STEERING WHEEL UNIT

Abstract

A steering wheel unit (100) comprising: a steering wheel (110) including a rim (110A), spokes (110B) and a plurality of electrodes (113, 113A to 113D) spaced apart and covering the rim (110A); a mode switch (131) configured to switch between a self-capacitance sensing mode and a mutual capacitance sensing mode for the plurality of electrodes (113, 113A to 113D); a capacitance meter (120) configured to measure a respective electrostatic capacitance at each of the plurality of electrodes (113, 113A to 113D); and a contact determiner (132) configured to determine, on the basis of the electrostatic capacitances measured by the capacitance meter (120), whether an operator's hand is in contact with the steering wheel (110) or not,wherein the mode switch (131) in the mutual capacitance detection mode selects a drive electrode from the plurality of electrodes (113, 113A to 113D) and selects an electrode adjacent to the selected drive electrode as a detection electrode, wherein in the self-capacitance detection mode set by the mode switch (131), when any electrostatic capacitance measured by the capacitance meter (120) is equal to or greater than a first threshold, the contact determiner (132) determines that the operator's hand is in contact with the ring (110A) in a position that overlaps at least one of the plurality of electrodes (113, 113A to 113D), wherein, when any electrostatic capacitance measured by the capacitance meter (120) is equal to or greater than a second threshold and less than the first threshold, the second threshold being less than the first threshold,The contact determiner (132) causes the mode switch (131) to switch from the self-capacitance detection mode to the mutual capacitance detection mode, and wherein, after switching, if an electrostatic capacitance newly measured by the capacitance meter (120) in the mutual capacitance detection mode is equal to or greater than a third threshold value, the control unit determines that the operator's hand is in contact with the ring (110A) at a position that overlaps a distance between the electrodes (113, 113A to 113D).

Description

TECHNICAL FIELDThe present disclosure relates to a steering wheel unit.BACKGROUNDA steering wheel unit of a vehicle in which a sensor detects whether a human body is in contact with a steering wheel is known. Such a steering wheel unit includes electrostatic capacity sensors disposed in the steering wheel to detect a magnitude of electrostatic capacity associated with contact of a human body with the steering wheel, wherein the outer peripheral portion of the rim of the steering wheel is provided with a detection area for detecting whether a human body is in contact with the steering wheel with the electrostatic capacity sensors, and the rim is further provided with a dead zone in which contact of a human body with the steering wheel is not detected, wherein the detection area and the dead zone are respectively formed in a left portion of the rim, which is a relatively left portion when the steering wheel is in a neutral position, and a right portion opposing the left portion, with a central portion of the rim interposed therebetween (see Patent Document 1).RELATED DOCUMENTSSPECIFICATIONPatent Document 1: Japanese Unexamined Patent Publication No. 2019-23009SUMMARY OF THE INVENTIONOBJECTS TO BE SOLVED BY THE INVENTIONIn a conventional steering wheel unit, the touch of the hand is not detected when the position of the hand on the steering wheel is in the dead zone. The electrostatic capacity sensor is a type of sensor configured to detect the self-capacitance. In other words, although a dead zone is provided in the conventional steering wheel unit to avoid erroneous detection or erroneous operation in hand-on-hand detection using self-capacitance, hand touch in the dead zone cannot be detected.Since a steering wheel unit necessarily has an area where a sensor cannot be disposed for design reasons, it is desirable to provide a steering wheel unit capable of determining where an operator's hand is contacted even in a dead zone where no sensor is present.According to an embodiment of the present disclosure, a steering wheel unit includes: a steering wheel including a rim, spokes, and a plurality of electrodes spaced apart from each other and covering the rim; a mode switcher configured to switch between a self-capacitance detection mode and a mutual capacitance detection mode for the plurality of electrodes; a capacitance meter configured to measure a respective electrostatic capacitance at each of the plurality of electrodes; and a contact determiner configured to determine whether or not a hand of an operator is in contact with the steering wheel based on the electrostatic capacitances measured by the capacitance meter. The mode switcher selects one driving electrode from the plurality of electrodes in the mutual capacitance detection mode, and selects one electrode adjacent to the selected driving electrode as the detection electrode. In the self-capacitance detection mode set by the mode switcher, when any one of the electrostatic capacitances measured by the capacitance meter is equal to or greater than a first threshold value, the contact determiner determines that the operator's hand contacts the rim at a position overlapping at least one of the plurality of electrodes. When the arbitrary electrostatic capacitance measured by the capacitance meter is equal to or greater than a second threshold value and less than the first threshold value, the second threshold value being less than the first threshold value, the contact determiner causes the mode switcher to switch the self-capacitance detection mode to the mutual capacitance detection mode. After the switching, when an electrostatic capacitance newly measured by the capacitance meter in the mutual capacitance detection mode is equal to or greater than a third threshold, the control unit determines that the operator's hand contacts the rim at a position overlapping a distance between the electrodes.EFFECTS OF THE INVENTIONA steering wheel unit may be provided that may determine whether an operator's hand contacts a dead zone in which no sensor is present in a rim of a steering wheel.BRIEF DESCRIPTION OF THE DRAWINGSFIG. 1 is a diagram showing an example of a steering wheel included in a steering wheel unit according to an embodiment. FIG. 2 is a diagram showing an example of a configuration of a cross section taken along the line A-A in FIG. 1. FIG. 3 is a diagram showing an example of the configuration of a steering wheel unit according to this embodiment. FIG. 4 is a flowchart showing an example of processing by a hands-off detection electronic control unit (HODECU). FIG. 5A is a diagram showing a threshold value Th 1 used by a contact determiner. FIG. 5B is a diagram showing a threshold value Th 2 used by the contact determiner. FIG. 6 is a diagram showing a threshold value Th 4 used by the contact determiner. FIG. 7A is a diagram showing a threshold value Th 3 used by a contact determiner. FIG. 7B is a diagram illustrating a threshold Th 5 used by the contact determiner. FIG. 8 is a diagram showing a configuration of sensors according to a modified example of the embodiment.DESCRIPTION OF THE EMBODIMENTSAn embodiment using a steering wheel unit according to the present disclosure will be described below.