Inertial Sensors and Inertial Measurement Units

Abstract

To provide an inertia sensor and an inertia measuring device which are not easily affected by the warpage of a substrate.SOLUTION: An inertia sensor 1 includes: a substrate 2; a fixing unit 22 arranged on one surface of the substrate 2; a mobile body 30 having an opening unit 43, the mobile body being capable of rocking around an axis J of rotation along a Y-direction as a first direction; and a support beam 35 for supporting the mobile body 30 as the axis J of rotation in an opening unit 43 of the mobile body 30; and a supporting unit 32 for supporting the support beam 35. The supporting unit 32 has a first unit 33 fixed to the fixing unit 22 and a second unit 34 not fixed to the fixing unit 22, and a length L2 of the second unit 34 in the Y-direction is longer than a length L1 of the first unit 33 in the Y-direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an inertial sensor and an inertial measurement unit. [Background technology]

[0002] In recent years, inertial sensors manufactured using MEMS (Micro Electro Mechanical Systems) technology have been developed. For example, Patent Document 1 describes an acceleration sensor having a base substrate, a sensor unit that is a movable body that seesaws around a rotation axis along a vertical direction relative to the base substrate, and a fixed electrode unit provided on the substrate, and capable of detecting vertical acceleration based on a change in electrostatic capacitance between a first part and a second part of the sensor unit having movable electrode units with different rotation moments around the rotation axis, and the fixed electrode units arranged at positions facing each other. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-40856 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the acceleration sensor described in Patent Document 1 has two support parts that serve as a rotation axis and are fixed to a base substrate, and are disposed on either side of the sensor part, so the distance between the two support parts is wide, making the sensor susceptible to warping of the base substrate due to external stress or thermal stress, which may degrade the detection accuracy of the acceleration sensor. [Means for solving the problem]

[0005] The inertial sensor comprises a substrate, a fixed portion arranged on one side of the substrate, a movable body having an opening and capable of swinging around a rotation axis along a first direction, a support beam supporting the movable body as the rotation axis in the opening of the movable body, and a support portion supporting the support beam, the support portion having a first portion fixed to the fixed portion and a second portion consisting only of a portion not fixed to the fixed portion, and the length of the second portion in the first direction is longer than the length of the first portion in the first direction.

[0006] The inertial measurement device includes the inertial sensor described above, and a control unit that performs control based on a detection signal output from the inertial sensor. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a plan view showing a schematic structure of an inertial sensor according to a first embodiment. [Diagram 2] Cross-sectional view taken along line AA in FIG. [Diagram 3] FIG. 2 is a plan view showing a schematic structure of a sensor element. [Figure 4] FIG. 11 is a plan view showing a schematic structure of an inertial sensor according to a second embodiment. [Diagram 5] FIG. 5 is a cross-sectional view taken along line BB in FIG. [Figure 6] FIG. 11 is a plan view showing a schematic structure of an inertial sensor according to a third embodiment. [Figure 7] FIG. 7 is a cross-sectional view taken along line CC in FIG. [Figure 8] FIG. 13 is a plan view showing a schematic structure of an inertial sensor according to a fourth embodiment. [Figure 9] 9 is a cross-sectional view taken along line DD in FIG. 8 . [Figure 10] FIG. 13 is a plan view showing a schematic structure of an inertial sensor according to a fifth embodiment. [Figure 11] 11 is a cross-sectional view taken along line EE in FIG. 10 . [Figure 12] FIG. 13 is an exploded perspective view showing a schematic configuration of an inertial measurement unit including an inertial sensor according to a sixth embodiment. [Figure 13]FIG. 13 is a perspective view of the substrate of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] 1. First embodiment First, the inertial sensor 1 according to the first embodiment will be described with reference to FIGS. 1, 2, and 3, taking an acceleration sensor that detects acceleration in the vertical direction as an example. In FIG. 1, for the sake of convenience in explaining the internal configuration of the inertial sensor 1, a lid 5 is removed.

[0009] For ease of explanation, each figure illustrates three mutually orthogonal axes, the X-axis, the Y-axis, and the Z-axis. The direction along the X-axis is called the "X-direction", the direction along the Y-axis is called the "Y-direction", and the direction along the Z-axis is called the "Z-direction". The tip side of the arrow in each axial direction is called the "plus side", the base side is called the "minus side", the plus side of the Z direction is called the "upper", and the minus side of the Z direction is called the "lower". The Z direction is along the vertical direction, and the XY plane is along the horizontal plane. In this embodiment, the first direction is the Y direction, the second direction is the X direction, and the third direction is the Z direction.

[0010] 1 and 2 can detect acceleration in the Z direction, which is the vertical direction of the sensor element 3. Such an inertial sensor 1 includes a substrate 2, a sensor element 3 disposed on the substrate 2, and a lid 5 bonded to the substrate 2 and covering the sensor element 3.

