JP2018028444A - Load sensor, load detection device, and seating sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a load sensor which can accurately detect a load using a conductive elastic member.SOLUTION: In a seating sensor 30, a conductive pad 38 is arranged between electrode parts 34, 36. In the electrode part 34, an insulation sheet 42 is arranged between an electrode thread 50 sewn into a basis material 38 having elasticity, and the conductive pad 38. The insulation sheet 42 is in a form of mesh with openings aligned therein. The conductive pad 38 is compressed by input of a load, and the electrode thread 50 makes contact with the conductive pad 38 via the openings of the insulation sheet 42. When the load is increased, displacement of the conductive pad 38 increases, and a contact area between the conductive pad 38 and the electrode thread 50 increases. In this way, since an electrical resistance value between the electrode parts 34, 36 largely changes according to the load being input, the seating sensor 30 can accurately detect the load being input from the electrical resistance value.SELECTED DRAWING: Figure 3

Description

    The present invention relates to a load sensor, a load detection device, and a seat for seating.

  In a seat such as a vehicle seat on which a vehicle occupant is seated, a cushion pad using urethane foam or the like is provided for the seat cushion. Further, in the vehicle seat, the cushion pad is elastically deformed according to the load received from the occupant seated on the seat cushion, so that the occupant can obtain a comfortable sitting comfort.

  On the other hand, the vehicle is provided with an occupant protection device such as an airbag device or a seat belt device, and the occupant seated on the vehicle seat is protected by operating the occupant protection device in the event of a vehicle emergency. The vehicle is also provided with an occupant detection sensor that detects whether or not an occupant is seated on the vehicle seat, and the operation of the occupant protection device is controlled in accordance with the detection result of the occupant detection sensor. There is something that made it so.

  As an occupant detection sensor provided in a vehicle seat, an electrostatic capacity method, a method using a strain sensor provided between a vehicle seat and a rail for fixing the vehicle seat to a vehicle body, a seat on which an occupant sits There is a method using a pressure sensor provided on a cushion. For example, Patent Document 1 proposes a capacitive occupant detection device. In the occupant detection device of Patent Document 1, a comb-like conductor is provided on the surface portion of the vehicle seat as a detection electrode, and the capacitance between the detection electrode and the vehicle body caused by the occupant sitting on the vehicle seat. Is detected as a change in the oscillation frequency by the oscillation circuit. Moreover, in the passenger | crew detection apparatus of patent document 1, it detects whether a passenger | crew is an adult with a large physique, or a child with a small physique from the change of electrostatic capacitance.

  In the case where an occupant detection sensor is provided in a vehicle seat, it is required that the seating comfort of the occupant seated on the seat cushion is not affected. Here, as an elastic member such as urethane foam, there is a conductive elastic member whose electric resistance value is changed by being elastically compressed. By using a conductive elastic member for the cushion pad and detecting a change in the electric resistance value of the conductive elastic member, it is possible to detect whether or not an occupant is seated on the seat cushion. It is also possible to detect from the resistance value of the conductive elastic member whether the occupant seated on the vehicle seat is an adult with a large physique (heavy weight) or a child with a small physique (small weight).

JP 2012-032342 A

  By the way, in a vehicle provided with an occupant protection device, when it is detected that the occupant is seated on the seat cushion, it is possible to detect not only whether the occupant seated on the seat cushion is an adult or a child, but also a more detailed physique. Required.

  The present invention has been made in view of the above-described facts, and an object thereof is to provide a load sensor, a load detection device, and a seat for seating that can accurately detect a load using a conductive elastic member.

  In order to achieve the above object, a load sensor according to claim 1 of the present invention is elastically compressed according to an input load, and is provided between one surface of the load in the input direction and a surface opposite to the one surface. A conductive elastic member whose electrical resistance value varies, a stretchable sheet disposed on the one surface side of the conductive elastic member, and a surface of the stretchable sheet facing the conductive elastic member side are provided. A first electrode and a second electrode provided opposite to the surface of the conductive elastic member opposite to the one surface and electrically connected to the first electrode via the conductive elastic member; A plurality of openings each having a predetermined size are arranged in a mesh shape, provided between the conductive elastic member and at least one of the first electrode and the second electrode, and elastically compressed to form the opening. Through the conductive elastic member entering the portion. It comprises a insulating sheet to electrically connectable, a and the second electrode and the.

  The load sensor according to claim 1 uses a conductive elastic member. The conductive elastic member is an elastic member that is elastically deformed and compressed according to the input load when the load is input. In addition, the conductive elastic member has conductivity because conductive carbon particles or the like are supported on the elastic member. For this reason, the conductive elastic member changes so that the electric resistance value between the one surface and the surface opposite to the one surface is reduced by being compressed. As such a conductive elastic member, for example, a conductive urethane foam in which conductivity is supported on a polyurethane foam (urethane foam) which is an elastic member can be applied.

  A stretchable sheet is provided on one surface of the conductive elastic member, and a first electrode is provided on the conductive elastic member side of the stretchable sheet. By providing the first electrode on the stretchable sheet, the first electrode expands and contracts following the elastic deformation of one surface of the conductive elastic member, and can be electrically connected to the conductive elastic member. The conductive elastic member is provided with a second electrode on the surface opposite to the one surface, and the electric resistance value of the conductive elastic member is detected by the first electrode and the second electrode.

  The insulating sheet has a mesh shape in which openings of a predetermined size are arranged. The insulating sheet is provided between at least one of the first electrode and the second electrode and the conductive elastic member. For this reason, for example, when the insulating sheet is disposed between the first electrode and the conductive elastic member, the first electrode is removed from the conductive elastic member when no load is input to the conductive elastic member. Since it leaves | separates, the electrical resistance value between a 1st electrode and a 2nd electrode becomes high. Further, when a load is input to the conductive elastic member, a part of the conductive elastic member enters the opening of the insulating sheet. Therefore, each of the first electrode and the second electrode is in contact with the conductive elastic member. Moreover, when the input load increases, the contact area between the conductive elastic member that has entered the opening and the first electrode increases.

  Thereby, the first electrode and the second electrode are electrically connected via the conductive elastic member, and the electric resistance value generated in the conductive elastic member and the contact area between the conductive elastic member and the first electrode are increased. A corresponding electrical resistance value is detected. At this time, the electrical resistance value is lowered by compressing the conductive elastic member, and the electrical resistance value is lowered by increasing the contact area between the conductive elastic member and the first electrode. Therefore, the electrical resistance value between the first electrode and the second electrode changes greatly between the state in which no load is input to the conductive elastic member and the state in which the load is input, and the load is applied to the conductive elastic member. Whether it is input or not can be detected with high accuracy. In addition, since the change in the electrical resistance value between the first electrode and the second electrode with respect to the change in the input load is greater than when no insulating sheet is provided, the input load is highly accurate. Can be detected.

  In the load sensor according to claim 2, the insulating sheet is provided with a plurality of small holes having openings smaller than the opening around the opening, and is elastically compressed to enter the small hole. The first electrode and the second electrode can be electrically connected via a conductive elastic member.

  In the load sensor according to the second aspect, a plurality of small holes that are smaller than the opening are formed in the insulating sheet. When the input load increases, the conductive elastic member enters the small hole of the insulating sheet. For this reason, the conductive elastic member and the first electrode (or the second electrode) are connected via the opening and the small hole opened smaller than the opening by further increasing the load input to the conductive elastic member. Therefore, the contact area of the first electrode (or the second electrode) that contacts the conductive elastic member increases. As a result, the electrical resistance value between the first electrode and the second electrode decreases according to the displacement of the conductive elastic member and the increase in the contact area of the first electrode, and therefore only according to the displacement of the conductive elastic member. It changes more greatly than the electrical resistance value.

  Therefore, since the change of the electrical resistance value between the first electrode and the second electrode is added to the displacement of the electrical resistance value of the conductive elastic member according to the input load, the first electrode and the second electrode The range in which the load input to the conductive elastic member can be detected with high accuracy from the electric resistance value between them is widened.

