buckle

Abstract

To measure motion of a tongue relative to a buckle in a state that a plate of the tongue is inserted into the buckle.SOLUTION: A buckle includes: a buckle body formed with an insertion port into which a plate of a tongue attached to a seat belt of a vehicle is inserted; an exterior cover which houses the buckle body; a lever which is rotationally moved by a load received from the plate inserted into the insertion port; an elastic body which is deformed by rotational movement of the lever; a sensor which outputs a signal according to deformation of the elastic body; and a processing part which processes the signal output from the sensor.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present disclosure relates to a buckle. [Background technology]

[0002] Conventionally, there has been known a buckle equipped with a pressure sensor that detects the breathing of an occupant by detecting pressure changes caused by changes in the tension of the seat belt, focusing on the fact that the tension of the seat belt changes due to the breathing of an occupant wearing the seat belt (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-290324 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the conventional pressure sensor is disposed between the buckle and an attachment member provided outside the buckle, and therefore, although the conventional pressure sensor can measure the movement of the buckle relative to the attachment member when the tongue plate is inserted into the buckle, it is difficult to measure the movement of the tongue relative to the buckle.

[0005] The present disclosure provides a buckle that can measure the movement of a tongue relative to the buckle when the tongue plate is inserted into the buckle. [Means for solving the problem]

[0006] In one aspect of the present disclosure, a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor is provided. Effect of the Invention

[0007] According to one aspect of the present disclosure, the movement of the tongue relative to the buckle can be measured with the tongue plate inserted into the buckle. [Brief description of the drawings]

[0008] [Figure 1] FIG. 2 is a front view of the appearance of the buckle according to the embodiment. [Diagram 2] 2 is a cross-sectional view taken along line AA of the buckle according to the embodiment of the present invention. FIG. [Diagram 3] FIG. 2 is an exploded perspective view of the buckle according to the embodiment. [Figure 4] FIG. 2 is an exploded perspective view of some components of the buckle according to the embodiment. [Diagram 5] FIG. 4 is a cross-sectional view for explaining a mechanism for detecting tension of a seat belt. [Figure 6] FIG. 4 is a cross-sectional view for explaining a mechanism for detecting tension of a seat belt. [Figure 7] FIG. 4 is a cross-sectional view for explaining a mechanism for detecting tension of a seat belt. [Figure 8] 4A and 4B are diagrams illustrating a positional relationship between a leaf spring, which is an example of an elastic body, and a lever. [Figure 9] 13 is a diagram showing the underside of the lever (the surface facing the leaf spring). FIG. [Figure 10] 11 is a cross-sectional view illustrating a state in which the leaf spring is pressed by a first pressing portion. FIG. [Figure 11] 4 is a cross-sectional view illustrating a state in which the leaf spring is pressed by a first pressing portion and a second pressing portion. FIG. [Figure 12]FIG. 2 is a perspective view showing a leaf spring supported by a plurality of support members. [Figure 13] 11 is a diagram showing an example of the relationship between the load that the lever receives from the plate of the tongue and the rotation stroke length of the lever. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment will be described. For ease of understanding, the scale of each part in the drawings may differ from the actual scale. In directions such as parallel, right angle, orthogonal, horizontal, vertical, up and down, left and right, deviations that do not impair the effects of the embodiment are permitted. The shape of the corners is not limited to right angles, and may be rounded in an arch shape. The X-axis direction, the Y-axis direction, and the Z-axis direction respectively represent directions parallel to the X-axis, the Y-axis direction, and the Z-axis direction. The X-axis direction, the Y-axis direction, and the Z-axis direction are mutually orthogonal. The XY plane, the YZ plane, and the ZX plane respectively represent imaginary planes parallel to the X-axis direction and the Y-axis direction, imaginary planes parallel to the Y-axis direction and the Z-axis direction, and imaginary planes parallel to the Z-axis direction and the X-axis direction.

[0010] Fig. 1 is an external front view of the buckle according to this embodiment. Fig. 2 is a cross-sectional view of the buckle according to this embodiment taken along line AA. The X-axis direction represents the width direction of the buckle 8. The Y-axis direction represents the height direction of the buckle 8 when mounted on a vehicle. The Z-axis direction represents the thickness direction of the buckle 8.