[0011] As shown in FIG. 1, the substrate 2 has an extension in the X-direction and the Y-direction, and a thickness in the Z-direction. As shown in FIG. 2, the substrate 2 has a recess 21 that opens to the upper surface side. The recess 21 is formed to include the sensor element 3 inside and is larger than the sensor element 3 in a plan view from the Z-direction. The recess 21 functions as a relief portion that suppresses contact between the sensor element 3 and the substrate 2. In addition, the substrate 2 has a fixed portion 22 and a protrusion 23 that protrude from the bottom surface toward the sensor element 3 side arranged on the bottom surface of the recess 21, which is one surface of the substrate 2, and a first detection electrode 24, a second detection electrode 25, and a dummy electrode 26 that overlap the sensor element 3 in a plan view from the Z-direction arranged on the bottom surface of the recess 21. The sensor element 3 is bonded to the upper surface of the fixed portion 22. In addition, the protrusion 23 is arranged at a position that overlaps with the movable body 30 in a plan view from the Z-direction. In this embodiment, the fixed electrodes include the first detection electrode 24, the second detection electrode 25, and the dummy electrode .

[0012] The protrusions 23 come into contact with the movable body 30 when excessive seesaw oscillation occurs in the movable body 30, thereby functioning as stoppers that restrict further seesaw oscillation of the movable body 30. By providing such protrusions 23, it is possible to suppress excessive closeness or contact over a wide area between the movable body 30 and the first detection electrode 24 and the second detection electrode 25, which have different potentials, and it is possible to effectively suppress the occurrence of "sticking," in which the movable body 30 remains attracted to the first detection electrode 24 or the second detection electrode 25 and does not return due to the electrostatic attraction generated between the movable body 30 and the first detection electrode 24 or the second detection electrode 25.

[0013] The substrate 2 is, for example, Na + For example, a glass substrate made of a borosilicate glass such as Pyrex (registered trademark) glass or Tempax (registered trademark) glass can be used. However, the substrate 2 is not particularly limited, and for example, a silicon substrate or a ceramic substrate can be used.

[0014] As shown in FIG. 2, the lid 5 is formed with a recess 51 that opens to the bottom side. The lid 5 is joined to the upper surface of the substrate 2 with the sensor element 3 housed in the recess 51. The lid 5 and the substrate 2 form a storage space S for housing the sensor element 3 inside. The storage space S is an airtight space, and is filled with an inert gas such as nitrogen, helium, or argon, and is preferably used at a temperature of about -40°C to 125°C and at approximately atmospheric pressure. However, the atmosphere of the storage space S is not particularly limited, and may be, for example, in a reduced pressure state or a pressurized state.

[0015] For example, a silicon substrate can be used as the lid 5. However, the present invention is not limited to this, and for example, a glass substrate or a ceramic substrate can be used. The method for bonding the substrate 2 and the lid 5 is not particularly limited, and may be appropriately selected depending on the materials of the substrate 2 and the lid 5. For example, anodic bonding, activation bonding in which bonding surfaces activated by plasma irradiation are bonded together, bonding using a bonding material such as glass frit, diffusion bonding in which metal films formed on the upper surface of the substrate 2 and the lower surface of the lid 5 are bonded together, and the like can be used.

[0016] The sensor element 3 is formed by etching a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), arsenic (As), etc., in particular by patterning the substrate by the Bosch process, which is a deep trench etching technique. As shown in Figs. 1 and 3, the sensor element 3 has an opening 43 and includes a movable body 30 that can swing around a rotation axis J along the Y direction, a support beam 35 that supports the movable body 30 as the rotation axis J, and a support portion 32 that supports the support beam 35.

[0017] The movable body 30 has a rectangular shape with the X direction as the longitudinal direction in a plan view from the Z direction. In addition, the movable body 30 has a first mass section 36 and a second mass section 37 arranged on either side of a support beam 35 as a rotation axis J in a plan view from the Z direction, and a third mass section 38 connected by a third connecting section 41 at both ends in the Y direction of an end of the second mass section 37 opposite the first mass section 36 in the X direction. The first mass section 36 is located on the negative side of the X direction with respect to the rotation axis J, and the second mass section 37 and the third mass section 38 are located on the positive side of the X direction with respect to the rotation axis J. In addition, the first mass section 36 and the second mass section 37 are connected by a first connecting section 39 and a second connecting section 40 at both ends in the Y direction of the ends facing each other.

[0018] The total length in the X direction of the second mass section 37 and the third mass section 38 is longer than the length in the X direction of the first mass section 36, and the rotation moment around the rotation axis J when an acceleration Az in the Z direction is applied is larger than that of the first mass section 36. Due to this difference in rotation moment, the movable body 30 seesaws around the rotation axis J when the acceleration Az is applied. Note that the seesaw swing means that when the first mass section 36 is displaced to the positive side in the Z direction, the second mass section 37 is displaced to the negative side in the Z direction, and conversely, when the first mass section 36 is displaced to the negative side in the Z direction, the second mass section 37 is displaced to the positive side in the Z direction.

