JP2009085807A - Pressure sensor and pressure-measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem with a conventional pressure sensor wherein pressure cannot be detected without an effect of acceleration. <P>SOLUTION: A fraction of change Δf<SB>1</SB>of the resonance frequency of a first doublet tuning fork oscillator 40 and a fraction of change Δf<SB>2</SB>of the resonance frequency of a second doublet tuning fork oscillator 50 by an inertial force generated by an acceleration can be offset because the direction of the change is opposite. A fraction of change Δfp<SB>1</SB>of the resonance frequency of the first doublet tuning fork oscillator 40 and a fraction change Δfp<SB>2</SB>of the resonance frequency of the second doublet tuning fork oscillator 50 by a pressure Fp of outside of a closed space 90 can be distinguished from the fraction of change Δf<SB>1</SB>of the resonance frequency of a first doublet tuning fork oscillator 40 and a fraction of change Δf<SB>2</SB>of the resonance frequency of a second doublet tuning fork oscillator 50 by the inertial force generated by an acceleration described above because the direction of the change is the same. Therefore, from the half of the sum of the resonance frequency (fp+Δf<SB>1</SB>) of the first doublet tuning fork oscillator 40 and the resonance frequency (fp-Δf<SB>2</SB>) of the second doublet tuning fork oscillator 50, a pressure sensor 1 can detect the pressure Fp of outside of the closed space 90 by eliminating the effect by acceleration. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure sensor and a pressure measurement device including a pair of diaphragm portions and a double tuning fork vibrating piece joined to each diaphragm portion.

  Conventionally, a pressure sensitive element (hereinafter referred to as a double tuning fork vibrating piece) is disposed in an internal space formed by stacking a pair of piezoelectric diaphragms (hereinafter referred to as diaphragm portions). Are referred to as pressure sensors) (see, for example, Patent Document 1). In this pressure sensor, the inner bottom surfaces of the opposing diaphragm portions are connected to each other by a force transmission column, and both ends (hereinafter referred to as a base portion) of the double tuning fork vibrating piece are fixed to the inner bottom surface of one diaphragm portion. The pressure sensor is installed so that the outer surface of one diaphragm portion is exposed to the measured body at the measured pressure P1, and the outer surface of the other diaphragm portion is exposed to the compared body at the comparative pressure P2. When the pressures acting on both outer surfaces are the same (P1 = P2), the pressure sensor is not deformed. When the pressures acting on both outer surfaces are different (P1> P2 or P1 <P2), the pressure sensor is deformed. Specifically, the center of the pair of diaphragm portions is pushed out to the side where the pressure is small, and the pair of diaphragm portions is thereby curved. The double tuning fork vibrating piece whose base is fixed to one diaphragm portion bends according to the curvature of the diaphragm portion. When the diaphragm portion is curved so that the inner bottom surface of the diaphragm portion to which the double tuning fork vibrating piece is fixed is concave, a compressive force acts on the double tuning fork vibrating piece in a direction crossing the vibration direction of the vibrating arm portion. In addition, when the diaphragm portion is curved so that the inner bottom surface of the diaphragm portion to which the double tuning fork vibrating piece is fixed is convex, a tensile force acts on the double tuning fork vibrating piece in a direction crossing the vibration direction of the vibrating arm portion. . Here, the resonance frequency of the double tuning fork vibrating piece generally decreases when a compressive force is applied in a direction crossing the vibration direction of the vibrating arm portion of the double tuning fork vibrating piece, and increases when a tensile force is applied. Are known. Therefore, this pressure sensor is based on the resonance frequency of the untwisted double tuning fork vibrating piece, and whether the measured pressure P1 is positive or negative with respect to the comparison pressure P2 depending on whether it is higher or lower than this frequency. It is possible to detect whether the pressure is applied.

JP 2004-132913 A (pages 4 to 7, FIGS. 1 to 6)

  However, not only the pressure but also inertial force generated by acceleration acts on the conventional pressure sensor. The direction in which the inertial force generated by acceleration acts is opposite to the direction in which the pressure sensor receives acceleration. Since the direction in which the pressure sensor receives the acceleration is not constant, the direction in which the inertial force generated by the acceleration acts on the pressure sensor is not constant. Therefore, even if an inertial force is applied to the pressure sensor, the pressure sensor is deformed and the inner bottom surface of the diaphragm portion to which the double tuning fork vibrating piece is fixed is either concave or convex as in the case of pressure. Bend. Therefore, even if the pressure to be measured P1 is detected by the pressure sensor, it cannot be distinguished whether it is due to the pressure acting on the pressure sensor or due to the inertial force generated by the acceleration. That is, the conventional pressure sensor has a problem that pressure cannot be detected without the influence of acceleration.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A pressure sensor according to this application example is bonded to a case portion having opposed circumferential end surfaces and a through hole formed in a central portion, and the entire circumference of one end surface of the case portion. The first joint portion formed, the first thin portion formed inside the first joint portion, the first holding portion formed inside the first thin portion, and the inside of the first holding portion. A first diaphragm portion that is formed and has a first central plate portion that is thinner than a thickness of the first holding portion, and a second joint portion that is joined to the entire circumference of the other end surface of the case portion. A second thin part formed inside the second joint part, a second holding part formed inside the second thin part, and formed inside the second holding part, A second diaphragm portion having a second central plate portion having a thickness thinner than the thickness of the holding portion, and the case portion are formed to face each other. A sealed space formed by the first diaphragm portion and the second diaphragm portion, two first base portions joined to the sealed space side of the first holding portion, and the first central plate portion. A first double tuning fork vibrating piece having a pair of first vibrating arms formed between the two first bases and facing the first diaphragm; and the sealed space of the second holding part Two second base portions joined to each other, and a pair of second vibrating arm portions formed between the two second base portions so as to straddle the second central plate portion, and the second diaphragm portion It has the 2nd double tuning fork vibrating piece which opposes, It is characterized by the above-mentioned.

  According to such a configuration, in the pressure sensor, a sealed space is formed by the case portion and the first diaphragm portion and the second diaphragm portion that are formed to face each other. In addition, an inertial force generated by acceleration received by the pressure sensor and a pressure outside the sealed space act on the pressure sensor.

  The inertial force generated by the acceleration received by the former pressure sensor acts on the inside of the pressure sensor as follows. When the pressure sensor receives the acceleration in the downward direction, the inertial force generated by the acceleration acts on the pressure sensor in the upward direction opposite to the direction of the acceleration. Therefore, the inertial force acts on the first diaphragm portion and the second diaphragm portion in one direction which is the above-described upward direction.