<>FIG. 1 is a diagram showing an example of a steering wheel 110 including a steering wheel unit 100, according to an embodiment. The steering wheel 110 includes a rim 110A, spokes 110B, a hub 110C, a steering core 111, an outer panel 112, and sensors 113A, 113B, 113C, and 113D. The sensors 113A to 113D are examples of a plurality of electrodes. In the following description, the configuration of the steering wheel 110 will be described with respect to the configuration when the steering wheel 110 is mounted on the vehicle and is in a neutral state unless otherwise specified. Further, a driver seat side of the steering wheel 110 is referred to as "front side", and the vehicle front side of the steering wheel 110 is referred to as "rear side".The steering wheel 110 is shown on the left side of FIG. 1. In the middle of FIG. 1, the steering wheel 110 is shown in an exploded drawing. In the middle of FIG. 1, the exterior trim 112 is omitted to make the arrangement of the sensors 113A to 113D visible. On the right side of FIG. 1, the rim 110A of the steering wheel 110 is illustrated in a partially enlarged shape. A portion of the rim 110A is shown in a straight form on the right side of FIG. 1.Although two spokes 110B extending leftward and rightward from the hub 110C at the center of the steering wheel 110 are illustrated in FIG. 1, the number of the spokes 110B may be any. Further, the rim 110A may not be circular, but may be rectangular, D-shaped, or the like, and may not be circular at all. The steering core 111 has a similar shape to the steering wheel 110 and includes a rim and spokes. The rim and spokes of the steering core 111 correspond to the rim 110A and the spokes 110B of the steering wheel 110.The outer cowl 112 is a member covering the rim of the steering core 111, and is a part with which the hands of the operator (drive) of the vehicle directly contact. The outer panel 112 is made of, for example, natural leather, artificial leather, or resin.The outer shroud 112 is integrated with, for example, the sensors 113A to 113D and covers the rim of the steering core 111, the sensors 113A to 113D being disposed between the outer shroud 112 and the rim of the steering core 111. The rim of the steering core 111 covered with the outer shroud 112 into which the sensors 113A to 113D are integrated is the rim 110A of the steering wheel 110. By attaching a decorative member or the like made of synthetic resin to the spokes of the steering core 111, the spokes of the steering core 111 become the spokes 110B of the steering wheel 110.The outer cowl 112 integrated with the sensors 113A to 113D is a sheet-like member before being fixed to the rim of the steering core 111. The outer panel 112 integrated with the sensors 113A to 113D and covering the rim of the steering core 111 is sewn, and thereby a seam 112A is formed. The seam 112A is formed along the circumferential direction of the rim 110A of the steering wheel 110. The seam 112A is formed on, for example, the inner circumferential side, the inner circumferential side, and the outer circumferential side, or the outer circumferential side of the rim 110A of the steering wheel 110.The sensors 113A to 113D are electrodes formed of a conductor and are provided to detect whether the operator's hand is in contact with the steering wheel 110. To the sensors 113A to 113D, a cable 114 connected to a hands-off detection (HODECU) electronic control unit or the like is connected. As the sensors 113A to 113D, for example, an electrode obtained by applying a silver paste to a plastic film or the like, or an electrode obtained by forming an aluminum foil, a copper foil or the like on a plastic film or the like can be used.For example, sensor 113A is located at the front of the right half of rim 110A, and sensor 113B is located at the front of the left half of rim 110A, for example. For example, sensor 113C is located at the back of the right half of rim 110A, and sensor 113D is located at the back of the left half of rim 110A, for example.The electrostatic capacitance between the sensors 113A to 113D and the operator's hand changes depending on whether the operator's hand contacts the rim 110A of the steering wheel 110. The electrostatic capacity between the sensors 113A to 113D and the operator's hand is different when the operator's hand grasps the rim 110A of the steering wheel 110 and when the operator's hand only slightly touches the rim 110A. For example, the electrostatic capacitance when the operator grasps the rim 110A is greater than the electrostatic capacitance when the operator lightly touches the rim 110A.When the outer panel 112 provided with the sensors 113A to 113D is attached to the rim of the steering wheel core 111, the sensors 113A to 113D are not located in the seam 112A; therefore, the electrostatic capacity between the sensors 113A to 113D and the operator's hand is different when the operator's hand is contacted with the seam 112A of the rim 110A of the steering wheel 110 and when the operator's hand is contacted with a part other than the seam 112A of the rim 110A (a part overlapping at least one of the sensors 113A to 113D). The range in which the sensors 113A to 113D are not present, for example, the seam 112A is an example of a position overlapping the distance between the plurality of electrodes in the rim 110A of the steering wheel 110.Hereinafter, a case where a portion where the sensors 113A to 113D are not present in the rim 110A of the steering wheel 110 is the seam 112A will be described, but there may also be a portion where the sensors 113A to 113D are present only in the seam 112A. For example, when the exterior panel 112 is not sewn but bonded, a portion shown as seam 112A would be a joint of the exterior panel 112, and there may be a portion where the sensors 113A to 113D are not present in the joint.In another example, when the decorative member of the spokes 110B of the steering wheel 110 is provided to extend to the rim 110A, the outer panel 112 provided with the sensors 113A to 113D may not be attached to a part of the rim 110A of the steering wheel 110. Therefore, even when no seam 112A is present, there may be a range in which the sensors 113A to 113D are not present in the rim 110A of the steering wheel 110.When the seam 112A is not present on the outer circumferential side of the rim 110A, the distance between the sensor 113A on the front side of the right half of the rim 110A and the sensor 113C on the rear side of the right half of the rim 110A is a portion where no sensor is present. When the seam 112A is not present on the outer circumferential side of the rim 110A, the distance between the sensor 113B on the front side of the left half of the rim 110A and the sensor 113D on the rear side of the left half of the rim 110A is a portion where no sensor is present. Further, the distance between the sensors 113A and 113B on the front side of the rim 110A and the distance between the sensors 113C and 113D on the rear side of the rim 110A are also portions where no sensor is present.The steering wheel unit 100 of the present embodiment can perform the detection of the contact of the operator's hand with the rim 110A of the steering wheel 110 even when the operator's hand is in contact with a part of the rim 110A of the steering wheel 110 where the sensors 113A to 113D are not present, such as the seam 112A. The details will be described below.