Sensor mat structure and gripping sensing system

Abstract

To solve the problem that there is a risk that a touch sensor in a steering wheel of a vehicle may sense that the steering wheel is gripped, although a driver is actually not gripping the steering wheel.SOLUTION: In a sensor mat structure of a touch sensor, a gripping part has a shape that is symmetric with a first plane including a rotary shaft direction of a steering part and a vertical direction of a vehicle, in a basic state where the steering part indicates an advancing direction of the vehicle. The touch sensor senses a state of gripping by a driver. The sensor mat structure comprises a conductive cloth layer. The conductive cloth layer includes a first conductive cloth that is provided at least in a first sensing range positioned closer to a side in a downward direction than a second plane including the rotary shaft direction and a lateral direction of the vehicle in the basic state, and a second conductive cloth that is provided in a second sensing range positioned closer to a side in an upward direction of the vehicle than the first sensing range. The first conductive cloth is constituted of the same materials as materials of the second conductive cloth and is constituted to be thicker than the second conductive cloth.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present disclosure relates to a sensor mat structure and a grip detection system. [Background technology]

[0002] There is a technology for detecting whether a driver is gripping the steering wheel of a vehicle using a touch sensor provided on the steering wheel, as described in Patent Document 1, for example. Such a technology is used to request the driver to grip the steering wheel while an advanced driving assistance system, including LTA (Lane Tracing Assist: a lane departure prevention assistance system) and LCA (Lane Change Assist: a lane change assistance system), is operating.

[0003] A steering wheel equipped with a touch sensor has a laminated structure. For example, the steering wheel has an outermost layer covered with leather. Furthermore, the steering wheel has an inner layer made of conductive cloth. The touch sensor detects a change in capacitance caused by the driver's hand approaching the outermost layer of the steering wheel and the conductive cloth. In this way, the touch sensor detects whether the steering wheel is being gripped. The structure of the steering wheel from the conductive cloth to the outermost layer is called the "sensor mat structure." [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-055420 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the capacitance also changes when something other than the driver's hand touches the steering wheel, so the touch sensor can also detect changes in capacitance that occur when the driver's knee touches the steering wheel, for example.

[0006] That is, with the conventional sensor mat structure, there is a risk that the steering wheel may be detected as being gripped by the driver even though the driver is not actually gripping the steering wheel. [Means for solving the problem]

[0007] The present disclosure can be realized in the following forms.

