JP5025965B2 - Inertial sensor element - Google Patents

Description

  The present invention relates to an inertial sensor used for attitude control, position detection, camera shake correction, and the like of an aircraft, a ship, an automobile, and the like.

  There are various types of inertial sensors, but there is a vibration type angular velocity sensor that satisfies the requirement of being thin, small and lightweight for incorporation. A conventional vibration type inertial sensor detects a Coriolis force that works with rotation by vibrating a quadrangular prism.

  As an example of such a conventional inertial sensor, there is one using a tuning fork type vibration element (see Patent Document 1 or 2). There has also been proposed a vibration element including a plurality of support portions extending in a plane intersecting the rotation axis and a plurality of flexural vibration pieces supported at the tips of the nuclear support portions (Patent Document 3). See). According to the vibration element disclosed in Patent Document 2, the in-plane rotation speed can be detected, and the gyroscope can be made low-profile.

  On the other hand, multi-axiality is required for the degree of freedom of motion to be detected, and an angular velocity sensor that detects each component (angular velocity) of two or three axes that are orthogonal has been proposed. For example, when three axes are to be achieved by a vibration element, Coriolis force, which is an angular velocity detection principle, is generated for all three axes, so the element has at least two orthogonal components as drive displacements. There is a need. As a technique for realizing this, a method in which one inertial body element is circularly moved by orthogonal two-phase driving has been proposed (see Non-Patent Document 1).

Regarding the inertial sensor element as described above, the following prior art document information is disclosed.
JP-A-8-128833 JP-A-10-047970 JP-A-11-281372 Hideki Tamura, Toshiya Ichimura, Yoshiro Tomikawa “3-axis angular velocity detection gyro sensor by two-phase drive”, ultrasonic TECHNO, 2002.1-2, p. 6-13, (2002-01)

  The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.

  As described above, conventionally, by combining a plurality of vibration elements, two of the orthogonal space axes (for example, the two-dimensional X axis and the Y axis) or three axes (for example, the three-dimensional X axis, Since each component of the Y axis and the Z axis) is detected, there is a problem that the configuration of the multi-axis angular velocity sensor is complicated and it is complicated to create an element. In addition, in the method in which one inertial body element is circularly moved by orthogonal two-phase driving, it is difficult to give a uniform circular motion to the plate (vibrating element) of the piezoelectric vibration material, and the orthogonality with other axis signals is disturbed. There is a problem that separation of signals of different components is not easy.

  The present invention has been made to solve the above-described problems, and an inertial sensor element having a shape that can be easily formed can detect angular velocities in two or more of the spatial axis directions. The purpose is to do.

In order to solve the above-described problems, an inertial sensor element according to the present invention includes: a base; a first tuning fork vibration part having a prismatic first leg part and a second leg part extending from one side of the base part; A second tuning fork vibrating part having a prismatic third leg part and a fourth leg part extending from one side of the base part opposed to the first tuning fork vibrating part by 180 ° across the base part; A third tuning fork vibration part having a prismatic fifth leg part and a sixth leg part extending from one side of the base part at a position of 90 ° across the base part with respect to the tuning fork vibration part, The tuning fork vibrating portion is composed of a fourth tuning fork vibrating portion having a prismatic seventh leg portion and an eighth leg portion extending from one side of the base portion that is 180 ° opposite to the tuning fork vibrating portion. The tuning fork vibration part, the second tuning fork vibration part, the third tuning fork vibration part, and the fourth tuning fork vibration part are integrally formed of a piezoelectric material. The bending vibration is driven by the first excitation electrodes provided on the first leg and the second leg and the first excitation electrodes provided on the third leg and the fourth leg, respectively. The first detection electrode for detecting the first vibration caused by the rotation of the inertial sensor element around the Y axis in the direction in which the third leg portion and the fourth leg portion extend, the fifth leg portion, A second excitation electrode provided on each of the six legs, and a seventh leg and an eighth in a state where bending vibration is driven by the second excitation electrode provided on each of the seventh and eighth legs. And a second detection electrode for detecting a second vibration caused by the rotation of the inertial sensor element about the X axis of the plane on which the eight legs are disposed. It is also a sensor element.

