Impact sensor

Abstract

To provide an impact sensor for reducing the erroneous detection of impact.SOLUTION: An impact sensor 300 includes a frame 1 having a first fixed electrode 11, and a movable element having a movable electrode 2 and being movable upon receiving an impact from the outside. The movable element (movable electrode 2) is supported by the frame 1 via a spring 4 and, upon receiving the impact of a predetermined first threshold value or more, causes the movable electrode 2 to come into contact with the first fixed electrode 11 while expanding and contracting the spring 4, and detects the impact by detecting an electrical connection between the movable electrode 2 and the first fixed electrode 11 when the movable electrode 2 comes into contact with the first fixed electrode 11. The spring 4 includes an abutting part 41 and an abutting part disposed at a position in the spring 4 opposite to the abutting part 41 from the compression direction of the spring 4, and the abutting part 41 is set to come into contact with an opposite part 42 when the movable element receives the impact of a second threshold value or greater which is lower than the first threshold value.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an impact sensor.

Background Art

[0002] Patent Document 1 discloses that a movable electrode is supported by a spiral elastic body, the central portion of the movable electrode has a cylindrical shape, a fixed electrode is arranged at a predetermined interval inside the cylindrical shape, and due to an external impact, the movable electrode moves relative to the fixed electrode by inertial force, and the external impact is detected when the movable electrode contacts the fixed electrode.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of Patent Document 1, even when an impact smaller than the threshold value set as the minimum value of the impact detectable in the movable electrode and the fixed electrode is applied, if the impact includes the resonance frequency of the vibration system by the elastic body and the movable electrode as a frequency component, this may be detected as an impact, and it has been difficult to perform correct detection.

[0005] Therefore, an object of one aspect of the present invention is to provide an impact sensor that reduces false detection of impacts.

Means for Solving the Problems

[0006] According to one aspect of the present invention, there is provided a shock sensor including a stator including a first fixed electrode, and a mover including a movable electrode and movable in response to an external shock. The mover is supported by the stator via an elastic body, and when receiving a shock equal to or greater than a predetermined first threshold value, the elastic body is compressed while the movable electrode is brought into contact with the first fixed electrode, and the shock is detected by detecting an electrical connection between the movable electrode and the first fixed electrode when the movable electrode contacts the first fixed electrode. The elastic body includes a contact portion and an opposing portion disposed at a position facing the contact portion from the compression direction of the elastic body. The contact portion is set to contact the opposing portion when the mover receives a shock equal to or greater than a second threshold value that is lower than the first threshold value.

Advantages of the Invention

[0007] According to one aspect of the present invention, vibration of the mover caused by a shock equal to or greater than the second threshold value and less than the first threshold value is suppressed. Further, even for a shock less than the second threshold value, even if the shock includes the resonance frequency of the vibration system related to the mover and the elastic body and the vibration system vibrates in the same manner as when receiving a shock equal to or greater than the second threshold value, the vibration can be suppressed. Therefore, a shock smaller than the first threshold value set as the minimum value of the shock detectable at the movable electrode and the first fixed electrode is not detected, and false detection of the shock can be reduced.

Brief Description of the Drawings

[0008]

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Embodiments for Carrying Out the Invention

[0009] The embodiments described below are not limited to the drawings explained by the simple explanation of the drawings.

[0010] A first aspect of the present invention includes a stator including a first fixed electrode, and a mover including a movable electrode and movable in response to an external impact. The mover is supported by the stator via an elastic body, and when receiving an impact equal to or greater than a predetermined first threshold value, compresses the elastic body and brings the movable electrode into contact with the first fixed electrode. The impact sensor detects the impact by detecting an electrical connection between the movable electrode and the first fixed electrode when the movable electrode contacts the first fixed electrode. The elastic body includes a contact portion and an opposing portion disposed at a position facing the contact portion from the compression direction of the elastic body. The contact portion is set to contact the opposing portion when the mover receives an impact equal to or greater than a second threshold value lower than the first threshold value.

[0011] According to the first aspect, vibration of the mover caused by an impact equal to or greater than the second threshold value and less than the first threshold value is suppressed. Even for an impact less than the second threshold value, if the impact includes the resonance frequency of the vibration system related to the mover and the elastic body, and the vibration system vibrates in the same manner as when receiving an impact equal to or greater than the second threshold value, the vibration can be suppressed. Therefore, an impact smaller than the first threshold value, which is set as the minimum value of the impact to be detected at the movable electrode and the first fixed electrode, is not detected, and false detection can be reduced.

[0012] A second aspect of the present invention is the impact sensor according to the first aspect, wherein the elastic body is a beam portion formed to reciprocate in a direction perpendicular to the compression direction while moving in the compression direction, the contact portion is disposed on one of a pair of portions adjacent to each other in the compression direction of the beam portion, and the opposing portion is disposed on the other of the pair of portions adjacent to each other in the compression direction of the beam portion.

[0013] According to the second aspect, the distance between the contact portion and the opposing portion can be made smaller more easily than the distance between other portions of the pair of adjacent beams where the contact portion and the opposing portion face each other, and a configuration in which the contact portion and the opposing portion contact before the movable electrode contacts the first fixed electrode due to an impact can be easily constructed.

[0014] In a third aspect of the present invention, in the first aspect or the second aspect, at least one of the contact portion and the opposing portion is an impact sensor that protrudes toward the other.

[0015] According to the third aspect, the distance between the contact portion and the opposing portion can be made more easily smaller than the distance between portions other than the portions where the contact portion and the opposing portion face each other in a pair of adjacent beams, and a configuration in which the contact portion and the opposing portion come into contact before the movable electrode contacts the first fixed electrode due to an impact can be easily constructed.

[0016] In a fourth aspect of the present invention, in the second aspect or the third aspect, the contact portion is one of a pair of folded-back portions adjacent to each other in the compression direction with respect to the folded-back portion of the beam portion, and is disposed at a position facing the other of the pair of folded-back portions, and the opposing portion is the other of the pair of folded-back portions adjacent to each other in the compression direction and is disposed at a position facing the contact portion, and is an impact sensor.

[0017] According to the fourth aspect, by disposing the contact portion and the opposing portion at the folded-back portion of the beam portion where the vibration during impact becomes large, the contact between the contact portion and the opposing portion can be easily achieved.

[0018] In a fifth aspect of the present invention, in any one of the first aspect to the fourth aspect, the elastic bodies are arranged in a pair so as to sandwich the mover from both sides in the compression direction, and the pair of elastic bodies are impact sensors that support the mover respectively.

[0019] According to the fifth aspect, the mover can be easily vibrated (displaced) selectively in the direction in which the elastic bodies are arranged, and the sensitivity to impact in the direction in which the elastic bodies are arranged can be enhanced.

[0020] In a sixth aspect of the present invention, in the fifth aspect, the contact portion and the opposing portion are impact sensors that are arranged symmetrically with respect to the mover.

[0021] According to the sixth aspect, it is possible to make the sensitivities to impacts in the left - right direction (positive direction) and the left - right direction (negative direction) the same.

[0022] According to the seventh aspect of the present invention, in the second aspect or the third aspect, the contact portion and the opposing portion are impact sensors disposed at the central portion of the portion extending in a direction perpendicular to the compression direction of the beam portion.

[0023] According to the seventh aspect, it is possible to suppress the variation in vibration of the vibration system due to the movable electrode and the spring portion more than when disposed at the folded portion of the beam portion, and improve the yield of the impact sensor.

[0024] According to the eighth aspect of the present invention, in the third aspect, at least one of the contact portion and the opposing portion, the tip protruding toward the other has a planar shape or a convex curved - surface shape, and is an impact sensor.

[0025] According to the eighth aspect, for example, when the tip has a planar shape, the frictional load between the contact portion and the opposing portion increases, and when the tip has a curved - surface shape, the frictional load decreases. Therefore, by appropriately selecting the shape of the tips of the contact portion and the opposing portion, the magnitude of the frictional load can be appropriately set.

[0026] According to the ninth aspect of the present invention, in any one of the first aspect to the eighth aspect, the stator, the mover, and the elastic body are an integral body, and the integral body is formed from a laminate in which an active layer is laminated on a support layer. The portion related to the stator of the integral body is formed by the laminate, and the portions related to the mover and the elastic body of the integral body are formed by the active layer obtained by removing the support layer from the laminate, and is an impact sensor.

[0027] According to the ninth aspect, it is possible to form an impact sensor by performing an etching process on the laminate, and the impact sensor can be manufactured simply and in large quantities.

