JP6155351B1 - Load detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To individually detect the presence / absence of a load and the presence / absence of a failure applied to an object to be detected. A load detection apparatus 100 includes switches SW1 to SW3, series resistors r1 to r3 connected in series to the switches SW1 to SW3, and a parallel resistor R1 connected in parallel to the switches SW1 to SW3. A plurality of load detection sensors 5X to 5Z having .about.R3 are provided between the pair of terminals 8T1 and 8T2. The load detection sensors 5X to 5Z are connected in series with each other, and the total combined resistance of the load detection sensors 5X to 5Z differs depending on the combination of ON and OFF of the switches SW1 to SW3. The resistance values of r1 to r3 and the resistance values of the respective parallel resistors R1 to R3 are different, and the resistance values of the series resistors r1, r2, and r3 of the load detection sensors 5X, 5Y, and 5Z and the resistances of the parallel resistors R1, R2, and R3 are different. The value is different. [Selection] Figure 2

Description

  The present invention relates to a load detection device, which is suitable for properly detecting seating and the like.

  As one of safety systems in vehicles, an alarm system for warning that a seat belt is not worn when riding is put into practical use. In this alarm system, a warning is issued when the seat belt is not detected while a person is seated. As a load detection device for detecting a load caused by a seating of a person, for example, there is one described in Patent Document 1 below.

  Patent Document 1 listed below describes a seating sensor that individually detects the presence or absence of seating in a plurality of seats. That is, in the seating sensor described in Patent Document 1 below, a plurality of sets of a sensor unit including a switch that is turned on in response to seating and a resistance element connected in parallel to the sensor unit are provided between a pair of terminals. ing. In this seating sensor, one set of sensor units and resistance elements is assigned to each seat, and the output resistance is different for each detection or non-detection combination in each set of sensor units. For this reason, the presence or absence of seating with respect to a plurality of seats can be determined based on signals output from the pair of terminals.

JP 2013-016285 A

  By the way, when a sensor unit fails due to an unforeseen factor, such as when a circuit of a sensor unit assigned to the seat is short-circuited due to, for example, spilling a drink, the presence or absence of seating on multiple seats is detected. It will be impossible. For this reason, it is desired to individually detect the presence / absence of seating and the presence / absence of failure in a plurality of seats.

  Then, an object of this invention is to provide the load detection apparatus which can detect separately the presence or absence of the load added to the detection target object which should detect a load, and the presence or absence of a failure.

  In order to solve the above problems, a load detection device according to the present invention includes a switch composed of a pair of electrodes opposed to each other, a series resistor connected in series to the switch, and the switch A plurality of load detection sensors having parallel resistances connected in parallel are provided between a pair of terminals, and the total combined resistance of the load detection sensors is different for each combination of ON and OFF of each switch, The resistance values of the series resistors and the resistance values of the parallel resistors are different from each other, and the resistance values of the series resistors and the parallel resistors are different from each other for each load detection sensor.

In such a load detection device, one load detection sensor is assigned to each detection target to be detected, for example, a seat cushion of a seat or a bed mat of a bed. Among these load detection sensors, a load detection sensor assigned to a detection target in a state where a load is applied turns on a switch included in the load detection sensor.
By the way, the parallel resistance connected in parallel to the switch may be connected in parallel only to the switch, or may be connected in parallel to the switch and the series resistance.
When the parallel resistance is connected only to the switch in parallel, the resistance value of the load detection sensor when the switch is turned on is the series resistance value, and the resistance value of the load detection sensor when the switch is off is the resistance value of the series resistance and the parallel resistance. This is the value of the combined resistance.
On the other hand, when the parallel resistance is connected in parallel to the switch and the series resistance, the resistance value of the load detection sensor that turns on the switch becomes the value of the combined resistance of the series resistance and the parallel resistance, and the load detection sensor that turns off the switch. The resistance value is a parallel resistance value.
Moreover, when the load detection sensor is short-circuited in either case where the parallel resistance is connected only in parallel to the switch or in the case where the parallel resistance is connected to the switch and the series resistance, the load detection sensor The combined resistance of the series resistance and the parallel resistance is substantially zero.
As described above, the total combined resistance of each load detection sensor is different for each combination of ON and OFF of each switch, the resistance value of each series resistance and the resistance value of each parallel resistance are different, and each load detection sensor is connected in series. The resistance value of the resistor is different from the resistance value of the parallel resistor.
For this reason, even if some or all of the load detection sensors have a failure, the inter-terminal resistance values as seen from the pair of terminals differ depending on the combination of ON and OFF of each load detection sensor. .
Therefore, with respect to the engine control unit electrically connected to the pair of terminals, the presence or absence of a load and the presence or absence of a failure applied to a plurality of detection objects based on the level of a signal given from the load detection device via the pair of terminals. Can be detected individually.

  In addition, the minimum resistance value of one of the parallel resistance and the series resistance in each of the load detection sensors is the other resistance of the parallel resistance and the series resistance in each of the load detection sensors. It is preferable that it is larger than the combined resistance value.

When detecting a change in the resistance value, the larger the change in the resistance value, the smaller the influence of noise and variation, and thus the detection can be easily performed. Here, there is a case where it is desired to detect one of the load and the failure with priority over the other. For example, when it is desired to detect a failure in preference to a load, if the series resistance is the one resistance and the parallel resistance is the other resistance, the change in resistance between the terminals as viewed from a pair of terminals when there is a failure Can be increased. In addition, when it is desired to detect the load in preference to the failure, if the parallel resistance is the one resistance and the series resistance is the other resistance, the change in the resistance value between the terminals as viewed from the pair of terminals when there is a load. Can be increased.
In addition, the change width of the resistance value of the other resistor corresponding to the one not giving priority to detection is smaller than the minimum resistance value of one resistor corresponding to the one giving priority to detection.
Therefore, since the change in the resistance value of the priority can be increased, it becomes possible to more easily detect the priority.

  Moreover, it is preferable that the resistance value of the parallel resistance in each of the load detection sensors is larger than the resistance value of the series resistance in each of the load detection sensors.

  In general, it is possible to detect the load more easily than a failure that hardly occurs.

  Moreover, it is preferable that each of the load detection sensors can be attached and detached individually.

  In such a case, even if one of the plurality of load detection sensors fails, only the failed load detection sensor can be easily replaced without replacing the entire plurality of load detection sensors. .

  Moreover, it is preferable that the parallel resistance and the series resistance of each of the plurality of load detection sensors are chip resistances.

  In this case, since the resistance value can be set more accurately than the printing resistance, it is possible to more clearly detect the presence / absence of a load applied to a plurality of detection objects and the presence / absence of a failure.

  The load detection sensor includes a substrate having one of the pair of electrodes, and an electrode sheet disposed on one surface of the substrate via a spacer and having the other of the pair of electrodes, and the chip resistance is The spacer is disposed on the other surface opposite to the one surface of the substrate facing the spacer.

  The thickness of the chip resistor is generally larger than the thickness of the printed resistor, but the chip resistor is on the other surface of the substrate opposite to the side where the first electrode facing the second electrode is disposed. Therefore, it is possible to avoid the sensitivity of the load detection sensor from being deteriorated due to the thickness of the chip resistor.

  As described above, according to the present invention, there is provided a load detection device that can individually detect the presence / absence of a load applied to a detection target to be detected and the presence / absence of a failure.

It is a schematic diagram which shows the structure of the load detection apparatus in 1st Embodiment. It is a figure which shows the equivalent circuit of the load detection apparatus in 1st Embodiment. It is an exploded view which shows the structure of the load detection sensor unit in 1st Embodiment. It is sectional drawing which shows a mode that the load detection sensor unit was attached to S spring of a seat apparatus. It is an exploded view which shows the structure of a load detection sensor. It is sectional drawing in the XX line of the load detection sensor shown in FIG. It is sectional drawing in the YY line of the load detection sensor shown in FIG. It is a figure which shows the ON state of a load detection sensor. It is a schematic diagram which shows the structure of the load detection apparatus in 2nd Embodiment. It is a figure which shows the equivalent circuit of the load detection apparatus in 2nd Embodiment. It is an exploded view which shows the structure of the load detection sensor unit in 2nd Embodiment. It is the figure which looked at the load detection sensor unit of FIG. 11 from another angle. It is sectional drawing of the load detection sensor unit of FIG. 11, FIG. It is an exploded view which shows the load detection sensor of FIG. 11, FIG.

  Hereinafter, a preferred embodiment of a load detection device according to the present invention will be described in detail with reference to the drawings. For ease of understanding, the scale of each figure may be different from the scale described in the following description.

(1) 1st Embodiment FIG. 1: is a schematic diagram which shows the structure of the load detection apparatus in 1st Embodiment. As shown in FIG. 1, the load detection device 100 includes a plurality of load detection sensor units 1 </ b> X to 1 </ b> Z and a cable 6.

  Each of the load detection sensor units 1X to 1Z is disposed below, for example, a seat cushion in a vehicle seat device, and one load detection sensor unit 1X, 1Y, 1Z is assigned to each seat cushion.