[0008] (1) According to one aspect of the present disclosure, there is provided a sensor mat structure having a touch sensor provided in a grip portion gripped by a driver in a steering unit for indicating a traveling direction of a vehicle, the steering unit being rotatably attached to the vehicle, the grip portion having a shape symmetrical with respect to a first plane including a rotation axis direction of the steering unit and a vertical direction of the vehicle in a basic state in which the steering unit indicates a straight traveling direction of the vehicle, the touch sensor having a plurality of detection ranges, and detecting the driver's grip in each of the plurality of detection ranges based on a change in capacitance due to the approach of the driver, the sensor mat structure including a conductive cloth layer made of a conductive material, the conductive cloth The layer includes: a first conductive cloth provided in the plurality of detection ranges, and at least a first detection range among the plurality of detection ranges that is located downward of the vehicle relative to a second plane that includes the direction of the rotation axis and the left-right direction of the vehicle in the basic state; and a second conductive cloth provided in a second detection range among the plurality of detection ranges that is located upward of the vehicle relative to the first detection range when the steering unit is in the basic state, on the side of the gripping unit where the first conductive cloth is provided with respect to a third plane that passes through the gripping unit and is perpendicular to the rotation axis of the steering unit, and the first conductive cloth is made of the same material as the second conductive cloth and is thicker than the second conductive cloth. With this configuration, the touch sensor detects the driver's grip using the first conductive cloth and the second conductive cloth, which have different thicknesses. In the touch sensor, when the driver approaches the grip, electric charge concentrates on the surface of the conductive cloth. The thinner the conductive cloth, the more easily electric charge concentrates on the surface of the conductive cloth, and a stronger electric field is likely to be generated between the driver and the conductive cloth. In other words, the thinner the conductive cloth, the more easily the capacitance changes. And the thicker the conductive cloth, the less likely the capacitance changes. Therefore, when the materials are the same, the change in capacitance of the first conductive cloth is slower than the change in capacitance of the second conductive cloth. The first conductive cloth is provided at least in the first detection range. Because the legs of a seated driver are located on the lower side of the grip, there is a high possibility that they will come into contact with the first detection range below the grip when the driver crosses their legs. However, the change in capacitance of the first conductive cloth is less likely to change than the change in capacitance of the second conductive cloth. In other words, even if the driver's legs come into contact with the grip, it is difficult to detect. Therefore, this type of sensor mat structure can prevent the grip portion from being mistakenly detected as being gripped by the driver even though the driver is not gripping it. (2) In the sensor mat structure of the above aspect, the first conductive cloth may be provided only on the rear side of the gripping portion that does not face the driver with respect to the third plane. With this configuration, the first conductive cloth is provided only on the side of the gripping portion that is likely to come into contact with the knee. Therefore, with this sensor mat structure, the first conductive cloth can be made smaller than in a configuration in which the first conductive cloth is also provided on the front side. In other words, with this sensor mat structure, the range in which the sensitivity of the gripping portion is reduced can be made smaller, making it easier to detect the driver's grip while preventing the gripping portion from being mistakenly detected as being gripped. (3) In the sensor mat structure of the above aspect, the first conductive cloth may be provided only in the first detection range of the gripping portion. In this configuration, the first conductive cloth is provided only in the first detection range on the back side of the grip portion. This allows the sensor mat structure of this configuration to reduce the range in which the sensitivity of the grip portion is reduced compared to a configuration in which the first conductive cloth is provided in areas other than the first detection range. Therefore, this sensor mat structure can more easily detect the driver's grip. (4) In the sensor mat structure of the above form, the gripping portion may be annular, and the first conductive cloth may be provided only in an arc-shaped portion of the gripping portion in the basic state when viewed from the front side, from 4 o'clock to 8 o'clock on a clock centered on the rotation axis of the steering unit. By adopting this configuration, the first conductive cloth is provided in an area smaller than the first detection area. In other words, this sensor mat structure can reduce the area where the sensitivity of the gripping portion is reduced. Therefore, this sensor mat structure can more easily detect the driver's grip. (5) According to another aspect of the present disclosure, there is provided a grip detection system, the grip detection system comprising: a steering unit provided in a steering device of a vehicle, rotatably attached to the vehicle to indicate a traveling direction of the vehicle, the steering unit having a grip to be gripped by a driver of the vehicle; an output unit that outputs information; a touch sensor having a plurality of detection ranges, the touch sensor detecting the driver's grip based on a change in capacitance caused by the driver's approach in each of the plurality of detection ranges; and a control unit, wherein the grip has a shape symmetrical with respect to a first plane including a rotation axis direction of the steering unit and a vertical direction of the vehicle in a basic state in which the steering unit indicates a straight traveling direction of the vehicle; the touch sensor is provided along the shape of the grip and includes, in a cross section of the grip, a conductive cloth layer made of a conductive material, the conductive cloth layer is provided in the plurality of detection ranges, and a touch sensor is provided in each of the plurality of detection ranges to detect the rotation axis direction and the left-right direction of the vehicle in the basic state. and a second conductive cloth provided in a second detection range, among the plurality of detection ranges, on the side of the gripping unit where the first conductive cloth is provided with respect to a third plane that passes through the gripping unit and is perpendicular to the rotation axis of the steering unit, the second conductive cloth being provided in a second detection range that is located above the first detection range of the vehicle when the steering unit is in the basic state, the second conductive cloth being made of the same material as the second conductive cloth and being thicker than the second conductive cloth, and the control unit detects the driver's gripping of the gripping unit when the driver grips a predetermined reference range that includes a cross section of the gripping unit that overlaps the second plane, and if the control unit does not detect the driver's gripping, the output unit outputs a signal indicating that the gripping unit is not being gripped, and if the control unit detects the driver's gripping, the output unit does not output a signal. In this embodiment, the grip detection system is designed to more easily detect gripping in the second detection range than in the first detection range below the grip portion in the basic state. Furthermore, because the first conductive cloth is thicker than the second conductive cloth, gripping in the first detection range is less likely to be detected. Because the legs of a seated driver are located on the lower side of the vehicle in the grip portion, there is a high possibility that the driver will come into contact with the first detection range below the grip portion when crossing their legs. Therefore, this grip detection system can prevent the grip portion from being mistakenly detected as being gripped by the driver even when it is not being gripped. Furthermore, there is a high possibility that the driver will grip the second detection range when starting to manually steer the vehicle. This grip detection system can easily detect the range that is likely to be gripped. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is an explanatory diagram showing a grip detection system according to a first embodiment. [Figure 2] FIG. 2 is an explanatory diagram showing the front side of the steering section. [Figure 3] FIG. 2 is an explanatory diagram showing the back side of the steering section. [Figure 4] FIG. 4 is a cross-sectional view taken along line IV-IV of FIGS. 2 and 3. [Figure 5] FIG. 4 is a cross-sectional view of FIGS. 2 and 3 . [Figure 6] FIG. 2 is a block diagram illustrating the configuration of a control unit according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A. First embodiment: FIG. 1 is an explanatory diagram showing a grip detection system 10 according to a first embodiment. The grip detection system 10 is installed in, for example, a vehicle M equipped with an advanced driving assistance system. The advanced driving assistance system includes LTA (Lane Tracing Assist: a lane departure prevention assistance system), LCA (Lane Change Assist: a lane change assistance system), and automated driving that does not require operation by the driver DR. In this specification, manual driving means that the driver DR operates the vehicle M when the advanced driving assistance system is not operating. FIG. 1 illustrates a state in which the driver DR is not gripping the steering unit 100 to indicate that driving is being performed by the advanced driving assistance system. The grip detection system 10 requires the driver DR to grip the grip unit 120 when transitioning from driving by the advanced driving assistance system to manual driving.

[0011] 1 shows a simplified view of a steering device 11 of a vehicle M. A steering section 100 provided in the steering device 11 is operated by a driver DR, who is an occupant of the vehicle M. The steering device 11 is connected to a rotation axis AR of the vehicle M, and is configured to be rotatable about an axis line AX of the rotation axis AR.

[0012] The rotation of the steering device 11 is transmitted to a steering gearbox (not shown) via a rotation axis AR. The direction along the axis AX of the rotation axis AR is called the X-axis direction or rotation axis direction. In the X-axis direction, the direction away from the driver DR is called the +X direction. In the directions perpendicular to the axis AX, the direction along the left-right direction of the vehicle M is called the Y-axis direction or left-right direction. In the Y-axis direction, the direction toward the right of the vehicle M is called the +Y direction, and the direction toward the left of the vehicle M is called the -Y direction. The direction perpendicular to the axis AX and the Y direction is called the Z-axis direction. In addition, the direction along the up-down direction of the vehicle M is called the MU-axis direction or up-down direction. In the MU-axis direction, the direction toward the top of the vehicle M is called the +MU direction, and the direction toward the bottom of the vehicle M is called the -MU direction. The traveling direction of the vehicle M is an axis perpendicular to the MU-axis and is represented by the MF-axis. That is, in the direction parallel to the MF-axis, the positive direction is the front of the vehicle M, and the negative direction is the rear of the vehicle M. The direction along the positive direction of the MF-axis is called the straight-ahead direction.

