Contact detection device

Abstract

To provide a contact detection device capable of accurately detecting contact of a conductor to a contacted section.SOLUTION: A contact detection device 100 comprises an electrostatic sensor 111, a reference capacitor 120, an AC power supply 130, and a contact detection section 140. The electrostatic sensor 111 is provided in a contacted section 110 of a grip section 3. The reference capacitor 120 is provided in a place other than the contacted section 110. The contact detection section 140 performs measurement value acquisition processing for acquiring a contact section measurement value and a reference measurement value on the basis of one of an orthogonal phase component and an in-phase phase component obtained by performing quadrature demodulation of each of output signals from the electrostatic sensor 111 and the reference capacitor 120 to which an AC voltage is applied. The contact detection section 140 detects contact of a conductor to the contacted section 110 according to the fact that a differential value for indicating a difference between a reference measurement value and a contacted section measurement section is within a predetermined contact range.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The disclosed technology relates to a contact detection device including a contact detection unit that detects contact of a conductor with a contacted part. [Background technology]

[0002] For example, a contact detection device that detects contact with a human body may be mounted on the steering wheel of an automobile. As a contact detection device that detects contact with a conductor such as a human body, for example, Patent Document 1 discloses a technology that performs contact detection using an electrostatic sensor. Patent Document 1 also discloses a technology that corrects the sensitivity of contact detection by an electrostatic sensor according to the operating time of a peripheral device. This makes it possible to appropriately correct the sensitivity of contact detection by an electrostatic sensor, which fluctuates with changes in environmental temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-048290 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, the ambient temperature of a contact detection device does not necessarily change depending on the operating time of peripheral devices. For example, the ambient temperature of a contact detection device related to a steering wheel of an automobile may change depending on multiple factors, such as weather and season. For this reason, the above-mentioned conventional technology may not be able to accurately correct the sensitivity of the contact detection of the electrostatic sensor. This may result in inaccurate detection of the contact of a conductor.

[0005] The disclosed technique provides a contact detection device that can accurately detect contact of a conductor with a contacted part. [Means for solving the problem]

[0006] One aspect of the disclosed technology is a contact detection device that includes an electrostatic sensor provided on a contacted portion, a reference capacitor provided on a reference portion other than the contacted portion, an AC power supply that applies an AC voltage to the electrostatic sensor and the reference capacitor, and a contact detection unit that detects contact of a conductor with the contacted portion, wherein the contact detection unit performs a measurement value acquisition process to acquire a measurement value based on either a quadrature phase component or an in-phase phase component obtained by quadrature demodulating the output signals from the electrostatic sensor and the reference capacitor to which the AC voltage has been applied, and detects contact of the conductor with the contacted portion when a differential value indicating the difference between the contacted portion measurement value, which is the measurement value related to the electrostatic sensor acquired in the measurement value acquisition process, and the reference measurement value, which is the measurement value related to the reference capacitor, is within a predetermined contact range.

[0007] The measurement value of the electrostatic sensor provided on the contacted part may fluctuate with changes in the environmental temperature. In this contact detection device, if the measurement value of the electrostatic sensor fluctuates with changes in the environmental temperature, the measurement value of the reference capacitor will also fluctuate with changes in the environmental temperature. In other words, because both the measurement value of the electrostatic sensor and the measurement value of the reference capacitor fluctuate with changes in the environmental temperature, the difference between these values ​​is less susceptible to the influence of the environmental temperature. Therefore, the contact detection device according to the above aspect can accurately detect contact of a conductor with the contacted part. [Effects of the Invention]

[0008] According to the disclosed technique, a contact detection device capable of accurately detecting contact of a conductor with a contacted part is provided. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing a steering wheel provided with a contacted portion of a contact detection device according to an embodiment; [Figure 2] 1 is a schematic configuration diagram of a contact detection device according to an embodiment; [Figure 3] 10 is a flowchart illustrating a procedure of a contact detection process executed by a contact detection unit of the contact detection device according to the embodiment. [Figure 4] 10 is a flowchart showing the procedure of measurement range offset processing in the contact detection processing according to the first embodiment. [Figure 5] 10 is a flowchart showing the procedure of a contact determination process in the contact detection process. [Figure 6] FIG. 10 is a graph showing the relationship between the value of the quadrature component and temperature. [Figure 7] 10 is a graph showing the relationship between the temperature and the corrected measurement value obtained while performing the measurement range offset process according to the first embodiment. FIG. [Figure 8] 4 is a graph showing the relationship between the temperature and the raw measurement value acquired while performing the measurement range offset process according to the first embodiment. FIG. [Figure 9] 10 is a temperature offset table used in the measurement range offset process according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments embodying the present disclosure will be described in detail with reference to the accompanying drawings. First, a first embodiment, which is one of the embodiments, will be described, and then a second embodiment, which is different from the first embodiment, will be described.

[0011] First Embodiment FIG. 1 shows a steering wheel 1 equipped with a contact detection device 100 according to a first embodiment. The contact detection device 100 detects contact of a human body with the steering wheel 1. The steering wheel 1 has a base 2 and a grip portion 3. The base 2 is located near the center of the steering wheel 1 and is connected to the steering shaft. The grip portion 3 in this embodiment is provided in an annular shape so as to surround the base 2 from the outside. The grip portion 3 is fixed to the base 2 via spokes 4. The steering wheel 1 is mounted on a vehicle, and, for example, a driver can hold the grip portion 3 with their hands and input operations related to the direction of travel of the vehicle.

[0012] The contact detection device 100 has a contacted part 110 provided on the grip part 3. The contact detection device 100 detects contact of a conductor with the contacted part 110 by a capacitance method. Therefore, the contact detection device 100 can detect contact of the human body, which is a conductor, with the contacted part 110. This allows the contact detection device 100 to detect a state in which the driver is gripping the grip part 3 of the steering wheel 1.

[0013] 2 is a block diagram showing the configuration of the contact detection device 100. The contact detection device 100 includes a contacted part 110, a reference capacitor 120, an AC power supply 130, and a contact detection unit 140. The contacted part 110 of this embodiment, which is provided in the grip part 3, has an electrostatic sensor 111 and a skin 112. The skin 112 forms the surface of the grip part 3. The electrostatic sensor 111 is provided on the inner side of the skin 112. The electrostatic sensor 111 of this embodiment is a capacitor.