  In the load sensor according to a third aspect, the first electrode is formed by sewing a conductive thread into the stretchable sheet.

  In the load sensor according to the third aspect, a conductive yarn is used. The conductive yarn has conductivity, and the first electrode is formed by sewing the conductive yarn into the stretchable sheet. Since the conductive yarn is intermittently held on the stretchable sheet at the seam, it is possible to prevent the stretchability of the stretchable sheet from being impaired.

  According to a fourth aspect of the present invention, there is provided the load detecting device according to any one of the first to third aspects, and the electrical conductivity based on an electrical resistance value between the first electrode and the second electrode. A load output unit that outputs a load input to the elastic elastic member.

  The load detection device according to claim 4, wherein the load output unit is electrically connected to the first electrode and the second electrode, thereby detecting an electric resistance value between the first electrode and the second electrode. . The load output unit outputs a load (an electric signal corresponding to the load) input to the conductive elastic member based on the detected electric resistance value.

  A seat for seating according to claim 5 is a seat for seating provided with the load sensor according to any one of claims 1 to 3, wherein the conductive elastic member is provided on a cushion pad of the seat cushion. The elastic sheet and the insulating sheet provided with the first electrode are disposed on the upper surface side of the seat cushion, and the second electrode is disposed on the lower surface side of the seat cushion.

  In the seat for seating according to the fifth aspect, the conductive elastic member of the seating sensor is provided on the cushion pad of the seat cushion. The region where the conductive elastic member is provided only needs to include a region that receives a load from the seated person, so that when the person sits on the seat cushion, the load according to the physique (weight) of the seated person is conducted. The conductive elastic member is elastically deformed by being input to the conductive elastic member.

  Since a load corresponding to the elastic deformation of the conductive elastic member is input between the first electrode and the second electrode, a person can enter the seat cushion from the electric resistance value between the first electrode and the second electrode. Whether the person is seated or the physique of the person who is seated can be detected.

  Here, the elastic sheet provided with the first electrode is disposed on the upper surface side of the conductive elastic member, and is expanded and contracted according to the deformation of the upper surface of the conductive elastic member. Thereby, the 1st electrode provided in the elastic sheet does not impair the sitting comfort of the person seated on the seat cushion. Further, from the electrical resistance value between the first electrode and the second electrode, the physique (weight) of the occupant seated on the seat cushion can be detected with high accuracy as the load input to the conductive elastic member.

  The seat for seating of Claim 6 is provided with the load output part which outputs the load input into the said seat cushion based on the electrical resistance value between a said 1st electrode and a said 2nd electrode.

  In the seat for seating according to claim 6, the load output unit detects an electrical resistance value between the first electrode and the second electrode. The load output unit determines and outputs the load input to the seat cushion from the electrical resistance value between the first electrode and the second electrode. At this time, by measuring and storing in advance the displacement with respect to the load of the conductive elastic member and the electric resistance value with respect to the displacement, the load output unit determines the physique of the occupant seated on the seat cushion from the detected electric resistance value. Output with high accuracy.

  As described above, according to the present invention, by disposing a mesh-like insulating sheet in which a plurality of openings are arranged between one of the first electrode and the second electrode and the conductive elastic member, It has the effect that it can be detected appropriately whether the load was input into the elastic elastic member.

  Further, according to the present invention, the first electrode and the second electrode against the displacement of the conductive elastic member are provided by providing the insulating sheet with a plurality of small holes that are opened smaller than the opening together with the opening. Since the change in the electrical resistance value between the two electrodes can be increased, there is an effect that the range of loads that can be detected with high accuracy is widened.

It is a perspective view which shows the vehicle seat which concerns on this Embodiment. (A) And (B) is sectional drawing of the front view of a seat cushion, (A) shows the state in which the load is not input, (B) has shown the state in which the load was input. 1 is a schematic configuration diagram of an occupant detection device according to the present embodiment. (A) is a top view of an insulating sheet, (B) is an enlarged view of the principal part of an insulating sheet. (A) is a top view which shows the principal part of an electrode sheet, (B) is sectional drawing of (A). Each of (A) and (B) is a plan view seen from the insulating sheet side, showing an example of an electrode network formed on the electrode sheet by electrode yarns. It is the schematic which shows the change of the seating sensor according to the input load, the uppermost stage shows the state in which the load is not input, and the lower side from the uppermost stage shows the state in which the load increased in order. (A) is a diagram showing a change in resistance value with respect to displacement, and (B) is a chart showing a resistance value with respect to change in displacement.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view of a vehicle seat 10 as an example of a seat for seating according to the present invention. The vehicle seat 10 is provided in a vehicle (not shown) such as a passenger car, and an occupant seated in the vehicle is seated. In FIG. 1, the front of the seat is indicated by an arrow FR, the width direction of the seat is indicated by an arrow W, and the upper side of the seat is indicated by an arrow UP.

  As shown in FIG. 1, the vehicle seat 10 is provided with a seat cushion 12, a seat back 14, and a headrest 16. A pair of slide rails 18 are provided below the seat cushion 12, and the slide rails 18 are fixed to a vehicle body (not shown) with the longitudinal direction being the seat front-rear direction. The seat cushion 12 has a skeleton formed by a seat frame (not shown) including a metal seat pan, and the seat frame is bridged between a pair of slide rails 18 via a slide mechanism (not shown).

  The seat back 14 has a lower portion of a seat back frame (not shown) forming a skeleton coupled to the seat frame via a reclining mechanism (not shown) on the rear side of the seat cushion 12. The headrest 16 is provided integrally with the seat back 14 at the upper end portion of the seat back 14. Thus, the vehicle seat 10 is supported by the slide rail 18 and can move in the front-rear direction, and the seat back 14 can tilt with respect to the seat cushion 12.

  2A and 2B, the seat cushion 12 is shown in a cross-sectional view as viewed from the front. 2A shows the seat cushion 12 in a state where no occupant is seated, and FIG. 2B shows an example of the seat cushion 12 in a state where the occupant is seated. Has been.

  As shown in FIGS. 2A and 2B, the seat cushion 12 is provided with a cushion pad 20 as an elastic member, and the surface of the cushion pad 20 is covered with a skin material 22. . The vehicle seat 10 has a general configuration in which a cushion pad (not shown) of the seat back 14 and the headrest 16 is covered with a skin material 22. The vehicle seat 10 is defined by the material of the cushion pad 20, cushioning properties, elastic characteristics, and the like so that the occupant can have a comfortable sitting comfort and a comfortable riding comfort. The cushion pad 20 according to the present embodiment uses urethane foam (soft polyurethane foam) which is a polyurethane foam as an example of an elastic member.

  As shown in FIGS. 1, 2 (A), and 2 (B), the seat cushion 12 is provided with a side support portion 24, and the side support portion 24 protrudes on both sides in the width direction of the cushion pad 20. It is formed in a shape and faces the side of the thigh of the occupant. The seat cushion 12 is provided with a substantially flat seat portion 26 between which the occupant sits between the side support portions 24.

  The occupant is seated on the seat cushion 12 so that the buttocks and thighs are supported by the seat 26 and the back is supported by the seat back 14. Further, as shown in FIG. 2B, a load is applied to the seat portion 26 of the seat cushion 12 according to the physique (weight) of the seated occupant, and the cushion pad 20 is elastically deformed and compressed.

  Incidentally, the vehicle seat 10 is provided with an occupant detection device 28 as a load detection device. FIG. 3 shows the occupant detection device 28 in a schematic configuration diagram. The occupant detection device 28 is provided with a seating sensor 30 as a load sensor and an ECU (Electronic Control Unit) 32 as a load output unit.