[0019] In addition, the movable body 30 has a plurality of through holes that are uniformly formed over the entire area, for example, arranged regularly. This makes it possible to reduce damping due to viscosity. However, the through holes may be omitted, may not be arranged uniformly, and may not be of uniform size.

[0020] Inside the opening 43 formed by the first mass portion 36, the second mass portion 37, the first connecting portion 39, and the second connecting portion 40, the support portion 32 fixed to the fixed portion 22 by, for example, anodically bonding, and the support beam 35 acting as the rotation axis J and supporting the movable body 30 are arranged. Therefore, the fixed portion 22 provided on the substrate 2 is arranged inside the opening 43, that is, inside the sensor element 3, so that it is less susceptible to the effect of warping of the substrate 2, and deterioration of the detection accuracy of the inertial sensor 1 can be reduced. In addition, the sensor element 3 can be made smaller. In this embodiment, two fixed portions 22 and two support portions 32 are arranged with the support beam 35 sandwiched therebetween.

[0021] The support portion 32 has a first portion 33 having an area fixed to the fixed portion 22 at a position overlapping the fixed portion 22 in a plan view from the Z direction, a second portion 34 located between the first portion 33 and the first connecting portion 39 and the second connecting portion 40, which consists only of a portion not fixed to the fixed portion 22 and extends in the positive direction of the Y direction, and a second portion 34 consisting only of a portion not fixed to the fixed portion 22 and extends in the negative direction of the Y direction. As shown in FIG. 3, the length L2 of the second portion 34 in the Y direction is longer than the length L1 of the first portion 33 in the Y direction. The support portion 32 is between the first connecting portion 39 and the second connecting portion 40, and is aligned with the first connecting portion 39 and the second connecting portion 40 via a groove that constitutes a part of the opening 43. In this embodiment, the length of the first portion 33 in the X direction is longer than the length of the second portion 34 in the X direction.

[0022] In the sensor element 3 of this embodiment, the length L2 of the second portion 34 is longer than the length L1 of the first portion 33, and the second portion 34 is disposed between the first portion 33 and the first connecting portion 39 and the second connecting portion 40. Therefore, when an impact is applied in the in-plane direction, the end of the support beam 35 on the first connecting portion 39 and the second connecting portion 40 side, which has a large amount of displacement, comes into contact with the second portion 34 having an elastic function, making it easier to absorb the impact and improving the in-plane impact resistance. In addition, since the support portion 32 is long in the Y direction between the first connecting portion 39 and the second connecting portion 40, the contact area with the support beam 35 can be increased when an impact is applied in the in-plane direction, and the impact on the support beam 35 can be further suppressed. Furthermore, in the sensor element 3, the length L3 in the X direction from the support portion 32 to the support beam 35 is longer than the length L4 in the X direction from the support portion 32 to the first mass portion 36 and the second mass portion 37. Therefore, when an impact is applied in the in-plane direction, the first mass portion 36 and the second mass portion 37 come into contact with the support portion 32 first because the intervals between the support portion 32 and the first mass portion 36 and the second mass portion 37 are narrow, so that damage to the support beam 35 can be prevented.

[0023] The support beam 35 is connected to the connecting beam 31 that connects the two support parts 32. The connecting beam 31 on the first connecting part 39 side is provided with the support beam 35 that extends in the positive direction of the Y direction and connects to the first connecting part 39. The connecting beam 31 on the second connecting part 40 side is provided with the support beam 35 that extends in the negative direction of the Y direction and connects to the second connecting part 40. Therefore, the two support beams 35 serve as the rotation axis J, and the movable body 30 can be made to swing around the rotation axis J. In addition, since the support beam 35 is connected via the connecting beam 31 to the first part 33, which has no elastic function, of the support part 32 fixed to the fixed part 22, when an impact such as a drop impact is applied, the effect of the impact can be greatly reduced and damage to the support beam 35 can be prevented.

[0024] In the movable body 30, the positions of the first mass portion 36 and the second mass portion 37 facing the second portion 34 of the support portion 32 are closer to the support beam 35 than the positions facing the first portion 33. That is, as shown in Fig. 3, the length Lm in the X direction from the end of the movable body 30 facing the second portion 34 to the rotation axis J is shorter than the length Lc in the X direction from the end of the first portion 33 on the opposite side to the rotation axis J to the rotation axis J. Therefore, the facing area between the first mass portion 36 and the second mass portion 37 and the first detection electrode 24 and the second detection electrode 25 can be increased, and the detection sensitivity can be improved.

[0025] The first connecting portion 39 and the second connecting portion 40 each have three through holes 42 arranged along the X direction, and as shown in Fig. 3, the length La in the X direction from the rotation axis J to the end portions of the first connecting portion 39 and the second connecting portion 40 on the movable body 30 side is longer than the length Lm in the X direction from the rotation axis J to the end portions facing the second portion 34 of the movable body 30. By increasing the length La of the first connecting portion 39 and the second connecting portion 40, the movable body 30 becomes more flexible while maintaining improved in-plane impact resistance, and out-of-plane impact resistance can be improved.