  In the first diaphragm portion, the first thin portion of the first diaphragm portion is directly connected to the first joint portion joined to the case portion, and since it is thin, the inertia force acts, so that the first thin portion is It tilts with the contact point between the first thin portion and the first joint as a fulcrum. The first holding part formed in the first thin part by tilting the first thin part also tilts with the contact point between the first thin part and the first joint as a fulcrum. By tilting the first holding part, the first holding part is displaced and a rotational force is generated starting from the center point of the first holding part. Since the two places of the first holding part where the two first base parts of the first double tuning fork vibrating piece are joined are in a position sandwiching the first central plate part of the first diaphragm part, one place is, for example, a timepiece Around, the other part moves to rotate counterclockwise. In this way, the one part and the other part move so as to rotate in opposite directions. When the two portions of the first holding portion where the two first bases of the first double tuning fork vibrating piece are joined by the rotational force described above approach each other, the first double tuning fork vibrating piece moves in the vibration direction of the first vibrating arm portion. A compressive force acts in the crossing direction. In addition, when the two portions of the first holding portion where the two first base portions of the first double tuning fork vibrating piece are joined away from each other, the first double tuning fork vibrating piece has a direction crossing the vibration direction of the first vibrating arm portion. A tensile force acts on the.

  In addition, the inertial force and the rotational force act on the second diaphragm portion as well as the above-described first diaphragm portion. However, the position of the second double tuning fork vibrating piece with respect to the second diaphragm portion is exactly opposite to the position of the first double tuning fork vibrating piece with respect to the first diaphragm portion. From this, when a compressive force is applied to the second double tuning fork vibrating piece in a direction intersecting the vibration direction of the first vibrating arm portion on the first double tuning fork vibrating piece, A tensile force acts in the crossing direction. The second twin tuning fork vibrating piece intersects the vibration direction of the second vibrating arm when a tensile force acts on the first double tuning fork vibrating piece in a direction intersecting the vibration direction of the first vibrating arm. A compressive force acts in the direction. As described above, when the inertial force generated by the acceleration acts on the pressure sensor, forces in opposite directions act on the first double tuning fork vibrating piece and the second double tuning fork vibrating piece.

  The pressure outside the latter sealed space acts on the inside of the pressure sensor as follows. Unlike the former inertial force, the pressure outside the sealed space, which is a force acting on the pressure sensor, works toward the center point in the sealed space or from the center point toward the outer periphery. Moreover, the 1st diaphragm part and the 2nd diaphragm part are provided facing each other so as to sandwich the sealed space. Therefore, the pressure outside the sealed space acts in opposite directions to the first diaphragm portion and the second diaphragm portion. Further, the position of the first double tuning fork vibrating piece with respect to the first diaphragm and the position of the second double tuning fork vibrating piece with respect to the second diaphragm are opposite to each other as described above. From this, when a compressive force is applied to the second double tuning fork vibrating piece in a direction intersecting the vibration direction of the first vibrating arm portion on the first double tuning fork vibrating piece, A compressive force acts in the crossing direction. The second twin tuning fork vibrating piece intersects the vibration direction of the second vibrating arm when a tensile force acts on the first double tuning fork vibrating piece in a direction intersecting the vibration direction of the first vibrating arm. A tensile force acts in the direction. Thus, when the pressure outside the sealed space acts on the pressure sensor, forces in the same direction act on the first double tuning fork vibrating piece and the second double tuning fork vibrating piece.

  Here, the resonance frequency of the double tuning fork vibrating piece generally decreases when a compressive force is applied in a direction intersecting the vibration direction of the vibrating arm portion of the double tuning fork vibrating piece, and increases when a tensile force is applied. Are known. Therefore, even if the pressure sensor receives acceleration, a change (increase or decrease) of the resonance frequency of the first double tuning fork vibrating piece due to an inertial force generated by the acceleration and a change of the resonance frequency of the second double tuning fork vibration piece. Minutes (increase or decrease) can be offset because the direction of change is the opposite. Since the change in the resonance frequency of the first double tuning fork vibrating piece and the change in the resonance frequency of the second double tuning fork vibrating piece due to the pressure outside the sealed space coincide with each other, It is possible to discriminate between a change in the resonance frequency of the first double tuning fork vibrating piece and a change in the resonance frequency of the second double tuning fork vibrating piece due to the inertial force generated by the above. Therefore, from the sum of the change in the resonance frequency of the first twin tuning fork resonator element and the change in the resonance frequency of the second twin tuning fork resonator element (specifically, half the sum), the pressure sensor is outside the sealed space. The pressure can be approximated. Therefore, in any environment where the acceleration is constant and the environment where the acceleration changes, the pressure sensor can detect the pressure without the influence of the acceleration.

  Application Example 2 The pressure sensor according to the application example is formed so that the first diaphragm portion and the second diaphragm portion facing each other are parallel to each other, and the first double tuning fork vibrating piece and the second double tuning fork are formed. It is preferable that the vibrating piece is formed so as to face in parallel.

  According to such a configuration, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are formed so as to face each other in parallel. It is possible to realize a backed pressure sensor.

  Application Example 3 In the pressure sensor according to the application example, the first holding part is formed at a symmetrical position with respect to the first center of gravity of the first diaphragm part, and the second holding part is the second diaphragm part. The pair of first vibrating arms of the first double tuning fork vibrating piece is formed so as to pass through a straight line connecting the first center of gravity and the second center of gravity. It is preferable that the pair of second vibrating arm portions of the second double tuning fork vibrating piece straddle the second central plate portion so as to pass through the straight line, straddling the first central plate portion.

  According to such a configuration, the first holding portion is formed at a symmetrical position with respect to the first center of gravity of the first diaphragm portion, and the second holding portion is formed at a symmetrical position with respect to the second center of gravity of the second diaphragm portion. Has been. Further, the pair of first vibrating arm portions of the first double tuning fork vibrating piece straddles the first central plate portion so as to pass a straight line connecting the first gravity center and the second gravity center. Further, the pair of second vibrating arm portions of the second double tuning fork vibrating piece straddles the second central plate portion so as to pass through the straight line.

  As a result, the inertial force generated by acceleration and the pressure outside the sealed space act on the first diaphragm portion, and both locations of the first holding portion of the first diaphragm portion (the two first base portions of the first double tuning fork vibrating piece are joined together). ) Move so that they rotate about the same degree toward each other in the opposite direction. From this, a substantially equal compressive force or tensile force acts on the first double tuning fork vibrating piece in a direction intersecting the vibration direction of the first vibrating arm portion. Since a substantially uniform compressive force or tensile force acts on the first double tuning fork vibrating piece, the resonance frequency of the first double tuning fork vibrating piece after the change is stable.