  The seating sensor 30 is provided with an electrode part 34 provided with a first electrode, an electrode part 36 as a second electrode, and a conductive pad 38 using a conductive elastic member. A conductive pad 38 is disposed between the portion 36. In the present embodiment, urethane foam that is an elastic member similar to the cushion pad 20 is applied as an elastic member (conductive elastic member) that forms the conductive pad 38. In addition, the urethane foam used for the conductive pad 38 is a conductive urethane foam (conductive flexible polyurethane foam) having conductivity.

Urethane foam has an extremely high electrical resistance value (hereinafter referred to as a resistance value) (for example, a volume resistivity of 10 ¹¹ Ωm or more) and functions as an electrical insulator. The conductive urethane foam can be obtained by supporting conductive carbon particles such as carbon black on the urethane foam. Since the conductive urethane foam contains conductive carbon particles, the resistance value is lower than that of the urethane foam (for example, the volume resistivity is 10 ⁷ Ωm or less), and functions as a conductor.

  The conductive urethane foam is frequently used as a protective packaging material for electronic parts, an electronic shielding material, and the like. In this embodiment, the conductive urethane foam is used for the conductive pad 38. In addition, what was manufactured using the well-known method which makes electroconductive urethane foam carry | support electroconductive carbon particles, such as carbon black, etc. to urethane foam can be applied. In addition, the conductive urethane foam is not limited to the one using conductive carbon particles such as carbon black, and one obtained by imparting conductivity to the urethane foam by any method can be applied.

  In general, the conductive urethane foam has a higher resistance value as the thickness increases than when the thickness is small (thin). In addition, the conductive urethane foam is elastically compressed according to the load received by receiving the load, and the resistance value becomes lower than that when the conductive urethane foam is not compressed by being compressed. That is, the conductive urethane foam has a characteristic that the resistance value is lowered by being compressed according to the input load. As a result, the conductive pad 38 changes so that the electric resistance value is lowered by being compressed. In the seating sensor 30, the resistance value of the conductive pad 38 is generated between the electrode portions 34 and 36 by electrically connecting the electrode portions 34 and 36 to the conductive pad 38.

  As shown in FIG. 1, the seating sensor 30 of the occupant detection device 28 is provided on the seat cushion 12 of the vehicle seat 10. The conductive pad 38 of the seating sensor 30 is provided in the seat portion 26 of the seat cushion 12 so as to form a part of the cushion pad 20 in a portion where the occupant's buttocks abuts. As a result, the conductive pad 38 is elastically compressed by receiving a load corresponding to the physique (weight) of the occupant seated on the seat portion 26 of the seat cushion 12, and the upper surface of the conductive pad 38 by the softness and repulsive force of the conductive urethane foam. Is curved according to the physique of the occupant (the shape on the lower side of the buttocks).

Here, as the cushion pad 20 and the conductive pad 38, urethane foam having a hardness at IDL of 25% (a hardness according to an apparent density hardness test D method of JIS K6401) of 100 to 400 N (100 to 400 N / 314 cm ² ). Can be applied. The cushion pad 20 provided on the vehicle seat 10 is set to a hardness that provides a comfortable sitting comfort and a comfortable riding comfort for the occupant within the above-described hardness range. The hardness of the conductive pad 38 is the same as that of the cushion pad 20.

  The conductive pad 38 may be foam-molded so that the entire cushion pad 20 used for the seat cushion 12 or a portion corresponding to the seat portion 26 of the cushion pad 20 is conductive. In addition, the conductive pad 38 may be fitted into a portion of the cushion pad 20 corresponding to the electrode portions 34 and 36 (a portion that receives a load from the occupant). When the conductive pad 38 is fitted into the cushion pad 20, for example, the urethane foam of a necessary part is cut out from the cushion pad 20, and the conductive pad 38 is made to be conductive by performing a process for imparting conductivity to the cut out urethane foam. Form. Then, the seat cushion 12 provided with the conductive pad 38 is obtained by fitting the formed conductive pad 38 into the original portion of the cushion pad 20.

  An electrode portion 36 is disposed on the lower surface of the conductive pad 38 and is electrically connected. Further, an electrode portion 34 is disposed on the upper surface of the conductive pad 38, and the electrode portion 34 is covered with the skin material 22. Further, in the occupant detection device 28, the electrode portions 34 and 36 of the seating sensor 30 are electrically connected to the ECU 32.

  The ECU 32 detects the resistance value between the electrode portions 34 and 36, and detects the magnitude of the load input to the conductive pad 38 from the detected resistance value. Further, the ECU 32 is electrically connected to an occupant protection device provided in the vehicle such as a seat belt device or an airbag device, and outputs the detected magnitude of the load to the occupant protection device.

  Here, a metal material having conductivity such as iron or aluminum is applied to the electrode portion 36. Moreover, the electrode part 36 is applied with any shape that can be electrically connected to the conductive pad 38. As such an electrode part 36, a metal plate such as iron having a thickness of about 0.3 mm to 1.0 mm can be formed into a pan shape (flat plate shape, concave shape) by press forming. Moreover, the electrode part 36 may be applied with a mesh shape (punching metal) in which perforations having a predetermined shape are uniformly formed in a press-formed metal plate.

  Further, the vehicle seat 10 is provided with a metallic seat pan below the seat cushion 12, and the seat pan contacts the lower surface of the cushion pad 20 to support the cushion pad 20. A sheet pan can be used for the electrode part 36. In the present embodiment, a sheet pan is used for the electrode part 36. The electrode unit 36 is not limited to a sheet pan as long as it is electrically connected to the lower surface of the conductive pad 38, and a sheet carrying a conductor or a general electrode using metal is applied. be able to. Furthermore, even when the cushion frame is not provided with a seat pan, when the cushion frame is made of metal, the electrode portion 36 may be a cushion frame.

  On the other hand, the electrode part 34 of the seating sensor 30 is provided with an electrode sheet 40 and an insulating sheet 42 as an insulating sheet. In the electrode portion 34, the insulating sheet 42 is disposed on the conductive pad 38 side, and the electrode sheet 40 is overlaid on the insulating sheet 42. The electrode sheet 40 and the insulating sheet 42 cover the upper surface of the conductive pad 38 in a region where the seat cushion 12 receives a load from the occupant.

  As the insulating sheet 42, a sheet (sheet) having an insulating property such as an insulating resin film, a woven fabric, a knitted fabric, and the like and having a stretchability is used. 4A shows a plan view of an insulating sheet 42 using a woven fabric as an example, and FIG. 4B shows a main part of the insulating sheet 42 shown in FIG. 4A. It is shown in an enlarged view. In FIG. 4, as an example, a tulle mesh (trade name manufactured by Toray, model number # 2070) that is a woven fabric using polyester fibers is shown. In FIG. 4B, white portions are fibers (woven yarns). The black portion indicates a void (opening).

  The insulating sheet 42 is formed in a mesh shape by providing openings (hereinafter referred to as openings 44) arranged vertically and horizontally as openings. Generally, the size (size) of openings formed by arranging wire rods (woven yarns) vertically and horizontally is represented by the interval (opening width) between the vertical and horizontal wire rods. In a mesh in which openings are formed, the opening ratio ε is obtained from the thickness of the wire and the opening width of the openings.

  As shown in FIG. 4B, in the present embodiment, the diameter (inner diameter IDa) of the inscribed circle 46 of the opening 44 is used as the size of the opening 44 (size of the opening). . The opening ratio ε of the opening 44 (hereinafter referred to as the opening ratio ε1) is the ratio of the total area of openings (opening 44) per unit area (1 square inch) (the area of the opening 44 relative to the unit area). %) Is applied.

  Here, as the insulating sheet 42, it is preferable that a mesh-shaped insulating sheet having an inner diameter IDa of the inscribed circle 46 in a range of IDa = 20 μm to 2.0 mm (2000 μm) is applied. As the insulating sheet 42, an insulating sheet having an opening ratio ε per unit area of the opening 44 and the small hole 44A described below in the range of ε = 20% to 80% is preferably applied. Furthermore, the insulating sheet 42 has a thickness of 20 μm to 2.0 mm in a portion excluding the opening 44 and the following small hole 44A.

