Touch determination device

Abstract

To prevent accuracy of touch determination from being deteriorated due to temporal change of parasitic capacitance or the like.SOLUTION: A determination unit determines the presence or absence of a touch for each of a plurality of sensor electrodes disposed in different regions of a steering wheel by comparing the detected capacitance value C with a reference value Cref for touch determination set for each sensor electrode. When it is determined that a first sensor electrode of the plurality of sensor electrodes is not touched and a second sensor electrode is touched (when Yes in step 66), a correction unit corrects the reference value Cref for touch determination for the second sensor electrode based on a difference ΔC between the capacitance values detected in a state where there is no touch to the region where the first sensor electrode is disposed and the region where the second sensor electrode is disposed and on the reference value Cref for touch determination for the first sensor electrode (step 72).SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a touch determination device. [Background technology]

[0002] Patent Document 1 describes a technology in which, when it is determined that one of the driver's hands is off the steering wheel, the output value of a sensor electrode is used to determine whether the driver's other hand is touching the steering wheel, and a reference value is set. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-166978 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology described in Patent Document 1 determines whether one of the driver's hands is off the steering wheel based on whether the ignition switch is operated, and the reference value for touch determination is not updated after the ignition switch is operated. Therefore, the technology described in Patent Document 1 may have a possibility of reducing the accuracy of touch determination if the parasitic capacitance changes over time due to temperature changes or the like.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a touch determination device that can suppress a decrease in the accuracy of touch determination due to a change in parasitic capacitance over time or the like. [Means for solving the problem]

[0006] The touch determination device according to the first aspect includes a determination unit that determines whether or not a region in which a plurality of sensor electrodes are arranged in different regions of an operating member of a movable body is touched by comparing detected capacitance values ​​with a touch determination reference value set for each of the sensor electrodes; and a correction unit that, when a first region in which a first sensor electrode is arranged among the plurality of sensor electrodes is determined to be untouched and a second region in which a second sensor electrode is arranged is determined to be touched, corrects the touch determination reference value of the second sensor electrode based on the difference between the capacitance values ​​detected when the first region and the second region are not touched and the touch determination reference value of the first sensor electrode.

[0007] In the second aspect, in the first aspect, the correction unit corrects the reference value for the touch judgment of the second sensor electrode to an estimated value obtained by subtracting the difference in the capacitance values ​​from the reference value for the touch judgment of the first sensor electrode.

[0008] In a third aspect, in the second aspect, when the reference value for touch judgment of the second sensor electrode differs from the estimated value by a predetermined value or more, the correction unit corrects the reference value for touch judgment of the second sensor electrode so that the difference between the reference value for touch judgment of the second sensor electrode and the estimated value is less than the predetermined value.

[0009] In a fourth aspect, in any one of the first to third aspects, the correction unit calculates a difference between the capacitance values ​​detected for the plurality of sensor electrodes when the touch determination device is powered on.

[0010] A fifth aspect is any of the first to third aspects, further including a setting unit that initially sets a reference value for touch determination for each sensor electrode to a capacitance value that is initially detected for each of the plurality of sensor electrodes when the touch determination device is powered on, or an average value of capacitance values ​​that are detected multiple times for each of the plurality of sensor electrodes within a predetermined period from the powering on of the touch determination device, and that sets the detected capacitance value to the reference value for touch determination for the corresponding sensor electrode at a timing when the determination result by the determination unit shows that the deviation between the capacitance value detected during a no-touch period and the reference value exceeds a predetermined value.

[0011] In a sixth aspect, in any of the first to fourth aspects, the correction unit calculates a differential value of the detected capacitance value, and when the calculated differential value of the capacitance value is equal to or less than a threshold value, corrects the corresponding reference value for touch determination with the differential value of the capacitance for each of the plurality of sensor electrodes. [Effects of the Invention]

[0012] In a configuration in which multiple sensor electrodes are arranged in different regions of an operating member of a movable object, each sensor electrode is in a similar temperature environment. Therefore, even if the parasitic capacitance of the sensor electrodes changes over time due to temperature changes or the like, it is estimated that the difference in parasitic capacitance between the individual sensor electrodes will be approximately constant. Based on this, in a first aspect, when a first region, where a first sensor electrode is arranged among the multiple sensor electrodes, is determined to be untouched and a second region, where a second sensor electrode is arranged, is determined to be touched, the reference value for touch determination of the second sensor electrode is corrected based on the difference in capacitance values ​​detected when the first and second regions are untouched and the reference value for touch determination of the first sensor electrode. This makes it possible to prevent a decrease in the accuracy of touch determination due to changes in parasitic capacitance over time or the like.