[0013] The grip detection system 10 includes a steering unit 100, a touch sensor 200, an output unit 300, and a control unit 400. The touch sensor 200 is illustrated in FIG.

[0014] FIG. 2 is an explanatory diagram showing the front side Fs of the steering unit 100. The steering unit 100 is provided in the steering device 11 of the vehicle M and indicates the traveling direction of the vehicle M. The steering unit 100 is rotatably attached to the vehicle M. That is, the steering unit 100 steers the vehicle M by being rotated by the driver DR. The state in which the steering unit 100 indicates the straight traveling direction of the vehicle M is called the basic state. FIG. 2 illustrates the steering unit 100 in the basic state.

[0015] Fig. 2 illustrates the steering unit 100 when viewed in the +X direction. That is, as in Fig. 1, the front side Fs of the steering unit 100 facing the driver DR is illustrated. To facilitate understanding of the technology, in Fig. 2, when the rotation axis AR is the center and the +Z direction is 12 o'clock, the 2 o'clock, 3 o'clock, 4 o'clock, 6 o'clock, 8 o'clock, 9 o'clock, 10 o'clock, and 12 o'clock positions are indicated as 2o, 3o, 4o, 6o, 8o, 9o, 10o, and 12o, respectively.

[0016] In the following description, a first plane P1, a second plane P2, and a third plane P3 are used, which are imaginary planes. The first plane P1 is a plane that includes the X-axis and Z-axis directions in the basic state. That is, the first plane P1 is a plane that includes the rotation axis direction of the steering unit 100 and the up-down direction of the vehicle M in the basic state. The second plane P2 is a plane that includes the X-axis and Y-axis directions in the basic state. That is, the second plane P2 is a plane that includes the rotation axis direction of the steering unit 100 in the basic state and the left-right direction of the vehicle M. Note that, as shown in the left part of FIG. 2, in the grip unit 120 in the basic state, the side in the -Z direction from the second plane P2 is referred to as the lower side Ls, and the side in the +Z direction from the second plane P2 is referred to as the upper side Us. The third plane P3 is a plane that passes through the grip unit 120 and is perpendicular to the rotation axis AR, as shown in FIG. 1.

[0017] That is, the front side Fs of the steering section 100 is the side of the grip section 120 that faces the driver DR with respect to the third plane P3.

[0018] FIG. 3 is an explanatory diagram showing the back side Bs of the steering unit 100. FIG. 3 illustrates the steering unit 100 when viewed in the -X direction. The back side Bs of the steering unit 100 is the side that does not face the driver DR with respect to the third plane P3. To facilitate technical understanding, FIG. 3 shows the positions of 2o, 3o, 4o, 6o, 8o, 9o, 10o, and 12o shown in FIG. 2 at corresponding positions. FIG. 2 and FIG. 3 are in a front-to-back relationship. Therefore, the positions of 2o and 10o, the positions of 3o and 9o, and the positions of 4o and 8o in FIG. 3 are reversed from the positions of 2o and 10o, the positions of 3o and 9o, and the positions of 4o and 8o in FIG. 2.

[0019] The steering unit 100 includes a central portion 110 and a grip portion 120. In this specification, the "steering unit" is also referred to as a "handle."

[0020] The central portion 110 is rotatably attached to the vehicle M. Specifically, the central portion 110 is rotatably attached to the vehicle M by passing a rotation axis AR shown in FIG. 1 through and fixing a hole formed in the central portion 110. The central portion 110 is also connected to the grip portion 120. In the basic state, the central portion 110 is symmetrical with respect to the first plane P1.

[0021] The grip portion 120 is a portion that is gripped by the driver DR of the vehicle M. The grip portion 120 has a shape that is symmetrical with respect to a first plane P1 that includes the rotation axis direction of the steering unit 100 and the up-down direction of the vehicle M. More specifically, the grip portion 120 is an annular portion that is formed around the central portion 110 in the steering unit 100. The grip portion 120 is connected to the central portion 110 on the inner peripheral side of the grip portion 120.

[0022] Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 2 and Fig. 3. The gripping portion 120 includes a core portion 121, a heater layer 122, a shielding layer 123, an insulating layer 124, a conductive fabric layer 125, and a covering layer 126.

[0023] The core metal portion 121 is a portion that constitutes the skeleton of the grip portion 120. As shown in FIG. 2, the core metal portion 121 has a circular ring shape when viewed in the +X direction. The core metal portion 121 is composed of a core metal and a core metal covering portion (not shown). The core metal is made of a metal material such as iron or aluminum, and is conductive. Furthermore, the core metal is grounded. The core metal covering portion is made of a soft material such as polyurethane foam or an elastic material, and covers the periphery of the core metal. As shown in FIG. 4, the core metal portion 121 is covered with a heater layer 122.

[0024] The heater layer 122 generates heat when energized, and can raise the temperature of the gripping part 120. The heater layer 122 is configured, for example, by a flexible sheet-like heating element. A shield layer 123 is laminated on the heater layer 122. Note that the gripping part 120 does not necessarily have to include the heater layer 122. When the gripping part 120 does not have the heater layer 122, the core part 121 is covered with the shield layer 123.

