Sensor unit and structure monitoring device

Abstract

A sensor unit and a structure monitoring device with high detection accuracy. The sensor unit (100) includes: an acceleration sensor (18x, 18y, 18z) as a physical quantity sensor; a control IC (19) as a processing portion electrically connected to the acceleration sensor (18x, 18y, 18z); a circuit substrate (15) as a substrate on which the acceleration sensor (18x, 18y, 18z) and the control IC (19) are mounted; and a container (1) that houses the circuit substrate (15). The acceleration sensor (18x, 18y, 18z) and the control IC (19) are arranged on the circuit substrate (15) in a manner not overlapping in plan view.

Description

[0001] This application is a divisional application of patent application No. 201910284564.5, filed on April 10, 2019, entitled "Sensor Unit and Structure Monitoring Device", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to a sensor unit and a structure monitoring device. Background Technology

[0003] Previously, sensor units equipped with inertial sensors, such as accelerometers or angular velocity sensors, were known as physical quantity sensors. These sensor units can function as motion sensor units. Examples include tilt sensor units (tilt meters) installed on structures such as buildings or highways, slopes of mountains, or retaining walls of embankments, as well as inertial measurement units (IMUs) that detect the attitude and behavior (inertial motion) of moving bodies (installed devices) such as agricultural machinery, construction machinery, automobiles, drones, and robots.

[0004] As such a sensor unit, Patent Document 1 describes, for example, a sensor unit that functions as a so-called six-axis motion sensor, incorporating a three-axis accelerometer and a three-axis angular velocity sensor. Each sensor is electrically connected to a microprocessor unit (MPU), which is a control IC mounted on the back side of a circuit board, and is controlled by the MPU. The MPU performs calculations based on the detection signals output from each sensor and outputs the detection values.

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-23931

[0006] However, in the sensor unit described in Patent Document 1, the heat generated by the MPU is transmitted to each sensor, and the detection signal output from each sensor changes due to the heat, resulting in a technical problem of reduced detection accuracy. Summary of the Invention

[0007] The sensor unit of this application is characterized in that it includes: a substrate; a physical quantity sensor mounted on the substrate; a processing unit mounted on the substrate in a manner that does not overlap with the physical quantity sensor when viewed from above, and electrically connected to the physical quantity sensor; a temperature sensing element mounted on the substrate; and a container for housing the substrate, the substrate including: a first region on which the processing unit is mounted; and a second region on which the physical quantity sensor is mounted.

[0008] In the aforementioned sensor unit, preferably, the temperature-sensing element is mounted in the second region.

[0009] In the aforementioned sensor unit, preferably, the temperature sensing element is mounted on the surface of the second region on the side where the physical quantity sensor is mounted.

[0010] In the above-described sensor unit, preferably, the substrate has a connection region between the first region and the second region, and in a cross-sectional view taken from a first direction oriented from which the first region and the second region are arranged, the cross-sectional area S3 of the connection region is smaller than the cross-sectional area S1 of the first region and the cross-sectional area S2 of the second region.

[0011] In the aforementioned sensor unit, preferably, the connection area is a contracted portion that tapers along the outer edge of the substrate in the first direction when viewed from above.

[0012] In the aforementioned sensor unit, preferably, when viewed from above, the contraction portion is disposed on both sides of the substrate in a second direction orthogonal to the first direction.

[0013] In the above-described sensor unit, preferably, the sensor unit includes a connector mounted on the first region of the substrate.

[0014] In the above-mentioned sensor unit, preferably, the temperature sensing element is a thermistor or a diode.

[0015] In the aforementioned sensor unit, preferably, the physical quantity sensor detects at least one of acceleration and angular velocity.

[0016] The structure monitoring device of this application is characterized by comprising: a sensor unit as described in any of the above; a receiving unit for receiving a detection signal from the sensor unit installed on the structure; and a calculation unit for calculating the tilt angle of the structure based on the signal output from the receiving unit. Attached Figure Description

[0017] Figure 1 This is a perspective view showing the state in which the sensor unit according to the first embodiment of the present invention is fixed to the mounting surface.

[0018] Figure 2 It shows from Figure 1 A perspective view of the sensor unit as seen from the side of the mounting surface.

[0019] Figure 3 Is with Figure 1 An exploded 3D view of sensor units in the same state.

[0020] Figure 4 It shows from and Figure 3 A three-dimensional view of the approximate structure of a substrate (circuit board) viewed from the same direction.

[0021] Figure 5 This shows the substrate (circuit board) from Figure 4 A three-dimensional view of the approximate structure as seen from the opposite side.

[0022] Figure 6 This is a cross-sectional view showing an outline of the sensor unit.

[0023] Figure 7 This is a top view showing an outline of the container.

[0024] Figure 8 It is a three-dimensional diagram illustrating the general structure of an acceleration sensor element.

[0025] Figure 9 This is a cross-sectional view illustrating the general structure of an accelerometer detector using accelerometer sensor elements.

[0026] Figure 10 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the second embodiment of the present invention.

[0027] Figure 11 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the third embodiment of the present invention.

[0028] Figure 12 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the fourth embodiment of the present invention.

[0029] Figure 13 This is a configuration diagram showing the structure monitoring device according to the fifth embodiment of the present invention.

[0030] Explanation of reference numerals in the attached figures

[0031] 1. Container; 2. Lid; 3. Threaded hole; 4. Fixing protrusion; 11. Side wall; 12. Bottom wall; 12r. Lower surface; 15. Circuit board as substrate; 15f. First surface; 15r. Second surface; 16. Plug-type (male) connector; 18x, 18y, 18z. Accelerometer as physical quantity sensor; 19. Control IC as processing unit; 20. Temperature sensing element; 21. Opening; 22. Inner surface; 23. Opening surface; 25, 26. Second base; 27··· First base; 29··· Protrusion; 30··· Fixing component; 33, 34··· Retractable part; 41··· Sealing component; 42··· Fixing component; 70··· Fixing screw; 71··· Mounting surface; 72··· Screw; 74··· Internal thread; 76··· Through hole; 100··· Sensor unit; 200··· Accelerometer sensor element; 300··· Accelerometer sensor; 500··· Structure monitoring device; AL1··· First area; AL2··· Second area; AL3··· Connection area. Detailed Implementation

[0032] The following describes this embodiment. Furthermore, the embodiments described below are not intended to unduly limit the scope of the invention as described in the patent application. Additionally, all structures described in this embodiment are not necessarily essential components of the invention.

[0033] [Sensor Unit]

[0034] <First Implementation Method>

[0035] First, refer to Figure 1 as well as Figure 2 The sensor unit 100 according to the first embodiment of the present invention will be described below.