In the inertial sensor element described above, the first leg, the second leg, the fifth leg, and the sixth leg are provided with through-holes passing through the principal surfaces in the X-axis direction extending in the leg length direction. The electrodes having the same electrical polarity are formed on the two side surfaces in the length direction of the through hole, and each of the electrodes formed so as to face each side surface in the through hole. The electrode on the outer side of the leg is also an inertial sensor element characterized in that an electrode having an electrical polarity different from that of the electrode formed on each side surface in the through hole is formed.

  As described above, the inertial sensor element of the present invention provides an excellent effect that the angular velocity in the spatial axis direction of two or more axes can be detected with one element having a simple shape.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view illustrating an example of an external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 2A and 2B are cross-sectional views taken along the virtual cutting lines shown in FIG. 1, respectively. FIG. 2A shows a virtual cutting line aa ′ and FIG. 2B shows a virtual cutting line bb. 2 (c) corresponds to the virtual cutting line cc 'and FIG. 2 (d) corresponds to the virtual cutting line dd'. In addition, each figure of drawing does not show a part of components or a structure for clarity of explanation. In particular, FIGS. 1, 4 and 6 do not show the electrodes formed on the surface of the inertial sensor element in order to clearly show the appearance of the inertial sensor element. In addition, each dimension in the drawings is partially exaggerated, and the same reference numerals denote the same objects in each figure.

  The inertial sensor element 100 shown in FIG. 1 is made of quartz as a constituent member, and extends from the base 101 to one side (extends in the Yl direction in FIG. 8) and is arranged with a first leg 102 and a second leg. The first tuning fork vibrating part 110 composed of the part 103 and the base part 101 are disposed so as to extend from the base part 101 in the opposite direction (extending in the Y′1 direction in FIG. 8). A second tuning fork vibrating portion 111 composed of a third leg portion 104 and a fourth leg portion 105, and 110 and a second tuning fork vibrating portion 111 are provided in the same main surface of the inertial sensor element 100. The fifth leg 106 (extending in the Y'3 direction in FIG. 8) and the sixth leg 107 (extending in the Y2 direction in FIG. 8) are provided on one of the two surfaces perpendicular to the two side surfaces of the base 101. The third tuning fork vibrating part 112 constituted by the seventh leg 108 (see FIG. 8) on the other side surface. And a fourth fork vibrating unit 113 consists Y'2 direction extending) and eighth leg 109 (extending in the Y3 direction in FIG. 8) of the. Each leg is formed in a prismatic shape. The inertial sensor element 100 is fixed (supported) to an external package or the like on the side surface of the base 101. Further, the component member of the element is not limited to the quartz crystal of the embodiment, and the inertial sensor element may be composed of other piezoelectric materials.

  The inertial sensor element 100 is formed by rotating from 0 ° to 15 ° with respect to the electrical axis and mechanical axis of the crystal crystal axis and cutting out from the crystal plate having the optical axis as a normal line. The azimuth line X1 in each figure is an axis rotated by a predetermined angle from the electrical axis, the azimuth line Y1 is an axis rotated by a predetermined angle from the mechanical axis, and the azimuth line Z is an axis substantially coincident with the optical axis.

  The inertial sensor element 100 is made of quartz, and the quartz has a three-fold symmetry structure with respect to the optical axis, so that the fifth leg 106 (Y′3 direction), the sixth leg 107 (Y2 direction), the first The seventh leg 108 (Y′2 direction) and the eighth leg 109 (Y3 direction) are formed by extending the first leg 102, the second leg 103, the third leg 104, and the fourth leg 105. The direction Y1-Y′1 extends in the direction rotated by 120 ° (Y2-Y′2) and the direction rotated by −120 degrees (Y3-Y′3). Further, the distal end portions of the fifth leg portion 106, the sixth leg portion 107, the seventh leg portion 108, and the eighth leg portion 109 further extend in a direction parallel to the X1 axis.

