Disconnection determination device

Abstract

To improve accuracy of disconnection determination of a sensor electrode.SOLUTION: The dummy capacitance 40 is built in a steering ECU36 together with a disconnection / touch determination IC38 including an electrostatic capacitance detection part 46 and a multiplexer 42 capable of switching a connection destination of the electrostatic capacitance detection part 46, and variation of the electrostatic capacitance is made smaller than internal parasitic capacitance C _ ic of the disconnection / touch determination IC38. The judging section 56 judges disconnection of the wires of the sensor electrodes 32 by comparing the differential values Δ C between the first electrostatic capacitance detection values C1, which are detected by connecting the sensor electrodes 32 that are provided at the exterior of the steering wheel ECU36 to the electrostatic capacitance detecting section 46, and the second electrostatic capacitance detection values C2, which are detected by connecting the dummy capacitances 40 to the electrostatic capacitance detecting section 46, with the disconnection judging thresholds Cth1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a detection device that applies a voltage to a first electrode that detects contact or approach of a human body with an operation surface and a second electrode arranged opposite the first electrode, and detects a user operation on the operation surface based on a change in capacitance of the first electrode to which the voltage is applied. In this detection device, while applying a voltage to the first electrode and detecting a change in capacitance of the first electrode, the second electrode is forcibly set to ground potential, and based on the value of a detection signal obtained from the first electrode after grounding and the difference between the detection signals obtained from the first electrode before and after grounding, it determines whether the first electrode and the second electrode are disconnected. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2023-37347 Summary of the Invention [Problem to be solved by the invention]

[0004] When detecting a sensor electrode's wiring break by detecting its capacitance and comparing the detected capacitance value with a break detection threshold, the detected capacitance value includes the internal parasitic capacitance C_ic (see Figure 6) of the integrated circuit (IC), which includes a microcomputer, regardless of whether the break is present or absent. Therefore, depending on the magnitude of the IC's internal parasitic capacitance C_ic and its variation α, the difference between the detected capacitance value expected when the break is present and the detected capacitance value expected when the break is present becomes small. This can reduce the accuracy of the sensor electrode wiring break detection, or it can make it difficult to set the threshold, making it impossible to detect a break.

[0005] Specifically, as an example, when sensor electrodes are disposed on a steering wheel provided with heater wiring of a steering heater, as shown in FIG. 7, when there is a disconnection, the capacitance detection value becomes C_ic + C_ecu, and when there is no disconnection (and no touch), the capacitance detection value becomes C_ic + C_ecu + C_gnd + C_heater. Here, C_ic is the internal parasitic capacitance of the IC, C_ecu is the parasitic capacitance of the ECU, C_gnd is the parasitic capacitance of the sensor electrode (between the sensor electrode and the core metal of the steering wheel), and C_heater is the parasitic capacitance of the sensor electrode (between the sensor electrode and the steering heater) (see FIG. 6). Further, when there is no disconnection and a touch is made, the touch capacitance Cf (see FIG. 6) is further added to the capacitance detection value.

[0006] Here, if the variation of the internal parasitic capacitance C_ic of the IC is α, the variation of the parasitic capacitance C_ecu of the ECU is β, and the variation of the capacitance detection value when there is no disconnection is γ, then the capacitance detection value when there is a disconnection is within the range of C_ic + C_ecu ± (α + β), and the capacitance detection value when there is no disconnection (and no touch) is within the range of C_ic + C_ecu + C_gnd + C_heater ± γ. Thus, a value within the settable range that satisfies the condition of "C_ic + C_ecu + (α + β) < Cth1 < C_ic + C_ecu + C_gnd + C_heater - γ" is set as the disconnection determination threshold Cth1.

[0007] However, in many cases, the internal parasitic capacitance C_ic of the IC and its variation (tolerance) α are not published. In that case, the internal parasitic capacitance C_ic of the IC is measured actually, and the variation α is calculated statistically by standard deviation or the like. However, the calculated variation α is likely to be larger than the actual tolerance. As shown in FIG. 8, the variation width (α + β) of the capacitance detection value when there is a disconnection becomes large. As a result, particularly when the sensor parasitic capacitances C_gnd and C_heater are relatively small, etc., the settable range that satisfies the above condition becomes narrow, leading to a decrease in the accuracy of disconnection determination, or there may be no value that satisfies the above condition, resulting in the inability to determine a disconnection.

