Touch detection device

Abstract

A touch detection device is provided. The touch detection device includes: a turning body; a plurality of sensor units that generate capacitance between a sensor electrode disposed on the outer peripheral portion of the base body of the steering body and an occupant in contact with the steering body; a detection unit for detecting the capacitance of each of the sensor electrodes; a correction unit that corrects the capacitance of each of the sensor electrodes detected by the detection unit, using a difference indicating a change in the capacitance of each of the sensor electrodes detected by the detection unit; and a determination unit that determines, on the basis of the corrected capacitance, the state of contact with the steering body by the occupant.

Description

Technical Field

[0001] This disclosure relates to a touch detection device for detecting occupant contact. Background Technology

[0002] Japanese Patent Application Publication No. 2017-87883 discloses a contact determination processing device. The contact determination processing device has a shielding layer formed on the core (and heater layer) side, which is designed for a contact sensor whose output changes according to the contact state of the occupant's contact with the steering wheel and the non-contact state of no contact.

[0003] In this contact determination processing device, a contact state is determined when the output of the contact sensor is above a predetermined threshold, and a non-contact state is determined when the output is below the predetermined threshold. At this time, the contact determination processing device detects the steering wheel temperature, ambient temperature, or estimated temperature, and adjusts the threshold based on the detected or estimated temperature. Furthermore, in the contact determination processing device, if the heater used to heat the steering wheel is activated, the threshold is lowered by a predetermined value from the time it is activated until a predetermined time has elapsed or until a predetermined temperature is reached.

[0004] In vehicles, there is a desire to reduce the cost of structures used to detect occupants' touch on the steering wheel. By removing the shielding layer (shielding electrode) from the steering wheel or touch sensor, the construction can be simplified and the cost reduced.

[0005] Furthermore, the dielectric constant and other properties of the insulating material sandwiched between the sensor electrode, the core, and the heater change with temperature. Therefore, a problem arises when the shielding electrode positioned on the core side of the sensor electrode is removed; the temperature change within the vehicle interior alters the parasitic capacitance generated by the sensor electrode, leading to a decrease in the detection accuracy of touch detection using the sensor electrode. Summary of the Invention

[0006] This disclosure provides a touch detection device that can suppress the reduction in detection accuracy in touch detection of occupant contact with the steering wheel.

[0007] The first type of touch detection device includes: a steering body formed by covering an insulating substrate with a conductive core portion grounded to the vehicle body, and for steering the vehicle by contact and operation by an occupant; a plurality of sensor units that generate electrostatic capacitance between sensor electrodes respectively disposed at the outer periphery of the substrate of the steering body and an occupant in contact with the steering body; a detection unit for detecting the electrostatic capacitance of each of the sensor electrodes; a correction unit for correcting the electrostatic capacitance of each of the sensor electrodes detected by the detection unit using a difference representing a change in the electrostatic capacitance of each of the sensor electrodes detected by the detection unit; and a determination unit for determining the contact state of the occupant with the steering body based on the corrected electrostatic capacitance.

[0008] In the second type of touch detection device, based on the first type, the sensor electrode is provided on one side of the sheet-like insulating support and is opposite to the core portion.

[0009] For the touch detection device of the third type, based on the first or second type, the sensor electrodes are arranged in pairs in the steering body in the vehicle width direction.

[0010] For the touch detection device of the fourth method, based on any of the first to third methods, the correction unit includes setting a correction value for correcting the electrostatic capacitance of each of the sensor electrodes using the absolute value of the difference between the sensor electrodes.

[0011] For the touch detection device of the fifth method, based on the fourth method, a temperature detection unit is included to detect changes in the ambient temperature around the steering body, and the correction unit sets the correction value based on each of the differences and the changes in the ambient temperature.

[0012] For the touch detection device of the sixth method, based on the fourth or fifth method, the calibration unit includes a reference value setting unit. The reference value setting unit sets an initial value of the reference value of the electrostatic capacitance of each of the sensor electrodes based on the electrostatic capacitance of each of the sensor electrodes in the state where the occupant does not touch the steering body, and updates the reference value using the calibration value. The calibration unit calibrates the electrostatic capacitance of each of the sensor electrodes using the updated reference value for each of the sensor electrodes.

[0013] For the touch detection device of the seventh method, based on any one of the methods 4 to 6, the correction unit evaluates whether the correction value is insufficient for a preset threshold. If the evaluation finds that the correction value is insufficient for the threshold, the correction value is used to correct the electrostatic capacitance of each of the sensor electrodes.

[0014] For the touch detection device of the eighth method, based on any one of the methods 1 to 7, a heating part is included, which is disposed in the base of the steering body and heats the steering body through operation.

[0015] For the touch detection device of the ninth method, based on the eighth method which refers to the seventh method, the threshold is changed according to the operating state of the heating unit.

[0016] For the touch detection device of the 10th method, based on the 9th method, the threshold for the case where the heating element is activated is set higher than the threshold for the case where the heating element is not activated.

[0017] In the touch detection device of the first aspect of this disclosure, in a steering body where the vehicle is steered by an occupant touching and operating the steering body, a core portion covered by an insulating substrate is grounded to the vehicle body. Multiple sensor units are disposed on the steering body. For each sensor unit, each sensor electrode is disposed on the outer periphery of the steering body substrate, and the sensor electrode generates electrostatic capacitance between itself and the occupant in contact with the steering body. A detection unit detects the electrostatic capacitance of each sensor electrode, and a determination unit determines the occupant's contact state with the steering body based on the electrostatic capacitance of each sensor electrode after correction in a correction unit.

[0018] On the other hand, parasitic capacitance is generated between the sensor electrode and the core, heater, etc. The parasitic capacitance is manifested by the electrostatic capacitance of the sensor electrode. Due to temperature changes in the substrate, the parasitic capacitance changes, thereby changing the electrostatic capacitance manifested by the sensor electrode.

[0019] Here, the calibration unit corrects the electrostatic capacitance of each sensor electrode detected by the detection unit using the difference expressed as the change in electrostatic capacitance of each sensor electrode detected by the detection unit. Therefore, even if the electrostatic capacitance changes due to changes in parasitic capacitance or other factors in the sensor electrode, the calibration unit can suppress this change in electrostatic capacitance.

[0020] In the second type of touch detection device, a sensor electrode is provided on one surface of a sheet-like insulating support, and the sensor electrode is positioned opposite the core portion. Furthermore, the sensor portion does not have a shielding electrode that provides electrical shielding between the sensor electrode and the core portion.

[0021] Here, the calibration unit uses the difference, expressed as the change in electrostatic capacitance of each sensor electrode detected in the detection unit, to correct the electrostatic capacitance of each sensor electrode detected in the detection unit. Therefore, without providing shielding electrodes between the sensor electrodes and the core assembly, even if changes in parasitic capacitance or other factors alter the electrostatic capacitance of the sensor electrodes, the contact state of the occupant with the steering mechanism can be determined with high accuracy.

[0022] In the third type of touch detection device, sensor electrodes are arranged in pairs along the left and right sides of the steering body in the vehicle width direction. This allows for high-precision determination of whether the occupant is using both hands or one hand to operate the steering body.