[0013] In the second aspect, the reference value for touch judgment of the second sensor electrode is corrected to an estimated value obtained by subtracting the difference in capacitance values ​​from the reference value for touch judgment of the first sensor electrode, so that the reference value for touch judgment of the second sensor electrode can be corrected to an appropriate value.

[0014] In a configuration in which multiple sensor electrodes are arranged in different regions of an operating member of a movable object, the temperature and humidity environments of the individual sensor electrodes are not exactly the same, so the difference in parasitic capacitance between the multiple sensor electrodes may change slightly over time. Based on this, the third aspect corrects the reference value for touch determination of the second sensor electrode when the reference value for touch determination of the second sensor electrode differs from the estimated value by a predetermined value or more so that the difference between the reference value for touch determination of the second sensor electrode and the estimated value becomes less than the predetermined value. This makes it possible to achieve touch determination that takes into account the slight change in the difference in parasitic capacitance between the sensor electrodes over time, compared to an aspect in which the reference value for touch determination of the second sensor electrode is corrected to the estimated value even when the reference value for touch determination of the second sensor electrode differs from the estimated value by a predetermined value or more.

[0015] In the fourth aspect, the difference in capacitance value is calculated when the touch determination device is turned on, so that the accuracy of touch determination can be maintained even if the capacitance value of the sensor electrode changes over time.

[0016] In the fifth aspect, the reference value for touch judgment of the sensor electrode can be appropriately set when the touch judgment device is turned on and when the deviation between the capacitance value detected during the no-touch period and the reference value as a judgment result by the judgment unit exceeds a predetermined value.

[0017] In the sixth aspect, even if the first region where the first sensor electrode is arranged is not judged to be untouched and the second region where the second sensor electrode is arranged is not judged to be touched for a long period of time, it is possible to prevent errors in the reference values ​​for touch judgment from accumulating for each sensor electrode. [Brief explanation of the drawings]

[0018] [Figure 1]FIG. 2 is a front view of the steering wheel according to the embodiment. [Figure 2] FIG. 3 is a cross-sectional view of the rim portion as viewed in the circumferential direction of the steering wheel. [Figure 3] FIG. 2 is a functional block diagram of a steering ECU. [Figure 4] 10 is a flowchart showing an example of a reference value correction process executed by a correction unit of a steering ECU. [Figure 5] FIG. 10 is an explanatory diagram for explaining a problem in conventional touch determination. [Figure 6] FIG. 2 is an explanatory diagram for explaining the basic concept of correction in the first correction process and the second correction process. [Figure 7] FIG. 10 is an explanatory diagram for explaining the basic concept of correction in the second correction process. [Figure 8] FIG. 10 is an explanatory diagram showing details of the second correction processing. [Figure 9] FIG. 10 is an explanatory diagram showing details of a first correction process. DETAILED DESCRIPTION OF THE INVENTION

[0019] An example of an embodiment of the present disclosure will be described in detail below with reference to the drawings. Fig. 1 shows a vehicle steering wheel 12 as an example of an operating member of a moving body according to this embodiment. The steering wheel 12 is disposed on the front side of a seat (driver's seat) in which a user (driver) who drives the vehicle sits. In Figs. 1 and 2, the front side of the vehicle is indicated by an arrow FR, the upper side of the vehicle is indicated by an arrow UP, and the right side in the vehicle width direction is indicated by an arrow HR. The radial direction of the steering wheel 12 is indicated by an arrow R, and the circumferential direction of the steering wheel 12 is indicated by an arrow L.

[0020] As shown in FIG. 1, the steering wheel 12 includes an annular rim portion 14 serving as a grip portion, a boss portion 16 provided in the center, and stay portions 18. The steering wheel 12 is provided with a metal core. The core is made up of a rim core portion 20 (see FIG. 2) of the rim portion 14, a boss core portion (not shown) of the boss portion, and a stay core portion (not shown) of the stay portions 18, and the rim core portion 20 is formed in an annular (ring-like) shape. In the steering wheel 12, the rim core portion 20 and the boss core portion are connected via the stay core portion, and the core portion forms a skeleton, integrating the rim portion 14, boss portion 16, and stay portions 18.