[0011] The buckle 8 is a component to which a tongue 7 attached to a vehicle seat belt 4 is detachably connected, and is fixed, for example, to a seat on which an occupant sits or to a vehicle body in the vicinity of the seat. A flat plate 7a of the tongue 7 is inserted into and removed from the buckle 8. The tongue 7 is an example of a belt insertion tool through which the seat belt 4 is inserted, and is a component slidably attached to the seat belt 4. The seat belt 4 is a webbing that restrains an occupant seated in a vehicle seat, and is a belt-shaped member that is wound up in a retractor so as to be withdrawn.

[0012] The buckle 8 has a main body 8a and a stay 8b. The main body 8a is a portion to which the tongue 7 is detachably connected. The stay 8b is an example of a support member that supports the main body 8a of the buckle 8. The stay 8b is fixed to a seat on which a passenger sits or to a vehicle body in the vicinity of the seat.

[0013] When the tongue 7 is connected to the buckle 8, the portion of the seat belt 4 between the tongue 7 and a shoulder anchor (not shown) constitutes a shoulder belt portion 9 that restrains the chest and shoulders of the occupant. When the tongue 7 is connected to the buckle 8, the portion of the seat belt 4 between the tongue 7 and a belt anchor (not shown) constitutes a lap belt portion 10 that restrains the waist of the occupant.

[0014] Fig. 3 is an exploded perspective view of the buckle according to this embodiment. Fig. 4 is an exploded perspective view of some parts of the buckle according to this embodiment. As shown in Figs. 3 and 4, the buckle 8 (main body 8a) includes a buckle main body 8c, a circuit board 16, an upper cover 12, a lower cover 14, a lever 40, and a leaf spring 50.

[0015] The buckle body 8c is a sub-assembly that can be connected to the tongue 7 attached to the seat belt 4. The buckle body 8c has, for example, a button 31 that receives a push operation from the occupant's finger to release the connection between the tongue 7 and the buckle 8, and a buckle base 37 that holds the components of the buckle body 8c such as the button 31. The buckle body 8c is formed with an insertion opening 15 into which the metal plate of the tongue is inserted.

[0016] The upper cover 12 is a resin part that covers the buckle body 8c so as to expose the button 31. The upper cover 12 holds the buckle body 8c by sandwiching it between the upper cover 12 and the lower cover 14. In this embodiment, a lever 40 is attached to the upper cover 12. The lever 40 has a pivot 41 that protrudes in the X-axis direction, and is supported by the upper cover 12 to be rotatable around the pivot 41.

[0017] The circuit board 16 is fixed to the inner surface of the lower cover 14. In this embodiment, the circuit board 16 includes a sensor 20, a processing unit 60, and an output unit 80.

[0018] The sensor 20 detects tension (hereinafter also referred to as "tension N") acting on the seat belt 4, and outputs an output signal that changes in accordance with the detected tension N. When the seat belt 4 is fastened by an occupant, the movement of the occupant's chest and abdomen caused by the occupant's body movement and breathing is transmitted to the seat belt 4, causing the tension N of the seat belt 4 to change. The change in tension N of the seat belt 4 is transmitted to the tongue 7, and then transmitted to the buckle 8 via the tongue 7. The sensor 20 is provided in a main body 8a of the buckle 8.

[0019] The sensor 20 detects, for example, a deformation or displacement caused by a change in tension N of the seat belt 4 as tension N of the seat belt 4. For example, the sensor 20 is a strain sensor or a piezoelectric sensor that detects a change in the load input from the seat belt 4 to the buckle 8 via the tongue 7. The sensor 20 may be a capacitance sensor that detects a change in capacitance caused by a change in tension N of the seat belt 4.

[0020] Although the capacitance sensor is an example of a non-contact sensor, the sensor 20 may be a non-contact sensor of another sensing type. The sensor 20 may be an inductive sensor that detects a change in inductance caused by a change in tension N of the seat belt 4, or a magnetic sensor that detects a change in magnetism caused by a change in tension N of the seat belt 4. The sensor 20 may be a sensor that detects deformation or displacement caused by a change in tension N of the seat belt 4 by reflection of transmitted light or radio waves.

[0021] The processing unit 60 processes the sensor signal output from the sensor 20, for example, amplifying a small sensor signal. This makes it easier to handle a small analog sensor signal. The processing unit 60 may also perform filtering of the sensor signal.