  The load detection sensor unit 1X includes a load detection sensor 5X having a switch SW1, a series resistance r1 connected in series with the switch SW1, and a parallel resistance R1 connected in parallel with the switch SW1. A connector 31X of the load detection sensor unit 1X is connected to the load detection sensor 5X.

  The load detection sensor unit 1Y includes a load detection sensor 5Y having a switch SW2, a series resistance r2 connected in series with the switch SW2, and a parallel resistance R2 connected in parallel with the switch SW2. The load detection sensor 5Y is connected to the connector 31Y of the load detection sensor unit 1Y.

  The load detection sensor unit 1Z includes a load detection sensor 5Z having a switch SW3, a series resistance r3 connected in series to the switch SW3, and a parallel resistance R3 connected in parallel to the switch SW3. A connector 31Z of the load detection sensor unit 1Z is connected to the load detection sensor 5Z.

  The cable 6 connects the load detection sensor units 1X to 1Z and the engine control unit ECU, and includes a connector 8 on the engine control unit side and connectors 9X to 9Z on the load detection sensor unit side.

  The connector 8 on the engine control unit side is connected to the engine control unit ECU. The connectors 9X to 9Z on the load detection sensor unit side are connected to the connectors 31X to 31Z of the corresponding load detection sensor units 1X to 1Z. The load detection sensors 5X to 5Z of the load detection sensor units 1X to 1Z can be individually attached and detached by the connectors 31X to 31Z of the corresponding load detection sensor units 1X to 1Z.

  FIG. 2 is a diagram illustrating an equivalent circuit of the load detection device 100 according to the first embodiment. FIG. 2 shows a state where the connectors 31X to 31Z of the load detection sensor units 1X to 1Z and the connectors 9X to 9Z of the cable 6 are mounted. In this state, the pair of terminals 31X1, 31X2, 31Y1, 31Y2, 31Z1, 31Z2 of the connectors 31X, 31Y, 31Z and the pair of terminals 9X1, 9X2, 9Y1, 9Y2, 9Z1, 9Z2 of the connector are electrically connected. The In this state, the load detection sensors 5X to 5Z are connected in series between the pair of terminals 8T1 and 8T2 of the connector 8 in the cable 6.

  The switches SW1 to SW3 in the load detection sensors 5X to 5Z detect the presence or absence of a load caused by seating on the seat, and are turned on when seated and turned off when not seated. The combined resistances of the load detection sensors 5X to 5Z when the switches SW1 to SW3 are in the on state are different from the combined resistances of the load detection sensors 5X to 5Z when the switches SW1 to SW3 are in the off state. . The resistance values of the series resistors r1 to r3 and the resistance values of the parallel resistors R1 to R3 are different from each other, and the series resistors r1, r2, r3 and the parallel resistors R1, R2 of the load detection sensors 5X, 5Y, and 5Z, respectively. , R3 are different from each other.

  In the case of this embodiment, the resistance values of the parallel resistors R1 to R3 are made larger than the resistance values of the series resistors r1 to r3, respectively, and the minimum resistance value among the resistance values of the parallel resistors R1 to R3 is the series resistors r1 to r3. The combined resistance value is made larger. For example, the resistance values of the series resistors r1, r2, and r3 are 50Ω, 100Ω, and 200Ω, and the resistance values of the parallel resistors R1, R2, and R3 are 400Ω, 800Ω, and 1600Ω. In this example, the resistance values of the series resistors r1, r2, and r3 and the resistance values of the parallel resistors R1, R2, and R3 are all set to 1: 2: 4. When such resistance values of the series resistors r1 to r3 and the resistance values of the parallel resistors R1 to R3 are employed, the following Table 1 is obtained.

  As shown in Table 1, since there are three load detection sensors 5X to 5Z in the present embodiment, there are eight combinations of on and off of the switches SW1, SW2, and SW3 in the load detection sensors 5X to 5Z. It becomes. It can be seen from Table 1 that the total combined resistance of the load detection sensors 5X to 5Z is different for each combination. That is, when the load detection sensors 5X to 5Z are not short-circuited, even when one, two or all of the load detection sensors 5X to 5Z are short-circuited, the load detection sensors 5X to 5Z are turned on. The total combined resistance of the load detection sensors 5X to 5Z is different for each combination with OFF.

  Next, the configuration of the load detection sensor units 1X to 1Z will be described. However, since the configurations of the load detection sensor units 1X to 1Z are the same, only the configuration of the load detection sensor unit 1X will be described.

  FIG. 3 is an exploded view showing the configuration of the load detection sensor unit 1X in the first embodiment, and FIG. 4 is a cross-sectional view showing a state in which the load detection sensor unit 1X is attached to the S spring of the seat device. FIG. 4 is a cross-sectional view of the load detection sensor unit 1X on the surface along the left-right direction of the seat, and the load detection sensor 5X is simplified in order to avoid complication of the drawing.

  As shown in FIGS. 3 and 4, the load detection sensor unit 1X includes a pedestal 2X, a housing 3X, a housing cover 4X, and a load detection sensor 5X as main components.

  The pedestal 2 </ b> X includes a placement portion 21 on which the housing 3 </ b> X is placed and a pair of hook portions 22 that are coupled to the placement portion 21. The upper surface of the mounting portion 21 is a mounting surface 21S on which the housing 3X is mounted. Further, the mounting portion 21 is formed with a plurality of through holes 23 penetrating from the mounting surface 21S to the lower surface of the mounting portion 21 (the surface opposite to the mounting surface 21S). The pedestal 2X is formed, for example, by molding a metal plate. In this case, the plate thickness is set to 0.8 mm, for example.

  The pair of hook portions 22 are respectively provided at positions facing each other across the placement portion 21, and a pair of adjacent S springs among a plurality of S springs 90 stretched side by side in the opening of the frame in the vehicle seat device. Each is fitted into a spring 90. Accordingly, each hook portion 22 is a locking portion that locks the base 2 </ b> X to the S spring 90. In the present embodiment, the pair of hook portions 22 are formed so as to be fitted in a pair of S springs 90 arranged in the lateral direction of the seat device and adjacent in the lateral direction. In addition, with the pair of hook portions 22 fitted in the pair of adjacent S springs 90 as described above, the placement portion 21 is positioned below the seat cushion SC placed on the plurality of S springs 90, Further, when the plurality of S springs are viewed from above, the placing portion 21 is disposed between the pair of S springs 90. With the pair of hook portions 22 fitted into the pair of S springs 90 as described above, the placement surface 21S is positioned below the lower end of each S spring 90 in the present embodiment.

  The housing 3X includes a connector 31X that is mechanically and electrically connected to the connector 9X (FIG. 1) of the cable 6, and a switch housing portion 32 that is coupled to the connector 31X. The switch housing portion 32 has a bottom wall 37 and a frame wall 38, and a housing space CA for housing the load detection sensor 5X is formed by the bottom wall 37 and the frame wall 38. In the present embodiment, the frame wall 38 is subjected to a blanking process in order to suppress deformation during resin molding.

  A pair of fixing pins 33 and a pair of connection pins 34 are provided on the bottom wall 37 of the switch housing portion 32. The pair of fixing pins 33 are pins for fixing the load detection sensor 5X accommodated in the housing 3X. Further, the pair of connection pins 34 are electrically connected to corresponding connector terminals of the connector 31X, and are electrically connected to the load detection sensor 5X. In FIG. 3, the connector terminals of the connector 31X are omitted.

  A pair of projecting pieces 35 are provided on the outer surface of the frame wall 38 of the switch housing portion 32. In the present embodiment, the pair of protruding pieces 35 are provided so as to be arranged in the lateral direction of the seat. In addition, a plurality of hook pieces 36 that are fitted into the respective through holes 23 of the base 2 </ b> X are provided at the lower end of the frame wall 38. The respective hook pieces 36 are fitted into the respective through holes 23 of the pedestal 2X, whereby the housing 3X is fixed to the pedestal 2X and placed on the placement surface 21S of the housing 3X as described above. The upper surface of the bottom wall 37 of the switch housing portion 32 in the housing 3X is a mounting surface on which the load detection sensor 5X is mounted.

  The housing cover 4 </ b> X is a lid member that covers the accommodation space CA of the switch accommodation portion 32, and has a top wall 47 and a frame wall 48. A pair of arms 41 is provided at the lower end of the frame wall 48 of the housing cover 4X. Each arm 41 is formed with an opening 42 into which the protruding piece 35 provided on the frame wall 38 of the switch housing portion 32 in the housing 3X is fitted. The housing cover 4X is locked to the housing 3X by fitting the pair of protruding pieces 35 of the housing 3X into the openings 42 of the pair of arms 41, respectively. Therefore, in a state where the housing cover 4X is locked to the housing 3X, the pair of arms 41 sandwich the housing 3X from the lateral direction of the seat.

