Load detection sensor unit

A load detection sensor unit includes: a load detection sensor which includes a pair of electrodes facing each other with a predetermined gap interposed therebetween and a metal plate covering at least a part of one electrode; and a pressing member that includes a pressing portion pressed against a sheet cushion of a seat device and harder than the sheet cushion, and the pair of electrodes contacts each other when the metal plate is bent in a case in which the pressing portion presses a part of the metal plate.

TECHNICAL FIELD

The present invention relates to a load detection sensor unit suitable for appropriately detecting seating.

BACKGROUND ART

As one of safety systems in vehicles, an alarm system which indicates a seat belt non-wearing state when a person gets on the vehicle has been practically used. In this alarm system, a warning is generated when the wearing of the seat belt is not detected in a state where the seating of a person is detected. As a device for detecting the seating of the person, a seating detection device for detecting a load caused by seating is used in some cases.

As the seating detection device, there is known a load detection sensor having a configuration in which a spacer having an opening is disposed between a pair of resinous films and electrodes formed on the films face each other with a predetermined gap interposed therebetween inside the opening of the spacer. However, since the strength of the resinous film generally decreases in accordance with an increase in temperature, there is a tendency that the resinous film is bent by a weak force. Thus, there is a case in which the strength of the resinous film decreases as described above in a high-temperature environment such as a vehicle interior under a hot weather. In this case, even a case in which a load lighter than a normal person's load is applied to the seat device may be erroneously detected as seating.

Patent Literature 1 below discloses a seating detection device capable of suppressing the above-described erroneous detection. In a load detection sensor used in the seating detection device, a spacer having an opening is disposed between a pair of resinous films, electrodes respectively formed on the films face each other with a predetermined gap interposed therebetween inside the opening of the spacer, and a metal plate is disposed on a surface opposite to the spacer on one film to cover the opening.

According to the seating detection device, since the metal plate has elasticity and the elasticity does not change so much depending on the temperature, it is possible to suppress a change in bending of the film at the time of detecting seating with a temperature by the use of the metal plate. Thus, according to the seating sensor, it is possible to suppress a problem in which a load detecting seating changes in accordance with a temperature.

SUMMARY OF INVENTION

However, when the above-described metal plate is provided, there is concern that the film is not easily bent, the load detection unit is not easily turned on, and the seating is not easily detected compared to a case in which the metal plate is not provided. For this reason, there is a need to devise a load detection device which can be used in a seating detection device capable of suppressing an erroneous seating detection while appropriately detecting seating.

Here, an object of the invention is to provide a load detection sensor unit capable of suppressing an erroneous seating detection while appropriately detecting seating.

To solve the problem, the present invention is a load detection sensor unit which is disposed below a sheet cushion, including: a load detection sensor which includes a pair of electrodes facing each other with a predetermined gap interposed therebetween and a metal plate covering at least a part of one electrode located near the sheet cushion among the pair of electrodes from the sheet cushion; a pressing member that includes a pressing portion pressed against the sheet cushion of a seat device and harder than the sheet cushion, wherein the pair of electrodes contacts each other when the metal plate is bent in a case in which the pressing portion presses a part of the metal plate.

In such a load detection sensor unit, one electrode located near the sheet cushion is pressed by the bending of the metal plate pressed by the pressing portion and is brought into contact with the other electrode so that the switch is turned on. Incidentally, the flexibility of the metal does not change too much as described above even when a temperature changes. Thus, a bending way of the metal plate pressed by the pressing portion does not change even when an environment temperature around the load detection sensor unit changes. Thus, according to the load detection sensor unit, it is possible to suppress an erroneous seating detection even when an environment temperature changes. Further, in the load detection sensor unit, since the pressing portion which is harder than the sheet cushion presses a part of the metal plate, the metal plate can be appropriately bent compared to a case in which the sheet cushion directly presses the metal plate and thus the seating can be appropriately detected. Further, since creep hardly occurs in metal compared to a resin, the metal plate is not pressed even when a part thereof is pressed by the pressing member. Thus, according to the load detection sensor unit of the invention, it is possible to suppress an erroneous seating detection due to pressing or the like while appropriately detecting seating.

Furthermore, it is preferable that the pressing member further includes a pressure receiving surface pressed against the sheet cushion, and an area of the pressure receiving surface is larger than an area in which the pressing portion contacts the metal plate.

Since the area of the pressure receiving surface pressed against the sheet cushion is larger than the area of the pressing portion contacting the metal plate, a pressing force received in a wide surface can concentrate on the pressing portion and thus the metal plate can be more appropriately bent. Thus, the seating can be more appropriately detected.

In this case, it is preferable that the area of the pressure receiving surface is larger than an area of the one electrode.

Since the area of the pressure receiving surface is larger than the area of the electrode pressed by the pressing portion, the sheet cushion can transmit a force to the pressure receiving surface from a position other than a position directly above the electrode. For this reason, since a pressing force can more appropriately concentrate on the pressing portion, the metal plate can be more appropriately bent. As a result, the seating can be more appropriately detected.

Furthermore, it is preferable that the pressing portion contacts the metal plate while not being pressed against the sheet cushion.

Since the pressing portion contacts the metal plate while not being pressed against the sheet cushion, the pressing portion can promptly press the metal plate when the sheet cushion presses the pressing member. Thus, the seating can be promptly detected.

Furthermore, it is preferable that a first movement regulation member that regulates a relative movement between the pressing member and the metal plate in a plane direction of the metal plate is further included.

Since the relative positional deviation between the pressing portion and the metal plate is suppressed by the first movement regulation member, it is possible to suppress a problem in which the pressing portion presses a portion other than the metal plate.

Furthermore, it is preferable that the load detection sensor further includes a sheet-shaped spacer having an opening formed therein and a pair of insulation sheets formed on both surfaces of the spacer, the pair of electrodes is provided on a surface near the spacer in the insulation sheet and faces each other with the opening interposed therebetween, and the metal plate is provided at the opposite side to the spacer of the one insulation sheet.

In this case, the insulation sheet and the electrode on the insulation sheet are pressed by the bending of the metal plate pressed by the pressing portion and thus the electrodes contact each other. According to such a load detection sensor unit, since the electrode is provided on the insulation sheet, it is possible to suppress an unnecessary short-circuit between the electrode and other conductive members. Further, since the bending way of the metal plate does not change too much as described above even when the flexibility of the insulation sheet changes in accordance with a change in temperature, it is possible to suppress an erroneous seating detection due to a temperature.

Furthermore, it is preferable that the pair of insulation sheets and the metal plate do not adhere to each other.