< Of Method for Detecting Electrostatic Capacitance in Steering Wheel Unit 100 of Embodiment>FIG. 2 is a diagram showing an example of a configuration of the cross section taken along the line A-A in FIG. 1. Herein, a method for detecting an electrostatic capacitance in the steering wheel unit 100 of the embodiment will be described with reference to FIG. 2. In FIG. 2, the operator's hand H and the outer panel 112 and the seam 112A are shown separately from each other to represent an electrostatic capacitance between the operator's hand H and the sensor 113A and 113C with a capacitor symbol, however, it is assumed that the hand is in contact with the outer panel 112 and the seam 112A, respectively.For example, as illustrated in FIG. 2, the seam 112A is provided on the inner circumferential side (the left side in FIG. 2 ) of the rim 110A of the steering wheel 110, and a dead zone in which no sensor is present is provided on the outer circumferential side (the right side in FIG. 2 ). The seam 112A on the inner circumferential side and the dead zone on the outer circumferential side in which no sensor is present correspond to the positions of the sensors 113A and 113C. The right half of the steering wheel 110 in which the sensors 113A and 113C are provided will be described here; however, the following descriptions apply to the left half in which the sensors 113B and 113D are provided, the front side in which the sensors 113A and 113B are provided, and the rear side in which the sensors 113C and 113D are provided.In a self-capacitance detection mode, the steering wheel unit 100 selects the sensor 113A or 113C as a detection electrode and measures an electrostatic capacitance between the detection electrode and the ground. In the self-capacitance detection mode, the detection electrode also functions as a driving electrode. In the self-capacitance detection mode, in the case where the steering wheel unit 100 can measure a certain large electrostatic capacitance, the steering wheel unit 100 determines that the hand H contacts the steering wheel 110 at a position overlapping the sensor 113A or 113C.When the steering wheel unit 100 cannot measure electrostatic capacitance of a certain magnitude in the self-capacitance detection mode with the sensor 113A or 113C, the steering wheel unit 100 switches the detection mode to a mutual capacitance detection mode. Then, the steering wheel unit 100 selects one of the sensors 113A and 113C as a driving electrode, selects the electrode adjacent to the driving electrode (the other of the sensors 113A and 113C) as a sensing electrode, and measures an electrostatic capacitance between the driving electrode and the sensing electrode. In the mutual capacitance detection mode, in the case where the steering wheel unit 100 can measure an electrostatic capacitance of a certain magnitude, the steering wheel unit 100 determines that the hand H contacts the steering wheel 110 at a position overlapping the seam 112A or the dead zone in which no sensor is present.<Konfiguration of Steering Wheel Unit 100>FIG. 3 is a diagram showing an example of a configuration of the steering wheel unit 100 according to the embodiment. The steering wheel unit 100 includes the steering wheel 110, a capacitance meter 120, and the HODCU 130. The HODECU 130 includes a mode switcher 131 and a contact determiner 132. The HODECU 130 is connected to an advanced driver-assistance system electronic control unit (ADASCU) 200. The ADASECU 200 is, for example, a device configured for the control unit of a system that provides advanced driving assistance, such as an automatic driving system. The automatic driving system may be, for example, level 3 or higher of automatic driving levels 0 to 5 defined by the Society of Automotive Engineers of Japan, Inc. (JSAE).In FIG. 3, only the sensors 113A to 113D and the seam 112A of the steering wheel 110 are illustrated. The seam 112A is a dead zone in which the sensors 113A to 113D are not present.Capacitance meter 120 is a circuit provided between sensors 113A to 113D and contact determiner 132 of HODECU 130, and is configured to convert analog outputs from sensors 113A to 113D into digital outputs, and output the digital outputs to contact determiner 132. An electrostatic capacitance digitally converted and output by the capacitance meter 120 is a digitally converted value (raw value) before the HODCU 130 calculates a difference value (ΔAD) representing a difference between a measured electrostatic capacitance and a predetermined reference value.The HODCU 130 is implemented by a computer including a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), an input / output interface, an internal bus, and the like. The mode switcher 131 and the contact determiner 132 are function blocks provided by a program executed by the HODECU 130.The mode switcher 131 selects the sensors 113A to 113D as a driving electrode or a sensing electrode, and sets a mode by switching between the self-capacitance sensing mode and the mutual-capacitance sensing mode. In the self-capacitance detection mode, the mode switcher 131 selects each of the sensors 113A to 113D as a detection electrode in time division, and an electrostatic capacitance is measured by the capacitance meter 120 as a self capacitance. In this case, the remaining three sensors not used for detecting an electrostatic capacitance may be used as a shield.The sensors 113A to 113D may be simultaneously selected as a detection electrode, and the electrostatic capacitances may be measured as self capacitance by the capacitance meter 120. In this case, no shield is set.Here, shielding means that a sensor not selected as a detection electrode for detecting the electrostatic capacitance is brought to an arbitrary potential or to ground (0 V).In the mutual capacitance detection mode, the mode switcher 131 selects one of the sensors 113A to 113D as a driving electrode and the sensor adjacent to the selected driving electrode as a detecting electrode. The sensors 113A to 113D are adjacent to each other in a direction connecting the front and the back of the steering wheel 110 or in the circumferential direction of the steering wheel 110. For this reason, the mode switcher 131 may select, for example, any one of the sensors 113A to 113D as a driving electrode and select the sensor adjacent to the selected driving electrode as a sensing electrode. In the mutual capacitance detection mode, an electrostatic capacitance between the driving electrode and the detection electrode is measured as the mutual capacitance by the capacitance meter 120.The contact determiner 132 determines whether the operator's hand H is in contact with the rim 110A of the steering wheel 110 from an electrostatic capacitance measured by the capacitance meter 120. The details of the processing performed by the contact determiner 132 will be described with reference to the flowchart in FIG. 4.<Flussdiagramm Flow Diagram>FIG. 4 is a flowchart showing an example of processing performed by the HODECU 130.When the processing is started, the contact determiner 132 causes the mode switcher 131 to set the self-capacitance detection mode, and detects electrostatic capacitances sequentially measured in all the sensors 113A to 113D in time division by the capacitance meter 120 (step S 1). In step S 1, the contact determiner 132 determines a digitally converted value (raw value) representing the electrostatic capacitance detected by the capacitance meter 120.In step S 1, the mode switcher 131 may operate three sensors other than the sensor that detects an electrostatic capacitance as a shield. The contact determiner 132 may cause the mode switcher 131 to perform such processing. By operating the three sensors other than the electrostatic capacity detecting sensor as a shield, it is possible to suppress the influence of the mass or the like around the electrostatic capacity detecting sensor and stably detect an electrostatic capacity.The contact determiner 132 calculates an electrostatic capacity as a difference value (ΔAD) by subtracting a predetermined reference