  In addition, the inertia force generated by acceleration and the pressure outside the sealed space act on the second diaphragm portion, and both locations of the second holding portion of the second diaphragm portion (the two second base portions of the second double tuning fork vibrating piece are joined together) ) Move so that they rotate about the same degree toward each other in the opposite direction. For this reason, a substantially equal compressive force or tensile force acts on the second double tuning fork vibrating piece in a direction crossing the vibration direction of the second vibrating arm portion of the second double tuning fork vibrating piece. Since a substantially equal compressive force or tensile force acts on the second double tuning fork vibrating piece, the resonance frequency of the second double tuning fork vibrating piece after the change is stable. Therefore, in any environment where the acceleration is constant and the environment where the acceleration changes, it is possible to detect the pressure with high accuracy by excluding the influence of the acceleration.

  Application Example 4 The pressure sensor according to the above application example is preferably formed so that the sealed space is in a reduced pressure state.

  According to such a configuration, the first double tuning fork vibrating piece and the second double tuning fork vibrating piece are installed in a sealed space in a reduced pressure state. As a result, it is possible to suppress the air resistance that hinders the vibration of the first double tuning fork vibrating piece and the second double tuning fork vibrating piece, and to obtain stable vibration characteristics of the first double tuning fork vibrating piece and the second double tuning fork vibrating piece. It becomes possible. Therefore, it is possible to detect pressure with higher accuracy.

  Application Example 5 In the pressure sensor according to the application example, the case portion, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are the same. It is preferably formed of quartz cut at a cut angle.

  According to such a configuration, the case portion, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are formed of crystal cut at the same cut angle. Yes. Accordingly, the linear expansion coefficients of the case portion, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are substantially equal. Therefore, even if the temperature of the environment in which the pressure sensor is installed changes, the case portion, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are substantially the same. Inflate or shrink at a ratio of. Therefore, it is possible to minimize the distortion generated between the components of the pressure sensor. Therefore, the pressure sensor can detect pressure while minimizing the influence of environmental temperature changes.

  Application Example 6 A pressure measurement device according to this application example includes the pressure sensor described above and a circuit unit having a function of at least driving and controlling the pressure sensor in the sealed space. And

  According to such a configuration, the pressure measuring device includes the pressure sensor and the circuit unit having a function of performing at least driving and control of the pressure sensor in the sealed space of the pressure sensor. Measurements from pressure detection to calculation can be performed.

  Application Example 7 A pressure measuring device according to this application example includes the pressure sensor described above and a circuit unit having a function of at least driving and controlling the pressure sensor outside the sealed space. And

  According to such a configuration, the pressure measuring device includes the pressure sensor and a circuit unit having a function of performing at least driving and control of the pressure sensor outside the sealed space of the pressure sensor. Measurements from pressure detection to calculation can be performed.

  Hereinafter, embodiments will be described with reference to the drawings. The drawings referred to in the following description are schematic views in which the vertical and horizontal scales of members or portions are different from actual ones for convenience of illustration.

(First embodiment)
Fig.1 (a) is a top view which shows the pressure sensor of 1st Embodiment, FIG.1 (b) is the sectional view on the AA line of the same figure (a). As shown in FIG. 1, the pressure sensor 1 includes a case portion 10, a first diaphragm portion 20, a first double tuning fork vibrating piece 40, a second diaphragm portion 30, and a second double tuning fork vibrating piece 50. The case portion 10, the first diaphragm portion 20, the first double tuning fork vibrating piece 40, the second diaphragm portion 30, and the second double tuning fork vibrating piece 50 are formed by a photolithography method, an etching method, or the like using a crystal plate. . The crystal plate is a Z plate cut out with the Z′-axis direction rotated by a predetermined angle around the X-axis of the crystal axis of the crystal as the thickness direction and the X-axis direction and the Y-axis direction as the plane directions.

  The case portion 10, the first diaphragm portion 20, and the second diaphragm portion 30 form a sealed space 90. Further, the first diaphragm portion 20 and the second diaphragm portion 30 are formed so as to face each other substantially in parallel. Further, the first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50 are formed so as to face each other substantially in parallel. Moreover, the case part 10 has the surrounding circumferential end surfaces 11 and 12 used as front-back relation, the through-hole 13, and the sealed sealing hole part 60. FIG. The first diaphragm portion 20 includes a first joint portion 21 joined to the entire circumference of the end surface 11 of the case portion 10, a first thin portion 22 formed inside the first joint portion 21, and a first thin portion 22. The first holding portion 23 formed inside the first holding portion 23 and the first central plate portion 24 which is formed inside the first holding portion 23 and is thinner than the thickness of the first holding portion 23. The first holding part 23 is formed at a symmetrical position with respect to the first center of gravity 25 of the first diaphragm part 20. The first double tuning fork vibrating piece 40 includes a first base 41 and first vibrating arms 43 and 44 formed between the first base 42. The first base portions 41 and 42 are joined to the locations 26 and 27 on the end face 12 side of the first holding portion 23. The first vibrating arm portions 43 and 44 straddle the first central plate portion 24 so as to pass a straight line L connecting the first centroid 25 and a second centroid 35 described later.

  The second diaphragm portion 30 includes a second joint portion 31 that is joined to the entire periphery of the end surface 12 of the case portion 10, a second thin portion 32 that is formed inside the second joint portion 31, and a second thin portion 32. The second holding portion 33 formed inside the second holding portion 33 and the second central plate portion 34 formed on the inner side of the second holding portion 33 and having a thickness smaller than the thickness of the second holding portion 33. The second holding portion 33 is formed at a symmetrical position with respect to the second center of gravity 35 of the second diaphragm portion 30. The second double tuning fork vibrating piece 50 includes second base portions 51 and 52 and second vibrating arm portions 53 and 54 formed between the second base portions 51 and 52. The second base portions 51 and 52 are joined to the locations 36 and 37 on the end face 11 side of the second holding portion 33. The second vibrating arm portions 53 and 54 straddle the second central plate portion 34 so as to pass through a straight line L connecting the first centroid 25 and the second centroid 35.

  Here, the 1st diaphragm part 20 and the 1st double tuning fork vibrating piece 40, the 2nd diaphragm part 30 and the 2nd double tuning fork vibrating piece 50 are joined by the epoxy-type adhesive agent. Moreover, the case part 10 and the 1st diaphragm part 20, and the case part 10 and the 2nd diaphragm part 30 are joined by the low melting glass. In addition, the sealed space 90 is depressurized after the above-described joining, and the sealed hole 60 is sealed by a melting method using an Au—Sn low melting point metal after depressurization. As a result, the sealing hole 60 becomes a sealing portion, and the sealed space 90 is maintained in a reduced pressure state.

  With reference to FIGS. 2 and 3, the configuration of the electrode of the double tuning fork vibrating piece and the outline of the vibration form will be described by taking the first double tuning fork vibrating piece 40 as an example. FIG. 2 is a schematic view showing the configuration of the electrodes of the double tuning fork vibrating piece. FIG. 3 is a schematic view showing a vibration form of the double tuning fork vibrating piece.