[0022] For example, the processing unit 60 detects a vital sign, such as breathing or pulse, based on the tension change detected by the sensor 20. For example, the processing unit 60 detects the vital sign, such as breathing or pulse, by detecting periodicity of a signal component representing a change in tension N from the output signal of the sensor 20. This is because if there is periodicity, it is presumed that the periodic movement of breathing or pulse of an occupant wearing the seat belt 4 is detected as a tension change by the sensor 20. The processing unit 60 detects the vital sign by extracting a frequency component corresponding to the vital sign from the signal component representing the change in tension N detected by the sensor 20 using a predetermined filter. The breathing signal has a period of about 3 to 6 seconds, and the pulse signal has a period of about 0.5 to 1 second.

[0023] The processing unit 60 may detect the magnitude of a signal component representing the change in tension N from the output signal of the sensor 20. The processing unit 60 detects the magnitude of the tension N by detecting the magnitude of the signal component representing the change in tension N. This is because the magnitude of the signal component corresponds to the magnitude of the tension N.

[0024] The processing unit 60 may determine whether the object on the vehicle seat is a passenger or a child seat based on the detection state of the buckle switch and the detection state of the vital signs by the processing unit 60. A detailed determination method will be described later. A child seat, also called a CRS (Child Restraint System), is one of child restraint devices. The child seat is not limited to a seat for infants, but may be a seat for school children.

[0025] The processing unit 60 is, for example, an integrated circuit including one or more computers (specifically, microcomputers). The processing units 60 may be realized by different integrated circuits, or may be integrated into one integrated circuit. The computer has a processor such as a CPU (Central Processing Unit) and a memory. Each function of the processing unit 60 is realized by the processor operating according to a program stored in the memory. Each function of the processing unit 60 may be realized by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit).

[0026] The output unit 80 outputs the processing results by the processing unit 60 (e.g., a signal obtained by amplifying the sensor signal, the determination result of whether it is an occupant or a child seat, etc.) to an external device of the buckle 8 via wired or wireless communication. The external device executes a predetermined control based on the determination result. For example, if the external device determines that the object on the seat is an occupant, it determines that an airbag needs to be deployed, and if the object on the seat is determined to be a child seat, it determines that an airbag does not need to be deployed.

[0027] The output unit 80 outputs the result of the determination by the processing unit 60 to the outside of the buckle 8 by, for example, a signal, light, sound, vibration, or any combination thereof.

[0028] The lower cover 14 is an example of a buckle cover having an inner surface to which the circuit board 16 is fixed. The lower cover 14 is a resin part that covers the circuit board 16.

[0029] The upper cover 12 and the lower cover 14 are exterior covers of the buckle 8, and are housings that house the buckle body 8c, the circuit board 16, the lever 40, and the leaf spring 50. In this embodiment, in order to house these components, the exterior cover of the buckle 8 is composed of two components, the upper cover 12 and the lower cover 14, but it may be composed of three or more components.

[0030] When the buckle 8 is attached to the vehicle, the upper cover 12 faces the side opposite to an occupant wearing a seat belt connected to the buckle 8 via a tongue, and the lower cover 14 faces the occupant.

[0031] 5, 6 and 7 are cross-sectional views for explaining a mechanism for detecting tension of a seat belt. When the tongue 7 is inserted into the buckle 8 (see FIG. 5), the tip of the tongue 7 comes into contact with the ejector 33. The ejector 33 is pushed by the contact with the tip of the tongue 7 and moves in the direction in which the tongue 7 is inserted, causing the latch 34 to rotate and the slider 32 to move down. Due to the rotation of the latch 34, the latch 34 engages with the tongue 7, and the slider 32 moves under the lock pin 35 (see FIG. 6).