[0014] The contacted portion 110 is provided continuously around the circumference of the annular grip portion 3. The contacted portion 110 may be provided in a portion of the grip portion 3. Alternatively, multiple regions may be provided around the circumference of the grip portion 3, and a contacted portion 110 may be provided in each region. Furthermore, for example, the contacted portion 110 may be configured without the skin 112.

[0015] The reference capacitor 120 is a capacitor having temperature characteristics similar to those of the electrostatic sensor 111. In this embodiment, a capacitor having the same capacitance as that of the electrostatic sensor 111 is used as the reference capacitor 120. More specifically, the reference capacitor 120 in this embodiment is a multilayer ceramic chip capacitor having the same capacitance as that of the electrostatic sensor 111. Furthermore, the reference capacitor 120 in this embodiment is provided in the contact detection unit 140. In other words, it is provided in a location other than the grip portion 3 that is the contacted portion 110.

[0016] The AC power supply 130 is connected to the capacitive sensor 111 and the reference capacitor 120. The AC power supply 130 can apply an AC voltage to the capacitive sensor 111 and the reference capacitor 120, respectively.

[0017] The contact detection unit 140 includes a measurement value acquisition unit 150, a measurement range offset unit 160, a difference value calculation unit 170, a contact determination unit 180, and a storage unit 190. The measurement value acquisition unit 150 includes a contacted portion measurement value acquisition unit 151 and a reference measurement value acquisition unit 152.

[0018] The input side of the contacted part measurement value acquiring unit 151 is connected to the electrostatic sensor 111. This allows the contacted part measurement value acquiring unit 151 to acquire an output signal output from the electrostatic sensor 111 to which an AC voltage is applied. Furthermore, the contacted part measurement value acquiring unit 151 A / D converts the output signal from the electrostatic sensor 111 and performs quadrature demodulation, thereby acquiring a quadrature phase component or an in-phase component as a measurement value through the quadrature demodulation.

[0019] The input side of the reference measurement value acquiring unit 152 is connected to the reference capacitor 120. This allows the reference measurement value acquiring unit 152 to acquire the output signal output from the reference capacitor 120 to which an AC voltage is applied. Furthermore, the reference measurement value acquiring unit 152 A / D converts and quadrature demodulates the output signal from the reference capacitor 120 to which an AC voltage is applied, and can acquire the quadrature phase component or the in-phase phase component as a measurement value by the quadrature demodulation.

[0020] In this embodiment, contacted part measurement value acquisition unit 151 and reference measurement value acquisition unit 152 acquire the same phase component of the quadrature phase component and the in-phase phase component as a measurement value. In other words, when contacted part measurement value acquisition unit 151 acquires a value related to the quadrature phase component as a measurement value, reference measurement value acquisition unit 152 also acquires a value related to the quadrature phase component as a measurement value. Note that the measurement value acquired by contacted part measurement value acquisition unit 151 may be referred to as the contacted part measurement value hereinafter. The measurement value acquired by reference measurement value acquisition unit 152 may be referred to as the reference measurement value hereinafter.

[0021] The measurement range offset unit 160 can execute a measurement range offset process that can change the offset amount of the measurement range. In this embodiment, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 can accurately acquire measurement values ​​based on output signals that result in measurement values ​​that fall within the measurement range. Therefore, the measurement range offset unit 160 can switch the offset amount of the measurement range so that measurement values ​​related to the output signals input to the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 appropriately fall within the measurement range. This point will be described in detail later.

[0022] In this embodiment, the offset of the measurement range by the measurement range offset unit 160 is determined in advance according to the reference measurement value. In short, when a value near the upper limit of the current measurement range is likely to be measured as the reference measurement value, the measurement range offset unit 160 offsets the measurement range higher than the current value. On the other hand, when a value near the lower limit of the current measurement range is likely to be measured as the reference measurement value, the measurement range offset unit 160 offsets the measurement range lower than the current value. In other words, the measurement range offset unit 160 has a plurality of measurement ranges each determined in advance in a different range, and can switch the measurement range to be used from among these plurality of measurement ranges according to the reference measurement value.

[0023] Specifically, in this embodiment, the measurement ranges include a normal measurement range, a low measurement range offset toward lower values ​​than the normal measurement range, and a high measurement range offset toward higher values ​​than the normal measurement range. In this embodiment, the state in which no offset is set (a state in which the offset amount is zero) is the normal measurement range. Furthermore, the high measurement ranges include a first high measurement range and a second high measurement range offset toward higher values ​​than the first high measurement range. In other words, in this embodiment, the measurement ranges are predefined in order from the highest value to the lowest: the second high measurement range, the first high measurement range, the normal measurement range, and the low measurement range.

[0024] Here, when the measurement range is offset from the normal measurement range by the measurement range offset unit 160, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 each acquire a measurement value that differs from the actual value depending on the offset amount of the measurement range. That is, for example, when an offset is performed to set the measurement range to the low measurement range, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 acquire a measurement value that is higher than the actual value by the offset amount of the low measurement range from the normal measurement range. Also, for example, when an offset is performed to set the measurement range to the first high measurement range, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 acquire a measurement value that is lower than the actual value by the offset amount of the first high measurement range from the normal measurement range.

[0025] The measurement values ​​acquired by the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 as they are without taking into account the offset amount of the measurement range may hereinafter be referred to as raw measurement values. Also, the raw measurement values ​​acquired by the contacted part measurement value acquisition unit 151 may hereinafter be referred to as contacted part raw measurement values. The raw measurement values ​​acquired by the reference measurement value acquisition unit 152 may hereinafter be referred to as reference raw measurement values.

[0026] The offset amount of the measurement range by the measurement range offset unit 160 is known in the contact detection device 100. Therefore, after acquiring a raw measurement value, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 can also acquire an actual value by taking the measurement range offset into account. The raw measurement value corrected to an actual value by taking the measurement range offset into account may hereinafter be referred to as a corrected measurement value.