[0028] In the tenth aspect of the present invention, in any one of the first to tenth aspects, the mover is movable in the compression direction by receiving the impact, and the first fixed electrode is an impact sensor disposed apart from the movable electrode in the compression direction.

[0029] According to the tenth aspect, an impact from one direction can be detected with high sensitivity.

[0030] In the eleventh aspect of the present invention, in any one of the first to tenth aspects, a first recess in which a direction perpendicular to the compression direction is a depth direction is disposed in either one of the movable electrode and the first fixed electrode, and a first convex portion at least partially accommodated in the first recess is disposed in the other of the movable electrode and the first fixed electrode. The impact sensor detects the impact when the mover moves and the first convex portion and the first recess come into contact with each other, and the movable electrode and the first fixed electrode come into contact with each other.

[0031] According to the eleventh aspect, a configuration in which electrical connection between the movable electrode and the first fixed electrode is achieved by contact between the movable electrode and the first fixed electrode can be easily set.

[0032] In the twelfth aspect of the present invention, in any one of the first to eleventh aspects, the stator includes a second fixed electrode insulated from the first fixed electrode, and the second fixed electrode is an impact sensor electrically connected to the movable electrode by extending to the elastic body and the mover.

[0033] According to the twelfth aspect, a configuration in which electrical connection between the second fixed electrode and the first fixed electrode is achieved by contact between the movable electrode and the first fixed electrode can be easily set.

[0034] Hereinafter, embodiments will be described with reference to the drawings.

[0035] [First Embodiment] [Configuration of Impact Sensor 300] FIG. 1 is a plan view of the impact sensor 300 according to the first embodiment of the present invention. In FIG. 1 (the same applies to other figures), the X direction and the Y direction are perpendicular to each other. Also, in the following description, the "X direction" may be referred to as the "left - right direction", the "Y direction" as the "up - down direction", the "+X direction" as the "right direction", the "-X direction" as the "left direction", the "+Y direction" as the "up direction", and the "-Y direction" as the "down direction".

[0036] As shown in FIG. 1, the impact sensor 300 has a rectangular (square) shape in plan view. The impact sensor 300 includes a rectangular (square) frame portion 1, a movable electrode 2 disposed inside the frame portion 1, and a spring portion 4 disposed in the region between the frame portion 1 and the movable electrode 2, supported by the frame portion 1 and supporting the movable electrode 2.

[0037] The frame portion 1 has a substantially rectangular (square) opening, and the movable electrode 2 and the spring portion 4 are accommodated in the opening.

[0038] The frame portion 1 includes a first beam 141 extending in the left - right direction and having a first fixed electrode 11 disposed thereon, a second beam 142 connected to the left - hand end of the first beam 141 and extending downward, a third beam 143 connected to the right - hand end of the first beam 141 and extending downward, and a fourth beam 144 connecting the lower ends of the second beam 142 and the third beam 143 and extending in the left - right direction.

[0039] The movable electrode 2 is all or part of a movable element supported from both sides in the left - right direction by a spring portion 4 having a lower rigidity (elasticity) in the left - right direction than in the up - down direction. It is an electrode that can be selectively displaced in the left - right direction (the compression direction of the spring portion 4) by the spring portion 4, and displacement in the up - down direction (the compression direction of the spring portion 4) is strongly suppressed compared to displacement in the left - right direction. When the impact sensor 300 receives an impact (acceleration) in the left - right direction from the outside, the movable electrode 2 (movable element) generates an inertial force due to its mass and moves relative to the frame portion 1 in the left - right direction. Note that the "compression direction" includes not only the direction in which the spring portion 4 is compressed but also the reverse direction (the direction in which the spring portion 4 is extended).

[0040] In the first beam 141, a first fixed electrode 11 is disposed at a position facing the movable electrode 2. Further, the portion of the first beam 141 other than the portion where the first fixed electrode 11 is disposed (excluding the groove portion 13 described later), the second beam 142, the third beam 143, and the fourth beam 144 form the second fixed electrode 12.

[0041] In the first beam 141, a groove portion 13 is disposed between the first fixed electrode 11 and the second fixed electrode 12, and in the frame portion 1, the first fixed electrode 11 and the second fixed electrode 12 are insulated by the groove portion 13.

[0042] The first fixed electrode 11 has a first convex portion 111 that extends downward, that is, toward the movable electrode 2, at a position facing the central portion of the upper edge of the movable electrode 2 in the first beam 141. On the other hand, a first concave portion 21 is formed on the edge of the movable electrode 2 facing the first convex portion 111.

[0043] The first convex portion 111 forms gaps in the vertical and horizontal directions with the first concave portion 21, and at least a part of the first convex portion 111 is accommodated in the first concave portion 21 in a non-contact state with the first concave portion 21.

[0044] In the fourth beam 144, a second convex portion 121 that extends upward, that is, toward the movable electrode 2, is provided at a position facing the central portion of the edge of the movable electrode 2 extending in the left-right direction. On the other hand, a second concave portion 22 is formed on the edge of the movable electrode 2 facing the second convex portion 121.

[0045] The second convex portion 121 forms gaps in the vertical and horizontal directions with the second concave portion 22, and at least a part of the second convex portion 121 is accommodated in the second concave portion 22 in a non-contact state with the second concave portion 22.

[0046] Here, the left side surfaces of the first recess 21 and the second recess 22 are arranged at the same position in the left-right direction, and the right side surfaces of the first recess 21 and the second recess 22 are arranged at the same position in the left-right direction. That is, the central portions of the first recess 21 and the second recess 22 in the left-right direction are arranged at the same position in the left-right direction. Therefore, the movable electrode 2 has an "H" shape with the vertical direction being the up-down direction. The movable electrode 2 has a shape that is mirror-symmetric with respect to a line (broken line S shown in FIG. 1) that passes through the central portion of the movable electrode 2 in the left-right direction (i.e., the central portions of the first recess 21 and the second recess 22 in the left-right direction) and is parallel to the up-down direction. By forming the movable electrode 2 in the shape of an "H" in this way, vibrations in directions other than the direction (left-right direction) sandwiched by the spring portions 4 and rotational movements with an axis in a direction perpendicular to the left-right direction and the up-down direction can be reduced, and false detection by the impact sensor 300 can be reduced.

[0047] In addition, in the first embodiment, the first convex portion 111 and the second convex portion 121 may be formed on the movable electrode 2, the first recess 21 may be formed on the first fixed electrode 11, and the second recess 22 may be formed on the second fixed electrode 12.

[0048] The spring portion 4 is a beam portion that reciprocates in a direction perpendicular to the compression direction (left-right direction) while moving in the compression direction (left-right direction) of the spring portion 4. The spring portion 4 (spring portion 4L, spring portion 4R) is formed such that the rigidity (elasticity) with respect to the force in the left-right direction is weaker than the rigidity (elasticity) with respect to the force in the up-down direction, and is a member that can selectively expand and contract in the left-right direction and the expansion and contraction in the up-down direction is strongly suppressed compared to the expansion and contraction in the left-right direction. When the spring portion 4 receives an inertial force in the left-right direction from the movable electrode 2, it deforms, thereby generating a restoring force.

[0049] The left spring portion 4L is connected to a position on the left side of the first beam 141 where it can be connected to the second fixed electrode 12 and to the lower end portion of the left edge of the movable electrode 2.

[0050] The left spring portion 4L extends in the vertical direction in the region surrounded by the first beam 141, the movable electrode 2, the fourth beam 144, and the second beam 142, and has a zigzag structure that reciprocates vertically between the first beam 141 and the fourth beam 144 a plurality of times by turning back at a position adjacent to the first beam 141 and a position adjacent to the fourth beam 144. In the spring portion 4L, two turning-back portions are formed on the upper side in the vertical direction, and two turning-back portions are formed on the lower side in the vertical direction, but the number of turning-back portions is arbitrarily set.

[0051] The right spring portion 4R is connected to a position on the right side of the first beam 141 where it can be connected to the second fixed electrode 12 and to the lower end of the right edge of the movable electrode 2.

[0052] The right spring portion 4R has a zigzag structure that reciprocates vertically between the first beam 141 and the fourth beam 144 by turning back at a position adjacent to the first beam 141 and a position adjacent to the fourth beam 144 in the region surrounded by the first beam 141, the third beam 143, the fourth beam 144, and the movable electrode 2. In the spring portion 4R, two turning-back portions are formed on the upper side in the vertical direction, and two turning-back portions are formed on the lower side in the vertical direction, but it is preferable to set the number of turning-back portions in the spring portion 4R to the same number as that of the turning-back portions in the spring portion 4L.