In general, the insulation sheet and the metal plate have different thermal expansion coefficients. Thus, a partial position of the insulation sheet and a partial position of the metal plate are apt to be deviated from each other when a temperature changes. In this case, there is concern that an unnecessary stress is applied to the electrode on the insulation sheet when the insulation sheet and the metal plate adhere to each other. However, when the insulation sheet and the metal plate do not adhere to each other, it is possible to suppress a problem in which an unnecessary stress is applied to the electrode as described above even when the insulation sheet and the metal plate expand at different expansion coefficients due to a change in temperature.

In this case, it is preferable that a movement regulation member that regulates a relative movement between the pair of insulation sheets and the metal plate in a plane direction of the pair of insulation sheets is further included.

According to such a configuration, it is possible to suppress a problem in which the metal plate does not cover the electrode due to a positional deviation between the metal plate and the insulation sheet by the use of the movement regulation member.

Furthermore, it is preferable that the movement regulation member is a part of a housing accommodating the load detection sensor.

There is a case in which the load detection sensor unit includes a housing. In this case, the load detection sensor is used while being accommodated inside the housing. Thus, since a part of the housing becomes the movement regulation member, there is no need to provide a separate movement regulation member in addition to the housing. Thus, the load detection sensor unit can have a simple configuration when the load detection sensor unit includes the housing.

Further, when the pair of insulation sheets is used as described above, it is desirable that a portion which covers at least the electrode in the metal plate be separated from the insulation sheet.

Since the metal plate is separated from the insulation sheet, it is possible to suppress the contact of the electrode due to a slight bending of the metal plate. Thus, it is possible to suppress a problem in which seating is detected by the arrangement of a baggage on a seat surface.

In this case, it is preferable that the metal plate is formed of bimetal which is deformed to be separated from the electrode in accordance with an increase in temperature.

Generally, when the insulation sheet is formed of a resin and the electrode is formed on the resinous insulation sheet, the insulation sheet is deformed by a weak force in accordance with an increase in temperature so that the electrodes easily contact each other due to a feature that the resin is easily defamed in accordance with an increase in temperature. Here, since the metal plate is formed of bimetal which is deformed to be separated from the electrode in accordance with an increase in temperature as described above, the electrodes easily contact each other at a weak force as described above when the temperature increases. Accordingly, it is possible to suppress a change in seating detection in that the metal plate is separated from the electrode so that the metal plate cannot easily press the insulation sheet. Thus, the seating can be more appropriately detected.

Furthermore, the one electrode covered by the metal plate may be integrated with the metal plate and the electrode is a part of the metal plate.

As described above, according to the invention, a load detection sensor unit capable of suppressing an erroneous seating detection while appropriately detecting seating is provided.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of a load detection sensor unit according to the invention will be described in detail with reference to the drawings. For comprehension, the scale of each drawing may be different from the scale described in the following description.

FIG. 1is an exploded view illustrating a configuration of a load detection sensor unit of an embodiment andFIG. 2is a cross-sectional view illustrating a state where the load detection sensor unit is attached to an S spring of a seat device. Additionally,FIG. 2is a cross-sectional view of the load detection sensor unit in a plane along the left and right direction of the seat device. As illustrated inFIGS. 1 and 2, a load detection sensor unit1A mainly includes a pedestal2A, a housing3A, a housing cover4A, and a load detection sensor5A.

The pedestal2A includes a placement portion21on which the housing3A is placed and a pair of hook portions22which is connected to the placement portion21. An upper surface of the placement portion21is formed as a placement surface21S on which the housing3A is placed. Further, the placement portion21is provided with a plurality of penetration holes23which are formed from the placement surface21S to a lower surface of the placement portion21(a surface opposite to the placement surface21S) to penetrate the surfaces. The pedestal2A is formed by molding, for example, a metal plate. In this case, a plate thickness is, for example, 0.8 mm.

The pair of hook portions22is respectively provided at positions facing each other with the placement portion21interposed therebetween and is respectively fitted to the pair of adjacent S springs100in the plurality of S springs100stretched across the opening of the frame of the seat device of the vehicle. Thus, each of the hook portions22is a locking portion which locks the pedestal2A to the S spring100. In the embodiment, the pair of hook portions22is arranged in the lateral direction of the seat device and is fitted into the pair of S springs100which is adjacent to each other in the lateral direction. Further, in a state where the pair of hook portions22is fitted to the pair of adjacent S springs100, the placement portion21is located below the sheet cushion SC placed on the plurality of S springs100and the placement portion21is disposed between the pair of S springs100when the plurality of S springs are viewed from above. As described above, in the embodiment, the placement surface21S is located below a lower end of each of the S springs100while the pair of hook portions22is fitted into the pair of S springs100.

As illustrated inFIGS. 1 and 2, the housing3A includes a connector portion31which is connected to a vehicle control unit (not illustrated) and a switch accommodation portion32which is connected to the connector portion31. The switch accommodation portion32includes a bottom wall37and a frame wall38and an accommodation space CA which accommodates the load detection sensor5A is formed by the bottom wall37and the frame wall38. Additionally, in the embodiment, the frame wall38is subjected to drawing in order to suppress deformation during resin molding.

The bottom wall37of the switch accommodation portion32is provided with a pair of fixing pins33and a pair of connection pins34. The pair of fixing pins33corresponds to pins for fixing the load detection sensor5A accommodated in the housing3A. Further, the pair of connection pins34corresponds to pins which are respectively electrically connected to the connector terminal of the connector portion31and the load detection sensor5A so that the connector terminal is electrically connected to the load detection sensor5A. Additionally, inFIG. 1, the connector terminal of the connector portion31is not illustrated.

A pair of protrusion pieces35is provided on the outer surface of the frame wall38of the switch accommodation portion32. In the embodiment, the pair of protrusion pieces35is provided to be lined up in the lateral direction of the seat. Further, a lower end of the frame wall38is provided with a plurality of hook pieces36respectively fitted into the penetration holes23of the pedestal2A. When each hook piece36is fitted into each penetration hole23of the pedestal2A, the housing3A is fixed to the pedestal2A so that the housing3A is placed on the placement surface21S of the pedestal2A as described above.

The housing cover4A is a lid member that covers the accommodation space CA of the switch accommodation portion32and is a pressing member that is pressed against the sheet cushion SC to press the switch of the load detection sensor5A. The housing cover4A includes a top wall44and a frame wall48a.A pair of arms41is provided in a lower end of the frame wall48aof the housing cover4A. Each arm41is provided with an opening42through which a protrusion piece35provided in the frame wall38of the switch accommodation portion32of the housing3A is fitted. When the pair of protrusion pieces35of the housing3A is respectively fitted into the openings42of the pair of aims41, the housing cover4A is locked to the housing3A. Thus, the pair of aims41sandwiches the housing3A from the lateral direction of the seat while the housing cover4A is locked to the housing3A.