[0036] Figure 1 This is a perspective view showing the state in which the sensor unit according to the first embodiment of the present invention is fixed to the mounting surface. Figure 2 It shows from Figure 1 A perspective view of the sensor unit as seen from the side of the mounting surface.

[0037] like Figure 1 As shown, sensor unit 100 is an inertial measurement device that detects the attitude and behavior (inertial motion) of mobile bodies (installed devices) such as automobiles, agricultural machinery, construction machinery, robots, and drones. Sensor unit 100 functions as a physical quantity sensor, specifically as a so-called three-axis motion sensor, which has three accelerometers that detect the acceleration of each of the three axes.

[0038] The sensor unit 100 has a rectangular cuboid shape, with a length of approximately 50 mm along its long side in the first direction (X-axis direction), a length of approximately 24 mm along its short side in the second direction (Y-axis direction) orthogonal to the first direction, and a thickness of approximately 16 mm. Fixing protrusions 4 are provided at two locations near each end of one long side and at one location in the center of the other long side of the sensor unit 100, each with a threaded hole 3. Fixing screws 70 pass through each of the three threaded holes 3, and are used to fix the sensor unit 100 to the mounting surface 71 of a structure (device) that serves as an adhesive part, such as a bridge or bulletin board. Furthermore, the dimensions of the sensor unit 100 described above are only one example; by selecting or modifying the design of components, it can be miniaturized to a size suitable for mounting in, for example, HMDs (head-mounted displays, smart glasses), smartphones, or digital cameras. Furthermore, the opening opposite to the mounting surface 71 of the sensor unit 100 is covered by a cover 2 that is configured as a guide for the fixing protrusion 4. Additionally, the cover 2 passes through a through hole 76 comprising three recesses (lower sections) and is sealed via a sealing member 41 (see reference). Figure 3 It is fixed to container 1.

[0039] like Figure 2 As shown, an opening 21 is provided on the surface viewed from the mounting surface of the sensor unit 100. A plug-type (male) connector 16 is disposed inside (inner side) of the opening 21. The connector 16 has a plurality of pins arranged in two rows, with the pins in each row arranged along a second direction (Y-axis direction). A socket-type (female) connector (not shown) is connected to the mounting device on the plug-type (male) connector 16, and electrical signals such as the drive voltage and detection data of the sensor unit 100 are transmitted and received between the two. Furthermore, the plug-type (male) connector 16 is mounted on a circuit board 15 (see reference 15), which serves as a substrate. Figure 5 ).

[0040] The structure of the sensor unit 100 in this embodiment is not limited to a triaxial motion sensor; any unit or device equipped with a physical quantity sensor (inertial sensor) can be used.

[0041] Furthermore, in the following description, in top view, the direction along the long side of the rectangular sensor unit 100 is the first direction (X-axis direction). Additionally, in top view, the direction orthogonal to the first direction (X-axis direction) (along the short side) is the second direction (Y-axis direction). Furthermore, the thickness direction of the sensor unit 100 will be described as the third direction (Z-axis direction).

[0042] [Structure of the sensor unit]

[0043] Next, besides Figure 1 as well as Figure 2 Other than that, refer to Figure 3 , Figure 4 , Figure 5 , Figure 6 as well as Figure 7 The structure of the sensor unit 100 will be described.

[0044] Figure 3 Is with Figure 1 An exploded 3D view of sensor units in the same state. Figure 4 It shows from and Figure 3 A three-dimensional view of the approximate structure of a substrate (circuit board) viewed from the same direction. Figure 5 This shows the substrate (circuit board) from Figure 4 A three-dimensional view of the approximate structure as seen from the opposite side. Figure 6 This is a cross-sectional view showing an outline of the sensor unit. Figure 7 This is a top view showing an outline of the container.

[0045] like Figure 3 As shown, the sensor unit 100 comprises a container 1, a cover 2, a sealing member 41, and a circuit board 15 serving as a substrate. Specifically, the sensor unit 100 is configured such that the circuit board 15 is mounted via fixing members 30 and 42 (see reference 1). Figure 6 as well as Figure 7 It is installed inside the container 1 and covers the opening of the container 1 by means of the cover 2 via the sealing member 41.

[0046] Container 1 is a box-shaped component made of, for example, aluminum, with an internal space, and serves as a container for the circuit board 15. Container 1 can be formed by cutting aluminum or by die casting (mold casting). Furthermore, the material of container 1 is not limited to aluminum; other metals such as zinc or stainless steel, resin, or composite materials of metal and resin can also be used. The shape of container 1 is the same as the overall shape of the sensor unit 100 described above, being a roughly rectangular shape. Fixing protrusions 4 are provided at two locations near each end of one long side and at one location in the center of the other long side, and threaded holes 3 are formed on each of these fixing protrusions 4. Here, the fixing protrusions 4 at the two locations near each end of one long side include the intersection of the short and long sides, and are roughly triangular in shape when viewed from above. Additionally, the fixing protrusion 4 at one location in the center of the other long side is roughly trapezoidal in shape when viewed from above, facing the internal space of container 1.

[0047] Furthermore, the structure involved in fixing the container 1 is not limited to the threaded hole 3. For example, it can be formed by forming a notch that allows screws to be tightened (a notch is formed in the fixing protrusion 4 at the corner or the fixing protrusion 4 at the center of the container 1 where the threaded hole 3 is located). Alternatively, it can be formed by forming a flange (ear) on the side of the container 1 to tighten the flange portion with screws. However, when using the notch hole as the fixing part for screw tightening, if the notch hole is larger than the diameter of the screw head, the screw head will deviate from the notch and become tilted during screw tightening. This poses a risk that the screw tightening may easily fall off, and the notch hole portion of the outer shell may be deformed or scratched due to the deviated screw. Therefore, when providing a notch hole as the fixing part, it is preferable to design the notch hole to be smaller than the diameter of the screw head constituting the seat surface.

[0048] Container 1 is a box-shaped container with a cuboid shape and an opening on one side. The interior (inner side) of container 1 is an internal space (accommodation space) surrounded by a bottom wall 12 and a side wall 11. In other words, container 1 is box-shaped with an opening 23 on the side opposite to the bottom wall 12, the outer edge of the circuit board 15 is arranged (accommodated) along the inner surface 22 of the side wall 11, and the cover 2 is fixed to cover the opening. Here, the opening 23 opposite to the bottom wall 12 is the surface on which the cover 2 is placed. On the opening 23, a fixing protrusion 4 is erected at two locations near each end of one long side of container 1 and at one location in the center of the other long side. In addition, the upper surface of the fixing protrusion 4 (the surface exposed in the -Z direction) is the same as the upper surface of container 1.

