Contact / proximity detection device and mobile body

Abstract

The purpose of the present disclosure is to provide: a contact / proximity detection device that is capable of improving contact detection sensitivity when a signal ground of a detection circuit is floating without being grounded; and a mobile body that comprises the contact / proximity detection device. A contact / proximity detection device according to the present disclosure comprises: a detection processing unit that detects contact with and proximity to a mobile body; at least one sensor electrode that is installed on the outer surface of the mobile body and is connected to the detection processing unit; and a ground electrode that is installed on the outer surface of the mobile body and is connected to a signal ground of the detection processing unit.

Description

Contact proximity detection device and mobile body

[0001] This disclosure relates to a contact proximity detection device for detecting contact with and proximity to a moving object, and to a moving object equipped with the contact proximity detection device.

[0002] Conventionally, technologies for detecting contact with objects installed indoors or outdoors have been disclosed (see, for example, Patent Document 1).

[0003] Japanese Patent Application Publication No. 11-134986

[0004] In Patent Document 1, the detection circuit that performs the detection process must be grounded, and if the signal ground of the detection circuit is not grounded and is floating, contact with the object to be detected cannot be detected. When the signal ground of the detection circuit is not grounded and is floating, if the capacitance to ground of the signal ground of the detection circuit is small compared to the capacitance to ground of the sensor electrode installed on the object to be detected, there are problems such as a decrease in the sensitivity of contact detection or the occurrence of a distribution in the detection sensitivity.

[0005] This disclosure is made to solve such problems and aims to provide a contact detection device that can improve the sensitivity of contact detection when the signal ground of the detection circuit is not grounded and is floating, and a mobile body equipped with the contact detection device.

[0006] To solve the above problems, the contact proximity detection device according to this disclosure comprises a detection processing unit for detecting contact and proximity to a moving object, at least one sensor electrode installed on the outer surface of the moving object and connected to the detection processing unit, and a ground electrode installed on the outer surface of the moving object and connected to the signal ground of the detection processing unit.

[0007] According to this disclosure, it is possible to improve the contact detection sensitivity when the signal ground of the detection circuit is floating and not grounded.

[0008] The purposes, features, aspects, and advantages of this disclosure will become more apparent from the following detailed description and accompanying drawings.

[0009] Figure 1 is a diagram showing an example of the configuration of a mobile body equipped with a contact detection device according to Embodiment 1. Figure 2 is a diagram showing an equivalent circuit for explaining the operation when contact is made with the sensor electrode. Figure 3 is a diagram showing an example of the configuration of a mobile body equipped with a contact detection device according to Embodiment 2. Figure 4 is a diagram showing an equivalent circuit for explaining the operation when contact is made with the ground electrode. Figure 5 is a diagram showing an example of the configuration of a mobile body equipped with a contact detection device according to Embodiment 3. Figure 6 is a graph for explaining the determination of contact with the mobile body by the detection processing unit of the contact detection device according to Embodiment 4. Figure 7 is a graph for explaining the determination of contact with the mobile body by the detection processing unit of the contact detection device according to Embodiment 4. Figure 8 is a graph for explaining the determination of contact with the mobile body by the detection processing unit of the contact detection device according to Embodiment 4. Figure 9 is a diagram showing an example of the configuration of a mobile body equipped with a contact detection device according to Embodiment 5.

[0010] <Embodiment 1> Figure 1 shows an example of the configuration of a mobile body 1 equipped with a contact proximity detection device according to Embodiment 1. The mobile body 1 is, for example, a cart and is equipped with a contact proximity detection device (capacitive sensor). The contact proximity detection device comprises a detection processing unit 2, a sensor electrode 3, and a ground electrode 4. In this specification, since proximity detection is performed on the same or similar principle as contact detection, unless a distinction is particularly necessary, "contact detection" is treated as including "proximity detection".

[0011] The detection processing unit 2 detects contact with the moving object 1. The signal ground of the detection processing unit 2 is floating and not grounded.

[0012] The sensor electrodes 3 are installed on the outer surface of the mobile body 1 and are electrically connected to the detection processing unit 2. In the example shown in Figure 1, two sensor electrodes 3 are installed, but there may be one sensor electrode 3 or three or more. For example, when a person's hand touches a sensor electrode 3, the detection processing unit 2 detects that a person has come into contact with the mobile body 1.

[0013] The ground electrode 4 is installed on the outer surface of the mobile body 1 and is electrically connected to the signal ground of the detection processing unit 2.