[0021] The vehicle is provided with a steering shaft (not shown), which is axially aligned along the longitudinal direction of the vehicle and rotatably supported by the vehicle body. The steering wheel 12 is supported by the steering shaft, with the boss core portion of the boss portion 16 fixed to the rear end of the steering shaft, and is rotatable integrally with the steering shaft. Therefore, when the steering wheel 12 is rotated, the steering shaft is rotated and the vehicle is steered.

[0022] 2, the rim portion 14 has a generally circular (or generally elliptical) cross section in the radial direction of the steering wheel 12, and a base body 22 formed in a circular ring shape from a resin material such as urethane as an insulating material is disposed within the rim portion 14. The rim portion 14 has a rim core metal portion 20 housed within the base body 22 by insert molding, and the rim core metal portion 20 is covered by the base body 22.

[0023] Additionally, a decorative portion 24 serving as a contact portion is disposed on the outer periphery of the base body 22, and the entire circumference of the base body 22 in the radial cross section of the steering wheel 12 and the entire circumference (entire area) of the steering wheel 12 are covered with the decorative portion 24. A resin material such as urethane is used as an insulating material for the decorative portion 24, and the rim portion 14 of the steering wheel 12 is decorated with the decorative portion 24. The decorative portion 24 may be made of leather such as tanned leather.

[0024] A touch sensor 28 including a sensor electrode 32 is embedded between the base 22 and the decorative portion 24 in the rim portion 14 of the steering wheel 12. The sensor electrode 32 is formed in a generally strip-like shape from a sheet-like or film-like conductive material. The touch sensor 28 may include a shield electrode formed in a generally strip-like shape from an insulating material, similar to the sensor electrode 32, with the sensor electrode 32 disposed on one side of the strip-like insulating material and the shield electrode disposed on the other side. The sensor electrode 32 (as well as the shield electrode) of the touch sensor 28 may be formed from a conductive cloth in which a conductive material such as a metal is attached to the surface of a stretchable fabric woven with warp and weft threads.

[0025] According to the present disclosure, since the accuracy of touch determination can be ensured even if the shield electrode is omitted, it is also possible to reduce the cost of the steering wheel 12 by omitting the shield electrode.

[0026] 1, the touch sensors 28 (sensor electrodes 32) have their longitudinal direction aligned with the circumferential direction of the steering wheel 12, and are arranged in the rim portion 14 in a range that extends approximately halfway around the circumferential direction of the steering wheel 12. Also, as shown in FIG. 2, the touch sensors 28 are wrapped around approximately the entire outer periphery of the base 22, with each sensor electrode 32 positioned radially outward from the rim portion 14 and its width direction aligned with the circumferential direction of the rim portion 14.

[0027] As a result, the touch sensor 28 is wrapped around the outer peripheral surface of the base body 22 over substantially the entire circumference of the steering wheel 12 and the rim portion 14, and is covered with the decorative portion 24. Furthermore, when the steering wheel 12 is in the straight-ahead steering position (the position shown in FIG. 1), one of the two touch sensors 28 is located on the right side of the vehicle and the other is located on the left side of the vehicle, and they are electrically separated. The left and right touch sensors 28 (left and right sensor electrodes 32) are each connected to a steering ECU 30 built into the boss portion 16 of the steering wheel 12, for example.

[0028] Although not shown, the steering ECU 30 includes a CPU (Central Processing Unit), memories such as a ROM (Read Only Memory) and a RAM (Random Access Memory), non-volatile storage such as a HDD (Hard Disk Drive) and an SSD (Solid State Drive), a communication I / F (Interface) unit, and an input / output I / F unit, which are communicatively connected to each other via a bus. A touch sensor 28 is connected to the input / output I / F unit via an A / D converter. In this embodiment, the steering ECU 30 is an example of a touch determination device according to the present disclosure.

[0029] A touch determination program is stored in the ROM or storage of the steering ECU 30. The touch determination program is read from the ROM or storage and loaded into memory, and the touch determination program loaded into memory is executed by the CPU, causing the steering ECU 30 to function as the capacitance detection unit 34, determination unit 36, setting unit 38, and correction unit 40 shown in Fig. 3. Of these, the correction unit 40 executes a reference value correction process, which will be described later.