[0049] In addition, such as Figure 6 as well as Figure 7 As shown, in the internal space (accommodation space) of container 1, a protrusion 29 protruding from the side wall 11 toward the internal space is provided at the center of one of the long sides, opposite to the fixing protrusion 4 provided at the center of the other long side, extending from the bottom wall 12 to the opening surface 23. An internal thread 74 for fixing the cover 2 is provided on the upper surface of the protrusion 29 (the same surface as the opening surface 23). Here, the fixing protrusion 4 provided at the center of the other long side is the same as the protrusion 29, and can also be a structure that protrudes from the side wall 11 toward the internal space from the bottom wall 12 to the opening surface 23. Furthermore, the protrusion 29 and the fixing protrusion 4 are provided at the contraction portions 33 and 34 of the circuit board 15 described later (see reference). Figure 4 (Relative position)

[0050] Furthermore, within the internal space (reception space) of container 1, a first base 27 and second bases 25 and 26, protruding in a stepped manner from the bottom wall 12 toward the opening surface 23, are provided. Figure 6 as well as Figure 7 As shown, a first base 27 is positioned opposite the configuration area of ​​a male connector 16 mounted on the circuit board 15, and has an opening 21 for inserting the male connector 16. The first base 27 functions as a base for securing the circuit board 15 to the container 1 via a fixing member 42 disposed around the male connector 16. Furthermore, the opening 21 extends through the inner surface of the first base 27 and the lower surface 12r, which is the outer surface of the container 1. That is, the opening 21 extends through both the interior (inner side) and exterior of the container 1.

[0051] The second bases 25 and 26 are located on the opposite side of the first base 27, relative to the fixing protrusions 4 and 29 located at the center of the long side, and are disposed near the fixing protrusions 4 and 29. Alternatively, the second bases 25 and 26 can be connected to either the fixing protrusions 4 and 29. The second bases 25 and 26 function as bases for fixing the circuit board 15 to the container 1 on the opposite side of the first base 27 relative to the fixing protrusions 4 and 29.

[0052] Furthermore, an example of a container 1 with a roughly rectangular, box-like shape without a lid has been described, but this is not a limitation. The planar shape of the container 1 can also be a square, or a polygon such as a hexagon or octagon, or a polygon with chamfered corners and curved sides. Additionally, the planar shape of the interior (inner side) of the container 1 is not limited to the illustrated shape above and can be other shapes. Furthermore, the planar shapes of the container 1's exterior and interior can be similar or dissimilar.

[0053] The circuit board 15, serving as the substrate, is a multilayer substrate with multiple through-holes, and a glass epoxy resin substrate is used. However, it is not limited to a glass epoxy resin substrate; a rigid substrate capable of mounting multiple physical quantity sensors, electronic components, connectors, etc., can also be used. For example, a composite substrate or a ceramic substrate can be used.

[0054] like Figure 4 as well as Figure 5As shown, the circuit board 15 has a second surface 15r on one side of the bottom wall 12 and a first surface 15f opposite to the second surface 15r. The circuit board 15 is divided into a first region AL1, which houses a control IC 19 as a processing unit and a plug-type (male) connector 16; a second region AL2, which houses accelerometers 18x, 18y, and 18z as physical quantity sensors; and a connection region AL3 located between the first region AL1 and the second region AL2. Therefore, the control IC 19 and the accelerometers 18x, 18y, and 18z are arranged in a non-overlapping manner when viewed from above. In addition, various wiring and terminal electrodes are provided on the circuit board 15, but their illustrations and descriptions are omitted.

[0055] like Figure 4 As shown, a control IC 19 is mounted on the first surface 15f of the first region AL1, and three acceleration sensors 18x, 18y, and 18z are mounted on the first surface 15f of the second region AL2. Additionally, as... Figure 5 As shown, a plug-type (male) connector 16 is mounted on the second surface 15r of the first region AL1. Therefore, the first surface 15f is the surface of the circuit board 15 on which the control IC 19 and the acceleration sensors 18x, 18y, and 18z are mounted.

[0056] Viewed from above, the circuit board 15 has contraction portions 33 and 34 at its center along a first direction (X-axis direction) along the long side of the container 1, where the outer edge of the circuit board 15 tapers towards the center. Viewed from above, the contraction portions 33 and 34 are located on both sides of the circuit board 15 along a second direction (Y-axis direction) orthogonal to the first direction, contracting from the outer edge of the circuit board 15 towards the center, and are located at the protrusion 29 and the fixing protrusion 4 (see reference 4) of the container 1. Figure 3 The relative positions. Furthermore, the area where the contraction portions 33 and 34 are located is the connecting region AL3. Therefore, the connecting region AL3 is set with a cross-sectional area S3 ( Figure 4 The cross-sectional area of ​​the CC section shown is smaller than that of the section along the second direction (Y-axis direction) orthogonal to the first direction when viewed from the first direction (X-axis direction), which is the arrangement direction of the first region AL1 and the second region AL2, i.e., it is smaller than... Figure 4 The cross-sectional area S1 of the first region AL1 of the AA cross section shown is... Figure 4 The cross-sectional area S2 of the second region AL2 in the BB cross-section shown is small. Specifically, the connection region AL3 can be set between the position where the contraction begins on the outer edge of the first region AL1 side and the position where the contraction begins on the outer edge of the second region AL2 side in the contraction portions 33 and 34 of the circuit board 15. Figure 5 (between the two double-dotted lines shown in the image).

[0057] As described above, the control IC 19 and the acceleration sensors 18x, 18y, and 18z do not overlap. The control IC 19 is mounted in the first region AL1 of the circuit board 15, and the acceleration sensors 18x, 18y, and 18z are mounted in the second region AL2. Therefore, the acceleration sensors 18x, 18y, and 18z can be separated from the heat-generating control IC 19, making it difficult for the heat generated by the control IC 19 to spread to the acceleration sensors 18x, 18y, and 18z. Thus, the reduction in the detection accuracy of the sensor unit 100 caused by the heat generated by the control IC 19 spreading to the acceleration sensors 18x, 18y, and 18z can be reduced.

[0058] The circuit board 15 is inserted into the internal space of the container 1 with its second surface 15r facing the first base 27 and the second bases 25 and 26. Furthermore, the circuit board 15 is mounted to the container 1 on the first base 27 via a fixing member 42 arranged in a ring around the mounted plug-type (male) connector 16, and a fixing member 30 arranged on the second bases 25 and 26. That is, the circuit board 15 is mounted to the first base 27 and the second bases 25 and 26 of the container 1 via the fixing members 42 and 30, in the area around the plug-type (male) connector 16 in the first region AL1 and on one side of the connection area AL3 in the second region AL2.