[0014] FIG. 2 is a diagram for explaining the operation when a person touches the sensor electrode 3, and shows an equivalent circuit of the contact proximity detection device. In FIG. 2, the charge measurement unit 5 is a capacitor C Ｉｎｔ measures the amount of charge of . The charge measurement unit 5 is a function included in the detection processing unit 2. C ｓｅｎｓｏｒ－ｇｎｄ indicates the capacitance to ground of the sensor electrode 3, C ＳＧ－ｇｎｄ indicates the capacitance to ground of the ground electrode 4, and C ｈｕｍａｎ－ｇｎｄ indicates the capacitance to ground of a person.

[0015] When a person is not in contact with either the sensor electrode 3 or the ground electrode 4, current flows through the path indicated by the thin line arrow in FIG. 4.

[0016] On the other hand, when a person touches the sensor electrode 3, current flows through the path indicated by the thick line arrow. Specifically, the person's capacitance to ground C ｈｕｍａｎ－ｇｎｄ is connected in parallel, and the capacitance to ground of the sensor electrode 3 C ｓｅｎｓｏｒ－ｇｎｄ via the capacitance to ground of the ground electrode 4 C ＳＧ－ｇｎｄ in addition to the current component passing through, the person's capacitance to ground C ｈｕｍａｎ－ｇｎｄ via the capacitance to ground of the ground electrode 4 C ＳＧ－ｇｎｄ the current component passing through increases. Therefore, the amount of charge flowing to the charge measurement unit 5 decreases. As described above, when a person touches the sensor electrode 3, the amount of charge (detection value) flowing to the charge measurement unit 5 changes, so it can be detected that a person has touched the sensor electrode 3 based on this change.

[0017] The reason why the contact sensitivity of the sensor increases when the ground electrode 4 is in a floating state will be described. As described above, the current path that increases when a person makes contact is the person's capacitance to ground C ｈｕｍａｎ－ｇｎｄ via the capacitance to ground of the ground electrode 4 C ＳＧ－ｇｎｄ is the path passing through. The series capacitance of this path in this case is 1 / (1 / C ｈｕｍａｎ－ｇｎｄ +1 / C ＳＧ－ｇｎｄ ). In the case of the capacitance to ground of only the substrate, C ＳＧ－ｇｎｄ is several pF to several tens of pF, while C ｈｕｍａｎ－ｇｎｄ is 100 to 200 pF, so the small capacitance to ground of the ground electrode 4 C ＳＧ－ｇｎｄThis becomes dominant, and the change in charge due to contact is C ＳＧ－ｇｎｄ This is greatly limited by its small size. In particular, the capacitance C to ground of the sensor electrode 3. ｓｅｎｓｏｒ－ｇｎｄ The capacitance C of the ground electrode 4 to ground ＳＧ－ｇｎｄ It is significantly larger in comparison, and the human capacitance to ground C ｈｕｍａｎ－ｇｎｄ The decrease in sensitivity becomes significant when it is equal to or greater than the capacitance C of the ground electrode 4. ＳＧ－ｇｎｄ By increasing the value, the sensitivity of contact detection can be improved.

[0018] Based on the above, by connecting the signal ground of the detection processing unit 2 to the ground electrode 4, the capacitance to ground of the ground electrode 4 connected to the signal ground of the detection processing unit 2 increases. Therefore, it becomes possible to improve the detection sensitivity of contact with the moving body 1.

[0019] <Embodiment 2> Figure 3 shows an example of the configuration of a mobile body 1 equipped with a contact proximity detection device according to Embodiment 2. The contact proximity detection device according to Embodiment 2 is characterized in that it detects contact not only when a person touches the sensor electrode 3 but also when a person touches the ground electrode 4. The installation of the detection processing unit 2 and the sensor electrode 3 is the same as in Embodiment 1 (Figure 1).

[0020] The ground electrode 4 is located on the outer surface of the mobile body 1, specifically in a portion of the area where human contact is to be detected. The ground electrode 4 is also electrically connected to the signal ground of the detection processing unit 2.

[0021] The detection processing unit 2 not only detects human contact with the sensor electrode 3, but also with the ground electrode 4. Specifically, the detection processing unit 2 detects contact based on changes in the detected value when a person makes contact with the sensor electrode 3 or the ground electrode 4. The following describes the operation when a person makes contact with the ground electrode 4 and when a person makes contact with the sensor electrode 3.

[0022] Figure 4 is a diagram illustrating the operation when a person comes into contact with the ground electrode 4, and shows the equivalent circuit of the contact proximity detection device.