[0053] The beams constituting the spring portion 4 have a plurality of portions extending in the vertical direction, but a contact portion 41 is arranged on one side surface of a pair of portions adjacent to each other in the left-right direction, and a facing portion 42 is arranged on the other side surface of the pair of portions. In the present embodiment, two contact portions 41 and two facing portions 42 are arranged in the left spring portion 4L and the right spring portion 4R, respectively.

[0054] The contact portion 41 is, for example, a member protruding toward the opposing portion 42, and the opposing portion 42 is, for example, a member protruding toward the contact portion 41. However, it may be configured such that either one of them protrudes. The contact portion 41 is one of a pair of folded-back portions adjacent to each other in the left-right direction with respect to the folded-back portion of the beam portion, and is disposed at a position facing the other of the pair of folded-back portions. The opposing portion 42 is the other of the pair of folded-back portions adjacent to each other in the left-right direction and is disposed at a position facing the contact portion 41. Further, the contact portion 41 and the opposing portion 42 may be the same as or different from each other as components in terms of length, size, shape, etc., and may further be configured to replace their arrangement positions with each other. Here, for convenience, the contact portion 41 and the opposing portion 42 disposed on the side closer to the movable electrode 2 (the upper end in the vertical direction of the beam portion) are respectively referred to as the first contact portion 41A and the first opposing portion 42A, and the contact portion 41 and the opposing portion 42 disposed on the side farther from the movable electrode 2 (the lower end in the vertical direction of the beam portion) are respectively referred to as the second contact portion 41B and the second opposing portion 42B.

[0055] A gap is formed between the contact portion 41 and the opposing portion 42, and the gap, that is, the protruding amount of the contact portion 41 and / or the opposing portion 42, is set such that the contact portion 41 and the opposing portion 42 come into contact with each other at a predetermined acceleration (second threshold value) lower than the minimum acceleration (first threshold value) of the impact (acceleration) when the movable electrode 2 contacts the first fixed electrode 11, and is set based on the ratio of the predetermined acceleration (second threshold value) to the minimum acceleration (first threshold value). Thereby, when the movable electrode 2 relatively moves in the left-right direction with respect to the first fixed electrode 11, when an impact of a second threshold value lower than the first threshold value, which is an impact in the left-right direction, is applied, the contact portion 41 and the opposing portion 42 come into contact with each other.

[0056] By the way, the spring portion 4 constitutes a vibration system together with the movable electrode 2 (movable element). And the vibration system has a main vibration component that vibrates in the left-right direction. However, when an impact (acceleration) including the resonance frequency of the main vibration component is applied to the vibration system, even if the impact is lower than the above-mentioned minimum acceleration, the vibration system may vibrate (displace) excessively and the movable electrode 2 may contact the first fixed electrode 11, resulting in a possibility of being erroneously detected as an impact equal to or greater than a predetermined first threshold value, which is a predetermined inspection target.

[0057] On the other hand, the vibration system includes not only the main vibration component in the left - right direction but also the sub - vibration component that vibrates in the up - down direction, and the main vibration component and the sub - vibration component can transmit vibration energy to each other. Therefore, when the contact portion 41 and the opposing portion 42 are in contact, a frictional load is generated between the contact portion 41 and the opposing portion 42 due to the sub - vibration component, and thus the vibration (displacement) is suppressed by the decrease in the Q value of the vibration system. Also, when the contact portion 41 and the opposing portion 42 come into contact, the rigidity of the spring portion 4 becomes slightly higher and the resonance frequency changes, so excessive vibration (displacement) is suppressed.

[0058] From the above, for small vibrations (displacements) where the contact portion 41 and the opposing portion 42 do not contact each other, the vibration is not suppressed, but for large vibrations where the contact portion 41 and the opposing portion 42 contact each other, the vibration is suppressed. Also, even for an impact less than the second threshold value in the left - right direction, if an impact including the resonance frequency of the vibration system related to the mover (movable electrode 2) and the spring portion 4 is applied and the vibration system vibrates in the same way as when it receives an impact of the second threshold value or more, the vibration can be suppressed. Therefore, it is not possible to detect an impact smaller than the first threshold value (the minimum acceleration) set as the minimum value of the impact to be detected in the movable electrode 2 and the first fixed electrode 11, reducing false detection and enabling correct detection.

[0059] The second fixed electrode 12 extends to the spring portion 4 and is connected to the movable electrode 2. Therefore, when the movable electrode 2 (the first recess 21) contacts the first fixed electrode 11 (the first protrusion 111), the second fixed electrode 12 is electrically connected (energized) to the first fixed electrode 11.

[0060] <Operation of the impact sensor 300> FIG. 2 is a diagram showing the operation when an impact is applied to the impact sensor 300 according to the first embodiment of the present invention, and is a diagram when the first contact portion 41A and the first opposing portion 42A come into contact with each other. FIG. 3 is a diagram showing the operation when an impact is applied to the impact sensor 300 according to the first embodiment of the present invention, in which the movable electrode 2 is further displaced from the position shown in FIG. 2, and the second contact portion 41B and the second opposing portion 42B come into contact with each other in a state where the first contact portion 41A and the first opposing portion 42A are in contact with each other. FIG. 4 is a diagram showing the operation when an impact is applied to the impact sensor 300 according to the first embodiment of the present invention, in which the movable electrode 2 is further displaced from the position shown in FIG. 3, and the movable electrode 2 and the first fixed electrode 11 come into contact with each other in a state where the first contact portion 41A and the first opposing portion 42A are in contact with each other and the second contact portion 41B and the second opposing portion 42B are in contact with each other. FIG. 5 is a diagram showing the relationship between the intensity of the impact and the displacement of the movable electrode 2.

[0061] When an impact (acceleration) is applied to the impact sensor 300, an inertial force is generated in the movable electrode 2 (movable element) due to the mass of the movable electrode 2 (movable element), and the movable electrode 2 moves relative to the frame portion 1 due to the inertial force. When the acceleration becomes equal to or greater than a predetermined first threshold value (the minimum acceleration described above), the movable electrode 2 contacts the first fixed electrode 11. At this time, the spring portion 4 (spring portion 4R in the figure) on the side where the distance between the movable electrode 2 and the frame portion 1 becomes narrower due to the acceleration is compressed, but it is not compressed uniformly and is compressed from the portion close to the movable electrode 2.

[0062] Therefore, when an acceleration (impact) is applied to the impact sensor 300, first, as shown in FIG. 2, the first contact portion 41A and the first opposing portion 42A come into contact with each other. Then, as shown in FIG. 3, the second contact portion 41B and the second opposing portion 42B come into contact with each other in a state where the first contact portion 41A and the first opposing portion 42A are in contact with each other. Further, thereafter, as shown in FIG. 4, the movable electrode 2 (first recess 21) and the first fixed electrode 11 (first convex portion 111) come into contact with each other in a state where the first contact portion 41A and the first opposing portion 42A are in contact with each other and the second contact portion 41B and the second opposing portion 42B are in contact with each other.

[0063] As an example of the impact strength and the displacement of the movable electrode 2, as shown in FIG. 5, when an impact (acceleration) is about 60 [G] (second threshold value), the first contact portion 41A and the first opposing portion 42A come into contact (arrow (A)), when the impact is about 65 [G] (second threshold value), the second contact portion 41B and the second opposing portion 42B further come into contact (arrow (B)), when the impact is about 75 [G] (first threshold value), the movable electrode 2 (first concave portion 21) and the first fixed electrode 11 (first convex portion 111) further come into contact (arrow (C)), and the displacement of the movable electrode 2 (movable element) does not increase any further.

[0064] When an impact in which the first contact portion 41A and the first opposing portion 42A come into contact is applied to the impact sensor 300, a frictional load is generated between the first contact portion 41A and the first opposing portion 42A, and the resonance of the vibration system is suppressed.

[0065] Further, when an impact in which the second contact portion 41B and the second opposing portion 42B further come into contact is applied to the impact sensor 300, the resonance of the vibration system is further suppressed by the frictional load between the first contact portion 41A and the first opposing portion 42A and the frictional load between the second contact portion 41B and the second opposing portion 42B.

[0066] When the contact portion 41 and the opposing portion 42 come into contact, the spring portion 4 is bent and restricted, and its rigidity increases. Therefore, regarding the slope of the characteristic line with the horizontal axis being the impact [G] and the vertical axis being the displacement [μm] in FIG. 5, the slope of the characteristic line in the region where the impact [G] is from 60 [G] to 65 [G] is lower than the slope of the characteristic line in the region where the impact [G] is from 0 [G] to 60 [G], and the slope of the characteristic line in the region where the impact [G] is from 65 [G] to 75 [G] is lower than the slope of the characteristic line in the region where the impact [G] is from 60 [G] to 65 [G]. Note that the change rate between the rigidity (= spring constant) represented by the slope of the characteristic line in the region where the impact [G] is from 0 [G] to 60 [G] and the rigidity (= spring constant) represented by the slope of the characteristic line in the region where the impact [G] is from 65 [G] to 75 [G] is about 10 [%], and it is possible to design such that the displacement amount with respect to the impact does not change significantly.