[0023] In the touch detection device of the fourth type, the calibration unit uses the absolute value of the difference between each sensor electrode to set a calibration value for correcting the electrostatic capacitance of each sensor electrode. The change in electrostatic capacitance caused by the change in parasitic capacitance differs from the change in electrostatic capacitance caused by the occupant's contact state with the steering mechanism, and is less significant than the change caused by the occupant's contact state with the steering mechanism. Here, for example, by using the difference with the smaller absolute value among multiple differences, it is possible to suppress the situation where the electrostatic capacitance is not necessarily corrected significantly.

[0024] In the touch detection device of the fifth method, the temperature detection unit detects changes in the ambient temperature of the steering body, and the calibration unit sets calibration values ​​based on the differences and changes in ambient temperature. Since the parasitic capacitance of the sensor electrodes changes with temperature, a more appropriate calibration value can be set by using changes in ambient temperature in the setting of the calibration value.

[0025] In the touch detection device of the sixth method, the reference value setting unit sets an initial value for the electrostatic capacitance of each sensor electrode based on the electrostatic capacitance of each sensor electrode when the occupant is not in contact with the steering body, and updates each reference value using a correction value. The correction unit uses the updated reference value for each sensor electrode to correct the electrostatic capacitance of each sensor electrode.

[0026] Here, the reference value becomes the electrostatic capacitance, which mainly corresponds to the parasitic capacitance. By updating this reference value from the initial value using a correction value, the electrostatic capacitance of each sensor electrode is corrected using the reference value after correction (updated) for each sensor electrode. Thus, the contact state can be determined (touch detection) with high accuracy using the corrected electrostatic capacitance.

[0027] In the touch detection device of the seventh method, an evaluation is performed to determine whether the correction value is insufficient for a preset threshold. If the evaluation indicates that the correction value is insufficient for the threshold, the correction value is used to correct the electrostatic capacitance of each sensor electrode. This prevents the electrostatic capacitance of each sensor electrode from being significantly corrected beyond what is necessary.

[0028] In the touch detection device of the eighth method, a heating element is provided in the base of the steering body to heat the steering body by operation. Therefore, the parasitic capacitance of each sensor electrode increases due to the operation of the heating element, which in turn increases the change in electrostatic capacitance. However, since the detected electrostatic capacitance can be corrected according to the change in electrostatic capacitance, the decrease in the accuracy of contact state determination (touch detection) can be suppressed.

[0029] In the touch detection device of the ninth embodiment, the threshold is changed according to the operating state of the heating element. Furthermore, in the touch detection device of the tenth embodiment, the threshold when the heating element is operating is set higher than the threshold when the heating element is not operating. Therefore, when the heating element is operating, the correction value can be larger, and thus, the electrostatic capacitance of each sensor electrode can be properly corrected. Attached Figure Description

[0030] Figure 1 This is a block diagram showing the general structure of the touch detection device according to this embodiment.

[0031] Figure 2 This is a general front view showing the steering wheel.

[0032] Figure 3 It is a cross-sectional view taken radially to show the main parts of the steering wheel.

[0033] Figure 4 It represents the threshold Th BASE A diagram illustrating an example of the settings.

[0034] Figure 5A It is a line graph illustrating the change in temperature (ambient temperature) corresponding to changes in time.

[0035] Figure 5B This is a line graph illustrating the change in electrostatic capacitance corresponding to changes in time.

[0036] Figure 5C It means based on Figure 5A and Figure 5B A line graph showing the change of the baseline value corresponding to the change in time. Detailed Implementation

[0037] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings.

[0038] The touch detection device 10 involved in this embodiment is installed on the steering device 12 of the vehicle to detect whether the occupant is holding the steering wheel 14 of the steering device 12.

[0039] Figure 1 The schematic structure of the touch detection device 10 is shown in the block diagram. Furthermore, Figure 2 In the diagram, a general outline of the steering wheel 14 of the steering device 12 is shown from the perspective of the occupant's view. Figure 3 The figure shows the general structure of the main parts of the steering wheel 14 in a cross-sectional view when viewed radially. Additionally, in the figure, the right side in the vehicle width direction is indicated by arrow HR, and the top by arrow UP.

[0040] The steering device 12 functions as an operating device operated by the occupant (driver) in the vehicle. Furthermore, a steering wheel 14 is disposed on the steering device 12. The steering wheel 14 is located on the front side of the seat (driver's seat, not shown) where the occupant (driver) sits to operate the vehicle, and functions as both an operating element and a steering element operated by the occupant.

[0041] like Figure 2 As shown, the steering wheel 14 includes: a generally annular rim portion 16 serving as a grip portion, a hub portion 18 disposed at the center of the rim portion 16, and a support portion 20 connecting the rim portion 16 and the hub portion 18. Furthermore, in the accompanying drawings, the radial direction of the steering wheel 14 is indicated by arrow R.

[0042] The steering wheel 14 has a metal core that forms the frame. The core consists of a generally annular disc rim core 24, described below (see also disc rim core 24). Figure 3 The wheel 14 is composed of the hub core portion (not shown) of the hub portion 18 and the support strip core portion (not shown) of the support strip portion 20. For the steering wheel 14, the hub core portion and the rim core portion 24 are connected by the support strip core portion, and the rim portion 16, the hub portion 18 and the support strip portion 20 are integrated.

[0043] The steering device 12 has a steering shaft (not shown), which is located on the front side of the vehicle at the driver's seat. The axis direction is set in a generally longitudinal direction of the vehicle and is supported by the vehicle body to be rotatable. The hub portion 18 of the steering wheel 14 is fixed to the rear end of the steering shaft on the vehicle side. The steering wheel 14 can rotate integrally with the steering shaft and is supported by the vehicle body. The hub portion is grounded to the vehicle body via the steering shaft.

[0044] In the vehicle, the steering wheel 14 of the steering system 12 is rotated, thereby rotating the steering shaft and turning the steering wheels (front wheels) to perform steering operations. Additionally, Figure 2 The image shows the steering wheel 14 when the vehicle is traveling straight.

[0045] like Figure 3 As shown, a substrate 22 made of a resin material such as polyurethane as an insulating material is disposed on the rim portion 16 of the steering wheel 14. The substrate 22 covers the rim core portion 24 of the rim portion 16, and the rim core portion 24 is housed within the substrate 22 by an insert forming. Furthermore, Figure 3 The image shows a schematic cross-section of the main portion of the rim 16 along the circumference of the rim 16 in an unfolded state.

[0046] The steering wheel 14 has a decorative part 26, which serves as a contact part (skin), arranged on the radial outer side of the base 22. The decorative part 26 is made of leather or resin (or partially of wood), thus providing insulation. For the rim portion 16 of the steering wheel 14, the entire radial circumference of the steering wheel 14 and the entire circumferential circumference (full area) of the steering wheel 14 are covered by the decorative part 26.

[0047] Furthermore, the steering device 12 can be equipped with a heater (electric heater) 30 as a heating element (heating unit) on the steering wheel 14. Additionally, Figure 1 and Figure 2 The diagram shows a portion of heater 30.

[0048] For the heater 30, heating wires or the like are used to surround approximately the entire circumference of the outer peripheral surface of the base 22 within the disc rim 16, and are provided within a desired range (e.g., approximately the entire circumference) of the outer peripheral surface of the base 22 in the circumferential direction of the steering wheel 14. The heater 30 is attached to a support plate 32 that functions as a base using insulating material and polyurethane foam, etc., as a support member. The support plate 32 is located radially outside the disc rim 16 and is attached to the outer peripheral surface of the base 22.

