Detection body and handle

Abstract

To provide a detector capable of suppressing a short circuit between electrodes caused by air bubbles with a simple configuration, and a steering wheel including the same.SOLUTION: The detection body 1 includes a pair of electrodes 2 and 3 arranged to face each other, and an insulator 4 interposed between the electrodes 2 and 3. The insulator 4 is formed by stacking a plurality of insulating layers 6 cut out in a sheet shape from a single foamed resin body. In at least two insulating layers 6, surfaces 8 where cut surfaces from the foamed resin body do not coincide with each other are overlapped with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a detection body having an insulator interposed between a pair of electrodes, and a handle having the same. [Background technology]

[0002] Recently, a steering wheel, which is a steering handle for steering a vehicle, has been known to have a capacitance-type grip sensor attached to the rim, which is the gripping portion, with an insulator interposed between a sensor electrode and a shield electrode. The sensor detects contact or approach of the driver's fingers to detect whether the rim is being gripped. Foamed resin is often used as the insulator for such capacitance-type grip sensors. The foamed resin must be formed into a thin sheet of approximately 0.5 to 2 mm to facilitate workability when covering the surface of the rim with a skin such as leather. For example, when a foamed resin sheet is formed by slicing a foamed resin block to a predetermined thickness, air bubbles within the foamed resin block may form through-holes that penetrate the sliced ​​foamed resin sheet in the thickness direction. Such through-holes may short-circuit the electrodes sandwiching the insulating layer, impairing the detection function. However, it is difficult to eliminate through-holes in foamed resin sheets. Furthermore, eliminating all foamed resin sheets with through-holes would result in low yields and significantly reduced profitability (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-505469 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in an insulator using a foamed resin, it is desired to suppress short circuits between electrodes caused by bubbles with a simple configuration.

[0005] The present invention has been made in consideration of the above points, and aims to provide a detection body that can suppress short circuits between electrodes caused by air bubbles with a simple configuration, and a handle equipped with the same. [Means for solving the problem]

[0006] A detection body according to one aspect of the present invention comprises a pair of electrodes arranged opposite each other and an insulator interposed between the electrodes, the insulator being formed by stacking multiple insulating layers cut into sheets from a single foamed resin body, and at least two of the insulating layers being stacked such that the cut surfaces from the foamed resin body do not coincide with each other. [Effects of the Invention]

[0007] According to the present invention, short circuits between electrodes caused by bubbles can be suppressed with a simple configuration. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view schematically showing a detecting element according to an embodiment of the present invention. [Figure 2] FIG. 10 is a perspective view showing an example of a foamed resin body from which an insulating layer of the same detector is cut out. [Figure 3] FIG. 2A is a cross-sectional view schematically showing a part of a foamed resin body, and FIG. 2B is a cross-sectional view schematically showing an example of an insulator formed using an insulating layer cut out from the foamed resin body of FIG. 2A. [Figure 4] FIG. 4 is a cross-sectional view showing a part of the handle provided with the same detection body. [Figure 5] FIG. 2 is a front view showing an example of the handle. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0010] In Fig. 1, reference numeral 1 denotes a detection body. The detection body 1 is configured in a sheet or mat shape with an insulator 4 interposed between a pair of electrodes 2 and 3, and serves as a detector for a capacitance-type sensor.

[0011] Electrode 2 is an output electrode and is also called a sensor electrode. Electrode 3 is an input electrode and is also called a shield electrode. Electrodes 2 and 3 are formed into a sheet shape using, for example, conductive cloth. Electrodes 2 and 3 are each electrically connected to a detection device. The detection device periodically detects the differential signal between the input (AC voltage) to electrode 3 and the output from electrode 2 as a voltage value, and performs sensing based on the differential signal.

[0012] The insulator 4 interposed between the electrodes 2 and 3 is a dielectric material and is formed by stacking multiple insulating layers 6. The insulating layers 6 are cut into thin sheets from a single (common, identical) foamed resin body 7 shown in FIG. 2. That is, each insulating layer 6 is made of the same material. The foamed resin body 7, also known as a foamed resin block, is preformed as a rectangular or cubic block by foam molding or the like. The foamed resin body 7 is sliced ​​to a predetermined thickness, for example, about 0.25 to 1.0 mm, depending on the required characteristics, to cut out the insulating layers 6. In this embodiment, the cut insulating layers 6 each have a substantially uniform thickness. However, this is not limiting, and the thickness of any one of the insulating layers 6 may be different from the thickness of the remaining insulating layers 6. Note that the thickness of the insulating layers 6 is not limited to being set as a thickness determined based on the required characteristics of the original insulators 4 divided by the number of layers, as long as it does not affect the required characteristics of the insulators 4 shown in FIG. 1.