[0067] <Laminated Structure of Impact Sensor 300> FIG. 6 is a schematic diagram showing a state in which the impact sensor 300 according to the first embodiment of the present invention is mounted on the mounting substrate 5.

[0068] The impact sensor 300 is formed of, for example, an SOI (Silicon On Insulator) wafer. The SOI wafer is formed by laminating an insulating layer 1b (SiO2) (support layer) made of SiO2 and an active layer 1c (Si) in this order on a silicon substrate 1a (support layer).

[0069] As a manufacturing process of the impact sensor 300, for example, the silicon substrate 1a and the insulating layer 1b are etched (for example, dry-etched) along the outer shape of the frame portion 1 on the back surface of the SOI wafer, and the active layer 1c is etched along the shapes of the first fixed electrode 11, the second fixed electrode 12, the movable electrode 2, the spring portion 4, and the groove portion 13 on the front surface of the SOI wafer. The impact sensor 300 is formed by applying metal plating to the portion of the active layer 1c remaining on the front surface of the SOI wafer.

[0070] Therefore, the surface of the active layer 1c of the impact sensor 300 (the first fixed electrode 11, the second fixed electrode 12, the movable electrode 2, the spring portion 4) is covered with metal (for example, copper) plating except for the groove portion 13. Therefore, the second fixed electrode 12 is electrically connected to the movable electrode 2 via a connection electrode (a portion where the second fixed electrode 12 extends to the spring portion 4 (FIG. 1)) disposed on the spring portion 4. On the other hand, in the groove portion 13, the insulating layer 1b is exposed.

[0071] As shown in FIG. 6, the impact sensor 300 is bonded to the mounting substrate 5 with an adhesive or the like so that the silicon substrate 1a faces the lower surface, and electrodes (the first fixed electrode 11, the second fixed electrode 12) disposed on the active layer 1c and pad electrodes 51 disposed on the mounting substrate 5 are connected by wires 52 formed of gold (Au) or the like. The pad electrode 51 is connected to a latch circuit 600 described later.

[0072] Note that the width of the beam of the spring portion 4 is narrower than the thickness of the active layer 1c (the frame portion 1 (the portion of the active layer 1c), the movable electrode 2), but the thickness of the spring portion 4 is set to be substantially the same as or the same as the thickness of the active layer 1c. As a result, it becomes difficult to deform in the direction (thickness direction) perpendicular to the left-right direction and the up-down direction of the spring portion 4. For example, when the impact sensor 300 is arranged horizontally, the sinking of the movable electrode 2 in the thickness direction of the impact sensor 300 can be reduced.

[0073] [Second Embodiment] FIG. 7 is a plan view of the impact sensor 300 according to the second embodiment of the present invention. In the second embodiment, the contact portion 41 and the opposing portion 42 are arranged at the center of the portion of the spring portion 4 (beam) extending in the up-down direction. Further, the opposing surfaces of the contact portion 41 and the opposing portion 42 are flat (this figure in FIG. 7) or curved (enlarged view in FIG. 7). Even with the arrangement of the second embodiment, it has the same operational effects as the first embodiment. However, since the contact portion 41 and the opposing portion 42 are arranged at the center of the portion of the spring portion 4 (beam) extending in the up-down direction, the vibration variation of the vibration system due to the movable electrode 2 and the spring portion 4 can be suppressed more than when arranged at the folded-back portion of the beam portion as in the first embodiment, and the yield of the impact sensor 300 can be improved.

[0074] [Third Embodiment] FIG. 8 is a plan view of the impact sensor 300 according to the third embodiment of the present invention. In the third embodiment, a third contact portion 41C, a third opposing portion 42C, a fourth contact portion 41D, and a fourth opposing portion 42D are further arranged in the first embodiment.

[0075] The third contact portion 41C is arranged at a position opposing in the left-right direction at the folded-back portion above the spring portion 4 (beam portion) of the movable electrode 2 (movable element).

[0076] The third opposing portion 42C is arranged at a position opposing the third contact portion 41C in the left-right direction at the folded-back portion above the spring portion 4 (beam portion).

[0077] The fourth abutting portion 41D is the connection position of the movable electrode 2 (movable element) of the spring portion 4, and is arranged at a position facing in the left - right direction on the folded - back portion below the spring portion 4 (beam portion).

[0078] The fourth opposing portion 42D is the folded - back portion below the spring portion 4 and is arranged at a position facing the fourth abutting portion 41D in the left - right direction.

[0079] When the impact sensor 300 of the third embodiment receives an impact (acceleration) from the outside such that the movable electrode 2 contacts the first fixed electrode 11, first, the third abutting portion 41C and the third opposing portion 42C come into contact.

[0080] Next, with the third abutting portion 41C and the third opposing portion 42C in contact, the fourth abutting portion 41D and the fourth opposing portion 42D come into contact.

[0081] Next, with the third abutting portion 41C and the third opposing portion 42C in contact and the fourth abutting portion 41D and the fourth opposing portion 42D in contact, the first abutting portion 41A and the first opposing portion 42A come into contact.

[0082] Next, with the third abutting portion 41C and the third opposing portion 42C in contact, the fourth abutting portion 41D and the fourth opposing portion 42D in contact, and the first abutting portion 41A and the first opposing portion 42A in contact, the second abutting portion 41B and the second opposing portion 42B come into contact.

[0083] Finally, with the third abutting portion 41C and the third opposing portion 42C in contact, the fourth abutting portion 41D and the fourth opposing portion 42D in contact, the first abutting portion 41A and the first opposing portion 42A in contact, and the second abutting portion 41B and the second opposing portion 42B in contact, the movable electrode 2 contacts the first fixed electrode 11.

[0084] Therefore, when the impact (acceleration) on the impact sensor 300 is increased from zero, the third contact portion 41C and the third opposing portion 42C come into contact at the first predetermined value (second threshold value), the fourth contact portion 41D and the fourth opposing portion 42D come into contact at a second predetermined value (second threshold value) greater than the first predetermined value, the first contact portion 41A and the first opposing portion 42A come into contact at a third predetermined value (second threshold value) greater than the second predetermined value, the second contact portion 41B and the second opposing portion 42B come into contact at a fourth predetermined value (second threshold value) greater than the third predetermined value, and the movable electrode 2 and the first fixed electrode 11 come into contact at a fifth predetermined value (first threshold value) greater than the fourth predetermined value.

[0085] [Fourth Embodiment] FIG. 9 is a plan view of the impact sensor 300 according to the fourth embodiment of the present invention. In the impact sensor 300 of the fourth embodiment, first fixed electrodes 11A - 11D, second fixed electrodes 12A - 12D, and groove portions 13 are arranged in the frame portion 1. In the frame portion 1, the first fixed electrode 11A, the groove portion 13, the second fixed electrode 12A, the groove portion 13, the first fixed electrode 11B, the groove portion 13, the second fixed electrode 12B, the groove portion 13, the first fixed electrode 11C, the groove portion 13, the second fixed electrode 12C, the groove portion 13, the first fixed electrode 11D, the groove portion 13, the second fixed electrode 12D, and the groove portion 13 are arranged so as to circulate in this order.

[0086] Here, the frame portion 1 has a rectangular opening for accommodating the mover (movable electrode 2).

[0087] The mover (movable electrode 2) is movable in a first moving direction (left - right direction) and a second moving direction (up - down direction) orthogonal to the first moving direction.

[0088] The opening of the frame portion 1 has a rectangular shape with a pair of edge sides in the first moving direction (left - right direction) and a pair of edge sides in the second moving direction (up - down direction), respectively.

[0089] The mover (movable electrode 2) has a pair of edge sides (first edge side, third edge side) parallel to the first moving direction and a pair of edge sides (second edge side, fourth edge side) parallel to the second moving direction.

[0090] From the central portion of the upper edge (first edge) of the mover (movable electrode 2), a third convex portion 23A extends upward. From the central portion of the right edge (second edge), a third convex portion 23B extends. From the central portion of the lower edge (third edge), a third convex portion 23C extends. From the central portion of the left edge (fourth edge), a third convex portion 23D extends.