[0025] The shield layer 123 is made of conductive fabric, which is a fiber fabric that has been surface-treated with metal plating. An insulating layer 124, a conductive fabric layer 125, and a covering layer 126 are laminated on the shield layer 123, in that order. That is, the shield layer 123 is disposed between the core and the conductive fabric layer 125. The shield layer 123 is disposed between the insulating layer 124 and the heater layer 122. The shield layer 123 is electrically connected to the conductive fabric layer 125 via the sensor circuit 220. The sensor circuit 220 controls the shield layer 123 to have the same potential as the conductive fabric layer 125. Therefore, no capacitance is generated between the conductive fabric layer 125 and the core, or between the conductive fabric layer 125 and the heater layer 122. That is, the shield layer 123 can eliminate capacitance noise generated in the conductive fabric layer 125 regardless of whether the driver DR grips the grip portion 120.

[0026] The insulating layer 124 is disposed between the conductive fabric layer 125 and the shielding layer 123. The insulating layer 124 is made of a non-conductive, flexible material. For example, the insulating layer 124 is made of PET (Polyethylene terephthalate).

[0027] The covering layer 126 covers the conductive fabric layer 125. More specifically, the covering layer 126 is exposed to the outside at the grip portion 120 and is gripped by the driver DR. The covering layer 126 is made of a non-conductive material. For example, the covering layer 126 is made of natural leather or synthetic leather. The covering layer 126 may also be made of a synthetic resin such as urethane. The covering layer 126 is made of a first covering material 126f1, a second covering material 126f2, and a third covering material 126f3. The first covering material 126f1, the second covering material 126f2, and the third covering material 126f3 will be described later.

[0028] The conductive fabric layer 125 functions as one electrode of the touch sensor 200, which is a capacitance sensor. The conductive fabric layer 125 is made of a conductive material. More specifically, the conductive fabric layer 125 is made of a conductive fabric that is a fiber fabric that has been surface-treated with metal plating. In this specification, the "conductive fabric" is also referred to as "conductive fabric." The conductive fabric layer 125 is electrically connected to the sensor circuit 220. In this specification, the structure from the conductive fabric layer 125 to the covering layer 126 is referred to as the "sensor mat structure." The sensor mat structure will be described in detail later.

[0029] As shown in FIG. 4, the layers of the gripping portion 120 are bonded together with a bonding material 120a such as double-sided tape or adhesive.

[0030] 2 detects the driver DR's grip based on a change in capacitance caused by the driver DR's approach. More specifically, the touch sensor 200 acquires a measurement value at the grip portion 120 that changes in response to the driver DR's grip of the grip portion 120. Specifically, the touch sensor 200 is a capacitance sensor.

[0031] The touch sensor 200 is provided on the grip part 120 along the shape of the grip part 120. The touch sensor 200 has a plurality of detection ranges A200. In the first embodiment, the touch sensor 200 has four detection ranges A200 on each of the front side Fs and the back side Bs. The touch sensor 200 acquires a measurement value in each detection range A200. The plurality of detection ranges A200 is composed of a first detection range A201, a second detection range A202, and a third detection range A203. Each detection range A200 will be described later. The plurality of detection ranges A200 are symmetrical with respect to the first plane P1.

[0032] The touch sensor 200 includes a sensor unit 210 and a sensor circuit 220. The sensor unit 210 is electrically connected to the sensor circuit 220.

[0033] As shown in FIG. 4, the sensor unit 210 is composed of a cover layer 126 and a conductive cloth layer 125. That is, the sensor unit 210 has a sensor mat structure. The sensor unit 210 has capacitance between the hand of the driver DR and the conductive cloth layer 125. As described above, the conductive cloth layer 125 functions as one electrode of the capacitance sensor. The other electrode of the capacitance sensor is the hand of the driver DR. The capacitance of the sensor unit 210 changes depending on the distance between the hand of the driver DR and the conductive cloth layer 125, the area of ​​the hand, and the like.

[0034] That is, the sensor unit 210 constitutes the detection range A200 of the touch sensor 200. Therefore, the conductive cloth layer 125 is provided in the multiple detection ranges A200. The conductive cloth layer 125 is composed of a first conductive cloth 125f1 provided in the first detection range A201, a second conductive cloth 125f2 provided in the second detection range A202, and a third conductive cloth 125f3 provided in the third detection range A203.

[0035] As shown in FIG. 3, the first detection range A201 is a detection range A200 that is located below the vehicle M with respect to the second plane P2, among the multiple detection ranges A200.

[0036] As shown in the lower side Ls of FIG. 3 , the first conductive cloth 125f1 is provided in a first detection range A201, which is located below the second plane P2 of the vehicle M, among the multiple detection ranges A200. The first conductive cloth 125f1 is provided only on the back side Bs of the gripping portion 120. Furthermore, in the gripping portion 120 in the basic state when viewed from the back side Bs, the first conductive cloth 125f1 is provided only in an arc-shaped portion from 4 o'clock to 8 o'clock in the counterclockwise direction where the first conductive cloth 125f1 is provided. Therefore, when viewed from the front side Fs, which is opposite the back side Bs, the first conductive cloth 125f1 is provided only in an arc-shaped portion from 4 o'clock to 8 o'clock in the clockwise direction centered on the rotation axis AR of the steering unit 100 in the gripping portion 120 in the basic state.

[0037] 3, the second detection range A202 is a detection range A200 that is located above the vehicle M relative to the first detection range A201 when the steering section 100 is in the basic state, among the multiple detection ranges A200, on the side where the first conductive cloth 125f1 is provided with respect to the third plane P3. Note that the side where the first conductive cloth 125f1 is provided with respect to the third plane P3 is the back side Bs in the first embodiment.

[0038] That is, the second conductive cloth 125f2 is provided on the back side Bs of the gripping part 120 as shown in Fig. 4. More specifically, the second conductive cloth 125f2 is provided in a part of the detection range A200 on the back side Bs as shown in Fig. 3. When the gripping part 120 is in the basic state as seen from the back side Bs, the second conductive cloth 125f2 is provided in an arc-shaped portion from 4 o'clock to 8 o'clock counterclockwise as shown in Fig. 3.