  The insulating sheet 42 is provided with a plurality of small holes 44 </ b> A as small holes, and each of the small holes 44 </ b> A is opened around the opening 44 smaller than the opening 44. In the present embodiment, the size of the opening of the small hole 44A is indicated by the diameter (inner diameter IDb) of an inscribed circle 46A that is a circle in contact with the peripheral edge of the opening similarly to the opening 44. The inscribed circles 46 and 46A are the circles having the largest diameter among the circles in contact with at least two points on the periphery in each of the opening 44 and the small hole 44A.

  The insulating sheet 42 has an inner diameter IDb of the inscribed circle 46A of the small hole 44A and an opening ratio ε (hereinafter referred to as an opening ratio ε2) of the small hole 44A per unit area (1 square inch). The aperture ratio ε2 of the small hole 44A is a percentage of the total area (opening area) of the small hole 44A with respect to the unit area, and the area of the portion other than the small hole 44A includes the area of the opening 44.

  As the insulating sheet 42, an insulating sheet having a thickness, an inner diameter IDa of the opening 44, and an opening ratio ε of the opening 44 according to the outer diameter of the following electrode yarn 50 is used within the above range. As the insulating sheet 42, an insulating sheet having a thickness, an inner diameter IDb of the small hole 44A, and an opening ratio ε of the small hole 44A according to the outer diameter of the electrode yarn 50 described below is used.

  When a woven fabric and a knitted fabric are applied as the insulating sheet 42, the fiber yarn (woven yarn) forming the woven fabric and the knitted fabric is a synthetic fiber (resin) such as nylon (may be nylon 6 or nylon 66) fiber or polyester fiber. Fiber). The insulating sheet 42 can be made of synthetic fibers such as polyolefin fibers such as polyethylene (PE) and polypropylene (PP). The insulating sheet 42 is woven or knitted so that the openings 44 and the plurality of small holes 44A are formed by these synthetic fiber yarns or yarns formed by twisting synthetic fibers. At this time, the stretchability of the insulating sheet 42 is improved by weaving the yarn so that the small holes 44A are continuous in a chain.

  The electrode sheet 40 is formed by a base 48 as an elastic sheet and an electrode yarn 50 as a conductive yarn forming the first electrode. 5A shows a plan view of the main part of the electrode sheet 40, and FIG. 5B shows the main part of the electrode sheet 40 shown in FIG. It is shown in a sectional view along the sewing direction.

  The electrode sheet 40 is a sheet in which the base 48 has stretchability and insulation, and the base 48 preferably has a stretch rate of 130% or more, and a fabric (cloth) such as spandex. ) And resin films are applied. In the present embodiment, as an example of the substrate 48, a spandex having an expansion ratio equal to or greater than that of the skin material 22 of the seat cushion 12 is used.

  The electrode yarn 50 is formed by vapor-depositing a conductive metal on a fiber yarn, and conductivity is imparted by the metal vapor-deposited on the fiber yarn. Natural fibers may be used for the fiber yarns, but artificial fibers are preferable because metal deposition is performed, and synthetic fibers (resin fibers) such as polyester fibers are applied. The electrode yarn 50 is formed by twisting a plurality of (for example, two or three) fiber yarns, and has a wire diameter (outer diameter) in a range of 0.1 mm to 1.0 mm by metal deposition. Can be used. Moreover, as a metal vapor-deposited on a fiber thread | yarn, the alloy etc. which were formed by combining arbitrary metals, such as silver (Ag), gold | metal | money (Au), nickel (Ni), or multiple types of metals, etc. can be used.

  In the seating sensor 30, the outer diameter of the electrode yarn 50 and the sizes of the opening 44 and the small hole 44 </ b> A of the insulating sheet 42 are associated with each other. For example, the insulating sheet 42 is provided with an opening 44 in which the inner diameter IDa of the inscribed circle 46 is at least larger (including slightly larger) than the outer diameter of the electrode yarn 50, and the inner diameter IDa of the inscribed circle 46 is provided. Is more preferably provided with an opening 44 that is twice or more the outer diameter of the electrode yarn 50. The insulating sheet 42 is provided with a plurality of small holes 44A in which the inner diameter IDb of the inscribed circle 46A is smaller than the inner diameter IDa of the opening 44, and the inner diameter IDb of the inscribed circle 46A is an electrode thread. It is approximately the same as or slightly smaller than the outer diameter of 50. That is, the small hole 44 </ b> A has an inner diameter IDb that is equal to or smaller than the outer diameter of the electrode yarn 50.

  In the electrode sheet 40, an electrode thread 50 is sewn into the substrate 48 and is arranged. Arbitrary patterns can be applied to the wiring of the electrode yarn 50 to the substrate 48, but the area of the electrode yarn 50 appearing on the insulating sheet 42 side is large (long) and the stretchability of the substrate 48 is impaired. A pattern with no is preferred.

  FIG. 5A shows an example of the pattern of the electrode yarn 50 arranged on the substrate 48 in a plan view seen from the insulating sheet 42 side. 5B is a cross-sectional view of the main part of FIG.

  As shown in FIG. 5A, in the present embodiment, a staggered pattern 52 is applied as a pattern (seam pattern) for sewing the electrode thread 50 into the substrate 48. The staggered pattern 52 is obtained by alternately sewing the electrode threads 50 on the left and right sides around the wiring 54 with respect to the virtual wiring 54 along the sewing direction of the electrode thread 50. Yes. That is, the staggered pattern 52 is so-called zigzag stitching that is zigzag stitched so that the electrode threads 50 (stitches of the electrode threads 50) intersect the wiring 54.

  In the staggered pattern 52, the base 48 may be sewn with the electrode thread 50 on both the left and right sides of the wiring 54. Instead of scooping the base 48 with the electrode thread 50, the electrode thread 50 may be sewn with the base 48. You may be allowed to pass through. Further, when one electrode yarn 50 is inserted, the length of the electrode yarn 50 that appears on the insulating sheet 42 side of the substrate 48 is shortened. From here, the two electrode yarns 50 may be used, and the two electrode yarns 50 may be sewn into the substrate 48 so as to alternately appear on the insulating sheet 42 side. Thereby, since the gap between the stitches of the electrode thread 50 appearing on the insulating sheet 42 side can be continuously formed without opening, the length of the electrode thread 50 on the insulating sheet 42 side can be increased, and the insulating sheet 42 side The surface area of the electrode yarn 50 can be increased.

  As shown in FIG. 5B, in the present embodiment, an electrode yarn 50 and a non-conductive yarn (hereinafter referred to as a locking yarn 50A) are used. As the locking yarn 50A, any yarn can be used, and the fiber yarn before metal vapor deposition used for the electrode yarn 50 can be used. In the staggered pattern, the electrode yarn 50 is routed on one surface of the substrate 48, and the locking yarn 50A is routed on the other surface. At this time, the electrode thread 50 sewn into the substrate 48 is sewed together by the locking thread 50A sewn into the substrate 48 from the opposite side of the electrode thread 50, so that the electrode thread 50 and the locking thread 50A are sewn into the substrate 48. . As a result, the electrode yarn 50 is routed on one surface of the substrate 48, and the locking yarn 50 </ b> A is routed on the other surface of the substrate 48.

  In addition, as a method of routing the electrode yarn 50 on the substrate 48 with the staggered pattern 52, the electrode yarn 50 and the engagement yarn 50A are held on both the left and right sides of the routing wire 54 so that the electrode yarn 50 is wound. The stop yarns 50 </ b> A may be locked to the substrate 48. As a method of wiring the electrode yarn 50 on the substrate 48 with the staggered pattern 52, contrary to the above-described method, the electrode yarn 50 is used to squeeze the locking yarn 50A on both the left and right sides of the wiring 54. The electrode yarn 50 and the locking yarn 50A may be locked to the substrate 48.