The top wall44of the housing cover4A is provided with a pressing portion43which protrudes from an inner surface facing the bottom wall37of the switch accommodation portion32of the housing3A. A front end of the pressing portion43is formed in a protruding curved surface shape and the front end thereof contacts the switch of the load detection sensor5A while the housing cover4A covers the housing3A and each protrusion piece35is fitted into each opening42. That is, the front end of the pressing portion43contacts the switch of the load detection sensor5A while the housing cover4A is not pressed against the sheet cushion SC as described below.

Additionally, the housing cover4A is formed of a material which is harder than the sheet cushion SC. Thus, the pressing portion43which is a part of the housing cover4A is also formed of a material harder than the sheet cushion SC. Generally, since the sheet cushion SC is formed of a foamed urethane resin, polycarbonate (PC), polyamide (PA), polybutylene terephthalate (PBT), phenol resin, epoxy resin, and the like can be exemplified as a material of the housing cover4A.

In this way, the top wall44of the housing cover4A and the frame wall38of the housing3A are separated from each other to form a gap GA as illustrated inFIG. 2in a state where the pressing portion43of the housing cover4A contacts the load detection sensor5A.

In a state where the load detection sensor unit1A assembled in this way is attached to the pair of S springs100, the top surface44S of the top wall44of the housing cover4A faces the lower surface of the sheet cushion SC with a predetermined distance interposed therebetween. The top surface44S is formed in a flat surface shape. The top surface44S is a surface which is pressed by the sheet cushion SC and can be understood as a pressure receiving surface of the load detection sensor unit1A. The area of the top surface44S is set to be larger than an area in which the pressing portion43contacts the switch of the load detection sensor5A.

Next, the load detection sensor5A which is accommodated in the switch accommodation portion32of the housing3A will be described.

FIG. 3is an exploded view illustrating a configuration of the load detection sensor5A. Further,FIG. 4is a cross-sectional view taken along a line X-X of the load detection sensor5A illustrated inFIG. 3andFIG. 5is a cross-sectional view taken along a line Y-Y of the load detection sensor5A illustrated inFIG. 3.

As illustrated inFIGS. 3 to 5, the load detection sensor5A mainly includes a first electrode sheet50, a second electrode sheet60, and a spacer70.

The first electrode sheet50includes, for example, an insulation substrate51having little flexibility. As a material of the substrate51, a phenol resin, an epoxy resin, and the like can be exemplified. A first electrode52and a first contact point53are disposed on one surface F1facing the second electrode sheet60in the substrate51.

The first electrode52is an electrode which constitutes the switch SW and is formed as, for example, a circular metal printed layer. Further, the first contact point53includes a substantially rectangular contact area AR1which contacts the second electrode sheet60and a non-contact area AR2which does not contact the second electrode sheet60, the two areas being connected to each other.

The other surface F2which is opposite to one surface F1in the substrate51is formed as a lower surface of the load detection sensor5A and a resistance54is disposed on the other surface F2. The resistance54is a resistance for detecting a short-circuit and in the embodiment, the resistance54is configured as a chip resistance.

The substrate51is provided with a plurality of penetration holes which are formed from one surface F1to the other surface F2of the substrate51to penetrate the surfaces and the holes are a first sheet penetration hole55A, a second sheet penetration hole55B, fixing penetration holes55C and55D, and pin penetration holes55E and55F.

The first sheet penetration hole55A is a sheet penetration hole in which an opening is located within an area where the first electrode52is disposed in one surface F1of the substrate51. A first conductive member CPA is provided inside the first sheet penetration hole55A and the first electrode52is electrically connected to a circuit portion which is disposed on the other surface F2of the substrate51through the first conductive member CPA. Accordingly, the first conductive member CPA and the resistance54are electrically connected to each other, so that the first electrode52and the resistance54are electrically connected to each other. Further, the first conductive member CPA is provided on an inner peripheral surface of the first sheet penetration hole55A and an air hole SP which is surrounded by the first conductive member CPA is formed inside the first sheet penetration hole55A.

The second sheet penetration hole55B is a sheet penetration hole in which an opening is located within an area where the first contact point53is disposed on one surface F1of the substrate51. In the embodiment, the opening of the second sheet penetration hole55B is located within the non-contact area AR2of the first contact point53.

A second conductive member CPB is charged into the second sheet penetration hole55B. The circuit portion disposed on the other surface F2of the substrate51and the non-contact area AR2of the first contact point53are electrically connected to each other through the second conductive member CPB and the second conductive member CPB is connected to the resistance54on the other surface F2of the substrate51. Thus, the resistance54and the first contact point53are electrically connected to each other. Since the first electrode52and the resistance54are electrically connected to each other as described above, the first electrode52, the resistance54, and the first contact point53are electrically connected in series to one another in this order.

The fixing penetration holes55C and55D are penetration holes through which the pair of fixing pins33provided in the bottom wall37of the switch accommodation portion of the housing3A is inserted. The diameters of the fixing penetration holes55C and55D are set to be substantially equal to the outer diameters of the pair of fixing pins33.

The pin penetration holes55E and55F are penetration holes through which the pair of connection pins34provided in the housing3A is inserted. A terminal55T which is one terminal portion of an electric circuit of the load detection sensor5A is provided inside the pin penetration hole55E and a terminal55S which is the other terminal portion of the electric circuit of the load detection sensor5A is provided inside the pin penetration hole55F. The terminal55T is electrically connected to a contact point between the first electrode52and the resistance54and the terminal55S is electrically connected to a contact point between the resistance54and the first contact point53. Further, the terminals55T and55S are provided along inner peripheral surfaces of the corresponding pin penetration holes55E and55F and a width of a space which is surrounded by the terminals55T and55S is set to be substantially equal to the outer diameter of the connection pin34. When the pair of connection pins34is inserted through the pin penetration holes55E and55F, the terminal55T is electrically connected to one connection pin34and the terminal55S is electrically connected to the other connection pin34.

The second electrode sheet60is formed of a metal plate61and mainly includes a second electrode62and a second contact point63.

The metal plate61is formed of thin metal having flexibility and is formed, in the embodiment, in a thin cuboid shape which has a vertical width shorter than the vertical width of the substrate51and a horizontal width equal to the horizontal width of the substrate51. The material of the metal plate61is not particularly limited as long as metal has conductivity. For example, copper or stainless steel can be exemplified.

