JP2021139877A - Physical quantity sensor, electronic apparatus, and movable body - Google Patents

Abstract

To provide a physical quantity sensor that is hardly broken, an electronic apparatus, and a movable body.SOLUTION: When three directions orthogonal to one another are a first direction, a second direction, and a third direction, a physical quantity sensor has a substrate, and a movable body that is opposite to the substrate with a gap therebetween in the third direction and displaced in the third direction with respect to the substrate. The movable body has a first area that penetrates in the third direction and includes a plurality of through holes whose opening shape when viewed from the third direction is square, and a second area that does not include through holes. When the length of one side of the through hole is S0, and the interval between the adjacent through holes is S1, at least one of the length in the first direction and the length in the second direction of the second area is S0+2×S1 or more.SELECTED DRAWING: Figure 1

Description

The present invention relates to physical quantity sensors, electronic devices and mobile objects.

For example, the accelerometer described in Patent Document 1 is placed between a substrate, a fixed portion fixed to the substrate, a movable body connected to the fixed portion via a beam, and a movable body arranged on the substrate. It has a fixed detection electrode for detecting the generated capacitance. When acceleration is applied from the direction in which the movable body and the fixed detection electrode overlap, the movable body swings on the seesaw with the beam as the rotation axis, and the distance between the movable body and the fixed detection electrode changes accordingly. The electric capacity changes. Therefore, the acceleration sensor described in Patent Document 1 can detect acceleration based on a change in capacitance.

Further, the acceleration sensor described in Patent Document 1 has a protrusion protruding from the substrate, and when an excessive acceleration is applied, the movable body comes into contact with the protrusion. As a result, collision and sticking of the movable body to the substrate are suppressed. Further, the movable body is formed with a through hole for reducing damping, but the through hole is not formed at a portion in contact with the protrusion. As a result, the mechanical strength of the portion is ensured, and the movable body is suppressed from being damaged by the impact in contact with the protrusion.

Japanese Unexamined Patent Publication No. 2019-045167

However, such a configuration is insufficient to sufficiently increase the mechanical strength of the movable body.

When the physical quantity sensor of the present invention has three directions orthogonal to each other as the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body penetrates in the third direction, and has a first region having a plurality of through holes having a square opening shape when viewed from the third direction, and a second region having no through holes. Have and
The length of one side of the through hole is S0,
When the distance between adjacent through holes is S1,
At least one of the length of the second region in the first direction and the length of the second region is S0 + 2 × S1 or more.

When the physical quantity sensor of the present invention has three directions orthogonal to each other as the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body has a first region having a plurality of through holes penetrating in the third direction and having a circular opening shape when viewed from the third direction, and a second region having no through holes. Have and
The radius of the through hole is _ro ,
When half the distance between the centers of the through hole adjacent to the r _c,
At least one of the length of the second region in the first direction and the length of the second region is 4 × r _c- 2 × r ₀ or more.

When the physical quantity sensor of the present invention has three directions orthogonal to each other as the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body has a first region having a plurality of through holes penetrating in the third direction and having a polygonal opening shape when viewed from the third direction, and a second region having no through holes. Have,
The square root of the area of the through hole is S0,
When the distance between the adjacent through holes in the first direction and the distance in the second direction are added and divided by 2, the value is S1.
At least one of the length of the second region in the first direction and the length of the second region is S0 + 2 × S1 or more.

It is a top view which shows the physical quantity sensor which concerns on 1st Embodiment of this invention. FIG. 5 is a cross-sectional view taken along the line AA in FIG. It is a top view which shows the electrode which the physical quantity sensor shown in FIG. 1 has. FIG. 5 is a cross-sectional view taken along the line BB in FIG. It is a schematic diagram for demonstrating damping. It is a graph which shows the relationship between S0 and damping. It is a graph which shows the relationship between S1 / S0 and a sensitivity ratio and a damping ratio. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between the structure thickness and the hole size. It is a graph which shows the relationship between S0min, S1min and H, h. It is a graph which shows the relationship between S0min, S1min and H, h. It is a graph which shows the relationship between S0min, S1min and H, h. It is a graph which shows the relationship between S1min / S0min and H, h. It is a graph which shows the relationship between S1min / S0min and H, h. It is a graph which shows the relationship between S1min / S0min and H, h. It is a graph which shows the relationship between S1min / S0min and H, h. It is a graph which shows the relationship between the frequency of the received vibration and the displacement amount of a movable body. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a graph which shows the result of the random test of vibration resistance. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the modification of the physical quantity sensor of FIG. It is a top view which shows the physical quantity sensor which concerns on 2nd Embodiment of this invention. It is a top view which shows the physical quantity sensor which concerns on 3rd Embodiment of this invention. It is a top view which shows the smartphone as an electronic device which concerns on 4th Embodiment. It is an exploded perspective view which shows the inertial measurement unit as an electronic device which concerns on 5th Embodiment. It is a perspective view of the substrate which the inertial measurement unit shown in FIG. 40 has. It is a block diagram which shows the whole system of the mobile positioning apparatus as an electronic device which concerns on 6th Embodiment. It is a figure which shows the operation of the mobile positioning apparatus shown in FIG. 42. It is a perspective view which shows the moving body which concerns on 7th Embodiment.

Hereinafter, the physical quantity sensor, the electronic device, and the moving body of the present invention will be described in detail based on the embodiments shown in the accompanying drawings.

<First Embodiment>
First, the physical quantity sensor according to the first embodiment of the present invention will be described.

FIG. 1 is a plan view showing a physical quantity sensor according to the first embodiment of the present invention. FIG. 2 is a cross-sectional view taken along the line AA in FIG. FIG. 3 is a plan view showing an electrode included in the physical quantity sensor shown in FIG. FIG. 4 is a cross-sectional view taken along the line BB in FIG. FIG. 5 is a schematic diagram for explaining damping. FIG. 6 is a graph showing the relationship between S0 and damping. FIG. 7 is a graph showing the relationship between S1 / S0 and the sensitivity ratio and damping ratio. 8 to 16 are graphs showing the relationship between the structure thickness and the hole size. 17 to 23 are graphs showing the relationship between S0min and S1min and H and h. FIG. 24 is a graph showing the relationship between the frequency of the received vibration and the displacement amount of the movable body. 25 to 27 are plan views showing a modification of the physical quantity sensor of FIG. 1. FIG. 28 is a graph showing the results of a randomized test of vibration resistance. 29 to 36 are plan views showing a modification of the physical quantity sensor of FIG. 1.

In the following, for convenience of explanation, the three axes orthogonal to each other are the X-axis, the Y-axis, and the Z-axis, the direction parallel to the X-axis is the X-axis direction as the second direction, and the direction parallel to the Y-axis is the first. The Y-axis direction as one direction and the direction parallel to the Z-axis are also referred to as the Z-axis direction as the third direction. Further, the tip side in the arrow direction of each axis is also referred to as a "plus side", and the opposite side is also referred to as a "minus side". Further, the positive side in the Z-axis direction is also referred to as "upper", and the negative side in the Z-axis direction is also referred to as "lower". Further, the plan view from the Z-axis direction is also simply referred to as "plan view". Further, in FIGS. 25 to 36, the substrate 2 and the lid 5 are not shown for convenience of explanation.

Further, in the present specification, "orthogonal" includes not only the case where they intersect at 90 ° but also the case where they intersect at an angle slightly inclined from 90 °, for example, about 80 ° to 100 °. Specifically, when the X-axis is tilted by about -10 ° to + 10 ° with respect to the normal direction of the YZ plane, the Y-axis is tilted by about -10 ° to + 10 ° with respect to the normal direction of the XZ plane. If so, the case where the Z axis is tilted by about -10 ° to + 10 ° with respect to the normal direction of the XY plane is also included in "orthogonal".

The physical quantity sensor 1 shown in FIGS. 1 to 4 is an acceleration sensor capable of measuring the acceleration Az in the Z-axis direction. Such a physical quantity sensor 1 has a substrate 2, an element portion 3 arranged on the substrate 2, and a lid body 5 that covers the element portion 3 and is joined to the substrate 2. Hereinafter, each of these parts will be described in detail in order.

The substrate 2 has a plate shape and has a recess 21 that opens on the upper surface side. Further, in a plan view from the Z-axis direction, the recess 21 is formed larger than the element portion 3 so as to include the element portion 3 inside. The recess 21 functions as a relief portion for preventing contact between the element portion 3 and the substrate 2. Further, the recess 21 has a first recess 211 and a second recess 212 located on the positive side of the first recess 211 in the X-axis direction and deeper than the first recess 211. Therefore, the gap Q between the substrate 2 and the element portion 3 overlaps the first gap Q1 that overlaps the first recess 211 and the second recess 212, and is longer in the Z-axis direction than the first gap Q1. A second gap Q2 having a large separation distance between the substrate 2 and the element portion 3 is provided.