[0032] The insertion opening 15 is a gap between the button 31 and the lever 40. The opening height e of the insertion opening 15 (see FIG. 5) is determined by the height of the gap. The lever 40 and the leaf spring 50 are formed so that the opening height e of the insertion opening 15 when the lever 40 is in the initial position is slightly narrower than the plate thickness d of the plate 7a of the tongue 7. Therefore, in FIG. 6, when the plate 7a of the tongue 7 is inserted into the insertion opening 15, the lever 40 is pushed by the plate 7a of the tongue 7 at the action point P2, and rotates slightly clockwise around the pivot 41. The leaf spring 50 is pushed in by the lever 40 that rotates slightly. The elastic force of the leaf spring 50 pushed in by the lever 40 suppresses the rattling of the plate 7a of the tongue 7 between the button 31 and the lever 40 (pretension region). Thereby, minute changes in the tension N of the seat belt are transmitted with high accuracy to the sensor 20 via the plate 7a of the tongue 7, the lever 40, and the leaf spring 50. As a result, the sensor 20 can detect minute changes in the tension N with high accuracy.

[0033] In FIG. 7, the load (tension N) applied to the force point P1 of the tongue 7 causes the plate 7a of the tongue 7 to press the upper surface of the lever 40 at the action point P2, with the upper wall 37a of the buckle base 37 as the fulcrum P3. The lever 40 pressed into the tongue 7 at the action point P2 rotates clockwise around the pivot 41 and presses the leaf spring 50. The leaf spring 50 receives the load and transmits the force to the sensor 20 while bending itself. The lower wall 37b of the buckle base 37 has a mechanical stopper 38 that restricts the movement of the tongue 7 toward the lower wall 37b. The plate 7a of the tongue 7 comes into contact with the mechanical stopper 38, thereby stopping the movement of the tongue 7 toward the lower wall 37b. The mechanical stopper can limit the force applied to the sensor 20 via the lever 40 and the leaf spring 50, and can protect the sensor 20 from a large load caused by a collision or the like.

[0034] The buckle 8 has a point of action P2 and a fulcrum P3 in its main body 8a. The point of action P2 represents a point on which a rotational force (hereinafter also referred to as "rotational force Fr") acts around the fulcrum P3 in response to a load F1 input to the tongue 7. The fulcrum P3 represents the center of rotation of the rotational force Fr. The load F1 represents a force applied to the force point P1 by the tension of the seat belt 4. The force point P1 is located outside the buckle 8 when the plate 7a of the tongue 7 is inserted, and is located at the base end 7e that contacts the seat belt 4. The buckle 8 also includes a sensor 20. In this embodiment, the sensor 20 outputs a signal corresponding to the force acting on the point of action P2 (more specifically, a signal corresponding to the deformation of the leaf spring 50).

[0035] When the tension of the seat belt 4 increases, the load F1 increases in the direction of the arrow in the figure, so that the tongue 7 connected to the buckle 8 is slightly pulled toward the occupant (the lower cover 14 side in the negative Z-axis direction). When the load F1 increases and the tongue 7 is displaced toward the occupant, the rotational force Fr acting on the point of action P2 increases, so that the force that the sensor 20 receives from the point of action P2 via the lever 40 and the leaf spring 50 also increases.

[0036] Conversely, when the tension of the seat belt 4 decreases, the load F1 decreases, and the tongue 7 connected to the buckle 8 is pulled back to the side opposite the occupant (the upper cover 12 side in the positive Z-axis direction). When the load F1 decreases and the tongue 7 is displaced to the side opposite the occupant, the rotational force Fr acting on the point of action P2 decreases, and the force that the sensor 20 receives from the point of action P2 via the lever 40 and the leaf spring 50 also decreases.

[0037] Therefore, based on the signal output from the sensor 20 in response to the force acting on the application point P2, the displacement of the tongue 7 in a state where the plate 7a is inserted into the buckle 8 can be measured by the processing unit 60 or the like. In particular, in this embodiment, the fulcrum P3, which is the center of rotation of the rotational force Fr acting on the application point P2, is not outside the buckle 8 but inside the buckle 8. Since the fulcrum P3 is inside the buckle 8, the magnitude of the force acting on the application point P2 represents the relative displacement of the tongue 7 with respect to the buckle 8. Therefore, by processing the signal output from the sensor 20 in response to the force acting on the application point P2 in a state where the plate 7a is inserted into the buckle 8, it is possible to measure the relative movement of the tongue 7 with respect to the buckle 8. Since the relative movement of the tongue 7 with respect to the buckle 8 can be measured in a state where the plate 7a is inserted into the buckle 8, it is possible to measure, for example, the change in tension of the seat belt 4 that directly contacts the tongue 7.