[0059] The fixing member 42 is able to ensure airtightness between the container 1 and the circuit board 15 around the connector 16 by being arranged in a ring around the connector 16, thus preventing foreign objects such as dust or dirt from entering the interior of the container 1 from the area around the connector 16 exposed to the outside.

[0060] The plug-type (male) connector 16 is arranged at equal intervals along the Y-axis and has two rows of connection terminals arranged along the X-axis. Preferably, there are 20 connection terminals with 10 pins per row, but the number of terminals can be appropriately changed according to design specifications.

[0061] Accelerometers 18x, 18y, and 18z, which function as physical quantity sensors, are each capable of detecting acceleration along one axis. Preferably, accelerometers 18x, 18y, and 18z are vibration-type accelerometers that use crystal as oscillators and detect acceleration based on the resonant frequency, which varies according to the force applied to the oscillator. Further explanation of these accelerometers 18x, 18y, and 18z will be provided later.

[0062] Accelerometer 18x is upright with its sides facing the first surface 15f of the circuit board 15, with the front and back of the package facing the X-axis, and detects acceleration applied in the X-axis direction. Accelerometer 18y is upright with its sides facing the first surface 15f of the circuit board 15, with the front and back of the package facing the Y-axis, and detects acceleration applied in the Y-axis direction. Accelerometer 18z is connected with its front and back of the package facing the Z-axis, i.e., with the front and back of the package directly facing the first surface 15f of the circuit board 15, and detects acceleration applied in the Z-axis direction.

[0063] Furthermore, the accelerometers 18x, 18y, and 18z are not limited to vibration-type accelerometers using crystals; any sensor capable of detecting acceleration is acceptable. Other sensors could include, for example, capacitive accelerometers, piezoresistive accelerometers, or thermal accelerometers formed using MEMS technology on a silicon substrate. Additionally, the structure is not limited to using three accelerometers 18x, 18y, and 18z for each axis; any sensor capable of detecting acceleration along all three axes is acceptable. For example, a sensor device capable of detecting (sensing) acceleration along all three axes using a single package could also be used.

[0064] The control IC 19, serving as the processing unit, is electrically connected to the accelerometer sensors 18x, 18y, and 18z via wiring not shown. The control IC 19 is a microcontroller unit (MCU) with built-in storage including non-volatile memory and an A / D converter, controlling various parts of the sensor unit 100. The storage unit stores programs specifying the order and content of acceleration detection, programs digitizing the detection data and merging it into grouped data, and accompanying data. Additionally, several electronic components are mounted on the circuit board 15, but are not shown.

[0065] [Example of an accelerometer structure]

[0066] Here, refer to Figure 8 as well as Figure 9 The structure of the accelerometers 18x, 18y, and 18z is described.

[0067] Figure 8 It is a three-dimensional diagram illustrating the general structure of an acceleration sensor element. Figure 9 This is a front view (sectional view) illustrating the general structure of an accelerometer detector using accelerometer sensor elements.

[0068] In addition, Figure 8In the diagram, the x-axis, y'-axis, and z'-axis are shown as three mutually orthogonal axes. Regarding these axes, in an orthogonal coordinate system formed by the x-axis (electrical axis), y-axis (mechanical axis), and z-axis (optical axis) of the piezoelectric material (crystal) used as the substrate of the accelerometer, when the x-axis is the rotation axis, and the z-axis is tilted by a rotation angle φ (preferably -5°≤φ≤15°) by rotating the z-axis in the -y direction towards the +z side of the y-axis, and the y'-axis is tilted by a rotation angle φ by rotating the y-axis in the +z direction towards the +y side of the z-axis, an example is given using a so-called crystal z-plate (z'-plate) as the substrate. This z-plate is machined into a flat plate shape along a plane defined by the x-axis and y'-axis and has a predetermined thickness t in the z'-axis direction orthogonal to that plane. Furthermore, the z'-axis is the axis along the direction of gravity in the accelerometers 18x, 18y, and 18z.

[0069] [Structure of an accelerometer sensor element]

[0070] First, refer to Figure 8 The structure of the acceleration sensor element 200 will be described below. The acceleration sensor element 200 includes: a substrate structure 201, including a base 210, etc.; an acceleration detection element 270, which is connected to the substrate structure 201 and detects physical quantities; and mass parts 280 and 282.

[0071] The substrate structure 201 of the accelerometer sensor element 200 includes: a base 210; a movable portion 214 connected to the base 210 via a connector 212; a connecting portion 240; and a first support portion 220, a second support portion 230, a third support portion 250, and a fourth support portion 260 connected to the base 210. Here, the third support portion 250 and the fourth support portion 260 are connected to the side where the connecting portion 240 is located.

[0072] The substrate structure 201 uses a crystal substrate formed by cutting a crystal z-plate (z' plate) at a predetermined angle from a piezoelectric material, such as raw crystal, as described above. This crystal substrate is patterned and integrally formed into the substrate structure 201. Furthermore, patterning can be performed using, for example, photolithography and wet etching techniques.

[0073] The base 210 is connected to the movable part via the connector 212 and supports the movable part 214. The base 210 is connected to the movable part 214 via the connector 212, the connecting part 240 located on the opposite side of the side where the connector 212 is located, the first support part 220 and the second support part 230, the third support part 250 and the fourth support part 260 connected on the connecting part 240 side.

[0074] A connector 212 is disposed between the base 210 and the movable portion 214, connecting the base 210 and the movable portion 214. The thickness (length in the z' axis direction) of the connector 212 is set to be thinner (shorter) than the thickness of both the base 210 and the movable portion 214, and is formed in a contracted shape in a cross-sectional view from the x-axis direction. The connector 212 can be provided, for example, by performing a so-called half-etching on the substrate structure 201 including the connector 212 to form a thin-walled portion with a relatively thin thickness. When the movable portion 214 is displaced (rotated) relative to the base 210, the connector 212 functions as a fulcrum (intermediate hinge) and acts as a rotation axis along the x-axis direction.

[0075] The movable part 214 is connected to the base 210 via the joint part 212. The movable part 214 is plate-shaped and has main surfaces 214a and 214b that are opposite to each other along the z' axis. The movable part 214 can be displaced along the direction intersecting the main surfaces 214a and 214b (z' axis direction) with the joint part 212 as the fulcrum (rotation axis) based on the physical quantity, i.e., acceleration, applied in the direction intersecting the main surfaces 214a and 214b.

[0076] The connecting part 240 is configured such that it extends from the base 210 on the +x direction side where the third support part 250 is provided (described later) and surrounds the movable part 214 along the X-axis direction, and is connected to the base 210 on the -x direction side where the fourth support part 260 is provided (described later).