[0049] On the other hand, the touch detection device 10 is of the electrostatic capacitive type (self-capacitive type), and the touch detection device 10 includes a sensor 40 for detecting the proximity of an occupant and a controller 42. In addition, the touch detection device 10 includes a temperature sensor 44 as a temperature detector for detecting ambient temperature.

[0050] The sensor unit 40 includes a sensor electrode 46 and a sensor sheet 48 as a support. The sensor electrode 46 and the sensor sheet 48 are both strip-shaped (thin). For the sensor unit 40, the sensor electrode 46 uses a conductive component, and the sensor sheet 48 uses a resin material as an insulating material (dielectric).

[0051] The sensor unit 40 employs a layered structure in which a sensor electrode 46 is disposed on one surface of the sensor plate 48 without any shielding electrode. The sensor unit 40 is disposed on the outer side of the base 22 in the rim portion 16 such that the sensor electrode 46 is on the side of the decorative portion 26 (while the sensor plate 48 is on the side of the base 22). Furthermore, the sensor unit 40 is disposed across approximately the entire circumference of the base 22 (approximately the entire circumferential area of ​​the cross-section of the rim portion 16) within a predetermined range circumferentially around the steering wheel 14.

[0052] Therefore, when the occupant grips the rim 16 of the steering wheel 14, their hand comes into contact with the rim 16 (decorative part 26), and thus the occupant's hand approaches the sensor electrode 46 of the sensor part 40. Furthermore, when a heater 30 is provided on the rim 16, the sensor part 40 is positioned on the outside of the support plate 32 of the heater 30 (between the support plate 32 and the decorative part 26). Additionally, in the steering wheel 14, when the heater 30 is provided, the base 22 becomes thinner (its radial dimension decreases) by an amount corresponding to the thickness of the heater 30 and the support plate 32.

[0053] like Figure 1 and Figure 2 As shown, the touch detection device 10 uses two sensor units 40 (40L, 40R). Sensor unit 40L is arranged in approximately half a circumference on the left side of the steering wheel 14 in the vehicle width direction, and sensor unit 40R is arranged in approximately half a circumference on the right side in the vehicle width direction. Therefore, when an occupant holds the steering wheel 14 (rim portion 16), the occupant's left hand approaches sensor unit 40L, and the occupant's right hand approaches sensor unit 40R. In sensor unit 40, electrostatic capacitance is generated between the sensor electrode 46 and the occupant through the occupant's contact with the rim portion 16.

[0054] Furthermore, in the touch detection device 10, the sensor units 40L and 40R adopt approximately the same structure. Hereinafter, without distinguishing between sensor units 40L and 40R, sensor unit 40 will be used for description. The temperature sensor 44 of the touch detection device 10 is disposed near the steering wheel 14 or near the rim portion 16 of the steering wheel 14 (e.g., the hub portion 18, the support slat portion 20), and detects the temperature of the environment in which the rim portion 16 is located (the temperature inside the vehicle interior, which is considered the ambient temperature). Additionally, in the touch detection device 10, a controller 42 is disposed near the steering wheel 14, and the temperature sensor 44 is disposed within the controller 42. Not limited to this, the temperature sensor 44 may also be disposed within the rim portion 16, directly detecting the temperature of the substrate 22, etc.

[0055] like Figure 1As shown, in the touch detection device 10, a sensor unit 40 (sensor units 40L, 40R) and a temperature sensor 44 are electrically connected to the controller 42.

[0056] Furthermore, when a heater 30 is provided on the steering wheel 14, the steering device 12 includes a heater controller 34 for controlling the operation of the heater 30. The heater 30 and a controller 42 are connected to the heater controller 34. The heater controller 34 is powered on by a heater switch (not shown) and outputs a heater on signal to the controller 42. Conversely, the heater controller 34 is de-energized by the heater switch and outputs a heater off signal to the controller 42.

[0057] In the steering system 12, by energizing the heater 30, the rim portion 16 of the steering wheel 14 is heated to a predetermined temperature to prevent the occupant in contact with the rim portion 16 from feeling cold. Alternatively, the heater control unit 34 may stop energizing the heater 30 and output a heater disconnect signal to the controller 42 after a predetermined time has elapsed since the heater 30 was energized.

[0058] The controller 42 includes a microcomputer that connects a CPU, ROM, RAM, and non-volatile memory via a bus, as well as the necessary functional circuitry (all omitted from the diagram). In the controller 42, the CPU, acting as a processor, reads and executes touch detection programs stored in the ROM and persistent memory, thereby implementing touch detection functionality using the required functional circuitry. Alternatively, the controller 42 may use a field-programmable gate array (FPGA), a programmable logic array (PLA), or the like as a processor. Furthermore, the touch detection function can be executed by one of the aforementioned processors, or by a combination of two or more processors of the same or different types. More specifically, the hardware structure of the aforementioned processors is a circuit composed of circuit elements such as semiconductor components.

[0059] The controller 42 includes a detector 50, a capacitance correction unit 52 constituting the correction unit, and a determination unit 54. Furthermore, the controller 42 includes a filter unit 56, a difference generation unit 58, a comparison unit 60, a reference value setting unit 62, and a temperature filter unit 64 constituting the correction unit. In the controller 42, the functions of the correction unit, including the capacitance correction unit 52, the filter unit 56, the difference generation unit 58, the comparison unit 60, the reference value setting unit 62, and the determination unit 54, are implemented by the processor executing the aforementioned touch detection program. Alternatively, the function of the temperature filter unit 64 may also be implemented by executing the aforementioned touch detection program.

[0060] Furthermore, the detection unit 50, capacitance correction unit 52, filter unit 56, and difference generation unit 58 include detection units 50L, capacitance correction units 52L, filter units 56L, and difference generation units 58 for sensor unit 40L, and detection units 50R, capacitance correction units 52R, filter units 56R, and difference generation units 58R for sensor unit 40R. The basic structures of detection units 50L and 50R, capacitance correction units 52L and 52R, filter units 56L and 56R, and difference generation units 58L and 58R are the same. Therefore, without distinguishing between units for sensor unit 40L and sensor unit 40R, the following description will focus on detection units 50, capacitance correction units 52, filter units 56, and difference generation units 58.

[0061] For the sensor electrode 46 disposed at the disk rim 16, when an occupant contacts the disk rim 16, electrostatic capacitance is generated between the sensor electrode 46 and the occupant. Furthermore, parasitic capacitance may also occur between the sensor electrode 46 and the disk rim core portion 24. This parasitic capacitance changes depending on the dielectric constant of the insulating material used in the substrate 22 (and support plate 32), and the dielectric constant of the substrate 22 (and support plate 32) changes depending on the temperature of the substrate 22 (and support plate 32).