[0038] In the conventional technology that measures the relative movement of the buckle with respect to a member outside the buckle, when the buckle comes into contact with the seat cushion or the hips of the occupant, the force transmission path changes, making it difficult to accurately measure the movement of the tongue connected to the buckle. If the tongue movement is not accurately measured, it is difficult to accurately measure the change in tension of the seat belt attached to the tongue.

[0039] In contrast, in this embodiment, since the fulcrum P3 is inside the buckle 8, the force acting on the point of application P2 can be detected by the sensor 20 to measure the relative movement of the tongue 7 with respect to the buckle 8. In addition, the tongue 7 connected to the buckle 8 is located in a position less susceptible to contact and interference with an occupant or the seat than the buckle 8. Therefore, by measuring the relative movement of the tongue 7 with respect to the buckle 8, it becomes possible to stably measure the movement of the tongue 7 regardless of whether the buckle 8 is in contact with an occupant or the like.

[0040] By processing the signal output from the sensor 20, it is possible to measure the tension state of the seat belt 4, but it is also possible to measure other conditions, such as the breathing state of the occupant and the wakefulness state of the occupant.

[0041] When an occupant wearing the seat belt 4 breathes, the occupant's body surface (for example, the surface of the waist, the surface of the abdomen, the surface of the chest, etc.) is slightly displaced in synchronization with the breathing. For example, when the occupant breathes in, the occupant's body surface expands in the vehicle longitudinal direction and the vehicle width direction, and when the occupant breathes out, the occupant's body surface shrinks in the vehicle longitudinal direction and the vehicle width direction. Since the seat belt 4 is in contact with the occupant's body surface, when the occupant's body surface displaces in synchronization with the breathing, the tension of the seat belt 4 also changes in synchronization with the breathing of the occupant. When the tension of the seat belt 4 changes in synchronization with the breathing, the load F1 input to the tongue 7 attached to the seat belt 4 also changes in synchronization with the breathing. Therefore, the breathing state of the occupant can be measured by processing the signal output from the sensor 20 according to the force acting on the application point P2.

[0042] As described above, the buckle 8 according to this embodiment includes the lever 40 that rotates due to the load received from the plate 7a inserted into the insertion opening 15, the leaf spring 50 that deforms due to the rotational movement of the lever 40, the sensor 20 that outputs a signal according to the deformation of the leaf spring 50, and the processing unit 60 that processes the signal output from the sensor 20. As a result, when the plate 7a of the tongue 7 is inserted into the buckle 8, the movement of the tongue 7 relative to the buckle 8 can be measured by the processing unit 60 etc.

[0043] Next, the lever 40 and the leaf spring 50 will be described in more detail.

[0044] 8 is a diagram showing the positional relationship between a leaf spring, which is an example of an elastic body, and a lever. A point of application P2 is located on an upper surface 42 of the lever 40. When a rotational force Fr acts on the point of application P2, the lever 40 rotates about the pivot 41, and the lower surface 43 opposite to the upper surface 42 presses the upper surface 51 of the leaf spring 50.

[0045] FIG. 9 is a diagram showing the lower surface of the lever (the surface facing the leaf spring). The lower surface 43 of the lever 40 has pressing portions 44, 45 for pressing the leaf spring 50. The pressing portion 44 is an example of a first pressing portion, and in this embodiment, it is a protrusion protruding from the center of the lower surface 43. The pressing portion 44 has a tip portion 44a that contacts the upper surface 51 of the leaf spring 50. The pressing portion 45 is an example of a second pressing portion, and in this embodiment, it is a protrusion protruding from an end portion of the lower surface 43. The pressing portion 45 has a tip portion 45a that contacts the upper surface 51 of the leaf spring 50. The tip portion 45a of the pressing portion 45 is wider than the tip portion 44a of the pressing portion 44 in the axial length direction of the pivot 41. The tip portion 45a of the pressing portion 45 is provided at a location farther away than the tip portion 44a of the pressing portion 44.

[0046] Fig. 10 is a cross-sectional view illustrating a state in which the leaf spring 50 is pressed by the tip portion 44a of the pressing portion 44. Fig. 11 is a cross-sectional view illustrating a state in which the leaf spring 50 is pressed by the tip portion 44a of the pressing portion 44 and the tip portion 45a of the pressing portion 45.