[0091] A first fixed electrode 11A is disposed at a position facing the third convex portion 23A of the frame portion 1. A first fixed electrode 11B is disposed at a position facing the third convex portion 23B of the frame portion 1. A first fixed electrode 11C is disposed at a position facing the third convex portion 23C of the frame portion 1. A first fixed electrode 11D is disposed at a position facing the third convex portion 23D of the frame portion 1.

[0092] An L-shaped first opening 15A is formed by the upper right corner portion (first corner portion) formed by the first edge and the second edge of the mover (movable electrode 2), the third convex portion 23A, the third convex portion 23B, and the upper right portion of the opening of the frame portion 1.

[0093] An L-shaped second opening 15B is formed by the lower right corner portion (second corner portion) formed by the second edge and the third edge of the mover (movable electrode 2), the third convex portion 23B, the third convex portion 23C, and the lower right portion of the opening of the frame portion 1.

[0094] An L-shaped third opening 15C is formed by the lower left corner portion (third corner portion) formed by the third edge and the fourth edge of the mover (movable electrode 2), the third convex portion 23C, the third convex portion 23D, and the upper right portion of the opening of the frame portion 1.

[0095] An L-shaped fourth opening 15D is formed by the upper left corner portion (fourth corner portion) formed by the fourth edge and the first edge of the mover (movable electrode 2), the third convex portion 23D, the third convex portion 23A, and the upper left portion of the opening of the frame portion 1.

[0096] The spring part 4A is disposed within the first opening 15A and has an L shape following the outer shape of the first opening 15A. The spring part 4A has the positions adjacent to and facing the right side surface of the third convex part 23A and the upper side surface of the third convex part 23B as the folding positions respectively, has the position facing the first corner from the upper right diagonal direction as the position where it bends at a right angle, and is formed in a mode (zigzag structure) of reciprocating multiple times between the third convex part 23A side and the third convex part 23B side. The inner end of the spring part 4A is connected to the first edge of the mover (movable electrode 2) at a position adjacent to the third convex part 23A, and the outer end of the spring part 4A is connected to the right edge of the first opening 15A at a position adjacent to the third convex part 23B.

[0097] The spring part 4B is disposed within the second opening 15B and has an L shape following the outer shape of the second opening 15B. The spring part 4B has the positions adjacent to and facing the lower side surface of the third convex part 23B and the right side surface of the third convex part 23C as the folding positions respectively, has the position facing the second corner from the lower right diagonal direction as the position where it bends at a right angle, and is formed in a mode (zigzag structure) of reciprocating multiple times between the third convex part 23B side and the third convex part 23C side. The inner end of the spring part 4B is connected to the second edge of the mover (movable electrode 2) at a position adjacent to the third convex part 23B, and the outer end of the spring part 4B is connected to the lower edge of the second opening 15B at a position adjacent to the third convex part 23C.

[0098] The spring part 4C is disposed within the third opening 15C and has an L shape following the outer shape of the third opening 15C. The spring part 4C has the positions adjacent to and facing the left side surface of the third convex part 23C and the lower side surface of the third convex part 23D as the folding positions respectively, has the position facing the third corner from the lower left diagonal direction as the position where it bends at a right angle, and is formed in a mode (zigzag structure) of reciprocating multiple times between the third convex part 23C side and the third convex part 23D side. The inner end of the spring part 4C is connected to the third edge of the mover (movable electrode 2) at a position adjacent to the third convex part 23C, and the outer end of the spring part 4C is connected to the left edge of the third opening 15C at a position adjacent to the third convex part 23D.

[0099] The spring portion 4D is disposed within the fourth opening 15D and has an L-shaped configuration following the outer shape of the fourth opening 15D. The spring portion 4D has the positions adjacent to and facing the upper side surface of the third convex portion 23D and the positions adjacent to and facing the left side surface of the third convex portion 23A as folding positions respectively, has the position facing the fourth corner portion from the upper left diagonal direction as the position of bending at a right angle, and is formed in a mode (zigzag structure) of reciprocating a plurality of times between the third convex portion 23D side and the third convex portion 23A side. The inner end portion of the spring portion 4D is connected to the fourth edge of the mover (movable electrode 2) at a position adjacent to the third convex portion 23D, and the outer end portion of the spring portion 4D is connected to the upper edge of the fourth opening 15D at a position adjacent to the third convex portion 23A.

[0100] In the spring portions 4A - 4D, a contact portion 41 is disposed at one of a pair of adjacent folding positions, and a facing portion 42 is disposed at the other of the pair of folding positions.

[0101] When the movable electrode 2 relatively moves upward with respect to the frame portion 1 due to an impact and the third convex portion 23A contacts the first fixed electrode 11A, before that, the contact portion 41 and the facing portion 42 arranged in the vertical direction of the spring portion 4A, and the contact portion 41 and the facing portion 42 arranged in the vertical direction of the spring portion 4D contact. That is, when the downward impact is equal to or greater than the second threshold value and less than the first threshold value, the contact portion 41 and the facing portion 42 contact and the third convex portion 23A and the first fixed electrode 11A are non-contact. Also, when the downward impact is equal to or greater than the first threshold value, the contact portion 41 and the facing portion 42 contact and the third convex portion 23A and the first fixed electrode 11A contact.

[0102] When the movable electrode 2 moves relative to the frame portion 1 in the right direction due to an impact and the third convex portion 23B comes into contact with the first fixed electrode 11B, before that, the contact portion 41 and the opposing portion 42 arranged in the left-right direction of the spring portion 4A, and the contact portion 41 and the opposing portion 42 arranged in the left-right direction of the spring portion 4B come into contact. That is, when the impact in the left direction is equal to or greater than the second threshold value and less than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23B and the first fixed electrode 11B are non-contact. Further, when the impact in the left direction is equal to or greater than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23B and the first fixed electrode 11B come into contact.

[0103] When the movable electrode 2 moves relative to the frame portion 1 in the downward direction due to an impact and the third convex portion 23C comes into contact with the first fixed electrode 11C, before that, the contact portion 41 and the opposing portion 42 arranged in the up-down direction of the spring portion 4B, and the contact portion 41 and the opposing portion 42 arranged in the up-down direction of the spring portion 4C come into contact. That is, when the impact in the upward direction is equal to or greater than the second threshold value and less than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23C and the first fixed electrode 11C are non-contact. Further, when the impact in the upward direction is equal to or greater than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23C and the first fixed electrode 11C come into contact.

[0104] When the movable electrode 2 moves relative to the frame portion 1 in the left direction due to an impact and the third convex portion 23D comes into contact with the first fixed electrode 11D, before that, the contact portion 41 and the opposing portion 42 arranged in the left-right direction of the spring portion 4C, and the contact portion 41 and the opposing portion 42 arranged in the left-right direction of the spring portion 4D come into contact. That is, when the impact in the right direction is equal to or greater than the second threshold value and less than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23D and the first fixed electrode 11D are non-contact. Further, when the impact in the right direction is equal to or greater than the first threshold value, the contact portion 41 and the opposing portion 42 come into contact and the third convex portion 23D and the first fixed electrode 11D come into contact.

[0105] In the fourth embodiment, it is possible to detect impacts in two directions orthogonal to each other and their positive and negative.

[0106] [Electronic tag 100 including impact sensor 300] FIG. 10 is a schematic configuration diagram of an electronic tag 100 including an impact sensor 300 according to an embodiment of the present invention.

[0107] As shown in FIG. 10, the electronic tag 100 includes an impact sensor 300, a battery 400, a real-time clock (hereinafter referred to as RTC) 500, a latch circuit 600, a control circuit 700, an antenna 800, and a memory 900.

[0108] The RTC 500, the latch circuit 600, the control circuit 700, and the memory 900 can each be provided as an IC (Integrated Circuit) chip. Also, some or all of these multiple configurations may be mounted on a single IC package.

[0109] The electronic tag 100 is configured by housing a substrate (for example, the mounting substrate 5 in FIG. 6) on which the above-described respective configurations are mounted in a tag body 200 made of resin. The substrate may be a rigid substrate or a flexible substrate. The size of the electronic tag 100 is about several tens of [mm] in the longitudinal direction and about several [mm] in the thickness direction.

[0110] As the battery 400, for example, a button battery can be employed.

[0111] The RTC 500 has a clock function. The RTC 500 is electrically connected to the battery 400 so that power is constantly supplied. The RTC 500 constantly measures the time while power is being supplied.

[0112] The impact sensor 300 is connected to the latch circuit 600 by electric wires S1 and S2, and is electrically connected to the battery 400 via the latch circuit 600. In the present embodiment, the path for supplying power from the battery 400 to the impact sensor 300 is incorporated in the latch circuit 600.