  As shown in FIG. 2, excitation electrodes 71 as an example of electrode shapes for exciting the first vibrating arm portions 43, 44 are provided on the surfaces of the first vibrating arm portions 43, 44 of the first double tuning fork vibrating piece 40. , 72 are formed. The excitation electrode 71 includes electrodes 77 provided on the upper surface and the lower surface of the central portion of the first vibrating arm portion 43, excitation electrodes 83 and 84 provided on the side surfaces of the central portion of the first vibrating arm portion 43, and the first The electrodes 73 and 74 provided on the upper and lower surfaces of the portion of the vibrating arm 43 close to the connection with the first base portions 41 and 42 (the portions on both sides of the excitation electrode 71), and the first of the first vibrating arm 43 The electrodes 79, 80, 81, and 82 are provided on the side surfaces of the portions close to the connection portions with the one base portions 41 and 42 (portions on both sides of the excitation electrode 71). The excitation electrode 72 includes electrodes 78 provided on the upper and lower surfaces of the central portion of the first vibrating arm portion 44, electrodes 89 and 92 provided on the side surfaces of the central portion of the first vibrating arm portion 44, and the first vibration. The electrodes 75 and 76 provided on the upper and lower surfaces of the portion close to the connection portion of the arm portion 44 with the first base portions 41 and 42 (the portions on both sides of the excitation electrode 72), and the first of the first vibrating arm portion 44. It is comprised from the electrodes 85-88 provided in the side surface of the part close | similar to the connection part with the base parts 41 and 42 (the part of the both sides of the excitation electrode 72).

  The vibration will be described with reference to FIG. First, as shown in FIG. 3B, a negative (−) potential is applied to the electrodes 73, 74, 83, and 84 constituting the excitation electrode 71, and a positive (+) potential is applied to the electrodes 77, 79, 80, 81, and 82. Apply. At the same time, a positive (+) potential is applied to the electrodes 75, 76, 89, 92 constituting the excitation electrode 72, and a negative (−) potential is applied to the electrodes 78, 85, 86, 87, 88. By applying such a potential, the first vibrating arm portions 43 and 44 that are in a substantially parallel state as shown in FIG. 3A are curved outward as shown in FIG. 3B. Bend.

  Subsequently, as shown in FIG. 3C, a potential opposite to the potential shown in FIG. 3B is applied to each electrode. That is, a positive (+) potential is applied to the electrodes 73, 74, 83, and 84 constituting the excitation electrode 71, and a negative (−) potential is applied to the electrodes 77, 79, 80, 81, and 82. At the same time, a negative (−) potential is applied to the electrodes 75, 76, 89, 92 constituting the excitation electrode 72, and a positive (+) potential is applied to the electrodes 78, 85, 86, 87, 88. By applying such a potential, the first vibrating arm portions 43 and 44 are bent so as to be curved inward as shown in FIG.

  By repeatedly applying the potentials shown in FIGS. 3B and 3C, the first vibrating arm portions 43 and 44 vibrate in the X direction at a predetermined resonance frequency. In the present embodiment, the first double tuning fork vibrating piece 40 formed so that the resonance frequency is about 40 KHz is used.

  As described above, the first double tuning fork vibrating piece 40 that vibrates at a predetermined resonance frequency (about 40 KHz) intersects the vibration direction of the first vibrating arm portions 43 and 44 (Y-axis direction shown in FIG. 2). The resonance frequency changes when a compressive force is applied to the tube or a tensile force is applied to the tube. More specifically, the resonance frequency of the first double tuning fork vibrating piece 40 decreases when a compressive force acts in a direction intersecting the vibration direction of the first vibrating arm portions 43 and 44, and conversely when a tensile force acts. Will increase. The change in the resonance frequency has a proportional relationship with the magnitude of the acting force.

  Next, the action of the inertia force generated by the acceleration received by the pressure sensor 1 on the inside of the pressure sensor 1 will be described with reference to FIG. Fig.4 (a) shows the AA sectional view of Fig.1 (a), and is explanatory drawing of the effect | action inside the pressure sensor of an inertial force.

  As shown in FIG. 4 (a), when the pressure sensor 1 receives the acceleration in the downward direction indicated by the arrow α, the inertial force generated by the acceleration is applied to the pressure sensor 1 by the arrow F in the direction opposite to the arrow α. Work in the direction. In the first diaphragm portion 20, the first thin portion 22 of the first diaphragm portion 20 is directly connected to the first joint portion 21 joined to the case portion 10, and since it has a thin wall thickness, an inertial force works, The first thin portion 22 is inclined with the contact point between the first thin portion 22 and the first joint portion 21 as a fulcrum. The first holding portion 23 formed on the first thin portion 22 as the first thin portion 22 tilts also tilts with the contact point between the first thin portion 22 and the first joint portion 21 as a fulcrum. When the first holding part 23 is tilted, the first holding part 23 is displaced and rotated around the center points 23a and 23b of the first holding part 23. The locations 26 and 27 of the first holding portion 23 where the first base portions 41 and 42 of the first double tuning fork vibrating piece 40 are joined are located at the positions sandwiching the first central plate portion 24 of the first diaphragm portion 20. The part 26 moves so as to rotate counterclockwise as indicated by the arrow R1, and the part 27 rotates clockwise as indicated by the arrow R2. Thus, the location 26 and the location 27 move so as to rotate in opposite directions. Since the locations 26 and 27 of the first holding portion 23 where the first base portions 41 and 42 of the first double tuning fork vibrating piece 40 are joined are separated by the rotation described above, the first double tuning fork vibrating piece 40 has the first vibration. A tensile force acts in a direction crossing the vibration direction of the arm portions 43 and 44.

  In addition, the inertial force and the rotational force act on the second diaphragm part 30 as well as the first diaphragm part 20. However, the position of the second double tuning fork vibrating piece 50 with respect to the second diaphragm portion 30 is exactly opposite to the position of the first double tuning fork vibrating piece 40 with respect to the first diaphragm portion 20. Therefore, a compressive force acts on the second double tuning fork vibrating piece 50 in a direction intersecting with the vibration direction of the second vibrating arm portions 53 and 54 of the second double tuning fork vibrating piece 50. As described above, when the inertial force generated by the acceleration acts on the pressure sensor 1, forces in opposite directions act on the first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50. When the pressure sensor 1 receives acceleration in the direction opposite to the direction of the arrow α shown in FIG. 4A, the inertial force generated by the acceleration, the rotation generated by the inertial force, the first double tuning fork vibrating piece 40 and The directions of the forces acting on the second double tuning fork vibrating piece 50 are all opposite directions.