[0062] The sensor electrode 46 of the sensor unit 40L is connected to the detection unit 50L, and the sensor electrode 46 of the sensor unit 40L is connected to the detection unit 50R. The detection units 50 (50L, 50R) detect (measure) the electrostatic capacitance generated on the sensor electrode 46 at predetermined time intervals. At this time, in the detection unit 50, the potential output from the sensor electrode 46 is detected based on the electrostatic capacitance, and based on the detected potential, the electrostatic capacitance (electrostatic capacitance value) C(t) generated by the sensor electrode 46 is output at each time t. Thus, the detection unit 50L measures the electrostatic capacitance C generated in the sensor unit 40L. L (t) Output, the detection unit 50R will convert the electrostatic capacitance C generated in the sensor unit 40R. R (t) Output.

[0063] The capacitance correction unit 52 (52L, 52R) uses the reference value (electrostatic capacitance value) C set in the reference value setting unit 62 for correction. BASE_L (t), C BASE_R (t) The electrostatic capacitance C detected in the detection unit 50 L (t), C R (t) Temperature calibration is performed. Therefore, the capacitance calibration unit 52L uses the electrostatic capacitance C, which is used to determine the touch detection of the sensor unit 40L. touch_L (t) Output, the capacitance correction unit 52R will use the electrostatic capacitance C used to determine the touch detection of the sensor unit 40R. touch_R (t) Output.

[0064] The determination unit 54 uses a preset threshold Th for touch determination (state determination) judge According to the electrostatic capacitance C touch_L (t), C touch_R (t) Determine whether the occupant is in contact with sensor units 40L and 40R. This threshold Th judge The value (electrostatic capacitance value) is set based on the change in electrostatic capacitance generated when the occupant approaches the sensor electrode 46.

[0065] Based on the determination result, the determination unit 54 outputs a status signal G(t) indicating the occupant's grip state on the steering wheel 14 (including whether it is touched).

[0066] On the other hand, the filter section 56 (56L, 56R), the difference generation section 58 (58L, 58R), the comparison section 60, and the reference value setting section 62 that constitute the correction section start to operate when the determination section 54 detects that the occupant is holding (touching) the steering wheel 14 (outputs a state signal G(t) indicating holding).

[0067] Alternatively, if it is detected that the occupant is holding the steering wheel 14 with only their left or right hand (single-handed), the filter unit 56 and the difference generation unit 58 on the side not being detected to be holding the steering wheel stop processing. For example, if the occupant is holding the steering wheel 14 with their right hand (in the case where no touch is detected on the sensor unit 40L side), the filter unit 56R and the difference generation unit 58R start processing, while the filter unit 56L and the difference generation unit 58L stop processing.

[0068] The filter section 56 (56L, 56R) receives the electrostatic capacitor C L (t), C R (t) is a process for removing noise components. In the filter section 56, as a noise component removal process, for example, an electrostatic capacitance C used n times is applied.R C L This moving average process is performed. Therefore, the filter unit 56L filters the electrostatic capacitance C. L (t) Output, the filter section 56R filters the electrostatic capacitor C that has undergone filtering. R (t) Output. Furthermore, noise removal processing (filtering) is not limited to moving averages; it is applicable as long as the electrostatic capacitance C changes gradually (suppressing noise components). L (t), C R (t) This structure is not limited to this.

[0069] The difference generation unit 58 (58L, 58R) measures the electrostatic capacitance C after this filtering process. L (t), C R (t) and the electrostatic capacitance C after the previous filtering process L (t-1), C R The difference between (t-1) is calculated and used as the change in electrostatic capacitance (electrostatic capacitance value) ΔC. L (t), ΔC R (t) Output. That is, the difference generation unit 58L will output the difference ΔC. L (t)(=C) L (t)-C L (t-1)) is output to the comparison unit 60, and the difference generation unit 58L outputs the difference ΔC. R (t)(=C) R (t)-C R (t-1) is output to the comparison section 60.

[0070] A temperature sensor 44 is connected to a temperature filter unit 64. The temperature filter unit 64 acquires temperature T, which is temperature information, from the temperature sensor 44 at predetermined time intervals, performs predetermined filtering processing, and outputs the filtered temperature T(t) to the comparison unit 60. In the filtering processing at the temperature filter unit 64, for example, the temperature T(t) is obtained by averaging the temperature T using a moving average of n values ​​of temperature T. Furthermore, the noise removal processing of the temperature filter unit 64 is not limited to moving average; it is not limited to any structure that produces a gradually changing (noise-suppressed) temperature T(t).

[0071] The comparison unit 60 compares the difference ΔC. L (t) and the difference ΔC R The comparison process (t) is used to set the correction value ΔC(t). In the comparison process, the difference ΔC is... L The absolute value of (t) |ΔC L (t) | and the difference ΔC RThe absolute value of (t) |ΔC R (t)| for comparison. At this time, it can be considered that the change in electrostatic capacitance at sensor unit 40 is caused by the change due to temperature T and the change due to the occupant's actions, and the change caused by the occupant's actions is greater than the change caused by temperature T.

[0072] Therefore, in the comparison section 60, the absolute value |ΔC L (t)|、|ΔC R The smaller difference ΔC in (t) L (t) (or ΔC) R Let (t) be a candidate for the correction value ΔC(t).

[0073] Furthermore, in the comparison section 60, the difference ΔC is determined. L (t), ΔC R The sign of (t) is determined, and it is determined whether the temperature T(t) is trending upward or downward.

[0074] At this time, in the comparison section 60, the difference ΔC L (t), ΔC R In the case where all signs of (t) are "+" (positive, plus) and all signs are "-" (negative, minus), the absolute value |ΔC will be set as a candidate. L (t)|、|ΔC R The smaller difference ΔC in (t) L (t) (or ΔC) R (t) is set as the correction value ΔC(t).

[0075] Furthermore, in the comparison section 60, the difference ΔC L (t), ΔC R In cases where one sign of ΔC(t) is "+" and the other is "-" (negative, minus), the temperature T(t) (the changing trend of temperature T(t)) is used in setting the correction value ΔC(t). At this time, in the comparison unit 60, if the temperature T(t) is trending upwards (in the case where the temperature T(t) is higher than the previous temperature T(t-1), the absolute value |ΔC(t) is used). L (t)|、|ΔC R (t)| The difference ΔC with the sign "+" L (t) (or ΔC) R (t) is set as the correction value ΔC(t).

[0076] In contrast, in the comparison section 60, when the temperature T(t) is decreasing (when the temperature T(t) is lower than the previous temperature T(t-1), the difference ΔC is... L (t), ΔC RThe difference ΔC with the sign "-" in (t) L (t) (or ΔC) R (t) is set as the correction value ΔC(t).

[0077] Furthermore, when a heater 30 is installed on the steering wheel 14, there is a possibility that the temperature T(t) may not fully reflect the temperature of the base 22 (steering wheel 14). Therefore, the comparison unit 60 obtains a signal from the heater control unit 34 indicating whether the heater 30 is on or off. In the comparison unit 60, when the heater 30 is on and the temperature difference ΔC is between the heater 30 and the heater 30 is off, the comparison unit 60 will detect the heater 30's on-time and the temperature difference ΔC ... L (t), ΔC R When one sign in (t) is "+" and the other sign is "-" (negative, minus), the difference ΔC is... L (t), ΔC R The difference ΔC with the sign "+" in (t) L (t) (or ΔC) R (t) is set as the correction value ΔC(t).