[0026] Next, the first detection electrode 24, the second detection electrode 25, and the dummy electrode 26 arranged on the bottom surface of the recess 21 will be described. 1 and 2, in plan view from the Z direction, the first detection electrode 24 is arranged to overlap the first mass portion 36, and the second detection electrode 25 is arranged to overlap the second mass portion 37. The first detection electrode 24 and the second detection electrode 25 are provided approximately symmetrically with respect to the rotation axis J in plan view from the Z direction so that the electrostatic capacitances, which will be described later, are equal in a natural state in which no acceleration Az is applied.

[0027] Moreover, the dummy electrode 26 is located on the positive side in the X direction relative to the second detection electrode 25, and is provided so as to overlap with the third mass portion 38. In this manner, by covering the bottom surface of the recess 21 with the dummy electrode 26, it is possible to suppress charging of the bottom surface of the recess 21 due to the movement of alkali metal ions in the substrate 2. Therefore, it is possible to effectively suppress the generation of unintended electrostatic attraction between the bottom surface of the recess 21 and the second mass portion 37, which may lead to malfunction of the movable body 30. This results in the inertial sensor 1 being able to detect the acceleration Az with higher accuracy.

[0028] In addition, the dummy electrode 26 is electrically connected to an electrode on the upper surface of the protrusion 23 provided at a position overlapping the second mass portion 37 in a plan view from the Z direction. In addition, the electrode on the upper surface of the protrusion 23 provided at a position overlapping the first mass portion 36 in a plan view from the Z direction is electrically connected to the wiring 27 provided on the first mass portion 36 side. In addition, the electrode on the upper surface of the fixing portion 22 for applying a drive voltage to the sensor element 3 is electrically connected to the wiring 28 provided at a position overlapping the support beam 35 in a plan view from the Z direction. Therefore, by making the dummy electrode 26, the wiring 27, and the wiring 28 the same potential, the sensor element 3 and the electrode on the upper surface of the protrusion 23 come into contact when excessive seesaw oscillation occurs, and the occurrence of sticking can be reduced. In this embodiment, the electrode on the upper surface of the protrusion 23 is electrically connected to the dummy electrode 26, etc., but it may be configured to be electrically connected to the first detection electrode 24 and the second detection electrode 25. In that case, in order to prevent sticking from occurring, it is advisable to provide an insulating layer or the like on the surface of the electrode on the upper surface of the projection 23 .

[0029] When the inertial sensor 1 is driven, a drive voltage is applied to the sensor element 3 via the wiring 28, and the first detection electrode 24 and the QV amplifier, and the second detection electrode 25 and another QV amplifier are connected by wiring (not shown). As a result, a capacitance is formed between the first mass portion 36 and the first detection electrode 24, and a capacitance is formed between the second mass portion 37 and the second detection electrode 25. In a natural state where no acceleration Az is applied, the two capacitances are approximately equal to each other.

[0030] When acceleration Az is applied to the inertial sensor 1, the movable body 30 oscillates in a seesaw motion around the rotation axis J. This seesaw motion of the movable body 30 causes the gap between the first mass portion 36 and the first detection electrode 24 and the gap between the second mass portion 37 and the second detection electrode 25 to change in opposite phases, and accordingly the two capacitances change in opposite phases to each other. Therefore, the inertial sensor 1 can detect the acceleration Az based on the changes in the two capacitances.

[0031] In the inertial sensor 1 of this embodiment, the fixing portion 22 provided on the substrate 2 is positioned within the opening 43, i.e., inside the sensor element 3, so that the sensor is less susceptible to the effects of warping of the substrate 2, and deterioration of the detection accuracy of the inertial sensor 1 can be reduced.

[0032] Further, the length L2 of the second portion 34 is longer than the length L1 of the first portion 33, and the second portion 34 is disposed between the first portion 33 and the first and second connecting portions 39 and 40. Therefore, when an impact is applied in the in-plane direction, the end of the support beam 35 on the side of the first and second connecting portions 39 and 40, which has a large amount of displacement, comes into contact with the second portion 34 having an elastic function, making it easier to absorb the impact and improving the in-plane impact resistance. The total length in the Y direction of the multiple second portions 34 aligned in the Y direction is longer than the total length in the Y direction of the first portions 33 aligned in the Y direction with the second portions 34.

[0033] 2. Second embodiment Next, an inertial sensor 1a according to a second embodiment will be described with reference to Fig. 4 and Fig. 5. Note that Fig. 4 illustrates a state in which a lid 5 is removed for the convenience of describing the internal configuration of the inertial sensor 1a.

[0034] The inertial sensor 1a of this embodiment is similar to the inertial sensor 1 of the first embodiment, except that the structure of the substrate 2a is different from that of the inertial sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and descriptions of similar points will be omitted.