  Next, the action of gravity on the pressure sensor 1 will be described with reference to FIG. FIG. 4B shows a cross section taken along the line AA of FIG. 1A and is an explanatory diagram of the action of gravity inside the pressure sensor. As shown in FIG. 4B, when gravity acts on the pressure sensor 1 in the direction of arrow Fg, the pressure sensor 1 obtains gravitational acceleration in the direction of arrow g by gravity. The action of gravity inside the pressure sensor 1 is the same as the theory of the action of the inertial force generated by the acceleration inside the pressure sensor 1 described above. The first double tuning fork vibrating piece 40 has a tensile force and the second double tuning fork vibrating piece. Compressive force acts on 50.

  Next, the action of the pressure outside the sealed space 90 on the inside of the pressure sensor 1 will be described with reference to FIG. FIG.4 (c) shows the AA line cross section of Fig.1 (a), and is explanatory drawing of the effect | action inside the pressure sensor of the pressure outside sealed space. Although the inertial force and the pressure outside the sealed space 90 are applied to the pressure sensor 1, the inertial force is not applied to the pressure sensor 1 in order to explain the action of only the pressure outside the sealed space 90 on the inside of the pressure sensor 1. Assume that Further, as an example, it is assumed that the pressure outside the sealed space 90 is larger than the pressure inside the sealed space 90.

  As shown in FIG. 4C, the pressure outside the sealed space 90 acts on the pressure sensor 1 in the directions indicated by the arrows P <b> 3 and P <b> 4 toward the center point 91 in the sealed space 90. An arrow P3 which is a direction of pressure outside the sealed space 90 acting on the first diaphragm portion 20 is the same direction as the arrow F of the direction of inertia force acting on the first diaphragm portion 20 described above. Therefore, the tensile force acts on the first double tuning fork vibrating piece 40 in the direction crossing the vibration direction of the first vibrating arm portions 43 and 44 in the same reason as when the inertial force is applied. On the other hand, the 2nd diaphragm part 30 is provided facing the 1st diaphragm part 20 so that the sealed space 90 may be pinched | interposed. The position of the second double tuning fork vibrating piece 50 with respect to the second diaphragm portion 30 is exactly opposite to the position of the first double tuning fork vibrating piece 40 with respect to the first diaphragm portion 20. Therefore, a tensile force acts on the second double tuning fork vibrating piece 50 in a direction intersecting with the vibration direction of the second vibrating arm portions 53 and 54. Thus, when the pressure outside the sealed space 90 acts on the pressure sensor 1, forces in the same direction act on the first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50.

  In the case where the pressure outside the sealed space 90 is smaller than the pressure inside the sealed space 90, the direction in which the pressure outside the sealed space 90 acts is the opposite direction of arrows P3 and P4 although not shown. Therefore, a compressive force acts on the first double tuning fork vibrating piece 40 in a direction intersecting with the vibration direction of the first vibrating arm portions 43 and 44, and the second double tuning fork vibrating piece 50 has the second vibrating arm portion 53. , 54 in a direction crossing the vibration direction.

  Next, detection of pressure will be described with reference to the drawings. FIG. 5 is an explanatory diagram of pressure detection. The horizontal axis indicates the force acting on the first double tuning fork vibrating piece 40 or the second double tuning fork vibrating piece 50 (the positive direction is the tensile force and the negative direction is the compressive force), and the vertical axis is the first double tuning fork vibrating piece. 40, or the resonance frequency of the second double tuning fork vibrating piece 50. Note that when the pressure is detected, the inertial force generated by the acceleration and the pressure outside the sealed space 90 both act on the inside of the pressure sensor 1. Therefore, as shown in FIG. 4A, due to the inertial force generated by the acceleration, a tensile force acts on the first double tuning fork vibrating piece and a compressive force acts on the second double tuning fork vibrating piece. As shown in c), an example of the case where the pressure outside the sealed space 90 acts in the directions of arrows P3 and P4 and a tensile force acts on the first and second double-fork vibrating pieces is as follows. Will be described.

As shown in FIG. 5, from the change Δfp ₁ of the resonance frequency of the first double tuning fork vibrating piece 40 due to the pressure Fp outside the sealed space 90 and the change Δfp ₂ of the resonance frequency of the second double tuning fork vibrating piece 50, The resonance frequency of the double tuning fork vibrating piece 40 and the resonance frequency of the second double tuning fork vibrating piece 50 are the resonance frequency fp. Further, as described above, the tensile force ΔF ₁ acts on the first double tuning fork vibrating piece 40 and the compressive force ΔF ₂ acts on the second double tuning fork vibrating piece 50 due to the inertial force generated by the acceleration. As a result, the resonance frequency of the first double tuning fork vibrating piece 40 changes by Δf _{1 and} the resonance frequency of the second double tuning fork vibrating piece 50 changes by Δf ₂ . Since the direction in which the tensile force ΔF ₁ acting on the first double tuning fork vibrating piece 40 and the compressive force ΔF ₂ acting on the second double tuning fork vibrating piece 50 act is opposite, the resonance frequency corresponding to each of them. The direction of change between the change Δf ₁ and the change Δf ₂ is opposite. Therefore, the change Δf ₁ of the resonance frequency of the first double tuning fork vibrating piece 40 and the change Δf ₂ of the resonance frequency of the second double tuning fork vibrating piece 50 can be offset. The change amount Δfp ₁ of the resonance frequency of the first double tuning fork vibrating piece 40 and the change amount Δfp ₂ of the resonance frequency of the second double tuning fork vibrating piece 50 due to the pressure Fp outside the latter sealed space 90 have the same direction of change. since it is match, it can be classified as variation Delta] f ₂ of the resonance frequency of the change in Delta] f ₁ and a second double-ended tuning fork vibrating piece 50 of the resonance frequency of the first double-ended tuning fork vibrating reed 40 in the inertial force resulting from the acceleration of the above. Therefore, the pressure is calculated from the sum (specifically, half the sum) of the resonance frequency (fp + Δf ₁ ) of the first double tuning fork vibrating piece 40 and the resonance frequency (fp−Δf ₂ ) of the second double tuning fork vibrating piece 50. The sensor 1 can obtain the pressure Fp outside the sealed space 90 by approximating it by removing the influence of acceleration.

In the first embodiment described above, the following effects are obtained.
(1) The direction of change between the change Δf ₁ of the resonance frequency of the first double tuning fork vibrating piece 40 due to the inertial force caused by the acceleration and the change Δf ₂ of the resonance frequency of the second double tuning fork vibrating piece 50 are opposite to each other. Therefore, it can be offset. The direction of change of the change Δfp ₁ of the resonance frequency of the first double tuning fork vibrating piece 40 due to the pressure Fp outside the sealed space 90 and the change Δfp ₂ of the resonance frequency of the second double tuning fork vibration piece 50 are the same. from can be divided and variation Delta] f ₂ of the resonance frequency of the change in Delta] f ₁ and a second double-ended tuning fork vibrating piece 50 of the resonance frequency of the first double-ended tuning fork vibrating reed 40 in the inertial force resulting from the acceleration of the above. Therefore, the pressure sensor 1 excludes the influence of acceleration from the half of the sum of the resonance frequency (fp + Δf ₁ ) of the first double tuning fork vibrating piece 40 and the resonance frequency (fp−Δf ₂ ) of the second double tuning fork vibrating piece 50. Thus, the pressure Fp outside the sealed space 90 can be detected. Therefore, the pressure sensor 1 can detect the pressure Fp by removing the influence of the acceleration in both the environment where the acceleration is constant and the environment where the acceleration changes.