  The top wall 47 of the housing cover 4X is provided with a switch pressing portion 43 that protrudes from an inner surface facing the bottom wall 37 of the switch housing portion 32 in the housing 3X. The switch pressing portion 43 has a curved surface with a convex tip, and when the housing cover 4X covers the housing 3X and the respective projecting pieces 35 are fitted in the respective openings 42, the tip is the load detection sensor 5X. In contact with the switch. In this state, as shown in FIG. 4, the top wall 47 of the housing cover 4X and the frame wall 38 of the housing 3X are separated from each other, and a gap GA is formed. In general, the seat cushion SC is made of foamed urethane resin. Accordingly, examples of the material of the housing cover 4X include resins such as polycarbonate (PC), polyamide (PA), polybutylene terephthalate (PBT), phenol resin, and epoxy resin.

  By the way, in a state where the load detection device 100 is attached to the pair of S springs 90, the upper surface 47S of the top wall 47 of the housing cover 4X faces the lower surface of the seat cushion SC with a predetermined distance therebetween.

  The upper surface 47S is a pressure receiving surface that is pressed by the seat cushion SC, and is flat in this embodiment. Further, the entire upper surface 47S moves in the front-rear direction and the left-right direction with respect to the mounting surface 21S so that the angle of the upper surface 47S with respect to the mounting surface 21S changes when viewed along the mounting surface 21S direction of the base 2X. It is like that. However, since the pair of arms 41 of the housing cover 4X sandwich the housing 3X from the lateral direction of the seat device as described above, the angle at which the housing cover 4X rotates is larger in the front-rear direction than in the left-right direction of the seat. The Since the upper surface 47S is not divided, the entire upper surface 47S moves.

  Next, the load detection sensor 5X housed in the switch housing portion 32 of the housing 3X will be described.

  FIG. 5 is an exploded view showing the configuration of the load detection sensor 5X. 6 is a sectional view taken along line XX of the load detection sensor 5X shown in FIG. 5, and FIG. 7 is a sectional view taken along line YY of the load detection sensor 5X shown in FIG.

  As shown in FIGS. 5 to 7, the load detection sensor 5 </ b> X includes a first electrode sheet 50, a second electrode sheet 60, and a spacer 70 as main components.

  The 1st electrode sheet 50 has the insulating board | substrate 51 which does not have flexibility, for example. Examples of the material of the substrate 51 include phenol resin and epoxy resin. The first electrode 52 and the first contact portion 53 are disposed on one surface F1 of the substrate 51 that faces the second electrode sheet 60.

  The first electrode 52 is one electrode constituting the switch SW1 and is, for example, a circular metal printing layer. The first contact portion 53 is formed by connecting a substantially rectangular contact area AR1 that is in contact with the second electrode sheet 60 and a non-contact area AR2 that is not in contact with the second electrode sheet 60 to each other.

  In the substrate 51, the other surface F2 opposite to the one surface F1 is a lower surface of the load detection sensor 5X, and a parallel resistor R1 and a series resistor r1 are disposed on the other surface F2. The parallel resistor R1 and the series resistor r1 are chip resistors in this embodiment.

  The substrate 51 is formed with a plurality of through holes penetrating from one surface F1 to the other surface F2 of the substrate 51. The first sheet through hole 55A, the second sheet through hole 55B, and the fixing through hole 55C, respectively. , 55D and pin through holes 55E, 55F.

  55 A of 1st sheet | seat through-holes are sheet | seat through-holes in which opening is located in the area | region where the 1st electrode 52 is arrange | positioned among the one surfaces F1 of the board | substrate 51. FIG. A first conductive member CPA is provided in the first sheet through hole 55A, and the circuit portion and the first electrode 52 arranged on the other surface F2 of the substrate 51 via the first conductive member CPA. Are electrically connected. The first conductive member CPA is provided on the inner peripheral surface of the first sheet through hole 55A, and an air hole SP surrounded by the first conductive member CPA is provided in the first sheet through hole 55A. It is formed.

  The second sheet through hole 55 </ b> B is a sheet through hole in which an opening is positioned in a region where the first contact portion 53 is disposed on one surface F <b> 1 of the substrate 51. In the present embodiment, the opening of the second sheet through hole 55B is positioned in the non-contact area AR2 of the first contact portion 53.

  The second conductive member CPB is filled in the second sheet through hole 55B. The circuit part disposed on the other surface F2 of the substrate 51 and the non-contact area AR2 of the first contact portion 53 are electrically connected via the second conductive member CPB.

  The fixing through holes 55C and 55D are through holes through which a pair of fixing pins 33 provided on the bottom wall 37 of the switch housing portion in the housing 3X are inserted. The diameters of the fixing through holes 55 </ b> C and 55 </ b> D are approximately the same as the outer diameter of the pair of fixing pins 33.

  The pin through holes 55E and 55F are through holes through which a pair of connection pins 34 provided in the housing 3X are inserted. A terminal TLX1, which is one terminal part of the electric circuit in the load detection sensor 5X, is provided inside the pin through hole 55E, and the other terminal part of the electric circuit in the load detection sensor 5X is provided in the pin through hole 55F. A terminal TLX2 is provided. A terminal TLX1 provided in the pin through hole 55E is electrically connected to the series resistor r1, and is electrically connected to the first contact portion 53 via the series resistor r1. Further, the terminal TLX2 provided in the pin through hole 55F is electrically connected to a contact point between the first electrode 52 and the parallel resistor R1, and is connected to the first contact part 53 via the parallel resistor R1. The terminals TLX1 and TLX2 are provided along the inner peripheral surfaces of the corresponding pin through holes 55E and 55F, and the width of the space surrounded by the terminals TLX1 and TLX2 is approximately the same as the outer diameter of the connection pin 34. It is said. When the pair of pin through holes 55E and 55F is inserted, the terminal TLX1 and one connection pin 34 are electrically connected, and the terminal TLX2 and the other connection pin 34 are electrically connected. These connection pins 34 are electrically connected to the corresponding connector terminals of the connector 31X (FIG. 1) as described above, and are connected to the engine control unit ECU (FIG. 1) via the cable 6 (FIG. 1). .

  The 2nd electrode sheet 60 has the metal sheet 61, the 2nd electrode 62, and the 2nd contact part 63 as a main structure.

  The metal sheet 61 is a thin metal sheet having flexibility. In the present embodiment, the metal sheet 61 has a vertical width shorter than the vertical width of the substrate 51, and is a thin rectangular parallelepiped shape having a horizontal width equivalent to the horizontal width of the substrate 51. It is said. The material of the metal sheet 61 is not particularly limited as long as it is a metal, and examples thereof include copper and stainless steel.

  The metal sheet 61 is formed with fixing through holes 65C and 65D penetrating from one surface of the metal sheet 61 to the other surface. The fixing through holes 65C and 65D are through holes through which a pair of fixing pins 33 provided on the bottom wall of the switch housing portion in the housing 3X are inserted, and are formed in the substrate 51 of the first electrode sheet 50. It has the same shape and size as the holes 55C and 55D. Further, the arrangement positions of the second electrode 62 and the second contact portion 63 with respect to the fixing through holes 65C and 65D, and the first electrode 52 and the first contact portion 53 with respect to the fixing through holes 55C and 55D in the first electrode sheet 50 are provided. When the first electrode sheet 50 and the metal sheet 61 are overlapped with each other, the fixing through hole 55C and the fixing through hole 65C overlap each other, and the fixing through hole 55D The fixing through holes 65D overlap each other.

  The second electrode 62 is the other electrode that constitutes the switch SW1. In the present embodiment, the second electrode 62 is a portion facing the first electrode 52 via the spacer 70 in the metal sheet 61. That is, a part of the metal sheet 61 also serves as the second electrode 62. Note that, for example, a metal layer made of the same material as or different from the metal sheet 61 may be disposed as a second electrode 62 at a site facing the first electrode 52 via the spacer 70 in the metal sheet 61.

  The 2nd contact part 63 is one member which comprises the connection maintenance part AP, and is formed as a leaf | plate spring in this embodiment. That is, the metal sheet 61 is provided with a pair of notches 61A and 61B (FIG. 1) extending from one end of the metal sheet 61 toward the other end side with a predetermined interval therebetween, and these notches 61A and 61B ( A part sandwiched between the two parts shown in FIG. Further, the second contact portion 63 is bent toward the first electrode sheet 50 side so that the second contact portion 63 is inclined with respect to the sheet surface of the metal sheet 61, whereby the second contact portion 63 is It is formed as a leaf spring. In this way, a portion of the metal sheet 61 that is different from the portion that is the second electrode 62 is the second contact portion 63. The position where the second contact portion 63 is formed is a position that overlaps the contact area AR1 of the first contact portion 53 when the first electrode sheet 50 and the second electrode sheet 60 are overlapped. The shape of the leaf spring formed as the second contact portion 63 may be, for example, a trapezoid whose base width is larger than the width of the open end, and various shapes other than a rectangle and a trapezoid are applicable. is there. Further, as the second contact portion 63, a metal layer made of the same material as or different from the metal sheet 61 may be disposed on the first electrode sheet 50 side in the metal sheet 61.

  The spacer 70 is a thin insulating member that is sandwiched between the first electrode sheet 50 and the second electrode sheet 60. In the present embodiment, the spacer 70 is substantially the same shape as that obtained by removing the second contact portion 63 from the metal sheet 61. The same size. Examples of the material of the spacer 70 include resins such as PET, PI, and PEN.