[0030] For example, the capacitance detection unit 34 connects the sensor electrode 32 to a constant current source to charge the sensor electrode 32, and then acquires a detection signal of a voltage level corresponding to the capacitance value C of the sensor electrode 32 from the sensor electrode 32 via an A / D converter (not shown), and calculates the capacitance value C of the sensor electrode 32, for each of the left and right sensor electrodes 32 at predetermined time intervals. An example of the predetermined time is 100 ms.

[0031] The judgment unit 36 ​​compares the capacitance value C detected by the capacitance detection unit 34 with a reference value Cref for touch judgment set for each sensor electrode 32, and determines whether or not there is a touch in the area where the sensor electrode 32 is arranged, for each of the left and right sensor electrodes 32.

[0032] The setting unit 38 initially sets the reference value Cref for touch determination to the capacitance value C detected for the first time by the capacitance detection unit 34 when the steering ECU 30 is powered on, or the average value of the capacitance values ​​C detected multiple times by the capacitance detection unit 34 within a predetermined period after the steering ECU 30 is powered on. Furthermore, as shown in FIG. 5A , the setting unit 38 sets the reference value Cref for touch determination for the corresponding sensor electrode 32 to the capacitance value C detected by the capacitance detection unit 34 when the determination result by the determination unit 36 ​​indicates that the difference between the capacitance value C detected by the capacitance detection unit 34 during the no-touch period and the reference value Cref exceeds a predetermined value (|capacitance value C−reference value Cref|>predetermined value).

[0033] When the steering ECU 30 is powered on, the correction unit 40 calculates the difference ΔC between the capacitance values ​​of the left and right sensor electrodes 32 detected by the capacitance detection unit 34. When the area where one of the left and right sensor electrodes 32 is located is determined to be untouched and the area where the other sensor electrode 32 is located is determined to be touched, the correction unit 40 corrects the reference value Cref for touch determination of the sensor electrode 32 determined to be untouched, based on the difference ΔC in the capacitance values ​​and the reference value Cref for touch determination of the sensor electrode 32 determined to be untouched.

[0034] Next, as an operation of this embodiment, a reference value correction process that is started when the power supply to the steering ECU 30 is turned on and that is executed while the power supply to the steering ECU 30 is on will be described with reference to FIG.

[0035] In step 50, the correction unit 40 causes the capacitance detection unit 34 to detect the capacitance values ​​of the left and right sensor electrodes 32, and acquires the detected capacitance values ​​of the left and right sensor electrodes 32 from the capacitance detection unit 34. Note that the detected capacitance values ​​of the left and right sensor electrodes 32 are set by the setting unit 38 as the reference value Cref for touch determination of the left and right sensor electrodes 32, as described above.

[0036] In step 52, correction unit 40 calculates the difference ΔC between the capacitance values ​​of left and right sensor electrodes 32 acquired in step 50, and stores the calculated difference ΔC in capacitance values ​​in memory or the like (see also FIG. 8(A)). Also, in step 54, correction unit 40 acquires the capacitance values ​​of left and right sensor electrodes 32 in the same manner as in step 50.

[0037] 5A, the basic concept of touch determination will be described. As described above, when the amount of deviation between the capacitance value C detected by the capacitance detection unit 34 and the reference value Cref during the period in which the determination unit 36 ​​determines that there is no touch exceeds a predetermined value, the setting unit 38 sets the capacitance value C detected by the capacitance detection unit 34 as the reference value Cref for touch determination of the corresponding sensor electrode 32. The determination unit 36 ​​compares the capacitance value C detected by the capacitance detection unit 34 with the reference value Cref, and switches the determination result to no touch when the capacitance value C decreases to the reference value Cref.

[0038] However, the capacitance value C is temperature-dependent, and increases as the ambient temperature rises. Therefore, as shown in Fig. 5(B), if the ambient temperature rises during a period in which the determination unit 36 ​​determines that a touch has occurred, the capacitance value C does not decrease to the reference value Cref (see Fig. 5(C)), and it is no longer determined that no touch has occurred, even if the sensor electrode 32 has actually switched to a untouched state.