The metal plate61is provided with fixing penetration holes65C and65D which are formed from one surface to the other surface of the metal plate61so as to penetrate the surfaces. The fixing penetration holes65C and65D are penetration holes through which the pair of fixing pins33provided in the bottom wall of the switch accommodation portion of the housing3A is inserted and are formed to have the same shape and size as those of the fixing penetration holes55C and55D formed in the substrate51of the first electrode sheet50. Further, the arrangement portions of the second electrode62and the second contact point63with respect to the fixing penetration holes65C and65D and the arrangement portions of the first electrode52and the first contact point53with respect to the fixing penetration holes55C and55D of the first electrode sheet50have the same positional relation. When the first electrode sheet50and the metal plate61overlap each other, the fixing penetration hole55C and the fixing penetration hole65C overlap each other and the fixing penetration hole55D and the fixing penetration hole65D overlap each other.

The second electrode62is the other electrode which constitutes the switch SW and in the embodiment is formed as a portion which faces the first electrode52through the spacer70in the metal plate61. That is, a part of the metal plate61serves as the second electrode62. Thus, as illustrated inFIGS. 1 and 2, the second electrode62located near the sheet cushion SC among the first electrode52and in the second electrode62is covered by the metal plate61from the sheet cushion and can be understood that the electrode is integrated with the metal plate61as described above. Additionally, for example, a metal layer formed of a material which is the same as or different from the metal plate61may be disposed as the second electrode62at a portion facing the first electrode52through the spacer70in the metal plate61.

The second contact point63is one member that constitutes a connection maintaining portion AP and in the embodiment formed as a leaf spring. That is, the metal plate61is provided with a pair of notches61A and61B (FIG. 1) which extends from one end to the other end of the metal plate61so as to be separated from each other by a predetermined distance and a portion which is interposed between the notches61A and61B is formed as the second contact point63. Further, the second contact point63is formed as a leaf spring in such a manner that a base of the second contact point63is bent toward the first electrode sheet50so that the second contact point63is inclined with respect to a plate surface of the metal plate61. In this way, a portion which is different from the portion formed as the second electrode62in the metal plate61is formed as the second contact point63. A position of the second contact point63is set to a position overlapping the contact area AR1of the first contact point53when the first electrode sheet50and the second electrode sheet60overlap each other. Additionally, a shape of the leaf spring formed as the second contact point63may be, for example, a trapezoidal shape in which a width of a base is larger than a width of an opening end or various shapes other than a rectangle and a trapezoid are applicable. Further, a metal layer formed of a material which is the same as or different from the metal plate61may be formed as the second contact point63on the side of the first electrode sheet50in the metal plate61.

The spacer70is a thin insulation member that is interposed between the first electrode sheet50and the second electrode sheet60and in the embodiment is formed to have the same shape and size as those of a portion in which the second contact point63is removed from the metal plate61. As a material of the spacer70, a resin such as PET, PI, or PEN can be exemplified.

An opening71is formed in the spacer70. The opening71is formed at a position overlapping the first electrode52and the second electrode62in the vertical direction between the first electrode52disposed on the substrate51and the second electrode62of the metal plate61facing the first electrode52. The size of the opening71is set to be slightly smaller than the size of the first electrode52.

Further, the spacer70is provided with a slit-shaped opening72. The opening72is formed at a position overlapping the first contact point53and the second contact point63in the vertical direction between the first contact point53disposed on the substrate51and the second contact point63of the metal plate61facing the first contact point53. The size of the opening72is set to be slightly larger than the size of the leaf spring formed as the second contact point63in the metal plate61.

Further, the spacer70is provided with fixing penetration holes75C and75D which are formed from one surface to the other surface of the spacer70to penetrate the surfaces. The fixing penetration holes75C and75D are penetration holes through which the fixing pins33provided in the bottom wall of the switch accommodation portion of the housing3A are inserted and are formed to have the same and size as those of the fixing penetration holes55C and55D formed in the substrate51of the first electrode sheet50. Further, the arrangement portions of the opening71and the opening72with respect to the fixing penetration holes75C and75D of the spacer70and the arrangement portions of the first electrode52and the first contact point53with respect to the fixing penetration holes55C and55D of the first electrode sheet50have the same positional relation. Thus, when the first electrode sheet50, the spacer70, and the second electrode sheet60overlap one another, the fixing penetration hole55C, the fixing penetration hole65C, and the fixing penetration hole75C overlap one another and the fixing penetration hole55D, the fixing penetration hole65D, and the fixing penetration hole75C overlap one another.

The first electrode sheet50, the second electrode sheet60, and the spacer70overlap one another to form the load detection sensor5A. In the load detection sensor5A, as illustrated inFIG. 4, the first electrode52and the second electrode62face each other with the opening71interposed therebetween to form the switch SW. In a state where the first electrode52and the second electrode62are separated from each other, a distance between the first electrode52and the second electrode62is set to, for example, 0.1 mm. Then, the air hole SP formed inside the electrode penetration hole52A communicates with the opening71. Thus, unnecessary air can be discharged from the air hole SP to the outside of the load detection sensor5A when the second electrode62is bent to contact the first electrode52. In this way, the first sheet penetration hole55A serves as a hole used to electrically connect the first electrode52disposed on one surface F1of the substrate51and the circuit portion disposed on the other surface F2and also serves as an exhaust hole discharging air inside the opening71to the outside of the load detection sensor5A.

Further, as described above, in the load detection sensor5A, the second contact point63of the second electrode sheet60is formed as the leaf spring and is plastically deformed with respect to the plate surface of the metal plate61to be inclined normally. For this reason, as illustrated inFIG. 5, the second contact point63passes through the opening72formed as the notch of the spacer70and is connected to the contact area AR1of the first contact point53of the first electrode sheet50. In this way, the connection maintaining portion AP is formed when the first contact point53and the second contact point63contact each other. That is, the first contact point53of the first electrode sheet50is one member that forms the connection maintaining portion AP maintaining an electrical connection even when an external pressure is not applied to the housing cover4A and the second contact point63of the second electrode sheet60is formed as the other member foaming the connection maintaining portion AP.

Such a load detection sensor5A is fixed to the housing3A as illustrated inFIG. 1in such a manner that the pair of fixing pins33of the housing3A is inserted through the fixing penetration holes55C and55D of the first electrode sheet50, the fixing penetration holes75C and75D of the spacer70, and the fixing penetration holes65C and65D of the second electrode sheet60in this order.

In a state where the load detection sensor5A is fixed to the housing3A, the pair of connection pins34is respectively inserted into the pin penetration holes55E and55F of the first electrode sheet50. Accordingly, the terminals55T and55S provided inside the pin penetration holes55E and55F contact the corresponding connection pins34and are electrically connected to the connector terminal of the connector portion31of the housing3A through the connection pin34.