Further, the substrate 2 has a protruding mount portion 22 provided on the bottom surface of the first recess 211. Then, the fixing portion 31 of the element portion 3 is joined to the upper surface of the mount portion 22. As a result, the element portion 3 can be fixed to the substrate 2 in a state of being separated from the bottom surface of the recess 21. Further, the substrate 2 is located around the recess 21 and has grooves 25, 26, and 27 that are open to the upper surface side.

The substrate 2 is made of, for example, ^{a glass material containing an alkali metal ion (movable ion such as Na +} ) (for example, borosilicate glass such as Pyrex glass (registered trademark) and Tempax glass (registered trademark)). A glass substrate is used. However, the substrate 2 is not particularly limited, and for example, a silicon substrate or a ceramics substrate may be used.

Further, the substrate 2 has an electrode 8. The electrode 8 has a first fixed electrode 81, a second fixed electrode 82, and a dummy electrode 83 arranged on the bottom surface of the recess 21. Further, the substrate 2 has wirings 75, 76, 77 arranged in the grooves 25, 26, 27. One end of the wirings 75, 76, and 77 is exposed to the outside of the lid 5, and functions as an electrode pad P for electrically connecting to an external device. Further, the wiring 75 is electrically connected to the element portion 3 and the dummy electrode 83, the wiring 76 is electrically connected to the first fixed electrode 81, and the wiring 77 is electrically connected to the second fixed electrode 82. It is connected.

As shown in FIG. 2, the lid body 5 has a plate shape and has a recess 51 that opens on the lower surface side. The lid body 5 houses the element portion 3 in the recess 51 and is joined to the upper surface of the substrate 2. A storage space S for accommodating the element portion 3 is formed by the lid body 5 and the substrate 2. The storage space S is an airtight space. Further, the storage space S is filled with an inert gas such as nitrogen, helium, or argon, and the pressure is substantially atmospheric pressure at the operating temperature, for example, about −40 ° C. to 120 ° C. However, the atmosphere of the storage space S is not particularly limited, and may be in a reduced pressure state or a pressurized state, for example.

As the lid 5, for example, a silicon substrate can be used. However, the lid 5 is not particularly limited, and for example, a glass substrate or a ceramic substrate may be used. The method of joining the substrate 2 and the lid 5 is not particularly limited, and may be appropriately selected depending on the material of the substrate 2 and the lid 5. For example, the bonding surfaces activated by anode bonding or plasma irradiation are joined to each other. It is possible to use activation bonding, bonding with a bonding material such as glass frit, diffusion bonding for bonding metal films formed on the upper surface of the substrate 2 and the lower surface of the lid 5, and the like. In the present embodiment, the substrate 2 and the lid 5 are joined via a glass frit 59, which is a low melting point glass.

The lid body 5 is preferably connected to the ground. Thereby, the potential of the lid body 5 can be kept constant, and for example, the fluctuation of the capacitance between the lid body 5 and the element portion 3 can be reduced. The distance between the bottom surface of the recess 51 and the element portion 3 is not particularly limited, but is preferably, for example, 15 μm or more, more preferably 20 μm or more, and further preferably 25 μm or more. As a result, the capacitance between the lid 5 and the element portion 3 can be sufficiently reduced, and the acceleration Az can be detected more accurately.

As shown in FIGS. 1 and 2, the element portion 3 includes a fixed portion 31 joined to the upper surface of the mount portion 22, a plate-shaped movable body 32 displaceable with respect to the fixed portion 31, and the fixed portion 31. It has a support beam 33 that connects to the movable body 32. When the acceleration Az acts on the physical quantity sensor 1, the movable body 32 swings around the rotation axis J while twisting and deforming the support beam 33 with the support beam 33 as the rotation axis J.

Such an element portion 3 is formed by, for example, patterning a conductive silicon substrate doped with impurities such as phosphorus (P), boron (B), and arsenic (As) by dry etching. However, the method for forming the element portion 3 is not particularly limited. Further, the element portion 3 is bonded to the upper surface of the substrate 2 by anode bonding. However, the material of the element portion 3 and the method of joining the element portion 3 and the substrate 2 are not particularly limited.

The movable body 32 has a longitudinal shape along the X-axis direction in a plan view, and particularly in the present embodiment, it has a rectangular shape with the X-axis direction as a long side. The movable body 32 includes a first mass portion 321 located on the minus side in the X-axis direction with respect to the rotation axis J, and a second mass portion 322 located on the plus side in the X-axis direction with respect to the rotation axis J. , A connecting portion 323 that connects the first mass portion 321 and the second mass portion 322, and is connected to the support beam 33 at the connecting portion 323.

Further, the second mass part 322 is longer than the first mass part 321 in the X-axis direction, and the rotational moment, that is, the torque when the acceleration Az is applied is larger than that of the first mass part 321. Due to this difference in rotational moment, the movable body 32 swings around the rotation axis J when the acceleration Az is applied. In the following, the base end portion of the second mass portion 322, which is symmetrical to the first mass portion 321 with respect to the rotation axis J, is also referred to as a "base portion 322A" as the first portion, and is also referred to as a second mass portion. The portion of the tip of the 322 that is asymmetrical with the first mass portion 321 with respect to the rotation axis J is also referred to as a "torque generating portion 322B" as the second portion. An opening 325 extending in the Y-axis direction is formed at the boundary between the base portion 322A and the torque generating portion 322B.

Further, the movable body 32 has an opening 324 between the first mass portion 321 and the second mass portion 322, and the fixing portion 31 and the support beam 33 are arranged in the opening 324. As a result, the element unit 3 can be downsized. Further, the support beam 33 extends along the Y-axis direction to form the rotation axis J. However, the arrangement of the fixing portion 31 and the support beam 33 is not particularly limited, and may be located outside the movable body 32, for example.

Among the movable bodies 32 having such a configuration, the first mass portion 321 and the base portion 322A of the second mass portion 322 overlap with the first recess 211 in a plan view from the Z-axis direction, and the second mass portion 322. The torque generating portion 322B of the above overlaps with the second recess 212 in a plan view from the Z-axis direction.

Next, the electrode 8 will be described. As described above, the electrode 8 has a first fixed electrode 81, a second fixed electrode 82, and a dummy electrode 83. As shown in FIGS. 1 and 2, the first fixed electrode 81 is arranged in the first recess 211 and faces the first mass portion 321. Further, the second fixed electrode 82 is arranged in the first recess 211 and faces the base portion 322A of the second mass portion 322. The first and second fixed electrodes 81 and 82 are arranged symmetrically with respect to the rotation axis J in a plan view from the Z-axis direction.

Further, the dummy electrode 83 is located on the positive side of the second fixed electrode 82 in the X-axis direction, is arranged in the second recess 212, and faces the torque generating portion 322B of the second mass portion 322. The dummy electrode 83 is also located on the negative side of the first fixed electrode 81 in the X-axis direction. By providing the dummy electrode 83, it is possible to suppress the charging of the bottom surface of the recess 21 due to the movement of the alkali metal ions in the substrate 2. Therefore, it is effective to generate an unintended electrostatic attraction between the bottom surface of the recess 21 and the movable body 32, which leads to a malfunction of the movable body 32, particularly a displacement due to an external force other than the acceleration AZ which is the detection target. It can be suppressed. Therefore, the physical quantity sensor 1 can detect the acceleration Az more accurately.

When the physical quantity sensor 1 is driven, a predetermined drive voltage is applied to the element unit 3, and the first fixed electrode 81 and the second fixed electrode 82 are respectively connected to a QV amplifier (charge-voltage conversion circuit) (not shown). As a result, as shown in FIG. 2, a capacitance Ca is formed between the first fixed electrode 81 and the first mass portion 321, and the second fixed electrode 82 and the base portion 322A of the second mass portion 322 are formed. A capacitance Cb is formed between them.

When the acceleration Az is applied to the physical quantity sensor 1, the movable body 32 swings around the rotation axis J while twisting and deforming the support beam 33 due to the difference in the rotational moments of the first and second mass portions 321 and 322. Due to such swinging of the movable body 32, the gap between the first mass portion 321 and the first fixed electrode 81 and the gap between the base portion 322A and the second fixed electrode 82 of the second mass portion 322 change in opposite phases, respectively. The capacitances Ca and Cb change in opposite phases according to the above. Therefore, the acceleration Az can be detected based on the amount of change in the capacitances Ca and Cb, more specifically, the difference between the capacitances Ca and Cb.