[0039] For this reason, in this embodiment, as shown in Fig. 6, the determination unit 36 ​​estimates the variation in parasitic capacitance during the period in which it determines that a touch has occurred, and reflects the estimated variation in parasitic capacitance in the reference value Cref. As a result, when the sensor electrode 32 switches to a untouched state, the capacitance value C decreases to the reference value Cref, thereby improving the accuracy of the touch determination. As the correction process for achieving the correction shown in Fig. 6, the correction unit 40 performs a first correction process in steps 56 to 62 and a second correction process in steps 64 to 74. The second correction process will be described first below.

[0040] In this embodiment, the sensor electrodes 32 are disposed on the left and right sides of the steering wheel 12, and the left and right sensor electrodes 32 are in the same temperature environment. Therefore, as shown in FIG. 7A, even if the parasitic capacitance of the left and right sensor electrodes 32 changes over time due to temperature changes or other factors, it is estimated that the difference ΔC between the parasitic capacitances of the left and right sensor electrodes 32 will be approximately constant. As a result, if the parasitic capacitance of one of the left and right sensor electrodes 32 can be accurately detected, the parasitic capacitance of the other sensor electrode 32 can be estimated. Furthermore, for a sensor electrode 32 determined by the determination unit 36 ​​to be untouched, the capacitance value C is approximately equal to the parasitic capacitance. Therefore, as shown in FIG. 8B, the reference value Cref of a sensor electrode determined to be untouched can be accurately corrected by using the capacitance value C of the sensor electrode 32 determined to be untouched in addition to the capacitance difference ΔC.

[0041] In the second correction process based on the above, first, in step 64, the correction unit 40 acquires the touch determination results of the left and right sensor electrodes 32 from the determination unit 36. Next, in step 66, the correction unit 40 determines whether one of the left and right sensor electrodes 32 has been determined to be touched and the other has been determined to be untouched, based on the touch determination results acquired in step 64. If the determination in step 66 is negative, the second correction process ends and the process returns to step 54.

[0042] On the other hand, if the determination in step 66 is positive, the process proceeds to step 68. In step 68, the correction unit 40 calculates an estimate of the reference value of the sensor electrode 32 determined to be touched from the reference value Cref of the sensor electrode 32 determined to be untouched and the capacitance difference ΔC. Specifically, as shown in FIG. 8B , the value obtained by subtracting the capacitance difference ΔC from the reference value Cref of the sensor electrode 32 determined to be untouched is set as the estimate of the reference value of the sensor electrode 32 determined to be touched.

[0043] In the next step 70, the correction unit 40 determines whether the actual reference value Cref of the sensor electrode 32 determined to have been touched is different from the estimated value calculated in step 68 by ±predetermined value X or more. If the determination in step 70 is negative, the process proceeds to step 72. In step 72, the correction unit 40 sets the estimated value calculated in step 68 as the reference value Cref of the sensor electrode 32 determined to have been touched. After the processing of step 72 is completed, the process returns to step 54.

[0044] If the determination in step 70 is affirmative, the process proceeds to step 74. In step 74, the correction unit 40 corrects the reference value Cref of the sensor electrode 32 that has been determined to be touched, as shown in FIG. 8C as an example, so that the difference from the estimated value becomes less than ±predetermined value X. After the process in step 74 is completed, the process returns to step 54. The above-described second correction process improves the accuracy of the touch determination.

[0045] Next, the first correction process will be described. The second correction process described above is a correction that can be applied only when one of the left and right sensor electrodes 32 is determined to be touched and the other is determined to be untouched, and cannot be applied when both the left and right sensor electrodes 32 are determined to be touched. Therefore, in this embodiment, the first correction process that can be applied even when both the left and right sensor electrodes 32 are determined to be touched is also performed.

[0046] 9 shows an example of changes in the capacitance value C of the sensor electrode 32. During period A when the user's touch state is stable, the capacitance value C of the sensor electrode 32 shows changes that roughly reflect changes in parasitic capacitance. However, during period B when the user's touch state changes from no-touch to touch, or from touch to no-touch, the capacitance value C of the sensor electrode 32 changes suddenly due to the change in the touch state. Based on the above, in the first correction process, period B when the capacitance derivative exceeds the threshold is excluded, and the reference value Cref is corrected according to changes in the capacitance value C during period A when the capacitance derivative is equal to or less than the threshold.