[0013] At least two of the insulating layers 6 constituting the insulator 4 are overlapped with each other such that their cut-out surfaces PL (shown in FIG. 2) from the foamed resin body 7 do not coincide. In the illustrated example, the insulator 4 is composed of two insulating layers 6a and 6b, and the surface 8a of the insulating layer 6a and the surface 8b of the insulating layer 6b, which are overlapped with each other, are not cut out from the same cut-out surface PL (shown in FIG. 2). For example, in the foamed resin body 7 shown in FIG. 2, it is preferable to overlap insulating layers 6 that are cut out from separate locations in the foamed resin body 7, i.e., insulating layers 6 that are not cut out from the same cut-out surface PL, such as when an insulating layer 6 cut out from an end portion and an insulating layer 6 cut out from the center portion are used in combination. However, when adjacent insulating layers 6a and 6b cut out from the foamed resin body 7 along the same cut-out surface PL as shown in FIG. 3(a), the insulator 4 may be constructed by flipping at least one of the insulating layers 6a and 6b over the other, as shown in FIG. 3(b).

[0014] Although two insulating layers 6 are most preferable, three or more may be used as long as there are no problems in terms of quality and manufacturing. Furthermore, the insulating layer 6 may be made of any material as long as it has excellent insulating properties and a certain degree of flexibility.

[0015] 4 and 5, in this embodiment, the detection body 1 is applied to a steering wheel (steering wheel) 10 for steering a vehicle such as an automobile. The steering wheel 10 is exemplified as a steering wheel having a central boss 12 surrounded by a rim (grip) 13, which is a circular or arc-shaped handle, and the boss 12 and the rim 13 connected by radial spokes 14. However, the steering wheel 10 is not limited to this, and may be a control stick type, such as a so-called yoke type. The steering wheel 10 is usually mounted on a steering shaft, which is a steering shaft provided in a vehicle in an inclined state. Below, the steering wheel 10 will be described with the arrow U direction as the upper side and the arrow D direction as the lower side when viewed from the passenger side. The position and shape of each part of the steering wheel 10 will be described based on the steering reference state, i.e., the neutral position, shown in FIG. 5.

[0016] The boss portion 12 is attached to the steering shaft and is located at the center of rotation of the handle 10.

[0017] The rim portion 13 is the portion that the occupant (driver) grips to operate the steering wheel 10. In other words, the rim portion 13 is the portion used for steering. In this embodiment, the rim portion 13 is formed to extend in the rotational direction of the steering wheel 10, i.e., the circumferential direction. In the illustrated example, the rim portion 13 is formed in an arc shape or an annular shape.

[0018] There are multiple spokes 14. In the present embodiment, three spokes 14 are provided to connect the left and right side portions and the bottom portion of the boss portion 12 to the rim portion 13, but the number is not limited to this and may be, for example, two or four or more.

[0019] The handlebar 10 has a core (armature) 20, which is the handlebar main body. The core 20 is made of metal, such as a conductive alloy of aluminum or magnesium. The core 20 includes a boss core 22 corresponding to the boss 12, a rim core 23 serving as a grip core corresponding to the rim 13, and spoke cores 24 corresponding to the spokes 14. The spoke cores 24 are formed integrally and continuously from the boss core 22, and the rim core 23 is fixed to the spoke cores 24 by welding or the like, thereby forming an integral unit. In the core 20, the rim core 23 and the connecting portions of the spoke cores 24 and the rim core 23 are covered with a covering 25.

[0020] The boss core metal portion 22 forms the core of the boss portion 12. The boss core metal portion 22 has a substantially cylindrical boss with a serration structure that meshes with the steering shaft. A module 27 such as an airbag device is disposed in the boss core metal portion 22. The boss portion 12 is formed by the boss core metal portion 22 and the module 27. The back side of the boss core metal portion 22 is covered by a cover body, which is also called a back cover, a lower cover, or a body cover.

[0021] The rim core metal portion 23 forms the core of the rim portion 13. In this embodiment, the rim core metal portion 23 is formed in an annular or arc shape that continues around the entire circumference.

[0022] The spoke cores 24 form the cores of the spokes 14. The spoke cores 24 are arranged radially from the boss core 22. Note that not all spokes 14 necessarily have spoke cores 24, and some spokes 14 may not have spoke cores 24 and may instead be made up of a finisher, cover, or the like.