[0113] In the first to third embodiments, for example, the electric wire S1 is connected to the first fixed electrode 11, and the electric wire S2 is connected to the second fixed electrode 12 (that is, the movable electrode 2).

[0114] Also, in the fourth embodiment, four latch circuits 600 are used. The wire S1 of the first latch circuit 600 is connected to the first fixed electrode 11A, and the wire S2 is connected to the second fixed electrode 12A (movable electrode 2). The wire S1 of the second latch circuit 600 is connected to the first fixed electrode 11B, and the wire S2 is connected to the second fixed electrode 12B (movable electrode 2). The wire S1 of the third latch circuit 600 is connected to the first fixed electrode 11C, and the wire S2 is connected to the second fixed electrode 12C (movable electrode 2). The wire S1 of the fourth latch circuit 600 is connected to the first fixed electrode 11D, and the wire S2 is connected to the second fixed electrode 12D (movable electrode 2).

[0115] The impact sensor 300 is a mechanical sensor configured to be energized when an impact (acceleration) equal to or greater than the minimum acceleration is applied and not to be energized when an impact (acceleration) equal to or greater than the minimum acceleration is not applied. The impact sensor 300 does not consume the power of the battery 400 when an impact (acceleration) equal to or greater than the minimum acceleration is not applied.

[0116] The latch circuit 600 is electrically connected to the battery 400, the impact sensor 300, and the control circuit 700.

[0117] The latch circuit 600 detects the energization between the wire S1 and the wire S2.

[0118] When the wire S1 and the wire S2 are energized, the latch circuit 600 enters an ON state in which it supplies power to the control circuit 700, and maintains the ON state even after the energization is interrupted. Thereafter, when the latch circuit 600 receives a control signal (power-off signal) from the control circuit 700, it enters an OFF state in which it does not supply power to the control circuit 700. The latch circuit 600 does not consume the power of the battery 400 in the OFF state. The latch circuit 600 will be described in detail later.

[0119] The control circuit 700 is electrically connected to the RTC 500, the latch circuit 600, the antenna 800, and the memory 900. When power is supplied from the latch circuit 600 to the control circuit 700, power is also supplied to the memory 900 via the control circuit 700. When the latch circuit 600 is in the ON state, power may be directly supplied from the latch circuit 600 to the memory 900.

[0120] When power is supplied to the control circuit 700 from the latch circuit 600, the control circuit 700 acquires the time from the RTC 500 and writes the acquired time information to the memory 900.

[0121] In the electronic tag 100, when an acceleration (impact) with an absolute value equal to or greater than a predetermined acceleration is applied to the impact sensor 300, the impact sensor 300 is energized. As a result, the latch circuit 600 supplies power to the control circuit 700, and the control circuit 700 acquires the time when the acceleration (impact) was applied to the impact sensor 300 from the RTC 500.

[0122] For example, if there is a time lag from when an impact (acceleration) is applied to the impact sensor 300 until the control circuit 700 acquires the time from the RTC 500 due to, for example, insufficient processing capacity of the control circuit 700, the control circuit 700 corrects for that time lag to substantially obtain the time when the impact (acceleration) was applied to the impact sensor 300.

[0123] When the writing of the time to the memory 900 is completed, the control circuit 700 outputs a control signal (power OFF signal) to the latch circuit 600 to put the latch circuit 600 in an OFF state where it does not supply power to the control circuit 700 and the memory 900. As a result, the supply of power to the control circuit 700 and the memory 900 is stopped. The control circuit 700 and the memory 900 do not consume the power of the battery 400 when the latch circuit 600 is in the OFF state.

[0124] The memory 900 is a non-volatile memory that retains the stored content even when power is not supplied.

[0125] The antenna 800 generates power for operating the control circuit 700 and the memory 900 by receiving radio waves emitted from the reader / writer 920 (see FIG. 13). The control circuit 700 reads the information written in the memory 900 using the power generated by the antenna 800, and sends the read information from the antenna 800 to the reader / writer 920.

[0126] It is also possible to rewrite the information stored in the memory 900 using the reader / writer 920. Note that the memory 900 also stores information that cannot be rewritten. The information that cannot be rewritten is, for example, the identification information of the electronic tag 100.

[0127] Thus, the electronic tag 100 of the present embodiment is configured as a wireless communication tag (RFID tag) compatible with RFID (Radio Frequency Identification) technology.

[0128] The electronic tag 100 may be a BLE tag that adopts the communication method of BLUETOOTH (registered trademark) Low Energy (BLE), which is a low-power communication mode.

[0129] [Latch circuit 600] FIG. 11 is a circuit diagram showing an example of the latch circuit 600 that constitutes the electronic tag 100.

[0130] As shown in FIG. 11, the latch circuit 600 is an electronic circuit including a PNP transistor Tr1, an NPN transistor Tr2, a PNP transistor Tr3, an NPN transistor Tr4, resistors R1 to R11, and a capacitor C1. The latch circuit 600 is an electronic circuit that does not have a mechanical movable part.

[0131] The resistor R1 and the resistor R2 form a series circuit. One end of the resistor R1 is connected to the power supply (Vcc), and the other end is connected to the resistor R2. One end of the resistor R2 is connected to the resistor R1, and the other end is connected to the electric wire S1. Note that the electric wire S2 is grounded.

[0132] The emitter of transistor Tr1 is connected to the battery 400 (Vcc), the collector is connected to resistor R3, and the base is connected to the midpoint of the connection between resistor R1 and resistor R2. One end of resistor R3 is connected to the collector of transistor Tr1 and the other end is grounded.

[0133] Resistors R4, R7, and R8 form a series circuit. One end of resistor R4 is connected to the midpoint of the connection between transistor Tr1 (collector) and resistor R3, and the other end is connected to resistor R7. One end of resistor R7 is connected to resistor R4 and the other end is connected to resistor R8 and the base of transistor Tr2. One end of resistor R8 is connected to resistor R7 and the base of transistor Tr2 and the other end is grounded.

[0134] One end of capacitor C1 is connected to the midpoint of the connection between resistor R4 and resistor R7, and the other end is grounded.

[0135] The collector of transistor Tr2 is connected to resistor R9, the base is connected to resistor R7, and the emitter is grounded.

[0136] The emitter of transistor Tr3 is connected to the battery 400 (Vcc), the base is connected to resistor R9, and the collector is connected to resistor R11.

[0137] One end of resistor R9 is connected to the base of transistor Tr3 and the other end is connected to the collector of transistor Tr2.

[0138] One end of resistor R11 is connected to the collector of transistor Tr3 and the other end is connected to the control circuit 700 (power input side).

[0139] The collector of transistor Tr4 is connected to resistor R6, the base is connected to resistor R10, and the emitter is grounded.

[0140] One end of resistor R6 is connected to the midpoint of the connection between resistor R4 and resistor R7, and the other end is connected to the collector of transistor Tr4.

[0141] One end of the resistor R10 is connected to the base of the transistor Tr4, and the other end is connected to the control circuit 700 (control signal output side).

[0142] One end of the resistor R5 is connected to the midpoint of the connection between the resistor R11 and the control circuit 700 (power input side), and the other end is connected to the midpoint of the connection between the resistor R4 and the resistor R7.

[0143] In the initial state (before acceleration is applied), the impact sensor 300 is not powered on, and the transistors Tr1 to Tr4 are in the OFF state (non-powered state).

[0144] When the impact sensor 300 is powered on, the voltage at the midpoint of the connection between the resistor R1 and the resistor R2 drops, and the voltage at the base of the transistor Tr1 drops, causing the transistor Tr1 to be in the ON state (powered state).

[0145] When the transistor Tr1 is in the ON state, a voltage is applied from the transistor Tr1 to the series circuit of the resistor R3 and the resistors R4, R7, and R8. The voltage at the midpoint of the connection between the resistor R4 and the resistor R7 is applied to the capacitor C1, and the voltage at the midpoint of the connection between the resistor R7 and the resistor R8 is applied to the base of the transistor Tr2.

[0146] The capacitor C1 is charged up to the voltage at the midpoint of the connection between the resistor R4 and the resistor R7.

[0147] The voltage at the midpoint of the connection between the resistor R7 and the resistor R8 is applied to the base of the transistor Tr2. When the voltage drop across the resistor R8, that is, the voltage between the base and emitter of the transistor Tr2, becomes equal to or higher than the threshold voltage (e.g., 0.6 [V]), the transistor Tr2 turns ON.

[0148] When the transistor Tr2 is in the ON state, the voltage at the base of the transistor Tr3 drops, causing the transistor Tr3 to be in the ON state.