[0078] The correction value ΔC(t) set in the comparison unit 60 includes the original difference ΔC. L (t) or the difference ΔC R The sign of the value of (t) (electrostatic capacitance value) is inherited. Additionally, in the comparison section 60, the difference ΔC... L (t), ΔC R If one of the values ​​in (t) is "+" and the other is "-" (negative, minus), and it is determined that the temperature T(t) has not changed (in the case that it is neither an upward trend nor a downward trend), it is impossible to properly identify the correction direction. Therefore, the correction value ΔC(t) is set to "0" (ΔC(t) = 0).

[0079] On the other hand, in the reference value setting unit 62, a reference value C is preset as the initial value (electrostatic capacitance value) for the sensor units 40L and 40R. BASE_L (t), benchmark value C BASE_R (t). Regarding the baseline value C BASE_L (t), benchmark value C BASE_R The initial value of (t) is, for example, the electrostatic capacitance C detected by the sensor units 40L and 40R when the vehicle's ignition switch (not shown) is turned on, causing the touch detection device 10 to start operating. L (t), C R (t). That is, the baseline value C used as the initial value. BASE_L (t), benchmark value C BASE_R(t) The electrostatic capacitance of the sensor unit 40L and 40R when the occupant does not touch it (mainly electrostatic capacitance caused by parasitic capacitance).

[0080] Furthermore, when a heater 30 is provided on the steering wheel 14, the reference value setting unit 62 receives a signal from the heater control unit 34 indicating whether the heater 30 is turned on or off.

[0081] Furthermore, the reference value setting unit 62 is configured to adjust whether to use a correction value ΔC(t) to correct the reference value C. BASE_L (t), C BASE_R (t) The threshold Th used for this judgment BASE The reference value setting unit 62 uses the threshold Th BASE To evaluate the correction value ΔC(t). Preferably, at the threshold Th... BASE Multiple values ​​(electrostatic capacitance values) are set corresponding to changes in temperature T(t) and the on / off state of heater 30.

[0082] As a change threshold Th BASE Conditions that can be cited include changes in temperature T(t), the state of heater 30 (on or off), and the detected electrostatic capacitance (electrostatic capacitance C). L (t), C R The change of (t) and the difference (difference ΔC) L (t), ΔC R Changes in (t) and so on. Figure 4 The table shows the threshold Th based on these conditions. BASE One example.

[0083] like Figure 4 As shown, the temperature T(t) is divided into three stages: rising (rising trend), unchanged, or falling (falling trend). Furthermore, the state of the heater 30 is divided into two stages: ON or OFF. And, the electrostatic capacitance detected in the sensor unit 40 is divided into two stages: increasing (increasing trend) or decreasing (decreasing trend).

[0084] Therefore, as the threshold Th BASE It can be divided into Th BASE1 To Th BASE12 These 12 stages. Furthermore, without heater 30, the heater state is limited to off; therefore, it is possible to consider setting the threshold Th... BASE It is set to 6 stages. For these thresholds Th BASE In this regard, it is possible to predict the change in parasitic capacitance in advance along with various conditions, or to measure the change in parasitic capacitance along with conditions, and apply a value set based on the prediction or measurement results. Additionally, the threshold Th...BASE Quantity (threshold Th) BASE (The stages) are not limited to these.

[0085] Here, as an example, in the touch detection device 10, when a heater 30 is provided on the steering wheel 14, the threshold Th is set by removing the condition of temperature T(t) and the change in electrostatic capacitance of the sensor unit 40. BASE Therefore, in the reference value setting unit 62, the threshold Th is set as... BASE The threshold Th is set when heater 30 is turned on. BASE_H The value Th applied when heater 30 is disconnected BASE_L At this time, the change in electrostatic capacitance caused by parasitic capacitance due to the heater 30 being turned on is significant. Therefore, in the reference value setting unit 62, the threshold value Th applied when the heater 30 is turned on is set. BASE_H The value Th is set to be applied when heater 30 is disconnected. BASE_L Large value (Th) BASE_H >Th BASE_L ).

[0086] In the reference value setting unit 62, the correction value ΔC(t) and the threshold Th are compared during the evaluation. BASE When making comparisons, the absolute value of the correction value ΔC(t), |ΔC(t)|, is applied. In the reference value setting unit 62, if the absolute value |ΔC(t)| is insufficient, the threshold Th is... BASE In the case of (|ΔC(t)| < Th) BASE The correction value ΔC(t) is evaluated as equivalent to the change in parasitic capacitance caused by the change in temperature T, and correction is preferably performed. Therefore, in the reference value setting unit 62, the reference value C is set using the correction value ΔC(t). BASE_L (t), C BASE_R The correction of (t) is set in this way.

[0087] At this time, in the reference value setting unit 62, when the heater 30 is turned on, for the threshold Th BASE , applying threshold Th BASE_H When heater 30 is disconnected, for threshold Th BASE , applying threshold Th BASE_L In the reference value setting unit 62, the threshold value Th is set when the heater 30 is turned on. BASE Application threshold Th BASE_H At that time, the heater 30 was disconnected, thus lowering the threshold Th. BASE From the threshold Th BASE_H Change (return) to threshold Th BASE_L .

[0088] Furthermore, the heater 30 is temperature-controlled by the heater control unit 34; therefore, in the reference value setting unit 62, when the threshold Th is set... BASE A threshold Th was set. BASE_H In this case, by waiting for a preset time after the heater 30 is turned on, the threshold Th is... BASE Change to threshold Th BASE_L This time can be, for example, the time it takes for the steering wheel 14 to reach a specified temperature (the control temperature of the heater 30), or the time when the temperature rise stops.

[0089] In the reference value setting unit 62, the reference value C is set to be made using the correction value ΔC(t). BASE_L (t), C BASE_R In this case, the correction value ΔC(t) is used to update the reference value C. BASE_L (t), C BASE_R (t). That is, the following calculation process is performed in the reference value setting unit 62.

[0090] C BASE_L (t) = C BASE_L (t-1) + ΔC(t)

[0091] C BASE_R (t) = C BASE_R (t-1) + ΔC(t)

[0092] Therefore, for the benchmark value C BASE_L (t), C BASE_R For each of the t values, when the correction value ΔC(t) is positive (ΔC(t) > 0), they increase; when the correction value ΔC(t) is negative (ΔC(t) < 0), they decrease. Furthermore, without making any corrections, the reference value C... BASE_L (t), C BASE_R (t) Apply the previous baseline value C respectively BASE_L (t-1), C BASE_R (t-1)(C) BASE_L (t) = C BASE_L (t-1), C BASE_R (t) = C BASE_R (t-1)).

[0093] The capacitor correction unit 52 (52L, 52R) obtains the capacitance from the electrostatic capacitor C. L (t), C R Subtract the reference value C corresponding to the parasitic capacitance from (t). BASE_L (t), C BASE_R (t) and calculate the electrostatic capacitance C used in touch detection. touch_L (t), Ctouch_R (t). That is, the capacitance correction unit 52L calculates the electrostatic capacitance C. touch_L (t)(=C) L (t)-C BASE_L (t)) and outputs it, and the capacitor correction unit 52R calculates the electrostatic capacitance C. touch_R (t)(=C) R (t)-C BASE_R (t) and output it.

[0094] Therefore, in the determination unit 54, the electrostatic capacitance C can be used. L (t), C R (t) The electrostatic capacitance C obtained after temperature correction touch_L (t), C touch_R (t) determines whether the steering wheel 14 is being held by an occupant.