[0047] In FIG. 10, the plate 7a of the tongue 7 presses the upper surface 42 of the lever 40 at the point of application P2. The lever 40 pressed by the plate 7a of the tongue 7 at the point of application P2 rotates clockwise around the pivot 41, and the tip 44a of the pressing portion 44 presses the leaf spring 50 from the upper surface 51. The leaf spring 50 receives the load and transmits the force to the sensor 20 while bending and deforming itself. The sensor 20 receives the force from the deforming leaf spring 50 and outputs a sensor signal according to the magnitude of the force to the processing unit 60. At the timing shown in FIG. 10, the tip 44a of the pressing portion 44 is in contact with the upper surface 51 of the leaf spring 50, but the tip 45a of the pressing portion 45 is not in contact with the upper surface 51 of the leaf spring 50.

[0048] 11, when the rotational force Fr applied to the point of action P2 becomes even larger, the lever 40 rotates further clockwise about the pivot 41, and the tip 44a of the pushing portion 44 and the tip 45a of the pushing portion 45 press the leaf spring 50 from the upper surface 51. The leaf spring 50 receives a larger load and transmits a larger force to the sensor 20 while bending and deforming itself.

[0049] 12 is a perspective view showing a leaf spring supported by a plurality of support members. Leaf spring 50 is a thin elastic body and is made of, for example, stainless steel. Leaf spring 50 has a lower surface 52. Leaf spring 50 is supported from lower surface 52 by a plurality of support members 53 (53a, 53b, 53c, 53d, 53e) and is fixed to lower cover 14 by the plurality of support members 53, for example.

[0050] The leaf spring 50 according to this embodiment has a structure including an M-shaped body 54 supported at five corners 56 (56a, 56b, 56c, 56d, 56e), and a cantilever beam 55 extending from a central portion 54b into a central gap 54a of the M-shaped body 54. The sensor 20 is located between the central corner 56c and the central portion 54b in a plan view of the leaf spring 50 in the Z-axis direction, and is disposed in contact with the lower surface 52.

[0051] The corners 56a, 56b, 56c, 56d, and 56e are supported by corresponding support members 53a, 53b, 53c, 53d, and 53e, respectively, from the lower surface 52. The corners 56a, 56c, and 56e are aligned along the lower side of the M-shaped body 54, and the corners 56b and 56d are aligned along the upper side of the M-shaped body 54.

[0052] The M-shaped body 54 has both side portions 58 that sandwich the cantilever beam 55. When the lever 40 rotates, initially, only the cantilever beam 55 is pressed by the tip portion 44a of the pressing portion 44 of the lever 40 at the first contact line 57a. When the lever 40 rotates further, the cantilever beam 55 is pressed by the tip portion 44a of the pressing portion 44 at the first contact line 57a, and the both side portions 58 are pressed by the tip portion 45a of the pressing portion 45 at the second contact line 57b.

[0053] Thus, the leaf spring 50 has an elastic structure including a cantilever beam 55 that deforms with the rotational movement of the lever 40, and an M-shaped body 54 that deforms together with the cantilever beam 55 with further rotational movement of the lever 40. The cantilever beam 55 is an example of a first elastic part that deforms with the rotational movement of the lever 40. The M-shaped body 54 is an example of a second elastic part that deforms together with the first elastic part with the rotational movement of the lever 40, and functions as a doubly supported beam. The leaf spring 50 has such an elastic structure, and thus the characteristics shown in FIG. 13 can be obtained.

[0054] FIG. 13 is a diagram showing an example of the relationship (FS characteristic) between the load F (rotational force Fr) that the lever 40 receives from the plate 7a of the tongue 7 and the rotation stroke length S of the lever 40. FIG. 13 shows the FS characteristic in which the rate of change of the rotation stroke length S of the lever 40 with respect to the load F is larger when the load F is in the first load region A1 than when the load F is in the second load region A2 higher than the first load region A1. The first load region A1, where the load F is from f0 to f1, indicates the region where only the pressing portion 44 of the lever 40 presses the leaf spring 50 (the state of FIG. 10). The second load region A2, where the load F is from f1 to f2, indicates the region where the pressing portion 44 and the pressing portion 45 of the lever 40 press the leaf spring 50 (the state of FIG. 11). When the plate 7a comes into contact with the mechanical stopper 38, the increase in the rotation stroke length S stops, and the rotation stroke length S is maintained constant even if the load F increases.