  (2) Since the first diaphragm portion 20, the second diaphragm portion 30, the first double tuning fork vibrating piece 40, and the second double tuning fork vibrating piece 50 are formed so as to face each other substantially in parallel, the low The backed pressure sensor 1 can be realized. For example, when two pressure sensors of Patent Document 1 are used in the opposite direction, as a result, two sealed spaces are formed, which is larger than the present embodiment. Moreover, since the pressure sensor 1 of this embodiment only needs one sealed space, the effect of a manufacturing cost reduction and a yield improvement is acquired.

  (3) The first holding part 23 is formed at a symmetrical position with respect to the first center of gravity 25 of the first diaphragm part 20, and the second holding part 33 is at a symmetrical position with respect to the second center of gravity 35 of the second diaphragm part 30. Is formed. Further, the first vibrating arm portions 43 and 44 of the first double tuning fork vibrating piece 40 cross the first central plate portion 24 so as to pass through a straight line L connecting the first gravity center 25 and the second gravity center 35. . The second vibrating arm portions 53 and 54 of the second double tuning fork vibrating piece 50 cross the second central plate portion 34 so as to pass through the straight line L. Accordingly, the inertia force generated by the acceleration and the pressure Fp outside the sealed space 90 act on the first diaphragm portion 20, and the locations 26 and 27 of the first holding portion 23 of the first diaphragm portion 20 are directed in opposite directions. Move so that it rotates approximately the same. For this reason, a substantially uniform compressive force or tensile force acts on the first double tuning fork vibrating piece 40 in the Y direction. Since a substantially uniform compressive force or tensile force acts on the first double tuning fork vibrating piece 40, the resonance frequency of the first double tuning fork vibrating piece 40 after the change is stable. Further, the inertia force generated by the acceleration and the pressure Fp outside the sealed space 90 act on the second diaphragm portion 30, and the locations 36 and 37 of the second holding portion 33 of the second diaphragm portion 30 are substantially the same in the opposite directions. Move to rotate about. Therefore, a substantially uniform compressive force or tensile force acts on the second double tuning fork vibrating piece 50 in the Y direction. Since the substantially equal compressive force or tensile force acts on the second double tuning fork vibrating piece 50, the resonance frequency of the second double tuning fork vibrating piece 50 after the change is stable. Therefore, in any environment where the acceleration is constant and the environment where the acceleration changes, the pressure sensor 1 can detect the pressure Fp with high accuracy by excluding the influence of the acceleration.

  (4) The first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50 are installed in a sealed space 90 in a decompressed state. As a result, it is possible to suppress the air resistance that hinders the vibrations of the first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50 and to stabilize the first double tuning fork vibrating piece 40 and the second double tuning fork vibrating piece 50. Vibration characteristics can be obtained. Therefore, the pressure Fp can be detected with higher accuracy.

  (5) The case portion 10, the first diaphragm portion 20, the second diaphragm portion 30, the first double tuning fork vibrating piece 40, and the second double tuning fork vibrating piece 50 are formed of crystal cut at the same cut angle. Yes. As a result, the linear expansion coefficients of the case portion 10, the first diaphragm portion 20, the second diaphragm portion 30, the first double tuning fork vibrating piece 40, and the second double tuning fork vibrating piece 50 are equal. Therefore, even if the temperature of the environment in which the pressure sensor 1 is installed changes, the case portion 10, the first diaphragm portion 20, the second diaphragm portion 30, the first double tuning fork vibrating piece 40, and the second double tuning fork vibration. The pieces 50 expand or contract at substantially the same ratio. Therefore, the distortion generated between the components of the pressure sensor 1 can be minimized. Therefore, the pressure sensor 1 can detect the pressure Fp while minimizing the influence of environmental temperature changes.

(Second Embodiment)
In the present embodiment, description of the same content as the above-described embodiment will be omitted, and different content will be described. FIG. 6A is a plan view showing a pressure measuring device according to the second embodiment, and FIG. 6B is a cross-sectional view taken along the line BB of FIG. As shown in FIG. 6, the pressure measuring device 2 includes a pressure sensor 1 and a circuit unit 3. The circuit unit 3 is formed in the case unit 10 in the sealed space 90 and has a function of at least driving and controlling the pressure sensor 1. Note that a circuit pattern such as a metal wiring (not shown) is formed on the case portion 10, the first diaphragm portion 20, and the second diaphragm portion 30.

In the second embodiment described above, the following effects are obtained.
(6) Since the pressure measuring device 2 includes the pressure sensor 1 and the circuit unit 3 having a function of at least driving and controlling the pressure sensor 1 in the sealed space 90 of the pressure sensor 1, the pressure measuring device 2 Can perform measurement from detection to calculation of the pressure Fp.

(Third embodiment)
In the present embodiment, description of the same content as the above-described embodiment will be omitted, and different content will be described. FIG. 7 is a cross-sectional view showing a pressure measuring device according to the third embodiment. As shown in FIG. 7, the pressure measuring device 5 includes a pressure sensor 1, a circuit unit 3, and a mounting substrate 4. The circuit unit 3 has a function of at least driving and controlling the pressure sensor 1. Note that a circuit pattern such as metal wiring (not shown) is formed on the mounting substrate 4.

In the above-described third embodiment, the following effects can be obtained.
(7) Since the pressure measuring device 5 includes the pressure sensor 1 and the circuit unit 3 having a function of performing at least driving and control of the pressure sensor 1 outside the sealed space 90 of the pressure sensor 1, the pressure measuring device 5 Can perform measurement from detection to calculation of the pressure Fp.

(Comparative example)
In this comparative example, for comparison with the above-described embodiment, a conventional pressure sensor will be described. Here, a description of the same content as the above-described embodiment will be omitted, and a different content will be described. FIG. 8A is a plan view showing a pressure sensor of this comparative example, and FIG. 8B is a cross-sectional view taken along the line CC of FIG. 8A. As shown in FIG. 8, the pressure sensor 101 includes a case part 110, a diaphragm part 120, a first double tuning fork vibrating piece 140, a second double tuning fork vibrating piece 150, and a cover part 170. The cover part 170 is also formed by a photolithography method, an etching method, or the like using a quartz plate like the other constituent parts.