[0027] For example, if the measurement range is offset toward the higher value side relative to the normal measurement range, the corrected measurement value can be calculated by adding the offset amount of the measurement range to the raw measurement value. If the measurement range is offset toward the lower value side relative to the normal measurement range, the corrected measurement value can be calculated by subtracting the offset amount of the measurement range from the raw measurement value. Furthermore, a corrected measurement value obtained by correcting the contacted part raw measurement value according to the offset amount of the measurement range may be hereinafter referred to as a contacted part corrected measurement value. A corrected measurement value obtained by correcting the reference raw measurement value according to the offset amount of the measurement range may be hereinafter referred to as a reference corrected measurement value.

[0028] The difference value calculation unit 170 performs a difference value calculation process to calculate a difference value that indicates the difference between the contacted part measurement value and the reference measurement value. The difference value can be calculated, for example, by subtracting the contacted part measurement value from the reference measurement value. The difference value may be any value that indicates the difference between the contacted part measurement value and the reference measurement value, and instead of subtraction, the difference value may be calculated, for example, as the ratio of the contacted part measurement value to the reference measurement value.

[0029] The measurement value used to calculate the difference value may be either a raw measurement value or a corrected measurement value. The same raw measurement value or corrected measurement value may be used as the contacted part measurement value and the reference measurement value, respectively. That is, for example, the difference value may be calculated by subtracting the contacted part raw measurement value from the reference raw measurement value. Also, for example, the difference value may be calculated by subtracting the contacted part corrected measurement value from the reference corrected measurement value.

[0030] As described above, the raw measurement value differs from the actual value depending on the offset amount of the measurement range. However, even if the measurement range is offset from the normal measurement range, for example, the difference itself is the same as when there is no offset. In other words, the difference value calculated by subtracting the contacted part raw measurement value from the reference raw measurement value is the same as the difference value calculated by subtracting the contacted part corrected measurement value from the reference corrected measurement value. Therefore, the difference value calculation unit 170 can appropriately calculate the difference value regardless of the offset of the measurement range, whether using the raw measurement value or the corrected measurement value.

[0031] The contact determination unit 180 performs contact determination processing based on the difference value calculated by the difference value calculation unit 170. In the contact determination processing, it determines whether or not the difference value is a value indicating a contact state. Specifically, in the contact determination processing, if the difference value is a value within a predetermined contact range, the contact determination unit 180 determines that the driver's hand is in contact with the contacted unit 110. On the other hand, in the contact determination processing, if the contact state is not determined, it determines that the driver's hand is not in contact with the contacted unit 110, indicating a non-contact state. In other words, in the contact determination processing, if the difference value is a value outside the contact range, it determines that the non-contact state is present. In this way, the contact detection unit 140 can detect the driver's contact with the contacted unit 110.

[0032] In the contact detection device 100 of this embodiment, the contact detection unit 140 is provided inside the base 2 of the steering wheel 1. More specifically, the contact detection unit 140 is provided in an inner space away from the surface of the base 2 so that the reference capacitor 120 outputs an output signal of the same level regardless of whether the driver is in contact with the surface of the base 2 or not. This prevents the output signal from the reference capacitor 120 from being affected by the operation status of the steering wheel 1 by the driver, etc.

[0033] Furthermore, in the contact detection device 100 of this embodiment, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 are arranged close to each other in the same space so that their environments are similar. The measurement values ​​acquired by the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 may vary depending on the environmental temperature. The degree of variation in the measurement values ​​tends to be significantly affected by temperature changes in the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152. That is, the contacted part measurement value acquired by the contacted part measurement value acquisition unit 151 may differ depending on the temperature of the contacted part measurement value acquisition unit 151 even if the degree of contact of the driver's hand with the contacted part 110 is the same. Specifically, for example, even if no conductor is in contact with the contacted part 110 at all, the contacted part measurement value acquired by the contacted part measurement value acquisition unit 151 may differ if the temperature of the contacted part measurement value acquisition unit 151 is different.

[0034] In this embodiment, both contacted part measurement value acquisition unit 151 and reference measurement value acquisition unit 152 are placed in an environment with the same temperature. Therefore, when the contacted part measurement value acquired by contacted part measurement value acquisition unit 151 fluctuates due to the environmental temperature, the reference measurement value acquired by reference measurement value acquisition unit 152 also fluctuates in the same way. In other words, it is possible to acquire values ​​as the contacted part measurement value and the reference measurement value that are both affected by the environmental change to the same extent, rather than a value where only one of them is affected by the environmental change. Therefore, the difference between the contacted part measurement value and the reference measurement value can be accurately calculated without being affected by the environment.

[0035] The storage unit 190 stores various values ​​necessary for the processing performed by the contact detection unit 140. For example, it stores the offset amount for each measurement range, the contact range to be compared with the difference value, etc. Furthermore, if necessary, it may have an area for storing previously acquired or calculated values.

[0036] Next, the contact detection process performed by the contact detection unit 140 will be described with reference to Fig. 3 to Fig. 5. As shown in Fig. 3, in the contact detection process, the contact detection unit 140 performs a measurement value acquisition process (S101), a measurement range offset process (S102), a difference value calculation process (S103), and a contact determination process (S104).

[0037] In the measurement value acquisition process (S101), the contacted part measurement value acquisition unit 151 of the measurement value acquisition unit 150 acquires the contacted part measurement value A based on the output signal from the electrostatic sensor 111 to which an AC voltage is applied. Also, the reference measurement value acquisition unit 152 of the measurement value acquisition unit 150 acquires the reference measurement value B based on the output signal from the reference capacitor 120 to which an AC voltage is applied.

[0038] In the measurement range offset process (S102), the measurement range offset unit 160 may offset the measurement range to a higher value or a lower value than the current value. The measurement range offset process (S102) of this embodiment can offset the measurement range based on the reference measurement value B acquired in the measurement value acquisition process (S101).

[0039] Specifically, in the measurement range offset process (S102), the measurement range offset unit 160 first determines whether the reference measurement value B acquired in the measurement value acquisition process (S101) is higher than the upper limit of the reference range (S111), as shown in FIG. 4. The reference range is set within the measurement range and is a range that serves as a reference for changing the offset of the measurement range. In this embodiment, the upper limit of the reference range is a value lower than the upper limit of the measurement range. The lower limit of the reference range is a value higher than the lower limit of the measurement range.

