Touch detection device

Abstract

To provide a touch detection device that minimizes reduction in detection accuracy and attempts cost reduction.SOLUTION: A touch detection device 10 uses a touch sensor unit 30 having a sensor electrode 36 arranged on one surface of a sensor sheet 38. Also, a cable 40 provided with a shield 44 surrounding electric wires 42 is routed through a steering wheel 14. A controller 32 makes the sensor electrode 36 and the shield 44 the same potential when detecting capacitance of the sensor electrode 36. Thus, the touch detection device 10 can reduce parts configuring the touch sensor unit 30 and minimize reduction in detection accuracy of the capacitance of the sensor electrode 36 even when the cable 40 is routed through the steering wheel 14.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a touch detection device that detects a touch by an occupant. [Background technology]

[0002] In a vehicle, a touch detection device is provided on the steering wheel, and the touch detection device detects the grip (or touch, etc.) of the steering wheel by an occupant. Generally, the touch detection device uses a capacitive touch sensor in which a sensor electrode is arranged on one side of an insulating sheet and a shield electrode is arranged on the other side, and the touch detection device detects the capacitance generated in the sensor electrode.

[0003] Generally, in a touch detection device, the detected capacitance is affected by temperature. For this reason, Patent Document 1 describes an operation detection device in which a detection electrode of a touch sensor unit is disposed in a place that is subject to the thermal influence of a heater unit, and the temperature of the heater unit is controlled based on the amount of change in the detected capacitance of the detection electrode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2017-187893 A Summary of the Invention [Problem to be solved by the invention]

[0005] Cost reduction is desired in touch detection devices, and in the case of a touch detection device, eliminating the shield electrode in the touch sensor can simplify the structure, thereby enabling cost reduction.

[0006] In a vehicle, illumination or the like is sometimes provided on the rim of the steering wheel. When illumination or the like is provided on the rim of the steering wheel, wiring connected to the illumination is routed inside the rim.

[0007] However, in a touch detection device, if wiring is arranged inside the base in the rim portion where the touch sensor is arranged without the shield electrode, parasitic capacitance occurs between the sensor electrode and the conductor in the wiring, which causes a decrease in the detection accuracy of the capacitance of the sensor electrode in the touch detection device.

[0008] The present invention has been made in consideration of the above circumstances, and has an object to provide a touch detection device that can reduce costs while suppressing a decrease in detection accuracy. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the touch detection device of a first aspect includes an operating body having a conductive core grounded to the vehicle body covered with an insulating base and touched and operated by an occupant, an internal conductor and an external conductor surrounding the entire periphery of the internal conductor, a cable arranged within the base of the operating body, a sensor unit having a sensor electrode on one side of a sheet-like support body, which is disposed on the outer periphery of the base of the operating body, and in which a capacitance is generated between the sensor electrode and the occupant contacting the operating body, a detection unit for detecting the capacitance of the sensor electrode, and a potential adjustment unit for making the sensor electrode and the external conductor of the cable the same potential when detecting the capacitance of the sensor electrode.

[0010] The touch detection device of the second aspect is the same as in the first aspect, and further includes an environmental detection means for detecting an environmental temperature of the sensor electrode, and a correction unit for correcting the capacitance detected by the detection unit based on the environmental temperature.

[0011] A touch detection device according to a third aspect is the touch detection device according to the first or second aspect, wherein the cable has a plurality of the inner conductors that are integrally surrounded by the outer conductor. Effect of the Invention

[0012] In the touch detection device of the first aspect, a conductive core part grounded to the vehicle body is covered with an insulating base body, and a cable is arranged in an operating body that is touched and operated by an occupant. A sensor part is arranged on the outer periphery of the operating body, and the sensor part is provided with a sensor electrode that generates capacitance between the operating body and the occupant when the occupant touches the operating body.

[0013] The detection section detects the capacitance of the sensor electrode, and can detect whether or not an occupant is in contact with the operating object from the capacitance detected by the detection section.

[0014] The sensor section has a sensor electrode provided on one side of a sheet-shaped support, and the sensor section has a structure using the sensor electrode and the support, thereby reducing the number of parts compared to when a shield electrode is included.