value from the digitally converted value (raw value), and determines whether or not there is an electrostatic capacity equal to or greater than a threshold value Th 2 among the detected electrostatic capacities (step S 2). The threshold Th 2 is an example of a second threshold, and is set to an electrostatic capacitance with which it can be determined in the self-capacitance detection mode that the hand H contacts the rim 110A of the steering wheel 110 at any location including the seam 112A and the dead zone in which no sensor is present. Even when the hand H contacts the rim 110A of the steering wheel 110 in the dead zone, the electrostatic capacity of at least one of the sensors 113A to 113D increases to some extent. For this reason, the contact determiner 132 determines, based on the threshold Th 2, the detection of the contact of the hand H with the rim 110A of the steering wheel 110 at any location including the seam 112A and the dead zone where no sensor is present.When the contact determiner 132 determines that there is an electrostatic capacity equal to or greater than the threshold Th 2 among the detected electrostatic capacities (Yes in step S 2), the contact determiner 132 determines whether the electrostatic capacity (ΔAD) is equal to or greater than the threshold Th 1 (step S 3). The threshold Th 1 is an example of a first threshold, and is set to an electrostatic capacity with which it can be determined that the hand H contacts the rim 110A of the steering wheel 110 at a position overlapping at least one of the sensors 113A to 113D. Here, the position of the rim 110A overlapping at least one of the sensors 113A to 113D is a region of the rim 110A other than the seam 112A and the dead zone in which no sensor is present.Specifically, the threshold Th 1 is set to a value at which detection of firmly gripping the rim 110A with the hand H is expected at a portion other than the seam 112A or the dead zone where no sensor is present. In a state where the hand H firmly grips the seam 112A of the rim 110A or an area other than the dead zone where no sensor is present, a very large electrostatic capacity is achieved. In order to confirm that the hand H is in contact with the steering wheel 110, the processing in step S 3 is provided.Moreover, by determining whether the hand H contacts the rim 110A at a position other than the seam 112A and the dead zone in which no sensor is present, after step S 2 in which it is determined that the hand H contacts the rim 110A of the steering wheel 110 at any part including the seam 112A and the dead zone in which no sensor is present (Yes in step S 2), it can be made possible to distinguish between the case where the hand H contacts the seam 112A or the dead zone in which no sensor is present and the case where the hand H contacts another part of the rim 110A.When the contact determiner 132 determines that the electrostatic capacity is equal to or greater than the threshold Th 1 (Yes in step S 3), the contact determiner 132 determines that the hand H is in contact with the rim 110A of the steering wheel 110 (step S 4). When the contact determiner 132 has completed the processing in step S 4, the HODECU 130 transmits the determination result to the ADASECU 200 and returns to the beginning of the processing.When the contact determiner 132 determines that the electrostatic capacity is not equal to or greater than the threshold Th 1 in step S 3 (No in step S 3), the contact determiner 132 causes the mode switcher 131 to switch the mode to the mutual capacity detection mode (step S 5). The mode switcher 131 selects, as the driving electrode, the sensor that has detected an electrostatic capacity equal to or greater than the threshold Th 2 in step S 2, from among the sensors 113A to 113D, and selects, as the detecting electrode, the sensor adjacent to the sensor selected as the driving electrode.For example, when the sensor 113A is selected as a driving electrode, the sensor 113C adjacent to the sensor 113A may be selected with the rim of the steering core 111 interposed therebetween or the sensor 113B located on the opposite side of the rim of the steering core 111 may be selected as a sensing electrode. When the sensor 113C is selected as a driving electrode, the sensor 113A adjacent to the sensor 113C may be selected with the rim of the steering core 111 interposed therebetween or the sensor 113D located on the opposite side of the rim of the steering core 111 may be selected as a detection electrode. Similarly, in the case where the sensor 113B is selected as a driving electrode, the sensor 113D adjacent to the sensor 113B may be selected with the rim of the steering core 111 interposed therebetween, or the sensor 113A located on the opposite side of the rim of the steering core 111 may be selected as a detection electrode. When the sensor 113D is selected as a driving electrode, the sensor 113B adjacent to the sensor 113D with the rim of the steering core 111 interposed therebetween or the sensor 113C located on the opposite side of the rim of the steering core 111 may be selected as a detection electrode.The processing proceeds to step S 5 when it is determined in step S 2 that the electrostatic capacity is equal to or greater than the threshold Th 2 and it is determined in step S 3 that the electrostatic capacity is less than the threshold Th 1, at the same time when the hand H is not in contact with the rim 110A of the steering wheel 110 in a range overlapping the sensors 113A to 113D but in contact with, for example, the seam 112A or the dead zone in which no sensor is present, while a certain large electrostatic capacity is detected.The contact determiner 132 determines an electrostatic capacitance between the driving electrode and the sensing electrode using the driving electrode and the sensing electrode selected in step S 5 (step S 6).In step S 5, instead of selecting the sensor that has detected the electrostatic capacity equal to or greater than the threshold value Th 2 as the driving electrode in step S 2, each of the sensors 113A to 113D may be selected as the driving electrode, and a driving electrode and a detection electrode may be selected in a round trip method. In this case, the process of selecting a driving electrode and a sensing electrode in step S 5 and the process of sensing an electrostatic capacitance between the driving electrode and the sensing electrode in step S 6 may be repeatedly performed.Here, the selection of a driving electrode and a sensing electrode in a round trip method means measurement of an electrostatic capacitance (mutual capacitance) between the driving electrode and the sensing electrode in the case where all the sensors are selected as the driving electrode by sequentially selecting all the sensors as the driving electrode and selecting the sensor adjacent to the selected driving electrode as the sensing electrode.The contact determiner 132 determines whether the detected electrostatic capacity is equal to or greater than a threshold Th 3 (step S 7). The threshold Th 3 is an example of a third threshold, and is set to an electrostatic capacity with which it can be determined whether the hand H contacts the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present in the mutual capacity detection mode.When the contact determiner 132 determines that the detected electrostatic capacity is equal to or greater than the threshold Th 3 (Yes in step S 7), the contact determiner 132 determines that the hand H is in contact with the rim 110A of the steering wheel 110 (step S 4). In the case that the hand H contacts