JP7152752B2 - angular acceleration sensor - Google Patents

Description

The present invention relates to angular acceleration sensors.

Angular acceleration sensors that detect angular acceleration have been miniaturized due to recent advances in MEMS (Micro Electro Mechanical Systems) technology. It is spreading rapidly.

In recent years, as shown in Non-Patent Documents 1 and 2, angular acceleration sensors using fluid in an annular ring have been proposed. The angular acceleration sensor has a piezoresistive cantilever that traverses the fluid path. As the fluid flows through the path, the cantilever is pushed and deformed by the fluid. The cantilever changes its electric resistance value according to the amount of deformation. Angular acceleration sensors with such a structure are attracting attention because they are less affected by acceleration and less sensitive to other axes, and are capable of detection in a high-frequency region.

C.Andreou, Y.Pahitas, and J.Georgiou, “Bio-Inspired Micro-Fluidic Angular-Rate Sensor for Vestibular Prostheses”, Sensors, vol.14, 13173-13185, 2014. S.Cheng, M.Fu, M.Wang, L.Ming, H.Fu, and T.Wang, “Dynamic Fluid in a Porous Transducer-Based Angular Accelerometer”, Sensors, vol.17, 416, 2017.

However, when the angular acceleration sensors of Non-Patent Documents 1 and 2 are miniaturized, the sensitivity decreases in proportion to the square of the size. Furthermore, the other axis sensitivity relatively increases as the sensitivity decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an angular acceleration sensor capable of realizing a reduction in size and a high sensitivity.

An angular acceleration sensor according to the present invention is an angular acceleration sensor for detecting angular acceleration about a predetermined detection axis. The angular acceleration sensor is formed in a tubular shape and extends around the detection axis and is connected at both ends. and a filling material that is filled in the inside of the channel part and whose movement is restricted by the cantilever part. Detecting the angular acceleration.

According to the angular acceleration sensor of the present invention, miniaturization and high sensitivity can be achieved.

1 is a schematic diagram of an angular acceleration sensor of a first embodiment; FIG. 1 is an exploded perspective view of an angular acceleration sensor according to a first embodiment; FIG. It is a top view of a detection part. FIG. 4 is a cross-sectional view of the detection unit taken along line AA of FIG. 3; 4 is a graph showing response results to angular acceleration of the angular acceleration sensor of the first embodiment; 4 is a graph showing frequency response and multiaxial sensitivity of the angular acceleration sensor of the first embodiment; It is a schematic diagram of an angular acceleration sensor of a second embodiment. FIG. 8 is an exploded perspective view of an angular acceleration sensor according to a second embodiment; It is a side view of the angular acceleration sensor of 2nd Embodiment. It is an explanatory view explaining a Wheatstone bridge circuit. It is an explanatory view explaining an operation of an angular acceleration sensor of a 2nd embodiment. FIG. 11(a) is a diagram of the angular acceleration sensor viewed from the z-axis. FIG. 11(b) is a diagram of the angular acceleration sensor viewed from the x-axis. FIG. 11(c) is a diagram of the angular acceleration sensor viewed from the y-axis. 9 is a graph showing response results to angular acceleration of the angular acceleration sensor of the second embodiment; 9 is a graph showing frequency response and multiaxial sensitivity of the angular acceleration sensor of the second embodiment; It is explanatory drawing explaining the modification of a channel part. It is explanatory drawing explaining another modification of a channel part.

[First embodiment]
FIG. 1 is a schematic diagram of an angular acceleration sensor 10. As shown in FIG. Angular acceleration sensor 10 is used to detect angular acceleration about a predetermined detection axis. In the following description, the detection axis for detecting angular acceleration by the angular acceleration sensor 10 is assumed to be the z-axis out of the mutually orthogonal x-axis, y-axis, and z-axis.

As shown in FIG. 1, the angular acceleration sensor 10 includes a package 11, a sensor section 12, and a circuit board 13. As shown in FIG. The package 11, the sensor section 12, and the circuit board 13 are integrated using screws, for example.

The package 11 is formed by a cover plate 11a and a support plate 11b. The cover plate 11a and the support plate 11b are flat plates. In this example, the planar shape of the cover plate 11a and the support plate 11b is substantially rectangular with chamfered corners. The cover plate 11a and the support plate 11b are made of metal, resin, or the like, for example.