[0039] 2, the third detection range A203 is the detection range A200 on the side of the third plane P3 on which the first conductive cloth 125f1 is not provided. In the first embodiment, the side on which the first conductive cloth 125f1 is not provided on the third plane P3 is the front side Fs.

[0040] 4, the third conductive cloth 125f3 is provided on the front side Fs of the gripping portion 120. More specifically, the third conductive cloth 125f3 is provided over the entire detection range A200 on the front side Fs.

[0041] FIG. 5 is a VV cross-sectional view of FIGS. 2 and 3. The lower part of FIG. 5 shows the back side Bs of the gripping portion 120, on which the first conductive cloth 125f1 is provided. The upper part of FIG. 5 shows the front side Fs of the gripping portion 120, on which the third conductive cloth 125f3 is provided. The first conductive cloth 125f1 is configured to be thicker than the second conductive cloth 125f2 and the third conductive cloth 125f3. For example, the thickness T125f1 of the first conductive cloth is twice the thickness T125f2 of the second conductive cloth shown in FIG. 4. The second conductive cloth 125f2 and the third conductive cloth 125f3 have the same thickness. Furthermore, the first conductive cloth 125f1 is configured from the same material as the second conductive cloth 125f2 and the third conductive cloth 125f3.

[0042] The first conductive cloth 125f1, the second conductive cloth 125f2, and the third conductive cloth 125f3 are each a single piece of conductive cloth. That is, the first conductive cloth 125f1 is thicker than the second conductive cloth 125f2 because the fibers of the first conductive cloth 125f1 are thicker than the fibers of the second conductive cloth 125f2.

[0043] As shown in FIG. 5, in the covering layer 126, the first covering material 126f1 covering the first conductive cloth 125f1 is thinner than the second covering material 126f2 covering the second conductive cloth 125f2 and the third covering material 126f3 covering the third conductive cloth 125f3. The thickness T126f2 of the second covering material and the thickness of the third covering material are the same. The thickness of the covering layer 126 is designed so that the diameter of the gripping portion 120 is constant. For example, if the thickness T125f1 of the first conductive cloth is twice the thickness T125f2 of the second conductive cloth, the thickness T126f1 of the first covering material is half the thickness T126f2 of the second covering material.

[0044] In the touch sensor 200, when the driver DR approaches the grip portion 120, electric charges concentrate on the surface of the conductive cloth of the conductive cloth layer 125. The thinner the conductive cloth, the more easily electric charges concentrate on the surface of the conductive cloth, and the stronger the electric field is likely to be generated between the driver DR and the conductive cloth. In other words, the thinner the conductive cloth, the more easily the capacitance changes. And the thicker the conductive cloth, the less easily the capacitance changes. For this reason, when the materials are the same, the change in capacitance in the first conductive cloth 125f1 is slower than the change in capacitance in the second conductive cloth 125f2.

[0045] As described above, the first conductive cloth 125f1 is provided in the first detection range A201. As shown in Fig. 1, the legs of the seated driver DR are located on the downward side of the vehicle M in the grip portion 120, and therefore there is a high possibility that the legs will come into contact with the first detection range A201 below the grip portion 120 when the driver DR crosses his / her legs.

[0046] It should be noted that the driver DR may cross his / her legs when the vehicle M is steered automatically, for example, by an advanced driving assistance system. When the vehicle M is steered automatically, the driver DR can take his / her foot off the accelerator pedal and cross his / her legs. When the vehicle M is steered automatically, the vehicle M is likely to turn more gently than when the vehicle M is steered manually. In other words, the range of the rotation angle of the steering unit 100 is smaller when the vehicle M is steered automatically than when the vehicle M is steered manually. Therefore, when the driver DR crosses his / her legs, there is a high possibility that he / she will come into contact with the first detection range A201, which is located below the vehicle M with respect to the second plane P2.

[0047] However, the change in capacitance of the first conductive cloth 125f1 is slower than the change in capacitance of the second conductive cloth 125f2. In other words, even if the driver DR's leg comes into contact with the grip portion 120, it is difficult to detect. Therefore, the sensor mat structure of this embodiment can prevent the driver DR from erroneously detecting that the grip portion 120 is being gripped when it is not actually being gripped.

[0048] Furthermore, the knees of the driver DR who is seated and gripping the grip portion 120 are likely to be located on the back side Bs of the grip portion 120. As described above, the first conductive cloth 125f1 is provided only on the back side Bs of the grip portion 120. With this configuration, the first conductive cloth 125f1 is provided only on the side of the grip portion 120 that is likely to come into contact with the knees. Therefore, the sensor mat structure of this embodiment can reduce the range in which the sensitivity of the grip portion 120 is reduced compared to a configuration in which the first conductive cloth 125f1 is also provided on the front side Fs or a configuration in which the first conductive cloth 125f1 is provided in areas other than the first detection range A201. In other words, the sensor mat structure of this embodiment can reduce the range in which the sensitivity of the grip portion 120 is reduced, thereby making it easier to detect the driver DR's grip while preventing the grip portion 120 from being mistakenly detected as being gripped.

[0049] The sensor circuit 220 included in the touch sensor 200 will now be described. The sensor circuit 220 includes various circuits, such as a sensor drive circuit and a shield drive circuit, and detects changes in capacitance. The sensor circuit 220 acquires, as a change in voltage, a change in capacitance between the conductive cloth layer 125 and the driver DR when the grip portion 120 is being held by the driver DR and when the grip portion 120 is not being held by the driver DR. The sensor circuit 220 acquires the voltage change in each of the multiple detection ranges A200. The sensor circuit 220 sends information about the acquired voltage values ​​to the control unit 400. Furthermore, as described above, the sensor circuit 220 eliminates capacitance noise using the shield layer 123.