[0040] In this embodiment, as described above, four measurement ranges are defined: a low measurement range, a normal measurement range, a first high measurement range, and a second high measurement range. The normal measurement range is set as the initial measurement range when the power is turned on. The reference range is defined within the measurement range. That is, for example, when the current measurement range is the normal measurement range, the reference range is defined within the normal measurement range. That is, when the current measurement range is the normal measurement range, the upper limit value of the reference range is lower than the upper limit value of the normal measurement range. The lower limit value of the reference range of the normal measurement range is higher than the lower limit value of the normal measurement range. Similarly, the reference range of the low measurement range is defined within the low measurement range, the reference range of the first high measurement range is defined within the first high measurement range, and the reference range of the second high measurement range is defined within the second high measurement range.

[0041] If the reference measurement value B is higher than the upper limit of the reference range in the currently set measurement range (YES in S111), the measurement range is offset to one value higher than the currently set measurement range (S112), and this process ends. For example, when the normal measurement range is set and a value outside the high reference range, which is higher than the upper limit of the reference range, is measured as the reference measurement value B, a first high measurement range, which is a measurement range higher than the currently set normal measurement range, is set.

[0042] If the reference measurement value B is not higher than the upper limit of the reference range for the currently set measurement range (NO in S111), it is determined whether the reference measurement value B is lower than the lower limit of the reference range for the currently set measurement range (S113). If the reference measurement value B is lower than the lower limit of the reference range (YES in S113), the measurement range is offset to one value lower than the currently set measurement range (S114), and this processing ends. For example, when the normal measurement range is set and a value outside the low reference range, which is lower than the lower limit of the reference range, is measured as the reference measurement value B, a low measurement range, which is lower than the currently set normal measurement range, is set.

[0043] If the reference measurement value B is not higher than the upper limit of the reference range (NO in S111) and is not lower than the lower limit of the reference range (NO in S113), this process ends.

[0044] That is, in the measurement range offset process (S102), if the reference measurement value B is a value outside the high reference range that is higher than the upper limit value of the reference range, the measurement range offset unit 160 offsets the measurement range toward the higher value side. On the other hand, in the measurement range offset process (S102), if the reference measurement value B is a value outside the low reference range that is lower than the lower limit value of the reference range, the measurement range offset unit 160 offsets the measurement range toward the lower value side. Also, if the reference measurement value B is a value within the reference range, the measurement range is not changed from the current one, and this process ends.

[0045] In the difference value calculation process (S103), a difference value C is calculated, which indicates the difference between the contacted part measurement value A acquired in the measurement value acquisition process (S101) and the reference measurement value B. In the difference value calculation process (S103) of this embodiment, the difference value C is calculated by subtracting the contacted part measurement value A from the reference measurement value B.

[0046] In the contact determination process (S104), it is determined whether the driver's hand is in contact with the contacted portion 110, or in a non-contact state, based on the difference value C. Specifically, in the contact determination process (S104), as shown in FIG. 5, it is determined whether the difference value C is within a contact range, which is a range that indicates a contact state (S121). If the difference value C is within the contact range (YES in S121), it is determined that there is a contact state (S122), and this process ends. On the other hand, if the difference value C is not within the contact range (NO in S121), it is determined that there is a non-contact state (S123), and this process ends.

[0047] Next, measurement values ​​in this embodiment will be described using examples in FIGS. 6 to 8. First, FIG. 6 is a graph showing the relationship between the value of the quadrature component acquired from the electrostatic sensor 111 and the reference capacitor 120 and the temperature. In FIG. 6, the vertical axis represents the value of the quadrature component, and the horizontal axis represents the temperature. The values ​​of the quadrature component of the electrostatic sensor 111 and the reference capacitor 120 shown in FIG. 6 were both acquired using corrected measurement values. Furthermore, FIG. 6 was acquired while the environmental temperature of the contact detection device 100 was increased from a low temperature to a high temperature without contacting a conductor with the contacted part 110.

[0048] As shown in FIG. 6, it can be seen that the values ​​of the quadrature phase components acquired from the electrostatic sensor 111 and the reference capacitor 120 tend to decrease as the temperature increases. It can also be seen that the value of the quadrature phase component acquired from the reference capacitor 120 remains approximately the same as the value of the quadrature phase component acquired from the electrostatic sensor 111 in response to temperature changes. In this way, the reference capacitor 120 has temperature characteristics similar to those of the electrostatic sensor 111. This is because the reference capacitor 120 has the same capacitance as the electrostatic sensor 111.

[0049] That is, in the contact detection device 100 of this embodiment, when the contacted part measurement value A of the electrostatic sensor 111 fluctuates in response to a change in the environment, the reference measurement value B of the reference capacitor 120 also fluctuates in the same manner as the contacted part measurement value A of the electrostatic sensor 111. This shows that, in the contact detection device 100, even if there is a change in the environment, it does not affect the difference value calculated from the contacted part measurement value A and the reference measurement value B. Therefore, the contact detection device 100 can accurately determine contact even in a situation where the environment is changing. That is, the contact detection device 100 can accurately detect contact of a conductor with the contacted part 110.

[0050] Also, in Fig. 6, the normal measurement range D3 is indicated by a two-dot chain line. As mentioned above, the normal measurement range D3 is the measurement range in a state where no offset is set for the measurement range (a state where the offset amount is set to zero). Fig. 6 also shows the upper limit value DH3 and lower limit value DL3 of the normal measurement range D3.

[0051] 6, the values ​​of the quadrature components of the electrostatic sensor 111 and the reference capacitor 120 are higher than the upper limit value DH3 in a temperature range lower than temperature T1. Therefore, if only the normal measurement range D3 is used without offsetting the measurement range, the contact detection device 100 will not be able to accurately acquire measurement values ​​in a low-temperature environment lower than temperature T1. In other words, the contact detection device 100 may not be able to accurately determine contact in a low-temperature environment.