  An opening 71 is formed in the spacer 70. The opening 71 is between the first electrode 52 disposed on the substrate 51 and the second electrode 62 of the metal sheet 61 facing the first electrode 52, and the first electrode 52 and the second electrode 62 in the vertical direction. It is formed at a position overlapping the two electrodes 62. The size of the opening 71 is slightly smaller than the size of the first electrode 52.

  In addition, a slit-like opening 72 is formed in the spacer 70. The opening 72 is between the first contact portion 53 disposed on the substrate 51 and the second contact portion 63 of the metal sheet 61 facing the first contact portion 53, and is a first contact in the vertical direction. It is formed at a position overlapping the portion 53 and the second contact portion 63. The size of the opening 72 is slightly larger than the size of the leaf spring formed as the second contact portion 63 in the metal sheet 61.

  Further, the spacer 70 is formed with fixing through holes 75C and 75D penetrating from one surface of the spacer 70 to the other surface. The fixing through holes 75C and 75D are through holes through which the fixing pins 33 provided on the bottom wall of the switch housing portion in the housing 3X are inserted, and the fixing through holes 55C formed in the substrate 51 of the first electrode sheet 50. , 55D. Further, the arrangement portion of the opening 71 and the opening 72 with respect to the fixing through holes 75C and 75D in the spacer 70, and the arrangement portion of the first electrode 52 and the first contact portion 53 with respect to the fixing through holes 55C and 55D in the first electrode sheet 50. And have the same relative position. Therefore, when the first electrode sheet 50, the spacer 70, and the second electrode sheet 60 are overlapped, the fixing through hole 55C, the fixing through hole 65C, and the fixing through hole 75C are overlapped with each other, and the fixing through hole 55D is fixed. The through hole 65D and the fixing through hole 75C overlap each other.

  The first electrode sheet 50, the second electrode sheet 60, and the spacer 70 are overlapped to constitute the load detection sensor 5X. In the load detection sensor 5X, as shown in FIG. 6, the first electrode 52 and the second electrode 62 face each other in a state of being separated from each other through the opening 71, and the switch SW1 is configured. In a state where the first electrode 52 and the second electrode 62 are separated from each other, the distance between the first electrode 52 and the second electrode 62 is, for example, 0.1 mm. The air hole SP formed in the electrode through hole 52 </ b> A communicates with the opening 71. Therefore, when the second electrode 62 is bent and contacts the first electrode 52, unnecessary air can be discharged from the air hole SP to the outside of the load detection sensor 5X. As described above, the first sheet through hole 55A is only a hole for electrically connecting the first electrode 52 disposed on the one surface F1 of the substrate 51 and the circuit portion disposed on the other surface F2 side. It also serves as an exhaust hole for discharging the air in the opening 71 to the outside of the load detection sensor 5X.

  Further, as described above, in the load detection sensor 5X, the second contact portion 63 of the second electrode sheet 60 is formed as a leaf spring, and is plastically deformed with respect to the sheet surface of the metal sheet 61 so as to be always inclined. is there. Therefore, as shown in FIG. 7, the second contact portion 63 passes through the opening 72 formed by the notch of the spacer 70 and is connected to the contact area AR <b> 1 of the first contact portion 53 of the first electrode sheet 50. The Thus, the connection maintaining part AP is formed by the first contact part 53 and the second contact part 63 coming into contact with each other. That is, the first contact portion 53 of the first electrode sheet 50 is one member constituting the connection maintaining portion AP that maintains electrical connection even when no external pressure is applied to the housing cover 4X of the load detection sensor unit SU. The second contact portion 63 of the second electrode sheet 60 is the other member constituting the connection maintaining portion AP.

  In such a load detection sensor 5X, as shown in FIG. 3, the pair of fixing pins 33 in the housing 3X includes fixing through holes 55C and 55D for the first electrode sheet 50, and fixing through holes 75C and 75D for the spacer 70. And it is fixed to the housing 3X by being inserted through the fixing through holes 65C and 65D of the second electrode sheet 60 in order. At this time, the substrate 51 and the bottom wall 37 of the housing 3X are located between the first electrode 52 and the mounting surface 21S of the base 2X. Accordingly, the substrate 51 and the bottom wall 37 can be understood as support members that support the first electrode 52 on the base 2X.

  In addition, with the load detection sensor 5X fixed to the housing 3X, the pair of connection pins 34 are inserted into the pin through holes 55E and 55F of the first electrode sheet 50, respectively. As a result, the terminals TLX1 and TLX2 provided in the pin through holes 55E and 55F come into contact with the corresponding connection pins 34, and are electrically connected to the connector terminals of the connector 31X of the housing 3X via the connection pins 34. . Further, by attaching the housing cover 4X, the tip of the switch pressing portion 43 comes into contact with the opposite side of the second electrode 62 to the first electrode 52 side in the switch SW as described above.

  Next, an operation for turning on the switch SW1 of the load detection sensor 5X will be described.

  When a person sits on the seat, the lower surface of the seat cushion SC moves downward due to the load of the person. In the present embodiment, the lower surface of the seat cushion SC is positioned above the upper ends of the pair of hook portions 22. Therefore, even if the lower surface of the seat cushion SC is inclined with respect to the S spring surface including the respective S springs 90, the upper ends of the pair of hook portions 22 press the lower surfaces of the seat cushion SC, thereby causing the seat cushion SC to The inclination of the lower surface of the plate is moderated to some extent.

  When the lower surface of the seat cushion SC further moves downward, the lower surface of the seat cushion SC comes into contact with the upper surface 47S of the housing cover 4X while being deformed by being pressed by the upper ends of the pair of hook portions 22. At this time, the lower surface of the seat cushion SC may be inclined to some extent while the inclination is relaxed as described above. In this case, the lower surface of the seat cushion SC is inclined with respect to the mounting surface 21S of the pedestal 2X that is locked to the S spring 90, and the upper surface 47S of the housing cover 4X disposed on the mounting surface 21S. Even so, the lower surface of the seat cushion SC is inclined.

  In the present embodiment, as described above, the housing cover 4X can be rotated around the tip of the switch pressing portion 43, which is a shaft portion in contact with the load detection sensor 5X, so that the upper surface 47S is placed on the mounting surface. It moves so that the angle with respect to the surface 21S changes. Therefore, even if the lower surface of the seat cushion SC is inclined with respect to the upper surface 47S of the housing cover 4X, the upper surface 47S can be brought into surface contact with the lower surface of the seat cushion SC.

  When the lower surface of the seat cushion SC further moves downward, the gap GA is formed between the housing cover 4X and the housing 3X as described above. Therefore, the housing cover 4X is lowered within the range of the gap GA. Move to.

  FIG. 8 is a diagram illustrating an ON state of the load detection sensor 5X. As shown in FIG. 8, when the tip of the switch pressing portion 43 presses the second electrode 62 due to the downward movement of the housing cover 4 </ b> X, the second electrode 62 comes into contact with the first electrode 52. As a result, the switch SW1 of the load detection sensor 5X is turned on. For this reason, the resistance value between the pair of terminals TLX1 and TLX2 becomes low, and the change in resistance is detected by the engine control unit ECU (FIG. 1) via the cable 6 (FIG. 1).

  As described above, in the load detection device 100 of this embodiment, the plurality of load detection sensors 5X to 5Z are connected in series between the pair of terminals 8T1 and 8T2. Each of the load detection sensors 5X to 5Z includes switches SW1 to SW3 configured by a pair of electrodes opposed to each other, series resistors r1 to r3 connected in series to the switches SW1 to SW3, and switches And parallel resistors R1 to R3 connected in parallel to SW1 to SW3.

  In such a load detection device 100, one load detection sensor 5X to 5Z is assigned to each seat. Among the load detection sensors 5X to 5Z, for example, the load detection sensor 5X assigned to the seat in the seated state turns on the switch SW1 that the load detection sensor 5X has, and the resistance value at the load detection sensor 5X becomes the value of the series resistance r1. On the other hand, for example, in the load detection sensor 5Y assigned to a seat that is not in the seated state, the switch SW2 that the load detection sensor 5Y has is turned off, and the resistance value of the load detection sensor 5Y is the value of the combined resistance of the series resistance r1 and the parallel resistance R1.

  In the load detection device 100 according to the present embodiment, the total combined resistance of the load detection sensors 5X to 5Z is different for each combination of ON and OFF of the switches SW1 to SW3.

  For this reason, as shown in “No short” in Table 1 above, the inter-terminal resistance values viewed from the pair of terminals 8T1 and 8T2 are ON and OFF of the switches SW1 to SW3 of the respective load detection sensors 5X to 5Z. It will be different for each combination.

  On the other hand, among the load detection sensors 5X to 5Z, when the occupant seated in the seat spills a drink, for example, and the load detection sensor 5Z assigned to the seat shorts, for example, the series resistance r1 in the load detection sensor 5Z The combined resistance of the parallel resistor R1 is almost zero.