[0095] Next, the operation of the touch detection device 10 will be explained as part of this embodiment.

[0096] In the touch detection device 10, if the vehicle's ignition switch is turned on, the controller 42 starts to operate, and the detection units 50L and 50R respectively start the electrostatic capacitance C of the sensor units 40L and 40R. L (t), C R The detection of (t) begins, and the detected electrostatic capacitance C is output. L (t), C R (t).

[0097] In the controller 42, if the operation is started, the reference value setting unit 62 sets the reference value based on the electrostatic capacitance C detected by the sensor unit 40L. L (t) Set the baseline value C BASE_L The initial value of (t) is based on the electrostatic capacitance C detected in the sensor unit 40R. R (t) Set the baseline value C BASE_R The initial value of (t). At this time, since the occupant is not holding (not in contact with) the steering wheel 14, the electrostatic capacitance C detected by the sensor units 40L and 40R is... L (t), C R (t) becomes the electrostatic capacitance mainly caused by parasitic capacitance (electrostatic capacitance not affected by occupants). Therefore, in the reference value setting unit 62, the electrostatic capacitance C mainly caused by parasitic capacitance can be set. L (t), C R (t) is set as the baseline value C BASE_L (t)C BASE_R The initial value of (t).

[0098] Furthermore, in the controller 42, the temperature filter unit 64 is activated upon startup. Consequently, the temperature filter unit 64 begins to output a temperature T(t) that is a moving average (a moving average corresponding to n times) of the temperature T detected by the temperature sensor 44.

[0099] After the touch detection device 10 starts operating, if the occupant uses both hands to hold the steering wheel 14 for vehicle steering, the occupant's hands approach the sensor units 40L and 40R, and the electrostatic capacitance C... L (t), C R (t) increases. Therefore, if the electrostatic capacitance C output from the capacitor correction units 52L and 52R increases... touch_L (t), C touch_R (t) exceeded the threshold Th respectively judge (C) touch_L (t) > Th judge C touch_R (t) > Th judge If the condition is met, the determination unit 54 determines that the gripping with both hands has begun. This determination result is output from the determination unit 54 as a status signal G(t).

[0100] In the controller 42, if it detects that the steering wheel 14 has been gripped by an occupant, the correction unit begins to operate. Consequently, the filter units 56L and 56R begin to adjust the electrostatic capacitance C detected by the sensor unit 40L. L (t) and the electrostatic capacitance C detected by the sensor unit 40R R (t) The filtering process performed. Filter units 56L and 56R will process the electrostatic capacitance C obtained after filtering. L (t), C R (t) Output to the difference generation units 58L and 58R.

[0101] In the difference generation unit 58L, the electrostatic capacitor C that has undergone filtering is processed. L The change in (t) represents the difference ΔC. L (t)(=C) L (t)-C L (t-1) is calculated and output. Furthermore, in the difference generation unit 58R, the filtered electrostatic capacitor C is processed... R The change in (t) represents the difference ΔC. R (t)(=C) R (t)-C R Perform the calculations on (t-1) and output the result.

[0102] Here, in the comparison section 60, the difference ΔC is... L (t) and the difference ΔC R(t) is compared, and the benchmark value C is set based on the comparison result. BASE_L (t), C BASE_R The correction value ΔC(t) is used in relation to (t). Furthermore, in the comparison unit 60, the filtered temperature T(t) is used as needed when setting the correction value ΔC(t). In the comparison unit 60, the difference ΔC is used. L (t), difference ΔC L The absolute value of (t) |ΔC L (t)|、Difference ΔC R (t), difference ΔC R The absolute value of (t) |ΔC R The correction value ΔC(t) is set using the temperature T(t) and the temperature T(t).

[0103] At this time, in the comparison section 60, the difference ΔC L (t), ΔC R When all signs of (t) are "+" or "-" (with the same sign), the absolute value |ΔC L (t)|、|ΔC R The smaller difference ΔC in (t) L (t) (or difference ΔC) R (t) is set as the correction value ΔC(t).

[0104] Furthermore, in the comparison section 60, the difference ΔC L (t), ΔC R When one of the values ​​in (t) is "+" and the other is "-", the trend of temperature change T(t) is used. In this case, if temperature T(t) shows an upward trend, the comparison unit 60 will calculate the difference ΔC. L (t), ΔC R The difference ΔC with the sign "+" in (t) L (t) (or difference ΔC) R (t) is set as the correction value ΔC(t). Furthermore, when the temperature T(t) shows a decreasing trend, the comparison unit 60 sets the difference ΔC... L (t), ΔC R The difference ΔC with the sign "-" in (t) L (t) (or difference ΔC) R (t) is set as the correction value ΔC(t).

[0105] In the touch detection device 10, as an example, the temperature sensor 44 detects the ambient temperature around the steering wheel 14, but the temperature sensor 44 may not be able to detect the temperature of the substrate 22, etc. Therefore, there is a situation where although the heater 30 is turned on, causing the temperature of the substrate 22, etc. of the steering wheel 14 to rise, it is not reflected in the temperature T(t).

[0106] Therefore, in the touch detection device 10, if the heater 30 is turned on, it is assumed that the temperature T(t) is on an upward trend. Thus, in the touch detection device 10, the difference ΔC... L (t), ΔC R In case (t), one of them is "+" and the other is "-", and heater 30 is turned on, the difference ΔC will be... L (t), ΔC R The difference ΔC with the sign "+" in (t) L (t) (or difference ΔC) R (t) is set as the correction value ΔC(t).

[0107] If the correction value ΔC(t) is set in this way, then in the reference value setting unit 62, the reference value C is set using the correction value ΔC(t). BASE_L (t), C BASE_R (t) correction. At this time, in the reference value setting unit 62, a threshold value Th is set in accordance with the on / off state of the heater 30. BASE Using the threshold Th BASE Determine whether the correction value ΔC(t) is appropriate (whether correction is needed) (evaluate the correction value ΔC(t).

[0108] At this point, the absolute value of the correction value ΔC(t), |ΔC(t)|, is insufficient to reach the threshold Th. BASE In the case that (|ΔC(t)|<Th) BASE The correction value ΔC(t) is considered to be mainly the change in parasitic capacitance, and therefore the correction value ΔC(t) is used to determine the reference value C. BASE_L (t), C BASE_R Correction of (t). Thus, the reference value C, corresponding to the parasitic capacitance at temperature, is obtained. BASE_L (t)(=C) BASE_L (t-1) + ΔC(t)) and the baseline value C BASE_R (t)(=C) BASE_R (t-1) + ΔC(t)).

[0109] The capacitance correction unit 52L uses the electrostatic capacitance C detected from the sensor unit 40L in the detection unit 50L. L (t) and benchmark value C BASE_L (t), for the electrostatic capacitance CL Subtract the baseline value C from (t) BASE_L (t) The obtained electrostatic capacitance C touch_L (t) performs operations (C) touch_L (t) = C L (t)-C BASE_L (t)). Furthermore, the capacitance correction unit 52R uses the electrostatic capacitance C detected by the sensor unit 40R in the detection unit 50R. R (t) and benchmark value C BASE_R (t), for the electrostatic capacitance C R Subtract the baseline value C from (t) BASE_R (t) The electrostatic capacitance C obtained touch_R (t) performs operations (C) touch_R (t) = C R (t)-C BASE_R (t)).