[0050] Output unit 300 outputs information in response to a command from control unit 400. More specifically, output unit 300 outputs information indicating that grip unit 120 is not being gripped. Output unit 300 is, for example, an instrument panel.

[0051] FIG. 6 is a block diagram showing the configuration of the control unit 400 of the first embodiment. The control unit 400 is configured as a logic circuit centered around a microcomputer. More specifically, the control unit 400 includes a CPU 410, a ROM 420, a RAM 430, and input / output ports for inputting and outputting various signals. The CPU 410 executes a preset control program. The ROM 420 stores in advance control programs and control data required for the CPU 410 to execute various arithmetic processes. The RAM 430 temporarily reads and writes various data required for the CPU 410 to execute various arithmetic processes. The functions of the control unit 400 will be specifically described below.

[0052] The control unit 400 determines whether the grip portion 120 is being gripped based on the measurement value of the touch sensor 200 and a predetermined threshold value. For example, if the measurement value is designed to increase in response to the driver DR gripping the grip portion 120, the control unit 400 determines that the grip portion 120 is being gripped if the measurement value is equal to or greater than the threshold value. If the measurement value is less than the threshold value, the control unit 400 determines that the grip portion 120 is not being gripped.

[0053] The threshold value is designed based on measurements taken when the driver DR grips a predetermined reference range that includes a cross section of the grip portion 120 that overlaps with the first plane P1. The cross section of the grip portion 120 that overlaps with the first plane P1 is a cross section at the 3 o'clock and 9 o'clock positions on the grip portion 120 in FIG. 2. The reference range is, for example, an arc-shaped range from 8 o'clock to 10 o'clock and an arc-shaped range from 2 o'clock to 4 o'clock on the clock.

[0054] The driver DR can easily rotate the steering unit 100 either clockwise or counterclockwise by gripping both ends of the steering unit 100 in the left-right direction. Therefore, when the driver DR grips the grip unit 120 in the basic state with both hands, the driver DR is likely to grip the 3 o'clock and 9 o'clock positions. Therefore, the threshold value is designed based on, for example, average measurement values ​​when the 3 o'clock and 9 o'clock positions are gripped.

[0055] That is, when the driver DR grasps the predetermined reference range in the gripping portion 120 in the basic state, the control unit 400 detects that the driver DR is grasping the gripping portion 120. By adopting such a configuration, the grip detection system 10 can easily detect a range that is likely to be grasped.

[0056] When the control unit 400 does not detect gripping by the driver DR, the control unit 400 causes the output unit 300 to output a message indicating that the grip unit 120 is not being gripped. When the control unit 400 does not detect gripping by the driver DR, the control unit 400 causes the instrument panel to display a message indicating that the grip unit 120 is not being gripped. When the control unit 400 detects gripping by the driver DR, the control unit 400 does not cause the output unit 300 to output a message.

[0057] As described above, the sensor mat structure of this embodiment can prevent the driver DR from erroneously detecting that the grip portion 120 is being gripped when it is not. Specifically, the touch sensor 200 detects the driver DR's grip using the first conductive cloth 125f1 and the second conductive cloth 125f2, which have different thicknesses. In the touch sensor 200, when the driver DR approaches the grip portion 120, electric charges concentrate on the surface of the conductive cloth. The thinner the conductive cloth, the more easily electric charges concentrate on the surface of the conductive cloth, and a stronger electric field is likely to be generated between the driver DR and the conductive cloth. In other words, the thinner the conductive cloth, the more easily the capacitance changes. Furthermore, the thicker the conductive cloth, the less easily the capacitance changes. Therefore, when the materials are the same, the change in capacitance of the first conductive cloth 125f1 is slower than the change in capacitance of the second conductive cloth 125f2. The first conductive cloth 125f1 is provided in at least the first detection range A201. The legs of the seated driver DR are located on the downward side of the vehicle M of the gripping portion 120, so when the driver DR crosses his / her legs, there is a high possibility that the legs will come into contact with the first detection range A201 below the gripping portion 120. Therefore, when the driver DR crosses his / her legs, there is a high possibility that the legs will come into contact with the first detection range A201, which is located on the downward side of the vehicle M than the second plane P2. However, the change in capacitance of the first conductive cloth 125f1 is less likely to change than the change in capacitance of the second conductive cloth 125f2. In other words, even if the legs of the driver DR come into contact with the gripping portion 120, it is less likely to be detected. Therefore, the sensor mat structure of this embodiment can prevent the driver DR from erroneously detecting that the gripping portion 120 is being held when the driver DR is not actually holding it.

[0058] Furthermore, in the sensor mat structure of this embodiment, the first conductive cloth 125f1 is provided only on the back side Bs of the gripping portion 120. Therefore, as described above, the sensor mat structure of this embodiment can reduce the range in which the sensitivity of the gripping portion 120 is reduced, making it easier to detect that the driver DR is gripping the gripping portion 120, while preventing the gripping portion 120 from being mistakenly detected as being gripped.

[0059] Furthermore, the first conductive cloth 125f1 is provided only in the first detection range A201 on the back side Bs of the gripping portion 120. As a result, as described above, the sensor mat structure of this embodiment can reduce the range in which the sensitivity of the gripping portion 120 is reduced compared to a configuration in which the first conductive cloth 125f1 is provided in areas other than the first detection range A201. Therefore, the sensor mat structure of this embodiment can more easily detect the gripping of the driver DR.