Further, a front end of the pressing portion43contacts a position opposite to the first electrode52of the second electrode62in the switch SW by the attachment of the housing cover4A. An area in which the pressing portion43contacts the second electrode62is smaller than an area of the second electrode62and an area of the top surface44S corresponding to the pressure receiving surface is larger than an area of the second electrode62. In this way, a relative movement between the housing cover4A and the load detection sensor5A in the plane direction of the metal plate61is regulated while the load detection sensor5A is fixed to the housing3A and the housing cover4A is attached thereto. The regulation of the relative movement is performed in such a manner that the pair of fixing pins33regulates the movement of the load detection sensor5A with respect to the housing3A and the pair of aims41regulates the movement of the housing cover4A with respect to the housing3A in the horizontal direction. Thus, in the embodiment, the pair of fixing pins33and the pair of aims41constitute a first movement regulation member that regulates the relative movement between the housing cover4A and the metal plate61in the plane direction of the metal plate61.

FIG. 6is a diagram illustrating an equivalent circuit of the load detection sensor5A fixed to the housing3A. As illustrated inFIG. 6, the switch SW (the first electrode52and the second electrode62) and the connection maintaining portion AP (the first contact point53and the second contact point63) are connected to each other between the pair of terminals55T and55S which corresponds to circuit terminals of the load detection sensor5A. The switch SW is electrically connected between the pair of terminals55T and55S and is connected to the connector terminal provided in the connector portion31of the housing3A through the pair of terminals55T and55S. Further, since the resistance54is electrically connected to the first electrode52and the first contact point53as described above, the resistance54is electrically connected in parallel to the switch SW. Thus, when the switch SW is turned on, a resistance value between the terminals55T and55S is lower than that of a case in which the switch SW is turned off.

Next, a case in which seating is detected by the load detection sensor unit1A of the embodiment will be described.

When a person sits on the seat device, the lower surface of the sheet cushion SC moves downward by the weight of the person and the lower surface of the sheet cushion SC contacts the top surface44S of the housing cover4A. When the lower surface of the sheet cushion SC moves further downward, the lower surface of the sheet cushion SC presses the top surface44S of the housing cover4A. Then, since the gap GA is formed between the housing cover4A and the housing3A as described above when the lower surface of the sheet cushion SC moves further downward, the housing cover4A moves downward within the range of the gap GA.

FIG. 7is a diagram illustrating a state where the load detection sensor5A is turned on. The front end of the pressing portion43presses the second electrode62by the downward movement of the housing cover4A and then the second electrode62contacts the first electrode52so that the switch SW of the load detection sensor5A is turned on as illustrated inFIG. 7. That is, the second electrode62contacts the first electrode52by the bending of the metal plate61when the pressing portion43presses the metal plate61. For this reason, a resistance value between the pair of terminals55T and55S decreases and a change in resistance is detected by a vehicle control unit (not illustrated) through the connection pin34and the connector terminal. In this way, the seating is detected.

At this time, since an area of the top surface44S corresponding to the pressure receiving surface pressed against the sheet cushion SC is set to be larger than an area of a portion contacting the second electrode62corresponding to the front end of the pressing portion43as described above, a pressing force received in a wide surface can concentrate on the pressing portion43and thus the metal plate61can be appropriately bent. Particularly, in the embodiment, since the front end of the pressing portion43is formed in a protruding curved surface shape, a pressing force can be applied to the metal plate61at a higher density compared to a case in which the front end of the pressing portion43is formed in a flat surface shape and thus the metal plate61can be bent more appropriately. Further, since an area of the top surface44S is larger than an area of the second electrode62as described above, the sheet cushion SC can apply a force from a position except for a position directly above the second electrode62to the top surface44S. For this reason, since a pressing force can more appropriately concentrate on the pressing portion43, the metal plate61can be more appropriately bent.

As described above, in the load detection sensor unit1A of the embodiment, the second electrode62is formed as a portion facing the first electrode52in the metal plate61and a part of the metal plate61serves as the second electrode62. Incidentally, the flexibility of the metal does not change much even when a temperature changes. Thus, a bending way of the metal plate61pressed against the pressing portion43does not change much even when an environment temperature around the load detection sensor unit1A changes. Thus, according to the load detection sensor unit1A, an erroneous seating detection can be suppressed even when the environment temperature changes. Further, in the load detection sensor unit1A, since the pressing portion43which is harder than the sheet cushion SC presses a part of the metal plate61, the metal plate61can be appropriately bent compared to a case in which the sheet cushion SC directly presses the metal plate61and thus the seating can be appropriately detected. Further, since creep hardly occurs in metal compared to a resin, the metal plate61is not pressed even when a part thereof is pressed by the pressing portion43. Thus, according to the load detection sensor unit1A of the invention, it is possible to suppress an erroneous seating detection due to pressing or the like while appropriately detecting the seating.

Further, in the embodiment, the front end of the pressing portion43contacts the metal plate61while the top surface44S of the housing cover4A is not pressed against the sheet cushion SC as described above. Thus, the pressing portion43can promptly press the metal plate61when the sheet cushion SC presses the housing cover4A corresponding to the pressing member. Thus, the seating can be promptly detected.

Further, in the embodiment, the first movement regulation member that includes the pair of fixing pins33and the pair of auras41and regulates the relative movement between the housing cover4A and the metal plate61in the plane direction of the metal plate61is provided as described above. Thus, since it is possible to suppress the relative positional deviation between the pressing portion43and the metal plate61, it is possible to suppress the pressing portion43from pressing a portion other than the metal plate61.

Further, in the load detection sensor5A of the embodiment, a portion including the second contact point63in the second electrode sheet60is formed as a leaf spring which is formed by bending the metal plate61and presses the second contact point63against the first contact point53. For this reason, other members that normally maintain the connection state between the first contact point53and the second contact point63cannot be needed. Thus, it is possible to suppress an increase in the number of components and a decrease in size.

Next, a second embodiment of the invention will be described. Additionally, in the description of the embodiment, the same reference numerals will be given to the components which are the same as or equivalent to those of the first embodiment and a repetitive description thereof will be omitted unless otherwise specified.

FIG. 8is an exploded view illustrating a configuration of a load detection sensor unit according to the second embodiment of the invention andFIG. 9is a diagram illustrating the load detection sensor unit ofFIG. 8when viewed from a different angle. Further,FIG. 10is a cross-sectional view of the load detection sensor unit ofFIGS. 8 and 9. As illustrated inFIGS. 8 to 10, a load detection sensor unit1B of the embodiment mainly includes a housing3B, a housing cover4B, and a load detection sensor5B. Additionally, a pedestal is not described inFIGS. 8 to 10, but in the embodiment the load detection sensor unit1B may not include the pedestal.