[0110] In the determination unit 54, an electrostatic capacitor C is used. touch_L (t) and threshold Th judge To determine whether the left side of the steering wheel 14 (the occupant's left hand) is being held, an electrostatic capacitor C is used. touch_R (t) and threshold Th judge Determine whether the right side of the steering wheel 14 (the occupant's right hand) is being held. At this time, if the electrostatic capacitance C... touch_L (t) is greater than the threshold Th judge (C) touch_L (t) > Th judge If the left side of the steering wheel 14 (the sensor section 40L) is gripped, then the determination unit 54 determines that the left side of the steering wheel 14 is being gripped. Furthermore, if the electrostatic capacitor C... touch_R (t) is greater than the threshold Th judge (C) touch_R (t) > Th judge If the determination unit 54 determines that the right side of the steering wheel 14 (the sensor unit 40R part) is being held.

[0111] Here, Figures 5A-5C In the figure, temperature T(t) and electrostatic capacitance C are shown by line graph. L (t), electrostatic capacitance C R (t) and benchmark value C BASE (t) Approximate changes of each relative to time t. Additionally, Figure 5A The diagram shows the change in temperature T(t) relative to time t. Figure 5B The figure shows the electrostatic capacitance C. L (t) and electrostatic capacitance C R (t) is the change relative to time t. Figure 5C The reference value C is shown in the figure.BASE (t) represents the change relative to time t. Furthermore, Figure 5C In the middle, the benchmark value C BASE_L (t) and the benchmark value C BASE_R (t) is considered the same, and is represented by the baseline value C. BASE (t).

[0112] like Figure 5A As shown, the temperature T(t) gradually increases with time t, but then decreases at time t3. Additionally, in the attached figure, times t1, t2, and t3 are set to t1 < t2 < t3.

[0113] In addition, such as Figure 5B As shown, for the electrostatic capacitor C L (t) As far as time t3 is reached, the electrostatic capacitance C L (t) increases, and if time t3 is reached, then the electrostatic capacitance C L (t) changes to decrease, and at time t2, the degree of increase changes (becomes larger). Furthermore, for the electrostatic capacitance C... R (t) In terms of time, up to time t2 after time t1, the electrostatic capacitance C R (t) gradually decreases. If time t2 has elapsed, then the electrostatic capacitance C R (t) changes to an increase, and further, due to the passage of time t3, the electrostatic capacitance C R (t) turns into a decrease.

[0114] Here, up to time t2, the electrostatic capacitance C L The difference ΔC between (t) L (t) is "+", electrostatic capacitance C R The difference ΔC between (t) R (t) is "-". At this time, due to the increase in temperature T(t), the electrostatic capacitance C will be reduced. L The difference ΔC between (t) L (t) is set as the correction value ΔC(t). Therefore, as... Figure 5C As shown, with electrostatic capacitance C L (t) is the same, up to the arrival time t2, the reference value C BASE (t) changes in an increasing manner.

[0115] Furthermore, during the period from time t2 to time t3, the electrostatic capacitance C L The difference ΔC between (t) L (t) and electrostatic capacitance C R The difference ΔC between (t) R (t) are all "+". At this time, compared to the electrostatic capacitance C L The change in (t) affects the electrostatic capacitance C. RThe change in (t) is small, thus the absolute value |ΔC R (t) |Ratio of absolute value|ΔC L (t)|small(|ΔC) L (t)|>|ΔC R (t)|). Therefore, with electrostatic capacitance C R (t) is the same, from time t2 to time t3, the reference value C BASE (t) changes in an increasing manner.

[0116] Furthermore, if the temperature T(t) decreases after time t3, then the electrostatic capacitance C L The difference ΔC between (t) L (t) and electrostatic capacitance C R The difference ΔC between (t) R (t) are all "-". Furthermore, compared to the electrostatic capacitance C... L The change in (t) affects the electrostatic capacitance C. R The change in (t) is small, thus the absolute value |ΔC R (t) |Ratio of absolute value|ΔC L (t)|small(|ΔC) L (t)|>|ΔC R (t)|). Therefore, with electrostatic capacitance C R (t), same, benchmark value C BASE (t) changes by decreasing as time t3 passes.

[0117] In the touch detection device 10, the detection units 50L and 50R detect the electrostatic capacitance C through the sensor units 40L and 40R. L (t), C R (t) The determination unit 54 performs touch detection (touch determination, grip state determination) to determine the occupant's contact state with the steering wheel 14. In addition, in the sensor units 40L and 40R, no shielding electrode or other electrical shielding part is provided between the sensor electrode 46 and the disc rim core part 24.

[0118] Here, in controller 42, the difference generation units 58L and 58R generate a filtered electrostatic capacitor C. L (t), C R The difference ΔC in the change of (t) L (t), ΔC R (t), using the generated difference ΔC L (t), ΔC R (t), the electrostatic capacitance C detected in the detection units 50L and 50R. L (t), C R (t) is corrected.

[0119] Therefore, in the touch detection device 10, even if the parasitic capacitance in each of the sensor electrodes 46 changes, the electrostatic capacitance C is reduced. L (t), C R (t) has changed, and it is also possible to use an electrostatic capacitor C that suppresses changes caused by parasitic capacitance. touch_L (t), C touch_R (t) is used to determine touch.

[0120] Furthermore, in the touch detection device 10, a sensor unit 40L is arranged on the left side of the steering wheel 14 in the vehicle width direction, and a sensor unit 40R is arranged on the right side in the vehicle width direction. Thus, the touch detection device 10 can detect with high precision whether the occupant is holding the steering wheel 14 with both hands, with one hand, or without holding the steering wheel 14.

[0121] Furthermore, in the touch detection device 10, the comparison unit 60 uses a filtered electrostatic capacitor C. L (t), C R The difference ΔC between (t) L (t), ΔC R The absolute value of (t) |ΔC L (t)|、|ΔC R The correction value ΔC(t) is set using |ΔC(t). At this point, the correction value ΔC(t) can be applied using the absolute value |ΔC(t). L (t)|、|ΔC R The difference ΔC between the smaller values ​​of (t) and (t) L (t) (or difference ΔC) R (t)).

[0122] Therefore, the electrostatic capacitance C corresponding to the parasitic capacitance smaller than that caused by the occupant's actions is obtained. touch_L (t), C touch_R (t), therefore, it will not affect the electrostatic capacitance C. touch_L (t), C touch_R (t) Perform a significant correction beyond what is necessary. Therefore, in the touch detection device 10, it is possible to prevent errors caused by electrostatic capacitance C. touch_L (t), C touch_R (t) The decrease in touch detection accuracy caused by large-scale correction.

[0123] Furthermore, in the touch detection device 10, a correction value ΔC(t) is set based on the temperature T(t). Therefore, in the touch detection device 10, a correction value ΔC(t) that appropriately corresponds to the parasitic capacitance that changes according to the temperature T(t) can be obtained.