  In the load detection device 100 of the present embodiment, the resistance values of the series resistors r1 to r3 and the resistance values of the parallel resistors R1 to R3 are different from each other, and the series resistances r1 and r2 of the load detection sensors 5X, 5Y, and 5Z, respectively. , R3 and parallel resistors R1, R2, and R3 are different from each other.

  For this reason, as shown in Table 1 other than “No short”, the load detection sensors 5X to 5X to 5F are changed according to the combination of ON and OFF of the switches SW1 and SW2 of the remaining load detection sensors 5X and 5Y. The total (sum) of the combined resistance of 5Z is also different. That is, even if a part or all of the load detection sensors 5X to 5Z have a failure, the inter-terminal resistance values viewed from the pair of terminals 8T1 and 8T2 are ON of the switches SW1 to SW3 of the load detection sensors 5X to 5Z. It will be different for each combination of and off.

  Therefore, in the load detection device 100 of the present embodiment, the signal given from the load detection device 100 via the pair of terminals 8T1 and 8T2 to the engine control unit ECU electrically connected to the pair of terminals 8T1 and 8T2. Based on the level, the presence / absence of seating and the presence / absence of failure can be individually detected for a plurality of seats.

  In the case of the present embodiment, the resistance value (400Ω) of the parallel resistance R1 that is the minimum among the resistance values of the parallel resistances R1 to R3 in the load detection sensors 5X to 5Z is the value of the load detection sensors 5X to 5Z. It is larger than the combined resistance value (350Ω) of the series resistors r1 to r3.

  For this reason, compared with the change of the resistance value between terminals seen from a pair of terminals 8T1 and 8T2 when there is a failure, the change of the resistance value between terminals seen from a pair of terminals 8T1 and 8T2 when there is a seating becomes larger. In addition, the change width of the resistance value of the series resistors r1 to r3 corresponding to the one not giving priority to detection is smaller than the minimum resistance value of the resistance values of the parallel resistors R1 to R3 corresponding to the one giving priority to the detection. Therefore, it is possible to detect seating with priority.

  In the case of the present embodiment, the resistance values of the parallel resistors R1 to R3 in the respective load detection sensors 5X to 5Z are larger than the resistance values of the series resistors r1 to r3 in the respective load detection sensors 5X to 5Z.

  Therefore, the load can be detected more easily in preference to a failure that is generally difficult to occur.

  Furthermore, in the case of this embodiment, the connectors 31X to 31Z are connected to the load detection sensors 5X to 5Z, and the load detection sensors 5X to 5Z can be individually attached and detached by the connectors 31X to 31Z.

  Therefore, for example, when one of the load detection sensors 5X to 5Z fails, only the failed load detection sensor 5X can be easily replaced without replacing the entire load detection sensors 5X to 5Z. .

  Further, in the case of the present embodiment, the parallel resistors R1 to R3 and the series resistors r1 to r3 of each of the plurality of load detection sensors 5X to 5Z are chip resistors.

  In general, the resistance value of the chip resistor can be set more accurately than the printing resistor. Therefore, in this embodiment, the presence / absence of seating and the presence / absence of failure can be detected more clearly.

  Further, in the case of the present embodiment, the load detection sensors 5X to 5Z include a substrate 51 having a first electrode 52 and a second electrode 62 that is disposed on one surface F1 of the substrate 51 via a spacer 70. A two-electrode sheet 60. And parallel resistance R1-R3 and series resistance r1-r3 which are chip resistance are arrange | positioned on the other surface F2 on the opposite side to one surface F1 of the board | substrate 51 with which the spacer 70 opposes.

  Although the thickness of the chip resistor is generally larger than the thickness of the printing resistor, in this embodiment, the side of the substrate 51 opposite to the side where the first electrode 52 facing the second electrode 62 is disposed. Since it arrange | positions on the other surface F2, it can avoid that the sensitivity of the load detection sensor 5X deteriorates by the thickness of chip resistance.

  By the way, in the load detection sensor 5X of this embodiment, the circuit site | part formed in the 1st electrode sheet 50 via the 1st contact part 53 of the 1st electrode sheet 50, and the 2nd contact part 63 of the 2nd electrode sheet 60. And the circuit part formed in the second electrode sheet 60 are always in a conductive state. Therefore, each of the pair of terminals TLX1 and TLX2 can be arranged on the first electrode sheet 50.

  Further, in the load detection sensor 5 </ b> X of the present embodiment, a portion including the second contact portion 63 in the second electrode sheet 60 is a leaf spring that presses the second contact portion 63 against the first contact portion 53. For this reason, the other member for maintaining the 1st contact part 53 and the 2nd contact part 63 in a connection state always can be made unnecessary. Therefore, an increase in the number of parts can be suppressed and miniaturization can be achieved.

  Further, in the load detection sensor 5 </ b> X of the present embodiment, the second electrode sheet 60 is a metal sheet 61. For this reason, since there is little influence by the heat in the 2nd electrode sheet 60, even if it uses in high temperature environment or low temperature environment, the sensitivity of load detection sensor 5X is stabilized. Moreover, since the 2nd electrode sheet 60 is a metal, damage etc. can be reduced and durability can be improved. Furthermore, since the second contact portion 63 that is a leaf spring in the second electrode sheet 60 is also a metal, the second contact formed as the leaf spring is compared with a case where a part of the resin sheet is a leaf spring. The malleability and ductility of the part 63 can be increased. Accordingly, it is possible to reduce breakage such as breakage of the second contact portion 63 formed as a leaf spring and improve the durability of the leaf spring.

  In the load detection sensor 5 </ b> X of the present embodiment, the first sheet that penetrates from the one surface F <b> 1 facing the second electrode sheet 60 to the other surface F <b> 2 is the first sheet 51. It has a through hole 55A. Further, the first electrode 52 is electrically connected to a circuit portion disposed on the other surface F2 of the substrate 51 through a first conductive member CPA provided in the first sheet through hole 55A. For this reason, it becomes possible to take out one terminal TLX1 to the other surface F2 of the substrate 51. As in the present embodiment, the terminal TLX1 can be disposed inside the pin through hole 55E different from the first sheet through hole 55A. Therefore, it becomes simple when connecting the load detection sensor unit SU to another electronic component such as the connector 31X. Further, since the circuit part can be provided on the other surface F2, it is not necessary to provide the circuit part on the one surface F1, and unevenness due to the circuit part on the one surface F1 can be reduced. Thereby, the sensitivity of the load detection sensor 5X can be stabilized.

  Furthermore, in the load detection sensor 5 </ b> X of the present embodiment, the opening on the one surface side of the first sheet through hole 55 </ b> A is located in the region where the first electrode 52 is disposed on the one surface F <b> 1 of the substrate 51. The first sheet through hole 55 </ b> A has an air hole SP that communicates with the opening 71 between the first electrode 52 and the second electrode 62 via the electrode through hole 52 </ b> A provided in the first electrode 52. For this reason, the first sheet through-hole 55 </ b> A is a connection hole for electrically connecting the first electrode 52 disposed on the one surface F <b> 1 of the substrate 51 to the circuit portion on the other surface side of the substrate 51. In addition, it also serves as an exhaust hole for discharging the spacer air to the outside. For this reason, durability of the board | substrate 51 can be improved compared with the case where a connection hole and an exhaust hole are provided separately. Further, it is not necessary to provide a separate exhaust hole, and space can be saved.

  Furthermore, in the load detection sensor 5X of the present embodiment, the substrate 51 serving as the sheet of the first electrode sheet 50 is located at a position different from the first sheet through hole 55A from one surface F1 facing the second electrode sheet 60. It has the 2nd sheet penetration hole 55B which penetrates to the other field F2. Further, the first contact portion 53 is electrically connected to a circuit portion disposed on the other surface F2 of the substrate 51 through a second conductive member CPB provided in the second sheet through hole 55B. For this reason, the pair of terminals TLX1 and TLX2 can be taken out from the other surface F2 of the substrate 51. As in the present embodiment, the terminals TLX1 and TLX2 can be arranged inside the pin through holes 55E and 55F different from the first sheet through hole 55A. Therefore, it becomes simple when connecting the load detection sensor unit SU to another electronic component such as the connector 31X. Further, since the circuit part can be provided on the other surface F2, it is not necessary to provide the circuit part on the one surface F1, and unevenness due to the circuit part on the one surface F1 can be reduced. Thereby, the sensitivity of the load detection sensor 5X can be stabilized.

  Further, in the load detection sensor 5X of the present embodiment, a parallel resistor R1 and a series resistor r1 are disposed on the other surface F2 of the substrate 51. For this reason, even if the thickness of the parallel resistance R1 and the series resistance r1 is large, it can be avoided that the sensitivity of the load detection sensor 5X is deteriorated due to the thickness.

  In the present embodiment, the circuit portion, the series resistance r1 and the parallel resistance R1 in the first electrode sheet 50 are provided on the other surface F2 of the substrate 51, and the pair of terminals TLX1 and TLX2 are in the pin through holes 55E and 55F. Is provided. For this reason, components other than the 1st electrode 52 and the 1st contact part 53 can be excluded from one surface F1 of the board | substrate 51. FIG. Therefore, the unevenness | corrugation by other components can be eliminated in one surface F1 of the board | substrate 51, and the sensitivity of the load detection sensor 5X can be improved more.