As illustrated inFIGS. 8 and 9, the housing3B includes a bottom wall87, a plurality of frame walls88, and a plurality of arms81. The bottom wall87is formed in a substantially circular plate shape and the frame walls88are connected to three positions on the outer periphery of the bottom wall87. The frame wall88is formed so that an outer shape has the substantially same shape as that of the outer periphery of the bottom wall87and an inner shape is formed in a flat surface shape. Further, the bottom wall87is provided with a plurality of penetration holes30H.

The frame walls88are disposed at the interval of 90° about the substantial center of the substantially circular bottom wall87, the inner surfaces of the adjacent frame walls88form an angle of 90°, and the inner surfaces89of the facing frame walls88face each other. The inner surfaces89are substantially parallel to any one of lines connecting the centers of the adjacent penetration holes30H. Further, the arm81is connected to the outer periphery of each frame wall88. An opening82is formed in each arm81by punching. Further, the frame wall88and the arm81are formed at three positions in the embodiment and are not provided in a direction in which the load detection sensor unit1B extends.

The housing cover4B is a lid member that covers the bottom wall87and the frame wall88and is a pressing member that is pressed against the sheet cushion SC illustrated inFIG. 10to press the switch of the load detection sensor5B. The housing cover4B includes a top wall45and a frame wall48b.The top wall45is a substantially circular plate-shaped member. Further, the frame wall48bof the housing cover4B is divided into a plurality of parts and is connected to the outer peripheral shape of the top wall45. The hook piece47is connected to the top wall45between the plurality of divided frame walls48b.Each hook piece47is fitted into the opening82formed in the arm81of the housing3B. When each hook piece47is fitted into the opening82, the relative movement between the housing3B and the housing cover4B in the plane direction of the bottom wall87or the top wall45is regulated.

The top wall45of the housing cover4B is provided with a pressing portion46which protrudes from the inner surface facing the bottom wall87of the housing3B. The pressing portion46is formed in the same shape as that of the pressing portion43of the first embodiment except that the front end is formed in a flat surface shape, but the front end may be formed in a protruding curved surface shape. Further, the top wall45of the housing cover4B is provided with a plurality of ribs49which protrude from an inner surface on the same side as the installation side of the pressing portion46. These ribs49are formed at positions overlapping the plurality of penetration holes30H formed in the bottom wall87of the housing3B. These ribs49are respectively inserted into the penetration holes30H while the housing cover4B covers the housing3B and each hook piece47is fitted into each opening82. Further, a front end of the pressing portion46contacts the load detection sensor5B in this state. Thus, similarly to the pressing portion43of the first embodiment, the front end of the pressing portion46contacts the switch of the load detection sensor5B while the housing cover4B is not pressed against the sheet cushion SC as below.

Additionally, even in the embodiment, the housing cover4B is formed of a material harder than the sheet cushion SC similarly to the first embodiment and the pressing portion46which is a part of the housing cover4B is also formed of a material harder than the sheet cushion SC. Thus, the housing cover4B of the embodiment is formed of the same material as that of the housing cover4A of the first embodiment.

In this way, the top wall45of the housing cover4B and the frame wall88of the housing3B are separated from each other to form the gap GA as illustrated inFIG. 10while the pressing portion46of the housing cover4B contacts the load detection sensor5B.

In a state where the load detection sensor unit1A assembled in this way is disposed below the sheet cushion SC of the seat device, a top surface45S of the top wall45of the housing cover4B faces the lower surface of the sheet cushion SC with a predetermined distance interposed therebetween. The top surface45S is formed in a flat surface shape. The top surface45S is a surface which is pressed against the sheet cushion SC and can be understood as the pressure receiving surface of the load detection sensor unit1B. An area of the top surface45S is set to be larger than an area in which the pressing portion46contacts the load detection sensor5B.

Next, the load detection sensor5B of the embodiment will be described.

FIG. 11is an exploded view illustrating the load detection sensor5B ofFIGS. 8 and 9. Here, the viewing directions ofFIGS. 8, 9 and 11are changed in order to help the comprehension. As illustrated inFIGS. 8 to 11, the load detection sensor5B of the embodiment includes a switch sheet50B including a switch SW and a metal plate60B.

As illustrated inFIGS. 8 and 9, the switch sheet50B of the embodiment is configured as a sheet-shaped membrane switch. The switch sheet50B includes a main block50mwhich has a substantially rectangular shape and a tail block50twhich is connected to the main block50mand is narrower than the main block50m.The main block50mis provided with the switch SW. Further, a wide blade portion50fis formed in the tail block50t.Further, a penetration hole50H is formed in the vicinity of each of apexes of the main block50m.

As illustrated inFIG. 11, the switch sheet50B of the embodiment includes a first electrode sheet56, a spacer58, and a second electrode sheet57.

The first electrode sheet56mainly includes a first insulation sheet56s,a first electrode56e,and a first terminal56c.

The first insulation sheet56sincludes a main block56mwhich is formed of an insulation sheet having flexibility and has the same shape as the main block50mof the switch sheet50B and a tail block56twhich is connected to the main block56mand has the substantially same shape as the tail block50tof the switch sheet50B. The shape of the tail block56tis different from the shape of the tail block50tof the switch sheet50B in that a front end portion opposite to the main block56mis narrower than other portions of the tail block56t.Further, the main block56mis provided with a penetration hole56H which is formed at the same position as that of the penetration hole50H of the switch sheet50B. As a material of the first insulation sheet56s,a resin such as polyethylene terephthalate (PET), polyimide (PI), and polyethylene naphthalate (PEN) can be exemplified.

The first electrode56eis formed on one surface to be located at the substantially center of the main block56m.The first electrode56eis formed as a conductor layer, for example, a substantially circular metal printed layer. The first terminal56cis formed as a conductor layer, for example, a substantially square metal layer. The first terminal56cis formed on a surface on the installation side of the first electrode56eat the front end portion of the tail block56t.Further, the first electrode56eand the first terminal56care electrically connected to each other through a first wire56w.

The second electrode sheet57mainly includes a second insulation sheet57s,a second electrode57e,and a second terminal57c.

The second insulation sheet57sis formed as the same insulation sheet as that of the first insulation sheet56s.In the case of the embodiment, the second insulation sheet57sincludes a main block57mwhich has the same shape as that of the main block56mof the first insulation sheet56sand a tail block57twhich is connected to the main block57mand has the same shape as that of the tail block56tof the first insulation sheet56sexcept for the front end portion. The front end portion of the tail block57tis narrower than other portions of the tail block57t.When the first insulation sheet56sand the second insulation sheet57soverlap each other, the front end portion of the tail block56tof the first insulation sheet56sand the front end portion of the tail block57tof the second insulation sheet57sdo not overlap each other. Further, the main block57mis provided with a penetration hole57H which is formed at the same position as that of the penetration hole50H of the switch sheet50B similarly to the first insulation sheet56s.As a material of the second insulation sheet57s,a resin such as PET, PI, or PEN can be exemplified similarly to the first insulation sheet56s.Then, the material of the second insulation sheet57smay be the same as or different from the material of the first insulation sheet56s.