[0047] That is, in step 56, the correction unit 40 calculates the differential value of the capacitance value C acquired in step 54 for a predetermined one of the left and right sensor electrodes 32. In step 58, the correction unit 40 determines whether the differential value of the capacitance value C calculated in step 56 is equal to or less than a threshold value. If the determination in step 56 is positive, the process proceeds to step 60. In step 60, the correction unit 40 adds the capacitance differential value of the predetermined sensor electrode 32 to the reference value Cref for touch determination of the predetermined sensor electrode 32, and then proceeds to step 62. On the other hand, if the determination in step 56 is negative, the process skips step 60 and proceeds to step 62.

[0048] In step 62, the correction unit 40 determines whether or not the processes of steps 56 to 60 have been performed for each of the left and right sensor electrodes 32. If the determination in step 62 is negative, the process returns to step 56, and the processes from step 56 onwards are repeated. If the determination in step 62 is positive, the process proceeds to step 64. The above-described first correction process improves the accuracy of the touch determination even when a situation continues in which both the left and right sensor electrodes 32 are determined to be touched.

[0049] As described above, in this embodiment, the determination unit 36 ​​determines whether or not a touch has occurred for each of the multiple sensor electrodes 32 arranged in different regions of the vehicle steering wheel 12 by comparing the detected capacitance value C with the touch determination reference value Cref set for each sensor electrode 32. When a first region of the multiple sensor electrodes 32, where a first sensor electrode 32 is arranged, is determined to be untouched and a second region, where a second sensor electrode 32 is arranged, is determined to be touched, the correction unit 40 corrects the touch determination reference value Cref for the second sensor electrode 32 based on the difference ΔC between the capacitance values ​​detected when the first region and the second region are not touched and the reference value Cref for the touch determination for the first sensor electrode 32. This makes it possible to prevent a decrease in the accuracy of the touch determination due to, for example, changes in parasitic capacitance over time.

[0050] Furthermore, in this embodiment, the correction unit 40 corrects the reference value Cref for touch determination of the second sensor electrode 32 to an estimated value obtained by subtracting the capacitance difference ΔC from the reference value Cref for touch determination of the first sensor electrode 32. This allows the reference value for touch determination of the second sensor electrode 32 to be corrected to an appropriate value.

[0051] Furthermore, in the present embodiment, when the reference value for touch determination of the second sensor electrode 32 differs from the estimated value by a predetermined value or more, the correction unit 40 corrects the reference value Cref for touch determination of the second sensor electrode 32 so that the difference between the reference value Cref for touch determination of the second sensor electrode 32 and the estimated value becomes less than the predetermined value. This makes it possible to achieve touch determination that takes into account slight changes over time in the difference in parasitic capacitance of the sensor electrodes 32, compared to an aspect in which the reference value for touch determination is corrected to the estimated value even when the reference value for touch determination of the second sensor electrode 32 differs from the estimated value by a predetermined value or more.

[0052] Furthermore, in this embodiment, when the steering ECU 30 is powered on, the correction unit 40 calculates the difference ΔC between the capacitance values ​​detected for the plurality of sensor electrodes 32. This makes it possible to maintain the accuracy of the touch determination even if the capacitance value C of the sensor electrodes 32 changes over time.

[0053] Furthermore, in this embodiment, the setting unit 38 initially sets the capacitance value C detected for the first time for each of the left and right sensor electrodes 32 by the capacitance detection unit 34 when the steering ECU 30 is powered on, or the average value of the capacitance values ​​C detected multiple times for each of the left and right sensor electrodes 32 by the capacitance detection unit 34 within a predetermined period after the steering ECU 30 is powered on, as the reference value for touch determination for each sensor electrode 32. Furthermore, the setting unit 38 sets the detected capacitance value C as the reference value Cref for touch determination for the corresponding sensor electrode 32 when the determination result by the determination unit 36 ​​indicates that the difference between the capacitance value C detected during a no-touch period and the reference value Cref exceeds a predetermined value. This makes it possible to appropriately set the reference value Cref for touch determination for the sensor electrode 32 when the steering ECU 30 is powered on and when the determination result by the determination unit 36 ​​indicates that the difference between the capacitance value C detected during a no-touch period and the reference value Cref exceeds a predetermined value.

[0054] Furthermore, in this embodiment, the correction unit 40 calculates a differential value of the detected capacitance value, and when the calculated differential value of the capacitance value is equal to or less than a threshold value, corrects the corresponding reference value Cref for touch determination by the differential value of the capacitance, for each of the plurality of sensor electrodes 32. This makes it possible to prevent errors in the reference value Cref for touch determination from accumulating for each of the sensor electrodes 32, even when a situation continues in which an area where one sensor electrode 32 is provided is determined to be untouched and an area where the other sensor electrode 32 is provided is determined to be touched.