As described above, the recess 21 is located on the plus side in the X-axis direction of the first recess 211 that overlaps the rotation axis J and the first recess 211 in a plan view from the Z-axis direction, and is deeper than the first recess 211. It has a second recess 212 and. That is, the farther the recess 21 is from the rotation axis J, the greater the depth, that is, the distance from the movable body 32. As a result, the separation distance between the movable body 32 and the first and second fixed electrodes 81 and 82 can be reduced while suppressing the contact between the movable body 32 and the substrate 2 during rocking. Therefore, the capacitances Ca and Cb can be increased, and the detection accuracy of the acceleration Az is improved.

Further, as shown in FIGS. 1, 3 and 4, the physical quantity sensor 1 has a protrusion 6 protruding from the bottom surface of the first recess 211 toward the movable body 32 side. The protrusion 6 functions as a stopper for restricting further swinging of the movable body 32 by coming into contact with the movable body 32 when the movable body 32 swings excessively. By providing the protrusion 6, it is possible to suppress excessive approach or contact between the movable body 32 having different potentials and the first and second fixed electrodes 81 and 82 over a wide area, and the movable body 32 and the first and first fixed electrodes 81 and 82 can be prevented from coming into contact with each other. Effectively suppressing the occurrence of "sticking" in which the movable body 32 is attracted to the first fixed electrode 81 or the second fixed electrode 82 and does not return due to the electrostatic attraction generated between the second fixed electrodes 81 and 82. Can be done. In the present embodiment, the protrusion 6 is integrally formed with the substrate 2, that is, is a part of the substrate 2, but the present invention is not limited to this, and the protrusion 6 may be formed separately from the substrate 2.

The protrusion 6 includes a protrusion 61 provided so as to overlap the first mass portion 321 and a protrusion 62 provided so as to overlap the base portion 322A of the second mass portion 322 in a plan view from the Z-axis direction. .. Of these, the protrusion 61 suppresses the excessive approach between the movable body 32 and the first fixed electrode 81, and the protrusion 62 suppresses the excessive approach between the movable body 32 and the second fixed electrode 82. Further, a pair of protrusions 61 and 62 are provided so as to be separated from each other in the Y-axis direction. Further, the pair of protrusions 61 and the pair of protrusions 62 are arranged symmetrically with respect to the rotation axis J in a plan view from the Z-axis direction.

Further, as shown in FIGS. 3 and 4, each of the protrusions 61 and 62 is covered with a dummy electrode 83 having the same potential as the movable body 32. As a result, it is possible to suppress the charging of the surfaces of the protrusions 61 and 62 due to the movement of the alkali metal ions in the substrate 2. Therefore, it is effective to generate an unintended electrostatic attraction between the protrusions 61 and 62 and the movable body 32, which leads to a malfunction of the movable body 32, particularly a displacement due to an external force other than the acceleration AZ which is the detection target. It can be suppressed. Further, since the dummy electrode 83 covering the protrusions 61 and 62 and the movable body 32 have the same potential, it is possible to suppress the generation of unnecessary electrostatic attraction and suppress the occurrence of sticking between the dummy electrode 83 and the movable body 32. can. Therefore, the physical quantity sensor 1 can detect the acceleration Az more accurately.

In the present embodiment, as shown in FIG. 3, a pair of notches 811 extending from the end on the minus side in the X-axis direction to each protrusion 61 are formed on the first fixed electrode 81, and the notches 811 are formed in the first fixed electrode 81. By stretching the dummy electrode 83, the protrusion 61 is covered with the dummy electrode 83. Similarly, the second fixed electrode 82 is formed with a pair of notches 821 extending from the positive end in the X-axis direction to each protrusion 62, and the dummy electrode 83 is extended in each notch 821 to extend the dummy electrode 83. Covers the protrusion 62 with.

However, the method of covering the protrusions 61 and 62 with the dummy electrode 83 is not particularly limited. Further, the protrusion 61 may be covered with the first fixed electrode 81, or may be exposed without being covered with the electrode 8. Similarly, the protrusion 62 may be covered with the second fixed electrode 82, or may be exposed without being covered with the electrode 8. Further, the protrusion 6 may be omitted.

Returning to the description of the movable body 32, as shown in FIGS. 1, 2 and 4, the movable body 32 includes a plurality of through holes 30 that penetrate the movable body 32 in the thickness direction along the Z axis thereof. It has a first region R1 and a second region R2 that does not have a through hole 30. Since the movable body 32 has the first region R1 provided with the through hole 30, the damping of gas when the movable body 32 swings can be reduced, and the vibration characteristics of the movable body 32 are improved. On the other hand, since the movable body 32 has the second region R2 having no through hole 30, the damping can be increased and the movable body 32 can be made difficult to vibrate in the high frequency region. Further, by not forming the through hole 30, the lowered movable body 32 can be reinforced. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

As shown in FIG. 1, each of the plurality of through holes 30 formed in the first region R1 has a square opening shape in a plan view, and has a pair of sides extending in the X-axis direction and in the Y-axis direction. It has a pair of extending sides. The plurality of through holes 30 are uniformly arranged over the entire area of the first region R1. Further, the plurality of through holes 30 are regularly arranged in a plan view, and in particular, in the present embodiment, they are arranged in a matrix arranged in the X-axis direction and the Y-axis direction. Further, the plurality of through holes 30 have the same size as each other.

The term "uniform" means that the distances between the through holes 30 adjacent to each other in the X-axis direction and the Y-axis direction are the same for all the through holes 30, and also takes into account errors that may occur in manufacturing. It means that a part of the separation distance is slightly deviated from the other separation distance, for example, by about 10% or less. Similarly, the "square" means that it is substantially a square, and in addition to the case where it matches the square, the four corners take into account a shape slightly deviated from the square, for example, an error that may occur in manufacturing. Is not a corner and is chamfered or rounded, at least one corner is offset within a range of 90 ° to ± 10 °, or the length of at least one side is the length of the other side. It also means that the aspect ratio of the opening is in the range of about 1: 1.1 to 1.1: 1.

Next, the design of the through hole 30 in the first region R1 will be specifically described. The through hole 30 is provided to control the damping of gas when the movable body 32 swings around the rotation axis J. As shown in FIG. 5, the damping is composed of a damping in the hole of the gas passing through the through hole 30 and a squeeze film damping between the movable body 32 and the substrate 2.

The larger the through hole 30, the easier it is for gas to pass through the through hole 30, so that damping in the hole can be reduced. Further, as the occupancy rate of the through hole 30 is increased, the area where the movable body 32 and the substrate 2 face each other is reduced, so that the squeeze film damping can be reduced. However, at the same time, the area facing the movable body 32 and the first and second fixed electrodes 81 and 82 is reduced, and the mass of the torque generating unit 322B is reduced, so that the detection sensitivity of the acceleration Az is lowered. On the contrary, as the through hole 30 is made smaller, that is, as the occupancy rate is lowered, the facing area between the movable body 32 and the first and second fixed electrodes 81 and 82 increases, and the mass of the torque generating portion 322B increases. Therefore, the detection sensitivity of the acceleration Az is improved, but the damping is increased. In this way, the detection sensitivity and damping are in a trade-off relationship.

In the physical quantity sensor 1, the detection sensitivity and the damping are compatible with each other by devising the design of the through hole 30. This will be specifically described below. ^{The detection sensitivities of the physical quantity sensor 1 are (A) 1 / h 2} when the distance between the movable body 32 and the bottom surface of the recess 21, more precisely, the surface of the electrode 8 is h, and (B) the movable body 32. It is proportional to the area facing the first and second fixed electrodes 81 and 82, (C) 1 / k when the spring rigidity of the support beam 33 is k, and (D) the mass of the torque generating portion 322B. The spring rigidity of the support beam 33 is proportional to the length H of the through hole 30 in the Z-axis direction when the thickness of the movable body 32 is uniform. In the physical quantity sensor 1, first, in a state where damping is ignored, the areas of H, h and the movable body 32 facing the first and second fixed electrodes 81 and 82, which are necessary for obtaining the required detection sensitivity, in other words. And the occupancy rate of the through hole 30 in the first mass portion 321 and the base portion 322A are determined. As a result, the capacitances Ca and Cb of the required sizes are formed, and the physical quantity sensor 1 can obtain sufficient detection sensitivity.