  Here, as shown in FIG. 5A, the stitch interval ND of the electrode yarn 50 can be set to about ND = 3 mm to 5 mm, and is a dimension in a direction intersecting with the wiring 54 of the electrode yarn 50. A certain stitch width NW can be about NW = 3 mm to 5 mm. In addition, if the angle α (see FIG. 5A) between the electrode yarns 50 adjacent to each other along the wiring 54 is too narrow (too small), the substrate with respect to the direction in which the electrode yarn 50 intersects the wiring 54. If the angle α is too wide (too large), the electrode yarn 50 may suppress the expansion and contraction of the substrate 48 in the direction along the routing line 54. From here, the angle α is preferably in the range of 30 ° to 150 °. Further, by determining the stitch interval ND and the angle α, the length L of the electrode thread 50 for one stitch in the staggered pattern 52, that is, the stitch width NW of the staggered pattern 52 is determined. Accordingly, the staggered pattern 52 has a stitch interval ND and a stitch width NW that are set so that the stretchability of the substrate 48 is not impaired and the length of the electrode yarn 50 that appears on the insulating sheet 42 side is increased. It is determined and formed on the substrate 48.

  Since the staggered pattern 52 is applied to the electrode sheet 40 as a pattern for arranging the electrode yarns 50, it is possible to prevent the vertical and horizontal stretchability of the substrate 48 into which the electrode yarns 50 are sewn from being impaired. In the electrode sheet 40, the electrode thread 50 is sewn into a region of the substrate 48 (for example, substantially the entire region of the substrate 48) corresponding to a region where a load is input to the conductive pad 38. As a result, an electrode network as a first electrode is formed on the substrate 48. FIGS. 6A and 6B are plan views showing an example of an electrode network applicable in this embodiment.

  In the electrode network 56 shown in FIG. 6 (A), straight wiring lines 54A and 54B are set in a lattice form vertically and horizontally at a predetermined stitch interval SD. In the electrode network 56, the electrode thread 50 is sewn by the staggered pattern 52 along each of the plurality of wirings 54 </ b> A and 54 </ b> B.

  When the interval between the adjacent wiring lines 54A (or the wiring lines 54B) is the stitch interval SD (the stitch interval SD1 of the routing line 54A, the stitch interval SD2 of the routing line 54B), the stitch interval SD is If it is narrow, it will affect the stretchability of the substrate 48, and if the stitch interval SD is wide, the arrangement of the electrode threads 50 will be sparse. From here, the electrode network 56 has a stitch interval SD set in a range of SD = 1 cm to 10 cm (SD1 = 1 cm to 10 cm, SD2 = 1 cm to 10 cm).

  In the electrode network 58 shown in FIG. 6B, a plurality of wiring lines 54C each having a circular shape with different radii are set concentrically. In the electrode network 58, a plurality of straight wiring lines 54D are set radially from the center position of the wiring line 54C. In the electrode network 58, the electrode yarns 50 are routed by being sewn by the staggered pattern 52 along each of the routing lines 54C and 54D. In the electrode network 58, the interval between the adjacent wiring lines 54C is set as the stitch interval SD, and the electrode network 58 has a plurality of wiring lines 54C so as to have the stitch interval SD (SD = 1 cm to 10 cm). Each radius is set.

  In the electrode sheet 40, the stitch interval SD is set together with the stitch width NW and the stitch interval ND of the staggered pattern 52 so that the electrode threads 50 are evenly arranged in a predetermined region to form the electrode nets 56 and 58. Is done. At this time, the electrode yarn 50 faces or is adjacent to part or all of the openings 44 of the insulating sheet 42, and the electrode yarn 50 faces or is adjacent to part or all of the small holes 44 </ b> A.

  In the present embodiment, an electrode network 56 is formed on the electrode sheet 40 as an example of the first electrode. The electrode sheet 40 may be formed with an electrode network having a combination of the electrode networks 56 and 58, such as disposing the electrode network 56 around the outer periphery of the electrode network 58. In addition, the electrode sheet 40 may be formed with an electrode network in the form of an oblique lattice in which each of the straight wiring lines 54A and 54B is inclined.

  In the seating sensor 30, an insulating sheet 42 having elasticity is disposed on the conductive pad 38, and the electrode sheet 40 is superimposed on the insulating sheet 42, whereby the conductive pad 38 is interposed via the electrode sheet 40 and the insulating sheet 42. Load is input to. Accordingly, even if the upper surface of the conductive pad 38 is waved by the input load (displacement due to elastic compression), the insulating sheet 42 is brought into close contact with the upper surface of the conductive pad 38 and the electrode of the electrode sheet 40 The thread 50 is brought into close contact with the insulating sheet 42.

  In the occupant detection device 28, the electrode threads 50 arranged on the electrode sheet 40 of the seating sensor 30 are collectively connected and electrically connected to the ECU 32. Thereby, the ECU 32 can detect the resistance value between the electrode portions 34 and 36 by electrically connecting the electrode portions 34 and 36 to the conductive pad 38. The resistance value between the electrode portions 34 and 36 detected by the ECU 32 changes in accordance with the amount of displacement of the thickness when the conductive pad 38 is elastically deformed, and the resistance detected by increasing the amount of displacement. The value becomes lower. Further, the resistance value detected by the ECU 32 changes in accordance with the contact area of the electrode yarn 50 of the electrode part 34 that contacts the conductive pad 38, and becomes lower than when the contact area is widened.

  In the ECU 32, the displacement of the conductive pad 38 with respect to the load and the resistance value between the electrode portions 34 and 36 with respect to the displacement of the conductive pad 38 are measured in advance, and stored as a map of the load with respect to the resistance value, for example. The ECU 32 determines the load input to the conductive pad 38, that is, the weight of the passenger seated on the vehicle seat 10, from the resistance value between the electrode portions 34 and 36 and the load map with respect to the resistance value stored in advance. .

Next, the operation of the present embodiment will be described.
The seat cushion 12 of the vehicle seat 10 is provided with the conductive pad 38 of the seating sensor 30 together with the cushion pad 20, and when the occupant sits on the seat cushion 12, the conductive pad 38 becomes the physique (weight) of the occupant. Accordingly, it is elastically deformed and compressed. Thereby, in the seating sensor 30, the resistance value of the conductive pad 38 between the electrode portions 34 and 36 changes. The ECU 32 of the occupant detection device 28 detects the resistance value between the electrode portions 34 and 36 of the seating sensor 30, and the load input to the conductive pad 38 from the detected resistance value, that is, the occupant seated on the seat cushion 12. Determine the body weight (physique).

  Here, a conductive urethane foam is used for the conductive pad 38, and the conductive urethane foam has the same elastic characteristics as the cushion pad 20 of the seat cushion 12. In addition, the electrode portion 34 of the seating sensor 30 uses a stretchable substrate 48 for the electrode sheet 40 and a stretchable fabric for the insulating sheet 42. As a result, the seat cushion 12 is restrained from changing its elastic characteristics from the original elastic characteristics, so that the seating sensor 30 can provide a comfortable feeling of loss of sitting comfort to the passenger seated on the seat cushion 12. Can be prevented.

  Further, in the seating sensor 30, the electrode yarn 50 is routed on the base 48 of the electrode sheet 40 provided on the seat cushion 12, and the electrode yarn 50 is easily cut when it is thin (for example, the outer diameter is less than 0.1 mm). . In addition, if the electrode thread 50 is thick (for example, if the outer diameter is about several millimeters), the passenger sitting on the seat cushion 12 may feel uncomfortable. On the other hand, in the seating sensor 30, the electrode yarn whose wire diameter (outer diameter) is in the range of 0.1 mm to 1.0 mm (0.1 mm or more and 1.0 mm or less) by metal deposition of the fiber yarn. 50 is used. Thereby, the seating sensor 30 does not cause an uncomfortable feeling to the occupant seated on the seat cushion 12 due to the electrode yarn 50 provided on the electrode seat 40. Therefore, the vehicle seat 10 can give the passenger a comfortable feeling of sitting comfort even if the seating sensor 30 is provided.