the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present, the processing proceeds to step S 4 via step S 7.When the contact determiner 132 determines that the detected electrostatic capacity is not equal to or greater than the threshold Th 3 in step S 7 (No in step S 7), the contact determiner 132 determines that the hand H does not contact the rim 110A of the steering wheel 110 (step S 8). For example, in the case where the hand H is in contact with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone where no sensor is present at the time of detecting the electrostatic capacitance in step S 1, but the hand H is no longer in contact with the rim 110A of the steering wheel 110 at the time of detecting the electrostatic capacitance in step S 6, the processing proceeds from step S 7 to step S 8. When the contact determiner 132 completes the processing in step S 8, the HODECU 130 transmits the determination result to the ADASECU 200 and returns to the beginning of the processing.When it is determined in step S 2 that there is no electrostatic capacity equal to or greater than the threshold Th 2 among the calculated electrostatic capacities (ΔAD), the contact determiner 132 determines whether there is an electrostatic capacity equal to or greater than a threshold Th 4 among the electrostatic capacities (raw values) of the sensors 113A to 113D acquired in step S 1 (step S 9). The threshold Th 4 is an example of a fourth threshold. An initial value is a value output from each of the sensors 113A to 113D in a state where the hand H is not in contact with the steering wheel 110. Such an initial value is a value determined depending on a configuration of each of the sensors 113A to 113D, and may be stored in, for example, an internal memory of the HODECU 130. To set the threshold Th 4, the sensitivity for determining whether the hand H is in contact with the steering wheel 110 may be adjusted depending on a degree of increase from the output value.The threshold Th 4 is set to an electrostatic capacity with which it can be determined in the self-capacity detection mode that the hand H is in light contact with the rim 110A of the steering wheel 110 at any location including the seam 112A and the dead zone in which no sensor is present. In step S 9, it is determined which sensor (one of the sensors 113A to 113D) the hand H approaches when the hand H is in slight contact with any part of the rim 110A by checking an increase in electrostatic capacitances (raw values) of the sensors 113A to 113D acquired in step S 1. When the hand H slightly touches the rim 110A or is near the rim 110A of the steering wheel 110, it is possible to restrict the sensors to a sensor in step S 9.When the contact determiner 132 determines that the electrostatic capacitances of the sensors 113A to 113D include an electrostatic capacitance equal to or greater than the threshold Th 4 (Yes in step S 9), the contact determiner 132 causes the mode switcher 131 to switch the mode to the mutual-capacitance detection mode (step S 10). The mode switcher 131 selects, as the driving electrode, the sensor in which an electrostatic capacity equal to or greater than the threshold Th 4 is determined from among the sensors 113A to 113D in step S 9, and selects, as the sensing electrode, the sensor adjacent to the sensor selected as the driving electrode.The contact determiner 132 determines an electrostatic capacitance between the driving electrode and the sensing electrode using the driving electrode and the sensing electrode selected in step S 10 (step S 11).The contact determiner 132 determines whether the detected electrostatic capacity is equal to or greater than a threshold Th 5 (step S 12). The threshold Th 5 is an example of a fifth threshold, and is set to an electrostatic capacity with which it can be determined whether the hand H is in contact with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present in the mutual capacity detection mode. The processing in step S 12 is the same as the processing in step S 7, but the threshold values are different. The processing proceeds to step S 12 in the case where it is determined that there is no electrostatic capacity equal to or greater than the threshold value Th 2 among the electrostatic capacities (ΔAD) detected in step S 2, and simultaneously in the case where the hand H is not in contact with the rim 110A of the steering wheel 110 at any part including the seam 112A and the dead zone where no sensor is present.The threshold value Th 3 used in step S 7 is an electrostatic capacitance with which it can be determined in the mutual capacitance detection mode whether the hand H contacts the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present. In contrast, the threshold Th 5 used in step S 12 is smaller than the threshold Th 3 because the threshold Th 5 is an electrostatic capacitance with which it can be determined in the mutual capacitance detection mode whether the hand H contacts the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present.When the contact determiner 132 determines that the detected electrostatic capacity is equal to or greater than the threshold Th 5 (Yes in step S 12), the HODECU 130 determines that the hand H contacts the rim 110A of the steering wheel 110 (step S 4). When the hand H contacts the rim 110A of the steering wheel 110 at a dead zone such as the seam 112A where no sensor is present, the processing proceeds to step S 4 via step S 12.When the contact determiner 132 determines that the detected electrostatic capacity is not equal to or greater than the threshold Th 5 (No in step S 12), the HODECU 130 determines that the hand H does not contact the rim 110A of the steering wheel 110 (step S 8). The processing proceeds from step S 12 to step S 8 in the case where the hand H is in very slight contact with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone, for example, in which a sensor is not present at a time point at which the electrostatic capacity is detected in step S 1, but the hand H is no longer in contact with the rim 110A of the steering wheel 110 at the time point at which the electrostatic capacity is detected in step S 11.When the contact determiner 132 determines in step S 9 that there is no electrostatic capacitance equal to or greater than the threshold Th 4 among the electrostatic capacitances of the sensors 113A to 113D (No in step S 9), the HODECU 130 determines that the hand H is not in contact with the rim 110A of the steering wheel 110 (step S 8). The processing proceeds from step S 9 to step S 8 when the hand H is located outside the rim 110A of the steering wheel 110, for example.< Of Threshold Values><Threshold Th1>FIG. 5A is a diagram illustrating the threshold value Th 1 used by the contact determiner 132 in the processing in step S 3. In FIG. 5A, the vertical axis represents the electrostatic capacitance ΔAD as a difference value (ΔAD) calculated by subtracting a predetermined reference value from the digitally converted value (raw value).Since the threshold Th 1 is set to a value at which the detection of firmly gripping the rim 110A with the hand H is performed at a portion other than the seam 112A or the dead zone where no sensor is present in the self-capacity detection mode, the threshold Th 1 is set to a largest value among the thresholds used by the contact determiner 132 in the processing illustrated in FIG. 4.When the contact determiner 132 determines that there is an electrostatic capacity equal to or greater than the threshold Th 2 among the detected electrostatic capacities (ΔAD) in step S 2 (Yes in step S 2), the contact determiner 132 determines whether the electrostatic capacity is equal to or greater than the threshold Th 1 (step S 3). When the electrostatic capacity is equal to or greater than the threshold value Th 1, such as the electrostatic capacity ΔAD 1 illustrated in FIG. 5A, the contact determiner 132 determines that the hand H is in contact with the rim 110A of the steering wheel 110 (step S 4).On the other hand, when the electrostatic capacitance illustrated in FIG. 5A is less than the threshold value Th 1, such as the electrostatic capacitance ΔAD 2, the contact determiner 132 determines that there is a possibility that the hand H does not contact the rim 110A of the steering wheel 110, and the processing proceeds to step S 5.