  The case part 110, the diaphragm part 120, and the cover part 170 form a sealed space 190. The case portion 110 includes a flat plate portion 111, a frame portion 112 formed on the outer periphery of the flat plate portion 111, and a sealed sealing hole portion 160 formed in the flat plate portion 111. The diaphragm portion 120 includes a joint portion 121 connected to the entire circumference of the frame portion 112, a thin portion 122 formed inside the joint portion 121, a holding portion 123 formed inside the thin portion 122, and a holding portion. A through-hole portion 124 formed inside 123 is provided. The first double tuning fork vibrating piece 140 is joined to the places 126 and 127 on the case part 110 side of the holding part 123. The second double tuning fork vibrating piece 150 is joined to the locations 128 and 129 of the holding portion 123 on the cover portion 170 side. In this way, the first double tuning fork vibrating piece 140 and the second double tuning fork vibrating piece 150 are joined to face each other substantially parallel with the center of gravity 125 sandwiched between the front and back of one diaphragm portion 120. The cover part 170 is joined to the portions 128 and 129 of the holding part 123 on the side opposite to the case part 110 so as to cover the second double tuning fork vibrating piece 150. Here, the diaphragm part 120 and the cover part 170 are joined by low melting glass.

  Next, the action of the inertia force generated by the acceleration received by the pressure sensor 101 on the inside of the pressure sensor 101 will be described with reference to FIG. FIG. 9A is a cross-sectional view taken along the line CC of FIG. 8A, and is an explanatory diagram of the action of inertia force inside the pressure sensor.

  As shown in FIG. 9A, when the pressure sensor 101 receives acceleration in the downward direction indicated by the arrow α, the inertial force generated by the acceleration is applied to the pressure sensor 101 by the arrow F in the direction opposite to the arrow α. Work in the direction. In the diaphragm part 120, the thin part 122 of the diaphragm part 120 is directly connected to the joint part 121 joined to the frame part 112, and is thin, so that the inertial force is applied, so that the thin part 122 is separated from the thin part 122. Inclining toward the cover 170 with the contact point with the joint 121 as a fulcrum. When the thin portion 122 is tilted, the holding portion 123 is also tilted, and the holding portion 123 is displaced and rotates around the center points 123a and 123b of the holding portion 123. Since the places 126 and 128 and the places 127 and 129 of the holding part 123 are at positions where the through-hole part 124 of the diaphragm part 120 is sandwiched, the places 126 and 128 are located in the counterclockwise direction indicated by the arrow R1 in the places 127 and 127. 129 moves to rotate clockwise as indicated by arrow R2. Thus, the locations 126 and 128 and the locations 127 and 129 move so as to rotate in opposite directions. Since the locations 128 and 129 of the holding portion 123 move away due to the rotation described above, the second double tuning fork vibrating piece 150 has a tensile force in a direction intersecting the vibration direction of the second vibrating arm portions 153 and 154 (see FIG. 8). Since the points 126 and 127 come close to each other, a compressive force is applied to the first double tuning fork vibrating piece 140 in a direction crossing the vibration direction of the first vibrating arm portions 143 and 144.

  Next, the action of gravity on the pressure sensor 101 will be described with reference to FIG. FIG. 9B shows a cross section taken along the line CC of FIG. 8A and is an explanatory diagram of the action of gravity inside the pressure sensor. As shown in FIG. 9B, when gravity acts on the pressure sensor 101 in the direction of arrow Fg, the pressure sensor 101 obtains gravitational acceleration in the direction of arrow g by gravity. The action of the gravity inside the pressure sensor 101 is the same as the reasoning of the action of the inertial force generated by the acceleration inside the acceleration sensor 101, and the first double tuning fork vibrating piece 140 has a tensile force and the second double tuning fork vibrating piece. A compression force acts on 150.

  Next, the action of the pressure Fp outside the sealed space 90 by the pressure sensor 1 on the inside of the pressure sensor 1 will be described with reference to FIG. FIG. 9C shows a cross section taken along the line CC of FIG. 8A, and is an explanatory view of the action of the pressure outside the sealed space inside the pressure sensor. Assume that no inertial force is applied to the pressure sensor 101. Further, as an example, it is assumed that the pressure Fp outside the sealed space 190 is larger than the pressure inside the sealed space 190.

  As shown in FIG. 9C, the pressure Fp outside the sealed space 190 acts on the pressure sensor 101 in the direction indicated by the arrow P <b> 5 so as to go into the sealed space 190. In the diaphragm portion 120, the thin portion 122 of the diaphragm portion 120 is directly connected to the joint portion 121 joined to the frame portion 112 and is thin, so that the thin portion 122 is caused by the pressure Fp outside the sealed space 190. Is inclined toward the case portion 110 with the contact point between the thin portion 122 and the joint portion 121 as a fulcrum. When the thin portion 122 is tilted, the holding portion 123 is also tilted, and the holding portion 123 is displaced and rotates around the center points 123a and 123b of the holding portion 123. Since the places 126 and 128 and the places 127 and 129 of the holding part 123 are at positions sandwiching the through-hole part 124 of the diaphragm part 120, the places 126 and 128 are located at the places 127 and 129 in the clockwise direction indicated by the arrow R3. Moves so as to rotate counterclockwise as indicated by arrow R4. Thus, the locations 126 and 128 and the locations 127 and 129 move so as to rotate in opposite directions. Since the locations 128 and 129 of the holding portion 123 approach each other due to the rotation described above, a compressive force acts on the second double tuning fork vibrating piece 150 in a direction that intersects the vibration direction of the second vibrating arm portions 153 and 154. Further, since the locations 126 and 127 are moved away from each other, a tensile force acts on the first double tuning fork vibrating piece 140 in a direction intersecting with the vibration direction of the first vibrating arm portions 143 and 144.

  When the pressure Fp outside the sealed space 190 is smaller than the pressure inside the sealed space 190, the direction in which the pressure Fp outside the sealed space 190 acts is the opposite direction of the arrow P5 although not shown. Therefore, a compressive force acts on the first double tuning fork vibrating piece 140 in a direction crossing the vibration direction of the first vibrating arm portions 143 and 144, and the second vibrating tuning fork vibrating piece 150 has the second vibrating arm portion 153. , 154, a tensile force acts in a direction crossing the vibration direction.