[0023] The covering portion 25 is a resin layer formed from, for example, a synthetic resin. For example, a soft foamed resin such as urethane foam is used as the synthetic resin forming the covering portion 25. The covering portion 25 has a rim covering portion 30, which is a gripping main body portion that covers the rim core portion 23, and spoke covering portions 31 that cover the ends of the spoke core portions 24 that connect to the rim core portion 23.

[0024] The rim covering portion 30 is formed in a shape that is easy for a rider to grip, such as a circular or elliptical cross section.

[0025] The spoke covering portion 31 is continuous with the rim covering portion 30 and covers the end of the spoke core portion 24 on the rim core portion 23 side up to a position adjacent to the module 27 and the finisher.

[0026] The detection body 1 installed on the rim portion 13 functions as a grip sensor that detects the grip of the rim portion 13 by the occupant based on a change in capacitance.

[0027] In this embodiment, the detection body 1 is curved in the meridian direction, cross-sectional circumferential direction, or minor diameter direction of the rim portion 13 so as to wrap around the rim covering portion 30, and is wound around the covering portion 25 (rim covering portion 30) so that both side edges extending in the longitudinal direction face the inner edge side of the rim covering portion 30, that is, the side facing the boss portion 12, in other words, facing away from each other in the meridian direction at a position closer to the rotation center of the steering wheel 10. The detection body 1 is wound around the rim covering portion 30 of the covering portion 25 with the electrode 3 on the inside, that is, the surface side of the covering portion 25, facing the core 20, and the electrode 2 on the outside.

[0028] Furthermore, the detection body 1, together with the covering portion 25, mainly the surface of the rim covering portion 30, is covered by a skin body 40. The skin body 40 is formed in the shape of a thin sheet of natural leather, synthetic leather, synthetic resin, or the like, and is wrapped around the surface of the rim covering portion 30 to cover the entire rim covering portion 30. The skin body 40 is in close contact with the electrode 2 and is set to the same electrical potential as the electrode 2. In this embodiment, the surface of the skin body 40 forms the surface of the rim portion 13. However, the detection body 1 may also be embedded in the covering portion 25, in which case the skin body 40 may not be provided and the covering portion 25 may form the surface of the rim portion 13.

[0029] The detection device 42 connected to the detection body 1 may be, for example, an on-board control unit (ECU). The electrodes 2 and 3 are directly and electrically connected to the detection device 42 by wires 43 and 44, which are lead wires, respectively. The reference potential of the detection device 42 is directly electrically connected to the core 20 by wire 45, which is a lead wire, and is also directly electrically connected to the reference potential of the vehicle body by wire 45, which is a lead wire. The core 20 is also electrically connected to the reference potential of the vehicle body via the steering shaft. Therefore, the core 20 and the detection device 42 are each set to substantially the same potential as the reference potential of the vehicle body. Furthermore, power is supplied to the detection device 42 from the vehicle body via a power supply line.

[0030] In this electrical configuration, a capacitance is generated between the electrodes 2 and 3 in the detection body 1, the capacitance being set according to the opposing area, the distance between them, and the dielectric constant of the insulator 4. A capacitance is also generated between the electrode 3 and the core 20. A capacitance, which is a structural parasitic capacitance, is also generated between the electrode 2 and the core 20. The capacitance between the electrode 3 and the core 20 is charged by an input from the detection device 42 to the electrode 3.

[0031] When the user's hand approaches or comes into contact with rim 13, detection device 42 detects that the user is gripping rim 13 in response to fluctuations in the differential signal due to the capacitance generated between the hand and electrode 2. For example, detection device 42 counts the number of times the periodically detected differential signal is equal to or greater than a predetermined threshold, and if the count exceeds a predetermined number within a predetermined time period, it determines that the user is gripping rim 13.

[0032] In this case, according to one embodiment, the insulator 4 located between the electrodes 2, 3 is formed by stacking multiple insulating layers 6 cut into sheets from a single foamed resin body 7, and at least two of these insulating layers 6 are overlapped with each other so that the surfaces 8 of the cut-out surfaces PL from the foamed resin body 7 do not coincide with each other.Therefore, even if there is a hole caused by an air bubble that penetrates through a single insulating layer 6 in the thickness direction, the cut-out surfaces PL of the insulating layers 6 do not coincide, so that the occurrence of a short circuit between the electrodes 2, 3 caused by air bubbles can be suppressed with a simple configuration using only the same material, without using any special material.