[0023] If no person is in contact with either the sensor electrode 3 or the ground electrode 4, current flows through the path indicated by the thin arrow in Figure 4. This current branches into a component that flows from the signal generation unit to the charge measurement unit 5 and a component that flows to the sensor electrode 3. The component that flows to the charge measurement unit 5 is used to measure the amount of charge in the charge measurement unit 5. The component that flows to the sensor electrode 3 is used to measure the capacitance C of the sensor electrode 3 to ground. ｓｅｎｓｏｒ－ｇｎｄ The capacitance C to ground of the ground electrode 4 via this ＳＧ－ｇｎｄ It passes through and returns to ground electrode 4.

[0024] On the other hand, when a person touches the ground electrode 4, current flows through the path indicated by the thick arrow. This current flows through the capacitance C to ground of the sensor electrode 3. ｓｅｎｓｏｒ－ｇｎｄ Through this, the human capacitance to ground C ｈｕｍａｎ－ｇｎｄ It passes through and returns to ground electrode 4.

[0025] Thus, when a person comes into contact with the ground electrode 4, the charge flowing through the sensor electrode 3 increases, while the amount of charge flowing through the charge measurement unit 5 decreases compared to when the person is not in contact with the ground electrode 4. In other words, when a person comes into contact with the ground electrode 4, the amount of charge flowing through the charge measurement unit 5 (detected value) changes, and based on this change, it is possible to detect that a person has come into contact with the ground electrode 4.

[0026] The area of ​​the ground electrode 4 is larger than the area of ​​the substrate constituting the detection processing unit 2, or greater than or equal to the area of ​​the sensor electrode 3. When the area of ​​the ground electrode 4 is larger than the area of ​​the substrate constituting the detection processing unit 2, the detection sensitivity of contact to the ground electrode 4 is improved. Also, when the area of ​​the ground electrode 4 is greater than or equal to the area of ​​the sensor electrode 3, sufficient detection sensitivity of contact to the ground electrode 4 can be ensured.

[0027] <Embodiment 3> Figure 5 shows an example of the configuration of a mobile body 1 equipped with a contact proximity detection device according to Embodiment 3. Embodiment 3 is characterized in that the outer surface of the mobile body 1 is made of metal, and the signal ground of the detection processing unit 2 is electrically connected to the outer surface of the mobile body 1. That is, the outer surface of the mobile body 1 shown in Figure 3 includes the ground electrode 4 shown in Figure 2 (the outer surface of the mobile body 1 plays the role of the ground electrode 4). In the example of Figure 5, two sensor electrodes 31 and 32 are installed, but it is also possible to have only one of the sensor electrodes 31 and 31, or three or more sensor electrodes including sensor electrodes other than sensor electrodes 31 and 31.

[0028] The detection processing unit 2 not only detects human contact with the sensor electrodes 31 and 32, but also detects human contact with the outer surface of the mobile body 1 (excluding the sensor electrode 3). Specifically, the detection processing unit 2 detects contact with the mobile body 1 based on the change in the detected value when the sensor electrodes 31 and 32 or the outer surface of the mobile body 1 are in contact. The operation when the outer surface of the mobile body 1 is in the same way as when the ground electrode 4 is in contact (Figure 3) as described in Embodiment 2, but with "ground electrode 4" replaced by "outer surface of the mobile body 1". The operation when the sensor electrodes 31 and 32 are in contact is the same as in Embodiment 2 (Figure 4).

[0029] Based on the above, contact with the moving body 1 can be detected based on the change in the detected value (amount of charge) when it comes into contact with the outer surface of the moving body 1.

[0030] <Embodiment 4> The configuration of the contact proximity detection device and the mobile body 1 according to Embodiment 4 is the same as the configuration of the contact proximity detection device and the mobile body 1 according to Embodiment 3 (see Figure 5). The contact proximity detection device according to Embodiment 4 is characterized by determining the location of contact by a person among the sensor electrodes 31, 32 and the outer surface of the mobile body 1 (excluding the sensor electrode 3).

[0031] FIGS. 6 to 8 are graphs for explaining the determination of contact with a moving body 1 by the detection processing unit 2 of the contact proximity detection device according to the fourth embodiment. In FIGS. 6 to 8, the horizontal axis represents time, and the vertical axis represents the difference between the currently measured capacitance and the base capacitance (the base line, that is, the charge amount (detection value) flowing in the charge measurement unit 5 when no person is in contact, that is, the capacitance difference, which is a change in the detection value).

[0032] FIG. 6 is a graph showing a change in capacitance difference when a person contacts the moving body 1. At the time point indicated by (A), the capacitance differences of both the sensor electrodes 31 and 32 exceed the threshold value at the same time, so the detection processing unit 2 determines that a person has contacted the outer surface of the moving body 1. After the time point indicated by (B), the capacitance differences of both the sensor electrodes 31 and 32 fall below the threshold value at the same time, so the detection processing unit 2 determines that the person has left the outer surface of the moving body 1.