The second electrode57ehas the same configuration as that of the first electrode56eand is provided on one surface of the main block57mof the second insulation sheet57sto be located at the substantially center thereof. Further, the installation position of the second electrode57eis set as a position overlapping the first electrode56ewhen the first electrode sheet56and the second electrode sheet57overlap each other. The second terminal57chas the same configuration as that of the first terminal56cand is provided on a surface on the installation side of the second electrode57eat the front end portion of the tail block57t.Further, since the front end portions of the insulation sheets do not overlap each other when the first insulation sheet56sand the second insulation sheet57soverlap each other as described above, the first terminal56cand the second terminal57care exposed while not being located between the first insulation sheet56sand the second insulation sheet57s.Further, the second electrode57eand the second terminal57care electrically connected to each other through the second wire57w.

The spacer58includes a main block58mwhich is formed of an insulation sheet having flexibility and a tail block58twhich is connected to the main block58m.The main block58mis formed so that an outer shape is the same as those of the main blocks56mand57mof the first insulation sheet56sand the second insulation sheet57s.Further, an opening58cis formed at the center of the main block58m.Further, a penetration hole58H is formed at the same position as that of the penetration hole50H of the switch sheet50B similarly to the first insulation sheet56sand the second insulation sheet57s.The tail block58tis formed in a shape in which the front end portions having a narrow width in the tail blocks56tand57tof the first insulation sheet56sand the second insulation sheet57sare excluded.

The opening58chas a substantially circular shape and has a diameter which slightly smaller than the diameters of the first electrode56eand the second electrode57e.Then, the opening58cis formed so that the opening58cis located at the inside of the peripheral edges of the first electrode56eand the second electrode57ein the top view of the spacer58when the spacer58overlaps the first electrode sheet56and the second electrode sheet57. Further, the spacer58is provided with a slit58bwhich connects a space inside the opening58cto a space outside the switch sheet50B. The slit58bis formed as an air vent when the first electrode sheet56, the spacer58, and the second electrode sheet57overlap one another.

As a material of the spacer58, a resin such as PET, PI, or PEN can be exemplified similarly to the first insulation sheet56sand the second insulation sheet57s.Additionally, the material of the spacer58may be the same as or different from that of the first insulation sheet56sor the second insulation sheet57s.Further, an adhesive (not illustrated) is applied to both surfaces of the spacer58so that the first electrode sheet56and the second electrode sheet57adhere thereto.

In a state where the first electrode sheet56, the spacer58, and the second electrode sheet57adhere to one another in this order, the first electrode56eand the first wire56wof the first electrode sheet56and the second electrode57eand the second wire57wof the second electrode sheet57are located between the first insulation sheet56sand the second insulation sheet57s.Then, the first electrode56eand the second electrode57eface each other with the opening58cinterposed therebetween to form the switch SW. Further, the penetration holes56H,57H, and58H overlap one another to form the penetration hole50H of the switch sheet50B in a state where the first electrode sheet56, the spacer58, and the second electrode sheet57overlap one another.

Further, signal cables19connected to a control device (not illustrated) are respectively connected to the first terminal56cand the second terminal57cof the switch sheet50B. The first terminal56cand the second terminal57care respectively connected to the signal cables19by conductive paste or soldering. The end of the tail block50tof the switch sheet50B including the first terminal56cand the second terminal57cconnected to the signal cables19is covered by a terminal sealing resin18as illustrated inFIGS. 8 and 9. The terminal sealing resin18is, for example, hot melt or light curing resin. In this way, the separation of the signal cables19from the first terminal56cand the second terminal57cis suppressed and the short-circuit of the first terminal56cand the second terminal57cdue to dust or the like is suppressed.

Further, the metal plate60B is formed of a metal plate member having flexibility. The metal plate60B is formed of, for example, the same material as that of the metal plate61of the second electrode sheet60of the first embodiment. The metal plate60B is formed in the substantially same shape as that of the main block50mof the switch sheet50B and a penetration hole60H is formed at the same position as that of the penetration hole50H of the switch sheet50B. Thus, the penetration hole50H of the switch sheet50B and the penetration hole60H of the metal plate60B overlap each other when the switch sheet50B and the metal plate60B overlap each other. Further, the metal plate60B covers the switch SW of the switch sheet50B when the switch sheet50B and the metal plate60B overlap each other. Specifically, as obvious fromFIG. 11, the metal plate60B is provided at the opposite side to the spacer58of the first insulation sheet56sand covers the first electrode56elocated near the sheet cushion SC among the first electrode56eand the second electrode57efrom the sheet cushion SC. Additionally, in the embodiment, the metal plate60B and the first insulation sheet56s(the switch sheet50B) do not adhere to each other.

The load detection sensor5B with the above-described configuration is disposed on the bottom wall87of the housing3B as illustrated inFIGS. 8 to 10. Specifically, the main block50mof the switch sheet50B including the switch SW is located on the bottom wall87of the housing3B. Then, since the frame wall88and the arm81of the housing3B are not provided in a direction in which the load detection sensor unit1B extends as described above, the tail block50tof the switch sheet50B, the terminal sealing resin18, and the pair of signal cables19are drawn from the housing3B.

Further, the front end of the pressing portion46contacts a position overlapping the switch SW in the metal plate60B of the load detection sensor5B as described above while the housing cover4B covers the housing3B in which the load detection sensor5B is disposed and each hook piece47is fitted into each opening82as described above. An area in which the pressing portion46contacts the metal plate60B is smaller than an area of the first electrode56epressed against the metal plate60B and an area of the top surface45S corresponding to the pressure receiving surface is larger than an area of the first electrode56e.Further, in this state, each rib49is inserted into each penetration hole60H of the metal plate60B and each penetration hole50H of the switch sheet50B and is inserted into each penetration hole30H of the housing3B. Thus, a relative positional deviation between the switch sheet50B and the metal plate60B is suppressed even when the metal plate60B and the first insulation sheet56sdo not adhere to each other as described above. Thus, the rib49can be understood as the second movement regulation member that regulates the relative movement between the switch sheet50B and the metal plate60B in the plane direction, that is, the relative movement of the first insulation sheet56s,the second insulation sheet57s,and the metal plate60B in the plane direction. Further, the rib49can be understood as the first movement regulation member that regulates the relative movement between the housing cover4B and the metal plate60B in the plane direction of the metal plate60B.

Next, a case in which seating is detected by the load detection sensor unit1B of the embodiment will be described.