  That is, in the inertial sensor element 100, the fifth leg 106, the sixth leg 107, the seventh leg 108 and the eighth leg 109 depend on the symmetry of the crystal axis of the piezoelectric material forming the inertial sensor element 100. In the case of a crystal material that is three times symmetrical with respect to the axis in the thickness direction, the fifth leg portion 106 and the eighth leg portion 109 are the first leg portion 102, the second leg portion 103, the third leg portion, The leg 104 and the fourth leg 105 extend on a shaft rotated 120 degrees clockwise, and the sixth leg 107 and the seventh leg 108 are the first leg 102 and the second leg, respectively. 103, the third leg 104, and the fourth leg 105 extend on a shaft rotated 120 degrees counterclockwise. In addition, when the piezoelectric material forming the inertial sensor element 100 is a crystal material that is four times symmetrical with respect to the axis in the thickness direction, the fifth leg portion 106, the sixth leg portion 107, the seventh leg portion 108, and the The eight legs 109 extend in a direction perpendicular to the first leg 102, the second leg 103, the third leg 104, and the fourth leg 105.

  In addition, the central axis in the extending direction of the first leg portion 102 and the central axis in the extending direction of the third leg portion 104 coincide with each other, and the central axis in the extending direction of the second leg portion 103 and the fourth leg portion 105. The central axes in the extending direction coincide. In each leg portion configured in this manner, first, the first leg portion 102 is provided with Y-axis excitation electrodes 121, 122, 123, and 124, and the second leg portion 103 is provided with Y-axis excitation electrodes 131, 132, 133 and 134 are provided. The third leg 104 is provided with Y-axis detection electrodes 141, 142, 143, and 144, and the fourth leg 105 is provided with Y-axis detection electrodes 151, 152, 153, and 154. In addition, the fifth leg portion 106 is provided with X-axis excitation electrodes 161, 162, 163, and 164, and the sixth leg portion 107 is provided with X-axis excitation electrodes 171, 172, 173, and 174. The seventh leg portion 108 is provided with X-axis detection electrodes 181, 182, 183 and 184, and the eighth leg portion 109 is provided with X-axis detection electrodes 191, 192, 193 and 194.

  In the first leg 102 and the second leg 103, the Y-axis excitation electrodes 121, 123, 132, and 134 have the same electrical polarity (hereinafter referred to as the same polarity) and are connected to the Y-axis excitation terminal E11. The excitation electrodes 122, 124, 131 and 133 have the same polarity and are connected to the Y-axis excitation terminal E12. In the third leg 104 and the fourth leg 105, the Y-axis detection electrodes 141, 144, 152, and 153 have the same polarity and are connected to the Y-axis detection terminal E13, and the Y-axis detection electrodes 142, 143, 151, and 154 has the same polarity and is connected to the Y-axis detection terminal E14. In the fifth leg 106 and the sixth leg 107, the X-axis excitation electrodes 161, 163, 171 and 173 have the same polarity and are connected to the X-axis excitation terminal E15, and the X-axis excitation electrodes 162, 164, 172 and 174 has the same polarity and is connected to the X-axis excitation terminal E16. In the seventh leg portion 108 and the eighth leg portion 109, the X-axis detection electrodes 181, 184, 191 and 194 have the same polarity and are connected to the X-axis detection terminal E17, and the X-axis detection electrodes 182, 183, 192 and 193 has the same polarity and is connected to the X-axis detection terminal E18.

  In the inertial sensor element having such an electrode configuration, for example, as shown in FIG. 3, the Y-axis excitation terminal E11 and the Y-axis excitation terminal E12 are connected to the oscillation circuit 301. Bending vibration is driven by the second leg portion 103. The Y-axis detection terminal E13 and the Y-axis detection terminal E14 are connected to the differential amplifier circuit 302. A reference phase signal based on the drive frequency of the oscillation circuit 301 is output from the phase circuit 303.

  Detection signals generated based on the angular velocity to be measured are input to the differential amplifier circuit 302, respectively. The input detection signal is amplified by the differential amplifier circuit 302 and output to the synchronous detection circuit 304. The synchronous detection circuit 304 uses the output signal of the phase circuit 303 as a reference, synchronously detects the detection signal input by the differential amplifier circuit 302, and outputs it as an angular velocity signal.