[0052] On the other hand, the values ​​of the quadrature components of the electrostatic sensor 111 and the reference capacitor 120 remain within the normal measurement range in a temperature range higher than temperature T1. That is, although the values ​​of the quadrature components of the electrostatic sensor 111 and the reference capacitor 120 decrease to near the lower limit DL3 in a high-temperature environment, they are still higher than the lower limit DL3.

[0053] However, when a conductor comes into contact with the contacted part 110, the value of the quadrature phase component of the electrostatic sensor 111 is lower than when the conductor is not in contact with the contacted part 110. That is, in a high-temperature environment, when a conductor comes into contact with the contacted part 110, the value of the quadrature phase component of the electrostatic sensor 111 may become lower than the lower limit value DL3. For this reason, if only the normal measurement range D3 is used without offsetting the measurement range, the contact detection device 100 may not be able to accurately acquire the value of the quadrature phase component of the electrostatic sensor 111 when a conductor comes into contact with the contacted part 110 in a high-temperature environment. That is, the contact detection device 100 may not be able to accurately determine contact even in a high-temperature environment.

[0054] Fig. 7 is a graph showing the relationship between the temperature and the corrected measurement value acquired from the electrostatic sensor 111 and the reference capacitor 120 while performing measurement range offset processing. As with Fig. 6, the value of the quadrature phase component is used as the corrected measurement value acquired from the electrostatic sensor 111 and the reference capacitor 120 in Fig. 7. As with Fig. 6, Fig. 7 was also acquired while the environmental temperature of the contact detection device 100 was increased from a low temperature to a high temperature without bringing a conductor into contact with the contacted part 110.

[0055] Figure 7 shows, from low temperature to high temperature, the second high measurement range D1, the first high measurement range D2, the normal measurement range D3, and the low measurement range D4. Figure 7 also shows the upper limit value DH1 and the lower limit value DL1 of the second high measurement range D1, the upper limit value DH2 and the lower limit value DL2 of the first high measurement range D2, the upper limit value DH3 and the lower limit value DL3 of the normal measurement range D3, and the upper limit value DH4 and the lower limit value DL4 of the low measurement range D4. The second high measurement range D1, the first high measurement range D2, the normal measurement range D3, and the low measurement range D4 all have the same numerical range for the difference between their upper and lower limits. Note that any of the second high measurement range D1, the first high measurement range D2, the normal measurement range D3, and the low measurement range D4 may be set so that the difference between its upper and lower limits is a different numerical range from any of the other measurement ranges.

[0056] The offset amount of each measurement range other than the normal measurement range D3 relative to the normal measurement range D3 is equal to, for example, the value obtained by subtracting the upper limit value DH3 of the normal measurement range D3 from the upper limit value of each measurement range other than the normal measurement range D3. 7 shows the second high offset amount F1 of the second high measurement range D1 relative to the normal measurement range D3, the first high offset amount F2 of the first high measurement range D2 relative to the normal measurement range D3, and the low offset amount F4 of the low measurement range D4 relative to the normal measurement range D3.

[0057] The second high offset amount F1 and the first high offset amount F2 are offset amounts that offset the measurement range toward higher values ​​relative to the normal measurement range D3. The second high offset amount F1 is an offset amount greater than the first high offset amount F2. The low offset amount F4 is an offset amount that offsets the measurement range toward lower values ​​relative to the normal measurement range D3.

[0058] 7 also shows the reference ranges for each measurement range. Specifically, it shows a second high reference range E1 for the second high measurement range D1, a first high reference range E2 for the first high measurement range D2, a normal reference range E3 for the normal measurement range D3, and a low reference range E4 for the low measurement range D4. It also shows the upper limit value EH1 and lower limit value EL1 of the second high reference range E1, the upper limit value EH2 and lower limit value EL2 of the first high reference range E2, the upper limit value EH3 and lower limit value EL3 of the normal reference range E3, and the upper limit value EH4 and lower limit value EL4 of the low measurement range D4. In this embodiment, each reference range is located near the center between the upper limit value and lower limit value of the corresponding measurement range.

[0059] As shown in Fig. 7, the measurement range switches from the low temperature T11 to the high temperature T15, from the second high measurement range D1 to the first high measurement range D2, the normal measurement range D3, and the low measurement range D4. Specifically, the second high measurement range D1 is set in the temperature range below temperature T12. The first high measurement range D2 is set in the temperature range equal to or greater than temperature T12 and less than temperature T13. The normal measurement range D3 is set in the temperature range equal to or greater than temperature T13 and less than temperature T14. The low measurement range D4 is set in the temperature range equal to or greater than temperature T14.

[0060] 7, measurement of the contacted portion corrected measurement value and the reference corrected measurement value is started at the lowest temperature T11 with the measurement range set to the second high measurement range D1. After that, when the temperature rises to temperature T12, a reference corrected measurement value lower than the lower limit value EL1 of the second high reference range E1 is measured, so the offset is changed and the measurement range setting is changed to the first high measurement range D2.

[0061] Furthermore, when the temperature rises further to temperature T13, a reference correction measurement value lower than the lower limit value EL2 of the first high reference range E2 is measured, so the offset is changed and the measurement range setting is changed to the normal measurement range D3. Furthermore, when the temperature rises further to temperature T14, a reference correction measurement value lower than the lower limit value EL3 of the normal reference range E3 is measured, so the offset is changed and the measurement range setting is changed to the low measurement range D4.

[0062] As shown in Figure 7, both the contacted part corrected measurement value and the reference corrected measurement value fall within the measurement range in any temperature range. Furthermore, the contacted part corrected measurement value never falls close to the lower limit of any measurement range that is set. Note that Figure 7 shows the results when corrected measurement values ​​are obtained while increasing the temperature from low to high. However, similarly, when corrected measurement values ​​are obtained while decreasing the temperature from high to low, both the contacted part corrected measurement value and the reference corrected measurement value can fall within the measurement range in any temperature range.