(2) Second Embodiment Next, a second embodiment of the present invention will be described. In the description of the present embodiment, the same or equivalent components as those in the first embodiment are denoted by the same reference numerals, and redundant description is omitted unless specifically described.

  FIG. 9 is a schematic diagram illustrating the configuration of the load detection device 200 according to the second embodiment. As shown in FIG. 9, the load detection device 200 in the present embodiment includes a plurality of load detection sensor units 1 </ b> A to 1 </ b> C and a cable 7.

  Each of the load detection sensor units 1A to 1C is disposed, for example, below a seat cushion in a vehicle seat device, and one load detection sensor unit 1A, 1B, 1C is assigned to each seat cushion.

  The load detection sensor unit 1A includes a switch SW1, and a load detection sensor 5A having a series resistance r1 and a parallel resistance R11. The parallel resistor R11 is connected in parallel to the switch SW1 and the series resistor r1. In this load detection sensor unit 1A, there is no connector 31X as in the first embodiment, and the wiring of the load detection sensor 5A and the wiring of the cable 7 are electrically and mechanically connected by, for example, soldering or welding. .

  The load detection sensor unit 1B includes a switch SW2, and a load detection sensor 5B having a series resistance r2 and a parallel resistance R12. The parallel resistor R12 is connected in parallel to the switch SW2 and the series resistor r2. In this load detection sensor unit 1B, there is no connector 31Y as in the first embodiment, and the wiring of the load detection sensor 5B and the wiring of the cable 7 are electrically and mechanically connected by, for example, soldering or welding. .

  The load detection sensor unit 1C includes a switch SW3, and a load detection sensor 5C having a series resistance r3 and a parallel resistance R13. The parallel resistor R13 is connected in parallel to the switch SW3 and the series resistor r3. In this load detection sensor unit 1C, there is no connector 31Z as in the first embodiment, and the wiring of the load detection sensor 5C and the wiring of the cable 7 are electrically and mechanically connected by, for example, soldering or welding. .

  The cable 7 connects each of the load detection sensor units 1A to 1C and the engine control unit ECU, and has a connector 8 on the engine control unit side. The cable 7 does not have the connectors 9X to 9Z on the load detection sensor unit side in the cable 6 of the first embodiment, and each load detection is provided at a predetermined portion of the cable wiring 7w connected to the connector 8 on the engine control unit side. Signal cables 19 of the sensors 5A to 5C are connected.

  FIG. 10 is a diagram illustrating an equivalent circuit of the load detection device 200 according to the second embodiment. As shown in FIG. 10, in the load detection device 200, the load detection sensors 5 </ b> A to 5 </ b> C are disposed between the pair of terminals 8 </ b> T <b> 1 and 8 </ b> T <b> 2 of the connector 8 in the cable 7. Connected in series.

  The total combined resistance of the load detection sensors 5A to 5C is different for each combination of ON and OFF of the switches SW1 to SW3. Further, the resistance values of the series resistors r1 to r3 and the resistance values of the parallel resistors R11 to R13 are different from each other, and the series resistors r1, r2, and r3 and the parallel resistors R11 and R12 of the load detection sensors 5A, 5B, and 5C, respectively. , R13 are different from each other.

  In the case of the present embodiment, the resistance values of the parallel resistors R11 to R13 are made larger than the resistance values of the series resistors r1 to r3, respectively, and the minimum resistance value among the resistance values of the parallel resistors R11 to R13 is the series resistors r1 to r3. The combined resistance value is made larger. For example, as in the first embodiment, the resistance values of the series resistors r1, r2, and r3 and the resistance values of the parallel resistors R1, R2, and R3 are all 1: 2: 4.

  In such a load detection device 200, as in the first embodiment, when the load detection sensors 5A to 5C are not short-circuited, one, two, or all of the load detection sensors 5A to 5C are short-circuited. In this case, the total combined resistance of the load detection sensors 5A to 5C is different for each combination of ON and OFF of the load detection sensors 5A to 5C.

  Next, the configuration of the load detection sensor units 1A to 1C will be described. However, since the configurations of the load detection sensor units 1A to 1C are the same, only the configuration of the load detection sensor unit 1A will be described.

  FIG. 11 is an exploded view showing the configuration of the load detection sensor unit 1A in the second embodiment, and FIG. 12 is a view of the load detection sensor unit 1A of FIG. 11 viewed from another angle. FIG. 13 is a cross-sectional view of the load detection sensor unit 1A shown in FIGS. In FIG. 13, the load detection sensor 5 </ b> A is simplified to avoid complication of the drawing.

  As shown in FIGS. 11 to 13, the load detection sensor unit 1 </ b> A of the present embodiment includes a housing 3 </ b> A, a housing cover 4 </ b> A, and a load detection sensor 5 </ b> A as main components. Although the pedestal is not described in FIGS. 8 to 10, in the present embodiment, the load detection sensor unit 1 </ b> A may or may not include the pedestal.

  As shown in FIGS. 11 and 12, the housing 3 </ b> A includes a bottom wall 87, a plurality of frame walls 88, and a plurality of arms 81. The bottom wall 87 has a substantially circular plate shape, and frame walls 88 are connected to three locations on the outer periphery of the bottom wall 87. The frame wall 88 has an outer shape that is substantially the same as the outer periphery of the bottom wall 87, and an inner shape that is flat. A plurality of through holes 30 </ b> H are formed in the bottom wall 87.

  The respective frame walls 88 are arranged in directions that form 90 degrees with respect to the approximate center of the substantially circular bottom wall 87, and the inner side surfaces of the adjacent frame walls 88 form 90 degrees and face each other. The inner side surfaces 89 of the frame wall 88 are opposed to each other. These inner side surfaces 89 are substantially parallel to any of the lines connecting the centers of the adjacent through holes 30H. An arm 81 is connected to the outer periphery of each frame wall 88. Each arm 81 is provided with an opening 82. Further, the frame wall 88 and the arm 81 are provided in three places in the present embodiment, and are not provided in the direction in which the load detection sensor unit 1A extends.

  The housing cover 4A is a lid member that covers the bottom wall 87 and the frame wall 88, and is a pressing member that presses the switch SW1 of the load detection sensor 5A when pressed by the seat cushion SC shown in FIG. The housing cover 4A has a top wall 45 and a frame wall 48b. The top wall 45 is a substantially circular plate member. Further, the frame wall 48 b of the housing cover 4 </ b> A is divided into a plurality of parts and connected to the outer periphery of the top wall 45. A hook piece 48a is connected to the top wall 45 between each of the frame walls 48b divided into a plurality. Each hook piece 48a is configured to be fitted into an opening 82 formed in the arm 81 of the housing 3A. By fitting each hook piece 48a into the opening 82, relative movement between the housing 3A and the housing cover 4A along the surface direction of the bottom wall 87 and the top wall 45 is restricted.

  A switch pressing portion 46 is provided on the top wall 45 of the housing cover 4A so as to protrude from the inner surface facing the bottom wall 87 of the housing 3A. The switch pressing portion 46 has the same shape as the switch pressing portion 43 of the first embodiment except that the tip is flat, but the tip may be a convex curved surface. The top wall 45 of the housing cover 4A is provided with a plurality of ribs 49 protruding from the inner surface on the same side as the side on which the switch pressing portion 46 is provided. These ribs 49 are formed at positions overlapping the plurality of through holes 30H formed in the bottom wall 87 of the housing 3A. These ribs 49 are inserted into the respective through holes 30H in a state in which the housing cover 4A covers the housing 3A and the respective hook pieces 48a are fitted in the respective openings 82. Further, in this state, the switch pressing portion 46 comes into contact with the load detection sensor 5A. Accordingly, in the same manner as the switch pressing portion 43 of the first embodiment, the tip of the switch pressing portion 46 is in the state where the housing cover 4A is not pressed against the seat cushion SC as will be described later. In contact with the switch SW1.

  In the present embodiment as well, the housing cover 4A is formed of a material harder than the seat cushion SC as in the first embodiment, and the switch pressing portion 46, which is a part of the housing cover 4A, is also formed from the seat cushion SC. Is also made of a hard material. Therefore, the housing cover 4A of the present embodiment is made of the same material as the housing cover 4A of the first embodiment.

  Thus, with the switch pressing portion 46 of the housing cover 4A in contact with the load detection sensor 5A, the top wall 45 of the housing cover 4A and the frame wall 88 of the housing 3A are separated as shown in FIG. A gap GA is formed.

  With the load detection sensor unit 1A assembled in this manner disposed below the seat cushion SC of the seat device, the upper surface 45S of the top wall 45 of the housing cover 4A is spaced a predetermined distance from the lower surface of the seat cushion SC. Facing each other. The upper surface 45S is planar. The upper surface 45S is a pressure receiving surface that receives pressure from the seat cushion SC, and can be understood as the pressure receiving surface of the load detection sensor unit 1A. The area of the upper surface 45S is the portion of the switch pressing portion 46 that contacts the load detection sensor 5A. It is larger than the area.