[0015] In addition, the cable has an inner conductor surrounded entirely by an outer conductor, and the potential adjustment section sets the sensor electrode and the outer conductor of the cable at the same potential when the detection section detects the capacitance of the sensor electrode.

[0016] Therefore, even if the sensor unit has a simple configuration in which a sensor electrode is provided on a support, it is possible to suppress the occurrence of parasitic capacitance between the sensor electrode and the internal conductor of the cable, and even if a sensor unit with a reduced number of components is used, it is possible to suppress a decrease in the detection accuracy of the capacitance.

[0017] In the touch detection device of the second aspect, the environmental detection means detects the environmental temperature of the sensor electrode. The correction unit corrects the capacitance detected by the detection unit based on the environmental temperature. This makes it possible to suppress a decrease in the detection accuracy of the capacitance even if the parasitic capacitance between the sensor electrode and the core changes depending on the environmental temperature.

[0018] In the touch detection device of the third aspect, a cable in which multiple internal conductors are integrally surrounded by an external conductor is used, and the cable is arranged in the operation body. Therefore, even if the current or voltage flowing through the internal conductor changes, the capacitance generated in the sensor electrode can be prevented from changing, and the deterioration of the detection accuracy of the capacitance when the cable is arranged in the operation body can be effectively prevented. [Brief description of the drawings]

[0019] [Figure 1] 1 is a schematic configuration diagram of a touch detection device according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a front view showing a schematic configuration of a steering wheel. [Diagram 3] Each of (A) to (C) is a schematic diagram showing the main parts of a steering wheel, where (A) shows a steering wheel according to this embodiment, (B) shows a steering wheel in which an unshielded cable is arranged, and (C) shows a steering wheel in which no cable is arranged inside. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The touch detection device 10 according to this embodiment is provided in a steering device 12, and the steering device 12 functions as an example of an operating device operated by a passenger (driver) in a vehicle. Fig. 1 shows a schematic configuration diagram of the touch detection device 10, and Fig. 2 shows a front view of a main part of the steering device 12 as seen from the passenger's perspective. In the drawings, the right side in the vehicle width direction is indicated by an arrow HR, and the upward direction is indicated by an arrow UP.

[0021] As shown in Fig. 2, the steering device 12 includes a steering wheel 14 as an operating body and a steering body operated by a passenger. The steering wheel 14 is disposed in front of a seat (driver's seat) in which a passenger who drives the vehicle sits. The steering wheel 14 is composed of a substantially annular rim portion 16 as a gripping portion, a boss portion 18 provided at the center of the rim portion 16, and a stay portion 20 connecting the rim portion 16 and the boss portion 18, and the steering wheel 14 is formed in a substantially annular shape. In the drawing, the radial direction of the steering wheel 14 is indicated by an arrow R.

[0022] The steering wheel 14 has a metal core (not shown) as the core that forms the framework, and the core is made up of a substantially annular rim core portion 24 of the rim portion 16, a boss core portion of the boss portion 18, and a stay core portion of the stay portion 20. The rim core portion 24 and the boss core portion are connected by the stay core portion, so that the rim portion 16, the boss portion 18, and the stay portion 20 are integrated into one body.

[0023] The steering device 12 includes a steering shaft (not shown), which is rotatably supported by the vehicle body at the front of the driver's seat with its axis aligned approximately in the vehicle front-rear direction. The steering wheel 14 is supported by the vehicle body such that the boss core portion of the boss portion 18 is fixed to the vehicle rear end of the steering shaft, and the steering wheel 14 is rotatable together with the steering shaft. Therefore, the core of the steering wheel 14 is grounded to the vehicle body via the steering shaft.

[0024] In a vehicle, the steering wheel 14 of the steering device 12 is rotated to rotate the steering shaft and turn the steered wheels (front wheels) to steer the vehicle. Note that Fig. 2 shows the steering wheel 14 when the vehicle is traveling straight ahead.

[0025] As shown in Fig. 1, a base 22 made of a resin material such as urethane as an insulating material is disposed on the rim portion 16 of the steering wheel 14. The base 22 covers a rim core metal portion 24 of the rim portion 16, and the rim core metal portion 24 is housed within the base 22 by insert molding. Note that Fig. 1 shows a schematic cross section of a main portion of the rim portion 16 taken along the circumferential direction of the rim portion 16.