[0060] Furthermore, the grip detection system 10 of this embodiment can easily detect a range that is likely to be gripped. More specifically, the grip detection system 10 of this embodiment is designed to more easily detect a grip in the second detection range A202 than in the first detection range A201 below the grip portion 120 in the basic state. Furthermore, because the first conductive cloth 125f1 is thicker than the second conductive cloth 125f2, a grip in the first detection range A201 is less likely to be detected. As described above, when the driver DR crosses his / her legs, he / she is likely to come into contact with the first detection range A201, which is located below the second plane P2 of the vehicle M. Furthermore, when the driver DR starts to manually steer the vehicle M, he / she is likely to grip the second detection range A202. Therefore, the grip detection system 10 of this embodiment can prevent the driver DR from erroneously detecting that the grip portion 120 is being gripped, even though the driver DR is not gripping the grip portion 120. Furthermore, the grip detection system 10 of this embodiment can easily detect an area that is likely to be gripped.

[0061] B. Second embodiment: In the above embodiment, the first conductive cloth 125f1 is provided only on the back side Bs of the gripping portion 120. However, the first conductive cloth 125f1 may also be provided on the front side Fs. For example, the first conductive cloth 125f1 is provided in the first detection range A201 on the front side Fs and the back side Bs. That is, the multiple detection ranges A200 do not have to include the third detection range A203. The multiple detection ranges A200 may be composed of only the first detection range A201 and the second detection range A202. Therefore, the conductive cloth layer 125 does not have to include the third conductive cloth 125f3. The conductive cloth layer 125 only needs to include the first conductive cloth 125f1 and the second conductive cloth 125f2.

[0062] By adopting this configuration, even if the driver's physique or the position of the steering unit 100 causes the driver's DR's knees to touch the front side Fs of the gripping portion 120, the sensor mat structure of this embodiment can prevent the driver DR from mistakenly detecting that the gripping portion 120 is being gripped even though it is not.

[0063] C. Third embodiment: In the above embodiment, the first conductive cloth 125f1 is provided only in the first detection range A201 of the grip portion 120. However, it is sufficient that the first conductive cloth 125f1 is provided in at least the first detection range A201 of the multiple detection ranges A200. For example, the first conductive cloth 125f1 may be provided in all of the detection ranges A200 on the back side Bs. By adopting such a configuration, it is possible to prevent the grip portion 120 from being erroneously detected as being gripped, regardless of the degree of rotation angle of the steering section 100.

[0064] D. Fourth embodiment: In the above embodiment, the first conductive cloth 125f1 is provided only in an arc-shaped area from 4 to 8 o'clock on the grip portion 120 in the basic state when viewed from the front side Fs, with the grip portion 120 centered on the rotation axis AR of the steering unit 100. However, the first conductive cloth 125f1 may be provided in the first detection range A201. For example, the first conductive cloth 125f1 may be provided in an arc-shaped area from 5 to 7 o'clock or an arc-shaped area from 3:30 to 8:30 on the watch. This configuration allows the designer of the touch sensor 200 to adjust the area in which the first conductive cloth 125f1 is provided depending on the size and position of the steering unit 100. Therefore, the sensor mat structure of this embodiment can more appropriately prevent the grip portion 120 from being erroneously detected as being gripped.

[0065] E. Other Embodiments: (1) In the first embodiment, the multiple detection ranges A200 include the first detection range A201, the second detection range A202, and the third detection range A203. Other detection ranges may also be included. The multiple detection ranges A200 only need to include the first detection range A201 and the second detection range A202.

[0066] (2) In the above embodiment, the third conductive cloth 125f3 has the same thickness as the second conductive cloth 125f2. However, the third conductive cloth 125f3 may have a thickness different from that of the second conductive cloth 125f2.

[0067] (3) In the above embodiment, the grip portion 120 is a ring-shaped portion. However, the grip portion 120 is not limited to a ring shape and may be any shape, such as a polygonal shape or an elliptical shape. Furthermore, the grip portion 120 is not limited to a ring shape and may be, for example, an arc shape without an upper side. Furthermore, the grip portion 120 may be composed of multiple portions that are not continuous with each other, such as a right side portion, a left side portion, and a lower side portion.

[0068] (4) In the above embodiment, the touch sensor 200 has four detection ranges A200 on each of the front side Fs and the back side Bs. However, the touch sensor 200 may have two detection ranges A200 on each of the front side Fs and the back side Bs. Alternatively, the touch sensor 200 may have eight detection ranges A200 on each of the front side Fs and the back side Bs. In other words, it is sufficient for the touch sensor 200 to have multiple detection ranges A200.

[0069] (5) In the above embodiment, an instrument panel is exemplified as the output unit 300. However, the output unit 300 may output information indicating that the grip unit 120 is not being gripped by other methods. For example, the output unit 300 may display the information on a display provided in the vehicle M. Alternatively, the output unit 300 may output the information by sound using a speaker provided in the vehicle M. Furthermore, the output unit 300 may output the information by light using an illumination device provided in the steering unit 100.

[0070] (6) In the above embodiment, the thickness of the covering layer 126 is designed so that the diameter of the gripping portion 120 is constant. Specifically, the first covering material 126f1 covering the first conductive cloth 125f1 is configured to be thinner than the second covering material 126f2 covering the second conductive cloth 125f2. The diameter of the gripping portion 120 may be designed to be constant by other methods. For example, the diameter of the gripping portion 120 may be designed to be constant by adjusting the thickness of the shielding layer 123. Alternatively, another layer having a thickness corresponding to the difference between the thickness T126f1 of the first covering material and the thickness T126f2 of the second covering material may be added between the second conductive cloth 125f2 and the second covering material 126f2. For example, the other layer is a layer made of the same material as the insulating layer 124.

[0071] (7) In the above embodiment, the thickness T125f1 of the first conductive cloth is twice the thickness T125f2 of the second conductive cloth. However, the thickness T125f1 of the first conductive cloth may be 1.5 times or 1.7 times the thickness T125f2 of the second conductive cloth. For example, the thickness T125f1 of the first conductive cloth is in the range of 1.5 to 2.0 times the thickness T125f2 of the second conductive cloth.