[0008] The present disclosure has been made in consideration of the above circumstances, and an object of the present disclosure is to provide a wire breakage determination device that can improve the accuracy of wire breakage determination. [Means for solving the problem]

[0009] The first aspect of the open circuit determination device is incorporated into an ECU (Electronic Control Unit) together with an integrated circuit including a capacitance detection unit and a switching unit capable of switching the connection destination of the capacitance detection unit, and includes a dummy capacitance having smaller capacitance variation than the internal parasitic capacitance of the integrated circuit, and a determination unit that determines an open circuit in the wiring of the sensor electrode by comparing the difference value between a first capacitance detection value detected by connecting a sensor electrode provided outside the ECU to the capacitance detection unit and a second capacitance detection value detected by connecting the dummy capacitance to the capacitance detection unit with a open circuit determination threshold.

[0010] In the second aspect, in the first aspect, a plurality of the sensor electrodes are provided, and the determination unit determines whether the wiring of each of the plurality of sensor electrodes is broken by comparing the difference values ​​between the plurality of first capacitance detection values ​​and the plurality of second capacitance detection values ​​detected for each of the plurality of sensor electrodes with the break determination threshold.

[0011] A third aspect is that, in the first or second aspect, when the parasitic capacitance of the ECU added to the first capacitance detection value includes a capacitive element whose temperature variation tolerance of capacitance is equal to or greater than a predetermined value, the dummy capacitance is composed of the capacitive element.

[0012] A fourth aspect is any one of the first to third aspects, wherein the sensor electrode is a touch sensor provided on an operation surface of a steering body for steering a moving body. [Effects of the Invention]

[0013] In a first aspect, an ECU includes an integrated circuit including a capacitance detection unit and a switching unit capable of switching the connection destination of the capacitance detection unit, and a dummy capacitance, the dummy capacitance having a smaller capacitance variation than the internal parasitic capacitance of the integrated circuit. The determination unit determines a disconnection of the sensor electrode wiring by comparing a difference between a first capacitance detection value detected by connecting a sensor electrode provided outside the ECU to the capacitance detection unit and a second capacitance detection value detected by connecting the dummy capacitance to the capacitance detection unit with a disconnection determination threshold. Note that the "variation" in the first aspect includes individual variations, temperature variations, and variations due to aging, which are general physical properties of capacitors (capacitance).

[0014] With the above configuration, the first and second capacitance detection values ​​each include the internal parasitic capacitance C_ic of the integrated circuit (IC), and the internal parasitic capacitance C_ic of the integrated circuit is canceled out and removed from the difference between the first and second capacitance detection values. Furthermore, since the second capacitance detection value includes the capacitance value C_dummy of the dummy capacitance, the difference value also includes the capacitance value C_dummy of the dummy capacitance. Here, since the dummy capacitance has smaller capacitance variations than the internal parasitic capacitance of the integrated circuit, the difference value has a smaller fluctuation range in capacitance value than the first capacitance detection value. This expands the settable range of the disconnection detection threshold Cth1 (increasing the difference between the maximum capacitance detection value when a disconnection occurs and the minimum capacitance detection value when no disconnection occurs), thereby improving the accuracy of disconnection detection.

[0015] In the second aspect, in an aspect in which multiple sensor electrodes are provided, the second capacitance detection value is commonly used to determine whether each sensor electrode is disconnected, thereby simplifying the configuration of the disconnection determination device of the present disclosure in the above aspect.

[0016] In a third aspect, when the ECU's parasitic capacitance added to the first capacitance detection value includes a capacitive element whose temperature variation tolerance of capacitance is equal to or greater than a predetermined value, the dummy capacitance is configured by the capacitive element. In this case, the first capacitance detection value and the second capacitance detection value each include the capacitance value of the capacitive element, and the capacitance value of the capacitive element, including the temperature variation tolerance component, is canceled out and removed from the difference value between the first capacitance detection value and the second capacitance detection value. This suppresses fluctuations in the difference value due to temperature changes, further improving the accuracy of disconnection determination.