The occupancy rate of the through hole 30 in the first region R1 is not particularly limited, but is, for example, preferably 75% or more, more preferably 78% or more, and further preferably 82% or more. preferable. This makes it easier to achieve both detection sensitivity and damping.

After determining the occupancy rate of the through hole 30 in the first mass portion 321 and the base portion 322A in this way, the portion where the separation distance h between the bottom surface of the recess 21 and the element portion 3 is different, that is, the first mass portion 321 and The base portion 322A and the torque generating portion 322B are independently designed for damping.

As a new technical idea to minimize damping without changing the sensitivity, in the physical quantity sensor 1, the difference between the damping in the hole and the squeeze film damping shown in FIG. 5 is preferably as small as possible. A plurality of through holes 30 are designed so as to be equal to the squeeze film damping. By reducing the difference between the hole damping and the squeeze film damping as much as possible in this way, the damping can be reduced, and in particular, when the hole damping and the squeeze film damping are equal, the damping is minimized. Therefore, according to the physical quantity sensor 1, damping can be effectively reduced while maintaining a sufficiently high detection sensitivity.

Since the methods of damping design in the first mass portion 321 and the base portion 322A and the torque generating portion 322B are the same as each other, the damping design of the first mass portion 321 will be described as a representative below, and the base portion 322A and the torque will be described. The description of the damping design of the generation unit 322B will be omitted.

As shown in FIGS. 1 and 2, the length of the Z-axis (thickness of the movable body 32) of the through hole 30 arranged in the first region R1 of the first mass portion 321 is H [m], the first. The length of 1/2 of the length of the mass portion 321 along the Y-axis direction is a [m], the length along the X-axis direction is L [m], the first fixed electrode 81 and the first mass portion 321. The distance from the through hole 30 is h [m], the length of one side of the square of the through hole 30 is S0 [m], the distance between the through holes 30 adjacent to each other in the X-axis direction or the Y-axis direction is S1 [m], and the first When the viscous resistance (viscosity coefficient) of the gas in the gap Q1, that is, the gas filled in the storage space S is μ [kg / ms], and the damping generated in the first mass portion 321 is C, C is as follows. It is expressed by the equation (2) of. Equation (2) is the same as Equation (1).

ただし、式（２）で用いているパラメーターは、下記式（３）〜（９）で表される。

However, the parameters used in the equation (2) are represented by the following equations (3) to (9).

Here, the hole damping component included in the formula (2) is represented by the following formula (10), and the squeeze film damping component is represented by the following formula (11).

Therefore, the damping C is minimized by using the dimensions of H, h, S0, and S1 in which the above equation (10) and the above equation (11) are equal, that is, satisfying the following equation (12).

Here, when the length S0 of one side of the through hole 30 satisfying the above formula (12) is S0min, the distance S1 between adjacent through holes 30 is S1min, and these S0min and S1min are substituted into the above formula (2). Damping C, that is, the minimum value of damping C is Cmin.

Although it depends on the accuracy required for the physical quantity sensor 1, in the base portion 322A of the first mass part 321 and the second mass part 322, the range of S0 and S1 when H and h are constant has the following equation (13). It is preferable to satisfy, it is more preferable to satisfy the following formula (14), further preferably to satisfy the following formula (15), and most preferably to satisfy the following formula (16). As a result, the damping of the movable body 32 can be sufficiently reduced, the detection sensitivity can be maintained within a desired band, and noise can be reduced.

FIG. 6 is a graph showing the relationship between the length S0 of one side of the through hole 30 and damping. H and h were constant, and the S1 / S0 ratio was 1 so that the sensitivity was constant. This indicates that the opening ratio does not change even if the size of S0 is changed. From this graph, the damping of the above formula (2) can be separated into the squeeze film damping of the above formula (11) and the damping in the hole of the above formula (10), and the damping in the hole is dominant in the region where S0 is smaller than S0min. It can be seen that squeeze film damping is dominant in the region where S0 is larger than S0min. S0 satisfying the above equation (13) is in the range from S0'on the side smaller than S0min to S0' on the side larger than S0min.

Further, since the torque generating portion 322B of the second mass portion 322 is provided at a position far from the rotation axis J, the displacement of the movable body 32 is larger than that of the first mass portion 321 and the base portion 322A. Although the damping must be large, the range of S0 and S1 when H and h are constant preferably satisfies the following formula (17), more preferably the following formula (18), and the following formula. It is more preferable to satisfy (19), and most preferably to satisfy the following formula (20). Thereby, the damping of the movable body 32 can be sufficiently reduced. Further, it becomes easy to secure the mass of the torque generating unit 322B, and the decrease in the detection sensitivity can be effectively suppressed.

The relationship between S0 and S1 is not particularly limited, but it is preferable to satisfy the following formula (21), more preferably to satisfy the following formula (22), and further preferably to satisfy the following formula (23). By satisfying such a relationship, the through hole 30 can be formed in the movable body 32 in a well-balanced manner.

Further, FIG. 7 is a graph showing the relationship between S1 / S0 and the sensitivity ratio and the minimum damping ratio. The sensitivity ratio is the ratio to the sensitivity when S1 / S0 = 1, and the minimum damping ratio is the ratio to the minimum damping when S1 / S0 = 1. As can be seen from the figure, when S1 / S0> 3, the increase rate of the sensitivity ratio tends to be saturated, and the minimum damping ratio tends to increase significantly. Therefore, the following equations (21) to (23) are used. By satisfying the requirements, damping can be sufficiently reduced while sufficiently increasing the detection sensitivity.

Here, the simulation and experimental verification related to the dimensional ratio S1 / S0 in the process of deriving the range of the above equations (21) to (23) will be described in detail below. 8 to 16 show hole sizes and interpupillary distance values such that H is 5 to 80 μm, h is 1.0 to 3.5 μm, and S1 / S0 is S0min and S1min in the range of 0.25 to 3.0 μm. It is a graph plotting. Then, based on S0min and S1min obtained in FIGS. 8 to 16, the graph is summarized as the horizontal axis S0 and the vertical axis S1 as shown in the graph of FIG. Further, as an example, S0min and S1min when S1 / S0 = 0.25 and H = 5 μm and h = 1.0 to 3.5 μm are shown in FIG. 18, and S1 / S0 = 0.25 and H = FIG. 19 shows S0min and S1min when 80 μm is set and h = 1.0 to 3.5 μm. From FIGS. 18 and 19, it can be seen that the larger H or h is, the larger the dimensions of S0min and S1min tend to be.

Here, FIG. 20 shows the range of all points of S0min and S1min in the range of 5 to 80 μm for H, 1.0 to 3.5 μm for h, and 0.25 to 3.0 for S1 / S0. The direction of arrow A is determined by the range of S1 / S0, and the direction of arrow B is determined by the range of H and h. Further, as an example, the conditions of S0min and S1min when S1min / S0min = 0.25 to 3.0, H = 20 μm, and h = 1.0 to 3.5 μm are as shown in FIG. Further, FIG. 22 shows a region in which H = 5 to 80 μm and h = 1.0 to 3.5 μm and S1min / S0min is limited in the range of the above formulas (21) to (23).

Up to this point, S0min and S1min have been described, but for S0 and S1 in the range of the above equations (13) to (23), for example, when H = 20 μm and h = 3.5 μm as an image, S0min, Since it includes the periphery of S1min, it is in the range shown in FIG. 23, and when viewed as a whole, it is a range in which only two sides are widened.

The length H of the through hole 30 in the Z-axis direction, that is, the thickness of the movable body 32 is not particularly limited, but is preferably 5.0 μm or more and 80.0 μm or less, for example. As a result, a sufficiently thin movable body 32 can be obtained while maintaining the mechanical strength. Therefore, the physical quantity sensor 1 can be miniaturized. The length h of the gap Q is not particularly limited, but is preferably 1.0 μm or more and 3.5 μm or less, for example. As a result, the capacitances Ca and Cb can be sufficiently increased while sufficiently securing the range of motion of the movable body 32. The length S0 is not particularly limited and varies depending on the lengths a and L, but is preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less.