[0035] As shown in Fig. 4 and Fig. 5, the substrate 2a of the inertial sensor 1a has a recess 21 that opens to the upper surface side, a recess 21a that opens to the upper surface side on the bottom surface of the recess 21, a recess 21b that opens to the upper surface side on the bottom surface of the recess 21a, and a recess 21c that opens to the upper surface side on the bottom surface of the recess 21b. On the bottom surface of the recess 21, a fixing portion 22 that protrudes to the upper surface side, a first detection electrode 24, a second detection electrode 25, and a wiring 28 are arranged. On the bottom surface of the recess 21a, a protrusion 23 that protrudes to the upper surface side, a wiring 27 that electrically connects with the electrode provided on the upper surface of the protrusion 23, and a dummy electrode 26 that electrically connects with the electrode provided on the upper surface of the protrusion 23 are arranged. On the bottom surface of the recess 21b, the first detection electrode 24, the second detection electrode 25, the dummy electrode 26, and the wiring 27 are arranged. A dummy electrode 26 is disposed on the bottom surface of the recess 21c.

[0036] The movable body 30 is arranged in the opposing region to the first detection electrode 24, the second detection electrode 25, and the dummy electrode 26, which are fixed electrodes, separated by a first gap 61, a second gap 62, a third gap 63, and a fourth gap 64, each of which has a different distance between the movable body 30 and the fixed electrodes.

[0037] The first gap 61 is disposed closer to the rotation axis J than the second gap 62, and the first gap 61, the second gap 62, the third gap 63, and the fourth gap 64 are disposed in this order from the rotation axis J. Also, the distance H1 between the movable body 30 and the fixed electrode in the first gap 61 is narrower than the distance H2 in the second gap 62. That is, the distance between the movable body 30 and the fixed electrode becomes wider in the order of the first gap 61, the second gap 62, the third gap 63, and the fourth gap 64. Therefore, when the movable body 30 seesaws due to the application of the acceleration Az in the Z direction, the tip of the third mass portion 38, which has the largest displacement, is less likely to come into contact with the bottom surface of the recess 21c, which has the largest distance from the movable body 30, and the detection range of the acceleration Az can be increased. Furthermore, since the distance between the first mass portion 36 and the second mass portion 37 can be narrowed, the capacitance value can be increased, and the detection sensitivity can be improved.

[0038] In this embodiment, the substrate 2a has three steps, but the present invention is not limited to this and may have two or more steps. In addition, the movable body 30 is not linearly symmetrical with respect to the rotation axis J in this embodiment, but the present invention is not limited to this and may have a linearly symmetrical structure as long as the first mass portion 36 and the second mass portion 37 have different masses and a rotational moment is generated.

[0039] 3, in a plan view from the Z direction perpendicular to the X and Y directions, a part of the movable body 30 within a range F between an end portion facing the second portion 34 of the movable body 30 and an end portion facing the first portion 33 of the movable body 30 overlaps with the fixed electrode. Therefore, compared with a case where the overlap with the fixed electrode is limited to the end portion facing the first portion 33 of the movable body 30, the capacitance value can be made larger, and the detection sensitivity can be improved.

[0040] According to this embodiment, in addition to the effects of the first embodiment, the amount of displacement of the movable body 30 can be increased, so that the detection range of the acceleration Az can be increased. Also, the capacitance value between the detection electrode and the fixed electrode can be increased, so that the detection sensitivity can be improved. In this embodiment, the substrate 2a is provided with a step, but this is not limiting. The lid 5 may be provided with a step in which the distance from the movable body 30 increases as the lid 5 moves away from the rotation axis J.

[0041] 3. Third embodiment Next, an inertial sensor 1b according to a third embodiment will be described with reference to Fig. 6 and Fig. 7. Note that Fig. 6 illustrates a state in which the lid 5 is removed for the convenience of describing the internal configuration of the inertial sensor 1b.

[0042] The inertial sensor 1b of this embodiment is similar to the inertial sensor 1 of the first embodiment, except that the structures of the substrate 2b and the sensor element 3b are different from those of the inertial sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and descriptions of similar matters will be omitted.

[0043] 6 and 7, the substrate 2b of the inertial sensor 1b has four fixing portions 22b arranged on the bottom surface of the recess 21, protruding from the bottom surface toward the sensor element 3b. The four fixing portions 22b are arranged line-symmetrically with respect to the rotation axis J as the center line in a plan view from the Z direction, and are also arranged line-symmetrically with respect to the center line in a direction perpendicular to the rotation axis J. In addition, the first detection electrode 24, the second detection electrode 25, and the dummy electrode 26 are respectively arranged on the bottom surface of the recess 21 facing the first mass portion 36b, the second mass portion 37b, and the third mass portion 38 of the sensor element 3b.

[0044] The sensor element 3b has an opening 43b, a movable body 30b that can swing around a rotation axis J along the Y direction, a support beam 35 that supports the movable body 30b as the rotation axis J in the opening 43b of the movable body 30b, and a support portion 32b that supports the support beam 35.

[0045] The opening 43b of the movable body 30b is composed of a first mass portion 36b and a second mass portion 37b arranged on either side of the rotation axis J, and a first connecting portion 39 and a second connecting portion 40 connecting the first mass portion 36b and the second mass portion 37b.