  In the inertial sensor element shown in FIG. 1, when excitation signals are applied to the first leg 102 and the second leg 103 by the Y-axis excitation electrodes 121, 122, 123, 124, 131, 132, 133 and 134, Due to the inverse piezoelectric effect, the first leg 102 and the second leg 103 cause bending vibration (excitation) in the XY plane. Here, even if the first leg 102 and the second leg 103 cause bending vibration, the third leg 104 and the fourth leg 105 do not cause bending vibration. In this state of excitation, if distortion due to the Coriolis force of rotational movement about the Y axis is applied to the inertial sensor element 100 of FIG. 1, the third leg 104 and the fourth leg 105 are Y The bending vibration is caused in the −Z plane, and the charges proportional to the distortion (angular velocity) of the bending vibration are detected by the Y-axis detection electrodes 141, 142, 143, 144, 151, 152, 153 and 154. (Piezoelectric effect).

  Therefore, if the electric signals detected by the Y-axis detection electrodes 141, 142, 143, 144, 151, 152, 153 and 154 are processed by a circuit as shown in FIG. It is possible to obtain the magnitude of the angular velocity of the rotational motion with the rotation axis. Further, the direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal.

  Similarly, when an excitation signal is applied to the fifth leg 106 and the sixth leg 107 by the X-axis excitation electrodes 161, 162, 163, 164, 171, 172, 173 and 174, the fifth leg 106 The sixth leg 107 causes bending vibration (excitation) in the XY plane. Here, even if the fifth leg portion 106 and the sixth leg portion 107 cause bending vibration, the seventh leg portion 108 and the eighth leg portion 109 do not cause bending vibration. In this state of excitation, when distortion due to the Coriolis force of the rotational motion about the X axis is applied to the inertial sensor element 100 of FIG. 1, the seventh leg 108 and the eighth leg 109 are X The bending vibration is caused in the −Z plane, and the charges proportional to the distortion (angular velocity) of the bending vibration are detected by the X-axis detection electrodes 181, 182, 183, 184, 191, 192, 193 and 194. (Piezoelectric effect).

  Therefore, if the electric signals detected by the X-axis detection electrodes 181, 182, 183, 184, 191, 192, 193 and 194 are processed by a circuit as shown in FIG. It is possible to obtain the magnitude of the angular velocity of the rotational motion with the rotation axis. Further, the direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal. As described above, according to the inertial sensor element 100 shown in FIG. 1, the angular velocity in the two-axis directions of the Y-axis and the X-axis can be detected.

Further, in the inertial sensor element 100 shown in FIG. 1, the outer dimensions of the first leg portion 102 and the second leg portion 103, the outer dimensions of the third leg portion 104 and the fourth leg portion 105, or the fifth leg portion 106. The outer dimensions of the sixth leg 107 and the outer dimensions of the seventh leg 108 and the eighth leg 109 are different from each other. In addition, the frequency of the excitation signal applied to the first leg 102 and the second leg 103 by the Y-axis excitation electrodes 121, 122, 123, 124, 131, 132, 133 and 134, and the X-axis excitation electrode 161 , 162, 163, 164, 171, 172, 173 and 174, the frequencies of the excitation signals applied to the fifth leg 106 and the sixth leg 107 are different. The frequency Fs of the excitation signal applied to each leg is expressed by the following equation: “Fs = kf × λ2 × (leg width) ÷ (leg length) 2” (kf is a frequency constant, λ is a boundary condition) Just decide. In this way, the dimensions of the legs are in different states, and excitation signals of different frequencies are applied to the legs to be excited by different excitation electrodes corresponding to different axial directions, so that each excitation electrode in each axial direction Between the excitation tuning fork vibrating part constituted by each leg formed with each of the legs and the detection tuning fork vibrating part constituted by each said leg formed with each detection electrode forming a pair with this excitation tuning fork vibrating part . The resonance frequency is different for each axial direction, and each vibration caused by the rotation about the different axis can be detected in a more accurately distinguished state.