When a person sits on the seat device, the lower surface of the sheet cushion SC moves downward by the weight of the person and the lower surface of the sheet cushion SC contacts the top surface45S of the housing cover4B to press the top surface45S similarly to the description of the first embodiment. Then, when the lower surface of the sheet cushion SC moves further downward, the front end of the pressing portion46presses the metal plate60B and the first insulation sheet56sis also bent by the bending of the metal plate60B. As a result, the first electrode56econtacts the second electrode57eand the switch SW of the load detection sensor5B is turned on. Then, the seating is detected by a vehicle control unit (not illustrated) connected to the signal cable19. Even in the embodiment, since an area of the top surface45S is larger than an area of the first electrode56epressed by the metal plate60B similarly to the first embodiment, the sheet cushion SC can transmit a force to the top surface45S from a position other than a position right above the first electrode56e.For this reason, since a pressing force can more appropriately concentrate on the pressing portion46, the metal plate61can be more appropriately bent.

Additionally, in the embodiment, the relative movement between the switch sheet50B and the metal plate60B in the plane direction or the relative movement between the metal plate60B and the housing cover4B is regulated by the rib49. However, the rib49is not essential. In this case, for example, the movement of the switch sheet50B and the metal plate60B in the plane direction may be regulated by the inner surface89of the frame wall88of the housing3B so as to regulate the relative movement between the metal plate60B and the switch sheet50B in the plane direction. Alternatively, the relative movement between the metal plate60B and the housing cover4B may be regulated by the hook piece47. Here, in this case, a frame wall may be formed to regulate the movement of the switch sheet50B and the metal plate60B in a direction from the main block50mof the switch sheet50B to the tail block50tin addition to the frame wall88of the embodiment described inFIGS. 8 and 9.

Next, a third embodiment of the invention will be described. Additionally, in the description of the embodiment, the same reference numerals will be given to the components which are the same as or equivalent to those of the first embodiment and a repetitive description thereof will be omitted unless otherwise specified.

FIG. 12is a cross-sectional view illustrating a configuration of a load detection sensor unit according to the third embodiment of the invention. As illustrated inFIG. 12, a load detection sensor unit1C of the embodiment is different from the load detection sensor unit1A of the first embodiment in that a load detection sensor5C is used instead of the load detection sensor5A.

The load detection sensor5C of the embodiment includes a metal plate60C and the switch sheet50C which is the same as the switch sheet50B of the second embodiment. The metal plate60C has a width larger than that of the switch sheet50C differently from the metal plate60B of the second embodiment. Further, the metal plate60C of the embodiment covers the switch SW of the switch sheet50C, but a portion covering the first electrode and the second electrode of the switch SW is separated from the first electrode sheet and the second electrode sheet of the switch sheet50C. Specifically, the configuration is as below. The housing3A of the embodiment includes a pair of ribs39formed at a position surrounded by the frame wall38. A distance between the ribs39is set to be smaller than the width of the metal plate60C, both ends of the metal plate60C are fixed to the ribs39, and the metal plate60C is bent. By this bending, a portion covering the first electrode and the second electrode of the switch SW is separated from the first electrode sheet and the second electrode sheet of the switch sheet50C as described above. Then, the front end of the pressing portion43of the housing cover4A contacts a portion covering the first electrode and the second electrode of the metal plate60C.

Even in the detection of the seating by the load detection sensor unit1C of the embodiment, when a person sits on the seat device, the lower surface of the sheet cushion SC moves downward by the weight of the person and the lower surface of the sheet cushion SC presses the top surface44S of the housing cover4A similarly to the description of the first embodiment. Then, when the lower surface of the sheet cushion SC moves further downward, the front end of the pressing portion43presses the metal plate60C so that the metal plate60C is bent from the state ofFIG. 12. Accordingly, since the first electrode and the second electrode of the switch sheet50C contact each other, the seating is detected.

According to the load detection sensor unit1C of the embodiment, since the metal plate60C is separated from the insulation sheet of the switch sheet50C, it is possible to suppress the contact of the electrode due to the slight bending of the metal plate60C. Thus, an erroneous detection that seating is detected when the sheet cushion is bent by a baggage or the like loaded on the seat surface of the seat device can be suppressed.

Additionally, in the embodiment, the metal plate60C may be formed of bimetal. In this case, it is desirable that the metal plate60C be formed of bimetal so that a portion covering the first electrode and the second electrode of the switch SW is defamed to move away from the first electrode and the second electrode in accordance with an increase in temperature. As in the embodiment, when the electrode is formed on the resinous insulation sheet, the insulation sheet is easily deformed in accordance with an increase in temperature and thus the switch SW is easily turned on by a weak force in accordance with an increase in temperature. Further, metal does not greatly flexibly change even when a temperature changes, but it does not mean that the flexibility does not change at all. Here, since the metal plate60C is formed of bimetal which is deformed to be separated from the electrode in accordance with an increase in temperature, the metal plate is easily bent or the switch SW is easily turned on by a weak force in accordance with an increase in temperature. Since the metal plate is separated from the electrode, a change in seating detection can be suppressed. Thus, the seating can be more appropriately detected.

While the load detection sensor unit of the invention has been described by the above-described embodiments, the invention is not limited to the above-described embodiments.

For example, the pressing portions43and46of the embodiments may be separated from the metal plate in a state other than the seating detection state.

For example, the pedestal2A of the first embodiment is not essential. In this case, the load detection sensor unit1A of the first embodiment may have a configuration in which the hook portion22of the pedestal2A is provided in the housing3A. Further, the load detection sensor unit1A may not be fixed to the S spring of the seat device and may be disposed on a seat pan of the seat device by removing the pedestal2A and changing the shape of the housing3A.

Further, the load detection sensor unit1B of the second embodiment may have the same pedestal as that of the first embodiment and may be fixed to the S spring of the seat device.

Further, it has been described that the metal plate60B and the switch sheet50B do not adhere to each other in the second embodiment, but the metal plate60B and the switch sheet50B may adhere to each other. Here, since the adhesive becomes soft or hard in accordance with a change in temperature, it is desirable that the metal plate60B and the switch sheet50B do not adhere to each other as described above due to a change in on-load.

Further, the components of the load detection sensor units1A,1B, and1C may be combined, omitted, and modified or known techniques may be added without departing from the object of the invention in addition to the content described in the above-described embodiments or modified examples.

Further, in the above-described embodiments, as illustrated inFIGS. 2, 10, and 12, a case in which the lower surface of the sheet cushion SC is separated from the load detection sensor unit in a non-seating state has been described. However, the lower surface of the sheet cushion SC may contact the load detection sensor unit in the non-seating state.

As described above, according to the invention, it is possible to provide the load detection sensor unit capable of suppressing an erroneous seating detection while appropriately detecting seating.

REFERENCE SIGNS LIST