[0017] In a fourth aspect, in an aspect in which a touch sensor (sensor electrode) is provided on the operation surface of a steering body for steering a moving body, the accuracy of determining whether the wiring of the touch sensor (sensor electrode) is broken can be improved. [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] This is a schematic diagram of the disconnection / touch detection IC built into the steering ECU. [Figure 4] 10 is a flowchart showing a disconnection / touch determination process executed by a microcomputer. [Figure 5] 4 is a diagram showing an example of a disconnection determination threshold Cth1 in the present embodiment. FIG. [Figure 6] 10A and 10B are conceptual diagrams showing various parasitic capacitances in determining whether a wire is broken; [Figure 7] 10 is a diagram showing an example of a disconnection determination threshold Cth1 when the internal parasitic capacitance C_ic of an IC and the variation α are known. [Figure 8] 10 is a diagram showing an example of a disconnection determination threshold Cth1 when the internal parasitic capacitance C_ic of an IC is actually measured to obtain a variation α. 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 a steering body 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] 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.

[0026] 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 36 built into the boss portion 16 of the steering wheel 12, for example.

[0027] In this embodiment, the steering ECU 36 is an example of a touch determination device according to the present disclosure. As is clear from FIG. 1, in this embodiment, the left and right sensor electrodes 32 are provided outside the steering ECU 36.

[0028] 2, heater wiring 34 for the steering heater is embedded in the base 22. The heater wiring 34 is connected to a heater drive circuit (not shown), and when a heater switch provided on the instrument panel of the vehicle or the like is turned on, it is energized and generates heat, thereby raising the temperature of the rim portion 14 of the steering wheel 12.

[0029] 3, the steering ECU 36 is provided with an open / touch determination IC 38 and a dummy capacitor 40. The open / touch determination IC 38 includes a multiplexer 42, a constant current source 44, a capacitance detection unit 46, and a microcomputer 54. The left and right sensor electrodes 32 and the dummy capacitor 40 are each connected to the multiplexer 42. The open / touch determination IC 38 is an example of an integrated circuit in the present disclosure. The multiplexer 42 is an example of a switching unit in the present disclosure.

[0030] In this embodiment, when the internal parasitic capacitance of the open circuit / touch judgment IC 38 is C_ic and its variation is α, and the capacitance of the dummy capacitance 40 is C_dummy and its variation is σ, an element whose capacitance variation is smaller than that of the open circuit / touch judgment IC 38 (σ<α) is used as the dummy capacitance 40.

[0031] The constant current source 44 is connected to the multiplexer 42. The capacitance detection unit 46 includes a switching element 48, a sample-and-hold capacitor 50, and an A / D converter 52. An input terminal of the A / D converter 52 is connected to the multiplexer 42 via the switching element 48, and one end of the sample-and-hold capacitor 50, one end of which is grounded, is connected between the A / D converter 52 and the switching element 48. A control terminal of the switching element 48 and an input terminal of the A / D converter 52 are connected to a microcomputer 54.

[0032] Although not shown in the figure, the microcomputer 54 includes a CPU (Central Processing Unit), memory such as ROM (Read Only Memory) and RAM (Random Access Memory), non-volatile storage such as HDD (Hard Disk Drive) and SSD (Solid State Drive), a communication I / F (Interface) section, and an input / output I / F section, which are connected to each other via a bus so that they can communicate with each other.

[0033] In addition, a disconnection / touch determination program is stored in the ROM or storage of the microcomputer 54. The microcomputer 54 functions as a determination unit 56 by reading the disconnection / touch determination program from the ROM or storage and expanding it in memory, and then executing the touch determination program expanded in memory by the CPU.

[0034] The determination unit 56 determines whether the wiring of the sensor electrode 32 is broken by comparing the difference value ΔC between the first capacitance detection value C1 detected by connecting the sensor electrode 32 provided outside the steering ECU 36 to the capacitance detection unit 46 and the second capacitance detection value C2 detected by connecting the dummy capacitance 40 to the capacitance detection unit 46 with the break determination threshold Cth1.

[0035] Next, the disconnection / touch determination process that is repeatedly executed by the microcomputer 54 while the ignition switch of the vehicle is on will be described with reference to FIG.

[0036] In step 70 of the disconnection / touch determination process, the determination unit 56 switches the multiplexer 42 so that the dummy capacitance 40 is connected to the constant current source 44, thereby charging the dummy capacitance 40. In step 72, the determination unit 56 switches the multiplexer 42 so that the dummy capacitance 40 is connected to the capacitance detection unit 46, turns on the switching element 48 for a predetermined time, and acquires a detection signal of a voltage level corresponding to the capacitance of the dummy capacitance 40 via the A / D converter 52, thereby detecting the capacitance of the dummy capacitance 40 (second capacitance detection value C2).