  Next, another embodiment of the inertial sensor element according to the present invention will be described. FIG. 4 is a perspective view illustrating an example of the external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 5A and 5B are cross-sectional views taken along the virtual cutting lines shown in FIG. 4. FIG. 5A is a virtual cutting line ee ′, and FIG. 2B is a virtual cutting line ff. 2 (c) corresponds to the virtual cutting line gg 'and FIG. 2 (d) corresponds to the virtual cutting line hh'. The inertial sensor element 400 shown in FIG. 4 is made of quartz as a constituent member, and extends from the base 401 to one side (extends in the Yl direction in FIG. 8) and is arranged with a first leg 402 and a second leg. 411 composed of a portion 403 and a third leg portion 404 arranged to extend from the base 101 in the direction opposite to 411 across the base 401 (extend in the Y′1 direction in FIG. 8). And a fourth leg 405, and a second leg constituted by a third leg 404 and a ninth leg 406 extending in parallel with the fourth leg 405 between the third leg 404 and the fourth leg. The tuning fork vibrating part 412 is provided on the same main surface of the inertial sensor element 400, and one of two surfaces perpendicular to the two side surfaces of the base 401 provided with the 411 and the second tuning fork vibrating part 412 is provided on the first surface. 5 leg portions 407 (extending in Y′3 direction in FIG. 8) and 6 leg portions 408 (Y2 direction in FIG. 8) The third tuning fork vibrating part 413 composed of an extension) has a seventh leg 409 (extending in the direction Y'2 in FIG. 8) and an eighth leg 410 (in FIG. 8) on the other side. And a fourth tuning fork vibrating portion 414 configured to extend in the Y3 direction). Each leg is formed in a prismatic shape.

  The inertial sensor element 400 is formed by rotating from 0 ° to 15 ° with respect to the electrical axis and mechanical axis of the crystal crystal axis and cutting out from the crystal plate having the optical axis as a normal line. The azimuth line X1 in each figure is an axis rotated by a predetermined angle from the electrical axis, the azimuth line Y1 is an axis rotated by a predetermined angle from the mechanical axis, and the azimuth line Z is an axis substantially coincident with the optical axis.

  In the inertial sensor element, the fifth leg 407, the sixth leg 408, the seventh leg 409, and the eighth leg 410 depend on the symmetry of the crystal axis of the piezoelectric material forming the inertial sensor element, In the case of a crystal material that is three-fold symmetric with respect to the axis in the thickness direction, the fifth leg 407 and the eighth leg 410 have a first leg 402, a second leg 403, a third leg 404, The fourth leg portion 405 and the ninth leg portion 406 extend on an axis rotated clockwise by 120 degrees, and the sixth leg portion 408 and the seventh leg portion 409 are the first leg portion 402 and the second leg portion 409, respectively. The leg portion 403, the third leg portion 404, the fourth leg portion 405, and the ninth leg portion 406 extend on an axis rotated 120 degrees counterclockwise. If the piezoelectric material forming the inertial sensor element is a crystal material that is four times symmetrical with respect to the axis in the thickness direction, the fifth to eighth legs are the first leg 402, the second leg 403, The third leg portion 404, the fourth leg portion 405, and the ninth leg portion 406 extend in a perpendicular direction.

  The central axis of the extending direction of the first leg 402 and the central axis of the extending direction of the third leg 404 coincide with each other, and the central axis of the extending direction of the second leg 403 and the extending of the fourth leg 405 are aligned. The central axes of direction coincide. The ninth leg 406 is disposed at the center between the third leg 404 and the fifth leg 405. In each of the legs configured as described above, in the inertial sensor element shown in FIG. 4, first, the first leg 402 is provided with Y-axis excitation electrodes 421, 422, 423, and 424, and the second leg 403. Are provided with Y-axis detection electrodes 431, 432, 433 and 434. The third leg 404 is provided with Z-axis excitation electrodes 441, 442, 443 and 444, and the fourth leg 405 is provided with Z-axis excitation electrodes 451, 452, 453 and 454. 406 includes Z-axis detection electrodes 461, 462, 463, and 464, the fifth leg 407 includes X-axis excitation electrodes 471, 472, 473, and 474, and the sixth leg 408 includes X-axis detection electrodes. Excitation electrodes 481, 482, 483 and 484 are provided, the seventh leg 409 has X-axis detection electrodes 491, 492, 493 and 494, and the eighth leg 410 has X-axis detection electrodes 411, 412, and 494. 413 and 414 are provided.

