electrical energy. The resistor 131 is installed in the steering wheel or seat. To simplify the structure, the resistor 131 is a long wire that wraps around the frame 110 as a whole. The resistor 131 is connected to the power supply via an electronic switch such as a MOSFET. The power supply can be the heater's built-in power supply or the vehicle's own power system.

[0024] The resistor 131 is accompanied by at least one signal wire installed in the steering wheel or seat. The signal wire is located in the detection layer 150. In one option, the signal wire and the resistor 131 are arranged in the same layer to simplify the structure and reduce the thickness. In this case, the resistor 131 is preferably heated by DC to ensure that detection and heating do not interfere with each other. When they are in the same layer, PWM heating can interfere with capacitance detection. In another option, the signal wire and the resistor 131 are arranged in separate layers to reduce the interference of heating on detection. Preferably, see [reference needed]. Figure 3 The heating layer 130, where the resistor 131 is located, is situated between the active shielding layer 140 and the frame 110. The detection layer 150 is separated from the heating layer 130 by the active shielding layer 140, which further avoids the influence of heating on the detection. In the layered scheme, the resistor 131 is heated based on PWM or DC without restriction.

[0025] See Figure 5 , Figure 6The detection layer 150 is equipped with signal lines 151, 152, and 153. Signal line 151 is wound in area A, signal line 152 in area B, and signal line 153 in area C, achieving zoned detection. This distinguishes between the proximity of a driver's belly to the steering wheel and the proximity of their hands to the steering wheel, especially for drivers with large bellies. Similarly, monitoring the hand grip on the steering wheel and the posture of the driver's buttocks and back after sitting down provides more information for the vehicle's warning system or intelligent airbag control system. In one alternative solution, see [link to alternative solution]. Figure 5 Signal lines 151, 152, and 153 can all be configured as single lines, serving as self-capacitance electrodes for the accompanying resistive element. In another optional scheme, see... Figure 6 Signal lines 151, 152, and 153 are each accompanied by at least two wires, which serve as mutual capacitance electrodes of the accompanying resistor. The signal lines are connected to a capacitance-to-digital converter (CDC), which collects self-capacitance and / or mutual capacitance data. Self-capacitance detection distance is relatively larger than mutual capacitance, while mutual capacitance is less susceptible to environmental influences such as temperature and humidity. The two are combined according to engineering requirements.

[0026] The capacitor-to-digital converter circuit includes a capacitor excitation signal circuit. In one optional embodiment, the capacitor excitation signal circuit generates a square wave excitation signal with a frequency of 600kHz. This frequency range offers three advantages: 1. It conforms to the fundamental frequency range of the control module, saving spread spectrum resources and achieving higher frequency accuracy; 2. It has minimal impact on the inductance formed by the long-wire-wound resistor 131; 3. The parasitic capacitance inevitably generated by the length of the resistor 131 wire is provided by this frequency range, allowing sufficient detection time. The capacitor-to-digital converter circuit is connected to the control module, which outputs a logic signal to detect the proximity of a human body to the steering wheel or seat.

[0027] In this embodiment, the core, see [link to relevant documentation] Figure 3 , Figure 4 An active shielding layer 140 is provided between the detection layer 150 where the signal line is located and the frame 110 of the steering wheel or seat. The active shielding layer 140 can be implemented using conductive cloth, metallized fiber fabric, metal wire braid, or conductive film, and is insulated from the frame and the signal line respectively. The capacitor-to-digital conversion circuit is connected to the active shielding layer 140 to form an equipotential shield with the signal line.

[0028] The active shielding isolates the signal line from the internal frame 110. Since the frame 110 is grounded, without the active shielding layer 140, the signal line would be extremely close to the ground of the frame 110. For a hand, which is also grounded, the distance between the hand and the signal line is roughly the same as the distance between the frame and the signal line. This large ground area would attract the electric field lines from the signal line into the frame 110, making it difficult to detect touches, such as a little finger or two fingers resting on the steering wheel or seat. By adding a conductive cloth shielding layer 140 between the frame 110 and the signal line, connected to the active shielding line, the absorption of the electric field from the signal line by the frame 110 is isolated, enhancing detection sensitivity. Because the heater structure still uses accompanying wire winding, it has a cost advantage. The excitation signal does not need to rely on high-frequency boosting of the inductive impedance against the junction capacitance, avoiding various problems arising from high frequencies. Ultimately, this achieves a balance between high-frequency issues and cost, further enhancing sensitivity and meeting the requirements for distinguishing when a little finger is resting on the surface.

[0029] In the steering wheel of this embodiment, after the detection layer 160 is wrapped with a secondary foaming layer 160, the outer skin 170 is then wrapped on top of it to achieve a good feel.

[0030] The heater structure of this embodiment can also be installed on the seat. Similarly, the seat can be divided into multiple areas, each equipped with a heater that detects human proximity. The detection method for the heater on the seat is the same as that for the heater on the steering wheel, so it will not be described again.

[0031] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit the scope of protection of this utility model. Although this utility model has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this utility model without departing from the essence and scope of the technical solutions of this utility model.

Claims

1. A heater with a human proximity detection function, used for a steering wheel or seat connected to a vehicle power source, comprising a power source, an electric heating module, a capacitor-to-digital converter circuit, and a control module; the electric heating module consists of a resistor that heats up through electrical energy, the resistor being connected to the power source via a switch, the resistor being installed in the steering wheel or seat, the resistor being accompanied by at least one signal line installed in the steering wheel or seat, the signal line being connected to the capacitor-to-digital converter circuit, the capacitor-to-digital converter circuit including a capacitor excitation signal circuit, the capacitor-to-digital converter circuit being connected to the control module, the control module outputting a logic signal detecting the proximity of a human body to the steering wheel or seat, characterized in that: An active shielding layer is provided between the signal line and the frame of the steering wheel or seat to form an equipotential with the signal line. The active shielding layer is insulated from both the frame and the signal line. The capacitor-to-digital converter circuit is connected to the active shielding layer.

2. The heater of claim 1, wherein: The signal lines are arranged in the same layer as the resistors.

3. The heater of claim 1, wherein: The signal lines and resistors are arranged in layers.

4. The heater according to claim 3, characterized in that: The layer containing the resistor is located between the active shielding layer and the skeleton.

5. The heater of claim 2 or 3, wherein: The resistor is heated based on PWM or DC.

6. The heater according to claim 1, characterized in that: The signal line is configured as a self-capacitance electrode accompanying the resistive element; Alternatively, the signal lines may have at least two lines, which together form mutual capacitance electrodes accompanying the resistive element.

7. The heater of claim 1, wherein: The active shielding layer is a conductive cloth, a metallized fiber fabric, a metal wire braided layer, or a conductive film.

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