[0149] When the transistor Tr3 turns ON, power is supplied from the battery 400 (Vcc) connected to the emitter of the transistor Tr3 to the control circuit 700 (power input side) via the collector of the transistor Tr3 and the resistor R11. At this time, the voltage at the connection midpoint between the resistor R11 and the control circuit 700 is applied to the resistors R5, R7, and R8. Therefore, the voltage caused by the collector of the transistor Tr3 and applied to the connection midpoint between the resistors R7 and R8 becomes the base voltage of the transistor Tr2. As a result, even if the impact sensor 300 becomes non-powered and the transistor Tr1 turns OFF thereafter, the ON state of the transistor Tr2 is maintained.

[0150] When a control signal (power OFF signal) is input from the control circuit 700 to the base of the transistor Tr4, the transistor Tr4 turns ON.

[0151] When the transistor Tr4 turns ON, a current flows through the resistor R6 (which has a resistance value sufficiently smaller than that of the resistor R5), so that the voltage applied to the resistor R8, that is, the voltage between the base and emitter of the transistor Tr2, becomes lower than the threshold voltage (for example, 0.6 [V]), and thus the transistor Tr2 turns OFF.

[0152] When the transistor Tr2 turns OFF, the base current of the transistor Tr3 becomes zero and the transistor Tr3 turns OFF. As a result, the power supply to the control circuit 700 stops.

[0153] As described above, when an impact (acceleration) equal to or greater than the minimum acceleration is applied to the impact sensor 300, it becomes energized, and when the absolute value of the acceleration applied thereafter decreases and falls below the minimum acceleration, it becomes non-energized and the power supply is cut off.

[0154] Therefore, if the electronic tag 100 is configured such that power is supplied to the control circuit 700 and the memory 900 only while the impact sensor 300 is energized, there is a possibility that the power supply to the control circuit 700 and the memory 900 will stop before the control circuit 700 completes writing the time to the memory 900. In this case, the time when the impact sensor 300 detects an impact cannot be recorded in the memory 900.

[0155] On the other hand, in this embodiment, by providing the latch circuit 600, the power supply to the control circuit 700 and the memory 900 is maintained until the control circuit 700 completes writing the time to the memory 900. After the control circuit 700 completes writing the time to the memory 900, the latch circuit 600 turns off, stopping the power consumption of the latch circuit 600, the control circuit 700, and the memory 900. Therefore, it is possible to prevent the occurrence of a fail in which the time when the impact sensor 300 detects an impact cannot be recorded while suppressing the consumption of the battery 400.

[0156] Also, in this embodiment, a series circuit of a resistor R1 and a resistor R2 that supply power from the battery 400 to the impact sensor 300 forms part of the latch circuit 600.

[0157] Therefore, when the impact sensor 300 detects an impact and is energized, the latch circuit 600 operates and power is supplied to the control circuit 700. That is, the current flowing through the series circuit of the resistor R1 and the resistor R2 functions as a detection signal indicating that the impact sensor 300 has detected an impact.

[0158] According to this, there is no need to separately transmit a detection signal from the impact sensor 300 to the latch circuit 600. Therefore, compared with the case where the latch circuit 600 is operated by separately transmitting a detection signal from the impact sensor 300 to the latch circuit 600, the time lag from when the impact sensor 300 detects an impact until the latch circuit 600 supplies power to the control circuit 700 can be reduced. As a result, the time lag until the control circuit 700 acquires the time from the RTC 500 is also reduced, so the reliability of the time stored in the memory 900 is increased. Also, since the time until the latch circuit 600 becomes the OFF state is shortened, consumption of the battery 400 can be suppressed.

[0159] [Operating Procedure of Electronic Tag 100] FIG. 12 is a flowchart showing the operation flow of the electronic tag 100.

[0160] In step S01, an impact (acceleration) with an absolute value greater than or equal to the minimum acceleration is applied to the electronic tag 100 (impact sensor 300).

[0161] In step S02, the impact sensor 300 is energized and becomes in an energized state.

[0162] In step S03, the latch circuit 600 becomes in the ON state and power is supplied from the latch circuit 600 to the control circuit 700 and the memory 900.

[0163] In step S04, the control circuit 700 acquires the time from the RTC 500.

[0164] In step S05, the control circuit 700 writes the acquired time into the memory 900.

[0165] In step S06, the control circuit 700 outputs a control signal (power OFF signal) to the latch circuit 600.

[0166] In step S07, the latch circuit 600 becomes in the OFF state and the supply of power from the latch circuit 600 to the control circuit 700 and the memory 900 is stopped.

[0167] [Method of Using Electronic Tag 100] FIG. 13 is a diagram for explaining the method of using the electronic tag 100.

[0168] In step (1), the electronic tag 100 is attached to the portable article 910. The portable article 910 is various articles that can be transported and to which the electronic tag 100 can be attached.

[0169] The electronic tag 100 may be attached to the portable article 910 with, for example, double-sided tape, or may be attached to the portable article 910 with a dedicated jig or the like.

[0170] In step (2), an impact is applied to the portable article 910 to which the electronic tag 100 is attached. The electronic tag 100 stores in the memory 900 the time when the impact is detected by the impact sensor 300. FIG. 13 shows a state in which a negative acceleration is applied to the portable article 910 due to dropping.

[0171] When the electronic tag 100 detects impacts a plurality of times, it stores all the times when the impacts are detected in the memory 900.

[0172] In step (3), the information stored in the memory 900 is read using the reader / writer 920.

[0173] [Effects of Embodiments of the Present Invention] A shock sensor 300 includes a stator (frame portion 1) including a first fixed electrode 11, and a rotor (movable electrode 2) including a movable electrode 2 and movable in response to an external shock. The rotor (movable electrode 2) is supported by the stator (frame portion 1) via an elastic body (spring portion 4), and when receiving a shock equal to or greater than a predetermined first threshold, compresses the elastic body (spring portion 4) and brings the movable electrode 2 into contact with the first fixed electrode 11. The shock is detected by detecting an electrical connection between the movable electrode 2 and the first fixed electrode 11 when the movable electrode 2 contacts the first fixed electrode 11. The elastic body (spring portion 4) includes a contact portion 41 and an opposing portion 42 disposed at a position opposing the contact portion 41 from the compression direction (left - right direction or up - down direction (hereinafter referred to as "left - right direction, etc.")) of the elastic body (spring portion 4). The contact portion 41 is set to contact the opposing portion 42 when the rotor (movable electrode 2) receives a shock equal to or greater than a second threshold lower than the first threshold.

[0174] With the above configuration, the vibration of the rotor (movable electrode 2) caused by a shock equal to or greater than the second threshold and less than the first threshold is suppressed. Also, even for a shock less than the second threshold, if the shock includes a vibration system related to the rotor (movable electrode 2) and the elastic body (spring portion 4), and the vibration system vibrates in the same manner as when receiving a shock equal to or greater than the second threshold, the vibration can be suppressed. Therefore, a shock smaller than the first threshold (the minimum acceleration described above), which is set as the minimum value of the shock to be detected in the movable electrode 2 and the first fixed electrode 11, is not detected, and false detection can be reduced.

[0175] In this embodiment, the elastic body (spring portion 4) is a beam portion formed to reciprocate in a direction perpendicular to the compression direction (left - right direction, etc.) while moving in the compression direction (left - right direction, etc.). The contact portion 41 is disposed on one of a pair of adjacent portions in the compression direction (left - right direction, etc.) of the beam portion, and the opposing portion 42 is disposed on the other of the pair of adjacent portions in the compression direction (left - right direction, etc.) of the beam portion.

[0176] With the above configuration, a configuration in which the contact portion 41 and the opposing portion 42 contact before the movable electrode 2 contacts the first fixed electrode 11 due to a shock can be easily constructed.

[0177] In the present embodiment, at least one of the contact portion 41 and the opposing portion 42 protrudes toward the other.

[0178] With the above configuration, the distance between the contact portion 41 and the opposing portion 42 can be made smaller more easily than the distance between the portions other than the portions where the contact portion 41 and the opposing portion 42 face each other in a pair of adjacent beams, and a configuration in which the contact portion 41 and the opposing portion 42 come into contact before the movable electrode 2 contacts the first fixed electrode 11 due to an impact can be easily constructed.

[0179] In the present embodiment, the contact portion 41 is disposed at a position facing the other of a pair of folded-back portions adjacent to each other in the compression direction (such as the left-right direction) with respect to the folded-back portion of the beam portion, and the opposing portion 42 is disposed at a position facing the contact portion 41, which is the other of a pair of folded-back portions adjacent to each other in the compression direction (such as the left-right direction).