[0033] In other words, when insulating layers 6 are cut out from a molded foamed resin body 7 and adjacent to each other via the same cut-out surface PL, there is a high possibility that holes caused by bubbles formed in the foamed resin body 7 will be formed in the same position, and if the layers are pasted together as is, holes will be formed that penetrate the insulator 4, which may cause a short circuit between the electrodes 2 and 3. However, in this embodiment, by overlapping surfaces 8 whose cut-out surfaces PL from the foamed resin body 7 do not coincide with each other, even if large bubbles are formed in the foamed resin body 7, holes that penetrate the insulator 4 in the thickness direction will not be formed, and short circuits between the electrodes 2 and 3 due to such through holes can be suppressed.

[0034] Therefore, the occurrence of through holes that cause short circuits can be suppressed without significantly changing the mechanical properties of the insulator 4, such as capacitance and elongation.

[0035] In particular, when the detection body 1 is used on the rim portion 13 of the steering wheel 10, a compressive force often acts across the electrodes 2 and 3 when the driver grips the rim portion 13, and so if a through hole is formed in the insulator 4, the through hole is likely to trigger a short circuit between the electrodes 2 and 3. Therefore, by using the detection body 1 as described above, a short circuit between the electrodes 2 and 3 is unlikely to occur even if the driver grips the rim portion 13, and it can be suitably used as a grip sensor that detects gripping of the rim portion 13.

[0036] Therefore, the accuracy of detecting the state of grip of the rim portion 13 by the driver can be improved, which also contributes to improving the accuracy of automatic driving based on the detection of the grip state.

[0037] In addition, by making each insulating layer 6 approximately uniform in thickness, it becomes easier to cut out the insulating layer 6 from the foamed resin body 7, and the range of combinations of insulating layers 6 that can be selected is expanded to prevent through holes from occurring in the insulator 4 formed from insulating layers 6 cut out from the same foamed resin body 7.

[0038] On the other hand, by making the thickness of any one of the insulating layers 6 different from the thickness of the remaining insulating layers 6, the capacitance of the insulator 4 as a whole can be controlled by appropriately selecting the thickness of the insulating layers 6 to be superimposed.

[0039] In the embodiment, the insulator 4 is formed by overlapping the cut-out surfaces PL of the insulating layers 6 from the foamed resin body 7 with their surfaces 8 not aligned with each other. However, this is not limited to this. The insulator 4 may be formed by overlapping the cut-out surfaces PL of the insulating layers 6 with their surfaces not aligned with each other in at least one of the three-dimensional directions (X, Y, and Z directions) of the foamed resin body 7. For example, one insulating layer 6 and another insulating layer 6 may be overlapped by rotating them at a predetermined angle less than 360°, for example, 180°, around the normal direction of the cut-out surfaces PL. In other words, the positive and negative polarities of the X and Y directions of the foamed resin body 7 are opposite between the one insulating layer 6 and the other insulating layer 6. This configuration achieves the same advantageous effects as the above-described embodiment, such as suppressing short-circuiting between the electrodes 2 and 3 due to bubbles, even if a single insulating layer 6 has a hole due to a bubble that penetrates the thickness of the insulating layer 6.

[0040] Furthermore, the detection body 1 is not limited to the rim portion 13 of the handle 1, but may be applied to any device. [Industrial Applicability]

[0041] The present invention can be suitably used as a detection element such as a grip sensor used in a steering wheel of a vehicle such as an automobile. [Explanation of symbols]

[0042] 1 Detected object 2,3 electrodes 4. Insulators 6 insulating layer 7. Foam resin body 8 sides 10 Handle PL cut surface

Claims

1. a pair of electrodes arranged opposite to each other; an insulator interposed between the electrodes, the insulator is formed by stacking a plurality of insulating layers each cut into a sheet shape from a single foamed resin body; At least two of the insulating layers are overlapped with each other such that the cut-out surfaces from the foamed resin body do not coincide with each other. A detection element characterized by:

2. a pair of electrodes arranged opposite to each other; an insulator interposed between the electrodes, the insulator is formed by stacking a plurality of insulating layers each cut into a sheet shape from a single foamed resin body; At least two of the insulating layers are superposed on each other so that at least one of the three-dimensional directions of the foamed resin body does not coincide with each other. A detection element characterized by:

3. Each insulating layer has a substantially uniform thickness.

3. The detection element according to claim 1 or 2.

4. The thickness of any of the insulating layers is different from the thickness of the remaining insulating layers.

3. The detection element according to claim 1 or 2.

5. The detecting element according to claim 1 or 2 is provided. A handle characterized by:

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