The design of the through hole 30 in the first region R1 has been described above. Next, the second region R2 will be described. As described above, the through hole 30 is not formed in the second region R2. By providing the movable body 32 with such a second region R2, the mechanical strength of the movable body 32 can be increased. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, as shown in FIG. 24, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered in the high frequency region, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

As shown in FIG. 1, such a second region R2 is provided at the base portion 322A of the first mass portion 321 and the second mass portion 322. Further, the first mass portion 321 is provided with a pair of second regions R2 separated from each other in the Y-axis direction. Then, in a plan view from the Z-axis direction, one second region R2 overlaps with one protrusion 61, and the other second region R2 overlaps with the other protrusion 61. That is, when the movable body 32 is excessively shaken, the first mass portion 321 comes into contact with the protrusion 61 in the second region R2. Further, in the base portion 322A, a pair of second regions R2 are provided so as to be separated from each other in the Y-axis direction. Then, in a plan view from the Z-axis direction, one second region R2 overlaps with one protrusion 62, and the other second region R2 overlaps with the other protrusion 62. That is, when the movable body 32 swings excessively, the second mass portion 322 comes into contact with the protrusion 62 in the second region R2. Since the through hole 30 is not formed in the second region R2, the mechanical strength of the second region R2 is higher than that of the first region R1 in which the through hole 30 is formed. Therefore, by bringing the second region R2 into contact with the protrusions 61 and 62, damage to the movable body 32 due to the impact generated at the time of contact can be effectively suppressed.

Further, in a plan view from the Z-axis direction, the pair of second regions R2 provided in the first mass portion 321 and the pair of second regions R2 provided in the base portion 322A of the second mass portion 322 are rotating axes. It is arranged symmetrically with respect to J. As a result, the moments of inertia around the rotation axis J of the first mass portion 321 and the base portion 322A can be made uniform.

Further, each of the four second regions R2 has a square shape in a plan view from the Z-axis direction, and has a configuration in which the formation of a total of 9 through holes 30 of 3 × 3 is omitted. The width Wx, which is the length of each second region R2 in the X-axis direction, is 3 × S0 + 4 × S1, and the width Wy, which is the length in the Y-axis direction, is also 3 × S0 + 4 × S1. That is, the area of each second region R2 is (3 × S0 + 4 × S1) ² = 9 × S0 ² + 16 × S1 ² + 24 × S0 × S1, and the total area of the four second regions R2 is 4 (3 × 3 ×. S0 + 4 × S1) ² = 36 × S0 ² +64 × S1 ² +96 × S0 × S1. By setting the total area of the second region R2 to 36 × S0 ² + 64 × S1 ² + 96 × S0 × S1 or more, the squeeze film damping of the movable body 32 can be sufficiently increased, and the movable body 32 in the high frequency region can be sufficiently increased. The amount of displacement of is sufficiently small.

The area of the second region R2 (total area if there are a plurality of regions) is ^{preferably 17100 μm 2} or less. As a result, a detectable frequency band, in other words, a sufficiently detectable minimum frequency can be secured. The lowest detectable frequency is preferably, for example, about 500 Hz. As a result, the physical quantity sensor 1 can detect vibrations having a sufficiently low frequency and can be easily mounted on any electronic device.

Although the physical quantity sensor 1 has been described above, the configuration of the physical quantity sensor 1, particularly the configuration of the second region R2 is not particularly limited, and at least one of the width Wx and the width Wy is S0 + 2 × S1 or more. good. That is, if Wx ≧ S0 + 2 × S1 or Wy ≧ S0 + 2 × S1 is satisfied, the above-mentioned effect can be exhibited. As such an example, for example, there is a configuration as shown in FIG. 25, and each second region R2 has a configuration in which the formation of one through hole 30 is omitted. That is, Wx = S0 + 2 × S1 and Wy = S0 + 2 × S1.

Further, for example, in the configuration shown in FIG. 26, each second region R2 has a configuration in which the formation of a total of 25 through holes 30 of 5 × 5 is omitted centering on the portion overlapping the protrusions 61 and 62. .. Further, for example, in the configuration shown in FIG. 27, each second region R2 has a configuration in which the formation of a total of 49 through holes 30 of 7 × 7 is omitted centering on the portion overlapping the protrusions 61 and 62. .. As described above, as the area of the second region R2 is increased, the movable body 32 is less likely to vibrate in the high frequency region.

FIG. 28 is a graph showing the results of a randomized vibration resistance test for the configuration mp1 having no second region R2, the configuration mp2 of the present embodiment, the configuration mp3 of FIG. 26, and the configuration mp4 shown in FIG. 27. Here, the vibration resistance ratios of the configurations mp2, smp3, and mp4 are shown when the vibration resistance of the configuration mp1 is 1. It can be seen that the configuration smp2, smp3, and smp4 having the second region R2 all have higher vibration resistance than the configuration mp1 having no second region R2.

Further, the second region R2 may be provided at a position where it does not overlap with the protrusions 61 and 62. For example, in the configuration shown in FIG. 29, the second region R2 is not provided in the base portion 322A of the first mass portion 321 and the second mass portion 322, but is provided only in the torque generating portion 322B. Further, the second region R2 is provided in pairs separated in the Y-axis direction, and each second region R2 has a configuration in which the formation of a total of 25 through holes 30 of 5 × 5 is omitted.

Further, for example, in the configuration shown in FIG. 30, one second region R2 is provided at each of the base portion 322A of the first mass portion 321 and the second mass portion 322. Further, the second region R2 provided in the first mass portion 321 is provided in the central portion of the first mass portion 321 so as not to overlap with the protrusion 61, and the second region R2 provided in the base portion 322A is provided. It is provided at the center of the base portion 322A so as not to overlap the protrusion 62. Further, each second region R2 has a configuration in which the formation of a total of 25 through holes 30 of 5 × 5 is omitted. Further, for example, in the configuration shown in FIG. 31, in addition to the configuration shown in FIG. 30, a second region R2 is further provided in the torque generating unit 322B. The second region R2 provided in the torque generating portion 322B is provided in the central portion of the torque generating portion 322B, and is a total of 5 × 5 like the second region R2 provided in the first mass portion 321 and the base portion 322A. The configuration is such that the formation of the 25 through holes 30 is omitted.

Further, for example, in the configuration shown in FIG. 32, five second regions R2 are provided at each of the base portion 322A of the first mass portion 321 and the second mass portion 322. Further, the five second regions R2 provided in the first mass portion 321 are dispersedly provided in the central portion and the four corners of the first mass portion 321 so as not to overlap with the protrusion 61, and are provided in the base portion 322A. Similarly, the five second regions R2 provided are also dispersedly provided at the central portion and the four corners of the base portion 322A so as not to overlap the protrusions 62. In this way, by arranging the second region R2 on the movable body 32 in a well-balanced manner, uneven formation (roughness) of the through holes 30 in the movable body 32 is reduced. Therefore, the processing accuracy of the through hole 30 can be improved.

Further, for example, in the configuration shown in FIG. 33, in addition to the configuration shown in FIG. 32, the torque generating portion 322B of the second mass portion 322 is also provided with five second regions R2. Further, the five second regions R2 provided in the torque generating portion 322B are dispersedly provided in the central portion and the four corners of the torque generating portion 322B. Further, for example, in the configuration shown in FIG. 34, the arrangement of the second region R2 is the same as that shown in FIG. 33, but the second region R2 located at the center of each is 1 × 3, for a total of three. The formation of the through holes 30 is omitted, and the second region R2 located at the four corners is configured to omit the formation of a total of eight through holes 30 of 2 × 4. Further, for example, in the configuration shown in FIG. 35, the second region R2 provided in the first mass portion 321 and the second region R2 provided in the base portion 322A are omitted from the configuration shown in FIG. 33. ..

Further, for example, in the configuration shown in FIG. 36, even in the torque generating unit 322B, the range of S0 and S1 when H and h are constant satisfies the above equation (17). As a result, the damping of the movable body 32 can be sufficiently reduced, the detection sensitivity can be maintained within a desired band, and noise can be reduced. Further, it is preferable to satisfy the above formula (18), more preferably to satisfy the above formula (19), and further preferably to satisfy the above formula (20). In this configuration, the length h of the gap Q in the Z-axis direction has a relationship of first mass portion 321 = base portion 322A <torque generating portion 322B, and therefore, accordingly, the length S0 of one side of the through hole 30. However, the first mass portion 321 = base portion 322A <torque generating portion 322B, and the distance S1 between the adjacent through holes 30 is the first mass portion 321 = base portion 322A <torque generating portion 322B.

The physical quantity sensor 1 has been described above. As described above, in such a physical quantity sensor 1, when the three directions orthogonal to each other are the Y-axis direction which is the first direction, the X-axis direction which is the second direction, and the Z-axis direction which is the third direction, It has a substrate 2 and a movable body 32 that faces the substrate 2 in the Z-axis direction across a gap and is displaced in the Z-axis direction with respect to the substrate 2. Further, the movable body 32 has a first region R1 having a plurality of through holes 30 penetrating in the Z-axis direction and having a square opening shape when viewed from the Z-axis direction, and a second region R1 having no through holes 30. It has R2 and. Then, when the length of one side of the through hole 30 is S0 and the distance between the adjacent through holes 30 is S1, the width Wx which is the length of the second region R2 in the X-axis direction and the length in the Y-axis direction are used. At least one of a certain width Wy is S0 + 2 × S1 or more.