[0180] With the above configuration, by disposing the contact portion 41 and the opposing portion 42 at the folded-back portion of the beam portion where the vibration during impact becomes large, the contact between the contact portion 41 and the opposing portion 42 can be easily achieved.

[0181] In the present embodiment, a pair of elastic bodies (spring portions 4) are arranged so as to sandwich the mover (movable electrode 2) from a direction parallel to the compression direction (such as the left-right direction), and the pair of elastic bodies (spring portions 4) support the mover (movable electrode 2) respectively.

[0182] With the above configuration, the mover (movable electrode 2) can be easily vibrated (displaced) selectively in the direction in which the elastic bodies (spring portions 4) are arranged, and the sensitivity to impacts in the direction in which the elastic bodies (spring portions 4) are arranged can be enhanced.

[0183] In the present embodiment, the contact portion 41 and the opposing portion 42 are arranged symmetrically with respect to the mover (movable electrode 2).

[0184] With the above configuration, the sensitivity to impacts in the left-right direction (positive direction) and the left-right direction (negative direction) can be made the same.

[0185] In this embodiment, the contact portion 41 and the opposing portion 42 are arranged at the center of a portion extending in a direction (vertical direction) perpendicular to the compression direction (such as the left - right direction) of the beam portion.

[0186] With the above configuration, the vibration variation of the vibration system by the movable electrode 2 and the spring portion 4 can be suppressed more than when arranged at the folded - back portion of the beam portion, and the yield of the impact sensor 300 can be improved.

[0187] In this embodiment, at least one of the contact portion 41 and the opposing portion 42, and the tip protruding toward the other has a planar shape or a convex curved - surface shape.

[0188] With the above configuration, for example, when the tip has a planar shape, the frictional load between the contact portion 41 and the opposing portion 42 increases, and when the tip has a curved - surface shape, the frictional load decreases. Therefore, by appropriately selecting the shape of the tips of the contact portion 41 and the opposing portion 42, the magnitude of the frictional load can be appropriately set.

[0189] In this embodiment, the stator (frame portion 1), the rotor (movable electrode 2), and the elastic body (spring portion 4) are integrated, and the integrated body is formed from a laminate (SOI wafer) in which an active layer 1c is laminated on a support layer (silicon substrate 1a, insulating layer 1b). The portion related to the stator (frame portion 1) of the integrated body is formed by the laminate (SOI wafer), and the portions related to the rotor (movable electrode 2) and the elastic body (spring portion 4) of the integrated body are formed by the active layer 1c obtained by removing the support layer (silicon substrate 1a, insulating layer 1b) from the laminate (SOI wafer).

[0190] With the above configuration, the impact sensor 300 can be formed by performing an etching process on the laminate (SOI wafer), and the impact sensor 300 can be manufactured simply and in large quantities.

[0191] In this embodiment, the mover (movable electrode 2) is movable in the compression direction (such as the left-right direction) by receiving an impact, and the first fixed electrode 11 is arranged at a distance from the movable electrode 2 in the compression direction (such as the left-right direction).

[0192] With the above configuration, an impact from one direction can be detected with high sensitivity.

[0193] In this embodiment, a first recess 21 whose depth direction is a direction perpendicular to the compression direction (such as the left-right direction) is arranged on either the movable electrode 2 or the first fixed electrode 11, and a first convex portion 111 that is at least partially accommodated in the first recess 21 is arranged on the other of the movable electrode 2 and the first fixed electrode 11. When the mover (movable electrode 2) moves and the first convex portion 111 and the first recess 21 come into contact with each other, an impact is detected by the contact between the movable electrode 2 and the first fixed electrode 11.

[0194] With the above configuration, a configuration in which an electrical connection between the movable electrode 2 and the first fixed electrode 11 is established by the contact between the movable electrode 2 and the first fixed electrode 11 can be easily set.

[0195] In this embodiment, the stator (frame portion 1) includes a second fixed electrode 12 that is insulated from the first fixed electrode 11, and the second fixed electrode 12 is electrically connected to the movable electrode 2 by extending to the elastic body (spring portion 4) and the mover (movable electrode 2).

[0196] With the above configuration, a configuration in which an electrical connection between the second fixed electrode 12 and the first fixed electrode 11 is established by the contact between the movable electrode 2 and the first fixed electrode 11 can be easily set.

[0197] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show one example of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

Explanation of Reference Numerals

[0198] 300 Impact Sensor 1 Frame Portion 1a Silicon Substrate 1b Insulating layer 1c Active layer 1d Support frame 11 11A 11B 11C 11D First fixed electrode 111 First convex portion 12 Second fixed electrode 121 Second convex portion 13 Groove portion 141 First beam 142 Second beam 143 Third beam 144 Fourth beam 15A First opening 15B Second opening 15C Third opening 15D Fourth opening 2 Movable electrode 21 First concave portion 22 Second concave portion 23A 23B 23C 23D Third convex portion 4 4A 4B 4C 4D 4L 4R Spring portion 41 Contact portion 41A First contact portion 41B Second contact portion 41C Third contact portion 41D Fourth contact portion 42 Opposing portion 42A First opposing portion 42B Second opposing portion 42C Third opposing portion 42D Fourth opposing portion 5 Mounting substrate 51 Pad electrode 52 Wire 100 Electronic tag 200 Tag body 300 Impact sensor 400 Battery 500 RTC 600 Latch circuit 700 Control circuit 800 Antenna 900 Memory 910 Movable item 920 Reader / writer

Claims

1. A stator including a first fixed electrode, A mover including a movable electrode and movable in response to an external impact, and The mover is supported by the stator via an elastic body and contacts the first fixed electrode while compressing the elastic body when receiving an impact equal to or greater than a predetermined first threshold value, and detects the impact by detecting an electrical connection between the movable electrode and the first fixed electrode when the movable electrode contacts the first fixed electrode. An impact sensor, The elastic body includes a contact portion and an opposing portion disposed at a position facing the contact portion from the compression direction of the elastic body, The contact portion is set to contact the opposing portion when the mover receives an impact equal to or greater than a second threshold value lower than the first threshold value. An impact sensor.

2. The elastic body is A beam portion formed in a mode of reciprocating in a direction perpendicular to the compression direction while moving in the compression direction, The contact portion is disposed on one of a pair of portions adjacent to each other in the compression direction of the beam portion, The opposing portion is disposed on the other of a pair of portions adjacent to each other in the compression direction of the beam portion. The impact sensor according to claim 1.

3. At least one of the contact portion and the opposing portion protrudes toward the other. The impact sensor according to claim 2.

4. The contact portion is disposed at one of a pair of folded portions adjacent to each other in the compression direction with respect to the folded portion of the beam portion and at a position facing the other of the pair of folded portions, The opposing portion is disposed at the other of a pair of folded portions adjacent to each other in the compression direction and at a position facing the contact portion. The impact sensor according to claim 2.

5. A pair of the elastic bodies are arranged so as to sandwich the mover from both sides in the compression direction, and the pair of elastic bodies support the mover respectively The impact sensor according to claim 2.

6. The contact portion and the opposing portion are arranged symmetrically with respect to the mover. The impact sensor according to claim 5.

7. The contact portion and the opposing portion are disposed at the center of a portion extending in a direction perpendicular to the compression direction of the beam portion. The impact sensor according to claim 2.

8. The tip of at least one of the contact portion and the opposing portion protruding toward the other has a planar shape or a convex curved surface shape. The impact sensor according to claim 3.

9. The stator, the mover, and the elastic body are integrated, and the integrated body is formed from a laminate in which an active layer is laminated on a support layer. The portion of the integrated body related to the stator is formed by the laminate. The impact sensor according to claim 1, wherein the portions of the integrated body related to the mover and the elastic body are formed by the active layer obtained by removing the support layer from the laminate.

10. The mover is movable in the compression direction by receiving the impact. The impact sensor according to claim 1, wherein the first fixed electrode is arranged to be spaced apart from the movable electrode in the compression direction.

11. A first recess is arranged in either one of the movable electrode and the first fixed electrode, with the direction perpendicular to the compression direction being the depth direction. A first protrusion is arranged in the other of the movable electrode and the first fixed electrode, with at least a part of the first protrusion being received in the first recess. The impact sensor according to claim 10, wherein the mover moves so that the first protrusion and the first recess come into contact with each other, and the impact is detected by the contact between the movable electrode and the first fixed electrode.

12. The stator includes a second fixed electrode that insulates from the first fixed electrode. The impact sensor according to claim 1, wherein the second fixed electrode is electrically connected to the movable electrode by extending to the elastic body and the mover.

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