[0046] Each of the two support parts 32b includes a plurality of first parts 33b arranged in the Y direction. That is, the two support parts 32b are arranged on either side of the rotation axis J, and each of the support parts 32b includes four first parts 33b including an area fixed to the fixed part 22b at a position overlapping the fixed part 22b in a plan view from the Z direction, and a second part 34b is arranged between two first parts 33b arranged symmetrically with respect to a center line in a direction perpendicular to the rotation axis J among the four first parts 33b, connects the two first parts 33b, and includes only a part not fixed to the fixed part 22b and extends in the Y direction. The length L2 of the second part 34b in the Y direction is longer than the length L1 of the first part 33b in the Y direction. It is preferable that the length of the second part 34b in the Y direction is longer than the total length of the first parts 33b arranged in the Y direction together with the second parts 34b, but is not limited thereto.

[0047] The two support beams 35 are each connected to the connecting beam 31 that connects the two support portions 32b at the second portion 34b, and to the first connecting portion 39 and the second connecting portion 40. Therefore, the support beam 35 serves as a rotation axis J, and the movable body 30b can be made to swing around the rotation axis J.

[0048] According to this embodiment, in addition to the effects of the first embodiment, when an in-plane impact is applied, the four first portions 33b come into contact with the first mass portion 36b and the second mass portion 37b, thereby suppressing the displacement of the movable body 30b and improving the in-plane impact resistance.

[0049] 4. Fourth embodiment Next, an inertial sensor 1c according to a fourth embodiment will be described with reference to Fig. 8 and Fig. 9. Note that Fig. 8 illustrates a state in which the lid 5 is removed for the convenience of describing the internal configuration of the inertial sensor 1c.

[0050] The inertial sensor 1c of this embodiment is similar to the inertial sensor 1 of the first embodiment, except that the structures of the substrate 2c and the sensor element 3c are different from those of the inertial sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and descriptions of similar matters will be omitted.

[0051] The sensor element 3c of the inertial sensor 1c has two support parts 32c each having a plurality of first parts 33c arranged in the Y direction. As shown in Figs. 8 and 9, the substrate 2c of the inertial sensor 1c has six fixing parts 22c protruding from the bottom surface toward the sensor element 3c arranged on the bottom surface of the recess 21. The six fixing parts 22c are arranged line-symmetrically with respect to the rotation axis J as the center line in a plan view from the Z direction, and are also arranged line-symmetrically with respect to the center line in a direction perpendicular to the rotation axis J. In addition, the first detection electrode 24, the second detection electrode 25, and the dummy electrode 26 are respectively arranged on the bottom surface of the recess 21 facing the first mass part 36c, the second mass part 37c, and the third mass part 38 of the sensor element 3c.

[0052] The sensor element 3c has an opening 43c, a movable body 30c that can swing around a rotation axis J along the Y direction, a support beam 35 that supports the movable body 30c as the rotation axis J in the opening 43c of the movable body 30c, and a support portion 32c that supports the support beam 35.

[0053] The opening 43c of the movable body 30c is composed of a first mass portion 36c and a second mass portion 37c arranged on either side of the rotation axis J, and a first connecting portion 39 and a second connecting portion 40 connecting the first mass portion 36c and the second mass portion 37c.

[0054] The two support parts 32c are arranged on either side of the rotation axis J, and each of them has a first part 33c fixed to the fixed part 22c at a position overlapping the fixed part 22c in a plan view from the Z direction, and a second part 34c that is connected to the first part 33c located on the positive side of the Y direction and the first part 33c located on the negative side of the Y direction, and is made up of only a part not fixed to the fixed part 22c and extends in the Y direction, among the three first parts 33c arranged side by side in the Y direction. The length L2 of the second part 34c in the Y direction is longer than the length L1 of the first part 33c in the Y direction. The relationship L2>L1 may be satisfied between one or more first parts 33c and one or more second parts 34c in the multiple first parts 33c and multiple 34c arranged side by side in the Y direction. It is preferable that the total length in the Y direction of the second portion 34c is longer than the total length in the Y direction of the first portion 33c aligned in the Y direction with the second portion 34c, but this is not limited thereto.

[0055] The two support beams 35 are connected to the connecting beam 31, which is connected to the two first portions 33c located in the center, and to the first connecting portion 39 and the second connecting portion 40. Therefore, the support beam 35 serves as a rotation axis J, and the movable body 30c can be made to swing around the rotation axis J.

[0056] According to this embodiment, in addition to the effects of the first embodiment, when an in-plane impact is applied, the four first portions 33c arranged at the four corners of the opening 43c come into contact with the first mass portion 36c and the second mass portion 37c, thereby suppressing the displacement of the movable body 30c and improving the in-plane impact resistance.

[0057] 5. Fifth embodiment Next, an inertial sensor 1d according to a fifth embodiment will be described with reference to Fig. 10 and Fig. 11. Note that Fig. 10 illustrates a state in which the lid 5 is removed for the convenience of describing the internal configuration of the inertial sensor 1d.