  Further, in the occupant detection device 28, a seat pan provided on the seat cushion 12 is used as the electrode portion 36. The seat pan has a position and shape that takes into account the seating comfort and the like of an occupant seated on the vehicle seat 10. The vehicle seat 10 is provided with a seating sensor 30 by using the seat pan as the electrode portion 36. Even in this case, the seat comfort of the seat cushion 12 is suppressed from changing. The occupant detection device 28 can eliminate the need for a dedicated electrode (second electrode) by using the seat pan as the electrode portion 36.

  On the other hand, FIG. 7 shows an outline of the change in accordance with the load in the seating sensor 30, in which the uppermost stage shows a state in which no load is input (hereinafter referred to as a no-load state), and is lower than the uppermost stage. The side shows a state in which the input loads are sequentially increased. In FIG. 7, the magnitude of the load is indicated by the thickness of the two-dot chain line arrow, and the thick arrow indicated by the two-dot chain line indicates that the input load is larger than the thin arrow. .

  The conductive pad 38 used for the seating sensor 30 is elastically compressed when a load is input. At this time, the displacement (thickness displacement) due to the elastic compression of the conductive pad 38 is determined by the load-displacement characteristic of the conductive urethane foam, but increases as the input load increases. Further, the conductive pad 38 has a predetermined resistance value (volume resistivity and thickness) between the electrode portions 34 and 36 as long as the electrode portions 34 and 36 are electrically connected even in a no-load state. Corresponding resistance value). Further, the electrical resistance value of the conductive pad 38 changes due to the displacement.

  As shown in the uppermost stage of FIG. 7, the electrode part 34 of the seating sensor 30 is provided with an insulating sheet 42 between the conductive pad 38 and the electrode sheet 40 on which the electrode yarn 50 is provided. For this reason, when the electrode portion 34 is in an unloaded state, the electrode yarn 50 is separated from the conductive pad 38 and is in an electrically non-connected state. Thereby, in the seating sensor 30, since the insulating sheet 42 is arrange | positioned between the electroconductive pad 38 and the electrode sheet 40 (electrode thread | yarn 50), the resistance value between the electrode parts 34 and 36 is very large. .

  Further, the insulating sheet 42 has a mesh shape in which openings 44 serving as openings are arranged, and small holes 44 </ b> A having openings smaller than the openings 44 are formed. A load is input to the conductive pad 38 via the electrode sheet 40 and the insulating sheet 42. At this time, the entire upper surface of the conductive pad 38 is pressed from the insulating sheet 42, but the force received by the region facing the opening 44 and the small hole 44A is lower than the force received by the surrounding area.

  Here, the conductive urethane foam forming the conductive pad 38 has a softness and a repulsive force, and when the load is input, if there is a difference in the input load, the input load The region with a large is deformed (depressed) more than the region with a small input load. Therefore, as shown in the second row from the top in FIG. 7, when the input load is relatively small, the conductive material that forms the conductive pad 38 in the opening 44 that is larger than the small hole 44A. A part of the surface layer portion of the porous urethane foam enters the opening 44, particularly, the inscribed circle 46 of the opening 44. Further, the electrode sheet 50 is pressed toward the insulating sheet 42 by the input load. As a result, the conductive pad 38 comes into contact with a part of the electrode yarn 50 facing the opening 44 in the opening 44 of the insulating sheet 42 and is electrically connected to the electrode yarn 50. Therefore, in the seating sensor 30, the resistance value between the electrode portions 34 and 36 is greatly reduced as compared with the case where no load is input. That is, in the seating sensor 30, when a load is input to the conductive pad 38, the resistance value between the electrode portions 34 and 36 is greatly reduced as compared to the case of no load.

  Further, when the input load increases, the conductive pad 38 contacts the electrode yarn 50 also at the peripheral portion of the opening 44 of the insulating sheet 42 and at the peripheral portion of the opening 44 outside the inscribed circle 46. Is done. Further, the conductive pad 38 enters the small hole 44A and comes into contact with the electrode yarn 50 facing the inscribed circle 46A which is a large opening portion in the small hole 44A. That is, the conductive urethane foam forming the conductive pad 38 enters the small hole 44A by its softness and repulsive force, and comes into contact with a part of the electrode yarn 50 on the upper side of the small hole 44A.

  Therefore, as shown in the third row from the top in FIG. 7, the conductive pad 38 that has entered the small hole 44 </ b> A of the insulating sheet 42 contacts the electrode yarn 50 that is positioned opposite the small hole 44 </ b> A. And are electrically connected. As a result, in the seating sensor 30, the displacement of the conductive pad 38 becomes larger than that in the case where the load is small, and the area of the electrode thread 50 that contacts the conductive pad 38 increases. Thereby, the change in the resistance value between the electrode portions 34 and 36 includes a change in the resistance value due to an increase in the contact area between the conductive pad 38 and the electrode yarn 50 in a change in the resistance value of the conductive pad 38. Join. Accordingly, the resistance value between the electrode portions 34 and 36 is further reduced as compared with the case where the load is small.

  Further, as shown in the lowermost stage of FIG. 7, when the input load further increases, the conductive pad 38 further enters the small hole 44 </ b> A formed in the insulating sheet 42. Therefore, the conductive pad 38 contacts the electrode yarn 50 at the peripheral edge of the small hole 44A. As a result, the displacement of the conductive pad 38 increases, the contact area between the conductive pad 38 and the electrode yarn 50 further increases, and the resistance value between the electrode portions 34 and 36 of the seating sensor 30 further decreases.

  Therefore, in the seating sensor 30, the contact area between the conductive pad 38 and the electrode yarn 50 changes according to the load, so that the resistance value between the electrode portions 34 and 36 is a resistance corresponding only to the displacement of the conductive pad 38. It changes greatly compared to the change in value.

  Here, FIGS. 8A and 8B show an example of the measurement result of the resistance value between the electrode portions 34 and 36 with respect to the displacement of the conductive pad 38 in the seating sensor 30 according to the present embodiment. ing. In FIG. 8A, the change in resistance value (resistance value R (Ω)) with respect to the displacement (mm) of the conductive pad 38 is shown in a diagram, and FIG. The measured value of the resistance value R (Ω) with respect to the displacement in the diagram (A) is shown in the chart. In addition, the resistance value and the load with respect to the displacement are measured three times. In FIGS. 8A and 8B, the first measurement result is N1, the second measurement result is N2, and 3 The result of the second measurement is indicated by N3. Further, in FIG. 8A, a change in the resistance value R with respect to the displacement of the conductive pad 38 as a comparative example is indicated by a two-dot chain line. In the comparative example, the insulating sheet 42 is removed from the seating sensor 30, that is, even when no load is input, the electrode yarn 50 of the electrode sheet 40 is applied to the conductive pad 38 on the substantially entire surface on the conductive pad 38 side. It is configured to be electrically connected.

  In the measurement, a conductive urethane foam having a hardness at IDL of 25% (hardness according to the apparent density hardness test D method of JIS K6401) of 220 N is used as the conductive pad 38 of the seating sensor 30. For the conductive pad 38, a sample having a length and width of 400 mm and a height (thickness) of 100 mm (400 mm × 400 mm × height 100 mm) is used. An iron seat pan provided on the seat frame of the seat cushion 12 is used for the electrode portion 36.

  In addition, the electrode portion 34 uses an electrode sheet 40 and an insulating sheet 42 having a size covering a sample of the conductive pad 38. The base 48 of the electrode sheet 40 is made of spandex, the electrode yarn 50 is made of polyethylene terephthalate (PET) fiber, and the electrode yarn 50 is silver-deposited yarn formed by twisting two polyethylene terephthalate fibers. Thus, the thickness (outer diameter) is 300 μm. Further, a staggered pattern 52 having a stitch interval ND = ND = 3 mm and a stitch width NW = NW = 3 mm is applied to the electrode sheet 40, and the electrode thread 50 is placed so that the stitches on the insulating sheet 42 side are substantially continuous. An electrode network 56 is formed by sewing into the substrate 48. The electrode network 56 is sewn into the substrate 48 so that the vertical and horizontal stitch intervals SD (SD1, SD2) are SD (= SD1 = SD2) = 3 cm.