[0077] The first support portion 220 and the second support portion 230 are configured symmetrically about the acceleration detection element 270. Similarly, the third support portion 250 and the fourth support portion 260 are configured symmetrically about the acceleration detection element 270. Furthermore, in the first support portion 220, the second support portion 230, the third support portion 250, and the fourth support portion 260, the substrate structure 201 has a support fixing portion (see reference). Figure 9 The function of the accelerometer 300 package 310 (described later).

[0078] An acceleration detection element 270 is configured to connect the base 210 and the movable portion 214 of the substrate structure 201. In other words, the acceleration detection element 270 is configured to span the base 210 and the movable portion 214 of the substrate structure 201. The acceleration detection element 270 has vibration beam portions 271a and 271b, a first base 272a, and a second base 272b, which serve as vibration portions. The first base 272a and the second base 272b are connected to the acceleration detection element 270 at the base 210. For example, the movable portion 214 generates displacement based on a physical quantity, generating stress on the vibration beam portions 271a and 271b, thereby changing the detected information of the physical quantity generated on the vibration beam portions 271a and 271b. In other words, the vibration frequency (resonance frequency) of the vibration beam portions 271a and 271b changes. In this embodiment, the acceleration detection element 270 is a double tuning fork element (double tuning fork type vibration element) having two vibrating beam portions 271a and 271b, a first base portion 272a, and a second base portion 272b. The vibrating beam portions 271a and 271b, which are the vibrating parts, can also be referred to as vibrating wrists, vibrating beams, or columnar beams.

[0079] The acceleration detection element 270 is the same as the substrate structure 201 described above, using a crystal substrate made of a piezoelectric material, such as raw crystal, cut at a predetermined angle. The acceleration detection element 270 is formed by patterning the crystal substrate using photolithography and wet etching techniques. As a result, the vibration beams 271a and 271b, as well as the first base 272a and the second base 272b, can be integrally formed.

[0080] Furthermore, the acceleration detection element 270 is not limited to the crystal substrate described above. For example, piezoelectric materials such as lithium tantalate (LiTaO3), lithium tetraborate (Li2B4O7), lithium niobate (LiNbO3), lead zirconate titanate (PZT), zinc oxide (ZnO), and aluminum nitride (AlN) can be used. Additionally, semiconductor materials such as silicon with a piezoelectric coating such as zinc oxide (ZnO) or aluminum nitride (AlN) can be used. However, it is preferable to use the same material as the substrate structure 201.

[0081] For example, an output electrode (not shown) and an excitation electrode are provided on the acceleration detection element 270, but the description is omitted.

[0082] Masses 280 and 282 are disposed on the main surface 214a of the movable part 214 and on the main surface 214b, which is opposite to the main surface 214a and serves as the back surface. More specifically, masses 280 and 282 are disposed on the main surfaces 214a and 214b via a mass bonding material (not shown). Examples of materials used for masses 280 and 282 include metals such as copper (Cu) and gold (Au).

[0083] In addition, in this embodiment, the acceleration detection element 270 is constructed by a double tuning fork oscillator (double tuning fork type vibration element) whose vibration part is composed of two columnar beams 271a and 271b. However, the vibration part may also be constructed by a single columnar beam (single beam).

[0084] [Structure of the accelerometer]

[0085] Next, refer to Figure 9 The structure of the acceleration detector 300 using the acceleration sensor element 200 described above will be explained. Furthermore, the acceleration detector 300 described here can be used as the acceleration sensors 18x, 18y, and 18z of the sensor unit 100 described above.

[0086] like Figure 9 As shown, the accelerometer 300 houses the aforementioned accelerometer sensor element 200. The accelerometer 300 includes the accelerometer sensor element 200 and a package 310. The package 310 also includes a package base 320 and a cover 330. The accelerometer 300 houses (mounts) the accelerometer sensor element 200 within the package 310. More specifically, the accelerometer sensor element 200 is housed (mounted) within the space 311 where the package base 320 and the cover 330 are connected.

[0087] The encapsulation base 320 has a recess 321, within which an acceleration sensor element 200 is disposed. The shape of the encapsulation base 320 is not particularly limited, as long as it allows the acceleration sensor element 200 to be disposed within the recess 321. In this embodiment, ceramic is used as the encapsulation base 320, for example. However, it is not limited to this; materials such as crystal, glass, and silicon can be used.

[0088] The package base 320 has a stepped portion 323 that protrudes from the inner bottom surface (the bottom surface inside the recess) 322 of the package base 320 toward the cover 330. The stepped portion 323 is provided, for example, along the inner wall of the recess 321. A plurality of internal terminals 340b are provided on the stepped portion 323.

[0089] Internal terminals 340b are positioned opposite (overlapping in top view) to the fixing connection terminals 79b of each fixing part, which are located on the first support part 220, second support part 230, third support part 250, and fourth support part 260 of the accelerometer sensor element 200. The internal terminals 340b are electrically connected to the fixing connection terminals 79b, for example, using a conductive adhesive 343 containing conductive materials such as metal fillers, similar to silicone resin. Thus, the accelerometer sensor element 200 is mounted on the encapsulation base 320 and housed within the encapsulation 310.

[0090] An external terminal 344 for use when mounting external components is provided on the outer bottom surface (the side opposite to the inner bottom surface 322) 324 of the package base 320. The external terminal 344 is electrically connected to the internal terminal 340b via internal wiring (not shown).

[0091] The internal terminal 340b and the external terminal 344 are configured as, for example, a metal film formed by laminating a coating of nickel (Ni), gold (Au), etc. onto a metallization layer of tungsten (W) by methods such as electroplating.

[0092] On the package base 320, a sealing portion 350 is provided at the bottom of the recess 321 to seal the interior (cavity) of the package 310. The sealing portion 350 is disposed within a through hole 325 formed in the package base 320. The through hole 325 extends from the outer bottom surface 324 to the inner bottom surface 322. Figure 9 In the example shown, the through-hole 325 has a stepped shape with a larger diameter on the outer bottom surface 324 side than on the inner bottom surface 322 side. The sealing portion 350 is provided in the through-hole 325 with a sealing material, such as a gold (Au) and germanium (Ge) alloy, solder, etc., which is hardened after being heated and melted. The sealing portion 350 is used to hermetically seal the interior of the package 310.

[0093] The cover 330 is configured to cover the recess 321 of the encapsulation base 320. The shape of the cover 330 is, for example, plate-shaped. As the cover 330, for example, the same material as the encapsulation base 320 or an alloy of iron (Fe) and nickel (Ni), stainless steel, or other metals can be used. The cover 330 is engaged with the encapsulation base 320 via a cover engaging member 332. As the cover engaging member 332, for example, a sealing ring, low-melting-point glass, inorganic adhesive, etc., can be used.