[0058] The inertial sensor 1d of this embodiment is similar to the inertial sensor 1 of the first embodiment, except that the structures of the substrate 2d and the sensor element 3d are different from those of the inertial sensor 1 of the first embodiment. Note that the following description will focus on the differences from the first embodiment described above, and descriptions of similar points will be omitted.

[0059] 10 and 11, the substrate 2d of the inertial sensor 1d has a fixed portion 22d disposed on the bottom surface of the recess 21, protruding from the bottom surface toward the sensor element 3d. The fixed portion 22d is disposed at the center of the recess 21 in the Y direction in a plan view from the Z direction. The first detection electrode 24, the second detection electrode 25, and the dummy electrode 26 are disposed on the bottom surface of the recess 21 facing the first mass portion 36d, the second mass portion 37d, and the third mass portion 38 of the sensor element 3d, respectively. In this embodiment, the support portion 32d of the sensor element 3d is fixed by two fixed portions 22d, but the number of fixed portions 22d may be one.

[0060] The sensor element 3d has an opening 43d, a movable body 30d that can swing around a rotation axis J along the Y direction, a support beam 35 that supports the movable body 30d as the rotation axis J in the opening 43d of the movable body 30d, and a support portion 32d that supports the support beam 35.

[0061] The opening 43d of the movable body 30d is composed of a first mass portion 36d and a second mass portion 37d arranged on either side of the rotation axis J, and a first connecting portion 39 and a second connecting portion 40 connecting the first mass portion 36d and the second mass portion 37d.

[0062] The support portion 32d has a first portion 33d fixed to the fixed portion 22d at a position overlapping the fixed portion 22d in a plan view from the Z direction, and two second portions 34d consisting of only a portion not fixed to the fixed portion 22d, extending in the positive direction of the Y direction from both ends of the end on the positive side of the Y direction of the first portion 33d, and two second portions 34d extending in the negative direction of the Y direction from both ends of the end on the negative side of the Y direction of the first portion 33d. The first portion 33d is located on the rotation axis J. Therefore, the length of the sensor element 3d in the X direction can be shortened. The length L2 in the Y direction of the second portion 34d is the distance from the first portion 33d to the tip of the second portion 34d, and is longer than the length L1 in the Y direction of the first portion 33d.

[0063] The two support beams 35 are connected to the connecting beam 31 that connects the two second portions 34d of the support portion 32d, and to the first connecting portion 39 and the second connecting portion 40. Therefore, the support beam 35 serves as the rotation axis J, and the movable body 30d can be made to swing around the rotation axis J.

[0064] According to this embodiment, in addition to the effects of the first embodiment, since the first portion 33d of the support portion 32d is positioned on the rotation axis J, the length of the sensor element 3d in the X direction can be shortened, and the inertial sensor 1d can be made smaller.

[0065] 6. Sixth embodiment Next, an inertial measurement device 2000 including the inertial sensors 1 to 1d according to the sixth embodiment will be described with reference to Fig. 12 and Fig. 13. In the following description, a configuration to which the inertial sensor 1 is applied will be described as an example.

[0066] 12 is a device that detects inertial momentum such as the attitude and behavior of a moving body such as an automobile or a robot. The inertial measurement unit 2000 functions as a so-called six-axis motion sensor that includes an acceleration sensor that detects accelerations Ax, Ay, and Az in directions along three axes, and an angular velocity sensor that detects angular velocities ωx, ωy, and ωz about the three axes.

[0067] The inertial measurement unit 2000 is a rectangular parallelepiped with a substantially square planar shape. Moreover, screw holes 2110 are formed as fixing parts near two vertices located in the diagonal direction of the square. The inertial measurement unit 2000 can be fixed to a mounting surface of a mounting body such as an automobile by passing two screws through the two screw holes 2110. Note that by selecting parts and modifying the design, it is possible to reduce the size to a size that can be mounted on a smartphone or digital camera, for example.

[0068] The inertial measurement device 2000 has an outer case 2100, a joint member 2200, and a sensor module 2300, and is configured such that the sensor module 2300 is inserted inside the outer case 2100 with the joint member 2200 interposed therebetween. The sensor module 2300 also has an inner case 2310 and a substrate 2320.

[0069] The external shape of outer case 2100 is a rectangular parallelepiped with a substantially square planar shape, similar to the overall shape of inertial measurement unit 2000, and screw holes 2110 are formed near each of two vertices located diagonally in the square. Outer case 2100 is also box-shaped, and contains sensor module 2300 therein.

[0070] The inner case 2310 is a member that supports the substrate 2320, and is shaped to fit inside the outer case 2100. The inner case 2310 is formed with a recess 2311 for preventing contact with the substrate 2320 and an opening 2312 for exposing a connector 2330, which will be described later. The inner case 2310 is joined to the outer case 2100 via a joining member 2200. The substrate 2320 is joined to the bottom surface of the inner case 2310 via an adhesive.