[0026] The steering wheel 14 has a decorative portion 26 disposed as a contact portion (skin) on the outer periphery of the base body 22, and the decorative portion 26 is made of leather or resin (a part of the decorative portion may be made of wood) and has insulating properties. The rim portion 16 of the steering wheel 14 is covered with the decorative portion 26 over the entire circumference of the base body 22 in the radial cross section of the steering wheel 14 and over the entire circumference (entire area) in the circumferential direction of the steering wheel 14.

[0027] As a result, in the rim portion 16 of the steering wheel 14, the rim core metal portion 24 constitutes the ground (GND) portion, the outside of the rim core metal portion 24 serves as the base body 22, and the decorative portion 26 is disposed on the outside of the base body 22.

[0028] The touch detection device 10 detects the touch of an occupant with the rim portion 16 of the steering wheel 14 and makes it possible to determine whether or not the occupant is gripping the rim portion 16 of the steering wheel 14 .

[0029] The touch detection device 10 is of a capacitance type (self-capacitance type), and includes a touch sensor unit 30 as a sensor unit for detecting the approach of an occupant, and a controller 32. The touch detection device 10 also includes a temperature sensor 34 as an environment detection means, and the temperature sensor 34 detects the temperature out of the temperature (environmental temperature) and humidity (environmental humidity).

[0030] The touch sensor unit 30 of the touch detection device 10 includes a sensor electrode 36 and a sensor sheet 38 serving as a support. The sensor electrode 36 and the sensor sheet 38 are each in the form of a long sheet (film), and the touch sensor unit 30 has a two-layer structure in which the sensor electrode 36 is disposed on one side of the sensor sheet 38. The sensor electrode 36 is made of a conductive metal (copper foil), and the sensor sheet 38 is made of a resin material serving as an insulating material (dielectric).

[0031] The touch sensor unit 30 is disposed on the outer periphery of the base body 22 with the sensor sheet 38 facing the base body 22 in the rim portion 16 of the steering wheel 14. The touch sensor unit 30 is disposed over substantially the entire outer periphery of the base body 22 (substantially the entire area in the circumferential direction of the cross section of the rim portion 16) within a predetermined range in the circumferential direction of the steering wheel 14.

[0032] Thereby, when the occupant touches the rim portion 16 (decorative portion 26) by gripping the rim portion 16 of the steering wheel 14, the occupant's hand is brought close to the sensor electrode 36 of the touch sensor portion 30.

[0033] 2, the touch detection device 10 uses two touch sensor units 30 (30L, 30R), with the touch sensor unit 30L arranged in a range of approximately half the circumference on the left side in the vehicle width direction in the circumferential direction of the steering wheel 14, and the touch sensor unit 30R arranged in a range of approximately half the circumference on the right side in the vehicle width direction. As a result, when an occupant grips the steering wheel 14 (rim portion 16), the occupant's left hand is brought close to the touch sensor unit 30L, and the occupant's right hand is brought close to the touch sensor unit 30R. In the touch sensor unit 30, when the occupant touches the rim portion 16, a capacitance is generated between the sensor electrode 36 and the occupant.

[0034] In the touch detection device 10, the touch sensor units 30L and 30R have substantially the same configuration, and in the following, when there is no need to distinguish between the touch sensor units 30L and 30R, they will be described as the touch sensor unit 30. In addition, the touch detection device 10 uses two touch sensor units 30L and 30R as an example, but is not limited thereto, and three or more touch sensor units 30 may be used and arranged in the circumferential direction of the steering wheel 14 in the rim portion 16.

[0035] The temperature sensor 34 of the touch detection device 10 is positioned near the steering wheel 14 or near the rim portion 16 of the steering wheel 14 (for example, the boss portion 18 or the stay portion 20) and detects the temperature of the rim portion 16 (ambient temperature, environmental temperature).

[0036] Meanwhile, various electrically operated electrical components such as illumination (not shown) can be disposed on the rim portion 16 of the steering wheel 14. The electrical components are disposed on the rim portion 16 between the touch sensor portion 30L and the touch sensor portion 30R, or in a portion where a part of the touch sensor portion 30 (30L, 30R) has been removed.