By providing the movable body 32 with the second region R2 having such a size, the mechanical strength of the movable body 32 can be increased. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

Further, as described above, the area of the second region R2 is ^{36 × S0 2 + 64 × S1} 2 + 96 × S0 × S1 or greater. As a result, the squeeze film damping of the movable body 32 can be sufficiently increased, and the displacement amount of the movable body 32 in the high frequency region can be suppressed to be sufficiently small.

Further, as described above, the area of the second region R2 is 17100 μm ² or less. As a result, a detectable frequency band, in other words, a sufficiently detectable minimum frequency can be secured.

Further, as described above, the first region R1 satisfies the above formula (13). As a result, the design of the plurality of through holes 30 becomes appropriate, and damping can be sufficiently reduced while having excellent detection sensitivity. Therefore, the physical quantity sensor 1 capable of securing a desired frequency band while having excellent detection sensitivity can be obtained.

Further, as described above, the physical quantity sensor 1 is a support beam 33 that connects the fixed portion 31 fixed to the substrate 2 and the movable body 32 and the fixed portion 31 to form a rotation axis J along the Y-axis direction. , Have. Further, the movable body 32 is displaceable around the rotation axis J, and is located on one side in the X-axis direction with respect to the rotation axis J in a plan view from the Z-axis direction. And a second mass portion 322, which is located on the other side and whose rotational moment around the rotation axis J is larger than that of the first mass portion 321. Further, the second mass portion 322 is located at the base portion 322A, which is a first portion symmetrical to the first mass portion 321 with respect to the rotation axis J, and distal to the rotation axis J with respect to the base portion 322A, and is located on the rotation axis J. On the other hand, it has a first mass portion 321 and a torque generating portion 322B which is an asymmetrical second portion. Then, the first region R1 located in the first mass portion 321 and the base portion 322A satisfies C ≦ 1.5 × Cmin, respectively. As a result, even in the movable body 32 that swings on the seesaw, the damping of the first region R1 can be sufficiently reduced.

Further, as described above, the first region R1 located in the torque generating unit 322B satisfies C ≦ 2.5 × Cmin. As a result, even in the movable body 32 that swings on the seesaw, the damping of the first region R1 can be sufficiently reduced. Further, it becomes easy to secure the mass of the torque generating unit 322B, and the decrease in the detection sensitivity can be effectively suppressed.

Further, as described above, the physical quantity sensor 1 has a protrusion 6 that protrudes from the substrate 2 toward the movable body 32 and overlaps with the second region R2 in a plan view from the Z-axis direction. As a result, the mechanical strength of the portion of the movable body 32 that comes into contact with the protrusion 6 is increased, and damage to the movable body 32 due to contact can be suppressed. Further, by coming into contact with the protrusion 6, it is possible to effectively suppress the sticking of the movable body 32 to the substrate 2.

<Second Embodiment>
FIG. 37 is a plan view showing a physical quantity sensor according to a second embodiment of the present invention.

This embodiment is the same as the above-described first embodiment except that the opening shape of the through hole 30 is different. In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description of the same matters will be omitted. Further, in FIG. 37, the same reference numerals are given to the same configurations as those in the above-described embodiment.

As shown in FIG. 37, each of the plurality of through holes 30 formed in the first region R1 has a circular opening shape in a plan view. The plurality of through holes 30 are uniformly arranged over the entire area of the first region R1. Further, the plurality of through holes 30 are regularly arranged in a plan view, and in particular, in the present embodiment, they are arranged in a matrix arranged in the X-axis direction and the Y-axis direction. Further, the plurality of through holes 30 have the same size as each other.

In addition, "circular" means that it is substantially circular, and in addition to the case where it matches the circular shape, the roundness is taken into consideration in consideration of a shape slightly deviated from the circular shape, for example, an error that may occur in manufacturing. Means that includes those in the range of 0.9 to 1.0.

Here, in the present embodiment, r ₀ of the above formula (9) is the radius of the through hole 30, and r _c of the above formula (8) is half the distance between the centers of the adjacent through holes 30.

In the physical quantity sensor 1 having such a configuration, at least one of the width Wx and the width Wy of each second region R2 is 4 × r _c- 2 × r ₀ or more. Thereby, the mechanical strength of the movable body 32 can be increased as in the first embodiment described above. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

In particular, in the present embodiment, both the width Wx and the width Wy are 4 × r _c- 2 × r ₀ or more. That is, the width Wx ≧ 4 × r _c -2 × r ₀ and the width Wy ≧ 4 × r _c -2 × r ₀ . As a result, the above-mentioned effect becomes more remarkable. In the present embodiment, each of the second regions R2 has a square shape in a plan view from the Z-axis direction, and the formation of a total of 9 through holes 30 of 3 × 3 is omitted. ing. Therefore, the width Wx and the width Wy of each second region R2 are 8 × r _{c −} 2 × r ₀ , respectively. Therefore, it has a sufficiently large width Wx and Wy with respect to the lower limit value of 4 × r _c- 2 × r ₀ , and the above-mentioned effect becomes more remarkable.

As described above, in the physical quantity sensor 1 of the present embodiment, when the three directions orthogonal to each other are the Y-axis direction which is the first direction, the X-axis direction which is the second direction, and the Z-axis direction which is the third direction. A movable body 32 that faces the substrate 2 in the Z-axis direction with a gap between the substrate 2 and is displaced in the Z-axis direction with respect to the substrate 2. Further, the movable body 32 has a first region R1 having a plurality of through holes 30 penetrating in the Z-axis direction and having a circular opening shape when viewed from the Z-axis direction, and a second region R1 having no through holes 30. It has R2 and. The radius r _o of the through hole _30, a half of the distance between the centers of the through holes 30 adjacent when the r _c, X-axis direction width Wx and the Y-axis direction is a length of the second region R2 At least one of the width Wy, which is the length, is 4 × r _c- 2 × r ₀ or more.

By providing the movable body 32 with the second region R2 having such a size, the mechanical strength of the movable body 32 can be increased. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

The second embodiment as described above can also exert the same effect as the first embodiment described above.

<Third Embodiment>
FIG. 38 is a plan view showing a physical quantity sensor according to a third embodiment of the present invention.

This embodiment is the same as the above-described first embodiment except that the opening shape of the through hole 30 is different. In the following description, the present embodiment will be mainly described with respect to the differences from the above-described embodiment, and the description of the same matters will be omitted. Further, in FIG. 38, the same reference numerals are given to the same configurations as those in the above-described embodiment.

As shown in FIG. 38, each of the plurality of through holes 30 formed in the first region R1 has a regular pentagonal opening shape in a plan view. The plurality of through holes 30 are uniformly arranged over the entire area of the first region R1. Further, the plurality of through holes 30 are regularly arranged in a plan view, and in particular, in the present embodiment, they are arranged in a matrix arranged in the X-axis direction and the Y-axis direction. Further, the plurality of through holes 30 have the same size as each other.

In the above-described first embodiment, the length of one side of the square of the through hole 30 is set to S0, and the distance between the through holes 30 adjacent to each other in the X-axis direction or the Y-axis direction is set to S1. Let S0 be the square root of the area of the through holes 30, and let S1 be the value obtained by adding the distance Dx in the X-axis direction and the distance Dy in the Y-axis direction between adjacent through holes 30 and dividing by 2.

In the physical quantity sensor 1 having such a configuration, at least one of the width Wx and the width Wy of each second region R2 is S0 + 2 × S1 or more. Thereby, the mechanical strength of the movable body 32 can be increased as in the first embodiment described above. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

In particular, in the present embodiment, both the width Wx and the width Wy are S0 + 2 × S1 or more. That is, the width Wx ≧ S0 + 2 × S1 and the width Wy ≧ S0 + 2 × S1. As a result, the above-mentioned effect becomes more remarkable. In the present embodiment, each of the second regions R2 has a square shape in a plan view from the Z-axis direction, and the formation of a total of 9 through holes 30 of 3 × 3 is omitted. ing. Therefore, the width Wx and the width Wy of each second region R2 are about 3 × S0 + 4 × S1, respectively. Therefore, it has a sufficiently large width Wx and Wy with respect to the lower limit value S0 + 2 × S1, and the above-mentioned effect becomes more remarkable.