  Next, the load detection sensor 5A of this embodiment will be described.

  FIG. 14 is an exploded view showing the load detection sensor 5A shown in FIGS. However, for easy understanding, the viewing direction is changed between FIG. 11 and FIG. 12 and FIG. As shown in FIGS. 11 to 14, the load detection sensor 5 </ b> A of this embodiment includes a switch sheet 50 </ b> A having a switch SW and a metal plate 60 </ b> A.

  As shown in FIGS. 11 and 12, the switch sheet 50A of the present embodiment is a sheet-like membrane switch. The switch seat 50A includes a substantially rectangular main block 50m and a tail block 50t that is connected to the main block 50m and is narrower than the main block 50m. The main block 50m is provided with a switch SW. The tail block 50t is formed with a wide blade portion 50f. Further, through holes 50H are formed in the vicinity of each vertex of the main block 50m.

  As shown in FIG. 14, the switch sheet 50 </ b> A of this embodiment includes a first electrode sheet 56, a spacer 58, and a second electrode sheet 57.

  The first electrode sheet 56 mainly includes a first insulating sheet 56s, a first electrode 56e, and a first terminal 56c.

  The first insulating sheet 56s is a flexible insulating sheet, and is substantially the same as the main block 56m having the same shape as the main block 50m of the switch sheet 50A, and the tail block 50t of the switch sheet 50A connected to the main block 56m. The tail block 56t has the same shape. The shape of the tail block 56t is different from the shape of the tail block 50t of the switch seat 50A in that the tip portion opposite to the main block 56m is narrower than the other portion of the tail block 56t. Further, a through hole 56H is formed in the main block 56m at the same position as the through hole 50H of the switch seat 50A. Examples of the material of the first insulating sheet 56s include resins such as PET, PI, and PEN.

  The first electrode 56e is provided on one surface in the approximate center of the main block 56m. The first electrode 56e is made of a conductor layer, for example, a substantially circular metal printing layer. The first terminal 56c is made of a conductor layer, for example, a substantially rectangular metal layer. The first terminal 56c is provided on the surface of the tail block 56t on the side where the first electrode 56e is provided. The first electrode 56e and the first terminal 56c are electrically connected to each other via the first wiring 56w.

  The second electrode sheet 57 mainly includes a second insulating sheet 57s, a second electrode 57e, a second terminal 57c, and a series resistor r1.

  The second insulating sheet 57s is an insulating sheet similar to the first insulating sheet 56s. In the case of this embodiment, the second insulating sheet 57s includes a main block 57m having the same shape as the main block 56m of the first insulating sheet 56s, and the tail block 56t of the first insulating sheet 56s connected to the main block 57m and other than the tip portion. The tail block 57t has the same shape. The tip portion of the tail block 57t has a narrower width than other portions of the tail block 57t, and when the first insulating sheet 56s and the second insulating sheet 57s are overlapped, the tail block 56t of the first insulating sheet 56s. The tip portion of the second insulating sheet 57s and the tip portion of the tail block 57t of the second insulating sheet 57s do not overlap each other. Further, in the main block 57m, a through hole 57H is formed at the same position as the through hole 50H of the switch sheet 50A in the same manner as the first insulating sheet 56s. As the material of the second insulating sheet 57s, a resin such as PET, PI, or PEN can be used similarly to the first insulating sheet 56s. The material of the second insulating sheet 57s is the same as the material of the first insulating sheet 56s. They can be the same or different.

  The second electrode 57e has the same configuration as that of the first electrode 56e, and is provided on one surface of the second insulating sheet 57s in the approximate center of the main block 57m. The position where the second electrode 57e is provided is a position that overlaps the first electrode 56e when the first electrode sheet 56 and the second electrode sheet 57 are overlapped. The second terminal 57c has the same configuration as that of the first terminal 56c, and is provided on the surface of the tail block 57t on the side where the second electrode 57e is provided. In addition, as described above, when the first insulating sheet 56s and the second insulating sheet 57s are overlapped, the tip portions of the respective insulating sheets do not overlap with each other, so the first terminal 56c and the second terminal 57c are not insulated from each other. The sheet 56s and the second insulating sheet 57s are not positioned and are exposed. The second electrode 57e and the second terminal 57c are electrically connected to each other through the second wiring 57w.

  The series resistor r1 is disposed in the middle of the second wiring 57w, and is electrically and mechanically connected to the second wiring 57w. The series resistance r1 is a chip resistance in the first embodiment, but is a printing resistance in the present embodiment. When the first insulating sheet 56s and the second insulating sheet 57s are attached with the spacer 58 interposed therebetween, the first electrode 56e and the second insulating sheet of the first insulating sheet 56s are caused by the thickness of the series resistance r1. The distance from the 57s second electrode 57e is prevented from increasing.

  The spacer 58 is an insulating sheet having flexibility, and includes a main block 58m and a tail block 58t connected to the main block 58m. The main block 58m has the same outer shape as the main blocks 56m and 57m of the first insulating sheet 56s and the second insulating sheet 57s. Further, the main block 58m has an opening 58c formed in the center, and in the same manner as the first insulating sheet 56s and the second insulating sheet 57s, a through hole is formed at the same position as the through hole 50H of the switch sheet 50A. 58H is formed. The tail block 58t has a shape excluding the narrow tip portions of the tail blocks 56t and 57t of the first insulating sheet 56s and the second insulating sheet 57s.

  The opening 58c has a substantially circular shape, and has a diameter slightly smaller than the diameters of the first electrode 56e and the second electrode 57e. When the spacer 58 is overlapped with the first electrode sheet 56 and the second electrode sheet 57 and the spacer 58 is viewed in plan, the opening 58c is located inside the peripheral edges of the first electrode 56e and the second electrode 57e. It is formed to be located. Further, the spacer 58 is formed with a slit 58b that connects the space in the opening 58c and the space outside the switch sheet 50A. The slit 58b serves as an air vent when the first electrode sheet 56, the spacer 58, and the second electrode sheet 57 are overlapped.

  As the material of the spacer 58, a resin such as PET, PI, or PEN can be used as in the first insulating sheet 56s and the second insulating sheet 57s. The material of the spacer 58 may be the same as or different from the material of the first insulating sheet 56s or the second insulating sheet 57s. Further, an adhesive (not shown) for bonding the first electrode sheet 56 and the second electrode sheet 57 is applied to both surfaces of the spacer 58.

  With the first electrode sheet 56, the spacer 58, and the second electrode sheet 57 adhered in this order, the first electrode 56e, the first wiring 56w, and the second electrode sheet 57 of the first electrode sheet 56 are attached. The second electrode 57e and the second wiring 57w are located between the first insulating sheet 56s and the second insulating sheet 57s. The first electrode 56e and the second electrode 57e are opposed to each other through the opening 58c to configure the switch SW1. In addition, in a state where the first electrode sheet 56, the spacer 58, and the second electrode sheet 57 are overlapped, the respective through holes 56H, 57H, and 58H overlap each other to form the through hole 50H of the switch sheet 50A.

  The signal cable 19 connected to the connector terminal of the connector 31X (FIG. 9) in the load detection sensor unit 1A is connected to the first terminal 56c and the second terminal 57c of the switch sheet 50A. A parallel resistor R11 is disposed between the first terminal 56c and the second terminal 57c. One wiring connected to the parallel resistor R11 is connected to the first terminal 56c, and the other wiring connected to the parallel resistor R11 is connected to the second terminal 57c.

  The ends of the tail block 50t of the switch seat 50A including the first terminal 56c and the second terminal 57c, the parallel resistor R11 connected to the first terminal 56c and the second terminal 57c, and a part of the signal cable 19 are illustrated in FIG. 11 and FIG. 12, it is covered with a terminal sealing resin 18. The terminal sealing resin 18 is made of, for example, hot melt or photo-curing resin. Thus, the signal cable 19 and the parallel resistor R11 are prevented from being disconnected from the first terminal 56c and the second terminal 57c, and the first terminal 56c and the second terminal 57c are short-circuited by conductive dust or the like. It is suppressed. The signal cable 19 is connected to the cable wiring 7w of the cable 7 as shown in FIGS.

  The metal plate 60A is made of a flexible metal plate material. The metal plate 60A is made of the same material as the metal sheet 61 of the second electrode sheet 60 in the first embodiment, for example. The metal plate 60A has substantially the same shape as the main block 50m of the switch sheet 50A, and a through hole 60H is formed at the same position as the through hole 50H of the switch sheet 50A. Therefore, when the switch sheet 50A and the metal plate 60A are overlapped, the through hole 50H of the switch sheet 50A and the through hole 60H of the metal plate 60A overlap each other. Further, when the switch sheet 50A and the metal plate 60A are overlapped, the metal plate 60A covers the switch SW of the switch sheet 50A. Specifically, as is apparent from FIG. 11, the metal plate 60A is provided on the opposite side of the first insulating sheet 56s from the spacer 58, and on the seat cushion SC side of the first electrode 56e and the second electrode 57e. The positioned first electrode 56e is covered from the seat cushion SC side. In the present embodiment, the metal plate 60A and the first insulating sheet 56s (switch sheet 50A) are not bonded to each other, but may be bonded to each other.