[0037] When electrical components such as illumination are arranged on the rim portion 16 of the steering wheel 14, a cable 40 is arranged in the steering wheel 14 as electrical wiring for connecting the electrical components to equipment on the vehicle body side (for example, a power source for the electrical components or a control device for sending control signals to the electrical components).

[0038] In the steering device 12, the cable 40 is routed from the rim portion 16 through the stay portion 20 to the boss portion 18. At this time, in the steering wheel 14, the cable 40 is routed by embedding the cable 40 in the base body 22 in the rim portion 16 (or fitting into a groove portion formed in the base body 22). This prevents the occupant from feeling that the cable 40 is routed inside the rim portion 16 when gripping the rim portion 16 (causing the occupant to feel uncomfortable).

[0039] The steering device 12 in which the touch detection device 10 is provided uses a so-called shielded cable as the cable 40, in which an electric wire (core wire) 42 as an inner conductor is surrounded by a shield 44 as an outer conductor. In the cable 40, the electric wire 42 is housed in an insulating sheath, and the outer periphery of this sheath is covered with the shield 44, and the shield 44 is covered with an insulating protective layer.

[0040] The shield 44 may be made of a metal foil or a braid of metal wires, and the shield 44 surrounds the entire circumference of the electric wires 42 in the cable 40 using a conductive material.

[0041] Such a cable 40 may be a coaxial cable in which a shield 44 is arranged to surround the outer periphery of an electric wire 42 arranged at the axial center. The cable 40 may have a structure in which each of the electric wires 42 is surrounded by the shield 44 (individual shielding), or a structure in which the shield 44 is arranged to surround the electric wires 42 as a whole (collective shielding). In the cable 40 according to this embodiment, two electric wires 42 are surrounded as a whole by the shield 44.

[0042] As a result, in the touch detection device 10, the base 22 or the base 22 and the cable 40 are disposed directly below the touch sensor portion 30 (radially inside the rim portion 16).

[0043] In the touch detection device 10, the touch sensor unit 30 (touch sensor units 30L, 30R) and the temperature sensor 34 are each electrically connected to the controller 32. In addition, the shield 44 of the cable 40 is electrically connected to the controller 32. When a plurality of cables 40 face one touch sensor unit 30, the shields 44 of the cables 40 may be connected together to the controller 32. When separate cables 40 face two touch sensor units 30 (30L, 30R), the shields 44 may be connected together to the controller 32 or may be connected separately to the controller 32.

[0044] The controller 32 includes a microcomputer in which a CPU, a ROM, a RAM, and a non-volatile storage are connected by a bus, as well as required functional circuits (all not shown). In the controller 32, the CPU reads out and executes a touch detection program stored in the ROM and the storage, thereby realizing a touch detection function using the required functional circuits. Note that the controller 32 may be implemented using a field programmable gate array (FPGA), a programmable logic array (PLA), or the like.

[0045] The controller 32 is provided with a detection section 50, a correction section 52, and a potential adjustment section 54. The controller 32 may also be provided with a determination section 56.

[0046] When an occupant comes into contact with the rim portion 16, a capacitance is generated between the sensor electrode 36 disposed on the rim portion 16 and the occupant. Also, a parasitic capacitance may be generated between the sensor electrode 36 and the rim core metal portion 24. This parasitic capacitance changes depending on the dielectric constant of the insulating material used in the base 22, etc., and the dielectric constant of the base 22 changes depending on the temperature of the base 22, etc.

[0047] Here, the detection unit 50 is provided for each touch sensor unit 30, and detects (measures) the capacitance generated in the sensor electrode 36 by applying a self-capacitance method. The correction unit 52 corrects the parasitic capacitance generated in the sensor electrode 36 based on the dielectric constant of the base 22 etc. and the temperature detected by the temperature sensor 34, thereby correcting the capacitance of the sensor electrode 36.

[0048] In addition, the controller 32 may have the detection unit 50, the correction unit 52 and the potential adjustment unit 54 separated for the touch sensor unit 30L and the touch sensor unit 30R, or may have one set of the detection unit 50, the correction unit 52 and the potential adjustment unit 54, and may alternately perform touch detection for the touch sensor unit 30L and touch detection for the touch sensor unit 30R.