[0094] After the cover 330 is attached to the package base 320, under a depressurized state (high vacuum state) inside the package 310, a sealing material is placed in the through hole 325, and a sealing part 350 is formed by heating and melting the material and then hardening it, thereby enabling the package 310 to be hermetically sealed. The interior of the package 310 can also be filled with inert gases such as nitrogen, helium, and argon.

[0095] In the accelerometer 300, when a drive signal is applied to the excitation electrode of the accelerometer element 200 via the external terminal 344, the internal terminal 340b, the fixing connection terminal 79b, etc., the vibrating beam portions 271a and 271b of the accelerometer element 200 vibrate (resonate) at a predetermined frequency. Furthermore, the accelerometer 300 can output the resonant frequency of the accelerometer element 200, which varies according to the applied acceleration, as an output signal.

[0096] According to the sensor unit 100 described above, the heat generated from the control IC 19 mounted in the first region AL1 of the circuit board 15 is slowed down due to the propagation speed of the connection region AL3 with a cross-sectional area of ​​S3, making it difficult for the heat to propagate to the accelerometers 18x, 18y, and 18z mounted in the second region AL2 of the circuit board 15. Specifically, by providing the contraction portions 33 and 34, the cross-sectional area S3 of the connection region AL3 is smaller than the cross-sectional area S1 of the first region AL1 where the control IC 19 is mounted and the cross-sectional area of ​​the second region AL2 where the accelerometers 18x, 18y, and 18z are mounted. Therefore, the propagation speed of the heat generated from the control IC 19 mounted in the first region AL1 can be slowed down in the connection region AL3, making it difficult for the heat generated from the control IC 19 to propagate to the accelerometers 18x, 18y, and 18z mounted in the second region AL2. Therefore, the sensor unit 100 can reduce the decrease in detection accuracy caused by the heat generated by the control IC 19 propagating to the accelerometers 18x, 18y, and 18z.

[0097] <Second Implementation Method>

[0098] Next, the sensor unit 100a according to the second embodiment of the present invention will be described.

[0099] Figure 10 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the second embodiment of the present invention.

[0100] The circuit board 15a of the sensor unit 100a in this embodiment is the same as that of the sensor unit 100 in the first embodiment, except for the different structure of the circuit board 15a. Furthermore, in the following description, the circuit board 15a of the sensor unit 100a in the second embodiment will be described focusing on the differences from the first embodiment; identical aspects will be omitted. Figure 10 In this document, the same reference numerals are added to structures that are the same as those in the first embodiment described above.

[0101] like Figure 10 As shown, the sensor unit 100a of this embodiment includes a circuit board 15a on the first surface of the second region AL2, which is equipped with three acceleration sensors 18x, 18y, and 18z capable of detecting acceleration in one axial direction, and a temperature sensing element 20. Furthermore, a control IC 19 is mounted on the first surface of the first region AL1 of the circuit board 15a, and a plug-type (male) connector (not shown) is mounted on the second surface of the circuit board 15a, which is opposite to the first surface of the first region AL1.

[0102] A temperature sensing element 20 is positioned close to the three accelerometers 18x, 18y, and 18z on the first surface of the circuit board 15a to sense the heat propagating to the accelerometers 18x, 18y, and 18z. Subsequently, based on the temperature measurement results, the output characteristics of the accelerometers 18x, 18y, and 18z are corrected for temperature in the control IC 19. Therefore, by using the temperature sensing element 20 to sense the heat propagating to the accelerometers 18x, 18y, and 18z, the reduction in detection accuracy of the sensor unit 100a due to the influence of heat can be reduced.

[0103] In addition, the temperature sensing element 20 can be, for example, a thermistor or a diode, as long as it is a temperature sensing device capable of detecting temperature.

[0104] With this structure, the sensor unit 100a with circuit board 15a can reduce the influence of heat propagating to the accelerometers 18x, 18y, and 18z, thereby achieving higher detection accuracy.

[0105] The second embodiment described above can achieve the same effect as the first embodiment described above.

[0106] <Third Implementation Method>

[0107] Next, the sensor unit 100b according to the third embodiment of the present invention will be described.

[0108] Figure 11 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the third embodiment of the present invention.

[0109] The circuit board 15g of the sensor unit 100b in this embodiment is the same as the circuit board 15g of the sensor unit 100 in the first embodiment, except for the different structure of the circuit board 15g. Furthermore, in the following description, the circuit board 15g of the sensor unit 100b in the third embodiment will be described focusing on the differences from the first embodiment; identical aspects will be omitted. Figure 11 In this document, the same reference numerals are added to structures that are the same as those in the first embodiment described above.

[0110] like Figure 11As shown, the sensor unit 100b of this embodiment includes a circuit board 15g mounted on the first surface of the second region AL2. Three accelerometers 18x, 18y, and 18z, capable of detecting acceleration in one axial direction, and an angular velocity sensor 17, capable of detecting angular velocity in all three axial directions, serve as physical quantity sensors. The angular velocity sensor 17 can detect the angular velocity in three directions (three axes) using a single device. It employs a vibrating gyroscope sensor formed using MEMS technology on a silicon substrate to detect the angular velocity based on the Coriolis force applied to the vibrating object. Furthermore, a control IC 19 is mounted on the first surface of the first region AL1 of the circuit board 15g, and a plug-type (male) connector (not shown) is mounted on the second surface of the circuit board 15g, which is opposite to the first surface of the first region AL1.

[0111] With this structure, the sensor unit 100b, equipped with the circuit board 15g, can be used, for example, as an inertial measurement unit (IMU) to detect the attitude and behavior (inertial motion) of moving bodies (installed devices) such as automobiles, agricultural machinery, construction machinery, robots, and drones. Furthermore, the sensor unit 100b using the circuit board 15g can function as a so-called six-axis motion sensor, equipped with three-axis accelerometers 18x, 18y, and 18z and a three-axis angular velocity sensor 17, which serve as physical quantity sensors.

[0112] In addition, the sensor unit 100b according to this embodiment can be equipped with at least one of the acceleration sensors 18x, 18y, 18z and the angular velocity sensor 17 as physical quantity sensors, and detect at least one of acceleration and angular velocity.

[0113] The third embodiment described above can achieve the same effect as the first embodiment described above.

[0114] <Fourth Implementation Method>

[0115] Next, the sensor unit 100c according to the fourth embodiment of the present invention will be described.

[0116] Figure 12 This is a perspective view showing the structure of the substrate (circuit board) of the sensor unit according to the fourth embodiment of the present invention.