The sensor unit 12 detects angular acceleration around the detection axis by a cantilever unit 15 (see FIG. 2), which will be described later. The sensor section 12 is arranged between the cover plate 11a and the support plate 11b. In the following description, the lid plate 11a side is the upper side, and the support plate 11b side is the lower side. The sensor part 12 has a channel part 14 which is formed in a tubular shape, surrounds the detection axis and is connected at both ends. Although details will be described later, in the case of this embodiment, the channel portion 14 is spirally wound on a plane orthogonal to the detection axis.

The circuit board 13 is arranged below the sensor section 12 and electrically connected to the sensor section 12 via a cable (not shown). The circuit board 13 has a detection circuit that outputs a detection signal according to the angular acceleration detected by the sensor section 12 . As the detection circuit, for example, an amplifier circuit, a bridge circuit, or the like is provided.

The configuration of the angular acceleration sensor 10 will be described in detail with reference to FIG. Angular acceleration sensor 10 includes channel portion 14 , sensing portion 16 having cantilever portion 15 , and filler 17 .

The channel portion 14 has a first channel 21 and a second channel 22 . The first channel 21 and the second channel 22 are provided at different positions in the axial direction of the detection axis. In this example, a first channel 21 is provided on the upper side and a second channel 22 is provided on the lower side.

The first channel 21 is spirally wound on a plane orthogonal to the detection axis. The second channel 22 is also spirally wound on a plane orthogonal to the detection axis. The winding directions of the first channel 21 and the second channel 22 are opposite to each other. In this example, the winding direction of the first channel 21 is counterclockwise from the inner end to the outer end. Accordingly, the winding direction of the second channel 22 is clockwise from the inner end to the outer end. The number of turns of the first channel 21 and the second channel 22 corresponds to the number of turns of the channel portion 14 .

The first channel 21 is formed, for example, by forming a spiral groove on the surface of the Si substrate by photolithography and DRIE (Deep Reactive Ion Etching), and attaching a glass substrate from above so as to cover the groove. . The method of forming the second channel 22 is the same as that of the first channel 21 except that the spiral groove is formed in a direction opposite to that of the first channel 21, so the description thereof will be omitted.

A first channel 21 is provided in the upper housing 23 . The upper housing 23 has an inner through hole 23a provided at a position corresponding to the inner end of the first channel 21 and an outer through hole 23b provided at a position corresponding to the outer end of the first channel 21. .

A second channel 22 is provided in the lower housing 24 . The lower housing 24 has an inner through hole 24a provided at a position corresponding to the inner end of the second channel 22 and an outer through hole 24b provided at a position corresponding to the outer end of the second channel 22. .

The first channel 21 and the second channel 22 are connected at their inner ends via an inner through hole 23a and an inner through hole 24a, and are connected at their outer ends via an outer through hole 23b and an outer through hole 24b. is doing. Thereby, the inside of the first channel 21 and the inside of the second channel 22 communicate with each other.

The detector 16 is arranged between the upper housing 23 and the lower housing 24 . The cantilever portion 15 of the detection portion 16 is arranged between the outer through hole 23b and the outer through hole 24b. Thereby, the cantilever portion 15 is provided across the channel portion 14 .

The detection unit 16 will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a plan view of the detection unit 16. FIG. 4 is a cross-sectional view taken along line AA of FIG. 3. FIG. The detection unit 16 is provided on a substrate 27 having an opening 26 so as to close the opening 26 (FIG. 4). The detection section 16 is formed of a Si layer 31 , an insulating layer 32 , an upper Si layer 33 , a piezoresistive layer 34 and an electrode layer 35 . A cantilever portion 15 is formed by the upper Si layer 33 and the piezoresistive layer 34 . It should be noted that illustration of the substrate 27 is omitted in FIG.

The detection part 16 has a gap 37 penetrating in the thickness direction. The thickness direction of the detection section 16 is along the stacking direction of the Si layer 31 , the insulating layer 32 , the upper Si layer 33 , the piezoresistive layer 34 and the electrode layer 35 . The gap 37 connects one side and the other side of the cantilever portion 15 .