[0049] A parasitic capacitance occurs between the sensor electrode 36 and the rim core metal portion 24 according to the dielectric constant of the insulating material forming the base 22 and the sensor sheet 38. The dielectric constant of the base 22 and the sensor sheet 38 changes according to the temperature (ambient temperature) of the base 22 (and the sensor sheet 38). A correction coefficient for the parasitic capacitance is set and stored in advance in the correction unit 52 based on the change in the dielectric constant of each of the base 22 and the sensor sheet 38 with respect to temperature. The correction unit 52 sets the correction coefficient according to the temperature detected by the temperature sensor 34. This allows the detection unit 50 to output the capacitance excluding the parasitic capacitance as the capacitance of the sensor electrode 36.

[0050] The determination unit 56 determines whether or not the occupant is in contact with the steering wheel 14 based on whether or not the corrected capacitance exceeds a preset threshold value (criterion value). At this time, the touch detection device 10 uses the touch sensor units 30L and 30R to make it possible to determine whether or not each of the left and right hands of the occupant is in contact with the rim portion 16.

[0051] When the detection unit 50 detects the capacitance of the sensor electrode 36, the potential adjustment unit 54 supplies power (a predetermined current) to each of the sensor electrode 36 and the shield 44 of the cable 40 so that the sensor electrode 36 and the shield 44 of the cable 40 have the same potential. In this way, the potential adjustment unit 54 puts the sensor electrode 36 into a charged state according to the capacitance while keeping the sensor electrode 36 at the same potential as the shield 44. The detection unit 50 detects the charged state of the sensor electrode 36.

[0052] Next, the operation of this embodiment will be described. In the touch detection device 10, a touch sensor unit 30 (30L, 30R) is disposed on a steering wheel 14 (rim portion 16) of a steering device 12. Therefore, when an occupant grips (touches, holds) the steering wheel 14 in an operable manner, the occupant's hand approaches a sensor electrode 36 of the touch sensor unit 30, and the capacitance of the sensor electrode 36 increases.

[0053] In the controller 32 of the touch detection device 10, the detection unit 50 detects the capacitance of the sensor electrode 36, and the determination unit 56 determines whether the occupant has touched the steering wheel 14 based on the detected capacitance.

[0054] Incidentally, in the touch detection device 10, the touch sensor unit 30 has a structure in which the sensor electrode 36 is arranged on the sensor sheet 38, and the touch sensor unit 30 has a structure in which the shield electrode is removed from the surface of the sensor sheet 38 opposite the sensor electrode 36. As a result, in the touch detection device 10, the number of components of the touch sensor unit 30 is reduced and assembly is simplified, thereby enabling cost reduction.

[0055] When the sensor sheet 38 is provided with a sensor electrode 36 and a shield electrode (not shown), parasitic capacitance can be suppressed by setting the shield electrode to the same potential as the sensor electrode 36. Therefore, even if the rim core metal part 24 or a cable (electric wire 42) is present directly below the sensor electrode 36, it is possible to accurately detect the capacitance generated in the sensor electrode 36. Furthermore, temperature changes in the detected capacitance are suppressed.

[0056] However, in the touch sensor unit 30 in which the shield electrode is omitted, parasitic capacitance is likely to occur in the sensor electrode .

[0057] 3(A) to 3(C) are schematic cross-sectional views of the rim portion 16, which is a main portion of the steering wheel 14, cut in the circumferential direction of the steering wheel 14. FIG. 3(A) shows a state in which the cable 40 is disposed directly below the sensor electrode 36, and FIG. 3(C) shows a state in which the cable 40 is not disposed directly below the sensor electrode 36. FIG. 3(B) shows a state in which the cable 46, which does not have a shield 44, is disposed directly below the sensor electrode 36.

[0058] 3(C), in a touch sensor unit 30 that does not have a shield electrode, if the parasitic capacitance (electrostatic capacitance) occurring mainly between the sensor electrode 36 and the rim core metal portion 24 is regarded as Cx, this parasitic capacitance Cx affects the dielectric constant of the base 22 and the dielectric constant of the sensor sheet 38. From this, by using a coefficient α determined by the dielectric constant of the base 22 and the dielectric constant of the sensor sheet 38, a correction value Δx of the parasitic capacitance Cx for obtaining the capacitance C of the sensor electrode 36 can be set as Δx = α·Cx.