  When the pressure Fp is detected, the inertial force generated by the acceleration and the pressure Fp outside the sealed space 190 both act on the inside of the pressure sensor 101. A change in the resonance frequency (increase or decrease) of the first double tuning fork vibrating piece 140 due to an inertial force generated by the former acceleration, and a change in the resonance frequency (increase or decrease) of the second double tuning fork vibrating piece 150. Since the direction of the change is opposite, the amount of change in the resonance frequency of the first double tuning fork vibrating piece 140 and the amount of change in the resonance frequency of the second double tuning fork vibrating piece 150 are the pressures of the above-described embodiments. The offset can be made in the same manner as the sensor 1. However, the change in the resonance frequency of the first double tuning fork vibrating piece 140 due to the pressure Fp outside the sealed space 190 and the change in the resonance frequency of the second double tuning fork vibrating piece 150 are the pressure sensors of the above-described embodiment. Unlike 1, the direction of change does not match (the direction of change is the opposite). Therefore, it cannot be distinguished from the change in the resonance frequency of the first double tuning fork vibrating piece 140 and the change in the resonance frequency of the second double tuning fork vibrating piece 150 due to the inertial force generated by the acceleration described above. Therefore, the pressure sensor 101 cannot detect the pressure Fp without the influence of acceleration.

  In addition, the said embodiment is not limited to the above-mentioned content, In the range which does not deviate from the main point, it is possible to perform a various change other than the above-mentioned content. For example, the material of the case part 10, the first diaphragm part 20, the first double tuning fork vibrating piece 40, the second diaphragm part 30, and the second double tuning fork vibrating piece 50 is, for example, zinc oxide, lithium tantalate, zirconate titanate. Lead acid, lithium niobate and the like may be used.

  Further, the first holding part 23 may be a plurality of holding parts formed with the first central plate part 24 interposed therebetween, and the second holding part 33 is formed with the second central plate part 34 interposed therebetween. There may be a plurality of holding portions.

  Further, the first diaphragm portion 20 and the first double tuning fork vibrating piece 40, and the second diaphragm portion 30 and the second double tuning fork vibrating piece 50 are bonded with an acrylic, imide, urethane, polysulfone or other adhesive. It may be used.

  The sealing hole 60 may be sealed using a low melting point metal such as Au—Ge.

  Further, the sealing hole 60 may be formed in the first diaphragm portion 20 or the second diaphragm portion 30.

(A) is a top view which shows the pressure sensor of 1st Embodiment, (b) is the sectional view on the AA line of (a). Schematic which shows the structure of the electrode of a double tuning fork vibrating piece. Schematic which shows the vibration form of a double tuning fork vibrating piece. (A) shows the AA line cross section of Fig.1 (a), explanatory drawing of the effect | action inside the pressure sensor inside of an inertia force, (b) shows the AA line cross section of Fig.1 (a). Explanatory drawing of the effect | action to the inside of the pressure sensor of gravity, (c) shows the AA line cross section of Fig.1 (a), and is explanatory drawing of the effect | action inside the pressure sensor of the pressure outside sealed space. Explanatory drawing about the detection of a pressure. (A) is a top view which shows the pressure measuring device of 2nd Embodiment, (b) is the BB sectional drawing of (a). Sectional drawing which shows the pressure measuring device of 3rd Embodiment. (A) is a top view which shows the pressure sensor of a comparative example, (b) is CC sectional view taken on the line of (a). 8A is a cross-sectional view taken along the line C-C in FIG. 8A, and is an explanatory diagram of the action of inertia force inside the pressure sensor. FIG. 8B is a cross-sectional view taken along the line C-C in FIG. Explanatory drawing of the effect | action to the inside of the pressure sensor of gravity, (c) shows CC sectional view of FIG. 8 (a), and explanatory drawing of the effect | action inside the pressure sensor of the pressure outside sealed space.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Pressure sensor, 2, 5 ... Pressure measuring device, 3 ... Circuit part, 10 ... Case part, 11, 12 ... End surface, 13 ... Through-hole, 20 ... 1st diaphragm part, 21 ... 1st junction part, 22 ... 1st thin part, 23 ... 1st holding part, 24 ... 1st center board part, 25 ... 1st gravity center, 30 ... 2nd diaphragm part, 31 ... 2nd junction part, 32 ... 2nd thin part, 33 ... 1st 2 holding part, 34 ... second central plate part, 35 ... second center of gravity, 40 ... first double tuning fork vibrating piece, 41, 42 ... first base, 43, 44 ... first vibrating arm part, 50 ... second double Tuning fork vibrating piece, 51, 52 ... second base, 53, 54 ... second vibrating arm, 90 ... sealed space, L ... straight line.

Claims (7)

A case portion having opposing circumferential end faces and a through hole formed in the central portion;
A first joint part joined to the entire circumference of one end face of the case part, a first thin part formed inside the first joint part, and a first joint part formed inside the first thin part. A first diaphragm portion having one holding portion and a first central plate portion formed on the inner side of the first holding portion and having a thickness smaller than a thickness of the first holding portion;
A second joint part joined to the entire circumference of the other end surface of the case part; a second thin part formed inside the second joint part; and a second joint part formed inside the second thin part. A second diaphragm portion having two holding portions and a second central plate portion formed on the inner side of the second holding portion and having a thickness smaller than a thickness of the second holding portion;
A sealed space formed by the case portion and the first diaphragm portion and the second diaphragm portion formed to face each other;
Two first base parts joined to the sealed space side of the first holding part, and a pair of first vibrating arm parts formed between the two first base parts across the first central plate part A first double tuning fork vibrating piece facing the first diaphragm portion;
Two second base parts joined to the sealed space side of the second holding part, and a pair of second vibrating arm parts formed between the two second base parts across the second central plate part And a second double tuning fork vibrating piece facing the second diaphragm portion. The pressure sensor according to claim 1.
The first diaphragm part and the second diaphragm part facing each other are formed in parallel,
The pressure sensor, wherein the first double tuning fork vibrating piece and the second double tuning fork vibrating piece are formed to face each other in parallel. The pressure sensor according to claim 1 or 2,
The first holding part is formed at a symmetrical position with respect to the first center of gravity of the first diaphragm part,
The second holding part is formed at a symmetrical position with respect to the second center of gravity of the second diaphragm part,
A pair of the first vibrating arms of the first double tuning fork vibrating piece straddles the first central plate so as to pass through a straight line connecting the first center of gravity and the second center of gravity,
The pair of second vibrating arm portions of the second double tuning fork vibrating piece straddles the second central plate portion so as to pass through the straight line. The pressure sensor according to any one of claims 1 to 3,
The pressure sensor, wherein the sealed space is formed to be in a reduced pressure state. The pressure sensor according to any one of claims 1 to 4,
The case portion, the first diaphragm portion, the second diaphragm portion, the first double tuning fork vibrating piece, and the second double tuning fork vibrating piece are formed of crystal cut at the same cut angle. A featured pressure sensor. The pressure sensor according to any one of claims 1 to 5,
A pressure measuring apparatus comprising: a circuit unit having a function of at least driving and controlling the pressure sensor in the sealed space. The pressure sensor according to any one of claims 1 to 5,
A pressure measuring device comprising a circuit unit having a function of at least driving and controlling the pressure sensor outside the sealed space.

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