The gap 37 is formed to have a size (width) that restricts the flow of the filler 17, which will be described later. The width of gap 37 is preferably about 100 times or less the mean free path of the molecules of filler 17 . This is because if the width of the gap 37 is larger than 100 times the mean free path of the molecules of the filler 17, leakage of the filler 17 occurs in the gap 37 and the sensitivity is lowered.

A gap 37 is formed at the outer edge of the cantilever portion 15 (FIG. 3). The cantilever portion 15 is formed by defining the upper Si layer 33 and the piezoresistive layer 34 with a gap 37 .

The cantilever portion 15 has a flat pressure receiving portion 38 and a hinge portion 39 integrally formed on one side surface of the pressure receiving portion 38. The hinge portion 39 is a fixed end and the pressure receiving portion 38 is a free end. ing. The cantilever portion 15 is elastically deformed around the hinge portion 39 due to the pressure difference between the pressure generated on one side and the pressure generated on the other side.

The filling material 17 fills the inside of the first channel 21 and the inside of the second channel 22, that is, the inside of the channel portion 14 (see FIG. 2). Filler 17 is restricted in movement by cantilevered portion 15 across channel portion 14 . A fluid or gel is used as the filler 17 . A fluid is a liquid or a gas. As the liquid, for example, water, silicon oil, ionic liquid, etc. are used. As the gas, for example, carbon dioxide, xenon, or the like is used. Examples of gels that can be used include collagen and agarose gels.

When the angular acceleration sensor 10 configured as described above rotates in the direction of the arrow shown in FIG. As a result, the filling material 17 rotates together with the channel portion 14 . A force required to rotate the filling material 17 integrally with the channel part 14 , that is, the inertial force of the filling material 17 acts on the cantilever portion 15 . At this time, the pressure ΔP generated in the cantilever portion 15 is represented by the following formula (1).

ρ is the density of the filler 17; α _z is the angular acceleration around the z-axis as the detection axis. r is the radius of the channel portion 14 at a given position. r is represented by the following formula (2).
r=r ₀ (1−θ/θ ₀ ) (2)

r ₀ is the radius at the outer end of the channel portion 14; θ is an angle at a predetermined position of the channel portion 14 . θ ₀ is the angle that determines the number of turns of channel portion 14 . θ is in the range of 0<θ<θ ₀ −π. θ is the angle formed by a straight line connecting the inner end and the outer end of the channel portion 14 and a straight line connecting the inner end of the channel portion 14 and a point at a predetermined position on a plane orthogonal to the detection axis. expressed. For example, θ ₀ is 2π when the number of turns of the channel portion 14 is 1, and is 50π when the number of turns of the channel portion 14 is 25.

The cantilever portion 15 is elastically deformed around the hinge portion 39 by the applied pressure ΔP. Then, the electric resistance value of the cantilever portion 15 changes according to the amount of deformation. The angular acceleration sensor 10 can measure the pressure ΔP by measuring the resistance change rate of the cantilever portion 15, thereby measuring the angular acceleration α.

Since the inertial force of the filler 17 increases in proportion to the number of turns of the channel portion 14, the angular acceleration sensor 10 can be made compact and highly sensitive.

An angular acceleration sensor 10 having a cantilever portion 15 with a length of 80 μm, a width of 80 μm, and a thickness of 0.15 μm was actually manufactured, and the response to angular acceleration around the detection axis was measured. The width of the gap 37 was set to 1 μm. The channel portion 14 has a conduit width of 400 μm and a conduit height of 500 μm, and each of the first channel 21 and the second channel 22 has 24 turns. Air (ρ=1.0 kg/m ³ ) was used as the filler 17 .

FIG. 5 shows the response to angular acceleration when the angular acceleration sensor 10 is fixed on a rotary table (not shown) and driven by a sine wave with an amplitude of π/2 [rad/s] and 1 [Hz]. In FIG. 5, the vertical axis is the resistance change rate ΔR/R, and the horizontal axis is the angular acceleration α. From FIG. 5, it can be confirmed that the angular acceleration sensor 10 linearly responds to the angular acceleration.