[0063] Fig. 8 is a graph showing the relationship between the raw measurement values ​​acquired from the electrostatic sensor 111 and the reference capacitor 120 while performing measurement range offset processing and the temperature. Fig. 7 above shows a case where, when the measurement range is offset, a corrected measurement value, which is a value that cancels out the offset, is used. In contrast, Fig. 8 shows a case where the raw measurement values ​​acquired with the measurement range offset are used as is.

[0064] 8, as in Fig. 7, the values ​​of the quadrature phase components are used as the raw measurement values ​​acquired from the electrostatic sensor 111 and the reference capacitor 120. Also in Fig. 8, as in Fig. 7, the values ​​were acquired while the environmental temperature of the contact detection device 100 was increased from a low temperature to a high temperature without bringing a conductor into contact with the contacted part 110.

[0065] 8 also shows, in order from the low temperature side to the high temperature side, the second high measurement range D1, the first high measurement range D2, the normal measurement range D3, and the low measurement range D4. Also, FIG. 8 shows the reference range for each measurement range. Furthermore, FIG. 8 also shows the upper and lower limit values ​​for each measurement range and each reference range. Because FIG. 8 shows raw measurement values, at least the upper and lower limit values ​​for each measurement range are the same.

[0066] As shown in Figure 8, even when raw measurement values ​​are used, the measurement range switches from the low temperature T11 to the high temperature T15, from the second high measurement range D1 to the first high measurement range D2, the normal measurement range D3, and the low measurement range D4.

[0067] 8, measurement of the contacted part raw measurement value and the reference raw measurement value is started at the lowest temperature T11 with the measurement range set to the second high measurement range D1. After that, when the temperature rises to temperature T12, a reference raw measurement value lower than the lower limit EL1 of the second high reference range E1 is measured, so the offset is changed and the measurement range setting is changed to the first high measurement range D2.

[0068] Furthermore, when the temperature rises further to temperature T13, a reference raw measurement value lower than the lower limit value EL2 of the first high reference range E2 is measured, so the offset is changed and the measurement range setting is changed to the normal measurement range D3. When the temperature rises further to temperature T14, a reference raw measurement value lower than the lower limit value EL3 of the normal reference range E3 is measured, so the offset is changed and the measurement range setting is changed to the low measurement range D4.

[0069] 8, the raw measurement values ​​acquired by offsetting the measurement range higher than the normal measurement range D3 are lower than the raw measurement values ​​acquired in the normal measurement range D3 by the amount of the offset. Also, the raw measurement values ​​acquired by offsetting the measurement range lower than the normal measurement range D3 are higher than the raw measurement values ​​acquired in the normal measurement range D3 by the amount of the offset.

[0070] As shown in Figure 8, both the contacted part raw measurement value and the reference raw measurement value fall within the measurement range in any temperature range. Furthermore, the contacted part raw measurement value never falls close to the lower limit of any measurement range that is set. Note that Figure 8 shows the results when raw measurement values ​​are acquired while increasing the temperature from the low temperature side to the high temperature side. However, similarly, when raw measurement values ​​are acquired while decreasing the temperature from the high temperature side to the low temperature side, both the contacted part raw measurement value and the reference raw measurement value can fall within the measurement range in any temperature range.

[0071] 7 and 8, the contact detection unit 140 of this embodiment can acquire a measurement value that falls appropriately within the measurement range, regardless of the temperature of the contact detection device 100, regardless of whether the contact detection unit 140 uses a corrected measurement value or a raw measurement value. This is because the contact detection unit 140 of this embodiment can perform measurement range offset processing to change the offset of the measurement range. In other words, the contact detection unit 140 does not acquire a measurement value using only the normal measurement range D3, but can offset the measurement range to a higher or lower value than the current value based on the reference measurement value B through measurement range offset processing. The contact detection device 100 can then more accurately detect the contact of a conductor with the contacted part 110 through measurement range offset processing that offsets the measurement range to a higher or lower value than the current value.

[0072] Furthermore, in the contact detection device 100 of this embodiment, the offset of the measurement range is changed based on a reference range set within the measurement range. Specifically, when the reference measurement value B is outside the high reference range, that is, a value higher than the upper limit of the reference range, the contact detection unit 140 executes a measurement range offset process to offset the measurement range to a higher value than the current value. This prevents the value of the measurement target from becoming higher than the upper limit of the measurement range due to environmental changes. Therefore, the contact detection device 100 can more accurately detect the contact of a conductor with the contacted part 110.

[0073] Furthermore, when the reference measurement value B is outside the low reference range and is lower than the lower limit of the reference range, the contact detection unit 140 executes a measurement range offset process to offset the measurement range to a lower value than the current value. This prevents the measurement target value from falling below the lower limit of the measurement range due to environmental changes. This allows the contact detection device 100 to more accurately detect the contact of a conductor with the contacted part 110.

[0074] As described above, each reference range is located near the center between the upper and lower limits of the corresponding measurement range. In this embodiment, each reference range is located slightly higher than the center between the upper and lower limits of the corresponding measurement range. More specifically, the difference between the lower limit of the reference range and the lower limit of the measurement range is larger than the difference between the upper limit of the reference range and the upper limit of the measurement range. This allows the contacted part measurement value to be properly measured as a value within the measurement range even when the contacted part measurement value decreases due to contact of a conductor with the contacted part 110. Each reference range may be set to be located slightly lower than the center between the upper and lower limits of the corresponding measurement range. This allows the contacted part measurement value to be properly measured as a value within the measurement range even when the contacted part measurement value increases due to contact of a conductor with the contacted part 110.

[0075] Second Embodiment Next, a second embodiment different from the above embodiment will be described. In the second embodiment, the content of the measurement range offset process differs from the above embodiment. That is, in the measurement range offset process of this embodiment, a predetermined table is referenced using a reference measurement value to determine the offset amount of the measurement range. Below, the differences from the above embodiment will be described.

[0076] The measurement range offset unit 160 of the contact detection device 100 of this embodiment performs a measurement range offset process that is different from the above embodiment. Specifically, in the measurement range offset process, the measurement range offset unit 160 of this embodiment determines an offset amount by referring to a temperature offset table using a reference corrected measurement value, and offsets the measurement range by the determined offset amount.