[0055] 13 indicates that the leaf spring 50 has an elastic characteristic in which the elastic modulus changes depending on the magnitude of the load F. In this case, the elastic modulus of the leaf spring 50 is smaller when the load F is in the first load region A1 than when it is in the second load region A2.

[0056] 13, the load F is reduced in the pretension region where the plate 7a is pretensioned by pressing the leaf spring 50, and the force applied to the sensor 20 via the leaf spring 50 is suppressed. This makes it possible to reduce deviations in the sensor characteristics of the sensor 20 due to excessive force applied to the sensor 20 in the pretension region.

[0057] Although the embodiment has been described above, the present invention is not limited to the above embodiment, and various modifications and improvements, such as combinations with or substitutions for part or all of other embodiments, are possible.

[0058] For example, the elastic body that is deformed by the rotational movement of the lever is not limited to a leaf spring, and may be another elastic body such as rubber. [Explanation of symbols]

[0059] 4. Seatbelts 7 Tongue 8 Buckle 8a Main body 8b Stay 8c Buckle body 12 Upper cover 13 Buckle switch 14 Lower cover 15 Insertion port 16 Circuit Board 20 Sensors 38 Mechanical Stopper 40 Lever 41 Pivot 42 Top surface 43 Bottom surface 50 Leaf spring 51 Top side 52 Bottom surface 53, 53a, 53b, 53c, 53d, 53e Support members 54 M-shaped body 54a Central gap 54b Central part 55 Cantilever beam 56,56a,56b,56c,56d,56e corner 57a 1st contact line 57b 2nd contact line 58 Both sides 60 Processing section 70 Judgment section 80 Output section

Claims

1. a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor, The sensor receives a force from the elastic body which is deformed, A buckle, wherein the elastic modulus of the elastic body changes depending on the magnitude of the load.

2. The buckle according to claim 1 , wherein the elastic body includes a first elastic portion that is deformed by the rotational movement, and a second elastic portion that is deformed together with the first elastic portion by the rotational movement.

3. a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor, The sensor receives a force from the elastic body which is deformed, The elastic body includes a first elastic portion that is deformed by the rotational movement, and a second elastic portion that is deformed together with the first elastic portion by the rotational movement.

4. the first elastic portion is a cantilever beam that is deformed by the rotational movement, The buckle according to claim 2 or 3, wherein the second elastic portion is deformed together with the cantilever beam by the rotational movement.

5. The buckle according to claim 4 , wherein the second elastic portion is a doubly supported beam that deforms together with the cantilever beam due to the rotational movement.

6. The doubly supported beam includes an M-shaped body supported at five corners, The buckle according to claim 5 , wherein the cantilever beam is a beam that extends into a central gap of the M-shaped body.

7. The M-shaped body has two side portions that sandwich the cantilever beam, The buckle according to claim 6 , wherein the lever includes a first pressing portion that presses the cantilever beam, and a second pressing portion that presses the cantilever beam and both side portions.

8. The buckle according to claim 7 , wherein the second pressing portion is wider than the first pressing portion.

9. The buckle according to claim 2 , wherein the lever includes a first pressing portion that presses the first elastic portion, and a second pressing portion that presses the first elastic portion and the second elastic portion.

10. The buckle according to claim 1 , wherein the buckle body has a stopper that regulates movement of the plate inserted into the insertion opening to limit a force applied to the sensor.

11. a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor, A buckle, wherein a rate of change of the rotational stroke length of the lever relative to the load is greater when the load is in a first load range than when the load is in a second load range that is higher than the first load range.

12. a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor, The lever is rotatably supported by the outer cover.

13. a buckle body having an insertion opening into which a tongue plate attached to a seat belt of a vehicle is inserted; An outer cover that houses the buckle body; a lever that rotates in response to a load applied from the plate inserted into the insertion opening; an elastic body that is deformed by the rotational movement of the lever; a sensor that outputs a signal corresponding to the deformation of the elastic body; A processing unit that processes the signal output from the sensor, A buckle, wherein an opening height of the insertion opening when the lever is in an initial position is narrower than a thickness of the plate.

14. The buckle according to claim 1 , wherein the processing unit amplifies the signal.

15. The buckle according to claim 1 , wherein the processing unit detects a vital sign based on the signal.

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