[0059] Here, the correction coefficient α can be set according to the dielectric constant of the base 22, the dielectric constant of the sensor sheet 38, and the rate of change of each dielectric constant with respect to temperature. That is, the dielectric constant and the rate of change of the dielectric constant of the base 22 with respect to temperature are determined by the insulating material used for the base 22, and the dielectric constant and the rate of change of the dielectric constant of the sensor sheet 38 with respect to temperature are determined by the insulating material used for the sensor sheet 38. From this, the correction coefficient α that changes with the environmental temperature can be determined by performing measurements, calculations, etc. in advance. By using this correction coefficient α, the capacitance C of the sensor electrode 36 of the touch sensor unit 30 can be easily obtained.

[0060] On the other hand, as shown in FIG. 3B, when a cable 46 is present directly below the sensor electrode 36 in the touch sensor unit 30, the parasitic capacitance (electrostatic capacitance) of the sensor electrode 36 includes a parasitic capacitance with the rim core metal part 24 and a parasitic capacitance with each of the electric wires 42 of the cable 46. In this case, the parasitic capacitance between the sensor electrode 36 and the rim core metal part 24 is affected by the area of ​​the overlapping part with the cable 46, etc. In addition, the parasitic capacitance between the sensor electrode 36 and each of the electric wires 42 of the cable 46 is affected by the length and wiring state of the electric wires 42, the dielectric constant of the insulating material covering the electric wires 42 (including the dielectric constant of the sensor sheet 38), and the temperature change of these dielectric constants. For this reason, the parasitic capacitance of the sensor electrode 36 differs for each steering device 12, and the change in the parasitic capacitance with respect to temperature also differs for each temperature.

[0061] For this reason, if the cable 46 is routed directly below the sensor electrode 36, it becomes substantially difficult to correct the capacitance of the sensor electrode 36, and it becomes difficult for the touch detection device 10 to detect the capacitance with high accuracy.

[0062] 3A, in the steering device 12, a cable 40 provided with a shield 44 is arranged inside the base 22. In addition, in the touch detection device 10, when detecting the capacitance of the sensor electrode 36, the shield 44 of the cable 40 is set to the same potential as the sensor electrode 36.

[0063] As a result, in the touch detection device 10, the occurrence of parasitic capacitance between the sensor electrode 36 and the electric wire 42 of the cable 40 can be suppressed, and when detecting the capacitance of the sensor electrode 36, it is only necessary to consider the parasitic capacitance occurring mainly between the sensor electrode 36 and the rim core portion 24.

[0064] In this case, if the parasitic capacitance Cy is considered to be caused by the rim core metal portion 24, the parasitic capacitance Cy is affected by the dielectric constant of the base 22, the dielectric constant of the sensor sheet 38, and also by the area of ​​the rim core metal portion 24 where the cable 40 overlaps. Therefore, when the cable 40 is routed in the rim portion 16, the parasitic capacitance Cy is mainly affected by the dielectric constant of the base 22 and the dielectric constant of the sensor sheet 38. Therefore, in the touch sensor portion 30 where the cable 40 is routed directly below, by using a coefficient β determined by the dielectric constant of the base 22 and the dielectric constant of the sensor sheet 38, the correction value Δx of the parasitic capacitance Cy to obtain the capacitance C of the sensor electrode 36 can be set as Δx = α·Cy.

[0065] Here, the correction coefficient β can be set according to the dielectric constant of the base 22, the dielectric constant of the sensor sheet 38, and the rate of change of each dielectric constant with respect to temperature, as well as the area in which the cable 40 hides the rim core metal portion 24 as viewed from the sensor electrode 36. That is, the dielectric constant and the rate of change of the dielectric constant with respect to temperature of the base 22 are determined by the insulating material used for the base 22, and the dielectric constant and the rate of change of the dielectric constant with respect to temperature of the sensor sheet 38 are determined by the insulating material used for the sensor sheet 38. In addition, the area in which the cable 40 affects the parasitic capacitance is obtained from the outer diameter and length of the cable 40.

[0066] In addition, the correction coefficient β, which changes depending on the environmental temperature, can be determined in advance by performing measurements, calculations, etc. By using this correction coefficient β, the detection unit 50 can easily and accurately detect the capacitance C of the sensor electrode 36 of the touch sensor unit 30 (detection errors are suppressed).