FIG. 6 shows the result of measuring the frequency response of the rotational motion of the angular acceleration sensor 10 . In FIG. 6, the vertical axis is angular acceleration sensitivity and the horizontal axis is frequency. In FIG. 6, the dotted line indicates the sensitivity to angular acceleration α _z about the z-axis, the dashed line indicates the sensitivity to angular acceleration α _x about the x-axis, and the solid line indicates the sensitivity to angular acceleration α _y about the y-axis. It can be confirmed from FIG. 6 that the angular acceleration sensor 10 responds to the angular acceleration about the z-axis with a constant sensitivity from 1 Hz to 100 Hz. Further, the angular acceleration sensor 10 was placed at an angle of 90° with respect to the rotary table, and the angular acceleration sensitivity about the x-axis and the angular acceleration sensitivity about the y-axis were evaluated. From FIG. 6, it has been confirmed that the angular acceleration sensitivity about the x-axis and the angular acceleration sensitivity about the y-axis are about 1/100 of the angular acceleration sensitivity about the z-axis.

[Second embodiment]
An angular acceleration sensor 40 shown in FIG. 7 differs from that of the first embodiment in the configuration of a channel portion 42 . Channel portion 42 has a third channel 43 and a fourth channel 44 . In this figure, the third channel 43 is provided on the upper side and the fourth channel 44 is provided on the lower side. In the following description, description of the same configuration as that of the first embodiment is omitted.

As shown in FIG. 8, third channel 43 is formed by upper housing 46 and lower housing 47 . The upper housing 46 and the lower housing 47 are made of aluminum, for example. The upper housing 46 has a semicircular groove 49, a through hole 50 provided at one end of the groove 49, a through hole 51 provided at the other end of the groove 49, and a lid member 52 closing the groove 49. . A groove 49 is formed in the upper surface of the upper housing 46 . The lower housing 47 has a semicircular groove 53 , a through hole 54 provided at one end of the groove 53 , a through hole 55 provided at the other end of the groove 53 , and a lid member 56 closing the groove 53 . . The lid member 56 is made of glass, for example. A groove 53 is formed in the lower surface of the lower housing 47 . The through holes 50 and 54 are connected, and the through holes 51 and 55 are connected. The third channel 43 has a helically wound structure along the axial direction of the detection axis by connecting the upper groove 49 and the lower groove 53 . In this figure, the number of turns of the third channel 43 is one. A detection portion 59 having a cantilever portion 58 is arranged between the through hole 50 and the through hole 54 . The cantilever portion 58 has a configuration similar to that of the cantilever portion 15 . The detector 59 has the same configuration as the detector 16 .

Fourth channel 44 is formed by upper housing 60 and lower housing 61 . The upper housing 60 and the lower housing 61 are made of aluminum, for example. The upper housing 60 has a semicircular groove 62, a through hole 63 provided at one end of the groove 62, a through hole 64 provided at the other end of the groove 62, and a lid member 65 closing the groove 62. . A groove 62 is formed in the upper surface of the upper housing 60 . The lower housing 61 has a semicircular groove 66, a through hole 67 provided at one end of the groove 66, a through hole 68 provided at the other end of the groove 66, and a lid member 69 closing the groove 66. . The lid member 69 is made of glass, for example. A groove 66 is formed in the lower surface of the lower housing 61 . The through holes 63 and 67 are connected, and the through holes 64 and 68 are connected. Thus, the fourth channel 44 has a spirally wound structure along the axial direction of the detection axis by connecting the upper groove 62 and the lower groove 66 . In this figure, the fourth channel 44 has one turn. A detection portion 71 having a cantilever portion 70 is arranged between the through hole 63 and the through hole 67 . The cantilever portion 70 has a configuration similar to that of the cantilever portion 15 . The detection unit 71 has a configuration similar to that of the detection unit 16 .

As shown in FIG. 9, groove 49 of third channel 43 is positioned above groove 66 of fourth channel 44 . The groove 53 of the third channel 43 is arranged above the groove 62 of the fourth channel 44 . That is, the channel part 42 has a third channel 43 and a fourth channel 44 which are provided at different positions in the axial direction of the detection axis and which are symmetrical with respect to the plane P orthogonal to the detection axis. The number of turns of channel portion 42 corresponds to the number of turns of third channel 43 and fourth channel 44 . FIG. 9 is a side view of a portion of the angular acceleration sensor 40, and is a view of the angular acceleration sensor 40 viewed from the surface side (see FIG. 8) on which the cantilever portions 58 and 70 are provided in the x-axis direction.