[0037] In step 74, the determination unit 56 selects one of the left and right sensor electrodes 32 as a target for determination of disconnection and touch. Then, the determination unit 56 switches the multiplexer 42 so that the selected sensor electrode 32 is connected to the constant current source 44, thereby charging the sensor electrode 32. In step 76, the determination unit 56 switches the multiplexer 42 so that the sensor electrode 32 is connected to the capacitance detection unit 46, turns on the switching element 48 for a predetermined time, and acquires a detection signal of a voltage level corresponding to the capacitance of the sensor electrode 32 via the A / D converter 52, thereby detecting the capacitance of the sensor electrode 32 (first capacitance detection value C1).

[0038] In step 78, the determination unit 56 calculates the absolute value of the difference between the first capacitance detection value C1 and the second capacitance detection value C2 as the capacitance difference value ΔC. Then, in step 80, the determination unit 56 determines whether the capacitance difference value ΔC calculated in step 78 is greater than a preset disconnection determination threshold value Cth1.

[0039] Here, when the wiring of the sensor electrode 32 to be determined is broken, the first capacitance detection value C1 of the sensor electrode 32 to be determined is C_ic+C_ecu, with a variation of ±(α+β) (see also FIG. 5 ). On the other hand, the second capacitance detection value C2 is C_ic+C_dummy, with a variation of ±σ (where σ<α). Therefore, when the wiring of the sensor electrode 32 to be determined is broken, the capacitance difference value ΔC is C_ecu-C_dummy, with a variation of ±(β+σ). This cancels out and eliminates the internal parasitic capacitance C_ic of the break / touch determination IC 38, and reduces its variation (fluctuation range). Therefore, as is clear from FIG. 5 , the settable range of the break determination threshold Cth1 (the difference between the maximum capacitance value when the break occurs and the minimum capacitance value when the break does not occur) is expanded, improving the accuracy of break determination.

[0040] If the determination in step 80 is negative, the process proceeds to step 82. In step 82, the determination unit 56 notifies the occurrence of the disconnection by, for example, switching the display on a display unit such as an in-vehicle display or outputting audio from an audio output unit such as an in-vehicle speaker, and then the process proceeds to step 84. On the other hand, if the determination in step 80 is positive, the process skips step 82 and proceeds to step 84.

[0041] In step 84, the determination unit 56 compares the first capacitance detection value C1 with a preset touch determination threshold Cth2 to determine whether the area where the sensor electrode 32 is located is being touched (whether the touch capacitance Cf (see FIG. 6) is added to the first capacitance detection value C1), and outputs the determination result to a predetermined ECU. An example of the predetermined ECU is an ECU that performs processing to determine the driver's physical condition, specifically, drowsiness and fatigue level, based on the driver's electrocardiogram waveform detected by the sensor electrode 32 during the period when it is determined that the area where the sensor electrode 32 is located is being touched. Note that, instead of the first capacitance detection value C1, the capacitance difference value ΔC may be compared with the touch determination threshold Cth2 to determine whether the area where the sensor electrode 32 is located is being touched.

[0042] In step 86, the determination unit 56 determines whether or not the disconnection and touch determination has been performed for all of the sensor electrodes 32. If the determination in step 86 is negative, the process returns to step 74, and the process of step 74 is repeated for each of the sensor electrodes 32 for which the disconnection and touch determination has not yet been performed. Then, once the disconnection and touch determination has been performed for each of the left and right sensor electrodes 32, the determination in step 86 is positive, and the disconnection / touch determination process is completed.

[0043] As described above, in this embodiment, the dummy capacitor 40 is built into the steering ECU 36 together with the open-circuit / touch determination IC 38, which includes the capacitance detection unit 46 and the multiplexer 42 that can switch the connection destination of the capacitance detection unit 46. The dummy capacitor 40 has smaller capacitance variation than the internal parasitic capacitance C_ic of the open-circuit / touch determination IC 38. The determination unit 56 determines whether the wiring of the sensor electrode 32 is open by comparing the difference value ΔC between the first capacitance detection value C1, which is detected by connecting the sensor electrode 32, provided outside the steering ECU 36 to the capacitance detection unit 46, and the second capacitance detection value C2, which is detected by connecting the dummy capacitor 40 to the capacitance detection unit 46, with the open-circuit determination threshold Cth1. This expands the settable range of the open-circuit determination threshold Cth1, thereby improving the accuracy of the open-circuit determination.