[0072] (8) In the above embodiment, the knee of the driver DR is in contact with the grip portion 120 as an example of the case where the grip portion 120 is erroneously detected as being gripped. However, examples of the case where the grip portion 120 is erroneously detected as being gripped are not limited to this. For example, there are cases where a hand placed on the knee comes into contact with the grip portion 120, where the driver DR comes into contact with the grip portion 120 when the legs are not crossed due to the position of the steering unit 100 or the thickness of the driver DR's legs, and where the driver DR leans against the console box and the driver's leg comes into contact with the grip portion 120. Furthermore, since the touch sensor 200 may acquire measurement values ​​from objects other than the human body, the grip portion 120 may be erroneously detected as being gripped even when an object is placed on the knee or when an object is placed so as to lean against the lower side Ls of the grip portion 120.

[0073] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit of the present disclosure. For example, the technical features of the embodiments corresponding to the technical features in each aspect described in the Summary of the Disclosure section can be appropriately replaced or combined to solve some or all of the above problems or achieve some or all of the above effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0074] 10...Grip detection system, 11...Steering device, 100...Steering section, 110...Central section, 120...Grip section, 120a...Joining material, 121...Core section, 122...Heater layer, 123...Shield layer, 124...Insulating layer, 125...Conductive cloth layer, 125f1...First conductive cloth, 125f2...Second conductive cloth, 125f3...Third conductive cloth, 126...Covering layer, 126f1...First covering material, 126f2...Second covering material, 126f3...Third covering material, 200 ...touch sensor, 210...sensor unit, 220...sensor circuit, 300...output unit, 400...control unit, 410...CPU, 420...ROM, 430...RAM, A200...detection range, A201...first detection range, A202...second detection range, A203...third detection range, AR...rotation axis, AX...axis, Bs...back side, DR...driver, Fs...front side, Ls...lower side, M...vehicle, P1...first plane, P2...second plane, P3...third plane, Us...upper side

Claims

1. A sensor mat structure of a touch sensor provided in a grip part that is gripped by a driver in a steering part for indicating the traveling direction of a vehicle, The steering unit is rotatably attached to the vehicle, The grip portion has a shape that is symmetrical with respect to a first plane that includes a rotation axis direction of the steering portion and a vertical direction of the vehicle in a basic state in which the steering portion indicates a straight traveling direction of the vehicle, The touch sensor is a plurality of detection ranges, and in each of the plurality of detection ranges, the grip of the driver is detected based on a change in capacitance due to the approach of the driver; The sensor mat structure includes: A conductive cloth layer is provided, which is made of a conductive material. the conductive cloth layer is provided in the plurality of detection areas, a first conductive cloth provided at least in a first detection range among the plurality of detection ranges, the first detection range being located on a lower side of the vehicle than a second plane including the rotation axis direction and a left-right direction of the vehicle in the basic state; a second conductive cloth provided in a second detection range, among the plurality of detection ranges, located on an upper side of the vehicle than the first detection range when the steering unit is in the basic state, on a side of the grip unit where the first conductive cloth is provided with respect to a third plane that passes through the grip unit and is perpendicular to the rotation axis of the steering unit, A sensor mat structure in which the first conductive cloth is made of the same material as the second conductive cloth and is thicker than the second conductive cloth.

2. The sensor mat structure according to claim 1, A sensor mat structure, wherein the first conductive cloth is provided only on a back side that does not face the driver with respect to the third plane.

3. The sensor mat structure according to claim 2, A sensor mat structure in which the first conductive cloth is provided only in the first detection range of the gripping portion.

4. The sensor mat structure according to claim 3, The grip portion is annular, A sensor mat structure in which the first conductive cloth is provided only in an arc-shaped area from 4 o'clock to 8 o'clock on a clock centered on the rotation axis of the steering unit, in the gripping portion in the basic state when viewed from the front side.

5. A grip detection system, comprising: a steering unit provided in a steering device of a vehicle and rotatably attached to the vehicle to indicate a traveling direction of the vehicle, the steering unit having a grip portion to be gripped by a driver of the vehicle; an output unit that outputs information; a touch sensor having a plurality of detection ranges, the touch sensor detecting the driver's grip in each of the plurality of detection ranges based on a change in capacitance due to the driver's approach; a control unit, The gripping portion is In a basic state in which the steering unit instructs the straight-ahead direction of the vehicle, the steering unit has a shape that is symmetrical with respect to a first plane that includes a rotation axis direction of the steering unit and a vertical direction of the vehicle, The touch sensor is The grip portion is provided along the shape of the grip portion. A cross section of the grip portion includes a conductive cloth layer made of a conductive material, the conductive cloth layer is provided in the plurality of detection areas, a first conductive cloth provided at least in a first detection range among the plurality of detection ranges, the first detection range being located on a lower side of the vehicle than a second plane including the rotation axis direction and a left-right direction of the vehicle in the basic state; a second conductive cloth provided in a second detection range, among the plurality of detection ranges, located on an upper side of the vehicle than the first detection range when the steering unit is in the basic state, on a side of the grip unit where the first conductive cloth is provided with respect to a third plane that passes through the grip unit and is perpendicular to the rotation axis of the steering unit, the first conductive cloth is made of the same material as the second conductive cloth and is thicker than the second conductive cloth; The control unit When the driver grips a predetermined reference range including a cross section of the grip portion that overlaps the second plane, detecting that the driver is gripping the grip portion; When the gripping by the driver is not detected, the output unit outputs an output indicating that the gripping portion is not being gripped. A grip detection system that does not output from the output unit when gripping by the driver is detected.

Images