[0033] FIG. 7 is a graph showing a change in capacitance difference when a person contacts the sensor electrode 31. (C) shows a situation where a person approaches the sensor electrode 31, and the detection processing unit 2 determines that the person has contacted the sensor electrode 31 when the capacitance difference of the sensor electrode 31 exceeds the threshold value. (D) shows a situation where the person leaves the sensor electrode 31, and the detection processing unit 2 determines that the person has left the sensor electrode 31 when the capacitance difference of the sensor electrode 31 falls below the threshold value.

[0034] FIG. 8 is a graph showing a change in capacitance difference when a person contacts the sensor electrode 32. (E) shows a situation where a person approaches the sensor electrode 32, and the detection processing unit 2 determines that the person has contacted the sensor electrode 32 when the capacitance difference of the sensor electrode 32 exceeds the threshold value. (F) shows a situation where the person leaves the sensor electrode 32, and the detection processing unit 2 determines that the person has left the sensor electrode 32 when the capacitance difference of the sensor electrode 32 falls below the threshold value.

[0035] From the above, by using two types of capacitance differences (changes in detection values), it is possible to determine the location contacted by a person among the sensor electrodes 31, 32 and the outer surface of the moving body 1 (excluding the sensor electrode 3).

[0036] <Embodiment 5> Figure 9 shows an example of the configuration of a mobile body 1 equipped with a contact proximity detection device according to Embodiment 5. The configuration of the contact proximity detection device and mobile body 1 according to Embodiment 5 is the same as the configuration of the contact proximity detection device and mobile body 1 according to Embodiment 2 (Figure 2). Embodiment 5 is characterized in that the mobile body 1 stops the operation of the transport robot 6.

[0037] Figure 9 shows a situation where the mobile body 1 is being transported in the direction of the arrow by the transport robot 6. In this situation, if a person comes into contact with the ground electrode 4 (or sensor electrode 3), the detection processing unit 2, which detects the contact, wirelessly transmits a stop signal to the transport robot 6. When the transport robot 6 receives the stop signal from the detection processing unit 2, it stops operating.

[0038] Based on the above, the operation of the transport robot 6 can be stopped by a simple operation: a person touching the sensor electrode 3 or the ground electrode 4.

[0039] In the above description, the case in which the configuration of the contact proximity detection device and mobile body 1 according to Embodiment 5 is the same as the configuration of the contact proximity detection device and mobile body 1 according to Embodiment 2 (Figure 2) has been described, but it is not limited to this. The configuration of the contact proximity detection device and mobile body 1 according to Embodiment 5 may be the same as the configuration of the contact proximity detection device and mobile body 1 according to Embodiment 1, or it may be the same as the configuration of the contact proximity detection device and mobile body 1 according to Embodiment 3.

[0040] Within the scope of this disclosure, it is possible to freely combine the embodiments, or to modify or omit the embodiments as appropriate.

[0041] Although this disclosure has been described in detail, the above description is illustrative and not limiting in all aspects. It is understood that countless variations not illustrated are possible.

[0042] 1 Mobile unit, 2 Detection processing unit, 3 Sensor electrode, 4 Ground electrode, 5 Charge measurement unit, 6 Transport robot, 31 Sensor electrode, 32 Sensor electrode.

Claims

1. A contact proximity detection device comprising: a detection processing unit for detecting contact with and proximity to a moving object; at least one sensor electrode installed on the outer surface of the moving object and connected to the detection processing unit; and a ground electrode installed on the outer surface of the moving object and connected to the signal ground of the detection processing unit.

2. The contact proximity detection device according to claim 1, wherein the detection processing unit detects contact and proximity to the moving body based on changes in the detected value when in contact with and near the ground electrode.

3. The contact proximity detection device according to claim 2, wherein the area of ​​the ground electrode is larger than the area of ​​the substrate constituting the detection processing unit, or is greater than or equal to the area of ​​the sensor electrode.

4. The contact proximity detection device according to claim 1, wherein the ground electrode is included in the moving body having a metallic outer surface, and the detection processing unit detects contact with the moving body based on changes in detected values ​​when the moving body is in contact with or close to the outer surface of the moving body.

5. The contact proximity detection device according to claim 4, wherein a plurality of the sensor electrodes are connected to the detection processing unit, and the detection processing unit determines that there is contact with and proximity to the outer surface of the moving body when the detected values ​​change simultaneously when there is contact with and proximity to each of the sensor electrodes.

6. A mobile body that is transported by a transport robot, comprising a contact proximity detection device according to any one of claims 1 to 5, wherein the detection processing unit transmits a signal to the transport robot when it detects contact with the mobile body, and stops the operation of the transport robot.

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