In the second embodiment, the circuit board 13 has a Wheatstone bridge circuit 72 shown in FIG. The Wheatstone bridge circuit 72 outputs the difference value between the electrical resistance value of the cantilever portion 58 provided in the third channel 43 and the electrical resistance value of the cantilever portion 70 provided in the fourth channel 44 as a detection signal. .

The action of the angular acceleration sensor 40 will be described with reference to FIG. FIG. 11A is a diagram of the angular acceleration sensor 40 viewed from above in the z-axis direction. FIG. 11(b) is a view of the angular acceleration sensor 40 as seen from the surface side (see FIG. 8) on which the cantilever portions 58 and 70 are provided in the x-axis direction. FIG. 11(c) is a view of the angular acceleration sensor 40 as seen from the side on which the grooves 53 and 62 are provided in the y-axis direction. In FIG. 11, α _z indicates the angular acceleration about the z-axis, α _x indicates the angular acceleration about the x-axis, and α _y indicates the angular acceleration about the y-axis. 11, only the portion of the third channel 43 is shown, and the portion of the fourth channel 44 is omitted.

When the angular acceleration sensor 40 rotates in the arrow direction shown in FIG. ΔP is generated. A pressure ΔP generated in the cantilever portions 58 and 70 is represented by the following formula (3). r is the radius of the ring structure, ie, the channel portion 42 shown in FIG. 11(a).
ΔP=2π・ρ・r ²・_αz (3)

Since the cantilever portion 58 is elastically deformed upward and the cantilever portion 70 is elastically deformed downward, the detection signal output from the Wheatstone bridge circuit 72 is doubled. That is, the angular acceleration sensor 40 has doubled angular acceleration sensitivity about the z-axis.

When the angular acceleration sensor 40 rotates in the direction of the arrow shown in FIG. 11B, that is, around the x-axis, the cantilever portions 58 and 70 do not elastically deform, so no detection signal is output. This is because there is no ring structure that generates an inertial force in the filler 17 when it rotates around the x-axis. Therefore, the angular acceleration sensor 40 has almost no angular acceleration sensitivity around the x-axis.

On the other hand, when the angular acceleration sensor 40 rotates in the direction of the arrow shown in FIG. transform. The pressure ΔP generated in the cantilever portions 58, 70 can be calculated based on Equation (3). In this case, r is the radius of the ring structure shown in FIG. 11(c). Therefore, the inertial force generated in the filler 17 is smaller than that in the case of rotation about the z-axis. Furthermore, the cantilever portions 58 and 70 elastically deform in the same direction. As a result, the outputs of the cantilever portions 58 and 70 are canceled by the Wheatstone bridge circuit 72 . Therefore, the angular acceleration sensor 40 has almost no angular acceleration sensitivity around the y-axis.

Since the inertial force of the filler 17 increases in proportion to the number of turns of the channel portion 42, the angular acceleration sensor 40 can achieve miniaturization and high sensitivity in the same manner as the angular acceleration sensor 10. FIG. Further, the angular acceleration sensor 40 doubles the output of the detection axis and cancels the output of the other axes, so that the sensitivity can be further improved.

Actually, the angular acceleration sensor 40 having the radius of the channel portion 42 of 17.5 mm was manufactured, and the response to the angular acceleration around the detection axis was measured. The channel portion 42 has a width of 2 mm and a height of 2 mm. Pure water (ρ=1000 kg/m ³ ) was used as the filler 17 . The cantilever portions 58 and 70 are 100 μm long, 80 μm wide and 0.3 μm thick. A gap 37 between the cantilever portions 58 and 70 was set to 1 μm.

FIG. 12 shows the response to angular acceleration when the angular acceleration sensor 40 is fixed on a turntable (not shown) and driven by a sine wave with an amplitude of π/2 [rad/s] and 1 [Hz]. In FIG. 12, the vertical axis is the resistance change rate ΔR/R, and the horizontal axis is the angular acceleration α. From FIG. 12, it can be confirmed that the angular acceleration sensor 40 linearly responds to the angular acceleration.