[0117] The circuit board 15h of the sensor unit 100c according to this embodiment is the same as the circuit board 15h of the sensor unit 100 of the first embodiment, except for the different structure of the circuit board 15h. Furthermore, in the following description, the circuit board 15h of the sensor unit 100c of the fourth embodiment will be described focusing on the differences from the first embodiment; identical items will be omitted. Figure 12 In this document, the same reference numerals are added to structures that are the same as those in the first embodiment described above.

[0118] like Figure 12 As shown, the sensor unit 100c of this embodiment includes a circuit board 15h on the first surface of the second region AL2, which is equipped with three angular velocity sensors 17x, 17y, and 17z capable of detecting angular velocities in one axial direction, as well as an acceleration sensor 18, serving as physical quantity sensors. Furthermore, a control IC 19 is mounted on the first surface of the first region AL1 of the circuit board 15h, and a plug-type (male) connector (not shown) is mounted on the second surface of the circuit board 15h, which is opposite to the first surface of the first region AL1.

[0119] Angular velocity sensors 17x, 17y, and 17z are gyroscope sensors that detect the angular velocity of one axis. As a preferred example, a vibrating gyroscope sensor uses a crystal as the oscillator and detects the angular velocity based on the Coriolis force applied to the vibrating object. However, any sensor capable of detecting angular velocity is acceptable; it is not limited to a vibrating gyroscope sensor. For example, sensors using ceramic or silicon as the oscillator can also be used.

[0120] Accelerometer 18 uses a capacitive accelerometer, for example, formed using MEMS technology on a silicon substrate, capable of detecting (sensing) acceleration in three directions (three axes) of the X, Y, and Z axes using a single device. However, any sensor capable of detecting acceleration is acceptable and is not limited to this type of sensor. For example, it could be a piezoresistive accelerometer or a thermal accelerometer, or it could be a structure like the angular velocity sensor described above, with one accelerometer for each axis.

[0121] With this structure, the sensor unit 100c equipped with the circuit board 15h can be used, for example, as an inertial measurement unit (IMU) to detect the attitude and behavior (inertial motion) of moving bodies (installed devices) such as automobiles, agricultural machinery, construction machinery, robots, and drones. Furthermore, the sensor unit 100c using the circuit board 15h functions as a so-called six-axis motion sensor, equipped with a three-axis accelerometer 18 as a physical quantity sensor and three-axis angular velocity sensors 17x, 17y, and 17z.

[0122] In addition, the sensor unit 100c according to this embodiment can be equipped with at least one of the acceleration sensor 18 and the angular velocity sensors 17x, 17y, and 17z, which are physical quantity sensors, to detect at least one of acceleration and angular velocity.

[0123] The fourth embodiment described above can achieve the same effect as the first embodiment described above.

[0124] [Structure Monitoring Device]

[0125] <Fifth Implementation Method>

[0126] Next, the Structural Health Monitoring (SHM) 500 according to the fifth embodiment of the present invention will be described.

[0127] Figure 13 This is a configuration diagram showing the structure monitoring device according to the fifth embodiment of the present invention.

[0128] The structure monitoring device 500 includes a sensor unit 510, which has the same structure as the sensor units 100 (100a, 100b, 100c) in the embodiments, and is mounted on the structure 590 to be monitored. The sensor unit 510 includes a transmitter 511 for transmitting detection signals. The transmitter 511 can be implemented as a communication module and an antenna separate from the sensor unit 510.

[0129] The sensor unit 510 is connected to, for example, a monitoring computer 570 via a wireless or wired communication network 580. The monitoring computer 570 has a receiving unit 520 connected to the sensor unit 510 via the communication network 580 and a calculation unit 530 that calculates the tilt angle of the structure 590 based on the signal output from the receiving unit 520.

[0130] In this embodiment, the arithmetic unit 530 is implemented using an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array) mounted on the monitoring computer 570. However, it may also be implemented in software, where the arithmetic unit 530 functions as a processor such as a CPU (Central Processing Unit), and the processor performs calculations on programs stored in the IC memory 531. The monitoring computer 570 can accept various operation inputs from the operator via the keyboard 540 and display the results of the calculations on the touch panel 550.

[0131] According to the structure monitoring device 500 of this embodiment, the tilt of the structure 590 is monitored using the sensor units 100, 100a, 100b, and 100c of this embodiment. Therefore, by utilizing the effect of the sensor units 100, 100a, 100b, and 100c, namely the high-precision acceleration detection, the tilt of the monitored object, i.e., the structure 590, can be detected with high precision, thereby improving the monitoring quality of the structure 590.

[0132] Hereinafter, the contents derived from the above embodiments will be described as various methods.

[0133] The sensor unit involved in this method is characterized by comprising: a physical quantity sensor; a processing unit electrically connected to the physical quantity sensor; a substrate on which the physical quantity sensor and the processing unit are mounted; and a container for housing the substrate, wherein the physical quantity sensor and the processing unit are arranged on the substrate in a non-overlapping manner when viewed from above.

[0134] According to this method, since the physical quantity sensor and the heat-generating processing unit are arranged in a non-overlapping manner, the heat generated by the processing unit is difficult to propagate to the physical quantity sensor. Therefore, the detection signal output from the physical quantity sensor is less likely to change due to the heat generated by the processing unit, thereby reducing the decrease in detection accuracy of the sensor unit.

[0135] In the sensor unit described above, it is preferable that the substrate includes a first region on which the processing unit is mounted and a second region on which the physical quantity sensor is mounted.

[0136] According to this method, since the processing unit is mounted in a first region of the substrate and the physical quantity sensor is mounted in a second region of the substrate, the processing unit and the physical quantity sensor can be separated, making it difficult for heat generated by the processing unit to propagate to the physical quantity sensor. Therefore, the reduction in detection accuracy of the sensor unit due to heat generated by the processing unit can be reduced.

[0137] In the sensor unit described above, it is preferable that the sensor unit includes a temperature sensing element mounted in the second region.

[0138] According to this method, since a temperature-sensing element is mounted in the second region of the substrate where the physical quantity sensor is mounted, the heat transmitted to the physical quantity sensor can be sensed by the temperature-sensing element. Therefore, the reduction in the detection accuracy of the sensor unit due to the influence of heat can be reduced.

[0139] In the sensor unit described above, it is preferable that the temperature sensing element is mounted on the surface of the second region of the substrate on the side where the physical quantity sensor is mounted.

[0140] According to this method, since the temperature sensing element is mounted on the surface of the substrate on which the physical quantity sensor is mounted, the temperature sensing element can be configured close to the physical quantity sensor, enabling more accurate sensing of heat propagating towards the physical quantity sensor. Therefore, the reduction in detection accuracy of the sensor unit due to the influence of heat can be further reduced.

[0141] In the sensor unit described above, it is preferred that the temperature sensing element is a thermistor or a diode.