<Threshold Th2>FIG. 5B is a diagram illustrating the threshold value Th 2 used by the contact determiner 132 in the processing in step S 2. In FIG. 5B, the vertical axis represents the electrostatic capacitance ΔAD as a difference value (ΔAD) calculated by subtracting a predetermined reference value from the digitally converted value (raw value).The threshold Th 2 is smaller than the threshold Th 1 because the threshold Th 2 is set to an electrostatic capacity with which it can be determined in the self-capacity detection mode that the hand H is in contact with the rim 110A of the steering wheel 110 at an arbitrary position including the seam 112A and the dead zone in which no sensor is present, and with which a state in which the hand H is in contact with the dead zone of the rim 110A can also be determined. The threshold Th1 is also shown in FIG. 5B.In step S 2, the contact determiner 132 determines whether or not an electrostatic capacity is equal to or greater than the threshold Th 2 among all electrostatic capacities measured by the capacity meter 120 in step S 1. When the contact determiner 132 determines that the electrostatic capacitance is equal to or greater than the threshold Th 2, such as the electrostatic capacitance ΔAD 3 illustrated in FIG. 5B, the processing proceeds to step S 3. On the other hand, if the contact determiner 132 determines that all of the electrostatic capacitances measured by the capacitance meter 120 in step S 1 are less than the threshold value Th 2, such as the electrostatic capacitance ΔAD 4 illustrated in FIG. 5B, the processing proceeds to step S 9.<Threshold Th4>FIG. 6 is a diagram illustrating the threshold Th 4 used by the contact determiner 132 in the processing in step S 9. In FIG. 6, the vertical axis represents an electrostatic capacitance (raw value) measured by the capacitance meter 120 in the self-capacitance detection mode.The threshold Th 4 is set to an electrostatic capacity with which it can be determined that the hand H easily contacts the rim 110A of the steering wheel 110 at an arbitrary position in the self-capacity detection mode, and is not a difference value (ΔAD) representing a difference from the predetermined reference value but a digitally converted value (raw value) before the difference value (ΔAD) is calculated. This is intended to detect a slight change in an electrostatic capacitance (raw value) that is digitally converted and output by the capacitance meter 120.When the contact determiner 132 determines that there is an electrostatic capacity equal to or greater than the threshold Th 4 among the electrostatic capacities of the sensors 113A to 113D in step S 9 (Yes in step S 9), the processing proceeds to step S 10 because there is a possibility that the hand H is in light contact with the rim 110A of the steering wheel 110. When the contact determiner 132 determines that the electrostatic capacitance is equal to or greater than the threshold Th 4, such as the electrostatic capacitance Raw 1 illustrated in FIG. 6, the processing proceeds to step S 10.On the other hand, when the electrostatic capacity is less than the threshold value Th 4 such as the electrostatic capacity Raw 2 illustrated in FIG. 6, the contact determiner 132 determines that the hand H does not contact the rim 110A of the steering wheel 110 (step S 8).<Threshold Th3>FIG. 7A is a diagram illustrating the threshold value Th 3 used by the contact determiner 132 in the processing in step S 7. In FIG. 7A, the vertical axis represents an electrostatic capacitance ΔAD measured by the capacitance meter 120 in the mutual capacitance detection mode.The threshold value Th 3 is set to an electrostatic capacity with which it can be determined in the mutual capacity detection mode whether the hand H contacts the rim 110A of the steering wheel 110 at the seam 112A or the dead zone where no sensor is present.When the contact determiner 132 determines in step S 7 that the electrostatic capacity ΔAD 5 illustrated in FIG. 7A is equal to or greater than the threshold Th 3, the contact determiner 132 determines that the hand H is in contact with the rim 110A of the steering wheel 110 (step S 4). After it is determined in step S 2 that the hand H is in contact with the rim 110A at least at any part and it is determined in step S 3 that the hand H is not in contact with a position overlapping at least one of the sensors 113A to 113D, a state in which the hand H is in contact with the rim 110A of the steering wheel 110 is detected at the seam 112A or the dead zone in which no sensor is present.When the contact determiner 132 determines that the electrostatic capacity ΔAD 6 illustrated in FIG. 7A is not equal to or greater than the threshold Th 3 in step S 7 (No in step S 7), the contact determiner 132 determines that the hand H is not in contact with the rim 110A of the steering wheel 110 (step S 8).<Threshold Th5>FIG. 7B is a diagram illustrating the threshold value Th 5 used by the contact determiner 132 in the processing in step S 12. In FIG. 7B, the vertical axis represents an electrostatic capacitance ΔAD measured by the capacitance meter 120 in the self-capacitance detection mode.The threshold value Th 5 is set to an electrostatic capacity with which it can be determined in the mutual capacity detection mode whether the hand H is in contact with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone in which no sensor is present. The case where the processing proceeds to step S 12 is different from the case where the processing proceeds to step S 7 in that it is determined that there is no electrostatic capacity equal to or greater than the threshold value Th 2 among the electrostatic capacities (ΔAD) calculated in step S 2 (No in step S 2).The threshold Th 5 is only for detecting the contact of the hand H with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone where no sensor is present, and is therefore smaller than the threshold Th 3 with which it is determined whether the hand H is in contact with the rim 110A at the seam 112A or the dead zone where no sensor is present.When the contact determiner 132 determines in step S 12 that the electrostatic capacity ΔAD 7 illustrated in FIG. 7B is equal to or greater than the threshold Th 5, the contact determiner 132 determines that the hand H is in contact with the rim 110A of the steering wheel 110 (step S 4). It is understood from the determination that the hand H contacts the rim 110A of the steering wheel 110 only at the joint 112A or the dead zone where no sensor is present.When the contact determiner 132 determines in step S 12 that the electrostatic capacity ΔAD 8 illustrated in FIG. 7B is not equal to or greater than the threshold Th 5, the contact determiner 132 determines that the hand H is not contacted with the rim 110A of the steering wheel 110 (step S 8). It is understood from the determination that the hand H does not contact the rim 110A of the steering wheel 110 even at the seam 112A or the dead zone where no sensor is present.