  As described above, in the load detection device 200 of the present embodiment, the plurality of load detection sensors 5A to 5C are connected in series between the pair of terminals 8T1 and 8T2. Each of the load detection sensors 5A to 5C includes switches SW1 to SW3, series resistors r1 to r3, and parallel resistors R11 to R13 connected in parallel to the switches SW1 to SW3 and the series resistors r1 to r3.

  In such a load detection device 200, for example, in the load detection sensor 5A assigned to the seat in the seated state among the load detection sensors 5A to 5C, the switch SW1 included in the load detection sensor 5A is turned on, and the resistance value in the load detection sensor 5A is It becomes the value of the combined resistance of r1 and the parallel resistance R11. On the other hand, in the load detection sensor 5B assigned to a seat that is not in the seating state, for example, the switch SW2 that the load detection sensor 5B has is turned off, and the resistance value of the load detection sensor 5B becomes the value of the parallel resistance R12.

  In the load detection device 200 according to the present embodiment, the total combined resistance of the load detection sensors 5A to 5C is different for each combination of ON and OFF of the switches SW1 to SW3.

  For this reason, the resistance value between terminals seen from the pair of terminals 8T1 and 8T2 is different for each combination of ON and OFF of the switches SW1 to SW3 of the load detection sensors 5A to 5C, as in the first embodiment. become.

  On the other hand, among the load detection sensors 5A to 5C, when an occupant seated in the seat spills a drink, for example, and the load detection sensor 5A assigned to the seat shorts, for example, the series resistance r1 in the load detection sensor 5A The combined resistance of the parallel resistor R11 is almost zero.

  In the load detection device 200 of the present embodiment, the resistance values of the series resistors r1 to r3 and the resistance values of the parallel resistors R11 to R13 are different from each other, and the series resistances r1 and r2 of the load detection sensors 5A, 5B, and 5C, respectively. , R3 and parallel resistors R11, R12, R13 are different from each other.

  For this reason, as in the first embodiment, the total (sum) of the combined resistances of the load detection sensors 5A to 5C according to the combination of the on and off of the switches SW2 and SW3 of the remaining load detection sensors 5B and 5C. ) Is also different. That is, even if some or all of the load detection sensors 5A to 5C have a failure, the resistance value between the terminals viewed from the pair of terminals 8T1 and 8T2 is the same as that of the first embodiment. It will be different for each combination of ON and OFF of the switches SW1 to SW3 of ˜5C.

  As a result, even in the case of the present embodiment, signals given from the load detection device 100 via the pair of terminals 8T1 and 8T2 to the engine control unit ECU electrically connected to the pair of terminals 8T1 and 8T2 The presence / absence of seating and the presence / absence of a failure can be individually detected based on the level of each.

  As mentioned above, although the said embodiment was demonstrated to the example about the load detection apparatus of this invention, this invention is not limited to the said embodiment.

  For example, in the first embodiment, the parallel resistors R1 to R3 of the load detection sensors 5X to 5Z in the load detection sensor units 1X to 1Z are connected in parallel to the switches SW1 to SW3. In the second embodiment, the parallel resistors R11 to R13 of the load detection sensors 5A to 5C in the load detection sensor units 1A to 1C are connected in parallel to the switches SW1 to SW3 and the series resistors r1 to r3. . However, the parallel resistors R1 to R3 of the load detection sensors 5X to 5Z in the first embodiment may be connected in parallel to the switches SW1 to SW3 and the series resistors r1 to r3. Further, the parallel resistors R11 to R13 of the load detection sensors 5A to 5C in the second embodiment may be connected in parallel only to the switches SW1 to SW3.

Moreover, in the said embodiment, the resistance value of parallel resistance R1, R11 which becomes the minimum among the resistance values of parallel resistance R1-R3, R11-R13 is combined resistance value of series resistance r1-r3 (each series resistance r1- (total resistance value of r3). However, the minimum resistance value among the resistance values of the series resistors r1 to r3 may be larger than the combined resistance value of the parallel resistors R1 to R3 and R11 to R13.
In this case, the change in the resistance value between the terminals viewed from the pair of terminals 8T1 and 8T2 when there is a failure is larger than the change in the resistance value between the terminals 8T1 and 8T2 when there is a seating. . In addition, the change widths of the resistance values of the parallel resistors R1 to R3 and R11 to R13 corresponding to those not prioritizing detection are smaller than the minimum resistance values of the resistance values of the series resistors r1 to r3 corresponding to those prioritizing the detection. Becomes smaller. Therefore, it becomes possible to detect failure with priority. Thus, it is useful when priority is given to detecting a failure.

  Note that when the failure is preferentially detected as described above, the resistance values of the series resistors r1 to r3 may be larger than the resistance values of the parallel resistors R1 to R3 and R11 to R13. In this way, it is possible to more easily detect the failure with priority over the load.

  In the first embodiment, the substrate 51 having the first electrode 52, the metal sheet 61 that also serves as the second electrode 62 that is spaced apart from the first electrode 52, and the substrate 51 and the metal sheet 61 are disposed. The load detection sensors 5X to 5Z having a structure including the spacer 70 to be used are employed. In the second embodiment, the first insulating sheet 56s having the first electrode 56e, the second insulating sheet 57s having the second electrode 57e facing away from the first electrode 56e, and the first insulating sheet 56s. And the load detection sensors 5A-5C of the structure containing the spacer 58 arrange | positioned between 57 s of 2nd insulating sheets were employ | adopted. However, the load detection sensor includes a switch composed of a pair of electrodes opposed to each other, a series resistance connected in series to the switch, and a parallel resistance connected in parallel to the switch. The structure of the load detection sensor is not particularly limited.

  It should be noted that the components in the load detection devices 100 and 200 are appropriately combined, omitted, modified, or added with a well-known technique within the scope not departing from the purpose of the present application, other than the contents shown in the above-described embodiments and the above-described modifications. And so on.

  The present invention can be used as long as the presence / absence of a load and the presence / absence of a failure are individually detected for a plurality of objects to be detected. That is, in the said embodiment, it arrange | positions at the several seat of a vehicle, and the presence or absence of a person's seating and the presence or absence of a failure were detected separately, However, Not only the said embodiment but another form is employable. For example, the form which arrange | positions the load detection apparatus 100 or 200 for every some division allocated to one nursing bed mat, such as dividing one nursing bed mat into front and rear, right and left, is mentioned. Even in such a configuration, it is possible to detect the presence or absence of a load indicating the location of a person on the bed mat and the presence or absence of a failure using the load detection device of each section.

DESCRIPTION OF SYMBOLS 100,200 ... Load detection apparatus 1X-1Z, 1A-1C ... Load detection sensor unit 3X, 3A ... Housing 4X, 4A ... Housing cover 5X-5Z, 5A-5C ... Load detection Sensor 6, 7 ... Cable 90 ... S spring AP ... Connection maintaining part SC ... Seat cushion SW1-SW3 ... Switch r1-r3 ... Series resistance R1-R3, R11-R13 ..Parallel resistance

Claims (5)

A load detection sensor having a switch composed of a pair of electrodes opposed to each other, a series resistance connected in series to the switch, and a parallel resistance connected in parallel to the switch Provided between a pair of terminals,
Each of the load detection sensors is connected in series with each other,
The total of the combined resistance of each of the load detection sensors is different for each combination of ON and OFF of each of the switches,
Unlike resistance value and the resistance value of each of the parallel resistance of each of the series resistance to each other, the resistance value of the series resistor for each of the load sensor and the resistance value of the parallel resistance varies with each other,
The minimum resistance value among the resistance values of the parallel resistors among all the load detection sensors is larger than a combined resistance value obtained by combining the resistance values of the series resistors of all the load detection sensors. A load detection device characterized by that. A load detection sensor having a switch composed of a pair of electrodes opposed to each other, a series resistance connected in series to the switch, and a parallel resistance connected in parallel to the switch Provided between a pair of terminals,
Each of the load detection sensors is connected in series with each other,
The total of the combined resistance of each of the load detection sensors is different for each combination of ON and OFF of each of the switches,
The resistance value of each series resistance and the resistance value of each parallel resistance are different from each other, and the resistance value of the series resistance and the resistance value of the parallel resistance are different from each other for each load detection sensor,
The minimum resistance value among the resistance values of the series resistors among all the load detection sensors is larger than the combined resistance value obtained by combining the resistance values of the parallel resistors of all the load detection sensors.
A load detection device characterized by that. Each of the load sensing sensor load detection device according to claim 1 or claim 2, characterized in that it is a individually detachable. A plurality of the load detecting sensor of each of the parallel resistor and the series resistance, load sensing device according to any one of claims 1 to claim 3, characterized in that the chip resistor. The load detection sensor includes a substrate having one of the pair of electrodes, and an electrode sheet disposed on one surface of the substrate via a spacer and having the other of the pair of electrodes,
The load detection device according to claim 4 , wherein the chip resistor is disposed on the other surface opposite to the one surface of the substrate facing the spacer.

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