[0142] According to this method, since the temperature sensing element is a thermistor or a diode, the structure of the temperature sensing element is simple.

[0143] In the sensor unit described above, it is preferable that the substrate has a connection region between the first region and the second region, and in a cross-sectional view taken from the arrangement direction of the first region and the second region, the cross-sectional area S3 of the connection region is smaller than the cross-sectional area S1 of the first region and the cross-sectional area S2 of the second region.

[0144] According to this method, since a connection region with a cross-sectional area S3 smaller than the cross-sectional area S1 of the first region and the cross-sectional area S2 of the second region is included between the first region and the second region of the substrate, the heat propagation speed of the processing unit mounted in the first region is slowed down in the small-area connection region, making it difficult for the heat generated by the processing unit to propagate to the physical quantity sensor mounted in the second region. Therefore, the reduction in detection accuracy of the sensor unit due to the heat generated by the processing unit can be further reduced.

[0145] In the sensor unit described above, it is preferable that the connection region is a contracted portion that tapers along the outer edge of the substrate in a first direction arranged along the first region and the second region when viewed from above.

[0146] According to this method, by using a so-called waist-shaped connection region that tapers towards the outer edge of the substrate, the heat propagation speed in the connection region is slowed down, making it difficult for heat generated by the processing unit to propagate to the physical quantity sensor mounted in the second region. Therefore, the reduction in sensor unit detection accuracy due to heat generated by the processing unit can be further reduced.

[0147] In the sensor unit described above, it is preferable that, in a top view, the contraction portion is disposed on both sides of the substrate in a second direction orthogonal to the first direction.

[0148] According to this method, by providing the contraction portions on both sides of the substrate in the second direction, the connection area can be further reduced. Therefore, in the connection area, the heat propagation speed can be further slowed down, and the heat generated by the processing unit is further difficult to propagate to the physical quantity sensor mounted in the second area.

[0149] In the sensor unit described above, it is preferred that the physical quantity sensor detects at least one of acceleration and angular velocity.

[0150] According to this method, the influence of heat generated by the processing unit can be reduced, and at least one of acceleration and angular velocity can be detected with high precision.

[0151] The structure monitoring device according to this method is characterized by comprising: a sensor unit as described in any of the above methods; a receiving unit for receiving detection signals from the sensor unit installed on the structure; and a calculation unit for calculating the tilt angle of the structure based on the signals output from the receiving unit.

[0152] According to this method, since the influence of heat generated by the processing unit is reduced, and the tilt angle of the structure is calculated based on the detection signal of the sensor unit with high detection accuracy, a structure monitoring device capable of detecting the tilt angle with high accuracy can be provided.

Claims

1. A sensor unit, characterized in that, Comprising: When three mutually orthogonal axes are defined as X-axis, Y-axis and Z-axis, the sensor unit comprises: a circuit substrate comprising a first region disposed on the -X side of the X-axis, a second region disposed on the +X side of the X-axis, and a connecting region connecting the first region and the second region; a processing part mounted on the first region; and a physical quantity sensor mounted on the second region and electrically connected to the processing part, wherein in a cross-sectional view viewed along the X-axis direction, when the cross-sectional area of the first region is defined as S1, the cross-sectional area of the second region is defined as S2, and the cross-sectional area of the connecting region is defined as S3, the condition S3 < S1 and S3 < S2 is satisfied.

2. The sensor unit according to claim 1, characterized in that, in a top view viewed along the Z-axis direction, a constricted part is provided in the connecting region.

3. The sensor unit according to claim 1 or 2, characterized in that, the physical quantity sensor is an acceleration sensor.

4. The sensor unit according to claim 3, characterized in that, the acceleration sensor comprises: an X-axis acceleration sensor configured to detect acceleration along the X-axis direction; a Y-axis acceleration sensor configured to detect acceleration along the Y-axis direction; and a Z-axis acceleration sensor configured to detect acceleration along the Z-axis direction.

5. The sensor unit according to claim 4, characterized in that, the X-axis acceleration sensor is arranged upright with its front and back faces facing the X-axis direction and its side face opposite to the second region, the Y-axis acceleration sensor is arranged upright with its front and back faces facing the Y-axis direction and its side face opposite to the second region, the Z-axis acceleration sensor is arranged with its front and back faces facing the Z-axis direction and either the front face or the back face opposite to the second region.

6. The sensor unit according to claim 5, characterized in that, an angular velocity sensor configured to detect angular velocities in the X-axis direction, the Y-axis direction and the Z-axis direction is mounted on the second region.

7. The sensor unit according to claim 5 or 6, characterized in that, the sensor unit comprises a temperature sensing element mounted on the second region.

8. The sensor unit according to claim 7, characterized in that, the temperature sensing element is mounted on a side of the second region where the physical quantity sensor is mounted.

9. The sensor unit according to claim 1 or 2, characterized in that, the physical quantity sensor is an angular velocity sensor.

10. The sensor unit according to claim 9, characterized in that, the angular velocity sensor comprises: an X-axis angular velocity sensor configured to detect angular velocity along the X-axis direction; a Y-axis angular velocity sensor configured to detect angular velocity along the Y-axis direction; and a Z-axis angular velocity sensor configured to detect angular velocity along the Z-axis direction.

11. The sensor unit according to claim 10, characterized in that, The X-axis angular velocity sensor is upright with its front and back facing the X-axis direction, so that its side faces the second region. The Y-axis angular velocity sensor is upright with its front and back facing the Y-axis direction, so that its side faces the second region. The Z-axis angular velocity sensor is configured such that either the front or the back face is opposite to the second region, with the front and back faces oriented towards the Z-axis direction.

12. The sensor unit according to claim 11, characterized in that, An accelerometer that detects acceleration in the X-axis direction, the Y-axis direction, and the Z-axis direction is mounted in the second region.

13. The sensor unit according to claim 11 or 12, characterized in that, The sensor unit includes a temperature-sensing element mounted in the second region.

14. The sensor unit according to claim 13, characterized in that, The temperature sensing element is mounted on the side of the second region on which the physical quantity sensor is mounted.

15. The sensor unit according to claim 7, characterized in that, The temperature sensing element is a thermistor or a diode.

16. The sensor unit according to claim 13, characterized in that, The temperature sensing element is a thermistor or a diode.

17. The sensor unit according to claim 15 or 16, characterized in that, The sensor unit includes a connector mounted in the first region.

18. A structure monitoring device, characterized in that, include: The sensor unit according to any one of claims 1 to 17; The receiving unit receives detection signals from the sensor unit installed on the structure; as well as The calculation unit calculates the tilt angle of the structure based on the signal output from the receiving unit.

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