FIG. 13 shows the result of measuring the frequency response of the rotational motion of the angular acceleration sensor 40 . In FIG. 13, the vertical axis is angular acceleration sensitivity and the horizontal axis is frequency. In FIG. 13, the dotted line indicates the sensitivity to angular acceleration α _z about the z-axis, and the solid line indicates the sensitivity to angular acceleration α _y about the y-axis. Angular acceleration sensitivity about the x-axis is not shown. From FIG. 13, it can be confirmed that the angular acceleration sensor 40 responds with constant sensitivity from 0.1 Hz to 100 Hz to the angular acceleration around the z-axis. Furthermore, the angular acceleration sensor 40 was placed at an angle of 90° with respect to the rotary table, and the angular acceleration sensitivity around the y-axis was evaluated. From FIG. 13, it was confirmed that the angular acceleration sensitivity around the y-axis is about 1/100 of the angular acceleration sensitivity around the z-axis.

The present invention is not limited to the above embodiments, and can be appropriately modified within the scope of the present invention.

For example, the configuration of channel portion 14 and the configuration of channel portion 42 may be combined. For example, in the angular acceleration sensor 10 of the first embodiment, in addition to the channel portion 14, the channel portion is provided at a different position in the axial direction of the detection axis and is symmetrical with respect to the plane orthogonal to the detection axis. may be provided.

Two or more sets of the first channel 21 and the second channel 22 may be provided in the angular acceleration sensor 10 of the first embodiment.

Modifications of the channel portion will be described below. The channel part may be composed of an annular body and a fifth channel spirally provided on the outer peripheral surface of the annular body. The annular body is, for example, a torus shape whose central curve is a circle (large circle) with a radius R and whose cross-sectional shape perpendicular to the circumferential direction is a circle (small circle) with a radius r. The fifth channel circulates around the detection axis while spirally winding along the annular body. That is, the fifth channel is helically wound around the winding axis that goes around the detection axis. The fifth channel is connected at both ends to form a closed curve.

The shape of the fifth channel is represented by the following equation (4) representing the position vector c of a point at a given position on the fifth channel.

R is the radius of the great circle of the toroid. r is the radius of the small circle of the toroid. m is the number of turns the fifth channel spirally winds. n is the number of revolutions of the fifth channel around the detection axis and corresponds to the number of turns of the channel section. m and n are relatively prime. The parameter θ is in the range 0≦θ≦2π.

The channel portion is not limited to having a configuration in which the fifth channel is provided in the annular body, and may have the fifth channel represented by Equation (4). That is, the channel part may have only the fifth channel represented by Equation (4) without having the annular body. If there is no annular body, a torus-shaped space is formed inside the fifth channel. In formula (4), the radius of the large circle in the torus-shaped space is R, and the radius of the small circle in the torus-shaped space is r.

A specific example of a channel portion having a configuration in which a fifth channel is provided in an annular body will be described below with reference to FIGS. 14 and 15. FIG.

FIG. 14 is a schematic diagram of a channel section 75 having a fifth channel 74 when r=0.1R, n=3 and m=29 in equation (4). In FIG. 14, illustration of the annular body is omitted. In FIG. 14, the fifth channel 74 is shown with different shades each time it rotates around the detection axis. FIG. 15 is a schematic diagram of a channel section 77 having a fifth channel 76 when r=0.1R, n=5 and m=3 in equation (4). In FIG. 15, illustration of the annular body is omitted. In FIG. 15, the fifth channel 76 is shown with different shades each time it rotates around the detection axis. The channel portion 75 and the channel portion 77 have the same configuration except that n and m are different. The channel portion 75 will be described below, and the description of the channel portion 77 will be omitted.

An example of a method for forming the channel portion 75 will be described. The channel portion 75 is formed, for example, by preparing an annular body (not shown) and a tubular fifth channel 74 and winding the fifth channel 74 around the annular body. The annular body is made of metal, resin, or the like, for example. The fifth channel 74 is tubular, for example, by using a silicone tube. Alternatively, a thick photosensitive film that is cured by irradiation with ultraviolet light is formed by photolithography so as to have the cross-sectional shape of the channel portion 75 , and the channel portion 75 is formed by repeating this process in multiple layers.