[0055] In the above embodiment, the correction unit 40 performs the first correction process in steps 56 to 62, and then performs the second correction process in steps 64 to 74. However, the present disclosure is not limited to the correction unit 40 performing the correction processes in the above order, and the correction unit 40 may perform the first correction process after performing the second correction process.

[0056] Furthermore, in the above embodiment, an aspect in which two sensor electrodes 32 are provided has been described, but the present disclosure is not limited to this and can also be applied to a case in which three or more sensor electrodes 32 are provided. When three or more sensor electrodes 32 are provided, the second correction process can be executed if the determination unit 36 ​​determines that the area in which any one of the sensor electrodes 32 is provided is untouched.

[0057] In the above embodiment, the first correction process is described as correcting the reference value Cref for touch determination with the capacitance derivative when the capacitance derivative is equal to or less than a threshold value, for each of the plurality of sensor electrodes 32. However, the present disclosure is not limited to this, and the first correction process may be performed by correcting the capacitance of each sensor electrode using a differential value indicating a change in capacitance for each sensor electrode, for example.

[0058] Furthermore, in the above embodiment, a vehicle is used as an example of a moving body, but the present disclosure is not limited thereto, and the moving body may be a ship, an airplane, etc. Furthermore, in the above embodiment, a steering wheel 12 is used as an example of an operating member, but the present disclosure is not limited thereto, and the operating member may be a shift body, etc.

[0059] Furthermore, in the above embodiment, the touch determination program is described as being pre-stored (installed) in ROM or storage, but the touch determination program can also be provided in a form recorded on a non-temporary recording medium such as an HDD, SSD, or DVD. [Explanation of symbols]

[0060] 12... steering wheel, 28... touch sensor, 30... steering ECU, 32... sensor electrode, 34... capacitance detection unit, 36... determination unit, 38... setting unit, 40... correction unit

Claims

1. a determination unit that determines whether or not a region in which a plurality of sensor electrodes are disposed in different regions of an operating member of the movable body is touched by comparing a detected capacitance value with a reference value for touch determination set for each of the sensor electrodes; and a correction unit that, when a first region in which a first sensor electrode is disposed among the plurality of sensor electrodes is determined to be untouched and a second region in which a second sensor electrode is disposed is determined to be touched, corrects the reference value for touch determination of the second sensor electrode based on a difference between capacitance values ​​detected in a state in which the first region and the second region are not touched and the reference value for touch determination of the first sensor electrode; A touch determination device comprising:

2. 2 . The touch determination device according to claim 1 , wherein the correction unit corrects the reference value for the touch determination of the second sensor electrode to an estimated value obtained by subtracting the difference in capacitance values ​​from the reference value for the touch determination of the first sensor electrode.

3. 3. The touch determination device according to claim 2, wherein, when the reference value for the touch determination of the second sensor electrode differs from the estimated value by a predetermined value or more, the correction unit corrects the reference value for the touch determination of the second sensor electrode so that the difference between the reference value for the touch determination of the second sensor electrode and the estimated value becomes less than the predetermined value.

4. The touch determination device according to claim 1 , wherein the correction unit calculates a difference between the capacitance values ​​detected for the plurality of sensor electrodes when the touch determination device is powered on.

5. 2. The touch determination device according to claim 1, further comprising: a setting unit that initially sets a reference value for touch determination for each sensor electrode to a capacitance value that is initially detected for each of the plurality of sensor electrodes when the touch determination device is powered on, or an average value of capacitance values ​​that are detected multiple times for each of the plurality of sensor electrodes within a predetermined period from the powering on of the touch determination device, and that sets the detected capacitance value to the reference value for touch determination for the corresponding sensor electrode when a deviation between the capacitance value detected during a no-touch period and the reference value exceeds a predetermined value in the determination result by the determination unit.

6. 2. The touch determination device according to claim 1, wherein the correction unit calculates a differential value of the detected capacitance value, and when the calculated differential value of the capacitance value is equal to or less than a threshold value, corrects the corresponding reference value for touch determination with the differential value of the capacitance for each of the plurality of sensor electrodes.

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