  In the first leg 402, the Y-axis excitation electrodes 421 and 423 have the same polarity, and the Y-axis excitation electrodes 422 and 424 have the same polarity. On the other hand, in the second leg 403, the Y-axis detection electrodes 431 and 434 have the same polarity, and the Y-axis detection electrodes 432 and 433 have the same polarity. In the third leg 404 and the fourth leg 405, the Z-axis excitation electrodes 441, 443, 452, and 454 have the same polarity, and the Z-axis excitation electrodes 442, 444, 451, and 453 have the same polarity. Yes. On the other hand, in the ninth leg 406, the Z-axis detection electrodes 461 and 463 have the same polarity, and the Z-axis detection electrodes 463 and 464 have the same polarity. In the fifth leg 407 and the sixth leg 408, the X-axis excitation electrodes 471, 473, 481, and 483 have the same polarity, and the X-axis excitation electrodes 472, 474, 482, and 484 have the same polarity. ing. On the other hand, in the seventh leg portion 409 and the eighth leg portion 410, the X-axis detection electrodes 491, 494, 415, 418 have the same polarity, and the X-axis detection electrodes 492, 493, 416, 417 have the same polarity. ing.

  In the inertial sensor element 400 shown in FIG. 4, excitation signals are applied to the Y-axis excitation electrodes 421, 422, 423, and 424 to excite the first leg portion 402 and the second leg portion 403. In this state, if the electric signals detected by the Y-axis detection electrodes 431, 432, 433, and 434 are detected as angular velocity signals, the magnitude of the angular velocity of the rotational motion with the Y axis as the rotation axis can be obtained. Further, the direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal.

  Further, excitation signals are applied to the Z-axis excitation electrodes 441, 442, 443, 444, 451, 452, 453, and 454 to excite the third leg 404 and the fourth leg 405. In this state, if the electrical signals detected by the Z-axis detection electrodes 461, 462, 463, and 464 are detected as angular velocity signals, the magnitude of the angular velocity of the rotational motion with the Z axis as the rotation axis can be obtained. The direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal.

  Further, excitation signals are applied to the X-axis excitation electrodes 471, 472, 473, 474, 481, 482, 483, and 484 to excite the fifth leg 407 and the sixth leg 408. In this state, if the electrical signals detected by the X-axis detection electrodes 491, 492, 493, 494, 415, 416, 417 and 418 are detected as angular velocity signals, the angular velocity of the rotational motion with the X axis as the rotational axis can be detected. The size can be determined. The direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal. According to the inertial sensor element 400 shown in FIG. 4, the angular velocities in the directions of the three axes of the X axis, the Y axis, and the Z axis can be detected.

  Next, another embodiment of the present invention will be described. FIG. 6 is a perspective view illustrating an example of an external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 7A and 7B are cross-sectional views taken along the virtual cutting lines shown in FIG. 6, respectively. FIG. 7A shows a virtual cutting line ii ′, and FIG. 2B shows a virtual cutting line j-j. 2 (c) corresponds to the virtual cutting line kk ′ and FIG. 2 (d) corresponds to the virtual cutting line mm ′. An inertial sensor element 600 shown in FIG. 6 extends in the length direction of the leg at the base of each leg 102, 103, 106, 107 of the inertial sensor element 100 shown in FIG. It is a structure provided with a hole penetrating between both main surfaces. The inertial sensor element 600 is made of quartz and is made up of a first leg 602 and a second leg 603 arranged to extend from the base 601 to one side (extend in the Yl direction in FIG. 8). 614 and the third leg portion 604 and the fourth leg portion 605 disposed so as to extend from the base portion 601 in the opposite direction (extending in the Y′1 direction in FIG. 8) across the base portion 601. And a second tuning fork vibrating part 615 composed of the following, and in the same main surface of the inertial sensor element 600, and perpendicularly intersects two side surfaces of the base 601 provided with the 614 and the second tuning fork vibrating part 615. A third tuning fork comprising a fifth leg 606 (extending in the Y′3 direction in FIG. 8) and a sixth leg 607 (extending in the Y2 direction in FIG. 8) on one of the two side surfaces of The vibrating portion 616 is arranged on the other side with a seventh leg portion 608 (extending in the Y′2 direction in FIG. 8) and And a fourth fork vibrating portion 617 consists of 8 legs 609 (extending in the Y3 direction in FIG. 8). Each leg portion is formed in a prismatic shape. A through hole 610 is formed at the root portion of the first leg portion 602, a through hole 611 is formed at the root portion of the second leg portion 603, and the fifth leg portion 606 is formed. The base portion has a through hole 612 and the sixth leg portion 607 has a structure having a through hole 613 at the root portion.