[0077] 9 is an example of a temperature offset table according to this embodiment. As shown in FIG. 9, the offset amount for the measurement range is determined based on the range of the reference measurement value B. As described above, the reference measurement value B can take on different values ​​depending on the environmental temperature. As shown in FIG. 9, the temperature offset table is a table that determines different offset amounts for each range of the reference measurement value B previously acquired for each of a plurality of temperature ranges.

[0078] 9, for example, the range of reference measurement value B corresponding to the temperature range below temperature T12 is defined as a range where the reference measurement value B is equal to or greater than EL1. Corresponding ranges of reference measurement value B are also defined for other temperature ranges. An offset amount for the measurement range is also defined for each range of reference measurement value B. As a result, a second high measurement range D1, a first high measurement range D2, a normal measurement range D3, and a low measurement range D4 are defined for each range of reference measurement value B.

[0079] The second high offset amount F1 corresponding to the second high measurement range D1 and the first high offset amount F2 corresponding to the first high measurement range D2 are offset amounts that offset the measurement range toward higher values ​​relative to the normal measurement range D3. The second high offset amount F1 is an offset amount greater than the first high offset amount F2. The low offset amount F4 corresponding to the low measurement range D4 is an offset amount that offsets the measurement range toward lower values ​​relative to the normal measurement range D3. In the example of FIG. 9, the offset amount corresponding to the normal measurement range D3 is set to zero. Note that when the reference measurement value B corresponding to the normal measurement range D3 is measured, the measurement range may not be offset.

[0080] The temperature offset table shown in Fig. 9 can be obtained based on the graph of Fig. 7 described in the above embodiment. More specifically, each range of the reference measurement value B in Fig. 9 can be created based on each temperature range for each measurement range shown in Fig. 7, the lower limit value of the reference measurement range for each measurement range, and the offset amount for each measurement range. In the contact detection device 100, the created temperature offset table can be stored in the memory unit 190.

[0081] In the contact detection process of this embodiment, similarly to the above embodiment, the measurement value acquisition process, measurement range offset process, difference value calculation process, and contact determination process are performed. In the measurement value acquisition process of this embodiment, corrected measurement values ​​are acquired as both the contacted portion measurement value A and the reference measurement value B.

[0082] Next, in the measurement range offset process, the temperature offset table is referenced using the reference measurement value B acquired in the measurement value acquisition process. Then, an offset amount is determined depending on the range of the reference measurement value B acquired in the measurement value acquisition process. Furthermore, the measurement range is offset from the normal measurement range by the determined offset amount. The difference value calculation process and contact determination process can be performed in the same manner as in the above embodiment. As a result, the contact detection device 100 of this embodiment can also accurately detect contact of a conductor with the contacted part 110, as described in the above embodiment.

[0083] As described above in detail, the contact detection device 100 according to the embodiment includes the electrostatic sensor 111, the reference capacitor 120, the AC power supply 130, and the contact detection unit 140. The electrostatic sensor 111 is provided on the contacted portion 110 of the grip unit 3. The reference capacitor 120 is provided on the contact detection unit 140 inside the base 2. In other words, the reference capacitor 120 is provided at a location other than the contacted portion 110. The contact detection unit 140 performs a measurement value acquisition process to acquire a contact portion measurement value and a reference measurement value based on either a quadrature phase component or an in-phase phase component obtained by quadrature demodulating the output signals from the electrostatic sensor 111 and the reference capacitor 120 to which an AC voltage is applied. Specifically, in the measurement value acquisition process, the contact detection unit 140 acquires the contacted portion measurement value based on either a quadrature phase component or an in-phase phase component obtained by quadrature demodulating the output signal from the electrostatic sensor 111 to which an AC voltage is applied. In the measurement value acquisition process, the contact detection unit 140 acquires a reference measurement value based on either the quadrature-phase component or the in-phase component obtained by quadrature demodulating the output signal from the reference capacitor 120 to which an AC voltage is applied. The contacted part measurement value and the reference measurement value both have the same quadrature-phase component or the in-phase component. The contact detection unit 140 then detects contact of a conductor with the contacted part 110 based on whether a differential value indicating the difference between the reference measurement value and the contacted part measurement value is within a predetermined contact range. In the contact detection device 100, if the measurement value of the electrostatic sensor 111 fluctuates with changes in ambient temperature, the measurement value of the reference capacitor 120 also fluctuates with changes in ambient temperature. In other words, because both the measurement value of the electrostatic sensor 111 and the measurement value of the reference capacitor 120 fluctuate with changes in ambient temperature, these differential values ​​are less susceptible to the effects of ambient temperature. This allows the contact detection device 100 to accurately detect contact of a conductor with the contacted part 110.

[0084] The above-described embodiments are merely examples and do not limit the present disclosure in any way. Therefore, the present disclosure can be naturally improved and modified in various ways without departing from the spirit and scope of the present disclosure.

[0085] In the above embodiment, an example in which the value of the quadrature phase component is used as the measurement value has been specifically described. However, the value of the in-phase component can also be used as the measurement value. When the value of the in-phase component is used as the measurement value, the measurement value may fluctuate due to changes in the environment or the circuit configuration, just as when the quadrature phase component is used. Even when the measurement value related to the in-phase component that fluctuates due to the environment or the circuit configuration is used, the technology disclosed herein can accurately detect the contact of the conductor with the contacted part.

[0086] In the above embodiment, the reference capacitor 120 is described as being provided in the contact detection unit 140 located inside the base 2. However, the reference capacitor 120 only needs to be provided in a location where its output signal is not affected whether or not a conductor is in contact with the contacted unit 110. Furthermore, as in the above embodiment, it is preferable that the reference capacitor 120 is provided in a location where the output signal of the reference capacitor 120 located in the internal space is not affected even if an external conductor comes into contact with the reference capacitor 120.

[0087] In the above embodiment, for example, the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 are disposed close to each other in the same space. However, it is preferable that the contacted part measurement value acquisition unit 151 and the reference measurement value acquisition unit 152 are disposed so as to have approximately the same temperature, and they do not necessarily have to be disposed close to each other in the same space.