  For the insulating sheet 42, a fabric using a polyester fiber (trade name: Tulle Mesh, model number # 2070, manufactured by Toray Industries, Inc.) is used. In the opening 44 of the insulating sheet 42, the inner diameter IDa of the inscribed circle 46 is IDa = 500 μm, and the inner diameter IDa of the inscribed circle 46 is larger than the outer diameter of the electrode yarn 50. The insulating sheet 42 is provided with a plurality of small holes 44A around the opening 44. The small holes 44A have an inner diameter IDb of the inscribed circle 46A that is slightly smaller than the outer diameter of the electrode yarn 50. Yes. Further, the insulating sheet 42 has a thickness T (pressure average thickness defined in JIS L1096) T of T = 250 μm.

  The insulating sheet 42 has a ratio of the area (opening area) of only the opening 44 per unit area as an opening ratio ε1, and a ratio of the area (opening area) of only the small holes 44A per unit area as an opening ratio ε2. The aperture ratio ε1 = 37.81% and the aperture ratio ε2 = 6.87%. The insulating sheet 42 has an opening ratio ε = 44.68 (= ε1 + ε2), where the ratio of the area of the opening 44 and the small hole 44A per unit area (unit area) is the opening ratio ε. Yes.

  In addition, when the average value of the inner diameter IDa of the inscribed circle 46 of the opening 44 and the inner diameter IDb of the inscribed circle 46A of the small hole 44A in the unit area is defined as the average diameter AID, the insulating sheet 42 has a thick average diameter AID. It is larger than T. At this time, in each of the openings 44, the inner diameter IDa of the inscribed circle 46 is larger than the average diameter AID, and in each of the small holes 44A, the inner diameter IDb of the inscribed circle 46A is smaller than the average diameter AID.

  For the aperture ratios ε, ε1, and ε2, a general method of counting the number of pixels on the image data obtained by imaging the target insulating sheet 42 and calculating from the counted number of pixels can be used. For imaging, a stereomicroscope (Leica M125C) capable of capturing images is used, and imaging is performed at an arbitrary magnification. The obtained image data is subjected to image processing such as rotation, inversion, trimming, contrast adjustment, etc. using general image processing software to clarify the shading. Cut out the image data for the aperture ratio calculation target area from the image data obtained in this way, paint the opening part black, and then convert the black part of the opening part and the white part of the fiber part to image data (See FIG. 4B), and then converted into bitmap data. The number of black and white pixels is counted from the bitmap data, and the number of pixels in the unit area, the number of pixels in the opening 44 in the unit area, and the number of pixels in the small holes 44A in the unit area are counted. The aperture ratios ε, ε1, and ε2 are calculated based on the obtained count values. The size of the opening 44 of the insulating sheet 42 (inner diameter IDa of the inscribed circle 46) and the size of the small hole 44A (inner diameter IDb of the inscribed circle 46A) are also acquired from the image data of the captured image of the insulating sheet 42. can do.

  In the comparative example, each of the electrode yarn 50 and the electrode portion 36 of the electrode portion 34 is in electrical contact with and electrically connected to the conductive pad 38 even in a no-load state. As a result, as shown in FIG. 8A, in the comparative example, a resistance value of the conductive pad 38 is generated between the electrode portions 34 and 36 even in a no-load state. Further, in the comparative example, when a load is input and a displacement occurs in the conductive pad 38, only the resistance value corresponding to the displacement of the conductive pad 38 is detected, so that the resistance value changes when the displacement changes. Is getting smaller.

  On the other hand, in the seating sensor 30, since the insulating sheet 42 is provided between the electrode yarn 50 and the conductive pad 38, the electrode yarn 50 and the conductive pad 38 of the electrode portion 34 are not loaded. Since the insulating sheet 42 is interposed therebetween, the resistance value between the electrode portions 34 and 36 is extremely high as compared with the comparative example.

  In the seating sensor 30, when a load is input to the conductive pad 38, a part of the electrode thread 50 corresponding to the opening 44 of the insulating sheet 42 is electrically connected to the conductive pad 38. . Thus, in the seating sensor 30, the conductive pad 38 and the electrode yarn 50 are electrically connected, and the resistance value between the electrode portions 34 and 36 is greatly reduced. Therefore, the ECU 32 can accurately determine whether or not a load is input from the change in the resistance value between the electrode portions 34 and 36, and the occupant detection device 28 determines whether or not the occupant is seated on the vehicle seat 10. Can be accurately detected.

  Further, in the seating sensor 30, when the load input to the conductive pad 38 through the electrode sheet 40 and the insulating sheet 42 of the electrode portion 34 increases, the conductive pad 38 (conductive urethane foam) increases with the load. Enters the opening 44 and also enters the small hole 44A. That is, the seating sensor 30 is provided with the opening 44 and the small hole 44A in the insulating sheet 42, so that when the load input to the conductive pad 38 increases, the conductive pad 38 becomes smaller than when the load is small. The area of the electrode yarn 50 in contact with increases.

  For this reason, in the seating sensor 30, the displacement of the conductive pad 38 increases as the input load increases, and the contact area of the electrode yarn 50 with the conductive pad 38 increases. Thereby, the seating sensor 30 has a larger change in the resistance value R with respect to the displacement of the conductive pad 38 than in the comparative example.

  On the other hand, in the seating sensor 30, the electrode sheet 40 and the insulating sheet 42 are overlapped, and the electrode sheet 40 may slightly shift with respect to the insulating sheet 42 when a load is input. For this reason, the position of the electrode yarn 50 with respect to each of the opening 44A and the small hole 44A of the insulating sheet 42 may be shifted, and when the position of the electrode yarn 50 with respect to each of the opening 44A and the small hole 44A is shifted, A change occurs in the contact area between the conductive pad 38 and the electrode yarn 50 with respect to the load.

  Here, in the seating sensor 30, the variation of the resistance value R with respect to the displacement from the first time to the third time is within 10%. The change in the resistance value R due to the displacement of the position of the electrode yarn 50 with respect to each of the opening 44A and the small hole 44A of the insulating sheet 42 is suppressed.

  Further, in the insulating sheet 42, the inner diameter IDa of the inscribed circle 46 of the opening 44 is larger than the outer diameter of the electrode yarn 50, and the inner diameter IDb of the inscribed circle 46A of the small hole 44A is outside the electrode yarn 50. It is smaller than the diameter. The insulating sheet 42 has a thickness T larger than the average diameter AID. Thereby, it is considered that the load input to the conductive pad 38 gradually increases, so that the conductive pad 38 and the electrode yarn 50 gradually come into contact with each other through the opening 44 and the small hole 44A. At this time, in the region where the input load is low, the opening 44 mainly contributes to the contact between the conductive pad 38 and the electrode yarn 50, and the conductive pad 38 contacts the electrode yarn 50 through the opening 44. Touched. In addition, in the region where the input load is high, the small holes 44A contribute to the increase in contact between the conductive pad 38 and the electrode yarn 50, and the conductive pad 38 and the electrode yarn 50 through the opening 44 are connected. Contact is made between the conductive pad 38 and the electrode yarn 50 via the small hole 44A.

  Thus, by making the thickness T of the insulating sheet 42 larger than the average diameter AID, the seating sensor 30 can increase the slope of the resistance value with respect to the displacement as compared with the comparative example. At this time, by appropriately combining the thickness T of the insulating sheet 42 and the average diameter AID, the resistance value range (change range) with respect to the displacement of the conductive pad 38 can be widened.