[0044] In this embodiment, a plurality of sensor electrodes 32 are provided, and the determination unit 56 determines whether or not there is a break in the wiring of each of the plurality of sensor electrodes 32 by comparing the difference value ΔC between the plurality of first capacitance detection values ​​C1 and the plurality of second capacitance detection values ​​C2 detected for each of the plurality of sensor electrodes 32 with a break-determination threshold Cth1. This simplifies the configuration of the break-determination device (steering ECU 36) in an embodiment in which a plurality of sensor electrodes 32 are provided.

[0045] In this embodiment, the sensor electrode 32 constitutes a touch sensor 28 provided on the operation surface of the steering wheel 12 for steering the vehicle. This improves the accuracy of determining whether the wiring of the touch sensor 28 (sensor electrode 32) is broken in an aspect in which the touch sensor 28 (sensor electrode 32) is provided on the operation surface of the steering wheel 12 for steering the vehicle.

[0046] In the above embodiment, the dummy capacitor 40 is an element having a capacitance variation smaller than that of the open / touch determination IC 38 (σ<α). If the parasitic capacitance C_ecu of the steering ECU 36, which is added to the first capacitance detection value C1, includes a capacitive element (e.g., a Zener diode) having a capacitance temperature variation tolerance equal to or greater than a predetermined value, the dummy capacitor 40 may be configured with the capacitive element as long as the condition of "having a capacitance variation smaller than that of the open / touch determination IC 38 (σ<α)" is satisfied. In this case, the first capacitance detection value C1 and the second capacitance detection value C2 each include the capacitance value of the capacitive element. Therefore, the capacitance value of the capacitive element, including the temperature variation tolerance, is canceled out and removed from the difference value ΔC between the first capacitance detection value C1 and the second capacitance detection value C2. This suppresses fluctuations in the difference value ΔC due to temperature changes, further improving the accuracy of open circuit determination.

[0047] Furthermore, in the above embodiment, the present disclosure is described as being applied to a configuration in which two sensor electrodes 32 are provided, but the present disclosure is also applicable to a configuration in which only one sensor electrode 32 is provided, or to a configuration in which three or more sensor electrodes 32 are provided.

[0048] In the above embodiment, the sensor electrode 32 is disposed on the steering wheel 12 provided with a steering heater to perform the disconnection / touch determination. However, the present disclosure is not limited to this, and may be applied to a steering wheel that is not provided with a steering heater.

[0049] Furthermore, in the above embodiment, a vehicle is used as an example of a moving body, but the present invention is not limited to this, and the moving body may be a ship, an airplane, or the like. [Explanation of symbols]

[0050] 12... steering wheel (steering body), 28... touch sensor, 32... sensor electrode, 36... steering ECU, 38... open circuit / touch determination IC (integrated circuit), 40... dummy capacitance, 42... multiplexer (switching unit), 46... capacitance detection unit, 56... determination unit

Claims

1. a dummy capacitance that is built into the ECU together with an integrated circuit including a capacitance detection unit and a switching unit that can switch a connection destination of the capacitance detection unit, and that has a smaller variation in capacitance than the internal parasitic capacitance of the integrated circuit; a determination unit that determines a disconnection of the wiring of the sensor electrode by comparing a difference value between a first capacitance detection value detected by connecting a sensor electrode provided outside the ECU to the capacitance detection unit and a second capacitance detection value detected by connecting the dummy capacitance to the capacitance detection unit with a disconnection determination threshold; and A wire breakage determination device including:

2. a plurality of the sensor electrodes are provided; 2. The open circuit determination device according to claim 1, wherein the determination unit determines the open circuit in the wiring of each of the plurality of sensor electrodes by comparing the difference values ​​between the plurality of first capacitance detection values ​​and the plurality of second capacitance detection values ​​detected for each of the plurality of sensor electrodes with the open circuit determination threshold value.

3. 2. The open circuit determination device according to claim 1, wherein when the parasitic capacitance of the ECU added to the first capacitance detection value includes a capacitive element whose temperature variation tolerance of capacitance is equal to or greater than a predetermined value, the dummy capacitance is composed of the capacitive element.

4. 2. The disconnection determination device according to claim 1, wherein the sensor electrode is a touch sensor provided on an operating surface of a steering body for steering a moving body.

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