<>The steering wheel unit 100 includes the steering wheel 110 having the rim 110A, the spokes 110B, and the sensors 113A to 113D disposed inside the rim 110A; the mode switcher 131 that selects any one of the sensors 113A to 113D as a driving electrode or a sensing electrode and enables switching between the self-capacitance sensing mode and the mutual capacitance sensing mode; the capacitance meter 120 that measures an electrostatic capacitance sensed by the driving electrode and the sensing electrode; and the contact determiner 132 that determines whether the hand H of the operator is in contact with the steering wheel 110 based on the electrostatic capacitances measured by the capacitance meter 120. The mode switcher 131 selects one driving electrode from the sensors 113A to 113D, and selects the electrode adjacent to the selected driving electrode as the detection electrode in the mutual capacitance detection mode. When the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 1 in the self-capacitance detection mode set by the mode switcher 131, the contact determiner 132 determines that the operator's hand H contacts the rim 110A at a position overlapping at least one of the sensors 113A to 113D. When the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 2 that is less than the threshold Th 1, the contact determiner 132 causes the mode switcher 131 to switch the mode from the self-capacitance detection mode to the mutual capacitance detection mode.After switching the operation mode, when the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 3, the contact determiner 132 determines that the operator's hand H contacts the rim 110A at a position overlapping a distance between the sensors 113A to 113D. Therefore, even when it is determined in the self-capacitance detection mode that the hand H of the operator does not contact the rim 110A, it is possible to determine whether or not the hand H is in contact by measuring the electrostatic capacitance in the mutual capacitance detection mode.Therefore, the steering wheel unit 100 is capable of determining whether the operator's hand H contacts the rim 110A of the steering wheel 110 in a dead zone in which no sensor is present.When the electrostatic capacitance measured by the capacitance meter 120 in the mutual capacitance detection mode is less than the threshold Th 3, the contact determiner 132 determines that the hand H is not in contact with the rim 110A. Therefore, it can be determined that the operator's hand H does not contact with the dead zone in which no sensor is present.When the electrostatic capacitance measured by the capacitance meter 120 in the self-capacitance detection mode is less than the threshold Th 2 and equal to or greater than the threshold Th 4, the contact determiner 132 causes the mode switcher 131 to switch the mode from the self-capacitance detection mode to the mutual-capacitance detection mode. After the mode switching, when the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 5, the contact determiner 132 determines that the operator's hand H contacts the rim 110A at a position overlapping a distance between the sensors 113A to 113D. Therefore, even when the electrostatic capacitance measured by the capacitance meter 120 in the self-capacitance detection mode is small, for example, smaller than the threshold Th 2, it can be determined that the operator's hand H is in contact with the dead zone in which no sensor is present.When the electrostatic capacitance measured by the capacitance meter 120 in the mutual capacitance detection mode is less than the threshold Th 5, the contact determiner 132 determines that the hand H is not contacted with the rim 110A. Therefore, even when the electrostatic capacitance measured by the capacitance meter 120 in the self-capacitance detection mode is small, for example, smaller than the threshold Th 2, it can be determined that the operator's hand H does not contact in the dead zone in which no sensor is present.The threshold Th 5 is smaller than the threshold Th 3. The threshold Th 5 serves to easily detect the contact of the hand H with the rim 110A of the steering wheel 110 at the seam 112A or the dead zone where no sensor is present, and therefore the threshold Th 5 is smaller than the threshold Th 3 used for determining a state where the hand H is in contact with the rim 110A at the seam 112A or the dead zone where no sensor is present.The threshold Th 4 is a threshold used for comparison with an electrostatic capacity (raw value) that is not an electrostatic capacity calculated by subtracting a reference value from the electrostatic capacity measured by the capacity meter 120 in the self-capacity detection mode. Therefore, it is possible to determine that the operator's hand H is in contact in the dead zone in which no sensor is present by detecting a slight change in electrostatic capacitance (raw value) that is digitally converted and output from the capacitance meter 120.When the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 2, the contact determiner 132 determines whether the electrostatic capacitance measured by the capacitance meter 120 is equal to or greater than the threshold Th 1. Therefore, it is possible to distinguish between the case where the hand H is contacted with the seam 112A or the dead zone in which no sensor is present and the case where the hand H is contacted with another part of the rim 110A.The distance between the sensors 113A- 113D is at the seam 112A or the junction of the outer panel 112 covering the rim 110A. Therefore, it can be determined whether the operator's hand H contacts the rim 110A at a dead zone such as the seam 112A or the joint of the outer panel 112.<Modifizierte Examples>FIG. 8 is a diagram showing a configuration of the sensors 113 according to a modified example of the embodiment. Although the four sensors 113A to 113D are provided in the steering wheel 110 in the embodiment described with reference to FIGS. 1 to 3, the number of sensors is not limited to four, but may be more than four, for example.FIG. 8 shows 21 sensors 113 arranged in seven columns and three rows, and initial values (raw values) of the electrostatic capacitances of the seven sensors in the second row measured by the capacitance meter 120. These 21 sensors 113 are provided on a flat outer cladding 112 (see FIG. 1 ). The seam 112A as a dead zone is located at a position corresponding to the eighth column of the sensors 113 in the arrangement of three rows and seven columns. For example, when the outer panel is wound around the rim of the steering core 111, the seam 112A is located between the sensor 113 in the first column and the sensor 113 in the seventh column.The processing performed by the HODECU 130 in the case where the operator's hand H contacts the seam 112A in the dead zone located at the position corresponding to the eighth column of the second row will be described below.When the processing is started, the contact determiner 132 causes the mode switcher 131 to set the self-capacitance detection mode, and detects electrostatic capacitances, which are sequentially measured in 21 sensors 113 in time division by the capacitance meter 120 (step S 1). In step S 1, the contact determiner 132 determines a digitally converted value (raw value) representing the electrostatic capacitance detected by the capacitance meter 120.In step S 1, the mode switcher 131 may operate 20 sensors other than the sensor that detects an electrostatic capacitance as shielding. The contact determiner 132 may cause the