  Accordingly, the seating sensor 30 can widen the range of the resistance value with respect to the displacement of the conductive pad 38 and there is little variation in the resistance value with respect to the displacement. Therefore, the accuracy of determining the load input to the conductive pad 38 from the resistance value is improved. Can be improved. Further, the occupant detection device 28 using the seating sensor 30 can improve the detection accuracy when detecting the physique of the occupant seated on the vehicle seat 10.

  The design of the vehicle seat 10 may use an occupant dummy seated on the seat. The occupant dummy includes a child dummy and an adult dummy. The adult dummy includes an adult female dummy and an adult male dummy. May be used. A child dummy (P-6) corresponding to a 6-year-old child has a physique with a height of 120 cm and a weight of 22 kg. The adult female dummy (AF05) has a physique with a height of 145 cm and a weight of 45 kg, and the adult male dummy (AM50) has a physique with a height of 175 cm and a weight of 78 kg.

  FIG. 8A shows displacement amounts Ld1 to Ld3 of the conductive pad 38 when it is assumed that the dummy is seated on the vehicle seat 10. FIG. The displacement amount Ld1 corresponds to the displacement amount of the child dummy (9 mm), the displacement amount Ld2 corresponds to the displacement amount of the adult female dummy (34 mm), and the displacement amount Ld3 corresponds to the displacement amount of the adult male dummy (58 mm). It is supported.

  Here, in the seating sensor 30, the difference in resistance value R corresponding to each of the displacement amounts Ld1 to Ld3 is clear, and the resistance value R of the displacement amounts Ld1 to Ld3 divided into at least three stages is clearly identified. be able to. From this, by dividing the range of the displacement amount on the basis of the displacement amounts Ld1 to Ld3, it is possible to determine which range of the displacement amounts Ld1 to Ld3 the displacement amount belongs to from the resistance value R.

  As a result, the occupant detection device 28 using the seating sensor 30 is not in two stages of whether the occupant seated on the vehicle seat 10 is an adult or a child, but a child physique occupant, an adult female physique occupant, and an adult male Can be divided into three stages of occupants of the physique. Further, it is obvious that the occupant detection device 28 can identify the occupant's physique not only in three stages but also in a plurality of stages including four or more stages.

  As described above, the seating sensor 30 is configured such that the opening 44 is arranged between the electrode yarn 50 forming the first electrode and the conductive pad 38 to dispose the meshed insulating sheet 42. It is possible to accurately detect the load that causes displacement in the porous urethane foam. Further, by operating the occupant protection device according to the occupant's physique detected by the occupant detection device 28, the seated occupant is appropriately protected by the occupant protection device in the vehicle seat 10.

  At this time, the size of the opening 44 of the insulating sheet 42, the size of the small hole 44A, the opening ratios ε, ε1, ε2, the outer diameter of the electrode yarn 50, and the stitching pattern of the electrode yarn 50 are adjusted. By setting according to the softness and the repulsive force, the change width of the resistance value with respect to the change of the displacement of the conductive pad 38 can be set.

  When an infant is seated on the vehicle seat 10, an infant restraint device (CRS: Child Restraint System, hereinafter referred to as a child seat) called an infant assist device is attached to the vehicle seat 10. The resistance value detected by the ECU 32 is smaller when the child seat is attached to the vehicle seat 10 than when the child seat is not attached, and when the infant is placed on the child seat, the resistance value is reduced. Further decrease. By incorporating such an algorithm for detecting a change in resistance value into the ECU 32, it is possible to accurately determine that the infant is placed on the child seat mounted on the vehicle seat 10, and appropriate protection of the infant placed on the child seat is achieved. It becomes possible.

  In the present embodiment described above, the electrode yarn 50 obtained by vapor-depositing a conductive metal material on the fiber yarn is used as the conductive yarn. However, the conductive yarn is not limited to the electrode yarn 50. The conductive yarn may be a thread-like material carrying conductivity, may be a fiber yarn coated with metal, or formed by twisting a plurality of metal coated fiber yarns It may be. The conductive yarn may be a metal yarn formed by stretching a metal material into a thin line shape, or may be formed by twisting a plurality of metal yarns. Further, the conductive yarn may be formed by twisting a fiber yarn carrying conductivity and a non-conductive fiber yarn.

  Moreover, in this Embodiment demonstrated above, although the insulating sheet 42 was arrange | positioned between the electrode thread | yarn 50 and the electroconductive pad 38, not only this but the insulating sheet 42 is the electrode part 36, the electroconductive pad 38, You may arrange | position between. By providing the insulating sheet 42 between the electrode portion 36 and the conductive pad 38, the contact area of the electrode portion 36 with respect to the load input to the conductive pad 38 can be easily grasped, and a desired resistance value R for displacement can be obtained. It is easy to design a seating sensor to obtain changes.

  Furthermore, in the present embodiment, urethane foam is used as the elastic member for the cushion pad 20 and conductive urethane foam is used as the conductive elastic member for the conductive pad 38. The material of the conductive elastic member is not limited to this. As the elastic member, a known material used for the sheet can be applied, and as the conductive elastic member, it is preferable to apply an elastic member having conductivity to the elastic member used for the sheet.

  Further, in the present embodiment, the vehicle seat 10 is described as an example of the seat for seating, but the vehicle seat may be configured not to include a reclining mechanism. Moreover, the seat for seating is not limited to the seat for vehicles provided in the automobile, and can be applied to seats for seating provided in various vehicles such as railway vehicles. In addition, as a seat for seating, it is applied to any seat having cushioning properties such as a seat provided in various passenger equipment such as a ship, an aircraft, an amusement facility attraction, and a seat provided in an entertainment facility such as a movie theater. . In this embodiment, the load sensor is used as the seating sensor 30. However, the load sensor can be provided in any mechanism that receives a load, and the received load can be applied to the determination.

DESCRIPTION OF SYMBOLS 10 Vehicle seat 12 Seat cushion 20 Cushion pad 28 Crew detection device 30 Seating sensor (load sensor)
32 ECU (Load output section)
34 Electrode part 36 Electrode part (second electrode)
38 Conductive Pad (Conductive Elastic Member)
40 Electrode sheet 42 Insulating sheet (insulating sheet)
44 opening 44A small hole 46, 46A inscribed circle 48 body (stretch sheet)
50 Electrode thread (first electrode)
52 Staggered patterns 56, 58 Electrode network

Claims (6)

A conductive elastic member that is elastically compressed in accordance with an input load and changes an electrical resistance value between one surface in the load input direction and the surface opposite to the one surface;
An elastic sheet disposed on the one surface side of the conductive elastic member;
A first electrode provided facing the conductive elastic member side surface of the stretchable sheet;
A second electrode provided opposite to the surface opposite to the one surface of the conductive elastic member and electrically connected to the first electrode via the conductive elastic member;
A plurality of openings each having a predetermined size are arranged in a mesh shape, provided between the conductive elastic member and at least one of the first electrode and the second electrode, and elastically compressed to form the opening. An insulating sheet that allows the first electrode and the second electrode to be electrically connected via the conductive elastic member that enters the portion;
Load sensor with   The insulating sheet is provided with a plurality of small holes having openings smaller than the opening around the opening, and the elastic sheet is elastically compressed to enter the small holes through the conductive elastic member. The load sensor according to claim 1, wherein one electrode and the second electrode can be electrically connected.   The load sensor according to claim 1, wherein the first electrode is formed by sewing a conductive thread into the stretchable sheet. The load sensor according to any one of claims 1 to 3,
A load output unit that outputs a load input to the conductive elastic member based on an electrical resistance value between the first electrode and the second electrode;
A load detecting device including: A seat for seating provided with the load sensor according to any one of claims 1 to 3,
The conductive elastic member is provided on the cushion pad of the seat cushion,
The seat for seating in which the elastic sheet and the insulating sheet provided with the first electrode are arranged on the upper surface side of the seat cushion, and the second electrode is arranged on the lower surface side of the seat cushion.   The seat for seating of Claim 5 provided with the load output part which outputs the load input into the said seat cushion based on the electrical resistance value between a said 1st electrode and a said 2nd electrode.