[0124] Furthermore, in the touch detection device 10, the electrostatic capacitance C in the state where the occupant is not in contact is measured.L (t), C R (t) is set as the initial value, and the baseline value C is updated using the correction value ΔC(t). BASE_L (t), C BASE_R (t). Therefore, in the touch detection device 10, touch determination can utilize the electrostatic capacitance C. L (t), C R The electrostatic capacitance C obtained by subtracting the capacitance corresponding to the parasitic capacitance from (t) is the electrostatic capacitance. touch_L (t), Ct ouch_R (t), therefore, touch detection can be performed with high precision.

[0125] Furthermore, in the touch detection device 10, a threshold Th is used. BASE The evaluation of the correction value ΔC(t) is performed. If the correction value ΔC(t) is insufficient, the threshold Th is reached. BASE The evaluation is deemed appropriate, and a correction using the correction value ΔC(t) is performed. Therefore, in the touch detection device 10, unnecessary corrections due to changes in electrostatic capacitance caused by factors such as occupant movements can be suppressed.

[0126] Furthermore, in the touch detection device 10, when a heater 30 is provided on the steering wheel 14, the threshold Th is set according to the on / off (operating state) of the heater 30. BASE Furthermore, regarding the threshold Th BASE In other words, the threshold Th used when heater 30 is disconnected BASE_L Compared to the threshold Th used when heater 30 is turned on. BASE_H Small. Therefore, it is possible to suppress corrections, including those caused by changes in electrostatic capacitance due to occupant movements.

[0127] Furthermore, in the embodiment described above, the correction when both hands are holding the steering wheel 14 is mainly used as an example. However, in the touch detection device 10, this embodiment can also be applied when single-handed holding is detected, such as when the right hand is detected, or when the left hand is detected (and vice versa).

[0128] In this case, according to the electrostatic capacitance C L The difference ΔC between (t) L (t) and temperature T(t) are used to set a correction value ΔC(t). For the set correction value ΔC(t), a threshold Th is used. BASE An evaluation is performed. Therefore, if the correction value ΔC(t) is insufficient to reach the threshold, the correction value ΔC(t) is used to adjust the baseline value C. BASE_L (t), C BASE_R (t) can be used for correction and update. Therefore, not only can the baseline value C be updated.BASE_L (t) can also update the baseline value C. BASE_R (t), therefore, a more appropriate determination of the contact state can be made.

[0129] Furthermore, in this embodiment, a sensor section 40 is used, in which a sensor electrode 46 is disposed on one side of the sensor sheet 48. However, the sensor section can be any structure in which the sensor electrode is disposed on the outer periphery of the substrate and an electrostatic capacitance is generated between it and the occupant (occupant's hand, fingers) who is close to the steering body.

[0130] Furthermore, in the embodiment described above, sensor units 40L and 40R are provided on the steering wheel 14. However, it is also possible to provide three or more sensor units (sensor electrodes) on the steering body. In this case, the difference in electrostatic capacitance detected by each sensor electrode is calculated, the absolute values ​​of the calculated differences are compared, and a correction value is set based on the comparison result.

[0131] Furthermore, in this embodiment, a threshold Th is used as the threshold for touch detection (determination of contact state). judge However, the threshold used for touch detection can also be set with multiple thresholds, such as a threshold corresponding to the state of the occupant gripping the steering wheel tightly, a threshold corresponding to the state of the occupant lightly gripping the steering wheel, and a threshold corresponding to the state of the occupant lightly touching the steering wheel.

[0132] Furthermore, in this embodiment, the electrostatic capacitance C of the sensor units 40L and 40R is... L (t), C R (t) Each corresponding electrostatic capacitance C used in touch detection is obtained. touch_L (t), C touch_R (t). However, it is also possible to obtain the electrostatic capacitance used in touch detection corresponding to the combined capacitance of the electrostatic capacitances detected in each of the multiple sensor electrodes. In this case, as the threshold used in touch detection, at least a threshold for determining single-handed holding and a threshold for determining two-handed holding can be set.

[0133] Furthermore, in this embodiment, a generally circular steering wheel 14 is described as an example. However, the steering body is not limited to a generally circular shape; it may also be a generally rectangular irregular steering wheel with the handles arranged in pairs on the left and right sides separated by the hub, each connected to the hub at one or more locations, or it may be a D-shaped (flat-bottomed) shape, etc.

[0134] Alternatively, the touch detection program described in this embodiment may be provided in the form of a non-transitory storage medium such as a CD-ROM (CompactDisc Read Only Memory), DVD-ROM (Digital Versatile Disc Read Only Memory), or USB (Universal Serial Bus) persistent storage. Furthermore, the touch detection program may also be downloaded from an external device via a network.

[0135] The entire publication of Japanese Patent Application No. 2023-206513, filed on December 6, 2023, is incorporated herein by reference.

[0136] All documents, patent applications and technical standards described in this specification, as well as those specifically and separately described herein, are incorporated herein by reference.

Claims

1. A touch detection device, characterized in that, include: The steering body is formed by covering an insulating substrate with a conductive core that is grounded to the vehicle body, and the vehicle is steered by contact and operation by the occupants. Multiple sensor units that generate electrostatic capacitance between sensor electrodes respectively disposed on the outer periphery of the base of the steering body and the occupant in contact with the steering body; The detection unit is used to detect the electrostatic capacitance of each of the sensor electrodes; The calibration unit corrects the electrostatic capacitance of each sensor electrode detected by the detection unit using the difference, which is represented by the change in electrostatic capacitance of each sensor electrode detected by the detection unit. as well as The determination unit determines the occupant's contact state with the steering body based on the corrected electrostatic capacitance.

2. The touch detection device according to claim 1, characterized in that, The sensor electrode is disposed on one side of the sheet-like insulating support and is opposite to the core portion.

3. The touch detection device according to claim 1, characterized in that, The sensor electrodes are arranged in pairs in the steering body along the vehicle width direction.

4. The touch detection device according to claim 1, characterized in that, The calibration unit includes setting a calibration value for correcting the electrostatic capacitance of each of the sensor electrodes using the absolute value of the difference between the differences between the sensor electrodes.

5. The touch detection device according to claim 4, characterized in that, It includes a temperature detection unit that detects changes in the ambient temperature surrounding the steering body. The correction unit sets the correction value based on each of the differences and the change in the ambient temperature.

6. The touch detection device according to claim 4, characterized in that, The calibration unit includes a reference value setting unit. This unit sets an initial reference value for the electrostatic capacitance of each sensor electrode based on the electrostatic capacitance of each sensor electrode in a state where the occupant is not in contact with the steering element. The unit then updates each reference value using the calibration value. The calibration unit includes calibrating the electrostatic capacitance of each sensor electrode using the reference value after the update settings have been performed for each sensor electrode.

7. The touch detection device according to claim 4, characterized in that, The correction unit includes: evaluating whether the correction value is insufficient for a preset threshold; and if the evaluation indicates that the correction value is insufficient for the threshold, using the correction value to correct the electrostatic capacitance of each of the sensor electrodes.

8. The touch detection device according to claim 7, characterized in that, It includes a heating element, which is disposed within the base of the steering body and heats the steering body during operation.

9. The touch detection device according to claim 8, characterized in that, The threshold is changed according to the operating state of the heating element.

10. The touch detection device according to claim 9, characterized in that, Regarding the threshold, the threshold for the case where the heating element is operating is set higher than the threshold for the case where the heating element is not operating.

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