As described above, in the physical quantity sensor 1 of the present embodiment, when the three directions orthogonal to each other are the Y-axis direction which is the first direction, the X-axis direction which is the second direction, and the Z-axis direction which is the third direction. A movable body 32 that faces the substrate 2 in the Z-axis direction with a gap between the substrate 2 and is displaced in the Z-axis direction with respect to the substrate 2. Further, the movable body 32 penetrates in the Z-axis direction, and has a first region R1 having a plurality of through holes 30 having a polygonal opening shape when viewed from the Z-axis direction, and a second region R1 having no through holes 30. It has a region R2 and. Then, when the square root of the area of the through hole 30 is S0, the distance Dx in the X-axis direction between the adjacent through holes 30 and the distance Dy in the Y-axis direction are added and divided by 2, the second region is defined as S1. At least one of the width Wx, which is the length of R2 in the X-axis direction, and the width Wy, which is the length in the Y-axis direction, is S0 + 2 × S1 or more.

By providing the movable body 32 with the second region R2 having such a size, the mechanical strength of the movable body 32 can be increased. It is also possible to intentionally increase the squeeze film damping of the movable body 32. Therefore, the Q value of the frequency characteristic of the physical quantity sensor 1 can be lowered, and the movable body 32 is less likely to vibrate in the high frequency region. Therefore, it is possible to make the movable body 32 less likely to generate vibration in the high frequency region, and further, it is possible to effectively suppress damage to the movable body 32 even when strong vibration in the high frequency region is applied.

The third embodiment as described above can also exert the same effect as the first embodiment described above.

Here, in the present embodiment, the opening shape of the through hole 30 in a plan view is a regular pentagon, but the opening shape is not limited to this, and for example, a pentagon other than a triangle, a quadrangle, and a regular pentagon, a hexagon, and a hexagon or more. It may be a polygon. Even if the opening shape of the through hole 30 is a polygon other than a regular pentagon, the same effect as that of the present embodiment can be obtained.

<Fourth Embodiment>
FIG. 39 is a plan view showing a smartphone as an electronic device according to the fourth embodiment.

The smartphone 1200 shown in FIG. 39 is an application of the electronic device of the present invention. The smartphone 1200 has a built-in physical quantity sensor 1 and a control circuit 1210 that controls based on a detection signal output from the physical quantity sensor 1. The detection data detected by the physical quantity sensor 1 is transmitted to the control circuit 1210, and the control circuit 1210 recognizes the posture and behavior of the smartphone 1200 from the received detection data and changes the image displayed on the display unit 1208. It can be made to vibrate, sound a warning sound or a sound effect, or drive a vibration motor to vibrate the main body.

The smartphone 1200 as such an electronic device includes a physical quantity sensor 1 and a control circuit 1210 that controls based on a detection signal output from the physical quantity sensor 1. Therefore, the effect of the physical quantity sensor 1 described above can be enjoyed, and high reliability can be exhibited.

In addition to the smartphone 1200 described above, the electronic device of the present invention includes, for example, a personal computer, a digital still camera, a tablet terminal, a clock, a smart watch, an inkjet printer, a laptop personal computer, a television, a smart glass, and an HMD. Wearable terminals such as (head mount display), video cameras, video tape recorders, car navigation devices, drive recorders, pagers, electronic notebooks, electronic dictionaries, electronic translators, calculators, electronic game devices, toys, word processors, workstations, televisions Telephones, security TV monitors, electronic binoculars, POS terminals, medical equipment, fish finder, various measuring equipment, mobile terminal base station equipment, vehicles, railroad vehicles, aircraft, helicopters, various instruments such as ships, flight simulators , Network server, etc.

<Fifth Embodiment>
FIG. 40 is an exploded perspective view showing an inertial measurement unit as an electronic device according to a fifth embodiment. FIG. 41 is a perspective view of a substrate included in the inertial measurement unit shown in FIG. 40.

The inertial measurement unit 2000 (IMU: Inertial Measurement Unit) as an electronic device shown in FIG. 40 is an inertial measurement unit that detects the posture and behavior of an attached device such as an automobile or a robot. The inertial measurement unit 2000 functions as a 6-axis motion sensor including a 3-axis acceleration sensor and a 3-axis angular velocity sensor.

The inertial measurement unit 2000 is a rectangular parallelepiped having a substantially square plane shape. Further, screw holes 2110 as fixing portions are formed in the vicinity of two vertices located in the diagonal direction of the square. The inertial measurement unit 2000 can be fixed to the mounted surface of a mounted body such as an automobile by passing two screws through the two screw holes 2110. By selecting parts and changing the design, it is possible to reduce the size to a size that can be mounted on a smartphone or a digital camera, for example.

The inertial measurement unit 2000 includes an outer case 2100, a joining member 2200, and a sensor module 2300, and has a configuration in which the sensor module 2300 is inserted by interposing the joining member 2200 inside the outer case 2100. There is. The outer shape of the outer case 2100 is a rectangular parallelepiped whose plane shape is substantially square, similar to the overall shape of the inertial measurement unit 2000 described above, and screw holes 2110 are formed in the vicinity of two vertices located in the diagonal direction of the square. Has been done. Further, the outer case 2100 has a box shape, and the sensor module 2300 is housed inside the outer case 2100.

The sensor module 2300 has an inner case 2310 and a substrate 2320. The inner case 2310 is a member that supports the substrate 2320, and has a shape that fits inside the outer case 2100. Further, the inner case 2310 is formed with a recess 2311 for preventing contact with the substrate 2320 and an opening 2312 for exposing the connector 2330 described later. Such an inner case 2310 is joined to the outer case 2100 by a joining member 2200. Further, the lower surface of the inner case 2310 is bonded to the substrate 2320 with an adhesive.

As shown in FIG. 41, on the upper surface of the substrate 2320, there are a connector 2330, an angular velocity sensor 2340z for detecting an angular velocity around the Z axis, an acceleration sensor 2350 for detecting acceleration in each of the X-axis, Y-axis and Z-axis directions, and the like. Is implemented. Further, on the side surface of the substrate 2320, an angular velocity sensor 2340x for detecting the angular velocity around the X axis and an angular velocity sensor 2340y for detecting the angular velocity around the Y axis are mounted. Then, for example, the physical quantity sensor of the present invention can be used as the acceleration sensor 2350.

Further, a control IC 2360 is mounted on the lower surface of the substrate 2320. The control IC 2360 is an MCU (Micro Controller Unit) and controls each part of the inertial measurement unit 2000. The storage unit stores a program that defines the order and contents for detecting acceleration and angular velocity, a program that digitizes the detection data and incorporates it into packet data, and accompanying data. In addition, a plurality of other electronic components are mounted on the substrate 2320.

<Sixth Embodiment>
FIG. 42 is a block diagram showing the entire system of the mobile positioning device as an electronic device according to the sixth embodiment. FIG. 43 is a diagram showing the operation of the mobile positioning device shown in FIG. 42.

The mobile body positioning device 3000 shown in FIG. 42 is a device that is attached to a moving body and used to perform positioning of the moving body. The moving body is not particularly limited and may be any of bicycles, automobiles, motorcycles, trains, airplanes, ships, etc., but in the present embodiment, when a four-wheeled vehicle, particularly an agricultural tractor, is used as the moving body. Will be described.

The mobile positioning device 3000 includes an inertial measurement unit 3100 (IMU), an arithmetic processing unit 3200, a GPS receiving unit 3300, a receiving antenna 3400, a position information acquisition unit 3500, a position synthesis unit 3600, and a processing unit 3700. , A communication unit 3800, and a display unit 3900. As the inertial measurement unit 3100, for example, the above-mentioned inertial measurement unit 2000 can be used.

The inertial measurement unit 3100 has a 3-axis acceleration sensor 3110 and a 3-axis angular velocity sensor 3120. The arithmetic processing unit 3200 receives the acceleration data from the acceleration sensor 3110 and the angular velocity data from the angular velocity sensor 3120, performs inertial navigation arithmetic processing on these data, and outputs inertial navigation positioning data including the acceleration and attitude of the moving body. do.

Further, the GPS receiving unit 3300 receives a signal from a GPS satellite with the receiving antenna 3400. Further, the position information acquisition unit 3500 outputs GPS positioning data representing the position (latitude, longitude, altitude), speed, and direction of the mobile positioning device 3000 based on the signal received by the GPS reception unit 3300. The GPS positioning data also includes status data indicating a reception status, reception time, and the like.