mode switcher 131 to perform such processing. By operating these 20 sensors other than the sensor that detects an electrostatic capacitance as shielding, it is possible to suppress the influence of the mass or the like in the vicinity of the sensor that detects an electrostatic capacitance and stably detect an electrostatic capacitance.The contact determiner 132 calculates an electrostatic capacity as a difference value (ΔAD) by subtracting a predetermined reference value from the digitally converted value (raw value), and determines whether or not there is an electrostatic capacity equal to or greater than a threshold value Th 2 among the detected electrostatic capacities (step S 2). Since the operator's hand H is in contact with the seam 112A, the electrostatic capacity is less than the threshold Th 2, and the process proceeds to step S 9.In this section, the output value (raw value) of the electrostatic capacitance of each sensor detected by the capacitance meter 120 will be described.The positions of the 21 sensors with respect to the seam 112A are different between the first and seventh columns, and the number of the sensors 113 arranged in the left and right lateral direction from the sensors is different between the first and seventh columns. For example, the sensor in the second row and the sixth column is positioned at the second left and the sixth right sides of the seam 112A, and the initial value (raw value) of the electrostatic capacitance is lower than that of the sensor in the second row and the seventh column. This is because the more sensors are present between the seam 112A and the steering wheel 110, and the lower the initial value, the less capacitive coupling to the ground in the vicinity, such as the steering wheel 110. Therefore, the 21 sensors in the first to seventh columns and the first to third rows have different initial values of the electrostatic capacitances (raw values) measured by the capacitance meter 120. The initial value is an electrostatic capacity (raw value) in the case where the hand H is not in contact with the seam 112A.In step S 9, the contact determiner 132 determines that the electrostatic capacitances (raw values) of the sensors 113 of the first column and the seventh column adjacent to the seam 112A exceed the threshold value Th 4 using the sensors 113 of each row and each column, and is capable of detecting a possibility that the hand H may be in contact with the seam 112A, and the processing proceeds to step S 10.The processing in steps S 10 to S 12 is as described below.Although the steering wheel unit according to the exemplary embodiment of the present disclosure has been described above, the present disclosure is not limited to the specifically disclosed embodiment, and various modifications and changes may be made without departing from the scope of the claims.This international application claims priority to Japanese Patent Application No. 2022-125647 filed on Aug. 5, 2022, the entire contents of which are incorporated herein by reference.LIST OF REFERENCE CHARACTERS100 Steering wheel unit 110 Steering wheel 110A Rim 110B Spokes 111 Steering core 112 Outer cover 112A Seam (an example of a position overlapping with a distance between a plurality of electrodes) 113, 113A to 113D Sensors (an example of a plurality of electrodes) 120 Capacitance meter 130 HODECU 131 Mode switcher 132 Contact determiner 200 ADASECUReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedJP 2022-125647

[01103]

Claims

A steering wheel unit, comprising: a steering wheel including a rim, spokes, and a plurality of electrodes spaced apart from each other and covering the rim; a mode switcher configured to switch between a self-capacitance detection mode and a mutual capacitance detection mode for the plurality of electrodes; a capacitance meter configured to measure a respective electrostatic capacitance at each of the plurality of electrodes; and a contact determiner configured to determine whether or not a hand of an operator is in contact with the steering wheel based on the electrostatic capacitances measured by the capacitance meter, wherein the mode switcher selects one driving electrode from the plurality of electrodes and selects one electrode adjacent to the selected driving electrode as a detection electrode in the mutual capacitance detection mode, wherein, in the self-capacitance detection mode set by the mode switcher, when any one of the electrostatic capacitances measured by the capacitance meter is equal to or greater than a first threshold, the contact determiner determines that the hand of the operator is in contact with the rim at a position overlapping at least one of the plurality of electrodes, wherein, when the any one of the electrostatic capacitances measured by the capacitance meter is equal to or greater than a second threshold and less than the first threshold, wherein the second threshold is less than the first threshold, the contact determiner causes the mode switcher to switch the self-capacitance detection mode to the mutual capacitance detection mode, and wherein after the switching, when an electrostatic capacitance newly measured by the capacitance meter in the mutual capacitance detection mode is equal to or greater than a third threshold, the control unit determines that the operator's hand is in contact with the rim at a position overlapping a distance between the electrodes.The steering wheel unit according to claim 1, wherein when the electrostatic capacitance measured by the capacitance meter in the mutual capacitance detection mode is less than the third threshold, the contact determiner determines that the operator's hand is not in contact with the rim.The steering wheel unit according to claim 1, wherein when any one of the electrostatic capacitances measured by the capacitance meter in the self-capacitance detection mode is less than the second threshold and the electrostatic capacitance measured by the capacitance meter is equal to or greater than a fourth threshold, the self-capacitance detection mode is switched to the mutual-capacitance detection mode by the mode switch, wherein after the switching, when an electrostatic capacitance newly measured by the capacitance meter is equal to or greater than a fifth threshold, the contact determiner determines that the operator's hand is in contact with the rim at a position overlapping a distance between the electrodes.The steering wheel unit according to claim 3, wherein when the electrostatic capacitance measured by the capacitance meter in the mutual capacitance detection mode is less than the fifth threshold, the contact determiner determines that the operator's hand is not in contact with the rim.The steering wheel unit according to claim 3, wherein the fifth threshold is smaller than the third threshold.The steering wheel unit according to claim 3, wherein the fourth threshold is a threshold used for comparison with the electrostatic capacitances measured by the capacitance meter in the self-capacitance detection mode, and from which no reference value is subtracted.The steering wheel unit according to any one of claims 1 to 6, wherein when any one of the electrostatic capacitances measured by the capacitance meter is equal to or greater than the second threshold, the contact determiner determines whether the any one of the electrostatic capacitances measured by the capacitance meter is equal to or greater than the first threshold.The steering wheel unit according to claim 1, wherein a distance between the plurality of electrodes is disposed at a seam or a joint of an outer panel covering the rim.