  In each leg portion configured as described above, the Y-axis excitation electrodes 621, 622, 633, and 634 have the same polarity, and the Y-axis excitation electrodes 623, 624, 631, and 632 have the same polarity. The Y-axis detection electrodes 641, 644, 652, and 653 have the same polarity, and the Y-axis detection electrodes 642, 643, 651, and 654 have the same polarity. The X-axis excitation electrodes 661, 662, 671, and 672 have the same polarity, and the X-axis excitation electrodes 663, 664, 673, and 674 have the same polarity. The X-axis detection electrodes 681, 684, 691 and 694 have the same polarity, and the X-axis detection electrodes 682, 683, 692 and 693 have the same polarity.

  In the inertial sensor element 600 shown in FIG. 6, excitation signals are applied to the Y-axis excitation electrodes 621, 622, 623, 624, 631, 632, 633 and 634, and the first leg 602 and the second leg 603 are applied. Exciting. By providing through holes 610 and 611 at the base portions of the first leg 602 and the second leg 603 and configuring the electrodes as described above and shown in FIG. 7A, an electric field is generated in parallel with the electric axis direction. Since the electric field can be distributed over the entire range of the excitation legs, the electric field can be efficiently applied. Therefore, the equivalent series resistance Rl is small, the Q value is high, and the angular velocity detection sensitivity is high. An inertial sensor element can be obtained. In this state, if the electrical signals detected by the Y-axis detection electrodes 641, 642, 643, 644, 651, 652, 653 and 654 are detected as angular velocity signals, the angular velocity of the rotational motion with the Y axis as the rotational axis can be detected. The size can be determined. Further, the direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal.

  Further, an excitation signal is applied to the X-axis excitation electrodes 661, 662, 663, 664, 671, 672, 673, and 674, and the fifth leg 606 and the sixth leg 607 are excited. Also in this case, similarly, by providing the through holes 612 and 613 in the root portions of the fifth leg portion 606 and the sixth leg portion 607, the same action as the first leg portion 602 and the second leg portion 603 is achieved. Thus, an inertial sensor element having a small equivalent series resistance Rl, a high Q value, and a large angular velocity detection sensitivity can be obtained. If the electrical signals detected by the X-axis detection electrodes 681, 682, 683, 684, 691, 692, 693, and 694 are detected as angular velocity signals, the magnitude of the angular velocity of the rotational motion with the X axis as the rotational axis is obtained. be able to. The direction in which the angular velocity is generated can be detected by comparing the polarity of the detected charge with the phase of the excitation signal. According to the inertial sensor element shown in FIG. 6, the angular velocities in the two spatial axis directions of the X axis and the Y axis can be detected.

  In each of the embodiments described above, the form of the inertial sensor element that can detect the inertial forces (angular velocities) in the two spatial axis directions of the X axis and the Y axis has been disclosed. However, the present invention is disclosed in the form disclosed in the above examples. It is obvious that the present invention includes an inertial sensor element that can detect inertial forces (angular velocities) in the three spatial axis directions of the X axis, the Y axis, and the Z axis. Various changes and improvements can be made without departing from the scope of the present invention.