[0088] Furthermore, for example, in the above embodiment, an example has been described in which an AC voltage is applied to the electrostatic sensor 111 and the reference capacitor 120 by the AC power supply 130. However, for example, an AC power supply that applies an AC voltage to the electrostatic sensor 111 and the reference capacitor 120 may be provided for each of the electrostatic sensor 111 and the reference capacitor 120.

[0089] Furthermore, for example, in the above embodiment, an example has been described in which the reference capacitor 120 has the same capacitance as the electrostatic sensor 111. However, the reference capacitor 120 does not necessarily have to have the same capacitance as the electrostatic sensor 111. For example, the reference capacitor 120 may have a capacitance that has temperature characteristics similar to those of the reference capacitor 120. Furthermore, for example, the reference capacitor 120 may have a capacitance different from that of the electrostatic sensor 111, and the measurement value of the reference capacitor 120 may be calculated as a value that exhibits temperature characteristics similar to those of the raw measurement value of the contacted part by multiplying the measurement value of the reference capacitor 120 by a correction coefficient corresponding to the reference raw measurement value.

[0090] 6, the contact detection device 100 according to the first embodiment can obtain accurate measurement values ​​using only the normal measurement range D3 without offsetting the measurement range in an intermediate temperature environment between a low-temperature environment and a high-temperature environment. Therefore, depending on the expected usage environment, the contact detection device 100 according to the first embodiment can accurately detect contact of a conductor with the contacted part 110 even when using only the normal measurement range D3 without offsetting the measurement range. Therefore, depending on the expected usage environment, it is not necessarily necessary to perform measurement range offset processing.

[0091] In addition, for example, in the above embodiment, the offset amount for the normal measurement range is described as zero, but for example, offsetting may be performed for all of a plurality of measurement ranges including the normal measurement range.

[0092] In addition, for example, in the above embodiment, the measurement range offset process is described as being capable of offsetting the measurement range to both the high value side and the low value side. However, the measurement range offset process may be configured to offset the measurement range to only one of the high value side and the low value side.

[0093] For example, in the above embodiment, a measurement range offset process was described in which two offsets are possible on the higher value side of the normal measurement range and one offset is possible on the lower value side of the normal measurement range. However, the measurement range offset process may be a process that can offset only one offset toward the higher value side of the normal measurement range, or a process that can offset three or more offsets toward the higher value side of the normal measurement range. Furthermore, the measurement range offset process may be a process that can offset two or more offsets toward the lower value side of the normal measurement range.

[0094] In the above embodiment, a contact detection device that detects contact with a steering wheel has been described. However, the contact detection device is not limited to a steering wheel and can naturally be used for other purposes. For example, the contact detection device is not limited to detecting contact of a human body with a contacted part, and may be any device that detects contact of a conductor.

[0095] The above-mentioned disclosed technology also includes the following means 1 to 4. [Means 1] The contact detection device according to claim 1, The contact detection unit The contact detection device is capable of performing a measurement range offset process for offsetting a measurement range, which is a range in which the measurement value can be measured, to a higher or lower value side than the current value.

[0096] [Means 2] The contact detection device according to Means 1, The contact detection unit When the reference measurement value acquired in the measurement value acquisition process is a value outside one of the reference ranges, which is either a value higher than the upper limit value or lower than the lower limit value of the reference range set within the measurement range, the contact detection device executes the measurement range offset process, which offsets the measurement range to one side from the current value.

[0097] [Means 3] The contact detection device according to means 2, The contact detection unit When the reference measurement value acquired in the measurement value acquisition process is a value outside the other reference range, which is the other value opposite to one of the reference ranges, the contact detection device executes the measurement range offset process, which offsets the measurement range to the other side from the current side.

[0098] [Means 4] The contact detection device according to Means 1, The contact detection unit a storage unit that stores a temperature offset table that defines a different offset amount for each range of the reference measurement value that is acquired in advance for each of a plurality of temperature ranges; As the measurement range offset process, a contact detection device determines the offset amount by referring to the temperature offset table using the reference measurement value acquired in the measurement value acquisition process, and offsets the measurement range by the determined offset amount. [Explanation of symbols]

[0099] 100: Contact detection device 110: Contacted part 111: Electrostatic sensor 120: Reference capacitor 130: AC power supply 140: Contact detection unit 190: Storage section

Claims

1. an electrostatic sensor provided on the contacted portion; a reference capacitor provided in a reference portion other than the contacted portion; an AC power source that applies an AC voltage to the electrostatic sensor and the reference capacitor; a contact detection unit that detects contact of a conductor with the contacted portion, The contact detection unit performing a measurement value acquisition process for acquiring a measurement value based on either a quadrature phase component or an in-phase component obtained by quadrature demodulating output signals from the electrostatic sensor and the reference capacitor to which an AC voltage has been applied; A contact detection device that detects contact of the conductor with the contacted part when a differential value indicating the difference between the contacted part measurement value, which is the measurement value of the electrostatic sensor acquired in the measurement value acquisition process, and the reference measurement value, which is the measurement value of the reference capacitor, is within a predetermined contact range.

2. The contact detection device according to claim 1 , The contact detection unit The contact detection device is capable of performing a measurement range offset process for offsetting a measurement range, which is a range in which the measurement value can be measured, to a higher or lower value side than the current value.

3. The contact detection device according to claim 2, The contact detection unit When the reference measurement value acquired in the measurement value acquisition process is a value outside one of the reference ranges, which is either a value higher than the upper limit value or lower than the lower limit value of the reference range set within the measurement range, the contact detection device executes the measurement range offset process, which offsets the measurement range to one side from the current value.

4. The contact detection device according to claim 3, The contact detection unit When the reference measurement value acquired in the measurement value acquisition process is a value outside the other reference range, which is the other value opposite to one of the reference ranges, the contact detection device executes the measurement range offset process, which offsets the measurement range to the other side from the current side.

5. The contact detection device according to claim 2, The contact detection unit a storage unit that stores a temperature offset table that defines a different offset amount for each range of the reference measurement value that is acquired in advance for each of a plurality of temperature ranges; As the measurement range offset process, a contact detection device determines the offset amount by referring to the temperature offset table using the reference measurement value acquired in the measurement value acquisition process, and offsets the measurement range by the determined offset amount.

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