[0071] 13, a connector 2330, an angular velocity sensor 2340z that detects an angular velocity around the Z axis, an acceleration sensor unit 2350 that detects acceleration in the directions of the X axis, the Y axis, and the Z axis, and the like are mounted on the upper surface of the substrate 2320. In addition, an angular velocity sensor 2340x that detects an angular velocity around the X axis and an angular velocity sensor 2340y that detects an angular velocity around the Y axis are mounted on the side surface of the substrate 2320.

[0072] The acceleration sensor unit 2350 includes at least the inertial sensor 1 for measuring the acceleration in the Z direction described above, and can detect the acceleration in one axis direction, or in two or three axes directions as necessary. Note that the angular velocity sensors 2340x, 2340y, and 2340z are not particularly limited, and for example, a vibration gyro sensor that utilizes the Coriolis force can be used.

[0073] In addition, a control IC 2360 is mounted on the bottom surface of the substrate 2320. The control IC 2360, which serves as a control unit that performs control based on the detection signal output from the inertial sensor 1, is an MCU (Micro Controller Unit) that incorporates a storage unit including a non-volatile memory, an A / D converter, and the like, and controls each unit of the inertial measurement device 2000. The storage unit stores a program that defines the order and content for detecting acceleration and angular velocity, a program that digitizes the detection data and incorporates it into packet data, associated data, and the like. Note that a plurality of other electronic components are also mounted on the substrate 2320.

[0074] Such an inertial measurement unit 2000 uses an acceleration sensor unit 2350 including an inertial sensor 1, and therefore an inertial measurement unit 2000 having excellent shock resistance and high reliability can be obtained. [Explanation of symbols]

[0075] 1, 1a, 1b, 1c, 1d... inertial sensor, 2... substrate, 3... sensor element, 5... cover, 21... recess, 22... fixed portion, 23... protrusion, 24... first detection electrode, 25... second detection electrode, 26... dummy electrode, 27... wiring, 28... wiring, 30... movable body, 31... connecting beam, 32... support portion, 33... first part, 34... second part, 35... support beam, 36... first mass portion, 37... second mass portion, 38... third mass portion, 39... first connecting portion, 40... second connecting portion, 41... third connecting portion, 42... through hole, 43... opening, 51... recess, 2000... inertial measurement unit, F... range, H1, H2... interval, J... rotation axis, L1, L2, L3, L4, La, Lc, Lm... length, S... storage space.

Claims

1. A substrate having an extension in a first direction and a second direction intersecting the first direction; A fixing portion disposed on one surface of the substrate; a movable body having an opening and capable of swinging about a rotation axis along the first direction; A support that supports the movable body as the rotation axis inside the opening of the movable body. A beam and a support portion supporting the support beam, The support portion has a plurality of first portions and a plurality of second portions, The second portions of the support are arranged to be in contact with the first portions of the support. The first portion is connected to the end of the first portion on the side of the rotating shaft, and the first direction Extending to the plurality of first portions have portions fixed to the fixed portion, the plurality of second portions do not have any portion fixed to the fixed portion, The length of the second portion in the first direction is longer than the length of the first portion in the first direction, The support portion has the first portion and the second portion arranged side by side along the first direction. There are Inertial sensor.

2. The support portion is configured such that a total length of the second portion in the first direction is equal to or smaller than a total length of the first portion in the first direction. longer than the total length of the The inertial sensor of claim 1 .

3. A first mass portion and a second mass portion disposed on either side of the support beam; a first connecting portion that connects the first mass portion and the second mass portion and is connected to the support beam; and Two connecting parts; having The second portion is disposed between the first portion and the first connecting portion and between the first portion and the second connecting portion. Each is located 3. An inertial sensor according to claim 1 or 2.

4. The length in the second direction from the end of the movable body facing the second portion to the rotation shaft is , the length in the second direction from the end of the first portion opposite to the rotation shaft side to the rotation shaft Shorter than The inertial sensor according to claim 3 .

5. The first portion is located on the rotation axis. The inertial sensor according to any one of claims 1 to 4.

6. The distance from the rotation shaft to the end of the first connecting portion and the end of the second connecting portion on the movable body side. The length in two directions is the distance from the rotation axis to the end of the movable body facing the second portion. longer than the length in the second direction, The inertial sensor according to claim 4.

7. the substrate has a fixed electrode disposed on the one surface; The movable body and the fixed electrode are spaced apart from each other in a region facing the fixed electrode. The fixed electrode is disposed across a first gap and a second gap having different distances from the fixed electrode. An inertial sensor according to any one of claims 1 to 6.

8. The first gap is disposed closer to the rotation axis than the second gap, The spacing of the first gap is narrower than the spacing of the second gap. The inertial sensor according to claim 7.

9. When viewed from a third direction perpendicular to the first direction and the second direction, a front end portion of the movable body that faces the second portion and an end portion of the movable body that faces the first portion; A portion of the movable body overlaps with the fixed electrode. The inertial sensor according to claim 7 or 8.

10. An inertial sensor according to any one of claims 1 to 9; A control unit that performs control based on a detection signal output from the inertial sensor; Equipped with Inertial measurement unit.

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