The position synthesis unit 3600 is based on the inertial navigation positioning data output from the arithmetic processing unit 3200 and the GPS positioning data output from the position information acquisition unit 3500, and the position of the moving body, specifically, the position of the moving body on the ground. Calculate whether you are traveling at a position. For example, even if the position of the moving body included in the GPS positioning data is the same, as shown in FIG. 43, if the posture of the moving body is different due to the influence of the inclination θ of the ground or the like, the position of the moving body is different. It means that the moving body is running. Therefore, the accurate position of the moving body cannot be calculated only from the GPS positioning data. Therefore, the position synthesizing unit 3600 calculates which position on the ground the moving body is traveling by using the inertial navigation positioning data.

The position data output from the position synthesis unit 3600 is subjected to predetermined processing by the processing unit 3700 and displayed on the display unit 3900 as a positioning result. Further, the position data may be transmitted to an external device by the communication unit 3800.

<7th Embodiment>
FIG. 44 is a perspective view showing a moving body according to the seventh embodiment.

The automobile 1500 shown in FIG. 44 is an automobile to which the moving body of the present invention is applied. In this figure, the vehicle 1500 includes at least one system 1510 of an engine system, a braking system and a keyless entry system. Further, the automobile 1500 has a built-in physical quantity sensor 1, and the physical quantity sensor 1 can detect the posture of the vehicle body. The detection signal of the physical quantity sensor 1 is supplied to the control circuit 1502, and the control circuit 1502 can control the system 1510 based on the signal.

As described above, the automobile 1500 as a moving body includes the physical quantity sensor 1 and the control circuit 1502 that controls based on the detection signal output from the physical quantity sensor 1. Therefore, the effect of the physical quantity sensor 1 described above can be enjoyed, and high reliability can be exhibited.

In addition, the physical quantity sensor 1 includes a car navigation system, a car air conditioner, an anti-lock braking system (ABS), an airbag, a tire pressure monitoring system (TPMS), an engine control, and a hybrid vehicle. It can be widely applied to electronic control units (ECUs) such as battery monitors for electric vehicles and electric vehicles. Further, the moving body is not limited to the automobile 1500, and for example, an unmanned vehicle such as a railroad vehicle, an airplane, a helicopter, a rocket, an artificial satellite, a ship, an AGV (automated guided vehicle), an elevator, an escalator, a bipedal walking robot, or a drone. It can also be applied to airplanes, radio-controlled models, railway models, and other toys.

Although the physical quantity sensor, the electronic device, and the mobile body of the present invention have been described above based on the illustrated embodiment, the present invention is not limited to this, and the configuration of each part is an arbitrary configuration having the same function. Can be replaced with one. Further, any other constituents may be added to the present invention. In addition, the above-described embodiments may be combined as appropriate.

Further, in the above-described embodiment, the configuration in which the physical quantity sensor detects the acceleration has been described, but the physical quantity detected by the physical quantity sensor is not particularly limited, and may be, for example, angular velocity, pressure, or the like.

1 ... Physical quantity sensor, 2 ... Substrate, 21 ... Recessed, 211 ... 1st recess, 212 ... 2nd recess, 22 ... Mount part, 25, 26, 27 ... Groove part, 3 ... Element part, 30 ... Through hole, 31 ... Fixed part, 32 ... Movable body, 321 ... 1st mass part, 322 ... 2nd mass part, 322A ... Base part, 322B ... Torque generating part, 323 ... Connecting part, 324, 325 ... Opening, 33 ... Support beam, 5 ... Lid, 51 ... concave, 59 ... glass frit, 6, 61, 62 ... protrusion, 75, 76, 77 ... wiring, 8 ... electrode, 81 ... first fixed electrode, 811 ... notch, 82 ... second fixed electrode , 821 ... notch, 83 ... dummy electrode 1200 ... smartphone, 1208 ... display, 1210 ... control circuit, 1500 ... automobile, 1502 ... control circuit, 1510 ... system, 2000 ... inertial measurement unit, 2100 ... outer case, 2110 ... Screw hole, 2200 ... Joining member, 2300 ... Sensor module, 2310 ... Inner case, 2311 ... Recess, 2312 ... Opening, 2320 ... Board, 2330 ... Connector, 2340x, 2340y, 2340z ... Angular velocity sensor, 2350 ... Accelerometer, 2360 ... control IC, 3000 ... mobile positioning device, 3100 ... inertial measurement unit, 3110 ... acceleration sensor, 3120 ... angular velocity sensor, 3200 ... arithmetic processing unit, 3300 ... GPS receiving unit, 3400 ... receiving antenna, 3500 ... position information acquisition unit 3,600 ... position synthesis unit, 3700 ... processing unit, 3800 ... communication unit, 3900 ... display unit, Az ... acceleration, Ca, Cb ... capacitance, Dx, Dy ... interval, J ... rotation axis, P ... electrode pad, Q ... void, Q1 ... first void, Q2 ... second void, R1 ... first region, R2 ... second region, S ... storage space, S0 ... length, S1 ... spacing, Wx, Wy ... width, θ ... Inclined

Claims (11)

When the three directions orthogonal to each other are the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body penetrates in the third direction, and has a first region having a plurality of through holes having a square opening shape when viewed from the third direction, and a second region having no through holes. Have and
The length of one side of the through hole is S0,
When the distance between adjacent through holes is S1,
A physical quantity sensor characterized in that at least one of the length of the second region in the first direction and the length of the second region is S0 + 2 × S1 or more. When the three directions orthogonal to each other are the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body has a first region having a plurality of through holes penetrating in the third direction and having a circular opening shape when viewed from the third direction, and a second region having no through holes. Have and
The radius of the through hole is _ro ,
When half the distance between the centers of the through hole adjacent to the r _c,
A physical quantity sensor characterized in that at least one of the length of the second region in the first direction and the length of the second region is 4 × r _{c −} 2 × r _{0 or more.} When the three directions orthogonal to each other are the first direction, the second direction, and the third direction,
With the board
It has a movable body that faces the substrate in the third direction with a gap between the substrate and is displaced in the third direction with respect to the substrate.
The movable body has a first region having a plurality of through holes penetrating in the third direction and having a polygonal opening shape when viewed from the third direction, and a second region having no through holes. Have,
The square root of the area of the through hole is S0,
When the distance between the adjacent through holes in the first direction and the distance in the second direction are added and divided by 2, the value is S1.
A physical quantity sensor characterized in that at least one of the length of the second region in the first direction and the length of the second region is S0 + 2 × S1 or more. The area of the second region, the physical quantity sensor according to claim 1 or 3 is ^{36 × S0 2 + 64 × S1} 2 + 96 × S0 × S1 or greater. The physical quantity sensor according to any one of claims 1 to 4, wherein the area of the second region is 17100 μm ^{2 or less.} The first region is

The physical quantity sensor according to any one of claims 1 to 5, which satisfies the relationship of.
However,
The length of the through hole in the third direction is H,
The length of 1/2 of the length of the movable body along the first direction is a,
The length of the movable body along the second direction is L,
The length of the gap in the third direction is h,
The viscous resistance of the gas in the void is μ,
When the damping generated in the movable body is C,

In the above formula (1),

Let C be Cmin when the condition is satisfied. A fixed portion fixed to the substrate and
It has a support beam that connects the movable body and the fixed portion and forms a rotation axis along the first direction.
The movable body can be displaced around the rotation axis, and has a first mass portion located on one side of the second direction with respect to the rotation axis in a plan view from the third direction. It has a second mass part, which is located on the other side and whose rotational moment around the rotation axis is larger than the first mass part.
The second mass portion is located at a first portion symmetrical with respect to the first mass portion with respect to the rotation axis and distal to the rotation axis with respect to the first portion, and the second mass portion is located with respect to the rotation axis. It has one part by mass and an asymmetrical second part.
The physical quantity sensor according to claim 6, wherein the first mass portion and the first region located in the first portion satisfy C ≦ 1.5 × Cmin, respectively. The physical quantity sensor according to claim 7, wherein the first region located in the second portion satisfies C ≦ 2.5 × Cmin. The physical quantity sensor according to any one of claims 1 to 8, which has a protrusion protruding from the substrate toward the movable body and having a protrusion overlapping the second region in a plan view from the third direction. The physical quantity sensor according to any one of claims 1 to 9,
An electronic device including a control circuit that performs control based on a detection signal output from the physical quantity sensor. The physical quantity sensor according to any one of claims 1 to 9,
A mobile body including a control circuit that controls based on a detection signal output from the physical quantity sensor.

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