FIG. 1 is a perspective view illustrating an example of an external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 2A and 2B are cross-sectional views taken along the virtual cutting lines shown in FIG. 1, respectively. FIG. 2A shows a virtual cutting line aa ′ and FIG. 2B shows a virtual cutting line b-. FIG. 2C corresponds to the virtual cutting line cc ′, and FIG. 2D corresponds to the virtual cutting line dd ′. FIG. 3 is a block diagram showing a circuit configuration example for angular velocity detection in the inertial sensor element according to the present invention. FIG. 4 is a perspective view illustrating an example of an external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 5A and 5B are cross-sectional views taken along the virtual cutting lines shown in FIG. 4. FIG. 5A shows a virtual cutting line ee ′, and FIG. 2B shows a virtual cutting line f−. 2 (c) corresponds to the virtual cutting line gg ', and FIG. 2 (d) corresponds to the virtual cutting line hh'. FIG. 6 is a perspective view illustrating an example of an external configuration of an inertial sensor element according to the present invention, illustrating an angular velocity sensor element that is one of the inertial sensor elements. 7A and 7B are cross-sectional views taken along the virtual cutting lines shown in FIG. 6, respectively. FIG. 7A shows a virtual cutting line ii ′ and FIG. 2B shows a virtual cutting line j-. FIG. 2C corresponds to the virtual cutting line kk ′, and FIG. 2D corresponds to the virtual cutting line mm ′. FIG. 8 is a crystal orientation diagram showing the symmetry of the crystal in the plane perpendicular to the optical axis of the crystal in the inertial sensor element of this example.

Explanation of symbols

100, 400, 600 ... inertial sensor elements 101, 401, 601 ... base 102, 402, 602 ... first leg 103, 403, 603 ... second leg 104, 404, 604 .. Third leg 105, 405, 605 ... Fourth leg 106, 407, 606 ... Fifth leg 107, 408, 607 ... Sixth leg 108, 409, 608 ... 7th leg 109, 410, 609 ... 8th leg 406 ... 9th leg 110, 411, 614 ... 1st tuning fork vibrating part 111, 412, 615 ... 2nd tuning fork Vibration part 112,413,616 ... 3rd tuning fork vibration part 113,414,617 ... 4th tuning fork vibration part 121,122,123,124,131,132,133,134,421,422 423,424,4 1,442,443,444,451,452,453,454,471,472,473,474,481,482,483,484,621,622,623,624,631,632,633,634,661 662,663,664,671,672,673,674 ... Excitation electrode 141,142,143,144,151,152,153,154,431,432,433,434,461,462,463,464 491,492,493,494,415,416,417,418,641,642,643,644,651,652,653,654,681,682,683,684,691,692,693,694 ... Detection electrode 610, 611, 612, 613 ... through hole

Claims (2)

A base, a first tuning fork vibrating part having a prismatic first leg and a second leg extending from one side of the base, and a 180 ° sandwiching the base with respect to the first tuning fork vibrating part A second tuning-fork vibration part having a prismatic third leg part and a fourth leg part extending from one side of the base part facing each other, and a 90 ° position with the base part sandwiched between the first tuning-fork vibration part; A third tuning fork vibrating portion having a prismatic fifth leg portion and a sixth leg portion extending from one side of the base portion, and opposite to the third tuning fork vibrating portion by 180 ° across the base portion And a fourth tuning fork vibrating portion having a prismatic seventh leg portion and an eighth leg portion extending from one side of the base portion, the base portion, the first tuning fork vibrating portion, and the second tuning fork vibrating portion. , The third tuning fork vibrating part and the fourth tuning fork vibrating part are integrally formed of a piezoelectric material,
Bending vibration is driven by the first excitation electrodes provided on the first leg and the second leg, respectively, and the first excitation electrodes provided on the third leg and the fourth leg, respectively. A first detection electrode for detecting a first vibration caused by rotation of the inertial sensor element about the Y axis in a direction in which the third leg and the fourth leg extend in a state where the third leg and the fourth leg extend. A second excitation electrode provided on each of the fifth leg portion and the sixth leg portion; and a flexural vibration driven by the second excitation electrode provided on the seventh leg portion and the eighth leg portion, respectively. A second detection electrode for detecting a second vibration caused by rotation of the inertial sensor element about the X axis of the plane on which the seventh leg portion and the eighth leg portion are disposed inertial sensor element characterized that you have provided and. 2. The inertial sensor element according to claim 1 , wherein the first leg, the second leg, the fifth leg, and the sixth leg penetrate through the main surface in the X-axis direction extending in the leg length direction. Electrodes having the same electric polarity are formed on two side surfaces in the longitudinal direction in the through hole, and are opposed to the respective side surfaces in the through hole. An inertial sensor element , wherein the electrodes on the outer side surfaces of the legs formed in this way are formed with electrodes having different electrical polarities from the electrodes formed on the side surfaces in the through holes .

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