[0067] As a result, in the touch detection device 10, a correction coefficient α that includes temperature changes is set for the touch sensor unit 30 that is not opposed to the cable 40, and a correction coefficient β that includes temperature changes is set for the touch sensor unit 30 that is opposed to the cable 40.

[0068] In the touch detection device 10, the capacitance of the sensor electrode 36 is detected for each touch sensor unit 30, and a change in the capacitance is detected. At this time, in the touch detection device 10, the correction unit 52 sets a correction coefficient α or β based on the temperature detected by the temperature sensor 34, and corrects the detected capacitance. The determination unit 56 determines whether or not an occupant is touching the steering wheel 14 from the corrected capacitance. In this way, in the touch detection device 10, a decrease in the detection accuracy of whether or not an occupant is touching the steering wheel 14 is suppressed.

[0069] In this manner, the touch detection device 10 uses the touch sensor unit 30 that is configured with the sensor electrode 36 and the sensor sheet 38. Therefore, in the touch detection device 10, the number of components in the touch sensor unit 30 can be reduced to simplify the configuration, thereby enabling cost reduction.

[0070] Furthermore, in the touch detection device 10, a shield 44 is provided on the cable 40 arranged in the steering wheel 14, and when detecting the capacitance of the sensor electrode 36, the shield 44 of the cable 40 and the sensor electrode 36 are set to the same potential. This makes it possible to suppress the influence of the electric wire 42 of the cable 40 on the parasitic capacitance generated in the sensor electrode 36. This makes it possible to suppress capacitance detection errors caused by the electric wire 42 of the cable 40, and enables highly accurate detection of the capacitance of the sensor electrode 36.

[0071] Furthermore, by providing the shield 44 on the cable 40, the potential of the electric wire 42 and the current flowing through the electric wire 42 do not affect the capacitance of the sensor electrode 36, and the touch detection device 10 is able to perform highly accurate touch detection even if the cable 40 is routed to the steering wheel 14. Moreover, the cable 40 has multiple electric wires 42 collectively surrounded by the shield 44, and the shield 44 is covered with a protective layer, making it easy to route the cable 40 to the steering wheel 14.

[0072] In this embodiment, the steering body is described by taking the steering wheel 14 having a substantially circular ring shape as an example. However, the steering body is not limited to a substantially circular ring shape, and may be a substantially rectangular irregular steering wheel in which a pair of grip parts are arranged on the left and right sides of a boss part and each grip part is connected to the boss part at one or more points, or may be a D-shape (flat bottom shape) or the like.

[0073] In addition, in the present embodiment, the steering wheel 14 provided in the steering device 12 has been described as an example of the operating object. However, the operating object may be any of various operating objects that are gripped or touched by an occupant in a vehicle, such as a shift lever of a shift device. [Explanation of symbols]

[0074] 10...touch detection device, 14...steering wheel (operating body), 16...rim portion, 22...base, 24...rim core portion (core portion), 30...touch sensor portion (sensor portion), 32...controller, 34...temperature sensor (environment detection means), 36...sensor electrode, 38...sensor sheet (support), 40...cable, 42...electric wire (inner conductor), 44...shield (outer conductor), 50...detection portion, 52...correction portion, 54...potential adjustment portion.

Claims

1. an operating body having a conductive core portion grounded to a vehicle body and covered with an insulating base body, the operating body being operated by being touched by a vehicle occupant; a cable including an inner conductor and an outer conductor surrounding the inner conductor, the cable being disposed within the base of the operating body; a sensor section in which a sensor electrode is provided on one surface of a sheet-like support, the sensor section being disposed on an outer periphery of the base body of the operating body, and in which capacitance is generated between the sensor electrode and an occupant who touches the operating body; A detection unit for detecting the capacitance of the sensor electrode; a potential adjusting unit for adjusting the potential of the sensor electrode and the outer conductor of the cable to the same potential when detecting the capacitance of the sensor electrode; 2. A touch detection device comprising:

2. An environment detection means for detecting an environmental temperature of the sensor electrode; a correction unit that corrects the capacitance detected by the detection unit based on the environmental temperature; The touch detection device of claim 1 , further comprising:

3. The touch detection device according to claim 1 , wherein the cable has a plurality of the inner conductors integrally surrounded by the outer conductor.

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