An angular acceleration sensor is formed by providing the cantilever portion 15 across the channel portion 75 and filling the inside of the channel portion 75 with the filling material 17 . The operation of the angular acceleration sensor having the channel portion 75 will be described below.

The pressure ΔP generated in the cantilever portion 15 when the angular acceleration sensor having the channel portion 75 makes one rotation about the z-axis shown in FIG. 14 is represented by the following formula (5).

In Expression (5), α indicates an angular acceleration vector. The angular acceleration vector α is represented by the following formula (6).

t denotes the tangent vector of the fifth channel 74; The tangent vector t is represented by the following Equation (7).

(5), α×c represents the angular acceleration experienced by a point at a given location on the fifth channel 74 . −ρ(α×c) represents the inertial force per volume experienced by the filler 17 inside the fifth channel 74 .

According to Equation (5), the angular acceleration sensor having the channel portion 75 has no sensitivity to rotation about the x-axis and rotation about the y-axis, but has sensitivity only to rotation about the z-axis. The sensitivity of the angular acceleration sensor having the channel portion 75 is represented by the density ρ of the filler 17 and the constants n, R, and r that determine the shape of the fifth channel 74 . Therefore, the angular acceleration sensor having the channel portion 75 can achieve miniaturization and high sensitivity.

Similarly to the angular acceleration sensor having the channel portion 75, the angular acceleration sensor having the channel portion 77 also has sensitivity only to rotation around the z-axis. The sensitivity of the angular acceleration sensor having the channel portion 77 is represented by the density ρ of the filler 17 and the constants n, R, and r that determine the shape of the fifth channel 76 . Therefore, the angular acceleration sensor having the channel portion 77 can achieve miniaturization and high sensitivity.

The number of turns of the channel portions 14, 42, 75, 77 may be changed as appropriate. The shape of the channel portions 14, 42, 75, 77 in plan view can be changed as appropriate, and may be rectangular, for example.

10, 40 Angular acceleration sensor 12 Sensor section 13 Circuit board 14, 42, 75, 77 Channel section 15, 58, 70 Cantilever section 16, 59, 71 Detection section 17 Filling material 21 First channel 22 Second channel 37 Gap 43 Second 3rd channel 44 4th channel 74, 76 5th channel

Claims (4)

In an angular acceleration sensor that detects angular acceleration around a predetermined detection axis,
a channel portion which is formed in a tubular shape and which extends around the detection shaft and is connected at both ends;
a cantilever portion extending across the channel portion;
a filling material that is filled inside the channel portion and whose movement is restricted by the cantilever portion;
The channel portion is spirally wound on a plane orthogonal to the detection axis,
An angular acceleration sensor that detects the angular acceleration based on the amount of deformation of the cantilever portion that is deformed by the inertial force of the filler. The channel part has a first channel and a second channel which are provided at different positions in the axial direction of the detection axis and whose winding directions are opposite to each other,
2. The angular acceleration sensor according to claim 1 , wherein the first channel and the second channel are connected at their inner ends and connected at their outer ends. In an angular acceleration sensor that detects angular acceleration around a predetermined detection axis,
a channel portion which is formed in a tubular shape and which extends around the detection shaft and is connected at both ends;
a cantilever portion extending across the channel portion;
a filling material that is filled in the channel portion and whose movement is restricted by the cantilever portion;
with
The channel portion has a spirally wound structure along the axial direction of the detection axis, and is provided at different positions in the axial direction of the detection axis. having a third channel and a fourth channel that are plane symmetrical;
The cantilever portion is provided in each of the third channel and the fourth channel ,
An angular acceleration sensor that detects the angular acceleration based on the amount of deformation of the cantilever portion that is deformed by the inertial force of the filler . In an angular acceleration sensor that detects angular acceleration around a predetermined detection axis,
a channel portion which is formed in a tubular shape and which extends around the detection shaft and is connected at both ends;
a cantilever portion extending across the channel portion;
a filling material that is filled in the channel portion and whose movement is restricted by the cantilever portion;
with
The channel portion has a fifth channel spirally wound around a winding axis that surrounds the detection axis ,
An angular acceleration sensor that detects the angular acceleration based on the amount of deformation of the cantilever portion that is deformed by the inertial force of the filler .

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